EP0722899B1 - Method and device for compensating the tension forces over the width of a running web - Google Patents

Description

The invention relates to a device for compensating clamping forces on the Width of a running web according to that mentioned in the preamble of claim 1 Art.

Such a device is known from US Pat. No. 2,066,306 A. It consists of one Roller that is freely rotatable on a shaft. The shaft is at both ends guided in scenes and gripped by a lever linkage. This prevents one movement in the same direction of both shaft ends, so that the shaft and with it the roller is held pivotable only about an axis. However, this known device has the disadvantage that both in the scenes and in the lever linkage Swiveling the shaft sliding movements take place. The related Frictional forces limit the accuracy of what can be achieved with 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 There is hate friction in the scenes and lever arm.

The invention has for its object a device of the aforementioned To create a type that ensures precise compensation of tension across the width of the web, without hindering the web.

This object is achieved with the features of claim 1.

The device according to claim 1 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 supported by the tension compensation roller on both sides provided toothed gear realized. Practice the web on the tension compensation roller torque off, this tries the tension compensation roller on the side of the higher clamping force in the direction of force. The toothed gear sets this movement of the tension compensation roller in one Rotation of the shaft around. This is in turn from the opposite gear in an opposite adjustment movement of the opposite end of the Wave implemented. This mechanism ensures that the tension balancing roller is only pivoted about an axis and not shifted overall can be. This in turn causes that with varying total clamping force the tension compensating roller does not reach any of its end stops. Of the Tension compensation across the width of the web is therefore among all occurring Operating conditions ensured. The application of toothed gears for Swiveling holding the shaft results in particularly low frictional forces since the teeth the toothed gear gripping each other without sliding against each other. The The shaft ends are supported in the scenes via roller bearings, which are located on the scenes pass on. In this way, frictional forces emanating from the scenes largely suppressed. The one for pivoting the tension compensation roller The force required is therefore very low, so that the tension compensation of the web even without active adjustment of the tension compensation roller solely by that of the Railway transmitted torque can take place. The desired clamping force compensation is therefore achieved particularly inexpensively with the simplest of means. Also lets the device build very compact, so that existing systems through simple replacement of a roller can be converted without problems.

According to claim 2, ball or roller bearings have proven themselves as rolling bearings. This have very favorable running properties, especially those for an exact Tension compensation harmful friction force is negligible. That ball or Roller bearing is only on one side of a rail or column as a counter bearing and rolls on it. This counter bearing limits the freedom of movement of the tension compensation roller on one level. This prevents pivoting of the Tension compensation roller around a perpendicular to the desired swivel axis Axis that would result in a lateral path. In addition, the counter bearing a correct position of the parts of the toothed gear, so that its teeth always interlock correctly.

According to claim 3, it is advantageous to the rack and pinion one To form gear. Preferably the gear meshes directly with the rack, which minimizes the friction losses of the swivel bearing. Since the rack is fixed, the gear must turn on when adjusting the tension compensation roller roll this, whereby the gear is rotated together with the shaft. Preferably the racks are on both ends of the shaft at diagonally opposite Provided sides of the shaft axis. This causes the adjustment of the Shaft ends are synchronized in opposite directions to each other. The tension compensation roller can therefore only be pivoted about a fixed, predetermined pivot axis, the gear meshing with the rack through the center of gravity of the tension compensation roller runs. Alternatively, the racks could be the same Side of the shaft axis can be provided. In this case one of the toothed gears would have to have an intermediate gear that reverses the rotational movement of this side. To minimize the frictional forces between the gear and the rack it is convenient to equip them with involute or cycloid teeth.

According to claim 4, it is favorable to have an intermediate gear between the rack and the shaft to provide. This allows the pivot axis of the Relocate the tension compensation roller as required. The height of this pivot axis in relation The tension compensation roller is through the axes of the rack intermeshing intermediate gears set.

In printing machines in particular, it is desirable that the center line of the web undergoes no change in length due to the tension compensation roller. this will achieved according to claim 5 in that the pivot axis of the tension compensation roller is shifted to her coat. The pivot axis affects the Tension compensation roller in the area in which it is wrapped in the web side and length registers remain unaffected.

If the rack is designed as a threaded spindle or worm, So the tension compensation roller can be easily turned by turning the threaded spindle or adjust the screw in its altitude.

If the threaded spindles or screws are connected to actuators according to claim 7, so the pivoting of the tension compensation roller can be actively by the Actuators take place. For free pivoting of the tension compensation roller To prevent under the pressure of the track, the shaft is against twisting blocked around its longitudinal axis. The pivoting of the tension compensation roller by means of actuators offers the advantage that their inertia is overcome more easily can be as if the train itself had to exert the power.

According to claim 8, it is favorable to connect the actuators to a control device. The control device receives its actual value from force measuring devices which are in the bearings of a roller are provided. The measured force values are over subtracted from each other, the output value of which from the web torque exerted on the tension compensation roller is proportional. This Value is regulated by the control device to the setpoint zero, so that in the steady state State of the control device the tension forces of the web in both Web halves are equal to each other. Because the pivoting of the tension compensation roller actively done through the regulation, play frictional influences, as well the inertia of the tension compensation roller for tension compensation only a subordinate role. They only limit the speed at which one Clamping force difference is corrected. The accuracy of the clamping force compensation is exclusively from the precision of the detection of the web on the tension compensation roller exerted torque and the quality of the controller. For Determining the torque, the bearing forces of one of the rollers are measured and their difference calculated. The difference in the bearing forces of both ends of a roller is with a central web run, proportional to the torque that the web has on the roller exercises. The roller's bearing forces can be particularly easily and precisely adjusted by in determine the force measuring devices provided in the bearings. Preferably the Bearing forces determined on the tension compensation roller. This ensures that the The tension of the web is correctly unaffected by the friction of other rollers is detected. It also eliminates time delays between the pivoting of the tension compensation roller and the effect on it Tension of the web is reduced to a minimum. The scheme can therefore Compensate any tension difference of the web faster.

In the case of an off-center web run, it is advantageous according to claim 9, the location of both web edges using an edge sensor and this value with the link measured bearing forces. This makes it possible to determine the bearing force difference caused by the web run calculate and correct so that a signal is fed to the controller which is proportional to the torque of the web related to the center of the web.

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.

Preferred embodiments of the subject matter of the invention are shown in the drawing described by way of example 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 Vorrichtung zum Ausgleich von Spannkräften einer Bahn mit aktiver Regelung.

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

a device for compensating tension forces of a web with active control.

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 trained. The tension compensation roller 5 is freely rotatable a shaft 7 mounted about a pivot axis extending through its center of gravity S. 8 is pivotally held. Both ends 9 of the shaft 7 are supported in bearings 10, which are held on a frame 11 and together a pivot bearing for the Form wave 7.

The structure and the function of the bearing 10 will be explained in more detail with reference to FIGS. 2 and 3 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 Threaded spindle 16. This meshes with a gear 17, the teeth 18 only is indicated. The gear 17 is connected to the shaft 7 in a rotationally fixed manner.

In practice, the web 3 presses the shaft 7 with a force F and tries to drive it to move in that direction. Since the gear 17 with the threaded spindle 16 combs, it must roll on this displacement on the threaded spindle 16, so that it is simultaneously rotated in direction 19. In the provided at the opposite end 9 Bearing 10, the shaft 7 is held in mirror image to the representation according to Figure 2. This causes the described rotation 19 of the gear 17 and thus the shaft 7 at its opposite end 9 is a displacement directed against the force F. causes. 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 voltage compensation roller 5 only is pivotable 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 and only with its Receiving opening 22 is shown. The roller bearing 21 runs between the columns 20, whose distance e from each other is slightly larger than the outer diameter D of Rolling bearing is. This ensures that the roller bearing 21 only on one of the two Columns 20 abuts and rolls on it without sliding. The backdrop guide causes that the shaft 7 can only move within one plane ε. This ensures that the axis 23 of the shaft 7 is always equally spaced from the threaded spindle 16 is, so that the teeth 19 of the threaded spindle 16 and the gear 17 engage correctly. This is important so that the teeth of the gear 17 roll on 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 the shaft 7.

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. 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 only in one direction, but at the opposite end 9 of the shaft 7 there is another 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 also by active regulation by means of actuators to be able to pivot, penetrates the threaded spindle 16 on its lower End the housing block 15. In this way, the threaded spindle 16 with a Actuator, for example an electric motor or a hydraulic motor, connected that will set them in rotation. This rotation of the threaded spindle 16 will transmitted to the shaft 7 via the gears 32 and 17. 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 carriage 36. It works against them Shaft 7 and prevents its rotation relative to the cage in the tightened position 36. In the 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 alternative embodiment of the device 1 with active adjustment 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 is blocked. The threaded spindles 16 of the bearings 10 are with actuators 50 connected. These can, for example, be flanged electric motors Gearboxes or hydraulic motors. The actuators 50 offset the threaded spindles 16 in rotation and thus cause a height adjustment of the ends 9 of the shaft 7. The actuators 50 are in operative connection with displacement sensors 51 which detect the adjustment path of the threaded spindle 16. Because the rotation of the threaded spindle 16 is coupled via the gear 17 to the shaft 7, that is from the displacement sensor 51 signal obtained is also proportional to the displacement of the end 9 of the shaft 7. Force measuring devices 52 are provided between the bearings 10 and the frame 11, those exerted by the tension compensation roller 5 and the web 3 Record bearing forces F. At both web edges 53 are for continuous detection Path position edge sensor 54 is 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. Constantly about the position of the pivot axis 8 of the shaft 7 hold, the average of the adjustment paths from the ends 9 of the tension compensation roller 5 regulated. For this purpose, the displacement sensors 51 are equipped with a further summer 63 connected, whose output signal is the average of the adjustment paths of both Ends 9 of the shaft 7 is proportional. This signal is in a further controller 64 regulated to a constant setpoint. The controller 64 also preferably has a P-, PI or PID behavior. The correction signal obtained from controller 64 arrives non-inverting inputs 65, 66 of the summers 61, 62 and therefore causes one Adjustment of both ends 9 of the shaft 7 in the same direction the middle position of the tension compensation roller 5 and thus the position of its Pivot axis 8 held.

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 the same 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 ( from ) + b 2nd - a 2nd L ( Lab ) , 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 shaft 7 blocked from 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 have relatively large forces on the tension compensation roller 5 exercise 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 will. 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 (10)

1. A device for compensating tensile forces over the width of a web (3), preferably a paper or film web, drawn over rollers (4, 5, 6), with a freely rotatable tension compensating roller (5) deflecting the web (3) and mounted on a shaft (7) rotatable round its longitudinal axis (23), wherein the shaft (7) is supported in a swivel bearing (10) that is held in a frame (11), and the shaft (7) is held on both sides of the tension compensating roller (5) coupling the movement of its two ends in opposite directions and being carried in guideways (20), characterized in that the shaft (7) is held on both sides of the tension compensating roller (5) for movement by toothed gears (16, 17, 32) and is supported in the guideways (20) by means of antifriction bearings (21).
2. A device according to claim 1, characterized in that the antifriction bearing (21) is a ball or roller bearing fixed on the shaft (7), which is supported on a rail or column (20) as the bearing means.
3. A device according to claim 1, characterized in that the toothed gear (16, 17, 32) is formed by a toothed rod (16) which is disposed in an operative connection with a gear wheel (17) joined secured for rotation to the shaft (7).
4. A device according to claim 3, characterized in that between the toothed rod (16) and the gear wheel (17) of the shaft (7) there is provided an intermediate toothed gear (32) as the operative connection.
5. A device according to claim 4, characterized in that the axis (37) of the intermediate toothed gear (32) is aligned with the generated surface (40) of the tension compensating roller (5).
6. A device according to at least one of claims 3 to 5, characterized in that the toothed rod (16) is designed as a threaded spindle or worm.
7. A device according to claim 6, characterized in that on both threaded spindles (16) or worms there act actuating drives (50) coupled for movement in opposite directions, and that the shaft (7) is blocked against rotation round its longitudinal axis (23).
8. A device according to claim 7, characterized in that the actuating drives (50) are disposed in an operative connection with a control device (55) which is acted on by force sensing devices (52) provided on at least the bearings (12) of one of the rollers (4, 5, 6), preferably the tension compensating roller (5).
9. A device according to claim 8, characterized in that the control device (55) is acted on by at least one edge sensor (54) detecting the position of the web edge (53).
10. A device according to claim 8, characterized in that the force sensing devices (52) are disposed in an operative connection with a window comparator (75) which compares the torque exerted by the web (3) on the tension compensating roller (5) with a range lying between two limits, in which arrangement the tension compensating roller (5) is held for free pivoting in the case of torques lying within the range, and otherwise its position is regulated by the actuating drives (50).

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