Note: Descriptions are shown in the official language in which they were submitted.
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SPRAY DEVICE HAVING AN ADJUSTMENT MEMBER FOR NEEDLE VALVE OPENING RANGE
[TECHNICAL FIELD]
[0001] The present invention relates to a spray device for
spraying paint onto an object to be coated. More
specifically, the present invention relates to a spray
device wherein the needle can move in the axial direction.
The present invention further relates to a spray device
which can spray not only paint but also various kinds of
liquids, including water, adhesives, rust prevention agents,
insulating agents, coating agents and drugs onto an object
to be sprayed, and which is provided with a manual
adjustment member (adjustment knob).
[PRIOR ART]
[0002] With plate-type automatic guns, which are spray
devices for spraying paint onto an object to be coated, one
or more of these guns are normally arranged on a coating
line as automatic spray guns for coating. There are many
kinds of line, such as suspended- or floor-type conveyors,
and there are also lines in which the conveyor speed is
fixed and cyclical-type lines. Furthermore, the objects to
be coated may be moved individually, the objects to be
coated may be caused to rotate, a plurality of objects to be
coated may be suspended from the same hanger, or a plurality
of objects to be coated may be lined up in a circular
fashion and rotated on a cyclical-type line.
[0003] The method of arranging automatic spray guns may
involve a fixed system, robots may be made to hold the
automatic spray guns, one or more automatic spray guns may
be mounted on a device known as a "reciprocating engine"
which moves vertically or longitudinally (from front to
back) on the same straight line, or the above configurations
may be combined.
[0004] The actual user normally handles a range of objects
to be coated, and objects to be coated which are the same
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are often divided up for coating with many different colors.
It is also known that there are various shapes and sizes of
objects to be coated.
[0005] The coating involves a primer or a base coat, and use
is made of diverse coatings such as single-color coatings
known as solid coatings, metallic coatings (normally
aluminum powder), pearl coatings, mica coatings, beads
(glass) coatings, clear (transparent) coatings, and color-
clear (colored transparent) coatings. The solvent may be
solvent-based, of the high-solid-type (with a small
proportion of solvent) or water-based, etc. Many different
kinds of resin may be used, such as melamine, fluorine,
acrylic or urethane. The coating process may involve an
undercoat, middle coat and top coat, and such processes
entail various steps and requirements.
[0006] For example, a first conventional type of system has
a configuration in which a spray gun is provided with a
remote control-type displacement mechanism allowing a
stopper to be displaced between two preset positions, and
the degree of opening of the discharge orifice can be
remotely controlled in two stages, namely fully open and
half open (see Patent Document 1).
[0007] A second conventional type of system has a
configuration in which a first rear end striking position of
a needle valve is momentarily lowered to a second rear end
striking position of the needle valve by releasing the drive
force of a cylinder, and accumulated matter inside an
ejection flow path is discharged, after which the cylinder
is driven to instantly return to the first rear end striking
position of the needle valve, whereby the initial set amount
of coating is restored. The position of the end part when
the cylinder piston has advanced is adjusted by a piston
forward-end adjustment screw (see Patent Document 2).
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[0008] In a third conventional type of system, a spray
device is provided with a gun unit for atomizing paint for
ejection, and a bracket unit for receiving paint and air.
The bracket unit is detachably fixed to the gun unit. Paint
is ejected from a paint ejection orifice by movement of a
nozzle open/close valve to the rear (see Patent Document 3).
[0009] A fourth conventional type of system has a
configuration in which the rear end of a needle valve in a
spray gun is fixed by a screw to a first piston which is
disposed at the rear, and a second piston is disposed in
front of the first piston. Compressed air is supplied to a
first air supply passage which causes the first piston to
move, or compressed air is supplied to a second air supply
passage which causes the second piston to move, so that the
amount of movement of the needle valve is changed and
varying amounts of discharge are produced (see Patent
Document 4).
[0010] In a fifth conventional type of system, a first
controlling member which can be adjusted to the front and
rear by a screw is provided on a cylinder end cover. The tip
end of the first controlling member is made to respond to a
spring receiving member. A second controlling member which
can be adjusted from the outside by a screw is linked by a
screw and provided in the spring receiving member (see
Patent Document 5).
[0011] In a sixth conventional type of system, a first
controlling member which can be adjusted to the front and
rear by a screw is provided on a cylinder end cover. The tip
end of the first controlling member is made to respond to a
spring receiving member. A second controlling member which
can be adjusted from the outside by a screw is linked by a
screw and provided in the spring receiving member (see
Patent Document 6).
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[0012] In a seventh conventional type of system, an
open/close valve with a flow rate control function is
provided with a long spring and a short spring as reverting
springs. Increases and reductions in the pilot air pressure
are used to open a needle valve body in stages, thereby
adjusting the flow rate (see Patent Document 7).
[0013] In an eighth conventional type of system, a needle
valve body in a needle valve for supplying paint is switched
between a small flow passage open position and a large flow
passage open position (see Patent Document 8).
[0014] A ninth conventional type of system has a
configuration in which, in a needle valve for a spray gun, a
second piston is displaced to a locking position provided at
a first piston by pumping air to a second cylinder chamber
so that a paint discharge orifice is half-opened. The first
piston is displaced along with the second piston by pumping
air to a first cylinder chamber so that the paint discharge
orifice is fully opened (see Patent Document 9).
[PRIOR ART DOCUMENTS]
[0015]
[Patent Document 1] Japanese Unexamined Patent Application
Publication S59-62360
[Patent Document 2] Japanese Unexamined Patent Application
Publication 2003-205258
[Patent Document 3] Japanese Unexamined Patent Application
Publication 2008-649
[Patent Document 4] Japanese Unexamined Patent Application
Publication 2008-12404
[Patent Document 5] Japanese Examined Utility Model
Application Publication S63-38929
[Patent Document 6] Japanese Unexamined Utility Model
Application Publication S60-13264
[Patent Document 7] Japanese Unexamined Utility Model
Application Publication H5-71547
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[Patent Document 8] Japanese Examined Utility Model
Application Publication H3-36779
[Patent Document 9] Japanese Examined Utility Model
Application Publication S48-14667
[SUMMARY OF THE INVENTION]
[0016] Looking at the above, frequent changes of color and
cleaning operations are anticipated with spray devices, and
it is desirable for such changes of color and cleaning to be
carried out quickly and reliably in an automatic manner.
When the spray guns in conventional spray coating devices
are overhauled, it is necessary to remove the nozzle from
the spray gun body. A further point with conventional spray
coating devices is that the piston members and body members
have a complex structure, which means that production and
assembly require a large amount of time.
[0017] Looking at Figure 19, a conventional adjust type
spray coating device 900 has a gun body 910 and a rear body
930. A fluid tip 912, a needle 914, and a front piston 916
are disposed in the gun body 910. The front piston 916 is
urged forward by means of a spring 918. A front piston seal
920 closes off (seals) the front piston 916 and the gun body
910. -
[0018] The degree of opening (clearance) of the fluid tip
912 and the needle 914 can be adjusted by means of an
adjustment knob 932 and a lock nut 934 which are disposed at
the rear. With this spray coating device 900, coating is
carried out with the degree of opening of the needle 914
during coating being set to a position in which the
adjustment knob 932, which is the adjustment member, is
rotated to 1.5 from fully open, or to a position in which
the adjustment knob 932 is rotated to 2.0 from fully open.
When a change of color is required for the object being
coated on the coating line, a cleaning process is carried
out, and the coating apparatus (spray coating device) is
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filled with paint of a different color than the color of
paint which was being coated until that point. At such
times, when the degree of opening (clearance) of the fluid
tip 912 and the needle 914 is narrow, the cleaning (use of
solvent) is time consuming and leads to production losses
and therefore the adjustment knob is often adjusted for a
time during cleaning to the fully open position, in other
words to a position in which it has been rotated to 4.0 or
5Ø
[0019] The problem in this case is that once the cleaning
process has been completed, the degree of opening
(clearance) of the fluid tip 912 and the needle 914 needs to
be returned to the original state, but the conventional
adjustment knob 932 employs a spring system, and the
adjustment knob 932 has a structure which is fixed by means
of the lock nut 934, and therefore it is difficult to
reliably adjust the adjustment knob 932 to its original
position, and the adjustment is time consuming. If the
adjustment knob 932 is wrongly adjusted, the amount of paint
sprayed from the spray coating device 900 fluctuates, and
there is a risk of coating defects occurring.
[0020] The aim of the present invention is to provide a
spray device in which coating operations when the nozzle of
the spray device is being cleaned can be carried out
effectively, and in which the time needed to change paint is
shortened and the device can deal with painting operations
involving a large number of colors.
A further aim of the present invention is to provide a spray
device which makes it possible to adjust the amount of paint
ejected simply and in a short time.
A further aim of the present invention is to provide a spray
device which can be easily produced and assembled.
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A further aim of the present invention is to provide a spray
device which can be easily realized with any of the
conventional adjust type, air-type two-stage-pull type and
manual multiple-stage type structures.
[0021] The present invention concerns a spray device for
spraying paint from a paint ejection orifice, which is
provided with: a nozzle having a paint ejection orifice for
atomizing and ejecting paint; a needle for opening and
closing the paint ejection orifice; a front piston which is
fixed to the needle; a needle spring which is provided so as
to push the front piston toward the paint ejection orifice;
a gun body which accommodates the nozzle and accommodates
the front piston; a rear body which is disposed to the rear
of the gun body; a needle position adjustment mechanism for
adjusting the position of the needle in a direction along
the center axis of the nozzle; and a bracket unit which is
detachably fixed to the gun body.
[0022] When the bracket unit is fixed to the gun body, the
paint and air contained in the bracket unit flow through the
gun body. The needle position adjustment mechanism includes
an adjustment member which is rotatable with the center axis
of the nozzle at the center, and a rotation position setting
member for setting the position of the front piston along
the center axis of the nozzle in correspondence to the angle
of rotation of the adjustment member.
[0023] The needle
position adjustment mechanism is
configued that when the front piston moves together with
the needle along the center axis of the nozzle in a
direction away from the paint ejection orifice in a state
in which the amount of discharge paint exiting the paint
ejection orifice is set, the front piston and the needle
come together and the needle moves away from the paint
ejection orifice to open the orifice. The spray device
having this configuration is simple to disassemble,
assemble, maintain, and the components on the
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gun body side are simple to replace. With the spray device
according to the present invention, the amount of paint
discharged can be easily adjusted, and the nozzle can be
effectively cleaned.
[0024] With the spray device according to the present
invention, the needle position adjustment mechanism includes
an adjustment knob which is rotatable with the center axis
of the nozzle at the center, and a rotational stopper for
setting the position of the front piston along the center
axis of the nozzle in correspondence to the angle of
rotation of the adjustment member. The outer peripheral part
of the cylindrical section of the front piston is slidably
disposed within the inner peripheral part of the cylindrical
section of the rotational stopper.
[0025] With the spray device according to the present
invention, a plurality of counterbored holes are formed in
the rotational stopper, and a rotational stopper positioning
pin is provided in the rear body; and the rotational stopper
positioning pin can be positioned in the counterbored holes
by moving the adjustment knob in the direction along the
center axis of the nozzle and causing the rotation of the
adjustment knob.
[0026] The spray device according to the present invention
can also be used in a fixed system; it can also be used in a
system in which a robot is made to hold an automatic spray
gun; it can be used in a system in which one or more
automatic spray guns are mounted on a device known as a
"reciprocating engine"; or it may be used in a system
combining the above configurations.
[0027] When coating operations are carried out with the
spray device according to the present invention, the needle
position adjustment mechanism is used to cause the
adjustment member to rotate with the center axis of the
nozzle at the center, so that the position of the front
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piston along the center axis of the nozzle is set in the
coating operation position. Front piston operating air is
then sent to the gun unit from a supply source for front
piston operating air, and the needle is moved back and paint
is ejected from the paint ejection orifice. At this point,
atomized air is introduced from an atomized air supply
source, and atomized air is ejected from an atomized air
orifice so that the paint which has been ejected from the
paint ejection orifice can be atomized. Also at this point,
pattern air is introduced from a pattern air supply source
and the pattern air is ejected from a pattern air orifice so
that a pattern of atomized paint can be formed. The
remaining paint which has not been ejected from the paint
ejection orifice can be returned to the paint supply source
(or paint tank). It is possible to construct a paint
circulation line in this way.
[0028] When metal powder or the like is contained in the
paint, as with metallic paints, then if the paint circuit
remains closed for a long time, the heavier content tends to
settle (precipitate), and there is a risk of painting
defects and clogging of the paint circuit. In such cases
therefore, a circulating-type structure is preferred. It is
also possible to adopt a non-circulating-type configuration
which does not have a return path. The spray device
according to the present invention may also be used to
automatically or manually spray not just paint, but various
kinds of liquids, including water, adhesives, rust
prevention agents, insulating agents, coating agents and
drugs.
[0029] When the nozzle of the spray gun body in the spray
device according to the present invention is cleaned, the
needle position adjustment mechanism is used to cause the
adjustment member to rotate with the center axis of the
nozzle at the center so that the position of the front
piston along the center axis of the nozzle is set in the
cleaning operation position. While front piston operating
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air is introduced from a supply source for front piston
operating air into a front piston operating chamber, a state
is maintained in which the needle and the front piston come
together and move backward along the center axis of the
nozzle in resistance to the spring force of the needle
spring. The nozzle can be cleaned in this state.
[EFFECTS OF THE INVENTION]
[0030] With the spray device according to the present
invention, it is possible to set the amount by which the
needle can move backward from the closed nozzle state to the
cleaning state to be sufficiently large. This means that the
cleaning operation when the nozzle of the spray device is
cleaned can be carried out efficiently, and the downtime of
the coating operations can be shortened. Furthermore, with
the spray device according to the present invention, the
time required for changing the paint can be shortened, and
it is possible to deal with painting operations involving a
large number of colors. Furthermore, the spray device
according to the present invention has a detachable unitary
structure, and therefore it is simple to produce and
assemble each of the components making up the unit.
[0031] Furthermore, the spray device according to the
present invention has the configuration described above, and
therefore the cleaning time is significantly reduced and
enhanced performance can be achieved in terms of
significantly improved operating efficiency, among other
things, compared with a conventional spray device. With
conventional spray devices, it is necessary to open a manual
knob when "fully open" is required. Consequently, in most
cases when the needle position is to be returned to the
original position, the readjustment needs to be carried out
manually and depends on the feeling and vision of the
operator.
[0032] In addition, the spray device according to the
present invention can be easily realized with any of the
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three types of conventional spray devices, namely adjust
type, air-type two-stage-pull type and manual multiple-stage
type spray devices. By introducing spray devices such as
these three types, each user of the spray device can select
the type of spray device to match the type of line, the
state of equipment, color changes in objects to be coated
(products), and type of paint used etc., and it is also
possible to use several types of spray device conjointly.
That is to say, it is possible to increase the value of the
objects to be coated by means of a synergistic effect
achieved by using three types of spray device, making it
possible to achieve a distinction with standard products and
making it possible to anticipate ease in selling the
products.
[0033] In addition, with a manual multiple-stage type spray
device according to the present invention, there is one less
air circuit than with an air-type two-stage-pull type spray
device (the same as with a conventional adjust type spray
device), and therefore when a conventional adjust type spray
device is being used, it is possible to replace this with a
manual multiple-stage type spray device according to the
present invention without adding an air circuit.
[BRIEF DESCRIPTION OF THE FIGURES]
[0034] [Figure 1] is a view in longitudinal section showing
the structure of a spray device in the closed nozzle state,
in accordance with a mode of embodiment of the present
invention;
[Figure 2] is a front view showing the structure of the gun
unit, in accordance with a mode of embodiment of the present
invention;
[Figure 3] is a side view showing the structure of the spray
device, in accordance with a mode of embodiment of the
present invention;
[Figure 4] is a back view showing the structure of the gun
unit, in accordance with a mode of embodiment of the present
invention;
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[Figure 5] is a back view showing the structure of the gun
unit and the bracket unit, in accordance with a mode of
embodiment of the present invention;
[Figure 6] is a view in longitudinal section showing a
structure containing the flow passage of the spray device,
in accordance with a mode of embodiment of the present
invention;
[Figure 7] is a schematic in cross section showing the
arrangement of the flow passages of the spray device, in
accordance with a mode of embodiment of the present
invention;
[Figure 8] is an exploded assembly drawing showing the
structure of the rear body, rotational stopper and
adjustment knob, in accordance with a mode of embodiment of
the present invention;
[Figure 9] shows the structure of the rear body, rotational
stopper and adjustment knob, in accordance with a mode of
embodiment of the present invention, where Figure 9(a) is a
front view, Figure 9(b) is a cross-sectional view, Figure
9(c) is a side view, and Figure 9(d) is a back view;
[Figure 10] is an oblique view showing the structure of the
rotational stopper, in accordance with a mode of embodiment
of the present invention;
[Figure 11] shows the structure of the rotational stopper,
in accordance with a mode of embodiment of the present
invention, where Figure 11(a) is a front view, Figure 11(b)
is a cross-sectional view, Figure 11(c) is a side view, and
Figure 11(d) is a back view;
[Figure 12] shows the structure of the adjustment knob, in
accordance with a mode of embodiment of the present
invention, where Figure 12(a) is a front view of the
adjustment knob, Figure 12(b) is a cross-sectional view of
the adjustment knob, Figure 12(c) is a side view of the
adjustment knob, and Figure 12(d) is a back view of the
adjustment knob;
[Figure 13] is a view in longitudinal section showing the
structure of the spray device in the state of the first
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discharge amount of the nozzle, in accordance with a mode of
embodiment of the present invention;
[Figure 14] is a view in longitudinal section showing the
structure of the spray device in the state of the second
discharge amount of the nozzle, in accordance with a mode of
embodiment of the present invention;
[Figure 15] is a view in longitudinal section showing the
structure of the spray device in the state of the third
discharge amount of the nozzle (nozzle cleaning state), in
accordance with a mode of embodiment of the present
invention;
[Figure 16] is a view in longitudinal section showing the
structure of the spray device in a state in which the nozzle
is closed when an air-type two-stage-pull type spray device
is configured using the gun unit according to the present
invention;
[Figure 17] is a view in longitudinal section showing the
structure of the spray device with the nozzle in a first
open state when an air-type two-stage-pull type spray device
is configured using the gun unit according to the present
invention;
[Figure 18] is a view in longitudinal section showing the
structure of the spray device with the nozzle in a second
open state (nozzle cleaning state) when an air-type two-
stage-pull type spray device is configured using the gun
unit according to the present invention; and
[Figure 19] is a view in longitudinal section showing the
structure of the spray device in a state in which the nozzle
is closed in a conventional adjust type spray device;
[MODE OF EMBODIMENT OF THE INVENTION]
[0035] (1) Configuration of the spray device:
A mode of embodiment of the present invention will be
described below in conjunction with the figures. The mode of
embodiment of the present invention described below relates
to a spray device for spraying paint onto an object, but it
should be noted that the spray device according to the
present invention can be widely applied, not only to paint,
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but also to various kinds of liquids, including water,
liquid-type adhesives, liquid-type rust prevention agents,
liquid-type insulating agents, liquid-type coating agents
and liquid-type drugs.
[0036] The spray device according to the present invention
may be referred to as a "manual two-stage-pull type" spray
device, but in this instance "two-stage pull" means both an
arbitrary position (pull-back of the needle) and the CLEAN
position. The spray device according to the present
invention therefore relates to a "manual multiple-stage
type" spray device in which the needle can be set in a
plurality of positions. The mode of embodiment of the spray
device according to the present invention which will be
described below relates to a spray device in which the
needle can be set in three positions (a position in which a
first discharge amount can be ejected, a position in which a
second discharge amount can be ejected, and a cleaning
position), but it should be noted that the spray device
according to the present invention can equally be applied to
a spray device in which the needle can be set in two
positions, or it can be applied to a spray device in which
the needle can be set in three or more positions (a position
in which a first discharge amount can be ejected, a position
in which a second discharge amount can be ejected, ... , a
position in which an Nth discharge amount can be ejected,
and a cleaning position).
[0037] Looking at Figures 1 to 3, showing a mode of
embodiment of the present invention, a spray device 400 for
spraying paint onto an object to be coated from a paint
ejection orifice of a nozzle is provided with a gun unit 110
for atomizing and ejecting paint, a bracket unit 210 which
constitutes a manifold for receiving paint and air, and a
rear body 420. The bracket unit 210 is designed so that it
can be detachably fixed to the gun unit 110 by using a unit
fixing device such as a bolt 220 with a hexagonal hole. For
example, the bracket unit 210 is disposed on one face of the
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gun unit 110. The rear body 420 is disposed to the rear of
the gun unit 110.
[0038] (2) Configuration of the gun unit:
Looking at Figures 1 to 4, the gun unit 110 is provided with
a gun body 112 which constitutes a base member; a nozzle 114
which is supported in front of the gun body 112; an air cap
120 which is supported in front of the nozzle 114; a
retaining ring 128 which supports the air cap 120 on the gun
body 112; and the rear body 420 which is disposed to the
rear of the gun body 112. The gun body 112 is preferably
formed from engineering plastic which is rigid and resistant
to solvents.
[0039] The gun body 112 is formed from POM
(polyoxymethylene), for example. The rear body 420 is
preferably formed from POM (polyoxymethylene), for example.
POM (polyoxymethylene) is resistant to solvents and can cope
with aqueous systems. This structure makes it possible to
reduce the weight of the gun body 112. If several spray
devices are mounted on a robot or a reciprocating engine,
there may be limitations on the loading weight (loading
capacity) or the range of operation, in which case it is
necessary to reduce the weight of the gun body 112.
Moreover, if there is no need to reduce the weight, it is
possible to use a conventional article made of aluminum
(alumite treated), stainless steel or heat-treated stainless
steel.
[0040] A guide pin 112P for guiding the bracket unit 210 is
provided on the lower surface of the gun body 112. A female
thread part 112F for screwing tight the bolt 220 with a
hexagonal hole which fixes the bracket unit 210 is provided
on the lower surface of the gun body 112. Only one guide pin
1122 is depicted, but two guide pins 1122 are preferably
provided. There may be one guide pin 1122, or there may be
two.
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[0041] Here, the terms "front" and "in front" refer to the
direction in which paint is ejected from the gun unit 110.
Furthermore, "rear" and "behind" refer to the opposite
direction to the direction in which paint is ejected from
the gun unit 110.
[0042] The nozzle 114 has a cylindrical shape and dictates
the center axis 114A of the nozzle. The nozzle 114 includes
a nozzle body 114B and a nozzle tip 1140. The tip end of the
nozzle tip 114C has a tapered shape. The nozzle tip 1140 is
preferably formed from tungsten alloy. The nozzle body 114B
is supported on the gun body 112 by means of a first
threaded strengthening ring 115 and a second threaded
strengthening ring 116. A first stop pin 117 positions the
second threaded strengthening ring 116 on the gun body 112.
The first threaded strengthening ring 115 is positioned
further forward than and to the outside of the second
threaded strengthening ring 116. The first threaded
strengthening ring 115 is preferably fixed to the gun body
112 by secure fastening using a pin (not depicted).
Heliserts (commercially available threaded strengthening
components) are preferably used for the threaded part of the
gun body 112.
[0043] Looking at Figures 1 and 2, a paint ejection orifice
122 for ejecting paint is provided at the tip end of the
nozzle tip 1140. The inside of the nozzle 114 is designed to
allow the flow of liquid paint. The air cap 120 has an
auxiliary atomized air orifice 124. The tip end of the
nozzle 114 is disposed inside the nozzle orifice of the air
cap 120. The center axis of the paint ejection orifice 122
lies on the center axis 114A of the nozzle. The center of
the nozzle orifice of the air cap 120 lies on the center
axis 114A of the nozzle. Provision is made for a pattern air
orifice 126 for ejecting air in order to form a pattern with
the paint which has been atomized and ejected from the paint
ejection orifice 122. A plurality of pattern air orifices
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126 are preferably concentrically disposed with the center
axis 114A of the nozzle at the center.
[0044] A plurality of auxiliary atomized air orifices 124
are preferably concentrically disposed with the center axis
114A of the nozzle at the center. Alternatively, a plurality
of auxiliary atomized air orifices 124 may be concentrically
disposed around a first radius with the center axis 114A of
the nozzle at the center, and they may also be
concentrically disposed around another radius other than the
first radius (second radius or second and third radii etc.)
with the center axis 114A of the nozzle at the center.
[0045] Looking at Figure 1, the gun unit 110 is provided
with a nozzle open/close valve, i.e. a needle 150, for
opening and closing the paint ejection orifice 122; a needle
seal kit 160 which is disposed inside the gun body 112 and
supports the needle 150; and a front piston 170 which is
disposed to the rear of the needle seal kit 160 inside the
gun body 112. The needle seal kit 160 is disposed to the
rear of the nozzle 114. The needle 150 includes a needle tip
1500 which is positioned at the front, and a needle main
body 1503 which is positioned at the rear. The rear part of
the needle tip 1500 is fixedly fitted into the front part of
the needle main body 150B. The center axis of the needle tip
1500 lies on the center axis 114A of the nozzle. The center
axis of the needle main body 1503 lies on the center axis
114A of the nozzle. Accordingly, the center axis of the
needle 150 lies on the center axis 114A of the nozzle.
[0046] The needle tip 1500 is preferably formed from
tungsten alloy. The needle main body 150B is preferably
formed from stainless steel (SUS304, for instance) and
preferably undergoes a hard chromium treatment. By forming
the needle tip 1500 from tungsten alloy it is possible to
significantly improve durability compared with conventional
components which are formed from SUS303. This constitution
makes it possible to prevent spitting caused by wear (in
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other words a defect which is one kind of coating problem
caused by leakage of liquid from the tip end of the nozzle).
At the same time, this constitution makes it possible to
simplify maintenance of the needle 150 and to postpone the
time when the needle 150 needs replacing. In addition, if
the needle main body 150B undergoes a hard chromium
treatment, it is possible to avoid problems caused by
leakage of liquid from the needle seal part due to wear of
the needle main body 150B, and this makes it possible to
simplify maintenance of the needle 150 and to postpone the
time when the needle 150 needs replacing.
[0047] A third threaded strengthening ring 142 is fixed to
the gun body 112 by means of a third threaded strengthening
ring stop pin 140. The third threaded strengthening ring 142
has a female thread part for fixing the needle seal kit 160
by screwing. The needle seal kit 160 has a male thread part
so that it can be fixed by screwing. By screwing the male
thread part of the needle seal kit 160 into the female
thread part of the third threaded strengthening ring 142 it
is possible to detachably fix the needle seal kit 160 to the
gun body 112.
[0048] The needle seal kit 160 includes: a collar 160A; a
seal stopper 160B positioned to the rear; a first general
seal 1600; a seal housing 160D; a first 0-ring 160E; a
second general seal 160F; a second 0-ring 160G; and a front
seal 160H positioned at the front. The center axis of the
needle seal kit 160 lies on the center axis 114A of the
nozzle. The second 0-ring 160G is positioned further forward
than the first 0-ring 160E. The second general seal 160F is
positioned further forward than the first general seal 1600.
The second general seal 160F is held inwardly in front of
the seal housing 160D by means of the front seal 160H. The
first general seal 1600 is held inwardly to the rear of the
seal housing 160D by means of the seal stopper 160B. The
seal stopper 160B is held inwardly to the rear of the seal
housing 160D by means of the collar 160A. The second general
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seal 160F and the first general seal 160C are provided in
order to seal the seal housing 160D and the needle main body
150B. The first 0-ring 160E and the second 0-ring 160G are
provided in order to seal the seal housing 160D and the gun
body 112.
[0049] The first 0-ring 160E and the second 0-ring 160G are
preferably perfluoro 0-rings. Rubber-based materials
generally have low resistance to solvents and there is a
large possibility of deformation and expansion. When the
product is mainly to be applied to coating and solvents are
used for overhauling and maintenance, perfluoro is
preferably used in order to avoid problems in terms of not
being able to assemble the 0-rings or the 0-rings not
moving.
[0050] The needle seal kit 1.60 has a structure such that it
can be replaced by removing it as a single piece, and
therefore maintenance of the gun is simplified. Two V seals
which are used in the needle seal kit 160 have low
resistance to sliding and therefore serve to prevent leakage=
of liquid caused by friction with the needle main body 150B
and to improve durability. The front seal 160H is a
component which doubles the front V seal function (the
liquid . sealing function), and the sliding resistance
(sealing state) thereof can be adjusted using the clamping
state of the needle seal kit 160. Accordingly, the structure
of the front seal 160H is such that when it is worn, a
liquid sealing function is demonstrated by increasing the
amount of clamping thereof. That is to say, the needle seal
kit 160 is clamped and the tip end of the front seal 160H is
flattened whereby a liquid sealing function is demonstrated.
[0051] The two 0-rings on the outer side of the needle
seal kit 160, in other words the first 0-ring 160E and the
second 0-ring 160G, are such that the front-side of second
0-ring 160G demonstrates a liquid (paint) sealing function,
and the rear-side of first 0-ring 160E demonstrates
an air sealing function
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with the gun body 112. Accordingly, this configuration makes
it possible to significantly improve the durability of the
needle seal kit 160, to simplify maintenance of the needle
seal kit 160 and to postpone the time when the needle seal
kit 160 needs replacing.
[0052] The front piston 170 is provided so as to be able to
move along the center axis 114A of the nozzle. The front
piston 170 is disposed to the rear of the needle seal kit
160. The front piston 170 includes a front piston shaft
170A, a front piston flange 170F which is provided in front
of the front piston shaft 170A, and a front piston seal
receiving part 170G which is provided at the outer periphery
of the front piston flange 170F. A front piston hole 170H is
provided in front of the front piston shaft 170A. A rear
shaft part 150D which is provided to the rear of the needle
main body 150B is fitted into the front piston hole 170H and
fixedly attached therein.
[0053] A front piston seal 1700 is disposed inside a groove
in the front piston seal receiving part 170G. The front
piston seal 1700 is provided in order to seal a front piston
main body 170B and the gun body 112. The front piston seal
1700 is preferably made from perfluoro. This constitution
makes it possible to reduce sliding resistance and improve
durability.
[0054] The front piston main body 170B may be formed from
aluminum alloy A2021 (alumite treatment may be carried out,
for example). A front piston operating chamber 176 is
configured inside the gun body 112, in front of the front
piston 170.
[0055] A needle spring 174 is provided in order to push the
front piston main body 1703 forward. The needle spring 174
may be formed by a coil spring made of stainless steel
(SUS304, for instance). The needle spring 174 is disposed to
the outer side of a rear shaft part 170D of the front piston
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main body 170B. The rear section of the needle spring 174 is
disposed so as to come into contact with a planar section
facing the front of a rotational stopper 450 (to be
described later). The front section of the needle spring 174
is disposed so as to come into contact with a section facing
the rear of the front piston flange 170F of the front piston
main body 170B. The center axis of the needle spring 174 may
lie on the center axis 114A of the nozzle. The front piston
170 is subjected to force in a forward-moving direction by
means of the elastic force of the needle spring 174.
Accordingly, when compressed air is not introduced into the
front piston operating chamber 176, the front piston 170
moves forward and the needle tip 1500 of the needle 150 is
designed to close off the paint ejection orifice 122.
[0056] Looking at Figures 1 and 4, the rear body 420 is
fixed to the rear end of the gun body 112 by screw
fastening, using rear body fixing bolts 192A, 192B. As
depicted, the rear body 420 can be fixed to the gun body 112
using two rear body fixing bolts 192A, 192B, for example.
The two rear body fixing bolts 192A, 192B may be disposed
symmetrically about a point such that there is an angular
interval therebetween of 1800 with the center axis 114A of
the nozzle at the center. There may be one, or two or more
rear body fixing bolts. When several rear body fixing bolts
are used, said rear body fixing bolts may be disposed such
that there is an equal angular interval therebetween with
the center axis 114A of the nozzle at the center.
[0057] The gun unit 110 is also provided with an adjustment
knob 430 which' constitutes the adjustment member for
adjusting the position of the needle 150 along the center
axis 114A of the nozzle, and a rotational stopper 450 for
determining the position of the adjustment knob 430 in the
direction of rotation. The adjustment knob 430 is designed
to be able to rotate with the center axis 114A of the nozzle
at the center. The adjustment knob 430 is disposed to the
rear of the rear body 420.
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[0058] Looking at Figures 8 and 9, the rear body 420
includes a base part 422, an annular front recess 424 which
is formed on the front side of the base part 422, and an
annular rear projection 426 which is formed on the rear side
of the base part 422. Two screw holes 426A, 426B are formed
in the base part 422. Two bolts holes 420A, 420B may be
provided at positions which are symmetrical about a point
such that there is an angular interval therebetween of 180
with the center axis 114A of the nozzle at the center. A
rear body center hole 420H is formed in the base part 422
with the center axis 114A of the nozzle at the center. The
two screw holes 426A, 426B may be symmetrically disposed
about a point such that there is an angular interval
therebetween of 180 with the center axis 114A of the nozzle
at the center. Two rotational stopper positioning pins 432A,
4323 are fixed vertically with respect to a surface facing
the front inside the rear projection 426 of the rear body
420, by means of pin fixing screws 440A, 440B. That is to
say, the positions at the centers of the two rotational
stopper positioning pins 432A, 432B are the same as the
centers of the screw holes 426A, 426B, respectively.
[0059] Looking at Figures 8 to 11, the rotational stopper
450 is disposed within the front recess 424 in the rear body
420. The rotational stopper 450 includes a disk-shaped base
part 452, an annular front shaft part 453 which is formed at
the front side of the base part 452, and a columnar rear
shaft part 454 which is formed at the rear side of the base
part 452. A front hole part 455 is formed in the central
part of the base part 452 and front shaft part 453. An
adjustment knob locking screw part 456 is formed in the
central part of the rear shaft part 454. Two rotational
stopper positioning holes 457A, 4573 are formed in the rear
shaft part 454, in the area surrounding the adjustment knob
locking screw part 456. In the mode of embodiment depicted,
two rotational stopper positioning holes are provided, but
there may be one, or two or more of these rotational stopper
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positioning holes. Furthermore, instead of providing the
rotational stopper positioning holes it is possible to
employ a different positioning structure comprising a recess
and a projection, or a structure may be formed such that the
rear part of the rotational stopper configures the
adjustment knob. The plurality of rotational stopper
positioning holes 457A, 457B may be provided symmetrically
about a point taking the center axis of the rotational
stopper 450 as a reference. The front ends of rotational
stopper positioning pins 468A, 468B are disposed in the
respective rotational stopper positioning holes 457A,
457B.
[0060] Looking at Figure 8, marks 420M showing "CLEAN",
"1.5", "2.0", "CLEAN", "1.5", "2.0" which indicate the
position of the needle 150 are formed on the rear surface of
the rear body 420 at angular intervals of 600, for example.
The mark "CLEAN" indicates the CLEAN position (corresponding
to the cleaning position, which is to say a needle pull of
4.5 mm). The mark "1.5" indicates the first discharge amount
position (corresponding to the small amount of discharge
position, which is to say a needle pull of 1.5 mm). The mark
"2.0" indicates the second discharge amount position
(corresponding to the large amount of discharge position,
which is to say a needle pull of 2.0 mm). Using these three
types of marks 420M it is possible to confirm the three set
positions of the rotational stopper 450 in the direction of
rotation.
[0061] Six counterbored holes 461 - 466 are formed on the
rear side of the base part 452 of the rotational stopper 450
as "non-through holes (blind holes)". The center positions
of the six counterbored holes 461 - 466 may lie at equal -
angular intervals with respect to one another and at equal
distances taking the center axis of the rotational stopper
450 as a reference. However, the inner diameters of the
counterbored holes 461 - 466 are preferably of the same
size. The first counterbored .hole 461 and the fourth
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counterbored hole 464 are formed to have equal depths. The
second counterbored hole 462 and the fifth counterbored hole
465 are formed to have equal depths. The third counterbored
hole 463 and the sixth counterbored hole 466 are formed to
have equal depths. The first counterbored hole 461 and the
fourth counterbored hole 464 are symmetrically provided
about a point with the center axis of the rotational stopper
450 as a reference. The second counterbored hole 462 and the
fifth counterbored hole 465 are symmetrically provided about
a point with the center axis of the rotational stopper 450
as a reference. The third counterbored hole 463 and the
sixth counterbored hole 466 are symmetrically provided about
a point with the center axis of the rotational stopper 450
as a reference.
[0062] In the mode of embodiment depicted, there are two
each of counterbored holes having three different depths.
For example, the first counterbored hole 461 and the fourth
counterbored hole 464 are formed with a depth of 3.5 mm and
are set as the CLEAN position (corresponding to the cleaning
position, which is to say a needle pull of 4.5 mm). The
second counterbored hole 462 and the fifth counterbored hole
465 are formed with a depth of 1.0 mm and are set as the
second discharge amount position (corresponding to the large
amount of discharge position, which is to say a needle pull
of 2.0 mm). The third counterbored hole 463 and the sixth
counterbored hole 466 are formed with a depth of 0.5 mm and
are set as the first discharge amount position
(corresponding to the small amount of discharge position,
which is to say a needle pull of 1.5 mm).
[0063] Looking at Figures 8, 9 and 12, the adjustment knob
430 is disposed at the rear side of the rear projection 426.
The adjustment knob 430 includes a disk-shaped base part
432, a front recess 434 which is formed at the front side of
the base part 432, and an annular front shaft part 435 which
is formed at the front side of the base part 432, inside the
front recess 434. A center hole 436 is formed in the central
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part of the base part 432 and the front shaft part 435. An
adjustment knob locking screw plate 438 is formed in the
central part of the base 432. The rear projection 426 which
is formed at the rear side of the rear body 420 has a size
and shape that allows it to move inside the front recess 434
of the adjustment knob 430.
[0064] Two rotational stopper pin holes 437A, 437B are
formed in the front shaft part 435 in the area surrounding
the center hole 436. In the mode of embodiment depicted,
there are two rotational stopper pin holes, but one, or two
or more rotational stopper pin holes may be provided. The
plurality of rotational stopper pin holes 437A, 437B may be
symmetrically provided about a point with the center axis of
the rotational stopper 450 as a reference. The positions
where the rotational stopper pin holes 437A, 437B are
provided are determined in such a way as to correspond to
the respective positions where the rotational stopper
positioning holes 457A, 4573 of the rotational stopper 450
are provided. The rear ends of the rotational stopper
positioning pins 468A, 468B are disposed in the respective
rotational stopper pin holes 437A, 4373.
[0065] Looking at Figure 8, two marks 430M for confirming
the position of the rotational stopper 450 in the direction
of rotation are formed on the rear surface of the adjustment
knob 430 at an angular interval of 180 . The adjustment knob
430 is rotationally adjusted so that the marks 430M on the
adjustment knob 430 and the marks 420M on the rear body 420
are aligned, whereby the position of the rotational stopper
450 in the direction of rotation can be confirmed.
[0066] Looking at Figures 8 and 9, the two rotational
stopper positioning pins 432A, 432B are disposed in the
front recess 424 of the base part 422 of the rear body 420,
respectively, and the rotational stopper positioning pins
432A, 432B are fixed to the rear projection 426 by means of
the pin fixing screws 440A, 440B. The front ends of the
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rotational stopper positioning pins 468A, 4683 are disposed
in the rotational stopper positioning holes 457A, 457B,
respectively, and the rotational stopper 450 is disposed in
the front recess 424 of the base part 422 of the rear body
420; the rear shaft part 454 of the rotational stopper 450
is designed to pass through the rear body center hole 420H,
and the rear ends of the rotational stopper positioning pins
468A, 4683 are disposed in the rotational stopper pin holes
437A, 437B, respectively, and the adjustment knob 430 is
immobilized by screw fastening with respect to the
rotational stopper 450 by means of an adjustment knob
locking screw 430A.
[0067] When the marks 430M on the adjustment knob 430 are
set in a position corresponding to "CLEAN" from the marks
420M on the rear body 420, the rotational stopper
positioning pins 432A, 432B are designed to enter the first
counterbored hole 461 and the fourth counterbored hole 464.
When the marks 430M on the adjustment knob 430 are set in a
position corresponding to "1.5" from the marks 420M on the
rear body 420, the rotational stopper positioning pins 432A,
432B are designed to enter the third counterbored hole 463
and the sixth counterbored hole 466. When the marks 430M on
the adjustment knob 430 are set in a position corresponding
to "2.0" from the marks 420M on the rear body 420, the
rotational stopper positioning pins 432A, 4323 are designed
to enter the second counterbored hole 462 and the fifth
counterbored hole 465.
[0068] Looking at Figure 1, by moving the adjustment knob
430 forward, the rotational stopper positioning pins 432A,
4323 are able to exit the counterbored holes. In this state,
the adjustment knob 430 is rotated and the adjustment knob
430 is moved backward so that the rotational stopper
positioning pins 432A, 432B enter any of the counterbored
holes, and the rotational stopper positioning pins 432A,
432B can be positioned.
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[0069] Looking at Figures 1, 3, 4 and 9, the base part 422
of the rear body 420 is fixed by screw fastening to the rear
end of the gun body 112, using the rear body fixing bolts
192A, 192B. By virtue of this configuration, the position of
the needle 150 in the axial direction and the position of
the front piston 170 in the axial direction can be
accurately adjusted to three different positions. That is to
say, with the configuration of the present invention, the
adjustment knob 430 is rotated so that the position of the
needle 150 in the axial direction and the position of the
front piston 170 in the axial direction can be adjusted to
the same positions, however many times the position of the
needle 150 in the axial direction and the position of the
front piston 170 in the axial direction are switched, and
there is no need for any fine adjustment operation, which
was the case with conventional screw-type systems.
[0070] Looking at Figures 1 to 12, a description has been
given in the mode of embodiment depicted of a structure in
which six counterbored holes 461 - 466 are formed at the
rear side of the base part 452 of the rotational stopper 450
as "non-through holes (blind holes)", but two, or three or
more counterbored holes may be provided. When a plurality of
counterbored holes are formed, the respective counterbored
holes may be provided equidistantly, taking the center axis
of the rotational stopper 450 as a reference. Furthermore, a
description has been given in the mode of embodiment
depicted of a structure in which the counterbored holes 461
- 466 are formed in the base part 452 of the rotational
stopper 450, but the counterbored holes may be provided in
the rear body, and the rotational stopper positioning pins
may be provided in the rotational stopper.
[0071] Furthermore, a description has been given in the mode
of embodiment depicted of a structure in which provision is
made for counterbored holes and rotational stopper
positioning pins, but it would also be possible to position
the rotational stopper in the axial direction using recesses
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provided on either the rotational stopper or the rear body,
and projections provided on the other of the rotational
stopper and the rear body. Furthermore, a description has
been given in the mode of embodiment depicted of a structure
in which the structural components are connected by screws
or bolts, but keys, bayonets or any other well-known method
may be used for the fixing method and connecting shapes.
[0072] The needle 150 is designed to come together with the
front piston 170 and to be able to move in a forward/back
direction along the center axis 114A of the nozzle. When the
needle 150 moves back, the paint ejection orifice 122 can be
opened by the front tip end of the needle 150. When the
needle 150 moves forward, the paint ejection orifice 122 can
be closed by the front tip end of the needle 150. As
described above, when compressed air is not introduced into
the front piston operating chamber 176, the front piston 170
moves forward and the needle tip 150C of the needle 150 is
designed to close off the paint ejection orifice 122, under
the elastic force of the needle spring 174.
[0073] The overall length of the needle 150 may be set at 66
mm, for example, and 10 mm of this may be designed to enter
the front piston 170. The diameter of the needle 150 may be
set at 4 mm, for example. The overall length when the needle
150 is fixedly attached to the front piston 170 may be set
at 73.5 mm, for example. The tip end of the nozzle 114 and
the tip end of the needle 150 should be flush.
[0074] By setting the dimensions in this way, it is possible
to set the working parts of the two-stage pull by assembling
the nozzle 114 of overall length 28 mm with the gun body 112
of overall length 60 mm, and using the needle 150 and front
piston 170 of overall length 73.5 mm.
[0075] Looking at Figures 1 to 5, a gun paint passage 320
for the passage of paint is provided inside the gun unit 110
and the bracket unit 210. The gun paint passage 320 includes
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an outlet section 320A, a gun body-internal section 320B, a
bracket unit-internal section 3200, and a bracket inlet
section 320D. The outlet section 320A of the gun paint
passage 320 is disposed between the inner wall of the nozzle
114 and the needle 150. The downstream side of the gun paint
passage 320 is configured to form a passage with the paint
ejection orifice 122.
[0076] Paint can be sent from the bracket inlet section
320D, which is the inlet end of the gun paint passage 320,
toward the paint ejection orifice 122. With this
configuration, the needle 150 constitutes a needle valve
which is disposed in the gun paint passage 320. This means
that the tip end of the needle valve is able to open and
close the paint ejection orifice 122.
[0077] A paint return passage 324 for returning the paint is
provided inside the gun unit 110. The paint return passage
324 includes a return port section 324A, a gun body-internal
section 324B, a bracket unit-internal section 3240, and a
bracket outlet section 324D. The outlet end 324D of the
paint return passage and the bracket outlet section 324D of
the gun paint passage 320 are disposed at the rear of the
bracket unit 210.
[0078] An atomized air passage 330 for the passage of
atomized air is provided inside the gun unit 110 and the
bracket unit 210. The atomized air passage 330 includes an
outlet section 330A, a gun body-internal section 330B, a
bracket unit-internal section 3300, and a bracket inlet
section 330D. The outlet section 330A of the atomized air
passage 330 is disposed outside the outer wall of the nozzle
114. The downstream side of the atomized air passage 330 is
configured to form a passage with a main atomized air
orifice 125. Atomized air can be sent from the bracket inlet
section 330D, which is the inlet end of the atomized air
passage 330, toward the main atomized air orifice 125.
Looking at Figure 3, the bracket inlet section 330D of the
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atomized air passage 330 is disposed at the rear of the
bracket unit 210. In addition, the downstream side of the
atomized air passage 330 may be configured to form a passage
with an auxiliary atomized air orifice 124. This auxiliary
atomized air orifice 124 has an auxiliary role, and it is
also possible to employ a structure without this auxiliary
atomized air orifice.
[0079] A pattern air passage 340 for the passage of pattern
air is provided inside the gun unit 110. The pattern air
passage 340 includes an outlet section 340A, a gun body-
internal section 340B, a bracket unit-internal section 340C,
and a bracket inlet section 330D. The outlet section 340A of
the pattern air passage 340 is disposed inside the inner
wall of the retaining ring 128. The downstream side of the
pattern air passage 340 is configured to forma passage with
the pattern air hole 126. Pattern air can be sent from the
inlet section 330D of the pattern air passage 340 toward
the inlet section 340D of the pattern air passage 340
toward the pattern air orifice 126. The inlet end 340D of
the pattern air passage 340 is disposed to the rear of the
bracket unit 210. -
[0080] A front piston operating air passage 350 for the
passage of operating air for ejecting paint, which causes
the needle 150 to move back when paint is ejected, is
provided inside the gun unit 110. The front piston operating =
air passage 350 includes a gun body-internal section 350B, a
bracket unit-internal section 350C, and a bracket inlet
section 350D. The downstream side of the front piston
operating air passage 350 is designed to form a passage into
the front piston operating chamber 176 which is provided in
front of the front end of the front piston 170. Operating
air can be sent from the inlet end of the front piston
operating air passage 350 to the front piston operating
chamber 176. With this configuration, the valve opening and
closing device consists of a piston which is operated by
means of front piston operating air sent from the front
piston operating chamber 176. Looking at Figure 3, the inlet '
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section 350D of the front piston operating air passage 350
is disposed to the rear of the bracket unit 210.
[0081] In addition, it is possible to allow the front piston
170 to move in a straight line backward along the center
axis 114A of the nozzle by positioning the needle seal kit
160 as far as possible to the front. Furthermore, it is
possible to improve the cleaning efficiency by making the
color reservoir (volume of the flow passage) inside the gun
body 112 as small as possible. In addition, it is possible
to set a narrow gap between the nozzle 114 and the needle
150 by providing a tapered part at the rear of the nozzle
114, which makes it possible to carry out reliable cleaning
and to improve the cleaning efficiency.
[0082] (3) Configuration of the bracket unit:
Looking at Figures 1 to 3, the bracket unit 210 includes a
bracket main body 212 which constitutes the base member of
the bracket unit. The bracket unit-internal section 320C and
the bracket inlet section 320D of the gun paint passage 320
are provided in the bracket main body 212. The bracket unit
210 is detachably fixed to the gun body 112. The bracket
inlet section 320D should consist of a straight thread, and
an 0-ring (preferably made of perfluoro) which is shaped
like a counterbored hole should be disposed inside the
thread. When the bracket unit 210 is fixed to the gun body
112, the paint and air received by the bracket unit 210
flows to the gun body 112.
[0083] The bracket unit-internal section 350C and the
bracket inlet section 350D of the front piston operating air
passage 350 for the passage of front piston operating air
are provided in the bracket main body 212. A front piston
operating air junction (not depicted) is provided in the
inlet section 350D of the front piston operating air passage
350. The front piston operating air junction is linked to a
control panel (not depicted) by way of a piping member such
as a tube (not depicted), and it may also be connected from
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the control panel to a front piston operating air supply
source.
[0084] Operating air may be introduced from the inlet
section 350D of the front piston operating air passage 350
to a spray device 100. When the bracket unit 210 is fixed to
the gun unit 110, the inlet end of the gun body-internal
section 3503 of the front piston operating air passage 350
is connected to the outlet end of the bracket unit-internal
section 3500. An 0-ring is preferably provided at this
connection. An 0-ring may be provided on the bracket unit
210, it may be provided on the gun unit 110, or it may be
provided on both. The inlet section 350D may consist of a
tapered thread. An electromagnetic valve (not depicted) is
provided in the front piston operating air passage 350. When
the electromagnetic valve (not depicted) is open, front
piston operating air introduced into the front piston
operating chamber 176 can be discharged.
[0085] The bracket unit-internal section 3300 and the
bracket inlet section 330D of the atomized air passage 330
are provided in the bracket main body 212. An atomized air
junction (not depicted) is provided in the inlet section
330D of the atomized air passage 330. The atomized air
supply source and the atomized air junction may be linked
using a piping member such as a connecting hose (not
depicted). The inlet section 330D should consist of a
tapered thread. Operating air may be introduced into the
spray device 100 from the inlet section 330D of the atomized
air passage 330. When the bracket unit 210 is fixed to the
gun unit 110, the inlet end of the gun body-internal section
3303 of the atomized air passage 330 is connected to the
outlet end of the bracket unit-internal section 3300. An 0-
ring is preferably provided at this connection. An 0-ring
may be provided on the bracket unit 210, it may be provided
on the gun unit 110, or may be provided on both.
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[0086] The bracket unit-internal section 3400 of the pattern
air passage 340 and the bracket inlet section 330D are
provided in the bracket main body 212. A pattern air
junction (not depicted) is provided in the inlet section
340D of the pattern air passage 340. The pattern air supply
source and the pattern air junction may be linked using a
piping member such as a connecting hose (not depicted). The
inlet section 340D should consist of a tapered thread.
Operating air may be introduced into the spray device 100
from the inlet section 340D of the pattern air passage 340.
When the bracket unit 210 is fixed to the gun unit 110, the
inlet end of the gun body-internal section 3403 of the
pattern air passage 340 is connected to the outlet end of
the bracket unit-internal section 3400. An 0-ring is
preferably provided at this connection. An 0-ring may be
provided on the bracket unit 210, it may be provided on the
gun unit 110, or may be provided on both.
[0087] The bracket unit-internal section 3200 and the
bracket inlet section 320D of the gun paint passage 320 are
provided in the bracket main body 212. A paint inlet
junction (not depicted) is provided in the bracket inlet
section 320D of the gun paint passage 320. The bracket inlet
section 320D should consist of a straight thread, and an 0-
ring (preferably made of perfluoro) which is shaped like a
counterbored hole should be disposed inside the thread. The
paint supply source and the paint inlet junction may be
linked using a piping member such as a connecting hose (not
depicted). Paint can be introduced into the spray device 100
from the bracket inlet section 320D of the gun paint passage
320. When the bracket unit 210 is fixed to the gun unit 110,
the inlet end of the gun body-internal section 3203 of the
gun paint passage 320 is connected to the outlet end of the
bracket unit-internal section 3200. An 0-ring is preferably
provided at this connection. That is to say, when the
bracket unit 210 is fixed to the gun unit 110, the paint
received by the bracket unit 210 flows through the gun unit
110. An 0-ring may be provided on the bracket unit 210, it
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may be provided on the gun unit 110, or may be provided on
both.
[0088] The bracket unit-internal section 3240 and the
bracket outlet section 3240 of the paint return passage 324
are provided in the bracket main body 212. A paint return
port junction (not depicted) is provided in the bracket
outlet section 324D of the paint return passage 324. The
paint supply source (or the paint tank) and the paint return
port junction may be linked using a piping member such as a
connecting hose (not depicted). Paint may be discharged from
the bracket outlet section 3240 of the paint return passage
324. The bracket outlet section 324D should consist of a
straight thread, and an 0-ring (preferably made of
perfluoro) which is shaped like a counterbored hole should
be disposed inside the thread. When the bracket unit 210 is
fixed to the gun unit 110, the outlet end of the gun body-
internal section 324B of the paint return passage 324 is
connected to the inlet end of the bracket unit-internal
section 3240. An 0-ring is preferably provided at this
connection. An 0-ring may be provided on the bracket unit
210, it may be provided on the gun unit 110, or may be
provided on both.
[0089] In addition, looking at Figures 6 and 7, in order to
respond to an air-type two-stage-pull spray device which
will be described later, then during operation other than
when the nozzle 114 is being cleaned, a rear piston
operating air passage 360 may be provided for the passage of
rear piston operating air which moves the rear piston
further forward and holds it there. The rear piston
operating air passage 360 includes a rear body-internal
section 360A, a gun body-internal section 3603, a bracket
unit-internal section 360C, and a bracket inlet section
360D. The downstream side of the rear piston operating air
passage 360 forms a passage into a rear piston end chamber
186 which is provided to the rear of a rear piston main body
1803. Cleaning operation air can be sent from the inlet end
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of the rear piston operating air passage 360 to the rear
piston end chamber 186.
[0090] The inlet section 360D of the rear piston operating
air passage 360 is disposed to the rear of the bracket unit
210. When the rear body is fixed to the gun body 112, the
inlet end of the rear body-internal section 360A of the
front piston operating air passage 350 is connected to the
outlet end of the gun body-internal section 3603. An 0-ring
is preferably provided at this connection. An 0-ring may be
provided on the rear body, it may be provided on the gun
body 112, or may be provided on both.
[0091] With the spray device according to the present
invention, each of the abovementioned gun paint passage 320,
paint return passage 324, atomized air passage 330, pattern
air passage 340, front piston operating air passage 350, and
rear piston operating air passage 360 may have an inner
diameter which is set at a suitable value in the range from
2 mm to 10 mm. These inner diameters may be set to suitable
values by simulation analyses, experimentation etc., taking
into account the viscosity of the atomized liquid and the
state of atomization.
[0092] Looking at Figure 3, with the spray device according
to the present invention, the bracket inlet section 320D of
the gun paint passage 320, the bracket outlet section 324D
of the paint return passage 324, the bracket inlet section
330D of the atomized air passage 330, the bracket inlet
section 340D of the pattern air passage 340, the bracket
inlet section 350D of the front piston operating air passage
350, and the bracket inlet section 360D of the rear piston
operating air passage 360 are preferably provided on one
surface of the bracket unit 210, for example a surface lying
at the rear. Looking at Figure 1, the surface lying at the
rear of the bracket unit 210 consists of three planes each
at an angle. One or two or three of the bracket inlet
section 320D of the gun paint passage 320, the bracket
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outlet section 324D of the paint return passage 324, the
bracket inlet section 330D of the atomized air passage 330,
the bracket inlet section 340D of the pattern air passage
340, the bracket inlet section 350D of the front piston
operating air passage 350, and the bracket inlet section
360D of the rear piston operating air passage 360 may be
disposed on each of these three planes. This configuration
makes it possible for paint and air to be supplied rapidly
and reliably to the spray device, and in a stable state.
This configuration also means that the tubes for supplying
paint and air are easily detached, so the tube detachment
time can be shortened and the time of maintenance operations
can be shortened.
[0093] When the spray device according to the present
invention is used for liquids such as water, liquid-type
adhesives, liquid-type rust prevention agents, liquid-type
insulating agents, liquid-type coating agents and liquid-
type drugs, the supply source for the liquid to be atomized
and the paint inlet junction (that is to say, in such cases
the junction which is configured as the "liquid inlet
junction") may be linked using a piping member such as a
connecting hose (not depicted). The spray device according
to the present invention has a unitary structure including
the gun unit and the bracket unit, and therefore the
production process for each structural component is
simplified and the components can be easily assembled.
[0094] The spray device according to the present invention
is configured as a plate-type gun. With this structure, the
plate is fixed when the gun is mounted if the gun is fixed
for use, if a robot is made to hold the gun, or if the gun
is mounted on a reciprocating engine. When the gun undergoes
maintenance, only the gun main body is detached, and
overhauls can be carried out, parts can be replaced, or the
main body can be replaced. This configuration makes it
possible to avoid the problem of being unable to install the
gun in its original position during installation after the
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removal of a tube (hose) which occurs in conventional guns,
which makes it possible to shorten the operating time.
[0095] A description has been given in this mode of
embodiment and the figures depict a structure in which the
gun unit is fixed to the bracket unit by a bolt with a
hexagonal hole, but it is also feasible to use a one-touch
(90 rotation) type structure.
[0096] (4) Coating operations using the spray device:
Looking at Figure 1, the spray device 100 may be used in a
fixed system, a robot may be made to hold an automatic spray
gun for use, one or more automatic spray guns may be mounted
on a device known as a "reciprocating engine" for use, or
the above structures may be combined for use.
[0097] As the paint used in the spray device 100, it is
possible to use solid paint, or it is possible to use
metallic paint. Paint containing organic solvents may also
be used. Paint containing aluminum powder may also be used.
For example, the gun unit 110 of the spray device 100 is
fixed to a robot arm. This fixing may employ a fastening
member such as nuts or bolts. Alternatively, the gun unit
110 of the spray device 100 is fixed to a robot arm, after
which the bracket unit 210 may be fixed to the gun unit 110.
In this case, the bracket unit 210 is fixed to the gun unit
110, after which a connecting hose (not depicted) may be
linked to the bracket unit 210, or the connecting hose is
linked to the bracket unit 210 and then the bracket unit 210
may be fixed to the gun unit 110.
[0098] Looking at Figures 1 and 8, when coating operations
are carried out, if the marks 430M on the adjustment knob
430 are set in a position corresponding to "1.5" from the
marks 420M on the rear body 420, the rotational stopper
positioning pins 432A, 4325 enter the third counterbored
hole 463 and the sixth counterbored hole 466. Furthermore,
if the marks 430M on the adjustment knob 430 are set in a
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position corresponding to "2.0" from the marks 420M on the
rear body 420, the rotational stopper positioning pins 432A,
432B enter the second counterbored hole 462 and the fifth
counterbored hole 465.
[0099] Front piston operating air is introduced from the
front piston operating air supply source into the front
piston operating chamber 176, passing through the connecting
hose and by way of the front piston operating air passage
350. When the front piston operating air is introduced into
the front piston operating chamber 176, the needle 150 and
the front piston 170 come together, and move backward along
the center axis 114A of the nozzle in resistance to the
spring force of the needle spring 174, and the cylindrical
section lying at the rear of the front piston shaft 170A
moves backward inside the inner peripheral part of the
cylindrical section lying in front of the rotational stopper
450, and the end face at the tip end of the cylindrical
section lying at the rear of the front piston shaft 170A is
maintained in a state of contact with the step part inside
the inner peripheral part of the cylindrical section lying
in front of the rotational stopper 450. For the front piston
operating air, it is possible to use compressed air at
around 0.25 MPa to 0.35 MPa, for example. The amount by
which the needle 150 can move backward may be set at 2 mm,
for example.
[0100] When the needle 150 moves back, the paint ejection
orifice 122 opens. Paint is supplied, from the paint supply
source by way of the piping member such as a connecting
hose, from the gun paint passage 320 to the nozzle 114, and
paint can be ejected from the paint ejection orifice 122.
[0101] At this point, atomized air is introduced from the
atomized air supply source through the connecting hose, by
way of the atomized air passage 330, and passes through the
main atomized air orifice 125 (and if necessary through the
auxiliary atomized air orifice 124), and atomized air is
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ejected so that it is possible to atomize the paint ejected
from the paint ejection orifice 122. The atomized air used
may be compressed air at around 0.25 MPa, for example. The
atomized state of the paint can be adjusted by changing the
atomized air pressure and the number and arrangement of
auxiliary atomized air orifices 124.
[0102] Furthermore, pattern air is introduced at the same
time from the pattern air supply source through the
connecting hose, by way of the pattern air passage 340, and
the pattern air is ejected from the pattern air orifice 126,
whereby a pattern of atomized paint can be formed. The
pattern air used may be compressed air at around 0.25 MPa,
for example. The shape of the paint pattern can be adjusted
by changing the pattern air pressure and the number and
arrangement of pattern air orifices 126.
[0103] The paint which is discharged from the tip end of the
nozzle 114 is normally atomized by the atomized air in the
air cap 120, and the paint is formed into a fan-shape by the
pattern air. If the needle 150 is not positioned in the
center of the nozzle 114, the discharge state of the paint
which is discharged from the tip end of the nozzle 114 is
unstable. In the present invention, as described above, it
is possible to allow the front piston 170 to move in a
straight line backward along the center axis 114A of the
nozzle by positioning the needle seal kit 160 as far as
possible to the front. Furthermore, in the present
invention, as will be described later, the rear piston main
body 180B and a needle stopper 180C of the rear piston 180
which is disposed at the rear serve to receive the front
piston 170, and the rear piston 180 itself is reliably
placed on the center axis 114A of the nozzle by means of a
rear coupling 172 and a rear body 190, and the front piston
170 can be moved in a straight line backward along the
center axis 114A of the nozzle. The configuration of the
present invention therefore makes it possible for the needle
150 to be positioned at the center of the nozzle 114, and
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for the rear piston 180 to be moved in a straight line
backward along the center axis 114A of the nozzle, and
therefore it is possible to improve the durability to wear
of the needle 150 and the sliding components inside the
needle seal kit 160.
[0104] The remaining paint which is not ejected from the
paint ejection orifice 122 can be returned to the paint
supply source (or the paint tank) via the paint return
passage 324 and the connecting hose. By doing so, it is
possible to construct a paint circulation line.
Alternatively, various kinds of liquids, including water,
adhesives, rust prevention agents, insulating agents,
coating agents and drugs can be automatically or manually
atomized using the spray device according to the present
invention.
[0105] When the coating operation has been completed, the
supply of front piston operating air is stopped, and the
needle 150 and front piston 170 come together and are moved
forward by the spring force of the needle spring 174. When
the needle 150 moves forward, the paint ejection orifice 122
closes, and the ejection of paint from the paint ejection
orifice 122 can be stopped. At the same time, the supply of
atomized air can be stopped, and the supply of pattern air
can be stopped.
[0106] (5) Cleaning of the nozzle:
Looking at Figures 1 and 8, when the nozzle of the spray gun
body is cleaned, the marks 430M on the adjustment knob 430
are set in a position corresponding to "CLEAN" of the marks
420M on the rear body 420. In this state, the rotational
stopper positioning pins 432A, 432B enter the first
counterbored hole 461 and the fourth counterbored hole 464.
When the nozzle of the spray gun body is cleaned, the gun
unit 110 of the spray device 100 is removed from the robot
arm so that the nozzle 114 can be cleaned. Alternatively,
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the nozzle 114 can be cleaned with the gun unit 110 of the
spray device 100 still attached to the robot arm.
[0107] Looking at Figure 13, in a state in which front
piston operating air has been introduced into the front
piston operating chamber 176 from the front piston operating
air supply source, the needle 150 and the front piston 170
come together, and they are maintained in a state in which
they move backward along the center axis 114A of the nozzle,
in resistance to the spring force of the needle spring 174.
At this point, the amount by which the needle 150 can move
back may be set at 3 mm, for example. By virtue of this
configuration, the amount by which the needle 150 can move
back from the closed state of the nozzle 114 to the nozzle
cleaning state may therefore be set at 5 mm, for example.
[0108] As described above, the degree of opening of the
discharge port of the spray device according to the present
invention can be set in a total of three different
positions, namely two coating positions and one position for
cleaning, and improved performance can be achieved in terms
of significantly reduced cleaning times and significantly
improved operating efficiency. Furthermore, with the spray
device according to the present invention, the needle
position can be manually set to fully open by operation of
the adjustment knob. Furthermore, when the needle position
is returned to the original position, the needle position
can be manually set so as to return to the original position
by operation of the adjustment knob. Furthermore, with the
spray device according to the present invention, the needle
position during coating is always a fixed position, which
means that there is an effect whereby the quality of the
object to be coated (product) can be kept constant.
Furthermore, the spray device according to the present
invention has a detachable unitary structure, and therefore
the components making up each of the units can be easily
produced and assembled.
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[0109] (6) Air-type two-stage-pull spray device:
(6-1) Closed nozzle state
A description will be given below of the configuration and
action when an air-type two-stage-pull spray device is
constructed using the gun unit according to the present
invention. Looking at Figure 16, the rear coupling 172 is
disposed to the rear of the gun body 112. The needle spring
174 is provided in order to push the front piston main body
170B forward. The rear section of the needle spring 174 is
disposed so as to come into contact with the planar section
facing the front of the rear coupling 172. The front section
of the needle spring 174 is disposed so as to come into
contact with a section facing the rear of the front piston
flange 170F of the front piston main body 170B. The center
axis of the needle spring 174 may lie on the center axis
114A of the nozzle. The front piston 170 is subjected to
force in a forward-moving direction by means of the elastic
force of the needle spring 174. Accordingly, when compressed
air is not, introduced into the front piston operating
chamber 176, the front piston 170 moves forward and the
needle tip 150C of the needle 150 is designed to close off
the paint ejection orifice 122.
[0110] The rear body 190 is fixed to the rear of the gun
body 112 by means of the fixing bolts 192A and 192B. The
rear body 190 can be fixed to the gun body 112 using two
rear body fixing bolts 192A and 192B, for example. The
rear coupling 172 is disposed inside the rear body 190.
The rear body 190 is preferably formed from POM
(polyoxymethylene), for example.
[0111] Looking at Figure 16, the gun unit 110 is provided
with the rear piston 180 which can move along the center
axis 114A of the nozzle. The rear piston 180 is disposed at
the rear of the front piston 170, inside the rear body 190.
The rear piston 180 includes a rear piston main body 180B
and a rear piston shaft part 180G. A rear piston hole 180H
is provided inside part of the rear piston shaft part 180G
from the front of the rear piston main body 180B. The needle
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stopper 180C is fixed in the rear piston hole 180H. A rear
piston 0-ring 180D is disposed inside a groove at the outer
periphery of the rear piston main body 180B. The center axis
of the rear piston 180 lies on the center axis 114A of the
nozzle. The outer peripheral part of the cylindrical section
lying at the rear of the front piston shaft 170A is slidably
disposed within the inner peripheral part of the cylindrical
section lying in front of the needle stopper 1800. The outer
peripheral part of the cylindrical section lying at the rear
of the needle stopper 1800 is fixed inside the inner
peripheral part of a hole lying in front of the rear piston
main body 180B. The planar section facing the front of the
rear piston main body 180B is disposed so as to come into
contact with the planar section facing the rear of the rear
coupling 172.
[0112] The rear piston end chamber 186 for receiving the
rear piston operating air which moves the rear piston 180
forward along the center axis 114A of the nozzle is
configured inside the rear body 190, behind the rear piston
main body 1803. In addition, a rear piston operating chamber
188 for the introduction of rear piston operating air which
has been received in the rear piston end chamber 186 in
order to push the rear wall surface of the rear piston main
body 180B is configured inside the rear body 190, outside
the shaft part behind the rear piston main body 180B.
[0113] The rear piston 0-ring 180D is disposed in a groove
provided at the outer periphery of the rear piston main body
180B. The rear piston 0-ring 180D is provided in order to
seal the rear piston main body 1803 and the rear body 190.
As regards the rear piston 0-ring 180D, it is preferable to
use an 0-ring in order to increase the sliding resistance
for receiving the front piston 170. The rear piston 0-ring
180D is preferably formed from perfluoro.
[0114] The rear piston main body 180B may be formed from
aluminum alloy A2021 (alumite treatment may be carried out,
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for example). The outer diameter of the front piston 170 is
preferably designed to be smaller than the outer diameter of
the rear piston 180. Accordingly, the outer diameter of the
front piston seal 1700 is preferably designed to be smaller
than the outer diameter of the rear piston 0-ring 180D.
[0115] The needle 150 is designed to come together with the
front piston 170 and to be able to move in a forward/back
direction along the center axis 114A of the nozzle. When the
needle 150 moves back, the paint ejection orifice 122 can be
opened by the front tip end of the needle 150. When the
needle 150 moves forward, the paint ejection orifice 122 can
be closed by the front tip end of the needle 150. In
addition, the needle 150, front piston 170 and rear piston
180 are designed to come together and to be able to move
further back along the center axis 114A of the nozzle from
the position in which the needle 150 has moved back together
with the front piston 170.
[0116] The overall length of the needle 150 may be set at 66
mm, for example, and 10 ram of this may be designed to enter
the front piston 170. The diameter of the needle 150 may be
set at 4 mm, for example. The overall length when the needle
150 is fixedly attached to the front piston 170 may be set
at 73.5 mm, for example. The tip end of the nozzle 114 and
the tip end of the needle 150 should be flush.
[0117] By setting the dimensions in this way, it is possible
to set a one-stage pull of 2 mm, for example, by assembling
the nozzle 114 of overall length 28 ram with the gun body 112
of overall length 60 mm, and using the needle 150 and front
piston 170 of overall length 73.5 mm, and by adjusting the
rear coupling 172 of width 4 mm, the dimensions of the rear
piston 180, and the hole depth of the needle stopper 1800
inside the rear piston main body 180B of overall length 26
mm. Furthermore, it is possible to set the working parts of
a two-stage pull of 3 mm, for example, by adjusting the
dimensions inside the rear body 190, the rear coupling 172
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of width 4 mm, and the dimensions of the working parts of
the rear piston 180.
[0118] The inner diameter of the cylinder of the front
piston 170 is 22 mm, for example. The inner diameter of the
cylinder of the rear piston 180 is 24 mm, for example.
[0119] A rear piston operating air passage (not depicted)
for the passage of rear piston operating air which moves the
rear piston 180 further forward and holds it there during
operations other than when the nozzle 114 is being cleaned
is provided inside the rear body 190. The downstream side of
the rear piston operating air passage is configured to form
a passage into the rear piston end chamber 186 which is
provided at the rear of the rear piston main body 180B.
Cleaning operation air can be sent from the inlet end of the
rear piston operating air passage to the rear piston end
chamber 186.
[0120] The inlet section of the rear piston operating air
passage is disposed behind the bracket unit 210. When the
rear body 190 is fixed to the gun body 112, the inlet end of
the rear body-internal section of the front piston operating
air passage is designed to be connected to the outlet end of
the gun body-internal section. An 0-ring is preferably
provided at this connection. An 0-ring may be provided on
the rear body 190, it may be provided on the gun body 112,
or it may be provided on both.
[0121] Looking at Figure 16, the rear body 190 has two bolt
holes for the passage of the rear body fixing bolts. The
rear body 190 also has six air passage holes 190K which form
a passage between the rear piston end chamber 186 and the
rear piston operating chamber 188. A plurality of air
passage holes 190K are preferably arranged concentrically
with the center axis 114A of the nozzle at the center. Six
air passage holes 190K are shown, but there may be four air
passage holes, or eight air passage holes, or another number
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of such holes. The plurality of air passage holes are
preferably concentrically disposed such that there is an
equal angular interval therebetween with the center axis
114A of the nozzle at the center. By providing this
concentric plurality of air passage holes 190K, the rear
piston 180 can move reliably and smoothly forward.
[0122] The rear piston main body 180B and the needle stopper
180C of the rear piston 180 which is disposed at the rear
serve to receive the front piston 170, and the rear piston
180 itself is reliably placed on the center axis 114A of the
nozzle by means of the rear coupling 172 and the rear body
190. This configuration makes it possible for the front
piston 170 to be moved in a straight line backward along the
center axis 114A of the nozzle. In addition, the
configuration of the present invention makes it possible for
the rear piston 180 to be moved in a straight line backward
along the center axis 114A of the nozzle.
[0123] (6-2) First open state of the nozzle
Looking at Figure 17, rear piston operating air is
introduced from the rear piston operating air supply source
into the rear piston end chamber 186, passing through the
connecting hose, and by way of the rear piston operating air
passage. The rear piston operating air which is introduced
into the rear piston end chamber 186 passes through the
plurality of air passage holes 190K and flows into the rear
piston operating chamber 188 from the rear piston end
chamber 186. When the rear piston operating air is
introduced into the rear piston operating chamber 188, the
rear piston 180 moves forward along the center axis 114A of
the nozzle, and the planar section facing the front of the
rear piston main body 180B is maintained in a state of
contact with the planar section facing the rear of the rear
coupling 172. For the rear piston operating air, it is
possible to use compressed air at around 0.4 MPa to 0.5 MPa,
for example.
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[0124] Front piston operating air is introduced from the
front piston operating air supply source into the front
piston operating chamber 176, passing through the connecting
hose and by way of the front piston operating air passage
350. When the front piston operating air is introduced into
the front piston operating chamber 176, the needle 150 and
the front piston 170 come together, and move backward along
the center axis 114A of the nozzle in resistance to the
spring force of the needle spring 174, and the cylindrical
section lying at the rear of the front piston shaft 170A
moves backward inside the inner peripheral part of the
cylindrical section lying in front of the needle stopper
180C, and the end face at the tip end of the cylindrical
section lying at the rear of the front piston shaft 170A is
maintained in a state of contact with the step part inside
the inner peripheral part of the cylindrical section lying
in front of the needle stopper 180C.
[0125] For the front piston operating air, it is possible to
use compressed air at around 0.25 MPa to 0.35 MPa, for
example. The rear piston operating air pressure is set to be
higher than the front piston operating air pressure. The
difference between the rear piston operating air pressure
and the front piston operating air pressure may be set at
around 0.05 MPa to 0.25 MPa, for example. The amount by
which the needle 150 can move backward may be set at 2 mm,
for example.
[0126] When the needle 150 moves back, the paint ejection
orifice 122 opens. Paint is supplied, from the paint supply
source by way of the piping member such as a connecting
hose, from the gun paint passage 320 to the nozzle 114, and
paint can be ejected from the paint ejection orifice 122.
[0127] At this point, atomized air is introduced from the
atomized air supply source through the connecting hose, by
way of the atomized air passage 330, and passes through the
main atomized air orifice 125 (and if necessary through the
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auxiliary atomized air orifice 124), and atomized air is
ejected so that it is possible to atomize the paint ejected
from the paint ejection orifice 122. The atomized air used
may be compressed air at around 0.25 MPa, for example. The
atomized state of the paint can be adjusted by changing the
atomized air pressure and the number and arrangement of
auxiliary atomized air orifices 124.
[0128] Furthermore, pattern air is introduced at the same
time from the pattern air supply source through the
connecting hose, by way of the pattern air passage 340, and
the pattern air is ejected from the pattern air orifice 126,
whereby a pattern of atomized paint can be formed. The
pattern air used may be compressed air at around 0.25 MPa,
for example. The shape of the paint pattern can be adjusted
by changing the pattern air pressure and the number and
arrangement of pattern air orifices 126.
[0129] (6-3) Second open state of the nozzle (nozzle
cleaning state)
A description will be given below of the action when the
nozzle of the spray gun body is cleaned. Looking at Figure
18, in a state in which front piston operating air has been
introduced into the front piston operating chamber 176 from
the front piston operating air supply source, an
electromagnetic valve (not depicted) which is provided in
the rear piston operating air passage is opened, whereby the
rear piston operating air which has been introduced into the
rear piston end chamber 186 and the rear piston operating
chamber 188 is discharged.
[0130] By means of this, the needle 150, front piston 170,
and rear piston 180 come together and move backward along
the center axis 114A of the nozzle in resistance to the
spring force of the needle spring 174, and the planar
section facing the rear of the rear piston main body 180B is
maintained in a state of contact with the step part inside
the rear body. At this point, the amount by which the needle
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150 can move back may be set at 3 mm, for example. By virtue
of this configuration, the amount by which the needle 150
can move back from the closed state of the nozzle 114 to the
nozzle cleaning state may therefore be set at 5 mm, for
example.
[INDUSTRIAL APPLICABILITY]
[0131] The spray device described above can be easily
realized with any of the three types of conventional spray
devices, namely adjust type, air-type two-stage-pull type
and manual multiple-stage type spray devices. That is to
say, it is possible to increase the value of the objects to
be coated (products) by means of a synergistic effect
achieved by using three types of spray device, making it
possible to achieve a distinction with standard products. In
addition, with a manual multiple-stage type spray device
according to the present invention, there is one less air
circuit than with an air-type two-stage-pull type spray
device (the same as with a conventional adjust type spray
device), and therefore there is the advantage that when a
conventional adjust type spray device is being used, it is
possible to replace this with a manual multiple-stage type
spray device according to the present invention without
adding an air circuit. Furthermore, the spray device
according to the present invention has a detachable unitary
structure, and therefore it is simple to produce and
assemble each of the components making up the unit.
[0132] The spray device according to the present invention
can also be used in a fixed system; it can also be used in a
system in which a robot is made to hold an automatic spray
gun; it can be used in a system in which one or more
automatic spray guns are mounted on a device known as a
"reciprocating engine"; or it may be used in a system
combining the above configurations. The spray device
according to the present invention makes it possible to
shorten the downtime when the spray gun body is cleaned,
when the spray gun body is replaced, or when the nozzle is
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replaced, and paint can be sprayed with only a short amount
of time lost. Furthermore, the spray device according to the
present invention makes it possible to shorten the downtime
for coating operations when the nozzle is cleaned. In
addition, the spray device according to the present
invention makes it possible to spray not only paint but also
various kinds of liquids, including water, adhesives, rust
prevention agents, insulating agents, coating agents and
drugs. The structural components of the spray device
according to the present invention can be easily produced
and assembled, and therefore the device can be produced
using a simple process.
[KEY TO SYMBOLS]
[0133]
100 spray device
110 gun unit
112 gun body
114 nozzle
150 needle
160 needle seal kit
170 front piston
174 needle spring
176 front piston operating chamber
180 rear piston
186 rear piston end chamber
188 rear piston operating chamber
190 rear body
210 bracket unit
220 bolt with hexagonal hole
400 spray device
420 rear body
430 adjustment knob
450 rotational stopper
