EP1795470A1 - Method for determining the web tension - Google Patents

Abstract

The method involves determining a web tension (S1) of a web tension section (111), which is provided in a product web (101), based on the modulus of elasticity of product web materials, the speed of a transport axle and the drive torque of the axle. The drive torque of the axle depends on the diameter of the axle. Web tensions (S2, S3, S4) of web tension sections (112, 113, 114) are determined based on the determined web tension (S1). The change in the expansion characteristics of the product web is evaluated. Independent claims are also included for the following: (1) a processing unit for determining the web tension of the web tension section (2) a computer program with a program code for determining the web tension of a web tension section (3) a computer program product with a program code structure for determining the web tension of a web tension unit.

Description

The present invention relates to a method for determining a web tension according to the preamble of patent claim 1.

State of the art

There are various devices or machines in which a web is processed in individual web sections with associated web tension. The control of web tension of a web is a complex process involving a variety of variables. For the control of the web tension to a predetermined setpoint, the knowledge of a current actual value is required.

Processing machines in which the web is subdivided into sections of different web tension can be found especially in the area of paper, cardboard, plastic and metal foils. In these machines, the web as it passes through the machine is divided into at least two sections, each section having a predetermined web tension value.

In the prior art, the web tension in each section is measured by means of suitable web tension sensors and regulated by a corresponding influence of the machine on the target value. For example, the speeds of the transport axes are changed so that the web tension in each section follows the respective target value. For this purpose, web tension controls are known, e.g. the system SYNAX, which has such a function for web tension control.

In the EP 0 914 944 For example, there is disclosed a tension control system having a plurality of tension detectors disposed on the upstream sides of pressure cylinders and on the upstream sides of tension rollers for detecting tension on a web, wherein speed setting means for adjusting respective rotational speeds of the pressure cylinders and the tension rollers on the base of the output signals from regulators to which detected values are fed back from respective voltage detectors, the regulators being associated with voltage setting devices and the controllers comparing the detected values from the voltage detectors and setpoints from the voltage setting devices and the output signals for controlling the rotational speeds of the voltage comparators Output pressure cylinder and the tension rollers to reduce the compared values to zero.

Since the adjustment of a drive axle acts on the web tension of several sections, e.g. the SYNAX system makes it possible to control one positioning axis of two web tension control systems. That The web tension control of a section can adjust both the previous and subsequent transport axes, so as not to interfere with web tension in the adjacent sections during control operations in this section. Depending on the time constant of the controls, oscillatory processes can occur as a result.

In the cited prior art, a separate measuring device is thus provided for each web tension section, wherein in addition an influence of the voltage adjustments of the individual sections with each other can not be completely avoided.

It is therefore an object to provide an improved method for determining a web tension, which does not have the above-mentioned problems.

According to the invention, therefore, a method for determining a web tension and a corresponding computing unit, a computer program and a computer program product with the features of the independent patent claims are presented. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

In the method for determining a web tension of at least one second web tension section in one At least two web tension sections having web, the web tension of at least a first web tension section is first determined. The web tension of the at least one second web tension section is then determined on the basis of the determined web tension of the at least one first web tension section. It should be made clear at this point that the web tension of the at least one second web tension section is not measured in particular.

Advantageously, a large number of measuring sensors for determining the web tension can be saved with the solution according to the invention. Depending on the embodiment of the invention, all or all but one measuring device can be saved. Thus, a significant cost and material savings is possible because the remaining web tension values are determined by calculation or estimation. The method according to the invention can be used very advantageously in conjunction with a web tension control. The values obtained are expediently compared with intended target web tension values and the web tension is then regulated accordingly. Furthermore, the mutual influence can be advantageously reduced. If, in the solution according to the invention, the different web tension controllers automatically receive early changes in the preceding web tension sections via a precontrol, the compensation processes are considerably shorter.

Advantageously, the web tension of the at least one first web tension section is measured. For this example, a measuring roller and a pressure cell can be used, as is known in the art. This will be determines an absolute web tension value that may be used to determine the remaining web tension values.

, wobei der Transport von der Transportachse bzw. -walze mit der Drehzahl n1 in Richtung der Transportachse mit der Drehzahl n2 erfolgt. Der Term $\frac{n2-n1}{n1}$

beschreibt eine Dehnung d.According to a preferred embodiment of the solution according to the invention, the web tension of the at least one first web tension section is determined taking into account a modulus of elasticity of the web material and a rotational speed of at least two transport axes. This also determines an absolute web tension value that can be used to determine the remaining web tension values. Assuming slip-free transport, the web tension value S1 in the at least one first web tension section between two transport axes is calculated with the rotational speeds n1 and n2 taking into account the modulus of elasticity E of the web material $S1=e\cdot \frac{n2-n1}{n1}$

, The transport from the transport axis or roller at the speed n1 in the direction of the transport axis at the speed n2. The term $\frac{n2-n1}{n1}$

describes an expansion d.

According to an equally preferred embodiment of the solution according to the invention, the web tension of the at least one first web tension section is determined taking into account a known web tension value, in particular by means of a dancer based on the web tension value impressed by the dancer, and a drive torque of at least one transport axis. This also determines an absolute web tension value that can be used to determine the remaining web tension values. For example, to determine a web tension S1, taking into account the known Web tension S0 considered the drive torque N of the transport axis between the sections with the web tension S0 and S1. The drive torque N is typically determinable in a machine. It can, for example, be read by the drive or by the tension control. From the drive torque N can preferably be closed over the diameter D (lever law) on the web tension-changing force F1 = 2N / D and from there to the fed web tension F1. S1 then calculates to S1 = S0 - F1. If the drive operates in the motor range (positive drive torque), the web tension in section 1 will be lower than in section 0. If it operates in regenerative mode (negative drive torque), the web tension in section 1 will be higher than in section 0 ,

It is expedient if, in the method according to the invention, the web tension of the at least one second web tension section is determined on the basis of a rotational speed of at least two transport axes. If the web tension S1 is known in a section, the elasticity modulus can be deduced on the basis of the rotational speeds of the transport axes delimiting the web section. If this constant of the web is not changed (eg by processing), it can be concluded in another section on the web tension S2 contained therein. For this purpose, the elastic moduli are set equal in both sections. Thus, a web tension value S2 of the at least one second web tension section is determined on the basis of the web tension value S1 of the first web tension section. About the speeds of the transport axes involved obtained, as described above, the strains d1 and d2 of the sections. That's what one determines $S2=S1\cdot \frac{d2}{d1}$

It is expedient if, in the method according to the invention, changes in a stretching property, in particular a modulus of elasticity, of the material web are taken into account. The modulus of elasticity is typically changed by machining on the web. If this change is known, this can be taken into account when determining the web tension. Thus, the accuracy of the method can be increased.

. Somit ergibt sich die Bahnspannung S2 im Bahnspannungsabschnitt mit dem Querschnitt A2 zu $S2=S1\cdot \frac{d2}{d1}\cdot \frac{A2}{A1}$

. Damit kann die Genauigkeit des Verfahrens erhöht werden.According to an advantageous development of the invention, a second cross section of the web deviating from a first cross section of the web in a web tension section in a different web tension section is considered linearly with the ratio of the first to the second cross section for the modulus of elasticity. If, for example, the cross-section of the web is changed by processing the web, for example by trimming the edge or punching out material, the modulus of elasticity will change accordingly. If, for example, the cross-section of the web is reduced, the modulus of elasticity will also be reduced. As an approximation one can assume a linear relationship between web width or cross-section A and elastic modulus E. If the cross section is changed from A1 to A2, the modulus of elasticity of E1 changes $e2=e1\cdot \frac{A2}{A1}$

, Thus, the web tension S2 results in the web tension section with the cross section A2 $S2=S1\cdot \frac{d2}{d1}\cdot \frac{A2}{A1}$

, Thus, the accuracy of the method can be increased.

It is advantageous if, in the invention, a slippage of the transport axes is taken into account by estimating the slip. Likewise, the slippage of the transport axes is taken into account by measuring the slip. Is the transport not completely slip-free. (For example, by not permanently employed counter-pressure rollers), so with knowledge of this slip this can be included in the determination of the speed ratios. This slip can not be determined automatically, but must be estimated or measured, e.g. by means of a measuring wheel. Thus, the accuracy of the method can be increased.

Preferably, in the method according to the invention, the web tension of the at least one second web tension section is determined on the basis of a drive torque of at least one transport axis.

According to a preferred embodiment of the method according to the invention, the drive torque is converted by means of a diameter of the at least one transport axis by means of a lever law in a web tension-changing force.

Appropriately, in the invention, in particular when determining the web tension-changing force, a friction torque of the at least one transport axis taken into account. The friction torque can be taken into account, for example, as the sum of a constant value and a speed-dependent or speed-proportional value or another predefinable speed-dependent characteristic. The compensation values can be easily compared a manual, semi-automated or fully automated test drive without web. This makes it possible to increase the accuracy of the web tension determination.

Equally expediently, a machining torque of a machining axis within a web tension section is taken into account in the method according to the invention. As a result, a tension to be determined can be determined more accurately. It makes sense to take the machining torque into account with a constant and a speed-proportional component. This embodiment makes it possible, in particular, to use a simple computer model.

Appropriately, in the invention, a measurement of the drive torque by means of a filtering of the measured moments, the determined friction and / or the machining forces performed. This makes it possible to smooth the determined web tension values over time, and thus to make it easier to further process the determined values.

Appropriately, in the case of a measurement of the drive torques, a calibration of drive data, in particular a torque constant of the motor, is taken into account. The accuracy of the method according to the invention for determining a web tension can hereby be improved.

Appropriately, in the invention, the drive data are determined by means of a manual, semi-automatic or fully automated test drive. This is for a user improves the handling of the method or system according to the invention.

Appropriately, in the invention, a field weakening operation of a motor of the determination of the drive torque is taken into account. This consideration also increases the accuracy of the method according to the invention.

A computing unit according to the invention determines the web tension of the at least one second web tension section on the basis of the web tension determined in the first web tension section according to a method of the invention.

A computer program according to the invention contains program code means for determining the web tension of the at least one second web tension section on the basis of the web tension determined in the first web tension section according to the inventive method, when the computer program is executed on a computer or a corresponding computer unit, in particular one of the computer units according to the invention.

A computer program product according to the invention contains program code means which are stored on a computer-readable data carrier in order to determine the web tension of the at least one second web tension section on the basis of the web tension determined in the first web tension section according to the inventive method, if the computer program product is stored on a computer or on a corresponding computer unit, in particular one of the computer units according to the invention, is performed. Suitable data carriers are in particular floppy disks, hard disks, flash memories, EEPROMs, CD-ROMs, etc. It is also possible to download a program via computer networks (Internet, intranet, etc.).

The solution according to the invention is preferably used in conjunction with a web tension control.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention is illustrated schematically with reference to an embodiment in the drawing and will be described below in detail with reference to the drawings.

figure description

FIG. 1

shows schematically the structure of a processing machine, in which an embodiment of the method according to the invention can be advantageously applied; and

FIG. 2

1 shows a flow chart of an embodiment of a method according to the invention for use for the processing machine according to FIG. 1.

In FIG. 1, a processing machine, in which a material web 101 is subdivided into sections of different web tension, is denoted overall by 100. In the processing machine 100, a web 101 is transported and processed. For clarity, the processing devices are not shown themselves. The web 101 moves in the present example in the direction indicated by an arrow V.

The web 101 is, as mentioned, divided into several web sections 111 to 114. Each web section 111 to 114 has an actual and a desired web tension. The web sections 111 to 114 are each web cross-sections A1 to A4 and Elastic moduli E1 to E4 associated.

The web sections 111 to 114 are limited by the associated transport axes. For example, the web portion 111 is limited on one side by the transport axes 200, 200 'and on the other side by the transport axes 201, 201'. The transport axes 200 to 204 are the driven transport axes, whereas the transport axes 200 'to 204' are, for example, driveless counterpressure axes. The transport axes 200, 200 'rotate at a speed n0, the transport axes 201, 201' rotate at a speed n1, etc. The transport axes 204, 204 'finally rotate at a speed n4.

In the web section 111 is a measuring device 210 for determining an absolute web tension S1 in this Section provided. According to the proposed solution, the web tension in the sections 112, 113 and 114 is determined on the basis of this determined first web tension. For these web sections 112 to 114 no measuring devices are provided.

In the following, it will be explained in conjunction with FIG. 2 how the web tension in the individual sections 111 to 114 is determined.

The method begins in a method step 301. Subsequently, in a step 302, the web tension S1 is determined in the section 111 by means of the measuring device 210. Based on the rotational speeds n0 and n1 of the transport section 200, 200 ', 201, 201' delimiting the web section 111, an elongation d1 of the web section 111 is determined in a method step 303.

From the web tension S1 and the elongation d1 in the first web section 111, a modulus of elasticity E1 of the web in section 111 is determined in a step 304.

On the basis of the rotational speeds n1, n2 of the associated transport axes 201,..., 202 ', an elongation d2 of the web portion 112 is determined in a step 305. Since the elasticity modulus is not changed by the processing of the material web (not shown) carried out in the web section 112, a modulus of elasticity E2 of the web portion 112 can be set equal to the modulus of elasticity E1 of the web portion 111. From this, in a method step 306, a Web tension S2 of the web portion 112 to S2 = E2 x d2 determined.

In web section 113, a processing of the web takes place in such a way that a change in the web cross-section is brought about. The web section A3 in the web section 113 thus differs from the web cross section A2 in section 112.

In a method step 307, an elongation d3 in the material web section 113 is determined on the basis of the rotational speeds n2 and n3 of the associated transport axes 202,... 203 '. In a method step 308, a modulus of elasticity E3 of the web section 113 is determined on the basis of the cross sections A3 and A2 and the modulus of elasticity E2 to E3 = E2 × A3 / A2.

In a method step 309, a web tension S3 of the web section 113 is determined on the basis of the elongation d3 and the modulus of elasticity E3 of the web section 113 to S3 = E3 × d3.

A web tension S4 in the web section 114 is determined on the basis of drive torques of the respective transport axes. In a method step 310, a drive torque NA3 of the transport axis 203 is determined for this purpose. Since a diameter D3 of the drive axle 203 is conventionally known constructively, in a method step 311 the web tension SA3 fed from the drive axle 203 is determined to be SA3 = 2NA3 / D3 by means of the lever law on the basis of the drive torque NA3 and the diameter D3.

Finally, in a method step 312, a web tension S4 of the web section 114 is determined to S4 = S3-SA3 on the basis of the determined web tension S3 and the determined web web tension SA3. If the transport axis 203 is operating in the motor area, the result is a positive drive torque NA3, whereas if it is operating in the regenerative range, the result is a negative drive torque NA3.

In determining the web tension based on the drive torque is disadvantageous that machining forces affect the web tension, friction moments by non-driven guide rollers affect the web tension, friction torques by the transport rollers affect the web tension, the measurement of the drive torque is often inaccurate, since the drive torque often by measuring the torque-forming current and multiplication of the torque constant of the motor is determined, in particular, the knowledge of the torque constant is subject to strong manufacturing variations, and the measurement of the drive torque in the drive is often subjected to highly fluctuating values. These disadvantages can be counteracted by the abovementioned developments of the method according to the invention, whereby the accuracy of this determination is improved.

In a method step 313, the actual web tension values S1 to S4 are compared with the desired web tension values. Deviations are compensated by measures known in the prior art (speed change of the transport axis, etc.). In order to the proposed solution can be used advantageously in conjunction with the regulation of web tension.

The method ends in a step 314.

reference numeral

100

processing machine

101

web

111, 112, 113, 114

Web sections

200, 201, 202, 203, 204,

drive roller

200 ', 201', 202 ', 203', 204 '

Backing roll

n0, ..., n4

speeds

E1, ..., E4

elastic moduli

A1, ..., A4

cross sections

S1, ..., S4

Web tension

NA3

drive torque

D3

diameter

SA3

fed web tensioning

V

transport direction

301, ..., 314

steps

Claims (21)

Method for determining a web tension (S2, S3, S4) of at least one second web tension section (112, 113, 114) in a web (101) having at least two web tension sections (111, 112, 113, 114), the web tension (S1) at least a first (111) web tension section is determined,
characterized in that
the web tension (S2, S3, S4) of the at least one second web tension section (112, 113, 114) is determined on the basis of the determined web tension (S1) of the at least one first web tension section (111). A method according to claim 1, characterized in that the web tension (S1) of the at least one first web tension section (111) is measured. A method according to claim 1, characterized in that the web tension (S1) of the at least one first web tension section (111) is determined taking into account a modulus of elasticity (E1) of the web material and a rotational speed (n0, n1) of at least two transport axes. A method according to claim 1, characterized in that the web tension (S1) of the at least one first web tension section (111) is determined taking into account a known web tension value and a drive torque of at least one transport axis (200). Method according to one of the preceding claims, characterized in that the web tension (S2, S3, S4) of the at least one second web tension section (112, 113, 114) is determined from a rotational speed (n1, n2, n2, n3, n3, n4) of at least two Transport axes (201, 202, 202, 203, 203, 204) is determined. A method according to claim 5, characterized in that the change of an elongation property, in particular a modulus of elasticity (E1, E2, E3, E4), the web (101) is taken into account. A method according to claim 6, characterized in that for the elastic modulus (E1, E2, E3, E4) one of a first cross section (A1, A2, A3, A4) of the web (101) in a web tension section (111, 112, 113, 114 ) deviating second cross-section (A1, A2, A3, A4) of the web (101) in another web tension section (111, 112, 113, 114) linearly with the ratio of the first to the second cross section (A1, A2, A3, A4) considered becomes. Method according to one of claims 5 to 7, characterized in that a slippage of the transport axes (200, 201, 202, 203, 204) is taken into account by estimation or by measuring the slip. Method according to one of claims 1 to 4, characterized in that the web tension (S2, S3, S4) of the at least one second web tension section (112, 113, 114) based on a drive torque (NA3) at least one transport axis (201, 202, 203, 204) is determined. A method according to claim 9, characterized in that the drive torque (NA3) based on a diameter (D3) of the at least one transport axis (201, 202, 203, 204) by means of a lever law in a web tension-changing force (FA3) is converted. A method according to claim 9 or 10, characterized in that a friction torque of at least one transport axis (201, 202, 203, 204), in particular with a constant and a speed-proportional component, or a predetermined by a speed-dependent characteristic portion is taken into account. A method according to claim 11, characterized in that the friction torque of the at least one transport axis (201, 202, 203, 204) is determined by means of a manual, semi-automatic or fully automated test drive. Method according to one of claims 9 to 12, characterized in that a machining torque, in particular with a constant and a speed-proportional component, or a predetermined by a speed-dependent characteristic portion is taken into account. Method according to one of claims 9 to 13, characterized in that a measurement of the drive torque (NA3) is performed by filtering the measured moments, the determined friction and / or the machining forces. Method according to one of claims 9 to 14, characterized in that in a measurement of the drive torque (NA3), a calibration of drive data, in particular a torque constant of the engine, is taken into account. A method according to claim 15, characterized in that the drive data are determined by means of a manual, semi-automated or fully automated test drive. Method according to one of claims 9 to 16, characterized in that a field weakening operation of an engine is taken into account in the determination of the drive torque. Arithmetic unit for determining the web tension (S2, S3, S4) of the at least one second web tension section (201, 202, 203, 204) on the basis of the web tension (S1) determined in the first web tension section (111) according to one of claims 1 to 17. Computer program with program code means for determining the web tension (S2, S3, S4) of at least the at least one second web tension section (112, 113, 114) on the basis of the web tension (S1) determined in the first web tension section (111) according to one of claims 1 to 17 to determine when the computer program on a computer or a corresponding processing unit, in particular according to claim 18, is executed. Computer program product with program code means, which are stored on a computer-readable data carrier, for determining the web tension (S2, S3, S4) of the at least one second web tension section (112, 113, 114) on the basis of the web tension (S1) determined in the first web tension section (111). according to one of claims 1 to 17, when the computer program product is executed on a computer or on a corresponding computing unit, in particular according to claim 18. Use of a method according to one of claims 1 to 17 in conjunction with a web tension control.

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