Note: Descriptions are shown in the official language in which they were submitted.
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Nozzle Attachment For An Adhesive SpraY Gun
Related Patents
This invention is related to Canadian
Patent ~o. 1,263,808, issued December 12, 1989,
and entitled "Adhesive Spray Gun and Nozzle
Attachment", which is assigned to the same assignee as
this invention.
Field of the Invention
This invention relates to adhesive spray
guns, and, more particularly, to an adhesive spray gun
having a nozzle attachment for spraying hot melt
adhesive in beads or fibers in a controlled spray
pattern onto a substrate.
Backqround of the Invention
Hot melt thermoplastic adhesives have been
widely used in industry for adhering many types of
products, and are particularly useful in applications
where quick setting tlme is advantageous. One appli-
cation for hot melt adhesive which has been of consid-
erable interest in recent years is the bonding of non-
WoVeD~ fibrous materlal to a polyurethane substrate in
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articles such as disposable diapers, incontinence pads
and similar articles.
One aspect of forming an appropriate bond
between the non-woven layer and polyurethane substrate
of a disposable diaper, for example, is to avoid loss
of adhesive in the valleys or gaps formed in the
irregular surface of the chopped fibrous or fluff-type
makerial which forms th~ non-woven layer. If the
adhesive is discharged onto the non-woven layer in
droplet form, for example, a portion of the dropl~ts
can fall between the gaps in the surface of the
fibrous, non-woven material. As a result, additional
quantities of adhesive are required to obtain the
desired bond strength between the polyurethane sub-
strate and non-woven material.
This problem has been overcome in the prior
art by forming hot melt thermoplastic adhesives in
elongated, thin beads or fibers which are deposited
atop the non-woven material and span the gaps in its
irregular surface. Elongated beads or fibers of
adhesive have been produced in prior art spray devices
which include a nozzle formed with an adhesive dis-
charge opening and one or more air jet orifices
through which a jet of air is ejected. A bead of
adhesive is ejected from the adhesive discharge
opening in the nozzle which is then impinged by the
air jets to attenuate or stretch the adhesive bead
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forming a thin fiber for deposition onto the sub-
strate. Examples of spray devices of this type are
disclosed in U.S. Patent Nos. 2,626,424 to Hawthorne,
Jr.; 3,152,923 to Marshall et al; and, 4,185,981 to
Ohsato et al.
Ln applications such as the formation of
disposable diapers, it is important to carefully
control the spray pattern of adhesive fibers deposited
onto the non-woven substrate in order to obtain the
desired bond strength between the non-woven layer and
polyurethane substrate using as little adhesive as
possible. Improved control of the spray pattern of
adhesive fibers has been obtained in prior art spray
devices of the type described above by impacting the
adhesive bead discharged from the nozzle with air jets
directed substantially tangent to the adhesive bead.
The tangentially applied air jets control the motion
of the elongated fibers of adhesive formed from the
adhesive bead ejected from the adhesive discharge
opening in the gun nozzle, and confine the elongated
fibers in a relatively tight, or compact, spiral
pattern for application onto the substrate. Structure
which produces a spiral spray pattern of adhesive
fibers for deposition onto a substrate is disclosed,
for example, in the '424 Hawthorne, Jr. patent and the
'981 Ohsato et al patent mentioned above.
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In order to produce a compact spiral spray
pattern of adhesive fibers in the spray devices
described above, it is important to ensure that the
air jets are dlrected tangentiallv relative to the
bead of adhesive ejected from the nozzle of the spray
device. This requires accurate placement of the bores
or passageways through which pressurized air is
ejected from the nozzle or gun body of the spray
device, which are typically on the order of about
lO 0.015 to 0.020 inches in diameter. The boring or
drilling of passageways having such a small diameter
at the appropriate angles in the nozzle and/or gun
body of prior art spray devices is a relatively
expensive and difficult machining operation.
Many problems with prior art adhesive fiber
spray systems have been overcome by the nozzle attach~
ment disclosed in Canadian Patent No. l,263,808,
issued December 12, 1989, and entitled "Adhe-
sive Spray Gun and Nozzle Attachment" which is
20 assigned to the same assignee as this invention. The
nozzle attachment of that invention is adapted to
mount to the nozzle of a standard adhesive spray gun
which is formed with an adhesive discharge opening
connected to an adhesive passageway in the gun body
~S and an air discharge opening connected to an air
passageway in the gun body. The nozzle attachment is
a one-piece annular plate formed with a boss extending
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outwardly from a first surface of the plate and a
nozzle tip extending outwardly from a second surface
of the plate. A throughbore is formed between the
boss and nozzle tip which communicates with the
adhesive discharge opening in the nozzle of the gun
body when the plate is mounted to the nozzle. Heated
hot melt adhesive is transmitted through the adhesive
passageway in the gun body, out its adhesive discharge
opening and then into the throughbore in the plate.
The adhesive is ejected as a bead through the nozzle
tip toward a substrate.
The annular plate is formed with a V-shaped
notch or groove which extends from its first surface
having the boss toward the second surface formed with
the nozzle tip. The V-shaped groove is provided to
assist in drilling air jet bores in the plate through
which jets of pressurized air are directed at an angle
of about 30 and tangent to the adhesive bead ejected
from the nozzle tip. The annular V-shaped groove is
formed with two sidewalls, one of which is disposed
substantially perpendicularly to the longitudinal axis
of each of the air jet bores. This construction
permits the drill bit to contact the plate at the
~ surface of one of the sidewalls in the V-shaped groove
which is substantially perpendicular to the axis of
movement of the drill bit, i.e., at an angle of abut
30 to the first and second surfaces of the plate. As
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a result, sliding of -the drill bit relative to the
plate is minimized duriny the drilliny or boring
operation which helps locate the air jets bores at the
desired angle in the plate.
While the nozzle attachment disclosed in
Canadian Patent No. 1,263,808 solves many of the problems of
prior art devices designed to spray adhesive fibers,
some deficiencies have been discovered in certain
applications. It has been found that the formation of
a groove in the relatively thin nozzle attachment or
plate can result in deflection of the nozzle attach-
ment during operation. This deflection can form a
leakage path at the interface between the nozzle
attachment and nozzle of the spray gun. In some
instances, it has been found that hot melt adhesive
entering the nozzle attachment has flowed along this
leakage path and been deposited in the V-shaped groove
where the air flows into the air jet bores. This can
clog the air jet bores and restrict the flow of air
necessary to attenuate or stretch the adhesive bead to
form adhesive -fibers.
Another potential problem with the nozzle
attachment of Canadian Patent No. 1,263,808, iS that the air
; jet bores are drilled in the plate or nozzle attach-
ment from the inner side or surface which contacts the
nozzle toward the outer side or surface formed with
the nozzle tip. Because the air jet bores are so
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small in diameter, i.e., .015 to .020 inches, it is
possible for the drill bit to drift or move off line
in the course of passing throuyh the nozzle attachment
from its inner side to the outer side. As a result,
the discharge outlet of the air jet bores at the outer
side of the nozzle attachment miyht be slightly out of
position and this can affect the efficiency of the
nozzle attachment in forming adhesive fibers because
the air jets may not impact the adhesive bead pre-
cisely tangentially thereto.
The nozzle tip of the nozzle attachmen-t
disclosed in Canadian Patent No. 1,263,808, protrucle~ from the
outer surface thereof when mounted to the nozzle of
the gun body, and extends outwardly from a mounting
nut which secures the nozzle attachment to the nozzle
of the spray gun. A cavity or space is thus formed
between the nozzle tip and such mounting nut. When
the spray gun is operated intermittently, it has been
found that cut-off drool, i.e., adhesive remaining
after the gun is shut off, can collect in the space or
cavity between the nozzle tip and mounting nut. This
cut-off drool might collect and partially block the
discharge outlet of the air jet bores formed in the
~ nozzle attachment, thus affecting the performance of
the nozzle attachment in forming adhesive fibers.
Additionally, the protruding nozzle tip is exposed and
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can be damaged if it contacts the target substrate or
other object during operation of the spray gun.
Summary of the Invention
It is therefore among the objectives of this
invention to provide a nozzle attachment for use in a
spray gun for spraying hot melt adhesive in elongated
beads or fibers onto a substrate which is r~latively
inexpensive to manufacture, which provides accurately
located air jets to attenuate or stretch an adhesive
bead to form adhesive fibers, which avoids leakage of
adhesive from the spray gun, which is rugged in
construction, which resists clo~ging with adhesive and
which is readily installed on a standard spray gun to
convert the spray gun to one capable of spraying hot
melt adhesive in fiber form.
These objectives are accomplished in a
nozzle attachment for a hot melt adhesive spray device
which includes a gun body and a nozzle having an
adhesive passageway and an air passageway. The nozzle
attachment is a one-piece annular plate which is
mounted by a cap or nut to the nozzle of the gun body.
The nozz~e attachment or plate is formed with a
throughbore adapted to connect to the adhesive
passageway in the nozzle, and a plurality of spaced
air jet bores are formed in the plate which communi-
cate with the air passageway in the nozzle. An
adhesive bead is ejected from the throughbore in the
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plate which is impacted by air jets from the spaced
air jet bores. The air ~ets are directed tangentially
to the bead to both stretch the bead forming hot melt
adhesive fibers, and to impart a spiral motion to the
adhesive fibers so that they are deposited in a
controlled spray pattern upon a substrate.
The one-piece annular plate is formed with a
boss extending outwardly from a first, inner surface
of the plate, and a nozzle tip extending inwardly from
a second, outer surface of the plate toward its inner
surface. A throughbore is formed between the boss and
nozzle tip which communicates with the adhesive
passageway in the nozzle when the plate is mounted
thereto. Heated hot melt adhesive is transmitted
through the nozzle and then into the throughbore in
the plate from which it is ejected through a discharge
outlet of the nozzle tip toward a substrate.
The annular plate of this invention is
relatively thick from its inner surface to its outer
surface in order to resist deflection with respect to
the nozzle during operation of the spray gun. The
inner surface of the plate is flat or planar except
for the boss which extends outwardly therefrom. This
inner surface forms an effective me~al-to-metal seal
with the mating surface of the nozzle of the spray gun
when the plate is mounted thereto. As a result,
adhesive transmitted from the nozzle into the
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throughbore of the plate is prevented from leaking at
the interface therebetween.
The annular plate forming the nozzle attach-
ment of this invention is formed with an annular,
V-shaped notch or groove which extends inwardly from
the outer surface of the plate toward its inner
surface. This V-shaped groove is provided to assist
in the drilling operation of the air jet bores through
which jets of pressurized air are directed from the
air passageway in the nozzle, through the plate and
then into contact with the adhesive bead ejected from
the discharge outlet of the nozzle tip.
In the presently preferred embodiment, each
of the spaced air jet bores is drilled at an angle of
approximately 30 with respect to the longitudinal
axis of the throughbore in the plate from which the
adhesive bead is ejected. In order to assist in
drilling the air jet bores at this angle, the V-shaped
notch or groove at the outer surface of the nozzle
attachment forms two sidewalls. One of the sidewalls
is oriented substantially perpendicularly to the
longitudinal axis of each of the air jet bores. The
other sidewall forms the outer surface of the noæzle
tip such that the discharge outlet of the nozzle tip
is substantially coplanar with the outer surface of
the plate. The sidewall of the V-shaped ~roove
oriented perpendicularly to the longitudinal axis of
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the air jet bores permits the drill bit to contact the
plate at a surface which is substantially perpendicu-
lar to the axis of movement of the drill bit even
though the drill bit is moved at a 30 angle with
respect to the outer surface of the plate.
The air jet bores formed in the nozzle
attachment of this invention are drilled by movement
of a drill bit from the outer surface of the nozzle
attachment where the V-shaped groove is formed, toward
the inner surface of the nozzle attachment which
contacts the nozzle. As mentioned above, it is
important that the outlet of the air jet bores be
precisely located so that the air jets discharged
therefrom tangentially impact the adhesive bead
discharged from the nozzle tip of the nozzle attach-
ment. Because the drilling operation begins at the
outer surface of the nozzle attachment, the location
of the outlet of the air jet bores at such outer
surface can be precisely controlled. Any drift of the
drill bit in moving through the nozzle attachment or
plate has no effect on the location of the outlet of
the air jet bores at the outer surface of the plate.
This had sometimes presented a problem in the machin-
ing of the nozzle attachment disclosed in prior
Canadian Patent No. 1~,263,808 wherein the drilling
operation proceeded from the inner surface of the
pIate toward the outer surface.
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In a presently preferred embodimen~, the
spaced air jet bores are also formed in the plate at
an angle relative to the outer periphery of the
throughbore and the adhesive bead ejected there~rom.
5The longitudinal axis of each air jet bore is oriented
at an angle of appro~imately 10~ with respect to a
vertical plane which passes through the longitudinal
axis of the throughbore in the plate and the center of
such air jet bore at the V-shaped groove in the plate.
lOAs a result, the jets of pressurized air ejected from
the spaced air jet bores impact the adhesive bead
discharged from the nozzle tip of the plate at its
outer periphery so as to impart a rotational movement
to the bead. The adhesive bead is attenuated or
15stretched into elongated fibers upon impact with the
air jets, and these fibers are then rotated by the air
jets in a spiral motion to control the width of the
spray pattern applied to the substrate.
In the presently preferred embodiment, an
20annular recess is formed in the nozzle attachment or
plate which extends inwardly at the peripheral edge of
the plate from its outer surface toward the inner
surface. This annular recess forms a seat which
receives the mounting nut or cap which mounts the
25nozzle attachment to the nozzle of the spray yun.
Preferably, the outer surface of the nozzle attachment
and the discharge outlet of the nozzle tip are
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coplanar with the mounting cap or nut when the nozzle
attachment is mounted to the spray gun nozzle.
This construction has two advantages.
First, there is no space or cavity formed between the
mounting nut and nozzle tip ln which cut-off drool or
strands of adhesive cvuld collect to block the air jet
bores. This had been a problem in the aforementioned
Canadian Patent No. 1,263,808 wherein a gap
was formed between the nozzle tip and mounting nut.
Secondly, the mounting nut, the outer surface of the
nozzle attachment and the discharge outlet of the
nozzle tip are all coplanar. This prevents the nozzle
tip from contacting the substrate or another object
during separation of the spray gun where it could be
damaged.
The nozzle attachment or plate of this
invention provides an economical means to convert a
standard spray gun into one in which hot melt adhesive
may be discharged in elongated strands or fibers for
applications such as bonding the non-woven and poly-
urethane layers of disposable diapers or other
hygienic articles. The construction of the nozzle
attachment or plate prevents leakage of adhesive at
~ its interace with the nozzle, facilitates the accu-
rate drilling of air jet bores so that the adhesive
bead discharged from the spray device is consistently
formed into elongated fibers and resists clogging from
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build-up of cut-off drool. ThP nozzle attachment or
plate is easily removed from the spray gun and re-
placed with another nozzle attachment of different
size to accommodate different applications and/or
different spray guns.
Detailed Description of the Drawings
The structure, operation and advantages of
the presently preferred embodiment of this invention
will become further apparent upon consideration of the
following description, taken in conjunction with the
accompanying drawings, wherein:
Fig. 1 is a cross sectional view of a spray
gun incorporating the nozzle attachment herein with a
schematic view of a manifold mounted to the spray gun;
Fig. 2 is an enlarged cross sectional view
of the nozzle attachment herein showing an adhesive
bead impacted by air jet streams; and
Fig. 3 is a top plan view of the nozzle
attachment shown in Fig. 2.
Detailed Des~ription of the Invention
Referring now to Fig. 1, an adhesive spray
device lO is illustrated comprising a gun body 12
having a nozzle 14 connected at one end, and an
adhesive manifold 16 and air manifold 17 mounted to
the gun body 12. The air manifold 17 is mounted to
the adhesive manifold 16 by two or more screws 19,
each of which extend through a spacer 21 extending
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between the manifolds 16, 17. The noz~le 1~ supports
a nozzle attachment 18 from which a bead of heated hot
melt adhesive is discharged and formed into a thin,
elongated bead or fiber which is rotated in a compact
spiral spray pattern onto a substrate, as discussed in
detail below. The structure of the gun body 12 and
manifolds 16, 17 are suhstantially identical to the
Model H200 spray gun manufactured and sold by the
assignee of this invention, Nordson Corporation of
Amherst, Ohio. These elements form no part of the
invention per se and are thus discussed only briefly
herein.
As shown in Fig. 1, the upper portion of gun
body 12 is formed with an air cavity 20 which receives
the upper end of a plunger 22 mounted to a seal 24.
The seal 24 is slidable within the air cavity 20 and
provides an airtight seal along its walls. A collar
26 is mounted to the upper end of gun body 12, such as
by bolts 28, which is formed with a throughbore
defining an inner, threaded wall 30. The collar 26
receives a plug 32 having external threads which mate
with the threaded wall 30 of the collar 26. The plug
32 is hollow and a spring 34 is mounted in its interi-
or which extends between the top end of the plunger 22
and the head 36 of plug 32 having a screw slot 38. A
lock nut 40 is threaded onto the plug 32 into engage-
ment with the top edge of the collar 26.
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The plug 32 is rotatable with respect to the
collar 26 to vary the force applied by the spring 34
against the top edge of plunger 22. In order to
rotate the plug 32, the lock nut 40 is first rotated
to disengage the collar 26 after which a screwdriver
is inserted into the screw slot 38 in the head 36 of
plug 32 and rotated to move the plug 32, and in turn
increase or decrease the compression force of spring
34 within the collar 26.
The plunger 22 is sealed at the base of the
air cavity 20 by a seal 42 which permits axial move-
ment of the plunger 22 therealong. The plunger 22
extends downwardly through the gun body 12 from the
air cavity 20 through a stepped bore 44 which leads
into an adhesive cavity 46 having a seal 48 at its
upper end and a plunger mount 50 at its lower end. A
spring 51 carried around the plunger 22 is disposed
within the adhesive cavity 46 and extends between the
seal 48 and plunger mount 50 to hold the seal 48 in
place. This seal 48 and seal 42 aid in guiding the
axial movement of plunger 22 within the gun body 12.
The upper end of the nozzle 14 extends into
the adhesive cavity 46 and is sealed thereto by an
0-ring 52. The nozzle 14 is fixed to the gun body 12
by screws 54. The plunger 22 extends downwardly from
the adhesive cavity 46 and plunger mount 50 into an
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adhesive passageway 56 formed in the nozzle 14 which
terminates at an adhesive discharge opening 57O
Immediately upstream from the adhesive discharge
opening 57, the adhesive passageway 56 is formed with
a conical-shaped seat 58 which mates with the terminal
end 59 of the plunger 22. As discussed below, move-
ment of the plunger 22 relative to the seat 58 con-
trols the flow oE heated hot melt adhesive ejected
from adhesive passageway 56 through its adhesive
discharge opening 57.
The nozzle 14 is also formed with a reduced
diameter portion having external threads 60 which mate
with internal threads formed in a cap 62. As de-
scribed below, the cap 62 mounts the nozzle attachment
18 to the base of nozzle 14 in communication with the
discharge opening 57 of adhesive passageway 56.
The gun body 12 is mounted to the adhesive
manifold 16 by mounting bolts 64. In turn, the
adhesive manifold 16 is supported on a bar 66 by a
mounting block 68 connected to the adhesive mani~old
16 with screws 70O As illustrated at the top of Fig.
1, the mounting block 68 is formed with a slot 72
forming two half sections 73, 75 which receive the bar
. 66 therebetweenu A bolt 74 spans the half sections
:73, 75 of the mounting block formed by the slot 72 and
tightens them down against the bar 66 to secure the
mounting block 68 thereto.
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The adhesive manifold 16 is formed with a
junction box 76 which receives an electric cable 78 to
supply power to a heater 80 and an RTD 82. The heater
80 maintains the hot melt adhesive in a molten state
when it is introduced into the adhesive manifold 16
through an adhesive inlet line 84 from a source of hot
melt adhesive (not shown~. The adhesive inlet line 84
communicates through a connector line 86 formed in the
gun body 12 with the adhesive cavity 46. An O-ring 85
is provided between the gun body 12 and adhesive
manifold 16 at the junction of the adhesive inlet line
84 and connector line 86 to form a seal therebetween.
Operating air for the plunger 22 is supplied through
an inlet line 88 formed in the adhesive manifold 16
which is joined by a connector line 90 to the air
cavity 20. The gun body 12 and manifold are sealed
thereat by an O-ring 89.
The air manifold 17 is formed with an air
inlet line 92 connected to an air delivery passageway
94 formed in the nozzle 14 which terminates in an
annular chamber 95 at the base of the nozzle 14.
O-ring seal 96 forms a fluid-tight seal between the
nozzle 14 and air manifold 17 at the intersection of
air inlet line 92 and air deIivery passageway 94.
Referring now to the bottom of Fig. 1 and to
Figs. 2 and 3, the nozzle attachment 18 of this
invention is shown in detail. The nozzle attachment
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18 is an annular plate having one side formed with a
first or inner surface 102 and an opposite side formed
with a second or outer surface 104 spaced from the
inner surface 102. For purposes of the present
description, the term "inner" refers to a direction
toward the nozzle 14, and the term "outer" refers to a
direction away from the nozzle 14 with the nozzle
attachment 18 mounted to the nozzle 14 as shown in
Fig. 1.
10 ~ ~ boss 106 extends outwardly from the inner
surface 102, and a nozzle tip 108 extends inwardly
from the outer surface 104 in alignment with the boss
106. A throughbore 110 is drilled in the nozzle
attachment 18 between the boss 106 and nozzle tip 108
forming a discharge outlet 109 in the nozzle tip 108
which is coplanar with the outer surface 104 of nozzle
attachment 18. The throughbore 110 has a diameter in
the range of about 0.010 to 0.040 inches, and pref-
erably in the range of about 0.0175 to 0.0185 inches.
An annular, V-shaped groove 112 is formed in
the nozzle attachment 18 which extends inwardly from
its outer surface 104 toward the inner surface 102.
The annular groove 112 defines a pair of sidewalls
114, 116 which are substantially perpendicular to one
another and intersect. In a presently preferred
embodiment, the sidewall 116 is formed at approxi-
mately a 30 angle with respect to the planar outer
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surface 104 of the nozzle attachment 18, and the
sidewall 114 forms the outer surface of the nozzle tip
108. As best shown in Figs. 2 and 3, six air jet
bores 118 are formed in the nozzle attachment 18
be`ween the annular groove 112 and the inner surface
102, preferably at an angle of approximately 30 with
respect to the longitudinal axis of the throughbore
110. The diameter of the air jet bores 118 is in the
range of about 0.010 to 0.040 inches, and preferably
in the range of about 0.017 to 0.019 inches.
The annular groove 112 facilitates accurate
drilling of the air jet bores 118 so that they are
formed at the desired angle relative to throughbore
110 and are precisely located at the desired position
lS along the sidewall lI6 of groove 112. By forming the
sidewall 116 at a 30 angle relative to the upper
surface 102 of nozzle attachment 18, a drill bit (not
shown) can enter the annular groove 112 in the nozzle
attachment 18 at a 30 angle relative to its outer
surface 104, but contact the sidewall 116 formed by
the annular groove 112 at a 90 angle. As a result,
the drilling operation is performed with minimal
slippage between the drill bit and nozzle attachment
18. This allows the outlet 119 of the air jet bores
118 to;be precisely positioned at the sidewall 116 and
oriented~ at the appropriate angles relative to
throughbore 110. In the event of any drift of the
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21-
drill bit as it moves through the nozzle attachment 18
to the inner surface 102, the inlet 121 of the air jet
bores 118 may be slightly out of position but would
nevertheless intersect the annular chamber 95 formed
in nozzle 14.
As shown in Fig. 3, the longitudinal axis of
each of the air jet bores 118 is angled approximately
10~ with respect to a vertical plane passing through
the longitudinal axis of the throughbore 110 and the
centQr of each such bore 118 at the annular groove
112. For example, the longitudinal axis 122 of air
jet bore 118a is angled approximately 10 relative to
a vertical plane passing through the longitudinal axis
124 of throughbore 110 and the center point 126 of
bore 118a at the annular groove 112 in nozzle attach-
ment 18. As a result, the jet of pressurized air 128
ejected from air jet bore 118a is directed substan-
tially tangent to the outer periphery of the through-
bore 110 and the adhesive bead 130 ejected therefrom
as described below.
Referring now to Figs. 1 and 2, the cap 62
is formed with an annular seat 132 which mates with an
annuIar recess 134 formed in the peripheral edge of
~ nozæle attachment 18 which extends inwardly from its
outer surface 104. The cap 62 is threaded onto the
lowermost end of the nozzle 14 so that the boss 106 on
the inner surface ~02 of nozzle attachment 18 extends
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within a seat 136 formed in the base of nozzle 14 at
the adhesive discharge opening 57 of adhesive passage-
way 56. With the nozzle attachment 18 in this posi~
tion, the inlet of each of the air jet bores 118
5communicates with the annular air chamber 95 formed in
the ba~e of the nozzle 1~ at the end of the air
delivery passageway 94. No 0-rings or other seals are
required between the inner surface 102 of the nozzle
attachment 18 and the nozzle 1~ in order to create a
10fluid-tight seal therebetween and between the boss 106
and adhesive discharge opening 57. The nozzle attach-
ment 18 is easily removed and replaced by another
attachment of different size by rotating the cap 62
out of engagement with the nozzle 14.
15The operation of the spray device 10 of this
invention is as follows. Heated hot melt adhesive is
introduced into the adhesive cavity 46 of the gun body
12 through the adhesive inlet line 84. Adhesive flows
from the adhesive cavity 46 into the nozzle 14 through
20the adhesive passageway 56. With the terminal end 59
of the plunger 22 in engagement with the seat 58
formed at the end of the adhesive passageway 56, as
illustrated in Fig. 1, the adhesive is not permitted
. to flow through the adhesive discharge opening 57 of
25the adhesive passageway 56 to the throughbore 110. In
order to retract the plunger 22 and permit the flow of
adhesive into the discharge opening 57, operating air
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is introduced through the operating air line 88 into
the air cavity 20 in the gun body 12. This pressur-
ized air acts against the seal 24 connected to the
plunger 22 which forces the plunger 22 upwardly so
that its terminal end 59 disengages the seat 58 at the
lower end of the adhesive passageway 56. The plunger
22 is rPturned to its closed position by discontinuing
the flow of air to the air cavity 20 allowing the
return spring 34 to move the plunger 22 back into a
seated position.
The flow of hot melt adhesive through the
adhesive discharge opening 57 of adhesive passageway
56 is transmitted into the throughbore 110 of nozzle
attachment 18 from which it is discharged through the
discharge outlet 109 of nozzle tip 108 to form the
adhesive bead 130. At the same time the adhesive bead
130 is formed and ejected from the nozzle attachment
18, pressurized air is directed through the air inlet
line 92, air delivery passageway 94 and air chamber 95
to the air jet bores 118 formed in the nozzle attach~
ment 18.
As best shown in Fig. 2, the air jet bores
118 are angled relative to the longitudinal axis of
the throughbore 110 so that the jets of air 128
flowing therethrough impact the adhesive bead 130
substantially tangent to its outer periphery at a
point spaced below the nozzle tip 108. The air
;. ~ ,
.
131~3~3
-24-
ejected from the air jet bores 118 performs two
functions. First, the jets of air 128 attenuate or
stretch the adhesive bead 130 forming elongated
strands or fibers of hot melt adhesive for deposit
onto a substrate. Additionally, since the air jet
bores 118 are oriented to direct jets of air 128
tangent to the outer periphery of the adhesive bead
130, the adhesive bead 130 and adhesive fib~rs formed
therefrom are rotated in a compact spiral path toward
a substrate. As a result, a controlled pattern of
adhesive having a desired width is obtained on the
substrate.
While the invention has been described with
reference to a preferred embodiment, it will be
understood by those skilled in the art that various
changes may be made and equivalents may be substituted
for elements thereof without departing from the scope
of the invention. In addition, many modifications may
be made to adapt a~particular situation or material to
the teachings of the invention without departing from
the essential scope thereof. Therefore, it is intend-
ed that the invention not be limited to the particular
embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention
will include all embodiments falling within the scope
of the appended claims.
.
'~ '
;
