JPH0523854A - Arc welding robot to carry out weaving operation - Google Patents

Abstract

PURPOSE:To easily change a weaving pattern and welding conditions by storing respective coordinate positional data of a welding torch for one period, reading out contents thereof and converting these into the coordinate positional data of a coordinate system of a robot main body. CONSTITUTION:A welding wire 13 is fitted to the welding torch 12. A weld line 14 is coincident with an X axis, a Y axis is made vertical to the weld line 14 and an axis of the welding wire 13 is coincident with a Z axis. The respective coordinate positional data for one period in a weaving coordinate system are stored in a memory. Further, the welding conditions with the lapse of time for one period are stored in the memory. These stored contents are read out, the quantities of displacement of the respective axes, X, Y and Z and angles, the welding voltage and a welding current are subjected to interpolation operation and obtained. The respective quantities of displacement are transformed by using a coordinate transformation matrix from the weaving coordinate system to a robot coordinate system. The quantities of displacement of the respective axes of the robot main body in the robot coordinate system are calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot for performing arc welding while performing a weaving operation.

[0002]

2. Description of the Related Art When performing an arc welding operation using a robot, it is more preferable to perform welding while weaving in a weaving pattern suitable for the type such as the plate thickness and shape of the target work.

In a typical prior art, when performing a weaving operation to the left and right of a welding line, its amplitude and frequency are given as teaching data and stored in a memory, and the contents of the memory are read and executed. The weaving operation is performed in a state in which the traveling direction of the working end gripping the welding rod and the weaving direction are perpendicular to each other in a two-dimensional plane parallel to the horizontal direction, and the welding conditions remain constant during the weaving operation. . Therefore, the plate thickness of the target work,
There is a problem that arc welding cannot be performed with an optimal weaving pattern that matches the type of shape.

Another prior art is shown in FIG. XY
The intersection of the XY plane and the XZ plane of the Z Cartesian coordinate system is the welding line 1, and the welding torch held at the working end of the multi-axis robot main body has taught the reference points 2, 3 and 4, and these The weaving operation is performed so as to follow each side of the triangle in a plane perpendicular to the welding line 1 formed by the reference points 2, 3, and 4.

In the prior art shown in FIG. 6 as described above,
It is necessary to teach the positions of the reference points 2, 3 and 4 for one cycle in the YZ plane and store them in the memory, which makes the teaching work troublesome and the reference points 2, 3 and 4 are changed. Each time, the teaching needs to be performed again, and the weaving operation cannot be performed with a weaving pattern other than the triangle. Therefore, for example, as shown in FIG. 7 (1), in order to weld the welding lines 5 and 6, it is possible to perform a weaving operation such that the welding torch moves along the path indicated by reference numeral 7. In addition, as shown in FIG. 7B, the weaving operation cannot be performed while swinging the welding torch 9 as indicated by the arrow 10 in the narrow groove of the work 8. Particularly in FIG. 7 (2), when the welding torch 9 is swung as indicated by the arrow 10,
It is necessary to change the welding conditions, such as welding voltage and welding current, or else the welding torch 9 and the work 8
However, there is a problem in that discharge undesirably occurs.

Therefore, in each of the above-mentioned prior arts, there are cases where sufficient welding quality cannot be obtained depending on the welding shape and welding position.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an arc welding robot performing a weaving operation in which the weaving pattern and welding conditions can be easily changed to improve the welding quality. Is.

[0008]

According to the present invention, there is provided a robot main body having a plurality of axes to which a welding torch is attached at a working end,
A memory that stores coordinate position data for one cycle in a weaving coordinate system having multiple axes determined by the welding line and the axis line of the welding torch, and the stored contents of the memory are read out and converted into coordinate position data of the coordinate system of the robot body. In addition, the arc welding robot performing a weaving operation is characterized by including control means for driving the robot body.

Further, the present invention is characterized in that the memory also includes welding control means for storing welding conditions for one cycle and causing the welding torch to perform welding under the welding conditions stored in the memory. .

[0010]

According to the present invention, a welding torch is attached to the working end of a robot body having a plurality of axes, and a weaving coordinate system having a plurality of axes determined by the welding line and the axis of the welding torch is defined. Each coordinate position data for one cycle of the weaving operation of the welding torch in the weaving coordinate system is stored in a memory, and the weaving coordinate system is, for example, the welding line in the XYZ rectangular coordinate system as the X axis, and the axis line of the welding torch. This is the coordinate system when it is matched with the Z axis, and 1 stored in such a memory
Each coordinate position data for the cycle is read and the coordinate position is converted into coordinate position data of the robot body coordinate system using a conversion matrix etc., and each axis of the robot body is converted by the coordinate position data of the robot body coordinate system thus obtained. The displacement amount is calculated and each axis of the robot body is driven by the control means. In this way, the coordinate position data for one cycle in the weaving coordinate system is stored in the memory, and therefore, it is not necessary to perform troublesome teaching work and the amplitude and frequency of the weaving operation can be easily changed to desired values. In addition, the weaving pattern can be easily changed, and the welding shape of the target work and the welding position of the welding torch can be set to desired values, thereby improving welding quality.

Further in accordance with the invention, the memory also includes
Since the welding conditions for one cycle are stored and the welding conditions are read and welding is performed using the welding torch, for example, the arc of the narrow groove described with reference to FIG. Even during welding, the welding work can be performed without causing undesired discharge.

[0012]

1 is a perspective view showing a weaving coordinate system according to an embodiment of the present invention. A welding wire 13 is attached to the welding torch 12, the welding line 14 is aligned with the X axis, the Y axis is perpendicular to the welding line 14, and the axis of the welding wire 13 is aligned with the Z axis. . The welding wire 13 performs a weaving operation with a predetermined weaving pattern while reciprocatingly moving to the left and right of the welding line 14 in a plane parallel to the welding line 14, and moves in the traveling direction 15 along the X axis. The X-axis is the front-back direction of the welding wire 13, the Y-axis is the left-right direction of the welding wire 13, and the Z-axis is the welding wire 13.
Up and down. Furthermore, the welding wire 13 can be angularly displaced about the X axis by an angle θ.

The welding torch 12 is attached to the working end of the robot body 16 shown in FIG. A plurality of (6 in this embodiment) axes JT1 to JT6 can be angularly displaced from the base 30 provided at a fixed position to the working end.

FIG. 3 is a block diagram showing the electrical construction of the embodiment shown in FIGS. 1 and 2. The key input means 18 is connected to the processing circuit 17 realized by a microcomputer or the like, and the processing circuit 17 is provided with a rewritable memory 19. Each axis JT of the robot body 16
Drive sources 20 to 25 are provided to drive 1 to JT 6, respectively. Welding control means 28 is provided for setting the welding conditions of the welding torch 12.

FIG. 4 is a diagram for explaining the operation of the above embodiment. The displacement of the X axis corresponding to the welding line 14 in the weaving coordinate system does not change as shown in FIG. 4 (1), but changes in the Y axis direction as shown by a line 26 of FIG. 4 (2). It is changed in the Z-axis direction as shown in FIG. The angle θ of the welding wire 13 about the X axis is a constant value as shown in FIG. 4 (4).
The memory 19 stores coordinate position data X, Y, Z, and θ for one period T0 in the weaving coordinate system shown in FIGS. 4 (1) to 4 (4). Further, the memory 19 stores the welding conditions with the lapse of time of one cycle T0. The welding voltage as the welding condition is changed as shown in FIG. 4 (5), and the welding current is changed as shown in FIG.
As shown in (6), it changes over time.

The locus of movement of the welding wire 13 in the weaving coordinate system over one period T0 of the welding wire 13 is shown in FIG.
It is shown in simplified form in (7).

The storage status of the memory 19 is shown in Table 1. The time of one cycle T0 of the welding wire 13 is represented by%, and the starting point is defined to start from zero on the X, Y, and Z axes, and the end point is similarly defined to end at zero. The displacement of each axis of X, Y, Z is expressed by a ratio (%) to the amplitude, and each axis X, Y, Z
The amplitude for each is preset by the key input means 18. The time in one cycle T0 is represented by a ratio (%) with one cycle T0 as 100%. For example, with respect to the Y axis, coordinate position data y of the Y axis at times t1, t2, ..., Tn for one cycle.
1, y2, ..., yn are stored, and similarly, the other axes X and Z, the angle θ, and the welding condition, that is, voltage and current are represented at respective ratios, at the same time as in Table 1. It is stored in the memory 19. In one embodiment, the weaving pattern is, for example, on the Y-axis, time 0% and 1
It can be defined with a maximum of 15 points, excluding the point of 00%. The same applies to the other axes X and Z and the angle θ, and the same applies to the welding conditions.

[0018]

[Table 1]

With respect to the Y axis, points y1 to yn in FIG. 4B are set.
The time τi between them is expressed by Equation 1 where the frequency is f. i is a value of 1 to n.

[0020]

[Equation 1]

FIG. 5 is a flow chart for explaining the operation of the processing circuit 17. At the start of one cycle of the weaving operation in step n1, the weaving frequency f input from the key input means 18 is read in the next step n2. In step n3, the time T0 of one cycle is calculated and obtained, and in the next step n4, one cycle T
Clears and starts the timer that performs the clocking operation within 0. At step n5, the stored contents in the weaving coordinate system stored in the memory 14 including the stored contents shown in Table 1 are read out and the displacement amounts Δx, Δy, Δz, Δθ of the respective axes X, Y, Z and the angle θ are read. Further, the welding voltage V and the welding current I, which are the welding conditions, are calculated by interpolation. These interpolation calculations can be obtained from the passage of time for one cycle T0.

At step n6, the displacement amounts Δx, Δy, Δz, Δθ obtained at step n5 are converted using the coordinate conversion matrix from the weaving coordinate system to the robot coordinate system of the robot body 16. Step n7
Then, the amount of displacement of each axis JT1 to JT6 of the robot body 16 in the robot coordinate system is calculated and obtained. At step n8, each of the axes JT1 to JT6 is driven by the drive source 20 so that the displacement of each value obtained at step n7 is achieved.
Driven by .about.25. In step n9, the timer is incremented by (+ T / ΔT).
ΔT is one processing time. In step n10,
It is determined whether or not the time measured by the timer is one cycle T0 or less. If it is T0 or less, the process returns to step n5. When the time measured by the timer exceeds one cycle T0, step n
11, the operation for one cycle is completed, and the weaving operation for the next one cycle T0 is repeated from step n1.

Input to the memory 19 is performed by the key input means 18
And / or teaching.

[0024]

As described above, according to the present invention, the welding torch is attached to the working end of the robot main body having a plurality of axes, and the weaving having a plurality of axes determined by the welding line and the axis of the welding torch is provided in the memory. Each coordinate position data of the welding torch for one cycle in the coordinate system is stored, the contents stored in this memory are read and converted into the coordinate position data of the coordinate system of the robot body, and the coordinate system of this robot body The amount of displacement of each axis of the robot body is calculated based on the above, and each axis of the robot body can be driven to perform the weaving operation with the weaving pattern desired by the welding torch. In this way, the weaving pattern can be set in three dimensions, and the weaving pattern can be stored in memory.
It is not necessary to perform a troublesome teaching work, and the weaving pattern can be easily changed, and thus the welding quality can be improved.

Further in accordance with the invention, the memory also includes
Since the welding conditions for one cycle can be stored and the welding can be performed under the stored welding conditions, it is possible to perform welding without causing undesired electric discharge during welding such as narrow groove. become. The coordinate position data and welding conditions for each one cycle are repeated, and thus the arc welding is performed by repeating the weaving pattern for a plurality of cycles.

[Brief description of drawings]

FIG. 1 is a simplified perspective view illustrating a weaving coordinate system according to an exemplary embodiment of the present invention.

FIG. 2 is a simplified perspective view showing a robot body 16.

FIG. 3 is a block diagram showing an electrical configuration of one embodiment of the present invention shown in FIGS. 1 and 2.

FIG. 4 is a diagram for explaining the operation of the embodiment of the present invention.

5 is a flowchart for explaining the operation of the processing circuit 17. FIG.

FIG. 6 is a sectional view for explaining the prior art.

FIG. 7 is a diagram for explaining a weaving pattern.

[Explanation of symbols]

12 Working end 13 welding torch 14 Weld line 16 Robot body 17 Processing circuit 18 key input means 19 memory 20-25 Drive source for each axis 28 Welding control means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideki Ninobu             1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries             Akashi Factory Co., Ltd. (72) Inventor Masaki Tanaka             3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe             Saki Heavy Industries, Ltd.Kobe factory

Claims (2)

[Claims] 1. A robot body having a plurality of axes to which a welding torch is attached at a working end, and coordinate period data for one cycle in a weaving coordinate system having a plurality of axes determined by a welding line and an axis of the welding torch are stored. An arc welding robot performing a weaving operation, comprising: a memory; and a control means for reading the stored contents of the memory to convert the coordinate position data of a coordinate system of the robot body to drive the robot body. 2. The memory also includes welding control means for storing welding conditions for one cycle and causing the welding torch to perform welding under the welding conditions stored in the memory. An arc welding robot that performs the described weaving operation.