EP0976509B1 - Method and apparatus for slitting web material - Google Patents

Description

The invention relates to a method for slitting a material web running in the direction of travel, in which at least one knife unit on a carrier in one Machine frame moved transversely to the direction of travel and the position of your cutting edge in the machine frame becomes. The invention further relates to a device for longitudinal cutting of a machine running in the running direction Material web with at least one knife unit, which has a cutting edge and arranged on a carrier is in a machine frame across the Running direction is displaceable, and with a measuring device to determine the position of the cutting edge.

The invention is based on a paper web described as an example of a material web. she is but with all other material webs that are in the course their production in longitudinal strips of predetermined width must be cut, applicable. examples are Plastic or metal foils or cardboard sheets. In some cases, slitting also serves only for straightening one that runs parallel to the running direction Longitudinal edge. In this case, too Invention application.

Paper webs are often produced in widths that are too big for the later user. Modern paper machines produce paper webs in widths of up to 10 m, Users, such as printers, use paper webs up to a maximum of 3.8 m at present. In most Cases the desired width is even lower, namely in the range between 0.8 and 2 m. It is therefore necessary to close the paper web before winding Subdivide winding rolls into several partial webs. This Longitudinal cutting is carried out with every cutting line a knife unit, usually in a "silhouette" works and by a circular top knife on one side of the paper web and one too circular, lower knife on the other side of the Paper web is formed, usually at least one of these knives is powered. The touch plane forms between the upper knife and lower knife Cutting edge. The cutting edge usually falls with one end of the lower knife together.

The width of the partial paper webs desired by the user is given relatively precisely. The tolerances are here in the range of ± 0.25 mm. To this accuracy the cutting edges of the knife unit be positioned with the appropriate accuracy can. When the knife unit in the desired position has usually been spent Measure once whether the cutting edge is the desired one Has reached position. You can do this, for example use a steel measuring tape from a precisely defined reference position of the machine frame with a given force parallel to the direction of displacement the carrier is clamped. The positions of each Cutting edges can then be on this Read the measuring tape. If you put these positions into one programmable logic controller can be entered then move to other positions, for example when changing the cutting plan. This process will also called manual calibration.

Because such a manual calibration is relatively cumbersome and is time consuming, one has in DE 34 07 258 A1 suggested after positioning the carrier and thus the cutting edge a transducer over the Working width to move. The transducer determines the cutting edge positions relative to a machine-fixed Zero. Here, the individual Cutting edge positions, however, only in chronological order determine. A continuous recording is not possible. Therefore, the determination of all positions costs relatively much time and the longer the longer the measuring section is. The determination of the cutting edge positions is relative. The values of the positions are there not immediately after starting up the device Available.

DE 34 17 042 C2 shows a similar method in which on the one hand the position of the carrier in the machine frame determined, but also the position the cutting knife edge on the respective carrier. to The individual carriers determine this position sequentially passed sensors in the machine frame are stationary, with those leading past necessary time between a marking on the carrier and the cutting edge a statement about the distance of the Cutting edge allowed from this mark. This approach has the advantage that one in operation permanently about the position of the beams in the machine frame can be informed. The absolute position of the However, the cutting edge is still faulty. This results in on the one hand by the fact that this position is only relative can be determined. Second, changes, that occur during operation, for example through Wear, not detected.

The cutting knives of a knife unit usually have to be reground from time to time. After every Regrinding therefore requires recalibration. In addition, however, arise in the Operation wear and tear that is quite common in the Order of magnitude of the tolerance range.

GB 2 290 496 A describes a positioning device for Lower knife in slitting machines. The lower knife are cup-shaped and on a lower knife shaft postponed. You can't go there any closer presented means are determined. After postponing is the position of the cutting edges of the bottom knife initially unknown. To determine the position, move a slide parallel to the lower knife shaft. The The carriage carries two optical lasers. Every laser has one Transmitter for a laser beam and a receiver for the reflected laser beam, the laser beams have a relatively small distance from each other, for example 0.1 mm or less. Accordingly, one can by combining the signals from the two lasers, whether the cutting edge is between the laser beams located or not.

US 4 607 552 shows a device for automatic Position of a variety of cutters. With the Cutting devices can be a material web W in the running direction divide. A knife unit is placed on one Carrier moved transversely to the direction of travel. To do this, click on each positioning module electrical control elements and magnetic reference points are provided on a first rail. Using the reference points, the system can determine whether the corresponding slide has moved far enough has been. There is a wear detection switch on the carriage of the upper knife provided with a proximity switch, which is controlled by eddy currents, which in the Neighborhood of the upper knife is created around the upper knife to position relative to the lower knife.

The invention has for its object the determination to improve the position of the cutting edge.

This task is carried out in a method of the type mentioned at the beginning Art solved in that the position of the Cutting edge immediately on the carrier and the position the carrier is determined in the machine frame and the absolute position of the cutting edge in the machine frame by combining these two positions is formed.

With this procedure, there is no relative measurement the cutting edge and a reference position to points in the Machine frame. The position of the cutting edge on the Rather, the carrier becomes immediate and therefore with one determined higher accuracy. So you can also in Operation Information about the position of the cutting edge win without being required during a Business interruption the carrier past sensors close and then reposition them. There with any repositioning is at risk of error, this reduces the risk of errors.

At least the position of the cutting edge is preferred on the carrier by measuring a distance between the cutting edge and a beam-fixed first Fixed point determined. This approach is preferable because the distance of the cutting edge from the fixed point changes, for example when the Cutting edge due to regrinding of the lower knife relocated.

It is particularly preferred that it is monitored whether the distance exceeds or exceeds a predetermined minimum falls below and falls within a predetermined maximum dimension If an error message is issued. The question, whether you monitor a minimum or a maximum, then decides from which side you can view the Measures distance to knife edge. If one of the "Back" of the knife measures, then you become a minimum monitor. If the knife is sharpened too much has been, it is no longer usable because of it Has undersize. However, if one from the other Side, then the distance from the cutting edge increases with increasing grinding, so that after a certain number of grinding operations also none there is more usable knife. The same applies of course also in operation if there are signs of wear result. This can be done by monitoring immediately are displayed.

A particular advantage of the invention is that that both positions are determined permanently. So you can use a microprocessor in every program cycle can be read in with a control device is working. Can between individual import processes are quite short times, as is the case with microprocessor-controlled Machines is common. These times but are usually in areas smaller than 1 Second, so that they play no role in practice. By continuously monitoring the positions deviations of the cutting edge from the target position record quickly and compensate if necessary.

The object is achieved in a device of the type mentioned Kind solved in that the measuring device two Has transducers, of which a first transducer is arranged on the carrier and the distance the cutting edge to a fixed first fixed point determined, and a second transmitter the distance a second fixed fixed point from one in the machine frame stationary zero point determined.

By using a solid-state transmitter it enables the position of the cutting edge the carrier to determine immediately, so the risk of an error remains relatively small here. The measurement accuracy can be increased. The position of the carrier in the Machine frame can be determined by determining the Distance between a fixed fixed point and the Determine the zero point in the machine frame. Here too achieve high measuring accuracy. If you both Merging measured values results in an extremely precise Positioning. Since this position determination in Operating position and especially during operation Any errors that may occur can follow be quickly compensated.

The second transmitter preferably has a stationary one active and a movable passive part on. This means that the second transmitter does not require flexible Connections between the carrier and an evaluation device, which makes the operation easier and that Risk of measurement errors further reduced.

The active part is preferably designed as a measuring ruler. Such a measuring ruler works with a placemark, i.e. the second fixed point, on the beam together. The measuring ruler can be optically, acoustically, magnetically, work electromagnetically or capacitively. It allows determining the position with high accuracy.

The two fixed points preferably coincide. This facilitates the evaluation. You need for the calculation the absolute position of the cutting edge Offset more.

A comparator with the first is advantageous Sensor connected, which issues an error message, if the distance is below a predetermined value or exceeds. As above in connection with the The method has been explained, it can be used as a relative achieve simple error monitoring, whether the knife is undersized and therefore replaced must become.

Fig. 1

eine perspektivische Ansicht einer schematischen Anordnung einer Schneideinrichtung mit einer Messereinheit und

Fig. 2

eine Seitenansicht einer Schneideinrichtung mit zwei Messereinheiten.

The invention is described below with reference to a preferred embodiment in connection with the drawing. Show here:

Fig. 1

a perspective view of a schematic arrangement of a cutting device with a knife unit and

Fig. 2

a side view of a cutting device with two knife units.

A schematically illustrated longitudinal cutting device 1 for cutting a running in one direction 2 Material web 3, for example a paper web, has a carrier 4, which is also referred to as a "carriage" can be. This carrier 4 is transverse on rails 5 slidable to the direction of travel 2. He can do this on Rollers 6 be stored. Means to support the carrier 4 to fix after moving, for example one Clamping devices are available for reasons of clarity but not shown.

On the carrier 4 there is a circular knife 7, the is driven by a motor 8. The circular knife 7 is on one side, here the top, the Material web 3. On the other side, i.e. the bottom, a counter knife 9 is arranged on the Circular knife 7 is employed. The counter knife 9 lies under spring force with a relatively small overlap on the end face of the circular knife 7. Circular knife 7 and counter knife 9 thus work together like scissors and create a cutting line 10, the location of which by the position of the cutting edge 11 of the circular knife 7 is defined.

The counter knife 9 of course does not hang freely in the Air. It is attached to a similar support, the but is not shown for reasons of clarity. The carrier of the counter knife 9 can be reduced Accuracy can be positioned because of the counter knife 9 here with spring force on the circular knife 7 becomes.

Since the position of the section line 10 with a relatively large Accuracy of ± 0.25 mm must be observed, the circular knife 7, more precisely its cutting edge 11, positioned with exactly the same accuracy can be. To monitor the positioning is a measuring device is provided. The measuring device has a first transducer 12, the position the cutting edge 11 to a fixed point 13 on the carrier (in Fig. 2 shown as a line) determined. Further points the measuring device on a second transmitter, the from a fixed machine frame (of which only the Rails 5 are shown) mounted measuring ruler 14 and a placemark 15 firmly connected to the carrier consists. The measuring ruler 14 is the active part of the second transmitter and the placemark 15 the passive Part. In the present case, the right edge is the placemark 9 the "measuring point". You can measure ruler 14 and place marker 15 also referred to as a position converter. The same applies to the transmitter 12 and the Cutting edge 11. Both position transducers work without contact, for example optical, acoustic, magnetic, electromagnetic or capacitive type and Wise.

The operation of the position detection is now to be described with reference to FIG. 2 are explained in more detail. Same parts are provided with the same reference numerals. The web of material 3 is for the sake of clarity in FIG. 2 just as omitted as the carrier for the counter knife 9. Two knife units A, B are shown.

The first transducer 12 determines the knife unit A a distance II between the cutting edge 11 and the fixed point 13 (also equal to the right edge the placemark 15). The second transmitter 14, 15 determines a distance I between a zero point 0 and the same fixed point 13. An addition of both distances then provides the removal of the cutting edge 11 to the zero point 0 and thus the exact position of the Cutting edge in the machine frame.

To clarify a difference, one was added Identical knife unit arranged on the right B with a less worn circular knife 7 '. The transmitter 12 can now cover a distance IV between the cutting edge 11 and the fixed point 13 determine. The second transmitter 14, 15 determines a distance III between the zero point 0 and the fixed point 13. From this you can get the absolute distance the cutting edge 11 of the circular knife 7 'from Determine zero point 0.

In both cases it is assumed that the fixed point 13 for the first transmitter 12 and for the second Transmitter 14, 15 is identical. But this is not mandatory. You can also use two different fixed points use. The distance between the two fixed points must then be included in the calculation.

The individual distances I-IV are an evaluation device supplied, which is not shown. The evaluation device can also have a comparator who checks whether the distances II, IV exceed a predetermined minimum value. If the Distances II or IV less than or equal to is this minimum value, then the comparator gives one Warning off. It can be used to ensure that a Circular knife 7 with undersize immediately recognized and displayed becomes.

If a repositioning of the circular knives 7, 7 'is required is, then the control device mentioned the absolute position of the cutting edge 11 on each Carrier 4 known. The control device must then only ensure that the carrier 4 with its fixed point 13 the corresponding position opposite the measuring ruler Take 14. For this purpose, it can move the carriers 4 and that either via its own drive the carriers or via an external drive the carriers, as is known in itself.

Claims (9)

1. Method for slitting a material web (3) running in a running direction (21), in which at least one knife unit is displaced transversely with respect to the running direction on a carrier (4) in a machine frame (5), and the position of its cutting edge (11) in the machine frame (5) is determined, characterized in that the position of the cutting edge (11) is determined directly on the carrier (4) and the position of the carrier (4) in the machine frame is determined, and the absolute position of the cutting edge (11) in the machine frame is formed by combining these two items of position information.
2. Method according to Claim 1, characterized in that at least the position of the cutting edge (11) on the carrier (4) is determined by measuring a distance (II, IV) between the cutting edge (11) and a first fixed point (13) fixed to the carrier.
3. Method according to Claim 2, characterized in that monitoring is carried out as to whether the distance (II, IV) falls below a predetermined minimum amount or exceeds a predetermined maximum amount and, in this case, an error message is output.
4. Method according to one of Claims 1 to 3, characterized in that both positions are determined continuously.
5. Apparatus for slitting a material web (3) running in the running direction (21), comprising at least one knife unit which has a cutting edge (11) and is arranged on a carrier (4) which can be displaced transversely with respect to the running direction (21) in a machine frame (5), and comprising a measuring device for determining the position of the cutting edge (11), characterized in that the measuring device has two measured value transmitters, of which a first measured value transmitter (12) is arranged on the carrier (4) and determines the distance (II, IV) of the cutting edge (11) to a first fixed point (13) fixed to the carrier, and a second measured value transmitter (14, 15) which determines the distance (I, II) of a second fixed point fixed to the carrier from a zero point (O) whose location is fixed in the machine frame (5).
6. Apparatus according to Claim 5, characterized in that the second measured value transmitter (14, 15) has a stationary active and a movable passive part.
7. Apparatus according to Claim 6, characterized in that the active part is formed as a rule (14).
8. Apparatus according to one of Claims 5 to 7, characterized in that the two fixed points (13) coincide.
9. Apparatus according to one of Claims 5 to 8, characterized in that a comparator is connected to the first measured value transmitter (12) and outputs an error message when the distance (II, IV) falls below or exceeds a predetermined value.

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