JPH02224876A - Method for aligning resistance welding - Google Patents

Abstract

PURPOSE:To align welding terminals and welding electrodes with high accuracy without requiring skillfulness by detecting the welding terminals based on welding terminal patterns for alignment obtained by picking up the welding terminals on images and adding the offset quantity to detection coordinates at this time. CONSTITUTION:At the time of performing resistance welding of a wire 8, etc., to the welding terminals 7a - 7d of material 6 to be welded mounted on a movable table 1, the terminals 7a - 7d and the welding electrodes 13 and 14 are aligned in the following manner. Namely, an aligning mark in the visual range of an image pickup device 21 arranged in close vicinity to position coordinates and the electrodes 13 and 14 when a mark 20 having an electrode shape provided on the table 1 and the electrodes 13 and 14 are aligned and the mark 20 are aligned. The offset quantity of the electrodes 13 and 14 and the device 21 is then obtained from the position coordinates at this time and the welding terminal patterns for alignment are made out. After this, the terminals 7a - 7d are detected by the image pickup of the device 21 based on the patterns and the above-mentioned offset quantity is added to the detection coordinates at this time and the terminals 7a - 7d and the electrodes 13 and 14 are aligned.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an alignment method for resistance welding.

(Prior art) In a resistance welding device, for example, a pair of positive and negative welding electrodes is brought into contact with a welding terminal of a workpiece at a predetermined pressure through a wire or the like, and in this state, electricity is passed between each welding electrode. This causes heat to be generated. Then, there is a method that uses this heat to melt the wire or the like and weld the wire or the like to the welding terminal. By the way, in such a welding device, if the pair of welding electrodes are not accurately aligned with the welding terminal, welding defects will occur and highly accurate welding will not be possible. Therefore, the welding terminal and the welding electrode are aligned, but this alignment is done by visual inspection by an operator. For this reason,
In particular, when the shape of the welding terminal becomes small, it becomes difficult to align it with high precision. Furthermore, the alignment accuracy is greatly influenced by the skill level of the worker.

(Problems to be Solved by the Invention) As described above, it is difficult to align the welding terminal and the welding electrode with high precision, and the operator is required to be highly skilled.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a resistance welding positioning method that allows highly accurate positioning of a welding terminal and a welding electrode without requiring any skill.

[Configuration of the Invention (Means and Effects for Solving the Problems) The present invention provides a method for connecting a welding terminal and a welding electrode when resistance welding a wire or the like to a welding terminal of a workpiece placed on a movable table. In the positioning method for resistance welding, the position coordinates and the position within the field of view of an imaging device installed close to the welding electrode when the electrode shape mark provided on the moving table and the welding electrode are aligned. The amount of offset between the welding electrode and the imaging device is determined from the position coordinates when the alignment mark and the electrode shape mark are aligned, and the welding terminal is imaged by the imaging device to create a welding terminal pattern for alignment. After that, based on the created welding terminal pattern, the welding terminal is detected by imaging with an imaging device, and an offset amount is added to the detected coordinates at this time to align the welding terminal and the welding electrode to achieve the above purpose. This is a positioning method for resistance welding.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a resistance welding apparatus to which a resistance welding positioning method is applied. In the figure, reference numeral 1 denotes a moving table 7, and this moving table 1 has a θ table 3 provided on an XY table 2. The XY child table is driven by an XY child table moving circuit 4 to move in the XY force direction, and the θ table 3 is driven by a θ table drive circuit 5 to move in the θ direction. Incidentally, a workpiece 6 to be welded is placed on this θ table 3. Each welding terminal 7a to 7d is provided on this workpiece 6, and among these welding terminals 7a to 7d, welding terminal 7a and 7b
A wire 8 is welded between the welding terminals 7c and 76 and between the welding terminals 7c and 76.

On the other hand, an electrode holder 11 is provided on the support 10 so as to be movable in the vertical direction, that is, in the direction of arrow (A). Note that the electrode holder] 1 is moved by an electrode movement drive circuit 12. The electrode holder 1] holds the negative welding electrode 13 and the positive welding electrode 14 with their longitudinal directions facing up and down, respectively.
A welding drive circuit] 5 is connected to the welding drive circuit 14 so that electricity is supplied thereto. Further, a wire supply section in which the wire 8 is wound around a reel 16 is provided at the upper part of the support body 10. Note that 17 is a wire cutting mechanism that moves near the welding terminals 7a to 7d and cuts the wire 8 with a blade 18.

Now, a negative electrode shape mark 20 having the same shape as the tip shape of the negative welding electrode 13 is provided on the θ table 3.

Further, an imaging device 21 is provided in the vicinity of the positive welding electrode 14 and supported by the electrode holder 11 . The field of view of this imaging device 21 is directed onto the θ table 3,
The output image signal is sent to the image processing circuit 22 and stored as image data. The image data obtained by this image processing circuit 22 is sent to an image synthesis circuit 23. Further, a cursor signal indicating a cursor having the same shape as the tip shape of the negative welding electrode 13 is inputted to the image synthesis circuit 23 from the cursor generation circuit 24 . This image synthesis circuit 23 is connected to the imaging device 2
It has a function of fixedly arranging the image data of a cursor at a predetermined position of the image data obtained by one image capture and composing the image data. This composite image is displayed on monitor television 2.
5 and will be displayed.

The main control circuit 26 includes an XY table drive circuit 4, a θ table drive circuit 5, an electrode movement drive circuit 12, and a welding drive circuit 1.
5, a function of sending control signals to each of them to execute resistance welding control, an XY child table motion circuit 4, a θ table drive circuit 5, an image processing circuit 22, and a cursor synthesis circuit 2.
It has a function of sending a control signal to each of the positions 3 and 3 to perform positioning control.

Next, the positioning operation of the apparatus configured as described above will be explained.

First, the amount of offset between the negative welding electrode 13 and the imaging device 21 is determined. That is, the main control circuit 26
Control signals are sent to the child table movement circuit 4 and the θ table drive circuit 5, respectively, to move the XY table 2 in the XY force direction and rotate the θ table 3 in the θ direction, as shown in FIG. The negative electrode shape mark 20 is positioned directly below the negative welding electrode 13 for alignment.

Note that, at this time, fine adjustment of the positioning is performed by visual inspection by the operator. When the welding electrode 13 and the negative electrode shape mark 20 are aligned in this way, the position coordinate A of the negative electrode shape mark 20 at this time is stored in the main control circuit 26.

Next, the main control circuit 26 sends control signals to the XY child table motion circuit 4 and the θ table drive circuit 5, respectively, to bring the negative electrode shape mark 20 into the field of view of the imaging device 21 as shown in FIG. At this time, the main control circuit 26 sends a control signal to the image processing circuit 22 to start the operation. Thereby, the image signal output from the imaging device 21 is A/D (analog/digital) converted in the image processing circuit 22 and stored as image data. The image synthesizing circuit 23 receives the image data from the image processing circuit 22, synthesizes cursor image data on this image data, and sends the synthesized image data to the monitor television 25. Thus, on the screen of this monitor television 25, for example, a negative electrode shape mark 20 and a fixedly arranged cursor 3 as shown in FIG.
0 is displayed. Then, while viewing the image displayed on the monitor television 25, the worker aligns the negative electrode shape mark 20 with the cursor 30.

Note that FIG. 5 shows the result when the negative electrode shape mark 20 and the cursor 30 are aligned. Then, when the negative electrode shape mark 20 and the cursor 30 are aligned, the main control circuit 26 stores the position coordinates B of the negative electrode shape mark 20 at this time.

However, the main control circuit 26 calculates and determines the difference between the previously stored position coordinates A and B, and uses this difference between the negative welding electrode 13 and the cursor fixed within the field of view of the imaging device 21. It is stored as an offset amount between the position of 30 and the position of 30.

Next, the main control circuit 26 sends control signals to the XY child table movement circuit 4 and the θ table drive circuit 5, respectively, to bring the welding terminal 7a of the workpiece 6 into the field of view of the imaging device 21.

Then, as shown in FIG. 6, the welding terminal 7a is moved so that a part of the welding terminal 7a overlaps the cursor 30. By the way, moving the position of the welding terminal 7a in this way is
This is because the position of the cursor 30 corresponds to the actual position of the negative welding electrode 13. Therefore, it is assumed that the positive welding electrode 14 is placed next to the negative welding electrode 13. However, if the welding electrode 7a is arranged so as to partially overlap the cursor 30, the positive and negative welding electrodes 1, 4, and 13 will come into contact with the welding electrode 7a. Note that the welding electrode 14 is not displayed on the screen of the monitor television 25.

Thereafter, when the positioning of the welding electrode 7a with respect to the cursor 30 is completed, the image processing circuit 22 takes in the image signal from the imaging device 21 according to a command from the main control circuit 26, and the seventh
It is converted into image data as shown in the figure, and this image data is stored as a welding terminal pattern for positioning. Then, the main control circuit 26 stores the position coordinates of the welding terminal 7a at this time. As described above, the amount of offset between the negative welding electrode 13 and the imaging bag wt21 is determined, and the welding terminal pattern of the welding terminal 7a is obtained.

Next, move on to resistance welding work. When the workpiece 6 for welding work (the numbers 6.7a to 7d indicating the workpiece and each welding terminal are the same) is placed on the θ table 3, the main control circuit 26 Control signals are sent to the motion circuit 4 and the θ table drive circuit 5, respectively, to move the welding terminal 7a to the position coordinates of the welding terminal 7a determined in the above operation.

When the welding terminal 7 is moved in this manner, the image processing circuit 22 compares the image data obtained by imaging with the imaging device 21 and the welding terminal pattern, and determines the welding terminal 7 according to the welding terminal pattern.
Find the amount of positional deviation of a. Next, the main control circuit 26 sends control signals to the XY child table movement circuit 4 and the θ table drive circuit 5, respectively, to move the welding terminal 7b to the position coordinates of the welding terminal 7b obtained in the above operation, and The image data obtained by imaging is compared with the welding terminal pattern to determine the amount of positional deviation of the welding terminal 7b with respect to the welding terminal pattern. Then, the amount of positional deviation of each welding terminal 7c, 7d with respect to the welding terminal pattern is determined in the same manner. However, the main control circuit 26 controls the X
Find the correction amounts in the Y force direction and the θ direction. Then, the main control circuit 26 takes into account the offset amount and correction amount from the current position and sends control signals to the XY child table movement circuit 4 and the θ table drive circuit 5, respectively. Thereby, the welding terminal 7a is positioned directly below each welding electrode 13, 14 as shown in FIG. After that, the main control circuit 26 sends control signals to the electrode movement drive circuit 12 and the welding drive circuit 15, respectively, so that the electrode holding part 11 is lowered and each welding electrode 1
3.14 are brought into contact with the welding terminal 7a with a predetermined pressure, and the wire 8 is interposed between each welding electrode 13.14 and the welding terminal 7a. Then, electricity is applied in this state, and heat is generated by this electricity supply and the wire 8 is melted.

As a result, the wire 8 is welded to the welding terminal 7a. Note that after this welding, the electrode holder 11 is lifted up. Next, the main control circuit 26 sends control signals to the XY child table movement circuit 4 and the θ table drive circuit 5 to position the welding terminal 7b directly below each welding electrode 13, 14, taking into account the correction amount obtained by the above operation. Send. Then, when the welding terminal 7b is positioned directly below each welding electrode 13, 14, the wire 8 is welded to the welding terminal 7b in the same manner as described above. Thereafter, the wire 8 is also connected between the welding terminals 7c and 7d by the same operation.
is welded.

In this way, in the above embodiment, the position coordinates when the negative electrode shape mark 20 and the welding electrode 13 are aligned, and when the cursor 30 within the field of view of the imaging device 21 and the negative electrode shape mark 20 are aligned Find the offset amount between the welding electrode 13 and the imaging device 21 from the position coordinates of
Furthermore, the welding terminal 13 is imaged to create a welding terminal pattern, and each welding terminal 7a to 7d is then detected based on this welding terminal pattern, and an offset amount is added to the detected coordinates at this time to perform positioning. Therefore, the wire 8 can be welded with high accuracy regardless of the skill level of the worker. In particular, even if the shapes of the welding terminals 7a to 7d become smaller, the welding terminals 73 to 7d and the welding electrodes 13, 14 can be aligned with high precision.

In addition, even if each workpiece 6 is placed on the θ table 3 one after another, positioning is performed using the offset amount and the positional deviation amount of each welding terminal with respect to the welding terminal pattern. Highly accurate positioning is possible without positional variations. Furthermore, even if there are obstacles around the welding terminal, the cursor 30 is used, so positioning can be performed without being hindered by obstacles.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, although the correction amount was determined using two welding terminals 7a, 7b, the correction amount may be determined for each of the welding terminals 7a, 7b, . . . or by using a large number of terminals. Further, the objects 6 to be welded may be successively resistance welded by a feeding mechanism. Further, when aligning the welding terminals 78 to 7d and the welding electrodes 13.14, the welding electrodes 13.14 may be moved, and in this case, the welding terminals 7b to 7a may be welded in this order. Also, cursor 30
may be set to correspond to the position of only the positive welding electrode 14 or to the position of both the negative welding electrode 13 and the positive welding electrode 14.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a resistance welding positioning method that allows highly accurate positioning of a welding terminal and a welding electrode without requiring any skill.

[Brief explanation of the drawing]

1 to 8 are diagrams for explaining the positioning method for resistance welding according to the present invention, in which FIG. 1 is a block diagram of a resistance welding apparatus to which this method is applied, and FIGS. The figure is a schematic diagram for explaining the function of determining the offset amount.
5 and 5 are diagrams showing the alignment between the electrode shape mark and the cursor, FIG. 6 is a diagram showing the alignment between the welding terminal and the cursor 30, FIG. 7 is a schematic diagram showing the welding terminal pattern, and FIG. The figure is a diagram showing the alignment results. 1...Moving table, 2...XY table, 3...
・θ table, 6... object to be welded, 78-7d... welding terminal, 8... wire, 13.14... welding electrode,
20... Negative electrode shape mark, 21... Imaging device, 2
2... Image processing circuit, 23... Image synthesis circuit, 24
...Cursor generation circuit, 25...Monitor television. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (1)

[Claims] In a resistance welding positioning method for aligning a welding terminal and a welding electrode when resistance welding a wire or the like to a welding terminal of a workpiece placed on a movable table, Positional coordinates when the electrode shape mark and the welding electrode are aligned, and positional coordinates when the electrode shape mark is aligned with the alignment mark within the field of view of an imaging device provided close to the welding electrode. The amount of offset between the welding electrode and the imaging device is determined from the above, the welding terminal is imaged by the imaging device to create a welding terminal pattern for positioning, and then based on the created welding terminal pattern, a positioning method for resistance welding, characterized in that the welding terminal is detected by imaging with the imaging device, and the positioning of the welding terminal and the welding electrode is performed by adding the offset amount to the detected coordinates at this time. .