JPH0321823Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a welding torch used for welding, particularly for MIG and MAG welding equipment.

For example, the MIG welding method, which has been widely used in the past, generates an arc between a metal wire forming a consumable electrode and the object to be welded while surrounded by an inert gas such as carbon dioxide or argon. This type of welding device uses heat to melt both the wire and the object to be welded to form a welded joint, and this type of welding device uses a wire W wound around a wire reel R as illustrated in FIG. feed roll L that feeds the welding object Y, welding torch and gas regulator G that performs welding operations on the object to be welded Y, wire and gas controller C, power source B
It is composed of etc.

Of these, welding torch T (also called welding gun)
constitutes a cylindrical body from which an inert gas is led out, and is equipped with a copper tip S inside to supply electricity to the wire W, which is one electrode, and the inert gas and the wire W are protruded from the tip. In order to do this, a nozzle N is provided which is made of copper or copper alloy and has a pipe shape with an outer diameter of about 15 to 50 mm. Such a nozzle N is exposed to high temperatures associated with an arc during welding, and a portion of the molten object Y and wire W is blown away. If some of these blown particles adhere to the nozzle N, not only will it cause problems such as blocking the holes H from which inert gas comes out, but the blown particles that have gradually accumulated on the inner wall of the hole H in the nozzle N will cause the wire to Comes into contact with W. Therefore, an electric path is formed from the wire W forming one electrode to the nozzle N, and when welding, an electric path is formed not only from the wire W protruding from the nozzle N but also between the nozzle N and the object Y to be welded. There were many situations in which arcs were generated in the welding process, making it impossible to perform good welding work, and there was a risk of insulation failure. In addition, since the nozzle N itself is made of low melting point and soft copper or copper alloy,
The high heat associated with welding work can cause the nozzle to become distorted, or the nozzles can become completely welded to the nozzle, making it impossible to clean and remove them, making it impossible to perform good welding. The reality is that this is hindering this.

This proposal was devised in view of the drawbacks of the welding torches used in conventional MIG welding and MAG welding as described above.

Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. Fig. 2 is an enlarged cutaway view of the nozzle n constituting the torch t according to the present invention. The wire W, which is made of silicon (Si ₃ N ₄ ) ceramic and has a tip s inside that guides the wire W and conducts electricity, protrudes from the tip of the nozzle n, and during welding operation, the nozzle The wire W protrudes from the hole h at the tip of the wire W, and emits an inert gas such as carbon dioxide gas, which acts to surround and protect the part to be welded. Further, although not shown, a female thread is formed inside the rear end of the nozzle n, and is connected to the male thread formed on the torch t by screwing. Therefore, the nozzle n is removable and can be easily replaced.

By the way, as mentioned above, the nozzle n according to the present invention is made of a cylindrical body made of silicon nitride ceramic, but a method for manufacturing a cylindrical body having such a shape is to use a tapered and threaded inner metal. After filling the mold with silicon nitride raw material powder mixed with a binder so as to enclose the mold, and performing isostatic press molding,
The above-mentioned middle mold was pulled out, and the obtained molded body was
It may be fired at 1900°C to form a dense sintered body.
In this way, a nozzle n made of silicon nitride ceramic
has high hardness (HRA85~95) and bending strength of 3000~
It has excellent insulation properties with a resistance of 8000Kg/cm ² and an electrical volume resistivity of 10 ⁹ to 10 ¹⁴ , and has great heat resistance and mechanical strength, with a maximum usable temperature of 1200°C.

Furthermore, since it has high heat resistance and no affinity with metals, it does not react with molten iron that blows away during welding, and there is very little metal adhesion to the nozzle n. If the surface of the silicon nitride ceramic material is rough, the blown metal (iron) will be caught and adhered by the minute protrusions on the surface. As a result of various experiments regarding the surface roughness, it was found that if the surface roughness was polished to Rmax3S or less, there would be less adhesion of blown metal.

As mentioned above, the nozzle constituting the welding torch used in the MIG (or MAG) welding equipment related to this project is dense, has no affinity with molten metal, has high heat resistance and heat resistance strength, and has electrical insulation properties. Because the nozzle is made of silicon nitride ceramic material, there is no adhesion of blown metal during welding, and the nozzle hole does not become thermally deformed even at high temperatures, compared to conventional nozzles made of metal such as copper. The lifespan has been extended by more than 5 times. As a result, it is not only useful for manual welding work, but also for automatic welding equipment (welding robots), which can perform stable and homogeneous welding over a long period of time without frequently replacing the nozzle. Welding equipment can be brought to bear.

Moreover, since the ceramic nozzle n itself has a female thread and is screwed into the structure, the structure is simple, the overall strength of the welding torch is high, and the nozzle can be easily replaced. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing an example of a general welding apparatus in which a welding torch is used, and FIG. 2 is an enlarged cutaway view of only the nozzle constituting the welding torch according to the present invention. R: wire reel, T, t: welding torch, S,
s: chip, N, n: nozzle, W: wire.

Claims (1)

[Scope of utility model registration request] In a welding torch that is configured to include a current-carrying chip inside a cylindrical body for introducing an inert gas, and to send a metal wire through the chip, the tip of the cylindrical body has a surface roughness of Rmax3S or less. A tapered silicon nitride ceramic nozzle is screwed onto the nozzle.
A welding torch characterized by being made of dense silicon nitride ceramic fired at ℃ and having a bending strength of 3000 Kg/cm ² or more.