JPS5933067B2 - Fixed pipe circumferential welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic circumferential welding device for fixed pipes using the so-called TIG arc welding method, which welds a welded portion between a non-erasable electrode and a filler wire while shielding it with an inert gas.

Figures 1 and 2 show a conventional automatic circumferential welding device for fixed pipes of this kind. In Figure 1, 1 is a welding power source that supplies power to a welding head, which will be described later, and 2 is an automatic welding device. 3 is an operation box for starting welding or adjusting various welding conditions; 4 is a welding head; 5 is a fixed pipe to be welded; 6 is a welding head to which the welding head 4 is fixed. Guide rails □ and 8 for running around the pipe 5 are power cables and control cables that electrically connect the welding power source 1, welding head 4, operation box 3, etc. to each other.

Next, in FIG. 2 showing details of the welding head 4,
9 is a welding torch that generates an arc between it and the fixed tube 6;
10 is a position adjustment device that adjusts the position of the welding torch 9 vertically and horizontally with respect to the welding portion; 11 is a wire feeding device that feeds the filler agent, that is, the filler wire 14 to the welding portion; 1;
2 is a wire reel around which the filler wire 14 is wound;
Reference numeral 3 denotes a traveling device on which the welding torch 9, wire feeding device 11, etc. are mounted, and the traveling device runs around the fixed pipe 5 along the guide rail 6.

In the fixed pipe circumferential welding apparatus described above, the welding start position generally starts from the upper half of the fixed pipe 5 to be welded, and after welding is performed in one rotation in all positions in one direction, the welding torch is turned 9 is reversed and welding the second bus from the original starting position is performed in step 5, and this operation is repeated to perform circumferential welding of the fixed pipe 5 as many times as required, as is well known in the art. . According to the conventional device described above, it is necessary to reverse the welding head for each bath, and this reversing operation can be performed manually or automatically, but in any case, welding is stopped during the reversing operation. As a result, the arc time rate around the welding head 4 and welding power source 1 decreases, resulting in a significant decrease in welding efficiency.

In addition, if welding is carried out in the same direction, the amount of overlay tends to be unbalanced between the downward welding position and the upward welding position, so welding conditions must be adjusted each time, so welding capacity per unit time is reduced. There is also a disadvantage that it also decreases. Furthermore, in the conventional apparatus described above, only one welding direction (the direction in which the filler wire precedes) can be selected, and if welding is performed in the opposite direction, the filler wire 14 will plunge into the molten pool and solidify. This invention was made with attention to this point, and it is possible to weld the circumference of a fixed tube in both forward and reverse directions, whereas conventional methods could only be welded in the direction in which the filler wire precedes. The aim is to provide equipment. That is, FIG. 3 is an enlarged front view of the welding torch 9 of the welding head 4, and 15 is a filler wire 14.
16 is a cylindrical shielding gas nozzle that encloses the electrode 17 and flows the shielding gas around the electrode 17; 18 protrudes into the shielding gas nozzle 16, This is an electrode cooling gas nozzle disposed at a position opposite to the filler wire guide 15.

Since the device of the present invention is constructed as described above, the cooling gas is sprayed from the cooling gas nozzle 18 over the entire tip of the electrode 17, so that the arc 19 is caused by the wire insertion part as shown in FIG. Since the molten pool 20 extends backward even if the wire is deflected in the direction opposite to the wire insertion direction, the wire does not rush into the molten pool and become solidified as in the above-mentioned conventional method.

Therefore, according to the present invention, for the above-mentioned reason, welding can be performed in the direction opposite to the insertion direction of the filler wire 14, and a phenomenon such as welding and solidification of the wire does not occur (because the wire insertion direction is correct). This makes it possible to perform welding without any problem not only in the turning direction (wire leading direction) but also in the reverse direction.

Therefore, in the past, in order to weld one turn and unwind the cable, it was necessary to reverse the cable without producing an arc, but with this invention, it is possible to perform the reversal with an arc produced, and the cable can be unwound. This has the effect of omitting unwinding time and significantly improving welding efficiency. Also, as shown in Figure 5,
By making it possible to weld in the forward and reverse directions, it becomes possible to perform upward welding and downward welding, which not only naturally balances the amount of overlay on the left and right halves of the fixed pipe, but also improves the quality of the welded part. It also has the effect of further stabilizing it.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional circumferential welding device for fixed pipes, with Figure 1 being a front view showing the overall configuration of the device, and Figure 2
The figure is an enlarged front view showing the welding head. 3 to 5 each show an embodiment of the present invention, in which FIG. 3 is an enlarged front view of the welding torch, and FIGS. 4 and 5 are explanatory diagrams of the operation. In the drawing, 9 is a welding torch, 14 is a filler wire, 15 is a filler wire guide, 1
6 is a shielding gas nozzle, 17 is a non-erasable electrode, and 18 is an electrode cooling gas nozzle.

Claims (1)

[Claims] 1 In a device in which the circumference of a fixed tube is welded while shielding the welded part between a non-erasable electrode and a filler wire with an inert gas, a cylindrical shielding gas nozzle containing a non-erasable electrode, A circumferential welding device for fixed tubes, characterized in that an electrode cooling gas nozzle is disposed at a position opposite to the wire guide of the filler wire.