JP2020082287A - Welding robot - Google Patents

Abstract

To provide a welding robot which does not cause welding defects, and obtains finely finished welding traces, and thus, contributes to quality improvement of products.SOLUTION: A welding robot 1 includes: a sensor 3; and a controller 4 which recognizes a weld line Lw on the basis of a signal of the sensor 3. The controller 4 automatically arranges a plurality of teaching points Pt on the weld line Lw, and moves a welding tool 5 so as to follow the teaching points Pt. Further, the controller 4 specifies a point where a code of a second derivative changes in a numerical expression representing the weld line Lw, as an inflection point Pi of the weld line Lw, and arranges the teaching points Pt on the inflection points Pi.SELECTED DRAWING: Figure 6

Description

The present invention relates to a welding robot.

Conventionally, a welding robot that moves a welding tool so as to follow a teaching point is known. In order to perform welding with such a welding robot, an operator needs to input a teaching point. Therefore, in such a welding robot, it takes time and effort to input the teaching point.

Therefore, a welding robot that automatically arranges a plurality of teaching points on the welding line and moves the welding tool so as to follow the teaching points has been proposed (see Patent Documents 1 and 2). However, even with such a welding robot, if the teaching points cannot be appropriately arranged, a welding defect will occur or a welding mark will be lost. For example, if the number of teaching points arranged on a complicated welding line is small, there is a problem that the trajectory of the welding tool deviates from the welding line and welding failure occurs. Further, even if there are too many teaching points arranged on a simple welding line, there is a problem that the trajectory of the welding tool is jerky and the welding trace becomes unusable.

JP 2004-261878 A International Publication No. 2015/146180

(EN) Provided is a welding robot which does not cause welding defects and has a clean weld mark, which eventually contributes to improvement of product quality.

The first invention is
A sensor,
A controller that recognizes a welding line based on the signal of the sensor,
In a welding robot in which the controller automatically arranges a plurality of teaching points on the welding line and moves a welding tool so as to follow the teaching points,
The controller identifies a point at which a sign of a second derivative of a mathematical expression representing the welding line changes as an inflection point of the welding line, and arranges the teaching point on the inflection point. ..

A second invention is the welding robot according to the first invention,
Set a reference line passing through one of the teaching points,
Set a boundary line extending in parallel to the reference line with a predetermined distance,
The controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. , Things.

A third invention is the welding robot according to the first invention,
Set a circular boundary line with a predetermined radius centered on one of the teaching points,
The controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. , Things.

A fourth invention is the welding robot according to the first invention,
Set a reference line passing through one of the teaching points,
An elliptical boundary line is set with a long side having a predetermined length in a direction parallel to the reference line and a short side having a predetermined length in a direction perpendicular to the reference line around the teaching point. Then
The controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. , Things.

A fifth invention is a welding robot according to any one of the second to fourth inventions,
The controller arranges the teaching point on at least one inflection point in a high density portion of the inflection point, even if the area does not exceed the boundary line.

A sixth invention is a welding robot according to any one of the second to fourth inventions,
The controller sets the boundary line again at a position corresponding to the density transition of the inflection point, and arranges the teaching point on the inflection point in a region beyond the boundary line.

In the welding robot according to the first aspect of the present invention, the controller identifies a point at which the sign of the second derivative of the mathematical expression representing the welding line changes as an inflection point of the welding line, and sets a teaching point on the inflection point. Deploy. According to such a welding robot, since the trajectory of the welding tool does not easily deviate from the welding line, welding defects do not occur. In addition, the trajectory of the welding tool is not jerky, so the welding trace is clean. As a result, product quality can be improved.

In the welding robot according to the second aspect of the present invention, a reference line passing through one teaching point is set, and a boundary line that extends in parallel with the reference line is set. Then, the controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. According to such a welding robot, the trajectory of the welding tool becomes smooth without being caught by the fine distortion of the welding line, so that the welding trace becomes clearer. Furthermore, since the number of teaching points is reduced, the calculation load on the controller can be reduced.

In the welding robot according to the third aspect of the present invention, a circular boundary line having a predetermined radius is set around one teaching point. Then, the controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. According to such a welding robot, the trajectory of the welding tool becomes smooth without being caught by the fine distortion of the welding line, so that the welding trace becomes clearer. Furthermore, since the number of teaching points is reduced, the calculation load on the controller can be reduced.

In the welding robot according to the fourth aspect of the present invention, a reference line passing through one teaching point is set, and a direction parallel to the reference line with the teaching point as a center is a long side of a predetermined length, which is the reference line. An elliptical boundary line whose vertical direction is the short side of a predetermined length is set. Then, the controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. According to such a welding robot, the trajectory of the welding tool becomes smooth without being caught by the fine distortion of the welding line, so that the welding trace becomes clearer. Furthermore, since the number of teaching points is reduced, the calculation load on the controller can be reduced.

In the welding robot according to the fifth aspect, the controller arranges the teaching point on at least one inflection point in the high-density portion of the inflection point even if the area does not exceed the boundary line. According to such a welding robot, even if there is a complicated portion in the welding line, the welding tool appropriately follows, so it is possible to reliably prevent defective welding.

In the welding robot according to the sixth aspect of the invention, the controller sets the boundary line again at a position corresponding to the density transition of the inflection point, and arranges the teaching point on the inflection point in the area beyond the boundary line. According to such a welding robot, since the welding tool appropriately follows any welding line, it is possible to reliably prevent defective welding.

The figure which shows the welding robot which concerns on 1st embodiment. The figure which shows the tool for welding. The figure which shows each process at the time of welding. The figure which shows the recognition process of a welding line. The figure which shows the identification process of an inflection point. The figure which shows the arrangement|positioning process of a teaching point. The figure which shows the welding process by the welding tool. The figure which shows the placement process of the teaching point of the welding robot which concerns on 2nd embodiment. The figure which shows the placement process of the teaching point of the welding robot which concerns on 3rd embodiment. The figure which shows the placement process of the teaching point of the welding robot which concerns on 4th embodiment. The figure which shows the placement process of the teaching point of the welding robot which concerns on 5th embodiment. The figure which shows the placement process of the teaching point of the welding robot which concerns on 6th embodiment.

The technical idea disclosed in the present application can be applied to other welding robots in addition to the welding robot 1 described below.

First, the welding robot 1 according to the first embodiment will be described with reference to FIG.

The welding robot 1 is mainly composed of a manipulator 2.

The manipulator 2 includes a body 21 and a plurality of arms 22, 23, 24. The body 21 is supported by the mount base 25 and is rotatable. The arm 22 is supported by the body 21 and is rotatable. Further, the arm 23 is supported by the arm 22 and is rotatable and rotatable. The arm 24 is supported by the arm 23 and is rotatable and rotatable. Thus, the manipulator 2 moves the welding tools 5 described later by moving them simultaneously or independently.

In addition, the welding robot 1 includes a sensor 3 and a controller 4.

The sensor 3 is attached to the arm 24. The sensor 3 irradiates the work W with a sheet-shaped laser light (see FIG. 2). Then, the sensor 3 receives the reflected light returned from the work W and transmits a signal corresponding to the reflected light to the controller 4. More specifically, the sensor 3 receives the reflected light returned from the work W and transmits a signal corresponding to the time and the angle at which the reflected light returns to the controller 4. The type and characteristics of the sensor 3 are not limited.

The controller 4 is placed near the manipulator 2. The controller 4 recognizes the shape of the work W based on the signal of the sensor 3. Then, the controller 4 recognizes the characteristic portion of the work W represented as the two-dimensional or three-dimensional information as the welding line Lw. That is, the controller 4 recognizes the welding line Lw based on the signal of the sensor 3. After that, the controller 4 automatically arranges a plurality of teaching points Pt on the welding line Lw and moves the welding tool 5 so as to follow the teaching points Pt. The method of arranging the teaching point Pt will be described later.

Next, the welding tool 5 will be described with reference to FIG.

The welding tool 5 includes a laser welder 51 and an arc welder 52.

The laser welding machine 51 is composed of an oscillating section 51a and a condensing section 51b. The laser welding machine 51 narrows the beam diameter of the laser beam 5L using the oscillation part 51a as a light source at the condensing part 51b, and melts and joins the abutted part of the work W by its thermal energy. Since laser welding has a small diameter at the heat input portion, there is an advantage that the butt portion can be deeply melted and joined. Further, the laser welding has an advantage that the heat distortion of the work W can be suppressed because the heat input amount is relatively small.

The arc welder 52 includes a wire supply unit 52a, a gas supply unit 52b, and a torch unit 52c. The arc welding machine 52 uses the hot wire sent from the wire supply part 52a to the torch part 52c as an electrode to generate the arc 5A, and the thermal energy of the arc 5A melts and joins the butted part of the work W. Further, the arc welder 52 prevents the molten metal from oxidizing by surrounding the arc 5A with a shield gas (inert gas: argon gas or the like) 5G sent from the gas supply portion 52b to the torch portion 52c. In addition, since the arc welding can supply the hot wire to the molten metal as a filler material, there is an advantage that even if the gap between the butted portions is large, the gap can be filled and joined. In addition, the arc welding has an advantage that the heat input portion has a relatively large diameter and thus has a large margin for the groove shape and the like, and the welding trace B is clean.

In addition, the main welding tool 5 causes the laser irradiation by the laser welding machine 51 to precede and the arc discharge by the arc welding machine 52 to follow. However, the welding tool 5 may be one that causes the arc discharge by the arc welder 52 to precede and the laser irradiation by the laser welder 51 to follow. The output of laser irradiation by the laser welding machine 51 and the output of arc discharge by the arc welding machine 52 are appropriately set by an experiment using the material and thickness of the work W, welding speed, etc. as parameters. Further, the target point of laser irradiation by the laser welding machine 51 and the target point of arc discharge by the arc welding machine 52 are appropriately set by experiments using the material and thickness of the work W, welding speed, etc. as parameters. Further, the relative distance between the laser irradiation target point of the laser welding machine 51 and the arc discharge target point of the arc welding machine 52 is appropriately set by an experiment using the material and thickness of the work W, the welding speed and the like as parameters. It

Next, each step during welding will be described with reference to FIG. Here, the description will be complemented with reference to FIGS. 4 to 7. 4 to 7 are enlarged views (B) of the predetermined range R in the perspective view (A) viewed from the direction of arrow V.

In step S1, the welding robot 1 starts the process of recognizing the welding line Lw. More specifically, the controller 4 operates the manipulator 2 and moves the sensor 3 along a predetermined trajectory. As a result, the controller 4 recognizes the shape of the work W immediately below the track. In this way, the controller 4 detects the abutting portion of the work W and recognizes it as the welding line Lw (see FIG. 4).

In step S2, the welding robot 1 starts the process of identifying the inflection point Pi. Specifically, the controller 4 expresses the welding line Lw by a mathematical expression, and second-order differentiates the mathematical expression to calculate a second derivative. Thereby, the controller 4 grasps the change rate of the inclination of the tangent line Lt in this mathematical expression. In this way, the controller 4 detects the point at which the rate of change of the slope becomes zero (the point at which the sign changes) and specifies it as the inflection point Pi (see FIG. 5).

In step S3, the welding robot 1 starts the process of placing the teaching point Pt. Specifically, the controller 4 identifies the start point Ps and the end point Pe of the welding line Lw. Then, the controller 4 arranges the teaching points Pt on all the inflection points Pi including the start point Ps and the end point Pe of the welding line Lw. In this way, the controller 4 arranges the teaching points Pt at all positions where the bending direction of the welding line Lw changes in addition to the starting point Ps and the end point Pe of the welding line Lw (see FIG. 6).

Then, in step S4, the welding robot 1 starts the welding process using the welding tool 5. Specifically, the controller 4 performs laser irradiation by the laser welding machine 51 and arc discharge by the arc welding machine 52. Then, the controller 4 operates the manipulator 2, moves the laser welding machine 51 and the arc welding machine 52 so that the teaching point Pt is successively traced from the starting point Ps of the welding line Lw and finally passes the ending point Pe. In this way, the main welding robot 1 melts and joins the abutted portions of the work W (see FIG. 7).

As described above, in the present welding robot 1, the controller 4 identifies the point at which the sign of the second derivative of the mathematical expression representing the welding line Lw changes as the inflection point Pi of the welding line Lw, and determines the inflection point Pi. The teaching point Pt is arranged above. According to the welding robot 1, since the trajectory of the welding tool 5 (which is the laser welding machine 51 and the arc welding machine 52 in the main welding robot 1) is hard to deviate from the welding line Lw, welding defects do not occur. In addition, since the trajectory of the welding tool 5 is not jerky, the welding trace B becomes clean. As a result, product quality can be improved.

Next, the welding robot 1 according to the second embodiment will be described with reference to FIG. Here, the process of arranging the teaching point Pt will be focused on and described. Note that FIG. 8 also shows an enlarged view (B) of the predetermined range R in the perspective view (A) as seen from the direction of the arrow V.

The welding robot 1 according to the second embodiment, like the welding robot 1 according to the first embodiment, melts and joins the abutting portion of the work W through each process (see FIG. 3 ).

In step S3, the main welding robot 1 starts the process of placing the teaching point Pt. Specifically, the controller 4 identifies the start point Ps and the end point Pe of the welding line Lw. Further, the controller 4 sets a reference line Lr extending in the welding direction of the work W through a predetermined teaching point Pt, and at the same time sets a boundary line Lb extending in parallel with the reference line Lr with a predetermined distance d. .. Then, the controller 4 arranges the teaching point Pt on the inflection point Pi in the region beyond the boundary line Lb, including the start point Ps and the end point Pe of the welding line Lw. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area that does not exceed the boundary line Lb, but does not arrange the teaching point Pt on the inflection point Pi in the area that exceeds the boundary line Lb. Are arranged (see FIG. 8).

To describe in more detail the step of arranging the teaching point Pt, first, the controller 4 sets a reference line Lr extending in the welding direction of the workpiece W through the start point Ps, and at the same time, sets a predetermined distance d with respect to the reference line Lr. A boundary line Lb extending in parallel is also set. Then, the controller 4 arranges the teaching point Pt only on the first inflection point Pi in the region beyond the boundary line Lb, including the starting point Ps and the ending point Pe of the welding line Lw. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area not exceeding the boundary line Lb, but on the first inflection point Pi in the area exceeding the boundary line Lb. Only the teaching point Pt is arranged.

After that, the controller 4 sets a new reference line Lr passing through the first teaching point Pt arranged in a region beyond the boundary line Lb and a boundary line Lb parallel to the reference line Lr. Similarly, the teaching point Pt is arranged only on the first inflection point Pi in the area that exceeds the boundary line Lb. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area not exceeding the boundary line Lb, but on the first inflection point Pi in the area exceeding the boundary line Lb. Only the teaching point Pt is arranged. Then, this is repeated until the end point Pe is reached.

As described above, in the main welding robot 1, the reference line Lr passing through one teaching point Pt is set, and the boundary line Lb extending in parallel with the reference line Lr at a predetermined distance d is set. Then, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area that does not exceed the boundary line Lb, and sets the teaching point Pt on the inflection point Pi in the area that exceeds the boundary line Lb. Deploy. According to the welding robot 1, the trajectory of the welding tool 5 (which is the laser welding machine 51 and the arc welding machine 52 in the main welding robot 1) is smooth without being caught by the fine distortion of the welding line Lw. , The welding trace B becomes clearer. Further, since the number of teaching points Pt is reduced, the calculation load on the controller 4 can be suppressed.

Next, the welding robot 1 according to the third embodiment will be described with reference to FIG. Here, too, the process of arranging the teaching points Pt will be focused and described. Note that FIG. 9 also shows an enlarged view (B) of the predetermined range R in the perspective view (A) viewed from the direction of the arrow V.

The welding robot 1 according to the third embodiment, like the welding robot 1 according to the first embodiment, melts and joins the abutted portion of the work W through each process (see FIG. 3 ).

In step S3, the main welding robot 1 starts the process of placing the teaching point Pt. Specifically, the controller 4 identifies the start point Ps and the end point Pe of the welding line Lw. Further, the controller 4 sets a circular boundary line Lb having a predetermined radius r around the predetermined teaching point Pt. Then, the controller 4 arranges the teaching point Pt on the inflection point Pi in the region beyond the boundary line Lb, including the start point Ps and the end point Pe of the welding line Lw. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area that does not exceed the boundary line Lb, but does not arrange the teaching point Pt on the inflection point Pi in the area that exceeds the boundary line Lb. Are arranged (see FIG. 9).

The arrangement process of the teaching points Pt will be described in more detail. First, the controller 4 sets a circular boundary line Lb having a predetermined radius r centered on the starting point Ps. Then, the controller 4 arranges the teaching point Pt only on the first inflection point Pi in the region beyond the boundary line Lb, including the starting point Ps and the ending point Pe of the welding line Lw. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area not exceeding the boundary line Lb, but on the first inflection point Pi in the area exceeding the boundary line Lb. Only the teaching point Pt is arranged.

After that, the controller 4 sets a new circular boundary line Lb centered on the first teaching point Pt arranged in a region beyond the boundary line Lb. Similarly, the teaching point Pt is arranged only on the first inflection point Pi in the area that exceeds the boundary line Lb. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area not exceeding the boundary line Lb, but on the first inflection point Pi in the area exceeding the boundary line Lb. Only the teaching point Pt is arranged. Then, this is repeated until the end point Pe is reached.

As described above, in the main welding robot 1, the circular boundary line Lb having the predetermined radius r is set around the one teaching point Pt. Then, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area that does not exceed the boundary line Lb, and sets the teaching point Pt on the inflection point Pi in the area that exceeds the boundary line Lb. Deploy. According to the welding robot 1, the trajectory of the welding tool 5 (which is the laser welding machine 51 and the arc welding machine 52 in the main welding robot 1) is smooth without being caught by the fine distortion of the welding line Lw. , The welding trace B becomes clearer. Further, since the number of teaching points Pt is reduced, the calculation load on the controller 4 can be suppressed.

Next, a welding robot 1 according to the fourth embodiment will be described with reference to FIG. Here, too, the process of arranging the teaching points Pt will be focused and described. Note that FIG. 10 also shows an enlarged view (B) of the predetermined range R in the perspective view (A) seen from the direction of the arrow V.

The welding robot 1 according to the fourth embodiment, like the welding robot 1 according to the first embodiment, melts and joins the abutted portion of the work W through each process (see FIG. 3 ).

In step S3, the main welding robot 1 starts the process of placing the teaching point Pt. Specifically, the controller 4 identifies the start point Ps and the end point Pe of the welding line Lw. Further, the controller 4 sets a reference line Lr extending in the welding direction of the work W through a predetermined teaching point Pt, and at the same time, a direction parallel to the reference line Lr centering on the teaching point Pt is a predetermined length x. The elliptical boundary line Lb having the short side of the predetermined length y in the direction perpendicular to the reference line Lr. Then, the controller 4 arranges the teaching point Pt on the inflection point Pi in the region beyond the boundary line Lb, including the start point Ps and the end point Pe of the welding line Lw. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area that does not exceed the boundary line Lb, but does not arrange the teaching point Pt on the inflection point Pi in the area that exceeds the boundary line Lb. Are arranged (see FIG. 10).

The arrangement process of the teaching point Pt will be described in more detail. First, the controller 4 sets a reference line Lr extending in the welding direction of the work W through the starting point Ps, and at the same time, with respect to the reference line Lr centered on the teaching point Pt. Then, an elliptical boundary line Lb whose parallel direction is the long side of the predetermined length x and whose direction perpendicular to the reference line Lr is the short side of the predetermined length y is set. Then, the controller 4 arranges the teaching point Pt only on the first inflection point Pi in the region beyond the boundary line Lb, including the starting point Ps and the ending point Pe of the welding line Lw. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area not exceeding the boundary line Lb, but on the first inflection point Pi in the area exceeding the boundary line Lb. Only the teaching point Pt is arranged.

After that, the controller 4 sets a new reference line Lr passing through the first teaching point Pt arranged in a region exceeding the boundary line Lb and a new elliptical boundary line Lb centering on the teaching point Pt. To do. Similarly, the teaching point Pt is arranged only on the first inflection point Pi in the area that exceeds the boundary line Lb. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area not exceeding the boundary line Lb, but on the first inflection point Pi in the area exceeding the boundary line Lb. Only the teaching point Pt is arranged. Then, this is repeated until the end point Pe is reached.

As described above, in the main welding robot 1, the reference line Lr passing through one teaching point Pt is set, and the direction parallel to the reference line Lr about the teaching point Pt is the long side of the predetermined length x. Then, an elliptical boundary line Lb having a short side of a predetermined length y in a direction perpendicular to the reference line Lr is set. Then, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area that does not exceed the boundary line Lb, and sets the teaching point Pt on the inflection point Pi in the area that exceeds the boundary line Lb. Deploy. According to the welding robot 1, the trajectory of the welding tool 5 (which is the laser welding machine 51 and the arc welding machine 52 in the main welding robot 1) is smooth without being caught by the fine distortion of the welding line Lw. , The welding trace B becomes clearer. Further, since the number of teaching points Pt is reduced, the calculation load on the controller 4 can be suppressed.

Next, the welding robot 1 according to the fifth embodiment will be described with reference to FIG. The welding robot 1 according to the fifth embodiment is a welding robot 1 according to the second embodiment to which a specific technical idea is applied. However, it is also possible to apply to the welding robot 1 according to the third embodiment and the fourth embodiment.

The welding robot 1 according to the fifth embodiment, like the welding robot 1 according to the second embodiment, melts and joins the abutting portion of the work W through each process (see FIG. 3 ).

In step S3, the main welding robot 1 starts the process of placing the teaching point Pt. The controller 4 arranges the teaching point Pt on the inflection point Pi in the area beyond the boundary line Lb including the start point Ps and the end point Pe of the welding line Lw. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area that does not exceed the boundary line Lb, but does not arrange the teaching point Pt on the inflection point Pi in the area that exceeds the boundary line Lb. Are arranged (see FIG. 11).

At the same time, the controller 4 recognizes the distribution of the inflection points Pi. The controller 4 calculates the density of the inflection points Pi for each range divided by a predetermined distance, and grasps the high density portion D of the inflection points Pi. After that, the controller 4 arranges the teaching point Pt on at least one inflection point Pi in the high density portion D regardless of whether or not the boundary line Lb is crossed. For example, the teaching point Pt is arranged on the inflection point Pi closest to the center in the high density portion D.

As described above, in the main welding robot 1, the controller 4 teaches the teaching point Pt on at least one inflection point Pi in the high-density portion D of the inflection point Pi even if the area does not exceed the boundary line Lb. To place. According to the welding robot 1, the welding tool 5 (the laser welding machine 51 and the arc welding machine 52 in the main welding robot 1) appropriately follows even if there is a complicated portion on the welding line Lw. It is possible to reliably prevent defective welding.

Next, the welding robot 1 according to the sixth embodiment will be described with reference to FIG. The welding robot 1 according to the sixth embodiment is a welding robot 1 according to the second embodiment to which a specific technical idea is applied. However, it is also possible to apply to the welding robot 1 according to the third embodiment and the fourth embodiment.

The welding robot 1 according to the sixth embodiment, like the welding robot 1 according to the second embodiment, melts and joins the abutted portion of the work W through each process (see FIG. 3 ).

In step S3, the main welding robot 1 starts the process of placing the teaching point Pt. The controller 4 arranges the teaching point Pt on the inflection point Pi in the area beyond the boundary line Lb including the start point Ps and the end point Pe of the welding line Lw. In other words, the controller 4 does not arrange the teaching point Pt on the inflection point Pi in the area that does not exceed the boundary line Lb, but does not arrange the teaching point Pt on the inflection point Pi in the area that exceeds the boundary line Lb. Are arranged (see FIG. 12).

At the same time, the controller 4 recognizes the distribution of the inflection points Pi. The controller 4 calculates the density of the inflection points Pi for each range divided by a predetermined distance, and grasps the density transition of the inflection points Pi. After that, the controller 4 increases the predetermined distance d where the density of the inflection points Pi is high, and decreases the predetermined distance d where the density of the inflection points Pi is low, and then exceeds the boundary line Lb. The teaching point Pt is arranged on the inflection point Pi of the area. At this time, the value of the predetermined distance d is not limited. In addition, when applied to the third embodiment, the predetermined radius r is changed, and when applied to the fourth embodiment, the predetermined length x and the predetermined length y are changed in the same manner, and then the boundary is changed. The teaching point Pt is arranged on the inflection point Pi in the area beyond the line Lb.

As described above, in the main welding robot 1, the controller 4 newly sets the boundary line Lb at a position corresponding to the density transition of the inflection point Pi and sets it on the inflection point Pi in the area beyond the boundary line Lb. The teaching point Pt is arranged. According to the welding robot 1, since the welding tool 5 (the laser welding machine 51 and the arc welding machine 52 in the main welding robot 1) appropriately follow every welding line Lw, it is possible to prevent welding failure. It is possible to surely prevent it.

1 Welding Robot 2 Manipulator 3 Sensor 4 Controller 5 Welding Tool 51 Laser Welder 52 Arc Welder B Welding Trace Lb Boundary Lw Welding Line Pi Inflection Point Pt Teaching Point W Work

Claims (6)

A sensor,
A controller that recognizes a welding line based on the signal of the sensor,
In a welding robot in which the controller automatically arranges a plurality of teaching points on the welding line and moves a welding tool so as to follow the teaching points,
The controller identifies a point at which a sign of a second derivative of a mathematical expression representing the welding line changes as an inflection point of the welding line, and arranges the teaching point on the inflection point. And a welding robot. Set a reference line passing through one of the teaching points,
Set a boundary line extending in parallel to the reference line with a predetermined distance,
The controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. The welding robot according to claim 1, wherein: Set a circular boundary line with a predetermined radius centered on one of the teaching points,
The controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. The welding robot according to claim 1, wherein: Set a reference line passing through one of the teaching points,
An elliptical boundary line is set with a long side having a predetermined length in a direction parallel to the reference line and a short side having a predetermined length in a direction perpendicular to the reference line around the teaching point. Then
The controller does not arrange the teaching point on the inflection point in the area not exceeding the boundary line, but arranges the teaching point on the inflection point in the area exceeding the boundary line. The welding robot according to claim 1, wherein: 3. The controller arranges the teaching point on at least one inflection point in a high density portion of the inflection point even if the controller does not exceed the boundary line. The welding robot according to claim 4. The controller sets the boundary line again at a position according to the density transition of the inflection point, and arranges the teaching point on the inflection point in a region beyond the boundary line. The welding robot according to any one of claims 2 to 4.

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