JPH0446690A - Welding equipment - Google Patents

Abstract

PURPOSE:To detect a gap with high accuracy by setting a binarization reference level for each detection point photographed by an image pickup device, comparing a picture signal of each detection point to binarize this, detecting the central position of a gap of each detection point by these data and moving a welding torch on a center line. CONSTITUTION:The picture signal photographed by the image pickup device 3 is binarized by a binarization means based on the binarization reference level set for each detection point by level setting means 27 and 28. Accordingly, even if the intensity of reflected light has variance at each detection point, the proper binarization reference level for each detection point can be set and in its turn, the accurate gap can be detected. Consequently, the gap is detected by the constitution at the low cost and further, a threshold as a whole is not lowered and the gap can be detected with high accuracy by photographing plural detection points at the same time by the one camera to detect the gap.

Description

Detailed Description of the Invention [Purpose of the Invention (Industrial Application Field) The present invention provides continuous welding of parts to be welded by moving a welding torch relatively along a gap between the parts to be welded. This invention relates to a welding device that performs welding.

(Prior Art) In recent years, a welding device as shown in FIG. 4 has been developed to automate welding operations such as seam welding of vibrators. This welding device includes a vibrator 1 that is moved in the direction of arrow A (X-axis direction in X-Y coordinates) by a moving mechanism (not shown).
On the other hand, a welding torch 2 whose heat source is a laser beam is placed above it.
are arranged so as to be movable in the direction of arrow B (Y-axis direction). In order to cause the welding torch 2 to follow the groove gap 1a of the vibrator 1, a visual information processing device 4 including a camera 3 and the like is provided at the front side of the welding torch 2 in the drawing.

As shown in Japanese Unexamined Patent Publication No. 1-181990, this visual information processing device 4 irradiates two detection points of a vibrator 1 with semiconductor laser light from two slit light sources 5 and 6, and the reflected light is is received by the camera 3 and visualized, and the current position of the welding point W is determined based on the image signal. In this case, the photographed image 7 (monitor image) taken by the camera 3 becomes as shown in FIG. , Bright areas are indicated by hatching). Then, the control device 10 controls those two
The center positions a and b of the gap 1a at the detection points are detected, and these gap center positions a and b and these X
The welding point W is located on the straight line connecting the gap centers a and b based on the axial distance, the distance between the camera 3 and the welding torch 2, etc.
The position correction device 11 moves the welding torch 2 in the direction of arrow B (Y-axis direction) accordingly. By repeating this, the welding torch 2 comes to move following the gap 1a, and the gear lug 1a portion is continuously welded.

(Problem to be Solved by the Invention) By the way, in detecting the gap centers a and b based on the image signal of the camera 3 as described above, the image signal must be binarized by a hardware circuit due to processing speed. The data is processed and converted into binarized data, and the binarized data is input to a microcomputer for arithmetic processing. In this case, as illustrated in FIG. It is input into the digital circuit 14, but the binarization circuit 1
3, the image signal S■ from the analog circuit 12 is compared with a threshold value SL set in advance via a threshold value setting circuit 15 to be binarized.

However, in the above method, the gap centers a and b at two detection points are determined from one image signal of the camera 3.
However, since the threshold value SL set by the threshold setting circuit 15 is common to the two detection points, the following problem occurs.

That is, as shown in FIG. 6, for example, during the i-th horizontal scan of the monitor image 7, as shown in FIG.
(i) is output. These peak values are the threshold value SL
Since it is larger than , it can be determined that it is the surface of vibrator 1. Also,
As shown in (b) of the same figure, in the image signal SV (j) during the j-th horizontal scan, one detection point portion (
Since the peak value of the reflected light 9 portion) is below the threshold value SL, and the peak value of the reflected light 8 portion is greater than the threshold value SL, they are determined to be a gap and a surface, respectively.

In this way, when the level (peak value) of reflected light is approximately constant, there is no problem even if the threshold value SL is the same.

However, as shown in the same figure (C), for example, the image signal SV (k) during the th horizontal scan has different peak values in the reflected light portions 8 and 9, and both are originally larger than the threshold value SL. Although the two levels must be at the same level, one may be below the threshold SL and the other may be greater than the threshold SL. As a result, although it is actually the surface of the vibrator 1, it is determined to be the gap 1a, and as a result, gap identification cannot be performed successfully. This may be due to, for example, individual differences in the semiconductor laser light (peak oscillation wavelength or half-width) in the slit light sources 5 and 6, variations in adjustment of the optical system, or the projection angle of the slit light sources 5 and 6 or the light reception by the camera 3. There are differences in angle, etc., and these cannot be easily resolved.

In order to solve this problem, it is conceivable to lower the threshold value to SL-, for example, as shown in FIG. This results in a decrease in detection accuracy as a whole. It is also conceivable to provide two sets of visual information processing devices 4 with cameras 3 and below, but this poses a problem in that the entire device becomes expensive.

The present invention has been made in view of the above circumstances, and its purpose is to perform gap detection from image signals for a plurality of detection points, and to perform gap detection with an inexpensive configuration and with high accuracy. We provide welding equipment that can

[Structure of the Invention] (Means for Solving the Problems) The welding apparatus of the present invention is a welding device that simultaneously images a part of a workpiece to be welded located on the front side in the direction of relative movement of a welding torch at a plurality of detection points. a level setting means for setting a binarization reference level for each detection point photographed by the imager; and a level setting means for binarizing the image signal of each detection point by comparing it with the binarization reference level. digitization means, gap detection means for detecting the center position of the gap at each detection point based on the binarized data by the binarization means, and the center position of the gap at each detection point detected by the gap detection means. The structure is characterized by a position correction means for relatively moving the welding torch on a straight line connecting the two.

(Operation) According to the above means, the image signal photographed by the image pickup device is binarized by the binarization means based on the binarization reference level set for each detection point by the level setting means. Therefore, even if there are variations in the intensity of reflected light at each detection point, it is possible to set an appropriate binarization reference level for each detection point, which in turn makes it possible to perform accurate gap detection. Become.

In this case, since multiple detection points are simultaneously photographed using one imager, an inexpensive configuration can be used.
Furthermore, since the overall threshold value is not lowered, highly accurate detection can be performed.

(Embodiment) An embodiment in which the present invention is applied to seam welding of a vibrator will be described below with reference to FIGS. 1 to 4. Of the drawings, the appearance of the monitor screen 7 in FIG. 3 and the overall appearance in FIG. 4 are the same as those of the conventional example, so new illustrations are omitted and the same reference numerals are used.

FIG. 4 schematically shows the state of welding by the welding device 21 according to this embodiment. Here, 1 is a vibrator as an object to be welded, which has a gap 1a extending in the axial direction, and a gear 1a portion is joined by a welding device 21. The vibrator 1 is moved at a predetermined speed in the direction of an arrow A (X-axis direction in X-Y coordinates) by a moving mechanism (not shown), and the gap 1a is arranged approximately along the X-axis direction. It is extending. On the other hand, 2 is a welding torch, which is, for example, CO. It uses laser light as a heat source, and is disposed above the vibrator 1 so as to be movable in the direction of arrow B (Y-axis direction). In order to cause the welding torch 2 to follow the gap 1a of the vibrator 1, a camera 3 serving as an imager and two slit light sources are placed on the front side (front side in the figure) in the relative movement direction of the welding torch 2. A visual information processing device 4 consisting of 5, 6, etc. is provided. These slit light sources 5.6 are designed to irradiate semiconductor laser light onto two detection points on the vibrator 1, and the camera 3 receives the reflected light and images it. In this case, the laser beams from the slit light sources 5 and 6 are irradiated in a slit shape extending in a direction perpendicular to the direction in which the gap 1a extends. Therefore, the image taken by camera 3 (monitor image 7) is
As shown in the figure, a slit-shaped reflected light beam 8.9 interrupted at a portion corresponding to the width of the gap 1a is simultaneously photographed. In addition, in FIG. 3, brightly shining parts are shown by hatching for convenience.

The image signal from the camera 3 is input to the control device 10, and as described later, the control device 10 performs image processing to determine the current position of the welding point W, and the determined welding point W, the welding torch 2 is moved in the direction of the arrow B (in the Y-axis direction) by the position correction device 11 serving as the position correction means. In this case, as shown in FIG. The center positions a and b of the gap 1a at the detection point are detected, and these gap center positions a,
b, the distance between them in the X-axis direction, the distance between the camera 3 and the welding torch 2, etc., calculate the welding point W on the straight line connecting the gap centers a and b, and make the welding torch 2 follow it. It has become.

By repeating this process, the welding torch 2 will move into the gap 1a.
The parts to be joined are welded continuously.

Now, the control device 10 includes an image processing hardware circuit 22 which is a binarization means for disulfurizing the image signal from the camera 3, and a control device at each of the detection points based on the binarized data from the image processing hardware circuit 22. A CPU and memory (
(not shown), etc.

As shown in FIG. 1, the image processing hardware circuit 22 includes an analog circuit 23 into which the image signal from the camera 3 is input, and a signal SV from this analog circuit 23 for each valley detection point in this case. An image signal separation circuit 24 that separates the signals into two, SVl and SV2, and each of these signals SVI and SV
2, a digital circuit 26 to which the binary data binarized by the binarization circuit 25 is input, and the like. has been done. Two threshold setting circuits 27 serve as level setting means for setting the binarization reference level in the binarization circuit 25 for each signal SVI and SV2, respectively.
．． 28 are provided.

The arithmetic processing section receives data from the image processing hardware circuit 22, recognizes the gap 1a at each detection point, calculates center positions a and b of the gap 1a, and performs welding at a welding point W on a straight line connecting them. In order to move the torch 2, a correction signal is output to the position correction device 11. Note that the photographed image is displayed on the monitor image 7 (see FIGS. 2 and 3) using image data from the image processing hardware circuit 22.

Next, the operation of the above configuration will be described.

When the welding device 21 is started, a laser beam is irradiated from the welding torch 2 to the gear lug 1a portion of the pipe 1, and the gear lug 1a portion of the pipe 1 is heated and welded. And at the same time,
The vibrator 1 moves in the direction indicated by the arrow at a predetermined speed, thereby continuously welding the gap 18 portion. At this time, as described above, the image signal taken by the camera 3 is input to the control device 10 and processed, and the welding torch 2 is caused to follow the gap 1a.

Then, the gap center a is determined based on the image signal of the camera 3.
, b, the image signal is binarized by the image processing hardware circuit 22 and converted into binarized data. During the second horizontal scan, an image signal 5v(k) in which peaks appear corresponding to reflected lights 8 and 9 is output, as shown in FIG. 2(a). In this case, for example, individual differences (peak oscillation wavelength and half-value width) of the semiconductor laser beams in the slit light sources 5 and 6, adjustment variations in the optical system, or
Due to factors such as differences in the light projection angle of the slit light source 5.6 and the light reception angle of the camera 3, the image signal SV (k) may have different peak values in the reflected light 8 and 9 portions.

In this embodiment, the signal S■ from the analog circuit 23 is separated into two signals SV1 and SV2 by the image signal separation circuit 24. Therefore, as shown in (b) and (c) of the same figure, the image signal SV (k) is equal to the signal SVI
V2(k)l: Separated, and then in the binarization circuit 25, with the thresholds sL1 and SL2, which are the binarization reference levels set separately by the two threshold setting circuits 27 and 28, respectively. Binarization is performed by comparison. In this case, in the signal SVI (k) where a high peak of reflected light 8 appears,
A high threshold SLI is set, and for the signal SV2 (k) in which a relatively low peak of the reflected light 9 appears, a relatively low threshold SL2 is set accordingly. With this, the gap 1a and the surface of the pipe 1 can be determined separately in the reflected light 8 and 9 parts, so to speak.
The center positions a and b are calculated based on this binary data, and the welding torch 2 is moved to the welding point W in real time accordingly.

As described above, according to this embodiment, the center position a of the gap is determined from the image signals of the two detection points.

Since the current welding point W is detected by determining b, the position of the welding torch 2 can be corrected in real time regardless of the moving speed of the vibrator 1. The threshold setting circuits 27 and 28 set the binarization reference levels (thresholds SL1 and 5L2) for each detection point, so the threshold SL is different from the conventional one. Unlike the case where two detection points are common, it is possible to detect a gap with high precision and more accurately, and as a result, the quality of welding can be improved.

Further, since only one set of visual information processing devices 4 such as the camera 3 and the like is required as in the conventional case, the configuration can be completed at an inexpensive cost.

In the above embodiment, two detection points are photographed at the same time, but three or more detection points may be photographed, and the object to be welded is not limited to a vibrator, but two detection points. It can be applied to welding various things such as joining steel plates.

In addition, the present invention is not limited to the above-mentioned embodiments, and can be applied to, for example, a welding torch that is moved relative to a fixedly placed workpiece, and laser welding. The present invention is not limited to the present invention, but can be applied to other welding methods such as arc welding, and can be implemented with appropriate changes within the scope of the gist.

[Effects of the Invention] As is clear from the above explanation, the welding apparatus of the present invention detects gaps from image signals for a plurality of detection points, and uses a simple configuration for detecting gaps. Moreover, it has an excellent effect in that it can be performed with high precision.

[Brief explanation of drawings]

Figures 1 to 4 show an embodiment of the present invention. Figure 1 is a block diagram showing the electrical configuration of an image processing hardware circuit, and Figure 2 is a monitor screen and image signal waveform for explaining the operation. FIG. 3 is a plan view showing the state of the monitor screen, FIG. 4 is a perspective view schematically showing the overall configuration, and FIGS. 5 and 6 show conventional examples. These are views corresponding to FIG. 1 and FIG. 2, respectively. In the drawing, 1 is a pipe (workpiece), 1a is a gap, and 2
3 is a welding torch, 3 is a camera (image pickup device), 5.6 is a slit light source, 8 and 9 are reflected lights, 10 is a control device (binarization means, gap detection means), 11 is a position correction device (position correction means) ), 21 is a welding device, 22 is an image processing hardware circuit,
Reference numeral 25 indicates a binarization circuit, and reference numerals 27 and 28 indicate a threshold setting circuit (level setting means). Applicant: Toshiba Corporation

Claims (1)

[Claims] 1. In a welding torch that moves the welding torch relatively along the gap between the parts to be welded to continuously weld the parts to be welded, the welding torch is located on the front side in the direction of relative movement of the welding torch. an imager for simultaneously photographing a portion to be welded at a plurality of detection points; a level setting means for setting a binarization reference level for each detection point photographed by the imager; and an image of each of the detection points. Binarization means that binarizes the signal by comparing it with the binarization reference level, and gap detection means that detects the center position of the gap at each of the detection points based on the binarized data by the binarization means. and position correction means for relatively moving the welding torch on a straight line connecting the center positions of the gaps at the respective detection points detected by the gap detection means.