JPH0350632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a spot welding discharge nozzle used to surround a welded part with an antioxidant gas.

Conventional technology Previously, a capacitive DC power supply was used for spot welding with an electron gun, but due to the rapid rise of the welding current supplied to the welding electrode, part of the molten metal could form a burr around the welded part. In order to avoid this problem, a method using an AC power source (AC welding) has recently been adopted to avoid this problem. According to this AC welding, the welding current can be gradually increased to the current value required for spot welding, so the generation of splash burrs can be prevented to a certain extent, but the temperature of the welded part also gradually increases. Before the current reaches the value at which spot welding is actually performed, an oxide film forms on the part to be welded, making welding impossible. Therefore, it was necessary to further increase the welding current, which caused the problem that splash burrs were more likely to occur. In order to solve this problem, conventionally, as shown in Fig. 2, the spot welding electrode rod 1
A system in which a discharge nozzle 2 is provided for spraying an antioxidant gas toward a welded part is increasingly being adopted.

Problems to be Solved by the Invention With the conventional method of spraying antioxidant gas onto the welded part from the discharge nozzle 2, oxidation of the welding point and splash burrs may occur depending on the welding conditions and welding method. There was a problem with poor yield. For example, in the embodiment shown in FIG. 2, the inventors have discovered that when an antioxidant gas is sprayed under certain conditions, oxidation and splash burrs are likely to occur in the shaded portion of the spot welding electrode rod 1. This has been confirmed through experiments, and even when experiments were conducted using a nozzle in which an annular slit was formed surrounding the spot welding electrode rod 1, it was confirmed that the improvement effect was not as pronounced as on the left. The cause of this has not yet been clearly analyzed, but it is assumed that factors such as the width and diameter of the annular slit, the pressure and flow rate of the antioxidant gas, etc. are intricately and subtly intertwined. Depending on the conditions, it is possible to obtain a good product without oxidation or splash burrs, but the problem is that it is very difficult to adjust.

Means for Solving the Problems The present invention includes a cylindrical container having a gas inlet and an outlet, and a porous breathable material housed in the container that relaxes and equalizes the flow rate and pressure of the gas. A discharge nozzle for spot welding is used, which has a structure in which the inner circumferential surface on the outlet side of the container is the same as or expanded from the inner circumferential surface of the cylindrical container.

Effect: When the antioxidant gas is supplied to the container from its inlet, the antioxidant gas is diffused within the container by the porous breathable member, the flow rate and pressure are reduced, and the gas is distributed almost uniformly. Uniform flow velocity distribution and pressure distribution of antioxidant gas can be obtained from the outlet,
The part to be welded on the workpiece to be spot welded using a spot welding electrode is softly wrapped in antioxidant gas without disturbing the surrounding air layer.
Of course, the purpose is to protect the spot weld by not allowing air to be entrained or infiltrated, and to prevent the occurrence of oxidation and splash burrs. In addition, since there is no oxidation at the tip of the spot welding electrode, the tip needs to be corrected (polished) at a rate of 300 to 400 points/time, whereas conventionally it was done at 100 points/time. .

Embodiment FIG. 1 shows a preferred embodiment of the present invention, in which 10 is a spot welding electrode rod;
11 is a cylindrical container, 12 is an inlet thereof, 13 is an outlet thereof, and 14 is a breathable member.

In FIG. 1, the case where the container 11 is provided integrally with the spot welding electrode rod 10 is illustrated, and in particular, the case where the spot welding electrode rod 10 is provided by penetrating the center of the cylindrical container 11 via the rolling ring 18 is illustrated. Although illustrated, the container 11 is not limited to this, and the container 11 may be provided integrally along the side surface of the spot welding electrode rod 10, or may be provided separately.

The container 11 is not limited to a cylindrical shape, but may be a hollow cylinder. The inlet 12 is connected tangentially or appropriately to the end plate 15 or side plate at one end of the container 11, and the outlet 13 is connected to the other end of the container 11. Form using the entire end opening. The inner circumferential surface of the container 11 may be uniform or may have a tendency to expand toward the outlet 13, as long as there is no unevenness that prevents the flow of the antioxidant gas. It is preferable that the circumferential surface has no protrusion and is flush with or widened from the inner circumferential surface of the container 11.

The container 11 is filled with a breathable member 14, which can moderate the flow rate and pressure of the antioxidant gas within the container 11, make it uniform, and release it from the outlet 13. The material and properties of the material do not matter; in this example, glass fiber is used, but the material is not limited to this, and any porous, breathable material such as steel wool or sintered metal may be used. . In this case, in order to hold the breathable member 14 inside the container 11, at the outlet 13,
A mesh-shaped holding member 16 is attached to the end of the container 11 on the outlet 13 side via an annular lid 17, so that the inner peripheral edge of the flange of the annular lid 17 does not protrude.
The flange is made to be the same as the inner peripheral surface of the container 11, and the peripheral edge of the holding material 16 is held between this flange and the end surface of the container 11.

The antioxidant gas used in the present invention may be the same as that conventionally used, such as nitrogen gas, argon gas, or a mixed gas of nitrogen and hydrogen. The lower the gas pressure and flow rate, the better.

Usually, a spot welding electrode 10 of approximately 4φmm in diameter is used as the spot welding electrode 10 in the electron gun assembly, and when it is used by penetrating into the container 11 as shown in FIG. Inner diameter is approximately 10φ
mm, gas pressure at inlet 12 0.5-1.5Kg/cm ² , flow rate
It was 100% effective at 0.05/sec.

Effects of the Invention According to the present invention, by relaxing the outflow velocity of gas and making the pressure distribution uniform by the air-permeable member in the container, the sprayed area is isolated from the surrounding air layer, and oxidation is prevented uniformly with no difference in density. To improve the yield by being able to enclose the workpiece in a strong gas atmosphere, without disturbing the surrounding air layer, and by preventing air from being entrained or intruding, thereby reliably eliminating the occurrence of oxidation, splash burrs, etc. in the welded area. In addition, since the structure is simple, it can be implemented at low cost, and has the advantage of reducing the manufacturing cost of spot welding parts such as electron guns. In particular, it has practical effects such as greatly reducing the degree of correction and polishing of the welding tip and facilitating maintenance.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a spot welding discharge nozzle showing an example of the present invention, and FIG. 2 is an explanatory diagram of a conventional spot welding discharge nozzle and welding procedure. 10... Spot welding electrode rod, 11... Container,
12... Inlet, 14... Breathable member.

Claims (1)

[Claims] 1. A cylindrical container in which a spot welding electrode rod 10 has an inlet 12 and an outlet 13 for supplying antioxidant gas, and a gas permeable member 14 made of glass fiber or steel wool is housed therein to relax and equalize the flow rate and pressure of the gas. 11 and is provided through the outlet 1 of the container 11.
3 is on the welding side of the electrode rod 10, and is a mesh-shaped holding material 16 for holding the breathable member 14.
The annular lid 17 is opened flush with the inner circumferential surface of the container to which it is attached, and is expanded from the inlet 12, thereby enveloping the welded part in a uniform oxidation-preventing gas atmosphere and preventing the entrainment of ambient air. A gas discharge nozzle for spot welding, characterized by: