JPH0461756B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention applies a sensing voltage to a consumable electrode type welding torch in an automatic welding device that reproduces predetermined work contents, and uses this welding torch as a sensor. A welding line of an automatic welding device that corrects the taught welding start or end position by detecting a deviation in the welding line direction of a member (not limited to a workpiece forming a groove) facing the welding start or end position. It concerns the correction method.

[Conventional technology]

A consumable electrode type welding torch (hereinafter referred to as a welding torch) is used as a sensor, and the consumable electrode (hereinafter referred to as a wire) protruding from the welding torch is brought into contact with the workpiece to detect the position of the workpiece and detect individual differences and Conventionally, means have been used to detect deviations due to installation errors and automatically correct the weld line (see Japanese Patent Application Laid-Open No. 61-33775).

This prior art will be briefly explained with reference to FIG.
In addition, in FIG. 6, the horizontal plate W1 and the vertical plate W
Welding line WL at the right angle corner of workpiece W combined with 2
The solid line shows the position of the workpiece W actually placed, and the broken line shows the position of the workpiece W at the time of teaching.

First, the length of the wire protruding from the welding torch is regulated to a predetermined length, and then the welding torch is moved to the first sensing start point SP ₁ (a point near the welding start point WP ₂ ).
position and perform sensing. As a result of this sensing, the position information of the point P ₁ ' on the welding line WL is stored, and the difference ΔP ₁ from the position information of the corresponding point P ₁ at the time of teaching is calculated and stored. Next, move the welding torch to the second sensing start point SP ₂ (welding end point
WP ₃ ) and perform sensing. Then, in the same manner as described above, a point P ₂ ' on the welding line WL is determined, and the difference ΔP ₂ between the position information of the corresponding point P ₂ at the time of teaching is calculated and stored.

The rotational deviation of the work W (welding line) is obtained from the obtained differences ΔP ₁ and ΔP ₂ , and based on this, the position of the taught third sensing start point SP ₃ is corrected,
A correction point SP' ₃ corresponding to the rotational deviation of the workpiece W is calculated and stored, and the welding torch is moved and positioned to the correction point SP ₃ '. Furthermore, the sensing direction SP ₃ P ₃ -------> from the sensing start point SP ₃ at the time of teaching is also corrected and commanded based on the rotational deviation. As a result, the welding torch performs sensing while moving in a direction perpendicular to the end surface f ₃ of the vertical plate W2, and captures the positional information of the point P ₃ ' on the end surface f ₃ .
The difference ΔP ₃ (deviation in the welding line direction) from the position information of the corresponding point P ₃ at the time of teaching is calculated and stored.

Next, position the welding torch at teaching point _WP1 . Then, the difference ΔP ₁ obtained by sensing the next target point, that is, the taught welding starting point WP ₂ , is
The position was corrected by ΔP ₂ and ΔP ₃ and the corrected point
Command the position information of WP ₂ ′. As a result, the welding torch moves toward the new welding starting point WP ₂ ′.

When the welding torch reaches the point WP ₂ ′, the next target point,
In other words, the taught welding end point WP ₃ is divided by the difference ΔP ₁ ,
The position is corrected using ΔP ₂ and ΔP ₃ in the same manner as before, and the position information of the corrected point WP ₃ ' is commanded. Therefore, the welding torch starts arc weaving welding from point WP ₂ ′ and performs horizontal fillet welding toward point WP ₃ ′. In this way, welding ends when point WP ₃ ' is reached, and the welding torch returns to the taught evacuation point.
Move to WP ₄ .

As described above, in the conventional weld line correction means, at the points SP ₁ and SP ₂ which are the same position as the welding start point WP ₂ and the welding end point WP ₃ or in the vicinity thereof,
After sensing in the cross-sectional direction of the groove and detecting rotational deviations (ΔP ₁ , ΔP ₂ ), etc. of the workpiece W, based on the detected deviations, the deviation (ΔP ₃ ) of the workpiece W in the welding line direction is detected. The starting point SP ₃ of sensing performed to detect the sensing and its sensing direction are corrected to ensure that the welding torch comes into contact with the end face f ₃ of the workpiece W. Thereby, the deviation of the workpiece W in the welding line direction is reliably detected.

Then, each time the welding torch reaches a position WP ₁ , WP ₂ ′ related to a predetermined welding line WL, the next target point WP ₂ , WP ₃ is determined by the three values ΔP ₁ , The welding line position information taught in advance is corrected based on ΔP ₂ and ΔP ₃ .

[Problem to be solved by the invention]

However, this conventional technology requires extra work such as sensing SP ₁ and SP ₂ in the cross-sectional direction of the groove in order to increase the reliability of detecting deviations in the direction of the weld line of the workpiece, resulting in a decrease in operating efficiency. It becomes a factor that leads to

The present invention aims to solve these problems, and provides a weld line correction method for an automatic welding device that allows the detection of deviations in the weld line direction to be performed easily and reliably without extra work. The purpose is to provide.

[Means to solve the problem]

In order to achieve the above object, a weld line correction method for an automatic welding apparatus according to claim 1 of the present invention provides a welding start position or a welding end position detected by a previously taught sensing operation or a predetermined sensing operation in the groove cross-sectional direction. a first movement vector from a sensing start teaching point to a reference member detection teaching point, which is taught to start detecting the position of the reference member in the welding line direction; and a second movement vector from the reference member detection teaching point to a predetermined teaching point, and moving the welding torch from the sensing start teaching point in the direction of the first movement vector to the energization detection means. The reference member is detected by detecting the energization state at the reference member, and after moving the welding torch by the second movement vector from the reference member detection position, the position between the reached point and the predetermined teaching point. The method is characterized in that a difference in information is calculated, and the deviation in the welding line direction of the welding start position or welding end position is corrected using the calculated difference.

Further, in the welding line correction method of an automatic welding device according to claim 2 of the present invention, in the step, a sensing voltage is applied to the welding torch to cause the welding torch to approach the reference member at high speed (first movement vector ), stop the operation of the welding torch based on the energization detection output from the energization detection means, and then move the welding torch away at low speed based on the energization detection output, and move the welding torch away from the reference member at a low speed. The separation of the consumable electrode from the welding torch is detected by the energization detection means, and the separation detection output from the energization detection means is used as a movement command signal for the welding torch in the second movement vector direction. .

[Effect]

In the welding line correction method for an automatic welding device according to claim 1 of the present invention described above, first, the welding torch is moved in the direction of the first movement vector (vector from the sensing start teaching point to the reference member detection teaching point), When the actual reference member is detected by the energization detection means, the welding torch is moved by a second movement vector (vector from the reference member detection teaching point to the predetermined teaching point) to reach the point, The difference between the taught data and the actual torch point is calculated. Here, since the reference member has an unchanged positional relationship in the welding line direction with respect to the welding start position or welding end position, respectively,
By detecting the position of this reference member in the welding line direction, the deviation of the welding line in the welding line direction is obtained as the difference. By correcting the deviation of the welding start position or welding end position in the welding line direction based on this difference, the position of the welding line to be welded by the welding torch in the welding line direction is corrected.

Further, in the welding line correction method of an automatic welding device according to claim 2 of the present invention, when detecting the reference member, first, the wire protruding from the welding torch is aligned with the reference member while the sensing voltage is applied to the welding torch. The contact state is detected as the energized state of the wire by the energization detection means, but at this time, the operation of bringing the welding torch close to the reference member is performed at a high speed (at a speed that does not cause plastic deformation of the wire when it comes into contact with the reference member). . Then, when the wire becomes energized, the energization detection output from the energization detection means causes the wire to be energized.
After the welding torch stops moving toward the reference member, it moves at low speed in a direction away from the reference member. Thereafter, the time point when the wire becomes de-energized is detected as a separation detection output from the energization detection means. The detected position is the accurate reference member position where the elastic deformation caused by the contact of the wire with the reference member has been restored, and this reference member position can be detected in a short time.

Furthermore, in this method (claim 2), the energization detection output output from the energization detection means in a state where the wire is elastically deformed is not used as a movement command signal for moving the welding torch in the second movement vector direction. A separation detection output output from the energization detection means at an accurate reference member position where elastic deformation has been eliminated is used as a movement command signal for the welding torch in the second movement vector direction.

[Embodiments of the invention]

Below, before describing an embodiment of the welding line correction method of an automatic welding device of the present invention with reference to the drawings,
First, with reference to FIG. 3, the configuration of an arc welding robot, which is one type of automatic welding apparatus applied to the method of the present invention, will be explained.

As shown in FIG. 3, a welding torch 2 is attached to the wrist portion 1a of the multi-jointed arc welding robot 1, and its position and attitude can be controlled. This control is performed by the robot control panel 3 or a teaching box 4 attached to the robot control panel 3. Further, a wire is supplied to the welding torch 2, and the wire is fed from the welding torch 2 according to the welding conditions for performing welding.

In order to use the welding torch 2 as a sensor, a welding power source 6 selectively applies a welding voltage and a sensing voltage between the welding torch 2 and the workpiece 7.
is equipped with a sensing power source (not shown). The energization state due to contact between the wire and the workpiece 7 is detected by energization detection means (not shown) in the robot control panel 3. In addition, work 7
is controlled in attitude relative to the welding robot 1 by a positioner 8.

The arc welding robot 1 performs a welding operation on the workpiece 7 by teaching the contents of the welding operation in advance, and reproduces the program according to a program stored in the storage device of the robot control panel 3.

In this embodiment, a case will be described in which a downward V-shaped groove joint as shown in FIGS. 2a and 2b is welded.

Here, the work 7 to be welded is composed of two members 7a and 7b forming a V-shaped groove, and a reference member 9 is placed at the end of the welding end of the work 7 so as to cover the V-shaped groove. It is fixed to the workpiece 7. Therefore, the reference member 9 is at the welding end position P6,
The positional relationship remains unchanged with respect to P6' in the welding line direction (direction of arrow a).

Further, in this embodiment, the workpiece 7 has a welding line 10.
There are various types of workpieces 7 with different lengths, and these workpieces 7 may be
It is assumed that the welding start position P5 does not shift in the welding line direction when the workpiece 7 is attached to the positioner 8.
That is, in this embodiment, the deviation in the welding line direction occurs only with respect to the welding end positions P6 and P6'.

When carrying out welding work along the welding line 10 of the workpiece 7, as described above, the content of the work is first taught in advance, and then the robot 1 performs a reproducing operation in accordance with the taught content. The teaching is performed by controlling the relative positions of the welding torch 2 and the workpiece 7 by operating the teaching box 4, and following, for example, the following steps (a) to (g). In addition,
In Fig. 2 a and b, the broken line indicates the workpiece 7 at the time of teaching.
and the positions of the reference member 9, and the solid lines indicate the positions of the workpiece 7 and the reference member 9 during actual reproducing operation. Also, among the symbols P0 to P6, those without a ``'' indicate points at the time of teaching.

(a) Select the teaching mode and program number on the operation surface of the robot control panel 3.

(b) Move the welding torch 2 to the retracted position (see position P0 in FIGS. 2 a and b), memorize the position, and set the air cut speed to the next teaching point.

(c) Guide the welding torch 2 to the sensing start teaching point P1 where detection of the position of the reference member 9 in the welding line direction starts, store this point P1, and write the welding end position deviation search code (the operation is explained in the first , which will be described later with reference to FIG. 2), and set a command to start sensing in the welding line direction.

(d) Move the welding torch 2 to the reference member detection teaching point P
2 (the point on the reference member 9 at which the energization detection output is obtained by the energization detection means), and this point P2 is stored.

(e) Next, the welding torch 2 is sequentially moved to air cut points (next teaching points) P3 and P4 that do not interfere with the workpiece being taught, and each point P3 and P4 is sequentially memorized.

(f) Then, the welding torch 2 is moved to the welding start position 5 on the welding line 10 at the end of the workpiece 7, and the position P5 is memorized. At this time, if a mode is set to perform a predetermined sensing operation in the cross-sectional direction of the groove using the wire earth method (corresponding to a V-shaped groove joint), the welding start position P5 can be detected during automatic regeneration of the robot 1. can be done reliably.
Furthermore, at the welding start position P5, welding line 1
Set welding operation start command and welding conditions according to 0.

(g) Move the welding torch 2 to the welding end position P6 on the welding line 10 and memorize the position, and set a welding operation end command at the same position P6.

Next, a method for detecting a welding start position as an embodiment of the present invention, which is carried out by automatically regenerating the robot 1 after teaching as described above, will be described with reference to FIGS. 1 and 2. In addition,
FIG. 1 is a flowchart of the method of this embodiment, and FIGS. 2a and 2b are diagrams for explaining the state of movement of the welding torch according to the procedure shown in FIG. Figure 2b is a plan view.

(1) First, the welding torch 2 is positioned at the taught retreat position P0 based on the teaching data (step S1). Then, when the regeneration operation is started and the welding torch 2 reaches the sensing start teaching point P1, a sensing voltage is applied to the welding torch 2 in response to a sensing start command (step S2).

(2) At the same time, at the sensing start teaching point P1, this sensing start teaching point P
1 to the reference member detection teaching point P2.
A movement vector P1P2-----> and a second movement vector P2P3-----> from the reference member detection teaching point P2 to the next air cut point P3 are calculated and stored (step S3).

(3) Then, move the welding torch 2 from the sensing start teaching point P1 in the direction of the first movement vector P1P2---→ at a predetermined sensing speed (approximately 60 cm/min)
During this period, it is determined whether there is an energization detection output from the energization detection means (step S5). The movement in step S4 is continued until there is an energization detection output, and when that output is obtained, it is detected that the welding torch 2 has reached the actual detection point P2' on the reference member 9 (step S6). , the welding torch 2 is stopped. In addition, at this time, even if the welding torch 2 moves more than a predetermined distance, the actual detection point P
If 2' cannot be detected, an error signal is output.

(4) Next, move the welding torch 2 by the second movement vector P2P3---→ from the actual detection point P2' to the next point, the air cut point P.
3' (step S7).

(5) At the reached point P3', calculate and store the difference Δ in position information between this point P3' and the taught air cut point P3 (step S8).

(6) After that, move the welding torch 2 to the taught air cut point P4 (step S9),
Furthermore, after moving to the taught welding start position P5 and performing a sensing operation to detect this welding start position P5, welding along the welding line 10 under predetermined welding conditions by a welding operation start command (weaving welding) (Step S1)
0). In this example, as described above, the welding start position P5 is arranged so as not to shift in the direction of the welding line when the workpiece 7 is attached. ), the position corresponding to the taught welding start position P5 is reliably detected.

(7) Then, while performing welding along the welding line 10, the welding torch 2 is moved to the welding end position P6'=P6+Δ where the deviation is corrected based on the difference Δ, that is, the deviation in the welding line direction, and this position After P6' is reached, welding is terminated by a welding operation termination command (step S11).

As described above, according to the method of the present embodiment, a deviation in the welding line direction is detected for the welding end position P6, and the deviation is reflected only for the welding end position P6, resulting in different welding depending on the type of workpiece 7. The position of the welding end position P6 is corrected according to the length of the line 10. Therefore, it is possible to easily and reliably detect deviations in the welding line direction without performing extra sensing operations in the groove cross-sectional direction in order to reliably detect deviations in the welding line direction, as in conventional methods. can be reflected where necessary.

Furthermore, according to the method of this embodiment, the deviation in the welding line direction, that is, the difference Δ, is calculated at the air cut point P3' next to the actual detection point P2', so when performing the sensing operation, There is no need to manage the length of the wire protruding from the welding torch 2, and there is no need for any means for managing it.

Furthermore, the air cut point P where the difference Δ is calculated
3' will inevitably vary by the amount of deviation from point P3 at the time of teaching, so it is possible to prevent collisions during movement of the welding torch 2 due to deviations when mounting the workpiece 7 or reference member 9, and the operator can perform teaching operations that take into account deviations. There is no need to inflict it on others.

In addition, in the above description, a case has been described in which the deviation in the welding line direction is reflected in the welding end position P6, but as shown in FIG. 4, it can also be reflected in the welding start position P5. In FIG. 4, the welding start position P5 is on the reference member 9 side, and the welding start position P5 and welding end position P6 in the case of FIG.
This is a case in which the welding end position P6 does not shift in the welding line direction when the workpiece 7 is attached to the positioner 8. In this case, the difference Δ calculated at the air cut point P3' is P5'=P when the welding torch 2 moves to the welding start position P5.
It will be corrected and reflected as 5+Δ. In addition, in Fig. 4, P7 is the welding torch 2 after welding is completed.
is the retreat position to which it moves.

In addition, welding start position P5 and welding end position P
6 By providing corresponding reference members for each,
For each position P5, P6, the deviation in the welding line direction can be corrected in the same manner as described above, and this deviation can be reflected in both positions P5, P6.

Further, in the above embodiment, a case is explained in which a special member 9 is provided at the end of the workpiece 7 as a reference member, but the workpiece member itself forming the groove may also be used as the reference member. .

By the way, when detecting the actual detection point P2' executed in steps S4 to S6 in FIG.
cm/min), but by applying the method of claim 2 of the present invention, the actual detection point P2' can be detected by the following procedure. .

The basic procedure when performing arc welding using the arc welding robot 1 described above will be explained based on FIGS. 5a and 5b. In addition, FIG. 5a is a flowchart of the sensing operation, and FIG. 5b is a diagram for explaining an example of the moving state of the welding torch 2 during the sensing operation, and each point Q1 to Q7 in FIG.
is a plot of the position of the welding torch 2 at each constant control cycle until the detection operation of the reference member 9 is completed.

First, a sensing voltage is applied to the welding torch 2 to move the welding torch 2 toward the reference member 9 at high speed (step A1; points Q1 to Q3). The high moving speed at this time is such a speed that the wire does not undergo plastic deformation when the reference member 9 contacts, for example.
Select around 300cm/min. Note that the moving speed during conventional sensing operations was always about 60 cm/min.

When the wire comes into contact with the reference member 9 as it moves in step A1, the welding torch 2 and the reference member 9 become energized, which is detected by the energization detection means (step A2; point Q4), and this detection signal causes the welding torch to The movement of the reference member 2 in the direction of the reference member 9 is stopped (step A3). At the time of stopping, the welding torch 2 is
Since it was moving at high speed, the wire went too far toward the reference member 9 than the correct position of the reference member 9, as shown by point Q4 in FIG. 5b, and stopped in a state where the wire was elastically deformed.

Therefore, in the present invention, after stopping the welding torch 2, the welding torch 2 is moved at low speed in a direction away from the reference member 9 (step A4; point Q).
5, Q6). At this time, the low speed of movement is
For example, select around 30cm/min.

When the wire separates from the reference member 9 due to the movement in step A4, the welding torch 2 and the reference member 9 become de-energized, which is detected by the energization detection means (step A5; point Q
7). At the time when the wire separated from the reference member 9 and became de-energized, the welding torch 2 moved at a low speed, so the elastic deformation of the wire due to contact with the workpiece was gradually restored, and the welding torch 2 was moved so that the wire was the reference member. This means that an accurate workpiece position that can almost touch the member 9 has been detected.

At this time, when the welding torch 2 and the reference member 9 become de-energized, the separation detection output output from the energization detection means is the control signal of the arc welding robot 1 (in the case of this embodiment, the welding torch 2 control signal for moving from point P2' to P3')
The arc welding robot 1 is controlled by this separation detection output (step A6).

As described above, the energization detection output obtained when a wire with low rigidity is brought into contact with the reference member 9 and elastically deformed is not used as a processing signal as the position where the reference member 9 is detected, but is simply used for sensing operation. can be made extremely fast, greatly reducing sensing time. In addition, when the welding torch 2 is moved away from the reference member 9 at a low speed after stopping the high-speed sensing operation, the separation detection obtained when the elastic deformation of the wire is restored (when the wire is separated from the reference member 9). Since the signal is used as a subsequent control signal for the arc welding robot 1, the originally desired and accurate position of the reference member can be detected, and detection errors can be almost eliminated.

Note that in step A4 of the sensing operation flowchart in FIG. 5a, the welding torch is separated at a low speed of, for example, about 30 cm/min. When the bent wire is returned after approaching and stopping at high speed, the wire becomes curly, leading to an error in the separation of the wire. Therefore, it is better to gradually increase the separation speed of the welding torch. At this time, the curve to increase speed and the point at which it reaches can be arbitrarily selected.

In addition, in the above embodiment, the weld line correction method for a V-shaped groove joint was explained, but the method of the present invention
The present invention is not limited to this, and can be similarly applied to welding various other joint shapes.

Moreover, the teaching vector calculation of sensing operation and
The calculation may be performed at any time, such as when the teaching end signal is used, when the teaching program is performed using the playback operation signal, or when the workpiece detection point is reached during playback of the teaching program.

In addition, in the above embodiment, sensing is performed during the regeneration operation, and the difference Δ in position information at the next point reached by moving the welding torch 2 using the second movement vector from which the teaching vector is calculated in advance from the detection point.
However, depending on the computing power of the computer, it may be performed at any point up to the welding start point. In this case, it is necessary to calculate and store the second movement vector up to the point to be calculated.

Further, in the above embodiment, a case where detection is performed by moving the arc welding robot 1 side is shown, but the method of the present invention can be similarly utilized when detecting by moving the workpiece 7 side using the positioner 8.

Furthermore, the set moving speed of the welding torch 2 for the sensing operation described in the embodiment of the present invention is determined by the computing power of the computer used, and if the computing power of the computer is further improved in the future, the moving speed can also be made faster.

〔Effect of the invention〕

As described in detail above, according to the welding line correction method for an automatic welding device of the present invention according to claim 1, first, a deviation in the welding line direction is detected using a reference member with respect to the welding start position or the welding end position, and the deviation is detected. is corrected and reflected at each position, so deviations in the weld line direction can be easily and reliably detected without performing extra sensing operations in the groove cross-sectional direction as in the conventional method. In addition, since the deviation in the welding line direction is calculated at points after the actual detection point, there is no need to manage the length of the wire protruding from the welding torch, and there is no need for any means for managing it. Collisions during movement of the welding torch due to misalignment during installation of the reference member can be prevented, and there is no need to burden the operator with teaching operations in anticipation of misalignment.

Further, according to the welding line correction method of an automatic welding device of the present invention according to claim 2, when detecting the reference member, the energization detection output is obtained when the consumable electrode, which is not very rigid, is brought into contact with the workpiece and is elastically deformed. of,
Since the detected position of the reference member is not used as a processing signal but simply as a sensing operation stop signal, the sensing operation speed can be extremely fast, and the welding torch can be turned on after stopping the high-speed sensing operation. When moving the welding torch away from the reference member at low speed, the separation detection signal obtained when the consumable electrode separates from the reference member is used as a control signal to move the welding torch in the second movement vector direction. The automatic welding device can be controlled by detecting the desired accurate reference member position. Moreover, the sensing operation of the reference member in the method of claim 1 is performed in an extremely short time and accurately.

[Brief explanation of drawings]

1 to 5 show a welding line correction method for an automatic welding device as an embodiment of the present invention, and FIG. 1 is a flowchart for explaining the procedure, and FIG.
Figures a and b are diagrams for explaining the movement state of the welding torch according to the procedure of Figure 1, Figure 3 is a perspective view showing an arc welding robot to which the method of the present invention is applied, and Figure 4 is A diagram for explaining a modification of the moving state of the welding torch according to the procedure of this embodiment, FIG. 5a is a flowchart for explaining the procedure of the sensing operation, and FIG. 5b is the welding torch during the sensing operation FIG. 6 is a perspective view illustrating a welding line correction means of a conventional automatic welding device. In the figure, 1... arc welding robot (automatic welding device), 1a... wrist part, 2... welding torch, 3...
Robot control panel, 4...Teaching box, 6
... Welding power source, 7... Work (predetermined member), 7a,
7b... Member forming a welded joint, 8... Positioner, 9... Reference member, 10... Welding line.

Claims (1)

[Scope of Claims] 1. A welding voltage and a sensing voltage are selectively applied to a consumable electrode type welding torch, and when the sensing voltage is applied, the energization state between the consumable electrode protruding from the welding torch and a predetermined member is detected. A welding line correction method for an automatic welding device that has an energization detection means and reproduces work content taught in advance, the welding start being detected by a sensing action taught in advance or a predetermined sensing action in the cross-sectional direction of the groove. A reference member whose positional relationship remains unchanged in the welding line direction with respect to the position or welding end position is provided, and from a sensing start teaching point taught to start detecting the position of the reference member in the welding line direction to a reference member detection teaching point. and a second movement vector from the reference member sensing teaching point to a predetermined teaching point, and moving the welding torch from the sensing start teaching point in the direction of the first movement vector. The reference member is detected by detecting the energization state with the energization detection means, and after moving the welding torch by the second movement vector from the reference member detection position, the reached point and the previously determined Welding line correction for automatic welding equipment, characterized in that the difference in positional information from a determined teaching point is calculated, and the deviation in the welding line direction of the welding start position or welding end position is corrected using the calculated difference. Method. 2. When detecting the reference member by detecting the energization state with the energization detection means, a sensing voltage is applied to the welding torch to cause the welding torch to approach the reference member at high speed, and the energization detection means detects the reference member. The energization detection means stops the operation of the welding torch based on the energization detection output, and then causes the welding torch to move away at a low speed based on the energization detection output, thereby detecting the separation of the consumable electrode from the reference member. Welding line correction of an automatic welding apparatus according to claim 1, wherein the separation detection output from the energization detection means is used as a movement command signal for the welding torch in the second movement vector direction. Method.