DE20119467U1 - Cam track gear, especially for a sheet-fed printing machine - Google Patents

Description

Reference number: PDEMN09 (EM No. 101537)

Date: November 9, 2001

Applicant: MAN Roland Druckmaschinen AG, Mühlheimer Straße 341, 63075 Offenbach

Cam track gear, especially for a sheet-fed printing press

The invention relates to a cam track gear such as can be used, for example, in a pre-gripper or front lay control of a sheet-fed printing press.

In a sheet-fed printing press, to transfer a sheet to a printing cylinder, the sheet is usually sucked in by suction cups in the area of its front edge and inserted into so-called collecting hooks, where it is pre-aligned. The sheet is then finely aligned using front marks, which are cyclically swiveled into a stop position for each individual printing sheet and align the front edges of the sheet. Alignment of the sheet in the transverse direction is preferably also achieved in the lateral direction after it has been positioned by the front marks, by pulling the sheet towards the side marks or by pushing the side marks towards the sheet. The aligned sheet is gripped by a pre-gripper and transferred to the printing cylinder. In multi-color printing processes in particular, the quality of the printed image produced is largely determined by the precision of the printing sheet alignment achieved by the front marks and side marks. The pre-grippers intended for transferring the sheets to be printed onto the printing cylinder, as well as the front and side marks intended for aligning the fed sheets, are usually operated via a cam track gear that has a track element that rotates synchronously with the respective printing cylinder. Manufacturing or wear-related geometric errors in the components responsible for sheet transport and sheet alignment lead to so-called register deviations.

The invention is based on the object of creating a curved track transmission by means of which cyclically recurring movement sequences can be carried out with particularly high repeatability.

This object is achieved according to the invention by a cam track transmission with a track element which has at least one cam track and a cam track tapping element which is in contact with the cam track, wherein the cam track tapping element has a rolling surface which rolls on the cam track and the cam track and the cam track tapping element are designed such that the length of the cam track is a multiple of the length of the rolling surface of the cam track tapping element measured in the rolling direction.

This advantageously makes it possible to reduce the deviations between successive movement sequences caused by the interaction of the cam track and the cam track tapping element. In a particularly advantageous manner, it is possible to achieve each radial deflection of the cam track tapping element by means of a specific contact zone pairing of the contact surfaces formed by the cam track and the cam track tapping element that is repeated in the same way. This advantageously ensures that the shape tolerances of the cam track and the cam track tapping element have the same effect on the movement sequence of the cam track tapping element for each actuation cycle. This achieves a high and consistent registration accuracy over the entire printing run.

According to a particularly preferred embodiment of the invention, the length of the curved track is selected such that it is an integer multiple, e.g. 2, 3, 4... times the length of the rolling surface of the curved track tapping element measured in the rolling direction. This advantageously ensures that in immediately successive movement cycles initiated by the track element, the same contact zone pairings are decisive for the lifting movement.

The cam track tapping element is advantageously designed as a circular roller which rolls on the cam track tapping element essentially without slippage. In particular, when the cam track tapping element is designed as a circular roller, it is preferably rotatably mounted by a rolling bearing device. The rolling bearing device preferably comprises

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Needle, barrel or cylinder elements whose diameter is smaller than 1/10 of the diameter of the circular roller.

The cam track gear is advantageously part of a pre-gripper drive of a sheet-fed printing press. This makes it possible to achieve increased registration accuracy, since the sheet transfer carried out by the pre-gripper advantageously takes place with increased repeat accuracy.

The cam track gear according to the invention can also be used advantageously to actuate the front lays of a sheet-fed printing machine. If the front lays are actuated by the gear according to the invention, a high level of repeatability is achieved with regard to the sheet position determined by the front lays, which also proves to be advantageous with regard to the associated reduction in register deviation.

In particular in combination with the measures described above - or alternatively thereto - the object stated at the outset is also achieved by a cam track transmission with a track element which has at least one cam track and a cam track tapping element which is in contact with the cam track, wherein the cam track tapping element has a rolling surface which rolls on the cam track and a coupling device is provided for the positive rotational coupling of the cam track tapping element with the cam track.

This measure also reduces the permutation possibilities for the pairing of the contact points of the cam track and the cam track tapping element.

Advantageously, the coupling device comprises a tooth engagement structure, so that a rolling movement of the cam track tapping element on the cam track is forcibly brought about by tooth engagement.

The tooth engagement structure is preferably formed by a gear wheel coupled to the cam track tapping element, the pitch circle of which essentially corresponds to the diameter of the cam track tapping element. This gear wheel is preferably in engagement with a toothed section that extends along the cam track.

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The tooth engagement structure can be arranged in the side region of the cam track or the cam tapping element, or advantageously also be formed, for example, as a narrow toothing strip in the cam track.

At least part of the tooth engagement structure is preferably made of a plastic material, for example polyamide, which ensures that the cam track transmission runs particularly smoothly. It is also possible to form a tooth engagement structure between the cam track and the cam track tapping element, which only causes a rotational coupling of the cam track tapping element to the cam track itself in conjunction with a further coupling element, preferably a toothed belt with teeth on both sides.

It is possible to design the coupling device in such a way that a rotary coupling is achieved only along selected track zones by positive engagement of corresponding coupling structures - for example tooth engagement structures. These coupling structures can then be restricted to zones with a largely constant or low curved path curvature. It is thus possible to provide tooth engagement structures only in association with curved path sections in which the curved path follows a circular path. In the remaining zones of the curved path, toothing can then be dispensed with. With sufficient frictional rotary coupling of the curved path tapping element with the track element, the coupling device can be restricted to a small circumferential section, so that only in this circumferential section do the curved path tapping element and the track element experience fine alignment in this zone.

It is also possible to design the coupling device in such a way that, in association with selected zones of the curved path, a coupling play, in particular a toothing play, is permitted which is greater than the coupling or toothing play in association with curved path zones with a uniform path course.

Further details of the invention emerge from the following description in conjunction with the drawing. In the drawing:

Figure 1 is a schematic diagram to explain an application of the

inventive cam track transmission in a pre-gripper control;

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Figure 2 is a schematic view to explain an application example of the

inventive cam track gear in a front-brand drive;

Figure 3 is a sketch to explain a coupling device for the realization of a

positive rotary coupling of a cam track tapping element with the cam track assigned to it.

Figure 1 shows a printing cylinder 1 with a pre-gripper 2 assigned to it in the form of a highly simplified schematic representation. The pre-gripper 2 serves to transfer a sheet 5, which is brought onto a feed table 3 and aligned by front marks 4, to the printing cylinder 1. The pre-gripper 2 is actuated via a cam track gear 6, which is only shown in outline here.

The cam track gear 6 comprises a track element 7 which defines a cam track 8 on its outer circumference, the radial distance of which from a center of rotation Z varies. A cam track tapping element 9, which is designed here as a circular roller, runs on the cam track 8. The circular roller is arranged to be movable via a lever device 10 such that the circular roller is moved away from the center of rotation Z or can swing back to it in accordance with the radial stroke prevailing at the contact point between the circular roller and the cam track 8. Depending on the lifting or swiveling movement of the circular roller caused by the cam track 8, the pre-gripper 2 can be swiveled from the sheet receiving position shown here into a sheet feeding position, in which the sheet 5 initially still gripped by the pre-gripper 2 can be inserted into the catch hooks 11 provided on the printing cylinder side and fixed to the printing cylinder 1. The lever device 10 is shown here directly coupled to the pre-gripper 2 merely to illustrate a possible operative connection.

The track element 7 and the cam track tapping element 9 which interacts with it and is designed here as a circular roller, are designed such that the circumferential length of the cam track 8 measured in the circumferential direction corresponds to an integer multiple of the circumferential length of the cam track tapping element 9.

The required coordination of the curved path tapping element 9 and the path element 7 is advantageously achieved by first determining the required stroke of the curved path tapping element 9 and then adjusting the course of the curved path 8 to the required stroke. The circumferential length of the curved path 8 is then calculated and, on the basis of the calculated curved path 8, a suitable circumferential length for the curved path tapping element 9 is determined. If the curved path tapping element 9 is designed as a circular roller, its diameter can be calculated from the determined circumferential length. If the geometry of the curved path tapping element 9 influences the stroke caused in interaction with the curved path 8, the coordination of the geometry of the curved path 8 and the curved path tapping element 9 can be iteratively optimized on the basis of the dimensioning concept described above.

The coordination described above ensures that the lifting movement imposed on the cam track tapping element 9 is caused by clearly associated circumferential points of the cam track tapping element 9 and the cam track 8. In order to prevent the associated surface points of the cam track tapping element 9 and the cam track 8 from drifting, it is possible, as will be explained below in connection with Figure 3, to provide a coupling device by which, as an alternative or in addition to a frictional coupling of the cam track tapping element 9 with the cam track 8, a forced coupling of the two elements is achieved. The cam track gear 6 shown here in sketch form for actuating the pre-gripper 2 can also be used to control the gripping elements 12 of the pre-gripper 2 in a correspondingly modified form and with the inclusion of suitable coupling mechanisms. It is also possible, using a cam track gear dimensioned according to the invention, to actuate further printing press elements, e.g. front lays 4, provided for transporting or transferring the printed sheet 5, as will be described below with reference to Fig. 2.

In Figure 2, a front lay device 14 is shown, by which the printed sheet fed via a feed table 3 (Figure 1) is aligned in order to achieve a perfect register. The printed sheet 5 fed to the front lays 4 is aligned at the mark stops 15 in such a way that the front edge 5a of the printed sheet is aligned parallel to a gripper edge. The control of the front lay device 14 takes place via a cam track gear 6 which, as already described in connection with Figure 1, is a

Track element 7 and a curved track tapping element 9 which is moved radially in accordance with a curved track 8 defined by the track element 7 and which is also designed as a circular roller here.

The geometry of the curved track 8 and the diameter of the circular roller are determined such that the circumferential length of the curved track 8 is an integer multiple of the circumferential length of the circular roller.

This special definition of the geometry of the cam track 8 and the cam track tapping element 9 ensures that the end position of the mark stop 15, which is significant with regard to the alignment of the front edge 5a of the printed sheet 5, is defined by continuously identical contact zone pairings of the cam track tapping element 9 and the cam track 8. This also advantageously ensures that any wear-related increases in tolerance always have the same effect on the end position of the mark stop 15 determined by the cam track gear 6 and do not lead to fluctuating stop positions of the mark stops in an unforeseeable variety of permutations.

The track element 7 is preferably designed such that any track zones with a negative track curvature (zones with a curvature center lying outside the curved track 8) have a radius of curvature that is larger than the radius of curvature of the curved track tapping element. The curved track tapping element 9 and the curved track 8 are preferably further designed such that the contact between the curved track tapping element 9 and the curved track 8 takes place in the form of a line contact. In this exemplary embodiment, the curved track tapping element 9 is also preferably positively coupled to the curved track 8.

Figure 3 shows an example of a coupling device 16, via which a positive rotational coupling of the curved path tapping element 9 with the path element 7 is achieved.

In this embodiment, the coupling device 16 comprises a front engagement element 17 which is coupled to the track element 7 in a rotationally fixed manner. This front engagement element 17 is in engagement with a spur gear element 18 which is coupled to the curved track pick-up element 9 in a rotationally fixed manner. The two elements 17, 18 are designed in such a way

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designed so that their rolling area runs on the radial level of a contact zone 19, via which the cam track tapping element 9 is in contact with the track element 7. The elements 17, 18 are arranged here laterally next to the cam track tapping element 9 and the track element 7. It is also possible to arrange the coupling device formed by tooth engagement structures in such a way that it divides the contact zone 19.

The number of teeth of the spur engagement element 17 is preferably an integer multiple of the number of teeth of the spur gear element 18. The said ratio of the number of teeth also corresponds to the circumferential length ratio of the circumferential length of the curved path 8 defined by the track element 7 compared to the circumferential length of the curved path tapping element 9. In zones of strongly changing curvature of the curved path defined by the track element 7, it is possible to design the toothing structure in such a way that larger tooth flank clearances result at these points than in zones with a smaller change in the curvature of the path.

It is possible to design the coupling device in such a way that a rotary coupling is achieved only along selected track zones by positive engagement of corresponding coupling structures - for example tooth engagement structures. These coupling structures can then be restricted to zones with a largely constant or low curved path curvature. It is thus possible to provide tooth engagement structures only in association with curved path sections in which the curved path 8 follows a circular path. In the remaining zones of the curved path, toothing can then be dispensed with. With sufficient frictional rotary coupling of the curved path tapping element 9 with the track element 7, the coupling device 16 can be restricted to a small circumferential section, so that the curved path tapping element 9 and the track element 7 only experience fine alignment in this circumferential section in this zone.

It is also possible to design the coupling device in such a way that, in association with selected zones of the curved path 8, a coupling play, in particular a toothing play, is permitted which is greater than the coupling or toothing play in association with curved path zones with a uniform path course.

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LIST OF REFERENCE SYMBOLS

1 pressure cylinder

2 pre-grippers

3 Plant table

4 front stamps

5 sheets

5a Bow leading edge

6 cam track gear

7 Track element

8 Curved track

9 Curved track tapping element

10 Lever device 12 Gripping element

14 Front mark device

15 branding

16 Coupling device

17 Stem engagement element

18 Spur gear element

19 Contact zone Z turning center

Claims (12)

1. A cam track transmission with a track element ( 7 ) which has at least one cam track ( 8 ) and a cam track tapping element ( 9 ) which is in contact with the cam track ( 8 ), wherein the cam track tapping element ( 9 ) has a rolling surface which rolls on the cam track ( 8 ) and the cam track ( 8 ) and the cam track tapping element ( 9 ) are designed such that the length of the cam track ( 8 ) is a multiple of the length of the rolling surface of the cam track tapping element ( 9 ) measured in the rolling direction. 2. Cam track transmission according to claim 1, characterized in that the length of the cam track ( 8 ) is an integer multiple of the length of the rolling surface of the cam track tapping element measured in the rolling direction. 3. Cam track transmission according to claim 1 or 2, characterized in that the cam track tapping element ( 9 ) is designed as a circular roller. 4. Cam track transmission according to at least one of claims 1 to 3, characterized in that the cam track tapping element ( 9 ) is mounted by a rolling bearing device. 5. Cam track transmission according to at least one of claims 1 to 4, characterized in that it is a component of a pre-gripper drive. 6. Cam track transmission according to at least one of claims 1 to 4, characterized in that it is a component of a front-line drive. 7. Cam track transmission with a track element ( 7 ) which has at least one cam track ( 8 ) and a cam track tapping element ( 9 ) which is in contact with the cam track ( 8 ), wherein the cam track tapping element ( 9 ) has a rolling surface which rolls on the cam track ( 8 ) and a coupling device ( 16 ) is provided for the positive rotational coupling of the cam track tapping element ( 9 ) with the cam track ( 8 ). 8. Cam track transmission according to claim 7, characterized in that the coupling device ( 16 ) has a tooth engagement structure. 9. Curved track transmission according to claim 7 or 8, characterized in that the coupling device ( 16 ) is designed such that a rotary coupling by positive engagement takes place only along selected, in particular imprecision- or less precision-relevant track zones. 10. Cam track transmission according to claim 9, characterized in that the coupling structures are provided in association with zones with a largely constant or low cam track curvature. 11. Curved track transmission according to at least one of claims 7 to 10, characterized in that the coupling device ( 16 ) is designed to be limited to a small circumferential section, so that only in this circumferential section the curved track tapping element ( 9 ) and the track element ( 7 ) area experience a fine alignment. 12. Curved track transmission according to at least one of claims 7 to 10, characterized in that the coupling device ( 16 ) is designed such that, in association with selected zones of the curved track ( 8 ), a coupling, in particular toothing, play is permitted which is greater than the coupling or toothing play in association with curved track zones with a uniform path.