WO2014190369A1

WO2014190369A1 - Method and drive unit for driving an endless belt

Info

Publication number: WO2014190369A1
Application number: PCT/AT2014/050127
Authority: WO
Inventors: Karl Morgenbesser
Original assignee: Berndorf Band Gmbh
Priority date: 2013-05-29
Filing date: 2014-05-28
Publication date: 2014-12-04
Also published as: TW201509562A

Abstract

The invention relates to a drive unit for driving an endless belt (2), comprising a driving drum (3), which is intended for contact with said endless belt (2), and a first motor (5) coupled to the drum (3). The drive unit also comprises a second motor (7) coupled to the drum (3) and/or a brake (9) coupled to the drum (3). The invention further relates to a method for operating said drive unit. In said method, the effect of the second motor (7) and/or of the brake (9) is superposed on the effect of the first motor (5).

Description

Method and drive unit for driving an endless belt

The invention relates to a drive unit for driving an endless belt, comprising a drive drum, which is provided for the contact to said endless belt, and a first coupled to the drum motor. Furthermore, the invention relates to a method for driving an endless belt in contact with a drive drum, in which the endless belt is acted upon or brought into a first movement by means of a first motor coupled to the drive drum with a first drive force / with a first drive torque ,

Such a drive unit or such a method are known in principle. For example, said endless belts are used within a strip caster for the production of films or plates. In most cases, these strips are made of steel and have a ground and / or polished surface. To make a film or plate, a liquid or pasty material is applied to the endless belt and can be transported therefrom through various processing stations, for example a curing station, before the finished film or plate is lifted off the said endless belt. The endless belt and the associated drive unit are in this case also part of a conveyor.

A disadvantage of the known drive units or drive method is that sometimes relatively strong irregularities in the course of the endless belt can occur. In a strip caster, vibrations may be caused, for example, by a puller that lifts the finished film or plate from the endless belt.

In strip casting plants, the casting drum, via which the material is poured onto the strip surface, is usually driven. In contrast, the removal of the film of the material solidified on the strip surface generally takes place on a drum opposite the casting drum, around which the endless belt revolves. The stripping can - in particular because of the acting as a spring endless belt - now lead to vibrations in the endless belt, whereby the casting drum (drive drum) can be disturbed in their course. Egg- However, a fault in the run of the casting drum is very critical because it may change the amount of material applied. Thus, a delay in the rotation of the casting roll causes too much material to be applied to one location, and acceleration results in the opposite. The same applies to vibrations in the vertical direction. Overall, the film produced has a comparatively high waviness or uneven thickness and inhomogeneous material properties.

The aforementioned irregularities can, in particular in addition to the above-mentioned effect, also be caused by fluctuations in the drive torque of the drive motor. These fluctuations in torque may be caused, for example, by a powered electrical inverter and result in a fluctuating tensile stress within the endless belt and also non-uniform movement thereof. Under certain circumstances, this can also cause relatively violent vibrations in the band.

An object of the invention is therefore to provide an improved drive unit or an improved method for driving an endless belt. In particular, fluctuating tensile stresses in the endless belt and non-uniform movements and in particular vibrations in the endless belt or in the driving Antriebstrom- mel / casting drum should be avoided or at least reduced compared to the prior art as far as possible.

This object is achieved by a drive unit of the type mentioned, which additionally comprises a second coupled to the drum motor and / or coupled to the drum brake.

This object is also achieved by a method of the type mentioned, in which the said first drive force and / or the said first drive torque or said first movement a second drive force / a second drive torque / a second movement by means of a second with the Drum coupled motor and / or is superimposed with a brake coupled to the drum. By the proposed measures fluctuating tensile stresses in the endless belt and non-uniform movements and in particular vibrations in the endless belt or in the driving drive drum / casting drum can be avoided or at least reduced. In the proposed method, a total drive force resulting from the first and second drive force is preferably measured, a total drive torque resulting from the first and second drive torque or an overall movement resulting from the first and second movement is controlled and the second motor and / or the brake are controlled such that the total drive force, the total drive torque or the total movement is as uniform as possible.

The running of the endless belt and the drive drum / casting drum is calmed by the proposed measures. In particular, in a strip caster in which the endless belt and associated drive unit are part of a conveyor for the applied material, there is appreciable improvement over the prior art as the movement of the endless belt / caster directly affects the quality of the product being manufactured , As a result, the film or plate produced becomes smoother and has a uniform thickness and homogeneous material properties. Committee or substandard goods can be significantly reduced.

In general, the second drive force / the second drive torque / the second movement can be generated by means of a second motor coupled to the drum and / or with a brake coupled to the drum. In this case, the second motor can generate a second drive force / the second drive torque / the second movement, which is rectified or directed counter to the first drive force / the second drive torque / the second movement. By contrast, only a second drive force / a second drive torque / a second movement can be generated with the aid of the brake, which is directed counter to the first drive force / the second drive torque / the second movement. Accordingly, when using a brake, the first motor should be slightly more dimensioned than when using a second motor, assuming the same total drive torque. Further advantageous embodiments and modifications of the invention will become apparent from the dependent claims and from the description in conjunction with the figures.

It is advantageous if the first motor is coupled via a gear with the drum.

As a result, a high torque can be transmitted to the drive drum or a high tensile force to the endless belt with a comparatively small motor. In addition, the use of a geared motor is relatively inexpensive.

It is also advantageous if the second motor / brake is directly connected to the drum. As a result, the torque transmitted to the drive drum or the tensile force transmitted to the endless belt and thus also the movement of the drive drum or of the endless belt can be influenced relatively directly. The fact that a transmission is avoided by the direct coupling of the drum with the second motor / the brake, also eliminates an alternating load respectively a lifting of tooth flanks, which could lead to premature wear of the drive. The direct coupling of the drum with the second motor / brake thus results in a comparatively robust drive unit. In this context, it is particularly advantageous if the second motor is designed as a synchronous electric motor, in particular as a "torque motor", since comparatively high torques in the drive drum or tensile forces can be impressed into the endless belt in such a way Torque motors are suitable for high accelerations and thus lead to a high dynamics of the system.Torque motors also have a higher drive stiffness than motor-gear units excellent control characteristics through the use of Torque motors.

In particular, it is advantageous if the first motor is coupled via a gear with the drum and the second motor is directly connected to this. In this way, relatively cheap geared motors can be used for the main drive. The partly bad dynamics of these heavy drives are compensated by the directly coupled second motor. Since this is only needed to control exchange shares, it can be comparatively small. Overall, such a drive unit with excellent dynamics but at a moderate cost. It is also advantageous if the first motor and the second motor / the brake are mechanically connected in series. In this arrangement, the second motor is mechanically connected between the first motor and the drive drum. This means that the second motor is also rotated by the first motor and is also connected to the drive drum. As a result, the torques / movements of both motors are superimposed on the drive drum. For example, the second motor may be connected to the drive drum via a worm gear. In such a series connection of the motors, one can also speak of a "master-slave arrangement", wherein the first motor is the "master" and the second motor is the "slave".

In a particularly advantageous variant of the invention, the conveying device comprises a sensor for detecting a movement of the endless belt and / or a driving force / tensile force acting in or on the endless belt. As a result, non-uniform courses of said movement or of the named force can be determined at any point of the endless belt and used as an actual input for a regulation of the first and / or second motor and the brake. This is advantageous, for example, if the location where a uniform force curve and / or a uniform movement are to be present is relatively far away from the drive drum. The endless band is not rigid, so that in some places even out-of-phase movements can take place. The proposed measures, the movement of the endless belt or the forces occurring in the same at the measuring point can be well controlled. For example, the movement of the endless belt can be determined in a manner known per se with an optical sensor, in particular a video camera. Forces within the endless belt can be determined for example with strain gauges, which are arranged on the endless belt and report their result wirelessly to a control unit for the drive unit.

It is furthermore advantageous if an alternating component contained in the total drive force, in the total drive torque or in the overall movement is determined and the second motor and / or the brake are actuated substantially in phase opposition to this alternating component. As a result, vibrations in the endless belt and / or the drive drum can be compensated. It is also advantageous if, in addition to a fundamental vibration of the alternating component, at least one harmonic of the same is also used for the control of the second motor and / or the brake. As a result, non-sinusoidal courses of movement and / or force can be compensated. The run of the endless band will be even calmer. For the determination of the harmonics or their amplitude and phase position, for example, the Fourier analysis can be used.

Finally, it is favorable if the first drive force, the first drive torque or the first movement is uniform. Thereby, the control for the first motor can be kept simple.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures. Show it:

1 shows a conveyor with an endless belt which is driven by a first geared motor and a second directly coupled motor.

FIG. 2 is an exemplary force-time diagram, a torque-time diagram and a speed-time diagram; FIG.

Fig. 3 as shown in Figure 1, only with a brake and an additional sensor for detecting a movement of the endless belt.

Fig. 4 as shown in FIG. 3, only with a first directly coupled motor and

Fig. 5 as shown in FIG. 3, only with two mechanically series-connected motors.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location details selected in the description, such as th, laterally, etc. related to the immediately described and illustrated figure and are to be transferred to a new position in a position change accordingly. Furthermore, individual features or combinations of features from the various exemplary embodiments shown and described may also represent separate solutions, inventive or inventive.

Fig. 1 shows a conveyor 101 with an endless belt 2 (for example made of metal) and an associated drive unit for driving the same. The drive unit comprises a drive drum 3, which is provided for contact with said endless belt 2, and a first motor 5 coupled to the drum 3. In this example, the first motor 5 is coupled to the drum 3 via a gear 6, it could but also be directly connected with this. Furthermore, the drive unit comprises a second motor 7 coupled to the drum 3. The second motor 7 is connected directly to the drum 3 in this example. For example, this could be designed as a synchronous electric motor, in particular as a "torque motor", which can generate a comparatively high torque Finally, the conveyor 101 also includes a control 8, which is connected to the first motor 5 and the second motor 7 ,

The function of the conveyor 101 shown in FIG. 1 is as follows:

By driving the first motor 5 coupled to the drum 3, the drum 3 is acted upon by a first drive force / with a first drive torque or set into a first movement. By correspondingly driving the second motor 7 coupled to the drum 3, a second drive force / a second drive torque / a second movement is superimposed on said first drive force, said first drive torque or said first movement.

Preferably, a total drive force resulting from the first and second drive force, a total drive torque resulting from the first and second drive torque or an overall movement resulting from the first and second movement are measured and the second motor 7 is controlled such that the total drive power, the total drive torque or the total drive power Total movement runs as uniformly as possible. 2 shows an example which shows a force-time diagram F over t, a torque-time diagram M over t and a velocity-time diagram v over t. For the following explanations, only the torque-time diagram M will be referred to above t for the time being.

In a first step, only the drive torque caused by the first motor 5 is considered. This is acted upon by the control 8 with a current, whereupon the drum 3 is set in motion. In addition, a periodic torque curve, namely the total vibration S is detected in this example. For example, the arrangement of FIG. 1 for this purpose comprises a torque sensor of a known type between the drum 3 and the transmission 6. For example, this torque sensor may be formed by a measuring bridge with strain gauges. This total vibration S, which is caused for example by a converter for the electrical supply of the first motor 5 and / or elasticities in the drive train (by which essentially a mass-spring system is formed), is usually undesirable. Instead, in a conveyor normally a uniform torque curve is desired.

If this total oscillation S is now decomposed into its components, for example with the aid of the Fourier analysis, it is shown that the total oscillation S comprises a DC component SO, a fundamental oscillation S1 and a first harmonic S2. Basically, the drum 3 should be subjected to the DC component SO (desired drive torque), but as already mentioned, the total vibration S (actual drive torque) is determined. In order to eliminate the alternating component, that is to say the oscillation components S 1 and S 2, the second motor 7 is now driven substantially in phase opposition to these oscillation components S 1 and S 2, the magnitude and phase of which accordingly have to be taken into account. The fact that the second motor 7 is connected directly to the drum 3, the antiphase vibration components can be more precisely transmitted to the drum 3 than would be possible with the first motor 5, which acts on the drum 3 via the gear 6. In addition, there are also advantages in that for the "basic drive" (that is, for the DC component SO), which requires a comparatively large drive torque, a large, but less dynamic and yet relatively inexpensive first motor 5 are used can. By contrast, a highly dynamic and comparatively small and therefore cost-effective second motor 7 is used for the usually relatively small alternating parts S1 and S2. Furthermore, the transmission 6 is protected in this way, since it is just - depending on where exactly the vibrations arise - is largely uniformly loaded. An alternating load, especially if it should even come to a lifting of the tooth flanks of the gears, lead to increased noise and premature wear or even premature destruction of the transmission 6. In order to be able to measure the torque transmitted by the second motor 7 to the drum 3, a torque sensor (for example a measuring bridge with strain gauges) may likewise be provided in the drive shaft thereof.

According to the specified method, therefore, an alternating component S1, S2 contained in the total drive torque is determined, and the second motor 7 is driven substantially in antiphase with respect to this alternating component S1, S2. In this case, in addition to a fundamental vibration S 1 of the alternating component, at least one harmonic S 2 of the same is also used for the activation of the second motor 7. The first drive torque of the first motor 5 runs substantially uniformly.

Of course, this is just one of many possible examples. It would also be conceivable, for example, for the dynamics of the first motor 5 to be sufficient in order to eliminate the fundamental vibration S 1. The second motor 7 can then, since the applied for the first harmonic S2 drive torque is relatively small, also be small in size. Of course, higher orders of the harmonics can be evaluated for the control. In addition, of course, non-periodic rule operations can be performed. For example, stochastic disturbances can be corrected as far as possible. In addition, it is also conceivable that the first motor 5 is supported during startup of the belt 2 or during braking thereof by the second motor 7. The control can be related not only to the torque M, but also equivalent to a force F, which sträng in the drive or acts in the endless belt 2. In particular, in the endless belt 2 to measuring strips can be attached, which measure the forces acting in the endless belt 2 forces and non-contact, for example by radio to the control 8 über-. convey. It is also conceivable that the control based on a speed in the drive sträng or based on a movement or speed v of the endless belt 2. For this purpose, the conveyor 101 may be equipped with a Wegmeßsensor 10 for the endless belt 2 (see also Fig. 3 and 4).

3 now shows a conveying device 102, which is very similar to the conveying device 101 from FIG. In contrast, however, this has a brake 9 instead of the second motor 7. This can in particular be connected directly to the drum 3. In addition, the conveyor 102 is equipped with a distance measuring sensor 10, which is connected to the controller 8. The brake 9 assumes a function analogous to the second motor 7, but with the difference that they can only apply braking torques (ie negative moments in FIG. 2), but no drive torques. The first motor 5 should therefore be dimensioned slightly larger in order to have reserves in the intervention of the brake 9. In this case, the high dynamics of the brake 9 and the comparatively low costs are advantageous. Despite the somewhat larger first motor 5, the conveyor 102 may therefore be less expensive than the conveyor 101 of FIG. 1.

In addition or as an alternative to the control given in the above example based on the drive torque M or the drive force F, the control in this example can also be carried out based on the movement of the endless belt 2 determined by the sensor 10. If a specific belt speed v is required as the desired value, then this can be regulated even better with the aid of the sensor 10 than would be the case via the measurement of the drive torques M or of the drive forces F. In particular, the belt speed v can be measured and regulated at the point at which a predetermined value is to be maintained as far as possible. Due to its long and thin shape, the endless belt 2 acts essentially as a spring. Together with the relatively sluggish deflection roller 4 results in a mass-spring system that can not or only very difficult to be detected alone with a sensor in the drive roller 3 in its entirety. If necessary, this can be modeled and incorporated into the regulation.

4 now shows a conveying device 103, which is very similar to the conveying device 102 from FIG. In contrast, but there is the first motor 5 is connected directly to the drum 3. A negative influence of the transmission 6 on the control behavior can thus be avoided. be, but so increases the required torque of the first motor 5 and its size. For a high control dynamics in this case in turn provides the brake 9, alternatively or additionally, of course, a second motor 7 may be provided. Fig. 5 finally shows a conveyor 104, in which the first motor 5 and the second motor 7 are mechanically connected in series. That is, the second motor 7 is rotated by the first motor 4 and is also connected to the drive drum 3. As a result, the torques / movements of both motors 5, 7 are superimposed on the drive drum 3. For example, the second motor 7 may be connected to the drive drum 3 via a worm gear. Instead of the second motor 7 or in addition to a brake 9 could be connected between the first motor 5 and the drive drum 3.

The exemplary embodiments show possible embodiments of a drive unit or a conveyor 101... 104, it being noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather a possibility of variation based on the teaching on technical action by subject invention Can the expert working in this technical field. In particular, it is also noted that the illustrated drive units or conveyors 101... 104 may in reality also comprise more or fewer components than shown and are sometimes shown in greatly simplified form in the figures.

For the sake of order, it should finally be pointed out that the illustrated drive units or conveyors 101... 104 as well as their components have also been shown partially out of scale and / or enlarged and / or reduced in size to better understand their structure.

The task underlying the independent inventive solutions can be found in the description. REFERENCE NUMBERS

101..104 conveyor

2 endless belt

3 drive drum

4 pulley

5 first engine

6 gears

7 second engine

8 control / regulation

9 brake

10 position sensor

F force

M torque

S total vibration

50 DC share

51 basic vibration

52 harmonic

v speed

Claims

Patent claims

A drive unit for driving an endless belt (2), comprising:

a drive drum (3) provided for contact with said endless belt (2), and

a first motor (5) coupled to the drum (3),

marked by

a second motor (7) coupled to the drum (3) and / or a brake (9) coupled to the drum (3).

2. Drive unit according to claim 1, characterized in that the first motor (5) via a transmission (6) with the drum (3) is coupled.

3. Drive unit according to claim 1 or 2, characterized in that the second motor (7) / the brake (9) is connected directly to the drum (3).

4. Drive unit according to one of claims 1 to 3, characterized in that the second motor (7) is designed as a synchronous electric motor.

5. Drive unit according to one of claims 1 to 4, characterized in that the first motor (5) and the second motor (7) / the brake (9) are mechanically connected in series.

6. conveying device (101..104) with an endless belt (2), characterized by a drive unit connected thereto according to one of claims 1 to 5.

7. conveying device (101..104) according to claim 6, characterized by a sensor (10) for detecting a movement of the endless belt (2) and / or acting in or on the endless belt (2) driving force.

8. A method for driving an endless belt (2) in contact with a drive drum (3), wherein the endless belt (2) is coupled to a first drive force / with a first motor coupled to the drive drum (3) first acted upon torque or is placed in a first movement, characterized in that

in that said first drive force, said first drive torque or said first movement, respectively, is a second drive force / a second drive torque / a second movement with the aid of a second motor (7) coupled to the drum (3) and / or one with the drum (3) coupled brake (9) is superimposed.

9. The method according to claim 8, wherein a total drive force resulting from the first and second drive force, a total drive torque resulting from the first and second drive torque or an overall movement resulting from the first and second movement is measured, and the second Motor (7) and / or the brake (9) is controlled such that the total drive force, the total drive torque or the total movement is as uniform as possible.

10. The method according to claim 8 or 9, characterized in that in the total drive power, in the total drive torque or in the total movement contained AC component (S l, S2) determined and the second motor (7) and / or the brake (9) in Essentially in phase opposition to this alternating component (Sl, S2) is driven.

11. The method according to claim 10, characterized in that in addition to a

Basic vibration (S l) of the alternating component and at least one harmonic (S2) thereof for the control of the second motor (7) and / or the brake (9) is used.

12. The method of one of claims 8 to 11, characterized in that the first

Driving force, the first drive torque or the first movement is uniform.