FI110882B - Method for controlling an endless metal strip in a paper / cardboard machine and a method applying device - Google Patents

Description

110882

A method for controlling an endless metal belt in a paper / board machine and an apparatus for applying the method

The present invention relates to a method for guiding an endless metal belt 5 in a paper / board machine having one or more rolls and at least one guide roll or the like, around which an endless metal belt is arranged to rotate and having a counter roll which presses the endless metal belt against a soft surface roll. forming a nip zone between the endless metal belt and the counter roll through which the web material is passed.

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The present invention further relates to an apparatus for applying a method for guiding an endless metal belt in a paper / board machine having one or more rollers and at least one guide roll or the like around which the endless metal belt is arranged to rotate and having a counter roller against the roll forming a nip zone between the endless metal belt and the counter roll through which the web material can be passed.

From patent application 971342 there is already known a belt calender in which! The v20 endless metal belt is passed through at least a second nip forming a soft surface / roll and a third so-called. around the guide roller. Here are solutions to extend the nip zone by the guide roll and change the heating time of the material web by the guide roll in the belt calender. The transverse movement of the belt, in particular its steering, does not take a position on the reference pulley.

From patent application 931021, a belt calender is known, in which the position of the guide roll relative to the nip can be adjusted, whereby the inlet angle of the web material to the nip is changed. This, in turn, affects the distance between the material and the web in contact with the counter roll (heated roll) before the nip. Also in this publication there is no mention of the axial directional control of the roll of the metal belt, but of the adjustments related to the nip and roll contact of the material web, which are made by the guide roll.

The problem with using a steel belt is its precise tension adjustment around the soft-surface roller and guide roll, since the elastic elongation produced on the steel belt is very small compared to e.g. paper machine wires or belts. Due to the small elastic elongation, tension differences in the axial direction of the rolls are created and the metal belt cannot be accurately guided by the same methods as paper machine wires and belts. For example, at the edge of the treatment side metal belt of the paper / board machine, the tension or tensile stress may be less than that of the drive side metal belt of the paper / board machine. As a result, the metal belt can slide in the axial direction of the roll in the direction in which the belt tension is lower, in this case of the example in the direction of the service side.

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It is an object of the present invention to provide a method and an apparatus for applying the method to eliminate or substantially reduce the disadvantages associated with prior art metal belt tension adjustment and control.

In order to achieve the objects of the invention, the method according to the invention is characterized in that: the endless metal belt is guided in the axial direction of the rolls by adjusting the tension difference between the first edge and the second edge of the endless metal belt. -: * the tension difference between the first edge and the second edge of the metal belt, which for adjusting the edge tension difference: - applying a desired tension force to the first edge of the endless metal belt by means of a first adjustment cylinder 30; is applied to the other side of the endless metal strap: '· *. the desired tightening force by means of a second adjusting cylinder at one end of the guide roller; 3 110882 - providing a tensioning or loosening force on the first edge of the metal belt by means of an auxiliary adjustment cylinder arranged at the first end of the guide roll to adjust the tension difference between the first edge and the second edge; determining the position of the endless metal belt in the axial direction of the rolls by means of a position sensor; and that - adjusting the tightening or loosening force formed by the auxiliary control cylinder based on the determined position information by means of adjustment means arranged in connection with the auxiliary control cylinder.

Further, in order to achieve the objects of the invention, the apparatus employing the method is characterized in that, for guiding the endless metal belt in the axial direction of the rolls, the tension difference between the first edge and the second edge of the endless metal belt is adjustable having a desired clamping force applied to the first edge of the endless metal belt; a second adjustable cylinder is provided at the second end of the guide roll or the like. the desired clamping force at one end of the endless metal belt; «· · · J. (. 20 - an auxiliary adjustment cylinder is provided at the first end of the guide roller or the like for forming the first edge of the metal belt

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., ..; force to tighten or loosen the first edge; • · - a position sensor is provided adjacent to the metal belt to determine the position of the metal belt: in the axial direction of the rolls; and that adjusting means are provided in connection with the auxiliary adjusting cylinder »t · 25, by means of which the tensile tightening or loosening force produced by the auxiliary adjusting cylinder · ·: is adjustable according to the determined position information.

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Preferred embodiments of the present invention are set forth in the dependent claims.

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The invention will now be described with reference to the accompanying drawings, in which: 4 110882

Figure 1 shows a portion of the calender in an axonometric view.

Figure 2 is a front view of the belt calender portion of Figure 1.

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Figure 3A is a schematic view of another embodiment of the invention.

Figure 3B is a schematic view of a third embodiment of the invention, 10 and

Figure 3C is a diagrammatic view of a fourth embodiment of the invention.

Figures 1 and 2 illustrate an embodiment of the invention for guiding an endless metal 15 belt 6 in a belt calender 1. Figures 1 and 2 thus show a portion of a belt calender 1 having a soft-surface roll 2 with a roll casing coated, for example, with a polymer. This polymer roll 2 is supported on its bearings arranged in bearings 10 and 11. The polymer roll 2 may be fixed axis or the axis may rotate with the roll shell. In the proximity of the polymer roll 2 »» «» jv 20, a guide roll 4 supported on the movable bearing brackets 12 and 13 is arranged in the axial direction parallel to the polymer roll * 2.

The movement of the bearing brackets 12 and 13 is such that the guide roll 4 can be moved at its ends «· ..,..., Substantially parallel to the plane passing through the axes of the polymer roll 2 and the guide roll 4. Around the sheaths of the polymer roll 2 and the guide roll 4 is a matched endless metal strap 6 which wraps the roll sheaths of the rolls 2 and 4; ··: included along the enclosed engaging web. The material used for the mycamine belt 6 is preferably steel.

»♦» »»> * "'· The belt calender 1 also includes a counter roll 3 arranged in contact with the polymer roll 2 <»> 30 to form a nip N. In this case, the so-called nip band forms: v between the endless metal belt 6 and the counter roll 3 3 when pressed

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against the metal belt 6 against the roll shell 2 of the polymer roll. The web of material 9 is passed through a nip zone N 110 1102 for calendering and forward, for example, through another nip (not shown) or for further processing.

The tension of the metal belt 6 is adjusted around the rollers 2 and 4 by means of a guide roll 4, in particular at the ends of the guide roll 4, preferably by means of tension adjusting means of the metal belt 6 located in the bearing brackets 12 and 13. As part of the tension adjusting means, here are provided similar hydraulic rollers 14 and 15, i.e. adjusting cylinders, located at the ends of the guide roller 4. Alternatively, pneumatic cylinders may be used. The first adjusting cylinder 14 exerts a force F i, which moves the first end of the guide roll 4 in the direction of the above-mentioned plane, on the movement bar 10 rather than on the bearing bracket 12. However, the roll shell of the guide roller 4 is tensioned by the force F1 against the metal belt 6, in particular against the first region 6a of the metal belt 6, causing the end edge 6a of the endless metal belt 6 to tighten to a force F., 15 a hydraulic pressure set via a pressure relief valve and further via a feed line 20a. Correspondingly, the second adjusting cylinder 15 exerts a force F2 on the movable bearing bracket 13 which tends to displace one end of the guide roll 4 in the direction mentioned above.

However, the roll shell of the guide roller 4 is tensioned by the force F2 against the metal belt 6, in particular against the proximal region of the second edge 6b of the metal belt 6, causing the end edge of the metal belt 6 to be tightened ·: ··; force F2 proportional to force f.,. Similarly, the desired tension is achieved by applying to the cylinder 15 a controlled hydraulic pressure through the pressure relief valve 25 of the hydraulic circuit 18b of the cylinder 15 and further through the supply line 20b. The hydraulic pressure can be adjusted here preferably in the range of about 0 to 20 bar, but may be varied as necessary.

A simplified example is given above of the edges 6a and .... of the metal belt 6; 30 6b or the setting of the tightening forces Γ, and f2. The setting of the tightening forces * · *. · Forces f, jaf2 can be accomplished in many different ways, for example, by supplying the control cylinders 14 and 15 with the desired hydraulic pressure via a pressure-compensated pump. The aforementioned tension adjusting means has provided a pre-adjusting of the tension of the edges 6a and 6b of the metal belt 6, whereby the forces acting on the adjusting cylinders 14 and 15 by the forces f1 and f2 remain substantially constant in the actual control operation of the metal belt 6.

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Although the tensions of the edges 6a and 6b are apparently the same, a small difference in tension may actually occur between them, as a result of which the metal belt 6 tends to slide axially of the rolls 2 and 4 towards the lower tension.

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Auxiliary adjusting means for adjusting the tension of the metal belt 6 are provided adjacent the first hydraulic cylinder 14. These include a hydraulic cylinder 16, i.e. auxiliary control cylinder 16, arranged alongside the first hydraulic cylinder 14 and regulating means 23, 24, 25 controlling the auxiliary control cylinder 16. and a corresponding force f3 of tensioning or loosening the first edge 6a of the metal belt 6, which is substantially parallel or opposite to that of the tensioning forces 20f and if2.

·: ··: In equilibrium situations, i.e. with the metal belt 6 in place, the pressures acting on the cylinders 14, ·: ·: 15 and 16 are set so that the forces f, f3 and f3 of the metal belt 1 are tightened together by the same the second edge 6b is tightened by a force f2. Specifically, this is preferably achieved by selecting similar adjusting cams 14 and 15.

The pressure proportional to the first desired tightening force is set to ·. · *]: About 3% -10% lower in the first control cylinder 14, most preferably »* · about 5% lower than the pressure in the second control cylinder 15 relative to the second desired tightening force f2. Thus, a tension difference corresponding to the pressure difference between the cylinders 14 and 15 is formed between the edges 6a and 6b of the metal belts 6.

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The auxiliary regulating cylinder 16 compensates for the difference in tension caused by the regulating cylinders 14 and 15 by applying a pressure proportional to the desired tightening force f3 on the auxiliary regulating cylinder 16. Thus, at equilibrium, the desired clamping force f3 is equal to the clamping force f1 and f2. First, the auxiliary control cylinder 16 is selected to be a cylinder in which, at the above equilibrium position, the pressure is substantially from about 40% to about 60% at its maximum, most preferably about 50% at its maximum. In this case, the pressure control range in the auxiliary control cylinder 16 comprises a portion for increasing the pressure from its equilibrium state and a portion for reducing the pressure from its equilibrium state for the actual control function of the metal belt 6, which will be explained below. Further, the auxiliary cylinder 16 is selected with a cylinder 16 having a pressure adjustment range for adjusting the tightening or loosening force f3, preferably about 5 to 15 times greater, most preferably about 10 times greater than the pressure adjusting range f3 for the tightening or loosening force f3. man to adjust f1, f2. This is accomplished by selecting a cylinder having a piston area smaller than the piston area of the adjustment cylinders 14 and 15. The surface area is preferably about 75% to 95% smaller. The auxiliary control cylinder 16 thus obtains a pressure change proportional to the change in force f3, which is a multiple of about 4 to 20 times that of the pressure change obtained for the control cylinders 14 and 15 20 to produce a corresponding force f3. Hereby: the adjustment of the force f3 is made much more precise by the auxiliary control cylinder 16 and: ·· - considerably more controllable than the control cylinders 14 and 15,: * ·: where the pressure adjustment range for the force corresponding to the force f3 is small.

The adjustment range is typically in the range of about 0 to 200 bar. The adjustment range can be adjusted as required.

For the actual control of the metal belt 6, the function of the auxiliary control cylinder 16 is to provide the necessary tension difference by which the metal belt 6 can be controlled in the axial direction of the rolls 2 and 4 in a controlled manner. For this control, ·: · *: 30 a position sensor 17 is provided in connection with the metal belt 6 to monitor the position of the metal belt 6. Here, the position sensor 17 preferably detects the axial position of the rolls 2 and 4 of the first edge 6a of the metal belt 6. The determined 8 110882 position information of the metal belt 6 is transmitted along the transmission path 22 from the position sensor 17 to the control unit 23, which enables the pressure valve 25 to be controlled by an external signal. In the control unit 23, the position information is formed to suit the control signal 5 of the pressure control valve 25 of the hydraulic circuit controlling the auxiliary cylinder 16. The control signal is supplied along the transmission path 24 from the control unit 23 to the valve 25, which is preferably a pressure proportional valve. The pressure proportional valve 25 opens and closes in accordance with the signal received from the control unit 23, controlling the pressure acting on the hydraulic circuit 21 and thus the auxiliary cylinder 16. The control signal here is an electrical signal, but the control signal may be some other, for example, hydraulic or pneumatic pressure signal. In this way, the force F3 on the bearing bracket 12 of the auxiliary cylinder 16, and thus the force f3 on the first edge 6a of the metal belt 6, can be adjusted as necessary to adjust the tension difference

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Figure 3A illustrates another embodiment of the invention. The parts shown in FIG. 3A having the same or similar purpose as those shown in FIGS. 1 and 2 of the first embodiment are designated by the same reference numerals. Here, the metal belt 6 is arranged to rotate about the roll 2 and the guide roll 4: v. 20 with the guide roll 4 arranged in such a position that the web material 9 is: ·. in contact with the metal belt 6 before the nip N formed by roll 2 and counter roll 3;

Fig. 3B shows a third embodiment of the invention. Here too, the guide roll 4 is arranged in a position where the web material 9 is in contact with the webbing 6 before the nip N. Here, the counter roll 3 is arranged at a distance from the roll 2, where the nip N is formed without the or may be in contact with the metal ·· '* strap 6 also after nip N.

30; * · *: A metal belt arranged to rotate around two or more rollers is used in a paper machine outside calendars. For example, the web material drying section schematically shown in FIG. 3 110882 currently uses two metal belts 6 and 7 between which web material 9 is fed and between which web material drying takes place. It is contemplated that the method and apparatus of the invention for guiding the metal belt in the axial direction of the rolls can be applied to such drying sections in which each belt 6 and 7 rotate about at least two rolls. Such an arrangement is schematically shown in Figure 3C. These guiding rollers include, for example, rolls designated by reference numerals 2a and 3a. The method and apparatus of the invention can also be used in presses.

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Claims (12)

A method for guiding an endless metal belt (6) in a paper or board machine (1) having one or more rollers (2) and at least one guide roller (4) or 5, around which the endless metal belt (6) is arranged to rotate, and having a counter roll (3) which presses the endless metal belt (6) against the roll (2) to form a nip zone (N) between the endless metal belt (6) and the counter roll (3) through which the web material (9) is passed, that: the endless metal belt (6) is guided in the axial direction of the rolls (2, 4) by adjusting the tension difference between the first edge (6a) and the second edge (6b) of the endless metal belt (6), for adjusting the tension difference between the edges (6a, 6b): applying a desired tightening force (f.,) to the first edge (6a) of the endless metal belt (6) by means of a first adjusting cylinder (14) disposed at the first end of the guide roll (4); applying a desired tightening force (f2) to one edge (6b) of the endless metal belt (6) by means of a second adjusting cylinder (15) disposed at one end of the guide roll (4); - providing a tensioning or loosening force (f3) on the first edge (6a) of the metal belt (6) provided on the first end of the guide roll. by means of a working cylinder (16) for adjusting the tension difference between the first edge (6a) and the second edge (6b); ·. - determining the position of the endless metal belt (6) in the axial: ··· direction of the rollers (3, 4, 5) by means of a position sensor (17); and that "··: - adjusting the tightening or loosening force (f3) formed by the auxiliary control cylinder (16) on the basis of the determined position information by means of adjusting means arranged on the auxiliary control cylinder (16). A method according to claim 1, characterized in that the control cylinders (14, 15) are hydraulic or pneumatic cylinders and that the auxiliary control cylinder (16) is a hydraulic or pneumatic cylinder. ':' *: 30 The method according to claim 1 or 2, characterized in that the pressure of the first metering cylinder (14) proportional to the first desired tightening force (f.,) Is preferably set at about 3% to 10%, most preferably at about 3% to 10%. 5% less than the pressure of the second control cylinder (15) proportional to the second desired tightening force (f2). Method according to Claim 3, characterized in that the pressure of the auxiliary regulating cylinder (16) proportional to the tensioning or loosening force (f3) in the lumbar is set so that the tensioning or loosening force (f3) compensates for the pressure difference of the adjusting cylinders (14,15) the tension adjustment cylinder 10 between the first edge (6a) and the second edge (6b) of the metal belt (6) preferably having a pressure of about 40% to about 60% of its maximum, most preferably about 50% of its maximum. Method according to one of the preceding claims 1 to 4, characterized in that an auxiliary control cylinder (16) is selected whose pressure adjustment area 15 for adjusting the tightening or loosening force (f3) is preferably about 4 to 20 times larger, most preferably about 10 times larger than (14, 15) a pressure adjustment range for adjusting the force (fi, f2) corresponding to the tightening or loosening force (f3). : · 20 Applying the method according to any one of the preceding claims: a device for guiding an endless metal belt (6) in a paper or board machine (1) having one or more rollers (2) and at least one guide roller (4) or the like; around which the endless metal belt (6) is arranged to rotate and having a counter roll (3) with which the endless metal belt (6) can be pressed against the roll (2) to form an endless metal belt (6) and a counter roll (3) nip zone, (N) through which the web material (9) can be passed, characterized in that: for guiding the endless metal belt (6) in the axial direction of the rolls (2, 3, 4), the first edge (6a) of the endless metal belt (6); and the second edge (6b) is arranged to be adjustable by adjusting the tension difference of the edges (6a, 6b). Connected to the first end of the V: guiding roller (4) or the like: · a first adjusting cylinder (14) capable of applying a desired tightening force (f ^;) to the first edge (6a) of the endless metal belt. a second adjusting cylinder (15) disposed at the second end (6b) of the endless metal belt (6) is provided at the second end of the guide roll (4) or the corresponding first end; auxiliary adjusting cylinder (16) for applying to the first edge (6a) of the metal belt (6) a force (f3) to tighten or loosen the first edge (6a), - a position sensor (17) is provided in connection with the metal belt (6); the position in the axial direction of the rollers (2, 3, 4) is adjustable, and that adjusting means (23, 24, 25) are provided in connection with the auxiliary control cylinder (16) the tightening or loosening force (f3) produced by the cylinder (16) is adjustable based on the determined position information. Device according to Claim 6, characterized in that the control cylinders (14, 15 15) are hydraulic or pneumatic cylinders and that the auxiliary control cylinder (16) is a hydraulic or pneumatic cylinder. Device according to claim 6 or 7, characterized in that the first adjusting force (f,) is proportional to the first adjusting force (f,) of the first adjustment cylinder • I: ·. The pressure of 20 (14) is preferably set to be about 3% to 10% lower, most preferably about 5% lower than the pressure of the second control cylinder (15) proportional to the second desired tightening force (f2). • · Apparatus according to any one of claims 6 to 8, characterized in that, at equilibrium, the pressure of the auxiliary control cylinder (16) relative to the tightening or loosening force (f3) is set such that the tightening or: Y: loosening force ( f3) compensates for the difference in tension between the first edge (6a) and the second edge (6b) of the metal belt (6), which is proportional to the pressure difference of the adjusting cylinders (14, 15), preferably with a pressure adjusting cylinder (16) of about 40% to 60% , most preferably about 50% of its maximum Apparatus according to any one of claims 6 to 9, characterized in that the pressure adjustment range of the auxiliary control cylinder (16) for adjusting the tightening or loosening force (f3) is preferably about 4 to 20 times larger, most preferably about 10 times larger than the control cylinders (14, 15). ) a pressure adjustment region for adjusting the force (f. ,, f2) corresponding to the tightening or loosening force (f3). 10 110882 Device according to one of the preceding claims 6 to 10, characterized in that the control means comprise a pressure valve, preferably a pressure proportional valve (25), which is controllable by a control message based on the determined position information received from the position sensor (16). Use of the device according to claim 6, characterized in that the device is used in a belt calender or in a press or a drying device. • * • * · »» »i»> · · i4 110882