JPS6380971A - Detection method for root gap - Google Patents

Abstract

PURPOSE:To improve a welding quality by dividing the waveform of an arc voltage or that of a welding current at a fixed angle at the front and rear part points in the welding progressing direction and detecting the root gap based on the variation in the difference of the areas formed by each waveform. CONSTITUTION:The rotary welding of a wire 6 is performed by rotating an electrode nozzle 5 in a fillet welding of a lower plate 1 and vertical plate 2. In this case, the arc voltage waveform is divided in the right and left of the welding direction at the constant angle phi0<=+ or -90 deg. respectively with the front point Cf and rear point Cr as the center and the areas Scf, Scr of the waveform between the angle + or -phi0 are found. Since the variation from the reference value of the difference in these both areas has a close correlative relation with the root gap, the root gap and its variation can be detected with a non-contact and at real time by detecting the fluctuation value of the difference in both areas. Consequently the welding control is always optimized and welding quality can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting a root gap when performing, for example, fillet welding by high-speed rotating arc welding.

(Prior Art) Conventionally, for example, when performing fillet welding, the groove portion is required to have a metal touch in principle.

(Problems to be Solved by the Invention) It is not possible to expect that the grooves of fillet welding will adhere tightly at all locations, and root gaps of various sizes occur, which not only adversely affects the bead shape and leg length, but also In arc sensor tracing, there is a problem that groove tracing control is also disturbed.

Similarly, butt joints also have the problem that various defects occur in the weld when the root gap changes.

This invention has been made to solve such problems, and an object of the present invention is to propose a root gap detection method that can detect the root gap and its size in a groove in high-speed rotating arc welding without contact. The purpose is to

(Means for Solving the Problems) The root gap detection method according to the present invention is applicable to high-speed rotating arc welding in which the arc is rotated at high speed by rotating the electrode. ■ The arc voltage waveform of the rotating electrode or Detecting the welding current waveform, ■ Divide the arc voltage waveform or welding current waveform at a constant angle ±φ0 within a range of ±90 degrees or less centering on the rear point C in the welding direction and the rear point CR in the welding direction, respectively; ■ The area Scf created by the arc voltage waveform or welding current waveform divided by a constant angle ±φ on the front point C side, and the arc voltage waveform or welding current waveform divided at a constant angle ±φ on the rear point C1 side. Calculate the area S cr made by 7 times, calculate the difference in the above areas (S cf - S cr), and detect the change in this area difference (S et - S cr) to detect the root gap. It is characterized by

(Function) In the present invention, the presence and size of the root gap is detected based on fluctuations in the voltage waveform of the rotating arc or the welding current waveform, so the root gap can be detected non-contact and in real time.

[Embodiment] Fig. 1 shows a side view of a fillet weld joint to be welded according to an embodiment of the present invention. The root of the groove, 4, is the root gap created between the lower plate 1 and the vertical plate 2. 5 is an electrode nozzle, 6
is a wire that passes through the eccentric hole of the current-carrying tip at the tip of the electrode nozzle 5, and the electrode nozzle 5 is rotated in the direction of the arrow 7 by a rotating motor (not shown) at a rotation speed adapted to the welding current and welding speed, and the wire 6 is By rotating, the arc 8 is rotated at high speed and welding is performed along the groove route 3.

In addition, in Fig. 1, the welding direction is perpendicular to the page, from the back side of the page to the front side, λa is the arc length, and 1e
is the wire protrusion length, and Ex is the distance between the electrode nozzle 5 and the base material.

FIG. 2 is a view of the electrode nozzle 5 shown in FIG. 1 viewed from the rotation axis direction, and is Cf in the figure.

C, , R, and L indicate the position of the wire 6 when the electrode nozzle 5 is rotating, Cf indicates the position of the wire 6 in front of the welding direction 9, and R indicates the position of the wire 6 on the right side by 90 degrees toward the welding direction 9. , L indicates the position of the wire 6 on the left side by 90 degrees, and Cr indicates the position of the wire 6 at the rear with respect to the welding direction 9. Further, φ indicates the rotation angle of the wire 60 with respect to the welding direction 9.

As shown in Figs. 1 and 2, when the electrode nozzle 5 is rotated with the wire feeding speed constant, the arc length 2a varies depending on the position of the wire 6 during rotation, and the arc length 2a varies between the bipolar nozzle 5 and the base material. The distance Ex changes. When the distance IEX changes, the load characteristics change, and the welding current ■ and the voltage E between the electrode nozzle 5 and the base metal (hereinafter referred to as arc voltage) change.

Welding current I or arc voltage E due to change in distance Ex
The change in distance 11fE changes in a linear relationship with the distance Ex unless the change in x is large. As shown in FIG. 1, when the electrode nozzle 5 rotates during fillet welding, the distance E changes according to the position of the wire 6 using a sine wave as a reference form, so the welding current I and arc voltage E also change depending on the position of the wire 6. It changes according to the sine wave as a reference form. Note that this relationship holds true not only for the consumable electrode but also for the non-consumable two poles.

Figure 3 shows the waveform of the arc voltage E that changes depending on the position of the rotating wire 6, that is, the arc, when the lower plate 1 and the upright plate 2 are in close contact and there is no root gap 4 in the groove. Figure 4 shows the waveform of welding current I that changes depending on the position of the arc. The waveform of arc voltage E shown in FIG. 3 and the waveform of welding current I shown in FIG.
The welding current I waveform shown in the figure can be obtained only with a welding power source with constant voltage characteristics, but the arc/voltage waveform shown in Figure 3 can be obtained with either a welding power source with constant voltage characteristics or constant current characteristics. Obtainable.

If there is no root gap 4 in the groove, the waveform centered at the forward point Cf in the welding direction as shown in FIGS. 3 and 4,
The waveform is almost symmetrical to the waveform centered on the rear point Cr in the welding direction, and has a constant angle ±φ within a range of ±90 degrees around the Cf point and the C point. The area of the waveform created by Scf and S
The difference in cr, 5O=(Set-Sc-), is approximately constant.

However, when the root gap 4 exists in the groove and the rotating arc reaches the starting end of the root gap 4, the arc length j2a at the forward point Cf in the welding direction due to the existence of the root gap 4
becomes longer, and the arc voltage waveform shown in FIG. 3 becomes an arc voltage waveform in which the level locally increases around the forward point Cf, as shown in FIG. Therefore, the arc voltage waveform shown in Fig. 5 is the difference (S
ct S cr) is the area difference S when there is no root spacing 4. becomes larger.

Therefore, the root gap 4 can be detected by detecting the change in ΔS expressed by the following formula % (1).

Figure 6 shows the relationship between the above ΔS and the welding time T. In Figure 6, TI is when the front point CF reaches the start of the root gap 4, and T2 is when the front point Cr reaches the end of the root gap 4. Indicates the time. As shown in FIG. 6, when the root gap 4 does not exist, ΔS is zero, but when the arc reaches the root gap 4, the level of ΔS increases. The existence of the root gap 4 can be detected by detecting when the rise in the level of ΔS exceeds a certain level of the dead zone S. Further, since the area Scf centered on the front point Cf changes depending on the size of the root gap 4, there is a good correlation between the size of the root gap 4 and the changing level of ΔS. Therefore, by detecting the level of ΔS that changes due to the presence of the root gap 4, the size of the root gap 4 can also be detected.

When detecting the root gap mentioned above, the range of constant angle ±φ0 is upper 2
The range is from ゜5 degrees to ±90 degrees. The reason why the lower limit of the constant angle ±φ0 is set at 2°5 degrees is to prevent the influence of nozzle components riding on the waveform.

The route gap detection method described above will be explained based on the block diagram of the control circuit shown in FIG.

First, an arc 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 C 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. Switching logic circuit 4
2 is the rotation angle φ of the wire 6 detected by the rotation position detector 43
and a predetermined constant angle φ in the range of 2.5 degrees to 90 degrees. φ is set. Output φ of the setting device 44. For example 4
5 degrees and the rotation angle of the wire 6 is ±φ centered on the forward point Cf in the welding direction. A waveform in a certain section is output from the f side of the switch 41. Similarly, the rotation angle of the wire 6 is ±φ around the rear point Cr in the welding direction. A waveform in a certain section is output from the r side of the switch 41. The waveform output from the f side of the switch 41 is integrated by a forward integrator 45, and the waveform output from the r side of the switch 41 is integrated by a rear integrator 46. The n setting device 57 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. and its output S. , and S c
r is output to the front storage device 47 and the rear storage device 48, respectively. Each memory 47.48 is connected to each integrator 45.4 every n times.
The signals Scf and scr are outputted to the differential amplifier 49 while repeating the storage and holding of the signals Scf and scr manually inputted from 6. In the differential amplifier 49, this signal difference Scf S
cr is determined and output to the next stage differential amplifier 50. The differential amplifier 50 calculates the difference Δ5 between the difference signal 5cf-3cr and the base thread signal S0, which is preset in the reference voltage setter 51.
=(Scf 5cr) So is determined and output to the root gap determination circuit 52. The signal ΔS output from this differential amplifier 50 is τ when there is no root gap as shown in FIG.
becomes.

The route gap determination circuit 52 compares the signal ΔS with the dead zone level signal S1 set in the dead zone setting device 53, and determines when the signal ΔS exceeds the dead zone level signal Sl or becomes lower than the dead zone level signal S1. Detect the time and
Detecting the presence of root gaps.

Further, the root gap determination circuit 52 detects the size of the root gap by detecting the level of the manually input signal ΔS.

When the root gap is detected by the root gap discrimination circuit 52 as described above, welding is performed by changing the profile control method or by changing the welding conditions.

In the above embodiment, the root gap is detected by detecting the arc voltage waveform, but the root gap can also be detected by detecting the welding current waveform shown in FIG. 4 in the same manner as in the above embodiment.

Furthermore, although the above embodiments have been described with respect to fillet welding, changes in the root gap can also be detected in butt joints, and welding conditions can be adaptively controlled.

(Effects of the Invention) As explained above, the present invention can detect the existence and size of the root gap based on the fluctuations of the voltage waveform of the rotating arc or the welding current waveform, so it is possible to detect the presence and size of the root gap in real time without contact. This has the effect of being able to detect the root gap on the weld line or its change, allowing optimal control to be performed.

[Brief explanation of the drawing]

Fig. 1 is a side view of a fillet weld joint to be welded according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the wire position of the above embodiment, Fig. 3 is an arc voltage waveform diagram, and Fig. 4 is a welding joint. Figure 5 is a current waveform diagram, Figure 5 is an arc voltage waveform diagram when a root gap exists, Figure 6 is a waveform diagram for root gap determination in the above embodiment, and Figure 7 is a block diagram of the control circuit of the above embodiment. be. ! ...lower board, 2...vertical board, 3...bevel root,
4... Root gap, 5... Electrode nozzle, 6... Wire.

Claims (1)

[Claims] In high-speed rotating arc welding performed while rotating an electrode at high speed, [1] detecting the arc voltage waveform or welding current waveform of the rotating electrode; [2] detecting the arc voltage Divide the waveform or welding current waveform at a constant angle ±φ_0 within a range of ±90 degrees centering on the forward point C_f in the welding direction and the backward point C_r in the welding direction, [3] At a constant angle ±φ_0 on the forward point C_f side. Area S_c_ created by arc voltage waveform or welding current waveform divided by φ_0
f and the area S_c_ created by the arc voltage waveform or welding current waveform divided by a constant angle ±φ_0 on the rear point C_r side.
[4] Calculating the area difference (S_c_f - S_c_r), and detecting a change in this area difference (S_c_f - S_c_r) to detect the root gap. Detection method.