JPH0455078A - Weld line detector for laser beam welding - Google Patents

Abstract

PURPOSE:To surely detect a weld line by setting the position relations of 1st, 2nd photoirradiating means and ITV camera to equal the incident and reflection angle on and from the respective detection positions of the slit light beams from these two photoirradiating means. CONSTITUTION:The two detection positions B, C which exist in the front side of a welding point A by a welding head 23 and has a prescribed spacing in a welding direction are respectively irradiated with the slit beams 32, 37 from diagonal above by the 1st, 2nd photoirradiating means 28, 33 so as to intersect orthogonally with the weld line 22. The ITV camera 38 is disposed between the 1st and 2nd photoirradiating means 28 and 33 to receive the reflected beams 32a, 37a from the detection positions B, C. The position relations of the 1st, 2nd photoirradiating means 28, 33 and the ITV camera 38 are so set that the incident angles and reflection angles of the slit beams 32, 37 from the 1st, 2nd photoirradiating means 28, 33 on and from the respective detection positions are respectively equaled. The size over the entire part of the device is reduced in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a weld line detection device for laser welding, which welds butt portions of objects to be welded using laser light from a welding head.

(Prior art) For example, in manufacturing metal pipes, welding lines, which are the abutting parts of the workpieces made by bending metal plates into a cylindrical shape, are welded using a laser beam from a welding head. It is provided. In this case, when the object to be welded is bent, it is twisted and the welding line is deviated from the welding reference line by the welding head, making welding impossible.

For this reason, conventionally, as shown in FIG.
A weld line detection device for laser welding has been considered as shown in Japanese Patent Publication No. That is, 1 is an object to be welded having a butt portion (welding line) la, and 2 is a welding head for welding this butt portion 1a with a laser beam 3. 4 and 5 are first and second light irradiation means; 6 is a CCD serving as an ITV camera;
These cameras constitute a welding line detection device 7.

The welding head 2 welds the butt portion 1a of the workpiece 1 moved in the direction of the arrow 8 with the laser beam 3, and the first and second light irradiation means 4 and 5 Slit lights 9 and 10 are respectively irradiated to two detection positions B and C located in front of the welding point A and located at a predetermined interval in the welding direction of the welding point A by the light 3, and the reflected light 9a from the detection positions B and C is and 10a are received by the CCD camera 6, and the CCD
The reflected lights 9a and 10a received by the camera 6 are image-processed to calculate the deviation of the welding point A from the welding reference line, and based on the calculation result, the welding head 2 is adjusted to move in a direction perpendicular to the abutting portion 1a. Control is performed so that the welding point A by the laser beam 3 coincides with the butt portion 1a.

(Problem to be Solved by the Invention) In the conventional configuration, the first and second light irradiation means 4 and 5 are arranged so as to irradiate the slit lights 9 and 10 to the detection positions B and C from diagonally above on the right side. and, in contrast,
The CCD camera 6 detects reflected light 9 from its detection positions B and C.
a and 10a are arranged so as to receive light from diagonally above the left side, so that the welding line detection device 7 can detect the abutment part 1a.
There is a problem that the size increases along the direction. Also, since the distances from the CCD camera 6 to detection positions B and C are different, C
It is difficult to adjust the focus of the CD camera 6, and the amounts of reflected light 9a and 10a are also different.
Accurate detection of the weld line becomes impossible.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a weld line detection device for laser welding that can be miniaturized as a whole and can accurately detect a weld line.

[Structure of the Invention] (Means for Solving the Problems) A welding line detection device for laser welding of the present invention is for welding a butt part of a welded object using a laser beam from a welding head, and the welding line detection device for laser welding of the present invention First and second light irradiation means for irradiating slit light from diagonally above and perpendicular to the welding line are provided at two detection positions that are located in front of the point and are spaced apart from each other by a predetermined distance in the welding direction. The second light irradiation means is arranged between the first and second light irradiation means.
An ITV camera that receives reflected light from the detection position of the spot is provided, and these first and second light irradiation means and the ITV
The present invention is characterized by a configuration in which the positional relationship of the cameras is set so that the angle of incidence and angle of reflection of the slit light from the first and second light irradiation means with respect to each detection position are equal.

(Function) According to the weld line detection device for laser welding of the present invention,
The first and second light irradiation means and the ITV camera are
Since the positional relationship is set so that the angle of incidence and angle of reflection of the slit light from the second light irradiation means to each detection position are equal, the distances from the ITV camera to the two detection positions are equal. This makes it easier to adjust the focus of the ITV camera, and the amount of light reflected from each detection position to the ITV camera becomes equal.
It is now possible to accurately detect weld lines, and
The ITV camera is located between the two detection positions, and the first and second light irradiation means are located sandwiching the ITV camera, so the overall size can be reduced. .

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 4.

First, the overall configuration will be described with reference to FIG. 2
Reference numeral 1 denotes a welded object for manufacturing a metal tube, which is formed by bending a metal plate material into a cylindrical shape and has an abutment part 22 which is a weld line. 23 is a welding head, which is indicated by arrow 2
Welding is performed by irradiating the welding point A of the abutting portion 22 of the workpiece 21 moved in four directions with a laser beam 25.

This welding head 23 is adjusted to move in the direction of arrow 27, which is a direction perpendicular to the abutment portion 22, and in the opposite direction, by a drive device F26. 28
is a first light irradiation means, which is a semiconductor laser light emitting device 29. The slit light 3 is composed of a collimator lens 30, a cylindrical lens 31, etc., and is directed from the diagonally upper right side toward the first detection position B, which is spaced a certain distance forward from the welding point A of the butt portion 22 on the workpiece 21.
It is designed to irradiate 2. 33 is a second light irradiation means, which is a semiconductor laser light emitting device 34. It is composed of a collimator lens 35, a cylindrical lens 36, etc., and is located diagonally from above on the left side toward a second detection position C, which is spaced forward by a predetermined distance from the first detection position B of the butt portion 22 on the workpiece 21. A slit light 37 is irradiated. 38 is ITV camera CC
The D camera is located between the first and second light irradiation means 28 and 33, and together with them constitutes a weld line detection device 39. and,
The CCD camera 38 detects reflected light 32 from detection positions B and C.
a and 37a are received through a filter 40 for removing disturbance light. Note that the welding line detection device 39 is housed in one case and is integrally fixed to the welding head 23.

Now, the electrical configuration will be described with reference to FIG. 1. 4
1 is an image processing circuit, which is connected to the CCD camera 3;
In response to a signal from 8, image processing is performed as described later, and the image processing signal is supplied to control circuit 42. The control circuit 42 operates as will be described later, thereby giving a drive signal to the drive circuit 43 to cause the semiconductor laser light emitting elements 29 and 34 of the light irradiation means 28 and 33 to emit light, and also to the drive device 26. The welding head 23 is moved by applying a drive signal.

Next, the operation of this embodiment will be explained with reference to FIGS. 2 to 4.

Workpiece 21 to be welded by laser beam 25 from welding head 23
During welding of the abutting portion 22, the drive circuit 43 activates the semiconductor laser light emitting device 29 of the light irradiation means 28 and 33.
and 34 are driven, and slit lights 32 and 37 are irradiated from the cylindrical lenses 31 and 36 toward detection positions B and C on the front side of the welding point A by the welding head 23 from diagonally above the right side and diagonally above the left side, respectively. Ru. In this case, the incident angles of the slit beams 32 and 37 with respect to the detection positions B and C are equal to θ, as shown in FIG. These slit lights 32 and 37 are irradiated perpendicularly to the butt portion (welding line) 22 at each detection position B and C, and the irradiation cross section of the slit lights 32 and 37 at each detection device B and C is as follows. As shown in FIGS. 3 and 4, they are designated by 32b and 37b. CCD
The camera 38 filters the reflected lights 32a and 37a through a filter 40.
In this case, the reflected light 32
As shown in FIG. 2, the reflection angle of detection positions B and C of a and 37a is θ, which is equal to the incident angle. The light receiving area of the CCD camera 38 is rectangular as shown in FIGS. 3 and 4. Therefore, the CCD camera 38 processes the image of the light receiving area D and provides the image processing signal to the control circuit 42. The control circuit 42 calculates center lines 32d and 37d of the slits 32c and 37c formed by the abutting portions 22 of the irradiated cross sections 32b and 37b based on this image processing signal,
The deviation of the butt portion 22 from the reference welding line is calculated from these center lines 32d and 37d, and a correction signal serving as a drive signal based on the calculation result is provided to the drive device 26. Thereby, the drive device 26 moves the welding head 23 in the direction of the arrow 27 or the opposite direction by the amount of deviation from the welding reference line, and irradiates the actual abutting portion 22 with the laser beam 25 from the welding head 23. Correct it so that

As described above, according to this embodiment, the CCD camera 38 is installed above the intermediate position between the detection positions 1jB and 1jC of the workpiece 21, and the first and second light irradiation means 28 and 3
3 is positioned with the CCD camera 38 between them, so that the overall size of the welding line detection device 39 can be reduced compared to the conventional one. Furthermore, since the incident angles and reflection angles of the slit lights 32 and 37 from the first and second light irradiation means 28 and 33 with respect to each detection position B and C are set to be equal to θ, the CCD camera 38
Since the distances from the detection devices B and C to the two detection devices B and C become equal, focus adjustment of the CCD camera 38 becomes easier, and the respective reflected lights 32a and 37 to the CCD camera 38 are made equal.
The light intensity of a is also equal, so the butt part 2 which is the welding line
2 can be reliably detected, and welding reliability can be improved.

[Effects of the Invention] As explained above, the welding line detection device for laser welding of the present invention has the first and second light irradiation means placed between the ITa camera, and the first and second light irradiation means Since the positional relationship between the means and the ITV camera is set so that the angle of incidence and angle of reflection of the slit light of the first and second light irradiation means with respect to each detection position are equal, the overall size can be reduced, and This has the excellent effect of being able to reliably detect the weld line.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, FIG. 1 is a schematic explanatory diagram of the overall configuration, and FIG. 2 is a diagram showing the arrangement relationship between the first and second light irradiation means and the CCD camera. Side view shown, third
The figure is an enlarged plan view of the detection position portion of the CCD camera, and FIG. 4 is an enlarged plan view showing the light receiving area of the CCD camera.
FIG. 5 is a diagram corresponding to FIG. 2 of the conventional example. In the drawing, 21 is the object to be welded, 22 is the butt part (welding line),
23 is a welding head, 25 is a laser beam, 28 is a first light irradiation means, 32 is a slit light, 32a is a reflected light, 33 is a second light irradiation means, 37 is a slit light, 37a is a reflected light,
38 is a CCD camera (ITV camera), and 39 is a welding line detection device. Applicant Toshiba Corporation Nippon Steel Corporation

Claims (1)

[Claims] 1. In a device that welds the abutting parts of objects to be welded using a laser beam from a welding head, two detection positions located in front of the welding point by the welding head and having a predetermined interval in the welding direction are detected diagonally upward, respectively. first and second light irradiation means that irradiate slit light from the welding line orthogonally to the welding line;
an ITV camera disposed between the first and second light irradiation means to receive reflected light from the two detection positions; Welding line detection device for laser welding, characterized in that the positional relationship of the camera is set so that the angle of incidence and angle of reflection of the slit light from the first and second light irradiation means with respect to each detection position are equal, respectively. .