GB2282134A

GB2282134A - Registering sheets prior to printing

Info

Publication number: GB2282134A
Application number: GB9419377A
Authority: GB
Inventors: Alexander Pfisterer
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1993-09-27
Filing date: 1994-09-26
Publication date: 1995-03-29
Also published as: GB9419377D0; DE4332852A1

Description

1 2282134 SHEET FEEDING TABLE WITH FRONT LAYS FOR ALIGNING THE LEADING

EDGE OF A SHEET The invention relates to a sheet feeding table with front lays for aligning the leading sheet edge, especially in a rotary printing machine, in which the front lays are spaced in a row on the feeding table, over the entire width thereof and transversely to the sheet-conveying direction, preferably opposite a cylinder taking over the aligned sheets. The front lays may be individually adjustable by means of electric motors.

A device for aligning a sheet is disclosed in the publication DE 16 11 367 in which a closed path of the front marks is produced by superimposition of the pivoting movements imparted by levers. The levers are mounted independently of each other on axes extending almost parallel with respect to the sheet plane, and the pivoting movement of each lever is limited by means of a respective stop, with the front marks being in sheet-aligning position. Disadvantageous with this device is the fact that it requires a great number of apparatuses.

Further prior-art solutions are shown in the publications DE 27 43 557 C2 and DE 38 27 944 Al. The first publication relates to a device adjusting a front lay on a sheet-processing machine, with said front lay being fixed on a control shaft running transversely to the sheet-conveying direction. The second publication relates to a guiding device for adjusting the position in a sheet-fed printing machine. Front guiding elements against which the arriving sheets abut are moved up and down and are pivot-mounted on a shaft.

Both prior-art solutions have the disadvantage that the cyclic pivoting of the front lays implies a reversal caused by the kinematics of the pivoting movements. The cyclic pivoting process always involves a pivoting-backmovement which cannot be utilized and is time- consuming.

2 The application DE 40 04 461 Al discloses a device for aligning the leading sheet edges. Front lays arbitrarily selected may be fixed in an aligning position, and the remaining front lays may be pivoted both in an impact position before the aligning position and in a supporting position behind the aligning position. In this case, too, a time-consuming pivoting movement is effected in sheettravel direction.

Finally, a rotary sheet-fed printing machine is known from the German Patent DE 41 07 080 C1 in which a register rail permitting an individual front-lay adjustment by means of motors. In the visual range of the front lays control units and displays for the positions of the front lays are disposed on both sides of the machine. A separate servo- motor is assigned to each front lay adjustable in sheettravel direction; nothing is said about the cyclic movement of the front lays as a result of which said front lays, after having been aligned, disappear in the sheet-conveying plane.

Proceeding from the above-mentioned state of the art it is the object of the invention to provide front lays which can be controlled independently of the kinematics of a rotary printing machine.

According to the invention, this object is achieved in that the feeding table features rotatable front lays in the area of the table edge, the rotary axes of said front lays extending parallel to the conveying direction of sheets fed on the feeding table.

This solution has the advantage that it prevents the front lays from pivoting into and out of contact with the table edge, thus saving time and not limiting the speed of a rotary printing machine. According to the invention the front lays are moved without reversal. As the pivoting movement of the front lay does not bring about an idle stroke towards the table edge, the front-lay motion is much more time- saving. Inertia forces which, for example, are active when retarding or accelerat-ing a front lay pivotmounted on a shaft in sheet-conveying direction and which i 3 have a negative influence on the sheet alignment do not occur. The direction of rotation of the front lays provided on the rotary axes can be chosen so as to extend in the same direction as does the side lay on the feeding table, thus 5 supporting the lateral alignment.

In one embodiment of the invention, the rotary axes of the front lays are provided by bevel-gear shafts driven by another transversely extending bevel-gear shaft. Said transverse bevel-gear shaft is driven independently of the machine speed by means of a drive motor provided on the feeding table, whereby a cyclic axial movement can be superimposed on the front lays.

Depending on the sheet size to be processed, individual front lays may be disengaged from the table edge.

For this purpose, front-lay flanges are provided so as to be axially displaceable and are guided in bushings fixed against rotation. A plurality of front lays may be mounted on the circumference of the frontlay flanges. Furthermore, there is preferably axial play between the individual front lays and each bushing.

Disengagement of the front lays from the table edge may be done manually by means of engaging pins assigned to the individual front lays and embedded in the surface of the feeding table. Alternatively, a remotecontrolled disengagement of individual front lays, not needed with a respective sheet size, may be achieved by means of pneumatic or electromagnetic means.

Several embodiments of the invention are now described by way of example with reference to the accompanying drawings, in which:- FIGURE 1 is a side elevational view of the area of a feeder provided upstream of a printing unit; FIGURE 2 is a schematic plan view of the f eeding table including a drive scheme; FIGURE 3 shows a rotatable front lay engaged at the edge of the feeding table; FIGURE 4 shows a rotatable front lay disengaged from the edge of the feeding table; and 4 FIGURES 5 and 6 show an alternative drive configuration for the direct drive of individual front lays.

Figure 1 shows the area of the feeder provided upstream of a rotary printing machine.

As can be seen from Figure 1, a f eeder 1 has a suction head 2 and suckers 3 above a sheet pile 4. The sheets separated from the sheet pile 4 arrive on a feeding table 5, in a front-lay area 6 of which said sheets are aligned. After having been aligned, the sheets are transferred onto a transfer cylinder 8 of a printing unit 7. Each sheet is then transferred from transfer cylinder 8 onto an impression cylinder 9 and printed on a printing-unit cylinder 10 cooperating with a further printing-unit cylinder 11.

Referring now to Figure 2, on the feeding table 5 there is provided a drive motor 12 driving a bevel-gear shaft 13, equipped with a plurality of spaced bevel gears 14. Each gear 14 drives a front-lay shaft 15 extending parallel to the sheet-conveying direction indicated by an arrow, through a further bevel-gear. This makes rotatable front lays 16 provided on the edge 17 of the feeding table rotate. The preferred direction of rotation of the front lays 16 is the same in which the lateral alignment is effected. As the drive motor 2 is controlled independently of the machine speed, a reversal of the direction of rotation of the individual front lays 16 is easily possible when, for any reason, it is desired to switch the side alignment from the operating side to the drive side, for example.

As can be seen f rom Figure 3, both the bevel-gear shaft 13 extending transversely to the sheet-conveying direction and the front-lay shaft 15 are mounted below the surface 18 of the feeding table 5. Each of said shafts is equipped with bevel gears 14. In addition thereto, an adjusting cone 19 embedded in the table surface 18 is provided on the front-lay shaft 15 below a disengaging pin 20. A thrust bearing 21 absorbing the thrust loads acting on the front-lay shaft 1-5 is mounted between the adjusting cone 19 and a front-lay flange 27, which is axially k 1 displaceable and comprises a compression spring 22 which, at one end thereof, is supported on the bottom of a cup-shaped recess formed in said front-lay flange 27 and, at the other end thereof, is in contact with a bushing 26 which is fixed against rotation on the front-lay shaft 15. The bushing 26 features two safety mechanisms 24 which ensure that the rotary motion of the front-lay shaft 15 is communicated, via the bushing 26, to the front lays 16 provided on the frontlay f lange 27. On the circumference of the front-lay flange 27 a plurality of individual shoulders forming the front lays 16 is provided. Each of the f ront lays 16 extends into the surface 18 of the feeding table and when engaged at the edge of said feeding table, is accommodated by a depression on the circumference of the front-lay flange 27, making it possible for the sheets 7 to pass. Lowering of the front lays 16 in a circumferential direction corresponding to that of the front- lay shaft 15, without reversal, which takes place after the sheets have been aligned at the engaged front-lays 16, ensures considerably shorter front-lay changing cycles which otherwise could not be achieved at all or only with great efforts through a toand-fro pivoting movement.

Referring now to Figure 4, one of the disengaging pins 20 is turned for the purpose of disengaging an individual front lay 16 not needed for the alignment of certain sheet sizes. The tapered end of the disengaging pin 20 contacts the adjusting cone 19 and displaces the front-lay flange 27 in axial direction when the disengaging pin 20 is moved further into the table surface 18. Due to this movement being imparted by the compression spring 22 against the spring pre-load, an axial play 23, shown in Figure 3 as an annular or rotary gap between front-lay flange 27 and bushing 26 in the area of the safety mechanisms 24, is f ormed at the table edge 17. As shown in Figure 4, this axial play 23 is now active between the rotatable front lays 16 and the table edge 17. In the area of the bushing 26, the front-lay shaft 15 features a multi-edge profile 28 permitting a positive connection to the bushing 26. By 6 means of a spacer 25 and a retaining nut 30 provided on a thread lug 29, said bushing 26 is fastened to the front-Jay shaft 15.

Thus, the front-lays 16 disengaged from the edge 17 of the feeding table are now inactive with respect to the sheet alignment. By turning the disengaging pin 20 to move it outwards towards the table surface 18, the rotatable front lays 16 are again engaged at the table edge 17 due to the expanding compression spring 22.

Instead of using a disengaging pin 20 assigned to a respective front-lay 16, it is also conceivable to effect the engaging/disengaging movement pneumatically or electromagnetically. In so doing, the disengaging pin 20 could be dispensed with, and after having modified the adjusting cone 19, a pressure chamber could be provided between said adjusting cone and the wall of the feeding table 5. In this case, the adjusting cone 19 acts as a pneumatic piston due to which the front-lay 16 is disengaged from the feeding table 5, when supplying the pressure chamber with pressure. For this purpose, appropriate cylinders would have to be embedded in the feeding table 5.

Referring now to the embodiment of Figure 5, each of the front-lay shafts 15 holding the front-lays 16 on the edge 7 of the feeding table 5 can be driven via a separate drive motor 12. According to this embodiment, the bevel drives 3, 14 can be dispensed with.

Figure 6 shows the arrangement of the drive motors 12 below the surf ace 18 of the feeding table 5, each of the drive motors being directly connected to the respective front-lay shaft 15 and being individually controllable.

It will of course be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

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Claims

CLAIMS:

1. A feeding table for use with a rotary printing machine and provided with front lays for aligning the leading edge of sheets and which are spaced in a row on the feeding table, over the entire width thereof and transversely to the sheet-conveying direction, wherein the front lays are rotatably mounted about axes which extend parallel to the conveying direction of the sheets to be conveyed on the feeding table, the front lays being provided on said feeding table in the area of an edge of the table.

2. A f eeding table according to claim 1, wherein each front lay is mounted on a bevel-gear shaft which is driven by a bevel-gear shaft extending transversely below the feeding table.

3. A feeding table according to claim 2, wherein, independently of the machine speed, the bevel-gear shaft is driven by a drive motor provided on the feeding table.

4. A feeding table according to claim 1, wherein each of the front lays is driven separately by means of a drive motor.

5. A f eeding table according to any one of the preceding claims, wherein a cyclic axial movement is superimposed on the front lays.

6. A feeding table according to any one of the preceding claims, wherein, depending on the respective sheet size to be processed, individual front lays can be disengaged from the edge of the feeding table.

7. A feeding table according to any one of the preceding claims, wherein each front lay is provided with a front-lay flange which is axially displaceable along the front lay axis and is guided in a bushing fixed against rotation.

8 8. A feeding table according to claim 7, wherein a plurality of front lays is distributed on the circumference of the front-lay flanges.

9. A feeding table according to claim 7 or 8, wherein there is axial play between each front lay and its bushing.

10. A feeding table according to claim 7, 8 or 9, wherein compression springs are disposed between each axially displaceable front- lay flange and its bushing.

11. A feeding table according to any one of the preceding claims. wherein an adjusting cone is provided for each front lay.

12. A feeding table according to claim 11, wherein a disengaging pin is assigned to a respective front lay and acts on the adjusting cone, each engaging pin being embedded in a surface of the table.

13. A feeding table according to any one of claims 1-11, wherein the front lays can be disengaged pneumatically.

14. A feeding table according to any one of claims 1-11, wherein the front lays can be disengaged electromagnetically.

15. A feeding table, substantially as hereinbefore described with reference to Figures 1-4 or Figures 1, 5 and 6 of the accompanying drawings.

16. Means for aligning the leading edge of a sheet in a rotary printing machine, substantially as hereinbefore described with reference to the accompanying drawings.

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