JPH0694068B2 - Flat plate one-sided welding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a single-sided welding method for flat plates.

[Prior Art] The conventional single-sided welding method for flat plates is to form a narrow groove with a V-shaped or U-shaped bottom at the butt end surface of the flat plate, and place a copper backing material on the inner surface of the flat plate groove. Then, while running the automatic welding machine on the guide rail mounted on the flat plate, the welding current of 250 ~ by the MAG welding method by the oscillating arc with the arc swing speed of 5 Hz or less and the arc swing width of 1.0 to 2.0 mm. A method is known in which the first layer is welded on one side from the outer surface of a flat plate under the conditions of 300 A and a welding speed of 75 to 110 cm / min.

[Problems to be Solved by the Invention] In the conventional one-sided flat plate welding method, when high-speed welding is performed by increasing the welding current to increase the welding speed, the welding bead becomes discontinuous and welding such as insufficient penetration or cracking in the welded portion occurs. There is a problem that defects occur. In addition, there is a method of profiling the groove width by a contact type sensor that causes the guide roller inside the groove to travel in contact, but there is a problem in accuracy, and it is practically used for high-speed welding. The current situation is not.

The present invention has been made in order to solve the above problems, and is a flat plate welding method capable of speeding up initial layer welding in butt welding of flat plates with stable quality and applying high-precision groove automatic profile by an arc sensor. The purpose is to obtain.

[Means for Solving the Problems] A method for single-sided welding of a flat plate according to the present invention is to form a narrow groove or V groove having a V-shaped bottom on a butt end surface of the flat plate,
A ceramic backing material is placed on the inner surface of the flat plate, and while the automatic welding machine is running on the guide rail attached to the outer surface of the flat plate, the arc rotation speed is 10 Hz or more, and the arc rotation diameter is 1.0 to 4.0 mm. The feature is that the first layer from the outer surface of the flat plate is welded on all sides with a wire diameter of 0.8 to 1.6 mm while automatically controlling the groove by the arc sensor by the gas shielded arc welding method using a high-speed rotating arc. .

The reason for using the high-speed rotating arc welding method in which the arc is rotated at a high speed in this invention is that a high-speed (rotation) oscillation of 10 Hz or more (experimentally MAX250 Hz) can be obtained as compared with the oscillation frequency of 5 Hz or less in the conventional method. Even if high-speed welding is performed, uneven penetration and defective bead shape caused by a coarse swing pitch do not occur. In other words, the high speed limit of bead discontinuity in high speed welding is 1.4 to 2.0 times faster than the conventional welding method. Also, in the case of high speed welding of the first layer single sided welding, the welding torch, that is, the accuracy of the groove groove and the response speed greatly affect the welding quality.However, in this method, the circularly moving arc itself is used as a sensor to achieve high accuracy in real time. You can control the groove.

On the other hand, the reason why ceramic backing material is used is that with the conventional copper backing metal, the weld pool immediately after welding is rapidly cooled and cracks easily occur in the welded part. This is because it has been found that there is a limit, and the use of a ceramic backing material can result in much higher speed than a copper backing material.

[Operation] According to the present invention, since the high-speed rotating arc welding method and the backing material made of ceramics are used on the inner surface of the flat plate, the wire diameter can be 1.4 to 2.0 times faster than that of the conventional swing arc method. 0.
A stable penetration and a good weld bead can be obtained at 8 to 1.6 mm.

In addition, since the groove profile control by the arc sensor enables highly accurate profile in real time, the welding operation is automated and a stable back bead shape and a good front bead shape are realized.

[Example] The welding method of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an automatic welding machine.
Is installed so as to be self-propelled along a guide rail 12 temporarily attached to the outer surface of the flat plate 10. The welding torch 2 provided in the main body 1 of the welding machine is rotated by the motor 3 via the gear mechanism 4, and the width direction of the groove 14 (x
It is supported via an x-axis slide block 5 that is movable in the axis) and a y-axis slide block 6 that is movable in the torch axis direction (y-axis). The rotation speed N of the torch 2 is the rotation speed of the arc, and the rotation speed and rotation position are detected by a rotation detector (not shown). The welding wire 7 is automatically fed to the current-carrying tip having the eccentric hole of the torch 2,
The eccentric distance determines the rotating diameter D of the arc. This allows the rotating arc method to be implemented.

Reference numeral 16 is a ceramic backing material that is arranged so as to face the groove 14.

Fig. 2 shows the principle of the high-speed rotating arc.
Is rotatably supported by a bearing portion 20, 22 is a current-carrying tip having an eccentric wire passage hole, which is screwed to the lower portion of the electrode nozzle 21, and 7 is a welding wire, which passes through the center hole of the electrode nozzle and is It is continuously fed from the eccentric hole. 3 is a motor for continuously rotating the electrode nozzle 21 in one direction via the gear mechanism, that is, the current-carrying tip 22 having an eccentric hole joined to the tip of the electrode nozzle 21 is also rotated, so that the current-carrying tip 22
The welding wire 7 fed from the tip of the arc also makes a circular motion and the arc can be easily rotated at high speed.

FIG. 3 is a principle diagram of the groove profile control by the arc sensor, and shows the waveform of the arc voltage E which changes corresponding to the position of the rotating welding wire 7, that is, the arc. In the figure, (a)
Defines the position of the arc, where the front center of the arc that continuously rotates to the right is C _f , the rear center is C _r , and the left and right are L and R. In the figure, the waveform shown by the solid line shows the case where the center of the rotating arc deviates from the groove center to the R side by ΔX as shown in (b) in the figure, and the waveform shown by the broken line does not deviate. The waveform is asymmetric with respect to the position C _f when it is not displaced as shown by the broken line, but the waveform is asymmetric when it is displaced by ΔX as shown by the solid line. By detecting and correcting the asymmetry of this waveform, the deviation amount ΔX in the X-axis direction
Can be modified. That is, the waveform is taken out from the left and right at a predetermined angle centering on the position C _f, and the waveform areas S _L and S _R created between the predetermined angles are obtained, and the welding torch is moved to X so that the areas S _L and S _R become equal. The axial center of the arc and the groove center can be made to coincide by making correction in the axial direction.

Further, in the height direction of the torch, that is, the distance control in the y-axis direction, the average value for one rotation of the welding current waveform is compared with the reference value,
In this method, the y-axis is moved and controlled so that the difference becomes zero.

4 (a), (b), and (c) are enlarged cross-sectional views of the groove shape and the backing material, and the groove 14 of the flat plates 10 abutted to each other in the drawing has an annular shape in which the bottom 14a has a V shape. In the groove 14b, the vertical wall has an inclination angle θ of 0 ° to 3 °. Also the bottom 14
The inclination angle α of a is 70 ° to 110 °. Furthermore, the RF dimension is 0.
In the case of 5 to 1.5 mm and the plate thickness T of 8 to 16.7 mm,
The groove width G of the groove 14b is formed to be 5 to 10 mm. A small inner surface groove 14c may be provided on the inner surface side of the flat plate of the groove 14 as shown in FIG. 4 (b), and the inclination angle β of the inner surface groove 14c is 70 to 110 °. The height of the tip 14c is 0.5 ~
It is 1.5 mm. In FIG. 4 (c), the shape of the groove 14 of the flat plates 10 joined together is V-shaped, and the groove angle γ of the groove 14 is 30 ° to 110 °. Reference numeral 16 is a ceramic backing material arranged on the backing side of the groove 14 of the flat plate 10. In addition,
The ceramic backing material 16a or 16b with grooves shown in FIGS. 6 (a) and 6 (b) is also used.

FIG. 5 shows the laminated state of the cross section of the welded beads. In the figure, the first layer R had good back bead formation and did not cause welding defects such as insufficient penetration and cracking. The welding of the laminated layer F and the finishing layer C can be performed with a large current and a high speed by the welding method of the present invention.

Although welding is performed in the atmosphere of 100% CO ₂ gas in the above-described specific example, it goes without saying that welding can be performed in the same manner even in a mixed gas atmosphere of 80% inert gas.

[Effects of the Invention] As described above, the present invention is the first in high current and high speed welding by using the high speed rotating arc welding method, the arc sensor automatic groove profile control and the ceramic backing material on the groove back surface. High-quality and good back bead shape can be obtained by performing single-sided layer welding in all positions. Also for all-layer welding, there is an effect that the welding of flat plates can be performed with high quality and high efficiency, such as continuous welding by the welding method of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an automatic welding machine used in the welding method of the present invention, FIG. 2 is a principle diagram of a high-speed rotating arc, FIG. 3 is a principle diagram of an arc sensor groove profile, and FIG. 4 (a). ，
(B) and (c) are groove shapes and enlarged sectional views of the backing material,
The figure is an explanatory view showing the laminated state of the cross section of the welded bead, and FIGS. 6 (a) and 6 (b) are cross sectional views showing the grooved backing material. 1 ... Welder body, 2 ... Welding torch, 3 ... Motor,
4 ... Gear mechanism, 5 ... x-axis slide block, 6 ...
y-axis slide block, 7 ... welding wire, 10 ... flat plate, 12 ... guide rail, 14 ... groove, 16 ... backing material,
20 …… Bearing part, 21 …… Electrode nozzle, 22 …… Energizing tip.

Claims (1)

[Claims] 1. In butt welding of flat plates, a narrow groove or V groove having a V-shaped bottom is formed on the butt end surface of the flat plate, and a ceramic backing material is arranged on the inner surface of the flat plate. While the welding machine is running on the guide rail attached to the outer surface of the flat plate, the arc rotation speed is 10 Hz or more and the arc diameter is 1.0 to 4.0 mm. A single-sided welding method for flat plates, characterized by performing first-layer welding from the outer surface of the flat plate in all positions with a wire diameter of 0.8 to 1.6 mm while controlling profile.