JPH0461755B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention applies a sensing voltage to a consumable electrode type welding torch and uses this welding torch as a sensor in an automatic welding device that reproduces work content taught in advance. The present invention relates to a teaching data correction method for an automatic welding apparatus that detects a workpiece by performing a sensing operation and corrects the position necessary for appropriate welding.

[Prior art] A sensing voltage is applied to a consumable electrode type welding torch, the welding torch is used as a sensor, and the consumable electrode (hereinafter referred to as wire) protruding from the welding torch is brought into contact with the workpiece to automatically move the workpiece. Sensing means for detecting surfaces and weld lines have been conventionally used.

A technique using this sensing means is disclosed in Japanese Patent Publication No. 62-35861.

In this technique, a workpiece detection teaching point and a sensing operation (for example, three-way sensing) for detecting this workpiece detection teaching point are taught in advance according to the groove shape of the workpiece. Then, during regeneration operation when actually welding with automatic welding equipment, the actual workpiece position is detected as a workpiece detection point according to the taught sensing operation, and at this workpiece detection point, the same workpiece detection point and workpiece detection teaching are detected. Calculate the difference in position information from the point. In the case of three-directional sensing, the difference in such positional information is determined for three points, and the welding target position (welding start position) taught in advance is corrected based on the determined difference. As a result, the correct welding target position for each workpiece relative to the taught welding target position is detected.

[Problems to be Solved by the Invention] However, in this conventional technology, an error in the workpiece detection position (difference in positional information between the workpiece detection point and the workpiece detection teaching point) is detected at multiple positions by sensing operation, and then the error is detected. Only the final welding target position (welding start position) is corrected based on the error, so if the welding torch moves to another detection point during sensing operation due to an unexpected shift of the workpiece, the workpiece There is a problem that the operator is required to teach points that take into account the misalignment of the workpiece.

The present invention aims to solve these problems, and is designed to avoid collision between the welding torch and the workpiece during sensing operation, and to avoid the burden of teaching operations on the operator to prevent this. It is an object of the present invention to provide a teaching data correction method for an automatic welding device that allows correcting the position necessary for appropriate welding while correcting the teaching data based on information on positional deviation of a workpiece.

[Means for Solving the Problems] In order to achieve the above object, a method for correcting teaching data of an automatic welding apparatus according to claim 1 of the present invention includes the following steps: and a second movement vector from the workpiece detection teaching point to a predetermined teaching point, and executing the sensing operation to move the welding torch in the direction of the first movement vector, and the energization detection means After detecting the workpiece by detecting the energization state at the workpiece detection position and moving the welding torch by the second movement vector from the workpiece detection position, position information of the reached point and the predetermined teaching point is obtained. It is characterized by calculating the difference between the two and correcting the subsequent teaching data using the calculated difference.

Further, in the teaching data correction method for an automatic welding apparatus 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 workpiece at high speed (with a first movement vector). direction), 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 from the workpiece at a low speed based on the energization detection output, thereby removing the welding torch from the workpiece. Separation of the consumable electrode is detected by the energization detection means, and a 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.

[Function] In the teaching data correction method for an automatic welding apparatus according to claim 1 of the present invention described above, first, the welding torch is
When the actual workpiece is detected by the energization detection means by moving in the direction of the movement vector (vector from the sensing start teaching point to the workpiece detection teaching point), the second movement vector (vector from the workpiece detection teaching point to the workpiece detection teaching point) is detected. The welding torch is moved by a distance (vector to the teaching point), and at the point reached by this movement, the difference between the teaching data and the actual torch point is calculated, and the subsequent teaching data is corrected based on this difference. ,Furthermore, the sensing operation is performed based on the,modified teaching data, thereby avoiding collision of the welding torch,due to displacement of the workpiece during the sensing operation.
The position required for proper welding is corrected and detected.

In addition, in the teaching data correction method for an automatic welding apparatus according to claim 2 of the present invention, when detecting an actual workpiece, the consumable electrode protruding from the welding torch is first applied to the workpiece while a sensing voltage is applied to the welding torch. The contact state is detected as the energization state of the consumable electrode by the energization detection means, but at this time, the operation of bringing the welding torch closer to the workpiece is performed at a high speed (at a speed that prevents the consumable electrode from being plastically deformed when it comes into contact with the workpiece). . Then, when the consumable electrode becomes energized, the welding torch stops moving toward the workpiece according to the energization detection output from the energization detection means, and then moves at low speed in the direction away from the workpiece. . Thereafter, the time point when the consumable electrode becomes de-energized is detected as a separation detection output from the energization detection means. The detected position is the accurate workpiece position where the elastic deformation of the consumable electrode due to contact with the workpiece has been restored, and this workpiece 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 consumable electrode is elastically deformed is not used as a movement command signal in the second movement vector direction of the welding torch. The separation detection output output from the energization detection means at the correct workpiece 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] Before explaining embodiments of the teaching data correction method of an automatic welding apparatus of the present invention with reference to the drawings, first, FIG. The configuration of the basic arc welding robot will be explained.

As shown in FIG. 3, a consumable electrode type welding torch 2 is attached to the wrist portion 1a of the multi-jointed arc welding robot 1, and its position and posture are 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 as a consumable electrode is fed to the welding torch 2, and this wire always protrudes from the welding torch 2 by an appropriate amount.

In order to use the welding torch 2 as a sensor, the welding power source 6 includes a sensing power source (not shown) so that a welding voltage and a sensing voltage can be selectively applied between the welding torch 2 and the workpiece 7. It is provided. The state of energization from the welding torch 2 to the workpiece 7 due to the contact between the wire and the workpiece 7 is as follows:
It is detected by the energization detection means (not shown) in the robot control panel 3. Note that the workpiece 7 is fixed and supported at a suitable position and in a suitable posture by a positioner 8.

The arc welding robot 1 welds the workpiece 7 by teaching the contents of the welding work in advance, and performs the work in accordance with a program stored in the storage device of the robot control panel 3.

The sensing operation is taught by controlling the relative positions of the welding torch 2 and workpiece 7 by operating the teaching box 4, and for example, following the steps (a) to
(l). In this embodiment, as shown in FIG. 4, a case will be described in which the welding start position (welding target position) of a horizontal fillet joint is detected and corrected by three-directional sensing.

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

(b) First, move the welding torch 2 to the retracted position P1, store the position P1, and set the air cut speed to the next teaching point.

(c) Guide the welding torch 2 to the first sensing start teaching point P2, store this point P2, select the instruction code 3-direction sensing, and set the first direction (welding line direction) sensing start.

(d) Guide the welding torch 2 to the first workpiece detection teaching point P3 (the point on the vertical plate end surface 7a where the energization detection means obtains the energization detection output) and memorize this point P3.

(e) Move the welding torch 2 to a retreat position P4 that does not interfere with the work being taught, and store the position P4.

(f) Similarly to step (c) above, guide the welding torch 2 to the second sensing start teaching point P5, memorize this point P5, select the command code 3-direction sensing, and Board direction) Set sensing start.

(g) Guide the welding torch 2 to the second workpiece detection teaching point P6 (the point on the vertical plate surface 7b where the energization detection means can obtain the energization detection output) and store this point P6.

(h) Move the welding torch 2 to a retreat position P7 that does not interfere with the work being taught, and store the position P7.

(i) Similar to steps (c) and (f) above, welding torch 2
is guided to the third sensing start teaching point P8, this point P8 is memorized, the instruction code 3-direction sensing is selected, and the third direction (lower plate direction) sensing start is set.

(j) Guide the welding torch 2 to the third workpiece detection teaching point P9 (the point on the lower plate surface 7c where the energization detection means obtains the energization detection output) and memorize this point P9.

(k) Move the welding torch 2 to the retreat position P10 and memorize the position P10.

(l) Move the welding torch 2 to each position relative to the workpiece 7 in the order of welding start position P11, welding end position P12, and retreat position P13, store these positions P11 to P13, and perform welding operation at each position. Set commands, welding speed, etc.

After teaching the sensing operation and welding work content for each welding line of one workpiece as described above, the arc welding robot 1 executes a series of teaching operations for each newly installed workpiece 7.

Now, when starting the sensing operation taught during the reproducing operation, the taught data modification method which is a feature of the present invention is executed as follows. next,
A taught data modification method as an embodiment of the present invention will be explained with reference to FIGS. 1 and 2.

In this example, the sensing operation (three-directional sensing) taught as described above is reproduced,
The present invention is applied to detecting and correcting the welding start point in a horizontal fillet joint as shown in FIG.

The characteristic operations of the present invention (claim 1) include P2→P3→P4→P5 (first direction sensing), P5→P6→P7→ when reproducing the sensing operation shown in FIG. Since this is common to the three operations P8 (second direction sensing) and P8→P9→P10→P11 (third direction sensing), the sensing start teaching points P2, P5, and P8 are set to Q1 as shown in FIG. , the work detection teaching points P3, P6, and P9 are set as Q2, the retreat positions (next teaching points) P4, P7, and P10 are set as Q3, and the points P5, P8, and P11 are set as Q4, and only the characteristic basic movements are extracted and their flow is will be explained with reference to FIG.

Further, in FIG. 2, the position of the workpiece 7 and the operation of the welding torch 2 during teaching are shown by dotted lines, and the position of the workpiece 7 and the operation of the welding torch 2 during the actual regeneration operation are shown by solid lines.

(1) First, when starting the regeneration operation, the welding torch 2 is placed at the retracted position P1 (see FIG. 4). Then, the regeneration operation is started, and the welding torch 2
When the sensor reaches the sensing start teaching point Q1 (corresponding to points P2, P5, and P8 in Fig. 4), the welding torch 2 is activated by the sensing start command.
A sensing voltage is applied to (step S1).

(2) At the same time, at the sensing start teaching point Q1, this sensing start teaching point Q
1 to the work detection teaching point Q2 (corresponding to points P3, P6, and P9 in Fig. 4), and from the work detection teaching point Q2 to the next teaching point Q3 (corresponding to points P3, P6, and P9 in Fig. 4). A second movement vector Q2Q3---→ corresponding to points P4, P7, P10) is calculated and stored (step S2).

(3) Move the welding torch from the sensing start teaching point Q1 in the direction of the first movement vector Q1Q2---→ at a predetermined sensing speed (approximately 60 cm/min) (step S3), and during this period, the energization from the energization detection means is applied. Determine whether there is a detection output (step S)
4). Step S3 until there is an energization detection output.
When the welding torch 2 continues to move and the output is obtained, it is detected that the welding torch 2 has reached the actual workpiece detection point Q2' (step S
5) Stop the welding torch 2. Note that, at this time, if the workpiece detection point Q2' cannot be detected even if the welding torch 2 moves by a predetermined distance or more, an error signal is output.

(4) Then, the second
The welding torch 2 is moved by the movement vector Q2Q3---→ to reach the next point Q3' (step S6).

(5) At the reached point Q3', calculate the difference Δ in position information between point Q3' and the taught point Q3 (step S7).

(6) The subsequent teaching data (after point Q4) is corrected by the difference Δ calculated in step S7, and the subsequent reproducing operation is executed based on the corrected data (step S8).

In this way, P2→P3→P4→P5, P
5→P6→P7→P8, P8→P9→P10→P
Each time the first direction sensing, the second direction sensing, and the third direction sensing are executed along the lines 11 and 11, the teaching data after P5 is corrected by the difference Δ ₁ obtained in P4, and the welding torch 2 is moved. Thereafter, each time a difference Δ was obtained, the subsequent teaching data was corrected and the welding torch 2 was moved, and by cumulatively correcting the teaching data, the welding torch 2 finally reached the welding start position P11. sometimes,
This means that the welding start position, which is the required position for proper welding, has been reached.

In other words, in the conventional means, at the actual workpiece detection point Q2', the workpiece detection point Q2
The operation of calculating and memorizing the difference Δ in positional information between Immediately before reaching the welding start position, the taught welding start position P11 was corrected based on the stored difference Δ in the three directions, but in this example,
When a shift of the workpiece 7 is detected, the teaching data is sequentially corrected according to the magnitude of the shift.

Therefore, according to the embodiment of the present invention, there is no collision between the welding torch 2 and the workpiece 7 due to the displacement of the workpiece 7 during the sensing operation, and there is no burden on the operator to perform teaching operations to prevent this.
The welding start position can be corrected while correcting the teaching data based on the information on the positional deviation of the workpiece 7.

By the way, in the above embodiment, when detecting the actual workpiece detection point Q2' performed in steps S3 to S5 in FIG. However, when the method of claim 2 of the present invention is applied, the actual workpiece detection point Q2' 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 R1 to R7 in FIG.
is a plot of the position of the welding torch 2 at each constant control cycle until the detection operation of the workpiece 7 is completed.

First, the welding torch 2 is moved at high speed toward the workpiece 7 while applying a sensing voltage to the welding torch 2 and performing sensing to detect the energization state of the wire with the energization detection means (step A1;
points R1 to R3). The high moving speed at this time is selected to be a speed at which the wire does not undergo plastic deformation when the workpiece 7 contacts, for example, about 300 cm/min.
In addition, the movement speed during conventional sensing operation is
It was always around 60cm/min.

When the wire comes into contact with the workpiece 7 during the movement in step A1, the welding torch 2 and the workpiece 7 become energized, which is detected by the energization detection means (step A2; point R4), and at this point the welding torch 2 The movement of the workpiece in the direction of the workpiece 7 is stopped (step A3). At the time of stopping, the welding torch 2 is
Since it was moving at high speed, the wire moved too far to the workpiece 7 side than the correct position of the workpiece 7, as shown by point R4 in FIG. 5b, and stopped in a state where the wire was elastically deformed.

Therefore, in the present invention, following the stop of the welding torch 2, the welding torch 2 is moved at low speed in the direction away from the workpiece 7 (step A4; point R5,
R6). As the low moving speed at this time, for example, about 30 cm/min is selected.

When the wire separates from the workpiece 7 as it moves in step A4, the welding torch 2 and the workpiece 7 become de-energized, which is detected by the energization detection means (step A5; point R7).
Since the welding torch 2 is moving at low speed when the wire separates from the workpiece 7 and becomes de-energized, the elastic deformation of the wire due to contact with the workpiece is gradually restored, and the welding torch 2 This means that an accurate workpiece position where the wire is almost in contact with the workpiece 7 has been detected.

At the same time, the separation detection output output from the energization detection means when the welding torch 2 and the workpiece 7 become de-energized is the control signal of the arc welding robot 1 (the above-mentioned implementation shown in FIG. For example,
This is used as a control signal for moving the welding torch 2 from point Q2' to point _Q3 ', and the arc welding robot 1 is controlled by this separation detection output (step A6).

As described above, the energization detection output obtained when the non-rigid wire is brought into contact with the workpiece 7 and elastically deformed is not used as a processing signal to indicate the position at which the workpiece 7 is detected, but simply as a signal for the movement of the welding torch 2. Since it is used as a stop signal, the sensing operation speed can be made extremely fast, the sensing time can be significantly shortened, and the operating efficiency can be increased. In addition, when the welding torch 2 is moved away from the workpiece 7 at a low speed after stopping the high-speed sensing operation, the separation detection signal obtained when the elastic deformation of the wire is restored (when it separates from the workpiece 7) is detected. , arc welding robot 1
Since it is used as a subsequent control signal,
The desired and accurate workpiece position 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.

Further, in the above embodiment, the case where the present invention is applied to a horizontal fillet joint has been described, but the method of the present invention is not limited to this, and the method can be applied to an automatic method using the welding torch 2 as a sensor. As long as the welding device is used, the same applies to welding various other joints as described above. Further, although the case of three-directional sensing is described, the present invention is not limited to this, and is similarly applicable to weld length sensing, etc. when applied to only one-directional sensing, or when applied to two-directional sensing.

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, in the case of unidirectional sensing, sensing can be performed at any point up to the welding start point, or
In the case of sensing in more than one direction, sensing may be performed at any point up to the next sensing start teaching 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 in the future, if the computing power of the computer is further improved, the moving speed can also be made faster.

[Effects of the Invention] As detailed above, according to the teaching data correction method for an automatic welding apparatus of the present invention according to claim 1, the difference between the teaching data and the actual torch point is calculated at the points after the workpiece detection point. However, the subsequent teaching data is corrected by the difference, and subsequent regeneration operations are executed based on the corrected data, so collisions between the welding torch and the workpiece due to the workpiece displacement during sensing operation, and collisions caused by this This has the effect of being able to correct the position necessary for appropriate welding while correcting the teaching data based on information on the positional deviation of the workpiece, without incurring the burden of teaching operations on the operator to prevent this.

Further, according to the teaching data correction method for an automatic welding apparatus of the present invention according to claim 2, when obtaining the actual workpiece detection point, the energization obtained in the state where the non-rigid consumable electrode is brought into contact with the workpiece and is elastically deformed. The detection output is not used as a processed signal to indicate the detected position of the workpiece, but simply as a stop signal for the welding torch.In addition to allowing the sensing speed to be extremely fast, the welding When the torch is moved away from the workpiece at a low speed, the separation detection signal obtained when the consumable electrode separates from the workpiece is used as a control signal to move the welding torch in the second movement vector direction. Automatic welding equipment can be controlled by detecting the desired exact workpiece position. Therefore, the teaching data correction based on the method of claim 1 and the position correction/correction necessary for proper welding.
Detection takes place extremely quickly and accurately.

[Brief explanation of drawings]

1 to 5 show a teaching data correction method for an automatic welding device as an embodiment of the present invention.
The figure is a flowchart to explain the procedure,
Fig. 2 is a diagram for explaining an example of the movement state of the welding torch according to the procedure of Fig. 1, Fig. 3 is a perspective view showing an arc welding robot to which the method of the present invention is applied, and Fig. 4 is a diagram of the present invention. A perspective view for explaining the teaching operation of the sensing operation in this embodiment, FIG. 5a is a flowchart for explaining another example of the sensing operation in this embodiment, and FIG. 5b is a welding during the sensing operation. FIG. 3 is a diagram for explaining an example of a moving state of a torch. 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... Workpiece, 7a... Vertical plate end surface, 7
b...Vertical plate surface, 7c...Lower plate surface, 8...Positioner.

Claims (1)

[Scope of Claims] 1. Energization detection that selectively applies a welding voltage and a sensing voltage to a consumable electrode type welding torch, and detects the energization state between the consumable electrode protruding from the welding torch and the workpiece when the sensing voltage is applied. By detecting the energization state with the energization detection means, the sensing operation for detecting the position required for welding and the predetermined location of the workpiece to obtain the same position is taught in advance, and the A teaching data correction method for an automatic welding device that executes the sensing operation to correct a position necessary for proper welding, the method comprising:
Calculate and store a first movement vector from the taught sensing start teaching point to the work detection teaching point and a second movement vector from the work detection teaching point to a predetermined teaching point, execute the sensing operation, and perform the sensing operation. The workpiece is detected by moving the welding torch in the direction of the first movement vector and detecting an energization state by the energization detection means, and moving the welding torch by the second movement vector from the workpiece detection position. A method for correcting teaching data for an automatic welding device, comprising: calculating a difference in positional information between the reached point and the predetermined teaching point; and correcting subsequent teaching data based on the calculated difference. 2. When detecting the workpiece 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 workpiece at high speed, and the energization detection means detects the energization state. The operation of the welding torch is stopped based on the detection output, and then the welding torch is moved away at a low speed based on the energization detection output, and separation of the consumable electrode from the workpiece is detected by the energization detection means. 2. The teaching data correction method for 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 direction of the second movement vector.