JP2010046679A - Method of and device for inspecting laser welding quality - Google Patents

Abstract

A laser welding quality inspection method and apparatus capable of detecting a through hole at a laser welding site with high accuracy are provided.
After completion of laser welding on a member to be welded, 10 is irradiated with inspection light from an inspection light irradiation means on the laser irradiation surface side of the laser welding portion of the member to be welded, When the inspection light is detected by the light sensing unit 142 arranged on the opposite side of the inspection light irradiation unit 110, the determination unit determines that a through hole exists in the laser welding site.
[Selection] Figure 7

Description

  The present invention relates to a laser welding quality inspection method and apparatus.

In laser welding (remote welding) in which workpieces are welded using a laser beam, the welding quality is inspected by analyzing images obtained by photographing a laser beam irradiated portion and its vicinity with a CCD camera. (For example, refer to Patent Document 1).
JP 2004-148353 A

  However, image analysis is effective in detecting defects such as blowholes, underfill, and unwelded, but in the case of through-holes, the light and dark patterns and brightness are significantly different compared to the surrounding normal parts. However, there is a problem that it is difficult to detect with high accuracy.

  The present invention has been made to solve the above-described problems associated with the prior art, and an object thereof is to provide a laser welding quality inspection method and apparatus capable of detecting a through hole at a laser welding site with high accuracy.

  One aspect of the present invention for achieving the above object is a laser welding quality inspection method, which is a laser irradiation surface side or a laser irradiation surface at a laser welding portion of a member to be welded after completion of laser welding on the member to be welded. When the inspection light is detected by the light sensing means disposed on the opposite side of the inspection light irradiation means via the welded member and the inspection light is detected through the welded member, there is a through hole in the laser welding site. It is determined that

  Another aspect of the present invention for achieving the above object is a laser welding quality inspection apparatus having inspection light irradiation means, light sensing means and determination means. The inspection light irradiating means is used for irradiating the inspection light to the laser irradiation surface side or the opposite side of the laser irradiation surface at the laser welding portion of the member to be welded after completion of laser welding on the member to be welded. The light sensing means is disposed on the opposite side of the inspection light irradiating means via a member to be welded. The determination means determines that a through hole exists in the laser welding portion when the inspection light is detected by the light sensing means.

  According to the laser welding quality inspection method according to the uniform phase of the present invention and the laser welding quality inspection apparatus according to another uniform phase of the present invention, the presence or absence of the through hole is determined by detecting the inspection light that has passed through the through hole. Therefore, regardless of the surface shape of the through-hole, for example, the through-hole can be detected well even if the light-dark pattern and the luminance are substantially the same as compared with the surrounding normal part. That is, it is possible to provide a laser welding quality inspection method and a laser welding quality inspection device that can detect a through hole at a laser welding site with high accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view for explaining a laser welding quality inspection apparatus according to an embodiment of the present invention.

  Welding system 100 according to the present embodiment includes a laser welding apparatus for welding work (member to be welded) 10 using a laser beam from a location distant from work 10, and a laser for detecting a through hole at a laser welding site. The welding quality inspection device is integrated. More specifically, the welding system 100 includes a scanner head (laser irradiation means / inspection light irradiation means) 110, a through hole detection device 140, a robot arm 150, a robot controller 152, an oscillator (light source) 160, an optical fiber cable 164, and a control device 170. Have The workpiece 10 is, for example, various panel materials that form panel components such as a hood and a door panel of an automobile body.

  The scanner head 110 is disposed at the tip of the robot arm 150 and is used for irradiating a laser beam. The laser beam is used for welding and for inspection light for detecting a through hole. Therefore, it is not necessary to provide an independent inspection light irradiation device, and the cost and size of the device can be easily reduced. The shield gas (assist gas) is, for example, an inert gas such as argon gas.

  The through hole detection device 140 constitutes a laser welding quality inspection device integrally with the scanner head 110, and includes an optical sensor (light sensing means) 142, an amplifier 144, and a determination device (determination means) 146. The optical sensor 142 is used to detect a laser beam for inspection light that has passed through a through hole that exists in a laser welding portion of the workpiece 10. In the present embodiment, the laser beam for inspection light is irradiated from the scanner head 110 in the same manner as the laser beam for welding. Therefore, the optical sensor 142 is connected to the opposite side of the scanner head 110 via the workpiece 10 (of the workpiece 10). It is arranged on the opposite side of the laser irradiation surface side at the laser welding site. The amplifier 144 is used to amplify the output signal of the optical sensor 142 and input it to the determination device 146.

  The determination device 146 is configured to determine that a through hole exists in the laser welding portion of the workpiece 10 when the inspection sensor laser beam is detected by the optical sensor 142. The determination device 146 includes, for example, a computer having a central processing unit or a storage device, a monitor that displays the determination result, and / or a printer that prints the determination result, and the storage device includes an output of the optical sensor 142. A program for determining the presence or absence of a through hole based on the signal is installed.

  As described above, the welding system 100 has the laser welding quality inspection device including the scanner head 110 and the through-hole detection device 140. By detecting the laser beam for inspection light that has passed through the through-hole, the welding system 100 penetrates. It is possible to determine the presence or absence of holes. Therefore, regardless of the surface shape of the through-hole, for example, the through-hole can be detected well even if the light and dark pattern and the luminance are substantially the same as compared to the normal part around the through-hole. That is, the through hole in the laser welding site can be detected with high accuracy.

  Note that the optical sensor 142 is not particularly limited as long as it can detect a laser beam for inspection light. For example, a photodiode, a photoconductive cell, a photoresistor, a phototransistor, a photoelectric tube, or an image sensor can be applied. is there. In addition, it is possible to detect the position of the through hole with high accuracy by arranging a plurality of one-dimensional photosensors in a matrix (a grid pattern) or using a two-dimensional image sensor (area image sensor). Is possible.

  The robot arm 150 is a multi-axis (multi-joint) type, and is used to appropriately move the scanner head 110 disposed at the tip. The robot controller 152 is used, for example, to control the movement of the robot arm 150 in accordance with the motion path data given by the teaching work.

  The oscillator 160 uses a YAG laser and incorporates an optical system, a power supply, a control system, a cooling gas circulation system, and the like. The control system includes, for example, an output adjustment unit that adjusts oscillation output by changing power. (Output adjusting means / power density adjusting means) 162 is arranged. The oscillator 160 serves as both a light source for the inspection light laser beam and a light source for the welding laser beam. Therefore, it is not necessary to provide an independent light source for inspection light, and the apparatus can be easily reduced in cost and size. For the oscillator 160, a solid-state laser other than a YAG laser, or a liquid laser such as a carbon dioxide gas laser can be appropriately applied. The optical fiber cable 164 is a light guide member for connecting the oscillator 160 and the scanner head 110 and introducing a laser beam into the scanner head 110.

  Since the laser beam generated by the oscillator 160 is introduced into the scanner head 110 via the optical fiber cable 164, the power density of the laser beam emitted from the scanner head 110 is adjusted by the output adjustment unit 162 of the oscillator 160. It is possible to adjust. That is, by using the output adjustment unit 162 and reducing the oscillation output of the oscillator 160, the power density of the laser beam can be easily reduced.

  Therefore, when the laser beam for inspection light is irradiated after completion of laser welding, when the power density is reduced as compared with the power density of the laser beam for welding, the optical sensor 142 is deteriorated because the power density is small. And the influence of the inspection light laser beam on the workpiece 10 can be reliably eliminated.

  The control device 170 includes, for example, a computer having a central processing unit, a storage device, and the like, and is used to control the scanner head 110, the determination device 146, the robot controller 152, and the oscillator 160 as a whole.

  Next, the scanner head 110 will be described in detail. 2 is a cross-sectional view for explaining the scanner head shown in FIG. 1, and FIG. 3 is a perspective view for explaining an irradiation range of the laser beam shown in FIG.

  The scanner head 110 includes a laser input unit 112, a lens / mirror group 122, and a drive control system 132.

  The laser input unit 112 includes a holding unit 114, a position adjustment mechanism 116, and a control unit 118. The holding unit 114 is used to hold the optical fiber cable 164 extending from the oscillator 160. The position adjustment mechanism 116 is used to change the position of the end 165 of the optical fiber cable 164. The control unit 118 is used to adjust the focal length by controlling the position adjusting mechanism 116 and changing the position of the end 165 of the optical fiber cable 164. The control unit 118 is activated when the distance between the scanner head 110 and the laser welding portion of the workpiece 10 changes greatly due to, for example, the installation position of the robot arm 150 or the workpiece 10 being changed.

  The lens / mirror group 122 includes a collimator lens 123, a fixed mirror 124, a movable lens 125, a first lens 126, a second lens 127, and a movable mirror (mirror member) 128. The laser beam introduced from the end 165 of the optical fiber cable 164 held by the laser input unit 112 passes through the collimating lens 123, is reflected by the fixed mirror 124, and is movable lens 125, first lens 126, and second lens 127. , Reflected by the movable mirror 128, and irradiated from the scanner head 110 toward the laser welding site.

  The drive control system 132 includes a first actuator 134, a second actuator (mirror drive means) 136, and a control unit (movement speed control means / power density adjustment means) 138. The first actuator 134 is used to adjust the focusing distance in the Z direction by changing the position of the movable lens 125. That is, the scanner head 110 has an optical system for adjusting the focus of the laser beam for welding and the laser beam for inspection light irradiated toward the laser welding site.

  The second actuator 136 is used to rotate (rotate and drive) the movable mirror 128 and move the irradiation spot of the laser beam reflected by the movable mirror 128 in the XY direction. The control unit 138 is used to control the second actuator 136, and can adjust the rotation speed of the movable mirror 128 and change the moving speed of the irradiation spot.

  As described above, the scanner head 110 moves the irradiation spot at the laser welding site by rotating the movable mirror 128 for irradiating the laser beam from the oscillator 160 toward the laser welding site and the movable mirror 128. And a control unit 138 for adjusting the moving speed of the irradiation spot.

  Therefore, when the laser beam is used as inspection light, the power density of the inspection light laser beam can be easily reduced by increasing the moving speed of the irradiation spot of the inspection light laser beam at the laser welding site. is there. That is, the control unit 138 can adjust the power density of the inspection light laser beam at the laser welding site.

  The scanner head 110 has an optical system for adjusting the focus of the laser beam irradiated toward the laser welding site. Therefore, the power density of the inspection light laser beam can be easily reduced by separating the focal point of the inspection light laser beam from the laser welding portion. That is, it is possible to adjust the power density of the inspection light at the laser welding site also by using the optical system.

  Furthermore, the optical system can adjust the focus of the laser beam for inspection light so that the irradiation spot covers the entire laser welding site. In this case, the inspection time can be shortened because the entire laser welding site can be inspected at once without moving the inspection light laser beam.

  The scanner head 110 has a first actuator 134 used to adjust the light collection distance in the Z direction and a second actuator 136 used to move the irradiation spot in the XY direction. The irradiation range is a three-dimensional range (see FIG. 3). In addition, since the scanner head 110 is disposed at the tip of the robot arm 150, the operation of the robot arm 150 is added, and the laser beam can be irradiated in various directions.

  Next, a laser welding quality inspection method according to the present embodiment will be described.

  4, 5, and 6 are conceptual diagrams for explaining a C-shaped weld bead, an S-shaped weld bead, and a linear weld bead, and FIG. 7 is a diagram for explaining detection of inspection light. It is a perspective view. The weld bead is a weld mark formed by solidifying a part of the welded member melted by the laser beam at the laser welding site.

  First, the control device 170 controls the robot controller 152, the scanner head 110, and the oscillator 160, and executes a welding operation on the workpiece 10. The robot controller 152 operates each axis of the robot arm 150 according to the stored teaching data, and moves the scanner head 110 along a predetermined path.

  The drive control system 132 of the scanner head 110 controls the lens / mirror group 122 and irradiates a welding laser beam focused on the laser welding portion of the workpiece 10. The movement of the irradiation spot at the laser welding site is a combination of the movement of the scanner head 110 itself driven by the robot arm 150 and the movement of the welding laser beam based on the rotation of the movable mirror 128 of the scanner head 110. .

  The irradiation pattern of the welding laser beam is not particularly limited. For example, the C-shaped welding bead 12 shown in FIG. 4, the S-shaped welding bead 12 shown in FIG. 5, and the linear shape shown in FIG. It can be set to form a weld bead 12.

  When laser welding on the workpiece 10 is completed, the laser beam L for inspection light is irradiated from the scanner head 110 to the laser irradiation surface side of the laser welding portion of the workpiece 10.

  The inspection light laser beam L is moved so as to coincide with the irradiation path of the welding laser beam. For example, when the C-shaped weld bead 12 shown in FIG. 4 is formed, the inspection light laser beam L is moved in a C-shape as shown in FIG. In this case, since an independent control means (for example, a dedicated program) for controlling the movement of the inspection light laser beam L is unnecessary, it is easy to reduce the cost of the apparatus. Further, the position of the through hole 14 can be easily detected.

  Further, the power density of the inspection light laser beam L is reduced by reducing the oscillation output of the oscillator 160 (for example, 80 to 90%). That is, the power density of the laser beam L for inspection light at the laser welding site is reduced compared to the power density of the laser beam for welding, and the power density is small. The influence of the inspection light laser beam L on is reliably eliminated.

  When the inspection light laser beam L is irradiated, the second actuator 136 of the scanner head 110 is controlled to increase the rotational speed of the movable mirror 128, thereby reducing the power density of the inspection light laser beam L. It is also possible. That is, the power density of the inspection light laser beam L can be reduced by increasing the moving speed of the irradiation spot of the inspection light laser beam L at the laser welding site.

  Next, when the inspection light laser beam L emitted from the scanner head 110 is detected by the optical sensor 142 disposed on the opposite side of the scanner head 110 via the workpiece 10, the determination device 146 applies the laser beam to the laser welding site. It is determined that the through hole 14 exists.

  That is, since the presence or absence of the through hole 14 is determined by detecting the inspection light laser beam L that has passed through the through hole 14, for example, in a normal region around the through hole 14. In comparison, the through hole 14 can be detected well even if the light and dark pattern and the luminance are substantially the same. The detected through hole 14 can be repaired by using, for example, solder as necessary.

  8 and 9 are perspective views for explaining in-focus and defocus in Modification 1 according to the embodiment of the present invention, and FIGS. 10 and 11 are Modification 2 according to the embodiment of the present invention. It is a perspective view for demonstrating in-focus and defocus in FIG.

  The method of reducing the power density of the inspection light laser beam L in comparison with the power density of the welding laser beam is limited to a mode in which the oscillation output of the oscillator 160 is reduced or a mode in which the rotational speed of the movable mirror 128 is increased. Not.

  For example, by controlling the first actuator 134 of the scanner head 110 and changing the position of the movable lens 125 (see FIG. 2), the focusing distance in the Z direction is adjusted, and the laser beam L for inspection light is focused on the laser. It can be done by separating it from the weld site. In this case, the irradiation spot S is formed by performing in-focus (see FIG. 8) for focusing the laser beam L for inspection light above the laser welding site or defocusing (see FIG. 9) for focusing below the laser welding site. Due to the enlargement, the power density is easily reduced.

  Further, as shown in FIGS. 10 and 11, the power density can be reduced by adjusting the focus of the laser beam L for inspection light so that the irradiation spot S covers the entire laser welding region. In this case, the inspection time can be shortened because the entire laser welding part can be inspected collectively without moving the inspection light laser beam L.

  As described above, in the laser welding quality inspection method and the laser welding quality inspection apparatus according to the present embodiment, the presence or absence of the through hole is determined by detecting the inspection light that has passed through the through hole. Regardless of the surface shape, for example, the through-hole can be detected satisfactorily even if the light-dark pattern and the luminance are substantially the same as compared with the surrounding normal part. That is, it is possible to provide a laser welding quality inspection method and a laser welding quality inspection device that can detect a through hole at a laser welding site with high accuracy.

  The inspection light is composed of a laser beam emitted from the scanner head. When the inspection light laser beam is emitted, the power density at the laser welding portion is reduced as compared with the power density of the welding laser beam. Therefore, since it is not necessary to provide an independent inspection light irradiation device, it is easy to reduce the cost and size of the device, and since the power density is small, the deterioration of the optical sensor is suppressed and the inspection light laser for the workpiece is used. The influence of the beam can be surely eliminated.

  Since the laser beam oscillator for inspection light also serves as the laser beam oscillator for welding, it is not necessary to provide an independent oscillator for inspection light. Therefore, it is easy to reduce the cost and size of the apparatus.

  When the inspection light laser beam is moved so as to coincide with the irradiation path of the welding laser beam, an independent control means (for example, a dedicated program) for controlling the movement of the inspection light laser beam is unnecessary. Therefore, it is easy to reduce the cost of the apparatus.

  The power density of the laser beam for inspection light decreases the oscillation output of the oscillator, increases the moving speed of the irradiation spot at the laser welding site, or moves the focus of the laser beam for inspection light away from the laser welding site (inspection light It can be easily reduced by shifting the focus (in-focus or defocus).

  When the focus of the laser beam for inspection light is adjusted so that the irradiation spot covers the entire laser welding part, the entire laser welding part can be inspected at once without moving the laser beam for inspection light. , Inspection time can be shortened.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.

  For example, the laser welding quality inspection apparatus is not limited to a form in which the welding system is integrated with the laser welding apparatus, and may be an independent apparatus, for example. In this case, since the welding of the workpiece and the detection of the through hole can be performed in parallel, the productivity of the welding can be improved. It is also easy to irradiate the inspection light laser beam from the opposite side of the laser irradiation surface.

  The power density of the inspection light laser beam can be reduced by appropriately combining a decrease in the oscillation output of the oscillator, an increase in the rotational speed of the movable mirror, and a defocusing of the inspection light. Further, the moving path of the inspection light laser beam can be made different from the irradiation path of the welding laser beam, or the inspection light laser beam can be irradiated on the opposite side of the laser irradiation surface. Furthermore, a fixed mirror or a movable mirror can be substituted with a prism.

It is a perspective view for demonstrating the laser welding quality inspection apparatus which concerns on embodiment of this invention. It is sectional drawing for demonstrating the scanner head shown by FIG. It is a perspective view for demonstrating the irradiation range of the laser beam shown by FIG. It is a conceptual diagram for demonstrating a C-shaped welding bead. It is a conceptual diagram for demonstrating a S-shaped welding bead. It is a conceptual diagram for demonstrating a linear-shaped welding bead. It is a perspective view for demonstrating the detection of inspection light. It is a perspective view for demonstrating the in-focus in the modification 1 which concerns on embodiment of this invention. It is a perspective view for demonstrating the defocus in the modification 1 which concerns on embodiment of this invention. It is a perspective view for demonstrating the in-focus in the modification 2 which concerns on embodiment of this invention. It is a perspective view for demonstrating the defocus in the modification 2 which concerns on embodiment of this invention.

Explanation of symbols

10 Workpiece (member to be welded),
12 Weld beads,
14 through hole 100 welding system (laser welding equipment and laser welding quality inspection equipment),
110 Scanner head (laser irradiation means and inspection light irradiation means),
112 laser input section,
114 holding part,
116 position adjustment mechanism,
118 control unit,
122 lens / mirror group (power density adjusting means),
123 collimating lens,
124 fixed mirror,
125 movable lens,
126 first lens,
127 second lens,
128 movable mirror (mirror member),
132 Drive control system (power density adjusting means),
134 first actuator,
136 second actuator (mirror driving means),
138 control unit (movement speed control means and power density adjustment means),
140 through-hole detection device,
142 light sensor (light sensing means),
144 amplifier,
146 determination device (determination means),
150 robot arm,
152 robot controller,
160 oscillator (light source),
162 output adjustment unit (output adjustment means and power density adjustment means),
164 optical fiber cable,
165 end,
170 Controller L Laser beam for inspection light,
S Irradiation spot.

Claims (14)

After completion of laser welding on the member to be welded, irradiate inspection light on the laser irradiation surface side or the laser irradiation surface opposite side of the laser welding portion of the member to be welded,
When the inspection light is detected by light sensing means arranged on the opposite side of the inspection light irradiation means via the welded member, it is determined that a through hole exists in the laser welding portion. Laser welding quality inspection method. The inspection light consists of a laser beam irradiated from a laser irradiation means for irradiating a welding laser beam,
2. The laser welding quality inspection method according to claim 1, wherein a power density of the laser beam for inspection light at the laser welding portion is reduced as compared with a power density of the laser beam for welding.   3. The laser welding quality inspection method according to claim 2, wherein the inspection light laser beam is moved so as to coincide with an irradiation path of the welding laser beam.   4. The laser welding quality inspection according to claim 2, wherein the reduction of the power density of the laser beam for inspection light is performed by lowering an oscillation output of a light source of the laser irradiation unit. 5. Method.   3. The power density of the inspection light laser beam is reduced by increasing a moving speed of an irradiation spot of the inspection light laser beam at the laser welding site. 3. The laser welding quality inspection method according to 3.   The power density of the inspection light laser beam is reduced by moving a focus of the inspection light laser beam away from the laser welding site. Laser welding quality inspection method.   The laser welding quality inspection method according to claim 2, wherein a focus of the laser beam for inspection light is adjusted so that an irradiation spot of the laser beam for inspection light covers the entire laser welding portion. Inspection light irradiation means for irradiating inspection light to the laser irradiation surface side or the laser irradiation surface opposite side of the laser welding portion of the welded member after completion of laser welding to the member to be welded,
A light sensing means disposed on the opposite side of the inspection light irradiation means via the welded member; and
A laser welding quality inspection apparatus comprising: a determination unit that determines that a through hole exists in the laser welding part when the inspection light is detected by the light sensing unit.   9. The laser welding quality inspection apparatus according to claim 8, wherein the light source of the inspection light also serves as a light source of laser irradiation means for irradiating a welding laser beam. A power density adjusting means for adjusting the power density of the inspection light at the laser welding site;
The inspection light irradiation means also serves as the laser irradiation means,
The inspection light consists of a laser beam,
10. The laser welding according to claim 9, wherein the power density adjusting unit reduces the power density of the laser beam for inspection light at the laser welding portion as compared with the power density of the laser beam for welding. Quality inspection device. An output adjusting means for adjusting the oscillation output of the light source;
11. The laser welding according to claim 10, wherein the power density adjusting unit includes the output adjusting unit, and reduces a power density of the inspection light laser beam by reducing an oscillation output of the light source. Quality inspection device. The inspection light irradiation means includes
A mirror member for irradiating the laser beam for inspection light from the light source toward the laser welding site;
Mirror driving means for moving the irradiation spot of the laser beam for inspection light at the laser welding site by rotating the mirror member, and
It has a moving speed control means for controlling the mirror driving means and adjusting the moving speed of the irradiation spot,
The power density adjusting means includes the moving speed control means, and reduces the power density of the laser beam for inspection light by increasing the moving speed of the irradiation spot at the laser welding site. Item 11. The laser welding quality inspection device according to Item 10. The inspection light irradiation means has an optical system for adjusting the focus of the laser beam for inspection light irradiated toward the laser welding site,
The laser according to claim 10, wherein the power density adjusting unit includes the optical system, and reduces the power density of the inspection light laser beam by separating the focal point from the laser welding portion. Welding quality inspection device.   The inspection light irradiation means includes an optical system for adjusting a focus of the inspection light laser beam so that an irradiation spot of the inspection light laser beam covers the entire laser welding portion. The laser welding quality inspection apparatus according to claim 10.

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