JPH10193118A - Position correcting method for displacement sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance precision in correcting the position of a displacement sensor by detecting a three-dimensional distance from a welding torch using a reference sample divided into a high and a low planar part by a difference in level. SOLUTION: A displacement sensor 1 and a welding torch 2 are arranged at a prescribed position on the low planar part of a reference sample 9, with the supporting part lowered; the output of the position sensor 1, with the torch 2 in contact with the sample face, is determined to be a vertical distance Zp. Then, the displacement sensor 1 and the welding torch 2 are elevated vertically by Z1, horizontally moved linearly toward the high planar part of the sample 9, and further elevated if the torch 2 first comes into contact with the difference in level of the sample 9; the moving quantity of the sensor 1 until it reaches the difference in level is determined to be a horizontal distance Xp. In addition, with the sensor 1 reaching the difference in level first, the horizontal movement is continued, making a distance Xp for the torch 2 to come into contact with the difference in level. After that, the two are rotated at an angle of 90 deg., with the similar process applied, so that a horizontal distance Yp is determined orthogonally crossing Xp. The distance Xp, Yp, Zp thus determined is made the distance between the sensor 1 and the torch 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calibrating the position of a displacement sensor used in a shape measuring device for measuring the shape of an object.

[0002]

2. Description of the Related Art Generally, when welding a fillet in a groove using a welding torch, in order to form a high-quality weld bead, a position to be welded in a region to be welded of a material to be welded and It is necessary to accurately measure the cross-sectional shape at that position. For this reason, various shape measuring apparatuses have been conventionally proposed. For example, Japanese Patent Application Laid-Open No. 2-92458 describes an apparatus for applying a sensing voltage to a welding torch and measuring the shape of a welded portion using the welding torch itself as a sensor. Also, Japanese Patent Application Laid-Open No. 3-52774
Japanese Patent Laid-Open Publication No. H11-15064 discloses an apparatus in which a non-contact displacement sensor is provided near a welding torch to recognize the cross-sectional shape of a material to be welded and improve detection accuracy and reliability of a welding position.

[0003]

However, in the apparatus described in Japanese Patent Application Laid-Open No. 2-92458, the measurement result is affected by the condition of the welding wire at the tip of the torch, and the welding wire is bent or welded. If foreign matter adheres to the surface, the welding target area is erroneously detected, and the welding position cannot be detected. Further, in the device described in JP-A-3-52774, although the reliability of the measurement can be improved, when the displacement sensor can be attached or detached, or the position of the displacement sensor to be attached according to the object is changed. If changed, or if the welding torch or the displacement sensor collides with the target, the positional relationship between the welding torch and the displacement sensor will be changed, and accurate shape measurement cannot be performed. Was gone.

An object of the present invention is to provide a displacement sensor position calibration method capable of accurately detecting the positional relationship between a welding torch and a displacement sensor even when the positional relationship has changed. It is in.

[0005]

FIG. 1 shows an embodiment of the present invention.
6, the displacement sensor 1 that measures the distance to the object 3 in a non-contact manner is rotatably supported by a support unit in a three-dimensional and vertical plane, and the displacement sensor 1 Attached to a support portion near the welding torch 2 capable of measuring the distance of the object 3 and applied to a position calibration method of a displacement sensor in a shape measuring device for measuring the planar shape of the object 3 by the displacement sensor 1 and the welding torch 2, and the step 9C is used. While moving the welding torch 2 and the displacement sensor 1 in a direction parallel to the low plane portion 9B, the step 9C of the reference sample 9 having the divided high plane portion 9A and low plane portion 9B is moved.
The above-mentioned object is achieved by measuring the distance between the welding torch 2 and the displacement sensor 1 based on the detection result.

According to a second aspect of the present invention, the displacement sensor 1 and the welding torch 2 are positioned at an initial position above the low plane portion 9B of the reference sample 9, and the support portion is lowered by a predetermined distance in a direction perpendicular to the reference sample 9. Then, the welding torch 2 is brought into contact with the low plane portion 9B, the output of the displacement sensor 1 at the time of the contact is detected as a vertical distance Zp, and the support portion is raised in the vertical direction by a predetermined distance Z1. When the welding torch 2 moves in a horizontal direction linearly with respect to the reference sample 9 toward 9A, and the welding torch 2 comes into contact with the step 9C first, the support portion is further raised and the support portion is linearly moved in the horizontal direction. Then, the displacement L of the supporting portion from when the welding torch 2 contacts the step 9C to when the displacement sensor 1 detects the step 9C is detected as a horizontal distance Xp, and the displacement sensor 1 detects the step 9C first. if you did this The support portion is further linearly moved in the horizontal direction, and the displacement L of the support portion from when the displacement sensor 1 detects the step 9C to when the welding torch 2 contacts the step 9C is detected as the horizontal distance Xp. I do. According to a third aspect of the present invention, in the second aspect of the present invention, the support portion is rotated by 90 degrees around its axis, and the horizontal distance Yp in the horizontal direction orthogonal to the horizontal direction is further detected by the same procedure.

According to a fourth aspect of the present invention, the displacement sensor 1 and the welding torch 2 are positioned at an initial position above the low plane portion 9B of the reference sample 9, and the support portion is lowered by a predetermined distance in a direction perpendicular to the reference sample 9. Then, the welding torch 2 is brought into contact with the low plane portion 9B, the output of the displacement sensor 1 at the time of contact is detected as a vertical distance Zp, and the supporting portion is raised in the vertical direction by a predetermined distance Z1 and at a predetermined angle with respect to the vertical axis. θ, and then the support portion is linearly moved in the horizontal direction with respect to the reference sample 9 toward the high plane portion 9A. If the welding torch 2 contacts the step 9C first, the support portion is further raised. At the same time, the support portion is moved linearly in the horizontal direction, and after the welding torch 2 comes into contact with the step 9C, the displacement sensor 1 moves to the step 9C.
, The horizontal distance Xp is detected based on the movement amount L of the support portion until the displacement is detected, and when the displacement sensor 1 detects the step 9C first, the support portion is further linearly moved in the horizontal direction, The horizontal distance Xp is detected based on the movement amount L of the support portion from when the sensor 1 detects the step 9C to when the welding torch 2 contacts the step 9C. The invention of claim 5 is
According to the second aspect of the present invention, the support portion is rotated by 90 degrees around its axis, and the horizontal distance Yp in the horizontal direction orthogonal to the horizontal direction is further detected in the same procedure.

According to the present invention, the step 9C of the reference sample 9 is detected by the welding torch 2 and the displacement sensor 1, and based on the result of the detection, the three steps of the welding torch 2 and the displacement sensor 1 are detected.
The dimensional distances Xp, Yp, Zp are measured.

In the meantime, in the section of the means for solving the above-mentioned problem which explains the constitution of the present invention, the drawings of the embodiments of the present invention are used in order to make the present invention easy to understand. However, the present invention is not limited to this.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. -First Embodiment- Fig. 1 is a perspective view showing a schematic configuration of a cross-sectional shape measuring device for performing a position calibration method of a displacement sensor according to a first embodiment of the present invention. As shown in FIG. 1, a welding device with a sectional shape memory function for carrying out the first embodiment includes a welding torch 2 for performing welding while melting a welding wire 8 protruding from a tip, and a welding torch. 2, a non-contact displacement sensor 1 for measuring a cross-sectional shape of a work 3 and a displacement sensor 1 and a welding torch 2
A torch driving device 6 for driving in a three-dimensional manner, a sensor control device 4 for controlling the driving of the displacement sensor 1, and a torch driving device for acquiring shape information of a target range in accordance with a command from the sensor control device 4. 6, the torch drive device 6 is driven to move and rotate the displacement sensor 1 and the welding torch 2, and based on the shape information obtained by the displacement sensor 1, the movement and welding of the welding torch 2 during welding. And a welding control device 5 for controlling welding conditions by the power supply 7. In the present embodiment, the displacement sensor 1 reflects a laser beam emitted from itself on the surface of the work 3 and detects the reflected light so as to detect the distance between itself and the work 3. Be composed.

FIG. 2 is a perspective view showing the configuration of a reference sample used in the position calibration method according to the present embodiment. FIG.
As shown in the figure, the reference sample 9 is provided with a high plane portion 9A, a low plane portion 9B, and a step 9C. Here, the horizontal direction and the vertical direction in the present embodiment refer to the horizontal direction and the vertical direction with respect to the high plane portion 9A or the low plane portion 9B of the reference sample 9. FIG. 3 is a diagram showing a positional relationship between the displacement sensor 1 and the tip of the welding wire 8 of the welding torch 2 in FIG. As shown in FIG. 3, corresponding to the X-axis, Y-axis and Z-axis of the torch driving device 6, the tip of the welding wire 8 and the displacement sensor 1 are distance Xp in the X direction, distance Yp in the Y direction, and Z direction. By determining the distances Xp, Yp, and Zp, the positional relationship between the displacement sensor 1 and the tip of the welding wire 8, that is, the welding torch 2, can be obtained.

Next, the operation of this embodiment will be described. 4 and 5 are diagrams showing the operation of the displacement sensor 1 and the welding torch 2 in the present embodiment, and FIG. 6 is a flowchart showing the operation of the present embodiment. First, in step S1, the displacement sensor 1 and the welding torch 2 are set at an initial position above the low plane portion 9B of the reference sample 9.
At this time, a voltage is applied to the welding torch 2 to
Contact with the reference sample 9 can be detected.
In step S2, the displacement sensor 1 and the welding torch 2 are lowered, and when it is detected that the tip of the welding wire 8 has contacted the low flat portion 9B, the displacement sensor 1 and the welding torch 2 are stopped from lowering, and the displacement at the time of contact is stopped. The output of the sensor 1 is assumed to be Zp (FIGS. 4A and 5A). Next, in step S3, the welding torch 2 is raised by the distance Z1, and the displacement sensor 1 and the welding torch 2 are linearly moved in the direction of the step 9C horizontally with respect to the low plane portion 9B. At this time, a voltage is applied to the welding torch 2 in the same manner as when the welding torch 2 is lowered, and the step 9C of the reference sample 9 is detected by the tip of the welding wire 8, and the shape of the reference sample 9 is detected by the displacement sensor 1. Further, the distance L in which the welding torch 2 moves from the initial position in the horizontal direction is also detected.

Further, in step S4, it is determined whether or not the welding wire 8 has contacted the step 9C.
If the result in No. 4 is negative, it is determined in step S5 whether the displacement sensor 1 has detected the step 9C. When step S5 is denied, it returns to step S4,
The shape measurement of the reference sample 9 by the displacement sensor 1 and the welding torch 2 is continued. When step S4 is affirmed, the welding wire 8 has a step 9 before the displacement sensor 1.
C (FIG. 4B), and the horizontal moving distance L of the welding torch 2 is set to 0 in step S6.
Then, in step S7, the displacement sensor 1 and the welding torch 2 are further raised by the distance Z2. During this time, the movement of the displacement sensor 1 and the welding torch 2 in the horizontal direction is continued. Next, in step S8, it is determined whether or not the displacement sensor 1 has detected the step 9C. If step S8 is denied, the process of step S8 is repeated until step S8 is affirmed.

On the other hand, if step S5 is affirmed,
It is determined that the displacement sensor 1 has detected the step 9C earlier than the contact of the welding wire 8 (FIG. 5B), and the moving distance L is initialized to 0 in step S9. During this time, the displacement sensor 1 and the welding torch 2
In the horizontal direction is continued. Then, step S
At 10, it is determined whether or not the welding wire 8 has contacted the step 9C. If step S10 is denied, the process of step S10 is repeated until step S10 is affirmed.

When the displacement sensor 1 detects the step 9C (FIG. 4C) or when the welding wire 8 comes into contact with the step 9C (FIG. 5C), the displacement sensor 1 and the welding torch 2 are moved in step S11. The movement is stopped, and in step S12, the movement distance L of the displacement sensor 1 and the welding torch 2 after being initialized in step S6 or step S9 is detected, and this movement distance L is determined by the X of the displacement sensor 1 and the welding torch 2. It is detected as the distance Xp in the direction. Thereafter, the displacement sensor 1 and the welding torch 2 are rotated by 90 degrees around the vertical axis, and the above-described steps S1 to S
The movement distance L is obtained by repeating the processing up to 12, and the movement distance L is detected as the movement distance Yp of the displacement sensor 1 and the welding torch 2 in the Y direction.

In the above embodiment, the movement of the vertical distances Z1 and Z2 is for avoiding the contact between the welding wire 8 and the reference sample 9 during the horizontal movement. It is sufficient if the distance can be avoided, but the distance Z1 needs to be within the height of the step 9C of the reference sample 9. By the above processing, the distances Xp, Y indicating the three-dimensional positional relationship between the displacement sensor 1 and the welding torch 2
p and Zp are determined. The positional relationship between the displacement sensor 1 and the welding torch 2 can be accurately calibrated based on the distances Xp, Yp, and Zp obtained in this manner.

-Second Embodiment- Next, a second embodiment of the present invention will be described.
7 and 8 are diagrams showing the operation of the displacement sensor 1 and the welding wire 8 in the second embodiment, and FIG. 9 is a flowchart showing the operation of the second embodiment. First, in step S21, the displacement sensor 1 and the welding torch 2 are set at an initial position above the low plane portion 9B of the reference sample 9 (FIGS. 7A and 8A). At this time, welding torch 2
, A voltage can be applied to detect that the tip of the welding wire 8 contacts the reference sample 9. In step S22, the displacement sensor 1 and the welding torch 2 are lowered, and when the tip of the welding wire 8 comes into contact with the low plane portion 9B, the displacement sensor 1 and the welding torch 2 are stopped from lowering, and the output of the displacement sensor 1 at the time of contact is obtained. Is Zp (FIG. 7B, FIG. 8).
(B)). Next, in step S23, welding torch 2
Is increased by the distance Z1, and the displacement sensor 1 and the welding torch 2 are inclined at an angle θ with respect to the vertical axis V toward the direction of the step 9C (FIGS. 7C and 8C). Then, in step S24, the displacement sensor 1 and the welding torch 2 are linearly moved in the direction of the step 9C.
At this time, a voltage is applied to the welding torch 2 and the step 9C of the reference sample 9 is detected by the tip of the welding wire 8, and the shape of the reference sample 9 is also detected by the displacement sensor 1 as in the case of the descent. At this time, the displacement sensor 1 has
The laser light emitted from the displacement sensor 1 is scattered at the low plane portion 9B.
, The displacement sensor 1 and the low plane portion 9
The distance to B is detected. Further, the distance L in which the welding torch 2 moves from the initial position in the horizontal direction is also detected.

Further, in step S25, the step 9C
It is determined whether or not the welding wire 8 has come into contact with the first position. If the result at Step S25 is negative, it is determined at Step S26 whether or not the displacement sensor 1 has detected the step 9C. If step S26 is denied, step S26
25, the measurement of the shape of the reference sample 9 by the displacement sensor 1 and the welding torch 2 is continued. If step S25 is affirmed, it is determined that the welding wire 8 has contacted the step 9C earlier than the displacement sensor 1 (FIG. 7).
(D)), the moving distance L is initialized to 0 in step S27, and the displacement sensor 1 and the welding torch 2 are further raised by the distance Z2 in step S28 (FIG. 7 (e)).
During this time, the movement of the displacement sensor 1 and the welding torch 2 in the horizontal direction is continued. Next, in step S29, it is determined whether or not the displacement sensor 1 has detected the step 9C. If step S29 is denied, the process of step S29 is repeated until step S29 is affirmed.

On the other hand, if step S26 is affirmed, it is determined that the displacement sensor 1 has detected the step 9C earlier than the contact of the welding wire 8 (FIG. 8).
(D)), the moving distance L is initialized to 0 in step S30. During this time, the movement of the displacement sensor 1 and the welding torch 2 in the horizontal direction is continued. Next, in step S31, the welding wire 8 is moved to the step 9C.
Is determined, and if step S31 is denied, the process of step S31 is repeated until step S31 is affirmed.

When the displacement sensor 1 detects the step 9C (FIG. 7F), or when the welding wire 8 contacts the step 9C (FIG. 8E), the displacement sensor 1 and the welding torch 2 in step S32. Is stopped, and in step S33, step S27 or step S27 is performed.
The displacement distance L of the displacement sensor 1 and the welding torch 2 after being initialized at 30 is detected, and based on the movement distance L, the distance Xp between the displacement sensor 1 and the welding torch 2 in the X direction is described later. To detect. Thereafter, the displacement sensor 1 and the welding torch 2 are rotated by 90 degrees around the vertical axis, and the processing from step S21 to step S33 is repeated to obtain the moving distance L. Is detected as the distance Yp in the Y direction.

FIG. 10 shows a distance X based on the moving distance between the displacement sensor 1 and the welding torch 2 in the second embodiment.
It is a diagram for explaining a method of calculating p or Yp,
(A) is a case where the welding wire 8 contacts the step 9C first.
(B) is a diagram showing a case where the displacement sensor 1 previously detects the step 9C. In FIG. 10, the distance Lt is the distance between the displacement sensor 1 to be determined and the tip of the welding wire 8, and is the above-described distance Xp or Yp. Here, in FIG. 10A, the relationship between the moving distance L and the distance Lt is L <Lt, and in FIG. 10B, the relationship between the moving distance L and the distance Lt is L> Lt. ing. 10A, the relationship between the moving distance L and the distance Lt is as follows: Lt = Lcos θ + (Z1 + Z2) sin θ (1) In FIG. 10B, the moving distance L and the distance Lt
The relationship with t is as follows: Lt = Lcos θ−Z1 · sin θ (2) Then, in step S33, the distance Xp or Yp is obtained from the moving distance L based on the above equation (1) or (2).

In the above embodiment, the movement of the vertical distances Z1 and Z2 is for avoiding the contact between the welding wire 8 and the reference sample 9 during the movement in the horizontal direction. It is sufficient if the distance can be avoided, but the distance Z1 needs to be within the height of the step 9C of the reference sample 9. By the above processing, the distances Xp, Y indicating the three-dimensional positional relationship between the displacement sensor 1 and the welding torch 2
p and Zp are determined. Then, the positional relationship between the displacement sensor 1 and the welding torch 2 is calibrated based on the distances Xp, Yp, Zp obtained in this manner.

Here, when the welding wire 8 takes various welding positions with respect to the material to be welded, or when the feeding property of the welding wire 8 changes, bending shown by ΔXp, ΔYp, ΔZp in FIG. 11 occurs. For this reason, when the welding wire 8 is vertically held and moved with respect to the reference sample 9 as in the first embodiment, as shown in FIG. Cannot contact step 9C. On the other hand, in the second embodiment, when the displacement sensor 1 and the welding torch 2 are moved, they are inclined by an angle θ with respect to a vertical axis, as compared with the first embodiment. Therefore, even if the welding wire 8 is bent,
As shown in FIG. 2B, the tip of the welding wire 8 can contact the step 9C. Therefore, even if the welding wire 8 is bent, the distances Xp, Yp, and Zp between the tip of the welding wire 8 and the displacement sensor 1 can be accurately obtained.
The angle θ needs to be determined so that the tip of the welding wire 8 contacts the step 9C in consideration of the bending of the welding wire 8.

In the second embodiment, the amount of bending can be determined during welding. Calibration of the bending of the welding wire 8 will be described below with reference to FIG. As shown in FIG. 13, first, in step S41, FIG.
, The positional relationship between the displacement sensor 1 and the tip of the welding wire 8 is obtained, and the distances Xp, Yp, Zp obtained by these processes are set as initial calibration values X0, Y0, Z0. . In the next step S42, the detection of the welding position and the initial calibration values X0, Y0,
The target position of the welding torch 2 is determined based on the ZO, and welding is performed. The bending occurs in the welding wire 8 and step S43
Again from step S21 to step S shown in FIG.
33, the distances Xp, Yp, Zp are obtained. The distances Xp, Yp, Z obtained in step S43
p is the bending amount ΔXp, ΔYp, ΔZp of the welding wire 8
ΔXp, ΔYp, and ΔZp are obtained in step S44 by the following equation (3). ΔXp = Xp−X0 ΔYp = Yp−Y0 (3) ΔZp = Zp−Z0 These ΔXp, ΔYp and ΔZp are the amounts of bending to be determined.

[0025]

As described in detail above, according to the first to fifth aspects of the present invention, the step of the reference sample is detected by the welding torch and the displacement sensor, and the distance between the welding torch and the displacement sensor is determined. Since it is determined, the position of the displacement sensor can be accurately calibrated based on this distance. In particular, according to the fourth and fifth aspects of the present invention, when the step of the reference sample is detected, the welding torch and the displacement sensor are inclined at a predetermined angle with respect to the reference sample. Even if the welding wire is bent, the tip of the welding wire can contact the step, so that even if the welding wire is bent, the distance between the displacement sensor and the welding torch is obtained, and the position of the displacement sensor is determined based on this distance. Can be accurately calibrated.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a configuration of a cross-sectional shape measuring apparatus for performing a position calibration method of a displacement sensor according to the present embodiment.

FIG. 2 is a perspective view showing the shape of a reference sample.

FIG. 3 is a perspective view showing a positional relationship between a welding torch and a displacement sensor.

FIG. 4 is a diagram for explaining a position calibration method of the displacement sensor according to the first embodiment.

FIG. 5 is a diagram for explaining a position calibration method of the displacement sensor according to the first embodiment.

FIG. 6 is a flowchart showing processing performed by the displacement sensor position calibration method according to the first embodiment;

FIG. 7 is a view for explaining a position calibration method of a displacement sensor according to a second embodiment.

FIG. 8 is a diagram for explaining a position calibration method of a displacement sensor according to a second embodiment.

FIG. 9 is a flowchart showing processing performed by a displacement sensor position calibration method according to the second embodiment.

FIG. 10 is a diagram for explaining calculation of a distance between a displacement sensor and a welding torch in the second embodiment.

FIG. 11 is a view showing bending of a welding wire;

FIG. 12 is a diagram showing a state in which a bent welding wire contacts a step;

FIG. 13 is a flowchart showing a process for obtaining a bending amount;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Displacement sensor 2 Welding torch 3 Work 4 Sensor controller 5 Welding controller 6 Torch drive 7 Welding power supply 8 Welding wire 9 Reference sample 9A High plane part 9B Low plane part 9C Step

Claims (5)

[Claims] A displacement sensor for measuring a distance to an object in a non-contact manner is rotatably supported by a supporting portion on a three-dimensional vertical plane and capable of measuring the distance to the object. In a position calibration method of a displacement sensor in a shape measuring device attached to the support portion near a torch and measuring the planar shape of the object by the displacement sensor and the welding torch, a high plane portion and a low plane portion separated by a step The step of the reference sample having is detected by the welding torch and the displacement sensor while moving the welding torch and the displacement sensor in a direction parallel to the low plane portion, and the welding is performed based on the detection result. A position calibration method for a displacement sensor, comprising measuring a three-dimensional distance between a torch and the displacement sensor. 2. The welding torch, wherein the displacement sensor and the welding torch are positioned at an initial position above a low plane portion of the reference sample, and the support portion is lowered by a predetermined distance in a direction perpendicular to the reference sample. Is brought into contact with the low plane portion, an output of the displacement sensor at the time of the contact is detected as a vertical distance, and the support portion is raised in the vertical direction by a predetermined distance, and the support portion is directed toward the high plane portion. If the welding torch moves linearly in the horizontal direction with respect to the reference sample, and the welding torch contacts the step first, the supporting portion is further raised and the supporting portion is linearly moved in the horizontal direction. Detecting the amount of movement of the support section from when the welding torch contacts the step to when the displacement sensor detects the step, as a horizontal distance, and the displacement sensor first Is detected, the support portion is further linearly moved in the horizontal direction, and the amount of movement of the support portion from when the displacement sensor detects the step to when the welding torch contacts the step is determined. 2. The position calibration method for a displacement sensor according to claim 1, wherein the distance is detected as a horizontal distance. 3. The displacement according to claim 2, wherein the support section is rotated by 90 degrees around its axis, and a horizontal distance in a horizontal direction orthogonal to the horizontal direction is further detected in the same procedure. Sensor position calibration method. 4. The welding torch, wherein the displacement sensor and the welding torch are positioned at an initial position on a low plane portion of the reference sample, and the support portion is lowered by a predetermined distance in a direction perpendicular to the reference sample. Is brought into contact with the low plane portion, the output of the displacement sensor at the time of the contact is detected as a vertical distance, the support portion is raised in the vertical direction by a predetermined distance and rotated by a predetermined angle with respect to a vertical axis, and then the The support is moved linearly in a horizontal direction with respect to the reference sample toward the high plane portion, and when the welding torch contacts the step first, the support is further raised and the support is moved. Is moved linearly in the horizontal direction, and the horizontal distance is determined based on the amount of movement of the support portion from when the welding torch contacts the step to when the displacement sensor detects the step. If the displacement sensor detects the step first, the support portion is further linearly moved in the horizontal direction, and after the displacement sensor detects the step, the welding torch is moved to the step. 2. The position calibration method for a displacement sensor according to claim 1, wherein a horizontal distance is detected based on an amount of movement of the support unit until the support unit contacts. 5. The displacement according to claim 4, wherein the support section is rotated by 90 degrees around its axis, and a horizontal distance in a horizontal direction orthogonal to the horizontal direction is further detected in the same procedure. Sensor position calibration method.