JPH08271236A - Condition inspection device for welding electrode - Google Patents

Abstract

PURPOSE: To provide a condition inspection device for a welding electrode which decides good/bad of an electrode after welding and grinding. CONSTITUTION: A camera 2 taking in a picture of a tip of a welding electrode, and a picture processing device 5 processing the image taken in by the camera 2, are provided, and, based on the picture of the tip of the welding electrode, after used for welding, taken in by the camera 2, judgement as to whether grinding of the welding electrode is needed or not is done, and further, based on the image of the tip of the welding electrode, after grinding, taken in by the camera 2. judgement as to whether the welding electrode is ground sufficiently for use for later welding is done.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding electrode condition inspection device for examining the wear condition of electrodes used for welding.

[0002]

2. Description of the Related Art When a welding robot repeats spot welding or the like, there is a possibility that the tip of an electrode may be worn or impurities may be attached to the tip to prevent normal welding. In order to detect such a state, there is, for example, JP-A-1-192486 as a welding electrode state inspection device. In this conventional technology, the image sensor detects the brightness of the electrode tip,
The signal is image-processed and the tip of the electrode is measured to speed up the inspection and improve the inspection accuracy. Specifically, fix the electrode to be measured to a jig,
The image in the long axis direction of the electrode at the electrode tip is captured.

[0003]

When it is determined that the use of welding is not preferable as a result of inspection by the conventional state inspection device, the electrode is removed from the inspection device and the tip thereof is polished. It is conceivable to reuse the electrodes. However, in the past, since the quality of the electrode after polishing was judged by humans, the efficiency was poor and the accuracy of the judgment was not high.

The present invention has been made in view of the above circumstances, and an object thereof is to weld a welding electrode for a human to judge whether or not the electrode after polishing can be reused for welding. I am proposing a state inspection device.
Another object of the present invention is to propose a welding electrode condition inspection device capable of determining the quality of an electrode after welding and the quality of an electrode after polishing.

[0005]

In order to achieve the above object, an apparatus for inspecting a wear state of a welding electrode according to a first aspect of the present invention is a camera means for capturing an image of a tip of a polished welding electrode. And a means for judging whether the welding electrode is used for welding or not based on the captured image.

Since the electrodes are inspected by image processing after the polishing, it is possible to efficiently carry out the polishing without the need for manpower. An apparatus for inspecting a state of a welding electrode according to claim 2 has a camera means for capturing an image of the tip of the welding electrode and an image captured by the camera means for the tip of the welding electrode after being used for welding. Based on an image captured by the camera means at the tip of the welding electrode after polishing, the first determining means for determining whether the polishing of the welding electrode is necessary or not is performed. It is characterized by comprising a second judging means for judging whether the welding electrode has been polished to such an extent that it can be used for subsequent welding.

After welding, it is judged whether or not it is worn to such an extent that polishing is necessary based on the image processing of the electrode image, so that the judgment becomes accurate. Furthermore, if it is determined that the wear is present, the polishing is performed and the inspection by the image processing is performed again after the polishing, so that the above effect is doubled. According to the third aspect of the present invention, further, the third determination means for determining whether or not the welding electrode should be replaced is provided based on the image of the electrode captured by the camera means. Judgment of the replacement time will also be made, and more efficient operation is possible.

According to the fourth aspect of the present invention, since the first judging means and the second judging means make judgments based on pattern matching of images, it is possible to make a digital wear judgment. According to the invention of claim 5, the first determining means and the second determining means determine the area of the pixel having the first value and the area of the pixel having the second value in the image of the electrode. Since the determination is based on the ratio, it is possible to make an analog determination of the degree of wear (a determination that is strong against ambiguity).

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows welding / welding to which the present invention is applied.
It is a perspective view showing an example of an inspection system. In the figure, reference numeral 1 is a welding robot, and a welding gun 3 is attached to the tip of an arm thereof. Reference numeral 2 is a CCD camera for capturing an image of the welding electrode portion at the tip of the welding gun 3. The camera 2 is set at a fixed position. The image processing device 5 performs a predetermined process on the image captured by the camera 2 and inspects the degree of wear of the electrode to determine whether or not the electrode can be used. Further, 4 is an electrode polishing device set at a fixed position, which polishes the electrode.

The robot controller 7 controls the operation of the welding robot 1 (movement of the gun 3 to the welding position, control of start / stop of welding, movement of the gun 3 to the inspection position), and also controls the polishing device 4. To do. Robot controller 7
Controls the image processing apparatus 5 via the personal computer 6. The controller 7 can interpret and execute commands for controlling the robot 1, the welding gun 3, and the polishing apparatus 4. On the other hand, regarding image processing, for example, since image processing for pattern recognition or the like is executed in the image processing apparatus 5, only a command for image processing is prepared in the controller 7, and the actual execution of this command is It is performed in the processing device 5. When the controller 7 finds the image processing command, it passes the command (with parameters) to the personal computer 6. The personal computer 6 controls the interface between the image processing device 5 and the controller 7, interprets the image processing command received from the controller 7, and causes the image processing device 5 to execute the predetermined image processing defined by the command. . Since the image processing in the device 5 is well known, its detailed description is omitted here.

As described above, the welding robot 1 can move the arm to the welding position (not shown) and the inspection position. FIG. 1 shows a state in which the robot 1 has moved the tip of the welding gun 3 to an inspection position, that is, a position (teaching point) where the tip of the welding electrode is photographed by the camera 2. When the image taken by the camera 2 is processed and the necessity of polishing is recognized, the controller 7 moves the arm to the position (teaching point) where the tip of the welding gun 3 is polished by the polishing device. Let it polish.

In FIG. 2, a shank 11 is attached to the tip of the welding gun 3.
1 shows the electrode 10 mounted via. FIG. 3 shows the state of wear as a result of the electrodes being used. When the abrasion occurs, the tip of the portion A of the electrode 10 in FIG. 2 is abraded to form 13 in FIG. 3, and the impurity 13 is further attached to the tip. FIG. 4 is a block diagram showing an internal configuration of the image processing device 5. The image processing device 5 is internally provided with the CPU 2
0, ROM 21, RAM 22, disk 23, RS232C interface 2 for controlling communication with the personal computer 6
4 and. The CPU 20 has a ROM 21 and a RAM 22.
Pattern matching and binarization processing are performed according to the program stored in. The disk 23 stores a template file required for pattern matching.

FIG. 5 shows a control procedure of a program incorporated in a memory (not shown) of the controller 7. The CPU (not shown) of the controller 7 controls the image processing apparatus 5 via the personal computer 6 by executing the control procedure of FIG. The control procedure of FIG. 5 will be described below. Incidentally, it is assumed that the data file necessary for the pattern matching is previously stored in the disk 23 before the execution of the control procedure.

In step S2 of FIG. 5, the gun 3 is moved to the welding position taught in advance. In step S4, welding is performed at this position. Step S6
Then, the gun 3 is moved to the inspection position taught in advance. When moved to this inspection position, the welding electrode at the tip of the gun 3 is positioned in front of the camera 2 as shown in FIG.
In step S8, the image capture command is sent to the personal computer 6
To the image processing device 5 via. Upon receiving this command, the image processing device 5 causes the camera 2 to start capturing an image.
As shown in FIG. 6, the angle of view of the camera 2 is set so as to capture the image of the welding electrode from the lateral direction. Therefore, the camera 2 captures the image at the position shown in FIG. 2A or FIG. 3B. This image is sent to a memory (not shown) of the image processing device 5.

The controller 7 sends a pattern matching command to the image processing apparatus 5 in step S10. Upon receiving this command, the image processing device 5 determines the degree of wear based on the image stored in the memory. In the control procedure of FIG. 5 ,: If the axial length of the electrode is reduced to a predetermined length, it is judged that the electrode should be replaced. : If the degree of deformation of the tip of the electrode in the lateral direction is judged to be outside the permissible range as compared with the contour of the electrode when it is new, it is judged to be polished. : If the ratio of the area of the lateral image of the electrode tip to the white image portion and the black image portion decreases, that is, if the increase of the black image portion due to impurities exceeds the allowable limit,
Determined to be polished. This is because the copper-colored portion of the electrode is usually recognized as a white image when the binarization process is performed (by appropriately selecting the threshold value), and the portion having impurities attached is recognized as a black image. The above-mentioned allowable limit is obtained in advance by experiments or the like.

As described above, the disk 23 has an image previously taken when the electrode is new (image A in FIG. 2).
The features (outline, center of gravity, etc.) of the image are stored in advance based on. In step S10, the features of the image captured in step S8, that is, the outline and the center of gravity are calculated, and the outline of the new product and step S1 are calculated.
Shape change of the electrode tip based on the change from the outline calculated with 0 (whether the outer shape is within the allowable dimensions)
And external deformation (whether there is no dropout or deformation). Deformation and the like due to wear of the electrodes are prominent in changes in the outer shape of the electrodes in the lateral direction. In this embodiment, the electrodes are photographed from the lateral direction, which is advantageous for detecting such deformation. In step S12, further judgment is made.

In step S14, it is determined whether or not the size of the electrode has been shortened to the specified length to be replaced based on the determination of. If it is shorter, the process proceeds to step S30, and the operator is instructed to replace the electrode. If it is determined in step S14 that the electrodes are not worn to the extent of replacement, it is determined in step S16 whether the electrodes are not worn to the extent necessary for polishing. If it is determined that polishing is necessary, the electrode is moved to the polishing position at 18. When the polishing is completed, the process returns to step S6 and the inspection is performed again. If it is determined in step S16 of the inspection process again that the wear has been recovered, the process returns to the bath 2 to restart the welding.

As described above, according to the apparatus of this embodiment: Since the electrodes are inspected by the image processing after the polishing, it is possible to efficiently check whether the polishing has been normally performed without the need of manpower. Done. : After welding, it is determined whether or not it has worn to such an extent that polishing is necessary based on image processing of an image from the lateral direction of the electrode, so the determination is accurate. Furthermore, if it is judged to be worn, polishing is performed, and after this polishing, inspection by image processing is performed again, so the effect of is doubled. : Judgment is made because the wear inspection is performed by pattern matching (digital detection of shape change) and change of area ratio of white image portion and black image portion (analog detection of shape change). Will be accurate. : As for the wear inspection, the judgment of the polishing time of the electrode and the judgment of the quality of the polishing result of the electrode are performed together, so that the efficient operation is possible. : Furthermore, since the time to replace the electrode is also determined,
More efficient operation is possible. : Judgment of electrode polishing time, judgment of electrode polishing result, and judgment of electrode replacement time are all performed based on image processing, which requires hardware because it can be dealt with by changing or adding a program. Investment can be minimized.

<Modification> The present invention can be variously modified without departing from the spirit thereof. For example, in the above embodiment,
Although the wear inspection is performed every welding, it may be modified such that the inspection is performed once every predetermined number of times. Further, the replacement is performed by judging whether or not the specified dimension is reached, but it may be replaced unconditionally if the polishing is performed a predetermined number of times.

[0020]

As described above, according to the welding electrode condition inspection apparatus of the present invention, it is possible to efficiently judge whether the electrode after polishing can be reused for welding on behalf of a human being. Can be done. Further, since it is possible to perform the quality judgment of the electrode after welding and the quality judgment of the electrode after polishing, it is possible to contribute to downsizing of the apparatus.

[Brief description of drawings]

FIG. 1 is a diagram showing an appearance of a welding / inspection system according to an embodiment of the present invention.

FIG. 2 is a diagram showing lateral characteristics of electrodes used in Examples.

FIG. 3 is a diagram showing a state in which the electrodes of the example are worn.

FIG. 4 is a diagram showing a configuration of an image processing apparatus in the embodiment system.

FIG. 5 is a diagram showing a control procedure of the robot controller 7.

FIG. 6 is a diagram showing a positional relationship between electrodes and a camera.

Claims (5)

[Claims] 1. An apparatus for inspecting a wear state of a welding electrode, comprising camera means for capturing an image of a polished tip of the welding electrode, and whether or not the welding electrode is used for welding based on the captured image. And a means for determining the quality of the welding electrode. 2. An apparatus for inspecting the state of a welding electrode, comprising camera means for capturing an image of the tip of the welding electrode, and image captured by the camera means for the tip of the welding electrode after being used for welding. Based on the image captured by the camera means at the tip of the welding electrode after polishing, and the first determining means for determining whether the polishing of the welding electrode is necessary or not. A welding electrode condition inspecting device, comprising: a second determining unit that determines whether the welding electrode is polished to a degree that can be used for subsequent welding. 3. The third determination means for determining whether or not the welding electrode should be replaced based on the image of the electrode captured by the camera means. State inspection device for welding electrodes. 4. The welding electrode state inspection apparatus according to claim 1, wherein the first determination unit and the second determination unit perform determination based on image pattern matching. 5. The first determining means and the second determining means are based on a ratio of an area of a pixel having a first value and an area of a pixel having a second value in an image of the electrode. The condition inspection device for a welding electrode according to claim 1, wherein the condition is determined.