Apparatus for picking up an auxiliary stack when conveying sheets in a printing machine

Abstract

An apparatus for picking up an auxiliary stack when conveying sheets in a printing machine that makes it possible to reduce constraining forces when guiding loadbearing elements. The apparatus has loadbearing elements disposed on a crossmember for the auxiliary stack, the loadbearing elements being fastened to the crossmember so as to pivot in at least two degrees of freedom.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to an apparatus for picking up an auxiliary stack when conveying sheets in a printing machine.

German Patent DE 41 29 164 C1, corresponding to U.S. Pat. No. 5,242,261 to Pollich et al., describes a device for combining a residual sheet stack and a main sheet stack in the feeder of a sheet-fed printing press. The device includes a load bearing plate for the residual sheet stack, which has rectangular grooves on its upper side. Rigid, straight, rectangular rods are provided at the spacing of the grooves for the temporary support of the residual stack. The rods are fastened rigidly to a crossmember.

German Published, Non-Prosecuted Patent Application DE 197 38 029 A1 contains a sheet feeder for a printing press, having an auxiliary stacking table in which rods are provided that are disposed parallel to one another and can be inserted into the plane of a stack. In a first embodiment, resilient mounting of the rods in the form of a flexible crossmember is provided.

The resilient mounting has the effect that there is a difference in travel between the rods when the auxiliary stacking table is pulled out of the sheet feeder. In a further embodiment, one part of the rods is fastened fixedly to a crossmember while another part of the rods is associated with the crossmember through springs. Each spring is associated with a rod guide in which a rod can slide in the longitudinal direction.

The crossmember is moved with a drive to insert the rods into the grooves. Here, there are stringent requirements placed on the dimensions and spacings of the grooves and rods and on the positioning system for the crossmember. In order for it to be possible to guide the rods as freely as possible in the grooves, it is necessary to expend large amounts on costs and material.

In the stacking table with a device for refreshing a stack during continuous operation of a sheet-processing machine according to German Published, Non-Prosecuted Patent Application DE 42 15 791 A1, self-supporting chains are used as deposition elements for an auxiliary stack. The chains are seated on chain sprockets in a parallel configuration. To insert the chain ends into the grooves of a stack board, a motor that acts on the chain sprockets is provided and guide plates and tubular pieces to guide the chains. The mobility of the chains is defined by the geometry of the chain sprockets and chain links.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide an apparatus for picking up an auxiliary stack when conveying sheets in a printing machine that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that makes it possible to reduce constraining forces when guiding loadbearing elements.

With the foregoing and other objects in view, there is provided, in accordance with the invention, an apparatus for picking up an auxiliary stack when conveying sheets in a printing machine, including a crossmember and loadbearing elements being disposed at the crossmember for picking up the auxiliary stack, the loadbearing elements being fastened movably to the crossmember to pivot in at least two degrees of freedom.

In accordance with another feature of the invention, there is provided a chain mechanism, the crossmember having two sides and being coupled to the chain mechanism on both of the two sides, and the loadbearing elements being members pivotably connected to the crossmember.

In accordance with a further feature of the invention, the invention can be applied particularly advantageously in apparatuses in which pivotably connected members that can be moved on a curved path are used as loadbearing elements.

In accordance with an added feature of the invention, the apparatus takes up a small amount of volume in such a variant. The ends of the loadbearing elements can be fastened in cutouts in the crossmember through joints.

In accordance with an additional feature of the invention, the at least one joint movably connects the at least one loadbearing element to the crossmember.

In accordance with yet another feature of the invention, the walls of a cutout can simultaneously form stops for the movement of a loadbearing element.

In accordance with yet a further feature of the invention, in order for it to be possible to operate with constraining forces that are as low as possible, a loadbearing element can be coupled to a crossmember through a joint that permits movement in four degrees of freedom. In particular, a universal joint can be provided between the crossmember and a loadbearing element.

If, for supporting a stack, a pallet is used that has grooves in which the loadbearing elements are positioned, the loadbearing elements can be disposed in the crossmember so as to be displaceable within limits in the direction of the movement out of the grooves. Here, pairs of the loadbearing elements can have different limit regions for the displacement.

With the objects of the invention in view, there is also provided an apparatus for picking up an auxiliary stack when conveying sheets in a printing machine, including a crossmember moving on a curved path and having cutouts, loadbearing elements being disposed at the crossmember for picking up the auxiliary stack, and at least one joint being disposed in at least one of the cutouts between the crossmember and at least one of the loadbearing elements and movably connecting the at least one loadbearing element to the crossmember in at least two degrees of freedom.

With the objects of the invention in view, there is also provided an apparatus for picking up an auxiliary stack when conveying sheets in a printing machine, including a guide to be disposed adjacent a location for the auxiliary stack in the printing machine, a crossmember movably disposed at the guide, and loadbearing elements disposed at the crossmember for moving the auxiliary stack, the loadbearing elements being operatively connected to the crossmember to pivot in at least two degrees of freedom.

With the objects of the invention in view, in a printing machine having an auxiliary stack holding sheets, there is also provided an apparatus for picking up the auxiliary stack when conveying the sheets including a crossmember and loadbearing elements disposed at the crossmember for picking up the auxiliary stack, the loadbearing elements being fastened movably to the crossmember to pivot in at least two degrees of freedom.

Other features that are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in an apparatus for picking up an auxiliary stack when conveying sheets in a printing machine, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, cross-sectional view of a feeder of a sheet-fed printing press according to the invention;

FIG. 2 is a partially hidden and perspective view of loadbearing elements according to the invention fastened to a crossmember;

FIG. 3 is a fragmentary, cross-sectional view of loadbearing elements inserted into grooves in a pallet according to the invention;

FIG. 4 is a fragmentary, cross-sectional view of a guide for a crossmember for loadbearing elements;

FIG. 5 is a fragmentary, cross-sectional view of the guide of FIG. 4 along section lien V-V;

FIG. 6 is a fragmentary, cross-sectional view of joints according to the invention for attaching loadbearing elements to a crossmember;

FIG. 7 is a fragmentary, cross-sectional view of the joints of FIG. 6 but rotated one-quarter turn; and

FIG. 8 is a fragmentary, cross-sectional view of an attachment of loadbearing elements according to the invention with axial play.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown a feeder 1 and a first printing unit 2 of a sheet-fed offset printing press. The printing unit 2 includes an inking unit 3, a dampening unit 4, a form cylinder 5, a transport cylinder 6, an impression cylinder 7, a feed cylinder 8, and a transfer drum 9. A pallet 10 on which a stack 11 is situated belongs to the feeder 1. The pallet 10 lies on a stacking table 12 that can be positioned in the vertical direction 15 with the aid of chains 13, 14 of a chain mechanism. To make it possible to refresh the stack 11 during continuous operation of the sheet-fed offset printing press, an auxiliary stack apparatus is provided. The auxiliary stack apparatus includes a holder 16 for a plurality of loadbearing elements 17 disposed in parallel, an advancing device 18, and a guide 19 for the loadbearing elements 17, and a front loadbearing rail 20. The holder 16 can be positioned in the vertical direction by chains 21 of a chain mechanism together with the guide 19 and the advancing device 18, and can be positioned in the horizontal direction perpendicularly with respect to the plane of the drawing of FIG. 1 by a non-illustrated positioning apparatus. The loadbearing rail 20 can be positioned in the vertical direction 15 by chains 22 of a chain mechanism. The pallet 10 has webs and grooves. The stack 11 lies on the webs of the pallet 10. The loadbearing elements 17 can be positioned through the grooves by the advancing device to such an extent that they rest on the loadbearing rail 20.

During printing, the stack 11 is guided against a suction head 23 having suction grippers 24, 25, using the chains 13, 14 in accordance with the printing velocity. Vacuum lines 26 lead to the suction grippers 24, 25. The suction head 23 can be moved to and fro in the horizontal direction 27. The sheets 28 that lie on top of the stack 11 are separated using the suction grippers 24, 25 and are conveyed onto a feed table 29 against front lays 30 by the movement of the suction head 23. The sheets 28 are transferred from the front lays 30 to the feed cylinder 8 by a swinging gripper 31. The sheet 28 is printed as it passes through the nip between the impression cylinder 7 and the transfer cylinder 6. The transport drum 9 transports the sheet 28 to further printing units.

In the height position shown in FIG. 1 of the stacking table 12, the instant for refreshing the stack 11 has been reached. To refresh the stack 11, the auxiliary stack 11 is picked up temporarily on the loadbearing elements 17 together with the remainder of the sheets 28. For such a purpose, the holder 16 with the loadbearing elements 17 is positioned in the vertical and horizontal direction such that the tips 32 of the loadbearing elements 17 point approximately toward the centers of the cross-sectional areas of the pallet grooves. Afterward, the advancing device 18 is set in operation with a motor 33 and a mechanism 34. As a result, the loadbearing elements 17 that are fastened to a crossmember 35 pass through the pallet grooves onto the loadbearing rail 20. The loadbearing elements 17 are of pivotably connected members 36 that follow the curved shape of the guide 19 outside the pallet grooves and a guide in the holder 16. After passing through the guide in the holder 16 and after lying on the loadbearing rail 20, the members of the loadbearing elements 17 are flexurally rigid for the load of the auxiliary stack 11. Furthermore, the auxiliary stack 11 is moved toward the suction grippers 24, 25 by vertical driving of the holder 16 and the loadbearing rail 20 through the chain mechanism on the chains 21, 22. Here, the weight of the auxiliary stack 11 is completely held on the loadbearing elements 17. While the auxiliary stack is moved toward the suction head 23 by the chains 21, 22, the stacking table 12 together with the pallet 10 is lowered on the chains 13, 14 through the chain mechanisms until it assumes a lower position for picking up a new main stack. The new main stack is moved under the loadbearing elements 17 of the auxiliary stack even before the auxiliary stack 11 has been processed. As a result, the main stack and the auxiliary stack 11 are aligned. Subsequently, the loadbearing elements 17 are drawn in in the direction of the guide 19 by the advancing device 18. As a result, the auxiliary stack 11 and the new main stack are combined to form a stack 11. The combined stack 11 is moved further toward the suction head 23 by the chain mechanism and the chains 13, 14.

If designations that have already been introduced are used in the following description, then they are, in each case, features having the equivalent function.

FIG. 2 shows the loadbearing elements 17 on the crossmember 35. The crossmember 35 has cutouts 37 in which the ends of the loadbearing elements 17 are fastened. The loadbearing elements 17 are inserted in elongate form into grooves 38 of the pallet 10, which is shown in greater detail in FIG. 3. Both the tips 32 of the loadbearing elements 17 and the grooves 38 have insertion bevels 39, 40.

FIGS. 4 and 5 show two views with details of how the crossmember 35 is disposed in the guide 19. The crossmember 35 is guided on a roller track 43 on both sides by rollers 41, 42. To move the crossmember 35 forward and backward in the guide 19, the crossmember 35 is coupled to chains 46, 47 through pins 44, 45. The chains 46, 47 slide in the guide 19 and are connected to the mechanism 34.

FIGS. 6 and 7 show an articulated connection of a loadbearing element 17 to the crossmember 35. Universal joints 48 are disposed in the cutouts 37 of the crossmember 35. The end of the loadbearing element 17 is mounted so as to pivot about the axis of a pin 49. The pin 49 is seated on one side of a connecting piece 50 that is in the shape of a double fork. A bolt 55 whose axis runs parallel to the axis of the pin 49 is provided on the other side of the connecting piece 50. A further pin 51 penetrates the bolt 55 in a direction that is perpendicular with respect to the axis of the pin 49. Furthermore, the pin 51 is held in a bolt 52 with fork-shaped ends. The cylindrical bolt 52 is rotatably mounted in a hole in the crossmember 35. A projection 53 of the bolt 52 and a securing ring 54 prevent the bolt 52 from being displaced in the axial direction. The loadbearing element 17 and the connecting piece 50 can be pivoted about the axis of the pin 51. The pivoting movement of the loadbearing element 17 about the axes of the pins 49, 51 and the rotation about the axis of the bolts 52, 55 are limited by the inner walls of the cutouts 37.

When the loadbearing elements 17 are inserted into the grooves 38 of the pallet 10 (see FIG. 3), excessively high constraining forces on the loadbearing elements 17 and the pallet 10 are avoided because, even in the event of slight constraining forces, the loadbearing elements 17 yield to the resistance. In other words, a movement of the loadbearing elements 17 takes place in the context of the degrees of freedom present as a result of the joints 48 and the wall of the cutouts 37.

FIG. 8 shows an embodiment in which some of the loadbearing elements 17 have an amount of play x in the crossmember 35 because the length of the bolt 52 has been somewhat enlarged in comparison with FIGS. 6 and 7. When the loadbearing elements 17 under the stack 11 are pulled out, loadbearing elements 17 having the amount of play x begin to be pulled out somewhat later than loadbearing elements 17 without play. As a result of a different amount of play x, every loadbearing element 17 can be pulled out at a different instant. The play x can be provided in equal amounts symmetrically with respect to the sheet center across the width of a sheet 28, in the case of pairs of loadbearing elements 17.

This application claims the priority, under 35 U.S.C. § 119, of German patent application No. 103 58 741.1, filed Dec. 4, 2003; the entire disclosure of the prior application is herewith incorporated by reference.

Claims

1. An apparatus for picking up an auxiliary stack when conveying sheets in a printing machine, comprising: a crossmember; and loadbearing elements being disposed at said crossmember for picking up the auxiliary stack, said loadbearing elements being fastened movably to said crossmember to pivot in at least two degrees of freedom.

2. The apparatus according to claim 1, further comprising: a chain mechanism; said crossmember having two sides and being coupled to said chain mechanism on both of said two sides; and said loadbearing elements being members pivotably connected to said crossmember.

3. The apparatus according to claim 1, wherein said crossmember is moved on a curved path.

4. The apparatus according to claim 1, further comprising a curved path and said crossmember moving on said curved path.

5. The apparatus according to claim 1, wherein: said crossmember has cutouts; and at least one joint is disposed in at least one of said cutouts between said crossmember and at least one of said loadbearing elements.

6. The apparatus according to claim 1, wherein: said crossmember has cutouts; and joints are disposed in said cutouts between said crossmember and each of said loadbearing elements.

7. The apparatus according to claim 5, wherein said at least one joint movably connects said at least one loadbearing element to said crossmember.

8. The apparatus according to claim 6, wherein said joints movably connect said loadbearing elements to said crossmember.

9. The apparatus according to claim 5, wherein said cutouts have walls forming stops for movement of said at least one loadbearing element.

10. The apparatus according to claim 6, wherein said cutouts have walls forming stops for movement of a respective one of said loadbearing elements.

11. The apparatus according to claim 7, wherein said at least one joint provides four degrees of freedom for said at least one loadbearing element.

12. The apparatus according to claim 8, wherein said joints provide four degrees of freedom for said loadbearing elements.

13. The apparatus according to claim 1, further comprising a universal joint disposed between said crossmember and at least one of said loadbearing elements.

14. The apparatus according to claim 1, further comprising universal joints disposed between said crossmember and said loadbearing elements.

15. The apparatus according to claim 1, wherein: the auxiliary stack to be picked up lies on a pallet; the pallet has grooves in which said loadbearing elements are to be disposed; and said loadbearing elements are disposed displaceably in said crossmember within given limits in a direction of movement out of the grooves.

16. The apparatus according to claim 15, wherein given pairs of said loadbearing elements have different regions of limit for the displacement.

17. The apparatus according to claim 15, wherein at least one pair of said loadbearing elements have different regions of limit for the displacement than other of said loadbearing elements.

18. An apparatus for picking up an auxiliary stack when conveying sheets in a printing machine, comprising: a crossmember moving on a curved path and having cutouts; loadbearing elements being disposed at said crossmember for picking up the auxiliary stack; and at least one joint: being disposed in at least one of said cutouts between said crossmember and at least one of said loadbearing elements; and movably connecting said at least one loadbearing element to said crossmember in at least two degrees of freedom.

19. The apparatus according to claim 18, wherein said at least one joint provides four degrees of freedom for said at least one loadbearing element.

20. The apparatus according to claim 18, further comprising a universal joint disposed between said crossmember and at least one of said loadbearing elements.

21. An apparatus for picking up an auxiliary stack when conveying sheets in a printing machine, comprising: a guide to be disposed adjacent a location for the auxiliary stack in the printing machine; a crossmember movably disposed at said guide; and loadbearing elements disposed at said crossmember for moving the auxiliary stack, said loadbearing elements being operatively connected to said crossmember to pivot in at least two degrees of freedom.

22. In a printing machine having an auxiliary stack holding sheets, an apparatus for picking up the auxiliary stack when conveying the sheets comprising: a crossmember; and loadbearing elements disposed at said crossmember for picking up the auxiliary stack, said loadbearing elements being fastened movably to said crossmember to pivot in at least two degrees of freedom.