JPH04310397A - Device for positioning cutting edge of pair of disk knives of longitudinal direction cutter of paper web - Google Patents

Abstract

PURPOSE: To provide a positioning device for cutting edges of a pair of disk knives of a cutting device for cutting paper web in the longitudinal direction thereof capable of quickly and accurately position the cutting edge. CONSTITUTION: This device is provided with sliders 6, 9 for carrying disk knives 4, 5, rails 7, 11, 33 for supporting these sliders, a sensor 31 movable in parallel with a route of the sliders, and a slider driving device. A distance between the cutting edge 19 of the disk knife and a fixed mark 34 is obtained by the sensor.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION The invention relates to a device according to the preamble of claim 1.

0002

BACKGROUND OF THE INVENTION A device of this type is known from German Patent Specification No. 34 17 042.

[0003] The load on the disc knife is 3000 m/min.
It is extremely high at high speeds reaching up to . Because of this, wear is also very significant. This is especially true of so-called under-knives which are constructed in the shape of a pan. Therefore, disc knives must be resharpened from time to time to eliminate wear irregularities. This is done in the case of an underknife by resharpening the edges of the pan, thus making the pan "shallower". Here the amount can reach up to 2 mm.

Positioning is limited to bringing the slider to a specific location, and if the position of the cutting edge with respect to the slider changes due to sharpening, this change in position will affect the width of the split web produced. The split web will deviate from the target value by that amount.

[0005] In many cases this is unacceptable. It is known to compensate for changes in the position of the cutting edge due to sharpening by means of a support disk. This method is time consuming and error prone. This is because the required attachment disc must be determined by measurements that must be carried out for each pair of knives, and errors due to tolerances remain.

The basic concept of taking into account the wear of the disc knife in the control unit can be seen as such in DE 31 44 714 A1. However, this relates to a different device than the present invention in that each slider has its own drive motor. Each slider is associated with a respective wear electrode, which supplies the control with electrical signals for adjusting the slider to compensate for knife wear. It is not clear from DE 31 44 714 how this is to be implemented in detail, and in particular how the corresponding measures are realized in the longitudinal cutting machine according to the invention.

According to the publications mentioned at the outset, each knife slider has a fixed mark (fixed to the slider), which - along the direction of movement of the slider - cuts the underknife. It has a constant spacing to the edge. When the underknife is resharpened and reattached to the slider, the slider is guided past a position sensor installed at a fixed location. At this time, two signals are emitted. One signal is emitted when the cutting edge passes the position sensor, and the other signal is emitted when the indicator fixed to the slider passes the position sensor. The signal is provided to a microprocessor control. By calculating the correction amount by this control unit, accurate positioning is performed taking into account the reduction in the material of the underknife caused by sharpening.

[0008] Therefore, first of all the relative quantities are obtained, from which the absolute quantities for the actual knife position must then be ascertained by the control.

However, this known device and the method using this device have the following drawbacks.

[0010] There are only a limited number of sensors. It may therefore occur that a knife pair has to be introduced into the movement area of another knife pair in order to be moved past the sensor provided for that knife pair. In such a case, the already positioned knife pair or knife slider would have to be moved and finally returned once again to the originally adjusted position. In this case, the following inconvenience occurs. Firstly, it takes more time to consistently position the individual cutting edges. Furthermore, considerable control costs are required. Finally, there is a risk of inaccuracies in the positioning, due to the added risk of measurement errors and the inertia of the system, where also disadvantageous hysteresis effects may occur.

The main object of the invention is to construct the device according to the preamble of claim 1 in such a way that the cutting edge can be positioned quickly and unobjectionably. The cost of the control section required for this purpose is made smaller than in the past.

0012

This object is achieved by the features described in the characterizing part of claim 1.

The decisive concept here is to provide a sign installed at a fixed position (fixed to the machine) instead of a sign fixed to the slider, and also to provide a sign on the knife slider instead of a sensor fixed in place. The object is to include one or more sensors movable parallel to the path.

[0014] Generally this will be an optical sensor. Furthermore, it is preferable to mount this sensor on a measuring slide running on a rail. In this case, the measuring slide, together with the sensor mounted above, is moved past the individual knife slider and its cutting edge, and this also occurs when the cutting position changes, for example when starting up the rotary cutting machine. This is true even after replacing an old knife with a new knife and after sharpening the knife.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in more detail with reference to the drawings.

The paper web runs between two deflection rollers 2, 3, which are mounted on the frame M of the machine, and passes through the device perpendicularly in the direction indicated by the arrows in FIG. 1, where it is cut longitudinally. be done. The stock roll and the dividing roll on which the dividing web resulting from the longitudinal cutting is wound up again are not shown.

The web is divided by means of cooperating disc knives, ie so-called under-knives 4 and over-knives 5. The underknife 4 is journaled on an underknife slider, generally designated 6, which is guided along a rail 7 connected to the frame M of the machine and running transversely across the width of the web. The feed rod 8 is longitudinally movable in the rail 7 so that the underknife slider can be moved along the rail 7 to a desired position corresponding to the cutting position of the web 1.
The underknife slider 6 can be coupled to this feed rod as required.

The underknife 4 is driven in the direction shown, while the overknife 5 has no drive and simply idles along with it. The overknife 5 is supported by an overknife slider, generally designated 9, which, like the underknife slider 6, is extended laterally across the width of the web by a feed rod 10 and is moved by the machine. It is movable along a rail 11 fixed to the frame M. A pneumatic piston/cylinder unit 12 is arranged on the overknife slider 9, the piston 13 of which can be delivered perpendicularly to the web 1 towards the underknife slider 6 under the action of a spring 14. . Mounted at the forward end of the piston rod 15 is another piston/cylinder unit 16 , the axis of which extends parallel to the axis of the underknife 4 , the piston of which moves against the action of the spring 18 . According to FIG. 2, the overknife 5 can be displaced in such a way that it is pulled upwards.

The piston/cylinder unit 12 is for controlling the movement of the overknife 5 toward the underknife 4, and the piston/cylinder unit 16 is for controlling the movement of the overknife 5 toward the end face forming the cutting edge of the underknife 4. It is for placing on the edge 19 of the
As a result, a predetermined cutting pressure is strictly adhered to. Control is performed by a solenoid valve 20 attached to the over-knife slider 9, which in operation directs compressed air into a conduit 21.
from the piston/cylinder unit 12 via conduit 22
1, which causes the overknife 5 to be displaced to the right according to FIG. When the displacement is completed, the flow channel 23 formed in the piston 13 and the piston rod 15 is also connected to the compressed air conduit 22 so that the piston/cylinder unit 16 receives compressed air, so that the overknife 5 is connected to the end face 19 of the underknife 4. being towed towards. In this way, the operations are performed in an order that prevents the overknife 5 from hitting the periphery of the underknife 4.

Each pair of knives 4, 5 or each pair of sliders 6,
A solenoid valve 30 attached to the slider 9 is used to lock and release the sliders 6 and 9 from the respective rails 7 and 11. Compressed air is provided via conduit 26. The locking and unlocking device, which will be explained in more detail in connection with FIGS. 4 and 5, connects sliders 6, 9 to rails 7,
It can be left free along the line and simultaneously connected to the feed rods 8, 10, or it can be uncoupled from the feed rod and locked to the rails 7, 11. The locking and locking release device is operated using the solenoid valve 3.
0 simultaneously on the sliders 6, 9 via the conduits 27, 28, so that both sliders 6, 9 can be moved simultaneously.

FIG. 3 also shows two deflection rollers 2 and 3.
is shown, as well as a movable sensor 31, a measuring slide 32, a rail 33 for the measuring slide and a marking 34 fixed to the machine. sensor 3
1 and the measurement slider 32 are movable in the direction of the double arrow A. The measurement direction is indicated by arrow B.

Method of operation of the device When using an incremental displacement system, the actual value of the position is determined by means of an up-down counter.

Before starting the operation, a reference point (switch lug or reference mark) is reached and the counter is set to zero. This reference point corresponds to the zero point of the reference.

[0024] For each step of movement in one direction, the counter counts up, and for each step of movement in the other direction, the counter counts down.

This is necessary so that the instantaneous position of the scanning head is controlled in the event of a malfunction.

The counter always contains the actual value of the position associated with the reference point.

FIG. 4 diagrammatically represents the individual steps of the control.

The individual points of the flowchart are illustrated in FIG.

[0029] When the knife is resharpened or when the rotary cutter is started, the number of the knife whose position is to be verified is entered.

When the start key is pressed, the piston starts moving rapidly (vE = 200 mm/s). When the piston is over the reference mark, the counter must be set to zero.

Each knife edge emits a signal i which is summed by the control.

If the step consists, for example, in determining the position of the knife numbered 4, then z* = 2 * z - 1, then until the signal of i = z* - 1 is added in the counter, The piston advances rapidly.

An exception is the case of edge knives at the ends of the measuring section.

In this case, z* = 2 * z The value is calculated using the formula.

When the knife edge i=z*-1 is reached, the advance control switches to a low speed vs =10 mm/s.

[0036] Minimum distance between underknives is 180m.
m, so this process must take place within a section of approximately 150 mm.

Upon reaching the knife edge z* with slow progression, the corresponding sensor sends a pulse to the control and an incremental measurement value is accepted.

The scanning unit scans the next knife edge (z*
Further speed v = 10 mm/s until +1) is recognized.
Move with.

In the case of an edge knife at the end of the measuring section, the switching process takes place without a separate edge signal. In this case, the final value of the signal pulse controls the switching of the movement process. That is, if the signal pulse is at its maximum value, a change in direction and speed of the piston takes place.

Reverse travel is performed at rapid forward speed.

[0041] When reached, the signal transmitter attached to the cylinder returns an announcement that the piston is in its rear end position.

[0042]

As described above, according to the present invention, a cutting edge can always be positioned quickly and accurately, and a relatively inexpensive and high-performance positioning device of this type can be provided.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of an apparatus according to the present invention.

FIG. 2 is a top view of the device of FIG. 1, with some sections in section.

FIG. 3 is a schematic diagram as seen in the web feeding direction.

FIG. 4 is a control flowchart.

FIG. 5 illustrates several knife pairs in different scanning positions.

[Explanation of symbols]

1 Web 2, 3
Turning roller 4
under knife 5
over knife 6
Under knife slider 7, 11, 33
Rails 8, 10 Feed rod 9 Overknife sliders 12, 16 Piston/cylinder unit 13 Pistons 14, 18 Spring 15 Piston rod 19
Cutting edge 20, 30
solenoid valve

Claims (3)

[Claims] 1. Longitudinal cutting of a web, such as paper, comprising a knife slider carrying a knife, a rail extending transversely to the direction of the machine and carrying the knife slider, and further comprising an indicator provided at a fixed position. In the device for positioning the cutting edge of the disc knife pair of the machine, at least one sensor movable parallel to the path of the knife slider comprises:
Device, characterized in that it is provided for knowing the distance between the cutting edge (19) of the disc knife (4, 5) and a mark provided in a fixed position. 2. Device according to claim 1, characterized in that the sensor is an optical sensor. 3. The sensor according to claim 1 or 2, characterized in that the sensor is carried by a measuring slide, and a measuring rail is provided which is arranged parallel to the rail for the knife slider and supports the measuring slide. The device described.