JPH0724946B2 - Welding line detector in laser welding - Google Patents

Description

Description: [Object of the Invention] (Field of Industrial Application) The present invention relates to a welding line detection device in laser welding for welding a butt portion of an object to be welded by a laser beam from a welding head.

(Prior Art) For example, when manufacturing a metal tube, a metal plate is bent in a cylindrical shape, and a welding line, which is a butt portion of an object to be welded, is welded by a laser beam from a welding head. Has been done. In this case, when the object to be welded is bent, a twist occurs, and the welding line deviates from the welding reference line by the welding head, which makes welding impossible.

Therefore, conventionally, a welding detection device in laser welding as shown in FIG. 5 (see Japanese Patent Laid-Open No. 1-181900) has been considered. That is, 1 is an object to be welded having a butt portion (welding line) 1a, and 2 is a welding head for welding the butt portion 1a with a laser beam 3. Reference numerals 4 and 5 are first and second light irradiation means, and 6 is a CCD camera which is an ITV camera, and a welding line detection device 7 is constituted by these.

Thus, the welding head 2 welds the abutting portion 1a of the object to be welded 1 which is moved in the direction of the arrow 8 with the laser light 3, but the first and second light irradiation means 4 and 5 are lasers. Slit lights 9 and 10 are respectively radiated to two detection positions B and C located on the front side of the welding point A by the light 3 and having a predetermined distance in the welding direction, and reflected light from the detection positions B and C.
The CCD camera 6 receives 9a and 10a, and the reflected light 9a and 10a received by the CCD camera 6 is image-processed to calculate the deviation of the welding point A from the welding reference line, and the welding head 2 is calculated based on the calculation result. The welding point A by the laser beam 3 is controlled so as to coincide with the butt portion 1a by adjusting the movement in a direction orthogonal to the butt portion 1a.

(Problems to be Solved by the Invention) In the conventional configuration, the first and second light irradiating means 4 and 5 are arranged so as to irradiate the detection positions B and C with the slit lights 9 and 10 obliquely from the upper right side. And against this, CC
The D camera 6 reflects the reflected light 9a and 1 from the detection positions B and C.
Since 0a is arranged so as to receive light obliquely from above on the left side, there is a problem that the welding line detection device 7 becomes large along the direction of the abutting portion 1a. Further, since the distances from the CCD camera 6 to the detection positions B and C are different, it is difficult to adjust the focus of the CCD camera 6, and the light amounts of the reflected lights 9a and 10a are also different. Therefore, the accurate welding line is obtained. It becomes impossible to detect.

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

[Means for Solving the Problems] (Means for Solving the Problems) A welding line detection device in laser welding according to the present invention is for welding a butt portion of an object to be welded by a laser beam from a welding head. First and second light irradiating means for irradiating slit light from diagonally above so as to be orthogonal to the welding line are provided at two detection positions which are on the front side of the point and have a predetermined interval in the welding direction. Is disposed between the first and second light irradiation means of
An ITV camera for receiving the reflected light from the detection position of the location is provided, and the positional relationship between the first and second light irradiation means and the ITV camera is determined by the slit light from the first and second light irradiation means. It is characterized in that the incident angle and the opposite angle with respect to the detection position are set to be equal to each other.

(Operation) According to the welding line detection device in laser welding of the present invention,
The first and second light irradiation means and the ITV camera are arranged such that the incident angle and the reflection angle of the slit light from the first and second light irradiation means with respect to each detection position are equal to each other. Since the distances from the ITV camera to the two detection positions are equal, the focus adjustment of the ITV camera is easy, and the amount of light reflected from each detection position on the ITV camera is also equal. It becomes possible to detect accurately, and the ITV camera is located in the middle of the two detection positions and the first
Since the second light irradiating means is located so as to sandwich the ITV camera, it is possible to reduce the size as a whole.

(Embodiment) An embodiment 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. twenty one
Is an object to be welded for manufacturing a metal pipe, which is formed by bending a metal plate material in a tubular shape to form a butt portion 22 as a welding line.
Have. Reference numeral 23 is a welding head, which is adapted to irradiate a laser beam 25 to the welding point A of the abutting portion 22 of the object to be welded 21 which is moved in the direction of arrow 24 to perform welding. Then, the welding head 23 is driven by the drive device 26 and the butt portion 22 is moved.
The movement is adjusted in the direction of arrow 27, which is a direction orthogonal to the direction, and in the opposite direction. Reference numeral 28 denotes a first light irradiation means, which is composed of a semiconductor laser light emitting element 29, a collimator lens 30, a cylindrical lens 31, etc. The slit light 32 is radiated from the obliquely upper right side toward the first detection position B spaced apart from the above. 33 is a second light irradiating means, which is composed of a semiconductor laser light emitting element 34, a collimator lens 35, a cylindrical lens 36, etc.
The slit light 37 is emitted obliquely from the upper left side toward the second detection position C, which is spaced from the first detection position B of 22 by a predetermined distance to the front side. Reference numeral 38 denotes a CCD camera which is an ITV camera, which is located in the middle of the first and second light irradiation means 28 and 33, and constitutes a welding line detection device 39 together with these. And CC
The D camera 38 reflects the reflected lights 32a and 37a from the detection positions B and C.
Is received via a filter 40 for removing ambient light. 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. 41
Is an image processing circuit, which receives a signal from the CCD camera 38 and performs image processing as described later, and supplies the image processing signal to the control circuit 42. The control circuit 42 also operates as will be described later, thereby giving a drive signal to the drive circuit 43 so that the semiconductor laser light emitting elements 29 and 34 of the light irradiation means 28 and 33 are provided.
Is operated to emit light, and a drive signal is supplied to the drive device 26 to move the welding head 23.

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

During welding of the butt portion 22 of the workpiece 21 by the laser light 25 from the welding head 23, the semiconductor laser light emitting elements 29 and 34 of the light irradiation means 28 and 33 are driven by the drive circuit 43, and the respective cylindrical lenses 31. And 36 to welding head 23
The slit lights 32 and 37 are emitted toward the detection positions B and C on the front side of the welding point A by the obliquely upper right side and the obliquely upper left side, respectively. In this case, the incident angles of the slit lights 32 and 37 with respect to the detection positions B and C are equal to each other as shown in FIG. These slit lights 32 and 37 are irradiated so as to be orthogonal to the butt portion (welding line) 22 at the respective detection positions B and C, and the irradiation cross sections of the slit lights 32 and 37 in the respective detection devices B and C are: As shown in FIGS. 3 and 4, reference numerals 32b and 37b are provided. CCD
The camera 38 receives the reflected lights 32a and 37a via the filter 40. In this case, the reflected angles of the reflected lights 32a and 37a from the detection positions B and C are as shown in FIG. It is equal to the incident angle and θ. And CCD camera 38
The light receiving area of is in a rectangular shape as indicated by the symbol D, as shown in FIGS. Therefore, the CCD camera 38
Image processing of the light receiving area D is performed, and the image processing signal is given to the control circuit 42. The control circuit 42, based on this image processing signal, the butt section of the irradiation cross sections 32b and 37b.
The center lines 32d and 37d of the slits 32c and 37c by 22 are calculated, and the deviation from the reference welding line of the butt portion 22 is calculated from these center lines 32d and 37d, and a correction signal that is a drive signal based on the calculation result is calculated. The drive device 26 is supplied. As a result, the drive unit 26 moves the welding head 23 in the direction of the arrow 27 or in the opposite direction by the amount of deviation from the welding reference line, and irradiates the laser beam 25 from the welding head 23 on the actual butt section 22. Correct so that

As described above, according to the present embodiment, the CCD camera 38 is mounted on the workpiece 2
It is installed above the intermediate position between the detection positions B and C of 1 and the first and second light irradiation means 28 and 33 are provided in the CCD.
Since the camera 38 is positioned so as to be sandwiched, it is possible to reduce the size of the welding line detection device 39 as a whole as compared with the conventional one. Further, since the incident angles and the reflection angles of the slit lights 32 and 37 from the first and second light irradiating means 28 and 33 to the respective detection positions B and C are set to be the same θ, the CCD camera 38 From the two detecting devices B and C are equal to each other, the focus adjustment of the CCD camera 38 is facilitated, and the reflected light 32a to the CCD camera 38 is reflected.
The light amounts of 37a and 37a are also equal to each other, so that the deviation of the abutting portion 22, which is a welding line, can be reliably detected, and the welding reliability can be improved.

[Advantages of the Invention] As described above, the welding line detection device in laser welding according to the present invention has the first and second light irradiation means arranged with the ITV camera in between and the first and second light irradiation means. Since the positional relationship between the means and the ITV camera is set such that the incident angle and the opposite angle of the slit light of the first and second light irradiating means with respect to each detection position are respectively equal, it is possible to reduce the size as a whole, and This has an excellent effect that the welding line can be reliably detected.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is an overall schematic configuration explanatory view, and FIG. 2 shows a positional relationship between the first and second light irradiation means and a CCD camera. Fig. 3 is a side view, Fig. 3 is an enlarged plan view of the detection position of the CCD camera, and Fig. 4 is a CCD.
FIG. 3 is an enlarged plan view showing a light receiving area of a camera, and
FIG. 5 is a view corresponding to FIG. 2 of the conventional example. In the drawings, 21 is a workpiece, 22 is a butt portion (welding line), 23 is a welding head, 25 is a laser beam, 28 is a first light irradiating means, 32
Is slit light, 32a is reflected light, 33 is second light irradiating means, 3
7 is slit light, 37a is reflected light, 38 is a CCD camera (ITV camera), and 39 is a welding line detection device.

Claims (1)

[Claims] 1. In a method for welding a butt portion of an object to be welded by a laser beam from a welding head, at two detection positions located in front of a welding point by the welding head and having a predetermined interval in the welding direction. First and second light irradiation means for respectively irradiating the slit light obliquely from above and so as to be orthogonal to the welding line, and the above-mentioned two detection positions arranged in the middle of these first and second light irradiation means. Receives reflected light from
An ITV camera is provided, and the positional relationship between the first and second light irradiating means and the ITV camera is defined as an incident angle and an opposite angle of the slit light from the first and second light irradiating means with respect to each detection position. The welding line detection device in laser welding is characterized in that the values are set to be equal to each other.