DE102010056294A1 - Method for determining actual value of web tension in web tension sections of processing machine for processing material web, involves determining two actual values of web tension section - Google Patents

Abstract

The method involves determining two actual values (F-23,M-2) of the web tension section (23). The actual values are compared and an error of two investigations is detected when the actual values differ by more than a predetermined threshold or from the determined actual values to determine an outcome-value. An independent claim is also included for a computing unit.

Description

The present invention relates to a method for determining an actual value of the web tension in a web tension section of a processing machine for processing a web.

Although the invention is described below essentially with reference to printing presses, it is not limited to such an application, but rather can be used in all types of machine tools in which a tension of a web or material web is to be determined. The web can be made of paper, cloth, cardboard, plastic, metal, rubber, in foil form, etc.

State of the art

The present invention relates to the field of web tension determination in processing machines. In processing machines, in particular printing machines, a web is moved along driven and non-driven rollers. The material web is simultaneously processed by means of usually driven processing devices, for example printed, punched, cut, folded, etc. In a processing machine, one or more processing registers (for example longitudinal registers, page registers) and / or the web tension are usually regulated in the prior art.

A driven roller may belong to a nip, which positively or non-positively clamps the web and therefore can impress a web tension in the web. In a printing machine, a nip, for example, from a printing unit, in which a frictional unit between the driven pressure cylinder, the impression roller and the material web is formed formed.

The web can be divided into web tension sections, wherein a web tension section is limited by two nips. Within a web tension section further driven and / or non-driven rollers may be arranged. Often the entire web is divided into several web tension sections, sometimes with different web tension setpoints. To maintain the setpoints usually a web tension control is used. In the regulation, the specification of a desired web tension is based on an actual web tension.

The measurement of the web tension is usually carried out by a suitable measuring devices, such. B. a load cell. In addition, it is, for example, from the DE 10 2005 058 810 A1 known to determine the web tension by calculation to save measuring devices. In both cases, there is a risk that the determined actual web tension value is faulty, which can lead to a disruption in the processing and / or damage to the product.

It is therefore desirable to improve the quality of web tension determination.

Disclosure of the invention

According to the invention, a method for determining an actual value of the web tension in a web tension section of a processing machine for processing a web according to claim 1 is proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

According to one aspect of the invention, the determination of a web tension is improved by introducing redundancy. For this purpose, at least two actual values are determined and compared. If, in the context of a plausibility check, an excessive deviation between the determined values is detected, it can be concluded, for example, that a malfunction of one of the determination methods has occurred. This avoids the danger of working with faulty actual values and thereby damaging the machine and / or the material. In particular, a creeping deterioration of the measurement quality, which conventionally remains undetected for a long time, can be detected early within the scope of the invention.

According to a further aspect of the invention, the determination of a web tension is improved by determining a web tension value of interest from a plurality of determined actual values, for example in order to reduce noise components. This improves the quality of web tension actual value based procedures, such as: B. a scheme. If the web tension is determined several times in a section, an improved measured value of the web tension actual value can be obtained by suitable combination of the multiple web tension actual values (eg averaging). This can then be used for a pure actual value display or also for regulations.

Preferably, at least one of the at least two actual values is determined by measurement and / or calculation. Appropriately, different methods are used.

In a preferred embodiment of the invention, the measurement or computationally determined for a web tension section Plotted voltage actual value by means of a calculated web tension actual value (or vice versa). For the computational determination, in particular those in the DE 10 2005 058 810 A1 described method, in which the web tension of a portion of the web tension of an adjacent portion and a drive torque is determined. If a frictional torque is also taken into account in the mathematical determination of the web tension, the accuracy of determination can be further increased. For the calculation then the torque corrected by the friction torque is used. The consideration of the friction torque can be done in different preferred embodiments. In this case, the friction torque can be modeled as a constant friction, speed-dependent friction (proportional to speed or by means of a predefinable, speed-dependent characteristic) and / or as a winding mass-dependent friction (proportional to the winding mass, which in turn depends on the diameter). If an oversized discrepancy now occurs between the metrological and calculated web tension actual value, it can be concluded that the measuring device is malfunctioning, the friction is outside the expected limits and / or the friction torque or the drive torque have been determined incorrectly.

An arithmetic unit according to the invention, for. As a control device of a printing press, is, in particular programmatically, adapted to perform a method according to the invention.

Also, the implementation of the invention in the form of software is advantageous because this allows very low cost, especially if an executing processing unit is still used for other tasks and therefore already exists. Suitable data carriers for the provision of the computer program are in particular floppy disks, hard disks, flash memories, EEPROMs, CD-ROMs, DVDs and the like. a. m. It is also possible to download a program via computer networks (Internet, intranet, etc.).

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 indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention is illustrated schematically by means of exemplary embodiments in the drawing and will be described in detail below with reference to the drawing.

figure description

1 shows a schematic representation of a trained as a printing machine processing machine with a determination scheme according to a first preferred embodiment of the invention.

2 shows a schematic representation of a trained as a printing machine processing machine with a determination scheme according to a second preferred embodiment of the invention.

In the figures, the same elements are provided with the same reference numerals and will be described only once for the sake of clarity.

In 1 is a schematic section of a printing press 10 represented, in which a material web 101 through four here as printing works 1 to 4 trained clamping points transported and processed. Between each two adjacent clamping points, a web tension section is formed. For example, a web tension section 12 through the printing units 1 and 2 limited, a web tension section 23 through the printing units 2 and 3 and a web tension section 34 through the printing units 3 and 4 , Instead of printing units can also rail transport axes, such as collection or withdrawal plant, be present. 1 is merely illustrative of a preferred embodiment of the invention. For this reason, o. E. in 1 Track voltage actual values only redundantly determined for one web tension section.

The printing machine also has here as load cells 121 and 122 trained web tension sensors for determining the web tension or the tensile force F ₁₂ , F ₂₃ in the respective web tension sections 12 respectively. 23 on. In the illustration shown, the web tension over the peripheral speeds v ₁ to v _{4 of} the printing units 1 to 4 set. For controlling or regulating the printing press 10 is a control unit 150 provided that is programmatically set up to carry out the invention.

In the context of a first embodiment of the invention, the web tension for the section 23 determined twice. In addition to the metrological determination by means of the load cell 122 there is a computational determination, starting from the actual web tension value F ₁₂ for the section 12 using a drive torque M ₂ for the printing unit 2 and a radius of the driven roller (lever law), a second actual value F _{23, M is} determined.

The following is with reference to 2 describes how in the context of a second embodiment of the invention, a redundant actual value determination for a web tension section can be done without measuring device. At the printing press 10 according to 2 are the web tension sections 12 and 34 each with a load cell 121 respectively. 123 to determine the web tension or the tensile force F ₁₂ , F ₃₄ equipped. Based on the metrological determination of the actual web tension values for the web tension sections 12 and 34 a two-fold computational determination of the actual web tension value takes place for the web tension sections 23 , starting from the actual web tension value F ₁₂ for the section 12 using a drive torque M ₂ for the printing unit 2 and a radius of the driven roller (lever law) a first actual value F _{23, M1 is} determined and based on the actual web tension value F ₃₄ for the section 34 using a drive torque M ₃ for the printing unit 3 and a radius of the driven roller (lever law), a second actual value F _{23, M2 is} determined.

As described in the introduction, the respective second actual value can be used to check the plausibility of the respective first actual value and / or to form a result actual value (for example by averaging).

The invention can preferably be used in web tension control in order to increase the quality of the actual values used. For adjusting the web tension, for example, in the web tension section 23 There are two known strategies. In the upstream strategy, the printing unit 2 (and optionally upstream printing units) and adjusted in the downstream strategy, the printing unit 3 adjusted. Increasing the speed of the front nip causes a reduction in web tension, and increasing the speed of the rear nip causes the web tension to increase. This also describes a positive and negative sense of control. The positive control sense thus corresponds to the control by means of the rear limiting nip as a control signal (downstream), since in this case causes an increase of the control signal at the same time an increase of the output signal. Conversely, an increase in the velocity of the front nip causes the web tension to decrease, so this behavior is described by the term negative control sense. To carry out the web tension control, the result actual values of a device for web tension control (tension controller) are within the control unit 150 fed. The tension controller controls the speeds v ₁ to v _{4 as a} function of the result actual values.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005058810 A1 [0006, 0012]

Claims (11)

Method for determining an actual value (F ₂₃ , F _{23, M} , F _{23, M1} , F _{23, M2} ) of the web tension in a web tension section ( 12 . 23 . 34 ) a processing machine ( 10 ) for processing a web ( 101 ), wherein for the web tension section ( 23 ) at least two actual values (F ₂₃ , F _{23, M} , F _{23, M1} , F _{23, M2} ) are determined, characterized in that the determined actual values (F ₂₃ , F _{23, M} ; F _{23, M1} , F _{23, M2} ) and an error of at least one of the at least two determinations is detected if the determined actual values (F ₂₃ , F _{23, M} ; F _{23, M1} , F _{23, M2} ) differ by more than a predetermined threshold value and / or in that a result actual value is determined from the determined actual values (F ₂₃ , F _{23, M} , F _{23, M1} , F _{23, M2} ). Method according to Claim 1, wherein at least one (F _{23, M} ; F _{23, M1} , F _{23, M2} ) of the at least two actual values is determined by calculation. Method according to claim 2, wherein the actual value (F _{23, M} ; F _{23, M1} , F _{23, M2} ) of a first web tension section ( 23 ) from the actual value (F ₁₂ , F ₃₄ ) of an adjacent second web tension section ( 12 ; 34 ) and a drive torque (M ₂ , M ₃ ) of a clamping point separating the web tension sections ( 2 ; 3 ) is determined. Method according to claim 3, wherein the actual value (F _{23, M} ; F _{23, M1} , F _{23, M2} ) of the first web tension section ( 23 ) additionally on the basis of a friction torque of the web tensioning portions separating nip ( 2 ; 3 ) is determined. The method of claim 4, wherein the friction torque includes a constant and / or speed-dependent portion. The method of claim 5, wherein the speed-dependent portion includes a proportion proportional to the speed and / or a characteristic-based portion. Method according to one of the preceding claims, wherein the at least two actual values (F ₂₃ , F _{23, M} ; F _{23, M1} , F _{23, M2} ) are determined by means of at least two different methods. Method according to one of the preceding claims, wherein at least one (F _{23, M} ; F _{23, M1} , F _{23, M2} ) of the at least two actual values is determined by measurement. Method according to one of the preceding claims, wherein one for a web tension section ( 23 ) measured actual value (F ₂₃ , F _{23, M} , F _{23, M1} , F _{23, M2} ) is compared with a calculated actual value (F _{23, M} , F _{23, M1} , F _{23, M2} ). Method according to one of the preceding claims, wherein a regulation of the web tension is carried out using the result actual value. Arithmetic unit ( 150 ), which is adapted to perform a method according to any one of the preceding claims.

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