JPS6344471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a welding arc detector.

The welding groove that is the target of arc welding has a die groove as shown in Figure 1, for example.
It may be bent as shown in the dot. When attempting to weld such a groove 1, a method is used in which welding is performed while detecting the groove 1 using an ITV that detects the welding arc, or a photoelectric detector such as an image sensor, a phototransistor array, or a solar cell array. However, with this type of conventional method, it was not possible to accurately determine the weld groove width. That is, Fig. 2 shows an example of a conventional automatic welding machine, and the welding torch 2 is an NC
The X-axis and Y-axis are controlled according to data, and the y-axis is used to correct the error amount (displacement between welding torch 2 and welding groove 1) detected by welding arc detector 3.
Position control is performed by the axis. Conventionally, the welding arc detector 3 is fixed to the welding torch 2 (the welding arc detector 3 is oriented along the X axis). , It was not possible to accurately measure the weld groove width at a bent point such as point A. This means that if the direction of the welding arc detector 3 matches the direction of the welding groove 1 as shown in Figure 3a, the width Yp of the detected image will be is equal to the width Yw of
As shown in figure c, when the direction of welding arc detector 3 and the direction of welding groove 1 no longer match, the width of the detected image becomes Yp≠Yw as shown in figure d,
Moreover, the image of the arc may be partially obscured by the edge of groove 1.

Therefore, Japanese Patent Publication No. 51-17138 discloses a technique in which the angle of deviation of the welding arc detector 3 with respect to the direction of the welding groove 1 is detected and the detector 3 is rotated around the welding torch so that this angle of deviation becomes zero. However, since the technique according to this prior application detects the above-mentioned deviation angle based on an image of the welding arc, it has the following drawbacks.

That is, the accuracy of detecting the declination angle is low due to fluctuations in the image caused by arc fluctuations and the like.

Additionally, if the welding groove is bent at an angle smaller than 90°, the arc image cannot be captured accurately, and the welding arc detector rotates in the opposite direction to the bending direction of the welding groove, causing the torch to Copying control becomes impossible.

Furthermore, it is necessary to arrange a large number of photoelectric elements on the projection surface of the welding arc detector, and furthermore, it is necessary to prepare a processing circuit to process the output of these photoelectric elements, so the configuration is complicated. It becomes expensive.

An object of the present invention is to solve such conventional problems. Therefore, the present invention provides a welding arc detector which is rotatably supported around a welding torch and moves along a welding groove together with the welding torch to detect a deviation of the torch from the welding groove; In the welding arc detection device, the welding arc detection device is provided with a means for controlling the welding torch in a tracing manner so as to eliminate deviation, and a rotation angle command value for aligning the welding arc detector in the direction of the welding groove is determined by the X of the welding torch. a calculation means for calculating based on the axis movement command value and the Y-axis movement command value; and a control means for controlling the rotation angle of the welding arc detector based on the rotation angle command value calculated by the calculation means. I am trying to set up a.

The present invention will be described in detail below based on an embodiment of the accompanying drawings.

In FIG. 4, the welding robot 10 corrects the X-axis and Y-axis controlled according to NC data and the error amount (displacement between the welding torch 12 and the welding groove 11) detected by the welding arc detector 13. The welding torch 12 attached to the tip of the y-axis can be positioned at any location. The welding arc detector 13 is attached to the welding torch 12 so as to be rotatable about the welding torch 12 on the XY plane. That is, in the example shown in FIG. 4, the gear 14 is fixed to the welding torch 12, the rotary ring 15 is rotatably attached to the welding torch 12, the arm 15' is extended from the rotary ring 15, and the motor is connected to the arm 15'. 1
6 and ITV13 are fixed. Then, a gear 17 is attached to the motor 16 so that it meshes with the gear 14. With such a configuration, by controlling the motor 16, the welding arc detector 1
can be positioned at any angle on the XY plane with the welding torch 12 as the center. This positioning axis is hereinafter referred to as the T-axis.

FIG. 5 shows an example of a control circuit that controls the direction of the welding arc detector 13 in the direction of the welding groove 11 based on the control of the T-axis. The example in Figure 5 is the X axis, Y axis
The control amount of the T-axis is calculated based on the movement command values ΔX and ΔY of the axes.

In FIG. 5, a central control circuit 20 is a circuit that outputs various signals for operating the automatic welding machine 10 of FIG. 4. The X-axis control circuit 21 controls the X-axis according to NC data. That is, in the X-axis control circuit 21, the position detector 22
detects the X-axis position of automatic welding machine 10, and subtractor 2
3 takes the deviation between the NC data regarding the X-axis outputted from the central control circuit 20 and the detected position value, and applies the deviation to the drive motor 25 via the amplifier 24 to control the X-axis. The Y-axis control circuit 26 controls the Y-axis according to NC data. That is, in the Y-axis control circuit 26, the position detector 27
detects the Y-axis position of automatic welding machine 10, and subtractor 2
Reference numeral 8 calculates the deviation between the NC data regarding the Y-axis outputted from the central control circuit 20 and the detected position value, and applies the deviation to the drive motor 30 via the amplifier 29 to control the Y-axis.

The T-axis control circuit 31 receives a movement command value (ΔX) regarding the X-axis and a movement command value (ΔY) regarding the Y-axis.
This is a circuit that controls the T-axis by determining the control amount θt of the T-axis based on the following. That is, in the T-axis control circuit 31, the T-axis control amount calculation circuit 32 determines the T-axis control amount θt based on the X-axis and Y-axis movement command values ΔX and ΔY. This control amount θt can be obtained as θt=tan ⁻¹ ΔY/ΔX. The obtained angle θt is used as an angle command value regarding the T-axis (the direction along the X-axis is defined as 0°). That is, the angle detector 3
3 detects the actual angle of the T-axis using, for example, a pulse encoder, and a subtracter 34 takes the deviation between this angle detection value and the above-mentioned angle command value θt, and outputs the deviation to an amplifier 35.
In addition to the drive motor 16, the Y-axis is controlled via the drive motor 16. Thereby, the orientation of the welding arc detector 13 is controlled in the direction along the welding groove 11.

The welding control circuit 36 ignites the welding torch 12 based on a welding arc ignition command (usually given in the form of a pulse) from the central control circuit 20 .

The tracing control circuit 40 is for controlling the y-axis. In the tracing control circuit 40, an error detector 41 detects the deviation (error) between the welding groove 11 and the welding torch 12 based on the detection by the welding arc detector 5.
Calculate by calculation. The command switching circuit 42 selects either the obtained error or the origin command data from the central control circuit 20 and applies it to the subtracter 43 . Here, the origin command data is data for returning the y-axis position to its origin. A subtracter 43 calculates the deviation between the actual position of the y-axis detected by the position detector 44 and the position command from the command switching circuit 42, adds the deviation to the motor 46 via an amplifier 45, and
Controls the axis position to the commanded position.

Another embodiment of the control circuit for controlling the orientation of the welding arc detector 13 in the direction of the welding groove 11 is shown in FIG. In the example shown in FIG. 6, the T-axis command value θt is given as a separate numerical command.

In FIG. 6, the central control circuit 50 is similar to the central control circuit 20 in FIG.
This is a circuit that outputs various signals to operate the. The X-axis control circuit 51 is the X-axis control circuit 2 in FIG.
X from the central control circuit 50
The X-axis position is controlled according to the axis movement command value ΔX.
The Y-axis control circuit 52 is configured similarly to the Y-axis control circuit 26 in FIG. 5, and controls the Y-axis position in accordance with the Y-axis movement command value ΔY from the central control circuit 50.

The T-axis control circuit 53 receives the T-axis from the central control circuit 50.
The angle θ of the T-axis is controlled according to the axis angle command value θt. That is, in the T-axis control circuit 53, the angle detector 54 detects the T-axis angle (direction of the welding arc detector 13) θ, and the subtractor 55 detects the angle θ of the T-axis (direction of the welding arc detector 13).
The deviation between the command value θt regarding the T-axis output from 0 and the detected value θ is calculated, and the deviation is applied to the motor 16 via the amplifier 56 to control the T-axis.

The welding control circuit 57 ignites the welding torch 12 based on a welding arc ignition command from the central control circuit 50.

The copying control circuit 60 is the copying control circuit 40 in FIG.
It is configured in the same way as , and controls the y-axis by tracing.

In addition to the method shown in Figs. 5 and 6, the T-axis can be controlled by calculating the command angle θt of the T-axis in the central control circuit based on the command data of the circular arc or linear interpolation of the X- and Y-axes. You can do it like this.

As explained above, in the present invention, the rotation angle command value for aligning the welding arc detector along the welding groove is obtained based on the X-axis movement command value and the Y-axis movement command value of the welding torch. Therefore, the welding arc detector can be aligned in the direction of the welding groove with extremely high precision without being affected by arc light fluctuations or the like.

Further, even when the welding groove is bent at an acute angle, the torch can be placed along the direction of the bending of the welding groove.

Furthermore, in the present invention, since the rotation angle command is not created based on the output of the arc detector, it is only necessary to provide the arc detector with two photoelectric elements for detecting the amount of horizontal deviation of the torch. Therefore, the cost of the welding arc detector and the circuit for processing its output can be reduced.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a welding groove in a welding workpiece, Fig. 2 is a perspective view showing a conventional installation state of a welding arc detector in a welding robot, and Fig. 3 is a perspective view showing an example of a welding groove in a welding robot. 4 is a perspective view showing an embodiment of the present invention; FIG. 5 is a block diagram showing an example of the control system of the embodiment shown in FIG. 4; FIG. 6 is a diagram showing an example of the control system of the embodiment shown in FIG. FIG. 3 is a block diagram showing another example of the control system of the embodiment. 10... Welding robot, 11... Welding groove, 12
...Welding torch, 13 ...Welding arc detector, 1
4, 17...gear, 15...rotating ring, 15'
...Arm, 16...Motor, 31,53...T
Axis control circuit.

Claims (1)

[Scope of Claims] 1. A welding arc detector that is rotatably supported around a welding torch and moves along a welding groove together with the welding torch to detect deviation of the torch from the welding groove. In the welding arc detection device, the welding arc detecting device includes a means for tracing and controlling the welding torch so as to eliminate the deviation, and a rotation angle command value for aligning the welding arc detector in the direction of the welding groove is set by the welding torch. a calculation means for calculating based on the X-axis movement command value and Y-axis movement command value; and controlling the rotation angle of the welding arc detector based on the rotation angle command value calculated by the calculation means. A welding arc detection device comprising a control means.