EP0888993A1 - Method of and device for compensating the tension forces over the width of a running web - Google Patents

Abstract

The paper or foil length (3) moves over rollers (4-6), one of which is a pivoted tension compensation roller (5). A torque applied by the length to one of the rollers is measured and regulated to a set reference value by active pivoting of the compensation roller. The torque is measured by measuring both bearing forces (F) of one roller, preferably the compensation roller, and calculating the difference. The device has adjusting drives engaging on the shaft ends (9) of the tension compensation roller. The drives are in active connection with a regulator unit, which is influenced by the torque in the paper length.

Description

The invention relates to a method and a device for compensating clamping forces across the width of a running web according to that in the preambles of the claims 1 and 6 Art.

A device consisting of a shaft is known from US Pat. No. 2,066,306 a roller is freely rotatable. The shaft is in sets at both ends guided and gripped by a lever linkage. This prevents a like-minded Movement of both shaft ends, so that the shaft and with it the roller only around an axis is pivotally held. However, this known device has the Disadvantage that both in the scenes and in the lever linkage when pivoting the shaft moves smoothly. The associated frictional forces limit the accuracy of what can be achieved by this device Voltage equalization. In particular, voltage compensation is not possible if the tension difference between both sides of the web is less than the considerable Stiction is in the scenes and lever arm.

DE 39 20 310 A1 discloses a material tension meter and one constructed with it Material tension regulator known. The material tension meter determines the mean tension of the web by a control device by translatory Adjusting a roller to a predetermined setpoint is regulated. This well-known Material tension controller is therefore not able to differentiate Detect or compensate tension forces across the width of a running web.

The invention has for its object a method and an apparatus to create the type mentioned, which a precise clamping force compensation on the Guaranteed width of the web.

This object is achieved with the method steps of the claim 1 and solved with the features of claim 6.

In this method, a signal is detected which is from the web to the tension compensation roller exerted torque is proportional. This signal will used as a correction signal for regulation. With this scheme, through Swiveling the tension compensation roller that exercised by the web Torque regulated to the setpoint zero. This ensures that the clamping forces both web halves are the same in the steady state of the control. There the regulation of the tension compensation roller is active, play the effects of friction, as well as the inertia of the tension compensation roller only a subordinate role for clamping force compensation. They only limit the speed at which a clamping force difference is corrected. The precision of the clamping force compensation is based solely on the precision of the detection of the torque exerted by the web on the tension compensation roller and the Quality of the controller determined.

According to claim 2, it is advantageous to determine the torque, the bearing forces measure one of the rollers and calculate their difference. The difference in Bearing forces of both ends of a roller are proportional to when the web runs in the middle Torque that the web exerts on the roller. Leave the roller's bearing forces is particularly simple and precise due to the force measuring devices provided in the bearings determine. The bearing forces on the tension compensation roller are preferred determined. This ensures that the tension of the web is correct and is unaffected by the influence of friction of other rollers. Also be in this way time delays between the pivoting of the tension compensation roller and the impact on the tension of the web to a minimum limited. The regulation can therefore an occurring clamping force difference Compensate for the web faster.

A swiveling of the tension compensation roller by means of actuators in accordance with Claim 3 offers the advantage that its inertia can be easily overcome can.

According to claim 4, it is advantageous to additionally detect the position of the center of the web and to correct the bearing force difference. From the difference in the bearing forces of the roller only a torque related to the center of the roller can be determined. With off-center However, the course of the path must deviate from this, to the center of the railway related torque can be corrected. This is ensured by the fact that the web-related deviation of the difference in bearing forces is calculated and the determined bearing force difference is corrected by this value.

According to claim 5, it is advantageous that from the web to the tension compensation roller compare applied torque to a range. Dependent on The position of the tension compensation roller becomes from the comparison result either regulated and thus actively adjusted or kept freely pivoting. A free Swiveling holding has the particular advantage that the voltage balance between two halves of the track are particularly accurate and independent of the accuracy of the Force measurement takes place. Only if there are large deviations between the setpoint and actual value the position of the tension compensation roller is regulated and thus actively adjusted. This ensures that there is a large difference in tension between the two web halves is corrected very quickly because the actuators for pivoting the tension compensation roller can apply much more power than the web itself. This is especially with large rollers that have a correspondingly large moment of inertia, important. To ensure effective power transmission through the regulation on the To ensure tension compensation roller, the pivot bearing of the tension compensation roller blocked in this case.

The device according to claim 6 has a pivotally held tension compensation roller on. This is freely rotatable on a shaft, the ends of which are in a pivot bearing are supported. This ensures that the space around the Tension compensation roller is free, so that the running of the web is not disturbed in any way is. The pivot bearing of the shaft is preferably by the tension compensating roller on both sides provided toothed gear realized. This swivel bearing ensures that the tension compensation roller is only pivoted about an axis is and cannot be moved as a whole. This in turn causes if the total tension of the web varies, the tension compensation roller does not of their end stops. The tension compensation across the width of the web is therefore ensured under all operating conditions. The application of toothed gears for pivotably holding the shaft results in particularly low frictional forces, since the teeth of the toothed gears are rolling against each other without touching each other to slide. The shaft ends are preferably supported by roller bearings, that roll on scenes. This way, starting from the scenes Frictional forces largely suppressed. The one for pivoting the tension compensation roller Required force is therefore very low, so that the tension compensation the train can be done quickly. The desired clamping force compensation is therefore achieved particularly inexpensively with the simplest of means. In addition, the Build the device very compact, so that even existing systems by simple Replacing a roller can be converted without problems. The tension compensation roller is pivoted by actuators by a control device can be controlled. The control device receives the torque as the actual value the web exerts on one of the rollers. This value is set by the control device regulates the setpoint zero, so that in the steady state of the control device the tension forces of the web are equal to each other in both web halves.

According to claim 7, it is favorable to the torque of the web by means of force measuring devices to measure, which are provided in the bearings of a roller. The measured Force values are subtracted from each other via a subtractor, its initial value that exerted by the web on the tension compensation roller Torque is proportional. This value is set by the control device Setpoint zero regulated.

According to claim 8, it is advantageous in the case of off-center web running, the position of the web edges by means of an edge sensor and this value with the measured bearing forces to link. This allows the web force-related bearing force difference to be calculated and correct so that a signal is fed to the controller which is to open the path center related torque is proportional to the path.

If two independently acting actuators are used, these are required to synchronize with each other in opposite directions. This can be done very easily according to claim 9 can be achieved in that the two displacement sensors the adjustment paths of both Detect shaft ends. The average of the adjustment paths is determined by the control device regulated to a target value so that the middle position of the tension compensation roller is kept constant.

According to claim 10, it is advantageous that from the web to the tension compensation roller exerted torque by a window comparator with a Compare area. Depending on the comparison result, the location of the Tension compensation roller either regulated and thus actively adjusted or freely held pivotable. A freely pivoting holding has the particular advantage that the tension compensation between the two web halves is particularly precise and independent on the accuracy of the force measurement. Only with large deviations The tension compensation roller is positioned between the setpoint and the actual value regulated and thus actively adjusted. This ensures that there is a large difference in clamping force between the two halves of the web is corrected very quickly because the actuators for Swiveling the tension compensation roller apply considerably more force can than the web itself. This is especially true with large rolls that have a corresponding have a large moment of inertia, important. For effective power transmission through the regulation to ensure the tension compensation roller in this case the pivot bearing of the tension compensation roller is blocked.

If the actuators are connected with threaded spindles or screws according to claim 11, this results in a particularly powerful reduction of the actuators. The Swiveling the tension compensation roller is particularly easy. To be a free one To prevent pivoting of the tension compensation roller under the pressure of the web, the shaft is blocked against rotation about its longitudinal axis. Preferably a releasable braking device is used for this. Because the gear directly meshes with the rack, friction losses of the swivel bearing are minimized. To minimize the frictional forces between the gear and the rack it is favorable to equip them with involute or cycloid teeth.

A preferred example of the method according to the invention is shown in the drawing and preferred embodiments of the subject matter of the invention by way of example described without restricting the scope of protection.

Figur 1

eine perspektivische Darstellung einer Vorrichtung zum Ausgleich von Spannkräften einer Bahn,

Figur 2

eine perspektivische Darstellung einer Seite einer Schwenklagerung,

Figur 3

die Schwenklagerung gemäß Figur 2 ohne Zahnrad,

Figur 4

eine Schnittdarstellung einer alternativen Ausführungsform einer Seite eines Schwenklagers mit verschobener Schwenkachse und

Figur 5

eine alternative Ausführungsform einer Vorrichtung zum Ausgleich von Spannkräften einer Bahn.

It shows:

Figure 1

1 shows a perspective view of a device for compensating tension forces of a web,

Figure 2

a perspective view of one side of a pivot bearing,

Figure 3

the pivot bearing according to Figure 2 without gear,

Figure 4

a sectional view of an alternative embodiment of a side of a pivot bearing with shifted pivot axis and

Figure 5

an alternative embodiment of a device for compensating tension forces of a web.

Figure 1 shows a device 1 for compensating clamping forces across the width a path 3 running in the direction of arrow 2. This path 3 is on in bearings 12 held rollers 4, 5, 6 deflected, the middle roller 5 as a tension compensation roller is formed, which is acted upon by the web 3 with a force F. The tension compensation roller 5 is freely rotatably mounted on a shaft 7 around a pivot axis 8 extending through its center of gravity S is pivotably held is. Both ends 9 of the shaft 7 are supported in bearings 10, which are on a frame 11 are held and together form a pivot bearing for the shaft 7.

The structure and the function of the bearing 10 will be explained in more detail with reference to FIGS described. Figure 2 shows the bearing 10 consisting of a housing block 15, the Cover is removed. In the housing block 15 there is a stationary one or drivable threaded spindle 16. This meshes with a gear 17, the Tooth 18 is only indicated. The gear 17 is non-rotatably connected to the while 7.

On the threaded spindle 16, an actuator, not shown, acts on the rotary movement thereof is transmitted to the gear 17 and the shaft 7. In the opposite 9 provided bearing 10, the shaft 7 is a mirror image of the representation according to FIG. 2 held. The movements of the ends 9 of the shaft 7 are therefore opposite to each other synchronized so that the shaft 7 and thus the tension compensation roller 5th can only be pivoted about the pivot axis 8 indicated in FIG.

FIG. 3 shows the bearing 10 according to FIG. 2, the gear wheel 17 with the shaft 7 removed to see the parts underneath. In the housing block 15 are defined at a distance e two columns 20, the guide for the shaft 7 form. For this purpose, the shaft 7 carries a roller bearing 21, which alone with its receiving opening 22 for receiving the shaft 7 is shown. The roller bearing 21 is running between the columns 20, the distance e from each other slightly larger than the outer diameter D of the rolling bearing. It is thereby achieved that the rolling bearing 21st only rests on one of the two columns 20 and rolls on it without sliding. The Link guide causes the shaft 7 to move only within one plane ε can. This ensures that the axis 23 of the shaft 7 is always off the threaded spindle 16 is equally spaced so that the toothing 19 of the threaded spindle 16th and the gear 17 engage correctly with each other. This is important so that the Roll teeth of the gear 17 on those of the threaded spindle 16 without sliding.

In the housing block 15 21 through holes in the plane of movement of the rolling bearing 24 provided in which stops, not shown, for bilateral limitation the travel of the shaft 7 are provided. In addition, one of the Through bores 24 a shock absorber can be provided, the vibration movements dampens 7 while.

An alternative embodiment of the bearing 10 is shown in FIG. It exists from the housing block 15, on which a cover 30 is fixed. The cover 30 has an opening 31 penetrated by the shaft 7 on the shaft 7 is by means of Rolling bearing 21 is supported on the columns 20 and rotatably connected to the gear 17. The gear 17 meshes with an intermediate gear 32, the shaft 33 via further roller bearing 34 is also supported on the columns 20. The waves 7, 33 are Supported via roller bearings 35 on a cage 36, the mutual distance M between the shaft axis 23 and the shaft axis 37 keeps constant. The two Rolling bearings 21, 34 allow the cage 36 to move up and down in the direction force F. However, they prevent sideways movement and swiveling of the cage 36. In order to hold the shaft 33 in position in the longitudinal direction, is in the cover 30 a stop 38 is provided which presses against the shaft 33. Preferably, the Ball 39 held resiliently. The stop 38 limits the movement of the cage 36 Although only in one direction, there is another one at the opposite end 9 of the while 7 Bearing 10 provided diagonally opposite bearing, the movement of there provided cage 36 limited in the opposite direction. Since both cages 36 with the Shaft 7 are connected, is a movement of the shaft 7 in the direction of its longitudinal axis 23 excluded.

Tangential to the jacket 40 of the tension compensation roller about the pivot axis 8 5, where the web 3 touches the leveling roller 5 is an intermediate gear 32 meshing with the threaded spindle 16 and the gear 17 provided, the Axis 37 is aligned with the jacket 40. The gears 17, 32 are in their diameter dimensioned accordingly.

Around the tension compensation roller 5 through active regulation by means of actuators to be able to pivot, penetrates the threaded spindle 16 at its lower end the housing block 15. In this way, the threaded spindle 16 can be operated with an actuator, for example, an electric motor or a hydraulic motor that will set them in rotation. This rotation of the threaded spindle 16 is about the gears 32 and 17 transmitted to the shaft 7. That at the opposite end 9 of the shaft 7 located bearing 10 then also has an actuator. Both actuators are coupled in opposite directions so that a bearing 10 an upward movement of the shaft end 9 and the opposite bearing 10 a downward movement of the shaft end 9 causes. So that the rotation of the threaded spindle 16 in an adjustment of the cage 36 is implemented and does not merely cause the shaft 7 to twist a braking device 41 is provided on the slide 36. It acts against wave 7 and prevents their rotation relative to the cage 36 in the tightened position. In released position, the braking device 41 is spaced from the shaft 7, so that the tension compensation roller 5 can pivot freely.

FIG. 5 shows an embodiment of the device 1 with active adjustment of the Tension compensation roller 5. The basic structure corresponds to the device 1 according to Figure 1, wherein the shaft 7 against rotation about its longitudinal axis 23 can be blocked by means of a braking device. The threaded spindles 16 of the bearings 10 are connected to actuators 50. These can be electric motors, for example with a flange-mounted gearbox or hydraulic motors. Move the actuators 50 the threaded spindles 16 in rotation and thus cause a height adjustment the ends 9 of the shaft 7. The actuators 50 are with displacement sensors 51 in Active connection that detect the adjustment path of the threaded spindle 16. Because the rotary motion the threaded spindle 16 is coupled to the shaft 7 via the toothed wheel 17, the signal obtained by the displacement sensor 51 is also proportional to the adjustment path of the End 9 of the shaft 7. Between the bearings 10 and the frame 11 are force measuring devices 52 provided by the of the tension compensating roller 5 and Track 3 applied bearing forces F. At both edges 53 are permanent Detection of the web position edge sensor 54 provided.

The actuators 50, the displacement sensors 51, the edge measuring devices 52 and the edge sensors 54 are operatively connected to a control device 55. This control device 55 has the task of adjusting differences in tension in both web halves by adjusting to compensate for the tension compensation roller 5. A totalizer 56 is on the input side in operative connection with the force measuring devices 52 and calculates the Difference of the measured bearing forces, which is proportional to that of the web 3 on the Tension compensation roller 5 is exerted torque. The output signal of the Totalizer 56 is fed to a controller 58 via a further totalizer 57, which preferably has a P, PI or PID behavior. The one obtained from controller 58 Correction signal is a non-inverting input 59 and a inverting input 60 supplied by summers 61, 62, which are not shown Power amplifiers are operatively connected to the actuators 50. By This control loop is used when there is a difference in bearing force between the ends 9 of the shaft 7 causes an opposite height adjustment of the shaft 7, so this panned.

In order to keep the position of the pivot axis 8 of the shaft 7 constant, the mean value is also used the adjustment paths from the ends 9 of the tension compensation roller 5 regulated. For this purpose, the displacement sensors 51 are connected to a further summer 63, the Output signal proportional to the mean of the adjustment paths of both ends 9 of the shaft 7 is. This signal is set to a constant setpoint in a further controller 64 regulated. The controller 64 also preferably has a P, PI or PID behavior.

The correction signal obtained from the controller 64 reaches non-inverting inputs 65, 66 of the summers 61, 62 and therefore causes an adjustment in the same direction both ends 9 of the shaft 7. The middle position of the Tension compensation roller 5 and thus the position of its pivot axis 8 recorded.

The above-described control loops presuppose that the web 3 runs centrally over the tension compensation roller 5, so that, in the case of the same tension forces in both web halves, both bearing forces F are equal and the difference is zero. Should the web 3 exceptionally run eccentrically over the tension compensation roller 5, then this eccentric run causes a torque and thus different bearing forces F at both ends 9 even with balanced tensioning forces of both web halves Correction device 67 is provided. This has a circuit block 68 which is operatively connected to the edge sensors 54 on the input side. Circuit block 68 calculates the expression from the signals obtained from edge sensors 54 f = 2 L ( a - b ) + b 2nd - a 2nd L ( L - a - b ) , where a , b corresponds to the horizontal distances of the web edges 53 from the force measuring devices 52 and L to the distance between the two force measuring devices 52.

The signal f calculated by the circuit block 68 is also multiplied in a multiplier 69 a signal multiplied by the total of the web 3 on the tension compensation roller 5 corresponds to the force exerted. This signal is from a summer 70 won, the input side with the force measuring devices 52 in operative connection stands. The summer 70 is connected via an inverting input 71 connected to a coefficient element 72, by means of which the weight of the tension compensation roller 5 from those measured by the force measuring devices 52 Values is subtracted. The multiplier 69 calculates that difference in force between the two Ends of the shaft 7, which is caused by the off-center web run. This Value is fed to an inverting input 73 of the summer 57, so that on Output 74 of the summer 57 is proportional to the tension difference between the two web halves Signal pending.

A window comparator 75 is connected to the output 74 of the summer 57 and compares the control deviation with two fixed limit values. At a digital output 76 of the window comparator 75 is at a zero level when the control deviation is within the range between the limits. The digital output 76 is operatively connected to a hold input 77 of the controller 58, which is in the Inactive in the event of a zero level. This is important so that integrators in controller 58 do not accept undefined output values. Output 76 is also available a braking device of the bearing 10 in operative connection, which is pending at one level the time 7 blocked against rotation about its longitudinal axis, so that the actuators 50 can adjust the tension compensation roller 5. Through this Special arrangement is achieved that in the event of a large control deviation Shaft 7 is blocked, and the actuators 50 via the threaded spindles 16 Actively adjust the tension compensation roller 5. This adjustment takes place very quickly, since the actuators 50 exert relatively large forces on the tension compensation roller 5 can. Are the tension forces of both halves of the web almost balanced, that is Control deviation at the output 74 within that determined by the window comparator 75 Range, the controller 58 is switched off via the hold input 77 and the Blocking of shaft 7 released. So that the tension compensation roller 5 again swivels freely and sets itself automatically under the action of the tension of the web 3 a.

The control device 55 can be implemented by analog or digital arithmetic circuits become. In particular, implementation using a microcomputer is advantageous because in this case additional functions and changes to the control algorithms can be easily taken into account by adapting the program.

Reference list

1

contraption

2nd

Web direction

3rd

train

4th

roller

5

Tension compensation roller

6

roller

7

wave

8th

Swivel axis

9

The End

10th

camp

11

frame

12th

camp

15

Housing block

16

Threaded spindle

17th

gear

18th

Gearing

19th

Direction of rotation

20th

pillar

21

roller bearing

22

opening

23

axis

24th

Through hole

30th

cover

31

opening

32

Idler gear

33

wave

34, 35

roller bearing

36

Cage

37

axis

38

attack

39

Bullet

40

Lateral surface

41

Braking device

50

Actuator

51

Displacement sensor

52

Force measuring device

53

Web edge

54

Edge sensor

55

Control device

56, 57

Totalizer

58

Regulator

59

non-inverting input

60

inverting input

61, 62, 63

Totalizer

64

Regulator

65, 66

non-inverting input

67

Correction device

68

Circuit block

69

Multiplier

70

Totalizer

71

inverting input

72

Coefficient term

73

inverting input

74

exit

75

Window comparator

76

Digital output

77

Stop entrance

a, b

Distance of the web edge from the force measuring devices

D

outer diameter

e

Distance of the columns

F

force

L

distance

S

main emphasis

ε

level

Claims (11)

Method for compensating tension forces across the width of a web (3), preferably a paper or film web, which is pulled over rollers (4, 5, 6), in which a tension-compensating roller (5) deflecting the web (3) by approximately is pivoted perpendicular to it, characterized in that a torque exerted by the web (3) on one of the rollers (4, 5, 6) is detected and by actively pivoting the tension compensating roller (5) to a desired value is regulated. Method according to claim 1, characterized in that the torque of the web (3) is determined by measuring both bearing forces (F) of one of the rollers (4, 5, 6), preferably the tension compensation roller (5), and calculating their difference . Method according to Claim 1 or 2, characterized in that the control acts on actuators (50) acting on both roller ends (9). Method according to at least one of Claims 1 to 4, characterized in that the position of the web (3) is detected by sensing its edge edges (53) and the determined torque of the web (3) is corrected by the deviation caused by the web run. Method according to at least one of Claims 1 to 5, characterized in that the torque exerted by the web (3) on the tension compensation roller (5) is compared with a range lying between two limit values, the tension compensation roller (5) being used Torques are kept freely pivotable within the range and their position is otherwise regulated. Device for compensating tensioning forces across the width of a web (3) drawn over rollers (4, 5, 6), preferably a paper or film web with a freely rotatable web (3) that deflects the web (3), on one about its longitudinal axis (23) rotatable shaft (7) mounted tension compensation roller (5), the shaft (7) being supported in a pivot bearing (10) which is held in a frame (11), and the shaft (7) on both sides of the tension compensation roller ( 5) the movement of its two ends is held in opposite directions and is guided in scenes (20), characterized in that actuators (50) pivoting on the shaft ends (9) act on the tension compensating roller (5), which actuators (50) act on a control device (55). are in operative connection, which is influenced by the torque of the web (3) Apparatus according to claim 6, characterized in that the control device (55) is operatively connected to force measuring devices (52) which are provided on the bearings (12) of one of the rollers (4, 5, 6), preferably the tension compensation roller (5) are. Apparatus according to claim 6 or 7, characterized in that the control device (55) is influenced by at least one edge sensor (54) which detects the position of the web edge (53). Device according to at least one of claims 6 to 8, characterized in that an actuator (50) acts on each of the two shaft ends (9), and the control device (55) is operatively connected to the position sensors (51) detecting the position of both shaft ends (9) stands that the two actuators (50) are coupled in opposite directions. Device according to at least one of claims 6 to 9, characterized in that the force measuring devices (52) with a window comparator (75) comparing the torque exerted by the web (3) on the tension compensating roller (5) with a range lying between two limit values are in operative connection, the tension compensating roller (5) being freely pivotable within the range at torques and the position of the actuators (50) being regulated otherwise. Device according to at least one of claims 6 to 10, characterized in that the actuator (50) is operatively connected to a threaded spindle (16) or a worm which meshes with a gear (17) connected to the shaft (7) in a manner fixed against relative rotation.

Images