JPS5949109B2 - Fixed pipe circumference welding equipment - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a fixed pipe circumference welding device for welding the circumference of a fixed pipe by TIG welding, which uses a non-consumable electrode and shields the welded part with an inert gas. be.

A conventional device of this type is shown in FIG.

In Figure 1, 1 is a welding power source that supplies power to the welding head, 2 is a control device that performs various controls for automatic welding, 3 is a hand control box for adjusting welding start conditions, etc., and 4 is a welding device that actually performs welding. 5 is the welding head to be welded, 56 is the guide rail on which the welding head 4 runs, and T is the control device 2, welding head 4, and operation box 3.
A control cable 8 is a power cable that connects the welding power source 1, welding torch 9, and pipe 5. FIG. 2 shows a detailed view of the welding head 4. 9 is a welding torch that generates 10 arcs between pipes 5, 10 is torch 9
11 is a wire feeding mechanism that feeds the filler wire 14 to the welding area, 12 is a wire reel around which the filler wire 14 is wound, and 1315 is a welding torch. 9. Wire feeding mechanism 1
This is a traveling device that carries the first class and rotates around the pipe 5.

In a fixed tube circumferential welding device with such a configuration,
First, the welding head 4 is set at the upper position of the guide rail 6, and a command to start welding 20 is issued by operating the operation box 3. Based on this command signal, the control device 1 drives the traveling device 13 clockwise, and also operates the welding torch 9 and the wire feeding mechanism 11 to perform one rotation of welding in all positions in the clockwise direction. When the welding torch 9 makes one revolution, welding is stopped, and the welding torch 259 is reversed and returned to the original starting position. From this starting position, the second bus welding is performed in the same manner as described above. This operation is repeated to perform circular welding as many times as necessary to perform circumferential joint welding of the fixed pipe 5. However, the groove shape of the weld joint is formed into a V-groove and a U-groove as shown in Figures 3a and 30b.
Although it is not necessary to oscillate (so-called oscillation), after welding the second layer, if the welding torch is not oscillated, it will be necessary to perform two-bus welding on each layer. Generally speaking, there are two methods for oscillating a welding torch: a mechanical oscillation method that mechanically moves the welding torch from side to side, and a magnetic oscillation method that uses electromagnetic force to sway only the arc generated by the welding torch from side to side. The former allows the bead width to be widened to some extent, but the oscillation mechanism itself is complicated;
The mechanism around the welding torch becomes large. The latter uses a magnetic head that utilizes electromagnetic force, and the area around the welding torch can be made smaller, but the weld bead width cannot be made very wide. This invention was made in consideration of these points, and it is possible to increase the width of the arc by adding a simple nozzle that sprays cooling gas onto the arc, and to oscillate it by inserting multiple filler wires at the same time. The purpose of the present invention is to provide a fixed tube circumferential welding device that can widen the bead width without any problems, and can further improve welding efficiency.

FIG. 4 showing an embodiment of the present invention will be described below.

In FIG. 4, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, 13 is a traveling device, 14 is a filler wire, and two wires are inserted in parallel to one welding torch 9. ing. Further, a detailed diagram of the 9 parts of the welding torch is explained with reference to FIG.
is a cooling nozzle for cooling the tip of the electrode 16 from the front and rear in the direction of movement of the electrode 16 and jetting cooling gas to change the shape of the arc. Reference numeral 18 indicates an arc generated between the electrode 16 and the base material (pipe) 5, and reference numeral 19 indicates a molten pool 620, which indicates a weld bead.

Reference numeral 14 denotes filler wires inserted into the arc portion, two of which are inserted in parallel.

When welding is performed using such a device, first the arc 1
8 changes from a circular cross section to a flat shape as shown in FIG. 6 by the cooling gas ejected from the cooling nozzles 17a and 17b. That is, as shown in FIG. 6a, the normal arc 18
The arc 18 has a conical shape with the electrode 16 at its apex, but in the present invention, as shown in FIG. 6b, cooling gas is blown from both sides of the arc 18 to change the shape of the bottom from a circle to an ellipse. That is, the arc 18 changes into a flat shape and spreads in a direction perpendicular to the weld line. In this case, the front view of arc 18 is
The high brightness portion of No. 8 occurs completely separated on both sides. Therefore, filler wire 1 of the same diameter and the same feeding speed is applied to this part.
When two molten metals 4 are fed in parallel, each forms a molten pool, and these molten pools are connected by the arc heat in the center. This situation is shown in FIGS. 7 and 8. arc 1
8 is controlled by changing the magnitude of the welding current and cooling gas flow rate, and by adjusting the distance between the two inserted filler wires 14a and 14b accordingly, weld beads with various widths can be obtained. . According to experiments, a weld bead with a bead width 1.5 to 2 times larger than a normal bead width was obtained with the same welding current. As described above, according to the present invention, the arc spreads by simply changing the magnitude of the welding current and cooling gas flow rate, without causing the arc to sway from side to side or the welding torch from side to side using electromagnetic force. The welding torch can be controlled and the area around the welding torch can be made smaller.

Furthermore, by adjusting the spacing between the plurality of filler wires according to the above-mentioned spread, weld beads with various widths can be obtained, and the use of a plurality of filler wires increases the welding speed. Furthermore, for devices such as circumferential welding equipment, where the welding torch is in an ascending or descending attitude, or even upside down, the area around the welding torch can be made smaller. This point is particularly effective because the load on the traveling device and guide rails is reduced.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing a conventional fixed tube circumferential welding device, Figure 2
The figure is a configuration diagram showing details of the welding head shown in Figure 1;
3 is a cross-sectional view showing the groove shape of a welded joint, FIG. 4 is a configuration diagram showing an embodiment of the present invention, FIG. 5 is a cross-sectional view showing the details of the welding torch portion in FIG. Figure 6a is a diagram showing the shape of a conventional arc, Figures 6b and 7 are diagrams showing the shape of an arc in the present invention, and Figure 8 is a diagram showing the formation phenomenon of a molten pool in the present invention. be.

Claims (1)

[Claims] 1 Welding is carried out by rotating a welding torch having a non-consumable electrode along the circumferential welding line of the pipe to be welded, shielding the circumferential welding area with inert gas, and supplying filler wire. A cooling gas nozzle that sprays cooling gas onto the non-consumable electrode from the front and back in the direction of movement of the consumable electrode, and a filler wire feeding mechanism that supplies the plurality of filler wires from the front in the direction of movement of the non-consumable electrode. Fixed tube circumferential welding equipment.