JPH0139874B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a rotating arc welding method in which arc welding is performed while rotating a consumable electrode at a constant radius and speed. The present invention relates to a tracing control technique in which, when applying rocking, the rocking center traces the center in the width direction of the groove every half cycle of rocking.

[Prior art]

The rotating arc welding method itself, in which arc welding is performed while rotating the consumable electrode at a constant radius and speed, is disclosed in, for example, Japanese Patent Laid-Open Nos. 55-133871 and 57.
It is publicly known from Publication No.-91877. However, in all of these prior art techniques, the electrode only rotates and does not oscillate.

This rotating arc welding method that does not involve rocking is effective when the groove width can be maintained within a predetermined range because the consumable electrode generally rotates at a constant radius. However, it is difficult in practice to maintain the groove within a predetermined range in various cases. In reality, the groove width often has to exceed a predetermined upper limit due to restrictions in groove processing, assembly, and the structure of the welded object.

In such a case, it is obvious that welding defects such as poor penetration will occur on the groove wall, so it is necessary to give the electrode not only rotation but also oscillation in the width direction of the groove. . However, even if the singing motion is given at a constant frequency and amplitude depending on the amount of groove width,
Good welding results cannot be obtained unless the singing center moves correctly over the center of the groove width.

[Summary of the invention]

It is an object of the present invention to apply vibration with a predetermined period and amplitude in the groove width direction at the same time as rotation in the above-mentioned rotary arc welding method, and to automatically move the singing center correctly over the center of the groove width. In order to For each half period of , integrate the area of the left division waveform of the rotation for the left oscillation half period and the area of the right division waveform of the rotation for the right oscillation half period, compare the integral values, and calculate the differential value. By automatically correcting the swing center position so that the swing center position is zero, even if the groove width becomes large and exceeds the predetermined range of the prior art, the swing amplitude and period can be changed to create any groove width. The purpose of the present invention is to provide a rotating arc welding method that can obtain good welding results by dealing with the above problems.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing the outline of the present invention together with the locus of movement of the electrode, and shows a state in which the center of oscillation is shifted from the center of the groove width. In the figure, 1 is a groove having a constant width, 2 is an electrode, and 3 is a rotation locus of the electrode 2. The electrode 2 is rotating around a rotation center a at a constant radius and speed in the direction of the arrow. 4 is the oscillation locus of this rotation center a, which sings in the direction of the arrow with a constant period and amplitude in the groove width direction, and shows a state in which movement in the welding progress direction (indicated by arrow A) is combined. There is. b is the center line of the groove width, and c is the center of swing. For convenience of explanation, FIG. 1 shows a state in which the center of swing is uniformly shifted from the center of the groove width as a whole. In addition, L is the left side wall of the groove,
R indicates the right side wall.

FIG. 2 is a conceptual diagram of an automatic welding apparatus used to carry out the method of the present invention, and FIG. 3 is a block diagram of the profile control of the main part of the present invention. In FIG. 2, a consumable electrode 2, shown as a wire electrode, is adapted to be automatically fed to an electrode nozzle 5 at a fixed radial position from its center of rotation, ie, the center line a of the electrode nozzle. Reference numeral 6 denotes a rotating device for this electrode nozzle 5, which is composed of an ordinary gear mechanism. 7 is a swinging device connected to the main body of the rotating device 6 via a swinging arm 8;
The main body of the groove 1 is swung in the width direction of the groove 1. Reference numeral 9 denotes an X-axis slider that moves the swing device 7 horizontally in the groove width direction (X-axis) in order to correct the position of the swing center (not shown). 10 is a drive motor for the X-axis slider 9, and 11 is a cart supporting the X-axis slider 9, which is movable in the welding direction. 1
Reference numeral 2 denotes a rotational position detector for the electrode 2, which is attached to the electrode nozzle 5. The rotational position detector 12 transmits information every half cycle as to whether the rotational position of the electrode 2 is on the left or right side with respect to the welding direction (broken line passing through point a in FIG. 1).

Next, in FIG. 3, 13 is a detector that detects the arc current or arc voltage waveform, 14 is a reference voltage generator, 15 is a differential amplifier for these detection signals and the reference signal, and 16 is a detected output. This is a changeover switch for dividing the waveform into a left half cycle and a right half cycle of the rotation of the electrode 2, and is operated by the rotational position signal detected by the rotational position detector 12.
Reference numeral 17 denotes a left integrator that integrates the area of the left divided waveform corresponding to the left half period of the rotation of the electrode 2 (the shaded area in FIG. This is a right integrator that integrates the area of the right divided waveform corresponding to the right half cycle (the shaded part in FIG. 4) every right swing half cycle T/2, and for these left or right integrators 17 and 18, A swing position signal 19 from the swing device 7 is given every half cycle of swing, and determines when the integrators 17 and 18 start and end integration. Reference numerals 20 and 21 denote a left side memory and a right side memory, respectively, which store and hold the final integral values of the integrators 17 and 18, respectively, reproduce and store the next final integral value, and repeat this process. 22 is a differential amplifier that compares the difference between the stored values in the left memory and the right memory, and its differential output is
This serves as an input signal to the axis driver 23 and drives the motor 10 of the X-axis slider.

In FIG. 4, 1 indicates the swing period (T), the left half period (L) T/2, and the right half period (R) T/2. 2 is an example of the output waveform of the differential amplifier 15 in FIG. It shows. 3 is a waveform of the left half period of rotation divided by the changeover switch 16, and 4 is a waveform of the right half period of rotation, and the waveforms in the shaded portions are integrated by integrators 17 and 18, respectively. 5 indicates the timing at which the left integrator 17 starts operating and the right integrator 18 ends _{, and t L indicates} the timing at which the left integrator 17 ends and the right integrator 18 ends. 18 shows the timing of the start of operation.

Next, the operation of the above embodiment will be explained.

The electrode 2 rotates around the center a of the electrode nozzle 5 while generating an arc, and at the same time moves in the welding progress direction while performing a swinging motion of a predetermined width in the groove width direction.

During this arc welding, in order to make the swing center c of the electrode 2 accurately follow the center b of the groove width,
First, the waveform of arc current or arc voltage is detected. This detected waveform is differentially amplified with the reference signal (2 in FIG. 4) and input to the changeover switch 16. This changeover switch 16 divides the continuous output waveform into a left half period and a right half period of the rotation of the electrode 2 as shown in FIG. 17, and the right divided waveform (FIG. 4) is input to the right integrator 18, respectively. Next, both integrators 17 and 18 integrate the area of the left divided waveform for the left half cycle of the electrode 2's oscillation, and the area of the right divided waveform for the right half cycle, and calculate the integral value of both. compare.

When there is a difference between the two integral values, it is because the swing center C of the electrode 2 is shifted from the groove width center b in either the left or right direction. For example, when the electrode 2 is shifted to the left side from the center b, the electrode 2 approaches the left side wall of the groove, so the left side split waveform in Fig. 42 becomes larger than the right side split waveform, so the above integral value A difference will arise. Conversely, when the swing center c is shifted to the right from the center b of the groove width, the right side divided waveform becomes larger than the left side divided waveform, and a difference also occurs in the above-mentioned integral values. Therefore, the drive motor 10 of the X-axis slider 9 is operated in the direction in which this differential value becomes zero.

In this way, the swing center C of the electrode 2 is made to trace the center b of the groove width while correcting its position every half cycle of swing.

〔Effect of the invention〕

According to the present invention, as described above, the electrode is caused to swing at the same time as it rotates, and the center of the swing is made to correctly trace the center of the groove width every half period of the swing, so that the groove Even if the width becomes large and exceeds the predetermined range of the prior art, it is possible to cope with any groove and obtain good welding results by simply changing the oscillation amplitude.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an outline of the present invention together with a movement locus of an electrode, and shows a state in which the center of swing is shifted from the center in the width direction of the groove. FIG. 2 is a conceptual diagram of an automatic welding apparatus used to carry out the method of the present invention, FIG. 3 is a block diagram of a copying control of the main part of the present invention, and FIG. 4 is a diagram showing the output division waveform of arc current. 1: Groove, 2: Electrode, 3: Rotation trajectory, 4: Oscillation trajectory, 13: Arc current or arc voltage waveform detector, 16: Selector switch, 17: Left side integrator, 1
8: Right integrator, 22: Differential amplifier, a: Center of rotation, b: Center line of groove width, c: Center of oscillation.

Claims (1)

[Claims] 1. A rotating arc welding method in which arc welding is performed while rotating an electrode at a constant radius and speed, wherein the electrode is oscillated at a constant frequency and amplitude in the groove width direction simultaneously with the rotation. At the same time, the waveform of the arc current or arc voltage is detected, and the waveform is divided into a left half period and a right half period of the above rotation with respect to the welding progress direction, and a left half period of the above oscillation with respect to the groove center. For the above rotation, integrate the area of the left side divided waveform of the above rotation, and for the right half period of the above oscillation, integrate the area of the right side divided waveform of the above rotation, and compare the integral values, so that the differential value becomes zero. A rotating arc welding method involving oscillation, characterized in that arc welding is performed while automatically correcting the center position of the oscillation.