U.S. patent number 3,830,611 [Application Number 05/274,843] was granted by the patent office on 1974-08-20 for apparatus for matched-mold thermo-forming.
Invention is credited to Jere F. Irwin.
United States Patent |
3,830,611 |
Irwin |
August 20, 1974 |
APPARATUS FOR MATCHED-MOLD THERMO-FORMING
Abstract
The method provides matched molds in superimposed relation,
cyclically reciprocating vertically each of said molds relative to
the other, to first mold a product in a continuous web of heated
thermo-plastic material fed cyclically between said molds, halting
each cycle just short of its reaching the point of maximum
proximity between said molds to allow the material adjacent the
periphery of said product to cool prior to performing the trim
step, starting the next following cycle with the trim step, the
latter being accomplished by continuing the approach of said molds
to the point of their maximum proximity, said product being left
connected to the web by easily broken tabs and punching the product
from the web at a stacking station during a succeeding cycle. The
apparatus embodies a double action automatic press including
parallel vertical side frames rigidly united with each other and
with a tripod supported base. A pair of massive vertical guide
posts fixed at upper and lower ends to inner faces of said frames,
vertically guide upper and lower tooling mounting platens, each
platen being connected by four adjustable links to arms on one of
two pair of rocker shafts, one such pair being above the upper
platen, the other pair being below the lower platen. Outside one
side frame, short arms are fixed on the upper pair of rocker shafts
and double armed bell cranks are fixed on the lower pair of rocker
shafts, each of the bell cranks having a long arm and a short arm.
A pair of long links connect upper and lower outside short arms and
a third link connects said long arms. A pitman connects one of said
long bell crank arms to a crank arm fixed on one end of a
transversely journaled crank shaft at the forward end of the press.
A base mounted constant speed motor is connected through a variable
speed transmission and an electro-air controlled clutch brake
mechanism to a reduction gear box which is interposed in a gap in
said crank shaft and directly drives the latter. Each revolution of
the drive shaft accomplishes one production cycle of the press. A
separate control device determines at what point in the production
each cycle ends to provide a cooling "dwell" between cycles so that
the trim step takes place at the beginning of each cycle, thereby
improving the product. A cyclic web feeder and heater is provided
on and driven by the press. The tooling employed in the press
leaves the product lightly connected with the scrap of the web
following each trimming step by several oppositely disposed
transfer tabs which may readily be broken by a punching operation
when the product arrives at a stacking station. The press embodies
and automatically drives a product punch for accomplishing this
function. A product stack conveyor receives products thus punched
from the web and automatically discharges product stacks of
predetermined quantity. A scrap chopper disposes of the scrap left
in the web. The press also includes separate means manually
operable while the press is running to vary the time period of the
cooling dwell and also to vary the distance, short of reaching the
point of maximum proximity between the platens, at which each
operating cycle concludes.
Inventors: |
Irwin; Jere F. (Yakima,
WA) |
Family
ID: |
23049827 |
Appl.
No.: |
05/274,843 |
Filed: |
July 25, 1972 |
Current U.S.
Class: |
425/144; 264/321;
425/150; 425/157; 425/168; 425/291; 425/383; 425/398; 425/412;
425/817R; 425/160 |
Current CPC
Class: |
B29C
51/18 (20130101); B29C 51/32 (20130101) |
Current International
Class: |
B29C
51/32 (20060101); B29C 51/30 (20060101); B29C
51/18 (20060101); B29c 003/06 () |
Field of
Search: |
;425/415,406,291,157,383,384,388,393,398,423,144,150,160,168,412 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Spicer, Jr.; Robert L.
Claims
I claim:
1. An automatic press for employing matched molding-trimming
tooling in thermo-forming thermo-plastic material, said press
comprising:
a pair of platens mounted in parallel spaced relation and
constituting mounts for a pair of matched tooling elements;
means for automatically transmitting a series of consecutively
cyclic reciprocative relative movements to said platens, between
the points of maximum separation and maximum proximity of said
platens;
automatic means for halting each reciprocating movement just short
of the point of maximum proximity of said platens being
reached,
automatic means for resuming said reciprocating after a delay to
produce a cooling time period dwell while a product unit is being
molded in said press,
thereby facilitating a trim step, when said movement resumes, in
which the spacing between said platens is further decreased to the
point of maximum proximity,
said reciprocation when resumed continuing without interruption
into the next reciprocation, where it halts at the cooling time
period dwell thereof in the same manner as said first mentioned
reciprocation; and
means manually operable while said press is running to adjust said
automatic platen movement halting means to precisely and
selectively determine at what distance apart said platens will be
halted by said means.
2. A press as recited in claim 1, in which said dwell length
modifying means is operable manually while said press is running,
to precisely increase or decrease the time period of said dwell.
Description
SUMMARY OF THE INVENTION
In developing the present invention, one of the outstanding objects
kept in view was to provide an automatic press adapted for matched
mold thermo-forming which is simple, quick, smooth, dependable,
quiet, versatile and easy to operate.
Another object was to produce such an automatic press which can
efficiently produce a variety of products at a relatively low
cost.
Another object was to produce such an automatic press by which
thermo-plastic products of a higher quality than hitherto available
could be produced in large volume at low cost.
Another object of the invention is to provide a method of and
apparatus for producing in large volume thermo-plastic products at
a low cost in which the periphery of the individual product has a
smooth pleasingly rounded contour.
Still another object of the invention is to provide such a method
and apparatus by which such a product might be produced in which
the upper surface of the product is coated with a very thin
lamination of solid styrene which extends around the rounded edge
of the product to the extreme periphery thereof and is cleanly
trimmed to provide a continuously smooth edge to the product.
A yet further object of the invention is to provide such an
automatic press in which the length of the time dwell in each
cyclic operation and the distance short of maximum proximity
between the platens at the moment each operation of the cycle is
halted are manually variable while the press is running, whereby
product quality control may be exercised in accordance with
observations made of the character of the product coming from the
press and without stopping the operation of the press.
Still another object of the invention is to provide an automatic
press in which the form trim step may be accomplished for each
product in a single cycle of operation and in which transport tabs
are simultaneously provided connecting the product with the web
whereby the punching of the product from the web and the stacking
of the same is reserved for a subsequent cycle thereby simplifying
the production of the product and greatly decreasing the force
required and tooling needed for the punching step and permitting
all three steps to be performed in a single press.
Another very important object of the present invention is to
provide an automatic press for matched mold thermo-forming which is
capable of operation at relatively slow speeds and at relatively
high speeds and at any in-between speed and which provides
vertically juxtaposed flat platens which are guided vertically
relative to each other particularly as they approach the point of
their maximum proximity and which is the most critical point in
each operational cycle, with a very high degree of precision and at
the same time maintaining said platens in practically perfect
horizontal parallelism with each other and spaced apart at said
point of maximum proximity, a precisely predetermined distance
under which conditions the tooling attached to said platens is
designed to function with almost absolute precision in the
formation of the product.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic side elevational view of a preferred
embodiment of the automatic press of the invention taken from one
side thereof on which is mounted the control panel at the top of
the machine and the automatic web feeding mechanism at the bottom
of the machine. This view also shows diagrammatically the web
heating elements and the web advancing chains and the automatic
product punching device, and the automatic product stack receiving
conveyor which functions only in response to stacks of a
predetermined size being deposited thereon by the punch mechanism,
and the scrap chopper which disposes of the scrap left in the web
as it leaves the press.
FIG. 2 is a fragmentary enlarged elevational view of the automatic
press of the invention, portions of which are broken away to better
illustrate certain parts otherwise hidden, and illustrating in
broken lines the power plant of the press.
FIG. 3 is a view with the same scale as FIG. 2 taken from the
opposite side of the press and illustrating the linkage employed in
connecting the power plant to the vertically reciprocating platens
on which the tooling is carried. In each of FIGS. 1, 2 and 3, the
press of the invention is illustrated with the said platens
disposed at the point of their maximum proximity.
FIG. 4 is a view similar to FIG. 3 and with the adjacent side frame
partly broken away to reveal otherwise hidden elements of the
operating mechanism of the machine with all the various operating
elements shown as these are positioned with the platens of the
machine disposed in horizontal parallelism at the point of their
maximum separation.
FIG. 5 is an enlarged fragmentary transverse sectional view taken
on the line 5--5 of FIG. 4 and showing the upper and lower platens
of the press of the invention equipped with male and female
tooling, the latter being shown diagrammatically by broken lines in
outline only and with said platens as they are positioned when
approaching each other during a production cycle to bring said
tooling simultaneously into contact with a heated thermo-plastic
web shown in this view as suspended between said upper and lower
tooling.
FIG. 6 is a view similar to FIG. 5 and illustrates said upper and
lower platens and the tooling mounted thereon at the conclusion of
the trim step at the beginning of a cycle of production in which
said platens are located at the point of their maximum
proximity.
FIG. 7 is a fragmentary horizontal sectional view taken on the line
7--7 of FIG. 5 and illustrating the four cavity character of the
tooling illustrated diagrammatically in FIGS. 5 and 6.
FIG. 8 is an enlarged diagrammatic vertical sectional view taken on
the line 6--6 of FIG. 2 and particularly illustrating the squeeze
fit of the vertical guide bearings provided on the superimposed
platens of the press when said platens are located at the point of
maximum proximity between said platens.
FIG. 9 is a view similar to FIG. 8 and may be said to be taken on
the line 5--5 of FIG. 4 and illustrates the relatively sloppy fit
of said slide bearings on the vertical guide posts provided
therefor when the platens are at their point of maximum separation
as shown in FIG. 4.
FIG. 10 is a schematic wiring diagram of the electrical elements of
the press of the invention.
FIG. 11 is a fragmentary diagrammatic enlarged sectional view taken
on the line 11--11 of FIG. 7 and illustrating the details of the
tooling shown diagrammatically in FIGS. 5, 6 and 7 with the platens
carrying such tooling halted at the end of a given production cycle
with said platens short of arrival at the point of their maximum
proximity, in other words, with said platens spaced apart a
distance in excess by 0.005 of an inch above the spacing between
said platens which exists at their point of maximum proximity and
which will occur at the beginning of the next succeeding production
cycle in the accomplishing of the trimming step which will separate
the entire periphery of the product from the web with the exception
of the relatively fragile transfer tabs, means for forming which
are illustrated in FIG. 11.
FIG. 12 is a greatly enlarged fragmentary operational cross
sectional view taken on the line 12--12 of FIG. 7 and a portion of
the tooling illustrated in the latter view which is not provided
with means for forming transport tabs as is the case in the portion
of the tooling illustrated in FIG. 11. FIG. 12 however is taken at
the same instant in an operational production cycle as FIG. 11 is
taken, to wit: as the tooling supporting platens are located
approximately 0.005 of an inch short of the point of their maximum
proximity, this halting of the platens in the press of the
invention continuing throughout a time dwell period (and which is
adjustable in length) for the purpose of permitting cooling of the
thermo-plastic material of the web being fed between the platens
and being formed by the tooling in the production of a product.
FIG. 13 is a view similar to FIG. 12 and is taken at the instant in
the initial portion of the next following cycle that the trim step
is accomplished by the overlapping of the die and punch mounted
respectively on the upper and lower platens of the press when the
latter reach the point of their maximum proximity. As shown in this
view, the scrap portion of the web snaps away from the product
portion to effect this trimming operation which separates the
product from the web entirely excepting for those portions of the
periphery of the product which comprise the transporting tabs
aforementioned.
FIG. 14 is a fragmentary diagrammatic vertical sectional view of a
modified form of tooling which is adapted for use in the press of
the invention for the manufacture of a meat tray, the tooling being
here shown at the point of maximum proximity between the upper and
lower platens of the press which accomplishes the trim step
separating the product completely from the web excepting for those
restricted areas in which transporting tabs are formed.
FIG. 15 is a view similar to FIG. 14, illustrating a second
modified form of tooling adapted for use in the press of the
invention in the formation of said meat tray. This figure also
shows said modified form of tooling just as it reaches the point of
their maximum proximity where the trim step is accomplished and the
platens and the tooling attached thereto start to withdraw from
that point in pursuance of the next succeeding production
cycle.
FIG. 16 is a fragmentary horizontal sectional view taken on the
line 16--16 of FIG. 2 and illustrating the power plant of the press
of the invention. This view also illustrates the manual control for
actuating the chain speed transmission of said power plant as well
as the manually operable adjustment means for modifying the point
in the rotation of the drive crank shaft at which a production
cycle stops and starts.
FIG. 17 is an enlarged view taken on the line 17--17 of FIG. 16 and
illustrates the switch and adjustment means therefor which is
operable during the running of the press to modify the point in
each rotation of the drive crank shaft at which each of the
successive production cycles starts and stops.
FIG. 18 is a fragmentary bottom plan of a product showing the
transporting tabs formed thereon.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention includes a method and an apparatus 25 which is
required for practicing said method commercially. A detailed
description of the apparatus will therefore precede the description
of the method.
The apparatus 25 includes an automatic press 26 having an H-shaped
base 27 formed by welding a longitudinal square tubular member 28
to similar cross members 29 and 30, the cross member 29 having a
pair of widely spaced cylindrical foot plates 35 and the cross
member 30 having a single centrally located foot plate 36, thus
furnishing a tripod support for the press 26.
Rigidly fixed to opposite ends of cross members 29 and 30 of base
27 are vertical, parallel side frames 37 and 38, these frames being
substantially reverse duplicates of each other and being shaped as
shown in FIGS. 1, 2, 3 and 4. The frames 37 and 38 have
corresponding large openings 39 through which access may be had to
the interior of the press. Bars 40 and 41 are secured at their
opposite ends to inner faces of marginal portions of the frames 37
and 38, each of these bars being furnished with a series of
horizontal holes 42 for securing other elements of the press or
accessories to the side frames 37 and 38. Secured at their upper
and lower ends to side frames 37 and 38 at points above and below
the openings 39 so as to be centered upon the same transverse
vertical plane A--A is a pair of supplemental frame reinforcing
bars 43. Bars 43 are connected respectively to the horizontal
mounting bars 40 and 41 by discs 44 and 45. Secured to upper and
lower faces of horizontal mounting bars 40 and 41 by screws 50 are
plates 51 and 52, between which a pair of massive cylindrical guide
posts 53 and 54 are mounted by axial screws 55. The posts 53 and 54
are thus held in vertical parallel relation with their axes
disposed in the aforesaid vertical transverse plane A--A. These
posts are preferably made of cylindrical tool steel shafting with a
net diameter of 21/2 inches in a central portion 56 thereof
(approximately 6 inches long), the diameter of said posts
decreasing upwardly and downwardly from said area 56 to a diameter
of 2.494 inches, for reasons to be made clear hereinafter. (See
FIGS. 8 and 9).
Vertically slideable on each of the posts 53 and 54 is a pair of
upper and lower square slide blocks 57 and 58 all of which are
identical in construction and each of which includes a square body
59 having a turned down neck 60. Each block is provided with a bore
61 for receiving a bronze sleeve 62, opposite ends of bore 61 being
counter bored to provide recesses for mounting resilient oil
retaining seals 63 and 64 in opposite ends of the block. One side
of each body 59 is partially severed by a deep kerf 67 and is
provided with a pair of screws 68 by which the body 59 may be
contracted to compress sleeve 66 so as to actually reduce the
internal diameter of the latter to closely control the fit of said
sleeve when it is slid over one of the guide posts 53 or 54 onto
the central area 56 thereof. In practice, the screws 68 are
tightened so as to produce a normal inside diameter in the bronze
sleeve 66 of 2.4995 inches, which is to say, one-half
one-thousandth of an inch smaller in diameter than the external
diameter of the central 6 inch section 56 of the guide posts 53 and
54. This means that a considerable amount of force is required to
press each of the slide blocks 57 and 58 onto the central areas 56
of maximum diameter of the guide posts 53 and 54 as shown in FIG. 8
of the drawings.
The press 26 also includes a pair of platens 69 and 70, each of
which includes a flat plate 71 having holes 72 in its opposite ends
which are formed of the proper size and center spacing to snugly
receive the necks 60 of slide blocks 57 and 58, these side blocks
then being held in assembled relation with the plates 71 of the
respective platens 69 and 70 by corner screws 73. The platens 69
and 70 include coolant boxes 74 embodied with the respective plates
71 of said platens and extending respectively upwardly and
downwardly therefrom, each of said boxes including a pair of end
plates 75 which are located just inwardly from and close to holes
72 in plates 71 and are secured to said plates so as to extend
short distances forward and rearward from the corners of plates 71
as shown in FIG. 7, where end portions of end plates 75 are
apertured to receive bolts 80. End plates 75 are reinforced
outwardly by triangular gusset plates 81 and are connected
lengthwise along front and rear edges of plates 71 by coolant box
walls 82. Each coolant box 74 is completed by a cover plate 83
which is secured at its edges to end plates 75 and coolant box
walls 82. Each coolant box 74 has a central medial dividing wall
84. At one end of each coolant box 74 the spaces on opposite sides
of the medial wall 84 thereof are connected by a hose 85 while at
the opposite end of said box the spaces on opposite sides of said
medial wall are connected to separate hoses 86 and 87, opposite
ends of which connect to a water circulating manifold box 88 which
is centrally divided into two chambers which individually connect
with water circulating hoses 89 and 90 which lead to and from a
cooling water source, not shown.
Mounted in upper and lower portions of side frames 37 and 38 are
heavy ball bearings 95 and 96, the axes of which are horizontal,
parallel and lie in the vertical planes of the bolts 80 shown in
FIG. 7. Journalled in these bearings are upper and lower pairs of
rocker shafts 97 and 98, the major portions of these shafts being
hexagonal in cross section and being turned down at their end
portions to cylindrical cross section where they extend through
said bearings. Certain end portions of said rocker shafts extend
outwardly beyond side frame 38 where upper rocker shafts 97 receive
short arms 99 and lower rocker shafts 98 receive bell cranks 100,
each of which includes a short arm 101 and a long arm 102. The
short arms 99 and 101 connect pivotally at their outer ends to the
opposite ends of two parallel links 103. The outer ends of bell
crank long arms 102 are pivotally connected to opposite ends of a
link 104.
Journalling in heavy ball bearings 105 mounted at one end of the
press 26 on side frames 37 and 38 is a drive crank shaft 106
carrying a crank arm 110 and the outer end of this crank and the
outer end of the adjacent bell crank long arm 102 are pivotally
connected to opposite ends of a pitman 111, so that for each
rotation of the drive crank shaft 106, each of the rocker shafts 97
and 98 is rocked through an angle of 90.degree..
Mounted on the hexagonal middle portions of rocker shafts 97 and 98
are short arms 112 and 113 which are slidable lengthwise on said
rocker shafts and are in the form of clamps which permits them to
be set in an adjusted position lengthwise of said shafts. Pivotally
connected at their ends to bolts 80 of upper platen 69 and to the
ends of upper rocker arms 112 are longitudinally adjustable links
114. In a like manner, opposite ends of four links 115 are
pivotally connected to bolts 80 of lower platen 70 and to the ends
of lower rocker arms 113. The rocker arms 112 and 113 are so set on
rocker shafts 97 and 98 that at one extreme in each cyclic
revolution of drive crank shaft 106, as shown in FIG. 3, rocker
arms 112 are extending directly downwardly from upper rocker shafts
97, and lower rocker arms 113 are extending directly upwardly from
lower rocker shafts 98. At the opposite extreme in each cyclic
revolution of drive crank shaft 106, shown in FIG. 4, short arms
112 and 113 extend exactly horizontally in the same direction from
the respective rocker shafts 97 and 98 on which said short arms are
mounted. As before noted, the position of the operating parts just
discussed and shown in FIG. 3 results in upper and lower platens 69
and 70 being located at the point of their maximum proximity
whereas the opposite point in each cyclic revolution of drive crank
shaft 106, shown in FIG. 4, results in said platens being located
at the point of their maximum separation.
It is to be noted that the links 114 and 115 above described are
uniformly comprised of self-aligning bearings 116 at each of the
opposite ends thereof, and a turnbuckle 117 connecting said
bearings. Each of these turnbuckles preferably employs at each of
its ends, threads pitched in the same direction but slightly
differing as to the number of threads per inch so as to render each
of these trunbuckles capable of making a very fine adjustment in
the length of the link in which it is embodied. This is a vitally
important feature of the present invention inasmuch as only with
such a precise adjustment available in determining the exact length
of these links would it be possible to set up the press 26 so as to
obtain the high degree of precision and quality in the product of
which it is capable.
Referring again to FIG. 1, the press 26 is here shown as equipped
with a support 125 for a roll 126 of sheet thermo-plastic material
and a pair of feeder chains 127 for withdrawing a web 128 from said
roll and feeding it through a heater unit 129 along a horizontal
path extending practically midway between platens 69 and 70 and
terminating at the opposite end of the press 26.
The web feeder chains 127 are driven by an adjustable radius crank
arm 130 on the opposite end of drive crank shaft 106 from the crank
arm 110. The tip of crank arm 130 is pivotally connected to one end
of a pitman 131, the opposite end of which pivotally connects to a
large diameter sprocket 132 which is mounted on an idle shaft 133
mounted in suitable bearings on side frames 37 and 38. Trained
around the sprocket 132, an idler sprocket 134 and a sprocket
toothed unidirectional clutch 135 is an endless chain 140. The
clutch 135 turns freely in one direction on a shaft 141 but when
turned in the opposite direction by chain 140, it rotates the shaft
141 to drive a shaft 142 through a chain 143 so as to drive web
feeder chains 127 to carry web 128 an adjustable distance towards
and through the press 26. This distance is adjustably determined by
manual rotation of a screw 144 on the adjustable radius crank arm
130. This can be done while the press is running at all normal
production speeds.
The press 26 is also equipped with a mechanism 145 for punching the
product from said web after it has been formed and trimmed between
platens 69 and 70 and during a cycle subsequent to that in which
the product was molded. This mechanism includes a bell crank 146
rockably mounted on brackets 147 mounted on the side frames 37 and
38 and including an upwardly extending arm 148 which is connected
pivotally and adjustably to a link 149 which connects to a short
arm 150 which is clamped onto an adjacent one of the rocker shafts
97 so that with each production cycle of the press 26 the bell
crank 146 is rocked so as to impart a vertical reciprocation from
the bell crank 146 to a telescopic member 155 carrying a tool 156
designed for lightly engaging and punching from the web 128 one or
more products 157 previously formed and trimmed in a preceding
operation cycle of the press. Individual products 157 thus punched
from said web gravitate downwardly as shown in FIG. 1 to form
stacks 158 until such a stack contains a predetermined number of
individual products whereupon a relay provided in a control panel
159 mounted on the upper end of side frame 37 energizes a conveyor
160 causing this to remove the stack 158 just formed beneath the
product punch 145 so as to leave room on the conveyor to start
another stack.
Just beyond the point at which the feeder chains 127 terminate, a
scrap chopper 161 is mounted which automatically responds to the
delivery thereto of scrap remaining in the web 128 as the latter is
discharged from the press 26 to reduce this to small chips which
can be readily carried away by an airblower 162 to a place of
storage.
The drive crank shaft 106 is driven by a power plant 163 which is
clearly illustrated in FIGS. 1-4 and 16. Included in this are an
electric motor 164 which is pivotally mounted at 165 so that a
drive pulley 170 provided thereon extends into and is connected by
a belt 171 of a variable speed transmission 172 to the input end of
an electro-air controlled "posidyne" clutch/brake drive unit 173.
Unit 173 is the product of Force Control Industries, 3660 Dixie
Highway, Hamilton, Ohio 45014. The output shaft of this unit
connects in turn to a reduction gear unit 174 which is mounted in a
gap in drive crank shaft 106 and thus forms a connecting link in
said shaft and directly drives the latter at a reduced speed of 1
to 15. The variable speed transmission 172 preferably has the
capacity to vary the speed ratio between the motor 164 and the
clutch/brake unit 173 from 1-1 to 3-1. Modification of the latter
speed ratio is effected by a manual crank wheel 175 mounted on the
outer end of a threaded control shaft 176 which effects said
control by rocking the motor 164 about its pivot mount 165.
The drive crank shaft 106 is equipped with a manual cycle control
mechanism 177 which includes a triangular plate 178 having a bore
179 which receives drive crank shaft 106, the plate 178 being
mounted by screws 180 and spacer tubes 185 on the inner face of
side frame 37. Formed on plate 178 and extending inwardly therefrom
and bordering the bore 179 is an annularly recessed sleeve 186 on
which a flat control handle 187 is clamped so as to rotate on
sleeve 186, a lip on said control arm fitting the recess in sleeve
186 to retain said arm in assembled relationship with plate
178.
Mounted on a lower portion of control arm 187 is a switch 188
having a spring biased roller 189 which is spring propelled into a
position close to shaft 106 except when said roller is depressed by
a cam 190 provided on said shaft for the express purpose of
depressing said roller and then releasing said roller to actuate
said switch immediately upon the cam passing out of contact with
said roller.
Clutch/brake 173 is preferably operated through electric solonoid
valves 191 and 192, the first being for the brake and the other for
the clutch. The switch 188 is connected electrically to the
solonoids 191 and 192 whereby, as soon as the roller 189 rides off
the cam 190 as the latter moves past said roller, the unit 173 is
immediately actuated to disengage the clutch and set the brake
thereof. Also connected electrically in the circuits of the
solonoid valves 191 and 192 is a "series GP" plug-in automatic
reset delay/interval (timer) model number GP-6S which is
manufactured by Singer Industrial Timer Division, U.S. Highway 287,
Parsippany, N.J. 070754. This timer is located in control panel 159
and is designated therein by the letter T. The Singer timer is
energized by the actuation of the switch 188 (which stops rotation
of the drive crank shaft 106) to start a timer motor embodied
therein to advance a timer hand to alignment with the position of a
manual setting hand from which it then returns automatically in
short jumps at one-tenth second intervals, step-by-step, to the
zero position, thereby consuming the time period of the delay for
which the timer is manually set. At the conclusion of this time
period, the timer closes the clutch/brake air valve circuit which
starts another cyclic revolution of the drive crank shaft 106.
Referring now to FIG. 3, hoses 193 and 194 are there shown as
leading upwardly from solonoid valves 191 and 192 and being
connected through pressure regulators 195 and 196 to a hose 197
leading to an air compressor (not shown). By manipulation of the
pressure regulators 195 and 196, the pressure delivered through
hoses 193 and 194 to the solonoid valves 191 and 192 can be varied
thereby softening or hardening the force with which the clutch and
brake of the unit 173 are shifted from open to set positions and
visa versa.
The distance between opposed flat faces of upper and lower platens
69 and 70 when these are at the point of maximum proximity is
preferably 5.125 inches. Matched tooling including various
combinations of punches and dies, male and female molds and spring
biased strippers and jig plates are assembled on and united with
the flat plates 71 of the upper and lower platens, this tooling
embracing upper and lower tooling elements which are spaced apart
during most of each production cycle and then cooperate with each
other to mold a product, or a group of products, from web 128 as
the platens 69 and 70 approach the point of their maximum
proximity. Of the wide variety of various types of tooling suitable
for use in the press 26 of the invention, the tooling 200 shown in
FIG. 11 has been associated with some of the finest results
obtained in high quality production realized in the operation of
the press 26. This tooling includes an upper element 201 which is
mounted on upper platen 69 and this element includes a sub plate
202, a punch 203, a spring biased stripper 204, and a female mold
205, said sub plate, punch and female mold being rigidly secured
together.
Tooling 200 also includes a lower element 206 which is mounted on
lower platen 70 and includes a sub plate 207 and a die 208, which
are united with each other and with the lower platen, and a male
mold 209 which is normally spring biased upwardly above the upper
edge of the die 208 so as to come into molding relation with the
female mold 205 and mold a product substantially in its final form
between said two molds before die 208 advances upwardly relative to
male mold 209 as shown in FIG. 11. As shown in this view, means 210
are provided for circulating cold water through the internal
passages formed in male mold 209 so as to enhance the capacity of
this mold to cool the peripheral portion of a product being formed
between the female mold 205 and the male mold 209. The section
illustrated in FIG. 11 was taken at a point where the lower end of
punch 203 which is its cutting edge, has formed therein a series of
narrow grooves 215 which permits at each of the places occupied by
these grooves the escape of a small amount of material from the web
upwardly in these grooves, at the time the trim step is
accomplished, to form tabs 216. These tabs continue to connect the
web with a product 217 and serve to transport the product 217 with
the web from the product molding and trimming station located
between the platens 69 and 70, to the product punching and stacking
station which is located at the punch 145.
FIG. 11 illustrates the relationship of the upper element 201 and
the lower element 206 of the tooling 200 as these two tooling
elements are precisely related at the instant rotation of drive
crank shaft 106 is halted by the opening of the switch 188. As
before pointed out, the normal operation of the press 26 requires
an adjustment of the control arm 187 so that when switch 188
closes, the reciprocative relative movement between the platens 69
and 70 instantly stops with said platens short of reaching the
point of their maximum proximity. FIG. 11 illustrates the distance
short of maximum proximity at which the press is halted with the
upper tooling element 201 and the lower tooling element 206 yet to
travel 0.005 inches in order to accomplish the trim step which will
sever the product 217 from the web 128 at all points about the
periphery of the product excepting where the tabs 216 are
located.
One of the finest products tried out for production on the
invention to date is made of expanded styrene coated on the upper
surface with a clear film of pure styrene. The method of the
invention exhibits tremendous merit in the production of this
commodity and it is for this reason that FIG. 12 is shown to
illustrate in enlarged detail what is taking place in the tooling
200 illustrated in FIG. 11 at the same instant as illustrated in
the latter view, but with a section taken elsewhere than opposite
one of the tab forming grooves 215. FIG. 12 shows the molding of
the rounded peripheral lip of the product with this being covered
neatly by the shaping of a coating 218 of pure styrene with which
the web was laminated prior to the web being fed between the
tooling elements.
It is to be noted that a substantial portion of the rounded lower
and outer edge portions of the upper surface and lower surface of
the periphery of product 217 shown in FIG. 12 is not dependent on
its being molded but is produced by the material being stretched
between tangential points of contact with the upper and lower molds
and the pinching action of the cutting edges of the die and punch.
The coincidental interruption of the operation of the press for a
short interval to permit relative cooling of the material as thus
shaped has the effect, when the trim step occurs, of preserving the
form thus imparted to the edge portion of the product.
At the conclusion of the dwell time period which can vary between
one-fifth of a second and 6 seconds, the next cycle commences with
the consummation of the interrupted movement of the two platens
toward their relative maximum proximity which causes the die 208
and the punch 203 to overlap as shown in FIG. 13. While the action
of the die and punch at the instant of their accomplishing the trim
step is hidden from view, ample evidence obtained from studying the
product indicates that the trim step does not function as a true
shearing action but rather by a cracking of the web along the edge
of the die as this starts to overlap the corresponding cutting edge
of the punch. The wide separation of the edge of the product from
the edge of the scrap shown in FIG. 13, of course, cannot take
place at the points where the scrap and the product are still held
integrally joined by tabs 216. The retention of the smoothly
rounded surfaces produced on the peripheral portions of the product
217 at the conclusion of the trim step is clearly shown in FIG.
13.
In a similar manner plates, saucers and dishes of various kinds
made by the press 26 by the method of this invention without the
web being coated as shown in FIGS. 12 and 13, present a remarkably
smooth rounded edge throughout the periphery of the product
excepting where the tabs 216 appear and which are too small to be
objectionable.
FIG. 14 illustrates a modified form of tooling 220, the upper
element of which includes a die 221 and the lower element a punch
222 which itself forms a female mold that cooperates with a male
mold 223 embodied with the die 221.
FIG. 15 illustrates another modified form of tooling 225 in which
the upper tooling element carried by the upper platen embraces a
punch 230 and has a male mole 231 associated therewith, while the
lower tooling element embraces a die 232 which embodies in itself a
female mold cavity which cooperates with the mold 231 in the
formation of the product.
One of the significant differences between the modified forms of
tooling 220 and 225 over the tooling 200 shown in FIG. 11 is that a
further compression of the product takes place incidental to the
performance of the trim step because of the fact that the latter
requires a relative movement between the two tooling elements which
form the product in order to bring the cutting edges of the die and
punch into shearing relation with the web. The forms of tooling 220
and 225 therefore are suitable in more rapid production where a
relatively short cooling period between cycles is both practical
and desirable.
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