METHOD FOR CUTTING CIRCUITS WITH A PREDEFINED TARGET CONTAINMENT AND TEMPERATURE COMPENSATION

Description

[0001] The invention relates to a method for cutting circuit boards with a predetermined target contour according to the preamble of claim 1.

[0002] Such a procedure is known, for example, from WO 2016 / 135350 A1.

[0003] In the known process, sheet metal blanks or blanks are cut from a sheet metal strip continuously transported in one direction using several laser cutting units arranged in series. Each laser cutting unit produces a partial cut along a predefined cutting path. The cutting path is defined by cutting path coordinates. In practice, the sheet metal strip may not be transported exactly in the transport or x-direction. Consequently, it is necessary to correct the cutting path coordinates. For this purpose, the coordinates of a point on the surface of the sheet metal strip are determined with respect to a reference point. Furthermore, a displacement measuring device is provided to measure the transport path of the sheet metal strip in order to determine the cutting path coordinates to be corrected.

[0004] The known method allows for a relatively precise correction of the cutting path, so that the ends of the partial cuts surrounding a circuit board blend into one another with a high degree of accuracy. Post-processing of the circuit board in the area of ​​overlapping ends of partial cuts can be carried out with significantly reduced effort using this known method.

[0005] Previously, laser cutting processes were typically used to produce aluminum or steel sheets from a continuously transported strip of sheet metal. Any necessary post-processing of such sheets was possible with reasonable effort. This was not so easily possible with high-strength sheets.

[0006] Recently, there has been a requirement to produce sheet metal parts whose contour corresponds exactly to a specified target contour, at least in sections.

[0007] The object of the invention is to eliminate the disadvantages of the prior art. In particular, a method for manufacturing circuit boards that correspond almost exactly to a predetermined target contour is to be provided.

[0008] This problem is solved by the features of claim 1. Advantageous embodiments of the invention result from the features of the dependent claims. Definitions:

[0009] Transport path (xa): Feed path of the sheet metal strip in the transport or x-direction. The transport path xa is formed from successive transport path data. The transport path data is calculated using a first algorithm (see below). Cutting path (xy): The cutting path xy is calculated from CAD data that describes the target contour of the blank. The calculation is performed using the first algorithm. Each transport path data is assigned exactly one pair of cutting path coordinates. The cutting path coordinate pair is used to control an xy motion device, e.g., a gantry to which a cutting laser is attached. The cutting path xy can also be divided into several cutting path segments to generate partial cuts. In this case, the respective cutting path segments can be cut using different cutting lasers.For example, a first cutting path segment can be cut using a first cutting laser, and a second cutting path segment can be cut using a second cutting laser located downstream of the first. Laser cutting device (LS): comprises at least one cutting laser mounted on an xy-movement device and movable in the x-direction and a perpendicular y-direction by computer control. Working area (A1, A2): xy-range in which a cutting laser can generate cutting paths or cutting path segments. Reference temperature (TR): temperature at which the circuit board has the specified target contour, for example, the temperature of a measuring chamber in which the target contour of the circuit board is measured. First current temperature (T1): current temperature of the sheet metal strip; preferably, the first current temperature is measured upstream of a cutting laser of the laser cutting device.First algorithm: Calculates the transport path (xa) and xy values ​​describing the cutting path from CAD data and process parameters. Second algorithm: Calculates corrected xy values ​​from the xy values ​​and the initial current temperature (T1), which are provided to the xy motion device for moving the cutting laser along a corrected cutting path (xy-corr). Third algorithm: Calculates a corrected transport path (xa-corr) from the transport path (xa) and the initial current temperature (T1). x and y measuring device (LX1, LX2, LY1, LY2): Device for determining the position or measuring the distance of a cutting laser in the x or y direction, e.g., a linear measuring device with a glass rod. x- and y-reference points (RX1, RX2, RY1, RY2): predefined reference point of the x- and y-measuring device, e.g., the mounting point of the x- and y-measuring device on a machine frame. Machine frame: frame to which the laser cutting device is attached.Machine frame reference point (MRP): a predefined reference point on the machine frame. Second current temperature (T2): the temperature measured in the area of ​​the laser cutting unit. The measurement of the second current temperature serves to determine the temperature of the machine frame; it can be measured directly on the machine frame and / or indirectly in the vicinity of the machine frame. First calibration temperature (TK1): a predefined temperature at which the x and y measuring devices have a known distance relative to the machine frame reference point (MRP). Second / third calibration temperature (TK2 / TK3): device-specific temperatures for which distance measurements taken with the x measuring devices are calibrated. Fourth / fifth calibration temperature (TK4 / TK5): device-specific temperatures for which distance measurements taken with the y measuring devices are calibrated.Sixth calibration temperature (TK6): a predefined temperature at which a fixed point of a belt edge sensor has a known distance from the machine frame reference point (MRP). Seventh calibration temperature (TK7): a device-specific temperature for which a displacement measured with the measuring wheel is calibrated. Third actual temperature (T3): the temperature measured in the vicinity of the displacement measuring device. The measurement of the third actual temperature serves to determine the temperature of the displacement measuring device; it can be measured directly at the displacement measuring device and / or indirectly in the vicinity of the displacement measuring device. Target contour: The target contour is the outline of a single circuit board in top view. The target contour of a circuit board is usually defined by CAD data, which is provided as a data set. The target contour generally refers to a reference temperature of 20 °CD h.A circuit board conforms precisely to its target contour when it has a temperature of 20 °C.

[0010] Laser cutting systems for cutting circuit boards from a continuously transported strip of sheet metal are typically 5 meters or more in length. These systems are usually housed in large halls where the finished boards are conveyed away and temporarily stored. These halls are not usually maintained at a specific, predetermined temperature. They may have windows through which sunlight falls onto sections of the laser cutting system. Consequently, temperature variations can occur along the entire length of the laser cutting system. Sheet metal coils are often brought in from storage areas, which in turn have a temperature that differs from that of the laser cutting system.Overall, temperature fluctuations occur between the sheet metal coil and a downstream end of the sheet metal strip, which counteract the high-precision production of circuit boards with a predetermined target contour.

[0011] The proposed method was developed based on this finding. According to the invention, it is proposed that that the target contour is referenced to exactly one reference temperature of the circuit board, that a first current temperature of the sheet metal strip is measured, that in order to produce the target contour the cutting path is corrected in a second algorithm as a function of the first current temperature with respect to the reference temperature into a corrected cutting path, and that the transport path of the sheet metal strip is corrected in a third algorithm as a function of the first current temperature with respect to the reference temperature into a corrected transport path.

[0012] According to the inventive method, the desired contour is defined by a specific, predetermined reference temperature. This reference temperature can, for example, be the temperature at which the desired contour is defined by the CAD data. This could, for example, be 20 °C.

[0013] The first algorithm generates cutting path coordinates or machine coordinates from the CAD data, describing the cutting path (xy). Corresponding transport path data is also generated, describing the transport path or a target transport path. Advantageously, the first algorithm results in a table in which each transport path data point is assigned its corresponding xy values. Each transport path data point has a predefined interval with respect to the next. Interpolation is performed between two consecutive transport path data points with respect to their corresponding xy values.

[0014] According to the invention, a first current temperature of the sheet metal strip is measured. Using a second algorithm, the cutting path coordinates (xy) describing the cutting path, or the cutting path itself (xy), are then corrected to a corrected cutting path (xy-corr) as a function of the first current temperature relative to the reference temperature. For example, a circuit board contour produced at a temperature of 30 °C according to the corrected cutting path is larger than the target contour. Only when such a circuit board is cooled to the reference temperature does its dimension change so that it corresponds to the target contour.

[0015] According to a further provision of the invention, the transport path of the sheet metal strip is corrected into a corrected transport path according to a third algorithm, depending on the first current temperature relative to the reference temperature. This takes into account the fact that the sheet metal strip changes in length upstream of the laser cutting device due to a temperature deviation from the reference temperature. Because of the correction of the transport path data described by the invention, it is ensured that the required cuts can actually be performed within a working area of ​​the laser cutting device. Without the proposed correction of the transport path, it is possible that cuts or partial cuts may shift within the laser cutting device, and thus the desired cuts or partial cuts may no longer be possible within the respective working area.

[0016] Correcting the cutting path and further correcting the transport path enables the production of a circuit board that precisely matches the specified target contour. Using the proposed method, a large number of such circuit boards can be produced very efficiently from a continuously moving strip of sheet metal.

[0017] According to an advantageous embodiment, the laser cutting device can have a first working area, wherein the first working area has a first x-measuring device for determining an x-position of a first cutting laser, wherein a first x-reference point is assigned to the first x-measuring device, wherein a second current temperature is measured in the area of ​​the laser cutting device, and wherein an x-distance between the first x-reference point and a machine frame reference point is corrected as a function of the second current temperature with respect to a predetermined first calibration temperature.

[0018] A laser cutting device comprises a first cutting laser, which is mounted, for example, on a gantry. The gantry allows the first cutting laser to be moved back and forth in the x- and y-directions within a first working area. The laser cutting device also includes a housing in which the at least one cutting laser is located. The housing primarily serves to prevent unwanted laser beams from escaping into the environment. Due to the housing, the temperature inside the laser cutting device can differ from that in the surrounding environment. Consequently, temperature-related deviations also occur within the laser cutting device, particularly regarding the positioning of the cutting lasers. To correct for such deviations, it is proposed to measure a second, current temperature within the laser cutting device. The position of a cutting laser in the x-direction is measured by a first x-measuring device.The x-measuring device is fixedly connected to the machine frame at one point. A machine frame reference point is defined on the machine frame. The distance between the machine frame reference point and the mounting point of the x-measuring device on the machine frame is precisely known for a first calibration temperature. The x-measuring device measures x-values ​​precisely when the first calibration temperature is present. Changes in the distance resulting from a second current temperature that deviates from the first calibration temperature are compensated according to the proposed advantageous embodiment by correcting the x-distance between the first x-reference point and a machine frame reference point as a function of the second current temperature relative to the predetermined first calibration temperature.

[0019] The laser cutting device can have not only one cutting laser, but also several cutting lasers. Advantageously, the laser cutting device has a second working area downstream of the first working area, wherein the second working area has a second x-measuring device for determining an x-position of a second cutting laser, wherein a second x-reference point is assigned to the second x-measuring device, and wherein an x-distance between the second x-reference point and the machine frame reference point is corrected as a function of the second current temperature with respect to the first calibration temperature.

[0020] Apart from the first calibration temperature, each x-measuring device has a device-specific calibration temperature for which the x-values ​​supplied by the respective x-measuring device are valid. If x-measuring devices are located at a temperature that deviates from their respective device-specific calibration temperature, the x-values ​​supplied by them must be corrected. For example, if a linear scale is used as an x-measuring device, one length of the linear scale is calibrated to a second calibration temperature.Accordingly, it is advantageously proposed that the first x-measuring device has a predetermined second calibration temperature and is corrected with respect to the second calibration temperature using the second actual temperature, and / or that the second x-measuring device has a predetermined third calibration temperature and is corrected with respect to the third calibration temperature using the second actual temperature.

[0021] The proposed corrections to the x-measuring device(s) contribute to a particularly precise production of circuit boards according to the target contour.

[0022] In accordance with the proposed corrections for the x-measuring devices, first and / or second y-measuring devices can advantageously also be corrected analogously. For this purpose, the first working area can have a first y-measuring device for determining the y-position of a first cutting laser, wherein a first y-reference point is assigned to the first y-measuring device, and wherein a y-distance between the first y-reference point and the machine frame reference point is corrected as a function of the second current temperature relative to the first calibration temperature. According to the proposed embodiment, the first y-measuring device is corrected analogously to the first x-measuring device with respect to its first y-reference point and the machine frame reference point as a function of the second current temperature relative to the first calibration temperature.

[0023] Advantageously, the second working area has a second y-measuring device for determining a y-position of the second cutting laser, wherein a second y-reference point is assigned to the second y-measuring device, and a y-distance between the second y-reference point and the machine frame reference point is corrected depending on the second current temperature with respect to the first calibration temperature.

[0024] Analogous to the x-measuring devices, the y-measuring devices can also have device-specific calibration temperatures for which they deliver precise y-measurements. If there is a deviation from these specific calibration temperatures, the delivered y-measurements must be corrected. Advantageously, the first y-measuring device has a predefined fourth calibration temperature, and the first y-measuring device is corrected with respect to the fourth calibration temperature using the second current temperature, and / or the second y-measuring device has a predefined fifth calibration temperature, and the second y-measuring device is corrected with respect to the fifth calibration temperature using the second current temperature. This enables particularly precise manufacturing of circuit boards according to their specified target contour.

[0025] In a further advantageous embodiment, several temperature sensors are used to measure one or more of the current temperatures, and the current temperature is an average value derived from the measurements taken by the temperature sensors. This further increases the precision of the proposed method.

[0026] According to a further advantageous embodiment, strip edge sensors are provided for detecting the y-positions of the edges of the sheet metal strip, wherein the strip edge sensors are equipped with a device for adjusting the respective measuring position in the y-direction, and wherein the measuring positions of the strip edge sensors are corrected with respect to a sixth calibration temperature as a function of the second current temperature. Strip edge sensors typically have a relatively small measuring range. Their measuring position can be adjusted by means of a device for adjusting the respective measuring position in the y-direction. The term "measuring position" is understood to mean a fixed point of the respective strip edge sensor with respect to the machine frame reference point. The measuring positions of the strip edge sensors can advantageously be corrected with respect to the sixth calibration temperature as a function of the second current temperature. That is to say,The distance between the machine frame reference point and the respective measuring position in the y-direction is corrected depending on the second current temperature with respect to the sixth calibration temperature.

[0027] Advantageously, the actual transport path is measured using a displacement measuring device, and this actual transport path is used as the reference value for controlling the transport path. For example, a measuring wheel is used as the displacement measuring device, with one diameter of the measuring wheel being corrected relative to a predetermined seventh calibration temperature based on a third, current temperature. To correct the x-values ​​supplied by the measuring wheel, a third, current temperature of the measuring wheel is measured. The diameter of the measuring wheel is corrected relative to a seventh calibration temperature specified for the measuring wheel. This ensures that the x-values ​​supplied by the measuring wheel are corrected for temperature fluctuations.

[0028] The first and / or third current temperature is / are expediently measured upstream of the laser cutting device. This allows temperature differences along a laser cutting line to be taken into account.

[0029] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. The drawings show: Fig. 1 a schematic overview of the essential components of a laser cutting system, Fig. 2 a schematic overview of a laser cutting system with strip edge sensors, Fig. 3 a block diagram, and Fig. 4 a schematic representation of the effect of the method according to the invention.

[0030] Fig. 1 and Fig. 2 The schematic diagram shows components of a laser cutting system. Reference numeral 1 (see...) Fig. 2 ) is a sheet metal strip which is continuously transported in an x- or transport direction.

[0031] A conveyor (not shown here) can be used to transport the sheet metal strip 1, located upstream of a displacement measuring device 2. The conveyor could be, for example, a roll straightening machine or a roll feeder. The displacement measuring device 2 could be, for example, a measuring wheel.

[0032] A circuit board P (see Fig. 2 ), which is shown downstream of a laser cutting device LS, has a rectangular contour.

[0033] The laser cutting device LS comprises a first cutting laser L1, which is mounted on a first gantry 3 (not shown) and is movable in the x and y directions. The first cutting laser L1 can be moved in the x and y directions within the first working area A1. A first x-measuring device LX1, which can be, for example, an optical measuring device with a linear scale, is provided to determine the x-position of the first cutting laser L1. The first x-measuring device LX1 is attached to a machine frame (not shown) at a first x-reference point RX1. A first y-measuring device LY1, which is attached to the machine frame (not shown) at a first y-reference point RY1, is provided to measure the first y-position of the first cutting laser L1.

[0034] Downstream of the first cutting laser L1, a second cutting laser L2 is provided, which, analogous to the first cutting laser L1, can be moved back and forth in the x and y directions by means of a second gantry 4 in a second working area A2. A second x-measuring device is designated with the reference symbol LX2 and a second x-reference point with the reference symbol RX2. A second y-measuring device is designated with the reference symbol LY2 and a second y-reference point with the reference symbol RY2. A machine frame reference point is designated with the reference symbol RMG.

[0035] In Fig. 2 The strip edge sensors are shown in more detail. The sheet metal strip 1 has a first strip edge BK1 and a second strip edge BK2. Upstream of the first working area A1, a first stationary strip edge sensor L1SR is provided, and between the first working area A1 and the second working area A2, a second stationary strip edge sensor L2SR is provided. Within the first working area A1, a first moving strip edge sensor L1MR is provided, which is displaceable along a first positioning axis P1 in the y-direction. Within the second working area A2, a second moving strip edge sensor L2MR is provided, which is displaceable along a second positioning axis P2 in the y-direction.

[0036] The belt edge sensors L1SR, L2SR, L1MR, and L2MR shown here are each only shown for the first belt edge BK1. For clarity, the additional belt edge sensors opposite each other, used to determine the position of the second belt edge BK2, have been omitted.

[0037] The procedure will now be carried out in conjunction with the one in Fig. 3 The block diagram shown explains this in more detail.

[0038] The target contour of a circuit board P to be manufactured is initially defined by CAD data. A corresponding data set of CAD data is passed to a first algorithm. Furthermore, process data, such as the thickness of a sheet to be cut, a cutting speed, material properties, a maximum transport path, a maximum sheet width, and the like, are passed to the first algorithm. Based on this data, a transport path xa and cutting path coordinates xy are calculated using the first algorithm. The cutting path coordinates xy are control data for controlling the movements of the first cutting laser L1 and the second cutting laser L2 by means of their respective gantries 3 and 4. According to the invention, the cutting path coordinates xy generated by the first algorithm are then corrected in a second algorithm.The first measured temperature T1 and the reference temperature TR, for which the target contour applies, are used. The second algorithm provides a corrected cutting path xy-corr or corrected cutting path coordinates, which are used to control the motion devices or gantries 3, 4 that move the cutting lasers L1, L2.

[0039] According to the invention, the xa values ​​are further corrected in a third algorithm together with the reference temperature TR and the measured first current temperature T1. The third algorithm provides a corrected transport path xa-corr. The conveyor device for conveying the sheet metal strip 1 in the x-direction is controlled by means of the corrected transport path xa-corr.

[0040] Fig. 4This schematically illustrates the influence of correcting the transport path in the x-direction. The figure shows the case where an uncorrected transport path xa is smaller than a corrected transport path xa -corr. The cutting paths indicated by dashed lines refer to the transport path xa, and the corrected cutting paths indicated by solid lines refer to the corrected transport path xa -corr.

[0041] The example shown clearly demonstrates that if there is a deviation from one or more reference temperatures, the uncorrected cutting paths result in a cutting contour that deviates significantly from the target contour.

[0042] According to the invention, to improve the accuracy of a target contour to be produced, a corrected cutting path and a corresponding corrected transport path are calculated as a function of the first current temperature. To further improve the method, x- and / or y-measuring devices can be corrected with respect to their calibration temperatures based on a second current temperature. Furthermore, the position of the x- and / or y-measuring devices within the working ranges can be corrected with respect to the second current temperature. In this respect, temperature-induced geometric deformations of a machine frame on which the x- and / or y-measuring devices are mounted are taken into account.

[0043] In practice, during the transport of the sheet metal strip 1 in the x-direction, it can happen that the strip 1 moves back and forth in the y-direction. Such movement can be caused, for example, by a warping of the sheet metal strip 1. To correct the cutting path data xy or xy-corr in this respect as well, the measuring positions of the strip edge sensors L1, L2 can be changed depending on the second current temperature. This allows the current position of the strip edge BK to be measured precisely. The measured values ​​of the current position of the strip edge BK can be used to correct the cutting path coordinates xy or the corrected cutting path coordinates xy-corr. This further increases the accuracy of the proposed method. Reference symbol list

[0044] 1. Sheet metal strip 2-way measuring device 3. First gantry 4. Second gantry A1 First working area A2 Second working area BK1 First strip edge BK2 Second strip edge L1 First cutting laser L1M First moving strip edge sensor L2 Second cutting laser L2M Second moving strip edge sensor L1S First stationary strip edge sensor L2S Second stationary strip edge sensor LS Laser cutting device LX1 First linear scale LX2 Second linear scale LY1 First y-measuring device LY2 Second y-measuring device PPlatform P1 First positioning axis P2 Second positioning axis RX1 First x-reference point RX2 Second x-reference point RY1 First y-reference point RY2 Second y-reference point xa Transport path xa -corrected transport path xactual transport path

Claims

1. Method for cutting blanks (P) with a predetermined target contour from a sheet metal strip (1) transported continuously in a transport direction (x), comprising the following steps: providing a data set describing the target contour, calculating a transport path (xa) and a corresponding cutting path (xy) using a first algorithm, continuous transportation of the sheet metal strip (1) by means of a conveyor to a laser cutting device (LS) arranged downstream, cutting the blank along at least one cutting path (xy) from the sheet metal strip (1) by means of the laser cutting device (LS), characterized in that the target contour is related to exactly one reference temperature (TR) of the blank (P), a first current temperature (T1) of the metal strip (1) is measured, the cutting path (xy) is corrected in a second algorithm as a function of the first current temperature (T1) with respect to the reference temperature (TR) into a corrected cutting path (xy-corr) in order to produce the desired target contour, and the transport path (xa) of the sheet metal strip (1) is corrected into a corrected transport path (xa-corr) according to a third algorithm as a function of the first current temperature (T1) with respect to the reference temperature (TR).

2. Method according to claim 1, wherein the laser cutting device (LS) has a first working area (A1), wherein the first working area (A1) has a first x-measuring device (LX1) for determining an x-position of a first cutting laser (L1), wherein a first x-reference point (RX1) is assigned to the first x-measuring device (LX1), wherein a second current temperature (T2) is measured in the region of the laser cutting device (LS), and wherein an x axis distance between the first x-reference point (RX1) and a machine frame reference point (RMG) is corrected as a function of the second current temperature (T2) with respect to a predetermined first calibration temperature (TK1).

3. Method according to claim 2, wherein the laser cutting device (LS) has a second working area (A2) downstream of the first working area (A1), wherein the second working area (A2) has a second x-measuring device (LX2) for determining an x-position of a second cutting laser (L2), wherein a second x-reference point (RX2) is assigned to the second x-measuring device (LX2), and wherein an x axis distance between the second x-reference point (RX2) and the machine frame reference point (RMG) is corrected as a function of the second current temperature (T2) with respect to the first calibration temperature (TK1).

4. Method according to claim 2 or 3, wherein the first x-measuring device (LX1) has a predetermined second calibration temperature (TK2) and is corrected with respect to the second calibration temperature (TK2) using the second current temperature (T2) and / or the second x-measuring device (LX2) has a predetermined third calibration temperature (TK3) and is corrected with respect to the third calibration temperature (TK3) using the second current temperature (T2).

5. Method according to any one of claims 2 to 4, wherein the first working area (A1) comprises a first y-measuring device (LY1) for determining a y-position of a first cutting laser (L1), wherein a first y-reference point (RY1) is assigned to the first y-measuring device (LY1), and wherein a y axis distance between the first y-reference point (RY1) and the machine frame reference point (RMG) is corrected as a function of the second current temperature (T2) with respect to the first calibration temperature (TK1).

6. Method according to any one of claims 3 to 5, wherein the second working area (A2) comprises a second y-measuring device (LY2) for determining a y-position of a second cutting laser (L2), wherein a second y-reference point (RY2) is assigned to the second y-measuring device (LY2), and wherein a y axis distance between the second y-reference point (RY2) and the machine frame reference point (RMG) is corrected as a function of the second current temperature (T2) with respect to the first calibration temperature (TK1).

7. Method according to claim 5 or 6, wherein the first y-measuring device (LY1) has a predetermined fourth calibration temperature (KT4) and the first y-measuring device (LY1) is corrected with respect to the fourth calibration temperature (KT4) using the second current temperature (T2) and / or the second y-measuring device (LY2) has a predetermined fifth calibration temperature (KT5) and the second y-measuring device (LY2) is corrected with respect to the fifth calibration temperature (KT5) using the second current temperature (T2).

8. Method according to any one of the preceding claims, wherein several temperature sensors are used to measure one or more of the current temperatures (T1, T2) and an average value from the values measured with the temperature sensors is used as the current temperature (T1, T2).

9. Method according to any one of the preceding claims, wherein strip edge sensors (L1MR, L2MR) are provided for detecting the y-positions (Y1, Y2) of strip edges of the sheet metal strip (1), wherein the strip edge sensors (L1MR, L2MR) are provided with a device for adjusting the respective measuring position in the y axis direction, the measuring positions of the strip edge sensors (L1MR, L2MR) being corrected as a function of the second current temperature (T2) with respect to a sixth calibration temperature (TK6).

10. Method according to any one of the preceding claims, wherein an actual transport path (xt) is measured by means of a displacement measuring device (2) and the actual transport path (xt) is used as the actual value for controlling the transport path (xa).

11. Method according to claim 10, wherein a measuring wheel is used as the displacement measuring device (2), wherein a diameter (D) of the measuring wheel is corrected as a function of a third current temperature (T3) with respect to a predetermined seventh calibration temperature (TK7).

12. Method according to any one of the preceding claims, wherein the first current temperature (T1) and / or the third current temperature (T3) is measured upstream of the laser cutting device (LS).