JPS6029589B2 - 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 that welds by TIG arc welding using a non-consumable electrode and shielding the welded part with an inert gas.

An example of this type of device was the one shown in Figure 1.

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 5 is the pipe to be welded, that is, a fixed pipe; 6 is a guide rail on which the welding head runs; 7 is a control cable connecting the power source 1, head 4, and operation box 3; 8 is a power cable. . Figure 2 shows a detailed view of the welding head. 9 is a welding torch that generates an arc between the pipes 5; 1 is a fine adjustment mechanism that finely adjusts the torch 9 vertically and horizontally relative to the welding area; 11 is a welding torch that sends filler metal 14 to the welding area; 12 is a wire reel around which the filler wire 14 is wound; 13 is a traveling device that rotates around the pipe 5 and is equipped with a welding torch 9, a wire feeding mechanism 11, etc.;

Generally, welding of circumferential joints of fixed pipes involves all-position welding, and it is difficult to form a convex bead, especially when welding the first layer. The phenomenon of Uranami bead formation during first layer welding will be explained next.

FIG. 3 shows how force is applied when forming a weld bead in the first layer during circumferential welding of a fixed pipe. In Figure 3, 5
is a fixed tube, 15 is a molten metal, 16 is a hook, 17 is an electrode, Fg is the gravity of the molten metal, Fa is the arc force, and Fs is the surface tension of the molten metal. In order to prevent the Uranami beat 18 from being dented, it is necessary to set Fg<Fa10Fs,
Either reduce Fg (that is, reduce the volume of molten metal) or increase Fs by reducing the width of the front pea 19. To achieve this, it is necessary to reduce the arc length as much as possible, reduce the welding current, and at the same time, reduce the groove shape of the joint part of the fixed tube 5 and make the root part thin so that the back surface can be melted by heat input. As mentioned above, by reducing the thickness of the weld bead during initial layer welding,
A uranami bead is formed stably, but with conventional fixed pipe circumferential automatic welding equipment, the filler wire inserted into the welding part tends to meander due to bends in the wire, and the filler wire can be easily removed from the molten metal part during the first layer welding. In particular, as shown in Figure 4, the misalignment often penetrated the back side of the fixed tube, making stable welding impossible. In order to stably feed filament to the molten metal part during layer welding, the purpose is to provide a bag layer that can feed a curved wire to the welding part. The wire is curved so that it bends toward the electrode.

An embodiment of the apparatus of the present invention will be described based on FIG. In FIG. 5, 11 is a wire feeding mechanism, 12 is a wire reel, 20 is a wire strainer for straightening the bent wire, 21 is a wire guide, and 22 is a conduit tube.

FIG. 6 shows a wire feeding unit u which serves as a wire feeding path among the above-mentioned parts, and these parts are arranged so as to be substantially on the same plane. Now, assume that filler wires with three types of curvature are fed to a molten metal portion of a constant size.

This diagram is shown in FIGS. 7a, b, and c. Fig. 3a shows a filler wire bent toward the bead side, b shows a filler wire straight or bent in a direction perpendicular to the plane of the paper, and c shows a filler wire bent toward the electrode side of the present invention. In this figure, 5 is a fixed pipe, 23 is a weld bead, 24 is a molten pool, 1
7 is an electrode, 14 is a filler wire, and 21 is a wire guide. In particular, in order to form the Uranami bead in a convex shape, it is preferable to insert a wire into the back half (area A) of the molten pool. In the case of the front half, the molten metal rises to the top of the groove and tends to cause problems such as shorting with the electrode.Therefore, if the electrode is raised upwards, problems such as not melting to the back side occur. . In these three cases a, b, and c, assuming that the wire is inserted in area A,
When the insertion position of the wire is shifted vertically, the permissible value of the vertical fluctuation of the wire inserted into the A region is the largest c.
FIGS. 5 and 6 show an embodiment of a device in which the wire is curved in this manner so that the wire is bent toward the electrode after exiting the wire guide 21.

The wire wound around the wire reel 12 has a curvature close to at least the diameter of the wire reel 12, and to avoid changing this, the wire is guided through the conduit tube 22 and the wire feeding mechanism 11 to the wire strainer 20, where it is properly strained. curvature and feed it through the wire guide 21 to the welding part.
By arranging the wire reel 12, wire strainer 2Q, wire guide 21, and wire feeding unit 11 including the electrode 17 on substantially the same plane as in this embodiment, it is possible to prevent the filler wire 14 from shifting in the left-right direction of the electrode 17. In addition, it is possible to easily feed a wire with a predetermined curvature to the welding part by using the winding curl wound around the wire reel 12 and slightly softening the winding curl with the wire strainer 20. It is. As described above, in the present invention, when the curved filler wire comes out from the wire guide outlet at the tip of the feeding section, the wire comes out bent toward the electrode side. This allows stable welding without the wire penetrating into the back surface during initial welding, and even if the wire insertion position is slightly deviated due to variations in joint accuracy, arc length variations, etc., a good Uranami bead can be obtained. This is because it becomes.

Brief explanation of the drawings Fig. 1 is a system diagram showing a conventional circumferential welding device for fixed pipes, Fig. 2 is an enlarged schematic diagram of its welding head, and Fig. 3 shows the flow of molten metal during the formation of the first layer weld bead. FIG. 4 is an explanatory diagram of the relationship between such forces. FIG. 4 is an explanatory diagram of the problems encountered when using a conventional device. FIG. 5 is an explanatory diagram of the welding head of an embodiment of the present invention. FIG. FIG. 7 is a perspective view showing the wire feeding unit section including only the wire feeding path, and FIG. 7 is an explanatory view showing the effects of the present invention.

1 is a welding power source, 2 is a control device, 3 is a hand control box, 4 is a welding head, 5 is a fixed tube, 6 is a guide rail, 7 is a control cable, 8 is a power cable, 9 is a welding torch, 10 is fine adjustment mechanism, 11 is a wire feeding mechanism, 12 is a wire reel, 13 is a running device, 14 is a filler wire, 17 is an electrode, 20 is a wire strainer, 21 is a wire guide, 22
15 is a conduit tube, 15 is a molten metal, 16 is an arc, 18 is an underwave bead, 19 is a front bead, 23 is a welding bead, and 24 is a molten pool.

Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. In an apparatus that performs circumferential welding of fixed pipes using the TIG arc welding method, in which a non-consumable electrode is used and the welded part is shielded with an inert gas, the filler metal fed to the welded part is A circumferential welding device for a fixed tube, characterized in that it is equipped with a device that creates a curvature toward the non-consumable electrode at the welding part.