JPH0343951B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser welding device for welding steel using a laser beam, and particularly relates to a gap in a butting portion between a leading plate and a trailing plate to be welded. This invention relates to a laser welding device that performs welding after detecting the width.

[Conventional technology]

FIG. 10 is a plan view of a conventional laser welding device. In the figure, 4 is a moving block equipped with a duct for transmitting laser light from a laser oscillator (not shown), 5 is a feed screw for moving the moving block 4, 6 is a bearing for the feed screw 5, and a pair of supports 7,
They are provided at both ends of the crossbeam 8 which is installed on the bridge 7. 10 is a servo motor for moving the machining head Y-axis to rotate the feed screw 5; 11 is a drive gear fixed to the motor shaft of the servo motor 10; 12 is a gear fixed to one end of the feed screw 5; It is meshed with 11. 13 is a processing head attached to the side of the moving block 4; 14 is a bed; 15a is a leading plate that is a steel plate placed on the bed 14; 15b is a trailing plate that is a steel plate placed on the bed 14; 16 is a leading plate 15a and a trailing plate 15b
This is the welding line.

A conventional laser welding apparatus is constructed as described above, and for example, the ends of the leading plate 15a and the trailing plate 15b to be welded in the longitudinal direction, that is, in the direction of the arrow X in FIG. 10, are butted against each other on the bed 14.

Next, welding is performed by irradiating the abutting portion between the leading plate 15a and the trailing plate 15b, that is, the welding line 16, with a laser beam emitted from the processing bed 13. At this time,
The servo motor 10 is rotated, and its rotational force is transmitted to the feed screw 5 via the drive gear 11 and gear 12, and the rotation of the feed screw 5 moves the moving block 4 in the direction of arrow Y in FIG. 4
Welding is performed by moving the processing head 13 attached to the welding point 16 along the welding point 16.

[Problem that the invention seeks to solve]

In the conventional laser welding apparatus as described above, the leading plate 15a and the trailing plate 15b are butted together on the bed 14 by positioning using a clamper, so that the amount of gap at the butt portion between the leading plate 15a and the trailing plate 15b is small. In other words, the gap width is determined by the positioning operation of the clamper, and although the gap width is several tens of μm, it is not possible to determine whether it is the appropriate gap width, and there is a problem that reliable and highly accurate welding cannot always be achieved. It was hot.

This invention was made to solve this problem, and it measures the gap width at the abutting portion of the leading plate and the trailing plate without contact before welding, and determines whether the gap width is appropriate for laser welding. It is an object of the present invention to provide a laser welding device that can perform laser welding with certainty and high precision by performing laser welding after making a judgment.

[Means for solving problems]

The laser welding device according to the present invention includes an optical detection means for taking an image of the abutting part of two welding plates to be welded by a laser beam, and a right image of the abutting part taken by the optical detecting means to determine the left side and right side of the gap. A calculation means for calculating the width value, a comparison circuit for comparing and determining the values of the left and right side gap widths calculated by the calculation means with preset reference values for the left and right side gap widths, and a comparison circuit. The welding machine control circuit starts or stops welding according to the determined and output signal, and when the welding is stopped, drives the servo motors for moving the left and right sides of the steel plate.

[Effect]

In this invention, the gap widths of two welded plates are detected as a normal image by an optical detection means, and the left and right side gap widths of the gap are respectively calculated from the normal image by a calculation means, and the calculated left and right side gap widths are The comparison circuit compares the values with the reference values for the left and right side gear widths, and the welding machine control circuit starts or stops welding according to the output signal of the comparison circuit. Finely adjust the gap width by driving the servo motor for moving the right side of the steel plate.

〔Example〕

FIG. 1 is a front view of a laser welding device showing an embodiment of the present invention, and FIG. 2 is a plan view of the same laser welding device. In the figures, the same components as those of the conventional example are given the same reference numerals and redundant explanations will be omitted.

1 is a laser oscillator that emits a laser beam, 2a is a telescopic beam transmission duct that transmits the laser beam, 2b is a normal beam transmission duct, and 3 is a transmission that supports the beam transmission ducts 2a and 2b and changes the optical path. A duct support member, 17 is a laser beam emitted from the processing head 13, and 18 is an industrial video camera installed in parallel on the side of the processing head 13 to take a picture of the abutting portion between the leading plate 15a and the trailing plate 15b. do.

20 is a servo motor for moving the processing head on the X axis;
Reference numeral 1 denotes a drive gear pivotally attached to the motor shaft of a servo motor 20, and 22 a feed screw for moving the machining head 13, which is rotatably supported by a bearing 23.
24 is a gear fixed to one end of the feed screw 22;
It is meshed with the drive gear 21. 25a is a leading plate clamper that grips the leading plate 15a, 25b is a trailing plate clamper that grips the trailing plate 15b, 26a is the left side of the steel plate that is the left side of the trailing plate 15b, and 26b is the right side of the trailing plate 15b. This is the right side of the steel plate.
27 is a servo motor for moving the left side of the steel plate, 28 is a drive gear pivotally attached to the motor shaft of the servo motor 27, and 29 is a feed screw for moving the left end side of the trailing plate clamper 25b, which is rotatably supported on a bearing 30. has been done. A gear 31 is fixed to one end of the feed screw 29 and is meshed with the drive gear 28. 32
3 is a servo motor for moving the right side of the steel plate; 33 is a drive gear mounted on the motor shaft of the servo motor 32;
4 is a feed screw for moving the right end side of the trailing plate clamper 25b, and is rotatably supported by a bearing 35. A gear 36 is fixed to one end of the feed screw 34 and is meshed with the drive gear 33. It is assumed that the servo motors 20, 27, 32 and the bearings 23, 30, 35 are all fixed to appropriate members fixed to the installation base of the laser welding device. In addition, in the figure, illustration of those fixing members is omitted.

FIG. 3 is a schematic block diagram for detecting gap abnormalities in members to be welded by a laser welding device, and FIG. 4 is a more detailed block diagram than FIG. 3.

In the figure, 15a and 15b are the leading and trailing plates to be welded, G is the gap at the butt portion of the leading plate 15a and trailing plate 15b, 10 is the servo motor for moving the machining head Y-axis, and 20 is the machining head X. A servo motor for moving the shaft, 27 a servo motor for moving the left side of the steel plate, and 32 a servo motor for moving the right side of the steel plate. 19 is a magnifying optical system that magnifies the image of the gap G; 41 is a system that magnifies the image of the industrial video camera 18;
A binarization circuit converts the value into a digitized image; 42 is an arithmetic circuit that calculates the width of the gap G from the output signal of the binarization circuit 42; 43 is a display of the calculation result of the arithmetic circuit 42;
A CRT, 44 is a comparison circuit that compares the gap width calculated by the calculation circuit 41 with a preset reference value of the gap width, 45 is a calculation means consisting of a binarization circuit 41 and a calculation circuit 42, and 46 is This is a welding control circuit that controls the processing head 13 to perform laser processing. 47 is a microcomputer including a binarization circuit 41, an arithmetic circuit 42, and a comparison circuit 44. Next, the leading board 15a below the bet 14
The operation when detecting an abnormality in the gap width of the gap G at the abutting portion of the trailing plate 15b is shown in block diagrams in FIGS. 3 and 4, and schematic diagrams of gap detection in FIGS. 5 to 7. This will be explained with reference to the flowchart shown in FIG.

First, in step 100, the leading plate 15a and the trailing plate 15b to be welded on the bed 14 are butted against each other to start. Next, in step 101, the butting of the leading plate 15a and the trailing plate 15b is completed. Then, in step 102, the processing head Y-axis moving servo motor 10 rotates to rotate the feed screw 5, and accordingly, the moving block 4 moves in the Y direction, and the video camera 20 attached to the moving block 4 moves to the leading plate 15a. and the welding line 16 of the trailing plate 15b
Gap G at the butt part
scanning is performed. In step 103, the magnifying optical system 21 attached to the video camera 20
The image of Gap G is enlarged, and the video camera 20
An enlarged normal image of the gap G is captured. In step 104, the enlarged normal image of the gap G is converted into a binary image by the binarization circuit 41. In step 105, the binarized image shows that the gap G is black, and the others are white. In step 106, the arithmetic circuit 42 calculates the values of the left and right portions of the gap G in the black image portion corresponding to the gap G of the binarized image. Step 107
Then, the calculation result of the gap G by the calculation circuit 42 is
Display on CRT43. Comparison circuit 4 in step 108
4 compares the value of the gap width calculated by the calculation circuit 42 with the reference values Rf ₁ and Rf ₂ of the gap width of the left and right portions of the gap G set in advance, and determines in step 109 whether it is within the reference value. to decide.
When the gap width values of the left and right portions of the gap G calculated by the calculation circuit 42 are within the reference values Rf ₁ and Rf ₂ , the comparison circuit 44 outputs a welding start signal as shown in step 110. In step 111, the welding machine control circuit 46, which has received the welding start signal, drives the servo motor 10 for moving the processing head in the Y axis and causes the processing head 13 to perform welding. That is, the servo motor 10 is driven to return the machining head 13 to its original position, and then the servo motor 10 is driven again to rotate the feed screw 5 and the laser oscillator 1 is activated while moving the machining head 13 in the Y-axis direction. When turned on, the laser beam emitted from the laser oscillator 1 passes through the beam transmission duct 2a, the moving block 3, and the beam transmission duct 2b, and is irradiated from the processing head 13 onto the welding line 16 of the leading plate 15a and trailing plate 15b for welding. Welding is completed in step 112.

On the other hand, as shown in FIG. 5, it is determined in step 113 that the gap width values G ₁ and G ₂ of the left and right portions of the gap G calculated by the calculation circuit 42 are not within the reference values Rf ₁ and Rf ₂ , respectively. In this case, the comparator circuit 44 outputs a welding stop signal as well as signals for moving the left and right sides of the steel plate, as shown in step 115. In step 116, the welding machine control circuit 46 receives the welding stop signal and the steel plate left side and right side movement signals and stops welding by the processing head 13, and also turns on the servo motor 27 for moving the left side of the steel plate and the servo motor for moving the right side of the steel plate. 32 is driven to finely adjust the gap G and match the leading plate 15a and trailing plate 15b again (step
117). The operation thereafter returns to step 102.

Further, as shown in FIG. 6, the value of the left and right gap width in the gap G calculated by the calculation circuit 42 is
When G ₁ and G ₂ meet the condition of G ₁ < G ₂ , G ₁ is the reference value Rf ₁
When it is determined in step 114 that G ₂ is not within the reference value Rf ₂ , the comparison circuit 44 outputs a welding stop signal and a steel plate left side movement signal as shown in step 118. In step 119, the welding machine control circuit 46, which has received the welding stop signal and the left side movement signal of the steel plate, stops welding by the processing head 13 and drives the servo motor 27 for moving the left side of the steel plate to move the left side of the trailing plate 15b. is moved toward the leading plate 15a to finely adjust the gap G, and the leading plate 15a and trailing plate 15b are brought into butt again (step 120). The operation thereafter returns to step 102.

Further, as shown in FIG. 7, the values of the left and right gap widths in the gap G calculated by the calculation circuit 42 are
When G ₁ and G ₂ meet the condition of G ₁ > G ₂ , G ₂ is the reference value
If it is determined in step 121 that G _{1 is} not within the reference value Rf ₁ , the comparison circuit 44
outputs a welding stop signal and a steel plate right side movement signal as shown in step 121. In step 122, the welding control circuit 46, which has received the welding stop signal and the steel plate right side movement signal, stops welding by the processing head 13 and drives the steel plate right side movement servo motor 27 to move the right side of the trailing plate 15b. The gap G is finely adjusted by moving it toward the leading plate 15a, and the leading plate 15a and trailing plate 15b are brought into butt again (step 120). The operation thereafter returns to step 102.

By the above-described operation, butt welding of steel plates with a laser beam can be performed accurately and reliably.

In addition, the servo motor 10 for moving the processing head on the X axis
is for making fine adjustments in the X-axis direction so that the machining head 13 will not be misaligned when the weld line 16 is misaligned due to the gap fine adjustment operation. 9th
The figure is a front view showing a second embodiment of the invention.

In the drawings, the same components as in the first embodiment are given the same reference numerals as in the conventional example, and redundant explanation will be omitted. In this embodiment, two industrial video cameras 18,1
8 are used, and each is configured to be moved by the rotation of small feed screws 5a and 5b, which are separate from the feed screw 5. One video camera 20 images half of the abutting portion between the leading plate 15a and the trailing plate 15b, and the other video camera 20 images the remaining half of the abutting portion to detect a gap in the entire abutting portion. It is. Further, each small feed screw 5a, 5b is driven by a dedicated servo motor 38, respectively. Since the gap width of the gap G imaged by each video camera 18 is controlled by the same operation as in the first embodiment, a description of the operation will be omitted.

In this embodiment, two video cameras 18, 18
Since the gap at the butt part is detected in half at a time, the scanning time is shortened.

In the embodiment described above, fine adjustment of the gap G is performed using the servo motor 27 for moving the left side of the steel plate and the servo motor 32 for moving the right side of the steel plate, but instead of these servo motors 27 and 32, other methods such as a hydraulic mechanism may be used. Of course, it can also be implemented in a different manner. Further, in the above-described embodiment, the trailing plate 15b was moved by the drive of the servo motor 27 for moving the left side of the steel plate and the servo motor 38 for moving the right side of the steel plate to finely adjust the gap G. These servo motors 27 and 38 move the leading plate 1
Of course, the gap G may be finely adjusted by moving the leading plate 15a or the leading plate 15a and the trailing plate 15b.

〔Effect of the invention〕

As described above, according to the present invention, the gap width of the welded plate is detected as a normal image, the left side and right side gap widths of the gap are respectively calculated from the normal image by the calculating means, and the calculated values of the left side and right side gap widths are calculated. The comparing circuit compares the gap width with the reference values of the left and right side gap widths to determine whether the welding is started or stopped by the welding machine control circuit according to the output signal of the comparing circuit, and when stopping, the left side of the steel plate is By driving the servo motor for moving the right side of the steel plate, the gap width can be set so that the steel plate butt welding can be performed accurately and reliably using a laser beam, resulting in reliable and highly accurate welding results. This has the effect that it can be obtained.

[Brief explanation of drawings]

Fig. 1 is a front view of a laser welding device showing a first embodiment of the present invention, Fig. 2 is a plan view of the same laser welding device, and Fig. 3 is a detection of gap abnormalities in members to be welded by the laser welding device. Figure 4 is a more detailed block diagram than Figure 3.
5 to 7 are schematic diagrams of gap detection, FIG. 8 is a flowchart showing the operation, FIG. 9 is a front view of a laser welding device showing a second embodiment of the present invention, and FIG. 10 is a conventional FIG. 2 is a plan view of a laser welding device. In the figure, 15a is a leading plate (steel plate), 15b
is a trailing plate (steel plate), 18 is a video camera (optical detection means), 27 is a servo motor for moving the left side of the steel plate,
32 is a servo motor for moving the right side of the steel plate, 41 is 2
Value converting circuit, 42 is an arithmetic circuit, 44 is a comparison circuit, 4
5 is a calculation means, and 46 is a welding machine control circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. Optical detection means that images the abutting part of two steel plates to be welded by a laser beam, and values of the left and right side gap widths of the gap from the correct image of the abutting part taken by the optical detection means. and compares the values of the left and right side gap widths calculated by the calculation means with preset reference values for the left and right side gap widths, and calculates the values of the left and right side gap widths respectively. When the gap width is less than the reference value, a welding start signal is output, and when the left and right side gap widths are greater than the respective left and right side gap width reference values, a welding stop signal is output and the steel plate moves to the left and right sides. A signal is output, and when the value of the left gear width is less than the reference value of the left gear width and the value of the right gear width is greater than the reference value of the right gear width, a welding stop signal is output and a steel plate right side movement signal is output. , a comparison circuit that outputs a welding stop signal and a left side movement signal of the steel plate when the value of the left side gap width is greater than or equal to the reference value of the left side gap width and the value of the right side gap width is less than or equal to the reference value of the right side gap width; Welding is started by the welding start signal of the comparison circuit, welding is stopped by the welding stop signal, the servo motor for moving the left side of the steel plate is driven by the left side moving signal of the steel plate, and the servo motor for moving the right side of the steel plate is driven by the moving signal for the right side of the steel plate. A laser welding machine comprising a welding machine control circuit that drives a motor. 2 The calculation means includes a binarization circuit that converts the normal image of the butt portion of the two steel plates into a binarized image of the gap and other parts, and an arithmetic circuit that computes the value of the gap width output from the binarization circuit. A laser welding apparatus according to claim 1, characterized in that the laser welding apparatus comprises: