US2392392A - Sheet gripper - Google Patents

Description

Jan. 8, 1946.

IN VENT OR.

BY 62/9575 E Kwaamva M WM 9 M I ATTORNEYS Pie. 3

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Jan. 8, 1 946. g, KADDELAND 2,392,392

SHEET GRIPPER Filed March 12, 1942 2 Sheets-Sheet 2 IN VENTOR,

ATTORNEYJ Patented Jan. 8, 19 46 SHEET GRIPPER Christen R. Kaddeland, Shelton, Conn., assignor to Harris-Seybold-Potter Company, Cleveland, Ohio, a corporation of Delaware Original application September 4, 1941, Serial No.

. v 12 Claims. This invention relates to improvements in sheet grippers, that is to say in mechanism for' gripping sheets of paper, at their forward edges, and conveying them from a feeding means to an operating means, from one operating means to another, from an operating means to a delivery means, etc. The present invention finds its principal utility, however, in connection with endless conveyors for sheets, and is a division of my copending application, Serial No. 409,547 filed September 4, 1941.

One of the objects of the invention is the provision of sheet grippers particularly adapted for use upon endless conveyors;

Another object is the provision of gripper units with self-contained springs, .the units being adjustable along the gripper-shaft, and eliminating the necessity for separate spring means to urge the shaft toward sheet gripping position.

' Still another object is the provision of a spring arrangement such that the leverage through which the spring acts shall be greatest in the position in which the grippers are closed, at which time the spring is expanded and hence unable to exert as much force as when the grippers are open.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which:

Fig. 1 is a fragmental plan view of an endless conveyor comprising a gripper bar equipped with my improved sheet grippers.

Fig. 2 is a cross-sectional view of the gripper bar in operative relation with a drum at one end of an endless conveyor. A

Fig. 3 is a detail plan view on a larger scale showing one gripper unit and one stop unit for limiting the rotation of the gripper shaft toward sheet gripping position.

Fig. 4 is a detail sectional view on a larger scale taken substantially on the line 4-4 of Fig. 1.

Divided and this 12, 1942, Serial No. 434,401

application March Figs. 5 and 6 are further transverse detail secin connection with drums or cylinders in various sheet handling machines, it isillustrated herein as applied to an endless conveyor embodying a pair of endless chains l0 running over pairs of sprockets, not shown, and supported and guided between sprockets in tracks each of which comprises an upper member II and a lower member It.

The conveyor comprises in addition to the chains ill a plurality of transverse bars l3 mounted at their ends in the chains, each of these bars with its associated parts being adapted to grip the forward edge of a sheet and transport it from the taking position to a position at which it is transferred to another operating mechanism or to a sheet delivering mechanism.

The chains I0 comprise the usual side links H and pins l5, but contrary to usual practice, each pin l5 carries three independently rotatable rollers 16, the outer rollers bearing on runways 8 of track member l2 and the inner roller bearing upon a runway 9 of track member H. The arrangement of runways is such that each roller tends to rotate in one direction only as it'travels from one drum to the next, and looseness between the tracks and chain is eliminated. At the points of the conveyor where bars l3 are secured to chains [0, three of the pins 15 are made longer than the rest and carry flanged sleeves ll held in place by cotter pins I8. Each of the groups of three sleeves supports an end plate l9, one for each end of the bar, in the manner best shown in Fig. 7, and plate I9 is provided with two parallel slots extending in the general direction of the pitch line of the chain and one slot midway between the other slots and at right angles thereto. The sleeves ll have flat sides which fit slidably into these slots, as illustrated more in detail in my copending application previously referred to. By means of the construction described, the position of each end plate transversely of the pitch line of the chain is determined by the outermost sleeves ll and its position longitudinally of the pitch line by'the intermediate sleeve. At the same time the sleeves are free to slide in their slots to accommodate themselves to the various degrees of curvature of the chain path.

Each of the end plates I9 is formed with a lateral extension 20 which is provided with a beveled end surface 2| andbeveled side portions 22 and 23 for purposes of accurate registration with the drums over which the conveyor passes. Extensions 20 are secured by screws 24 to the end portions of gripper support bar [3 which extends across the conveyor from one extension 20 to plate extensions 20. Gripper bar I3 is provided with integral bearing portions 21 and 28 in which I is journaled gripper shaft 29. Mounted. upon this shaft at proper intervals are a plurality of grippers each of which comprises a dog 30 fixed on shaft 29 and straddling dog 30, a spring casing 33 pivoted at 34 to dog 30, and a compression spring 35 bearing against the free end wall of casing 33 and against a shouldered pin 36 which is surrounded byth'e spring, which pin is provided with a transversely elongated cavity 31 in its head that is formed as a segment of a cylinder and fits against a similarly formed head on a pin 38 set into the rear part of gripper finger 32. The construction described minimizes wear on the spring and spring rod inasmuch as a fiat seat at each end of the spring is maintained at all times. Casing 33 bears against a raised portion along one edge of bar l3, forming in effect a rail 39, and finger 32 bears against one of a series of gripper pads 40 that are elevated above the main portion Of a contact bar 40'.

Dog 30 is provided with a lug 4| for raising finger 32 when shaft 29 is turned anti-clockwise, as viewed in Fig. 5; in other words, when it is turned away from sheet gripping position. The arrangement of parts is such that spring 35 acts through a shorter leverage arm the further the finger 32 is lifted off pad 40. This characteristic of the construction is illustrated more particularly in Figs. 8 and 9 where the parts are shown in gripper closing and opening positions, respectively, the leverage through which the spring acts in Fig. 8 being represented by the length of line 42, while the leverage through which the spring acts in Fig. 9 is represented by the shorter line 43. Of course, the spring is more compressed when in the Fig. 9 position and therefore exerts greater force upon the pin 38 of the gripper finger than when the spring is in the less compressed condition shown in Fig. 8, but the increase in force is compensated for at least in :part by the difference in leverage. The character of the springs and the proportions of the parts maybe s chosen that the force which must be applied to turn shaft 29 either increases or decreases with increase in the distance of the fingers from their pads. Preferably the design is such that the required force is approximately uniform for all operating positions of the shaft.

Near one end of th bar l3 a collar 45 is secured to shaft 29 by means of a key 46. An arm 41 integral with collar 45 projects through an opening 48 in the bar and carries at its free end a roller 49 that is adapted to bear against a cam surface fl at the free end of an arm in a drum 52 over which the conveyor runs, see Fig.

2. These arms 5| in the drums at the two endsof the conveyor are actuated by suitable means, disclosed in my copending application referred to above, to swing arm 41 and shaft 29 for opening and closing the grippers at the proper times.

Collar 45 may have a spring casing 33 pivoted thereto which casing may be identical with those that are pivoted to dogs 30 and tending in like manner to turn the shaft 29 clockwise, as viewed in Fig. 6. The movement of the shaft in this direction, however, is limited by a stop finger 52' integral with collar 45 which is provided with an adjusting screw 53 that bears against a depressed surface 54 of contact bar 49'. This screw to shaft 29 by a screw 3 I, a gripper finger 32 loose 53 and the dogs 30 are adjusted to permit the shaft 29 to turn slightly farther than is required to allow the grippers to close, so that there is a slight clearance between each of the lugs 4| and its associated finger 32. The stop finger 52' and screw 53 are located near one end of the shaft 29 to one side of the position occupied by a sheet so as not to interfere with the latter.

In the operation of the mechanism described as each gripper bar approaches a drum at one end of the conveyor, it is locked in accurate register to the drum by means fully described in my aforesaid copending application, and while so locked, it transfers its sheet to the grippers of another sheet handling means, as for example to the impression cylinder of a printing press. The invention is also adapted, however, to use upon endless conveyors which retain their grip upon a sheet while it passes through a plurality of printing units or other mechanisms for operating upon the sheet. It is evident that the gripper mechanism described herein, instead of being only temporarily locked in the drum 52, may, if

desired, be constructed as a permanent part of such drum or of any other sheet handling cylinder, for example the impression cylinder of a printing or other machine, in which case, of course, the chains 10 and associated mounting devices for bar I3 would be omitted.

The gripper mechanism of this invention is particularly adapted for use in endless conveyors because the spring means is self-contained in the various units as distinguished from spring means conventionally employed at one end of a gripper bar for rocking a gripper shaft to sheet gripping position, such means generally employing springs of considerable length. In the present instance the springs 35 have the dollble function of pressing the various fingers 32 against the sheet with substantially uniform pressure, and of furnishing the principal force for rotating the shaft in the closing direction. It will be noted that the force of the spring 35 associated with each finger is applied to the finger itself which, being loose on the shaft, applies the force to the dog 30 and through the latter to the shaft. When the finger 32 meets its pad or grips a sheet therein the force of the spring is applied by the finger against the pad 49 instead of the dog 30. Thus when all the fingers are in sheet gripping position, all the dogs are free from the fingers and the shaft 29 is substantially entirely relieved of torsional stress due to springs 35. Under such conditions the shaft might be allowed to be free of any force biasing it in either direction. In the present construction, however, the spring 35 associated with collar 45 and stop finger 52' acts upon the shaft to hold the latter in its farthest clockwise position, as viewed in Fig. 6, that is, with screw 53 against-bar 40, the purpose being to cause roller 49 to properly engage cam surface 50. The

' arrangement herein described is in contrast to the usual construction in which the spring for each gripper lies directly between each dog and its associated finger, and one or more large heavy.

springs are employed to hold the fingers in gripping position against the total effect of the individual springs for each gripper, thus placing a 1. In mechanism of the character described, a

shaft, a shaft support, a plurality of dogs secured the force exerted by the unit varies with the,

to the shaft, a corresponding number of gripper fingers loose upon the shaft in association with said dogs and adapted to be turned in one direction by'the dogs, a spring for each finger, one end of which presses the finger toward sheet gripping shaft support for resisting '-movement of said mounting.

.2. In mechanism of the character described, a shaft, a rail parallel to the shaft and movable bodily therewith, a plurality of fingers on the shaft, an operative connection between the shaft and each of said fingers, a spring for each finger one end of which presses the finger toward sheet shaft, a rail parallel thereto and movable bodily therewith, a gripper finger adjustable along the shaft, an operative connection between the shaft and the finger, means for rocking the shaft to swing thefinger away from sheet gripping position, a spring one end of which presses said finger toward sheet gripping position, and a mounting for the spring pivotally connected with said shaft and comprising an abutment for the oppositeiend of the spring, said spring tending to move said mounting about its pivot, said abutment contacting said rail for resisting movement of said mounting.

4. In mechanism of the character described, a shaftga rail parallel thereto and movable bodily therewith, a gripper finger on the shaft, an operative connection between the shaft and the finger, means for rocking the shaft to swing the finger away from sheet gripping position, a spring the inner end of which presses said finger toward sheet gripping position, a spring casing comprising an abutment for the outer end of the spring, and a connection between the casing and the shaft comprising a pivot parallel to the shaft, the outer end of said casing contacting said rail. 5. In mechanism of the class described, a shaft, a rail parallel thereto and movable bodily therewith, a dog on the shaft held against rotation relative thereto, a gripper finger loose upon the shaft, means upon the dog for contacting the finger to swing the latter away from sheet gripping position when the shaft is rocked in one direction, a spring the inner end of which presses said finger toward sheet gripping position, a

spring casing comprising an abutment for the adapted to be turned in the finger retracting direction by its dog, a spring unit for each finger pivotally connected with its dog and having hearing at its opposite end against said rail. whereby angular relation between the unit and said rail, said spring units exerting force upon the fingers in the gripper closing direction.

7. In mechanism of the character described, a shaft, a rail parallel to the shaft and movable bodily therewith, a series of dogs secured on said shaft, a series of gripper fingers loose on the shaft each associated with one of said dogs and adapted to be turned in the finger opening direction by its dog, a pad for each finger against which the latter is adapted to close for gripping a sheet, a spring casing for each finger mounted at one end on a pivot parallel to said shaft carried by said dog and having bearing at its opposite end against said rail, a spring carried by each of said casings exerting force upon its finger in the closing direction, whereby the force exerted by the spring varies with the angular relation between the spring support and said rail, a lever secured to said shaft, cam means adapted to cooperate with said lever to turn said shaft, said springs constituting the principal means exerting force in opposition to said cam means when the latter acts to move the fingers in the opening direction.

8. In mechanism of the character described, a

shaft, a plurality of dogs secured to the shaft, a

corresponding number of gripper fingers loose upon the shaft in association with said dogs and .adapted to be turned in one direction by the dogs,

a gripper pad for each finger, a body rigid with said pads, and individual spring means for each finger pivotally connected withsaid shaft, said spring means having engagement with said body I 40 thereto, a gripper finger oscillatable about and adjustable along said shaft, spring means having an end bearing upon and adlustably slidable lengthwise of said rail, said spring means being adapted to rock said finger on said shaft into contact with said pad, and a dog on said shaft normally out of engagement with said finger adapted when the shaft is turned in one direction to engage and move said finger away from said pad in opposition to the force of said spring means, said I dog and said spring means being interconnected by a pivot extending parallel to said shaft.

10. In mechanism of the character described. an elongated support, a gripper pad at one side of said support, a rail at the opposite side of said support, a shaft oscillatably mounted on said support between said pad and rail, agripper finger oscillatable upon said shaft, spring means comprising a casing bearing at its outer end against said rail, said casing having a pivotal connection with said shaft and carrying a spring a shaft, bearings therefor, a support fixed with respect to said bearings, a plurality of dogs secured to said shaft, a corresponding number of gripper fingers loose upon the shaft in association with said dogs, spring means operatively dog and reacting directly against said support,

said spring. means functioning individually to urge said fingers towards closed position and collectively to oppose motion of said shalt and dogs toward finger opening position.

12. In mechanism of the character described,

a shaft, a plurality of dogs secured to said shaft,

a corresponding number or gripp r fingers loose upon the shaft in association with said dogs and adapted to be turned in one direction by the dogs,

a gripper pad for each finger, a longitudinally deformable coil spring ior each finger adapted to asoasoa press the finger against its pad, a pivotal connection between eachsaid spring and its finger for transmitting the force or the spring to the finger, a support for the opposite end of said spring, said support being fixed with respect to said pads, said pivotal connection being oflset from a line joining said shaft and said support, and the deformation 0! said spring in response to the finger opening movement of said dog being compensated by the movement of said pivoted connection toward said line,

CHRIS'I'EN R. KADDELA ND.

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