US2865289A - Gripper construction for duplicators - Google Patents

Description

Dec. 23, 1958 w. R. FOWLIE ET AL 2,865,289

GRIFPER CONSTRUCTION FOR DUPLICATORS I Filed Oct. 5, 1956 3 Sheets-Sheet 1 frail INVENTORS Wallace B. fbwlz'd John L. Tregag b fdgarli. P115015 Q W KZ/WMM fliiornags Dec. 23, 1958 I w. R. FOWLIE ETAL 7 2,865,289

GRIPPER CONSTRUCTION FOR DUPLICATORS Filed 001;. 3, 1956 3 Sheets-Sheet 2 was INVENTORSI Zlfallace 2. fbwlze Dec. 23, 1958 w. R. FOWLIE ET AL 2,365,239

GRIPPER CONSTRUCTION FOR DUPLICATORS 3 Sheets-Sheet 3 Filed 0:31;. 3, 1956 INVENTORS ZZ/azllacc 2. 1591111123 Unite States Patent GRIPPER CUNSTRUCTIUN FOR DUPLICATORS Wallace R. Fowlie, North Riverside, John L. Tregay,

Broadview, and Edgar H. Du Bois, Chicago, 111., assignors to A. B. Dick Company, Niles, Ill., a corporation of Illinois Application October 3, 1956, Serial No. 627,529

.5 Claims. (CL 101-409) This invention relates to duplicators or other printing machines, and pertains particularly to gripper constructions for securing the leading edges of paper sheets to a printing cylinder.

One object of the present invention is to provide a new and improved gripper construction having stop means whereby the leading edge portion of the sheet to be printed is accurately and positively located and positioned with respect to the printing cylinder, so that the printed matter will be accurately registered on the sheet with respect to the leading edge thereof.

A further object is to provide a new and improved gripper construction in which sheet-guiding elements are secured to the gripper fingers and are arranged to extend at an acute angle thereto to define an acutely angled crotch therebetween, so that the sheets to be printed will slide along the guiding elements into the crotch and will be positively located therein.

It is another object to provide a new and improved gripper construction having individually fiexible and resilient gripper fingers, with stop fingers disposed therebetween and having portions extending at an acute angle to the gripper fingers to define a paper receiving crotch therebetween.

A further object is to provide a new and improved gripper construction in which the gripper fingers are moved against an anvil portion on the cylinder and are flexed a controlled amount so as to clamp the successive paper sheets between the fingers and the anvil portion.

It is a further object to provide a new and improved gripper construction which is highly eifective yet is reasonably simple and low in cost.

Further objects and advantages of the present inven- I tion will appear from the following description, taken with the accompanying drawings, in which:

Fig. 1 is a diagrammatic side elevational view of a three cylinder printing machine equipped with a gripper mechanism constituting an illustrative embodiment of the present invention.

Fig. 2 is an enlarged side elevational view showing the gripper mechanism.

Figs. 3, 4 and 5 are fragmentary enlarged cross sectional views showing successive positions of the grippers.

Fig. 6 is a fragmentary perspective view showing the gripper mechanism, as embodied in the impression cylinder of the printing machine shown in Fig. 1.

Fig. 7 is a fragmentary perspective view, similar to Fig. 6 but with portions of the impression cylinder broken away.

Fig. 8 is an exploded view showing components of the gripper mechanism.

It will be understood that the present invention may be applied to all types of duplicators and printing machines. Thus, it is merely by way of example that the drawings illustrate a three cylinder offset printing machine 10 having a plate or master cylinder 12, a blanket or oifset cylinder 14, and an impression cylinder 16. The master cylinder 12 is adapted to hold a master print- 2,865,289 Patented Dec. 23, 1958 set cylinder 14 and the impression cylinder 16.

The printing machine or duplicator 10 is provided with a gripper mechanism 18 whereby the leading edges of the successive sheets are carried into the nip between the offset and impression cylinders 14 and 16. In this case, the gripper mechanism 18 is mounted on the impression cylinder 16.

It will be seen that the impression cylinder 16 has a cylindrically curved outer surface 20 which is adapted to receive and back up the paper sheets as they are printed by the offset cylinder 14. The cylindrical portion 20 of the cylinder 16 is interrupted by a gap or slot 22 in the cylinder. At one end of the cylindrical surface 20, adjacent the gap 22, the cylinder 16 is provided with a longi tudinally extending anvil portion 24 against which the leading edges of the paper sheets are adapted to be clamped. It will be seen that the anvil portion angles inwardly or recedes from the curve of the cylindrical portion 20. The anvil portion 24 is interrupted by a plurality of slots or notches 26, for a purpose that will be described in greater detail shortly.

Gripper elements 28 are adapted to engage the anvil portion 24 so as to clamp the paper sheets to the impression. cylinder 16. It will be seen that the gripper elements 28 are swingable toward and away from the anvil portion 24, between the open and closed portions of Figs. 3 and 4.

The grippers 28 may be varied in construction, but in this case they take the form of thin, flat blades or fingers secured to a gripper shaft 30 which is rotatably mounted on the impression cylinder 16. The illustrated grippers 28 are made of spring sheet metal and are flexible and resilient. In this case, the gripper shaft 30 is square in cross section. The gripper blades 28 are clamped or otherwise secured against one fiat face 32 of the shaft 38. From Figs. 6 and 8, it will be seen that the grippers 28 are formed in pairs on two sheet metal parts 34. On each part 34, the gripper blades 28 extend laterally from a body portion 36 which is secured to the gripper shaft 30 by bolts 38 or other suitable fasteners. Thus, the sheet metal parts 34 are generally C-shaped.

It will be understood that the successive sheets to be printed are fed to the impression cylinder 16 when the grippers 28 are open, as illustrated in Fig. 3. The sheets may be fed by an suitable means, such as the upper and lower forwarding rollers 40 and 4-2 shown in Fig. l. In this arrangement, the forwarding rollers propel the sheets toward the impression cylinder 16 between upper and lower generally horizontal guide plates 44 and as. The sheets are directed toward the impression cylinder 16 in a generally horizontal direction so that the sheets will reach the cylinder 16 at a point somewhat below the nip betwen the blanket and impression cylinders 14 and 16.

The operation of the gripper mechanism 18 is timed so that the grippers 28 are open fully, as shown in Fig. 3, when the sheets are fed to the cylinder 16. In order to insure accurate positioning of the leading edge of each sheet, the gripper mechanism 18 is provided with stop means 50 which are carried by the gripper shaft 38 and are rotatable with the gripper blades 28. The illustrated stop means 50 comprise a plurality of stop fingers or blades 52 which extend generally at right angles to the gripper blades 28. The stop blades 52 intersect the plane defined by the undersides of the gripper fingers at points spaced inwardly a short distance from the ex-- treme outer ends of the gripper fingers 28. Thus, the

' gripper fingers 28 have portions 54 which extend outwardly beyond the stop fingers 52, while the stop fingers '2 have portions 56 which extend upwardly between the gripper fingers 28. The stop fingers or blades 52 have shoulder portions 58 which face upwardly under the gripper fingers 28 and are adapted to be engaged by the ,un dersides of the gripper fingers when the grippers are open, as shown in Fig. 3. r

In the illustrated construction, the stop fingers or blades are formed on a single sheet metal member 68 which is generally angle-shaped in cross section. Thus, the member 60 has two flanges 62 and 64 which are generally at right angles to each other. All of the stop fingers 52 are formed on the angle 62. The flange 64 is clamped or otherwise secured to the gripper shaft 38.

it will be seen that the shaft 30 has a fiat face 66 which is diametrically opposite from the hat face The bolts 38 may be employed to clamp the flange 6-4 against the flat face 66 of the shaft 38. Thus, the flange 6d extends generally parallel to the gripper blades 28, while the flange 62 extends upwardly toward the gripper blades, generally at right angles thereto.

It will be seen that a crotch 70 is defined between the outer portions 54 of the gripper blades 28 and the stop fingers 52. in order to guide the leading edge of each paper sheet into the crotch 70, the stop fingers 52 are provided with sheet-guiding elements 72 which extend downwardly from the plane defined by the undersides of the gripper blades 28. The sheet guiding elements 72. angle outwardly, with respect to the stop fingers 52, and extend at an acute angle to the outer portions 54 of the gripper blades 28. In this case, the sheet guiding elements 72 are formed as tongues struck out of the angle member 60 on which the stop fingers 52 are formed. Because of the outward angling of the sheetguiding tongues '72, the paper-receiving crotch 78 is acutely angled.

As already indicated, the sheets may be fed horizontally to the impression cylinder 16 at a point somewhat below the nip between the blanket and the impression cylinders 14 and 16. The leading edge of the sheet strikes the sheet-guiding tongues 72 somewhat below the outer portions 54 of the gripper fingers. Because of the outward angling of the tongues 72, the edge of the sheet is deflected upwardly along the tongues and into the crotch'7-0. Thus, the position of the sheet is positively and accurately determined by the crotch 7th. As the grippers 28 close, the leading edge of the sheet remains in the crotch. Thus, the sheets are positioned peripherally with respect to the impression cylinder 16 with a high degree of accuracy and reproducibility. Accordingly, the

registration of the printed matter with respect to the head of the sheet is maintained and controlled with great accuracy.

It has already been indicated that the gripper blades 28 are opened fully (Fig. 3) to receive the paper sheets and then are closed to clamp the successive sheets against the anvil portion 24 so that the sheets will be carried through the nip between the blanket and impression cylinders 14 and 16 (Fig. 4-). The grippers 28 are then opened sufliciently to release the sheets, as shown in Fig. 5.

These movements are imparted to the grippers 28 by an operating mechanism '76 (Figs. 2 and 6). In the illustrated mechanism, a pinion 78 is secured to the gripper shaft 30 and is arranged to mesh with a sector gear 80 formed on a lever 81 which is swingable about a pivot 82 on the cylinder 16. A coil spring 84 is tensioned bctween the sector gear lever 81 and a cam follower arm 86 which carries a roller 88 adapted to engage a cam 96. In this case, the cam 98 is stationary while the cam follower arm 86 rotates with the impression cylinder E6. The cam 90 is secured to the mechanical frame. A coil spring 94 is tensioned between the cam follower arm 86 and an anchor 96 on the cylinder 16 so as to bias the roller 88 against the cam 98.

The cam follower arm 86 is adapted to be swung coun- A terclockwise by the positive action of the cam 90, while being swung clockwise by the spring 94. When the cam follower arm 86 is swung counterclockwise or outwardly, the spring 84 tends to swing the sector gear lever 81 counterwise so as to close the grippers 28.

The cam follower lever 86 may also impart clockwise motion to the sector gear lever 81 by virtue of a one-way lost motion connection 96, between the arm 86 and the lever 81. It will be seen that the lost motion connection 96 comprises relatively adjustable, interengageable stop elements 98 and 100 on the lever 81 and the arm 86. In this case, the stop 98 takes the form of an adjustable screw, while the stop 100 comprises a flange or lug on the arm 86 and adapted to be engaged by the screw 98.

The counterclockwise or closing movement of the sector gear lever 81 is limited by relatively adjustable stop elements 102 and 104 on the lever 81 and the cylinder 16. In the illustrated arrangement, the stop 102 comprises a flange or lug on the lever 81, while the stop 104 takes the form of an adjustable screw carried by the cylinder 16.

In the illustrated case, the gripper cam 90 has a low portion 106 adapted to permit the spring 94 to open the grippers 28. When the roller 88 engages the low portion 106, the spring 94 swings the arm 86 clockwise or inwardly. The interengaging stop elements 98 and 100 swing the gear sector clockwise, with the result that the pinion 76 and the grippers 28 are swung counterclockwise to their open position.

The cam has a high portion 108 adapted to close the grippers 28. As the roller 88 passes over the high portion 108, the arm 86 is swung counterclockwise or outwardly. The spring 84 swings the gear sector 80 counterclockwise so as to rotate the grippers 28 clockwise toward the anvil portion 24 on the cylinder 16. To provide firm clamping pressure between the gripper blades 28 and the anvil portion 24, so that the sheets will be securely clamped therebetween, the gripper shaft 30 may be rotated clockwise sufiiciently to flex the gripper fingers 28, as illustrated in Fig. 4. The gripper closing movement of the sector gear lever 81, and hence that of the gripper shaft 30, is limited bythe relatively adjustable stops 102 and 104 on the lever 81 and the cylinder 16. Thus, the position of the adjustable stop screw 104 determines the extent to which the grippers 28 are flexed. During the closing of the grippers 28, the oneway lost motion connection 96 permits overtravel of the cam follower arm relative to the gear sector lever 81. Such overtravel causes the stop flange to move away from the stop screw 98. At the same time, the spring 84 is stretched.

The cam 90 has a portion 110 of intermediate height, extending for the major portion of the periphery of the cam. The height of the portion 110 is such as to open the grippers 28 partially, so as to release the leading edge of the sheet, as shown in Fig. 5.

The released sheet is pushed away from the anvil portion 24 on the impression cylinder 16 by ejector means 112 taking the form of a plurality of ejector fingers 114 formed on a member 116 which is rotatable independently of the gripper shaft 30, but about the same axis. A cam follower arm 118 is mounted on the member 116 and is provided with a roller 120 which is engageable with a cam 122. The arm 118 rotates with the cylinder 16, while the cam 122 is secured to the cylinder shaft 92 and is essentially stationary. A coil spring 124 is stretched between the arm 118 and an anchor 126 on the cylinder 16, so as to hold the roller 120 against the cam 122.

The earn 122 has a high portion 128 adapted to swing the arm 118 and the ejector fingers 114 in a counterclockwise direction, so that the ejector fingers will push the leading edge of the sheet away from the anvil portion 24, as illustrated in Fig. 5. The ejector fingers 114 are movable through some of the slots 26 in the anvil portion 24. More specifically, the ejector fingers 114 and the sheet-guiding tongues 72 are positioned alternately in the slots 26.

The ejector cam 122 has a low portion 130 which extends for the major part of the periphery of the cam and permits the spring 194 to move the ejector fingers 114 to their retracted position, as shown in Fig. 4.

It will be apparent from Figs. 7 and 8 that the ejector fingers 114 are alignedwith the gripper fingers 28, or, in other words, are positioned directly under the gripper fingers. The ejector fingers 114 are movable through slots 132 defined between the stop fingers 52.

The operation of the gripper mechanism may be summarized by again noting that the sheets to be printed are fed toward the impression cylinder 16 so that they will engage the sheet-guiding tongues 72 which are rotatable with the grippers 28. The underside of the sheet makes an acute angle with the sheet-guiding tongues 72. Thus, the sheet is deflected upwardly so that it will slide along the tongues 72 into the crotch 70 between the stop fingers 52 and the outer portions 54 of the grippers 28. Thus, the acutely angled guiding tongues 72 insure that the sheet will be positively located in the crotch 70. The forwarding rollers 40 and 42 may be arranged to propel the sheet to a slightly greater extent than is normally necessary to seat the leading edge of the sheet in the crotch 70. The overtravel of the sheet is taken up by slight buckling of the sheet.

The grippers 28 are closed as they travel with the cylinder toward the nip between the blanket and impression cylinders 14 and 16. The closing movement of the grippers 28 is brought about by the high portion 108 of the .cam 90, which swings the cam follower lever 86 counterclockwise. The spring 84 imparts corresponding counterclockwise movement to the gear sector 80. Asa result, the pinion 78 and the grippers 28 are swung clockwise. In this case, the sectorgear 80 has a considerably greater radius than the pinion 78, with the result that the movement of the grippers 28 is magnified with respect to the movement of the sector gear 80. The grippers 28 clamp the leading edge of the sheet against the anvil portion 24, as shown in Fig. 4. In order to flex the gripper fingers 28 and thereby provide for firm clamping pressure between the fingers and the anvil portion 24, the gripper shaft 30 may be rotated slightly beyond the portion in which the gripper fingers move into clamping relation with the sheet. Such overtravel of the gripper shaft 30 is controlled by the adjustable stop screw 104, which limits the gripper closing movement of the sector gear lever 81. Any additional overtravel of the cam follower lever 84 results in separation between the stops 98 and ltl'h and stretching of the spring 84.

After the'grippers 28 pass the nip between the blanket and impression cylinders 14- and 16, the roller 88 encounters the intermediate portion 110 of the cam 90, with the result that the spring 94 swings the cam follower arm 86 clockwise. The stops 98 and 100 transmit the clockwise movement to the sector gear 80. Accordingly, the grippers 28 are swung counterclockwise away from the anvil portion 24, as shown in Fig. 5.

The high portion 128 of the ejector cam 122 swings the arm 118 and the ejector fingers 114 counterclockwise so that the fingers will push the leading edge of the sheet outwardly away from the cylinder 16. The sheet is then pealed off the impression cylinder 16 by stationary stripper elements 134 (Fig. 2).

As the grippers 28 approach the position in which the paper is fed to the cylinder 16, they are opened fully by the engagement of the roller 88 with the low portion 106 on the cam 90. The spring 94 swings the arm 86 and the sector gear 80 in a clockwise direction, so that the pinion 78 and the grippers 28 will be rotated counterclockwise. Thus, the sheet-guiding tongues 72 on the stop fingers 52 are swung outwardly beyond the periphery 6 of the, cylinder 16 so that the paper sheets will impinge upon the guide tongues 78 as the sheets are fed toward the cylinder 16.

It will be appreciated that the gripper construction of the present invention is eflective and dependable in operation, yet is reasonably simple and low .in cost. The angularity of the guide elements carried by the grippers insures that the leading edges of the sheets will be properly positioned relative to the printing cylinder.

Various modifications, alternative constructions, and equivalents may be employed without departing from the true spirit and scopeof the invention as exemplified in the foregoing description and defined in the following claims.

We claim:

1. In a printing machine, the combination comprising a printing cylinder having a cylindrically curved surface portion for receiving a sheet to be printed, an anvil portion extending longitudinally of said cylinder adjacent one end of said surface portion, a gripper shaft rotatably mounted on said cylinder adjacent said anvil portion, said shaft having diametrically opposite flat faces thereon, a plurality of flat spring sheet metal gripper blades fixed on said gripper shaft against one of said faces and having outer end portions swingable into and out of engagement with said anvil portion for clamping a sheet therebetween, an angle shaped stop member having a pair of flanges thereon extending generally at right angles to each other, one of said flanges being fixed to said gripper shaft against the opposite flat face thereon, said one flange extending from said shaft under said gripper blades and generally parallel thereto, the other flange on said stopmember having notches therein receiving said gripper blades and portions defined by the said notches and extending between said gripper blades generally at right angles thereto, said stop member having a plurality of sheet guiding tongues struck therefrom and extending outwardly from said other flange and downwardly relative to said gripper blades at an acute angle thereto, said tongues defining an acutely angled crotch between said tongues and said gripper blades for receiving and positioning the leading edges of the sheets to be printed.

2. In a printing machine, the combination comprising a printing cylinder for receiving successive sheets to be printed, said cylinder having an anvil portion against which the leading edge of each sheet is adapted to be clamped, a gripper shaft rotatably mounted on said cylinder adjacent said anvil portion, a plurality of flat, flexible, resilient gripper fingers secured to said shaft and swingable into and out of engagement with said anvil portion for clamping the leading edge of each sheet therebetween, a plurality of stop fingers secured to said shaft and extending between said gripper fingers generally at right angles thereto, a plurality of sheet-guiding elements fixed on said stop fingers and extending downwardly from the underside of said gripper fingers, said gripper fingers having outer portions extending beyond said stop fingers, said sheet-guiding elements on said stop fingers extending at an acute angle to said outer portions of said gripper fingers and defining an acutely angled crotch therebetween for receiving and positioning the leading edge of each successive sheet to be printed, a pinion secured to said gripper shaft, a gear sector meshing with said pinion and mounted on said cylinder for swinging movement about a predetermined axis, a nonrotatahle cam coaxial with said cylinder, a cam follower arm swingable on said cylinder about said predetermined axis and having a roller engageable with said cam, a first spring connected between said cylinder and said cam follower arm for biasing said roller against said earn, a second spring connected between said follower arm and said gear sector and operative to swing said gear sector in a first direction in response to outward movement of said follower arm by said cam, said movement 'of said gear sector in said first direction being operative to swing said gripper fingers against said anvil portion, said second spring being yieldable to provide for outward overtravel of said cam follower arm, relatively adjustable stop elements on said cylinder and said gear sector for limiting movement of said gear sector in said first direction, and relatively adjustable stop elements on said follower arm and said gear sector for swinging said gear sector in a second opposite direction in response to inward movement of said cam follower arm for swinging said gripper fingers away from said anvil portion.

3. In a printing machine, the combination comprising a printing cylinder having a cylindrically curved surface portion for receiving a sheet to be printed, an anvil portion extending longitudinally of said cylinder adjacent one end of said surface portion, a gripper shaft rotatably mounted on said cylinder adjacent said anvil portion, a plurality of flat spring sheet metal gripper blades fixed on said gripper shaft and having outer end portions swingable into and out of engagement with said anvil portion for clamping a sheet therebetween, a stop member fixed to said gripper shaft and having a flange thereon with notches therein receiving said gripper blades and defining finger portions extending between said gripper blades generally at right angles thereto, said stop member having a plurality of sheet guiding tongues struck from said finger portions and extending outwardly therefrom and downwardly relative to said gripper blades at an acute angle thereto, said tongues defining an acutely angled crotch between said tongues and said gripper blades for receiving and positioning the leading edges of the sheets to be printed.

4. In a printing machine, the combination comprising a printing cylinder for receiving successive sheets to be printed, said cylinder having an anvil portion against which the leading edge of each sheet is adapted to be clamped, a gripper shaft rotatably mounted on said cylinder adjacent said anvil portion, a plurality of flat, flexible, resilient gripper fingers secured to said shaft and swingable toward and away from said anvil portion for clamping the leading edge of each sheet therebetween, a plurality of stop fingers secured to said shaft and extending between said gripper fingers generally at right angles thereto, a plurality of sheet-guiding elements fixed on said stop fingers and extending downwardly from the level of the underside of said gripper fingers, said gripper fingers having outer portions extending beyond said stop fingers, said sheet-guiding elements on said stop fingers extending at an acute angle to said outer portions of said gripper fingers and defining an acutely angled crotch therebetween for receiving and positioning the leading edge of each successive sheet to be printed.

5. Ina printing machine, the combination comprising a printing cylinder for receiving successive sheets to be printed, said cylinder having an anvil portion against which the leading edge of each sheet is adapted to be clamped, a gripper shaft rotatably mounted on said cylinder adjacent said anvil portion, a plurality of gripper fingers secured to said shaft and swingable into and out of engagement with said anvil portion for clamping the leading edge of each sheet therebetween, stop means secured to said shaft and extending transversely to said gripper fingers to define a crotch therebetween for receiving and positioning the leading edge of each successive sheet to be printed, a pinion secured to said gripper shaft, a gear sector meshing with said pinion and mounted on said cylinder for swinging movement, a no-nrotatable cam coaxial with said cylinder, a cam follower arm swingable on said cylinder and having a roller engageable with said cam, a first spring connected between said cylinder and said cam follower arm for biasing said roller against said cam, a second spring connected between said follower arm and said gear sector and operative to swing said gear sector in a first direction in response to outward movement of said follower arm by said cam, said movement of said gear sector in said first direction being operative to swing said gripper fingers against said anvil portion, said second spring being yieldable to provide for outward overtravel of said cam follower arm, stop elements on said cylinder and said gear sector for limiting movement of said gear sector in said first direction, and stop elements on said follower arm and said gear sector for swinging said gear sector in a second opposite direction in response to inward movement of said cam follower arm for swinging said gripper fingers away from said anvil portion.

References Cited in the file of this patent UNITED STATES PATENTS 1,609,601 Berry Dec. 7, 1926 2,599,776 Peyrebrune June 10, 1952 2,647,462 Dell Aug. 4, 1953 2,720,165 Gullixson Oct. 11, 1955

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