US2797097A

US2797097A - Gripper for flexible sheet conveyor

Info

Publication number: US2797097A
Application number: US496125A
Authority: US
Inventors: Anton R Stobb
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-03-23
Filing date: 1955-03-23
Publication date: 1957-06-25
Anticipated expiration: 1974-06-25

Description

June25, 1957 A. R. STOBB GRIPPER FOR FLEXIBLE SHEET CONVEYOR 4 Shegts beet. 1

Filed lilarch 25, 1955 I/VI/ENTORI ANTON R. STOBB 5W :7 ATTORNEY June 25, 1957 A. R. STOBB 7 1 7 GRIPPER FOR FLEXIBLE SHEET CONVEYOR Filed March 25, 1955 4 Sheets-Sheet 2 INVENTORI 38 It: ANTO fTOBB 58 4/ 4a /9 ATTORNEV June 25, 1957 A. R. STOBB 2,797,097

GRIPPER FOR FLEXIBLE SHEET CONVEYOR 4 Sheets-Sheet. 3

Filed March 25, 1955 v //\/|/ENTOR' [i5 ANTON R. STOBB BK%/% TOPNEV June 25, 1957 A. R. STOBB GRIP-PER FOR FLEXIBLE SHEET CONVEYOR Filed March 23, 1955 4 Sheets-Sheet. 4

mmwijm lNVENTOR: ANTON -R. STOBB ATTORNEY United States Patent GRIPPER FOR FLEXIBLE SHEET CONVEYOR Anton R. Stobb, Racine, Wis.

Application March 23, 1955, Serial No. 496,125

7 Claims. (Cl. 271-82) This invention relates to the conveyance of flexible sheets, such as papers, and, more particularly, it relates to a method and means for gripping flexible sheets on conveyors.

Since this invention can be applied in the conveyance of sheets of paper, it will be explained in that regard although it should be understood that it is not limited to that application, but is limited only by the appended claims. Upon reading the following description, it will be apparent that this invention can be applied to flexible sheets of other material, such as plastic, cloth, etc.

Paper used in printing processes is, of course, cut into required lengths after repetitious printing along one continuous web of the paper. Thus, a roll of paper is fed into the printing press which repetitiously prints the impression of one printing plate along the paper. After the printing, the paper is cut into individual sections and then stacked. It is common practice to transfer the printed but uncut web of paper to a series of cylinders for cutting and subsequent conveying for stacking. Generally, the printed web is fed between two rotating cylinders which cut the paper across its width and also hold the paper for conveying it. The paper is usually held by :a plurality of pins mounted in a line across one of the cylinders whereby the paper is held across its width by having the pins puncture the paper and pass therethrough into aligned holes on the cooperating cylinder. The pins then hold the cut sheet of paper while it is carried around in the rotation of the cylinder until the pins are retracted from the paper and into the cylinder, and the paper then drops from the cylinder or another cylinder might similarly puncture the paper and transport it elsewhere.

In the foregoing outlined process, the paper is punctured with holes across its width between printed sections. To then make an acceptable appearance, the punctured ends must be trimmed from the paper. The trimming, of course, requires time and labor in addition to wasting the trimmed portion of the paper.

In addition to the foregoing, it is frequently required that the sections of the printed web be extended between two set points such as between the pins and a rotationally trailing tucker and folder. Of course, it is desired that the length of the sections be uniform to permit handling the sections with an initial setting of the cylinders. However, it is known that the sections are not always of a uniform length since different parts of a web s'hrink more or less than other parts due to drying difierences, paper irregularities, and the like. The consequence is that some of the sections will tear when subjected to certain processes such as tucking and folding. 7

It is, therefore, an object of this invention, to provide a flexible sheet gripping means and method which improves upon the present means and method and avoids the foregoing mentioned problems.

A more specific object of this invention is to provide a paper gripping means and method which clamps the paper to a moving carrier for conveyance of said paper.

2,797,097 Patented June 25, 1957 Another object of this invention is to conserve paper and time in the process of printing and handling the sheets of paper.

A further object is to provide a method and means of gripping flexible sheets on a conveyor to permit the sheets to move, with respect to the conveyor, in the direction of conveyance and a predetermined limit.

Still another object is to provide a method and means of gripping flexible sheets for conveyance thereof whereby the sheets are held to be straight and, therefore, not curved or bowed transverse to the direction of conveyance. This permits better control of the sheets as they are flat on a conveyor.

Other objects and advantages will become apparent upon reading the following description in conjunction with the accompanying drawings, wherein,

Fig. 1 is a partially sectioned view of a paper cutting and conveying cylinder having grippers for the paper.

Fig. 2 is an enlarged perspective view of the Working parts shown in Fig. 1.

Fig. 3 is an enlarged sectional view taken on the line 33 of Fig. 1.

Fig. 4 is an enlarged sectional view taken on the line 4-4 of Fig. 3.

Fig. 5 is a sectional view taken on the line 5--5 of Fig. 1.

Fig. 6 is a fragmentary right end view of the lower portion of the cylinder shown in Fig. 1 with a fragment of the cooperating cylinder also shown.

Fig. 7 is a side view of the cylinder shown in Fig. 1, but with parts removed and with the cylinder rotated ninety degrees from the Fig. 1 position.

Fig. 8 is a side elevation view of another embodiment of this invention.

Fig. 9 is a side elevational view of the embodiment shown in Fig. 8, but with parts thereof in a different position.

Fig. 10 is a side elevational view of the embodiment shown in Fig. 8 but with parts thereof in another different position.

Fig. 11 is a sectional view taken on the line 11--11 of Fig. 8 with the dotted lines showing parts thereof in a different position.

Fig. 12 is a side elevational view similar to Fig. 8, but of another embodiment of this invention.

Fig. 13 is a bottom view of the embodiment shown in Fig. 12 with the dotted lines showing parts thereof in a diiferent position.

Similar reference numerals refer to similar parts throughout the several views.

Fig. 1 shows a side view of a paper cutting and conveying cylinder or conveyor 10 mounted on an axially disposed shaft 11 to be rotatable with the shaft which is shown supported at opposite ends by ball bearings 12 located in suitable parallel and spaced apart frame members 13. The shaft is rotated by any suitable drive which rotates the cylinder in the direction of the arrows placed on Figs. 1, 5, 6, and 7.. Of course, the cylinder could be mounted and constructed in various manners and is shown to contain a hollow cylindrical member 14 which is suitably nonrotatably mounted over the shaft 11 by a pressed fit or the like. A cylindrical member 16 is shown attached to the cylinder 14 by bolts 17 to extend therefrom, through a web portion 18, to a circular exterior portion 19. The latter provides part of the circumference of the cylinder and is preferably formed as mentioned later. Also attached to the cylinder 14 is a pair of

circular end plates

21 and 22 providing the end closures for the cylinder with bolts 23 connecting the plates to the cylinder.

A rock shaft 26 is rotatably mounted in the

end plates

21 and 22 and also in the web 18. One end of the shaft 3 is non-rotatably attached by a bolt 27 to an arm 28 which imparts a rocking motion to the shaft 26 in a manner described later. A bearing 30 is preferably positioned between the end plate 21 and the arm 28 to space the latter from the end plate. The opposite end of the shaft is axially secured to the end plate 22 by means of a nut 29 which is threaded onto the shaft end 31. The latter is thus axially secure but rotatable in the cylinder 10.

As shown between Figs. 1 and 2, a paper gripper assembly 32 is attached to each opposite end of the shaft 26 to be operated by the rocking motion of the shaft. To this end, each assembly includes a biflurcated link 33 which is shown non-rotatably mounted onto the shaft 33 to rock correspondingly and consequently rock the gripper 38 through the link 36, as indicated by the dotted lines in Fig. 1. Thus, the lower gripper finger 41 is rocked about the shaft 39, and, with that motion, a sheet of paper is gripped or clamped between the finger 41 and the adjacent part of the cylinder 10. It is further preferred that the gripper be flexible to accommodate different thicknesses of paper and to dose with a yielding pressure. The gripper can thus be spring loaded to per mit the finger to flex with respect to the linkage driving it. As shown, the finger 41 is made of a flexible metal.

Since the link'33 and the gripper 38 are transverse to each other, the opposite ends of the link 36 are preferably formed to permit universal action but with a minimum of looseness.

Pins

42 and 43 rotatably attach between opposite ends of the link 36, and the link 33 and the gripper 38, respectively. The pins are, of course, disposed transverse to each other, as shown in Fig. 3. Fig. 4 shows a preferred bearing 44 mounted on the pin 42 to permit rotation of the link 36 about the axis of the pin 42 and simultaneously permit rotation of the link in any plane disposed along the axis of the pin 42. Since the connection of the link 36 on the pin 43 at the gripper 38 is the same, no looseness or binding is encountered at either

42 or 43. As shown, the link 36 is composed of two identical and opposite end pieces joined by a threaded stud 45. The link is thus composed of con: ventional bearing members and need not be described further.

Referring again to the mounting of the gripper shaft 39, it will be noted in Figs. 1 and 2 that a member 46 is radially disposed at each end portion of the shaft 26 between the cylinder 14 and the portion 19 forming the circumference of the cylinder 10. The radially inner end 47 and the. radially outer end 48 of the member 46 are respectively slidably received in a groove in each of the

parts

14 and 19. With this arrangement, the member '46 is guided as it slides axially along the cylinder 10 in a manner described later. The member 46 is shown to be composed of two

leg sections

51 and 52 with the radially outer free ends of the legs containing integral offset

portions

53 and 54. The portion 53 is arranged to provide the support for the shaft 39. upon which the gripper is rotatably mounted. Also offset from the member 46, but in this instance offset to the side thereof, is an angled piece 56 suitably attached to the side of the member 46 by bolts 57 or the like. The radially outer end 58 of the piece 56 extends to the outer circumference of the cylinder 10 and under the finger of the gripper to serve as a base and be, in effect, a part of the circumference of the cylinder 10.

It should now be apparent that the gripper assemblies are enclosed by the legs of the members 46, and the P grippers are allochirally mounted on the portions 53 of the member 46. Thus, axial movement of the members 46 correspondingly axiallydisplaces the grippers on the cylinder 10. Since the grippers clamp paper between the gripper fingers and the bases, adjustability of the members 46, axially of the cylinder 10, permits the grippers to secure papers of various widths.

To permit the adjustment of the gripper assemblies, both of the

end plates

21 and 22 and the opposite sides of the cylinder circumference 19 are preferably recessed as shown in Figs. 1, 6, and 7. Thus, the end plates are shown to each contain peripheral slots 61 and 62 with the circumferential portion 19 of the cylindrical portion 16, containing a slot 63 at opposite ends thereof to be aligned with the slots 61 of the end plates. The grippers can then move in the slots 61 and 63 when adjusted along the axis of the cylinder 10 from the shown position of maximum spacing therebetween to a position where the bases 58 abut the inner ends of the slots 63. As previously mentioned, Fig. 7 shows the cylinder 10 rotated ninety degrees from the Fig. 1 position and, therefore, the side of the cylinder with the grippers and slots is shown for the purpose of clarity.

Fig. 1 shows a preferred means for adjusting the members 46. A screw 66 is disposed parallel to the shaft 26 and it extends between the

end plates

21 and 22 to be rotatably supported thereby. The screw also rotatably passes through the web 18 and is not threaded therewith but is shown axially fixed by lock washers 67 engaged with the screw and adjacent each side of the web as shown. One end of the screw 66 contains a head 68 disposed outside of the end plate 21 to permit rotating the screw which is threadedly engaged with the members 46 through which the screw passes as shown in Fig. 2. Also, the screw is threaded in opposite directions at opposite ends thereof so that rotation of the screw in one direction will move the members 46 either toward or away from each other to effect the adjustment in the distance between the grippers as, of course, the entire gripper assemblies move along the screw 66 and the shaft 26. The key 34 retains the link 33 in a desired fixed rotated position on the shaft 26 while permitting the link to slide axially on the shaft.

Referring again to the rocking motion of the shaft 26, as best shown in Fig. 2, the motion is imparted through the arm 28 which is clamped at one end to a projecting end of the shaft while the opposite angled end of the arm contains a pin 71 enclosed by a pair of

rollers

72 and 73. The pin 71 is parallel to the shaft 26 but offset therefrom. The

rollers

72 and 73 ride in a pair of

cam grooves

74 and 76 in a plate stationarily attached to the frame 13 with the grooves disposed approximately circularly around the shaft 11. As shown, the cam grooves and rollers are always in engagement as the roller 72 rolls on the inner surface of the cam 74 in one direction of rotation and the roller 73 rolls on the outer surface of the cam 76 in the opposite direction of rotation. Thus, the pin 71 is positively and constantly controlled by the cam grooves. The latter contain an eccentric section 77 which causes the rollers and the pin 71 to move off a concentric path and correspondingly rock the shaft 26 to operate the gripper assemblies.

It should be understood that additional pairs of grippers could be mounted on the cylinder 10, and Fig. 1 shows the fingers of a pair of grippers located on the cylinder 180 degrees from the grippers 38. Each pair of grippers would then, of course, convey paper half way around the cylinder to the cylinder side opposite from the point of initial gripping.

Fig. 6 shows a fragment of the cylinder 10 and a fragment of a cooperating cylinder containing a slot 78 across the length of the cylinder 75. A'knife 79 is suit- .ably conventionally mounted in the slot 78 to project along the length of the cylinder 75.. The cylinder 10 contains a small slot 81 along the length of its circumference to receive'the projected edge of the knife 79 when the two cylinders are rotated in essential rolling contact adjacent each other in the direction of the arrows. Thus, when paper indicated at 82 is fed from a supply and between the cylinders, the knife cuts the paper and the grippers 38 clamp the paper to the conveyor to carry the cut sheet around to the opposite side of the cylinder as desired. The cycle is then repeated. Since a cycle of cutting and holding paper for conveying is well-known, no further description of the cycle is deemed to be necessary. It should also be understood that the cylinder or conveyor 75 is slotted as at 83 to permit the grippers 38 of the cylinder 10 to pivot as described.

Figs. 8 through 11 show another embodiment of the gripper. In this instance, a gripper 86 is rotatably mounted on the shaft 39 and, through a bifurcated end having ears 87, the gripper is attached to the pin 43 and the link 36. Therefore, the gripper 86 is mounted and pivotal in a manner similar to the gripper assemblies 32. The counterpart of the assembly in this embodiment also includes the member 56 suitably attached to the piece 46 by the screws 57. However, the member 56 is now shown to support a roller or movable base 88 by means of a bolt 89 with these pieces being employed in place of the previously mentioned base 58. The roller is rotatable about the axis of the bolt as a spacer 91 can be inserted to permit the roller to be free to rotate on the bolt. This arrangement presents the roller as part of the periphery of the conveyor 10 in the manner that base 58 is presented, and the paper 82 will then be guided as shown.

The gripper 86 also contains a body portion 92 which provides the portion for mounting the gripper onto the shaft 39. One side of the body 92 is shown to have a straight side ,93 to act as an abutment in the function described later. A gripper finger 94 is rotatably mounted between the cars 87 on a pin 96 and a transversely disposed pin 97 whereby the finger 94 isrotatable about the axis of both pins. One end 98 of the finger 94 is shown to extend slightly beyond an edge 99 of the gripper 86, in the Fig. 8 position, to abut a flat spring 101 which is pivotally attached to the gripper by a bolt 102. The spring engages the gripper at a spring end 103 which tends to keep the spring aligned with the gripper, as shown later. The spring and finger abutment is a flat spring on a flat edge of the finger end 98 and is, therefore, suitable to permit the spring to urge the finger in an aligned position between the ears 87 as shown by the solid lines in Fig. 11.

The opposite end 104 of the finger 94 is shown angled to the remainder of the finger and provided with a projecting tip 106 which clamps the paper 82 to the roller 88 when the gripper is in the Fig. 8 position. A compression spring 107 is shown between the gripper body 92 and the finger 94 to yieldingly urge the latter into a rotated position about the pin 96, as shown in Fig. 10.

With this construction, the link 36 will cause the gripper 86 to rock on the shaft 39 in the manner described previously. Thus, rotation of the body 92, in the direction shown in Fig. 9, moves the gripper from the Fig. 8 position to the Fig. 9 position. The finger 94 then pivots, as shown, with respect to the body 92 until the finger abuts the body edge 93. The tip 106 has then been moved axially of the roller 88 toward the outside of the main cylinder or conveyor 10 and the paper 82 is also pulled outwardly in a manner which removes any bulging across the width of the paper as, of course, a similar gripper 86 is mounted on the opposite end of the cylinder 10 as shown in Fig. 1. Since the finger 94 is spring biased, various thicknesses of paper 82, or other flexible sheets, can be clamped by the grippers.

In handling a plurality of sheets, occasionally certain of the sheets are shorter than others of the sheets due to irregular print drying and other reasons. In the event of shorter sheets, those sheets will have a greater tension to slightly rotate the roller 88. The. finger 94 is then correspondingly rotated about the pin 97 to the position shown in Fig. 11, and the paper is thus permitted to move longitudinally and adjust its position on the cylinder 10. Fig. 11 shows that the spring 101 has pivoted about its bolt 102 to be displaced with the end 98 of the finger 94. The spring end 103 is then strained to increase the tension at that end and thereby increase the tendency to return the spring 101 and the finger 94 to their aligned positions. Thus, when the finger is pivoted off the paper 82, such as in Fig. 10, the spring 101 does return the finger to the original or solid line position of Fig. 11.

In Fig. 10, the gripper 86 has rotated, in the direction of the arrow, from the Fig. 8 position to remove the finger from the paper 94. The spring 107 has, of course, urged the finger tip 106 away from the body 92 until the finger end 98 abuts the body edge 93. Upon reverse rotation and return to the Fig. 8 position, the tip 106 is pulled toward the edge 93 and correspondingly can pull the paper 82 through the distance indicated between the Fig. 10 and Fig. 8 relative positions of the tip 106. It should be noted that the pin 96 is offset from a line between the axis of the shaft 39 and the point of contact of tip 106 with the paper. The oifset is in the Fig. 9 direction of rotation of the gripper.

Figs. 12 and 13 show another embodiment of the invention with a gripper 11'1 rotatably mounted onto the shaft 39. Ears 112 are again provided on the gripper to rotatably attach to the pin 43 of the link 36. The gripper can be used with the roller '88 on the member 56 as with the previously described embodiment. A spring 113 is pivotally attached by a bolt 1 14 to the gripper 111 to form a part thereof and extend between the ears 112 to terminate in a bent end 116. The opposite end 117 of the spring 113 is curved to press against the gripper 111, as shown. Since a spring is employed, various thicknesses of paper can be clamped by the gripper. Here also the spring 113 is attached to its gripper at a point offset from the line between the axis of the shaft 39 and the point of contact of the end 116 with the paper 82. Thus, rotation of the gripper in the direction of the arrow on Fig. 12 will cause the spring finger 113 to pull the paper outwardly on the cylinder 10 as in Fig. 9. Fig. 13 shows the bottom view of the gripper 111 with the spring 113 also shown in a dotted position which is assumed when the paper 82 is pulled in the direction of the. dotted arrow. The spring end 117 is then strained and will thus cause the spring to return to an aligned position, asshown in solid lines, when the gripper is rotated 0E the paper 82.

While specific embodiments of this invention have been shown and described, the scope of the invention should be limited only by the appended claims.

I claimi 1. A flexible sheet conveyor comprising in combination a rotatable cylinder, a shaft rotatably disposed within said cylinder eccentric and parallel to the axis of said cylinder, a cam follower attached to said shaft to project beyond an end of said cylinder, a cam approximately circular and concentric with said cylinder and disposed beyond said end of said cylinder to engage said cam follower whereby rotation of said cylinder efiects a rocking motion of said shaft, a flexible sheet gripper pivotally mounted on each end of said cylinder to be aligned thereacross and pivot in a plane parallel to the axis of said cylinder to overlap a portion of the circumference of said cylinder at each end thereof, a linkage connected between said shaft and each said gripper to pivot the latter in response to the rocking motion of said shaft and thereby periodically overlap each said portion of said cylinder to clamp a flexible sheet to said cylinder and retain it during rotation of said cylinder, each said gripper including a spring biased finger attached on each said gripper at a point offset from a line between the than the other sheets and will thus be pulled in a manner axis of said shaft and said portion of said cylinder and offset in the direction of rotation of said shaft when each said gripper is pivoting to clamp said sheet and thereby causing said finger to be movable axially of said cylinder in response to increased clamping pressure to urge said sheet axially of said cylinder when clamping said sheet.

2. A flexible sheet conveyor comprising in combination a rotating cylinder, a pair of flexible sheet grippers pivotally attached to said cylinder with said grippers disposed at opposite cylinder ends, said grippers disposed to each overlap a portion of the circumference of said cylinder, a rock shaft rotatably disposed on said cylinder to be parallel to the axis thereof, a cam and a cam follower associated with said rock shaft to impart a predetermined rocking motion thereto in response to the rotation of said cylinder, a linkage attached between said shaft and each of said grippers to transmit said shaft rocking motion to said grippers for pivoting the latter to overlap each said portion of the circumference of said cylinder to clamp the rotationally leading end of said flexible sheet and retain it during rotation of said cylinder, said grippers being spring biased to effect opposite and axially outward movement of said grippers with respect to said cylinder to correspondingly urge said sheet axially outward on said cylinder in response to increased transmission of said shaft rocking motion to said grippers for tightening the latter.

3. In a conveyor for flexible sheets, the combination comprising a rotatable cylinder having two aligned slots in the circumferencethereof at opposite ends of said cylinder and extending axially thereof, a pair of flexible sheet grippers allochirally mounted on said cylinder with one of said grippers in each of said slots to be pivotal in said slots and radially beyond the circumference of said cylinder, a movable member mounted on said cylinder to be disposed in each of said slots on the circumference of said cylinder to be movable with respect to said cylinder and to be disposed radially inward from a portion of each of said grippers when the latter are in a pivoted position toward the circumference of said cylinder to grip a flexible sheet between each of said grippers and each said movable member when said sheet is fed onto said cylinder in the direction of rotation of the latter, means responsive to the rotation of said cylinder for predeterminately pivoting said grippers, said grippers and each said movable member mounted on said cylinder to be movable with respect thereto in reverse to the direction of rotation of said cylinder at the places where said sheet is gripped and While said sheet is gripped.

4. In a conveyor for flexible sheets such as paper or the like, the combination comprising a rotatable cylinder having two aligned slots disposed at the ends of the cylinder, a pair of spring biased grippers allochirally mounted on said cylinder to be movable with respect thereto in all directions and to be pivotal in said slots toward and away from the circumference of said cylinder, a rotatable member attached to said cylinder to be disposed in each of said slots on the circumference of said cylinder to be radially inward from a portion of each of said grippers when the latter are in a pivoted'position toward the circumference of said cylinder and with the axis of each said member parallel to the axis of said cylinder, means responsive to the rotation of said cylinder for pivoting said grippers toward and away from said rotatable member for gripping a flexible sheet between averse? said grippers and said rotatable member when said grippers are pivoted toward said rotatable member, a spring attached to each of said grippers to yieldingly urge said grippers into gripping position, said grippers and each said spring arranged for axially outward movement of said gripper with respect to said cylinder in response to increased gripping force, adjustment means on said cylinder engaged with said grippers and each said member to permit adjustable spacing apart of said grippers and of each said member.

5. In a device for conveying flexible sheets such as paper or the like, the combination comprising a movable member, a rock shaft rotatably mounted on said member to extend transverse to the direction of movement of the latter, a base attached to said member to be movable in the direction of movement of said member and with respect thereto, a finger mounted on said shaft to overlie an exterior portion of said movable base and to project into the path of movement of the exterior of said member and to be movable in the direction of movement of said member and with respect thereto, means responsive to the movement of said member for rocking said shaft to pivot said finger into and out of pressing relation with said movable base to clamp a flexible sheet therebetween.

6. A gripper assembly for holding flexible sheets on a conveyor, comprising in combination a gripper on said conveyor and movable into and out of a gripping position, a finger resiliently attached to said gripper to be flexible in the direction of gripping movement, a base disposed adjacent said finger at the gripping limit of movement of the latter, said finger being attached to said gripper to move with respect to said gripper in a plurality of directions including movement transverse and longitudinal of the direction of movement of said 7 conveyor.

7. A gripper assembly for flexible sheets such as paper, comprising in combination a rotatable cylinder, a rock shaft rotatably mounted on said cylinder transverse to the axis of said cylinder, a gripper mounted in a fixed position on said shaft to pivot into and out of a sheet gripping position, a base mounted on said cylinder and positioned adjacent said gripper and rota-table about an axis transverse to the axis of pivot of said gripper and rotatable with respect to said cylinder, a gripper finger resiliently attached to said gripper at a point offset from a line between said shaft and said base and in the direction of pivot of said gripper into sheet gripping position, said gripper and said finger and said base arranged for yieldingly urging said finger to said base to be movable axially of said cylinder when in a gripping position with said base to thereby pull the gripper sheet toward said shaft and with said finger and said base movable with respect to said cylinder along the line of conveyance of said sheet.

References Cited in the file of this patent UNITED STATES PATENTS 1,230,771 Pflanze June 19, 1917 1,356,184 Barber Oct. 19, 1920 1,713,644 Davis May 21, 1929 1,718,570 Maier June 25, 1929 1,730,449 Campbell Oct. 8, 1929 1,808,514 Zuckerman June 2, 1931 1,906,638 Schwartz May 2, 1933 1,937,456 Wood Nov. 28, 1933 Ennis; 4..