JPH07112277A - Arc welding method for groove width variation - Google Patents

Abstract

PURPOSE:To change the relative welding speed for a work weld line and to maintain the bead height constant by detecting the arc voltage or a welding current to compare it with a reference value and reversing the operating direction of arc oscillation. CONSTITUTION:The welding current is detected and arc welding is performed by articulated robot and a controller for a groove part 1 of works M. Welding is started with the proceeding speed Vo and a proceeding angle alpha of a welding torch for a welding center line AB extending from a welding starting point A to a welding finishing point B. The arc voltage or the welding current is detected to compare it with the reference value and the operating direction of arc oscillation is reversed, by which the relative welding speed for the work weld line is changed and the bead height is maintained constant without changing the welding speed at the time of welding. Consequently, the bead height can be maintained constant without using a complicated arithmetic unit and further, weld line profiling also can be performed at the same time by performing groove width profiling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding method in which an arc is oscillated to control a welding speed so that a bead height is kept constant in response to a change in groove width.

[0002]

2. Description of the Related Art As an arc welding method using an arc sensor method for keeping a bead height constant against groove width variation, a method of welding using a welding torch having a variable rotating diameter has been proposed. (See, for example, JP-A-5-23856). In this arc welding method, the bead height is made constant by adjusting the radius of gyration with respect to the groove width and the welding speed for the work.

[0003]

However, in the above arc welding method, the bead height is made constant by adjusting the radius of gyration with respect to the groove width and the welding speed with respect to the work. Therefore, the speed of the tip of the welding wire with respect to the workpiece fluctuates, the welding state becomes unstable, and spatter increases.

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a welding method with respect to a groove width variation capable of keeping the bead height constant in a stable welding state. .

[0005]

In order to achieve the above object, a welding method for groove width variation according to the present invention is an arc welding method for welding while swinging the arc when the groove width varies. , The arc voltage or welding current is detected, and the operating direction of arc oscillation is reversed by comparing with the reference value to change the welding speed relative to the workpiece welding line without changing the welding speed during welding. It is characterized by making the bead height constant.

[0006]

As described above, according to the present invention, the moving speed of the welding torch and the arc rotation radius are set to a constant value in advance to make the speed of the tip of the welding wire relative to the work constant and change the speed during welding. Do not let As a result, the welding state is stable and spatter can be reduced. Moreover, by detecting the arc voltage or the welding current and comparing the value with the reference value and reversing the tip of the welding wire with respect to the center of the welding line, the operation direction of the arc rocking is reversed and rocked.
The bead height is kept constant by changing the welding speed relative to the work welding line.

[0007]

EXAMPLES The present invention will be described below with reference to examples in which a welding current is detected to arc-weld a work groove. 1 is a plan view showing a target work, FIG. 2 is a cross-sectional view of the target work of FIG. 1, FIG. 3 is a partial view of a groove portion of the target work and an explanatory view showing a detected current change, and FIG. 4 is an opening view of the target work. FIG. 5 is a plan view showing another example of the target work, FIG. 5 is an explanatory view showing a weaving operation of the groove part of the target work, and FIG. Is. Arc welding is performed on the groove portion 1 of the work M as shown in FIG. 1 by detecting a welding current by a well-known articulated robot and a control device (not shown).

The control device includes a welding start point A, a welding end point B, a turning-back welding current reference value I ₀ , a welding torch moving speed V ₀ , a welding torch moving angle α (<90 °), and a turn-back minute radius R. Is defined in advance, set and input. The welding current I is detected by a detector (not shown) and input to the control device.

First, with respect to the welding center line AB extending from the welding start point A to the welding end point B, welding is started at the traveling speed V ₀ and the traveling angle α. The detected welding current I first gradually increases as the groove wall 2 or 3 is approached, as shown in FIG.

When the welding is continued, the welding torch approaches the groove wall 2 and the detector detects that the arc current has reached the reference value I ₀ of the folded welding current, and inputs it to the control device. When this reference value I ₀ is input, the control device advances the welding torch on the circular arc having the small turning radius R at the speed V ₀ . The rotation of the welding torch on this arc goes in the direction of the welding center line AB when the position is away from the welding center line AB. As shown in FIG. 4, if the clockwise direction is negative,
The rotation of the welding torch is angled at -α and continues to the angle -α. When the angle reaches -α, the welding torch is changed from the rotary motion to the linear motion and is moved straight in the tangential direction of the angle -α.

When the welding is further continued, the welding current I decreases, reaches the minimum value when the welding torch passes the welding center line AB, and the welding current I increases again. Then, when the welding torch approaches the groove wall 3 and the reference value I ₀ is input to the control device, the welding torch is folded back in the opposite direction this time in front of the groove wall 3 as described above. , The same operation as above is performed at an angle α on an arc having a minute radius R. As a result, the rocking motion is performed.

When the welding torch is along the welding center line AB, the advancing direction of the welding torch is at an angle of α or -α from the welding center line AB and approaches the groove wall 2 or 3, When the arc current reaches the reference value I ₀ and continues to a predetermined position in front of it, as described above, the arc rotates on the circular arc having the small turning radius R until it reaches the angle α or −α. Then, when the angle α or −α is reached, the welding torch is changed from the rotary motion to the linear motion and is moved straight in the tangential direction of the angle α or −α.

When the return welding current reference value I ₀ or more is detected, the traveling direction of the welding torch is directed to the center of the welding line.

In the case of a work having a varying groove width as shown in FIG. 5, the actual welding line is as shown in FIG. In this case, if the maximum groove width is W and the angle between the groove line and the welding line is θ, the actual travel distance L of the torch and the welding line center length Δ.
L is represented by the following equation. L = K ₁ (W, θ, R, α) (1) ΔL = K ₂ (W, θ, R, α) (2) Therefore, the relative speed of the work is expressed by the following equation. . V = K ₂ (W, θ, R, α) / (K ₁ (W, θ, R,
α) / V ₀ ), and if the groove width changes, the relative welding speed V with respect to the work also changes. Therefore, the welding speed V corresponds to the groove width, and a stable bead height can be obtained.

[0015]

According to the present invention, the bead height can be made constant by changing the relative welding speed with respect to the work welding line without using a complicated arithmetic unit. Further, by performing the groove width tracing, the welding line tracing can be performed at the same time.

[Brief description of drawings]

FIG. 1 is a plan view showing a target work for implementing a welding method according to the present invention.

FIG. 2 is a cross-sectional view of the target work of FIG.

3A and 3B are a partial view of a groove portion of the target work of FIG. 1 and an explanatory view showing a detected current change.

FIG. 4 is a partial view for explaining a swinging operation direction of a groove portion of a target work and an explanatory view showing a detected current change.

FIG. 5 is a plan view showing another example of the target work.

FIG. 6 is an explanatory view showing a swinging operation of the groove portion of the target work in FIG.

[Explanation of symbols]

 1: groove part 2, 3: groove wall M: work

Claims (1)

[Claims] 1. An arc welding method for welding while oscillating an arc when a groove width changes, in which an arc voltage or a welding current is detected, and an operating direction of arc oscillation is reversed by comparing with a reference value. Thus, the arc welding method with respect to the groove width variation is characterized in that the bead height is made constant by changing the relative welding speed with respect to the work welding line without changing the welding speed during welding.