JPH079373A - Welding robot and its tracking sensor - Google Patents

Abstract

PURPOSE:To continuously weld one work plate having rise add fall sections to the other work plate in mutually overlapping relation by obliquely projecting laser light to the end face of the work plate disposed along the direction that welding is advanced by means of a simple constitution with ease. CONSTITUTION:Rise and fall sections 2a are detected by a tracking sensor 18 based on both a change in an end face 2c in the Y axis direction of a work plate 2 which comprises the rise and fall sections formed roughly regular intervals in the X axis direction that welding is processed, and a change of the position of the work surface in the Z axis direction of the work plate 2, and laser light is projected to the end face 2c out of a working laser nozzle 17. The aforesaid laser light includes normal lines erected over the work surface of the work plate 2, and concurrently is projected obliquely in a laser light projecting surface normal to the end face of the work plate 2. By this constitution, the work plate 2 can thereby be welded to the other work plate 3 the joining section of which is disposed adjacent to the aforesaid work plate in mutually overlapping relation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding robot and a tracking sensor for welding objects to be welded, which have undulations at a substantially constant interval in the welding progress direction, and more particularly to a welding sensor. Detects the end face of the work piece along the processing progress direction, projects a laser beam from the processing laser nozzle on this end face to melt it, and another work piece to be welded with the welded part in contact with it The present invention relates to a welding robot and a tracking sensor for continuously lap-welding a robot.

[0002]

2. Description of the Related Art For example, as shown in FIG.
When the work plate materials 2 and 3 having a and 3a are overlap-welded, the work plate materials 2 and 3 are conventionally welded portions 2b and 3 thereof.
b are overlapped with each other, and the welded portions 2b and 3b are manually welded by arc welding or the like.

However, in such manual welding, the efficiency of the welding work is low, and the work plate members 2 and 3 have the undulations 2a and 3a, and the welding is performed at the undulations 2a and 3a. Since the joining line of No. 3 has a complicated shape, there is a problem that the quality of welding easily varies. Therefore, the undulating portion 2 as described above
For welding work plate materials 2 and 3 having a and 3a,
For example, it is desirable to employ a welding robot such as a laser welding robot to automate welding.

By the way, as a robot arm of a welding robot for irradiating an arbitrary point on a three-dimensional free-form surface with a welding beam from an arbitrary direction, what is generally called a one-point pointing type head or a swing arm type head is used. There is something called. These generally have five control axes, and their control requires sophisticated control technology.
FIG. 11 shows an example of the structure of a swing arm type head.

The swing arm type head 4 has an arm supporting portion 5 which is movable in the X-axis direction, the Y-axis direction and the Z-axis direction of the three-dimensional space, and the arm supporting portion 5 has the first arm portion 6 and the arm supporting portion 5. The second arm portion 7 and the third arm portion 8 are supported.

The first arm portion 6 has a shaft 6a whose one end is fixed to the arm supporting portion 5 and extends in the Z-axis direction, and is rotatable about the shaft 6a as indicated by an arrow A _1. ing. The second arm portion 7 has a shaft 7a having one end fixed to the other end of the first arm portion 6 and extending at right angles to the Z-axis direction.
It is rotatable around as shown by arrow A ₂ . Further, one end of the third arm portion 8 is fixed to the other end of the second arm portion 7, and the shaft 7 of the second arm portion 7 is fixed.
It has an axis 8a extending at a right angle to a.

It is conceivable to employ the welding robot having the swing arm type head 4 having the above-mentioned shaft configuration as a laser welding robot for laser welding the work plate materials 2 and 3 in FIG. In this laser welding robot, the third arm portion 8 is provided along the axis 8a of the third arm portion 8 of the swing arm type head 4 of FIG.
The laser beam 1 is emitted from the processing laser nozzle 9 at the other end. Further, the third arm portion 8 supports a tracking sensor (not shown) for detecting the end face 2c along the working progress direction of the welding work of the work plate member 2.

The above laser welding robot welds the work plate members 2 and 3 in the following manner, for example. That is, the work plate members 2 and 3 are placed on a bed (not shown) of the welding robot, and the work plate members 2 and 3 are moved in the machining progress direction by the bed. Then, as shown in FIG. 10, the swing arm type head 4 with respect to the end surface 2c including the normal line n standing on the work surface of the work plate material 3 and along the welding progress direction of the work plate materials 2 and 3 The arm support 5 and the first arm 6 are arranged such that the laser light 1 is incident on the end face 2c at an angle of, for example, 45 degrees with respect to the normal line n within the laser light projection plane P at a right angle.
Or controls the third arm portion 8. The postures of the first arm portion 6 to the third arm portion 8 in this case are shown in FIG.

[0009]

As can be seen from FIG. 12, in the welding robot having the swing arm type head 4, the flat portions 2d and 3d of the work plate members 2 and 3 to the undulating portions 2a and 3a (see FIG. 10). In the process (a) to (d) of reaching the flat portions 2d and 3d of the work plate members 2 and 3 again via the top of the arm supporting portion 5, the position of the arm supporting portion 5 in the X-axis, Y-axis and Z-axis directions respectively changes. ing. Further, the first arm portion 6 rotates about its axis 6a as indicated by an arrow A ₁ to change the direction of the second arm portion 7 in the XY plane. Moreover, the third arm portion 8 to change the direction in YZ plane rotates as indicated by arrow A ₂ The second arm portion 7 about its axis 7a. Furthermore, the third arm portion 8
The tracking sensor (not shown) supported by the work plate member 3 always avoids the welding light (plasma light).
In order to observe the end face 2c slightly ahead of the welding processing point from the normal line n direction of the workpiece surface, that is, in order to correct the visual field of the tracking sensor, the arrow A ₃ in FIG. It is necessary to rotate as shown in.

Therefore, when the welding robot having the swing arm type head 4 is adopted as the laser welding robot for welding the work plate materials 2 and 3 as described above, X
In addition to the control of the 5 axes of the axis, the Y axis, the Z axis, the axis 6a of the first arm portion 6 and the axis 7a of the second arm portion 7, the axis of the third arm portion 8 is used to correct the visual field of the tracking sensor. There is a problem in that the total of 6 axes to which 8a is added requires complex control in which each is related to each other, and the control becomes very complicated.

As for the tracking sensor, a conventional welding robot that detects the extending direction of a welding line that is almost a straight line on a two-dimensional plane has been conventionally proposed. However, a tracking sensor that can be used in the above laser welding robot that welds the work plate materials 2 and 3 having the undulating portions 2a and 3a as shown in FIG. 10 has not been conventionally known.

An object of the present invention is to carry out lap welding of an object to be welded onto another welded part of an object to be welded while maintaining a predetermined angle with respect to an end surface of the object to be welded along the welding progress direction. By feedback from the tracking sensor,
(EN) A welding robot and a tracking sensor therefor capable of easily performing correction control of a projection position of a laser beam with a simple configuration.

[0013]

In order to achieve the above object, a welding robot according to a first aspect of the present invention comprises a metal plate material, and an object to be welded in which undulations are formed in a direction in which welding processing proceeds. Laser light from the laser nozzle for processing on the end face, including the normal line standing on the work surface of the work piece to be welded, and zero degrees with respect to the normal line in the laser light projection plane perpendicular to the end face of the work piece to be welded. A welding robot for projecting and overlapping welding with an angle range between 90 degrees and 90 degrees, each arm supporting section being movable in the XYZ three-axis directions orthogonal to each other, and one end fixed to this arm supporting section. A first arm portion having a shaft extending vertically toward the work surface and rotatable about this shaft, and one end fixed to the other end of the first arm portion at a right angle to the vertical direction. Has an extending axis A second arm portion, both of which are rotatable about this axis, and an axis whose one end is fixed to the other end of the second arm portion and which crosses the axis of the second arm portion obliquely within the laser beam projection plane. And a third arm portion that emits laser light from the processing laser nozzle at the other end along the axis to the end surface of the workpiece to be welded.

Further, in order to achieve the above-mentioned object, claim 2
The tracking sensor of the welding robot according to the above is made of a metal plate material, and a laser beam is emitted from a processing laser nozzle to the end surface of the object to be welded in which the undulations are formed in the direction in which the welding process proceeds. Projecting with an angle range between 0 and 90 degrees with respect to the normal line in the laser light projection plane that includes the normal line standing on the work surface and is perpendicular to the end face of the workpiece, A tracking sensor for a welding robot that performs lap welding, which has a direction parallel to the normal line while passing through an observation point preceding the processing point on the end face of the workpiece to which the laser beam is projected in the processing progress direction. An image forming means having an image optical axis, an image pickup means arranged behind the image forming means, for picking up an image of the end face of the object to be welded formed thereby, and converting the image into an image signal, and the image pickup means. Incident welding light An illuminating light that is included in a plane including the image forming optical axis parallel to the laser beam projecting surface and inclined with respect to the image forming optical axis An end face illuminating means having an axis for illuminating the end face of the object to be welded, and two faces parallel to the laser beam projection face and having a space between each other, and the same with respect to the imaging optical axis. Point image projection means having spot light sources each having a projection optical axis inclined in the direction, and projecting light from these spot light sources in the vicinity of the observation point at the above-mentioned intervals in the processing progress direction, and these point image projections A point image synthesizing optical system for receiving the reflected light from the work surface of the light emitted from the spot light source of the means and optically synthesizing the respective point images of the respective spot light sources on a part of the image pickup screen of the image pickup means. Having It is an feature.

Further, in order to achieve the above object, the tracking sensor of the welding robot according to claim 3 is the tracking sensor of the welding robot according to claim 2, wherein the end face is observed on the work surface by the image pickup means. There is a first observation area of the image pickup means and a second observation area of the image pickup means for observing a point image of each spot light source projected on the surface of the work, and each point of each spot light source is present. The above-mentioned part of the image pickup screen where the images are optically combined is characterized by being a shielding region of the incident light from the first observation region provided on the side of the processing point of the first observation region. is there.

Furthermore, in order to achieve the above object, a tracking sensor of a welding robot according to a fourth aspect of the present invention comprises:
A laser beam from a processing laser nozzle is provided on the end surface of the workpiece to be welded, which is made of a metal plate material and in which the undulations are formed in the direction in which the welding process progresses, and includes a normal line standing on the work surface of the workpiece. With a tracking sensor of a welding robot for projecting with an angle range between 0 degree and 90 degrees with respect to the normal line in the laser beam projection plane perpendicular to the end surface of the workpiece and performing lap welding. And an image forming means having an image forming optical axis having a direction parallel to the normal line while passing through an observation point preceding the processing point on the end surface of the workpiece on which the laser light is projected and in the processing progress direction. An image pickup means arranged behind the image forming means for picking up the image of the end face of the object to be welded formed by the image forming means and converting the image into an image signal; and welding light for attenuating the welding light incident on the image pickup means. Attenuator and observer On the other hand, while being included in a plane parallel to the laser beam projection surface and including the image forming optical axis, and having the illumination optical axis inclined with respect to the image forming optical axis, Slit light projection means for illuminating an end face and means for projecting slit light, which has a slit light source and extends from the slit light source in the X-axis direction from a direction inclined with respect to the imaging optical axis, in the vicinity of the observation point. A slit image combining optical system for receiving light reflected from the work surface of light emitted from the slit light source of the slit light projecting means and optically combining the slit image of the slit light source with a part of the image pickup screen of the image pickup means. It is characterized by having and.

Further, in order to achieve the above object, a tracking sensor of a welding robot according to a fifth aspect of the present invention comprises:
The tracking sensor of the welding robot according to claim 4, wherein a slit image of a slit light source projected on the first observation region of the image pickup means where the end face is observed by the image pickup means and the work surface is observed on the work surface. The second observation area of the imaging means is present, and the part of the imaging screen on which the slit image of the slit light source is optically combined is the first observation area provided on the processing point side. 1
This is a region where the incident light from the observation region is shielded.

[0018]

According to the welding robot of the first aspect of the present invention, the arm supporting portion has a Y-axis perpendicular to the X-axis direction.
The first arm portion has an axis that moves in the axial direction and the Z-axis direction, one end of which is fixed to the arm support portion and extends in the Z-axis direction toward the workpiece surface, and is rotatable about this axis. , The second arm portion has an axis whose one end is fixed to the other end of the first arm portion and extends at right angles to the Z-axis direction, and is rotatable around this axis,
Further, the third arm portion has one end fixed to the other end of the second arm portion and has an axis obliquely intersecting with the axis of the second arm portion within the laser light projection plane, and the other end along the axis. Since laser light is emitted from the processing laser nozzle to the end surface of the workpiece,
In order to control the axis of the third arm portion fixed to the arm portion so as to be within the laser light projection plane, it is sufficient to control the rotation of the second arm portion around that axis, and therefore, it is necessary. The control is so-called 2.5-axis control for controlling the axes of the second arm part in addition to the Y-axis and the Z-axis, and the structure of the arm of the welding robot is simple and the correction control is easy.

According to the tracking sensor of the welding robot of the second aspect, the deviation of the end surface of the workpiece to be welded is detected by the observing means in the direction perpendicular to the working direction, while the spot of the point image projection means is detected. Light from the light source is included in two surfaces parallel to the laser light projection surface and spaced from each other, and each has a projection optical axis inclined in the same direction with respect to the imaging optical axis It is possible to detect the inclination of the work surface of the work piece by projecting the light emitted from the spot light source near the observation point with a space between the points and the positional relationship of the point images of the spot light source due to the reflected light from the work surface. Therefore, by feeding back this information to the control device of the welding robot, the laser beam projection surface will always be applied to the end surface of the work piece with the undulations in the machining direction. It is possible to emit a laser beam from Zanozuru.

Further, according to the tracking sensor of the welding robot of the third aspect, the point image of the spot light source is received by the reflected light of the work surface of the light emitted from the spot light source of the point image projection means by the point image combining optical system. Is optically combined with a part of the image pickup screen of the image pickup means, so that one image pickup means can detect the information about the deviation of the end surface of the workpiece to be welded in the direction perpendicular to the working direction and the information about the inclination of the work surface. The configuration is simple and compact, the restrictions on the attachment of the tracking sensor to the third arm of the welding robot are reduced, and moreover, since there is two pieces of information in one screen, image processing can be performed at once. The image processing time also requires only one image processing time, the image processing time is shortened, and even if the welding speed is increased, the position of the end surface is sampled at small intervals. It can be, it allows tracking of the end face with high accuracy.

Further, according to the tracking sensor of the welding robot of the fourth aspect, since the inclination of the work surface of the workpiece is detected by using the slit image reflected from the work surface of the slit light source, the spot light source is used. Only one light source is needed compared to the one using, and the configuration is further simplified.

Further, according to the tracking sensor of the welding robot of the fifth aspect, the information about the deviation of the end surface of the workpiece to be welded in the direction perpendicular to the working direction and the inclination of the work surface are obtained by one imaging means. The information can be detected and the configuration is compact.
There are less restrictions on the mounting of the tracking sensor on the arm, and moreover, there are two pieces of information in one screen, so image processing can be performed at one time, and image processing time requires only one image processing time. Even if the processing time is shortened and the welding speed is increased, the positions of the end faces can be sampled at small intervals, and the end faces can be tracked with high accuracy.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an arm portion of an embodiment of a welding robot according to the present invention.

In the following, the welding progress direction of the welding robot is referred to as the X-axis direction, and the direction perpendicular to the X-axis direction and parallel to the work surface of the work plate material is referred to as the Y-axis direction. Further, the direction perpendicular to the Y-axis direction and the X-axis direction is referred to as the Z-axis direction.

The above welding robot is a work plate material (workpiece) having undulations 2a and 3a at predetermined intervals in the X-axis direction.
It is for laser welding 2 and 3. The arm portion 11 of the welding robot includes an arm support portion 12, a first arm portion 13, a second arm portion 14 and a third arm portion 15.
Composed of.

The arm support 12 is supported by a gate frame (not shown) or the like, and is movable in the Y axis direction and the Z axis direction.

In this way, the bed 16 for supporting the work plate members 2 and 3 is provided movably in the X-axis direction with respect to the arm support portion 12 movable in the Y-axis direction and the Z-axis direction. Therefore, the work plate members 2 and 3 superposed on each other at the welded portions 2b and 3b are
It is held on 6 and moves in the X-axis direction.

As shown in FIG. 2, the first arm portion 13 has a shaft 13a having one end fixed to the arm support portion 12 and extending in the Z-axis direction toward the work surfaces of the work plate members 2 and 3. Arrow A around this axis 13a
It is rotatable as indicated by ₁₁ . In addition, the second
Arm 14 is pivotally as indicated by arrow A ₁₂ together around the shaft 14a having an axis 14a extending at right angles to the other end of the first arm portion 13 is fixed at one end relative to the Z-axis direction Has become.

The third arm portion 15 is the second arm portion 1.
One end is fixed to the other end of 4 and is supported by the second arm portion 14. As shown by the solid line in FIG. 2, the third arm portion 15 has a shaft 15a that intersects with the shaft 14a of the second arm portion 14 at a so-called obtuse angle.

The axis 15a of the third arm portion 15 may be oblique to the axis 14a of the second arm portion 14 at a so-called acute angle, as shown by the dotted line in FIG. This is because the first arm portion 13 has its shaft 13a
When rotated by 180 degrees around, the direction of the shaft portion 15a of the third arm portion 15 shown by the solid line in FIG. 2 can be matched with the direction of the shaft portion 15a of the third arm portion 15 shown by the dotted line. Because.

Therefore, in the following description, the third arm portion 15 shown by the solid line and the third arm portion 15 shown by the dotted line in FIG.

As shown in FIGS. 3A to 3D, the shaft 15a of the third arm portion 15 has the work plate member 3 attached thereto.
End surface 2c of the work plate member 2 on which the laser beam including the normal line n standing on the work surface and along the X-axis direction is projected.
As described above, the shaft 14a of the second arm portion 14 is obliquely intersected within the laser light projection plane P perpendicular to the above.

The third arm portion 15 has the shaft 15 thereof.
A laser beam is emitted from the processing laser nozzle 17 (see FIGS. 1 and 2) at the other end along a to the end surface 2c of the work plate member 2. A tracking sensor 18 (see FIG. 1) is supported by the third arm portion 15.

The structure of the tracking sensor 18 is shown in FIG.
It will be described with reference to FIG. The tracking sensor 1
8 photographs the end face 2c of the work plate 2 on the side where the laser beam is projected among the work plates 2 and 3, detects the edge thereof as a welding joining line, and detects the position in the Y-axis direction. Imaging device 21 as Y-axis sensor, the end surface 2c
The illuminating device 22 for illuminating the workpiece and the inclinations of the workpiece surfaces of the workpiece plate materials 2 and 3 are detected, and
The point image projection device 23 for detecting the undulating portions 2a and 3a.

The image pickup device 21 is included in the first observation region 24 and the first observation region 24 on the work surfaces of the rectangular work plate members 2 and 3 shown by hatching the inner circumference in FIG. An image of the end surface 2c of the work plate member 2 is captured.
Since strong welding light (plasma light) is incident on and reflected by the end region 26 near the processing point 25 of the first observation region 24 where the laser beam light 1 is irradiated, the imaging device 21 is used. Are used as mask regions 26 for the reflected light from the end regions 26. The configuration for masking the reflected light from the mask region 26 will be described later with reference to FIG. 7.

As shown in FIG. 4 for details of the specific structure of the image pickup device 21, the first observation region 24 (see FIG. 6).
Image forming lens 27 for picking up the image), an image forming lens 28 arranged behind this image forming lens 27, and an end surface 2c of the work plate material 2 arranged behind this image forming lens 28 and formed an image thereby. The first observation region 24 including the edge of
CCD camera 2 having a photoelectric conversion surface (imaging screen) on which the image of the image is formed and outputting an image signal corresponding to the formed image.
9 and two interference filters 31 and 32 for attenuating welding light from the welding processing point 25 incident on the CCD camera 29.

The image forming lens 27 and the image forming lens 28 are
Together with the interference filters 31, 32 and the infrared cut filter 33 for cutting infrared rays incident from the processing point 25, they are incorporated in one lens barrel 34. The lens barrel 34 is attached to the tip of the main lens barrel 35. The CCD camera 29 is attached to the rear end portion of the main lens barrel 35, and the whole is housed in one outer case 36. The interference filters 31 and 32 are arranged in the lens barrel 34 on the first observation region 24 side with respect to the imaging lens 27, and the infrared cut filter 33 is
In the lens barrel 34, the imaging lenses 27 and 28 are arranged on the CCD camera 29 side.

Optical axis of the imaging lens 27, imaging lens 2
The lens barrel 34 and the CCD camera 29 are attached to the main lens barrel 35 so that the optical axis of 8 and the axis of the CCD camera 29 coincide with the optical axis of the main lens barrel 35. Hereinafter, the optical axis of the main lens barrel 35 will be referred to as the optical axis 37 of the imaging device 21.

The image pickup device 21 has the outer case 36.
At, the support member 38 (see FIGS. 1 and 4) fixes the third arm portion 15. At this time, the imaging device 21
As shown in FIG. 5, the optical axis 37 of the
5 at a center point 39 (see FIG. 6) of the first observation region 24 that precedes the distance d _{1 by} 5 with the direction of the normal line of the work surfaces of the work plate materials 2 and 3 or in the X-axis direction (processing progress). and the angle theta ₁ inclined in the direction), is fixed to the third arm portion 15. In this embodiment, the distance d ₁ is, for example, 6
set to mm. Also, if the optical axis 37 of the imaging device 21 is the angle theta ₁ inclined, the angle theta _1, for example 1
It is set to 0 degrees.

In the outer case 36 of the image pickup device 21,
As shown in FIG. 4, in order to protect the interference filters 31 and 32 from the metal vapor generated at the processing point 25 due to the laser welding, a protection cover 41 is provided at the front part of the lens barrel 34, and a concrete cover is provided. Although not shown in the figure, a dry air blowing device is provided in the front part of the outer case 36. From this dry air blowing device, the protective cover 4
Dry air is jetted from the side of the protection cover 41 along the surface of the protection cover 41 to prevent the metal vapor from being deposited on the protection cover 41.

On the other hand, the illumination device 22 for illuminating the end surface 2c of the work plate member 2 illuminates the work surface of the work plate member 2 with scattered light.

Of the two illumination lenses 43 and 44 of the illumination device 22, in front of the illumination lens 43 on the opposite side of the one end of the light guide 46, as in the image pickup device 21,
In order to protect the illumination lens 43 from the metal vapor generated at the processing point 25 due to the laser welding, a protection cover 47 is provided on the front part of the lens case 42. Also,
Although not specifically shown, dry air is blown from the side of the protective cover 47 along the surface of the protective cover 47 by the dry air blowing device attached to the front portion of the lens case 42, and the dry air is blown to the protective cover 47. The metal vapor is prevented from being deposited.

As shown in FIG. 6, the illumination optical axis 48 of the illumination device 22 includes the center point 39 of the first observation region 24, is parallel to the laser light projection plane P, and is the optical axis of the imaging device 21. It is included in the plane P ₁ including 37 and forms an angle θ ₂ with the Z-axis direction. Thereby, the illuminating device 6 illuminates the end surface 2c of the work plate member 2 from diagonally above. In this embodiment, for example, θ ₂ = 20 degrees is set. In this way, when the end surface 2c of the work plate member 2 is illuminated obliquely from above in the lateral direction, the specular reflected light having a large change in brightness on the work surfaces of the work plate members 2 and 3 of the illumination device 22 does not enter the imaging device 21. , Imaging device 21
Light with a small change in brightness is incident on the edge of the edge, and the edge of the end face 2c can be emphasized.

The illumination device 22 is, as shown in FIG.
The support member 38 together with the imaging device 21 is attached to and supported by the third arm portion 15 so as to satisfy the above relationship.

The point image projection device 23, as shown in FIG.
First and second semiconductor lasers 51a and 51b are provided as two spot light sources (in FIG. 4, semiconductor laser 5
1b is not shown. ). Of the first and second semiconductor lasers 51a and 51b, the first semiconductor laser 51a has a projection optical axis 52a within the plane P ₁ including the optical axis 37 of the imaging device 21, as shown in FIG. Has a projection optical axis 52a inclined by an angle θ _{3 with} respect to the Z-axis direction,
Laser light is projected at a position at a distance d ₂ from the center point 39 of the first observation region 24. In this embodiment, the angle θ ₃ is set to 30 degrees and the distance d ₂ is set to 4 mm.

Second semiconductor laser 5 of point image projection device 23
1b, the projection optical axis 52b is the surface P ₁ parallel to the plane P ₂
It is inside. That is, the second semiconductor laser 51b is moved from the projection position of the laser light of the first semiconductor laser 51a to the side opposite to the processing point 25 by the distance d ₃ and the first semiconductor laser 5b is moved.
It has a projection optical axis 52b obtained by moving the above-mentioned projection optical axis 52a of the laser beam 1a in parallel.

As shown in FIG. 8, the laser light from the first semiconductor laser 51a and the laser light from the second semiconductor laser 51b are in the Z-axis direction of the processing laser nozzle 17 with respect to the work surface of the work plate 2. When the distance has a specified value, the first of the work surfaces of the work plate materials 2 and 3
From the X-axis passing through the center point 39 of the observation region 24, it is projected to a predetermined distance d ₂ apart projection position 54a and 54b.
These projection positions 54a and 54b are used to detect the distance between the work surfaces of the work plate members 2 and 3 and the processing laser nozzle 17 and the inclination of the work surface of the work plate members 2 and 3 as described below. Second set square shape
It is in the observation area 53.

In the point image projection device 23, since the projection optical axis 52a of the first semiconductor laser 51a and the projection optical axis 52b of the second semiconductor laser 51b are inclined as described above, the tracking sensor 18 ( (See FIG. 1) reaches the undulations (2a, 3a) of the work plate members 2, 3, the laser light of the first semiconductor laser 51a and the second semiconductor laser 51b of the point image projection device 23 on the work surface is changed. The projection position changes. Therefore, by detecting the projection position Z ₁ of the first semiconductor laser 51a,
The distance between the work surface and the processing laser nozzle 17 can be detected, and the first semiconductor laser 51 can be detected.
by detecting a change in the projection position of the second semiconductor laser 51b with respect to the projection position of a (Z ₂ -Z _1), that the X-axis direction of the inclination of the work surface of the work sheet 2 is detected Become.

As shown in FIG. 4, the point image projection device 23 is used.
Both the first semiconductor laser 51a and the second semiconductor laser 51b in front of the first semiconductor laser 51a and the second semiconductor laser 51b are similar to the imaging device 21 in that the first and second metal vapor generated from the metal vapor generated at the processing point 25 accompanying the laser welding. In order to protect the semiconductor lasers 51a and 51b, a protection cover 55 is provided in the front part. Although not specifically shown, the dry air blowing device attached to the front portion of the point image projection device 23 blows dry air from the side of the protective cover 55 along the surface of the protective cover 55 to protect it. The metal vapor is prevented from being deposited on the cover 55.

As shown in FIG. 4, the point image projection device 23 has the projection optical axes 52a and 52b having the above-mentioned relationship, and the mounting member 58 provided on the outer case 57 allows
It is fixed to the outer case 36 of the imaging device 21.

As shown in FIG. 8, the image of the second observation region 53 on which the light emitted from the first semiconductor laser 51a and the second semiconductor laser 51b of the point image projection device 23 is projected is as shown in FIG. Of the projection area 62 on which the image of the first observation area 24 is projected on the photoelectric conversion surface 61 of the CCD camera 29 of No. 21, a mask corresponding area 63 corresponding to the mask area 26 of the first observation area 24 will be described below. It is combined by the point image combining optical system.

FIG. 7 shows the optical axis 3 in the image pickup device 21.
7. From the center point 39 of the first observation area 24 to the CCD camera 2
9, the optical path 64 to the photoelectric conversion surface 61, the optical path 65 from the mask area 26 to the mask equivalent area 63 of the photoelectric conversion surface 61 of the CCD camera 29, and the optical path 6 of the point image combining optical system.
6a and 66b are shown.

The light from the center point 39 of the first observation area 24 is transmitted along the optical path 64 through the interference filters 31 and 32, the imaging lenses 27 and 28 described in FIG. 4, and the first diaphragm. After passing through the aperture 68 of the member 67,
The first observation region 24 on the photoelectric conversion surface 61 of the CCD camera 29 passes through the aperture 71 of the second aperture member 69.
Is incident on the projection area 62 of the image.

On the other hand, the light from the mask area 26 near the processing point 25 of the first observation area 24 is transmitted through the optical path 65.
Along with the interference filters 31, 32, the imaging lenses 27, 2
8 and the like, and then the aperture hole 68 of the first aperture member 67.
Passes, but is blocked by the second diaphragm member 69, and C
It does not enter the photoelectric conversion surface 61 of the CD camera 29.

On the other hand, the work plate member 2 of the laser light from the first semiconductor laser 51a and the second semiconductor laser 51b.
Each reflected light from the work surface of the optical path 66a,
66b, along with the interference filters 31 and 32, the imaging lens 2
After passing through 7, 28, etc., the wedge prism 72 provided on the first diaphragm member 67 is transmitted, and further another wedge prism 73 provided on the second diaphragm member 69 is transmitted, so that the CCD camera 29 The light is incident on the mask-corresponding region 63 on the photoelectric conversion surface 61.

As a result, an image in the first observation region 24 and an image in the second observation region 53 excluding the mask region 26 is formed on the photoelectric conversion surface 61 of the CCD camera 29, and CC
The D camera 29 outputs one image signal in which the image in the first observation area 24 and the image in the second observation area 53 are combined. Therefore, the time of one frame of the image signal output from the photoelectric conversion surface 61 of the CCD camera 29 (33
ms), position information in the Y-axis direction of the end surface 2c of the work plate material 2 to be welded, information in the Z-axis direction of the work plate materials 2 and 3 and information on the undulations 2a and 3a of the work plate materials 2 and 3 are obtained. Therefore, the image information processing load is reduced and the image information processing time is shortened.

As described above, the short image information processing time is particularly advantageous in the case of laser welding, in which the work plate materials 2 and 3 are welded at high speed. For example, the welding speed is 5m /
min, 3.0 m / min, 2.0 m / min, 1.5
At m / min and 1.0 m / min, the welding was 2.78 mm, 1.67 mm, 1.11 mm, 0.
It will travel 83 mm and 0.56 mm. Therefore, in this embodiment, even if the welding speed is 5 m / min, the position of the end surface 2c of the work plate member 2 can be sampled at intervals of 2.78 mm.

On the photoelectric conversion surface 61 of the CCD camera 29, as shown in FIG.
A first image processing area 74 having a width of a ₁ and a second image processing area 75 having a width of a ₂ at a distance f ₁ from the first image processing area 74 are set. The photoelectric conversion surface 61
The center line Xi corresponds to the X axis that is the center line of the first observation region 24.

The positions of the end faces 2c of the work plate members 2 and 3 in the Y-axis direction are, for example, the intersections of the sides of the first image processing area 74 on the mask equivalent region 63 side and the center line Xi, and the end faces 2c. Distance Y between image 2ci and the intersection of the above side
The end face 2c is detected by detecting _1.
The inclination with respect to the Y-axis direction is the distance Y between the intersection of the side of the second image processing area 75 on the mask equivalent region 63 side and the center line Xi and the intersection of the image 2ci of the end face 2c and the side. detected from ₂ and the difference between the distance _{Y 1 (Y 2 -Y 1)} .

Further, the photoelectric conversion surface 61 of the CCD camera 29
In the mask-corresponding region 63, the third image processing area 76 having a width b ₁ and the distance f from the third image processing area 76
_A fourth image processing area 77 having a width of b ₂ apart from ₂ is set.

The position of the processing point 25 on the work plate 2 in the Z-axis direction is projected from, for example, the first semiconductor laser 51a of the point image projection device 23, and is reflected by the work surface of the work plate 2 to cause photoelectric conversion of the CCD camera 29. This is detected by detecting the distance Z ₁ from the center line Xi of the point image 78 projected on the third image processing area 76 of the mask-equivalent region 63 of the conversion surface 61.

Further, X on the work surface of the work plate materials 2 and 3
The inclination in the axial direction is relative to the distance Z ₁ of the distance Z ₂ from the center line Xi of the point image 79 projected on the fourth image processing area 77 of the mask equivalent region 63 of the photoelectric conversion surface 61 of the CCD camera 29. It is detected by detecting the amount of change (Z ₂ −Z ₁ ).

As shown in FIG. 9, the tracking sensor 18 having the structure described above has its drive control section 81.
Together with this, the sensor unit 91 is configured. The drive controller 81 of the sensor unit 91 supplies drive power to the illumination device 22, the imaging device 21, the point image projection device 23, and controls the imaging of the imaging device 21.

Imaging device 21 of tracking sensor unit 18
The image signal output from the preprocessing unit 8 of the image processing unit 92.
Input to 3. The pre-processing unit 83 uses the image pickup device 2
Pre-processing for surely detecting the image 2ci of the end surface 2c of the work plate materials 2 and 3 is performed, such as removal of noise components from the image signal input from 1.

The image signal pre-processed by the pre-processing unit 83 is input to the detection position calculation unit 84. The detection position calculation device 84 has a memory (not shown) that stores a necessary image processing algorithm, processes the preprocessed image signal based on the image processing algorithm, and will be described with reference to FIG. Distance information Y ₁ , Y ₂ , Z ₁ and (Z ₂
-Z ₁ ) value is calculated.

A control interface section 93 is provided between the image processing section 92 and the robot control section 87 of the welding robot.
Is provided. The control interface unit 93 includes a correction amount calculation unit 85 and a pulse conversion unit 86.

The correction amount calculation section 85 includes an image processing section 92.
The distance information Y input from the detected position calculation unit 84 of
_1, based on Y _2, Z ₁ and (Z ₂ -Z _1), the correction amount in the Y-axis direction deviation of the processing laser nozzle 17 relative to the position of the end surface 2c to be welded of the work plate 2 (lateral), that is A correction amount of the displacement of the arm support portion 12 (see FIG. 2) in the Y-axis direction (hereinafter referred to as an arm support portion lateral displacement correction amount),
A correction amount of the inclination of the welding process with respect to the end surface 2c in the working direction, that is, the first arm portion 1 with respect to the end surface 2c.
3 (see FIG. 2) of the rotation angle correction amount (hereinafter referred to as the first arm portion rotation angle correction amount), and the deviation (vertical deviation) of the machining laser nozzle 17 with respect to the work surface of the work plate 2 in the Z-axis direction. Correction amount, that is, arm support 12 (see FIG. 2)
3 (a) to (a) in FIG. 3 on the laser light projection plane P that rotates based on the correction amount of the deviation in the Z-axis direction (hereinafter referred to as the arm support portion vertical deviation correction amount) and the inclination of the work surface. As shown in (i), the shaft 15 of the third arm portion 15 is always
In order to hold a, the correction amount of the rotation angle of the second arm portion 14 based on the inclination of the work surface of the work plate material 2 (hereinafter referred to as the second arm portion rotation angle correction amount) is calculated.

The arm support lateral deviation correction amount, the first arm rotation angle correction amount, the arm support vertical deviation correction amount, and the second arm rotation angle correction amount calculated by the correction amount calculation unit 85 are converted into pulses. For example, the number of pulses is converted by the unit 86 and output to the robot control unit 87.

The robot control section 87 converts the arm support section lateral deviation correction amount, the arm support section vertical deviation correction quantity, and the first arm section rotation angle converted into the number of pulses input from the pulse conversion section 86 of the control interface section 93. Depending on the correction amount and the second arm portion rotation angle correction amount, the Y-axis direction position and the Z-axis direction position of the arm support portion 12, the rotation of the first arm portion 13 around the axis 13a, and the second arm portion 14 are obtained.
Control the rotation about the axis 14a.

As a result, the processing laser nozzle 17 of the welding robot shown in FIG. 1 moves from the position shown in FIG.
When approaching the undulating portions 2a and 3a of the work plate members 2 and 3 indicated by (B) (in FIG. 3, for convenience of description, the robot arm is shown as moving in the X-axis direction). Since the distance information Z ₁ and (Z ₂ −Z ₁ ) change, the arm support 12 is displaced in the Z-axis direction according to the distance information Z ₁ , while the distance information (Z ₂ −Z ₁ ) changes. Accordingly, the second arm portion 14 rotates around its axis 14a, and as shown in FIG. 3B, the axis 15a of the third arm portion 15 is always arranged in the laser beam projection plane P. The robot controller 87 controls the machining laser nozzle 17 so that the machining laser nozzle 17 is incident on the end surface 2c of the work plate member 2 at an incident angle θ ₄ .

The distance information Z ₁ and (Z ₂ -Z ₁ ) continuously change while the processing laser nozzle 17 is in the undulating portions 2a and 3a of the work plate materials 2 and 3, and accordingly, the distance information Z ₁ and (Z ₂ -Z ₁ ) change accordingly. , The arm support portion 12 is continuously displaced in the Z-axis direction, while the second arm portion 14 is continuously rotated around its axis 14a, as shown in (b) to (h) of FIG. , The axis 15a of the third arm portion 15 is always the laser beam projection surface P.
The laser nozzle 17 for processing is placed inside the work plate 2
The robot controller 87 controls so that the light is incident on the end surface 2c at the incident angle θ ₄ .

When the processing laser nozzle 17 reaches the flat portions 2d, 3d from the undulating portions 2a, 3a of the work plate members 2, 3, the change in the distance information Z ₁ and (Z ₂ -Z ₁ ) is almost zero. However, also in this case, the distance information Z ₁ and (Z ₂ −Z ₁ ) control the position of the arm support 12 in the Z-axis direction and the rotation angle of the second arm 14 around the axis 14a. Then, as shown in (i) of FIG.
The robot controller 87 controls the arm 15 such that its axis 15a is always arranged in the laser beam projection plane P, and the processing laser nozzle 17 is incident on the end surface 2c of the work plate 2 at the incident angle θ _4. .

In the process of (a) to (i) of FIG. 3 described above, the control of the rotation angle indicated by the arrow A ₁₁ around the shaft 13a of the first arm portion 13 is performed as follows, for example. Done. That is, assuming that (a) in FIG. 3 is the initial position for welding one work plate member 2, based on the distance information (Y ₂ −Y ₁ ) at this initial position, the axis of the first arm unit 13 is changed. If the initial position around 13a is set, the shaft 15a of the third arm portion 15 is fixed to the second arm portion 14 obliquely to the shaft 14a of the second arm portion 14 as described above. And as shown in FIG.
Incident angle θ ₄ = 45 degrees of the laser beam 1 on one end face 2c of the above work plate material 2 along the X-axis direction (this angle θ ₄ or 90 ° −θ ₄ is arbitrary between 0 degree and 90 degrees if necessary. Value of, for example, 60 degrees.), The rotation angle of the one work plate 2 around the axis 13a of the first arm 13 indicated by arrow A ₁₁ can be controlled. It is unnecessary. As a result, the rotation position of the first arm portion 13 can be fixed to a constant initial value for each work plate member 2.

From the above, in the present embodiment, at most, two-dimensional control of the arm support portion 12 and control of the rotation angle of the second arm portion 14 around the shaft 14a are added at a very simple control (so-called). The second arm unit 1 by the 2.5-dimensional control)
The shaft 14a of No. 4 and the shaft 15a of the third arm portion 15 are always held in the laser beam projection surface P, and the processing laser nozzle 17
While tracking the end surface 2c of the work plate member 2, the laser beam 1 is projected onto the end face 2c of the work plate member 2 along the X-axis direction at the incident angle θ ₄ , and the work plate member 2 is projected.
Can be welded to another workpiece plate 3 having the welded portion 3b superposed thereon.

On the other hand, in the conventional welding robot having the swing arm type head 4 described with reference to FIG. 11, as described above, the X axis, the Y axis, the Z axis, the axis 6a of the first arm portion 6, It is necessary to control a total of 6 axes of the shaft 7a of the second arm portion 7 and the shaft 8a of the third arm portion 8.

In addition, in the above-mentioned conventional welding robot, the shaft 6a of the first arm portion 6 and the shaft 7a of the second arm portion 7 are connected at a right angle, and the shaft 7a of the second arm portion 7 and the third arm portion are connected. Since the axis 8a of the portion 8 is connected at a right angle, as can be seen from (a) to (i) of FIG. 12, the end surface 2a of the work plate member 2 in the laser beam projection plane P is at an angle of, for example, 45 degrees. In order to make the laser beam 1 incident, the rotation of the first arm portion 6 indicated by the arrow A ₁ and the rotation of the second arm portion 7 indicated by the arrow A _{2 are performed.}
It is necessary to combine with the rotation shown in (1), that is, to combine both and control them simultaneously.

Further, it is necessary to control the distance between the processing laser nozzle 1 and the end surface 2c of the work plate 2 to be constant.
For this control, in addition to the combined simultaneous control of the first arm section 6 and the second arm section 7, the arm support section 5 is controlled simultaneously in the X-axis, Y-axis and Z-axis directions. Will also be needed.

From the above, when the conventional welding robot having the swing arm type head 4 described in FIG. 11 is used, in addition to the control of 6 axes, combined control of these axes is required. Although extremely complicated axis control is required, in contrast to this, in the above-mentioned embodiment, as described above, the first and second control of the arm support portion 12 in the Y-axis direction and the Z-axis direction are at most important. 2 axis 14a of arm 14
The work plate materials 2 and 3 having the undulations 2a and 3a are subjected to the 2.5-dimensional control including the control of the rotation angle around the
INDUSTRIAL APPLICABILITY The present invention is extremely useful industrially because it can be continuously and automatically welded.

In the above-described embodiment, the point image projection device 23 includes the first semiconductor laser 51a and the second semiconductor laser 51.
Although the distance information Z ₁ and (Z ₂ −Z ₁ ) are obtained by using b, the first semiconductor laser 51a and the second semiconductor laser 51b are not specifically shown, but instead of the first semiconductor laser 51a and the second semiconductor laser 51b.
A slit light source can also be used.

That is, from the slit light source, slit light extending in the X-axis direction from the direction inclined with respect to the optical axis 37 of the image pickup device 21 is projected in the vicinity of the observation point, and the work surface of the light emitted from this slit light source. The slit image of the slit light source is optically combined with a part of the photoelectric conversion surface 61 of the CCD camera 29 by receiving reflected light from the CCD camera 29, and the third image of the mask-corresponding area 63 of the photoelectric conversion surface 61 of the CCD camera 29.
Distances Z ₁ and Z from the slit image center line Xi in the image processing area 76 and the fourth image processing area 37
By detecting ₂ , the distance information in the Z-axis direction between the work surface and the processing laser nozzle 17 and the work surface inclination information of the work plate materials 2 and 3 can be obtained from these distances Z ₁ and Z _2. You can

If the slit light source is adopted as described above, the distance information Z ₁ and (Z ₂₎ can be obtained as compared with the case using the first and second two semiconductor lasers 51a and 51b.
The structure of the -Z ₁ ) detection means is simplified, and the cost of the tracking sensor is reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external appearance of an arm portion of an embodiment of a welding robot according to the present invention.

FIG. 2 is an explanatory diagram of a shaft configuration of an arm portion that constitutes an arm portion of the welding robot of FIG.

FIG. 3 is an explanatory diagram showing a posture of an arm portion during welding of the welding robot of FIG.

4 is a perspective view showing a configuration of an example of a tracking sensor used in the welding robot of FIG.

5 is a side view of the tracking sensor of FIG. 4 viewed from the Y-axis direction.

6 is an explanatory diagram of a geometrical arrangement of optical axes of components of the tracking sensor of FIG.

FIG. 7 is an explanatory diagram of an optical path of an imaging device of a tracking sensor and a combining optical system.

FIG. 8 is an explanatory diagram of a photoelectric conversion surface of a CCD camera on which a first observation region, a second observation region, and an image thereof are projected.

FIG. 9 is a system configuration diagram of a welding robot according to the present invention.

FIG. 10 is an explanatory diagram of a work plate member having an undulating portion.

FIG. 11 is an explanatory diagram of a shaft configuration of an arm portion forming an arm portion of a conventional welding robot.

12 is an explanatory diagram showing the posture of the arm portion during welding of the welding robot of FIG. 11. FIG.

[Explanation of reference numerals] 1 laser light 2 work plate material 2a undulating portion 2b welded portion 2c end face 2d flat portion 3 work plate material 3a undulating portion 3b welded portion 3d flat portion 11 arm portion 12 arm support portion 13 first arm portion 13a shaft 14th 2 arm part 14a axis 15 3rd arm part 15a axis 16 bed 17 processing laser nozzle 18 tracking sensor 21 imaging device 22 illumination device 23 point image projection device 24 first observation area 25 processing point 26 edge area (mask area) 27 Image forming lens 28 Image forming lens 29 CCD camera 31 Interference filter 32 Interference filter 37 Optical axis 48 Illumination optical axis 51a Semiconductor laser 51b Semiconductor laser 52a Projection optical axis 52b Projection optical axis 53 Second observation area 61 Photoelectric conversion surface 62 Projection area 63 Mask equivalent area 74 First processing area 75 second processing area 76 third processing area 77 fourth processing area 78 point image 79 point image 87 robot controller 91 sensor unit 92 image processing unit 93 control interface unit

Claims (5)

[Claims] 1. A laser beam from a processing laser nozzle is erected on the work surface of the workpiece to be welded to an end surface of the workpiece, which is made of a metal plate material and has undulations formed in a direction in which welding proceeds. And lap welding in which the angle range between zero and 90 degrees with respect to the normal is included in the laser light projection plane that includes the normal and is perpendicular to the end face of the workpiece. A robot having an arm support part movable in three orthogonal XYZ axis directions and an axis having one end fixed to the arm support part and extending in the vertical direction toward the work surface, and rotating around this axis. A freely movable first arm part, and a second arm part having one end fixed to the other end of the first arm part and having a shaft extending at a right angle to the vertical direction and rotatable about the shaft. Of this second arm One end is fixed to the end and has an axis that obliquely intersects with the axis of the second arm portion in the laser light projection surface, and along this axis from the processing laser nozzle at the other end to the end surface of the workpiece. A welding robot, comprising: a third arm portion that emits laser light. 2. A laser beam from a processing laser nozzle is erected on the work surface of the workpiece to be welded to the end surface of the workpiece, which is made of a metal plate material and has undulations formed in the direction in which the welding process proceeds. And lap welding in which the angle range between zero and 90 degrees with respect to the normal is included in the laser light projection plane that includes the normal and is perpendicular to the end face of the workpiece. A tracking sensor for a robot, which has an imaging optical axis that passes through an observation point preceding the processing point on the end surface of the workpiece on which laser light is projected and that is parallel to the normal line. An image forming unit having the image forming unit, an image forming unit arranged behind the image forming unit, for forming an image of the end face of the object to be welded formed by the image forming unit, and converting the image into an image signal, and welding light incident on the image forming unit. Welding light attenuating means for attenuating While being provided with an observing means, the object to be welded has an illumination optical axis that is included in a plane parallel to the laser beam projection surface and that includes the imaging optical axis, and that is inclined with respect to the imaging optical axis. Of an end face illuminating means for illuminating the end face, and a projection optical axis included in each of two surfaces parallel to the laser light projection surface and having a distance from each other and inclined in the same direction with respect to the imaging optical axis. Each has a spot light source, and the point image projection means for projecting the light from these spot light sources in the vicinity of the observation point at the above-mentioned intervals in the working direction, and emitted from the spot light sources of these point image projection means. A point image synthesizing optical system for optically synthesizing each point image of each of the spot light sources on a part of the image pickup screen of the image pickup means by receiving reflected light of light from the work surface. Welding robot Tsu King sensor. 3. The image pickup means for observing a first observation region of the image pickup means where the end face is observed by the image pickup means and a point image of each spot light source projected on the work surface on the work surface. Second observation area exists, and the part of the imaging screen on which the point images of the spot light sources are optically combined is the first observation area provided on the processing point side of the first observation area. The tracking sensor of the welding robot according to claim 2, wherein the tracking sensor is a region for shielding incident light from the observation region of. 4. A laser beam from a processing laser nozzle is erected on the surface of the work piece to be welded, which is made of a metal plate material and has an undulating portion formed in the direction in which the welding process progresses. And lap welding in which the angle range between zero and 90 degrees with respect to the normal is included in the laser light projection plane that includes the normal and is perpendicular to the end face of the workpiece. A tracking sensor for a robot, which has an imaging optical axis that passes through an observation point preceding the processing point on the end surface of the workpiece on which laser light is projected and that is parallel to the normal line. An image forming unit having the image forming unit, an image forming unit arranged behind the image forming unit, for forming an image of the end face of the object to be welded formed by the image forming unit, and converting the image into an image signal, and welding light incident on the image forming unit. Welding light attenuating means for attenuating While being provided with an observing means, the object to be welded has an illumination optical axis that is included in a plane parallel to the laser beam projection surface and that includes the imaging optical axis, and that is inclined with respect to the imaging optical axis. A slit for illuminating the end face and a slit light source, and projecting slit light extending from the slit light source in the X-axis direction from a direction inclined with respect to the imaging optical axis in the vicinity of the observation point. A light projection unit and a slit for receiving the light emitted from the slit light source of the slit light projection unit and reflected from the work surface to optically combine the slit image of the slit light source with a part of the image pickup screen of the image pickup unit. A tracking sensor for a welding robot, comprising: an image synthesizing optical system. 5. A first observation region of the image pickup means where the end face is observed by the image pickup means and a slit image of a slit light source projected on the work surface is observed on the work surface. There are two observation regions, and the part of the imaging screen where the slit image of the slit light source is optically combined is incident from the first observation region provided on the processing point side of the first observation region. The tracking sensor for a welding robot according to claim 4, wherein the tracking sensor is a light shielding region.