DE102007030395A1 - Continuous laser beam welding of plate-shaped workpiece e.g. pipe along welding direction of workpiece, comprises detecting markings staggered to joint gap in workpiece in welding direction before and after the welded point at the workpiece - Google Patents

Abstract

The method for continuous laser beam welding of a plate-shaped workpiece (2) e.g. a pipe along a welding direction (3) of the workpiece, comprises detecting markings (14a, 14b) staggered to a joint gap (4) in the workpiece in welding direction before and after a welded point (5) at the workpiece, and determining an optimal welding position of the laser beam transverse to the welding direction from the position transverse to the welding direction of the detected markings before and after the welding point. A welding seam (6) and its seam geometry produced in the workpiece are detected. The method for continuous laser beam welding of a plate-shaped workpiece (2) e.g. a pipe along a welding direction (3) of the workpiece, comprises detecting markings (14a, 14b) staggered to a joint gap (4) in the workpiece in welding direction before and after a welded point (5) at the workpiece, and determining an optimal welding position of the laser beam transverse to the welding direction from the position transverse to the welding direction of the detected markings before and after the welding point. A welding seam (6) and its seam geometry produced in the workpiece are detected for marking in welding direction above the welding point to the joint gap and/or in welding direction below the welding point of the workpiece during welding. The laser beam is positioned at the determined welding position. The marking is applied on the workpiece by laser labeling or by spraying a coloring material before welding, deformation or bending process. The marking on the workpiece is applied as continuous marking or as discontinuous marking. Two markings are applied on opposite sides of the joint gap for determining the gap width of the joint gap. The determined gap width is used for regulating a device for clamping the workpiece transverse to the welding direction. An independent claim is included for a device for continuous laser beam welding of workpiece e.g. a pipe along a welding direction of the workpiece.

Description

The The present invention relates to a method for preferably continuous Laser beam welding of a workpiece, in particular of a pipe, along a welding direction along of the workpiece, wherein in the welding direction in front of a weld at least one to a joint gap on the workpiece in the workpiece offset mark is detected. The invention further relates to a device for preferred continuous laser beam welding of a workpiece, in particular a pipe, along a welding direction along the workpiece, comprising: a laser welding head for welding the workpiece to a weld, and a sensor unit for detecting at least one of Joint gap in the workpiece offset mark in the welding direction in front of the weld.

Such a method and such a device are known from DE 36 32 952 A1 known. In laser beam welding, the laser beam must be positioned at the welding point exactly in the middle of the joint gap to be welded. For this purpose, a sensor device for gap detection is usually arranged on the processing head leading to the laser beam or to the welding point, which detects the exact position of the joint gap, for example with the aid of the light section method. On the basis of the signal supplied by the sensor for gap detection, the positioning of the machining head transversely to the welding direction is regulated online during the welding process. Alternatively, as in the DE 36 32 952 A1 described, for determining the welding position transversely to the welding direction a parallel to the joint gap and laterally offset applied to this mark with a camera are detected as a sensor unit, whereby a measurement is made possible synchronously to the weld.

Continuous welding of profiles or tailored blanks can cause torsion or tension in the workpiece. This results in an inaccurate positioning of the laser beam transversely to the welding direction, if the distance between the sensor unit and the laser beam is so large that after the time of detection of the joining gap or the mark within the delay line Torsinnen or delay occur from the sensor unit are no longer detectable. To solve this problem, for example, in the JP 01181990 A and the JP 09182984 A proposed not only at one, but at two positions in the welding direction leading to the laser beam to determine the exact position of the joint gap, so as to calculate the influence of the torsion can.

Object of the invention

It is the object of the present invention, a method and a Device of the type mentioned in such a way that Welding defect due to tension or torsos be more easily detected and avoided in the workpiece can.

Subject of the invention

These The object is achieved according to the invention that the at least one mark also in the welding direction detected after the weld and out of the position across to the welding direction of the before and after the weld detected marking an optimal welding position of Laser beam is determined transversely to the welding direction. differs the actual welding position of the optimal Position off, for example, issued a warning and / or the process will be stopped. Preferably, with the aid of a control unit the laser beam is controlled at the determined welding position positioned.

According to the invention proposed, the applied mark (s) also in the welding direction to detect after the weld, as a sole Detection of the weld formed in the workpiece Weld after the weld no exact Positioning of the laser beam across the welding direction enabled: Only by detecting the weld is not apparent if the weld is actually runs exactly in the middle of the position of the joint or if there is a slight offset between joint gap and weld is present. By the detection of preferred two on opposite sides of the joint along the welding direction applied markings in the flow and caster to the weld or through the Detection of a mark on the one hand and the joining gap or the weld, on the other hand, is the exact one Determining the position of the joint gap across the welding direction also possible with the occurrence of torsion and / or tension. As a result, it is detected whether the position of the weld of the center of the joint gap deviates, so if a welding error is present, so that issued a warning and / or editing can be stopped. By regulating the positioning of the Laser beam based on the detected position of the markers and the Fügespalts or the weld can Welding errors are avoided.

In an advantageous variant of the method according to the invention, therefore, in addition to the marking in the welding direction in front of the welding point of the joint gap and / or in the welding direction after the weld, the welding in the workpiece he witnessed welded seam and preferably its seam geometry detected. In the detection of the weld seam and its seam geometry is preferably detected in terms of width of the seam, seam over-curvature or incidence, seam position offset with respect to the marking, as well as surface pores or holes.

at In an advantageous variant, the marking is made before the welding process applied to the workpiece, preferably on a plate-shaped workpiece before a subsequent forming process, in particular a subsequent Bending process. Especially when welding profiles it is advantageous if not already merged for welding Tube profile, but the plate-shaped band material before is marked as the deforming, as this is a well-defined Distance of the marking of the band edges is adjustable. alternative It is possible to mark during the welding process in the welding direction before the weld on the Apply workpiece.

at a particularly advantageous variant, the mark on the Workpiece as continuous marking or as interrupted Mark applied. If the mark is interrupted with a Applied pattern, z. B. as a dashed line can when detecting the mark additional information about the welding process can be won. So, for example at a known distance between two consecutive sections the mark a between the detection of the first and the second marking portion occurring time interval determines and thereby the feed rate of the workpiece or of the machining head are measured.

at In a further preferred variant, the marking is laser marking or by spraying a dye on the workpiece applied. Both methods allow the application of a label with high precision, without requiring mechanical parts must act on the workpiece.

at an extremely preferred variant to be Determine the gap width of the joint gap two markings Applied on opposite sides of the joint, wherein preferably the determined gap width for controlling a tensioning device for clamping the workpiece transversely to the welding direction is used. This can be the actual Gap width and possibly occurring gap widening determined What can be used to control component clamping devices.

The Invention is also realized in a device of the beginning mentioned type, which in addition a further sensor unit for detecting the mark in the welding direction the welding point and an evaluation unit for determining a welding position of the laser beam transverse to the welding direction from the position transverse to the welding direction of the before and after the weld has detected mark. Preferably The device further comprises a moving unit for moving the laser welding head or the laser beam relative to the workpiece transverse to the welding direction and a control unit for control the movement unit for positioning the laser beam on the determined welding position. By determining the location the marking leading transversely to the welding direction and trailing to the weld, the laser beam can also occur of torsion or tension in the workpiece in the center of the joint gap be positioned. This is either the entire laser welding head movably attached to the device, or the laser welding head is designed as a scanner welding head in which a positioning of the laser welding head via Scanner level is done.

at A preferred embodiment is the sensor unit for detecting the joining gap and / or the further sensor unit for detecting when welding to the workpiece formed weld and preferably of the seam geometry designed. This allows both the gap width of the Fügespalts determines as well as statements about the Quality of the weld can be made.

at A further advantageous embodiment is an in Welding direction arranged in front of the weld Marking device for applying at least one to the Joint gap in the workpiece offset mark intended. The marker brings the marker during the welding process on the workpiece which is already in welding direction for this process is aligned. Therefore, marking can be done in a simple way take place to the joint gap.

at An advantageous development is the marking device designed, the marking continuously or in a predetermined temporal Apply distances to the workpiece. Becomes applied a continuous mark, this ensures that these at any time during the welding process can be detected. But it is also possible to apply to interrupt the marking during short time intervals, whereby a pattern arises, which in the detection statements about the welding process, in particular via the feed rate of the workpiece or the machining head permits.

In a further advantageous development, the marking device is a laser marker processing unit or as a printing device with a nozzle for applying a dye. In both cases, the marking can be applied without this coming into contact with mechanical components, which could possibly cause tension in the workpiece.

at a particularly preferred embodiment is the marking device designed, two markings on opposite sides of the joining gap to apply to the workpiece, and the evaluation unit is designed from the distance of the markings transverse to the welding direction, the gap width of the joint gap to investigate. This can be a possibly occurring gap widening detected and measures for their correction can be initiated.

at A preferred embodiment is / are the sensor unit and / or the further sensor unit as a camera system with a light-section unit or an incident light unit. In a reflected light unit becomes the workpiece surface with light emitting diodes homogeneously illuminated, so that the position of the joint gap across to the welding direction at the location of the sensor unit using a camera can be measured. In a light section unit becomes a laser line on the workpiece surface projected, whereby the distance of the workpiece surface can be determined to the sensor unit. In both cases is used as a detector camera, z. B. a CCD camera or a CMOS camera.

at In a particularly preferred embodiment, the Device one in the welding direction in front of the weld arranged clamping device for clamping the workpiece transverse to the welding direction, their clamping force depending regulated by a determined gap width of the joint becomes. The gap width can hereby as shown above based on the Distance between two on opposite sides of the Fügespalts applied markings are determined. By imaging the joining gap by means of the sensor unit can The gap width can also be measured directly. It goes without saying that for checking the measurement results or for Increasing the accuracy both ways too can be used together.

Further Advantages of the invention will become apparent from the description and the Drawing. Likewise, the above and the even more features listed in each case or to several in any combination use. The shown and described embodiments are not to understand as a final list, but rather have exemplary character for the description the invention.

It shows:

figure a schematic representation of an embodiment of a Device according to the invention for laser welding on a tubular workpiece.

The figure shows a device 1 for continuous laser welding of a workpiece 2 in the form of a pipe. The workpiece 2 becomes in a welding direction 3 shifted, with one on the workpiece 2 formed joint gap 4 at a weld 5 under formation of a weld 6 is welded. At the weld 5 is the focal point of a on the workpiece 2 focused laser beam 7 that of a laser processing head 8th is produced. The laser processing head 8th is in the welding direction 3 fixedly arranged and by means of a movement unit indicated by a double arrow 9 transverse to the welding direction 3 movable. The movement unit 9 is required to the laser beam 7 even with a deviation of the joint gap 4 transverse to the welding direction 3 from an ideal situation 10 (dashed line) exactly in the middle of the joint gap 4 to position. This deviation is exaggerated in the figure for clarity.

In order to achieve such a central positioning, the position of the joining gap must be 4 transverse to the welding direction 3 at the location of the laser processing head 8th be determined.

This is in the welding direction 3 in front of the weld 5 a sensor unit 11 provided, which is designed as a camera system with light section unit. The sensor unit 11 However, the location of the gap can 4 only in one place in the welding direction 3 determine which is a distance to the weld 5 having. Occurs between the sensor unit 11 and the laser welding head 8th in welding direction 3 a torsion or tension in the workpiece 2 the laser beam hits 7 not exactly at the welding position P defining center of the joining gap 4 transverse to the welding direction 3 on the joint gap 4 and there is an offset (not shown) between the weld 6 and joint gap 4 ,

To avoid this problem, the device includes 1 another camera with light section unit as another sensor unit 12 in the welding direction 3 after the weld 5 is arranged, as well as a marking device 13 , which in welding direction 3 in front of the sensor unit 11 is arranged. The marking device 13 is designed as a laser marking unit and brings on both sides of the joint 4 offset to this and parallel to this one mark 14a . 14b on. The marks 14a . 14b be both from the sensor unit 11 leading to the weld 5 when also from the other sensor unit 13 trailing to the weld 5 detected.

The of the sensor units 11 . 12 supplied detection data are sent to one with the sensor units 11 . 12 related evaluation unit 15 transmitted and there to determine the location of the markings 14a . 14b transverse to the welding direction 3 evaluated. The evaluation unit 15 subsequently determines the lateral offset between the location of the marks 14a . 14b leading and trailing to the weld 5 as well as their relative position to the joining gap 4 and to the weld 6 , From this data, the location of the joint gap 4 transverse to the welding direction 3 on the laser processing head 8th be determined and the evaluation 15 can its movement device 9 such that the laser beam 7 exactly in the middle of the joint gap 4 is positioned at the welding position P. Through the two sensor units 11 . 12 , the evaluation unit 15 and the motion unit 9 Thus, a control loop for the online positioning of the laser beam 7 at the welding position P in the joint gap 4 formed during the welding process.

The further sensor unit arranged in the caster 12 In addition, the geometry of the weld can 6 in terms of their width, seam overhang or incidence, seam offset with respect to the markings 14a . 14b , surface pores, etc. determine and obtain additional information about the welding process, which can also be used to control the welding process, eg. B. by the power of the laser beam 7 or the feed rate in the welding direction 3 to be changed. Also, by taking a thermal image along the weld 6 Conclusions can be drawn on the quality of the weld.

At the arranged in the flow sensor unit 11 can the evaluation unit 15 the distance of the markings 14a . 14b transverse to the welding direction 3 and thereby the gap width of the joint gap 4 determine. If this deviates from a desired gap width, the clamping force, which is determined by a clamping device 16 on the workpiece 2 is exercised, adjusted until the desired gap width is reached.

Alternatively to the application of the markings shown in the figure 14a . 14b During the welding process, they can also be applied to the workpiece beforehand 2 be applied. So it is particularly advantageous in profile welding, if not the already merged for welding tube profile but the strip material is marked before deformation. In this way, a very well-defined distance of the markers from the strip edges can be set, which form the edges of the joint gap after a subsequent bending process.

Also as an alternative to the markings shown in the figure, applied as continuous lines 14a . 14b For example, the application of the markings can also be interrupted at predeterminable time intervals, so that marked and unmarked locations on the workpiece alternate and form a pattern, which also depends on the sensor units 11 . 12 can be detected to statements about the welding process, in particular about the feed rate of the workpiece 4 to obtain. Knowing this information can influence the welding process and, for example, regulate the feed rate.

It is understood that alternatively to the movement of the workpiece 2 in welding direction 3 with stationary laser processing head 8th also the workpiece 2 be arranged stationary and for welding the laser processing head 8th together with the sensor units 11 . 12 along the welding direction 3 can be moved. Also a combined movement of laser processing head 8th and workpiece 2 is possible. Furthermore, the device described above not only for profile welding, but also z. B. used for welding of tailored blanks. In any case, by detecting the mark (s) in the lead and wake of the weld 5 as well as the weld 6 and the joining gap 4 Welding errors avoided and an optimized control of the welding process can be achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3632952 A1 [0002, 0002]
• - JP 01181990 A [0003]
• - JP 09182984 A [0003]

Claims (17)

Method for preferably continuous laser beam welding of a workpiece ( 2 ), in particular a pipe, along a welding direction ( 3 ) along the workpiece ( 2 ), whereby in welding direction ( 3 ) in front of a weld ( 5 ) on the workpiece ( 2 ) at least one to a joint gap ( 4 ) in the workpiece ( 2 ) offset mark ( 14a . 14b ) is detected, characterized in that the at least one mark ( 14a . 14b ) also in welding direction ( 3 ) after the weld ( 5 ) is detected and from the position transversely to the welding direction ( 3 ) before and after the weld ( 5 ) detected label ( 14a . 14b ) an optimal welding position (P) of the laser beam ( 7 ) transversely to the welding direction ( 3 ) is determined. Method according to claim 1, characterized in that the laser beam ( 7 ) is positioned at the determined welding position (P). Method according to claim 1 or 2, wherein in addition to the marking ( 14a . 14b ) in welding direction ( 3 ) in front of the weld ( 5 ) the joint gap ( 4 ) and / or in welding direction ( 3 ) after the weld ( 5 ) when welding in the workpiece ( 2 ) produced weld ( 6 ) and preferably their seam geometry is detected. Method according to one of the preceding claims, in which the marking ( 14a . 14b ) before the welding process on the workpiece ( 2 ) is applied, preferably on a plate-shaped workpiece before a subsequent forming process, in particular a subsequent bending operation. Method according to one of the preceding claims, in which the marking ( 14a . 14b ) on the workpiece ( 2 ) is applied as a continuous mark or as an interrupted mark. Method according to one of the preceding claims, in which the marking ( 14a . 14b ) by laser marking or by spraying a dye on the workpiece ( 4 ) is applied. Method according to one of the preceding claims, in which for determining the gap width of the joining gap ( 4 ) two marks ( 14a . 14b ) on opposite sides of the joint gap ( 4 ) are applied. Method according to Claim 7, in which the determined gap width for regulating a tensioning device ( 16 ) for clamping the workpiece ( 2 ) transversely to the welding direction ( 3 ) is used. Contraption ( 1 ) for preferably continuous laser beam welding of a workpiece ( 2 ), in particular a pipe, along a welding direction ( 3 ) along the workpiece ( 2 ), comprising: a laser welding head ( 8th ) for generating a laser beam ( 7 ) for welding the workpiece ( 2 ) at a weld ( 5 ), and a sensor unit ( 11 ) for detecting at least one to a joint gap ( 4 ) in the workpiece ( 2 ) offset mark ( 14a . 14b ) in welding direction ( 3 ) in front of the weld ( 5 ), characterized by a further sensor unit ( 12 ) for detecting the mark ( 14a . 14b ) in welding direction ( 3 ) after the weld ( 5 ), as well as an evaluation unit ( 15 ) for determining an optimum welding position (P) of the laser beam ( 7 ) transversely to the welding direction ( 3 ) from the position transverse to the welding direction ( 3 ) before and after the weld ( 5 ) detected label ( 14a . 14b ). Apparatus according to claim 9, further comprising a moving unit ( 9 ) for moving the laser beam ( 7 ) relative to the workpiece ( 2 ) transversely to the welding direction ( 3 ), and a control unit ( 15 ) for controlling the movement unit ( 8th ) for positioning the laser beam ( 7 ) at the determined welding position (P). Apparatus according to claim 9 or 10, wherein the sensor unit ( 11 ) for detecting the joint gap ( 4 ) and / or the further sensor unit ( 12 ) for detecting when welding on the workpiece ( 2 ) formed weld ( 6 ) and preferably designed by their seam geometry. Device according to one of claims 9 to 11, which in welding direction ( 3 ) in front of the weld ( 5 ) arranged marking device ( 13 ) for applying at least one to the joint gap ( 4 ) in the workpiece ( 2 ) offset mark ( 14a . 14b ) having. Device according to Claim 12, in which the marking device ( 13 ), the marking ( 14a . 14b ) continuously or at predeterminable time intervals on the workpiece ( 2 ). Device according to one of claims 12 or 13, in which the marking device ( 13 ) is designed as a laser marking unit or as a printing device with a nozzle for spraying a dye. Device according to one of Claims 12 to 14, in which the marking device ( 13 ), two markings ( 14a . 14b ) on opposite sides of the joint gap ( 4 ) on the workpiece ( 2 ), and where the evaluation unit ( 15 ) is designed, from the distance of the Markierun gene ( 14a . 14b ) transversely to the welding direction ( 3 ) the gap width of the joining gap ( 4 ) to investigate. Device according to one of claims 9 to 15, in which the sensor unit ( 11 ) and / or the further sensor unit ( 12 ) are formed as a camera system with light section unit or with incident light unit. Device according to one of claims 9 to 16, which has a welding direction ( 3 ) in front of the weld ( 5 ) arranged tensioning device ( 16 ) for clamping the workpiece ( 2 ) transversely to the welding direction ( 3 ) whose clamping force in dependence on a determined gap width of the joining gap ( 4 ) is regulated.