JPH03291169A - Carbon dioxide gas arc welding torch nozzle - Google Patents

Abstract

PURPOSE:To provide high heat resistance, wear resistance and electrical insulation and to prevent wear of the nozzle by an electric discharge phenomenon between the nozzle and materials to be welded by coating silicon nitride on the surface of the nozzle. CONSTITUTION:The nozzle 4 is made of stainless steel or chromium copper and in the case of stainless steel, silicon nitride coating 10 is executed by the physical deposition method on the inside and outside and end face of the tip 4a at least. In the case of chromium copper, titanium nitride coating 11 is executed thereon by the chemical deposition method as pretreatment and then, silicon nitride coating 10 is executed thereon repeatedly by the chemical deposition method in the same way. Consequently, the high heat resistance, wear resistance and electrical insulation are provided and heat by return ion can be prevented and sticking of spatters can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a nozzle for a carbon dioxide arc welding torch that is widely used in many industries such as the machinery industry and shipbuilding industry.

(Conventional technology) Conventionally, nozzles for carbon dioxide arc welding torches have been made of chrome copper or plated with chrome because of their good thermal conductivity and good heat dissipation. A cylindrical nozzle covers the outside of the contact tip, feeds out the welding wire from inside the contact tip, energizes the welding wire through the contact tip, and ejects carbon dioxide gas from between the contact tip and the nozzle to remove this carbon dioxide. Welding is performed in a gas atmosphere while preventing oxidation, and the welding wire used has a diameter of 0. 9mm to 2. Several types between 4 mm were commonly used.

In addition, Utility Model Application Publication No. 63-9058 related to the application filed by the present inventors, etc.
No. 0 discloses a product made of aluminum with an ultra-hard alumite film formed thereon and a Teflon or silicone top coat applied thereon.

(Problem to be Solved by the Invention) The nozzle for a carbon dioxide arc welding torch is heated to a high temperature by return ions from welding, radiant heat, and heat conduction from scattered spatter. If touched, spatter will weld to the nozzle and
This spatter connects with spatter similarly welded to the contact tip, creating a bridge between the nozzle and the contact tip, allowing current to flow from the contact tip to the insulated nozzle through this bridge, and when current flows through the nozzle, the nozzle An electrical discharge phenomenon occurs between the object to be welded and the tip of the nozzle melts, and this spatter becomes an obstruction to the carbon dioxide gas passage, inhibiting the ejection of carbon dioxide gas, and causing carbon dioxide in the welded area. There was a problem in that the gas atmosphere was broken, leading to oxidation of the welded parts.

Chrome copper, which has excellent thermal conductivity and good heat dissipation, was used to prevent spatter from adhering to these nozzles, but chrome copper has a relatively low melting temperature and cannot prevent spatter from adhering to it. Therefore, it was necessary to remove the adhering spatter from time to time, and the nozzle was removed and the spatter was scraped off using a sharp knife, but it was not easy to remove, was troublesome, and reduced welding efficiency. This was causing a decrease in

In addition, in order to prevent spatter adhesion as much as possible, during welding, the tip of a 1-chi was often immersed in a liquid spatter adhesion preventive agent to apply the spatter adhesion preventive agent. Welding must be frequently interrupted to apply inhibitors, reducing welding efficiency and making automatic continuous welding difficult.
Furthermore, when a spatter adhesion prevention agent is used, there is a problem in that the spatter adhesion prevention agent adheres to the welded part and inhibits the adhesion of the coating when it is applied to the welded object in a subsequent process.

As described above, conventional nozzles are subject to severe wear and tear, cannot withstand long-term use, and are treated as consumable items.

In addition, a product in which a super-hard alumite film is formed on aluminum and then a top coat of silicone, etc. Also, the resistance of the top coat to thermal shock (rapid temperature change) was not as strong as that of ceramics, and the durability was not fully satisfactory.

The purpose of this invention is to provide a nozzle for a carbon dioxide arc welding torch that eliminates the above-mentioned conventional problems, prevents spatter from adhering to the nozzle as much as possible, and has excellent durability.

(Means for Solving the Problems) To achieve the above object, the present invention provides a carbon dioxide gas arc welding torch, which has a cylindrical body made of iron or copper-based metal, and has a cylindrical body coated with silicon nitride on at least the inner and outer surfaces and end surfaces of the tip. This is a nozzle for

Further, the present invention is a nozzle for a carbon dioxide arc welding torch in which the metal is stainless steel.

(Function) Iron-based metals have poor thermal conductivity, so they may not be suitable for nozzles that need to avoid temperature rises, but they have the advantage of being highly heat resistant and not easily melted, making it difficult for spatter to adhere. .

On the other hand, although copper-based metals are inferior to iron-based metals in heat resistance as described above, they have the advantage of high thermal conductivity and good heat dissipation.

In addition, silicon nitride (SisN4) to be coated is
It has extremely high heat resistance, non-insulating properties, and abrasion resistance, and can be used at a processing temperature of 70°C for chemical vapor deposition (CvD) and physical vapor deposition (PVD).
Since iron-based metals (particularly stainless steel) have sufficient heat resistance from 0°C to 900°C, they can be easily coated by both of the above vapor deposition methods.

In addition, titanium nitride (TiN) is used as a pretreatment for copper-based metals.
After forming the film, silicon nitride can be coated by chemical vapor deposition (CVD).

Thus, nozzles made of iron or copper metal coated with silicon nitride have high heat resistance and low wettability (affinity) for molten metal, making it difficult for spatter to adhere to them. There is no discharge phenomenon between the welding material and the silicon nitride film, which has high wear resistance and long life due to the high hardness of the silicon nitride film, and there is no need to use a spatter adhesion inhibitor.

(Example) This invention will be described in detail below based on an example shown in the drawings.

First, the configuration of the carbon dioxide arc welding torch will be explained with reference to a vertical sectional view of the tip of the carbon dioxide arc welding torch illustrated in FIG.

In the figure, (1) is the torch body, which is made of a cylindrical body.
An inner tube (2) is inserted into the inner hole (1a), and a welding wire (not shown) is passed through the inner tube (2) to connect the outer periphery of the inner tube (2) and the inner hole (la). Carbon dioxide gas passes through the gap with the inner circumference.

(3) is a contact tip made of chrome copper, has a wire passing hole (3a) in the center with an inner diameter approximately equal to the diameter of the welding wire, the rear end is screwed into the tip of the torch body (1), and the wire is A through hole (3a) communicates with the inner tube (2), and a welding wire passing through the inner tube (2) passes through the wire through hole (3a) and exits from the tip to be welded.

The welding wire is energized from the torch body (1) through the contact tip (3).

(4) is a nozzle made of stainless steel and an insulating cylinder (5) made of an electrical insulator screwed onto the outer periphery of the torch body (1).
), the rear end is screwed onto the male screw (6) fitted on the outer periphery of the contact tip (3), and the contact tip (3) is fitted over the outer periphery of the contact tip (3).
A space serving as a carbon dioxide gas passage (7) is formed between the inner periphery of the nozzle (4) and the outer periphery of the contact tip (3).

(8) is the orifice, which is a cylindrical body made of an electrical insulator such as ceramic and has a tapered outer periphery.
) is fitted onto the outer periphery of the tip of the nozzle (4), and the outer periphery of the large diameter part at the rear end is in close contact with the inner diameter of the nozzle (4), and the rear end surface is fitted with the insulating tube (
5), and is attached to the deep part of the carbon dioxide gas passage (7), and penetrates to the outer circumference through a gap (9) formed between the torch body (1) and the outer circumference of the torch body (1) by scraping the inner circumference. A plurality of orifice holes (8a) are provided on the circumference.

This orifice (8) is located in the inner hole (1) of the torch body (1).
Carbon dioxide gas supplied from the space between a) and the outer periphery of the inner tube (2) passes through a plurality of gas holes (1b) provided on the circumference near the tip of the torch body (1) and fills the void. This serves as a discharge port for carbon dioxide gas that exits from the orifice hole (8a) and then exits from the orifice hole (8a) to the carbon dioxide gas passage (7).

The nozzle (4) is the main body of the present invention, and is made of stainless steel or chrome copper in the shape shown in FIG.
In the case of stainless steel, as shown in Figure 3, a silicon nitride coating (10) of about 3 μm is applied by chemical vapor deposition (CVD).
or by physical vapor deposition (PVD), and in the case of chromium copper, as shown in Figure 4, 1 to 2
After applying the titanium nitride coating (11) with a thickness of μ, a silicon nitride coating (10) with a thickness of approximately 3μ is similarly applied in an overlapping manner by chemical vapor deposition (CVD).

This silicon nitride coating (10) may be applied not only to the tip but also to the entire portion.

Thus, if the base material of the nozzle (4) is made of stainless steel, it has the advantage that it has a high melting point and is difficult to melt when heated during welding, although it has poor thermal conductivity, and if it is made of chrome copper, it has the advantage of being difficult to melt when heated during welding. Although it has the disadvantage of high cost because it requires a titanium nitride coating (11), it is superior to stainless steel in that it is made of heat dissipating material.

In any case, a silicon nitride coating (l) is applied to the surface.
O) has a high degree of heat resistance, abrasion resistance, and electrical insulation, and can prevent heating due to return ions and can prevent sputtering from adhering.

Therefore, spatter does not inhibit the ejection of carbon dioxide gas, and there is no need to use a sputter adhesion inhibitor.

(Effects of the invention) According to the carbon dioxide gas welding nozzle related to this invention as explained above, silicon nitride is coated on the surface of the nozzle, so that it has a high degree of heat resistance, abrasion resistance, and electrical insulation. It repels return ions from arc discharge and reduces heating, and also has high resistance to thermal shock, that is, rapid heating, and reduces wettability (affinity) for molten metal (sputter). It is possible to prevent adhesion of spatter, and also to prevent current flow from the contact tip due to the cross-linked state of spatter, thereby preventing wear and tear on the nozzle due to discharge phenomena between the nozzle and the object to be welded.

Furthermore, there is no need to use spatter adhesion inhibitors, making continuous welding possible, improving efficiency, and making it easier to automate welding as there is no need to interrupt welding to apply spatter adhesion prevention agents. It is something that can be done.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the tip of an embodiment of a carbon dioxide arc welding torch, FIG. 2 is a partially cutaway side view of the nozzle,
FIG. 3 is a locally enlarged cross-sectional view of the nozzle tip portion whose base material is stainless steel, and FIG. 4 is a local enlarged cross-sectional view of the nozzle tip portion whose base material is chrome copper. 4.Nozzle■ ・Silicon nitride coating Utility model registration applicant Techno Co., Ltd.

Claims (2)

[Claims] (1) A nozzle for a carbon dioxide arc welding torch, characterized in that the inner and outer surfaces and end surfaces of at least the tip of a cylinder made of iron or copper-based metal are coated with silicon nitride. (2) A nozzle for a carbon dioxide arc welding torch according to claim 1, wherein the metal is stainless steel.