EP0178704A1 - Device for controlling the tension of a web - Google Patents

Abstract

1. Apparatus for controlling the tension in a web (4, 67) of paper, foil, fabric, textiles, plastics, metal or such like with a braking device (1, 26, 27, 17, 21, 28, 29, 52, 53), which acts on a turning spool (3, 51) and contains two actuating devices (8, 13, 16 ; 32, 33, 39 ; 73, 74, 61 ; 75, 76, 87), and a compensation roller (7, 70) acting on the braking device with the said of a cam disk (16, 73) or such like, characterized in that the compensation roller (7, 70) is connected both to the first (8, 13, 16 ; 61, 73, 74) and the second actuating device (32, 33, 39 ; 62, 75, 76, 87) for the braking device (1, 26, 27, 17, 21, 28, 29, 52, 53, 54) in such a way that it acts upon them, and is further connected additionally to a multipoint regulator (39, 75, 76), in that the second actuating device (32, 33, 39 ; 62, 75, 76, 87) for the braking device (1, 26, 27, 17, 21, 28, 29, 52, 53, 54) is connected to the compensation roller (7, 70) in such a way as to act upon the latter, a multipoint regulator (39, 75, 76) being interlineated and changing the effective range of the second actuating device (32, 33 39 ; 62, 75, 76, 87) and in that additionally the effective range of the first actuating device (8, 13, 16 ; 61, 73, 74) is at least as great as the degree by which the compensation roller (7, 70) can move without the multipoint regulator (39, 75, 76) responding.

Description

The proposed invention relates to the control of the tension in a web made of paper, film, fabric, textiles, plastics, metal or the like. With a braking device acting on an unwinding roll, containing two actuating devices and one with the aid of a cam or the like dancer roller acting on the braking device.

Devices of the type mentioned are used in machines for processing strip-shaped goods, for example in printing, slitting or winding machines. In these machines, a web unwinding from a roll has to be subjected to a certain constant tension so that this web can be subjected to a processing process, for example a printing process or a winding process, without any problems. For this reason, there has been no shortage of efforts to develop such facilities.

For example, from DD-PS 38 714 a device is known which contains a dancer roller which is able to act on two induction clutches, these induction clutches being mechanically connected to the reel from which a sheet of paper or the like is drawn off. However, the device described here is such that the dancer roller acts on both induction clutches in any of its many possible positions, and consequently both clutches must be designed in such a way that they can follow a very large control range. This means a high structural effort for the couplings.

From the other DD-PS 59 452, however, a device has become known which contains a worm gear, the mechanically low efficiency is exploited to brake that role from which a web to be processed is braked in such a way that - the worm gear is used in the sense of a constant-acting brake with high braking force, so that a dancer roller only has to adjust a smaller area. The worm gear takes over a relatively high but constant ratio of the braking power to be applied. Thus, the worm gear described here ultimately serves as an amplifier for the deflections that the pendulum roller delivers due to changes in the tension in the unwinding path.

From DE-AS 19 38 814 a further device is known, which contains two brakes, which alone or together can act on an unwound role. In this device, one of the two brakes is switched off if necessary, so that only a very rough and therefore unsatisfactory approach to the ideal hyperbolic characteristic of the brake device in question can be achieved.

From US-PS 29 65 326 a device is also known in which the tension of a web unwinding from a roll is measured by a dancer roll and in addition the radius of the shrinking roll is scanned. The device also contains a large number of actuating and control elements, so that there is a great deal of effort here, which also contains the risk of the control system vibrating. In addition, there are also fluctuations in the diameter of the unwinding roll, as they result from the previous winding of a natural material, such as paper or a plastic with inhomogeneities, for example thick spots, entered into the control system, although these fluctuations have nothing to do with the build-up of tension in the unwinding web. These fluctuations in diameter, even if they are only slight, are entered into the braking system for the unwinding reel and thus change the braking torque acting on the unwinding reel, although this does not affect the build-up of tension in the unwinding web is necessary and can also result in the risk of undesirable vibrations within the control system.

Proceeding from this, there is the task of creating a device of the type mentioned which, using machine elements which are less known per se and which has relatively little control capability per se, has both a large control range and high sensitivity and high stability. This object is achieved in that the dancer roller both with the first and with the second actuating device for the brake in terms of effectiveness and additionally with a multi-point controller that the second actuator for the brake is operatively connected to the dancer roller with the interposition of the multi-point controller, wherein the multi-point controller changes the effective range of the second actuating device and that, furthermore, the effective range of the first actuating device is at least as large as the deflection in which the dancer roller can move without the multi-point controller responding. The multi-point controller can be a three-point controller or a five-point controller.

The invention contains only a few machine elements for Setting or regulating the braking torque required on the unwinding roll, which are also available at low cost. There is therefore little play due to the small number of parts and also a slight tendency to vibrate in an undesirable manner, which means nothing other than that the proposed device is stable in terms of control technology. The ideal hyperbolic characteristic of a brake for the role of an unwinding web is well approximated, the dancer roller customary for scanning the tension prevailing in the unwinding web directly influencing only a small range of the braking force or braking torque to be applied to the reel needs and whereas the major part of the braking force or braking torque does not have to be influenced directly by the dancer roller. This results in a sensitivity and a high sensitivity of the entire control system, whereby the control range is variable within very large limits - as is necessary for the control of unwinding roles - since the dancer roller also indirectly accounts for the greater part of the Can influence the braking torque to be applied. The fact that the dancer roller via a multi-point controller, which allows the dancer roller a certain freedom of movement without this controller responding, which is able to adjust one of the two actuating devices for the brake, hereby specifies a specific braking range, which the dancer roller uses the first actuating device for the brake to modulate in a superimposed manner. When the limits of this modulation are reached, the second actuating device is adjusted accordingly, so that the braking and control process can be continued automatically at another level.

The proposed device will now be explained in more detail with reference to two exemplary embodiments schematically depicted in the attached figures, without these exemplary embodiments being intended to restrict the inventive concept. In the present context, non-essential machine parts are not shown in the figures for the sake of a clearer representation. The parts not shown are already well known to the person skilled in the art.

• Fig. 1 : mechanisch- elektrisches Ausführungsbeispiel
• Fig. 2 : Ausführungsbeispiel unter Verwendung von Druckmittel

The individual figures mean:

• Fig. 1: mechanical-electrical embodiment
• Fig. 2: embodiment using pressure medium

A rolling shaft 1 is rotatably supported on both sides in a bearing block 2. A roll 3 has been wound onto the unwind shaft in a previous work process. A web 4 is unwound from this in order to run to a processing or processing machine, for example a printing machine or a reel cutting and winding machine.

For this purpose, the web loops around 4 guide rollers 5 and 6 and a dancer roller 7. This is rotatably mounted in an arm 8, which is able to pivot about a fixed bearing 9 in the direction of arrow 10. In this way, the weight of the dancer roller 7 and the weight of the arm 8 and a load weight 12 adjustable in the direction of the arrow 11 presses on the web 4, so that a desired and essentially constant tension is created within the web 4.

On the arm 8, a pull rod 13 is rotatably fastened by means of a joint 14. With the help of a joint 15, the other end of the pull rod 13 is connected to an eccentric 16. The eccentric 16 is rotatably mounted within a brake shoe 17 so that it can be pivoted about the joint 18 in the direction of the arrow 19. A second brake shoe 21 is pivotally mounted about a further joint 20. The position of the brake shoes 17 and 21 can be adjusted by hand using a spindle 22 and a nut 23 as required.

Due to the articulated connection of the pendulum roller 7, swivel arm 8, pull rod 13 and eccentric 16, the eccentric can be adjusted when the pendulum roller 7 swings back and forth in the direction of arrow 10 as a result of the tensions within the web 4. In this way, the brake pads 24 and 25 of the brake shoes 17 and 21 come into more or less contact with a first brake disc 26, which in turn is mechanically firmly connected to the unwinding shaft 1, so that there is a changed tension within the track 4.

A second brake disc 27 is also mechanically fixed to the unwinding shaft 1. This is at least partially surrounded by brake shoes 28 and 29 with brake pads 30 and 31. The brake shoes 28 and 29 can be pivoted about joints 35 and 36 with the aid of a spindle 32, an electric motor 33 and a return spring 34.

The motor 33 is only adjusted if the deflections of the pendulum roller 7 in the direction of arrow 10 are large enough to engage the left end of the arm 8 in FIG. 1 with the contacts 37 or 38 of a control device 39, which is also a so-called three Point or five-point regulator can be brought into contact. If the contact or switch 37 is closed, then the motor 33 runs in one, when the contact or switch 38 is closed, the motor 33 rotates in the opposite direction of rotation. In this way, the spindle 32 rotates in one or the other direction of rotation, so that the brake 27, 28, 29, 30, 31 can be opened or closed indirectly by the dancer roller by means of the actuating device containing the motor 33 and the spindle 32 .

The operation of the device according to Fig. 1 is such that the first actuating device for the brake containing the eccentric 16 and the pull rod 13 and the arm 8 the movements of the pendulum roller 7, i. is able to continuously follow the changes in the tension of the web 4. Only when the deflections of the pendulum roller 7 in the direction of arrow 10 exceed a predetermined amount, which exceeds the distance 40 that the contacts or switches 37 and 38 have between themselves, is the motor 33 and the spindle 32 by means of between the dancer roller 7 and the motor 33 interposed control device, in particular a multi-point control device, the second actuating device for the brake. As a result, the brake pads 30 and 31 are in a different position relative to the brake disc 27, as a result of which the effective range of the entire brake device containing the brake discs 26 and 27 is adjusted. This gives the possibility that the deflection of the pendulum roller 7 is reduced again, i.e. that the switches or contacts 37 or 38 are no longer touched and the arm 8 assumes a central position between the switches or contacts 37 or 38 again. This is only possible if the multi-point controller is fixed in the machine within the swivel range of the dancer roller.

In this way, the dancer roller 7 is operatively connected directly to a first actuating device for the brake. In addition, the pendulum roller 7 cooperates with a multi-point controller 39 and the second actuating device for the brake, which contains the brake shoes 28 and 29, `becomes effective due to the deflections of the pendulum roller 7 with the interposition of the multi-point controller 39. The articulation points 14 and 15, as well as the size of the eccentric 16 and the pitch of the thread on the spindle 22 are designed so that those deflections of the pendulum roller 7 which do not yet trigger contact with the contacts or switches 37 and 38 make such a great change the braking effect on the first actuating device for the brake can result in the contacts or switches 37 and 38 being able to be reached with certainty by the deflection of the arm 8 if the control range of the first actuating device has not yet been exceeded. This means that the effective range of the first actuating device for the brake is at least as large as the deflections of the dancer roller 7 corresponding to the size of the multipoint controller.

In the exemplary embodiment according to FIG. 2, the unwinding shaft for the roll 51 to be unwound is fixedly connected in an analogous manner to a brake disk 52 and rotatably supported in bearings (not shown). Brake shoes 53 and 54 can engage with the brake disk 52. The brake shoes 53 and 54 are pivotally mounted in a brake frame, which includes the levers 55 and 56, by joints 57 and 58. The levers 55 and 56 can in turn be pivoted about joints 59 and 60.

On the levers 55 and 56 are also a first pressure medium cylinder 61 for a first actuating device of the brake and a second pressure medium cylinder 62 for a second actuating device of the brake are fastened by joints 63, 64, 65 and 66.

A web 67 is drawn off the roll 51 in order to run to a processing machine. The web 67 wraps around the guide rollers 68 and 69 and the dancer roller 7o. The dancer roller 70 is rotatably attached to an arm 71 which can pivot in the direction of arrow 72 around the center of the guide roller 68.

A cam 73 is fixedly connected to the arm 71 and thus follows the pivoting movements of the arm 71. A valve 74 is adjusted by pivoting the cam disk 73.

The device also contains a multi-point controller 75/76, the contacts 77, 78, 79 and 80 are arranged such that the arm 71 and thus the dancer roller 72 must first pass through a deflection 81 in the direction of arrow 72 before one of the Contacts 77 to 80 of the multipoint controller 75/76 can take effect.

By means of a pump 82 pressure medium is fed into a cylinder 83 which is connected to the arm 71 by means of a joint 84. With the help of the valve 85 and an associated manometer 86, a pressure can be set in the pressure medium cylinder 83 which corresponds to the tension desired in the path 67. With the help of the valve 74, pressure medium is fed into the cylinder 61, which belongs to the first actuating device for the brake. Due to the variations in the tension in the path 67, the dancer roller 70 swings out alternately in the direction of the arrow 72 and thus adjusts the position of the curves disc 73 and that of the valve 74. This results in a changed pressure in the cylinder 61 and an influencing of the braking force acting on the brake disc 52 or the braking torque taking effect from the deflections of the dancer roller in a direct manner.

The distance 81, which the contacts 78 and 79 of the multi-point controller 75/76 have between one another, is selected such that the control range of the first actuating device for the brake, comprising the cam disk 73, the valve 74 and the pressure medium cylinder 61, is at least not exceeded.

If the fluctuations in the tension in the web 67 and thus the deflections of the dancer roller 70 should increase, then the contacts 78 or 79 first become effective, which causes the control device 75/76 to pressurize pressure medium from the pump 82 via the valve 87 into the Initiate pressure medium cylinder 62. As a result, the brake, which comprises the brake disk 52 and the brake shoes 53 and 54 and the pressure medium cylinders 61 and 62, is actuated in a second indirect manner. In this way, a different pressure is created in the pressure medium cylinder 62 than before, so that with the aid of the pressure present in the pressure medium cylinder 61, the brake operates overall at a different level.

In the event that the deflections of the dancer roller 70 should become very large, the contacts 77 and 80 are provided in the multipoint controller 75/76. When these contacts are actuated, the controller 76 switches over to a quick adjustment, so that the same pressure as in the actuation of the contacts 78 and 79, but a larger amount of pressure medium is introduced into the cylinder 62.

The pressures in the pressure medium cylinders 61, 62 and 83 can be preselected or set by valves 85, 74 and 87. These pressures can be the same as one another but also different from one another. For example, a higher or even a significantly higher pressure can be effective in the pressure cylinder 62 than in the pressure cylinder 61. The pressure in the pressure medium cylinder 83 corresponds in each case to the desired tension in the path 67. It goes without saying that the valves and associated pressure medium cylinders are connected to one another by lines and that these lines to the valves and cylinders in the above-mentioned sense in Connect.

The pump 82 is connected to the pipeline 88 and this to the branch lines 89 and 90. The branch line 89 is fastened to the valve 85 and is operatively connected to it. With the help of the valve 85, the pressure prevailing by the pump 82 in the branch line 89 is reduced to a desired level, so that the pressure indicated by the manometer 86 prevails in the pipeline 91 and the pressure medium cylinder 83 connected to it. In addition, the pipeline 88 is connected to the valve 87 by means of the branch line 90. The position of the valve 87 can be changed with the aid of the multi-point controller 75/76 via line 92 in such a way that in the pipeline 93 and thus in the second pressure medium cylinder 62 connected to it, a by closing or not closing the contacts 77, 78, 79 or 80 the multipoint controller 75/76 certain pressure prevails. Finally, the valve 74 sensing the position of the cam disk 73 is connected via a pipe 94 to the first pressure medium cylinder 61 in such a way that the pressure prevailing in this pipe is determined by the respective position of the dancer roll 70, that is to say one by the dancer roll mo is pressure. The contact plate 75 of the multi-point controller and the contacts 77, 78, 79 and 80 are connected to the control device 76 of the multi-point controller via lines 95, 96, 97 and 98.

The exemplary embodiments show that in both cases only a few machine parts are used for regulating this web tension and that the parts are relatively inexpensive. In addition, the area in which the entire braking device acts on the unwinding roll is automatically changed by the deflections of the dancer rolls during the unwinding of a roll, which results in a very good approximation to the ideal hyperbolic characteristic of such a braking device. In addition, the device as a whole is also cheaper than an electrical device with so-called brake generators, which require complex control.

The present invention is not restricted to the exemplary embodiments described. Rather, it can be modified in many different ways, for example in that the motor 33 can also be connected to the spindle 22 instead of the nut 23. In this case, the return spring 34 could also be pushed over the spindle 22 in such a way that it comes to rest between the brake shoes 17 and 21 and the aim is to push them apart. In such a case, it is conceivable that the brake shoes 28 and 29 and the brake disc 27 can also be omitted.

In addition, it is also possible to actuate the brake connected to the unwinding roll electrically in two ways.

In addition, it is possible to rotatably support the roll to be unwound in place of a roll-off shaft also by means of cones in the roll rack assigned to it. In addition, the position of the web can be monitored using so-called side edge controls and corrected if necessary. In addition, it is possible to arrange compression springs between the brake shoes and the associated actuating devices so that any runout errors of the brake discs do not have a negative effect on the web tension.

Parts list for Figure 1

• 1 unwinding shaft
• 2 bearing block
• 3 roll
• 4 lanes
• 5 guide roller
• 6 guide roller
• 7 dancer roller
• 8 arm
• 9 bearings
• 10 arrow
• 11 arrow
• 12 load weight
• 13 tie rod
• 14 joint
• 15 joint
• 16 eccentrics
• 17 brake shoe
• 18 joint
• 19 arrow
• 20 joint
• 21 brake shoe
• 22 spindle
• 23 mother
• 24 brake pad
• 25 brake pad
• 26 first brake disc
• 27 second brake disc
• 28 brake shoe
• 29 brake shoe
• 30 brake pad
• 31 brake pad
• 32 spindle
• 33 electr. engine
• 34 return spring
• 35 joint
• 36 joint
• 37 Contact / switch
• 38 contact / switch
• 39 Control device / multi-point controller
• 40 distance

Parts list for Figure 2

• 51 roll
• 52 brake disc
• 53 brake shoe
• 54 brake shoe
• 55 levers
• 56 levers
• 57 joint
• 58 joint
• 59 joint
• 60 joint
• 61 first pressure cylinder
• 62 second pressure cylinder
• 63 joint
• 64 joint
• 65 joint
• 66 joint
• 67 lane
• 68 guide roller
• 69 guide roller
• 70 dancer roller
• 71 arm
• 72 arrow
• 73 cam
• 74 valve
• 75 contact plate
• 76 control unit
• 77 contact
• 78 contact
• 79 Contact
• 80 contact
• 81 distance
• 82 pump
• 83 pressure cylinder
• 84 joint
• 85 valve
• 86 manometers
• 87 valve
• 88 pipeline
• 89 branch line
• 90 branch line
• 91 pipeline
• 92 line
• 93 pipeline
• 94 pipeline
• 95 line
• 96 line
• 97 management
• 98 line

Claims (3)

1. A device for controlling the tension in a web (4.67) made of paper, film, fabric, textiles, plastics, metal or the like. With two actuating devices (8,13.) Acting on an unwinding roll (3,51) , 16; 32,33,39; 73,74,61; 62,75,76,87) containing braking device (1,26,27,17,21,28,29,52,53, 54) and one with help a cam disc (16.73) or the like. Dancer roller (7.70) acting on the braking device, characterized in that the dancer roller (7.70) with both the first (8.13.16; 61.73.74) as also effective with the second actuating device (32,33,39; 62,75,76,87) for the braking device (1,26,27,17,21, 28,29,52,53,54) and additionally with a multi-point controller (39,75,76) that the second actuating device (32,33,39; 62,75,76,87) for the braking device (1,26,27,17,21,28,29,52,53 , 54) is operatively connected to the dancer roller (7,70) with the interposition of the multi-point controller (39,75,76), the multi-point controller (39,75,76) the effective area of the second actuating device (32,33,39; 62,75,76,87) for the braking device and that the effective range of the first actuating device (8,13,16; 61,73,74) is at least as large as the deflection in which the dancer roller (7,70) can move without the multi-point controller (39,75,76) responding. 2. Device according to claim 1, characterized in that the multi-point controller (39,75,76) is a three-point controller. 3. Device according to claim 1, characterized in that the multi-point controller (39,75,76) is a five-point controller.

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