Method for adjusting the web tension of a processing machine

Abstract

For adjusting the web tension of a processing machine for processing a continuous material, in particular a shaftless printing press, the continuous material is subdivided into at least two web-tension sections, with one web-tension section being limited by two clamping points; the web tension is adjusted in the at least two web-tension sections when the continuous material comes to a standstill.

Description

CROSS-REFERENCE TO A RELATED APPLICATION

The invention described and claimed hereinbelow is also described in German Patent Application DE 10 2007 053 527.0 filed on Nov. 9, 2007. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d).

BACKGROUND OF THE INVENTION

The present invention relates to a method for adjusting the web tension of a processing machine, an appropriate computer program, and an appropriate computer program product.

Although the text below refers mainly to printing presses, the present invention is not limited thereto, but rather is directed to all types of processing machines with which a continuous material and/or a material web is processed. The present invention may be used, in particular, with printing presses such as newspaper presses, jobbing presses, gravure presses, printing presses for packaging or currency, and processing machines such as bagging machines, envelope machines, or packaging machines. The continuous material may be paper, cardboard, plastic, metal, rubber, or foil, etc.

With processing machines, in particular printing presses, a continuous material is moved along by driven axles (web conveyance axles), such as tension rollers or feed rollers, and by non-driven axles, such as breaker rollers, guide rollers, drying rollers, or cooling rollers. The continuous material is simultaneously processed—e.g., printed on, punched, cut, folded, etc.—using processing axles, which are usually also driven.

The web tension of the continuous material is influenced via “clamping points”, which clamp the continuous material in a frictional, form-fit, or non-positive manner. Driven conveyance or processing units are typically involved. With a gravure press, a clamping point is typically formed by a printing unit, with which a frictional unit exists between the driven impression cylinder, the pressure roller, and the material web. The continuous material is subdividable into web-tension sections, with a web-tension section being limited by two clamping points. Further driven and/or non-driven axles may be located within a web-tension section. It is often possible to subdivide the entire web of continuous material into several web-tension sections, with also have different web-tension setpoint values.

After processing has started, the web tension changes in the individual web-tension sections until a static web-tension behavior sets in the machine after a certain period of time, i.e., until the web tension in the individual web-tension sections reaches a static value. This adjustment and/or “back and forth” process requires a certain amount of time, during which the processing machine mainly generates waste. The processing machine is unable to produce products of adequate quality until a static state has been reached.

DE 10 2006 004 307 A1 discloses a method that may shorten the time required for the start-up process. The action that is described involves equipping the individual web-tension sections with web-tension measuring devices and adjusting the web tension while the machine is running. The disadvantage of the method is that a certain amount of waste is still produced, and it is a complex procedure to adjust the web tension during processing, since, in particular, the angular position of the printing units must be taken into account in order to ensure that register is maintained.

SUMMARY OF THE INVENTION

The present invention is therefore based on the object of providing an improved method for adjusting the web tension, with which a stationary machine state may be attained more quickly and waste is reduced.

This object is attained via a new method for adjusting web tension, a computer program, and a computer program product having the features of the present invention. Advantageous refinements are the subject of the description below.

With the method according to the present invention for adjusting the web tension of a processing machine, in particular a shaftless printing press—the continuous material being subdividable into at least two web-tension sections, and one web-tension section being limited by two clamping points—the web tension is adjusted in the at least two web-tension sections when the continuous material comes to a standstill.

With the solution according to the present invention, it is possible to adjust the web-tension values—which become stable—as closely as possible to the eventual end state, even before the machine run is started. As a result, the period of time until a stationary machine state is reached may be shorted considerably, which results directly in a substantial reduction of waste. The values that set in when the machine is at a standstill may be determined, e.g., via formulations from previous production runs, via measuring the cylinder diameter and entering the diameter and/or setpoint web tensions, and/or via measurement runs with extrapolations or interpolations of the resultant web tensions.

With a preferred embodiment, the web tension in the web-tension sections is ascertained using measuring elements, preferably load cells, via the driving torque of at least one of the clamping points that limits this web-tension section, and/or via operators (control engineering).

Advantageously, the web tension in a web-tension section is adjusted by acting upon or displacing at least one clamping point that limits this web-tension section.

Expediently, the web tension in a web-tension section is adjusted via angular displacement, rate feedback, and/or limitation of the driving torque of at least one clamping point that limits this web-tension section.

Advantageously, the acting upon or adjustment of the at least one clamping point that is used to adjust the web tension cascades to further clamping points. It is particularly advantageous to cascade the action on the clamping point as a precontrol, and/or to cascade the associated precontrol values to adjacent clamping points, in order to decouple the adjacent web-tension sections from the affected web-tension section. The cascading may be carried out with different factors, e.g., inverse, proportional, percent, etc.

According to a preferred embodiment, the web tension in the at least two web-tension sections is adjusted in succession, following the course of the continuous material. The adjustment may follow the course of the continuous material starting with an infeed and ending with an outfeed, with the web tension being adjusted in the consecutive web-tension sections in succession. The adjustment may take place starting with the outfeed and ending with the infeed. With this method, the web tension in the entire machine may be adjusted quickly and easily.

Even though a preferred embodiment is described below with which the adjustment takes place from the infeed to the outfeed, following the course of the continuous material, it is understood that the method described may also be used to adjust the web tension against the course of the continuous material, from the outfeed to the infeed.

Expediently, to perform the inventive method, the continuous material is initially clamped via a first clamping point and a second clamping point. These may be, in particular, an infeed and an outfeed of the processing machine. Next, the web tension in the web-tension section between the first clamping point and the second clamping point is adjusted. The adjustment may preferably take place by rotating the infeed and/or the outfeed. Expediently, the web-tension value that will set in essentially corresponds to the value—that sets in—of the web tension between the infeed and the first printing unit after it, or, in general, between the first clamping point and the next clamping point along the course of the continuous material, which is referred to here as the third clamping point. The continuous material is then clamped via the third clamping point; the third clamping point along the course of the continuous material lies between the first clamping point and the second clamping point. Next, the second clamping point may be used to adjust the web tension along the course of the web tension between the third clamping point and the second clamping point. With this method, the web tension in at least two web-tension sections may be adjusted quickly and easily.

It is advantageous when a change in web tension—which results from the eventual clamping of the continuous material with the third clamping point—is taken into account when the web tension is adjusted in the web-tension section between the first clamping point and the second clamping point. Clamping the continuous material via a clamping point usually results in the continuous material becoming wrapped around the rollers, i.e., the distance covered by the material web changes, and usually becomes longer. This results in an increase in web tension. When this change in web tension is taken into consideration before the web-tension values stabilize, the intended web-tension value in the related web-tension section may be attained via the eventual clamping and resultant change in web tension.

The adjustment method described above may be expediently expanded by adjusting the web tension in the web-tension section between the first clamping point and the second clamping point. The continuous material is then clamped with a fourth clamping point, which is located between the first clamping point and the third clamping point along the course of the continuous material. It is understood that, with the refinement described above as well, the change in web tension induced by the subsequent clamping should be taken into account in the adjustment. With this method, the web tension in at least one further web-tension section may be adjusted quickly and easily.

The adjustment method described above may be expediently expanded by subsequently releasing the continuous material from the third clamping point and then clamping it at a fifth clamping point, which is located between the third clamping point and the second clamping point along the course of the continuous material. The web tension in the web-tension section between the fourth clamping point and the fifth clamping point is then adjusted. Finally, the continuous material is clamped with the third clamping point once more.

Finally, it is expedient to adjust the web tension in the web-tension section between the fifth clamping point and the second clamping point.

In combination with the method steps described in the paragraphs above, depending on the embodiment of the processing machine, it is possible to attain an adjustment of different web-tension values in at least four web-tension sections without the need to move the continuous material, which would result in waste. It is understood that the method steps described above may be combined and repeated in any order. The number of web-tension sections to be adjusted is therefore not limited with the method according to the present invention.

The method according to the present invention may be used particularly advantageously with a processing machine that is designed as a printing press, the clamping points being designed as an infeed, outfeed, and/or printing units.

Expediently, the web tension is adjusted in a web-tension section via the angular displacement of a clamping point that limits this web-tension section, the change in web tension in this web-tension section induced by this angular displacement is ascertained, and, based thereon, a physical property of the continuous material (101), in particular the elasticity module, is ascertained. It is therefore possible—in a particularly easy manner—to ascertain additional physical properties that are helpful for the operation of a printing press.

An inventive processing machine includes, in particular, all means for carrying out an inventive method.

The present invention also relates to a computer program with program code means for controlling a processing machine according to the present invention when the computer program is run on a computer or an appropriate arithmetic unit, in particular in a processing machine according to the present invention.

The computer program product—which is provided according to the present invention—with program code means, which are stored on a computer-readable data storage device, is designed to control—according to the present invention—a processing machine when the computer program is run on a computer or an appropriate arithmetic unit, in particular in a processing machine. Suitable data storage devices are, in particular, diskettes, hard drives, Flash drives, EEPROMs, CD-ROMs, DVDs, etc. It is also possible that a program could be downloaded from computer networks (Internet, intranet, etc.).

The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a processing machine designed as a printing press, based on which a preferred embodiment of the method according to the present invention is described.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A processing machine designed as a printing press is labeled as a whole with reference numeral 100 in FIG. 1. A material to be printed on, e.g., paper 101, is supplied to the machine via an infeed 110. Paper 101 is then guided through clamping points, which are designed as printing units 111, 112, 113, 114, and they are printed on, then output via an outfeed 115. The infeed, outfeed, and printing units 110 through 115 are located such that they may be positioned, in particular such that their cylinders or angles may be corrected. Printing units 111 through 114 are located in a web tension-controlled region between infeed 110 and outfeed 115.

Printing units 111 through 114 each include an impression cylinder 111′ through 114′, against each of which a pressure roller 111″ through 114″ is pressed with strong pressure. Impression cylinders 111′ through 114′ may be driven separately and independently of one another. Associated drives 111′″ through 114′″ are depicted schematically. Pressure rollers 111′″ through 114′″ are designed such that they may rotate freely. Infeed 110 and outfeed 115 each include two cylinders, which rotate in opposite directions and guide paper 101. Infeed 110 and outfeed 115 may also be driven separately by a drive 110′″ and 115′″. Infeed 110 and outfeed 115 and printing units 111 through 114 form—with paper 101 passing through them—one unit that is connected via a friction connection. Infeed 110, outfeed 115, and printing units 111 through 114 therefore each represent one clamping point.

In the web sections (web-tension sections) between individual printing units 111 through 114, paper 101 is initially guided via a few rollers, which are labeled 102 and are not explained in greater detail. For clarity, not every roller is labeled with reference numeral 102. The rollers may be, in particular, deflection rollers, drying rollers, cooling rollers, cutting devices, etc. In addition, detection devices for determining the web tension are provided in the web-tension sections. An arithmetic unit 200 is provided to control the printing press and to adjust the web tension.

The text below describes how, with the embodiment of the printing press presented here, the web tension is adjusted—starting with infeed 110 and ending with outfeed 115—according to a preferred embodiment of the present invention when the continuous material comes to a standstill.

Sensors (not depicted)—which determine the web tension of continuous material 101, and, for this purpose, are designed as load cells—are located in the individual web-tension sections between clamping points 110 through 115. The web-tension values to be adjusted may be determined in advance using a measurement run.

Starting at the state shown, when continuous material 101 is at a standstill, pressure rollers 111″ through 114″ are halted, i.e., continuous material 101 is released from clamping points 111 through 114, which are designed as printing units. The web tension in the entire machine is then set to a first basic value by infeed 110 and/or outfeed 115.

Pressure roller 112″ is then activated, i.e., the continuous material is clamped with printing unit 112. Via printing unit 112, the web tension in the web-tension region between infeed 110 and printing unit 112 is adjusted such that it corresponds to a desired web tension in the web-tension region between infeed 110 and first printing unit 111. The increase in web tension that eventually results via the clamping with printing unit 111 is already taken into consideration in the adjustment. The web-tension sensors check the adjusted web tension. The check may also take place by evaluating the driving torque of printing unit 112 or via observers that are commonplace in control engineering. Next, pressure roller 111″ of printing unit 111 is activated, and the process of adjusting the web tension in the web-tension region between infeed 110 and first printing unit 111 is therefore completed.

Next, pressure roller 112″ of printing unit 112 is halted again, in order to release continuous material 101 from printing unit 112. Pressure roller 113″ of printing unit 113 is then activated, in order to clamp the continuous material via printing unit 113. Using printing unit 113, the web tension that is to eventually exist in the web-tension section between printing unit 111 and printing unit 112 is adjusted in the web-tension section between printing unit 111 and printing unit 113, the change in web tension that results from the subsequent activation of pressure roller 112″ being taken into account once more. Next, pressure roller 112″ is activated, and, with this, the adjustment procedure for the web-tension section between printing unit 111 and printing unit 112 is ended.

The adjustment of the web tensions in the web-tension sections between printing units 112 and 113, and between 113 and 114 is carried out in the same manner. The desired web tension in the web-tension section between printing unit 113 and printing unit 114 is attained by displacing outfeed 115. After pressure roller 114″ is activated, i.e., after continuous material 101 is clamped with printing unit 114, the web tension in the last web-tension section between printing unit 114 and outfeed 115 is adjusted once more by adjusting outfeed 115.

It is understood that only one particularly preferred embodiment of the present invention is depicted in the figures shown. Any other type of embodiment is also feasible, without leaving the framework of the present invention.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of methods and constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a method for adjusting the web tension of a processing machine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Claims

1. A method of adjusting a web tension of a processing machine for processing a continuous material, comprising the steps of subdividing the continuous material into at least two web-tension sections; limiting one of the web-tension sections by two clamping points; and adjusting a web tension in the at least two web-tension sections when the continuous material comes to a standstill, further comprising ascertaining the web tension in the web-tension sections using measuring elements via a driving torque of at least one of the clamping points that limits the web-tension section, and/or via operators.

2. A method as defined in claim 1, wherein the method for adjusting the web tension of a processing machine for processing a continuous material is a method for adjusting the web tension of a processing machine which is a shaftless printing press.

3. A method as defined in claim 1, further comprising ascertaining the web tension in the web-tension sections using measuring elements via a driving torque of at least one of the clamping points that limits the web-tension section, and/or via operators.

4. A method as defined in claim 3, wherein said ascertaining the web tension includes using the measuring elements configured as load cells.

5. A method as defined in claim 1, wherein said adjusting includes adjusting the web tension in a web-tension section by acting on at least one of the clamping points that limits this web-tension section.

6. A method as defined in claim 1, said adjusting by acting on the at least one clamping point includes adjusting the web tension in the web-tension section via angular displacement, rate feedback, and/or limitation of a driving torque of the at least one clamping point that limits the web-tension section.

7. A method as defined in claim 1, further comprising cascading an action applied to at least one of the clamping points to further clamping points.

8. A method as defined in claim 1, wherein said adjusting of the web tension in the at least two web-tension sections includes adjusting in succession, following a course of the continuous material.

9. A method as defined in claim 1, further comprising clamping the continuous material at a first clamping point and a second clamping point, adjusting the web tension in a web-tension section between the first clamping point and the second clamping point, clamping the continuous material with a third clamping point located between the first clamping point and the second clamping point along a course of the continuous material.

10. A method as defined in claim 9, further comprising taking into consideration a change in the web tension when the continuous material is clamped via the third clamping point when the web tension is adjusted in the web-tension section between the first clamping point and the second clamping point.

11. A method as defined in claim 9, further comprising adjusting the web tension in a web-tension section between a first clamping point and the third clamping point, clamping the continuous material at a fourth clamping point located between the first clamping point and the third clamping point along the course of the continuous material.

12. A method as defined in claim 11, further comprising releasing the continuous material from the third clamping point, clamping the continuous material at a fifth clamping point located between the third clamping point and the second clamping point along the course of continuous material, adjusting the web tension in a web-tension section between the fourth clamping point and the fifth clamping point, and clamping the continuous material at the third clamping point.

13. A method as defined in claim 12, further comprising adjusting the web tension in a web-tension section between the fifth clamping point and the second clamping point.

14. A method as defined in claim 1, wherein the method for adjusting the web tension of a processing machine is performed in the processing machine configured as a printing press, and further comprising configuring the clamping points as printing units selected from the group consisting of an infeed printing unit, an outfeed printing unit, and other printing units.

15. A method as defined in claim 1, wherein said adjusting includes adjusting in a web-tension section via an angular displacement of one of the clamping points that limits this web-tension section, ascertaining a change in web tension in this web-tension section induced by the angular displacement, and, based thereon, ascertaining a physical property of the continuous material.

16. A method as defined in claim 15, wherein said ascertaining includes ascertaining an elasticity module of the continuous material.

17. A computer program with program code means for carrying out the method recited in claim 1 when the computer program is run on a device selected from the group consisting of a computer and an appropriate arithmetic unit.

18. A computer program product with program code means stored on a computer-readable data storage device for carrying out the method defined in claim 1 when the computer program is run on the device selected from the group consisting of a computer and an appropriate arithmetic unit.