Note: Descriptions are shown in the official language in which they were submitted.
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MULTIPLE COMPONENT SPRAY GUN
Cross Reference to Parent Application
This application is a continuation-in-part of application
Serial No. 07 / 588,731 filed September 27, 1990 and naming
as the inventor Olin H. Martin.
Technical Field
The present invention generally relates to an improved spray
gun for spray applying multiple components under pressure onto
desired surfaces. More particularly, the invention relates
to the spraying of combined plastic compositions subsequent
to the mixing of at least two, preferably, but not essentially,
chemically reactive, components in a mixing chamber. The spray
gun is air purged to eliminate hardening or solidification of
any residual mixed components in the device upon completion
of spraying. End products of the spray applied compositions
may include polyurethane foams, elastomeric coatings, paints,
highly exothermic mixtures, thermosetting resin formulations,
and the like. The preferred mode in utilizing the spray gun
of this invention is via the spraying of polyurethane foams
onto desired substrates.
Background Art
The prior art describes a number of spray guns of the various
types for spraying plural component materials in which the
components are mixed prior to discharge or subsequent to
discharge. For example, U.S. Patent No. 3,837,757 shows an
air actuator controlled by the trigger which operates the flow
control ball valves. U.S. Patent Nos. 3,806,030 and 3,752,398
disclose an apparatus for spraying plastics in which cleaning
fluid is injected into the head by manually controlled valves
after the spraying cycle. Air purge of the spraying apparatus
is shown in U.S. Patent No. 3,146,950. Another patent, namely
U.S. Patent No. 3,920,188 discloses a mode to disperse the
polyurethane without the use of compressed air for atomizing
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or purging. U.S. Patent No. 3,708,123 teaches about an airless
spray apparatus permitting solvent and material flow into the
spray apparatus involving a low pressure type operation using
a novel mixing valve mechanism, which differs from the present
invention. A rotary plug valve which is solenoid operated is
shown in U.S. Patent No. 2,659,628.
The description of a compressed air gun for spraying plural
component coating materials is outlined in U.S. Patent No.
3,837,023. This approach depends upon compressed air to atomize
the mixed component materials ejected from the gun in a single
mixing action, and to shape the spray pattern projected from
the gun. During the spraying process the ejection orifice can
not move axially or laterally from its cooperative association
with the jets of air or the desired spray pattern will not be
formed resulting in large droplets and/or uneven particle
distribution. The orifice has to be stationary at all times,
and the mixing depends upon the compressed air supply, which
it cannot exceed. Additionally, U.S. Patent No. 2,989,242,
U.S. Patent No. 3,245,661, U.S. Patent No. 3,429,508, U.S. Patent
No. 3,795,364, U.S. Patent No. 3,837,575 and U.S. Patent No.
4,471,887 are all describing different functioning spray devices
of different design.
Disclosure of Invention
The present invention provides a multiple component spray
gun of improved design for spraying plural components generally
described above The concept of the spray gun involves a gun
body and a nozzle, a rotatable ball passage valve including
a ball with internal porting in a general Y-configuration with
two opposing lateral inlet passages, which define an integral
arrangement of the passages aligned at a 45 degree angle to
connect with the valve chamber and a cylindrical outlet bore
extending perpendicular to the two opposing passages with the
ball positioned in a totally enclosed resilient resinous
packing material within a metal housing of the gun body. The
preferred packing material is formed from polytetrafluoroethylene
commonly referred to under the trademark Teflon. The ball inlet
passages are communicating with four inlet passages from the
exterior of the metal housing by rotating the ball selectively
in 90 degree increments to either receive material flow or an
air purge through the two inlet passages of the ball into the
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valve chamber then exiting through the nozzle. The encapsulating
Teflon (trademark) packing has four bores and four steel rings
to prevent cold flow at the apertures of said bores interposing
the Teflon ~trademark) packing and the metal housing. Adjustable
means are provided for applying a compressive load to the Teflon
(trademark) packing to cause it to sealingly engage the inner
walls of the chamber and the exterior of the ball member. The
adjustable means include a rigid circular gland member closely
received in the bore and positioned to extend transversely
thereof. The gland member is mounted in direct engagement with
the packing and a circular opening in the gland member surrounds
the opening stem. Disk spring means are positioned on the gland
member on the side opposite the packing. Closely received in
the bore outwardly of the disk spring means is a packing nut
having an inner surface engaging the disk spring means. The
packing nut means can be tightened to move toward the rigid
gland member, thus compressing the disk spring means and apply
a compressive load to the packing. An optional second rigid
gland member can be employed to supply additional compression.
The flow control ball is rotated by means of a double acting
pneumatic cylinder. The cylinder or air motor is connected
to the ball and both reciprocate and rotate. A portion of the
cylinder is provided with a helical slot with a movable air
shaft blade. Therefore, as the air shaft blade reciprocates
in the chamber under the influence of air pressure directed
to one side and the other side of the blade, the blade will
rotate causing the ball to rotate through an appropriate linkage.
The exact details of the linkage connection and the degree of
movement for the air shaft blade may vary dependent upon the
type construction of the rotatable ball. The air is directed
through port holes in the air motor to one side or the other
side of the air shaft blade by means of a trigger and microswitch
arrangement on the gun.
Most, but not all, multiple component guns mix liquid
components only once and material back flow is a common problem
The present invention differs from prior art and method in that
it distributes material through the passages of the Y-configura-
tion prior to the novel multiple mixing action and material
back flow is virtually eliminated. Additionally, the gun design
makes it possible to exchange mixing chamber components without
the need to dismantle the gun body. Furthermore, the concept
of a double acting pneumatic cylinder in connection with the
design of a spray gun apparatus has not been formerly employed.
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Description of the Drawings
FIG. 1 is a side elevational view of the multiple component
spray gun according to the invention;
FIG. 2 is a top plan view and partially diagrammatic view
of the gun seen in FIG. 1;
FIG. 3 is a side elevational view of the double acting
pneumatic cylinder;
FIG. 4 is a cross sectional view of the cylinder seen in
FIG. 3;
FIG. 5 is a top plan view and diagrammatic view of the
rotatable ball for a two component application with an air purge;
FIG. 6 is a top plan view and a diagrammatic view of the
rotatable ball for a three component application with an air
purge;
FIG. 7 is a top plan view of the premixing plate and ejection
orifice;
O FIG. 8 is an exploded view showing certain components of
the ball valve assembly;
FIG. 9 is an enlarged partial cross-sectional view similar
to FIG. 1;
FIG. 10 is a view similar to FIG. 9 but showing a different
alignment of the internal passages.
Referring now to FIGS. 1 and 2 of the drawings in greater
detail, spray gun 10 comprises a spray head 11 and a nozzle
40, with said spray head 11 consisting of a metal housing 37
with means 11a connected to a double acting pneumatic cylinder
or air motor 12, a handle or pistol grip 13 extending at an
angle from cylinder 12 and a trigger 14. The spray head 11,
the handle 13 and the trigger 14, as well as other suitable
parts of spray gun 10, are fabricated from materials which are
chemically inert with respect to the components being mixed
and may include aluminum and aluminum alloys, steel and copper
alloys or any suitable wear resistant plastic materials.
Conduits 15 and 16 each supply a different liquid to spray
head 11, namely A and B components across a rotatable ball
passage valve 17. The two components are combined at the
juncture of an internal porting arrangement in the general
Y-configuration then ejected into the spiral mixing chamber
19 (FIG. 7) inside gun nozzle 40 with the subsequent discharge
of the material through orifice 20 by means of bore 40a. The
rotatable ball passage valve 17 is returned to a non-spraying
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position automatically by releasing the trigger 14 of the spray
gun 10 and reversing the mechanism to an air purge position
via inlets 21 and/or 22 by means of the double acting pneumatic
cylinder 12 as shown in FIGS. 2 and 3. Compressed air is
introduced through hose 23 into the spiral mixing chamber 19
through air inlets 21 and/or 22 for the purpose of cleaning
the front end of spray gun 10. In this way, the accumulation
of deposits of sprayed material about the outlet of the spray
gun is avoided. The pneumatic air cylinder 12, the ball passage
valve 17 and the appropriate linkage all reciprocate and rotate
by actuating the mechanism with compressed air supplied by hose
24.
The rotatable ball passage valve 17 is positioned within
a spherical cavity inside an encapsulating Teflon (trademark)
packing 25, which is secured by four steel rings 26 (FIG. 8)
to prevent distortion (cold flow). The connecting stem 27 is
embedded in a packing nut member 28, with a rigid circular gland
member 29 closely received in the bore of the metal housing
37, in direct engagement with the Teflon (trademark) packing
25, and rotatable ball passage valve 17 with disk spring means
29a positioned on the ball stem between gland member 29 and
packing nut member 28, having an inner surface 44, engaging
said disk spring means 29a. The stem 27 connects with a hollow
tubular sleeve 30 extending forwardly from air motor 12. The
actuating trigger of proper length is pivotally secured to gun
body 10 by bolt 31. The fingers of a person manipulating the
spray gun may easily grip the trigger 14 to pivot it toward
the pistol grip or handle 13, which depresses valve plunger
32 and activates air valve 33 with the air being directed to
one side or the other side through air inlet ports 34 into air
motor 12 causing the air shaft blade 35 in the helical slot
36 to reciprocate and rotate in 90 degree increments as shown
in FIG. 4. The withdrawal of the air from air motor 12 is
accomplished by the release of trigger 14.
In the drawings in FIGS. 5 and 6 two configurations of
mechanism are shown with the rotatable ball passage valve 17
separated from the metal housing 37 by the encapsulating Teflon
(trademark) packing 25 with bores 38 in the packing to allow
for an alignment with the rotatable ball valve's inlet passages.
FIG. 5 is in the air purge mode with the air exiting via the
Y-configuration 18 (not shown in this drawing) - the A and B
components are prevented from entering through the two opposing
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inlet passages. A 90 degree rotation of the ball passage valve
17 will reverse the process by blocking off air flow and
injecting the pressurized A and B components through the internal
passages across the Y-configuration 18. FIG. 6 shows the
injection of an A, B and C component under pressure entering
through the inlet passages of the rotatable ball valve 17, with
the air in the "off" position. A 45 degree rotation of the
ball passage valve 17 will reverse the process according to
the aforementioned mode of operation.
However, the present invention is not restricted to a two
component or a three component spray mechanism with an air purge,
but may involve additional multiple liquid components using
different rotatable ball valve configurations with different
internal passageway configurations all properly mixed and spray
applied to the desired substrates. The components may be
distributed by means of a low pressure or a high pressure type
application.
Referring to FIG. 7 an improved gun nozzle design 40, over
prior art, is shown involving a multiple mixing action. The A
and the B components are forced under pressure into the inlet
passages of the Y-configuration 18 (not shown in this drawing),
and the initial mixing occurs at the juncture of the passages.
The combined material is forced onto the premixing plate 39
within gun nozzle 40, which is attached to offset grooves 41
within mixing chamber 19, and further mixing is taking place,
followed by the material injection through the perpendicular
grooves 42 within said mixing chamber 19, with the final material
mixing occurring through the means of a spiral flow pattern
within the conical cavity of the chamber 19, and the subsequent
material discharge at the ejection orifice 20 via central bore
40a. Referring to FIGS. 1 and 2 of the drawings, the
aforementioned mechanism involving a multiple mixing action
via the rotatable ball passage valve 17, is shown from different
angles.
In the drawings in FIGS. 8 and 9 the rotatable ball valve
assembly 17, is shown with the general Y-configuration
passageways 18, merging in the trunion 43. Four steel rings
26, are closely received at the apertures of bores within the
Teflon (trademark) packing 25. The rotatable ball passage valve
17, has a cylindrical operating stem 27 extending axial outwardly
the metal housing 37, to a position exterior of said metal
housing 37 and terminating within bore 44 of packing nut member
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28, with means of said packing nut member 28 and bore 44 to
move toward the rigid gland member 29 through the disk spring
means 29a, and to apply a compressive force to the Teflon
(trademark) packing 25. It should be noted that the rigid gland
member 29, and the disk spring means 29a, have internal openings
45 and 46, which are only slightly larger than the cylindrical
stem 27. The number and stacking arrangement of the metallic
disk spring means 29a can be varied and they are positioned
in an alternating facing relationship as shown in FIG. 8. The
drawing in FIG. 10 discloses an alternate passageway arrangement
in the general T-configuration 47.
In view of this disclosure many modifications of this
invention will be apparent to those skilled in the art. It
is intended that all such modifications which fall within the
true scope of this invention be included within the term of
the appended claims.
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