EP0513482B1 - Side mark and overlap inspection in a rotary sheet fed press - Google Patents

Abstract

A side lay and overlap control device of a sheet-fed rotary printing machine is described which has a lateral sensor arrangement (14, 15) having a single sensor. The control actuates the transverse conveyor (10) when a sensor arrangement assigned to the front lays determines the presence of a sheet (3, 3a, 3b) and the lateral sensor (14, 15) determines that no sheet (3, 3a, 3b) is present. <??>The control device according to the invention is of simpler construction than conventional control devices and it operates more precisely with less waste. <IMAGE>

Description

The invention relates to a side mark and overdrawing control of a rotary sheet-fed printing machine with a lateral stop for the lateral alignment of sheets conveyed on a system table of the machine, with which stop a cross-conveyor which can be actuated in a controlled manner and which conveys the incoming sheets against the lateral stop, also with one the side stop arrangement assigned to the side stop, which determines whether a sheet is present (side mark control) or whether a sheet undermines the side stop (pull-over control), furthermore with front stops for aligning the front edges of the sheets and with a front stop assigned to the front stops Sensor arrangement that determines whether there is a sheet in the area of the front stops and with a controller that processes the output signals of the sensor arrangement.

A conventional side mark and pull-over control of this type has a first sensor which is arranged on the outside of the stop. If it detects a sheet, the control is actuated in the sense of a corresponding correction, preferably the drive is stopped, because otherwise waste would be produced.

The well-known side mark and overturn control has another sensor on the inside of the stop. If the sensor detects an arc, the cross conveyor is actuated, which conveys the arc to the side stop. Both sensors usually work on the principle of optical reflections. This means that an arc passing under the sensors reflects the light striking it and this is a signal for the presence of the bow.

However, the known side mark control described has the particular disadvantage that the sensor actuates the cross conveyor even when the sheet in question is too close to the lateral stop, so that a transverse position of the sheet can no longer be corrected by the cross conveyor. The sheet is then deformed (compression), in particular because the cross conveyor exerts a force on the sheet without it being able to move noticeably laterally.

The invention avoids these disadvantages. It is based on the task of proposing a side brand and overdrawing control with the features mentioned at the outset, which is to be distinguished by a simple structure and with which both controls and in particular the side brand control can be carried out very effectively, with practically no waste.

To achieve this object, the invention is characterized in that the lateral sensor arrangement has a sensor which is arranged at a measuring distance from the lateral stop which is smaller than a minimum distance which is determined from the drawing path of the sheet to the lateral stop and from the lateral stop is measured towards the center of the system table, and that the control operates the cross conveyor when the front sensor arrangement detects an arc and the lateral sensor arrangement detects no arc (side mark control).

The essence of the invention is therefore that the already existing sensor arrangement of the front marks, which in the prior art is not connected to the lateral sensor arrangement in terms of control, is used according to the invention to determine whether a sheet is present or not. If a sheet is in contact with the front marks - and is determined by the front sensor arrangement assigned to the front marks - this sheet is also for the side mark control because the side mark control is only slightly spaced in front of the front marks in the conveying direction of the sheets. On the other hand, the sensor arrangement of the side mark control according to the invention cannot be used, as in the prior art, to determine whether a sheet is present - this is done by the sensor arrangement assigned to the front marks - but the lateral sensor arrangement determines whether the sheet in question is within the range defined above There is a minimum clearance. If the sheet is at a minimum distance, there is a risk that the necessary drawing path is no longer available and the sensor then sends a corresponding correction signal to the control, which eliminates this condition. For example, the conveying of the sheets is stopped or the stacking table with the supply of the sheets to be conveyed is moved laterally in such a way that the subsequent sheets come with certainty outside the minimum distance to the side mark inspection.

The basic principles of side brand control were explained above. However, the same sensor can also provide the pull-over control at the same time, because according to the invention it is arranged in the minimum distance defined above, ie close to the lateral stop. This is why an important embodiment of the invention, characterized in that the side sensor arrangement has the sensor as the only sensor, which then takes over both controls (side mark control and pull-over control).

It has already been mentioned that sensors are generally used which work on the optical reflection principle. This is also preferred in the present invention, although infrared sensors and the like can also be used. It is essential to this extent that the sensor emits a beam (light beam) which is more or less covered by the arc when an arc is present. The light reflected from the arc is then measured. Alternatively, the transmitted light can also be measured.

If the control detects a coated sheet, this covers a much larger proportion of the light beam than in the case of the side mark control, in which case the sheet will only cover a much smaller part of the light beam, namely that part of the light beam which is towards the center of the system table points.

For this reason, a further important embodiment of the invention is characterized in that the sensor of the side sensor arrangement generates a signal which extends in the conveying direction of the cross conveyor and which is weighted and evaluated according to its intensity, with an output signal component of high intensity in the control as a pull-over control is evaluated and an output signal portion of low intensity as a side mark control. One takes advantage of the fact that the reflected Signal components are proportional to the area that the sheet covers from the flat measurement signal.

If you do not work with reflective, but in continuous light, the conditions are reversed, i.e. an output signal component of high intensity is evaluated by the controller as a side mark control and an output signal component of low intensity is evaluated by the controller for the stall control.

Fig. 1 -

schematisch eine Draufsicht auf einen Anlagetisch mit Vordermarken und Seitenmarken zur Erläuterung des erfindungsgemäßen Prinzips;

Fig. 2 -

demgegenüber vergrößert und ebenfalls schematisch eine Stirnansicht der Seitenmarke mit Anlagetisch und einem an der Seitenmarke anliegenden Bogen;

Fig. 3 -

ebenfalls vergrößert und stärker schematisiert die Situation von Fig. 1 zur Erläuterung weiterer Details;

Fig. 4 -

ein Diagramm, wobei die verschieden starken Ausgangssignale des Sensors des seitlichen Anschlags wiedergegeben sind.

The invention is explained in more detail below on the basis of exemplary embodiments, from which further important features result. It shows:

Fig. 1 -

schematically shows a plan view of a system table with front marks and side marks to explain the principle of the invention;

Fig. 2 -

on the other hand, enlarged and also schematically, an end view of the side mark with contact table and a sheet resting on the side mark;

Fig. 3 -

likewise enlarged and more schematically the situation of FIG. 1 to explain further details;

Fig. 4 -

a diagram, wherein the different output signals of the sensor of the side stop are shown.

In Fig. 1, a plant table 1 is indicated, on which sheets are transported one after the other in the direction of arrow 2. The sheets come from an investment machine. At the end of the feed table, they are aligned with their front edges and left side edges and then fed to the first inking unit of the sheet-fed printing press. In addition to the general situation, reference is also made to the German patent specification 15 61 015. (Alternatively, the sheets can of course also be aligned on their right side edges.)

In Fig. 1 one of the sheets 3 is almost on front marks (front stops) 4, which are attached to a register bar 5. Sensors 6 work together with the front marks and give a signal to the control of the machine as soon as they detect an arc.

In addition, a side mark 7 (lateral stop) is provided, on which a guide plate 8 is also attached. See also FIG. 2. This shows one of the arches 3 in contact with the inner contact surface 9 of the stop 7, while in FIG. 1 the arch is at a certain distance from the contact surface. The assembly 7.8 is usually adjustable laterally and in height.

In Fig. 1, a cross conveyor 10 is also indicated, which, when actuated by the controller, transversely, i.e. in the direction of arrow 11, against the stop 7 promotes.

A minimum distance 13 is defined between the contact surface 9 and an imaginary line 12. The incoming sheets should lie outside this minimum distance so that the cross conveyor 10 can possibly pull sheets that are not oriented at right angles via the pull path defined by the distance 13 to the stop and via this pull path the sheet can actually straighten without upsetting the bends.

A single sensor 14 is arranged within the minimum distance 13.

The device works as follows. If a sheet arriving in the position shown in FIG. 1 is detected by the sensors 6 of the front marks, this state is assessed as correct and the control activates the cross conveyor 10 so that the sheet in question is pulled against the contact surface 9 of the stop 7. The sensor 14 has not detected a sheet prior to the activation of the cross conveyor and the activation of the cross conveyor 10 assumes this state, i.e. that the sensors 6 detect an arc and the sensor 14 detects no arc. The sheet is then laterally aligned at the stop 7. It can then be removed.

If a sheet is conveyed whose left edge does not run outside the distance 13, as shown in FIG. 1, but within the distance, this sheet is sensed by the sensor 14. The control system therefore receives notification via sensors 6 and sensor 14 that a sheet is present, specifically within the minimum distance 13. This is information that a malfunction has occurred, which the machine control system then removes in a suitable manner, for example by stopping the Conveying along the system table and / or by laterally shifting the upstream stack of sheets in the opposite direction of the arrow 11 until the position of the sheets which has been recognized as correct and is shown in FIG. 1 is reached.

Even if a sheet is conveyed so that it is covered by the side mark 7, i.e. if the cross conveyor is at risk of coming under the side mark and jamming there, the sensor 14 emits a corresponding signal and, as explained above, the error is eliminated. A similarly positioned fault situation is shown in FIG. 3 with respect to the sheet 3a, in which there is a risk that the sheet 3a abuts the stop 7 with its front edge.

This so-called pull-over control can also be carried out by a further sensor 15, for which it is important that it is arranged in the region of the stop 7, i.e. to the right of it, as drawn in FIG. 1, to the left of it or at its height and then preferably in the conveying direction (arrow 2) in front of the stop 7.

3 and 4 explain the signal evaluation with the single sensor 14. For this purpose, an arc 3b is shown in FIG. 3, the left edge of which slightly covers the light cone of the sensor 14. This coverage area is indicated at item 16. If the sensor arrangement works on the principle of reflected light, only the relatively small area 16 reflects the light back into the sensor and this results in a relatively small signal 17, which is shown in FIG. 4.

However, if there is a risk of being pulled over, a larger part of the light cone of sensor 14 is covered and this results in a much larger signal, which is shown at item 18 in FIG. 4. In this diagram, the output signal of the sensor 14 is plotted as a current or voltage.

A discriminator circuit can now differentiate the signal level, as indicated by level 19 in FIG. 4.

If the sensor 14 detects a signal 17 lower than the threshold level 19, this means that the cross conveyor must not be activated (side mark control). If, on the other hand, the control detects a larger signal 18 above level 19, there is an overdrawing.

4 also shows the chronological sequence of the query. From the lower part of Fig. 4 it follows that the smaller signal 17 is generated by the sheet 3b and the larger signal 18 by the sheet 3a. (See also Fig. 3.)

Compared to conventional controls, the invention therefore only requires a change in the software of the control and only a single sensor 14 is required. Despite this simplification, the control works much more reliably and there is noticeably less waste.

Claims (3)

1. Side lay and overdraw check of a rotary sheet printing press with a lateral stop (7) for laterally aligning sheets (3, 3a, 3b) fed on a feed table (1) of the press with which stop (7) a controllably actuated transverse feeder (10) cooperates which feeds the arriving sheets (3, 3a, 3b) against the lateral stop (7), furthermore with a lateral sensor arrangement (14, 15) coordinated with the lateral stop (7) which determines whether a sheet (3, 3a, 3b) is present (lateral register check) or whether a sheet (3, 3a, 3b) runs under the lateral stop (7) (overdraw check), further with front stops (4) for aligning the front edge of the sheet (3, 3a, 3b) as well as with a front sensor arrangement (6) coordinated to one of the front stops (4) which determines if a sheet (3, 3a, 3b) is present in the region of the front stops (4) and with a control which evaluates the output signals of the sensor arrangement (6, 14, 15), characterised in that the lateral sensor arrangement has a sensor (14) which is arranged at a measured distance (13) from the lateral stop (7) which is smaller than a minimum distance which is determined by the pulling path of the sheet towards the lateral stop and which is measured from the lateral stop towards the centre of the feed table, and that the control of the transverse feeder (10) is actuated if the front sensor arrangement (6) sees a sheet (3, 3a, 3b) and the lateral sensor arrangement (14, 15) sees no sheet (side lay checking).
2. Side lay and overdraw check according to Claim 1, characterised in that the lateral sensor arrangement has the sensor as a single sensor (14).
3. Side lay and overdraw check according to Claim 2, characterised in that the sensor (14) of the lateral sensor arrangement generates a preferably optical signal which extends in the feed direction of the transverse feeder and which is weighed and evaluated according to its intensity, wherein an output signal proportion (18) of higher intensity is evaluated in the control as overdraw check and an output signal proportion (17) of lower intensity is evaluated as a side lay check.

Images