US2950913A

US2950913A - Sheet feeding apparatus

Info

Publication number: US2950913A
Application number: US778189A
Authority: US
Inventors: Alfred J Staines
Original assignee: Harris Intertype Corp
Current assignee: Harris Graphics Corp
Priority date: 1958-12-04
Filing date: 1958-12-04
Publication date: 1960-08-30
Anticipated expiration: 1977-08-30

Description

g- 1960 A. J. STAINES 2,950,913

SHEET FEEDING APPARATUS Filed Dec. 4, 1958 2 Sheets-Sheet 1 IN V EN TOR.

ALFRED J. STAINES aw/wa ATTORNEYS Aug. 30, 1960 A. J. STAINES SHEETFEEDINGAPPARATUS 2 Sheets-Sheet 2 Filed Dec. 4, 1958 FIG-6 INVEN TOR.

ALFRED J. STAINES ATTORNEYS United States Patent SHEET FEEDING APPARATUS I Alfred J. Staines, Cleveland, Ohio, assignor to Harris- Intertype Corporation, Cleveland, Ohio, a corporation of Delaware Filed Dec. 4, 1958, Ser. No. 778,189

20 Claims. Cl. 271-26) This invention relates to apparatus for feeding successive sheets of paper or similar materials froma pile.

The invention is particularly related to a sucker assembly for use, commonly in pairs, on a sheet feeder to lift the successive sheets from the pile for feeding and also to stretch or tauten each sheet in conjunction with the lifting thereof for the purpose of straightening the portion of the sheet between the pair of sucker assemblies. It is a primary object of the present invention to pro vide a sucker assembly for the purpose outlined above which is of improved and novel construction characterized by simplicity and reliability as well as by ease of adjustment to suit particular operating conditions.

A nore specific object of the invention is to provide such an improved sucker assembly wherein the lifting and stretching movements of the sucker are effected mechanically in adjustable timed relation such that the extent of either movement may be varied in accordance with the results desired for the material being handled.

Another object of the invention is to provide a sheet separating and lifting mechanism incorporating a pair of sucker assemblies of such structure and mode of operation that they are capable of moving in opposite directions outwardly of the pile while lifting each gripped sheet to stretch the sheet and thereafter moving inwardly of the pile to their original relation with the vertical before they are again lowered to grip the next sheet in'order to assure that each successive sheet will be gripped in the same proper locations thereon.

It is also an object of the invention to provide a sucker assembly for the purpose outlined above which is of such structure and mode of operation that vacuum may be applied thereto at any time'during its downward movement to grip the next sheet on the pile, and particularly wherein vacuum may be applied while the sucker is in the upper limit position of its lifting movement, in order to assure accurate operation of the assembly at high speeds.

7 Other objects and advantages of the inventionwill be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings Fig. l is a somewhat diagrammatic and fragmentary elevational view showing a sheet feeder equipped with sucker assemblies constructed and arranged in accordance with the invention for the feeding of sheets of paper, the view being opposite to the direction of feeding;

Fig. 2 is an enlarged subassembly' view taken as' indicated by the line 22 of Fig. l to show the sucker assembly at the left side of the view in Fig. 1;

Fig. 3 is an elevational view looking from right to left in Fig. 2 and illustrating the positioning of the parts for feeding sheets of cardboard;

Fig. 4 is a view taken as indicated by the line 44 in Fig. 3 with some parts removed; I

Fig. 5 is a view looking downwardly in Fig. 2; and

Fig. 6 is a view similar to Fig. 5 taken in section as indicated by the line 66 of Fig; 2. w

Referring to the drawings, which illustrate a pre- 2,950,913 Patented Aug. 30, 1960 ferred embodiment of the invention, in the fragmentary view of Fig. 1, the side frames 10 and 11 of a sheet feeder support a sheet separating and forwarding mechanism which includes

side plates

12 and 13 connected by a plurality of

shafts

14 and 15 and

tie rods

16 and 17 extending generally above and behind the pile of sheets S to be fed. The

tie rods

16 and 17 support a pair of

sucker assemblies

20 and 21 which are constructed in accordance with the invention and cooperate with the usual combers 22 and presser feet 23 to separate, lift and tauten or stretch the successive sheets S from the top of the pile. An additional shaft 24 extending across the feeder supports a pair of forwarding suckers 25 which receive the successive sheets from the suckers 20-21 and subject them to a forward feeding movement, the conventlonal practice being toprovide a plurality of such forwarding suckers which operate by periodic oscillation of the shaft 24.

, The present invention relates to the structure and mode of operation of the lifting and stretching

sucker assemblies

20 and 21, which are effectively mirror imagesof each other, and therefore only the lefehand assembly 20 of Fig. 1 is shown in detail in Figs. 2-6. The main component of this assembly is the suction cylinder 30, and it incorporates a hollow piston rod 31 having a suction mouth 32 at its lower end which is adaptedto engage the uppermost sheet. on the pileS and raise it from the pile when suction is applied to the cylinder through the line 33, which is connected with the cylinder at 34 as indicated in Fig. 2.

The cy-linder is shown in Fig. 2 as of the double acting type, andit includes an annular piston 35 at the upper end of the hollow piston rod 31 which. is normally supported by a relatively light coil spring 36. v The suction connection 34 is in turn connected by ahole 37 with the 7 annular space 38 surrounding the piston rod 31, and it is also connected by a hole 39 with the space above the piston 35 and thus to the interior of the piston rod 31 and suction mouth 32. As indicated in Fig. 2, the hole 37 is substantially larger than the hole 39, so that when 1 Vacuum is first applied to theline 33 with the suction mouth 32 uncovered, the piston rod 31 will move downwardly against the spring 36 until the suction mouth 32' is closed by engagement with a sheet, but it will then reverse its direction and move upwardly to lift the sheet In addition to the reciprocating movement of the piston rod 31 in each cylinder 30, the cylinders themselves are provided with mechanical means for raising and lowering them with respect to the pile to deliver the successive sheets to the forwarding suckers 25. Also,

the cylinders 30 are provided with further mechanical means for moving them in opposite directions outwardly of the pile while gripping each sheet to stretch or tauten the sheet, the provision is made for adjusting the extent and time relation of these mechanical movements in accordance with desired feeding conditions. p

The supporting structure for the sucker assembly 20 includes a composite bracket identified generally at 40 and mounted as shown in Fig. 2 on the

tie rods

16 and 17. This bracket 40 is adjustable axially of the tie rods in accordance with the width of the pile S, and the clamped connection at 41 secures it rigidly but releasably to the tie rod 17. Extending along the front edge of the bracket 40 is a pair of gibs 42 cooperating to form generally vertically arranged guide means for a slide 44 onwhic h'the cylinder 30 is supported for pivotal movement by means of a stud 45 and a retaining bolt and washer 46. As shown in Fig. 2, the gibs 42 v are inclined forwardly, -i. e.' in the direction of feeding,

from the vertical, and the slide 44 and stud 45 sup-- port the cylinder 30 in similarly inclined position to prevent the suction mouth 32 at the proper angle for effective gripping engagement with the corner portions of the successive sheets as they are combed by the associated comber 22.

Provision is made for mechanically reciprocating the slide 44 to raise and lower the cylinder 30. Referring particularly to Fig. 2, the shaft 15 is a cam shaft and carries a. cam 50 cooperating with a follower roller 51 carried by a bell crank 52 -mounted for rocking 'movement on the shaft 1-4, and a spring 53 maintains the roller 51 in engagement with the cam 50 at all times.

A link 55 has one end pivotally connected at 56 to the slide 44, and its other end is pivoted at 57 to a. pin 58 threadedin the end of the bell crank 52 for appropriate adjusting movement. it will be apparent from Fig. 2 that as the cam 50 rotates, it will act through the follower roller 51 to rock the bell crank 52 which will in T turn act through thelink 55 to raise and lower the slide 44 and cylinder 30 betweenupper and lower limit positions established by the throw of the cam 50 and also the adjustment of the pin 58.

The drive mechanism for causing the cylinder to v p,

combers 22 will have combed the sheet against the swing on its pivot stud .45 for stretching the sheet includes a follower roller 60 on the back side of the cylinder 30 which travels in a slotted track 61 in a guide 62 mounted for lateral movement below the gibs 42'. on its inner" side (to the right in Fig. 3) the guide 62' is supported by an L-shaped guide member 63 which is secured in depending relation to the bracket by screws, 64 as shown in Fig. 4. A stop stud 65 provided with a lock nut 66 is threaded through the guide member 63 to form an adjustable stop limiting movement of the guide 62.to the right as viewed in Fig. 3. This stop may be adjusted to establish this index position of the guide 62 such that the cylinder 30 will be aligned vertically with the gibs 42 as shown in full lines in Fig. 3 as may be desiredfor feeding cardboard or other sheet material whichv is not easily combed, and it may be adjusted to positio nrthe cylinder at an angle to the vertical causing the. suction mouths v 32 'to take combed paper sheets at an angle as shown in full lines in Fig.1. p

Movement of th g id 62 outwardly of the pile (tov the left in Fig. 3) is effected by a cam 70 on the cam shaft 15; in conjunction with a compound bell crank comprising a pair of adjustably connected

lever arms

71 and 72 arranged as best seen in Fig. 6. The lever arm 71 is pivoted on a stud 73 carried by a boss portion 74 of the bracket 40, this arm'71 carries a follower roller 75 which cooperates with the carn 7t andis crowned to compensate for angular movement of the arm 71 as the follower rides up and down on the cam. The lever arm 72 is also pivoted on the stud 73, and it is biased toward the arm 71 by a coil spring 77 connected to

pins

78 and 79 depending from the

respective arms

71 and 72. An adjustable stop screw 80 is threaded through the arm 72 and provided with a lock nut 81, and its inner end engages a stop 82 on the lever arm 71 to establish the angular spacing of the two arms 71-7 2.

The lever arm 72 is pivoted at 85 tothe guide 62, so that movement of lever arm 72 in clockwise direction as viewed in Fig. 6 about the stud 73 will cause movement of the guide 62 to the left in Fig. 3, wh ch in turn will act through the, follower 60 to swing the cylinder 30 on its pivot stud as described. Thelever arm 72 is normally biased in a counterclockwise direction in Fig. 6 by a spring 8 6-secured at its opposite end on a pin 87 depending from the bracket 40, and the stop screw 80 will therefore similarly operate through the stop..82 to force the lever arm 71 in the d rection to maintain the follower roller 75 in engagement with the cam 70. As the cam 70 rotates, therefore, the composite bell crank 7172 will rock about the-stud73 to produce the desired d lateral movement of the guide 62 and swinging movement of the cylinder 30.

The extent of this movement of the bell crank 7172 and guide 62 for a cam 78 of given design is determined by the adjustment of the stop screw 80. Since movement of the bell crank in counterclockwise direction in Fig. 6 is limited by engagement of the guide 62 with its stop 65, then as the screw 80 is backed off, the spring 77 will draw the lever arm 71 away from the cam to such extent that the follower roller 75 will be out of engagement with the cam for a portion of its cycle. The maximumvstroke for theguide 62 is therefore established when the roller 75 is in continuous engagement with the cam '70,v and the: parts are preferably so proportioned that it is possible to adjust the arm 71 to a presser feet 23' which are in engagement with the pile along the back edge and act as a backstop for the combing action. As soon as vacuum is applied to the line 33, the piston rod 31 will move downwardly as described until the suction mouth 32 is closed by the uppermost of-the' sheets 8', whereupon it will reverse its direction of movement and start to raise the sheet pneumatically. Such reversal will cause the rear corners only of the sheet to be lifted a short distance as indicated in dotted lines in Fig. 1, the remaining portion of the sheet still being held by the presser feet 23.

As the cam 50continues to turn in clockwise direction as viewed'in Fig. 2, theb'ell crank 52 will begin to rock in counterclockwise direction and thereby to raise the slide 44 which carries with it the cylinder 30. While this lifting move 'is taking place; conventional means (not shown) will move the presser'feet 23 to the position shown, in dotted lines in Fig. 2. The cam 70 will also be rotating andwill'act through the bell crank 71'72' to move the guide 62 laterally as indicated in Fig; 3, and the resulting lateral movement of the follower will cause the cylinder 30 to swing outwardly of the pile-on itspivotstud 45 while it.is moving upwardly.

This lateral inovement causes the sheet to be tautened or stretched as. already noted, and as, indicated by the upper dotted showing of the cylinders 30 in Fig. 1.

,Thetautening of the. gripped sheet will have been completed by the timethe sheet is raised to the level of the forwarding suckers 25,, which will preferably have vacuum on at the time the sheet reaches that level. This fully accomplished by that time. While the sheet is being lifted mechanically, the presser feet are returned to clampv the nextsheet against the pile and thereby to prevent fluttering of the top sheets of the pile when a' forwarding'air blast is directed under the sheet being.

forwarded in the customary member.

The cams 50 are designed ,as shown to cause the cylinders 30 to dwell in their upper limit position after transferring the sheet to the-fbrwarding suckers 25, and attheconclusi'on of the dwell, the cylinders 30 will begin to descend in preparation for lifting the next sheet. Preferably the drive for each of the guides 62 is so adjusted that each guide 62will be returned to its index position against its associated stop 65 duringthe dwell of the cylinders 30 so that the downward strokes of the cylinders. will be vertical even though the stops 65 may have been adjusted to incline the cylinders slightly as described, Suchyertiehl'downward movement makes it certain that each successive sheet will be grasped in the same position regardless of slight changes in pile height during normal feeding, or slight differences in height from one corner of the pile to the other, and it also makes it possible to achieve this result without critical adjustment of the vacuum control for the cylinders 30. In fact, the vacuum control will preferably be so adjusted that vacuum will be applied in the lines 33 when the cylinders 30 are not more than mid way on their downward strokes in order that the piston rods 31 can begin to extend toward the pile before the cylinders reach their lower limit positions.

It will be apparent that the timed relation of the lifting and stretching movements of the cylinders 30 is readily adjusted in accordance with the relationship of the

cams

50 and 70, in addition to the provision for adjustment of the extent of stretching movement of the cylinders by relative adjustment of the bell crank

arms

71 and 72 as already described. This adjustment may also effect the timed relation of the lifting and stretching movements, since if the parts are set for maximum stretching, some of this movement may occur before the upward mechanical stroke of the cylinder 30 begins. At the same time, it will be apparent that under all adjusted conditions, the sequence of operation will include first a short pneumatic lifting of the corners of the sheet by movement of the piston rods 31 in the cylinders 30, followed by a mechanical raising and lowering of the cylinders which is accompanied by the outward movement of the cylinders for stretching the sheet, and the return movement of the cylinders to their index positions may in all cases be caused to take place before the cylinders begin their downward strokes.

While the invention is of course not limited to the illustrated embodiment, the particular construction shown in the drawings does demonstrate a variety of advantages provided by the invention. For example, the use of a double acting cylinder in connection with the mechanical means for raising and lowering the cylinders and the mechanical means for moving them out and in for stretching provides great versatility in adjustment of the operating cycle. In particular, it eliminates any critical factor in the time for reapplying vacuum to the cylinders after a sheet has been transferred therefrom, since the construction of the invention makes it possible to return the cylinders to their index positions with respect to the vertical while they are at or near their upper limit positions of vertical travel, and thus in turn makes it possible to turn on the vacuum well in advance of arrival of the cylinders at their lower limit positions While still assuring that each successive sheet will be gripped in the same relative places.

It is also an important advantage of the invention that the lifting and tautening operations are carried out by separately adjustable mechanical means. For example, this makes it possible to adjust the extent of either movement and also their time relation to each other, and in particular it is possible with the structure of the invention to cause the tautening movement to coincide with a desired portion of the lifting movement. Also the several drive means are readily adjusted to cause greater stretching toward one side of the pile than the other, by making different adjustments for the tWo bell cranks 71-72.

It is a further advantage of the invention that the mechanical lifting movements at opposite sides of the sheet are easily synchronized, but the individual suckers are not required to act in unison, and therefore stretching will always take place in the proper horizontal plane even if there should be discrepancies in height across the ile. All of these factors contribute not only to maintained accuracy of operation but especially to increased speed of operation without scrificing accuracy.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be 6 understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

l. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, movable guide means associated with said cylinder and extending generally in the same direction as said stationary guide means, a follower on said cylinder movable therewith along said movable guide means, means mounting said movable guide means for movement generally laterally of the pile with respect to said stationary guide means, and means for moving said slide and said movable guide means in timed relation causing saidcylinder to swing on said axis outwardly of the pile and to rise with said slide. 7

2. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary, guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, movable guide means associated with said cylinder and including a track extending substantially parallel with said stationary guide means, a follower on said cylinder movable therewith along said track, means mounting said movable guide means for movement generally normally of said track with respect to said stationary guide means, and means for moving said slide and said movable guide means in timed relation causing said cylinder to swing on said axis outwardly of the pile and to rise with said slide.

3. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, movable guide means associated with said cylinder and extending generally in the same direction as said stationary guide means, a follower on said cylinder movable therewith along said movable guide means, means mounting said movable guide means for movement generally laterally of the pile with respect to said stationary guide means, means for moving said slide and said movable guide means in timed relation causing said cylinder to swing on said axis outwardly of the pile and to rise with said slide, and adjustable means for regulating the extent of said swinging movement of said cylin der by varying the extent of said movement of said movable guide means.

4. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile' thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on. the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, movable guide means associated with said cylinder and extending generally in the same direction as said stationary guide means, a follower on said cylinder movable therewith along said movable guide means, means mounting said movable guide means for movement generally laterally of the pile with respect to said stationary guide means, means including a bell crank connected with said movable guide means for causing said lateral movement thereof, and means for moving said slide and rocking said bell crank in timed relation causing said cylinder to swing on said axis outwardly of the pile and to rise with said slide.

5. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile there of and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, movable guide means associated with said cylinder and extending generally in the same direction as said stationary guide means, a follower on said cylinder movable therewith along said movable guide means, means mounting said movable guide means for move ment generally later-ally of the pile with respect to said stationary guide means, means establishing an index position of said movable guide means wherein said cylinder will move with said slide without swinging on said axis, means including a pair of pivotally connected lever arms forming a bell crank for moving said movable guide means, means connecting one of said arms with said movable guide means, a rotary cam mounted for driving engagement with the other of said lever arms to cause rocking of said bell crank and said lateral movement of said movable guide means with respect to said index position, means for moving said slide and rotating said cam in timed relation causing said cylinder to swing on said axis outwardly of the pile and to rise with said slide, and means for adjusting said lever arms with respect to each other to vary the extent of said lateral movement of said movable guide means.

6. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting saidcylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, mechanical drive means having an operati've connection with said cylinder for causing said cylinder to swing on said axis generally laterally of the pile with respect to said stationary guide means to stretch the gripped sheet, and means for moving said slide and actuating said drive means in time relation causing said cylinder to'swing outwardly on said axis and to rise with said slide.

7. A device of the character described for use in a sheet feeder for liftingand stretching successive sheets from a pile thereof, comprising .a double acting suction cylinder in l ding means responsive to the application of suction thereto to grip .the luppermost sheet on the pile, a supporting slide for said cylinder and to carryout a short upward stroke therewith with respect to said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, mechanical drive means having an operative connection with said cylinder for causing said cylinder to swing on said axis generally laterally of the pile with respect to saidistationary guide means to stretch the gripped sheet, and means for moving said slide and actuating said drive means in timed relation causing said cylinder to swing outwardly on said axis and to rise with said slide.

8. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, mechanical drive means including a bell crank having an operative connection with said cylinder for causing said cylinder to swing on said axis generally laterally of the pile with respect to said stationary guide means to stretch the gripped sheet, and means for moving said slide and rocking said bell crank in timed relation causing said cylinder to swing outwardly on said axis and to rise with said slide.

9. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, means including a bell crank having an operative connection with said cylinder for causing said cylinder to swing on said axis generally laterally of the pile with respect to said stationary guide means to stretch the gripped sheet, means for moving said slide and rocking said bell crank in timed relation causing said cylinder to swing outwardly on said axis and to rise with said slide, and means for changing the degree of said rocking movement of said bell crank to change the extent of said swinging movement of said cylinder independently of said movement of said slide.

10. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets'to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, means biasing said cylinder to an index position on said slide, means including a pair of pivotally connected lever arms forming a bell crank for effecting swinging of said cylinder on said axis, means connecting one of said arms with said cylinder, a rotary cam mounted for driving engagement with the other of said lever arms to cause rocking of said bell crank and said swinging movement 9 of said cylinder against said biasing means, means for moving said slide and rotating said cam in timed relation causing said cylinder to swing on said axis outwardly of the pile and to rise with said slide, and means for adjusting said lever arms with respect to each other to vary the extent of said swinging movement of said cylinder.

11. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, means biasing said cylinder to an index position on said slide, means including a pair of pivotally connected lever arms forming a bell crank for effecting swinging of said cylinder on said axis, meansconnecting one of said arms with said cylinder, a rotary cam mounted for driving engagement with the other of said lever arms to cause rocking of said bell crank and said swinging movement of said cylinder against said biasing means, means for moving said slide and rotating said cam in timed relation causing said cylinder to swing on said axis outwardly of the pile and to rise with said slide, means biasing said lever arms toward each other, and an adjustable stop member carried by one of said arms for adjustable engagement with the other said arm varying the angular relation therebetween to vary the extent of said swinging movement of said cylinder.

12. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, a rotary drive shaft, means forming a mechanical connection between said shaft and said slide for causing said slide to move up and down as said shaft rotates, and means forming a seperate mechanical connection between said cylinder and said shaft for causing said cylinder to swing on said axis independently of said up and down movement of said slide.

13. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile, a supporting slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said-cylinder and the sheet gripped thereby, a rotary drive shaft, a pair of cams on said shaft, means forming a mechanical connection between one of said cams and said slide for causing said slide to move up and down as said cam rotates, and means forming a mechanical connection between said cylinder and the other of said cams for causing said cylinder to swing on said axis independently of said up and down movement of said slide.

14. A device of the character described for use in a sheet feeder for liftingsucessive sheets from a pile thereof and subjecting such sheets to stretching, comprising a suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile,

asup'portin'g slide for said cylinder, means pivoting said cylinder on said slide for swinging movement about an axis extending generally parallel with the direction of feeding of the sheets, stationary guide means mounting said slide for generally vertical movement with respect to the pile to raise said cylinder and the sheet gripped thereby, a rotary drive shaft, means forming a mechanical connection between said shaft and said slide for causing said slide to move up and down as said shaft rotates, means forming a separate mechanical connection between said cylinder and said shaft for causing said cylinder to-swing on said axis independently of said up and down movement of said slide, and means for adjusting at least one of said mechanical connections to vary the extent of movement transmitted therethrough to said cylinder.

15. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a double acting suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile and to carry out a short upward stroke therewith with respect to said cylinder, means establishing an index position of said cylinder with respect to the vertical, first mechanical means for raising said cylinder to lift the gripped sheet, second mechanical means independent of the first mechanical means for moving said cylinder outwardly of the pile from said index position to stretch the gripped sheet and for moving said cylinder back to said index position, and adjustable means for said second mechanical means for causing said operations thereof to take place in predetermined timed relation.

16. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a double acting suction cylinder, first mechanical means for raising and lowering said cylinder and including means establishing a lower limit position for said cylinder, second mechanical means for moving said cylinder outwardly of the pile from a predetermined index position with respect to the vertical and for moving said cylinder back to said index position, said cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile and to lift the gripped sheet with respect to said cylinder, drive means having separate connections with each of said mechanical means and means for adjusting said connection be-' tween said drive means and said second mechanical means to cause said operations of both said mechanical means to take place in predetermined timed relation such that said outward movement of said cylinder is completed before said cylinder begins to be lowered and said movement of said cylinder back to said index position is completed before said cylinder reaches said lower limit position.

17. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile there of and subjecting such sheets to stretching, comprising a double acting suction cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile and to carry out a short upward stroke therewith with respect to said cylinder, stop means establishing an index position of said cylinder with respect to the vertical, first mechanical means for raising said cylinder to lift the gripped sheet, second mechanical means for moving said cylinder outwardly of the pile from said index position to stretch the gripped sheet and for moving said cylinder back to said index position, drive means having separate connections with said first and second mechanical means, means for separately adjusting at least one of said connections to cause said operations of said mechanical means to take place in predetermined timed relation, and means for adjusting said stop means to vary said index position.

18. A device of the character described for use in a sheet 'feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a double acting suction cylinder, first'mechanical means for raising and lowering said cylinder and including means establishing a lower limit position for said cylinder, second mechanical means for moving-said cylinder outwardly of the pile froma predetermined index position with respect to the vertical and for returning said cylinder to said index position, said cylinder including means responsive to the application :of suction thereto to grip the top sheet on the pile and to lift the gripped sheet with respect to said cylinder, and drive means for said first and second mechanical means for causing said operations thereof to take place in predetermined timed relation such that said outward and return movement of said cylinder from and to said index position is completed substantially before saidcylinder reaches said lower limit position.

19. A device of the character described for use in a sheet feeder for lifting successive sheets from a pile thereof and subjecting such sheets to stretching, comprising a double acting suction cylinder including means responsive to the application of suction thereto to grip the :top sheet on the pile and to carry out a short upward stroke therewith with respect to said cylinder, means establishing an index position of said cylinder with respect to the vertical, first mechanical means for raising said cylinder to lift the gripped sheet, second mechanical means for moving said cylinder outwardly of the pile from said index position to stretch the gripped sheet and for moving said cylinder back to said index position, and means for adjusting the extent of said movement of said second mechanical means and the time relationship of said movement thereof to the operation of said first mechanical means.

20. A device of .the character described fornse in a sheet feeder for lifting successive sheets vfrom a pile thereof and subjecting such sheets to stretching, comprising a double acting suction cylinder, mechanical means for naising and lowering said cylinder .and including means establishing upper and lower limit positions for said cylinder, additional mechanical means for moving said cylinder outwardly of the pile from apredetermined index position with respect to the vertical and for returning said cylinder to said index position, said cylinder including means responsive to the application of suction thereto to grip the top sheet on the pile and to lift the gripped sheet with respect to said cylinder in said lower limit position, and drive means for said mechanical means including means for causing said cylinder .to dwell in said upper limit position and for causing said return movement of said cylinder to said index position during said dwell.

References Cited in the file of this patent UNITED STATES PATENTS 2,108,702 Backhouse Feb. 15., 1938 2,222,459 Backhouse 'Nov. 19, 1940 2,233,935 Backhouse Mar. 4, 1941 2,389,480 :Baker Nov. 20, 194.5 2,395,527 Woolford Feb. 26, 1946 2,799,499 JPerry et al July 16, 1957 FOREIGN PATENTS 1,110,126 France Feb. 6, 1956