JPH0442067Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a welding nozzle for arc welding using carbon dioxide gas, argon gas, or the like as a shielding gas. [Prior art] Arc welding is currently widely used when joining metals, and gas shielding is used to weld by supplying inert gas or carbon dioxide gas to the molten metal to prevent welding defects such as blowholes. Arc welding is widely used. Among these, carbon dioxide arc welding, which uses carbon dioxide as a shielding gas, has become the mainstream gas shield welding method because the shielding gas is inexpensive and it is possible to obtain a high welding rate. Used in 30%. For example, the price of the shielding gas used for carbon dioxide arc welding is the price of MAG, which uses a mixture of carbon dioxide and argon gas as the shielding gas.
It is about 1/10 of welding. However, carbon dioxide arc welding produces 3 to 5 spatter compared to MAG welding.
It has the disadvantage of being twice as large. This spatter refers to slag and molten metal that are scattered during welding, and molten metal accounts for 80% of it, with iron being the main component. The occurrence of spatter in carbon dioxide arc welding is mainly due to the following four causes. This occurs when welding wire droplets collide with the cold material to be welded and scatter when welding is started or when re-arcing. Gas blows out from within the molten metal, and spatter occurs as the gas is released. When the arc voltage fluctuates during welding, the amount of welding wire fed changes, increasing the amount of welding wire that melts, which causes spatter. The arc length increases, and the droplets suspended at the end of the wire are blown sideways by the arc force. During welding, the temperature at the welding point reaches 1,700 to 1,800 degrees Celsius, and the temperature of the molten metal reaches 1,800 to 2,300 degrees Celsius. When this molten metal spatters, it adheres to the contact tip and welding nozzle. The causes of spatter adhering to tips and nozzles include metallurgical causes and physical causes. The metallurgical cause is that the molten metal that collides with the chip or nozzle melts the surface of the chip or nozzle due to its heat, and welds to the surface. Therefore, the higher the temperature of the spatter and the higher the temperature of the chip or nozzle, the thicker the alloy layer becomes, which makes the adhesion of the spatter stronger and harder to remove. The physical cause is mechanical adhesion caused by the roughness of the chip or nozzle surface. Therefore, in order to reduce the adhesion of spatter, we
61-77175, where the electrode tip and torch nozzle are coated with a thin layer of hard ceramics, and JP-A-61-111783, which has good thermal conductivity and It is known that the nozzle is made of non-oxide ceramics with a low coefficient of thermal expansion to prevent it from cracking during welding. [Problem that the invention aims to solve] However, the nozzle made of the above-mentioned copper alloy has high thermal conductivity and good cooling performance, so it is said that spatter does not easily form. Metallurgically and physically, spatter easily adheres (fixes), resulting in a durability problem. Further, due to its physical properties, copper or copper-based alloys undergo work hardening and heating softening. The former occurs at room temperature, and the latter at around 200-300°C. Immediately after being processed and created, the nozzle is hardened and therefore has high hardness, but due to heat radiation and contact with hot spatter, the temperature of the nozzle rises and softens as time passes. go. When cleaning the nozzle, a gold brush or the like is used, but as the nozzle gradually softens, it becomes easily scratched. When scratches occur, spatter tends to adhere there, and as time passes, spatter adheres to the nozzle, reducing the nozzle diameter, resulting in gas restriction and insufficient gas shielding, which causes blowholes to occur. On the other hand, silicon nitride ceramic nozzles are metallurgical,
Although the physical adhesion of spatter was eliminated, it inevitably became thick-walled and had relatively low thermal conductivity, making it easy to remove spatter, but it was not sufficient. The present invention has been developed in view of the above circumstances, and provides a welding nozzle made of iron or iron-based alloy coated with ceramic, which improves the durability of the nozzle, improves heat dissipation, and reduces adhesion of spatter. The purpose is to [Means and effects for solving the problem] The present invention to achieve the above object is provided around an electrode tip in which an electrode or welding wire is arranged in the center, and a gas In a metal welding nozzle that forms a passage, the nozzle is made of ultra-thin iron or iron-based alloy with a wall thickness of 1 mm to 1.5 mm, and the inner layer is a titanium carbide layer and the outer layer is a titanium nitride layer on the entire inner and outer periphery. It has a ceramic coating. Examples of metals used in the present invention include iron, aluminum, titanium, nickel, chromium, zinc, tin, and alloys of these metals, excluding copper or copper alloys. In addition, oxide ceramics include alumina, and non-oxide ceramics include silicon nitride, silicon carbide, sialon, and
Examples include aluminum nitride. Since the welding nozzle of the present invention is made of the above-mentioned metal, it is unlikely to be softened by heating during welding work, and the adhesion of spatter can be prevented. On the other hand, the metal used in this invention has a lower thermal conductivity than copper and copper-based metals, so it has poor heat conduction (heat dissipation) immediately after contact with spatter, and heat accumulation occurs, causing the temperature of the nozzle itself to rise. In contrast, the present invention forms a ceramic layer on the entire surface of the nozzle that is less likely to react to spatter, with a ceramic coating consisting of a titanium carbide inner layer and a titanium nitride outer layer, and further reduces the thickness of the nozzle. This is achieved by making the nozzle extremely thin, about 1/2 to 1/3 the thickness of a conventional copper nozzle, which is 2 to 3 mm, to prevent temperature rise and spatter adhesion. [Example] Next, an example of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which the entire inner and outer periphery of a welding nozzle 1 made of ferrous metal is covered with a ceramic coating part 3. There are mounting screws 2 on the inner periphery of the base of the welding nozzle 1.
is cut. The welding nozzle has a wall thickness of approximately 1/2 to 1/2 of the thickness of the conventional copper alloy nozzle 1a shown in Fig. 2.
It is formed to 1/3 of 1 mm to 1.5 mm. This value was determined from the amount of heat transferred Q. The amount of transferred heat Q [KCaI] can be calculated from the following equation (1). Q=λSt ₁ −t ₂ /dτ …(1) In the above equation (1), λ: Thermal conductivity [KCaI/m・hr・℃] S: Area [m ² ] d: Thickness [m] t ₁ , t ₂ ; internal and external temperature [°C]; τ; time [hr]; from this equation, the relationship Q∝λ/d can be understood. Next, the thermal conductivities of conventionally used copper and copper-based alloy nozzles and the iron-based alloy (common steel, die steel) of this example were measured, and the results were as shown in Table 1.

[Table] From the results in Table 1 above, it was found that since the ratio of thermal conductivity λ was approximately 2, it was possible to cope with the temperature rise by reducing the nozzle thickness to 1/2. Next, an experiment to investigate the state of spatter adhesion will be explained. In the experiment, ordinary steel (SS) and die steel (SKD-11) were used as materials for iron or iron-based alloys.
Nozzle 1 of the shape shown in Fig. 1 is made using two types of
The first layer of titanium carbide and the second layer of titanium nitride were formed using a chemical vapor deposition (CVD) device, with the furnace temperature (reaction temperature) set at 1030°C. Ta. Among the ceramic-coated nozzles, the common steel nozzle was reheated to 500°C, cooled in oil, and quenched to be used as a test product. On the other hand, since the die steel nozzle had already been quenched, it was tempered to 200°C and used as a test product. The two types of test products manufactured in this way were used in the same process and under the same working conditions as conventional copper-based alloy nozzles on an on-site arc welding line.
Welding was carried out on 200 units, and the results shown in Table 2 regarding the amount of spatter deposited were obtained.

[Effect of idea]

As explained above, according to the present invention, the nozzle is made of iron or an iron-based alloy, and has a wall thickness of 1 mm to 1.5 mm.
Because iron has a low thermal conductivity, by making the wall thickness extremely thin due to the total heat transfer, it is possible to prevent temperature rise during welding, similar to copper-based nozzles. Since it is made of alloy, it does not soften when heated during welding, which prevents the occurrence of blowholes, and the durability is significantly improved compared to copper nozzles. Furthermore, the inner layer is a titanium carbide layer, and the outer layer is a ceramic coating with a titanium nitride layer. Therefore, the ceramic coating layer is strong, has low thermal conductivity, and is particularly hard because the outer layer is made of titanium nitride, and since spatter does not easily react on it, the adhesion of spatter can be greatly reduced, which makes it possible to weld. This has a great effect of improving the operating rate of the equipment. Furthermore, by using the iron or iron-based alloy welding nozzle according to the present invention, the cost can be reduced by half compared to copper-based nozzles.

[Brief explanation of drawings]

FIG. 1 is a partially sectional front view of an embodiment of a ceramic-coated metal welding nozzle according to the present invention, and FIG. 2 is a partially sectional front view of a conventional copper alloy welding nozzle. 1... Iron-based alloy nozzle, (metal nozzle), 1a
...Copper alloy nozzle, 3...Ceramic coating part.

Claims (1)

[Scope of utility model registration request] In a metal welding nozzle that is provided around an electrode tip with an electrode or welding wire arranged in the center and forms a gas passage between the electrode tip and the electrode tip,
The nozzle is made of ultra-thin iron or iron-based alloy with a wall thickness of 1 mm to 1.5 mm, and is characterized in that its inner and outer peripheries are coated with ceramic, with the inner layer being a titanium carbide layer and the outer layer being a titanium nitride layer. Metal welding nozzle with ceramic coating.