JPS6319269B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for tracing a welding torch for narrow grooves, which makes it easy to adjust the position of the welding torch during groove welding.

Generally, when welding objects to be welded such as thick plates, it is very difficult to adjust the relative position between the welding torch and the groove because the groove width is narrow. For this reason, there has been a demand for the development of a tracing method that allows for easier position adjustment of the welding torch between grooves that are narrower than before.

The present invention has been made in view of the above-mentioned circumstances. By detecting the arc light of the welding torch in the groove width direction with a light detection unit, the center of the welding torch can be easily adjusted to the center of the groove. The purpose of the present invention is to provide a method for copying a tip welding torch.

Hereinafter, one embodiment of the present invention will be described with reference to FIG. In the figure, 10L and 10R are objects to be welded having narrow grooves 11, and a welding torch 12 is inserted into the grooves 11 of these objects to be welded 10L and 10R, and an arc 13 is emitted from the electrode 12a to separate the groove portions. Perform welding. Therefore, welding torch 1
At least one optical fiber 14L, 14R for detecting arc light is attached to both sides of 2, respectively. In addition, the optical fibers 14L, 14
It is assumed that the light receiving surfaces 15L and 15R of R are set at positions where they are not affected by heat due to welding, spatter, etc. 16 is a terminal block,
At least two holes are bored in this, and the optical fibers 14L, 14 are attached to one end of these holes.
The other end of R is individually inserted, and light receiving elements 17L and 17R are attached to the other end. These light receiving elements 17L, 17R are optical fibers 14L,
After detecting the arc light transmitted through 14R and converting it into electrical signals, the converted outputs are supplied to the positive input terminal and negative input terminal of the comparator circuit 18 shown in FIG.

FIG. 2 is a diagram showing a torch movement control system applied to the welding torch center tracing method.
The outputs of L and 17R are compared and positive and negative deviation signals are output. In the figure, 19 is a low-pass filter that removes noise signals, 20 is an amplifier, and 21 is an amplifier 20.
This is a torch movement control motor that controls the movement of the welding torch 12 to the right or left side via the torch arm 22 depending on the level of positive or negative output.

According to the apparatus to which the above method is applied, when the welding torch 12 is located approximately at the center of the groove width as shown in FIG.
Electrodes 12 are placed on the light receiving surfaces 15L and 15R of L and 14R.
The arc light emitted from a is received in approximately the same amount of light. For this reason, the same optical fiber 14L,
Since the signal levels photoelectrically converted by the light receiving elements 17L and 17R via the light receiving element 14R are equal, the deviation output of the comparator circuit 18 becomes zero, and the welding torch 12 is set at the current position without moving.

Next, when the welding torch 12 is biased to the right side of the groove width as shown in FIG.
Since the optical fiber 14L on the left side of R receives a larger amount of arc light, the output of the light receiving element 17L becomes larger than the output of the light receiving element 17R. Therefore, a positive deviation signal is output from the comparator circuit 18, which is supplied to the torch movement control motor 21 via the low-pass filter 19 and the amplifier 20. As a result, the motor 21 controls the welding torch 12 to move to the left, and stops when the welding torch 12 reaches the center of the groove width.

On the other hand, when the welding torch 12 is biased to the right side as shown in FIG. 5, the welding torch 12 is moved to the center of the groove width by performing an operation completely opposite to that shown in FIG. 4. Incidentally, FIG. 6 shows the set position locus A of the welding torch 12 in scanning the center of the groove.
y ₁ and y ₂ are the distances between the groove surface and the side surface of the welding torch 12. Furthermore, Z indicates the longitudinal direction of the groove, X indicates the lateral direction of the groove, and Y indicates the width direction of the groove.

Next, an example of the experimental configuration will be described. One optical fiber 14L on each side of the welding torch 12,
After attaching 14R, the same optical fiber 14L, 1
The light is received by 4R and converted into an electrical signal by light receiving elements 17L and 17R installed approximately 30 cm apart. Light receiving surface 15 of optical fibers 14L and 14R
L and 15R are electrode 1 to avoid the heat of welding arc.
It was set 10 cm above the base of 2a. The maximum angle of the arc receiving surfaces 15L and 15R is the optical fiber 14.
Although it is determined by the refractive index of the core portion and cladding portion of L and 14R, it was set to 120° in an experimental example. Furthermore, the two light receiving elements 17L, 17R and a variable resistor (not shown) constitute a bridge circuit that can adjust the balance, and the differential output is taken out and amplified by an amplifier 20, which is used to control the motor for torch movement control. 21 was supplied. Then, the welding torch 12 was controlled to move to the center of the groove width. In this case, the test was performed on a butt test piece with a plate thickness of 65 mm, a gap of 11 mm, and a weld of 350 mm. The weld line was 350 mm long and shifted 4 mm from the traveling trolley, and the TIG non-filler was used to run the weld line back and forth, and the displacement at that time was measured using a potentiometer.

In this experimental example, the welding torch 12 traced the inside of the groove while repeating swings of about 0.5 mm. The trajectories of the outbound and return trips matched and had high reproducibility. Moreover, the position of the welding torch 12 could be accurately controlled without noise.

As described in detail above, according to the present invention, optical fibers are attached to both sides of the welding torch, and the position of the welding torch is controlled while detecting arc light in the groove width direction with these optical fibers. It is possible to present a method of tracing a welding torch for narrow grooves, which is capable of reliably tracing the center of a groove with a simple configuration.

[Brief explanation of the drawing]

FIGS. 1 to 6 are diagrams illustrating a tracing method for a narrow gap welding torch according to the present invention;
The figure is a perspective view showing the welding state in a narrow groove, Figure 2 is a configuration diagram explaining the groove center scanning method, and Figures 3 to 5 are the position of the welding torch within the groove width and the arc light reception. FIG. 6 is a diagram showing the movement locus of the welding torch in the groove center tracing method. 10L, 10R... object to be welded, 11... groove,
12...Welding torch, 13...Arc, 14L,
14R... Optical fiber, 17L, 17R... Light receiving element, 18... Comparison circuit, 21... Torch movement control motor.

Claims (1)

[Claims] 1. In a device that performs welding by inserting a welding torch into the groove of the workpiece, a light detection section is provided on each side of the welding torch, and these light detection sections are used to detect arc light in the groove width direction. A welding torch for a narrow gap is characterized in that the welding torch is controlled to move in the groove width direction by controlling a torch movement control motor based on the comparison result of both arc light detection signals. Method.