US3748078A

US3748078A - Forming machine with web transport

Info

Publication number: US3748078A
Application number: US00235304A
Authority: US
Inventors: C Schott
Original assignee: Gloucester Engineering Co Inc
Current assignee: Gloucester Engineering Co Inc
Priority date: 1972-03-16
Filing date: 1972-03-16
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24
Also published as: CA994509A; DE2313208A1; GB1396477A; JPS494754A; FR2176152A1; FR2176152B1

Abstract

In a web forming machine (e.g., with pre-heat oven and die for plastic sheet) the web gripping and transporting members extending along the web (e.g., on a long chain) are advanced by a hydraulic actuated rotor stroking back and forth through a fraction of a revolution, with controlled deceleration of the system by combination of an orifice progressively occluded by the rotor at stroke end and a linkage establishing the motion of the gripping members as dependent upon motion of the rotor in varying ratio, with greatest value near mid-stroke and lesser values near end. The linkage shown is an elongated crank driving a rack which rides about and drives a pinion; preferably the crank extends parallel to the rack at the end of forward stroke and the pivot connecting rack to crank is adjustable to vary gripping member stroke. A clutch permits movement of the gripping members in only one direction and a controller engages the clutch during forward and disengages during backward stroke. The actuator, linkage and extended gripping members are movable as a unit to accommodate different web widths. The actuator is formed of a sandwich of plates, a central plate defining the chamber in which the rotor turns, as well as the stops, and an outer plate defines a fluid orifice which is occluded by the rotor for deceleration.

Description

United States Patent 1191 Schott, Jr.

[ FORMING MACHINE WITI-I WEB TRANSPORT [75] Inventor: Charles M. Schott, Jr., Gloucester,

' Mass.

[7 3] Assignee: Gloucester Engineering Co., Inc.,

Gloucester, Mass.

[22] Filed: Mar. 16, 1972 [211 Appl. No.: 235,304

425/398, 400, 406, 71, 122, 126, 112, DIG. -48; 74/130, 126, 88; 226/156, 157, 172, 179

[ July 24, 1973 Primary Examiner-Robert L. Spicer, Jr. Attorney-J. N. Williams [57] ABSTRACT In a web forming machine (e.g., with pre-heat oven and die for plastic sheet) the web gripping and transporting members extending along the web (e.g., on a long chain) are advanced by a hydraulic actuated rotor stroking back and forth through a fraction of a revolution, with controlled deceleration of the system by combination of an orifice progressively occluded by the rotor at stroke end and a linkage establishing the motion of the gripping members as dependent upon motion of the rotor in varying ratio, with greatest value near mid-stroke and lesser values near end. The linkage shown is an elongated crank driving a rack which rides about and drives a pinion; preferably the crank extends parallel to the rack at the end of forward stroke and the pivot connecting rack to crank is adjustable to vary [56] References Cited gripping member stroke. A clutch permits movement UNITED STATES PATENTS of the gripping members in only one direction and a 2,674,093 4/1954 s16mer 2261156 UX the clutch during fmwad and disen' 2,758,837 8/1956 Littell et al... 226/157 x gages durmg backward stroke- The actuator, llnkase 2,840,369 6/1968 Burman 226/157 x and extended pp members are movable as a unit 2,940,327 6/1960 Gartner 74/130 to accommodate different web widths. The actuator is 3,067,918 12/1962 Peterson 226/156 formed of a sandwich of plates, a central plate defining 3,079,632 3/ 1963 Peicltil 425/126 X th chamber in which the rotor turns, as well as the stops, and an outer plate defines a fluid orifice which er 0 3,359,600 1211967 O'Brien 6! al. 425/157 by i 14 Claims, 6 Drawing Figures /1O 1 v 12 I 6 .1 L i I i '7" I- EIII: '1 ::"::Ilillf le u] I.// I L Patented July 24, 1973 2 Sheets-Sheet 1 FIG I FIG 2 Patented July 24, 1973 3,748,078

2 Sheets-Sheet 2 FORMING MACHINE WITII WEB TRANSPORT BACKGROUND OF THE INVENTION This invention relates to machines for repetitively forming articles from webs and more particularly to the web transport part of the machine. It is of particular relevance to long machines used to transport plastic foam through preheat ovens to a periodically acting die.

The transport mechanism which advances the web by steps through such machines includes massive elements for gripping the web which must be put in motion and stopped. The transport mechanism is prone to wear and misalignment from the large forces required to start and stop the massive elements and especially so when it is subjected to large acceleration peaks.

SUMMARY OF THE INVENTION The objects of this invention include smoothly starting and stopping the web gripping members with their associated drive train, avoiding high acceleration peaks in moving the web, and minimizing the wear and misalignment of the web advancing mechanism, all with machine elements of simple and durable construction.

The invention features in a forming machine as mentioned above a hydraulic rotary actuator having a housing and a rotor mounted therein for reciprocating rotation through forward and backward strokes of a fraction of a revolution, the rotor and the housing coacting to define a chamber of variable volume diminishing as the rotor advances through a. stroke, the actuator including a passage connected to conduct fluid relative to the chamber as therotor advances, the passage having an orifice communicating'with thechamber, which orifice, duringa terminal fraction of the stroke, is progressively occluded: by therotor, thereby progressively increasing theflowresistance to the fluid: to decelerate the rotor, and a linkageconnected to and driven in reciprocating motion. through forward and backward strokes corresponding to the rotor strokes and connected to drive the gripping members, the linkage establishing the rate of motion of the gripping members dependent upon the rate of motion of the rotor in varying ratio thereto, the ratio having its greatest value near midstroke and lesser values near either stroke end.

A preferredembodiment features anzelongated crank affixed to the rotor, a pinion with axis parallel to that of the rotor connected to drive the gripping members, a rack engaging the pinion and a pivot connecting the crank to the rack, the crankbeing affixed to the rotor so as to extend parallel to the rack when therotor is at the end of its forward-stroke and the. pivot being adjustable in distance fromthe rotational axis of the rotor to vary the length of the linkage stroke. The preferred'embodiment further features a shaftsynchronously driving the gripping members and-a clutch connecting the pinion to theshaft and acontroller to operate the rotary actuator and the clutch and connected to engage the clutch during the, forward stroke of-the rotor and to disengage the clutch duringtheback stroke of the rotor. In the preferred embodiment: the actuator and drive train to drive the gripping members at one of the sides wherein a chamber is defined in part by a face of one of the outer plates, this face having a slot sunk therein to provide the exhaust passage and orifice. A further feature of the actuator in the preferred embodiment is that the chamber is in part defined by a cylindrical surface passing through the central plate and the orifice is in part defined by the intersection of the cylindrical surface with one of the parallel faces of the central plate. A second passage communicating with the chamber is also included, this passage positioned to provide unimpeded discharge of fluid from the chamber during its first fraction of stroke and to be blocked by the rotor during a subsequent fraction of stroke. The actuator of the preferred embodiment further features a second chamber similar to the first with correspondingly disposed exhaust passages and orifice, the first and second chambers being alternately operative for forward and backward strokes of the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows in elevation a web forming machine incorporating the invention.

FIG. la shows the same machine in plan.

FIG. 2 shows a portion of the web forming machine shown in FIG. 1 in perspective view to show the invention in greater detail.

FIG. 3 shows, in perspective view and with portions cut away, the rotary actuator shown in FIG. 2.

FIG. 4 shows a cross-sectional view taken along the section 44 of FIG. 3 to reveal further details of the apparatus.

FIG. 5 shows on an enlarged scale details of a controllir'igorifice of the actuator shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, web forming machine 10 includes web dispenser 6, softening oven 8, die frame 18 and bed 12 supporting web 14. Forming die 16' is supported for reciprocating motion. on frame 18 to form web portions, e.g., to form complete egg cartons from a continuous length of polystyrene foam sheet having 'a width of 40 inches and a thickness of oneeighth inch. Web transport mechanism 30, shown more particularly in FIG. 2, includes endless chain gripping members 32 gripping web 14 along one of its edges and similar endless chain gripping members 34 gripping web 14 along its other edge. Gripping

members

32 and 34 extend through oven 8 and past die 16, over alength L of, e.g., 20 feet, andare generally supported by

chain support bases

50 and 52 respectively. Bases 50; 52 are supported on toothed shafts 53 and may be positioned bymovement of pinion gears 55 affixed to shafts 57' to accommodate webs of various widths. Gripping members 32 are driven by sprockets 36 connected by short shafts to mutually engaged gears 38- which are in turn driven by drive gear 40 keyed to shaft 42 to permit axially sliding of gear 40'along shaft 42. Similarly, gripping members 34 are driven by sprockets 44 connected through short shafts to gears 46. Drive gear 48 affixed to shaft 42 drives gears 46. Shaft 42 'is supported in journals on'chain

support bases

50 and 52. Rotary actuator 60, the internal parts of which will be described below, is mounted on base 52 and actuates linkage 61 including crank 62, pivot 64, which is adjustable inslot 66 of crank 62, and rack 68, which is maintained in engagement with pinion 70 by keeper 72 and is'connected to crank 62 at pivot 64. I-Iydraulically operated clutch 74 alternatively engages pinion 70 to shaft 42 or permits pinion 70 to rotate freely about shaft 42. Hydraulic controller 76 of conventional design provides pressured hydraulic fluid to rotary actuator 60 through

conduits

78 and 80 and to hydraulically operated clutch 74 through conduit 82.

Base 52, together with shaft 42, drive gear 48, sprockets 44, chain gripping members 34, gears 46, actuator 60, rack 68, pinion 70, and clutch 74 supported thereon, is slidable as a unit to permit motion for adjustment to webs of distinct widths. Adjustment of pivot 64 in slot 66 provides for different stroke lengths as desired to obtain different increments of web advance.

Referring now especially to FIG. 3, rotary actuator 60 has a housing composed of center plate 100 and

outer plates

102, 104.

Plates

100, 102 and 104 are fastened together in a sandwich-like construction with faces 99 of plate 102 and face 101 of plate 100 pressed together and sealed by gasket 103 and with face 105 of plate 100 and face 106 of plate 104 pressed together and sealed by gasket 107. Central plate 100 has cavity 99, a portion 108 of the cavity being cylindrical and another portion 110 being planar. Rotor 112 is affixed to shaft 114 which is in turn journalled in

outer plates

102 and 104. Rotor 112 has vane 116 extending radially outward and supporting surface 118 in close proximity to surface portion 108 of central plate 100 and with

side surfaces

117 and 119 in close proximity to

faces

106 and 99 respectively. Surface portions 110 serve as positive rotor stops and are situated to permit rotor 1 12 to rotate through 180". Rotor 112 with its vane 116 together with

surface portions

108 and 110 of central plate 100 and the

faces

106 and 99 define chamber 120 appearing to the left as seen in FIG. 3 and chamber 122 appearing on the right. Each of

chambers

120 and 122 has a volume that is variable, dependent on the position of rotor 112. Duct 130a communicates (unless blocked by vane 116) with chamber 120, and corresponding duct 130b similarly communicates with chamber 122. Slots 132a and 132b are sunk into face 99 of outer plate 102. With the actuator assembled, slots 132a and l32b communicate respectively with

chambers

120 and 122, as shown particularly with respect to slot 132a and chamber 120 in FIGS. 4 and 5. Slot 132a also communicates through

holes

134a and 136a to duct 130a, as shown more particularly in the cross-section of FIG. 4. Slot 132b communicates in a similar manner to duct 130b although the intermediate connecting holes cannot be seen in FIG. 3 because of the removal of portions of the structure. Slot 132a therefore provides an exhaust passage for the flow of hydraulic fluid out of chamber 120 through the orifice 139a (see FIG. defined in part by edge portions 138a and 142a of slot 132a and in part by

edge portions

140a and 144a formed by the intersection of

surface portions

108 and 110 respectively with face 101. Similarly, slot l32b provides a corresponding passage and orifice for chamher 122.

In the preferred embodiment, the cavity in central plate 100 has a diameter of 6 in. in its circular portion, and a length of 3 in. in the direction of the rotor axis. The edge portion 144a of orifice 1390 is 0.090 in.; edge portion 142a is 0.030 in.; and edge portion 140a is 0.25 in. Pivot 64 is positioned at its greatest extension in. and at its least extension 3 in. from the axis of rotor 112. Pinion has a pitch diameter of4 in. Drive gears 40 and 48 have pitch diameter of l l in. Reflecting these dimensions, a single stroke of the advancing mechanism would advance the web at most 55 in. and at least 16.5 in. depending on the position of pivot 64.

The operation of the web transport mechanism is coordinated by controller 76 with the movement of die 16 so that the web is moved forward when the die is open. Taking up the cyclical operation at the point where the web is to be moved forward, vane l 16 is to the extreme right as viewed in FIG. 3 and is resting against surface 110. Crank 62 is extended straight down to be parallel to rack 68, which is in its position of extreme extension. Controller 76 initiates the web advance step by directing hydraulic fluid through conduit 82 to engage clutch 74, directing fluid through conduit into duct 130b and opening conduit 78 from duct 130a to permit discharge to a hydraulic sump. With vane 116 in its extreme rightward position, FIG. 3., direct flow of hydraulic fluid from duct 130b into chamber 122 is blocked by surface 118 of vane 1 l6 and hydraulic fluid flows through duct 136b, 134b and slot 132b into chamber 122 (which is progressively opened as the rotor turns). At the same time, controller 76 permits the free flow of hydraulic fluid from chamber through duct a and conduit 78 to the hydraulic sump. Vane 116 is accordingly driven leftward (as seen in FIG. 3) causing rotor 112 to rotate in the counterclockwise direction, FIG. 3, all movement occurring in the direction of the arrows shown. After the rotor has rotated 30, the direct outlet 130b into chamber 122 is unblocked, with a corresponding increase in speed of rotor 112. Hydraulic fluid continues to flow through duct 130b into chamber 122 which is steadily increasing in volume while at the same time hydraulic fluid flows out of chamber 120, which is diminishing in volume, through duct 130a. Corresponding to the rotation of rotor 112, crank 162 is rotated first rearward (arrow A FIG. 2) and then upwards. Initially the motion of crank 62 causes rack 68 to swing around pinion 70 without causing much rotation of pinion 70. As the rotation of crank 62 progresses, however, rack 68 is driven upwards causing rotation of pinion 70. The rotation of pinion 70 acting through now engaged clutch 74 causes rotation of shaft 42 and dependently driven drive gear 48 and gears 46, sprockets 44 and gripping members 34 at one edge of web 14 and a synchronous movement of drive gear 40, gear 48, sprockets 46 and gripping members 32 on the opposite edge of web 14 whereby web 14 is carried forward through the machine while maintained in a dimensionally stable condition. It may be noted that at the start of the stroke when crank 62 is nearly parallel to rack 68, the ratio of the rate of motion of pinion 70 and the dependently driven drive train and gripping members to the rate of motion of rotor 112 is small; that as the rotor passes through mid-stroke, when the crank is nearly at right angles with the rack, this ratio is larger; and finally at the end of the stroke when the crank is again nearly parallel to the rack, this ratio is again small. Because pinion 70 initially rotates very slowly and subsequently speeds up, the whole drive train and gripping members driven thereby are put smoothly and gradually into motion without large accelerational peaks. As rotor 112 advances farther than 90 from its original position, the rotation of pinion 70 corresponding to a given increment of rotation of crank 62 diminishes but the inertia of the drive train and especially of the massive gripping members tends to sustain the velocity of rotation of pinion 70 with the result that the stresses of the drive train are reversed and pinion 70 drives rotor 112 through rack 168. Corresponding to the reversal of stresses the fluid pressure can build up in chamber 120 to exceed the fluid pressure in chamber 122 so that actuator 60 begins to function as a brake. The braking action of actuator 60 is intensified when rotor 112 advances to a point 30 from the end of its stroke and vane 116 blocks the direct aperture into duct 130a. With direct access to duct 130a blocked, the fluid must flow out of chamber 120 through the passage provided by slot 1320. During this part of the stroke the pressure in chamber 120 is primarily controlled by the flow of fluid through orifice 139a, where the preponderant part of the pressure drop takes place. When the rotor 112 advances to within 5 of the end of its stroke, side 119 of vane 116 begins to occlude orifice 139a, so that the flow resistance for effluent hydraulic fluid is progressively increased, thus maintaining the pressure in chamber 120 even though the speed of the rotor and dependent linkage have been reduced by the previous braking action. The progressive restriction by further occlusion of orifice 139a continues until vane 116 comes gently to rest against surface 110, thereby terminating the forward movement of the advancement mechanism and the web. The braking action of the actuator during the last portion of its stroke, especially the progressively greater occlusion of the exit orifice 139a through which chamber 120 drains, brings the drive train and heavy gripping members smoothly to a halt without transient deceleration peaks.

At this point controller 76 permits the discharge of hydraulic fluid through conduit 82 to disengage clutch 74 and allow free rotation of pinion 70 on shaft 42. Fluid is also directed through conduit 78 to duct 130a while flow from duct l30b through conduit 80 is opened to the hydraulic sump. The rotor 112 of actuator 60 is thereby returned to its initial position with acceleration and braking in a manner analogous to the corresponding effects during the forward stroke, except that the drive beyond the now disengaged clutch is not placed in motion. When the vane 116 has come to rest againstsurface portion 110 thecycle is completed. Repeated operations of the cycle therefore ad vance the'web stepwise through the forming machine. The smooth action of the mechanism in starting and stopping the web and its drive train without accelerational peaks minimizes wear and misalignment in the apparatus;

The cooperating decelerating features as described avoid criticality of synchronism of the die with the transport mechanism. The die may'start to close upon the web even before the rotor reaches the positive stop because the special linkage ensures that virtually no travel of the gripping members will occur during terminal movement of the rotor.

What is claimed is:

1. In a forming machine for acting progressively upon an elongated web comprising a periodically acting forming die and web transport mechanism advancing said web periodically into said die at times when said die is open, said transport mechanism including extended gripping members extending along the length of the web and means for advancing said gripping members, the improvement wherein said advancing means comprises a hydraulic rotary actuator having a housing and a rotor mounted therein rotatable between stops through forward and backward strokes of a fraction of a revolution, said rotor and said housing coacting to define a chamber the volume of whicn varies as said rotor advances through a stroke, said actuator including a passage connected to conduct fluid relative to said chamber as said rotor advances, said passage having an orifice communicating with said chamber, which orifice, during a terminal fraction of said stroke, is progressively occluded by said rotor, thereby progressively increasing the flow resistance to the fluid of said chamber to smoothly decelerate said rotor, and linkage connected to and driven in reciprocating motion through forward and backward strokes corresponding to said rotor strokes and connected to drive said gripping members, said linkage establishing the rate of motion of said gripping members dependent upon the rate of motion of said rotor in varying ratio thereto, said ratio having its greatest value near mid-stroke and lesser values near either stroke end.

2. The forming machine of claim 1 comprising an elongated pre-heat oven and a forming die adapted to form articles from a plastic web, said web gripping members extending throughout the combined length of said oven and forming die, and constructed to grip and transport said plastic web.

3. The forming machine of claim, 1 wherein said web gripping members are carried upon an elongated, endless chain, said chain connected to a pinion, and said linkage connected to drive said pinion.

4. The device as claimed in claim 1, said linkage including an elongated crank affixed to said rotor, a pinion with axis parallel to that of said rotor connected to drive said gripping members, and a rack engaging said pinion and a pivot connectingsaid crank to said rack.

5. The device as claimed in claim 4, said crank being affixed to said rotor to extend parallel to said rack when said rotor is at the end of its forward stroke.

6. The device asclaimed in claim 4, said pivot being adjustable in distance from the rotational axis of said rotor to vary the length of said linkage stroke.

7. The device as claimed in claim l, including a clutch permitting movement of said gripping members in one direction only.

8. The device as claimed in claim 7, including a controller to operate said rotary actuator and said clutch and connected to engage said clutch during the forward stroke of said rotor and to disengage said clutch during the back stroke of said rotor, whereby repeated stroking of said rotor causes stepwise advancing of said gripping members with smooth stopping thereof.

9. The device as claimed in claim I, wherein said actuator, linkage and one of said gripping members are mounted on a base slidably supported by ways on said machine for movement to accommodate webs of distinct widths.

10. The device as claimed'in claim 9 including a drive gear with a shaft affixed thereto, supported on said base and engaged to drive said one gripping member.

11. The device as claimed in claim 1, said housing comprising a central and two outer plates with parallel faces assembled sandwich-like, said chamber being defined in part by a face of one of said outer plates, said face having a slot sunk therein to provide said passage, said orifice being in part defined by the intersection of said slot with the face of said central plate.

12. The device as claimed in claim 11, said chamber being in part defined by a cylindrical surface passing through said central plate, said orifice being in part defined by the intersection of said cylindrical surface with one of the parallel faces of said central plate.

13. The device as claimed in claim 12, including a second passage communicating with said chamber, said passage positioned to provide unimpeded discharge of said rotor.

Claims

1. In a forming machine for acting progressively upon an elongated web comprising a periodically acting forming die and web transport mechanism advancing said web periodically into said die at times when said die is open, said transport mechanism including extended gripping members extending along the length of the web and means for advancing said gripping members, the improvement wherein said advancing means comprises a hydraulic rotary actuator having a housing and a rotor mounted therein rotatable between stops through forward and backward strokes of a fraction of a revolution, said rotor and said housing coacting to define a chamber the volume of whIcn varies as said rotor advances through a stroke, said actuator including a passage connected to conduct fluid relative to said chamber as said rotor advances, said passage having an orifice communicating with said chamber, which orifice, during a terminal fraction of said stroke, is progressively occluded by said rotor, thereby progressively increasing the flow resistance to the fluid of said chamber to smoothly decelerate said rotor, and a linkage connected to and driven in reciprocating motion through forward and backward strokes corresponding to said rotor strokes and connected to drive said gripping members, said linkage establishing the rate of motion of said gripping members dependent upon the rate of motion of said rotor in varying ratio thereto, said ratio having its greatest value near mid-stroke and lesser values near either stroke end.

3. The forming machine of claim 1 wherein said web gripping members are carried upon an elongated, endless chain, said chain connected to a pinion, and said linkage connected to drive said pinion.

4. The device as claimed in claim 1, said linkage including an elongated crank affixed to said rotor, a pinion with axis parallel to that of said rotor connected to drive said gripping members, and a rack engaging said pinion and a pivot connecting said crank to said rack.

6. The device as claimed in claim 4, said pivot being adjustable in distance from the rotational axis of said rotor to vary the length of said linkage stroke.

7. The device as claimed in claim 1, including a clutch permitting movement of said gripping members in one direction only.

9. The device as claimed in claim 1, wherein said actuator, linkage and one of said gripping members are mounted on a base slidably supported by ways on said machine for movement to accommodate webs of distinct widths.

10. The device as claimed in claim 9 including a drive gear with a shaft affixed thereto, supported on said base and engaged to drive said one gripping member.

13. The device as claimed in claim 12, including a second passage communicating with said chamber, said passage positioned to provide unimpeded discharge of fluid from said chamber during a first fraction of said stroke and be blocked by said rotor during a portion of said stroke following said first fraction.

14. The device as claimed in claim 1, including a second chamber defined by said rotor and said housing and opposed across said rotor from said first mentioned chamber with correspondingly disposed second passage and orifice, Said first chamber, passage, and orifice and said second chamber, passage, and orifice alternatively operative for forward and backward strokes of said rotor.