JP6924378B2 - Welding position correction method and welding equipment - Google Patents

Description

The present invention relates to a welding position correction method and a welding apparatus, and more particularly to a welding position correction method and a welding apparatus suitable for automatic welding using a welding robot.

When performing automatic welding, it is common to move the welding torch along a predetermined reference welding line. However, in actual welding work, the welding line may deviate from the reference welding line, and the deviation of the welding line is detected and the welding line is corrected before starting welding.

For example, in Patent Document 1, a method of detecting two planes forming a welded joint by a sensor provided at a working end of an arc welding robot and calculating a welding line of the welded joint where the two detected planes intersect is calculated. Is disclosed.

Further, in Patent Document 2, position coordinates are acquired by performing touch sensing at three or more places by touch sensors on both sides of the weld line of the fillet joint portion, and the position coordinates of the welding line are specified from these position coordinates. The method of doing so is disclosed.

Japanese Unexamined Patent Publication No. 5-69132 Japanese Unexamined Patent Publication No. 2008-279461

By the way, in arc welding such as fillet welding, the work may be deformed due to heat input to the work during welding, and the welding line may deviate from the reference welding line due to the deformation of the work. At that time, in the methods described in Patent Documents 1 and 2 described above, since it is premised that the touch-sensed measurement point is on the plane or the straight line of the work, when the work is deformed. There is a problem that the correct welding position (welding line) cannot be detected.

Further, in the methods described in Patent Documents 1 and 2 described above, when the welding wire is used as the touch sensor, the tip of the welding wire is generally bent, and when the welding wire rotates during touch sensing. There is also a problem that the bending direction of the welding wire at the time of touch sensing changes, and the position of the measurement point cannot be calculated correctly.

The present invention has been devised in view of such a problem, and the welding position can be corrected to an appropriate welding position even when the work is deformed or the bending direction of the welding wire is changed. It is an object of the present invention to provide a correction method and a welding apparatus.

According to the present invention, the first step of touch-sensing a plurality of points on each of the first surface and the second surface to be welded, the second step of calculating the coordinates of the touch-sensed measurement point, and the coordinates of the measurement point are used as described above. The third step of calculating the first index indicating the shape of the first surface and the second index indicating the shape of the second surface, the first error between the first index and the measurement point on the first surface, and the above. A fourth step of calculating the second error between the second index and the measurement point on the second surface, and a fifth step of determining whether the first error and the second error are less than a predetermined threshold. When the first error and the second error are less than the threshold value, the sixth step of calculating the intersection position between the first surface and the second surface based on the first index and the second index. The seventh step of correcting the intersection position calculated by the sixth step to the welding position and the measurement point for calculating the first index when the first error is equal to or greater than the threshold value are changed. (Ii) A welding position correction method is provided, which comprises an eighth step of changing a measurement point for calculating the second index when the error is equal to or greater than the threshold error.

The first index and the second index are, for example, straight lines. At this time, the number of touch sensing points in the first step may be three or more for each of the first surface and the second surface.

Further, the first index and the second index may be flat. At this time, the number of touch sensing points in the first step may be four or more for each of the first surface and the second surface.

Further, the first error and the second error may be calculated by the sum of squared errors, the sum of the absolute values of the errors, or the maximum separation distance.

Further, the eighth step may be a step of changing the position of the measurement point and recalculating the touch sensing, or reducing the number of the measurement points to recalculate the first index or the second index. It may be a step.

Further, according to the present invention, a welding robot and a control device for controlling the welding robot are provided, and the control device touch-senses a plurality of points on each of the first surface and the second surface to be welded. The coordinates of the measurement points were calculated, and the first index indicating the shape of the first surface and the second index indicating the shape of the second surface were calculated from the coordinates of the measurement points, and the first index and the first index were calculated. The first error with the measurement point on the surface and the second error between the second index and the measurement point on the second surface are calculated, and whether the first error and the second error are less than a predetermined threshold. Whether or not it is determined, and when the first error and the second error are less than the threshold value, the intersection position between the first surface and the second surface is calculated based on the first index and the second index. The measurement point for calculating the first index is changed when the first error is equal to or greater than the threshold, and the second index is calculated when the second error is equal to or greater than the threshold. A welding apparatus is provided characterized in that it is configured to change the measurement point.

According to the welding position correction method and the welding apparatus according to the present invention described above, the first index and the second index indicating the shape of the first surface by touch-sensing a plurality of locations on the first surface and the second surface constituting the base material. By calculating the second index indicating the shape of the surface, calculating the error from these indexes and the coordinates of the touch-sensed measurement point, and comparing it with the threshold value, the calculated first index and second index are the first surface and the second index. It is possible to confirm whether or not the shape of the second surface is expressed.

Therefore, even if the work is deformed or the bending direction of the welding wire changes, the welding line can be corrected based on the probable first index and second index, and the welding line can be set at an appropriate welding position. Can be corrected to.

It is an overall block diagram which shows the welding apparatus which concerns on one Embodiment of this invention. It is a flow chart which shows the welding position correction method which concerns on 1st Embodiment of this invention. It is a conceptual diagram which shows the welding position correction method when a work is deformed. An appropriate example, (c) shows an example inappropriate for correction when there are four measurement points, and (d) shows an example suitable for correction when there are four measurement points. It is a conceptual diagram which shows the welding position correction method when the bending direction of a welding wire changes. An example suitable for correction in the case is shown. It is a flow chart which shows the welding position correction method which concerns on 2nd Embodiment of this invention. It is a flow chart which shows the welding position correction method which concerns on 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6. Here, FIG. 1 is an overall configuration diagram showing a welding apparatus according to an embodiment of the present invention. FIG. 2 is a flow chart showing a welding position correction method according to the first embodiment of the present invention.

As shown in FIG. 1, the welding device 1 according to the embodiment of the present invention includes a welding robot 2 and a control device 3 for controlling the welding robot 2, and the control device 3 is shown in FIG. It is configured to control the welding robot 2 based on the flow chart.

As shown in FIG. 1, the work 4 to be welded includes, for example, a vertical plane (first surface 41) and a horizontal plane (second surface 42), and the line of intersection between the vertical plane and the horizontal plane is the welding line 43. Consists of. Such welding is generally called fillet welding.

Note that FIG. 1 illustrates the case where the first surface 41 and the second surface 42 form a T-shape, but the first surface 41 and the second surface 42 form a cross shape. A cross joint or a square joint in which the first surface 41 and the second surface 42 form an L shape may be used.

The welding robot 2 is a robot that performs arc welding including a welding torch 21 provided with a welding wire W and a robot arm 22 for three-dimensionally moving the welding torch 21. Although FIG. 1 shows a case where the welding robot 2 is arranged on the floor surface, the welding robot 2 may be a welding robot arranged so as to be able to travel on a guide rail arranged above the work 4. ..

The control device 3 is programmed to perform welding while moving the welding torch 21 along a predetermined reference welding line, which is a design welding line 43. By the way, the work 4 may be deformed by the heat input to the work 4 at the time of welding, and the actual welding line 43 may deviate from the reference welding line. Therefore, when welding the work 4, it is necessary to correct the welding line that serves as a reference for moving the welding torch 21.

The welding position correction method according to the first embodiment shown in FIG. 2 includes a first step Step 1 for touch sensing each of a plurality of locations on the first surface 41 (vertical surface) and the second surface 42 (horizontal plane) to be welded, and touch. The second step Step 2 for calculating the coordinates of the sensed measurement points P _1n and P _2n (n is an error of 1 or more) and the first index I indicating the shape of the first surface 41 from the coordinates of the _{measurement points P 1n} and P _2n. Step 3 for calculating _{the second index I 2} (second straight line E _{2 ) indicating the shape of 1} (first straight line E ₁ ) and the second surface 42, _{and measurement on the first index I 1} and the first surface 41. a fourth step Step4 of calculating a second error Err ₂ the first error Err ₁ and the second index _{I 2} between the point _{P 1n} and the measurement point _{P 2n} on the second surface 42, the first error Err ₁ and the a secondary error Err ₂ is determining whether or not a fifth step Step5 is less than the predetermined threshold value TH, if the first error Err ₁ and the second error Err ₂ is less than the threshold value TH, the first index _{I 1} and the intersections based on two indices _{I 2} and the first face 41 and second face 42 (the intersection point _P t ') and the sixth step Step6 of calculating the cross position calculated by the sixth step Step6 (intersection _P t' Step 7 and the measurement point P _{1n for calculating the first index I 1} when the first error Err ₁ is equal to or higher than the threshold TH are changed, and the second error Err ₂ is The eighth step Step 8 for changing the measurement point P _{2n for calculating the second index I 2} when the threshold value TH or more is included is included.

In the first step Step 1, touch sensing is performed on a plurality of locations on the first surface 41 (vertical surface) constituting the welding line 43, and touch sensing is performed on a plurality of locations on the second surface 42 (horizontal plane) constituting the welding line 43. It is a step. Touch sensing is performed by using the welding robot 2 to bring the tip of the welding wire W gripped by the welding torch 21 into contact with the first surface 41 and the second surface 42.

In the present embodiment, a straight line intersecting (preferably orthogonal to) the welding line 43 is used as _{the first index I 1} indicating the shape of the first surface 41. In this case, touch sensing is performed on the first surface 41 at least one redundant point on the same straight line as the two points on which the straight line can be calculated. Similarly, on the second surface 42, at least three points on the same straight line are touch-sensed.

The second step Step 2 is a step of calculating the coordinates of the touch-sensed point (measurement point). In the present specification, the measurement point on the first surface 41 _{is expressed as P 1n,} and the measurement point on the second surface 42 is expressed _{as P 2n.} Here, n means the order in which you touch sensing, first point of measurement points P _11, the second point of the measuring points P _12, third point of the measurement points shall be displayed as P _13.

Hereinafter, a case where touch sensing is performed on a straight line orthogonal to the reference welding line of the first surface 41 (vertical surface) will be described. As shown in FIG. 1, if the X-axis is set on the reference welding line, the Y-axis is set on the second surface 42 (horizontal plane), and the Z-axis is set on the first surface 41 (vertical surface), The coordinates of the point (welding point P _t ) on the reference welding line can be displayed as _{P t} = {x _t , y _t , z _t}.

_{Here, the measurement point P 11} = {x _t , y _v1 , z _t + v ₁ by touch-sensing _{the design point {x t} , y _t , z _t + v ₁ } on the first surface 41 (lead surface). _{}, And the measurement point P 12} = {x _t , y by touch-sensing _{the design point {x t} , y _t , z _t + v ₂ } on the first surface 41 (vertical face). _{v2, z} t + _{v 2}} coordinates can be obtained of the first surface 41 design of the point _{{x t} of (vertical _{plane), y t, z t +} v 3} measuring point _{P 13} by touching sensing = can be obtained coordinates of _{{x t, y v3, z} t + v 3}.

_{That is, the measurement point P 1n} = {x _t , y _vn , z _t + v _n } by touch-sensing _{the design point {x t} , y _t , z _t + v _n } on the first surface 41 (lead face). Coordinates can be obtained. In general, when the first surface 41, which is a vertical plane, is deformed, the XZ plane is curved. Therefore, _{the coordinates of the measurement point P 1n} are different from the corresponding design points in the y coordinate. It becomes.

_{Similarly, the measurement point P 2n} = {x _t , y _t + h _n , z _hn } by touch-sensing _{the design point {x t} , y _t + h _n , z _t } on the second surface 42 (horizontal plane). Coordinates can be obtained. In general, when the second surface 42, which is a horizontal plane, is deformed, the XY plane is curved. Therefore, _{the coordinates of the measurement point P 2n} are different from the corresponding design points in the z coordinate. Become.

The third step Step 3 is a step of calculating _{the first index I 1} indicating the shape of the first surface 41 _{and the second index I 2} indicating the shape of the second surface 42. _{In the present embodiment, the first straight line E 1} orthogonal to the welding line 43 is _{used as the first index I 1} indicating the shape of the first surface 41, and welding is used as _{the second index I 2} indicating the shape of the second surface 42. It is assumed that the second straight line E ₂ orthogonal to the line 43 is used.

The first straight line E ₁ can be identified by, for example, the method of least squares, using the coordinates of the measurement point P _{1n on the first surface 41.} Similarly, the second straight line E ₂ can be identified by, for example, the method of least squares, using the coordinates of the measurement point P _{2n on the second surface 42.}

In the fourth step Step 4, the first error Err _{1 between the first straight line E 1} (first index I ₁ ) and the measurement point P _1n is calculated, and the second straight line E ₂ (second index I ₂ ) and the measurement point P _{2n are calculated.} This is a step of calculating the second error Err _{2 with.} The first error Err ₁ can be obtained, for example, by the sum of error squares used in the least squares method. The first error Err ₁ is an index indicating the degree of deviation of the measurement point P _{1n from} the first straight line E ₁ , and is not limited to the sum of squared errors.

For example, the first error Err ₁ may be obtained by the sum of the absolute values of the errors between each measurement point P _1n and the first straight line E ₁ (sum of absolute error values), or the first straight line E of _{the measurement points P 1n. It} may be obtained by the distance of the measurement point farthest from 1 (maximum separation distance). Similarly, the second error Err ₂ can also be obtained from the measurement point P _2n and the second straight line E _{2 by the} sum of squared errors, the sum of the absolute error values, the maximum separation distance, and the like.

The fifth step Step 5 is a step of _{determining whether or not the first error Err 1} is less than a predetermined threshold value TH and whether or not the second error Err ₂ is less than a predetermined threshold value TH. The threshold value TH for determining the first error Err ₁ and the threshold value TH for determining the second error Err ₂ may be the same value or different values.

For example, when the first error Err ₁ is larger than the threshold value TH, _{it is predicted that the first straight line E 1} (first index I ₁ ) does not properly represent the shape of the first surface 41. When the welding point P _t is corrected based on the straight line E ₁ , the corrected welding point P _t ′ is largely deviated from the actual welding line 43.

Therefore, in the present embodiment, _{whether or not the first index I 1} and the second index I ₂ obtained in the third step Step 3 are probable, that is, whether or not the deformed shape of the work 4 is appropriately expressed. The determination is made using the first error Err ₁ and the second error Err _2. By such processing, the deviation (error) of the corrected welding line can be reduced.

In the sixth step Step 6, when the first error Err ₁ is less than the threshold value TH and the second error Err ₂ is less than the threshold value TH, the position of the intersection P _{t ′ between the first} straight line E 1 and the second straight line E ₂ is set. This is the step to calculate. Further, the seventh step Step 7 is a step of correcting the _{welding point P t} to the intersection P _{t ′.}

In the eighth step Step 8, when the first error Err ₁ is equal to or higher than the threshold TH, or when the second error Err ₂ is equal to or higher than the threshold TH, the measurement point P _{1n for calculating the first} straight line E 1 is changed, and the measurement point P 1n is changed. This is a step of changing the measurement point P _2n for calculating the second index I _2. When a straight line is used as an index as in the present embodiment, the welding points on the welding line are corrected. Therefore, it is preferable to perform the above-described processing on a plurality of points on the X-axis.

Here, FIG. 3 is a conceptual diagram showing a welding position correction method when the work is deformed, (a) is an example of inappropriate correction when there are three measurement points, and (b) is an example in which the measurement points are An example suitable for correction in the case of three points, (c) an example inappropriate for correction in the case of four measurement points, and (d) an example suitable for correction in the case of four measurement points are shown. ing. Here, for convenience of explanation, only the case of the second surface 42 (horizontal plane) will be described, but the same applies to the case of the first surface 41 (vertical surface).

FIG. 3A shows a case where the coordinates of the measurement points P ₂₁ , P ₂₂ , and P ₂₃ are calculated to calculate the second straight line E _{2 which is the second index I 2} , and the second error Err ₂ is the threshold value. The case of TH or more is shown. Therefore, as shown in the figure, the second straight line E ₂ deviates significantly from the welding line 43. In this situation when corrected welding point based on the second straight line E ₂ can not be welded to the appropriate position.

Therefore, in the present embodiment, for example, as shown in FIG. 3B, the touch sensing position is changed _{, the coordinates of the new measurement points P 21} , P ₂₂ , and P ₂₃ are calculated, and the second straight line is calculated. E ₂ may be recalculated. At this time, for example, the measurement point P _2n is brought closer to the welding line while maintaining the ratio of the offset amount (y-coordinate value) of the measurement point P _{2n to the welding line.} In this way, when _{the position of the measurement point P 2n} is changed, as shown in FIG. 2, the process of returning to the first step Step 1 is performed after the eighth step Step 8.

Considering the general deformation of the work 4 in the case of fillet welding, _{by calculating the measurement point P 2n} at a position closer to the welding line, an index indicating the shape in the vicinity of the welding line 43 can be calculated more appropriately. Can be done. Therefore, when changing the position of the measurement point P _2n , it is preferable to bring it closer to the welding line. The ratio of the offset amount (y-coordinate value) to the welding line at the measurement point P _{2n does not necessarily have to be held.}

In the above-described embodiment, three measurement points P ₂₁ , P ₂₂ , and P _{23 are used when calculating the second straight line E 2} , but they are shown in FIGS. 3 (c) and 3 (d). As described above, four measurement points P ₂₁ , P ₂₂ , P ₂₃ , and P ₂₄ may be used by adding redundant points.

As shown in FIG. 3 (c), when _{the second straight line E 2} is identified by the least squares method using _{the four measurement points P 21} , P ₂₂ , P ₂₃ , and P ₂₄ , the second error Err _It is assumed that 2 is equal to or higher than the threshold value TH. In this case, among the four measurement points P ₂₁ , P ₂₂ , P ₂₃ , and P ₂₄ , the measurement point having the largest error (for example, measurement point P ₂₄ ) is set as the error point, and the second straight line E ₂ is calculated. It may be excluded from the points. That is, _{the number of measurement points P 2n} may be reduced to recalculate the second straight line E ₂ from the three measurement points P ₂₁ , P ₂₂ , and P _23.

Thus, in the eighth step Step8, may be changed measurement point P _2n by subtracting the measurement point P _2n for calculating a second straight E ₂ is the second index I _2. In this case, although not shown, the process of returning to the third step Step 3 after the eighth step Step 8 is performed according to the flow chart shown in FIG. When this method is adopted, it is not necessary to perform touch sensing again, and the processing time can be shortened.

Although FIGS. 3 (c) and 3 (d) describe the case where the number of measurement points is four, that is, the case where there are two redundant points, the number of measurement points may be five or more. .. By increasing the number of redundant points, the number of times the measurement points are reduced can be increased. Further, when the number of measurement points becomes three as a result of reducing the number of measurement points, the welding line may be corrected by the processes shown in FIGS. 3 (a) and 3 (b).

By the way, in the case of touch sensing using the welding wire W as in the present embodiment, the tip of the welding wire W is generally curved in a predetermined direction with respect to the axis of the welding torch 21. .. If the bending direction and bending amount of the welding wire W are always constant, all the measurement points calculated by touch sensing are deflected by the same amount in the same direction, so that the welding wire W is calculated when its coordinates are calculated. It is not necessary to consider the bending direction and the amount of bending.

However, when the welding torch 21 is moved during touch sensing, tension may be generated in the welding wire W, the welding wire W may rotate, and the bending direction may change. If the bending direction of the welding wire W changes in the middle, an error will occur at the measurement point, and an appropriate index cannot be calculated.

Here, FIG. 4 is a conceptual diagram showing a welding position correction method when the bending direction of the welding wire changes, and (a) is an example inappropriate for correction when there are three measurement points, (b). Shows an example suitable for correction when there are three measurement points.

For example, as shown in FIG. 4A, the bending direction of the welding wire W in the first touch sensing and the second touch sensing is downward, whereas the bending direction of the welding wire W in the third touch sensing is downward. When the bending direction of W changes upward, when the second straight line E _{2 is calculated using the coordinates of these measurement points (for example, measurement points P 21} , P ₂₂ , P ₂₃ ), the third measurement point Since the measurement position is deviated by the amount, an appropriate second index I ₂ cannot be calculated.

In this way, when the bending direction of the welding wire W changes during touch sensing, a second straight line E ₂ (second index I ₂ ), which is inappropriate for correcting the welding line, is obtained. In step 5, it is determined whether or not the second error Err _{2 of} the second straight line E ₂ (second index I ₂ ) is less than the threshold value TH, so that even if the bending direction of the welding wire W changes, it can be easily determined. can do.

Then, in the present embodiment, when the second error Err _{2 of the second straight line E 2} (second index I ₂ ) is equal to or higher than the threshold value TH, for example, as shown in FIG. 4 (b), touch sensing. The touch sensing is repeated until the change in the bending direction of the welding wire W disappears in the middle of the process, or until the change in the bending direction of the welding wire W becomes small enough not to affect _{the second error Err 2.}

Although not shown in the flow chart of FIG. 2, when the second error Err _{2 of the second straight line E 2} (second index I ₂ ) does not become less than the threshold value TH even if the touch sensing is repeated a predetermined number of times. , The process may be stopped as a measurement error.

Further, although FIGS. 4A and 4B describe the case where the bending direction of the welding wire W changes, the case where the bending amount of the welding wire W changes (for example, the axial direction of the welding wire W). Similarly, when the tension of the welding wire W changes or when the amount of protrusion of the welding wire W from the welding torch 21 changes), the second error Err _{2 of the second straight line E 2} (second index I ₂ ) is the threshold value TH. By determining whether or not it is less than, it is possible to determine whether or not the second index I ₂ is appropriate.

_{According to the welding position correction method according to the present embodiment described above, the first index I 1} indicating the shape of the first surface 41 by touch-sensing a plurality of locations of the first surface 41 and the second surface 41 constituting the base material. _{And the second index I 2} indicating the shape of the second surface 42 is calculated, and an error (first error Err ₁ , second error Err ₂ ) _{is obtained from these indexes and the coordinates of the measurement points P 1n} and P _2n that are touch-sensed. Is calculated and compared with the threshold value TH, _{it is easily confirmed whether or not the calculated first index I 1} and the second index I ₂ represent the probable shapes of the first surface 41 and the second surface 42. be able to.

Therefore, even when the work 4 is deformed or the bending direction of the welding wire W is changed, the welding line can be corrected based on _{the probable first index I 1} and second index I _{2, and welding can be performed.} The wire can be corrected to the proper welding position.

Next, the welding position correction method according to another embodiment of the present invention will be described with reference to FIGS. 5 and 6. Here, FIG. 5 is a flow chart showing a welding position correction method according to the second embodiment of the present invention. FIG. 6 is a flow chart showing a welding position correction method according to the third embodiment of the present invention.

In the welding position correction method according to the second embodiment shown in FIG. 5, a flow of repeating index error determination from touch sensing (first step Step 1 to fifth step Step 5, eighth step Step 8) is performed on the first surface 41 (step 1). It is separated into a vertical surface) and a second surface 42 (horizontal plane). In the flow shown in FIG. 5, the flow on the first surface 41 (vertical surface) and the flow on the second surface 42 (horizontal plane) are displayed in parallel. Or the other may be processed later.

Specifically, in the welding position correction method according to the second embodiment, the coordinates of the first step Step 11 for touch-sensing a plurality of points on the first surface 41 (vertical surface) and the touch-sensed measurement point P _{1n are calculated.} The second step Step 21 and the third step Step 31 for calculating _{the first index I 1} (first straight line E ₁ ) indicating the shape of the first surface 41 from the coordinates of the _{measurement point P 1n , the first index I 1} and the measurement point P. a fourth step Step41 of calculating a first error Err ₁ and _1n, a fifth step Step51 determines whether the first error Err ₁ is less than the threshold value TH, in the case of the first error Err ₁ is equal to or more than the threshold value TH Includes an eighth step Step 81 for changing the measurement point P _1n for calculating the first index I _1.

Further, the welding position correction method according to the second embodiment includes a first step Step 12 for touch-sensing a plurality of points on the second surface 42 (horizontal plane) and a second step Step 22 for calculating the coordinates of the _{touch-sensed measurement point P 2n. Step 32 for calculating the second index I 2} (second straight line E ₂ ) indicating the shape of the second surface 42 from the coordinates of the measurement point P _2n , and the second index I ₂ and the measurement point P _2n . a fourth step Step42 of calculating a second error Err _2, a second error Err ₂ is determining whether or not a fifth step Step52 is less than the threshold value TH, in the case of the second error Err ₂ is more than the threshold value TH, the The eighth step Step 82 for changing the measurement point P _2n for calculating the two indicators I _{2 is included.}

Since the specific processing in each step is the same as the welding position correction method according to the first embodiment described above, detailed description thereof will be omitted here. In this way, by separating the flow of repeating the error determination of the index from the touch sensing into the first surface 41 (vertical surface) and the second surface (horizontal plane), the first error Err ₁ or the second error Err ₂ can be obtained. When either one becomes the threshold value TH or more, only one of the first surface 41 or the second surface 42 whose error is equal to or more than the threshold value TH needs to be touch-sensed again, and the number of touch sensing processes is reduced. This can be done, and the processing time can be shortened.

The welding position correction method according to the third embodiment shown in FIG. 6 uses _{a plane (first plane F 1} ) showing the shape of the first surface 41 (vertical surface) as the first _{index I 1} and the second index. As I _{2 , a plane (second plane F 2} ) showing the shape of the second plane 42 (horizontal plane) is used. The basic flow is the same as the welding position correction method according to the first embodiment described above.

When using a planar as an index, the measurement point P _1n including redundant point of at least one point on a three-point flush capable of calculating a _plane, it is necessary to P _2n. The first plane F ₁ and the second plane F ₂ can be calculated by, for example, the least squares method. Further, as the first error Err ₁ and the second error Err ₂ , the sum of squares of errors when approximating the first plane F ₁ and the second plane F _{2 can be used.} Further, the intersection of the first index I ₁ (first plane F ₁ ) and the second index I ₂ (second plane F ₂ ) can be calculated as the line of intersection L'.

In this way, even when a plane is used as an index indicating the shapes of the first surface 41 and the second surface 42, a more probable index can be calculated by determining the error from the measurement point. , The welding line L can be corrected to an appropriate welding position (intersection line L').

Although not shown, in the welding position correction method according to the third embodiment, the first surface 41 is a flow (first step Step 1, fifth step Step 5, eighth step Step 8) in which the error determination of the index is repeated from the touch sensing. It may be separated into a (leading surface) and a second surface (horizontal plane).

It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 Welding device 2 Welding robot 3 Control device 4 Work 21 Welding torch 22 Robot arm 41 First surface 42 Second surface 43 Welding line W Welding wire Step1, Step11, Step12 First step Step2, Step21, Step22 Second step Step3, Step31 , Step32 3rd step Step4, Step41, Step42 4th step Step5, Step51, Step52 5th step Step6 6th step Step7 7th step Step8, Step81, Step82 8th step

Claims (9)

The first step of touch-sensing multiple points on each of the first and second surfaces to be welded,
The second step of calculating the coordinates of the touch-sensed measurement points,
A third step of calculating a first index indicating the shape of the first surface and a second index indicating the shape of the second surface from the coordinates of the measurement point, and
The fourth step of calculating the first error between the first index and the measurement point on the first surface and the second error between the second index and the measurement point on the second surface, and
The fifth step of determining whether or not the first error and the second error are less than a predetermined threshold value, and
A sixth step of calculating the intersection position of the first surface and the second surface based on the first index and the second index when the first error and the second error are less than the threshold value.
The seventh step of correcting the intersection position calculated by the sixth step to the welding position, and
Eighth step of changing the measurement point for calculating the first index when the first error is equal to or greater than the threshold value and changing the measurement point for calculating the second index when the second error is equal to or greater than the threshold value. When,
A welding position correction method comprising. The welding position correction method according to claim 1, wherein the first index and the second index are straight lines. The welding position correction method according to claim 2, wherein the number of touch sensing points in the first step is three or more for each of the first surface and the second surface. The welding position correction method according to claim 1, wherein the first index and the second index are flat surfaces. The welding position correction method according to claim 4, wherein the number of touch sensing points in the first step is four or more points on each of the first surface and the second surface. The welding position correction method according to claim 1, wherein the first error and the second error are calculated by any of the sum of squared errors, the sum of absolute error values, and the maximum separation distance. The welding position correction method according to claim 1, wherein the eighth step is a step of changing the position of the measurement point and re-touch sensing. The welding position correction method according to claim 1, wherein the eighth step is a step of reducing the number of measurement points to recalculate the first index or the second index. A welding robot and a control device for controlling the welding robot are provided.
The control device touch-senses a plurality of points on each of the first surface and the second surface to be welded, calculates the coordinates of the touch-sensed measurement points, and indicates the shape of the first surface from the coordinates of the measurement points. The index and the second index indicating the shape of the second surface are calculated, and the first error between the first index and the measurement point on the first surface and the second index and the measurement point on the second surface are obtained. The second error is calculated, it is determined whether or not the first error and the second error are less than a predetermined threshold, and when the first error and the second error are less than the threshold, the first error is calculated. Based on the index and the second index, the intersection position between the first surface and the second surface is calculated and corrected to the position to be welded, and the first index is calculated when the first error is equal to or greater than the threshold. The measurement point to be calculated is changed, and the measurement point for calculating the second index is changed when the second error is equal to or greater than the threshold value.
Welding equipment characterized by that.

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