JP2018171630A - Device for determining quality of spot-weld electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a determination device for the quality of a spot-weld electrode suitable for more accurate quality determination in the abrasive condition of an electrode tip.SOLUTION: There is provided a determination device A1 for quality of the abrasive condition of a spot-weld electrode tip. The device comprises: a light source unit 1 irradiating the tip surface of an electrode 6 with a linear light to pass through the intersection point Px of the tip surface and a central axis Ox of the electrode 6; a camera unit 2 imaging the tip surface irradiated with the linear light; and a determination unit 3 determining the quality of abrasive condition of the electrode 6 on the basis of the tip surface image imaged by the camera unit 2. The imaging direction Ny of the tip surface by the camera unit 2 is substantially inclined to the irradiation direction N1 of the linear light by the light source unit 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for determining the quality of a polished state of an electrode tip for spot welding.

  Electrodes used for spot welding are subjected to high pressure during welding and high current flows, so the tip wears out during use, forming a flat part, and the metal component of the welding object adheres. Or If the welding operation is continued in this state, the current density is lowered and a predetermined Joule heat cannot be obtained, resulting in poor welding. In order to prevent such poor welding due to electrode deterioration, the tip of the electrode is cut and polished at regular intervals in order to return the tip of the electrode to a predetermined curved surface shape.

  The electrode tip is polished using a polishing apparatus disposed near the welding robot. The polishing apparatus has a cutter holder in which, for example, a cutter is mounted in a recessed portion into which an electrode tip can be inserted. At the time of electrode polishing, the cutter holder is rotated in a certain direction by a driving force of a motor while the cutter holder is pressed and sandwiched by a pair of electrodes provided at the tip of the welding gun.

  An apparatus for automatically determining the polishing state of the electrode tip shape after polishing work is disclosed (see, for example, Patent Document 1). In this document, light is applied to the center of the electrode tip after polishing, and the quality of the electrode tip shape is determined based on the amount of reflected light. According to the determination method disclosed in Patent Document 1, the quality determination is performed based on the light reflection characteristics at the center of the electrode tip, so that the polishing state can be accurately determined in a relatively narrow range at the center of the electrode tip. . In the polishing of the electrode tip, it is important that the rounded tip shape is more accurately restored. However, in the determination method described in Patent Document 1, the peripheral part surrounding the central part at the electrode tip is used. May not be able to accurately determine the polishing state. Therefore, there is room for improvement in accurately determining the polished state of the electrode tip.

JP 2002-273575 A

  The present invention has been conceived under the circumstances described above, and provides a spot welding electrode pass / fail judgment device suitable for more accurately judging the quality of a polished state of an electrode tip. Let it be the main issue.

  In order to solve the above problems, the present invention employs the following technical means.

  A spot welding electrode quality determination apparatus provided by the present invention includes a light source unit that irradiates determination light onto the tip surface of an electrode, and a camera that images the tip surface irradiated with the determination light. And a determination unit that determines the quality of the polished state of the electrode based on the image of the tip surface captured by the camera unit, and the imaging direction of the tip surface by the camera unit is the light source It is characterized in that it is substantially inclined with respect to the irradiation direction of the determination light by the unit.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a schematic block diagram which shows an example of the quality determination apparatus of the electrode for spot welding which concerns on this invention. The example of the front-end | tip part surface of the electrode which linear light was irradiated by the quality determination apparatus shown in FIG. 1 is shown, (a) is the state seen from the front end side of the electrode in the direction along the central axis of the said electrode. (B) shows the image of the electrode imaged by the camera part. The other example of the surface of the front-end | tip part of the electrode irradiated with linear light by the quality determination apparatus shown in FIG. 1 is shown, (a) was seen in the direction along the central axis of the said electrode from the front-end | tip side of the electrode. A state is represented, (b) represents the image of the electrode imaged by the camera part. It is a figure which shows the other example of the quality determination apparatus of the electrode for spot welding which concerns on this invention, and shows arrangement | positioning of the light source part in planar view. FIG. 5 is a view taken along line VV in FIG. 4. FIG. 6 is a view taken along line VI-VI in FIG. 4. 5 represents the surface of the tip portion of the electrode irradiated with linear light by the quality determination device shown in FIG. It is a schematic block diagram which shows the further another example of the quality determination apparatus of the electrode for spot welding which concerns on this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a quality determination device for spot welding electrodes according to the present invention. As shown in FIG. 1, the pass / fail determination device A <b> 1 of the present embodiment includes a light source unit 1, a camera unit 2, and a determination unit 3.

  The light source part 1 is for irradiating the light for determination with respect to the surface of the front-end | tip part of the electrode for spot welding (electrode 6 shown in FIG. 1). The electrode 6 has a substantially cylindrical main part and a tapered end at a tip. Although detailed illustration explanation is omitted as the light source unit 1, for example, a light source that emits linear light that is an example of light for determination is used. The light source unit 1 emits line laser light from a laser light source or emitted from an LED module. The structure etc. which irradiate the emitted light from a linear slit via a light-guide plate can be employ | adopted. In the present embodiment, the irradiation direction N1 of the linear light emitted from the light source unit 1 substantially matches the direction along the central axis Ox of the electrode 6. Note that the linear light emitted from the light source unit 1 may be one or plural (two or more).

  The camera unit 2 images the front end surface of the electrode 6 irradiated with linear light. For example, a CCD image sensor is employed. As understood from FIG. 1, the imaging direction Ny (the direction along the optical axis Oy of the camera unit 2) of the tip surface of the electrode 6 by the camera unit 2 is the irradiation direction N <b> 1 of the linear light from the light source unit 1 (electrode). 6 in the direction along the center axis Ox).

  2 and 3 show the front end surface of the electrode 6 irradiated with linear light. FIG. 2 shows a case where one linear light L1 is irradiated on the tip surface of the electrode 6, and FIG. 3 shows a case where two linear lights L1 and L2 are irradiated on the tip surface of the electrode 6. Indicates. FIG. 2A and FIG. 3A show a state viewed from the tip side of the electrode 6 in a direction along the central axis Ox of the electrode 6. FIG. 2B and FIG. 3B show images of the electrodes 6 captured by the camera unit 2.

  As understood from FIGS. 2A and 3A, the light source unit 1 irradiates the linear light L1 so as to pass through the intersection Px between the tip surface of the electrode 6 and the central axis Ox of the electrode 6. To do. As shown in FIG. 2B and FIG. 3B, in the image captured by the camera unit 2, the linear light L <b> 1 (L <b> 2) irradiated on the tip part surface of the electrode 6 is the tip part of the electrode 6. The curved surface shape reflects the curved surface shape. In the present embodiment, the light source unit 1 and the camera unit 2 are rotatable around the central axis Ox of the electrode 6 without changing the relative position of each other.

  The determination unit 3 determines whether the polishing state of the electrode 6 is good or not based on the image of the surface of the tip of the electrode 6 captured by the camera unit 2.

  At the time of welding work by spot welding, a welding current of a predetermined value flows between the pair of electrodes 6 and 6 while sandwiching a welding object (workpiece) with a predetermined pressing force by a pair of electrodes as spot welding electrodes. The pair of electrodes 6 and 6 have their tips worn by repeated welding operations and change in shape, but are polished to have a desired shape using a polishing apparatus (not shown). The polishing apparatus includes a cutter having a shape corresponding to the tip shape of the pair of electrodes 6 and 6. The polishing operation of the electrodes 6 and 6 is performed by rotating the cutter while pressing the cutter between the pair of electrodes 6 and 6.

  The determination of the quality of the electrode tip by the determination unit 3 is performed based on control by a control panel (not shown), for example. The control panel performs drive control of a welding robot (not shown) equipped with a pair of electrodes. The control panel also performs drive control of the polishing apparatus. For example, during a welding operation, control signals are output from the control panel to the welding robot, and detection signals from various sensors are input to the control panel. Further, during the polishing operation, various detection signals are input to the control panel while a control signal is output from the control panel to the welding robot and the polishing apparatus.

  In the present embodiment, for example, a reference image serving as a reference for determination by the determination unit 3 is stored in the control panel. This reference image is an image of the surface of the tip of the electrode 6 captured by the camera unit 2 when the tip of the electrode 6 after polishing is finished in a desired shape.

  When determining the quality of the electrode tip in the determination unit 3, first, the polished electrode 6 is disposed at an appropriate position with respect to the light source unit 1. Next, the light source unit 1 irradiates the tip surface of the electrode 6 with linear light, and the camera unit 2 images the tip surface of the electrode 6. Here, for example, the light source unit 1 and the camera unit 2 are rotated by a predetermined angle around the central axis Ox of the electrode 6, and a plurality of images having different rotational phases are captured at each predetermined angle. Next, the determination unit 3 compares the captured image with the reference image read from the storage unit of the control panel, and, for example, according to the degree of coincidence or difference between the captured image and the reference image. The quality of the polished state at the tip of the electrode 6 is determined. In addition, the quality determination method of the polishing state of the electrode tip is not limited to the method of comparing the captured image and the reference image as described above. For example, a technique may be adopted in which image processing is performed on the captured image, the dimension of the tip portion of the electrode 6 is measured, and the quality is determined based on the measured dimension.

  Next, the operation of this embodiment will be described.

  In the spot welding electrode quality determination apparatus A1 of the present embodiment, the light source unit 1 irradiates the tip end surface of the electrode 6 with linear light, and the image of the tip end surface of the electrode 6 captured by the camera unit 2 is displayed. Based on this, the quality of the polished state of the tip of the electrode 6 is determined. The linear light L1 (L2) applied to the tip surface of the electrode 6 passes through the intersection Px between the tip surface and the center axis Ox of the electrode 6, and the surface of the tip surface of the electrode 6 by the camera unit 2 is detected. The imaging direction Ny (the direction along the optical axis Oy of the camera unit 2) is inclined with respect to the irradiation direction N1 of the linear light emitted from the light source unit 1 (the direction along the central axis Ox of the electrode 6). According to such a configuration, in the image captured by the camera unit 2, the linear light L <b> 1 (L <b> 2) irradiated on the tip end surface of the electrode 6 is a curve reflecting the curved shape of the tip end portion of the electrode 6. It becomes a shape. Since the quality of the polished state of the electrode 6 is determined based on the captured image in which the curved linear light L1 (L2) is reflected, each portion of the curved surface shape of the tip is restored to a predetermined curvature. It can be confirmed whether or not. Therefore, according to the present embodiment, a method for determining whether or not the curved surface shape at the tip of the electrode 6 is restored to a desired shape based on, for example, the amount of reflected light at the center of the electrode tip described in Patent Document 1 above. In comparison, it is possible to determine directly and accurately. As a result, it is possible to maintain welding quality after electrode polishing.

  FIGS. 4 to 6 and FIG. 8 show another example of the quality determination device for spot welding electrodes according to the present invention. In these drawings, the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment, and description thereof will be omitted as appropriate.

  The quality determination apparatus A2 shown in FIG. 4 includes a light source unit 1, a camera unit 2, and a determination unit 3. In the present embodiment, the arrangement configuration of the light source unit 1 and the arrangement of the camera unit 2 are different from the quality determination device A1 of the above embodiment.

  The light source unit 1 is configured to include four linear light sources 11 and 12, and two pairs of linear light sources 11 and 12 are arranged. For convenience of understanding, in FIG. 4, the paired linear light sources 11 and 12 are surrounded by dotted lines. As shown in FIG. 5, the linear light emitted from the paired linear light sources 11 and 12 is directed in the same direction, and the irradiation direction N1 of the linear light is relative to the central axis Ox of the electrode 6. It is inclined at a predetermined angle. Further, as shown in FIG. 6, the linear light emitted from the other pairs of linear light sources 11 and 12 is directed in the same direction, and the irradiation direction N2 of the linear light is the central axis of the electrode 6. It is inclined at a predetermined angle with respect to Ox.

  Further, as understood from FIGS. 5 and 6, in this embodiment, the imaging direction Ny (the direction along the optical axis Oy of the camera unit 2) of the tip surface of the electrode 6 by the camera unit 2 is the same as that of the electrode 6. It substantially coincides with the direction along the central axis Ox.

  FIG. 7 shows the surface of the tip portion of the electrode 6 irradiated with linear light. The figure shows a state viewed from the tip side of the electrode 6 in a direction along the center axis Ox of the electrode 6 and is an image of the electrode 6 taken by the camera unit 2.

  As understood from FIG. 7, the two pairs of linear light sources 11, 12 pass through the intersections Px between the tip surface of the electrode 6 and the central axis Ox of the electrode 6. Irradiate. As shown in the figure, in the image taken by the camera unit 2, the linear lights L 1 and L 2 irradiated on the surface of the tip of the electrode 6 have a curved shape reflecting the curved shape of the tip of the electrode 6. Become. In the present embodiment, the light source unit 1 (linear light sources 11 and 12) and the camera unit 2 are rotatable around the central axis Ox of the electrode 6 without changing the relative position of each other. Since the method for determining the quality of the electrode tip in the determination unit 3 is the same as that in the above embodiment, the description thereof is omitted.

  Next, the operation of this embodiment will be described.

  In the spot welding electrode quality determination device A2 of the present embodiment, the light source unit 1 irradiates the tip end surface of the electrode 6 with linear light, and the image of the tip end surface of the electrode 6 imaged by the camera unit 2 is displayed. Based on this, the quality of the polished state of the tip of the electrode 6 is determined. The linear lights L1 and L2 irradiated on the tip surface of the electrode 6 pass through the intersection Px between the tip surface and the center axis Ox of the electrode 6, and the camera unit 2 images the tip surface of the electrode 6. The direction Ny (the direction along the optical axis Oy of the camera unit 2) is inclined with respect to the irradiation directions N1 and N2 of the linear light emitted from the light source unit 1 (linear light sources 11 and 12). According to such a configuration, in the image captured by the camera unit 2, the linear lights L <b> 1 and L <b> 2 irradiated on the tip end surface of the electrode 6 are curved shapes reflecting the curved shape of the tip end portion of the electrode 6. It becomes. Then, since the quality of the polished state of the electrode 6 is determined based on the captured image in which the curved linear lights L1 and L2 are reflected, whether or not each part of the curved surface shape of the tip is restored to a predetermined curvature You can check whether or not. Therefore, according to the present embodiment, a method for determining whether or not the curved surface shape at the tip of the electrode 6 is restored to a desired shape based on, for example, the amount of reflected light at the center of the electrode tip described in Patent Document 1 above. In comparison, it is possible to determine directly and accurately. As a result, it is possible to maintain welding quality after electrode polishing.

  The quality determination device A3 shown in FIG. 8 includes a light source unit 1, a camera unit 2, and a determination unit 3. In the pass / fail judgment apparatus A2 of the above embodiment, the pass / fail judgment is made for one electrode 6. However, in the pass / fail judgment apparatus A3 of the present embodiment, the pass / fail judgment is performed for the pair of electrodes 6 and 6. Is configured to be possible.

  Two sets of the light source unit 1 and the camera unit 2 are provided corresponding to each of the pair of electrodes 6 and 6. The light source unit 1 corresponding to each electrode 6 includes four linear light sources 11 and 12 similar to the case of the quality determination device A2 shown in FIG. That is, the irradiation direction N1 of the linear light emitted from the paired linear light sources 11 and 12 and the irradiation direction of the linear light emitted from the other paired linear light sources 11 and 12 (not shown) 6 corresponding to the irradiation direction N2) is inclined at a predetermined angle with respect to the central axis Ox of the electrode 6, respectively. Further, the linear light sources 11 and 12 irradiate the linear light so as to pass through the intersection point Px between the tip surface of the electrode 6 and the center axis Ox of the electrode 6.

  In the present embodiment, the direction along the optical axis Oy of the camera unit 2 is perpendicular to the direction along the central axis Ox of the electrode 6. Further, a right-angle prism mirror 4 is interposed between the electrode 6 and the camera unit 2. Thereby, the imaging direction Ny of the tip part surface of the electrode 6 by the camera part 2 is substantially in agreement with the direction along the central axis Ox of the electrode 6. The light source units 1 and 1, the camera units 2 and 2, and the right-angle prism mirrors 4 and 4 having such an arrangement are supported by the housing 5 and integrated. The housing 5 is rotatable around the central axis Ox of the electrode 6. Since the method for determining the quality of the electrode tip in the determination unit 3 is the same as that in the above embodiment, the description thereof is omitted. Note that when the quality of the electrode tip is determined, the casing 5 is rotated by a predetermined angle around the central axis Ox of the electrode 6 to capture a plurality of images having different rotation phases. In the present embodiment, each light source unit 1 includes four linear light sources 11 and 12 (two pairs of linear light sources 11 and 12). Is not limited to this. For example, if the number of the linear light sources 11 and 12 included in each light source unit 1 is further increased, the tip shape of the electrode 6 can be grasped more accurately per one imaging.

  Next, the operation of this embodiment will be described.

  In the spot welding electrode quality determination apparatus A3 according to the present embodiment, the light source unit 1 irradiates the tip end surface of the electrode 6 with linear light, and the image of the tip end surface of the electrode 6 captured by the camera unit 2 is displayed. Based on this, the quality of the polished state of the tip of the electrode 6 is determined. The linear light applied to the tip surface of the electrode 6 passes through the intersection Px between the tip surface and the center axis Ox of the electrode 6, and the imaging direction Ny ( The direction along the central axis Ox of the electrode 6 is inclined with respect to the irradiation direction N1 (N2) of the linear light emitted from the light source unit 1 (linear light sources 11, 12). According to such a configuration, in the image captured by the camera unit 2, the linear light irradiated on the surface of the distal end portion of the electrode 6 has a curved shape reflecting the curved surface shape of the distal end portion of the electrode 6. Then, since the quality of the polished state of the electrode 6 is determined based on the captured image in which the curved linear light is reflected, it is determined whether or not each portion of the curved surface shape of the tip portion has been restored to a predetermined curvature. Can be confirmed. Therefore, according to the present embodiment, a method for determining whether or not the curved surface shape at the tip of the electrode 6 is restored to a desired shape based on, for example, the amount of reflected light at the center of the electrode tip described in Patent Document 1 above. In comparison, it is possible to determine directly and accurately. As a result, it is possible to maintain welding quality after electrode polishing.

  Furthermore, in this embodiment, it is possible to determine whether the polishing state is good or not for the pair of electrodes 6 and 6 at the same time. Therefore, it is possible to efficiently perform the work related to the quality determination of the pair of electrodes 6 and 6.

  Although the embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the above-described embodiment. The specific configuration of each part of the present invention can be variously changed.

  In the above embodiment, the case where linear light is used as the determination light has been described, but the present invention is not limited to this. As the light for determination, for example, light having a specific pattern shape such as a mesh shape, or light having a structure in which a shade is formed on the surface of the electrode tip by providing a shield in the optical path to the electrode tip is used. Also good. Further, the determination light emitted to the surface of the tip of the electrode does not necessarily have to pass through the intersection of the surface of the electrode tip and the center axis of the electrode. Furthermore, the arrangement of the light source unit and the camera unit is not limited to the arrangement shown in the above embodiment.

A1, A2, A3 Pass / fail judgment device 1 Light source unit 11, 12 Linear light source 2 Camera unit 3 Determination unit 4 Right angle prism mirror 5 Case 6 Electrode L1, L2 Linear light N1, N2 Irradiation direction Ny Imaging direction Ox Central axis ( Electrode center axis)
Oy optical axis (optical axis of camera)
Px intersection

Claims (1)

An apparatus for determining whether the state of polishing of the tip of the electrode for spot welding is good or bad,
A light source unit that emits determination light to the tip surface of the electrode;
A camera unit that images the tip surface irradiated with the determination light;
A determination unit that determines the quality of the polishing state of the electrode based on an image of the surface of the tip imaged by the camera unit,
An apparatus for determining the quality of a spot welding electrode, wherein an imaging direction of the surface of the tip portion by the camera unit is substantially inclined with respect to an irradiation direction of the determination light by the light source unit.

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