U.S. patent number 3,661,679 [Application Number 05/070,426] was granted by the patent office on 1972-05-09 for adhesive applicator for plywood patching machine.
This patent grant is currently assigned to Lockwood Technical, Inc.. Invention is credited to Raymond Thomas Law.
United States Patent |
3,661,679 |
Law |
May 9, 1972 |
ADHESIVE APPLICATOR FOR PLYWOOD PATCHING MACHINE
Abstract
A conventional plywood patching machine is modified to permit
accurately controlled application of adhesive directly to the
interface between patch and ply. Nozzle applicators are built into
the hold-down ring of a patching machine in a manner that requires
minimum modification of other parts of the machine. A particularly
effective nozzle and valve structure is described, responsive to
pressure pulses and effectively compensating pressure and viscosity
variations. A pulsed air jet spreads the adhesive. A release agent
is applied via an airstream to prevent buildup of adhesive on the
mechanism.
Inventors: |
Law; Raymond Thomas (Salinas,
CA) |
Assignee: |
Lockwood Technical, Inc. (Sand
City (Seaside), CA)
|
Family
ID: |
22095217 |
Appl.
No.: |
05/070,426 |
Filed: |
September 8, 1970 |
Current U.S.
Class: |
156/356; 118/411;
118/685; 144/346; 156/98; 156/390; 156/513; 156/524; 156/529;
156/548; 239/92; 239/586; 156/578; 239/417.3; 144/2.1;
144/24.16 |
Current CPC
Class: |
B27G
11/005 (20130101); B27G 1/00 (20130101); Y10T
156/1798 (20150115); Y10T 156/1352 (20150115); Y10T
156/1374 (20150115); Y10T 156/1304 (20150115); Y10T
156/1724 (20150115) |
Current International
Class: |
B27G
1/00 (20060101); B27G 11/00 (20060101); B32b
035/00 (); B27f 004/00 (); B05b 001/08 () |
Field of
Search: |
;144/31B,315R,317,2M
;239/88-92,63,110,417.3,584,586 ;118/2,7,8,DIG.9,410,411
;156/98,228,356,390,513,514,524,529,531,546,548,578 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Ansher; Harold
Claims
I claim:
1. In combination with a plywood patching machine having a
hold-down ring with an aperture and a working face surrounding the
aperture for clamping a ply, the machine having a cutting die
working in the aperture in the hold-down ring for punching out
defective ply sections and means for inserting sound sections in
the ply while clamped by the ring;
a nozzle assembly rigidly mounted on the hold-down ring and
including a nozzle tip with a nozzle orifice substantially at the
line of intersection of the working face and the aperture of the
ring,
conduit means for supplying adhesive to the nozzle assembly,
and means for ejecting liquid adhesive from the nozzle orifice in
timed relation to the operation of the machine to adhere the sound
section in the ply.
2. The combination defined in claim 1, and in which
said hold-down ring has a bore on an axis that is in a generally
radial plane and is oblique with respect to the axis of the
ring,
and said nozzle assembly is mounted on an outer peripheral portion
of the ring adjacent the bore and includes a nozzle tip portion
extending into the bore with said nozzle orifice at the end of the
tip portion.
3. The combination defined in claim 1, and in which said nozzle
assembly includes
structure forming a nozzle chamber communicating with the nozzle
orifice, and a coaxial piston chamber rearward of the nozzle
chamber and communicating with said conduit means,
a piston member including a piston in the piston chamber and a
coaxial plunger projecting forward into the nozzle chamber, the
piston member being axially slidable between a normal rearward
position and a forward position,
and adhesive metering mechanism for supplying adhesive from said
conduit means to the nozzle chamber forward of the plunger,
said adhesive ejecting means including
means for applying to said conduit means pressure pulses in timed
relation to the operation of the machine to drive the piston member
forward and thereby expel adhesive from the nozzle chamber through
the nozzle orifice.
4. The combination defined in claim 3, and in which said metering
mechanism includes
passage structure communicating between said conduit means and said
nozzle chamber,
and a normally closed valve connected in series with said passage
structure and including means acting to open the valve after the
start and to close the valve before the end of said forward
movement of said piston member.
5. The combination defined in claim 4, and in which said metering
mechanism includes also a manually adjustable flow limiting valve
connected in series with said passage structure and with said
normally closed valve.
6. The combination defined in claim 1, and including
structure forming a second nozzle orifice closely adjacent the
first said nozzle orifice and directed obliquely toward the axis
thereof,
and means for ejecting air from the second nozzle orifice in timed
relation to said adhesive ejection from the first said nozzle
orifice.
7. The combination defined in claim 6, and including
means for dispersing into said air prior to its said ejection a
finely divided liquid releasing agent.
8. The combination defined in claim 7, and in which
said releasing agent is silicone oil.
9. The combination defined in claim 1, and including
structure forming at least one orifice opening through the aperture
wall of said hold-down ring in a generally radial direction,
and means for ejecting through the last said orifice air containing
a finely divided releasing agent.
10. The combination defined in claim 9, and in which
said releasing agent is silicone oil.
Description
This invention has to do with the known operation in the
manufacture of plywood by which a small defective area of a single
ply is removed by a punching operation and is replaced by a sound
piece that accurately fits in the punched hole. During such a
patching operation, adhesive may be applied to the inserted patch
in minimum quantity required to hold it in position until the
patched ply has been assembled with other plies to form a completed
sheet of plywood.
The present invention provides particularly effective mechanism for
applying adhesive in suitable quantity and in accurately defined
relation to an inserted patch. The mechanism of the present
invention is integrated with the usual punching apparatus in a
manner which insures accurate and reliable operation, while
requiring remarkably simple and economical modification of already
existing machines.
The usual patching machine employed in the plywood industry
comprises upper and lower operating heads rigidly related by a
heavy U-shaped frame which is built around a table on which the
operator lays a single veneer sheet. He positions the defective
area of the sheet under a vertically oriented cutter die in the
upper head. By tripping a foot switch he causes a hold-down ring to
descend and clamp the veneer sheet firmly on the table, followed by
a cutter die which shears out a two by four inch section, usually
of modified elliptical shape. An ejection plunger within the die
ejects the bad section, which is carried away by suction. As the
die rises on the return stroke, a similar opposed cutter rises from
the lower head, cutting a patch from a clear strip of makeup veneer
and pressing the patch into place in the large sheet with a
friction fit. Finally, the hold-down ring rises, releasing the
sheet to be repositioned for another patch.
In accordance with the present invention, adhesive is applied via
one or more applicator nozzles which are mounted directly on the
hold-down ring and project obliquely through the body of the ring
to the working edge immediately adjacent the clamped ply. Upon
withdrawal of the cutting die and automatic insertion of the sound
patch, a drop of adhesive is applied directly by each nozzle to the
interface between the patch and the surrounding ply. That adhesive
is then preferably distributed over the desired area by an air
blast delivered through nozzle structure incorporated directly in
the adhesive applicator or built into the hold-down ring in
positively defined spatial relation to the nozzle orifice. Two such
applicator nozzle assemblies are preferably mounted on opposite
sides of the hold-down ring, although as many as four can be
provided if desired.
Each operation of the adhesive applicators is coordinated with the
machine operation by control mechanism which may be largely of
conventional form.
Another aspect of the invention provides coordinated nozzle and
valve structure by which a readily adjustable and accurately
definable quantity of adhesive is applied during each cycle of
operation. Although that structure is superficially similar to
previously known structures, such as that shown in U.S. Pat. No.
3,315,899, for example, the present valve is particularly well
adapted for metering small amounts of adhesive. Moreover, the
adjusting mechanism inherently provides substantial compensation
for normal variations in input pressure and in viscosity of the
adhesive.
Primary advantages provided by the invention are the accurate
metering of adhesive applied during each cycle and the reliable
positioning of the applied adhesive with direct relation to the
hold-down ring of the machine and hence in closely defined relation
to the patch itself.
A further advantage of the invention is that the nozzle assemblies
can readily be adapted for application of hot melt adhesive, by
providing heaters and thermostats in the assemblies to maintain
them and the hold-down ring at suitable elevated temperature.
A further aspect of the invention effectively prevents buildup of
adhesive on the patching mechanism, particularly on the cutting
die, the ejection plunger and the hold-down ring itself. That is
accomplished by applying a suitable release agent, such as silicone
or lecithin, for example, to those elements by means of an air
stream which is preferably projected from orifices in the hold-down
ring in timed relation to the action of the patching mechanism. The
same air and the same pulsing mechanism can usually be used for
that purpose as for spreading the drop of adhesive, but separate
airstreams and timing controls may be provided if desired.
A full understanding of the invention, and of its further objects
and advantages, will be had from the following description of
illustrative mechanism for carrying it out. The particulars of that
description, and of the drawings which form a part of it, are
intended only as illustration and not as a limitation upon the
scope of the invention.
In the drawings:
FIG. 1 is a schematic fragmentary side elevation representing a
patching machine in which the invention is embodied;
FIG. 2 is a plan representing two injection nozzles assembled with
a typical hold-down ring in accordance with the invention;
FIG. 3 is a section at enlarged scale on line 3--3 of FIG. 2;
and
FIG. 4 is a section on line 4--4 of FIG. 3.
In FIG. 1 the machine frame is indicated schematically at 10 with
upper head 12 and lower head 14. A wood ply is indicated at 16 in
operating position between the two heads on the supporting table
18, the thickness of the ply being greatly exaggerated for clarity
of illustration. The punching die 20 is reciprocated along the
vertical axis 21. It works in the fitting aperture 22 (FIG. 2) of
hold-down ring 24, and enters a corresponding clearance opening in
lower head 14. After a punching operation, the discarded section of
ply 16 is removed and is replaced by a sound patch, all by
automatic mechanism of known construction, which need not be
described in detail. As shown in FIG. 1 a sound patch 30 has been
inserted in the plane of ply 16.
In accordance with the present invention, injection nozzle
assemblies 40 and 42 are mounted in fixed relation directly on
hold-down ring 24 in the general orientation shown schematically in
FIG. 1, in position to place adhesive directly upon the interface
between patch 30 and ply 16.
A typical hold-down ring 24 is shown in plan in FIG. 2, comprising
essentially a flat plate 25 with central aperture 22 of modified
elliptical or biconvex lunar shape. The side slots 26 receive bolts
by which the ring is mounted on the mechanism of the head assembly.
Aperture 22 is surrounded by a boss 23 on the lower face of plate
25, and that boss carries the working face 36 (FIG. 3) by which the
ply is clamped to table 18 during the patching operation. In
accordance with the present invention the edge of plate 25 is cut
away on each side to form an oblique mounting surface 32. A bore 34
is formed in that mounting surface on an axis 35 which passes
substantially through the intersection of the side wall of die
aperture 22 and the lower working face 36 of the hold-down ring.
Axis 35 lies in a plane that is generally radial with respect to
the axis 21 of the hold-down ring, and is oblique with respect to
that axis and perpendicular to mounting surface 32.
The typical nozzle assembly 40 shown in FIGS. 3 and 4 has a
transverse mounting face 44 from which projects the nozzle tip 46.
Assembly 40 is mounted by the screws 33 with face 44 flatly
engaging the oblique mounting surface 32 of the hold-down ring and
with nozzle tip 46 projecting axially into bore 34. The nozzle tip
is designed with a conical end which fits just back of the dihedral
angle formed by the wall of die aperture 22 and the lower surface
36 of the ring, so that the nozzle avoids any interference either
with the die or with the clamped ply. At the same time, the nozzle
delivery orifice 48 is directed accurately toward the junction
between patch 30 and the surrounding ply 16.
The main body of nozzle assembly 40 has a through bore 50, which is
closed at its rearward end and partially closed at its forward end
by the end plates 51 and 57, respectively. The forward portion of
bore 50 is reduced in diameter by the fixedly mounted tip member 54
and valve member 56, in which the coaxial bore 55 terminates
forwardly in nozzle orifice 48. The piston member 60 comprises the
piston 62, which works in the piston chamber 52 formed by the
rearward portion of bore 50, and the forwardly projecting plunger
64, which works in bore 55 and acts as valve element. Plunger 64
has a peripheral valve channel 66 and a communicating axial bore 68
which opens forwardly into bore 55. Adhesive is excluded from the
portion of main bore 50 forward of piston 62 by the seals 63 and
65. Piston member 60 is yieldingly urged rearwardly by the strong
spring 58 to the normal retracted position shown in FIG. 4 and
defined by the stop post 59. Pressure application to piston chamber
52 drives the piston member forward against the force of spring 58
to the projected position shown in FIG. 3, defined in the present
illustrative structure by contact of the forward end of plunger 64
with the nozzle tip.
Adhesive from conduit 84 is directed by the plug 71 through the
replaceable filter element 72 to the vertical bore 74. The upper
end of bore 74 communicates directly with piston chamber 52. Its
lower end communicates via the needle valve 70 with the peripheral
channel 76 in valve member 56. A plurality of radial holes 78
connect that channel with axial bore 55, forming with plunger
channel 66 a valve designated by the numeral 80. The axial position
of the holes 78 is forward of valve channel 66 when piston member
60 is in its normal retracted position as in FIG. 4, and is back of
channel 66 when the piston member is fully projected as in FIG. 3.
Hence in both extreme positions of piston member 60 nozzle orifice
48 is isolated by valve 80 from supply conduit 84. However, during
movement of piston member 60 in either direction valve 80 opens
momentarily, for a time determined by the passage dimensions and
the rate of the piston movement. During the brief open periods of
valve 80, flow through it is limited by needle valve 70, which is
adjustable manually to control the adhesive feed.
Liquid adhesive is maintained in a supply tank, indicated
schematically at 82 (FIG. 1), from which it is supplied via the
flexible conduits 84 to the two nozzle assemblies in parallel. When
hot melt adhesive is to be used, as is preferred, the tank and
conduits are heated electrically in conventional manner. Each
nozzle assembly is independently heated, as by a resistive heater
86 set into the body of the assembly and controlled by a
thermostatic probe 88 which maintains the nozzle assembly and the
adjacent portions of ring 24 at suitably elevated temperature.
Electrical connections are indicated at 89.
Supply tank 82 typically incorporates a pump mechanism, indicated
schematically at 90, for producing in conduit 84 a sharp pressure
pulse in response to an electrical control signal supplied via the
line 92. Such mechanism may, for example, be of the general form
described in U.S. Pat. No. 3,348,520, issued on Oct. 24, 1967 to
Glynn H. Lockwood and assigned to the same assignee as the present
application. An electrical signal for control of mechanism 90 can
be generated in known manner, as by a microswitch 94 mounted in
position to be actuated by mechanical movement of a suitable member
of patching machine 10 after patch 30 has been inserted in the
deflective ply 16. The derivation of such a signal is well known in
and of itself, and is not a part of the present invention.
Upon delivery of a pressure pulse via conduits 84 to the two nozzle
assemblies 40 and 42, the two pistons 62 are driven forward
simultaneously. As each valve 80 opens momentarily, a pulse of
adhesive is supplied to the small nozzle chamber 96 formed in bore
55 forward of the plunger. After a definite travel increment by the
plunger valve 80 closes, isolating chamber 96 from the adhesive
source. As piston 62 continues to be driven forward, the adhesive
in chamber 96 is positively ejected from nozzle orifice 48. Hence
the mechanism deposits a small but accurately reproducible volume
of adhesive directly at the interface between ply and patch. As the
pressure pulse in conduit 84 subsides, piston 62 is returned by
spring 58 to its normal position. During most of that piston
retraction valve 80 is closed, so that plunger 64 positively
withdraws adhesive from the nozzle orifice and chamber, preventing
leakage from the nozzle during the quiescent period before the next
cycle. The momentary opening of valve 80 during piston retraction
does not significantly affect that plunger action, since the
differential pressure across the valve is small. That differential
pressure may be in either direction, depending upon the action of
control pump 90 (FIG. 1) and upon the detailed design of the valve
and nozzle assembly.
A particular advantage of the described valve structure is the ease
and accuracy with which the amount of adhesive deposited during
each cycle of operation may be determined by adjustment of control
needle valve 70. Variations in the amplitude of the pressure
pulses, and also variations in viscosity of the adhesive due to
such factors as temperature, tend to be compensated by inherent
action of the mechanism. For example, an increase in the average
pressure during a pulse causes the flow rate past control valve 70
to increase correspondingly; but piston 62 is also driven forward
more quickly, so that valve 80 remains open for a shorter period.
Similarly, increased viscosity of the adhesive reduces the flow
rate past valve 70, but also reduces the rate of adhesive flow to
piston chamber 52 and thereby slows the piston movement. With
appropriate dimensioning of the various passages, highly effective
compensation can be obtained, so that the delivery per cycle is
remarkably accurate and stable.
It is sometimes advantageous to spread the applied adhesive over a
wider area than that on which it is initially deposited by the
nozzle. The present invention accomplishes that by means of an air
jet that is produced by air nozzle structure directly related to
the adhesive nozzle. The spatial relation of the air jet to the
deposited adhesive is then reliably maintained. A particularly
simple and effective air nozzle is formed by providing clearance
between the conical outer surface of the adhesive nozzle tip
portion and the surrounding body of the hold-down ring. As shown in
FIGS. 3 and 4, such clearance produces a conically tapered annular
chamber 100 with nozzle orifice 101. That orifice concentrates the
air jet at the apex of the cone, which is on axis 35 of the
adhesive nozzle, and is spaced axially approximately at the work
surface. Air may be supplied to chamber 100 via passages formed in
the body of the hold-down ring, as by drilling intersecting holes
and plugging portions not used. Such passages are indicated
somewhat schematically at 102, with side passages 104 leading to
each of the chambers 100. A source of pressure pulses of air is
indicated schematically in FIG. 3 at 106, with output 105
communicating with flexible conduits 107 leading to suitable
fittings on the hold-down rings. That structure is omitted from
FIG. 1 for clarity of illustration.
Pulse source 106 may be of any suitable type that produces air
pulses in uniform timed relation to the adhesive pressure pulses,
preferably immediately after the latter. For example, compressed
air may be supplied via a solenoid valve that is opened momentarily
in response to an electrical control pulse. The control pulse may
be derived from switch 94 (FIG. 1), the desired time delay being
provided by suitable design of the valve solenoid, for example. Or
a separate switch similar to switch 94 may be mounted with
independent adjustment relative to the mechanism of the patching
machine.
In accordance with a further aspect of the invention, a fine mist
of a suitable liquid releasing agent, such as a silicone oil, for
example, is dispersed in the air delivered to passages 102. That is
typically accomplished by inserting in the line 105 a conventional
mechanism, indicated schematically at 108, such as is employed in a
standard pneumatic oiler for dispersing a mist of oil into an
airstream. When a releasing agent is thus introduced into the
airstream expelled from air nozzle orifice 101, the releasing agent
forms a film on the hold-down ring, the cutting die and other metal
working parts of the patching machine, and prevents buildup of
adhesive on those parts. A wide variety of substances are known to
have suitable releasing properties for preventing such buildup. The
present invention provides mechanism for effectively and
conveniently depositing such known materials directly at the
desired site.
It is sometimes desirable to distribute the air carrying the
dispersed releasing agent somewhat more widely than through the
nozzle orifice 101 associated directly with the adhesive
applicator. For that purpose the passages 102 may be extended any
desired distance in the body of the hold-down ring, with side
passages 109 at spaced intervals opening into the main aperture 22
through special air nozzles 110 (FIG. 3). If preferred, air
carrying the releasing agent may be distributed exclusively through
such special nozzles, the air supplied to nozzle chamber 100 being
taken directly from pulse source 106 without addition of releasing
agent. For that purpose a separate set of air passages similar to
passages 102 may be provided in the hold-down ring to serve air
nozzles 110.
* * * * *