U.S. patent number 3,775,225 [Application Number 05/159,993] was granted by the patent office on 1973-11-27 for machine for perforating and heat sealing a web including an elongated element with a multiplicity of drivers.
This patent grant is currently assigned to Gloucester Engineering Co., Inc.. Invention is credited to Charles M. Schott, Jr..
United States Patent |
3,775,225 |
Schott, Jr. |
November 27, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
MACHINE FOR PERFORATING AND HEAT SEALING A WEB INCLUDING AN
ELONGATED ELEMENT WITH A MULTIPLICITY OF DRIVERS
Abstract
Machines with elongated elements operable on an advancing web;
elements such as heat seal bar, perforator blade and clamp for
plastic film. Non-self supported elements are positioned and driven
by drivers at middle and at ends, positioned by referencing
stationary structure. Cam drivers, linear actuation, biased element
positioning, angled push rod actuation and other features are
shown. Slackness in web during heat sealing or supplemental
indexing is produced by rotation of the normally stationary portion
of a single direction clutch whose movable part is engaged with a
shuttle belt. Compensation for slip and slackening also are
achievable employing a differential drive between input and output
nip roll pairs, with selected driving of the third shaft of the
differential. Prolonged driving of the same differential can
establish a desired speed ratio between the two nip pairs to
compensate for slip, and change of the rotational input in response
to a position sensor serves as a registry control.
Inventors: |
Schott, Jr.; Charles M.
(Gloucester, MA) |
Assignee: |
Gloucester Engineering Co.,
Inc. (Gloucester, MA)
|
Family
ID: |
22575018 |
Appl.
No.: |
05/159,993 |
Filed: |
July 6, 1971 |
Current U.S.
Class: |
156/510; 83/627;
156/583.1 |
Current CPC
Class: |
B29C
65/18 (20130101); B29C 66/0044 (20130101); B29C
66/8122 (20130101); B29C 66/81419 (20130101); B29C
66/81431 (20130101); B29C 66/4312 (20130101); B29C
66/8226 (20130101); B29C 65/7457 (20130101); B29C
65/305 (20130101); B29C 66/81427 (20130101); B29C
66/83543 (20130101); B29C 66/8122 (20130101); B29C
66/1122 (20130101); B29C 66/8181 (20130101); B29K
2827/18 (20130101); B29C 66/8242 (20130101); B29C
66/71 (20130101); B31B 2155/003 (20170801); B29C
66/8511 (20130101); B29C 66/82261 (20130101); B29C
66/8511 (20130101); B29C 66/8161 (20130101); B29C
66/8223 (20130101); B31B 2160/10 (20170801); Y10T
83/8841 (20150401); B31B 50/645 (20170801); Y10T
156/12 (20150115); B29C 66/8225 (20130101); B29C
65/00 (20130101); B29K 2023/06 (20130101); B29C
66/71 (20130101); B31B 2155/00 (20170801) |
Current International
Class: |
B31B
19/00 (20060101); B31B 1/00 (20060101); B31B
19/64 (20060101); B29C 65/00 (20060101); B29C
65/18 (20060101); B31B 1/10 (20060101); B32b
031/00 (); B26d 005/08 () |
Field of
Search: |
;156/583,510
;83/627,590 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Drummond; Douglas J.
Claims
What is claimed is:
1. In a machine suitable for forming articles from plastic film
including an elongated forming surface adapted to be heated to a
temperature sufficient to weld plastic film and means to move the
forming surface in a predetermined path transverse to its length to
an operative position against the film, and back therefrom to an
inoperative position to allow advance of the plastic film, the
improvement wherein said elongated forming surface is defined by an
elongated element flexible in the direction of said path, lacking
self-support sufficient to maintain the proper geometry of said
forming surface throughout its length, stationary structure
extending along the length of said movable element and constructed
and arranged to allow said motion, a multiplicity of drivers spaced
apart along the length of said movable element, positioned at the
middle as well as the ends thereof, each driver comprising a cam
and roller follower combination, one of said combination comprising
a drive-force-receiving portion associated with said movable
element and the other comprising a cooperating drive-force-applying
portion positioned by stationary structure and movable relative
thereto, each said driver adapted, upon movement of its
force-applying portion, to position and drive the respective
portion of said movable element in said predetermined path, and a
drive means for driving all of said force-applying portions of said
drivers in synchronism to cause bodily movement of said element,
said force-applying portions and said stationary structure adapted
to transmit positioning forces through said drivers sufficient to
maintain said geometry of said forming surface during its movement,
and individual adjustment devices associated with individual
drivers, each adjustment device adapted to permit adjustment of the
position of the corresponding portion of said elongated element in
the direction of travel relative to other portions of said
elongated element.
2. The machine of claim 1 wherein the drive-force-applying portion
of said cam and roller-follower drivers are pivotally linked
together in an elongated linkage extending parallel to said
elongated forming surface, each said portion being free to be
displaced relative to the others by the respective adjustment
device, and a reciprocating drive moving said linkage axially to
drive and allow return of said forming surface.
3. The machine of claim 1 wherein said elongated element comprises
a heat seal bar, a series of support columns spaced apart along the
length of said bar are joined thereto through sheet-form flexures
flexible only in the direction of the length of said bar, each
column carrying thereon said drive-force-receiving portion of a
respective cam and roller-follower combination.
4. In a machine for perforating plastic film in which an elongated
plastic perforator element having a desired geometry along its
length periodically moves in a predetermined path transverse to
said length, the element adapted to move against a web to act
thereupon and away to allow web advance, said element associated
with strippers movable relative thereto during perforating and
withdrawal motions, the improvement wherein said elongated element
is comprised of a series of segments joined together, end to end
and is flexible lacking self-support sufficient to maintain said
desired geometry, stationary structure extending along the length
of said movable perforator element and constructed and arranged to
allow said motion, a multiplicity of drivers spaced apart along the
length of said movable element positioned at the middle as well as
at the ends thereof, each driver comprising a cam and roller
follower combination, one of said combination comprising a
drive-force-receiving portion associated with said movable element
and the other comprising a cooperating drive-force-applying portion
positioned by stationary structure and movable relative thereto,
each said driver adapted, upon movement of its force-applying
portion, to position and drive the respective portion of said
movable element in said predetermined path, and a drive means for
driving all of said force-applying portions of said drivers in
synchronism to cause bodily movement of said element, said
force-applying portions and said stationary structure adapted to
transmit positioning forces through said drivers sufficient to
maintain said desired geometry of said elongated element during its
movement.
5. In a machine suitable for forming articles from plastic film
including an elongated forming surface adapted to be heated to a
temperature sufficient to weld plastic film and means to move the
forming surface in a predetermined path transverse to its length to
an operative position against the film, and back therefrom to an
inoperative position to allow advance of the plastic film, the
improvement wherein said elongated forming surface is defined by an
elongated element flexible in the direction of said path, lacking
self-support sufficient to maintain the proper geometry of said
forming surface throughout its length, stationary structure
extending along the length of said movable element and constructed
and arranged to allow said motion, a multiplicity of drivers spaced
apart along the length of said movable element, positioned at the
middle as well as the ends thereof, each driver comprising a
drive-force-receiving portion associated with said movable element
and a cooperating drive-force-applying portion positioned by
stationary structure and movable relative thereto, each said driver
adapted, upon movement of its force-applying portion, to position
and drive the respective portion of said movable element in said
predetermined path, and a drive means for driving all of said
force-applying portions of said drivers in synchronism to cause
bodily movement of said element, said force-applying portions and
said stationary structure adapted to transmit positioning forces
through said drivers sufficient to maintain said geometry of said
forming surface during its movement, and wherein said element
comprises a heat seal bar and curtain means associated with said
bar, adapted to interpose a protective curtain between said heat
seal bar and said plastic, both said heat seal bar and said curtain
means being flexible in the direction of said path and individual
adjustment devices associated with individual drivers, each
adjustment device adapted to permit adjustment of the position of
the corresponding portion of said heat seal bar and curtain to the
other portions of said heat seal bar and curtain.
6. The machine of claim 5 wherein the drive-force-applying portions
of said drivers are pivotally linked together in an elongated
linkage extending parallel to said elongated forming surface, each
said portion being free to be displaced relative to the others by
the respective adjustment device, and a reciprocating drive moving
said linkage axially to drive and allow return of said forming
surface.
7. The machine of claim 5 wherein a series of support columns
spaced apart along the length of said elongated heat sealing bar
and associated curtain means are joined thereto through flexures
flexible only in the direction of the length of said heat seal bar,
each column associated with a respective driver for transmitting
drive and positioning forces to said heat seal bar and curtain
means.
8. In a machine in which an elongated element having a desired
geometry along its length periodically moves in a predetermined
path transverse to said length, the element adapted to move against
a web to act thereupon and away to allow web advance; the
improvement wherein said elongated element is flexible in the
direction of said path lacking self-support sufficient to maintain
said desired geometry, stationary structure extending along the
length of said movable element and constructed and arranged to
allow said motion, a multiplicity of drivers spaced apart along the
length of said movable element positioned at the middle as well as
at the ends thereof, each driver comprising a drive-force-receiving
portion associated with said movable element and a cooperating
drive-force-applying portion positioned by stationary structure and
movable relative thereto, each said driver adapted, upon movement
of its force-applying portion, to position and drive the respective
portion of said movable element in said predetermined path, and a
drive means for driving all of said force-applying portions of said
drivers in synchronism to cause bodily movement of said element,
said force-applying portions and said stationary structure adapted
to transmit positioning forces through said drivers sufficient to
maintain said desired geometry of said elongated element during its
movement,
said machine adapted to operate across the width of an elongated
traveling web, said stationary structure comprising an elongated
beam structure, stationary during operation, supported on end
columns and extending across the width of said web, and said
machine including the combination of at least two elongated
elements of the character above described, one of said elements
comprising a heat seal bar and the other comprising a perforator
blade, each element having associated therewith an independent
drive means, each of said elements positioned by its drivers
relative to said elongated beam structure.
9. In a machine in which an elongated element having a desired
geometry along its length periodically moves in a predetermined
path transverse to said length, the element adapted to move against
a web to act thereupon and away to allow web advance, the
improvement wherein said elongated element is flexi ble in the
direction of said path lacking self-support sufficient to maintain
said desired geometry, stationary structure extending along the
length of said movable element and constructed and arranged to
allow said motion, a multiplicity of drivers spaced apart along the
length of said movable element positioned at the middle as well as
at the ends thereof, each driver comprising a drive-force-receiving
portion associated with said movable element and a cooperating
drive-force-applying portion positioned by stationary structure and
movable relative thereto, each said driver adapted, upon movement
of its force-applying portion, to position and drive the respective
portion of said movable element in said predetermined path, and a
drive in synchronism to cause bodily movement of said element, said
force-applying portions and said stationary structure adapted to
transmit positioning forces through said drivers sufficient to
maintain said desired geometry of said elongated element during its
movement, and
wherein said drivers comprise cam assemblies one of said portions
of each assembly comprising a cam follower and the other of said
portions comprising a cam surface engaged with said follower,
and
said cam assemblies are mutually driven by a linkage reciprocating
in the direction parallel to the elongated element,
the machine including resilient biasing means for resiliently
urging said cam followers and cam surfaces together, said biasing
means applying a torque tending to rotate said elongated element
about its longitudinal axis, and said stationary structure includes
bearing surfaces opposing said tendency to rotate, thereby
cooperating to position said element,
said biasing means comprising a series of springs, one end of each
mounted to said stationary structure and the other end of each
being positioned to apply a portion of said torque, there being
a series of slidable supports spaced apart along the length of and
movable with said movable element, each extending from said element
to a said driver, each support including a torque arm extending
sideways and each said spring engaging a said torque arm.
10. The machine of claim 9 wherein said element includes a heat
sealing bar.
11. The machine of claim 10 wherein said element includes two
spaced apart bobbins, and a curtain of heat resistant, non-adherent
material extends between said bobbins under said heat sealing
bar.
12. A plastic film-working machine having a pair of elongated
plastic-working elements disposed side by side in proximity, each
of said elements having a desired geometry along its length and
movable in a predetermined path transverse to said length, each
element adapted to move against a web to act thereupon and away to
allow web advance, each said elongated element is flexible in the
direction of said path lacking self-support sufficient to maintain
said desired geometry, stationary structure extending along the
length of each said movable element and constructed and arranged to
allow said motion, each of said elements having a multiplicity of
drivers spaced apart along the length of the said movable element
positioned at the middle as well as at the ends thereof, each
driver comprising a cam and roller-follower combination having a
drive-force-receiving portion assocated with the said movable
element and a cooperating drive-force-applying portion positioned
by stationary structure and movable realtive thereto, each said
driver adapted, upon movement of its force-applying portion, to
position and drive the respective portion of said movable element
in said predetermined path, and each of said element having a
separate drive means for driving all of said force-applying
portions of the respective set of drivers in synchronism to cause
bodily movement of the respective element, said force-applying
portions and said stationary structure adapted to transmit
positioning forces through said drivers sufficient to maintain said
desired geometry of the respective elongated element during it
movement.
13. In a machine for forming bags from plastic film including an
elongated forming surface adapted to be heated to a temperature
sufficient to weld superposed plastic films together and means to
move the forming surface in a predetermined path transverse to its
length to an operative position against the film, and back
therefrom to an inoperative position to allow advance of the
plastic film, the improvement wherein said elongated forming
surface is defined by an elongated element flexible in the
direction of said path, lacking self-support sufficient to maintain
the proper geometry of said forming surface throughout its length,
stationary structure extending along the length of said movable
element and constructed and arranged to allow said motion, a
multiplicity of drivers spaced apart along the length of said
movable element, positioned at the middle as well as the ends
thereof, each driver comprising a drive-force-receiving portion
associated with said movable element and a cooperating
drive-force-applying portion positioned by stationary structure and
movable relative thereto, each said driver adapted, upon movement
of its force-applying portion, to position and drive the respective
portion of said movable element in said predetermined path, and a
drive means for driving all of said force-applying portions of said
drivers in synchronism to cause bodily movement of said element,
said force-applying portions and said stationary structure adapted
to transmit positioning forces through said drivers sufficient to
maintain said geometry of said forming surfaces druing its
movement,
said drivers comprising cam assemblies, one of said portions of
each assembly comprising a cam follower and the other of said
portions comprising a cam surface engaged with said follower, said
cam assemblies are mutually driven by a linkage reciprocating in
the direction parallel to the elongated element, said linkage
including movable portions of said cam assemblies is biased to one
position and a push rod and actuator assembly is mounted alongside
said linkage at an acute angle thereto, said push rod engaged with
said linkage and adapted upon activation of said actuator to push
said linkage in the direction overcoming said biasing means,
said actuator being a fluid drive cylinder pivotally mounted at a
pivot point fixed during operation, said rod engaging the linkage
to permit rotation during lenghtening of the cylinder with the
attendant change in angle between the push rod and the line of
action of said linkage.
14. The machine of claim 13 wherein said pivot point is formed by
an adjustable member engaging said cylinder, thereby to change the
position of said pivot point and alter the bottom position of the
movable element.
15. In a machine for forming bags from plastic film including an
elongated forming surface adapted to be heated to a temperature
sufficient to weld superposed palstic films together and means to
move the forming surface in a predetermined path transverse to its
length to an operative position against the film, and back
therefrom to an inoperative position to allow advance of the
plastic film, the improvement wherein said elongated forming
surface is defined by an elongated element flexible in the
direction of said path, lacking self-support sufficient to maintain
the proper geometry of said forming surface throughout its length,
stationary structure extending along the length of said movable
element and constructed and arranged to allow said motion, a
multiplicity of drivers spaced apart along the length of said
movable element, positioned at the middle as well as the ends
thereof, each driver comprising a drive-force-receiving portion
associated with said movable element and a cooperating drive-force
applying portion positioned by stationary structure nd movable
relative thereto, each said driver adapted, upon movement of its
force-applying portion, to position and drive the respective
portion of said movable element in said predetermined path, and a
drive means for driving all of said force-applying portions of said
drivers in synchronism to cause bodily movement of said element,
said force-applying portions and said stationary structure adapted
to transmit positioning forces through said drivers sufficient to
maintain said geometry of said forming surface druing its
movement,
said drivers comprising cam assemblies, one of said portions of
each assembly comprising a cam follower and the other of said
portions comprising a cam surface engaged with said follower, said
cam assemblies are mutually driven by a linkage follower, said cam
assemblies are mutually driven by a linkage reciprocating in the
direction parallel to the elongated element, said linkage including
movable portions of said cam assemblies is biased to one position
and a push rod and actuator assembly is mounted alongside said
linkage at an acute angle thereto, said push rod engaged with said
linkage and adapted upon activation of said actuator to push said
linkage in the direction overcoming said biasing means,
said actuator being a fluid rotary actuator, said actuator mounted
on supprting structure and said rod engaging said linkage and the
rotary actuator through rotary joints to permit an attendant change
in angle relative thereto during rotation of said actuator and
reciprocation of said linkage.
16. The machine of claim 15 wherein said supporting structure is
pivotally mounted to permit a change in the bottoming position of
said element and said position is adjustable by rotating said
structure in the direction of cam reciprocation by means of a
supported adjustment member.
Description
This invention relates to machines of the type having an elongated
element which periodically acts upon a web. It is particularly
relevant to the making of long formations or imprints in plastic
film and sheet and to machines for making plastic bags.
Objects of the invention include providing such machines which are
reliable and of high speed and in which the reciprocating member
can be made of any length, e.g., longer than 10 feet, to span webs
of similar width.
Particular objects are to provide such a machine which can act upon
wide plastic webs with controllable accuracy over the entire extent
of the active element.
The invention features an elongated element or forming surface and
its associated reciprocating assembly which lacks self-support over
its length sufficient to maintain the desired geometry of the
element. Stationary structure which extends along the length of the
element allows the desired back and forth motion of the element,
and a multiplicity of drivers are spaced apart along the element,
at its middle as well as at its ends. Each of these drivers
includes a drive-force-receiving portion on the movable assembly
and a drive force applying portion positioned by the stationary
structure and mounted for movement relative to it. A main drive
drives all of the force-applying portions in synchronism. This
movement is effective to move the element in the predetermined
direction and at the same time maintain the proper position and
geometry of the element.
By use of this structure the movable element may be of low mass
(permitting high speed), of simple construction and capable of
simple adjustment, e.g., to contour the element as desired.
Preferred embodiments of the invention feature: a series of
individual adjustment devices along the length of the active
element; the stationary structure comprising an elongated beam
extending across the width of the web and supported on end columns;
associated drive means, for the drivers, extending along the
elongated beam; active elements as forming dies, specifically
exampled by a plastic heat-sealing bar, as plastic penetrating
means exampled by a plastic perforator and as clamping surfaces
exampled by the heat seal bar as well as strippers associated with
the perforator. In the case of heat seal bars the invention
features a protective curtain means associated with the bar, in
which both bar and curtain means lack self-support and are
positioned by the drivers through reference to the stationary
structure.
The invention features the drivers as cam assemblies; the active
element slidably guided by the stationary structure to reciprocate
linearly; a series of support columns associated with the active
element; and push rod actuation of a linkage for driving the
drivers in synchronism; and both rotary and axially operable
actuators provide means for driving the push rods and adjusting the
stroke. In preferred embodiments positioning torque is applied to
the active element preferably by the same series of springs that
provide for return movement of the active element.
These and other objects and features of the invention will be more
fully understood in the light of the following description of the
preferred embodiments in connection with the drawings, wherein:
FIG. 1 is a perspective view, partially broken away, of a preferred
embodiment of the invention useful for manufacturing plastic
bags;
FIG. 2 is a diagrammatic, partially broken away perspective view of
the machine of FIG. 1 viewing the side of the heat seal bar
mechanism;
FIG. 3 is a cross-sectional view of the embodiment of FIG. 1 taken
on line 3--3 thereof;
FIG. 4 is a cross-sectional view on a larger scale of portions of
FIG. 3 showing the heat seal bar assembly details;
FIG. 5 is a view on scale similar to FIG. 4 showing perforator
blade assembly details;
FIG. 6 is a partially diagrammatic plan view with portions broken
away of the preferred embodiment;
FIG. 7 is a side view of one side of the machine showing in
particular the actuating arrangement for the heat seal bar
FIG. 8 is a side view of the other side of the machine showing the
actuating arrangement for the perforator blade and
FIG. 9 is a diagrammatic side view of a film drive according to the
invention while FIGS. 10 and 11 are cross-sectional, partially
diagrammatic views of preferred one way clutch assemblies for
accomplishing web salackening and supplemental indexing.
Referring to the drawings, there is shown a preferred embodiment of
the invention in which polyethylene film 8 is introduced between a
horizontal heat sealing bar 10, of length L, e.g., of 10 or 10
feet, and a lower platen 12. The elongated reciprocating heat
sealing bar 10 is connected to driven column members 14 through
flexures 18, all forming part of an elongated vertically
reciprocating assembly. The reciprocating assembly is intentionally
light-weight so that it may reciprocate quickly; however the
assemblyy lacks sufficient self-support to maintain the proper
geometry of the heat sealing surface 10a along its entire length.
The column members 14 are driven at their upper ends in the
vertical direction, transverse to the length of the heat sealing
bar, by reciprocating cam assemblies which are spaced apart along
the length of the heat sealing bar. Each of these comprises a first
portion, cam followers 22, and a second portion, cam surfaces 24.
The cam surfaces are reciprocated synchronously in the
longitudinal, horizontal direction by a plurality of connecting
rods 28 in a direction parallel to the heat sealing bar, these rods
interconnecting the cam surfaces with a drive means 30, for
example, a hydraulic-actuated piston. The cam surfaces are slidably
positioned for this motion by vertically adjustable extensions 31
FIG. 2 (see 68 FIG. 3) of the stationary structure 32, which
comprises a rigid beam extending across the width of the web,
supported by end pedestals 32a. The cam assembly is urged together
by the action of arms 33, connected to columns 14, and springs 34;
the resultant force of the springs tending to urge the cam
followers against the respective cam surfaces. The rigidity of the
stationary structure is thus transferred to the reciprocating
assembly through the adjustable extensions 31, via the cam
assemblies, and eventually to th heat sealing bar through the
flexures 18 which are stiff in the vertical direction. The flexure
connections are made periodically along the heat sealing bar, thus
providing several points of transfer of the supporting forces.
As the second portions 24 of the driven assemblies, i.e., the cam
surfaces, reciprocate in synchronism in the longitudinal direction,
along the length of beam 32, the first portions 22 of the driven
assemblies, i.e., the cam followers, reciprocate in the
predetermined transverse direction, i.e., the vertical direction,
thereby causing bodily reciprocation of the columns 14, fexures 18,
and heat sealing bar 10. At the same time, forces transmitted by
the cam surfaces serve to support and position adjacent portions of
the bar vertically so as to preserve the desired geometry of the
elongated forming surface. The forming surface thereby reciprocates
between the inoperative position whereby the film can be advanced
and the operative position whereby the plastic film is heat
sealed.
Referring more specifically to FIGS. 2, 3 and 4, the elongated heat
sealing bar 10 consists in part of an upper bar 38 and a lower bar
40 extending the length of the machine and welded as as to embrace
an elongated resistive heater element 42 (e.g., of tubular type)
also extending the length of the machine. The heater element
provides heat necessary for the sealing process. Two small diameter
bobbins 44, which extend the length of the machine and which
support a non-stick, heat-resistant curtain 46 (preferably part
Teflon), are also supported along the length of the heat sealing
bar. This curtain is wound around one bobbin, fitted around the
exterior of the lower bar 40, and is then wound around the second
bobbin, and is indexed periodically, as the exposed portion of the
curtain is used, in a known manner.
This assembly (i.e., the bars, bobbins and curtain) is supported at
spaced apart points by individual brackets 43 connected to flexures
18. Openings 48 in these brackets provide isolation tending to
prevent the structure above the openings from heating as the heat
sealing bar becomes hot.
The brackets 43, typically ten inches apart, provide the means by
which flexures 18 join the heat sealing bar to columns 14. The
brackets are slotted, providing two parts, and the flexure is
typically joined to these parts by screws. The flexure is a thin
piece of metal, about 0.050 inch thick, the direction of thickness
being arranged in the longitudinal direction of the bar and thus
allows motion by the heat sealing bar in the longitudinal
direction. The flexure however has much greater dimensions in the
vertical direction and in the other horizontal direction, and is
therefore rigid in those directions. Thus, the heat sealing bar
will not distort as its temperature rises causing expansion, but
rather will cause resilient deflection of the flexures in the
longitudinal direction, while remaining straight in the vertical
and other horizontal directions.
The stationary structure, which supplies rigidity to the system, is
composed of wall members welded together to provide an elongated
horizontal tubular structure 51 extending the length of the
reciprocating assembly. The column members 14 pass through
periodically spaced openings 53, one in each of two horizontal
members, and upwardly to support cam followers 22. The column
members are typically one inch cross section tubular structures and
the cam followers 22 are joined to the top ends of the column
members. Torque arm brackets 33 are joined to the column members
within the tube 51 and extend horizontally. A series of compression
springs 34 are grounded on the stationary tube wall and act upon
respective torque arms 33 to supply an upward force urging the cam
followers upwardly against the cam surfaces 24. The sum of all
forces on the periodically spaced columns is sufficient to raise
the weight of the reciprocating assembly and thus provide positive
contact of all of the cam followers against the respective cam
surfaces, and automatic return of the bars to the inoperative
position upon de-activating movement of the cams.
In addition to the vertical force on column members 14, there is
also a torque tending to rotate the reciprocating assembly about
its longitudinal axis due to the offset of the line of action of
the springs 34 on arms 33. This resiliently applied torque is
effective to force the column members against the bearing surfaces,
upper bearing surfaces 54 on one side, and lower bearing surfaces
56 on the other side of each column, thus to accurately position
the assembly in the sidewise direction. The bearing surfaces
typically of anti-friction material, thus slidably position the
reciprocating column members for movement in the reciprocating
direction. The lower bearings are typically free floating bearings
fitting around the lower wall member 50 for the length of the
opening cut therein. The upper bearings are positioned by dowels
not shown.
The cam structure includes a plurality of machined, cam surfaces 24
linked together by connecting rods 28 to form a chain-like series
wherein slight, self-adjusting rotation is allowed at joints 60.
Each cam surface 24 is slidably positioned against an adjustable
L-shaped block 68, FIG. 3. The L-shaped blocks slide in the
vertical direction on rod 70 which are secured to upper stationary
structure 72. The spacing between the upper stationary structure
and the upper surface of the L-shaped blocks is individually
adjusted by the screws 74 which are secured in the tapped upper
structure 72 and seat in the recesses 78 of the L-shaped
blocks.
The action of the cam surfaces 24 against the cam followers 22 can
produce significant longitudinal forces on the reciprocating
assembly. The force vector F resulting from the contact of the cam
surfaces against the cam followers is essentially normal to the cam
surfaces and therefore has both a vertical and a horizontal
component. The vertical component overcomes the spring forces and
produces the downward motion. The horizontal component is a
longitudinal thrust force. To oppose these longitudinal forces,
dowels 58 also secure third bearing members 80 (FIG. 7) which
prevent longitudinal movement of columns 14 as a result of the
longitudinal thrust force.
The drive means 30, which produces the reciprocating cam motion, is
preferably a hydraulic piston arrangement positioned as shown in
FIG. 7. The linear piston arrangement advantageously allows control
of the driving force necessary for proper operative positioning of
the sealing process when the machine is not run in a fixed gap
condition. The cylinder-piston rod arrangement preferably lies in a
horizontal plane and engages the driven cam 304 at a vertical
height substantially equal to the height at which the connecting
rods engage the cam surfaces. In this manner, vertical moments
resulting from the driving force are substantially eliminated.
Being at substantially the same vertical height as the connecting
rods, the driving means must be angled away from the direction of
motion of the cam rod chain, at an angle A, FIG. 6, the angle
changing slightly as the hydraulic cylinder reciprocates.
In the preferred embodiment, the piston arrangement is horizontally
arranged and consists of a hydraulic actuated cylinder 300
pivotally mounted at point 301 with drive rod 302 engaging driven
cam 304 at a rotatable joint 306, preferably a bearing surface of
anti-friction material, to permit rotation during lengthening of
the cylinder and resulting relative movement of the cam surface.
The bearing surface engaging drive rod 302 at 306 provides the
reaction force to oppose the driving force and reduces forces
normal to the driving force to a minimum.
By positioning the drive rod at an angle A to the direction of cam
movement, the driving force at joint 306 has a driving component
312 in the direction of cam movement and a smaller component 314
normal to force 312 which force 314 being opposed by reaction
forces from suitable bearing surfaces.
The throw of the linear piston driving means is fixed, however the
position of the drive can be varied by adjusting screw 308
supported by stationary structure 310. Screw 308 allows the
position of pivot point 301 to be changed, changing the bottom
position of the reciprocating member, allowing easy adjustment for
varying thicknesses of web. Pivot point 302 is defined by the
recess of cylinder 300 which is engaged by the rounded end of screw
308 and remains fixed during a series of sealing operations.
Drive rod 302 is always under compression to engage cam surface 304
and to ensure that the cylinder continues to engage adjusting screw
308 at a pivot point 301. The forces tending to urge the surface of
cam 304 against piston rod 302 are the upward spring force supplied
by springs 34, combined with the horizontal urging force supplied
by spring 62.
The adjusting screws 74 and vertically adjustable L-shaped blocks
68 allow fine vertical adjustment of an individual cam surface to
allow for local distortions or otherwise to contour the heat seal
bar as desired. While the throw of the sealing bar is fixed by the
reciprocating cam assemblies and the drive means, typically
three-eighths inch, the extremes of the throw are locally
translated. The sealing bar may be shaped by these periodically
spaced adjustments to match any distortions in the lower platen
12.
The upper stationary structure 72 is part of the tubular structure
51, this weldment providing sufficient rigidity for the accurate
positioning and adjustment of the heat sealing bar reciprocating
motion.
Referring in particular to FIGS. 3 and 5, adjacent the heat sealing
bar is the reciprocating perforating blade carried on plate 100.
The perforating blade assembly unlike the heat sealing bar, need
not dwell at the film and therefore may be heavier than the heat
sealing bar because more time (hence slower permissible speed) is
available to move the blade. It reciprocates as a result of
reciprocating cam action in a similar manner as the heat sealing
bar; however, periodically spaced adjustment is not necessary, an
error of 0.045 inch along the length of the plate not being
critical.
Plate 100 is biased against cam assemblies by the action of springs
102 against levers 104 (FIGS. 3, 5, 6) which are distributed
periodically along the length of the plate 100. Cam followers 106
are attached to a rigid support 108, and the cam surfaces 110 are
urged against the cam followers by the action of the spring and
lever. In order to prevent the longitudinal thrust forces resulting
from the sloping cam surfaces from affecting the perforating plate,
contact is made by a nearly frictionless, rolling or sliding
contact, thereby minimizing the transfer of horizontally directed
forces against the perforating plate and eliminating the need for
end bearings on the plate. The preferred method (FIG. 8) consists
of rollers 114 attached to plate 100, these rollers having a very
low coefficient of friction with the cam. Thus, the longitudinal
thrust load is absorbed by the rigid support 108, and the
horizontal component of force on plate 100 as a result of contact
with rollers 114 is insignificant.
It is therefore not necessary to oppose longitudinal forces on the
heavier perforating plate in the manner in which bearing surfaces
58 opposed longitudinal forces acting on the reciprocating heat
sealing assembly.
In the preferred embodiment, the cam surface driven by driving
means 350 (FIG. 6) is designated the master cam 110' and is
different in construction than the other reciprocating cams
surfaces, the slave cams 110. The master and slave cams are
connected together and substantially aligned in one direction in a
chain-like series by connecting rods 352 at joints 330 which allow
limited rotation. As the driving means 350 forces the master cam to
the right, FIG. 8, the resulting forces from drive cam followers
106 transmitted to the perforating plate 100 through roller 114,
force the perforating plate downward, overcoming the spring force
urging the perforating plate upward.
The driving means 350 is a hydraulic rotary actuator which
advantageously has controlled acceleration. The actuator has
directional valves which provide self-cushioning; the cushioning
occurs at the two dead center positions, which are 180.degree.
apart and correspond to the extremes of travel of the perforating
plate, and results from a small amount of hydraulic fluid,
preferably oil, which remains in the actuator chamber unable to
instantly escape from the chamber at the extreme of plate travel,
thereby cushioning the extremes of travel of the drive means. It is
the cushioning action which makes the rotary actuator not preferred
for the reciprocating heat sealing bar because the forces at the
extremes are difficult to control.
The range of travel of the perforating plate is established by the
point 352 (FIG. 6) at which the drive rod 354, which engages the
master cam at bearing surfaces 356, engages the oscillatory
rotating drive wheel 358. The rotation-allowing joint at point 352
is preferably a self-aligning spherical roller bearing which allows
rotation as the drive wheel circularly oscillates driving the
master cam in linear reciprocation. The drive wheel, shown in FIGS.
6 and 8 near, but below the right dead center position, where the
perforating plate is in the downward vertical position rotates
downward, through has rotated less than 180.degree., from below the
left dead center position. The direction of rotation then reverses.
Because of the cushioning effect, the exact point of reversal is
not precisely controllable; however, since this occurs at that
portion of the circular cycle which has an almost insignificant
component in the direction of cam reciprocation, the effect is
negligible.
The bottom position of the perforating plate can be adjusted by
pivoting the rotary actuator supporting structure 360 about
supporting pivot point 362. Thumbscrew adjustment 364 threaded
through rigid support 108 engages the supporting structure 360 at
recess 361 through compression line 365. Thumbscrew 364 engages
compression link 365 at recess 366. Compression link 365 allows for
horizontal movement of supporting structure 360 as it pivots about
pivot point 362 thereby adjusting the bottoming position of the
perforating plate. Adjusting screw 364 is arranged with a shear pin
to provide overload protection against the perforating plate
bottoming out. If the perforating plate should bottom out, thereby
able to cause destructive forces to be generated by the drive means
350, the shear pin will release, allowing supporting structure 360
to pivot clockwise about pivot point 362 relieving and reducing the
built-up forces from the rotary actuator drive.
As with the reciprocating cam surfaces for the heat sealing
structure, drive rod 354 engages the master cam at substantially
the same height as the connecting rods 352; and therefore to avoid
interference with those rods, the drive means is placed at an angle
B to the plane of plate reciprocation. The center of rotation 363
of the driver wheel is positioned at all times so that the driving
force on the master cam always has an upward vertical component
urging the master cam against the guides, cam followers 106.
Also similar to the cam-drive assembly for the reciprocating heat
sealing assembly, a force normal to the plane of the perforating
plate is generated because of the required angle B between the
direction of drive and the direction of the cam reciprocation. This
force is opposed by supported sliding bearing surfaces, preferably
anti-friction sliding bearing pads.
The master cam and slave cams are preferably placed approximately
every twenty inches along the perforating plate. The connecting
rods are always in tension, tension being supplied by the pulling
master cam as the perforating plate moves downward and are held in
tension by the upward urging tendency of the perforating plate
against the slave cams as the plate moves upward.
Each slave cam 110 moves to the right and downward, as the master
cam 110' moves to the right and downward in response to the drive
force, and following the action of the cam surface 370 against
fixed guide cam follower 106. As the perforating plate reverses its
direction the upward urging of the plate causes the slave cams to
move upward and to the left in conjunction with the action of the
master cam, the connecting rods always being kept in tension.
Uppper guide surface 374 ensures the path which the slave cams
traverse.
The perforating blade 120 is mounted in the bottom of the
perforating plate 100. Referring to FIG. 5, a notch 122 is machined
in the plate 100, in which the blade is positioned. A resilient
holding strip 124 is then placed in the notch to cover and hold the
blade, and strippers 126 are held in place while the gib, securing
the whole assembly, is fastened to the plate with fastener 129. The
strippers and web grippers 126 are slotted so that they may
reciprocate vertically and are spring loaded 130 (FIG. 8) so that
in moving vertically upward the spring force must be overcome.
Therefore, as the plate 100 lowers, the strippers first contact the
web. The plate continues to lower as the strippers remain
stationary and the blade emerges from between the strippers to
perforate the web. The motion of the plate is then reversed and as
the plate moves upwards, the blade retreats between the strippers
and any web still attached to the blade is stripped from the blade
by strippers 126.
The web is advantageously driven periodically past the machine by a
shuttle arrangement such as is shown in applicant's prior U.S.
Pats., No. 3,322,604, 3,361,614 and 3,526,563, to which reference
is made.
Referring to FIG. 9 improvements are introduced to the machine
shown enabling relaxation or supplementary indexing of the web.
The forming head 500 corresponds to the heat seal and perforator
machine discussed so far. The shuttle 510 driven by cylinder 512
takes up and pays out the web and the single direction clutch 514,
with its outer race normally stationary and its inner race engaged
with timing belt 520, all as explained in U.S. Pat. No.
3,526,563.
According to the present invention instead of permanently mounting
the outer race of the single direction clutch, it is mounted to
rotate, and a periodically operating drive, here cylinder 540 is
adapted to be actuated immediately after the heat seal bar raises.
The result of this movement is that the plastic film moves
slightly, proportional to the rotation of the outer race, and is
thus removed from the hot jaws of the heat seal bar where it is
cooled. Upon reversal of the movement of the shuttle the cylinder
may be returned to its original position, thus assuring
registry.
In FIG. 10 an alternate device is shown consisting of a chain drive
which can selectively drive the outer race. A longer range of
travel can be obtained, thus to achieve a supplementary indexing
effect. For instance the plastic heat seal can be advanced to a
pair of cooling jaws.
Referring to FIG. 8 there is also provided a drive 560 for one pair
of nip rolls the second pair being driven through a differential
570. A third input shaft 572 to the differential selectively driven
by the motor 574 provides a different speed. This motor can respond
to tension sensor 576 to adjust rate of speed for slippage. By
momentarily driving the shaft 572 at a different speed it is
possible to slacken the film between the nip rolls, and reversal
can remove the slack.
Another means of introducing slack is to translate a pair of nip
rolls (or the idler as noted in dotted lines) slightly on a
periodic basis as desired.
* * * * *