JPH05300Y2 - - 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 is 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 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. On the other hand, the nozzle that guides the shielding gas to the tip of the welding torch has a high temperature of 1700 to 1800 degrees Celsius near the welding point near the tip of the welding torch. It was made of high-grade copper or copper alloy. As a result, the surface hardness of the nozzle becomes low, resulting in the problem that the spatter mentioned above tends to adhere. Proposals to solve this problem include coating the electrode tip and torch nozzle with a thin layer of hard ceramic, as disclosed in Japanese Utility Model Application Publication No. 61-77175, in order to reduce spatter adhesion; Japanese Patent Laid-Open No. 61-111783 discloses a nozzle made of a tragic oxide ceramic having good thermal conductivity and a low coefficient of thermal expansion to prevent it from cracking during welding work. Further, as proposed by the applicant of the present application in Japanese Utility Model Application Publication No. 63-47074, the surface of a nozzle made of iron-based metal is coated with ceramic. [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 problems with durability. 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 has been eliminated, it inevitably becomes a thick-walled shape and has a relatively low thermal conductivity, making it easy to remove spatter, but it cannot be said to be sufficient. In addition, the proposal by Utility Model Application Publication No. 63-47074 is
Since the ceramic coating layer is relatively thin, there was a drawback that the ceramic coating layer was damaged by melted spatter, as shown in the micrograph of FIG. The present invention was developed in view of the above circumstances, and aims to provide a ceramic-coated metal welding nozzle that improves the durability of the nozzle, improves heat dissipation, and reduces spatter adhesion. . [Means for Solving the Problems] The present invention for achieving the above-mentioned object is provided around an electrode chip in which an electrode or welding wire is arranged in the center, and a gas passage is provided between the electrode chip and the electrode chip. In the metal welding nozzle to be formed, the nozzle is formed of an extremely thin iron-based metal with a wall thickness of 1 mm to 1.5 mm, and is coated with multiple ceramic layers consisting of two layers of titanium carbide and titanium nitride on the entire inner and outer periphery. It was formed. [Function] According to the above structure, since the welding nozzle is made of iron-based metal, softening due to heating is less likely to occur during welding work, and the adhesion of spatter can be prevented. On the other hand, iron-based metals have lower thermal conductivity than copper and copper-based metals, so heat conduction (heat radiation) is poor immediately after contact with spatter, and heat buildup occurs, causing the temperature of the nozzle itself to rise. However, the present invention prevents temperature rise by making the nozzle's wall thickness extremely thin, about 1/2 to 1/3 of the conventional copper nozzle, which is 2 to 3 mm, and prevents spatter on the surface. By forming a non-reactive ceramic layer, spatter adhesion is prevented.In addition, the ceramic layer is formed as two layers of ultra-hard titanium carbide and titanium nitride, and this ceramic layer is formed on the surface of a multi-layer nozzle. This prevents damage to the coating film. [Embodiment] Hereinafter, an embodiment of a ceramic-coated metal welding nozzle according to the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention. The almost cylindrical nozzle 1 is made by heating common steel (SS) to about 500℃ and cooling it with oil, or by heating die steel (SKD-11) to about 200℃.
It is formed by tempering at ℃. The entire inner and outer periphery of this nozzle 1 is coated with titanium carbide in the first layer and titanium nitride in the second layer by chemical vapor deposition (CVD).
It is deposited at a temperature of 1030℃, and one deposition process produces approximately
A ceramic coating 2 of 8 μm is formed. This vapor deposition was repeated five times to grow the film to a thickness of about 22 μm. Further, the wall thickness of the nozzle 1 is formed to be 1 to 1.5 mm, which is about 1/2 to 1/3 of the thickness of the conventional nozzle 3 shown in FIG. A mounting screw 4 is formed on the inner diameter side of the base of the nozzle 1, similar to the conventional nozzle 3. Next, the operation and effect of this embodiment will be explained. The wall thickness of the nozzle 1 made of iron-based metal is about 1/2 to 1/3 that of the conventional nozzle 4 made of copper-based metal, so the thermal conductivity is 25 to 40 Kcal/m・
hr·°C, which is almost the same as the thermal conductivity of the conventional nozzle 4, so it can cope with temperature increases. Table 1 below shows the results of an experiment on the amount of spatter deposited on a production line.

[Effect of idea]

As described above, according to the present invention, the welding nozzle is made of an extremely thin iron-based metal with a wall thickness of 1 mm to 1.5 mm, and multiple ceramic layers made of two layers of titanium carbide and titanium nitride are formed on the surface. Therefore, it is possible to prevent temperature rise during welding, reduce the amount of spatter deposited, prevent damage to the ceramic layer due to spatter, greatly improve the durability of the nozzle, and improve the operating rate of the welding equipment.

[Brief explanation of the drawing]

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

Claims (1)

[Claims for Utility Model Registration] (1) A metal welding nozzle that is provided around an electrode chip in which an electrode or a welding wire is arranged in the center and forms a gas passage between the nozzle and the electrode chip. It is made of ultra-thin iron-based metal with a wall thickness of 1 mm to 1.5 mm, and is coated with ceramic, characterized by having multiple ceramic layers made of two layers of titanium carbide and titanium nitride formed on the entire inner and outer periphery. Metal welding nozzle. (2) The ceramic-coated metal welding nozzle according to claim 1, which is characterized in that ordinary steel or die steel is used as the ferrous metal.