GB2071274A

GB2071274A - Damped drive coupling in a rotary printing machine

Info

Publication number: GB2071274A
Application number: GB8106036A
Authority: GB
Original assignee: Polygraph Leipzig Kombinat Veb
Current assignee: Polygraph Leipzig Kombinat Veb
Priority date: 1980-02-29
Filing date: 1981-02-26
Publication date: 1981-09-16
Also published as: DD154940A3; IT1195802B; FR2477068A1; SE449649B; FR2477068B1; SE8101299L; IT8167254A0; CS235931B1; DE3041015C2; JPS56124759A; JPH034786B2; GB2071274B; DE3041015A1; SU1142673A1

Abstract

A rotary printing machine comprises a pulley (15, 16, 17) for transmission of driving torque provided by a drive motor via belt means to a main drive shaft (6) of the machine. In order to damp power transmission oscillations, the pulley is mounted on the shaft (6) to be resiliently displaceable relative thereto in the circumferential direction of the shaft against the action of circumferentially extending tension springs. <IMAGE>

Description

SPECIFICATION Damped drive coupling in a rotary printing machine The present invention relates to a rotary printing machine, and has particular reference to a damped drive coupling in such a machine, preferably a multicolour rotary printing machine.

Rotary printing machine drives are known, in which transmission of driving torque from a drive motor to a main drive shaft takes place through circulating traction means, preferably a number of V-belts. In German (Fed. Rep.) patent specification No. WEB41 F/213 020 there is described a drive in which the ratio of the rotation of V-belts to the rotation of an impression cylinder functioning as a single revolution shaft is almost a whole number.

As a result, the phase position of any oscillations, caused by the belts, in the driving torque remains constant relative to the single revolution shaft.

It is disadvantageous in this case that the oscillations emanating from the belts are not suppressed, but merely become quasi-stationary oscillations with respect to the single revolution shaft. The oscillations emanating from the belts and from the drive motor are still transmitted to the rotary printing machine, which can lead to excessive ladings and thereby to wear and particularly to dynamic disturbances in the sheet transfer.

A rotary printing machine drive is also disclosed in DE-PS 2516462, in which low frequency oscillations, produced by the drive motor, in the driving torque are compensated for by the oscillations of a balancing mass. These oscillations, caused by the generation of a unidirectional voltage from an alternating voltage, have a frequency of 50 Hertz as fundamental and are superimposed by whole-numbered harmonics.

In the case of a compensating mass coupled through a spring rod to the drive so that the natural frequency of the system of spring rod and compensating mass is equal to the frequency to be suppressed, cancellation of the oscillation can be achieved. It is in that case a condition that the damping is a minimum (equal to zero in the ideal case). The compensating effect rises with an increase of the mass inertia moment of the compensating mass. It is, however, disadvantageous that only one frequency can be cancelied. Oscillations which result from the circulation of the traction means and are thus of substantially lower frequency cannot be suppressed, because constructional limits are imposed (inertia moment).

The described drives are not able to prevent, or can only prevent in a very restricted frequency range, tooth flank change or the raising of the tooth flanks. Due to this, registration errors and doubling phenomena may appear in the printed output of the rotary printing machine.

There is therefore a need for a printing machine main drive coupling by means of which transmission of any oscillations, caused by drive belt means and/or the drive motor, in the driving torque can be suppressed within a large frequency range and without being transmitted to the main drive shaft of the machine.

According to the present invention there is provided a rotary printing machine comprising a main drive shaft provided with a pulley, and a drive motor drivingly coupled to the pulley by belt means, the pulley being mounted on the shaft to be resiliently displaceable relative thereto in the circumferential direction of the shaft.

The pulley, arranged on the main drive shaft of the machine, is thus associated resiliently in circumferential direction with the main drive shaft.

Preferably, the pulley is coupled by tension springs with a connecting hub on the shaft. Rotatably arranged on the hub may be at least one spring ring coupled to the pulley and hub by tangentially arranged tension springs, which engage pin means of the ring and of the pulley and hub. In the case of several such rings, the rings are intercoupled through tangentially arranged tension springs engaging similar pin means.

The pulley preferably comprises a sleeve connected by screws or the like with an abutment ring rotatably mounted on the hub. The hub itself is preferably firmly connected with the main drive shaft and coupled by abutment pins with the abutment ring. The pins may be guided in the abutment ring in circularly arcuate elongate holes, the common centre of curvature of which lies in the rotational axis of the abutment ring and thus of the shaft.

A rotary printing machine embodying the present invention may have the advantage that transmission of oscillations produced by the belt means and/or the drive motor to the printing mechanisms of the machine are prevented by the low pass filter effect of the pulley. As a result, the raising of drive tooth flanks or changing of tooth flanks brought about by these oscillations can be avoided. The printing result may be substantially improved, i.e. registration errors can be reduced and doubling phenomena avoided. Moreover, the loading of drive gear may be reduced and an almost constant torque transmitted.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a schematic elevation of a rotary printing machine according to the said embodiment; Fig. 2 is a sectional elevation of part of a belt pulley of the main drive shaft of the machine of Fig. 1; Fig. 3 is an end view of half of the pulley in the direction of arrow X of Fig. 3; Fig. 4 is detail showing a tension spring mounting in the coupling of the pulley to the drive shaft; Fig. 5 is a diagram of the arrangement of the tension springs in such coupling in front elevation of the pulley, and Fig. 6 is a diagram of the arrangement of the tension springs in such coupling in side elevation of the pulley.

Referring now to the drawings, there is shown a rotary sheet printing machine comprising a plurality of printing units 1, a feeder 2 and a deposit 3. Drive of the printing units is effected by a drive motor 4 via several belts 5 and a belt pulley 7 arranged on a main drive shaft 6. The driving torque of the individual printing units 1 is transmitted from the main drive shaft 6 through several gear stages 8 to impression cylinders 9.

The printing units 1 are connected through drive wheels 1 forming a closed gear train, driving the impression cylinders 9 and transfer drums 10.

Fig. 2 shows the belt pulley 7 in detail. A hub 13 is fastened secure against rotation by a fitted key 12 on the main drive shaft 6. An annular axial end member 15 is rotatably mounted on the hub 13 through a roller bearing 14. A pulley element in the form of a sleeve 1 6 is secured by screws at one end face thereof to the member 1 5 and at its opposite end face to another annular axial end member 17, which is rotatably mounted on the hub 13 by a roller bearing 18. The member 17 is coupled through abutment pins 19 with the hub 13, the pins 19 being mounted in the member 17 in rubber-sprung bushes 20. Fig. 3 shows the arrangement of the pins 19.As will be apparent, radial movement of the pins 19 in the member 17 is limited by circularly arcuate elongate holes 30 in which the pins are engaged, the common centre of curvature of the holes lying on the rotational axis of the member 17. A first spring unit 21, consisting of a ring 23 and pins 24, is mounted by two roller bearings 25 on the hub 13 in the interior of the sleeve 16. A further such spring unit 22 is mounted on the hub 13 alongside the unit 21, and additional spring units may be provided depending on requirements.

As is evident from Fig. 4, the pins 24 are provided with annular grooves which receive hooked or looped ends of the springs 26. As shown in Fig. 5, the pins 24 extend parallel to the axis of the ring 23. Similar pins 27 and 28 are arranged on the member 1 5 and the hub 13, respectively, the pins 27 and 28 also having annular grooves receiving the ends of springs 26.

As can be appreciated from Figs. 5 and 6, the springs 26 extend tangentially to a notional circle concentric with the shaft axis and are arranged between the pins 28 of the member 1 5 and the pins 24 of the first spring unit 21, between the pins 24 of the first and second spring units 21 and 22, and between the pins 24 of the second spring unit 22 and the pins 27 of the member 17. In case of only one spring unit 21, the pins 24 of that unit are connected through tension springs 26 directly with the pins 27.

An end washer 29 secures the pulley 7 axially on the shaft 6.

In operation of the printing machine, a driving torque is transmitted through the motor 4 and belts 5 to the sleeve 16 and thereby to the members 1 5 and 17. The member 15 transmits the driving torque through the pins 27 and springs 26 to the first spring unit 21, from the unit 21 through springs 26 to the second spring unit 22, and from the unit 22 through springs 26 to the hub 13, the member 1 5, spring units 21 and 22 and hub 13 being resiliently coupled together by the springs 26 in the manner already explained.

The hub 13 transmits the driving torque through the key 12 to the shaft 6. When oscillations, produced by the belts 5 and/or by the motor 4, in the driving torque occur, these are absorbed by the tension springs 26 and kept by a low pass tuning for the rotary printing machine away from the nominal range thereof.

The guidance of the abutment pins 1 9 in the arcuate holes 30 serves to limit spring travel on switching on and off of the drive and to prevent overloading.

Claims

1. A rotary printing machine comprising a main drive shaft provided with a pulley, and a drive motor drivingly coupled to the pulley by belt means, the pulley being mounted on the shaft to be resiliently displaceable relative thereto in the circumferential direction of the shaft.

2. A machine as claimed in claim 1, wherein the shaft is provided with a support hub rotatable therewith and supporting the pulley, the pulley being coupled to the hub in the circumferential direction of the shaft by tension springs.

3. A machine as claimed in claim 2, wherein the hub is keyed to the shaft.

4. A machine as claimed in either claim 2 or claim 3, comprising annular coupling means rotatably mounted on the hub and provided with pin means connected by the tension springs with pin means of the pulley and pin means of the hub.

5. A machine as claimed in claim 4, the annular coupling means comprising a plurality of annular members each connected in the circumferential direction of the shaft to the or each adjacent annular member by a tension spring.

6. A machine as claimed in claim 4 or claim 5, wherein the tension springs each extend substantially tangentially to a notional circle concentric with the shaft.

7. A machine as claimed in any one of claims 2 to 6, wherein the pulley comprises an outer sleeve member engaged by the belt means and at least one annular support member secured to the outer annular member and rotatably mounted on the hub.

8. A machine as claimed in claim 5, comprising two such support members arranged one at each axial end of the sleeve member.

9. A machine as claimed in either claim 7 or claim 8, wherein the hub is connected to said one support member by at least one abutment pin limiting said displacement of the pulley relative to the shaft.

10. A machine as claimed in claim 9, wherein the or each abutment pin is engaged in a respective arcuate slot in said one support member, the centre of curvature of the or each slot lying on the axis of the shaft.

11. A rotary printing machine substantially as hereinbefore described with reference to the accompanying drawings.