JPH0361545B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a material for a contact tip of an arc welding torch. [Background of the Invention] An arc welding contact tip is a part used at the tip of a welding torch to hold a welding wire. Conventionally existing metal contact tips (Fig. 5) do not produce spatter (molten metal) due to the sputtering phenomenon in which weld metal scatters during welding.
This caused the welding wire to adhere to the welding wire, making it impossible to hold the welding wire in an accurate position. For this reason, various techniques have been proposed to coat the surface of a metal contact chip with ceramic. However, these techniques have the following drawbacks. Utility patent application Sho 50-76021, Utility patent application Sho 52-26630, Utility patent application Sho 57-160887. In these techniques, the ceramic is merely coated with a coating technique, and the film thickness is too thin, resulting in a lack of durability. Jitsukaisho 57-82484, Jitsukaisaki
59−49478. In these techniques, the outer periphery of the contact chip itself is formed of ceramic rather than ceramic coating, and the above-mentioned drawbacks are eliminated. However, simply forming it from ceramics would not be practical because the ceramic would crack due to the heat generated during arc welding and the heat from adhesion of spatter. [Object of the Invention] The present invention has been made in view of the above problems, and an object of the present invention is to provide a contact tip made of ceramics that does not crack during welding work. [Means for achieving the object] In order to achieve the above object, the present invention provides a thermal conductivity of 0.03 [cal/cm.
sec・℃] or more, the thermal expansion coefficient is 7.3×10 ^-6 [1/℃]
A cap made of at least one non-oxide ceramic selected from SiC, Si ₃ N ₄ , BN, B ₄ C is attached, and the outer peripheral surface of the cap is coated with chemical vapor deposition or physical vapor deposition. According to
It is characterized by forming a single layer or multiple layers of at least one type of titanium compound selected from TiC, TiN, and TiC+TiN. The inventor considered that the cause of cracks in ceramic contact tips is that the ceramic contact tips are locally heated and expanded by the heat during arc welding and the heat when spatter is attached. Therefore, in order to prevent cracking, we thought it would be a good idea to find out what range of thermal conductivity and coefficient of thermal expansion should be used among ceramics that can have a variety of physical properties. Therefore, the contact chips shown in FIG. 1 were manufactured from various ceramics, and experiments were conducted to determine whether or not cracks would occur by welding using these ceramic contact chips. The results of this experiment are shown in Table 1.

【table】

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG.
The contact chip of this example is the same as the contact chip of FIG. 1 used in the above experiment.
A titanium compound is used on the outer surface of the contact tip.
The coating is done by chemical vapor deposition of TiC. The contact tip body 1 is screwed into the tip of a head adapter (not shown) through a threaded portion 2 provided at the base. A hole 3 for passing a welding wire (not shown) is formed in the center. A cap 4 of the contact tip according to this embodiment is provided on the outer periphery of the tip. This cap 4 is screwed onto the outer periphery of the tip of the contact tip body 1 by means of a threaded portion 5 provided on the inner periphery. Cap 4 is
It is made of SiC ceramics, and a TiC layer 6 is chemically vapor deposited on the outer peripheral surface. This makes it even more heat resistant.
Not only the wear resistance is improved, but also the adhesion of welding spatter can be further suppressed. The reason is TiC
Depending on the coating, the surface hardness is 3300-4000
(VHN) and can be made to have a surface roughness of 1 μRZ or less by chemical vapor deposition, which prevents spatter, which is molten metal, from getting stuck on the surface of the contact chip. Furthermore, even after the spatter that has adhered to the chip is removed with a metal brush, the high hardness makes it wear-resistant, so the surface does not get scratched and maintains a smooth surface with low surface roughness, making it suitable for use as a ceramic contact chip. Lifespan can be further extended. [Other Embodiments] The cap 4 in the above embodiments was provided on the long outer circumference of the tip of the contact tip body 1, but in other embodiments it was provided as shown in FIGS. 3 and 4. It can also be provided in a short portion at the tip of the contact tip body 1. In this case as well, the outer surface may be coated with a titanium compound as shown in FIG. In the first embodiment, the cap 4 was attached to the contact chip body 1 by a threaded portion 5, but in other embodiments, it may be attached with an inorganic adhesive (for example, Aron Ceramics D manufactured by Toagosei Kagaku). is also possible. The cap 4 shown in FIG. 3 is bonded with this inorganic adhesive 7. In the above embodiments, the material of the cap is SiC, but the present invention is not limited thereto, and the material of the cap has a thermal conductivity of 0.03.
[cal/cm・sec・℃] or more, thermal expansion coefficient is 7.3×
In addition to SiC and Si ₃ N ₄ , which exhibit properties of less than 10 ^-6 [1/℃], they are also hexagonal and have covalent properties, and have a thermal conductivity of 0.036 to 0.069 [cal/cm・sec・℃〕,
BN with thermal expansion coefficient 0.5 to 1.7×10 ^-6 [1/℃], thermal conductivity 0.03 to 0.3 [cal/cm・sec・℃], thermal expansion coefficient
Non-oxide ceramics selected from B ₄ C with a temperature of 4.5×10 ^-6 [1/°C] can be used. Also,
In each of the above examples, the material of the outer peripheral layer was TiC,
The present invention is not limited to this, but the material of the outer peripheral layer is an equiaxed crystal system like TiC,
At least one type of titanium compound selected from TiN or a mixture of the two, TiC+TiN, which has similar properties such as heat resistance, and can be deposited not only by chemical vapor deposition but also by physical vapor deposition. It is. [Effects of the Invention] According to the contact tip for arc welding of the present invention, cracking during welding work can be prevented, and a practical ceramic cap of the contact tip can be provided.

[Brief explanation of drawings]

1 to 4 are longitudinal sectional views of a contact chip according to an embodiment of the present invention, and FIG. 5 is a longitudinal sectional view of a conventional contact chip. 1...Contact chip body, 2...Threaded part,
3...hole, 4...cap, 5...screw part, 6...
...TiC layer.

Claims (1)

[Claims] 1. The outer periphery of the tip of a copper alloy contact tip used in an arc welding torch has a thermal conductivity.
0.03 [cal/cm・sec・℃] or more, thermal expansion coefficient 7.3
SiC, Si ₃ N ₄ , BN, less than ×10 ^-6 [1/℃]
A cap formed of at least one type of non-oxide ceramic selected from B ₄ C is attached, and a material selected from TiC, TiN, TiC+TiN is attached to the outer peripheral surface of the cap by chemical vapor deposition or physical vapor deposition. A contact tip for arc welding, characterized in that a single layer or multiple layers of at least one selected titanium compound are formed.