GB2098181A

GB2098181A - Correcting web feed to packaging machine

Info

Publication number: GB2098181A
Application number: GB8212209A
Authority: GB
Original assignee: Nagema VEB
Current assignee: Nagema VEB
Priority date: 1981-05-12
Filing date: 1982-04-27
Publication date: 1982-11-17
Also published as: JPS5831850A; DD158535A1; CH656853A5; GB2098181B; DE3215444A1; IT1147961B; IT8248367A0

Abstract

Corrections in the web feed to a packaging machine is effected by a photoelectric scanner (18) monitoring impressed marks (M) on the web and varying the input voltage to electric motor (14) forming part of a variable gearing drive to the web-feeding rollers (1,2). The variable gearing also includes a single revolution shaft (6), an initiator disc (15a) starting a pulse counter in the motor regulator (17) and a pulse generator (16a) feeding pulses to the regulator (17). The scanner (18) stops the counting of the pulses when an impressed mark (M) is detected and a correction voltage dependant upon the position of the mark (M) in relation to the start pulse from initiator disc (15a) is applied to the motor (14) to vary its rotational speed. <IMAGE>

Description

SPECIFICATION Device for the correcting regulation of a strip of packaging material provided with impressed marks The invention relates to a device for the correcting regulation of a strip of packaging material provided with impressed marks, using a setting member to influence the drawn-off length in both directions and an opto-electric scanning head for scanning the impressed marks in comparison with a position of the single-revolution shaft of the packaging machine, consisting of a compensating gearing allocated to the basic drive of the feed means and acting with a setting movement additionally upon the conveying means.

Such an initially mentioned device is already known on a high-speed packaging machine. This packaging machine has a compensating gearing known per se, actuated by the single-revolution shaft, for the drive of the conveyor rolls. To generate a differential movement which is added to the basic movement of the conveyor rolls for the correction of the deviation, a drive which generates a movement which is positive or negative according to the deviation is in time connection with the compensating gearing. A correction can be introduced through a worm gearing which is connected with the compensating gearing, in a manner in which this correcting movement is introduced to the drive shaft of the conveyor rolls through two electomagnetic couplings arranged on alternate sides (GDR-PS 51,565).

This device is no longer satisfactorily usable for modern high-speed machines, since the number of necessary correction actions in these machines is too high. Therefore the desired correction movement cannot be transmitted to the conveyor rolls with the ordinary commercial electromagnetic couplings.

Furthermore a regulating apparatus is known which is characterised in that to the measuring member of the regulator there is added an intermediate member which records the defect pulses coming from the feelers, according to sign and frequency, and delivers setting pulses, dependent upon the totalling of these pulses, according to choice to one of the two setting members orto both at the same time (GFR.Pub.Sp. 11 55 325).

The aim of this regulating apparatus is to adapt the speed of regulation largely to the magnitude of the ascertained defect. The disadvantage of this device consists in that the regulation can be introduced only with two feelers or setting members. Therefore this device cannot be used for the packing material feed devices used in the ordinary way in the construction of packing machines, since the regulation can be effected only with a feeler member or setting member.

Furthermore still other such devices are generally known which all possess the disadvantage that they render possible only a correction within a fixedly set correction range between the indicator marks. A precise correction of the strip of packaging material according to the ascertained deviation is not thus achievable.

The invention has the aim of increasing the accuracy of correction in such a device.

The problem of the invention consists in ascertaining the actual position of the web in comparison with the impressed marks in order to instigate a correction in accordance with the ascertained deviation.

In accordance with the invention this is achieved in that the compensating gearing is connected for drive with a direct-current motor the input voltage of which is variable by means of an electronic regulator device through a slotted disc, driven by the single revolution shaft and generating increments, in combination with an actuator disc arranged on the single-revolution shaft and instigating a start pulse and the opto-electronic scanner head which delivers a stop pulse. Thus it is possible that the web is corrected in accordance with the actually occurring deviation from the ideal position, through the compensating gearing. In the case of conformity with the impressed mark a correction is superfluous, so that few setting movements of the compensating gearing are necessary. This is very favourable especially in an automatic reel change, since the impressed mark is adjusted quickly.

According to a further feature of the invention the actuator disc is adjustably arranged on the singlerevolution shaft. Thus in the processing of webs with different impressions the actuator disc can advantageously be set so that it is no longer necessary to vary the position of the scanning head.

The invention is explained diagrammatically in an example of embodiment in the drawing.

The web B of packaging material provided with impressed marks M is transported with the aid of the device as described below in the direction of the arrow. This feed device consists essentially of a lower drawing roll 2 and an upper drawing roll 1 between which the material web B is guided. The lower drawing roll 2 is connected through a shaft 3 with a compensating gearing 4, consisting of a cross-piece 4a, two planet wheels 4b, 4c, a drive wheel 4d and a drive wheel 4e. The compensating gearing 4 is driven through several change gears 5a, 5b, Sc by a single-revolution shaft 6, through a change gear 5d arranged thereon. On the crosspiece 4a of the compensating gearing 4 a spur gear 7 is secured which is in engagement through two further spur gears 8,9 with a spur gear 10.The spur gear 10 is coupled with a bevel wheel 11 which meshes with a bevel wheel 12.

The bevel wheel 12 is secured on the motor shaft 13 of a direct-current motor 14which can introduce an additional drive to the compensating gearing 4.

On the single-revolution shaft 6 there are secured an actuator disc 15 and a slotted disc 16. The actuator disc 15 can be adjusted on the singlerevolution shaft 6 in dependence upon the position of the impressed mark. The actuator disc 15 and the slotted disc 16 are connected with initiators 1 spa, 16a which are connected through the leads 1sub, 1 6b to an electronic regulator device with counter 17. A scanner head 18 is connected through a lead 18a to the electronic regulator device 17. By connection to the electronic regulator device 17 by means of a lead 19 an input voltage is fed to the direct-current motor 14.

The manner of operation of the invention is the subject of the following description.

The material web M is transported by means of the drawing rolls 1,2 in the direction of the arrowx. The two drawing rolls 1,2 rotate in opposite directions the drive being transmitted through the shaft 3 only to the lower drawing roll 2. In the normal case when the drawing is in conformity with the impressed marks M, the material web B is conveyed by the drawing rolls 1,2 equally at the spacing of the impressed marks M. A drive movement is introduced to the shaft 3 of the lower drawing roll 2 through the compensating gearing 4 on the one hand from the single-revolution shaft 6 and on the other through the direct-current motor 14. This normal drawing is designed for a specific range of impressed marks. By replacement of the change gears 5a to 5d other conveyed lengths are also achievable.In this normal case the rotation speed of the direct-current motor 14 amounts to one half of the maximum rotation speed.

If deviations in relation to the impressed marks M occur in the delivery of the material web B, the rotation speed of the direct-current motor 14 is raised or lowered. Thus the rotation speed of the compensating gearing 4 also varies accordingly.

This leads to a variation of the drawing of the material web B. The direct-current motor 14 is controlled by the regulator device 17. A number of pulse is fed to the regulator device 17 per machine cadence through the initiator 1 6a by the slotted disc 16 arranged on the single-revolution shaft 6. The actuator disc 15 likewise arranged on the singlerevolution shaft 6 in combination with the initiator 15a delivers a start pulse for the counter situated in the regulator device. When the impressed mark runs through beneath the scanning head 18 the signal delivered by the scanning head effects stopping of the counte in the regulator device 17. In the regulator device 17 the counter state is evaluated and converted in dependence upon the machine rotation speed into a direct-current voltage. The magnitude of this direct-current voltage corresponds to a specific position of the impressed mark M in relation to the start pulse triggered by the actuator disc 15.

In the normal case the signal delivered by the scanning head 18 lies exactly between two pulses which are triggered by the actuator disc 16. If the signal delivered by the scanning head 18 varies positively or negatively from the middle position, then by means of the regulator device 17, in evaluation of the counter state, the direct-current voltage is varied until the middle position is reached again. This direct-current voltage upwardly or downwardly varies the rotation speed of the direct-current motor 14 in relation to the standard rotation speed.

Claims

1. Device for the correcting regulation of a strip of packaging material provided with impressed marks, using a setting member for influencing the drawn-off length in both directions and an optoelectric scanning head for scanning the impressed marks in comparison with a position of the singlerevolution shaft of the packaging machine, consisting of a compensating gearing allocated to the basic drive of the feed means and acting with a setting movement additionally upon the conveying means, characterised in that the compensating gearing (4) is connected for drive with a direct-current motor (14) the input voltage of which is variable through an electronic regulator device (17) by a slotted disc (16), driven by the single-revolution shaft (6) and generating increments, in combination with an actuator disc (15) arranged on the single-revolution shaft (6) and generating a start pulse and with the opto-electronic scanning head (18) which delivers a stop pulse.

2. Device according to Claim 1, characterised in that the actuator disc is adjustably arranged on the single-revolution shaft.

3. A device for the correcting regulation of a strip of packaging material substantially as described with reference to the accompanying drawings.