JPS5997777A - Continuous multi-turn TIG welding method for pipes - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a full-circumference TIG welding method for pipes, particularly a continuous multi-circumference TIG welding method.

Conventional TIG welding of pipes all around the circumference involves welding the entire circumference in one direction, and the power cable and cooling hose become entangled with the pipe, resulting in -
The procedure was repeated by stopping welding every lap, returning the welding cart to the starting point, and starting welding again.

1 and 2, conventional full-circumference TIG welding will be briefly described.

In FIG. 1, (1) shows a pipe, (2) a welding cart, and (3) a fin wire supply device.

The welding cart (2) which started welding from the foot point S rotates clockwise to reach the starting point, slightly overruns and stops, interrupts the welding work, and retreats to the starting point S.

The timing chart of welding current, welding voltage, wire feeding, and carriage running at this time is as shown in FIG.

In such a conventional TIG welding method, - for each lap (for each layer)
In order to extinguish the arc, high frequency waves are generated every time the next welding starts, and the high frequency noise frequently affects peripheral equipment.Furthermore, the following setup is required. That is,
It is necessary to polish the electrode each time for re-ignition. Welding defects such as poor fusion are likely to occur at the overlapped part of the start and end of full-circumference welding.If a welding defect occurs, in order to eliminate the welding defect, we will remove the welding defect and re-weld it. etc. Therefore, welding efficiency is extremely poor and welding reliability is also low.

The present invention has been made to correct this problem by reversing the welding direction every round so that continuous welding can be performed for multiple rounds without extinguishing the arc.

The present invention will be described in detail below with reference to the drawings.

FIG. 3 shows a welding machine for carrying out the present invention, an outline of the welding machine, and a running locus of a welding wheel of the welding machine, and FIG. 4 is a timing chart for carrying out the present invention.

In Figure 3, (1) is the pipe, (2) is the welding wheel, (3) is the first wire supply device installed in the direction of the welding line, and (3) is the device installed on the opposite side of the first wire supply device. The second wire feeding device shown in FIG.

The electrode (4) of the welding wheel (2) is positioned at the starting point S, and an initial current (■) is applied to the electrode (4). Initial current I
0 is for stabilizing the aqueduct and stabilizing the melt penetration before starting welding, and wire feeding, truck running, etc. have not yet started at this time.

After stabilizing the arc at the initial current I0, the welding current is gradually increased (I2). In synchronization with the start of increase in welding current, the feeding of the first feeding device (3), shear wire (5) is started and the speed (Wl) is increased, and the welding wheel (
2) Start running. The increasing control of the welding current (mm) and wire feed speed is to gradually grow the molten metal pool to the state of actual welding, and to prevent poor fusion at the start of welding. Further, arc voltage control (arc length automatic control) is started at the same time as the welding current (I2) starts increasing.

Adjustment of the vertical position of the wire (5) is started during the transition period up to this main welding.

When the welding current reaches the main current value (I3), the wire (5)
The main welding is started so that the feeding speed becomes (W2).

While performing the main welding, the welding wheel (2) is run and rotated in the clockwise direction. This state continues until the electrodes (4) reach eight points.

Even after reaching the 8th point, the current (I3), arc voltage control, wire vertical position adjustment, and trolley running are maintained, and only the wire feeding speed is gradually decreased (W3). The current is reduced (I4) with a slight delay in the reduction of the wire feeding speed, and the reduced state continues even after the feeding of the wire (5) is stopped. This current (
The delayed operation of I4) improves the penetration of the lap portion and eliminates fusion defects.

In synchronization with the current (I4) decreasing to the arc holding current (1,,), the wire (5) is retreated by a predetermined distance (
W4). This is 1 when the welding wheel (2) is moved in reverse.
The bead (6) where the wire (5) that had been fed until now was formed
) (see Figure 5).

In addition, the wire vertical position adjustment and arc voltage control are performed when the current is I4.
When the state is reached, it stops in the middle of the I4 state.

The purpose of applying current (I5) to the electrode (4) is to maintain the arc without extinguishing it, and the value must be such that the bead is not remelted and the arc can be maintained stably. be.

When the welding wheel (2) has overrun the required distance, it is stopped and then moved in the reverse direction. When the electrode (4) matches the starting point ゛S゛, stop the welding wheel (2) again,
Increase the electrode current to the initial current (Eng).

In the reverse rotation movement, the wire (5) is fed from the second supply device (3), and the current, voltage, wire feeding, etc. may be controlled in the same manner as in the above-described normal rotation movement.

Here, in the process of moving from normal rotation to reverse rotation, the welding wheel (2) is run while the electrode current is maintained at I5 and an arc is generated, but as a result, the overlap portion is tanned. Improves the adhesion of beads to the base material. .

To finish welding after repeating the above full circumference welding in forward and reverse directions a required number of times, the current (I4) should be reduced to 0, and the current (I4) in the welding wheel (2) should be O. Stop at that point.

In the above example, the wire was fed from the front in the direction of travel in all postures, but it may be possible to feed it from the rear, from the front and back at the same time, or from the front in the direction of travel when moving upright. It goes without saying that various combinations of wire feeding are possible, such as feeding the shear wire and feeding it backwards during vertical movement, or feeding it from the opposite direction.

In addition, although the above embodiment describes the case where there is only one welding wheel, multiple welding wheels can be arranged on the same welding line and rotated forward and backward at any rotation angle to perform continuous multi-turn welding. Of course it is possible.

As described above, according to the present invention, there is no need to interrupt the welding work by extinguishing the arc until the welding is completed after the arc is ignited.
It is very efficient as it does not require the various setup operations required when restarting welding, and since the arc is ignited only once, there is very little effect on peripheral equipment due to high frequencies, and the quality of the overlapped part is very low. Good results can also be obtained with regard to bead shape. Furthermore, since setup work by the operator is not required, automation is possible. By programming welding conditions for each layer, welding conditions for welding positions, etc. and inputting them into the control device, all positions are always maintained in the optimal condition. Welding is possible.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing conventional full circumference welding of pipes, Figure 3 is a schematic diagram of a welding machine for implementing the present invention, and Figure 4 is a timing chart for implementing the present invention. , FIG. 5 is an explanatory diagram showing the state of the bead and wire. (1) is a pipe, (2) is a welding wheel, (3) (35 is a supply device, (4) is an electrode, (5) is a filler wire, (6)
indicates a bead. Patent applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Continued from page 1 0 Author: Ikuo Shiina 1 Shin-Nakahara-cho, Isogo-ku, Yokohama City Ishikawajima-Harima Heavy Industries Co., Ltd. Technical Research Center 0 Author: Rikio Abe Shin-Nakahara-cho, Isogo-ku, Yokohama City No. 1 Ishikawajima Harima Heavy Industries Co., Ltd. Technical Research Center

Claims (1)

[Claims] 1) Reverse the moving direction of the welding cart, which can feed filler wire from two directions, front and back in the welding line direction, so that it overruns every full circumference welding, and move back the filler wire that was being fed before reversal, and also during the transition period of reversal. A continuous multi-turn TIG welding method for pipes, characterized in that an arc holding current is applied to an electrode and a filler wire is fed from a predetermined direction at the start of reverse welding.