U.S. patent number 3,604,391 [Application Number 04/825,281] was granted by the patent office on 1971-09-14 for apparatus for applying ink to holes.
This patent grant is currently assigned to Western Electric Company, Incorporated. Invention is credited to Joseph C. Mallia, John C. Walz.
United States Patent |
3,604,391 |
Mallia , et al. |
September 14, 1971 |
APPARATUS FOR APPLYING INK TO HOLES
Abstract
Material is applied to holes in a workpiece by transfer pins.
The material is first introduced into holes in a template arranged
in a pattern corresponding to the holes in the workpiece. Free ends
of the transfer pins are then moved through the holes in the
template to transfer the material to the holes in the workpiece.
The material may then be pulled through the holes by a vacuum.
Inventors: |
Mallia; Joseph C. (Colonia,
NJ), Walz; John C. (Bloomfield, NJ) |
Assignee: |
Western Electric Company,
Incorporated (New York, NY)
|
Family
ID: |
25243595 |
Appl.
No.: |
04/825,281 |
Filed: |
May 16, 1969 |
Current U.S.
Class: |
118/50; 118/215;
118/243 |
Current CPC
Class: |
H05K
3/4053 (20130101); H05K 2203/0195 (20130101); H05K
2203/0338 (20130101); H05K 2201/09981 (20130101); H05K
2203/082 (20130101) |
Current International
Class: |
H05K
3/40 (20060101); B05c 001/02 () |
Field of
Search: |
;118/50,243,211,63,263,215 ;101/103,41 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McIntosh; John P.
Claims
What is claimed is:
1. An apparatus for applying catalytic ink to the periphery and
walls of holes formed in a predetermined pattern in a printed
wiring board, said apparatus comprising:
a reciprocable carriage for receiving the printed wiring board;
a perforated plate having holes formed therein in a pattern
corresponding to the pattern of the holes in said printed wiring
board;
applicator means for introducing the catalytic ink into the holes
formed in said perforated plate;
means for moving said reciprocable carriage to a position adjacent
said perforated plate;
positioning means responsive to movement to said adjacent position
for accurately positioning said reciprocable carriage so that said
holes in said printed wiring board are in registration with the
corresponding holes in said perforated plate;
a vertically movable member;
a plurality of transfer pins mounted vertically in said vertically
movable member and aligned with said holes in said perforated
plate; and
lifting means for raising the vertically movable member so that the
upper ends of said plurality of pins move through the holes of said
perforated plate to pick up the catalytic ink introduced therein
and apply the ink to the periphery and walls of said holes in said
printed wiring board.
2. The apparatus claimed in claim 1; comprising in addition:
vacuum means located above the reciprocable carriage for briefly
applying a partial vacuum to produce a pulse of airflow through
said holes in said printed wiring board so that said catalytic ink
spreads smoothly about and within said holes in said printed wiring
board.
3. The apparatus claimed in claim 1 wherein said applicator means
comprises means for applying catalytic ink across the entire
perforated plate while said reciprocable carriage is being moved to
said adjacent position, comprising in addition:
squeegee means for removing said catalytic ink from said perforated
plate while leaving a predetermined amount of said catalytic ink in
said holes in said perforated plate.
4. The apparatus claimed in claim 3; comprising in addition:
vacuum means located above the reciprocable carriage for briefly
applying a partial vacuum to produce a pulse of airflow through
said holes in said printed wiring board so that said catalytic ink
spreads smoothly about and within said holes in said printed wiring
board.
5. The apparatus claimed in claim 1, wherein said plurality of pins
are mounted such that their upper ends project partly into but
below the top of the corresponding holes in said perforated plate
when said vertically movable member is at its lowest position to
define a cavity for receiving a predetermined volume of said
material.
6. The apparatus claimed in claim 5; comprising in addition:
vacuum means located above the reciprocable carriage for briefly
applying a partial vacuum to produce a pulse of airflow through
said holes in said printed wiring board so that said catalytic ink
spreads smoothly about and within said holes in said printed wiring
board.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to apparatus for applying material to holes
formed in a workpiece, and more particularly, to apparatus for
applying adhesive catalytic ink to the periphery and walls of holes
formed in a printed wiring board.
In manufacturing printed wiring assemblies on a production basis,
the making of reliable electrical connections between the printed
wiring and the component lead wires which extend through the holes
in the printed wiring board has been a continuing source of
difficulty. This is particularly true when the printed wiring is
produced by the successive steps of applying catalytic ink through
the silk-screening technique and then plating copper onto the ink.
Where the hole has a rounded or chamfered edge, it has been found
that silk screening does not in all instances give a
well-controlled coating of ink to the periphery of the hole. As a
result, special techniques have been developed for treating holes,
so that both the periphery and a portion of the walls of the holes
will be adequately covered.
2. Description of the Prior Art
One method used to coat the periphery and walls of the holes
involves the application of ink onto the top surface of the printed
wiring board using an array of resiliently mounted pins to which
ink has been applied. The array has a pattern corresponding to that
of the holes in the printed wiring board, and the tips of the pins
are usually rounded or tapered to conform to the edges of the
holes. This technique has a disadvantage in that it is difficult to
control accurately the amount of ink which adheres to the
applicator tip; furthermore, when the ink is fairly viscous, some
of the ink is pulled upward when the applicator is raised away from
the hole and this ink will occasionally fall back unevenly about
the hole.
Another technique which has been taught for applying material to
the periphery of holes involves spreading the material across the
surface of the printed wiring board, and then removing the excess
using a squeegee so that only the quantity which was introduced
into the holes remains. This technique is suggested primarily for
use with nonconducting solder resist material. It would be
disadvantageous for use with catalytic adhesive ink since even
minute traces of ink remaining on the surface of the board would
result in copper deposition and possible high leakage between the
printed wiring lines.
Other apparatus previously utilized or taught for applying ink to
the periphery and walls of holes has involved a number of
successive steps by the operator, has not provided optimum control
of the amount of ink applied, or has involved apparatus not readily
suited to high production rates.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an apparatus for
applying controlled quantities of adhesive material to holes formed
in a workpiece.
Another object of this invention is to provide an apparatus for
applying material that aligns the material applying elements
accurately with respect to the holes in the workpiece.
A further object is to provide means for applying material which
will not contaminate the area surrounding the desired
application.
With these and other objects in view, this invention contemplates
providing a template having holes therein for receiving material
and facilities for displacing transfer pins through the holes and
into close proximity with a workpiece to transfer the material from
the holes in the template to predetermined holes in the
workpiece.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be more clearly understood by reference to the
following detailed description of an embodiment thereof, in
conjunction with the accompanying drawing, in which:
FIG. 1 is a perspective view of an apparatus for applying ink to
holes in a printed wiring board, in the position for loading and
unloading, as viewed from the upper side rear;
FIG. 2 is an enlarged cross section of the printing fixture
assembly portion of the apparatus shown in FIG. 1;
FIGS. 3 and 3a are enlarged cross sections of a portion of FIG. 2
showing the pins which transfer ink, after the ink has been applied
to the pin and then as the ink is being applied to the printed
wiring board; FIG. 4 is a side elevation of the apparatus shown in
FIG. 1, partially cut away to show the cam slide and clutch tripper
mechanisms;
FIG. 5 is a plan view of the apparatus shown in FIG. 1;
FIG. 6 is an enlarged perspective view of a squeegee assembly used
as an ink applicator in the apparatus shown in FIG. 1;
FIG. 7 is a front elevation of the apparatus shown in FIG. 1;
and
FIG. 8 is an enlarged cross section of the shaft and intermittent
clutch assembly for the apparatus shown in FIG. 1.
DETAILED DESCRIPTION
Referring now to FIG. 1, there is shown an embodiment of the
invention for applying a viscous adhesive catalytic ink to the
periphery and walls of holes in printed wiring boards, especially
suited to mass production operations requiring minimum setup time.
This apparatus comprises a frame assembly 50 on which is mounted a
driving motor 117 connected to an intermittent clutch assembly 120,
for operating the apparatus through a slide cam assembly 150 and
pivot arms 178--178. A workpiece 40 (FIG. 2) is inserted
horizontally into a slot in a reciprocable carriage assembly 70
used as a workpiece holder. The pivot arms 178--178 are connected
to the carriage assembly 70 to move it from the loading position
shown to a transfer or printing position. In the printing position,
the workpiece is adjacent a printing fixture assembly 10 having
holes formed therein in a pattern corresponding to the holes formed
in the workpiece.
A squeegee assembly 80 mounted on the carriage assembly 70 contains
a supply of adhesive catalytic ink to be applied. As the carriage
assembly 70 moves, the ink is introduced into the holes of the
printing fixture assembly 10. When the carriage is in the printing
position, movable pins within the printing fixture assembly are
raised through the holes by the motion of a slide cam assembly 150
to apply the ink introduced therein to the workpiece. A vacuum
nozzle 200 pulls air through the holes of the workpiece to
distribute the ink within the holes.
More particularly, the printing fixture assembly 10 shown in FIG. 2
includes a horizontally disposed flat rectangular printing plate
11, used as a template, having chamfered upper edges 12 and 13 at
its front and rear ends and having a plurality of holes 14--14
arranged in a pattern identical to the pattern of the holes in the
workpiece which are to be imprinted. A stud 16 is rigidly fixed to
the printing plate 11 near each corner, and has a bearing surface
17 whose axis is parallel to the axis of the other studs and
essentially perpendicular to the printing plate 11. Each stud 16
receives a slidably fitted bearing sleeve 18 which is tightly
fitted in a bushing 19. Each bushing 19 is mounted in a movable
lower plate 21 so that the lower plate is maintained parallel to
the printing plate 11 but vertically movable relative thereto. A
flat washer 22 is attached by a lockwasher 23 and retaining screw
24 at the lower end of each stud 16 to act as a stop for the
bushing 19. A compression spring 25, located about each of the
studs 16 and bushings 19, engages the printing plate 11 and the
movable lower plate 21 to hold the bushing against the stop.
A pin-retaining plate 27, having a plurality of holes 28--28
arranged in a pattern identical to the holes 14--14, is attached
above but separated from the movable lower plate 21 by a spacer 29
located therebetween, and is maintained in accurate alignment with
the movable lower plate by dowel pins 31--31. A plurality of
transfer pins 33--33, each pin having a head 34 at its lower end,
are slidably fitted in the holes 28--28, the upper end of each pin
being slidably fitted in the corresponding hole 14 of the printing
plate 11. The head 34 of each pin 33 is within a recess 36 of the
spacer 29, and is pressed lightly up against the lower surface of
the pin-retaining plate 27 by a resilient material 37 located in
the recess. The pins 33--33 are of such length that the upper end
of each pin is slightly below the upper surface of the printing
plate 11, as most clearly shown in FIG. 3, when the bushings 19--19
are against their flat washer 22. The upper end of each pin 33 and
the walls of the corresponding hole 14 define a cavity into which
ink 42 can be introduced, see FIG. 3.
In this manner, when material is introduced into the holes in the
template so as to fill each such hole, an accurately controlled
quantity of the material is provided which will then be transferred
by the pins to the workpiece, as seen in FIG. 3a Further, the use
of relatively long material transfer pins laterally supported at
each end provides precise alignment of the pins and protects them
from bending caused by accidental contact during normal use.
As shown in FIGS. 4 and 5, the frame assembly 50 includes a base
plate 51 to which are attached two parallel vertical sideplates 52
and 53. A front mounting block 54 and rear mounting block 55,
fastened transversely to the sideplates and extending beyond each
side of the upper edges thereof, receive a pair of longitudinally
extending parallel guide rods 57--57 on which the carriage assembly
70 slides.
The printing fixture assembly 10 is removably mounted on the frame
assembly 50, see FIG. 1. The printing plate 11 is held against the
top edge of the sideplates 52 and 53 by capturing the chamfered
front edge 12 of the printing plate 11 under the chamfered rear
edge 61 of a top plate 62 which is attached transversely to the
sideplates between the forward ends of the guide rods 57.
The rear edge 13 (FIG. 2) of the printing plate 11 is captured
under the chamfered forward edge 63 (FIG. 5) of a retaining plate
64 which is located transversely between the sideplates 52 and 53,
immediately forward of the rear mounting block 55 and clamped
thereto by a knurled head screw 66. The plates 11, 62 and 64 are
arranged with their upper surfaces coplanar so that the squeegee
assembly 80 can slide smoothly across these surfaces in sequence. A
pair of longitudinally extending vertical guide plates 68--68 are
mounted so as to extend above the side plates 52 and 53 from the
rear mounting block 55 forward to a point just beyond the position
of the squeegee assembly 80 when the carriage assembly 70 is in the
loading position, so arranged that the squeegee assembly fits
slidably between the guide plates 68 as it moves across the
surfaces of plates 62, 11 and 64.
The carriage assembly 70 includes a pair of sidepieces 71--71,
slidably fitted on the guide rods 57--57 and transversely connected
by a bridging plate 72 fastened to the sidepieces. A pair of
brackets 73--73 is mounted on opposite sides of the bridging plate
72 to hold the squeegee assembly 80 (FIG. 5). A transverse slot 75
in the overhanging portion of each bracket 73, having a counterbore
74 (FIG. 5) at the inner end of the slot, provides a loose-fitting
guide for the squeegee assembly 80. A pair of hook plates 76--76,
rigidly connected by a transverse rod 77, is pivotally mounted on
corresponding pins 78--78 which protrude horizontally outward from
each bracket 73, with the hook portions adjacent the slots 75, see
FIG. 5.
As shown in FIG. 6, the principal element of the squeegee assembly
80 is a stainless steel pot 81 open at its top and bottom, for
containing the supply of adhesive ink (not shown). At each end
there extends a rectangular cross section boss 83 from which a
guide pin 84 extends horizontally still further, for loose-fitting
engagement in the counterbores 74 (FIG. 5) and slots 75 (FIGS. 4
and 5) of the carriage assembly 70. A pair of clamping plates
86--86 holds rubber strips 87--87 in a vertical position along the
front and rear edges of the bottom of the pot 81, parallel to the
axis of the pin 84. When the squeegee assembly is in place on the
carriage assembly 70, the ends of the rubber strips 87 press
against the guide plates 68--68 (FIGS. 4 and 5) of the frame
assembly, and the bottom edges of the rubber strips 87 press
against top plate 62 (FIGS. 4 and 5), so that the ink supply in the
pot cannot leak out. Felt pads 89 in recesses of the pot 81 between
the rubber strips 87 at each end protrude slightly so as to press
against the frame guide plates 68, and thus prevent leakage of ink
from between the rubber strips 87. A removable cover plate 92 is
held tightly to the open top of the pot 81 by a pair of knurled
head screws 93 to prevent the ink supply from drying.
As shown in FIG. 4, in the normal position the hook plates 76 of
the carriage assembly 70 bear downward on the guide pins 84 where
they extend through the slots 75, to hold the squeegee assembly 80
in place. The hook plates 76 can be rotated upward and forward from
the guide pins 84 so that the squeegee assembly can be removed.
As shown in FIGS. 4, 5 and 7, the plate fixture assembly 100 (FIG.
5) is also mounted on the carriage assembly 70. The fixture plate
101, which is the principal element of this assembly 100, extends
transversely between recesses in the top surfaces of the carriage
sidepieces 71--71 to which it is accurately located by dowel pins
102 (FIG. 5) and held by knurled head screws 103. A pair of
longitudinal workpiece guides 104--104 (FIG. 7) having an internal
lower lip 105 is attached to the lower surface of the fixture
plate, so disposed that a workpiece 40 can be slid easily between
the guides 104--104 with the bottom surface of the workpiece
resting on the lips 105--105. A pair of pilot pins 107 and 108
(FIG. 5), spring loaded by leaf springs 109, are slidably fitted in
pilot holes in the fixture plate 101 to engage registration holes
(not shown) in the workpiece 40, for alignment of the workpiece
accurately to the plate fixture assembly. To compensate for
tolerance buildup between the workpiece registration hole spacing
and the fixture plate pilot holes, pilot pin 107 preferably
operates in a longitudinally extending slot which is a sliding fit
transversely and a loose fit longitudinally. A guide step (not
shown) is attached to the fixture plate so that the workpiece can
be inserted only to the point where the registration holes in the
workpiece are under the pilot pins.
Openings 111 and 112 (FIG. 5) are provided in the fixture plate
101, arranged to expose the region of the workpiece in which are
located the holes to be printed, so that the vacuum nozzle 200
(FIG. 4) can act on those holes. A chamfered surface 113 (FIG. 7)
in front lower edge of the fixture plate 101 immediately above the
space between the longitudinal guides 104--104 provides a guide for
the workpiece 40 into the opening between the plate 101 and the
lips 105. A recess 114 (FIG. 5) is provided in the fixture plate
101, and a tapering recess 115 (FIG. 7) in the mounting block 54,
so that an operator of the apparatus can grasp a workpiece with his
fingers to withdraw it when the carriage assembly 70 is in the
loading position shown in FIGS. 1, 4 and 5.
In normal operation, driving power is obtained from a continuously
rotating electric motor with integral gearhead 117 (FIG. 5),
connected by a belt 118 to the shaft and intermittent clutch
assembly 120. As shown in FIG. 8, a shaft 121 is rotatably fitted
in a bearing block 122 which is fastened to the vertical sideplate
53 *(FIG. 5), so arranged that the axis of shaft 121 is transverse
to the apparatus. A handwheel 124 is fastened on one end of the
shaft 121 to permit manual operation of the apparatus for
inspection or setup. A sprocket 125, rotatably fitted on the shaft
121 adjacent to the handwheel 124, engages the drive belt 118 (FIG.
5). A key 126 is slidably fitted in the keyway 127 in the shaft 121
and handwheel 124, so that the key can be pressed fully inward to
engage a mating keyway 128 in the sprocket 125 thereby locking the
sprocket to the shaft 121. A ball plunger 129 mounted in the hub of
the sprocket 125 engages a detent in the key 126 to hold the key in
the keyway 128. A stop 131 fastened to the handwheel 124, and a
shoulder 132 on the key 126 prevent the key 126 from being pulled
out of the keyway 127.
A clutch-driving disc 134 having a plurality of holes 135--135 is
rigidly mounted on the shaft 121 near the end opposite the
handwheel 124, with the axes of the holes 135 parallel to the axis
of shaft 121 and equidistant therefrom. An intermittent
clutch-driven plate 137 is rotatably mounted on the shaft 121 at
the end opposite the handwheel 124 and adjacent the clutch-driving
disc 134, and is retained by a spring clip 138 fitted in a groove
at the end of the shaft 121. A flat spring 141 attached to the end
of driven plate 137 bears against a clutch pin 143 which fits
slidably in hole 144 of the driven plate, the hole 144 being
parallel to the axis of shaft 121 and the same distance therefrom
as the holes 135. When the hole 144 is in line with one of the
holes 135, the spring 141 can urge the clutch pin 143 into
engagement with the hole 135, to cause the driven plate 137 to
rotate with the shaft 121. A clutch release pin 146 extends
radially from the clutch pin 143 and passes slidably through an
axial slot 147 in the driven plate, so that movement of the clutch
release pin in a direction away from the handwheel 124 overcomes
the force exerted by the flat spring 141 and slides the clutch pin
143 out of engagement with the hole 135, to permit the shaft 121 to
rotate independently of the clutch-driven plate 137.
Principal details of the slide cam assembly 150 are shown in FIG. 4
and FIG. 7. A connecting rod 148 (FIG. 4) is rotatably attached to
the end of clutch-driven plate 137 and pivotally connected to the
cam plate 151. The cam plate is mounted to a backing plate 149
(FIG. 7) slidably fitted in a longitudinal groove in the frame
assembly 50, so that rotation of the clutch-driven plate causes
longitudinal reciprocating motion of the cam plate 151. The top
edge of the cam plate 151 has sequential horizontal cam surfaces
152 and 154 (FIG. 4) connected by a slant surface 153. These
surfaces are engaged by the cam roller 38 of the printing assembly
10, as shown in FIG. 2, and are so arranged that as the roller
follows the slant surface 153 upward the inking pins 33 are raised
from the position for receiving ink to the position where they
apply ink to the holes of the workpiece, see FIGS. 3 and 3a. The
lower edge of the cam plate 151 includes a downward protruding
tooth having a leading edge 155 and a trailing edge 156 (FIG. 4)
for engaging cam roller 177.
A striker pin 158 projects transversely from the cam plate 151, so
disposed that it can engage a locating pin cam 161 which is rigidly
fastened to a transverse shaft 162 rotatably mounted to the frame
assembly. A pair of locating pin-operating arms 164, rigidly
fastened to shaft 162, extend longitudinally rearward from shaft
162 in an approximately horizontal position. As the cam plate 151
advances, and just before the cam roller 38 engages the cam surface
152, the striker pin 158 contacts the bottom edge of cam 161 to
rotate cam 161 and shaft 162 slightly. A connecting pin 167 extends
transversely from the lower end of each of a pair of vertical
locating pins 168 through a corresponding longitudinal slot 165
near the extreme end of each arm 164, so that rotation of the
operating arms 164 causes vertical motion of the locating pins
168--168.
Each locating pin 168 is slidably fitted in a vertical hole 169 of
a bracket 172, the brackets being mounted opposite each other on
the outer surfaces of the sideplates 52 and 53 of the frame
assembly. The brackets 172--172 are arranged such that, when the
carriage assembly has been moved to the printing position with the
holes in the workpiece positioned approximately above the
corresponding holes 14--14 in the printing plate 11, the locating
pins 168--168 are under and approximately in line with mating
close-fitting holes (not shown) in the underside of the carriage
sidepieces 71--71. The upper ends of the locating pins 168--168 are
pointed so that, as the pins are raised by rotation of the
operating arms 164, the carriage assembly 70 may be moved
longitudinally as required to permit the locating pins to enter the
holes in the sidepieces 71--71, thus aligning the carriage assembly
70 and workpiece 40 precisely above the printing plate 11. A pair
of springs 173 (FIG. 4) withdraws the pins 168 to a mechanical stop
(not shown) when the striker pin 158 is not engaging cam 161.
A shaft 174 is rotatably mounted in the sideplates 52 and 53 with
its axis transverse and below the slide cam assembly 150. A pair of
sector plates 175, rigidly fixed to the shaft 174 near its center,
support cam roller 176 and 177 between the sector plates with the
axes of the cam rollers parallel to and equidistant from the axis
of shaft 174. In operation, the leading edge 155 (FIG. 4) of the
tooth on the cam plate 151 engages the roller 176 as the slide cam
assembly 150 moves rearward, to rotate the sector plates 175 from
the loading position to the printing position, and the trailing
edge 156 of the tooth engages the roller 177 as the slide cam
assembly returns to the loading position, to rotate the sector
plates 175 back to the loading position. A pair of pivot arms
178--178, rigidly attached to the ends of the shaft 174 outside the
sideplates 52 and 53, extend upwardly in the same radial direction
as the sector plates 175. The upper end of each pivot arm 178 is
coupled to the corresponding sidepiece 71 of the carriage assembly
70 by a connecting link 179 (FIG. 7) pivotally attached at its
corresponding ends to the pivot arm and sidepiece, so that rotary
motion of the sector plates 175 will cause translation of the
carriage assembly along the guide rods 57.
The intermittent clutch assembly 120 (FIG. 4) is controlled by a
clutch tripper assembly 180 mounted below the clutch assembly 120
between sideplates 52 and 53. A clutch release cam 181, pivotally
mounted on a pin 183 having its axis parallel to the shaft 121, is
located adjacent to the clutch-driven plate 137. With the cam 181
in its normal position the cam surface is in helical relation to
the axis of shaft 121 so disposed that, at the point in driven
plate 137 rotation where the carriage assembly has nearly returned
to the loading position, the clutch release pin 146 engages the
surface of cam 181. As the driven plate 137 rotates further, the
clutch release pin follows the helical path away from the driving
disc 134, sliding the clutch pin 143 out of the hole 135 so that
the driven plate 137 stops rotating, see FIG. 4.
A pin 185 extending transversely from the cam 181 extends into a
slot 186 in a release lever 187, the lever being fastened rigidly
on a transverse shaft 189 mounted rotatably between the sideplates
52 and 53 and having an end protruding through plate 52. Rotation
of the lever 187 and shaft 189 causes the cam 181 to pivot about
the pin 183 away from the clutch-driven plate 137. Such motion
disengages the clutch release pin 146 form the cam surface, thereby
permitting the flat spring 141 to push the clutch pin 143 into one
of the holes 135 in the driving disc 134, see FIG. 8. For manual
operation of the clutch, a knob 191 is provided on the exposed end
of the shaft 189. Automatic operation is obtained through a
solenoid 193 which is mounted on base plate 51 and mechanically
connected to the release lever 187 by pivotally attached connecting
link 194, so that energizing the solenoid causes the lever 187 to
rotate. A spring 196 is connected between the lever 187 and the
solenoid end of the link 194 to return the lever and solenoid to
the deenergized position.
A nozzle 200 (FIG. 4) connected to a vacuum valve and source (not
shown) is mounted over the plate fixture assembly 100 (FIG. 4) by a
bracket (not shown), so arranged that when the carriage assembly is
in the loading position the openings 111 and 112 (FIG. 5) are under
the nozzle 200. A cam-operated switch (not shown) is mounted in
such a way that a brief switch closure is obtained just before the
clutch-driven plate 137 has reached the loading position, at which
the plate stops between operating cycles of the apparatus. The
switch closure actuates the vacuum valve, so that a pulse of air
preferably less than 1 second in duration is drawn upward through
the holes of the workpiece.
A control box (not shown) is mounted in any position convenient for
the operator, and typically includes a fuse, a switch with
indicating pilot light for the electrical supply, and a momentary
contact switch for energizing the solenoid.
With reference to the foregoing description, the operation of this
embodiment of the invention is as follows:
A workpiece, having a pattern of holes to which adhesive ink is to
be applied, is inserted by an operator into the opening in the
plate fixture assembly 100 so that the workpiece rests on the lips
105, with the side to be imprinted facing down, and is pushed
inward until it hits the guide stop and is held in place by the
pilot pins 107 and 108. The operator then presses the switch which
controls the solenoid 193.
Viewed from the direction of FIG. 4, operation of the solenoid
rotates the release lever 187 clockwise, pulling the clutch release
cam 181 down and thus releasing the clutch release pin 146. The
spring 141 pushes the clutch pin 143 into one of the holes 135 in
the continually rotating disc 134, so that the clutch-driven plate
137 begins to rotate clockwise. As the slide cam assembly 150 is
advanced to the right, the leading edge 155 engages the cam roller
176 and rotates the sector plates 175 clockwise until the
tooth-leading edge can pass over the roller 176. Rotation of the
pivot arms 178 pulls the carriage 70 and squeegee assembly 80 into
the printing position above the printing fixture assembly 10,
spreading the ink 42 from the squeegee assembly into the holes 14
of the printing plate 11 as the carriage moves. As the slide cam
assembly continues to advance, the striker pin 158 engages cam 161.
This rotates the shaft 162 and locating pin arms 164 slightly
counterclockwise, and raises the locating pins 168 so that they
engage the snug-fitting holes in the carriage sidepieces 71,
aligning and locking the carriage in position. As the slide cam
assembly advances to its extreme position, the cam surfaces 153 and
then 154 pass under the cam roller 38, forcing the plates 21 and 27
upward until the pins 33 contact the holes in the workpiece, as
shown in FIGS. 2 and 3a.
As the clutch-driven plate continues to rotate, the slide cam
assembly 150 is pulled back to its starting position, and the
various other mechanisms return to their start positions in reverse
order. The springs 25 return the pins 33 and plates 21 and 27
downward, and then the springs 173 withdraw the locating pins 168
from the carriage sidepieces 71. Finally, the cam plate tooth
railing edge 156 engages the roller 177 and returns the carriage to
its starting position, so that the plate fixture assembly 100 is
under the vacuum nozzle 200. The cam-operated switch actuates the
vacuum valve, so that the resulting pulse of air sucks the ink
upward in the holes to obtain a smooth coating.
Since the solenoid 193 is operated only momentarily, the clutch
release cam 181 returns to its normal position while the driven
plate 137 is rotating, and the clutch pin 143 is then withdrawn
from the driving disc 134 as the driven plate 137 completes one
revolution. This finishes a complete operating cycle. The operator
can now grasp the workpiece and withdraw it from the carriage, and
proceed to repeat the operation with another workpiece.
As can be seen from the detailed description above, a feature of
this embodiment of the invention is the grouping of parts, which
are peculiar to one pattern of holes or configuration of workpiece,
into two assemblies which are easily removed and replaced: the
plate fixture assembly and the printing fixture assembly. This
feature provides maximum utility of the basic apparatus with a
minimum expenditure for capital equipment and setup time.
As will be appreciated by one skilled in the art, many variations
in the apparatus disclosed can be made without departing from the
spirit of the invention. For example, the transfer pins 33--33 may
be held stationary and the workpiece 40 and printing plate 11
displaced towards the pins to transfer material from the plate to
the workpiece.
* * * * *