JP5761490B2 - Laser welding method and laser welding apparatus - Google Patents

Description

  The present invention relates to a laser welding method and a laser welding apparatus suitable for joining a long distance by laser welding (including laser arc hybrid welding) using laser light having an ultra-fine optical axis.

  In laser welding using the laser beam described above, since the optical axis of the laser beam is extremely fine, it is necessary to manage the target position of the laser beam in units of 0.1 mm when joining a long distance in a large structure. There is.

  Conventionally, as a laser welding apparatus suitable for use in such welding, for example, there is one described in Patent Document 1. This laser welding apparatus is configured by arranging a laser head and a sensor at the tip of a robot arm, and both the laser head and the sensor move along a welding line in accordance with a programmed operation of the robot arm.

  Both the laser head and the sensor are movable in the direction (left and right direction and up and down direction) perpendicular to the welding line with respect to the tip of the robot arm, and the laser light from the laser head comes off from the welding line or approaches and moves away from the welding line. When the sensor detects that the laser beam is detected, the laser beam is returned to the position as programmed with respect to the weld line based on a command from the control system.

US Pat. No. 6,430,472

  When joining a long distance in a large-sized structure, it is common to temporarily attach a plurality of grooves in order to prevent distortion generated in the grooves between the workpieces during welding or mutual displacement. The length of this tacking part (temporary welding bead) is usually around 20 mm, but in the above laser welding apparatus, if this tacking part exists on the groove, the possibility of losing the groove is denied. There is a problem that it is not possible to solve this problem, and it has been a conventional problem to solve this problem.

  The present invention has been made by paying attention to the above-described conventional problems. Even if there is a tacking portion on the groove, the laser beam with an ultra-fine optical axis always follows the groove without losing sight of the groove. As a result, it is an object of the present invention to provide a laser welding method and a laser welding apparatus capable of accurately and reliably joining a long distance.

  According to the first aspect of the present invention, when welding is performed by moving the welding laser beam along the groove, the welding laser beam moves together with the welding laser beam to the front side in the traveling direction of the welding laser beam. By irradiating a laser beam for detecting the groove of the stripe, two laser spots straddling the groove are formed at intervals, and the front laser spot is preceded by the two laser spots. Based on groove information obtained by imaging each operation of the preceding laser spot and the scanning laser spot, using the rear laser spot as a scanning laser spot, and processing the image of the scanning laser spot. When the laser beam for welding is moved along a groove, and the preceding laser spot passes through a groove non-detection part such as a tacking part or a burr existing on the groove. , Each of the image of the position approaching the groove non-detection unit and the image of the position separated from the groove non-detection unit, respectively, to obtain information on the hidden groove in the groove non-detection unit, When the scanning laser spot follows the preceding laser spot and passes through the groove non-detecting portion, the hidden groove information obtained by the preceding laser spot passing through the groove non-detecting portion. The laser beam for welding is configured to move based on the above, and the laser welding method of this configuration is used as a means for solving the above-described conventional problems.

  In the laser welding method according to claim 2 of the present invention, the maximum length in the welding progress direction of the groove non-detection portion is set, and when the preceding laser spot passes through the groove non-detection portion, When it is recognized that the length of the groove non-detecting portion in the welding progress direction exceeds the maximum value, the welding is stopped.

Here, the tacking portion assumed as the groove non-detecting portion may be formed continuously over the entire length of the groove or may be formed in a dotted manner. Is a case where a temporary attachment portion is scattered as a groove non-detection portion on the groove, or a case where there is no temporary attachment portion on the groove and only a burr (including chips) exists as a groove non-detection portion. Applies to
The length of the tacking portions scattered on the groove is determined based on the thickness of the work forming the groove and the groove shape itself, and is usually around 20 mm, and the groove non-detection section due to the burr is long. Does not exceed 15 mm.

  In the laser welding method according to the present invention, the maximum length in the welding progress direction of the groove non-detection portion is not particularly limited and can be freely set. In consideration of the length of the groove non-detection section, for example, the maximum value of the length of the groove non-detection portion in the welding progress direction can be set to about 30 mm.

  On the other hand, the invention according to claim 3 of the present invention is a laser welding apparatus for performing welding by moving a welding laser beam along a groove between workpieces, and the welding laser beam is directed toward the groove. A welding laser head that can be irradiated and moved along the groove, and moves together with the welding laser head, and irradiates the front of the welding laser head with a double groove detection laser beam in the traveling direction. A groove detecting laser head for forming two laser spots straddling the groove at a distance from each other, a preceding laser spot positioned in front of the two laser spots, and a rear Two image processing cameras for capturing each operation of the scanning laser spot positioned, and images from the preceding camera for capturing the operation of the preceding laser spot of the two image processing cameras and the front An image processing unit that processes an image from a copying camera that captures the operation of the copying laser spot, and the welding laser head based on groove position information obtained by processing the image from the copying camera by the image processing unit The control unit is configured to move along the groove, the control unit, when the preceding laser spot passes through a groove non-detection unit such as a tacking unit or a burr existing on the groove, Hidden groove in the groove non-detection part obtained by processing the image from the preceding camera at the position where the preceding laser spot has approached the groove non-detection part and the position where the preceding laser spot has left the groove non-detection part, respectively. In the case where the scanning laser spot follows the preceding laser spot and passes through the groove non-detecting section, the preceding laser spot detects the groove non-detection. In order to solve the above-described conventional problems, the laser welding apparatus is configured to move the welding laser head based on the hidden groove information obtained by passing through As a means of.

  The laser welding method and the laser welding apparatus according to the present invention are not limited to laser welding using only laser light with an ultrafine optical axis, and can also be applied to laser arc hybrid welding.

In the laser welding method and laser welding apparatus according to the present invention, laser light such as CO ₂ laser light or YAG laser light can be used as the welding laser light, while the preceding laser spot and the copying laser spot are used. A semiconductor laser beam can be used as the groove detection laser beam to be formed.

Furthermore, in the laser welding method and laser welding apparatus according to the present invention, the sizes of the preceding laser spot and the scanning laser spot are appropriately set based on the shape of the groove, and are not particularly limited.
For example, when the groove is an I groove (narrow groove), each of the preceding laser spot and the scanning laser spot is used in order to improve detection accuracy of the narrow groove during image processing and avoid interference between spots. The size can be about 5 mm in length and about 0.5 mm in width.
Further, for example, when the groove is a V groove, a Y groove, or a U groove, the laser spot needs to completely cross these grooves. Naturally, the length is set larger than in the case of the I groove.

  At this time, it is a matter of course that the distance between the spots of the preceding laser spot and the scanning laser spot positioned back and forth in the welding traveling direction is set to exceed the maximum length of the groove non-detection portion described above. For example, when the maximum value of the length of the groove non-detecting portion is set to about 30 mm as described above, it is desirable to set the distance between the spots of both laser spots to about 50 mm with a margin.

  Furthermore, in the laser welding method and laser welding apparatus according to the present invention, the distance between the scanning laser spot and the welding position is, for example, arc light or welding fume generated by laser arc hybrid welding at the time of laser spot operation imaging. It is desirable to set the distance so as not to obstruct the field of view near the laser spot following the noise.

  In the laser welding method and laser welding apparatus according to the present invention, in a situation where a portion without a groove non-detecting portion is being welded, a welding laser beam is obtained based on groove information obtained by processing an image of a scanning laser spot. Is moved along the groove, and on the other hand, a portion where a groove non-detection portion such as a temporary attachment portion or a burr exists on the groove is welded, the laser spot follows the groove non-detection portion. At the time of passing, the preceding laser spot moves based on the information on the hidden groove already obtained by passing through the groove non-detection part, so that the laser beam with an extremely thin optical axis is always transmitted without losing sight of the groove. Therefore, even if it is a long distance, it can be joined accurately and reliably.

  Since the laser welding method according to the present invention has the above-described configuration, even if there is a portion where a groove cannot be detected such as a temporary attachment part or a burr on the groove, the groove is lost. As a result, the laser beam can be always driven along the groove, and as a result, it is possible to join the long distance with high accuracy and reliability.

1 is a perspective explanatory view schematically showing a laser welding apparatus according to an embodiment of the present invention. It is a groove detection point explanatory drawing in the groove non-detection part of the laser welding apparatus shown in FIG. It is the first half of the flowchart which shows operation | movement of the laser welding apparatus in FIG. It is the latter half of the flowchart which shows operation | movement of the laser welding apparatus in FIG. It is operation | movement explanatory drawing (a)-(c) which shows the groove | channel detection operation | movement of the laser welding apparatus in FIG. 1 corresponding to each step of the flowchart in FIG. It is operation | movement explanatory drawing (a)-(c) which shows the groove | channel detection operation | movement of the laser welding apparatus in FIG. 1 corresponding to each step of the flowchart in FIG. It is operation | movement explanatory drawing (a)-(c) which shows the groove | channel detection operation | movement of the laser welding apparatus in FIG. 1 corresponding to each step of the flowchart in FIG. It is perspective explanatory drawing which shows schematically the laser welding apparatus which concerns on the other Example of this invention.

Hereinafter, the present invention will be described with reference to the drawings.
1 to 7 show an embodiment of a laser welding apparatus according to the present invention.

  As shown in FIG. 1, the laser welding apparatus 1 includes a welding laser oscillator 2, a welding laser head 3 that irradiates laser light emitted from the welding laser oscillator 2, and a control unit 4. .

  In this case, the laser welding apparatus 1 is provided so as to extend horizontally from the base beam 5 along the foundation E on which the workpieces W, W are placed side by side, and to extend from the base beam 5 onto the foundation E. An overhanging beam 6 that slides along the base beam 5, a vertical beam 7 that slides along the overhanging beam 6 and slides up and down with respect to the overhanging beam 6, and a fixed member disposed at the lower end of the vertical beam 7 A drive mechanism including the beam 8 is provided.

  The welding laser head 3 is mounted on the fixed beam 8 of the laser head driving mechanism, and the laser head driving mechanism operates in response to a command from the control unit 4 to weld the workpieces W and W on the foundation E. The height of the laser beam head 3 is adjusted to an appropriate position, and the laser beam Lw emitted from the welding laser head 3 is moved along the groove Wa between the workpieces W and W.

  The laser welding apparatus 1 also includes a groove detection laser head 9 mounted on a fixed beam 8 of a laser head driving mechanism together with a welding laser head 3. The groove detection laser head 9 irradiates the laser beam emitted from the groove detection laser oscillator 10 toward the base E side into two laser beams Lf and Lr, and works on the workpieces W and W. Two rectangular laser spots LSf and LSr are formed in a rectangular shape, and these rectangular laser spots LSf and LSr are both formed across the groove Wa between the workpieces W and W. It is like that. The two rectangular laser spots LSf and LSr are formed before and after the welding traveling direction at intervals which will be described later. The laser spot LSf on the front side in the traveling direction is set as the preceding laser spot LSf, and the laser on the rear side in the traveling direction. The spot LSr is copied as a laser spot LSr.

  Further, the laser welding apparatus 1 includes two image processing cameras 11 and 12 mounted on a fixed beam 8 of a laser head driving mechanism together with a welding laser head 3 and a groove detection laser head 10, and these An image processing unit 13 that processes images taken by the cameras 11 and 12 and transmits the processed images to the control unit 4 is provided. One of the two image processing cameras 11 and 12 is the preceding camera 11 that captures the preceding laser spot LSf or the vicinity thereof, and is one of the two image processing cameras 11 and 12. The other camera 12 is a copying camera 12 that photographs the scanning laser spot LSr or its vicinity.

  That is, the laser welding apparatus 1 captures a scanning laser spot LSr straddling the groove Wa between the workpieces W and W with the scanning camera 12 during welding, and the image processing unit 13 captures an image from the scanning camera 12. The welding laser head 3 is moved in accordance with the groove Wa between the workpieces W and W according to a command from the controller 4 based on the groove position information obtained from the image processor 13. It is supposed to let you.

  Further, in this laser welding apparatus 1, the preceding laser spot LSf got over the portion where the groove Wa was not visible due to being temporarily attached or burr inserted during welding, that is, the groove non-detection portion N. In this case, as shown in FIG. 2, the image of the preceding camera 11 that has taken the image is processed by the image processing unit 13 to obtain the start position Ns and the end position Ne of the groove non-detection unit N. While the preceding laser spot LSf passes through the groove non-detecting portion N, the welding laser head 3 is moved while irradiating the laser beam Lw based on the groove position information obtained by the copying camera 12. A main welding bead B is formed.

  Then, up to the start position Ns of the groove non-detecting portion N, the welding laser head 3 is moved along the groove Wa by a command from the control unit 4 based on groove position information obtained by the copying camera 12. On the other hand, from the start position Ns to the end position Ne of the groove non-detection part N, the welding laser is in accordance with a command from the control part 4 based on the groove position information of the groove non-detection part N obtained by the preceding camera 11. The head 3 is moved.

  Here, the maximum length of the groove non-detection portion N is not particularly limited, but the length of the temporary attachment portion as the groove non-detection portion N is usually around 20 mm, and the groove non-detection section due to the burr is long. In this embodiment, the maximum value of the length of the groove non-detecting portion N is set to about 30 mm in consideration of not exceeding 15 mm. When the preceding laser spot LSf gets over the groove non-detecting portion N, that is, when the section where the groove Wa is not visible does not exceed the maximum value 30 mm of the setting range, as described above, from the preceding camera 11 On the other hand, the groove position in the groove non-detecting portion N is calculated based on the image of the above, and the section where the groove Wa is not visible without the preceding laser spot LSf getting over the groove non-detecting portion N is the set range. When the maximum value exceeds 30 mm, the laser head drive mechanism or the control unit 4 may cause an error, and the welding is stopped.

  Needless to say, the inter-spot distance a between the preceding laser spot LSf and the scanning laser spot LSr positioned back and forth in the welding traveling direction is set to exceed the maximum value of the length of the groove non-detection portion N. When the maximum length of the groove non-detecting portion N is set to about 30 mm as described above, the inter-spot distance a between the preceding laser spot LSf and the copying laser spot LSr should be set to about 50 mm with a margin. Is desirable.

  The distance b between the scanning laser spot LSr and the welding position P (the tip position of the main welding bead B) irradiated with the laser beam Lw from the welding laser head 3 is the field of view of the scanning camera 12 that captures the scanning laser spot LSr. The distance is set so as not to be obstructed by welding fume generated during welding.

Therefore, the welding operation by the above laser welding apparatus 1 will be described.
First, as shown in FIG. 3, following the turning on of the groove copying program in step S1, the welding program is turned on in step S2.

  In this way, when the welding program is turned on, the laser output of the welding laser oscillator 2, the welding mode, the flow rate of the shielding gas, the welding speed and other welding conditions are controlled to preset values, and welding can be started. It becomes a state.

  Next, in step S3, as shown in FIG. 5A, the preceding laser spot LSf formed on the workpieces W and W by being irradiated with the laser beam Lf from the groove detecting laser head 9 starts welding. Shooting of a groove image by the preceding camera 11 is started from the time when the position SP is passed, and the groove Wa is detected by the preceding camera 11. At this time, the welding start position SP is set to a part where the groove Wa is not temporarily attached or a burr is not fitted, that is, a part where the groove Wa can be detected.

  Further, in step S4, as shown in FIG. 5B, the scanning laser spot LSr formed on the workpieces W and W when the laser beam Lr is irradiated from the groove detection laser head 9 starts welding. Shooting of a groove image by the copying camera 12 is started from the time when the position SP is passed, and the groove Wa is detected by the copying camera 12.

  Next, in step S5, after transmitting the groove position information of the welding start position SP detected from the image captured by the copying camera 12 to the image processing unit 13 and the control unit 4, in step S6, the control unit 4 The welding laser head 3 is moved to the welding start position SP by the command, and in step S7, welding is started by the command of the control unit 4 as shown in FIG.

  Thus, when welding is started, as shown in FIG. 4, the groove Wa is continuously detected by both the preceding camera 11 and the copying camera 12 in step S8. In step S9, the copying camera 12 is detected. The groove position information is transmitted from the side to the image processing unit 13 and the control unit 4, and in step S 10, the welding laser head 3 moves while irradiating the laser beam Lw according to the groove position information according to a command from the control unit 4. To do.

  In step S11, as shown in FIG. 6A, when the preceding laser spot LSf reaches the start position Ns of the groove non-detecting portion N and the groove Wa cannot be detected by the preceding camera 11, In step S12, measurement of the length of the groove non-detection portion N by the preceding camera 11 following the preceding laser spot LSf is started.

  Subsequently, in step S13, as shown in FIG. 6B, the preceding laser spot LSf reaches the end position Ne of the groove non-detecting portion N, and detection of the groove Wa by the preceding camera 11 is restored. Thus, if the measurement of the length of the groove non-detection portion N is completed and the length of the groove non-detection portion N is within a preset range (OK), the acquisition is performed by the preceding camera 11 in step S14. Based on the groove position information of the start position Ns and the end position Ne of the groove non-detection unit N, the groove position of the entire groove non-detection unit N is calculated by the control unit 4, and this calculation is performed in step S15. The groove position information of the entire groove non-detecting portion N is stored.

  While the preceding laser spot LSf passes through the groove non-detecting portion N (while the preceding camera 11 loses sight of the groove Wa), the welding laser head 3 is a groove obtained by the copying camera 12. It moves while irradiating the laser beam Lw based on the position information.

  Thereafter, in step S16, as shown in FIG. 7A, the arrow section D1 to the start position Ns of the groove non-detection unit N is also obtained from the control unit 4 based on the groove position information obtained by the copying camera 12. The welding laser head 3 moves while irradiating the laser beam Lw following the groove Wa to form the main welding bead B. Subsequently, in step S17, as shown in FIG. In addition, the arrow section D2 from the start position Ns to the end position Ne of the groove non-detection unit N is in accordance with a command from the control unit 4 based on the groove position information of the groove non-detection unit N obtained by the preceding camera 11. The welding laser head 3 moves while forming a main welding bead B on the groove non-detecting portion N.

  Then, in step S18, it is determined whether or not a preset welding length has been reached. As shown in FIG. 7C, the welding length at which the tip of the main welding bead B is set is the welding length. When the end point EP has been reached (Yes), the process proceeds to step S19, where the welding program is turned off, and subsequently, in step S20, the groove copying program is turned off. At this time, similarly to the welding start position SP, the welding end point EP is also set to a part where the groove Wa is not temporarily attached or a burr is not fitted, that is, a part where the groove Wa can be detected. .

  In step S18, when the tip of the main welding bead B has not reached the welding end point EP (No), the steps from step S8 to step S18 are continued until the tip of the main welding bead B reaches the welding end point EP. The process is repeated.

  On the other hand, when the length of the groove non-detection portion N exceeds the preset maximum value (NG) in step S13, it is determined in step S21 that a groove detection error has occurred, and FIG. As shown in c), the groove non-detection part N is processed as the groove non-detectable part Ng, and the process proceeds to step S19 and step S20 in turn, and the welding program and the groove copying program are successively turned off.

  Therefore, in the laser welding apparatus 1 according to the above-described embodiment, the welding laser is based on the groove information obtained by processing the image of the scanning laser spot LSr during the welding of the portion without the groove non-detection portion N. The light Lw is moved along the groove Wa, while the groove non-detection portion N is copied during welding of a portion where the groove non-detection portion N such as a temporary attachment or a burr exists on the groove Wa. When the laser spot LSr passes, the preceding laser spot LSf moves based on the hidden groove information already obtained by passing through the groove non-detection part N, so the groove Wa is lost. Without this, the welding laser beam Lw can be always along the groove Wa.

  Further, in the laser welding apparatus 1 according to the above-described embodiment, when the preceding laser spot LSf cannot get over the groove non-detecting portion N and the section where the groove Wa is not visible exceeds the maximum value of the setting range. Since there is a possibility that an error has occurred in the laser head drive mechanism or the control unit 4, since welding is stopped, it is possible to avoid the occurrence of welding defects.

In the laser welding apparatus 1 described above, prior to actual welding, the process is performed without executing step S7 in the welding program, that is, without irradiating the laser beam Lw from the welding laser head 3. It can be operated.
In such an operation method of the laser welding apparatus 1, the groove non-detecting portion N having a length exceeding the preset maximum value without performing welding by going through steps S 13, S 21, and S 19. Can be determined as the groove non-detectable portion Ng, which is useful for detecting a defect before welding.

  In the above-described embodiment, the laser welding using only the laser beam having an extremely thin optical axis has been described as an example. However, the present invention is not limited to this, and for example, the laser arc hybrid welding shown in FIG. Is possible.

  As shown in FIG. 8, this laser arc hybrid welding apparatus 21 includes an arc welder power source 22 and a welding torch 23 that is mounted on the fixed beam 8 at an appropriate angle and is supplied with power from the arc welder power source 22 to operate. The other configurations are the same as those of the laser welding apparatus 1 according to the previous embodiment.

  Also in this laser arc hybrid welding apparatus 21, during welding of a portion where the groove non-detecting portion N exists on the groove Wa, when the laser spot LSr passes through the groove non-detecting portion N, the preceding laser Since the spot LSf moves based on the hidden groove information already obtained by passing through the groove non-detecting portion N, the welding torch 23 and the welding laser beam Lw can be used without losing sight of the groove Wa. In either case, it can always be along the groove Wa.

  In addition, the structure of the laser welding method and laser welding apparatus which concern on this invention is not limited to the structure of an above-described Example.

DESCRIPTION OF SYMBOLS 1 Laser welding apparatus 2 Laser oscillator for welding 3 Laser head for welding 4 Control part 9 Laser head for groove detection 10 Laser oscillator for groove detection 11 Leading camera 12 Copying camera 13 Image processing part 21 Laser arc hybrid welding apparatus Lf, Lr Laser beam LSf for groove detection Previous laser spot LSr Scanning laser spot Lw Laser beam N for welding N Non-detection part Ne End position (position where the preceding laser spot leaves the non-detection part)
Ns start position (position where the preceding laser spot reaches the groove non-detection part)
W Work Wa Groove

Claims (3)

When performing welding by moving the laser beam for welding along the groove,
Two welding spot laser beams moving together with the welding laser beam are irradiated on the front side in the traveling direction of the welding laser beam, and two laser spots straddling the groove are spaced apart from each other. Forming back and forth,
Of the two laser spots, the front laser spot is used as the preceding laser spot, the rear laser spot is used as the copying laser spot, and the operations of the preceding laser spot and the copying laser spot are respectively photographed.
Moving the laser beam for welding along the groove based on groove information obtained by processing the image of the scanning laser spot;
When the preceding laser spot passes through a groove non-detecting portion existing on the groove, an image of the position where the preceding laser spot has approached the groove non-detecting portion and the groove non-detecting portion are separated. Each of the image of the position was processed to obtain information on the hidden groove in the groove non-detection unit,
When the scanning laser spot follows the preceding laser spot and passes through the groove non-detecting portion, the hidden laser beam obtained by the preceding laser spot passing through the groove non-detecting portion. A laser welding method, wherein the welding laser beam is moved based on information.   The maximum length in the welding progress direction of the groove non-detection part is set, and when the preceding laser spot passes through the groove non-detection part, the length of the groove non-detection part in the welding progress direction is The laser welding method according to claim 1, wherein when it is recognized that the maximum value is exceeded, welding is stopped. A laser welding apparatus for performing welding by moving a laser beam for welding along a groove between workpieces,
A welding laser head that irradiates a laser beam for welding toward the groove and is movable along the groove;
It moves with the welding laser head, irradiates the front of the welding laser head in the traveling direction with two stripe detection laser beams, and the two laser spots straddling the groove are spaced apart from each other. A groove detecting laser head formed back and forth,
Two image processing cameras for capturing the respective operations of the preceding laser spot and the scanning laser spot located at the rear of the two laser spots;
An image processing unit that processes an image from a preceding camera that captures the operation of the preceding laser spot of the two image processing cameras and an image from a scanning camera that captures the operation of the scanning laser spot;
A control unit that moves the welding laser head along the groove based on groove position information obtained by processing an image from the copying camera by the image processing unit;
In the case where the preceding laser spot passes through a groove non-detecting unit existing on the groove, the control unit detects the position where the preceding laser spot has reached the groove non-detecting unit and the groove non-detecting unit. Information on the hidden groove in the groove non-detecting portion obtained by processing the images from the preceding camera at the position where the laser beam is separated from the position is stored, and the scanning laser spot follows the preceding laser spot and the opening is detected. When passing through the tip non-detecting portion, the laser head for welding is moved based on the information on the hidden groove obtained when the preceding laser spot passes through the groove non-detecting portion. Laser welding equipment.

Images