JPS6036862B2 - How to control automatic welding machine - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method of controlling an automatic welding machine, and more particularly to a method of controlling a welding machine using a robot that is adaptable to dimensional errors and installation errors of the welding machine. .

[Background of the Invention] Figure 1 shows an example of an automatic welding device using an industrial robot, in which 1 is the industrial robot, 2 is its arm, 3 is an arc welding torch attached to the tip of the arm 2, and 4 is an example of an automatic welding device using an industrial robot. is a conduit for guiding welding wire, carbon dioxide gas, etc. to the torch 3.

The industrial robot 1 has multiple degrees of freedom, such as driving an arm 2 in the front and back, up and down, and lateral directions, and bending the wrist at the tip of the arm. Reference numeral 5 denotes a workpiece to be welded, which is fixed and positioned on a positioner 6.

FIG. 2 is a block diagram of a control device for a playback type industrial robot used for this purpose, in which 11 to 13 are servo calendars corresponding to each axis of the industrial robot, 14 is an arithmetic and control device, and 15 is a storage device. To briefly describe the operating method of such an automatic welding machine, during teaching, the operator gives position commands to the servo devices 11 to 13 via the arithmetic and control unit 14, and drives each axis of the robot to move the molten acid wire. The corresponding torch is positioned and stored in the position data storage device 15 at that time, and a series of operations are memorized using this procedure. During playback, the arithmetic and control unit 14 sequentially reads position data in the storage device 15,
It performs processing such as interpolation calculations, gives position commands to the servo devices 11 to 13, and performs a series of taught operations in which the torch 3 is driven. In such an automatic welding machine, torch 3
The trajectory is faithfully reproduced within the accuracy of the industrial robot 1 according to the position data in the storage device 15.

However, the position of the welding line to be worked on on the workpiece 5 is
Due to positional errors of the positioner 6, attachment errors of the workpiece 5 to the position 6, dimensional errors of the workpiece 5, etc., the position is not necessarily the same as that at the time of teaching. If welding is performed using an automatic welding machine with such a positional error of the welding line, the quality will deteriorate to such an extent that it cannot be put to practical use. In particular, the positional deviations do not always occur in parallel, and the errors in the workpiece dimensions do not necessarily occur uniformly in each part. Therefore, it is desirable to appropriately check and correct any positional deviations and dimensional errors. [Object of the Invention] An object of the present invention is to provide a control method capable of improving the drawbacks of the above-mentioned follower technology and performing check control with high work accuracy that can sufficiently adapt to any positional error.

[Summary of the invention]

A series of welding work on the welded material is divided into a plurality of linear units, and torch position data is taught and stored at multiple points in the divided linear work units, and the data is read out at the time of playback and checked at the check line (CL). ), move the torch along the welding line, measure the torch position corresponding to the welding line using a position detection means linked to the torch for two teaching points for each linear work unit, and determine the straight line by connecting the two actual measurements. The feature is that the welding is performed by correcting the torch position data of the divided hot saddle work castle.

[Embodiments of the invention]

Next, the present invention will be explained in detail using the drawings.

FIG. 3 is an explanatory diagram of an example of welding line detection means, 21, 22
is a welding base, 23 is a torch, 24 and 25 are a pair of base metal detectors, and when both base metal detectors 24 and 25 detect that they are at the optimal position with respect to the base metals 21 and 22, The torch 23 constitutes a weld line detector 26 arranged at an optimum position with respect to a weld line 27 at the joint between the base materials 21 and 22. Therefore, by positioning the torch 23 at the optimal position using this welding line detector 26 and importing the position data of each axis of the robot at that time, the position data of the welding line 27 converted to each axis of the robot is actually measured. can do. Hereinafter, the welding line position data converted to each axis will be simply referred to as welding line position data. Figure 4 shows the work procedure for the welding line, where P6 is the origin of the robot defined in a certain range of space, and the thick line indicates that the robot is at the origin when the welding torch 23 is positioned at this origin. The welding line WLI represented by is stored in the robot as torch position data corresponding to the teaching points Pa, to Pa6, and the robot is separately stored with retreat points Pt, , P, etc. before and after welding work. The welding work starts from the origin Po and moves to the point Pt,
After passing through the welding line WLI, the torch 23 is moved along the torch position corresponding to the welding line WLI stored at the teaching points Pa to Pa6 to perform welding. Here, Pa, one P that constitutes WLI
a2, Pa2-Pa3, Pa3-Pa4, Pa4-Pa
5, Pa5-Pa6, is a welding work castle (unit) divided into linear units.

The welding line WL2 shown in bold in FIG. 5 is at the check point Pc.
、． ~Pc2o and points other than the check points Pa, . ~Pa,
It is taught as torch position data corresponding to Pt, . , Pt,2 have been taught. In this case, first, the welding line W stored in the storage device 15 is
All teaching points Pc, . of L2. ~Pcyo, Pa,. ~Pa
, 4, a check trajectory CL is calculated from the welding line WL2 by a certain distance, and the torch 23 is moved along this check trajectory CL starting from the origin Poo, and each linear welding unit is , the weld line WL2 is detected using the weld line detector 26 at each two check points.
Measure position data. However, Pc,. '～Pc2
When the check work is completed for all of the check locus CL of o', the process returns to the origin via the retreat point Pt,2. Here, check points Pc, . ~Check point Pc stored in the measured position data storage device 15 of Pc2o,
．． ~Pc Used in place of the position data of the arc. For example, Pc,
．． -Pc, 2, Pc. 3-Pc, 4, etc. are connected by straight lines, and other points are memorized, for example, Pa.
、． , Pa, 2, etc., the outside of the position data is corrected. In this way, the position of the welding line WL2 is actually measured and the position and deviation of the welding line on the workpiece to be welded is corrected. Thereafter, the torch 23 is moved from the origin Poo to Pt, . ,Pc,
．． Welding is performed while accurately tracing the welding line WL2. FIG. 6 is a diagram for explaining the method of correcting the positional deviation of the weld line using the above-mentioned actually measured position data.
WLt indicated by a broken line is the welding line being taught,
The position of the check point actually measured during the check work is Pc,
．． ″~Pc2o″, then Pc, . ″, Pc
, 2'' to find the line segment L, Pc, 3'', Pc,
The actual welding line WLa (solid line) can be determined from the actually measured position data by connecting 4 to determine the line segment L2. As is clear from the comparison between the dotted line and the solid line in Figure 6,
Installation error that cannot necessarily be said to be parallel movement (e.g. rotation)
Even in such cases, corrections are possible.

The welding line position is actually measured and corrected using a torch for the two teaching points on the straight line divided in this way. 7th
The figure is a flowchart of the control method described above, and the arithmetic and control unit 14 causes the position detection work and the welding work using the torch to be performed in this order.

That is, block 28 checks whether the position of the welding torch has returned to the predetermined origin within the work area.

The block 29 receives teaching data for one work unit from the storage device 16 (teaching line WL2 shown in FIG. 5, and each work unit is as shown in FIG. 9b).

) is read out. The block 30 is for determining whether the workpiece has a check point or not. If there is no checkpoint, that is, for the workpiece shown in FIG. 4, the process proceeds to block 38.

However, in the present invention, a check point is always provided for each unit of linear work, so the process does not proceed directly from ◎ to block 38. The block 31 is for calculating the layer data of the check locus (Pc, ,' to Pc2o' shown in FIG. 5).

The block 32 drives the torch along the check trajectory calculated in the block 31.

Block 33 determines, when the torch advances from the origin Poo and reaches a predetermined point (for example, Pt, .), whether or not it is a check point (in this case, the process proceeds to block 35).

Note that information regarding predetermined check points is given, for example, as shown in FIG. 9a. Block 34 is for actually measuring position data using a sensor, in which case the sensor is shown in FIG.
, is placed at the position. Note that C2 indicates the relative position during welding. The flock 35 is for determining whether or not the work on the workpiece has been completed in one work unit.

Block 36 is for checking whether the torch has returned to its original position upon completion of the position inspection work.

Block 37 includes actually measured position data (Pc shown in FIG.
．． The teaching data (WLa) in the storage device 15 is corrected using the data ``~Pcsha'').

The flock 38 is used to perform workpiece welding work.

The flock 39 is used to check whether the torch has returned to its original position upon completion of the welding work.

The steps of blocks 28 to 39 are carried out by the arithmetic and control unit 14 to perform the random work.

As is clear from the above description, according to the present invention, positioning errors of a table such as a positioner or conveyor on which a work is mounted, errors in mounting the work on the table, dimensional errors of the work itself, positioning errors of the robot, etc. The positional error between the taught welding line and the actual welding line caused by various factors is checked at two points per work unit using a welding line detection means, and the welding line position data is collected at two points. After actually measuring the position, the torch position data can be corrected based on the measured position data, and the welding line can be traced correctly to perform high-quality welding.

In addition, since the welding work is divided into straight lines, there is little effect on welding distortion, and teaching is easy.
Accidents due to poor teaching can be prevented. In other words, the path taught to the robot is exactly the same whether there is a check operation or not. Furthermore, the program can be easily modified for each work unit. [Effects of the Invention] According to the present invention, it is possible to perform welding by correcting the post-welding line position in linear units with high accuracy.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an example of an automatic welding machine, Fig. 2 is a block diagram of the controller of an industrial robot, Fig. 3 is a welding line detector, and Figs. Figures 7a and 7b are flowcharts of the control system according to the invention, Figure 8 is a diagram showing the position of the torch, and Figure 9 explains teaching data and work units. It is a diagram. 1...Industrial robot, 2...Arm, 3...・Welding torch, 4... Conduit, 5... Work, 6... Position, 1
1 to 13...Servo device, 14...Arithmetic control device, 15...Storage device, 21...
Base metal, 22...Base metal, 23...Welding torch, 24...Base metal detector, 25...Base metal detector, 26... ...Welding line detector, 27...
welding line. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. Control of an automatic welding machine that performs automatic welding using a playback method and is equipped with an arithmetic control device that controls the position of the torch by giving a position command signal to a servo device based on torch position data corresponding to a welding line stored in a storage device. In the method, a series of welding operations on a workpiece to be welded is divided into a plurality of linear units, and torch position data is taught and stored at a plurality of points in the divided linear units,
At the time of playback, the taught data is sequentially read from the storage device and the torch is moved along a check line (CL) retreated by a predetermined distance from the taught position data, and two teaches are performed for each linear work unit. The torch position corresponding to the welding line is actually measured by a position detection means that moves the torch about a point, and the torch position data of the divided straight line welding work area is corrected by a straight line connecting the two detected values, and the corrected torch position is A method of controlling an automatic welding machine characterized by performing welding based on data.