JPS5946712B2 - Welding torch for narrow gap welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a narrow gap welding device, and more particularly to a welding device that can easily weld not only a straight butt narrow gap but also a complicated curved narrow gap. .

The inventors have previously proposed a narrow gap welding method and apparatus that can facilitate narrow gap welding and provide very good welding conditions.

The present invention provides a welding torch structure that can more effectively carry out the welding methods and devices proposed above. FIG. 1 shows a narrow gap welding device previously proposed by the inventors.

In the figure, welding wire 2 fed out by push roller 3 passes through guide tube 4, is bent by weaving roller 5 that reciprocates in the direction of the arrow, passes through pull roller 6, and is bent at the tip of torch 1. The bead 11 is automatically swung to form a good bead 11. Welding is performed by moving this welding torch 1 along the groove. Note that the reference numeral 9 indicates the base material, and 10 indicates the groove. 2 and 3 show details of the welding torch 1. FIG.

In the figure, a contact tube 16a is located approximately in the center of the welding torch 1, and a welding wire 2 is inserted into the tube 16a.
moves and reaches the welding part via the contact tip 19a at the lower end. 14a is a cooling water sending pipe, 15a is a cooling water return pipe, and the entire torch 1 is cooled by flowing cooling water.

Reference numerals 12a' and 12y are gas passages, and inert gas is injected into the welded area from gas jet ports 17a' and 17y at the lower end to seal the welded area with the inert gas.

The torch 1 constructed as described above is formed as a thin plate as a whole as shown in FIG. 1, and is inserted into a narrow gap and moves through the narrow gap while performing welding. Here, the width W1 of the welding torch
The thickness W2 is determined by the cross-sectional shape and area of the contact tube 16a, the cooling water supply pipe 14a, the cooling water return pipe 15a, and the two gas passages 12a' and 12d. When the width W and the thickness WC of the welding torch 1 are large, a narrow groove with a complicated curved shape (in addition, it also includes cases in which there is a three-dimensional displacement in the vertical direction) and a small radius R, as shown in Fig. 4. In a narrow gap, the torch 1 cannot be moved. For this reason, the torch 1 should be small in both width and thickness, but the welding wire passes through the contact tube, and a certain amount of cooling water must pass through the cooling water pipe, so the cross-sectional area should be reduced. I can't. Therefore, in order to downsize the torch, it is necessary to reduce the cross-sectional area of the gas passage, but when the cross-sectional area of the gas passage is reduced, the cross-sectional area of the gas ejection port naturally also decreases in the conventional nozzle shape. For this reason, when a predetermined amount of gas is passed through, the gas injection speed increases, which adversely affects the molten pool. Furthermore, in the past, two cooling water pipes were arranged side by side on one side of the contact tube, so there was a problem that the cooling efficiency was not always good. An object of the present invention is to eliminate the above-mentioned problems and provide a welding torch that can be made compact, can inject a predetermined amount of inert gas without increasing the injection speed, and has good cooling efficiency. .

In short, this invention reduces the cross-sectional area of the gas passage through which the inert gas passes, thereby making the entire welding torch smaller, and also gradually increases the cross-sectional shape of the gas nozzle (widens toward the end) to increase the gas flow rate. The cooling water pipes are arranged on both sides of the contact tube,
In some cases, this cooling water pipe has a double structure. Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 5 to 7, cooling water pipes 15 are arranged on both sides of the contact tube 16, and inside the cooling water pipes 15, an inner pipe 14 sharing a central axis is arranged, for example. The inner pipe 14 is used as a cooling water sending pipe, and the annular space formed by the inner pipe 14 and the cooling water pipe 15 is used as a cooling water return pipe. Next, gas passages 12a and 12b are arranged on both sides of the cooling water pipe 15. The cross-sectional area of this gas passage is set to approximately -1 of that shown in FIGS. 2 and 3, thereby reducing the overall shape of the torch. Reference numeral 20 denotes a lower block of the torch 1, in which a contact tip 19 for sending out a welding wire is arranged in the center, and gas nozzles 17a and 17b, which are gas nozzle parts for injecting inert gas, are formed on both sides.

Figure 8 shows details of the gas nozzle. A bent part 18 having a larger cross-sectional area than the gas passage 12a is formed between the gas passage 12a and the gas nozzle 17a, and following this bent part 18, there is a so-called widening section in which the cross-sectional area further increases toward the opening end. A gas nozzle 17a is formed. The bent portion 18 is bent toward the contact tip 19 so as not to increase the width of the lower block 20.

Preferably, the gas nozzle axis 17c is inclined toward the contact tube 19 side.In addition to the above configuration, the inert gas G flowing at high speed in the gas passage 12a is arranged so that the axis of the gas nozzle portion is on the contact tube side. The gas flow direction changes abruptly due to the bent portion 18 as shown in the illustrated embodiment, resulting in turbulent flow and a sudden increase in the cross-sectional area. Therefore, the flow velocity decreases.

Since the cross-sectional area of the gas nozzle 17a further increases toward the end, the gas flow rate decreases further and the gas is injected into the welded portion. In this case, since the axis 17c of the gas nozzle 17a has a tapered surface inclined toward the contact tip 19, the inert gas is mainly injected toward the contact tip 19, thereby making it possible to better seal the welded portion. By carrying out the present invention, the welding torch can be made compact and welding can be performed even in narrow grooves with complicated shapes.

Further, since the inert gas can be injected in a predetermined amount at an appropriate flow rate, the welded part will not be adversely affected and the welded part can be well sealed with gas.

Furthermore, by forming the cooling water pipe into a double structure, various effects such as being able to cool the welding chips effectively are exhibited.

[Brief explanation of drawings]

Figure 1 is a perspective view of a narrow gap welding device, Figure 2 is a front view of a conventional welding torch, Figure 3 is a sectional view of Figure 2, and Figure 4 is a narrow gap showing the state of movement of the welding torch. FIG. 5 is a partially cutaway side view of the welding torch according to the present invention, FIG. 6 is a front view of FIG. 5, FIG. 7 is a cross-sectional view of the lower prong, and FIG. It is an enlarged partial view. 1...Welding torch, 12a, 12b...
・Gas passage, 14...Inner pipe, 15...
Cooling water pipe, 16...Contact tube, 17
a, 17b...Gas nozzle, 18...
Bend section.

Claims (1)

[Claims] 1. In a welding torch used in a welding method in which the wire tip is weaved in the width direction of a narrow gap, gas passages are arranged before and after the contact tube in the welding progress direction,
Gas nozzle portions are formed at the tips of both gas passages so that their axes are inclined toward the contact tube and do not widen toward the entrance end, and a contact tip provided at the tip of the contact tube is formed at the open end of the gas nozzle portion. A welding torch for narrow gap welding, characterized in that it is configured to protrude more. 2. The welding torch for narrow gap welding according to claim 1, wherein the gas nozzle whose axis is inclined toward the contact tube and the gas passage are connected by a bent portion. 3 A cooling water pipe is placed between each contact tube and the gas passage, and this cooling water pipe has a double pipe structure, and either the annular space between the inner pipe and the cooling water pipe or the inside of the inner pipe is used for feeding cooling water. A welding torch for narrow gap welding according to claim 1 or 2, wherein the other is used for returning cooling water.