JPS6384775A - Weld line follow-up controlling method for welding torch - Google Patents

Abstract

PURPOSE:To follow a weld line with high accuracy by comparing the difference of integration values in the specific range which are calculated from arc voltage waveforms, etc., detected at a front point and a rear point in the welding proceeding direction with a predetermined reference value in the arc welding rotating at a high speed. CONSTITUTION:The welding is performed following the weld line 3 while rotating at a high speed an arc 9 of the tip of a welding wire 8 while rotating an electrode nozzle 4. At this time, the integration values of the arc voltages or the welding current waveforms in the range of a prescribed angle in the range of + or -2.5-+ or -90 deg. with the front point (cf) and the rear point (cr) in the welding proceeding direction as centers are calculated and the difference between the respective integration values (SCf - SCr) is compared with the predetermined specific value and controlled. The weld line is followed and controlled with the high accuracy by this method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a welding torch to follow a welding line in high-speed rotating arc fillet welding performed along a curved welding line.

[Conventional technology]

Conventionally, when automatically performing fillet welding of T-joints, corner joints, etc., the welding electrode is made to follow the groove route by tracing the groove using an arc sensor, for example.

[Problem that the invention seeks to solve]

Conventionally, for example, in a welding joint where the weld line 3 of the lower plate 1 and the upright plate 2 is bent to the left as shown in FIG. 11, while moving the welding torch 4 in the direction of the arrow 5 along the weld line O, When welding automatically, welding torch Ah - bending point The welding torch 4 has a receding angle θ with respect to the welding line 3. Since the welding line 3 is bent in this way, if the torch angle of the welding torch 4 changes, the bead shape may become discontinuous or the penetration depth may change, resulting in poor welding even if the bevel is traced. There was a problem.

This invention was made to solve this problem, and provides a welding torch that can always maintain a welding torch fixed to a welding wheel at an appropriate torch angle for a bent welding line. The purpose of this paper is to propose a follow-up control method.

[Means for solving problems]

The welding line tracking control method of a welding torch according to the present invention is performed in fillet welding along a curved welding line while rotating the arc at high speed with a welding torch fixed on a trolley. (a) The arc of the rotating arc Detect the voltage waveform or welding current waveform, and (b) calculate the arc voltage waveform or welding current waveform ± around the forward point Cf in the welding direction and the backward point Cr in the welding direction.
Divide at a constant angle ±φ0 in the range of 2.5 degrees to ±90 degrees, and set a constant angle ±φ on the Cf side of the forward point of G-3. Calculate the area Scf of the arc voltage waveform or welding current waveform created by and the area scr of the arc voltage waveform or welding current waveform created at a fixed angle ±φ0 on the rear point Cr side, and
Calculate f - Scr, detect the amount by which the difference in area changes from a predetermined reference value, and (e) correct the traveling direction of the welding torch to the left or right according to the amount of change. do.

[Effect]

In this invention, since the voltage waveform of the rotating arc or the welding current waveform changes when the torch angle with respect to the welding line changes, the fluctuation of the arc voltage waveform or welding current waveform during welding is detected and based on this fluctuation. The direction of movement of the welding wheel, which has a welding torch fixed to it, is controlled.

〔Example〕

@Figure 1 is an explanatory diagram of fillet welding using a rotating arc according to an embodiment of the present invention. In the figure, 1 indicates the lower plate,
A standing plate 3 erected on the lower plate 1 is a welding line 2, and a welding torch 4 is fixed to a cart (not shown).

First, the present invention will be explained in detail based on the above embodiment. The welding torch 4 is rotated in the direction of the arrow 7 by a rotating motor (not shown) at a rotational speed adapted to the welding current and welding speed, and a wire 8 is passed through the eccentric hole of the current-carrying tip at the tip of the welding torch 4.
Welding is performed along the welding line 3 while rotating the arc 9 at high speed. In Fig. 1, the welding direction is perpendicular to the page and from the back side of the page to the front side, ta is the arc length, t is the wire protrusion length,
Ex is the distance between the welding torch 4 and the base metal.

Figure 2 shows the welding torch 4 shown in Figure W11 on the rotation axis 10.
This is an explanatory diagram seen from the direction, and in the diagram C1r Cr,
RL indicates the position of the wire 8 when the welding torch 4 is rotating, and Cf indicates the position of the wire 8 in the forward welding direction 5.
r1 row tatami - Rke Itsubo Bei Takuzaku surface Ef side I position of wire 8 on 90 degree right side, L is position of wire 8 on 90 degree left side, Cr
indicates the position of the wire 8 at the rear with respect to the welding direction, and φ indicates the rotation angle of the wire 80 with respect to the welding direction 5.

As shown in Figure 1 and Figure 2, when the welding torch 4 is rotated with the wire feeding speed constant, the distance Ex between the welding torch 4 and the base metal will vary depending on the position of the wire O at the time of rotation. 1h changes. When the arc length changes, the load characteristics change and the welding current I and arc voltage E change. Welding current due to this change in arc length ta! Alternatively, if the change in distance Ex is large, the change in arc voltage E will change in a linear relationship with the change in distance EX. As shown in FIG. 1, when the welding torch 4 rotates during fillet welding, the wire 8
Since the distance Ex changes according to the 0 position using a sine wave as a reference form, the welding current and arc voltage E also change corresponding to the position of the wire 8 using a sine wave as a reference form. Note that this relationship holds true not only for consumable electrodes but also for non-consumable electrodes.

1F, Figure 3 W, (b) shows the rotating wire 8 when the welding tote 4 is perpendicular to the welding line 3 as shown in Figure 4.
In other words, the arc voltage E changes depending on the position of the arc.
and waveforms of electric welding work. In Figure 3 (a)
is the waveform of the arc voltage E, and (b) is the waveform of the welding current I, and each waveform has an upside-down shape. In addition,
The waveform of electric welding can be obtained only with a welding power source with constant voltage characteristics, and the waveform of arc voltage E can be obtained with either a welding power source with constant voltage characteristics or constant current characteristics.

When the welding torch 4 is perpendicular to the welding line 3 as shown in FIG.
) and (b), the waveforms have almost the same shape.

However, as shown in FIG. 5, when the welding torch 4 is tilted backward with respect to the welding progress direction 5 and takes an advancing angle θ, the arc ta at the forward position Cf of the wire 8 is at the backward position @C
When the arc length at rVc is longer than m, the arc voltage waveform becomes such that the voltage level at the front position Cf is higher than the voltage level at the rear position Cr, as shown in FIG. Conversely, as shown in FIG. 7, when the welding torch 4 is tilted forward with respect to the welding direction 5 and takes a receding angle θ, the arc length M at the front position Cf is not shorter than the arc length M at the rear position Cr. The arc voltage waveform is also in the forward direction as shown in Figure 8.
The voltage level of Cf becomes a waveform lower than the voltage level of rear position Cr.

Therefore, by detecting the change in the arc voltage waveform, it is possible to detect the change in the torch angle caused by the bending of the welding line 6.

That is, the arc voltage waveform is divided into left and right angles at fixed angles with respect to the welding direction centering on the Cf point and the Cr point,
The areas Scf and Scr of the waveform created between these angles 40 are calculated, and the amount of change in the torch angle can be detected from the difference between the area Scf and the area Scr. You can control how you drive.

Here, the constant angle φG is from 2.5 degrees to 90 degrees.

The angle φ is set to be greater than t-2,s degrees. 2.
This is because if the value is less than 5, the waveform will be easily affected by noise.6 FIG. 9 is an explanatory diagram of the operation of the embodiment of the present invention.
Welding is carried out using a truck to which a welding torch 4 is fixed, following the welding line 3 bent by the traveling of the truck 110. The method for controlling the welding line follow-up of the truck 11 during this welding is described in the 10th section.
The explanation will be based on the block diagram of the control circuit shown in the figure.

First, a voltage detector 40 detects an arc voltage E, and a switch 41 divides the detected arc voltage E into a front point Cf side and a rear point Cr side in the welding direction. The timing of division of the arc voltage E by the switch 41 is determined by a command signal from the switching logic circuit 42. The switching logic circuit 42 detects the rotation angle φ of the wire 8 detected by the rotational position detector 43 and a predetermined constant angle φ in the range of 2.5 degrees to 90 degrees.
ot-The output φ of the set 4 setting device 44. For example, by comparing and calculating 45 degrees with
Output from the side. Similarly, the rotation angle of wire O outputs a waveform from the r side of the switch 41. The waveform output from fa of the switch 41 is integrated by an integrator 45, and the waveform output from the r side of the switch 41 is integrated by an integrator 46. n
The setting device 53 is set with the number n of times these integrals are processed, and the two integrators 45 and 46 perform waveform integration for n arc rotations outputted via the switching logic circuit 42. The outputs Scf and Scr are outputted to the memory devices 47 and 48, respectively. Memory device 47°48
The signals Scf and Scr are stored while repeating the storage of the signals Scf and Scr input from the integrators 45 and 46 every n times.
cr is output to the differential amplifier 49. The differential amplifier 49 calculates the difference Scf -Scr between these signals and outputs it to the differential amplifier 50 at the next stage. Between the differential amplifiers, the difference signal Scf
-Scr and the original reference value at the proper torch angle set in advance in the base single voltage setting device 51 Δ5=(S
cf -5cr) -86 and the bogie running control means 52
Output to. Note that the base value S0 becomes zero when the welding torch 4 is set perpendicular to the welding line 3 as the appropriate torch angle.

The bogie traveling control means 52 determines whether the input signal ΔS is positive or negative, and the bogie travel control means 52 determines whether the input signal ΔS is positive or negative.
control the direction of travel. That is, when the signal ΔS is negative, the traveling direction of the truck 11 is corrected to the left, and when the signal ΔS is positive, the traveling direction of the truck 11 is corrected to the right. For example, when the welding line 6 is an arc as shown in FIG. 9, the truck 11 travels along the arc in the direction of the arrow 12 before performing fillet welding. Therefore, the welding torch 4 can always be maintained at an appropriate torch angle.

In addition, in the above embodiment, the arc voltage waveform is detected and the bogie 1 is
Fig. 3 (b)
) Even if the welding current waveform shown in FIG.

〔Effect of the invention〕

As explained above, this invention allows the welding torch to follow a welding line that is bent based on fluctuations in the voltage waveform of the rotating arc or the welding current waveform, so welding can always be performed at an appropriate torch angle. It is possible to form a bead that is continuous over the entire length of the weld line and has a constant penetration depth.

Furthermore, since the welding cart to which the welding torch is fixed runs following the welding line, the welding cart has the effect of being able to run on its own.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of rotating arc fillet welding of the present invention, Fig. 2 is an explanatory diagram showing the wire position of the above embodiment, and Fig. 3 (
a') is an arc voltage waveform diagram, Figure 3(b) is a welding current waveform diagram, Figures 4, 5 and 7 are explanatory diagrams of the welding torch position relative to the welding line, Figures 6 and 8. 9 is an arc voltage waveform diagram, FIG. 9 is a detailed explanatory diagram of the present invention, FIG. 10 is a block diagram of the control circuit of the above embodiment, and FIG. 11 is an explanatory diagram showing a conventional method. 1... Lower plate, 2... Vertical plate, 3... Welding line, 4... -
・Welding torch, 8... wire, 11... trolley. Agent Patent Attorney Masatoshi Sato (b) Figure 6 Figure 8 @ Figure 9 @ 11 Figure 1-

Claims (1)

[Claims] In fillet welding performed along a curved welding line while rotating an arc at high speed, (a) detecting the arc voltage waveform or welding current waveform of the rotating arc; (b) detecting the arc voltage The waveform or welding current waveform is ± centered on the forward point Cf in the welding direction and the backward point Cr in the welding direction.
Divide by a constant angle ±φ_0 in the range of 2.5 degrees to ±90 degrees, (c) Area Scf of the arc voltage waveform or welding current waveform created at a constant angle ±φ_0 on the front point Cf side and the rear point Cr Calculate the area Scr of the arc voltage waveform or welding current waveform created with a constant angle ±φ_0 on the side, (d) Calculate the difference in the above areas Scf - Scr, and calculate the amount by which this area difference changes from a predetermined reference value. and (e) correcting the traveling direction of the welding torch left and right according to the amount of change, and controlling the welding speed to a constant value.