US2882049A

US2882049A - Gripper for use in printing machines

Info

Publication number: US2882049A
Application number: US570102A
Authority: US
Inventors: Koch Werner
Original assignee: Roland Offsetmaschinenfabrik Faber and Schleicher AG
Current assignee: Roland Offsetmaschinenfabrik Faber and Schleicher AG; Faber and Schleicher AG
Priority date: 1955-03-12
Filing date: 1956-03-07
Publication date: 1959-04-14
Anticipated expiration: 1976-04-14

Description

April 14, 1959 w. KcH';

GRIPPER -EoR USE INPRINTING MACHINES l 5 Sheets-Sheet 1A i Filled March 7, 1956 April 14, 1959 w. Ko'cH GRIPPER FOR USE IN PRINTING MACHINES I 5 Sheets-Sheet 2 Filed March 7, 1956 .fm/@non /fRA/R Kaye/'1 3f Ham if H770 AfA/f rs Apri114,1,959g y w. KOCH' f "2,882,049

GRIPPER FQR USE vIN PRINTING MACHINES n Filed Marsh '1, 1956 5 sheets-sheet :s

vApril 14y1959A w.KocH-' 2,882,049

GRIPPER FOR USE IN PRINTING MACHINES Filed Marsh 7, 195ev l 5 sheets-shveef 4 .Im/enton April 14, 1959 w.-KCH

` GRIPPER FOR USE IN PRINTING MACHINES` 5 Sheets-Sheet 5 Filed March' '7, 195e if l;

l? L@ LL Lw United States Patent {ice 2,882,049 Patented Apr. 14, 1959 2,882,049 GRIPPER FOR USE IN PRINTING MACHINES Werner Koch, Offenbach (Main), Germany, assignor to Faber & Schleicher Aktiengesellschaft, Uf'tenbach (Main), Germany, a German body corporate Application March 7, 1956, Serial No. 570,102 Claims priority, application Germany March 12, 1955 Claims. (Cl. 271-79) This invention relates to a gripper device for use in connection with the conveying means of sheet printing machines, especially for the sheet feeding and stacking devices thereof. The device in accordance with the invention is particularly, though not exclusively, adapted for the conveyance, for example in multi-color printing machines, of the sheets in accurate registry from one printing mechanism to the next following.

Both the pregripper and the stacking gripper, and in multi-color printing machines lthe sheet conveyor also, cooperate with the printing cylinders of these machines. The feeding gripper, or pregripper, receives the sheets from the feed table and passes it to the printing cylinder, while the stacking gripper receives the printing sheets from the cylinder in order to deposit it, directly or indi-A rectly, on the stack of finished sheets. The sheet conveyor serves to take the sheets from the printing cylinder of one printing mechanism to the printing cylinder of the succeeding printing mechanism. In the moment of reception, or disposal respectively, the sheet is in contact with its front edge on one side with the surface of the printing cylinder and on its other side with the gripping means of the respective conveyer, except in the case of the pregripper in which the sheet is received not from the printing cylinder but from the feed table.

In all the aforesaid cases due consideration must be paid to the different thicknesses of the sheets, and conveying devices are known which, for that reason, are provided with devices by means of which the upper and/or lower grippers can be adjusted in a direction at right angles to the sheet surface in order to be able, at the moment of the reception, or disposal respectively, to adapt the width of the gap between the cylinder surface and the lower gripper to the thickness of the sheets to be printed.

Devices of the kind just referred to, however, are complicated in construction and expensive to produce. Another disadvantage consists in that their employment considerably prolongs the idling times of the machine, for which reason they are used in the conventional printing machines on the grippers only. In connection with the stacking devices and the conveyers this possibility of adjustment is, as a rule, not resorted to and, instead, one leaves the space between the cylinder surface and the gripper suiciently large to accommodate even the thickest printing material, such as cardboard for instance. This, however, encounters the other disadvantage that thin sheets are apt to stretch along their front edges during their transfer from one mechanism to the other and thus loose their registry"- for the succeeding printing operations. ln the transfer grippers of multi-color printing machines an exact transfer between the individual printing mechanisms is practically impossible.

In view of the above and other shortcomings of the known types of gripper devices the main object of the invention rests in a device in which all these disadvantages are avoided. The invention, therefore, in one of its particular aspects, consists in the provision of an upper gripper of which one part acts on one side of the sheet and is movable in relation to the gripper carrier, while in its closed position it rests against an abutment thereof, and of a lower gripper acting on the other side of the sheet opposite the upper gripper and which is also adapted to move in relation to the carrier.

Another object of the invention is the provision of a gripper in which one of the gripper parts, by which is meant either the upper 0r the lower gripper, will attain its sheet receiving position prior to the other and so that its sheet contacting surface will always remain unchangeably, though adjustably, in its receiving position, which usually is a position iiush with the surface of the printing cylinder, while the other gripper part is caused to move in timed relation toward the said first part and so as to adapt itself to the various thicknesses of the sheets.

In this way the invention renders it possible for the operative gripping surface particularly of the upper gripper to maintain its position in relation to the printing cylinder, and of both grippers in relation to the conveyer, or the gripper carrier respectively, independent of the thickness of the material to be printed. In this way any distortion or warping of the front edges of the sheets is successfully avoided and the accuracy of registry in the transportation of the sheets is ensured.

In connection with the object of the invention last referred to a further object rests in the provision of a preferably common actuating member for the two gripper parts, operating in such a manner as to cause the movement first of the upper gripper and, in timed relation thereto, of the lower gripper so as to close the latter upon the former irrespective of the thickness of the sheet which has meanwhile moved therebetween.

Waste owing to incorrect adjustment of the gripper pads or abutments will thus be avoided. The common actuating member, if such is used, also simplifies the entire mechanism which thus becomes inexpensive and yet more reliable.

A still further object of the invention is the provision of means for causing a resilient gripping action of at least one of the gripper parts, preferably of the lower gripper, for the purpose of affording a firm hold on the sheet which is gripped between the jaws of the upper and the lower gripper. The arrangement may preferably be such as will enable said resilient means to be varied in their effectiveness if required.

With these and other objects in view the invention consists in a device of the said kind, which shall be fully automatic in action and in which there will be no need ever to adjust the grippers to varying thicknesses of material, although they may be adjustable for other reasons, installation for instance.

In the gripper arrangement in accordance with the invention the lower gripper is movable in relation to the gripper carrier and for that reason may be journaled, or pivoted, in the gripper carrier or on the upper gripper. A preferred form of construction is that in which the lower gripper is in the shape of a two-arm lever which is pivoted to the upper gripper, and on the one arm of which the actuating member is caused to act, while its other arm is provided with the gripper jaw at its end and with a projection adapted to cooperate with a fixed abutment on the gripper carrier. A resilient member, such as a spring, may be interposed between the two grippers tending to move them into their open position. The force which is exerted by the actuating member on the lower gripper in the closing sense of the gripper also causes the latter to contact its abutment on the carrier with a pressure which increases with the magnitude of the said force with -which it tends to hold the sheet between the gripping surfaces of the upper and the lower gripper.

In accordance with the invention the actuating member may act positively on the lower gripper, but it has been found to be more effective if resilient means, such as a spring, are interposed between the said actuating member and the lower gripper. This is especially the case where several grippers are arranged to be controlled simultaneously, as is the custom in connection with printing machines. In order to equalize the action of the various grippers in a multiple gripper arrangement, the range of the action of the interposed resilient member may be limited as by an adjustable stop `for instance. In this case the actuating member will preferably be caused to act on the lower gripper resiliently in closing direction and positively in the opening sense. If a plurality of grippers is arranged on a common shaft, the resilient element may, of course, be interposed between the shaft and the actuating member.

Referring now to the accompanying drawings in which several modifications of the invention are illustrated by way of example, and in which Fig. 1 illustrates a sectional view of a gripper arrangement in accordance with the invention in its closed position.

Fig. 2 is a plan view thereof, partly in section.

Fig. 3 shows an intermediate position of the gripper and illustrates its resilient adaption to the various thicknesses of the sheets.

Fig. 4 is a view similar to Fig. 1 with the gripper in its open position.

Fig. 5 illustrates a modified form of the invention and is a view similar to Fig. 1.

Fig. 6 shows the same modification in an intermediate position of the gripper in a sectional view similar to Fig. 5.

Fig. 7 illustrates the same in its open position and is a view similar to Fig. 3. v

Fig. 8 is a plan view of Fig. 7, partly in section on line VIII-V111 of that gure.

Fig. 9 illustrates the invention as applied to a chain conveyor in side elevation.

Fig. 10 is a plan view of a gripper assembly in accordance with Fig. 9.

Like members are designated by like numerals throughout the various figures of the drawings.

In all the modifications shown the sheet to be conveyed may be held by the gripper, or grippers, for instance in the manner indicated in Fig. 9, in which it is shown how, at the moment of transfer from the cylinder 1 to the conveyor, the sheet is held by both the cylinder gripper and the conveyor or transfer gripper in common. The conveyor gripper may be of any known or convenient type and may be moved past the printing cylinder for instance by means of chains, a revoluble drum, an oscillating lever, or by any other means such as may be applicable to the invention hereinafter described.

The conveyor, by means of which the sheets are taken from the printing cylinder, usually comprises a plurality of grippers, of which in Fig. 2 only one is shown, and which are arranged on a carrier 3 of angular cross section which extends over the whole width of the machine. In this carrier the gripper shaft 4 for the actuation of the grippers is journaled in bearings 5 and adapted to be rocked at predetermined intervals by an arm 6 carrying a pin 7 on which is mounted a roller 8. The rocking movement of the gripper shaft is controlled by a cam 50 mounted as by bolts 49 to the frame 48 of the machine.

Freely turnable on the gripper shaft 4 is the upper gripper 9 which, in its closed position as shown in Fig 1, rests with a foot-like projection 10 on an abutment 11 in the carrier 3. 'Ihe gripper 9 is also provided with a bearing 12 mounting a cross pin 13 upon which the lower '4 gripper 14 is capable of limited pivotal movement. The said gripper K14 is forked and 'between the prongs of the fork is loosely turnable, also on the cross pin 13, a lever 15 having its lower end turned down and formed into a bearing for the reception of a pin 16 in such a manner, that it stands out to both sides from the lever 15 (Fig. 2).

To the rocking gripper shaft 4 a forked lever 17 is fastened as by means of a clamp 18 so that the pin 16 is received within the cavity formed by the arms of the lever 17. Arranged between the aforesaid lever 15 and a rearward extension 19 of the lower gripper 14 is a compression spring 20, the action of which is limited by a screw 21, while another spring 22 is arranged between the upper gripper 9 and the lower gripper 14 which has the tendency of keeping the gripper open by moving the upper part 9 away from the lower 14.

Fig. l shows the gripper in its closed position for which the gripper shaft 4 had to be rocked in counter-clockwise direction and in which the forked lever 17 acts on the pin 16 so as to compress the spring 20. Under the action of this pressure the lower gripper 14 diverts about its pivot 13 in a clockwise direction and presses the sheet 2 firmly against the jaw of the upper gripper 9 while simultaneously pressing its projection 10 onto the abutment 11 in the carrier 3. The arrangement is such that the gripping surface of the gripper 9 lies flush with the surface of the cylinder 1 so that dilerences in the thickness of the paper will cause no crumpling or other deand the entire set of grippers on the carrier made to open f and close -all simultaneously.

In order to open the

gripper

9, 14 the shaft 4 must be turned from its position of Fig. 1 in clockwise direction over the position of Fig. 3 into that shown in Fig. 4. Hereby the lever 15 which is turnable on the pin 13 of the upper gripper 9 rst comes to contact under the action of spring 20 with the head of the screw 21. On the rotation of shaft 4 being continued, lever 15, being lifted by its pin 16 and the fork 17, also lifts the tail end 19 of the lower gripper 14 by virtue of the screw 21 which is anchored therein. This again causes the lower gripper 14 to turn in counter-clockwise direction until its nose 23 becomes seated on a surface of the abutment 11. When the rotation of the gripper shaft 4 still continues, the nose 23 of the lower gripper 14 begins to press harder on the abutment 11, and the gripper 9, aided by the action of spring 22, now moves from the position of Fig. v3 into the position of Fig. 4.

:From the aforesaid and by reference especially to Figs. l, 3 and 4 of the drawings, it will be understood that at every closing of the grippers the lower gripper will adapt itself, on account of the spring 20, to any thickness of the sheets to be printed.

In the modified form of the invention which is illustrated in Figs. 5 to 8 the lower gripper 24 is pivoted on a pin 25 which corresponds to the pin 13 in the example first referred to but, in this case, is journaled in a forked bracket 26 of the abutment 27. A spring 28 partly housed in a bore of the said abutment and acting on the tail end of the lower gripper (Fig. 5) tends to turn the latter in counter-clockwise direction about its pivot 25 causing it to rest in the open position of the gripper against a projection 29 of the abutment 27 (Figs. 6 and 7). The intermediate lever 15 with its cross pin 16 and the set screw 21 with its spring 20 are similar to the like-numbered parts in the foregoing example. Merely the fork lever 17 has been replaced by a finger-cam 30 which acts in only one direction on the cross pin 16. On

the hub of the said finger-cam a projecting arm 32 is formed, which tends to exert a closing action on the upper gripper 34 over a spring 31 which is positioned between the said projection 32 and a projecting finger on the upper gripper. This position is shown in Fig. 5, where the said spring 31 is compressed and the arm 32 has moved a slight distance away from its stop 36 on the gripper 34. The gripper, in this position, is closed under the resilient action of spring 20, as will now be explained.

When the gripper shaft 4 is rocked in counter-clockwise direction from its position shown in Fig. 7 into the position of Fig. 5, the arm 32 of the cam 30 compresses the spring 31, thereby pivoting the upper gripper in also counter-clockwise direction until its abutment 33 comes to rest on the seat 35 of the iixed abutment 27. In this way, as in the aforedescribed example, the position of the gripping surface of the upper gripper 34 is caused` always to take its predetermined position flush with the outer surface of the printing cylinder 1 irrespective of the thickness of the material 2 to be printed, as is shown in Figs. 5 and 6.

To open the gripper, shaft 4 is rocked in clockwise direction until the arm 32 comes to bear on the stop 36 thereby relaxing the spring 31 (Fig. 6). Cam 30 and the arm 32 continuing on their clockwise rotation, then cause the upper gripper 34 to open under the pressure exerted by the arm 32 on the projection 36 whereby, nally, the position of Fig. 7 is reached. Simultaneously herewith the spring 20 had also expanded and thereby pushed lever 15 into contact with the head of the screw 21. Hereby the lower gripper 24 pivots on its pin 25 until its lower head portion comes to rest on the projection 29 of the xed abutment 27. This position is shown in Figs. 6 and 7 from which figures the ample space can be seen which exists between the two gripper jaws and which enables them to seize between them material of any conventional thickness without the risk of the leading edges of the sheets becoming crumpled or otherwise disiigured.

Figs. 9 and 10 illustrate the invention as applied to a chain conveyer by means of which the sheets are transferred, for example, from one printing cylinder to another. Fig. 9 shows the position in which the sheet 2 is passed by the chain gripper to the printing cylinder whereby the sheet is held at its front edge jointly by the two grippers, or the two sets of grippers respectively. The grippers 40 on the cylinder 1 have just closed while the grippers 9 will be opened on the continued operation of the machine. As in the foregoing examples a plurality of grippers 40 is arranged in known manner on a shaft 41 which is journaled in the cylinder 1 and adapted to be rocked by means of the springs 42, so that the grippers 40 will close and hold the sheet along its front edge.

Keyed to the shaft 41 is a lever 43 with a cam roller 44 which, in the rotation of the cylinder 1, comes into contact with a cam 45. This cam is fixed to the inside of the machine frame and is provided to effect the opening and closing of the grippers at predetermined intervals in the rotation of the cylinder. The conveyer which is shown in cooperation with the cylinder is a chain-conveyer comprising two endless chains 46. Each of these chains circulates along one of the inside walls 48 of the machine frame over chainwheels or sprockets (not shown). Fixed to the said chains are a plurality of carriers 3 in each of which a gripper shaft 4 is revolubly journaled. A spring 47 causes partial rotation of the shaft 4 in counter-clockwise direction whereby the grippers are resiliently closed.

Also fastened to the machine frame 48 is a cam 50 by means of bolts 49, which cam, by the movement of the chain gripper, acts on the roller 8 and thereby controls over the lever 6 the opening and closing of the grippers 9 in their predetermined succession.

What I claim is:

l. In a gripping arrangement for the sheet conveyers in sheet printing machines, a gripper carrier, an upper and a lower gripper mounted on said carrier, a pin on said upper gripper, a gripper shaft on said carrier on which the upper gripper is loosely turnable in relation to the gripper carrier, a xed abutment on the said car rier, means for moving the said upper gripper into engagement with the said abutment to arrest the upper gripper when the said upper gripper reaches its sheet receiving position, said lower gripper being turnable on said pin of the upper gripper also in relation to the said carrier, and actuating means for moving the said lower gripper toward and in timed relation to the upper gripper and to continue such movement after the said upper gripper occupies its sheet receiving position on the said abutment.

2. In a gripping arrangement for the sheet conveyers in sheet printing machines, a gripper carrier, an upper gripper mounted on said carrier, and a lower gripper pivoted to said upper gripper, a gripper shaft on said carrier, said upper gripper being loosely turnable on said shaft in relation to the said carrier, a xed abutment on the said carrier, a projection on the upper gripper to contact with the said abutment thereby to arrest said upper gripper in its sheet receiving position, said lower gripper turnable on the upper gripper also in relation to the carrier, and actuating means xed to the said gripper shaft common to both the upper and the lower gripper and operable by the said gripper shaft to move the said upper and lower grippers in mutually timed relation and to continue the closing movement of the lower gripper after the upper gripper has been arrested in its sheet receiving position by the said abutment of the carrier.

3. In a gripping arrangement for the sheet conveyers in sheet printing machines, a gripper carrier, an upper and a lower gripper mounted on said carrier, said lower gripper being pivoted to said upper gripper, a gripper shaft on said carrier, said upper gripper being loosely turnable on said shaft in relation to the said carrier, a fixed abutment on the said carrier, a projection on the upper gripper to contact with said abutment thereby to determine the sheet receiving position of the said upper gripper, said lower gripper turnable on the upper gripper also in relation to the carrier, an actuating member on the said gripper shaft for moving the upper gripper into and out of its closed and open position, and a resilient member intermediate the said gripper shaft and the said upper and lower grippers for moving the lower gripper in timed relation toward and away from the said upper gripper so as always to seize the sheets to be conveyed both at the correct moment and irrespective of the thickness of the sheets.

4. In a gripping arrangement for the sheet conveyers in sheet printing machines a gripper carrier an upper and a lower gripper mounted on said carrier and each adapted to clamp between them the sheet to be conveyed, a gripper shaft on the said carrier, said upper gripper being loosely turnable on said shaft, a projection on the upper gripper, a fixed abutment on the gripper carrier to determine, by contact with the said projection, the closing stroke of the said upper gripper, a pin on the said projection, said lower gripper pivotally carried on the said pin and also having a `projection for seating the said lower gripper also upon the said abutment at a different place thereof and prior to its having attained its sheet clamping position, an actuating member iixed to the gripper shaft for moving the upper and the lower gripper into and out of their sheet receiving positions, a member loosely interposed between the upper gripper and said actuating means and also pivoted to the said pin on the projection of the upper gripper, and a spring interposed between the lower gripper and the said loosely interposed member for causing the said lower gripper 2,882,049 7 to eiect a resilient hold on the sheets to be conveyed irrespective of the thickness of the same.

5. A sheet .gripping arrangement for printing machines as set forth in claim 4, in which the effective range of the :687,281 spring between the lower gripper and the said loosely` 5 851,184 interposed member is adjustably limited by the said spring ,1,164,802 being arranged on a screw shaft. 2,730,364

References .Cteitin- Spalckhaver 1 Nov. 26, 1901 Spalckhaver Apr. 23, 1907 -Freeman Dec. 21, 1915 .Thomsen Ian. 10, 1956