JPH0337470B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a ceramic contact chip used in arc welding that causes less adhesion of spatter, has a long life, and is reusable, and a method for manufacturing the same. [Prior Art] Conventional arc welding contact tips were mainly made of copper alloy or aluminum alloy, but since the surface of the contact tip is metal,
Spatter flying during arc welding may adhere to and accumulate on the surface of the contact tip due to thermochemical reactions, causing clogging, or the contact tip may be annealed and softened by the radiant heat during welding, and the tip of the contact tip may wear out as the wire passes through it. Due to acceleration, etc., the lifespan of arc welding contact tips was extremely short. As a method to solve the above-mentioned problems, as described in Japanese Utility Model Application Publication No. 52-26630, Japanese Utility Model Application Publication No. 59-49478, or Japanese Utility Model Application Publication No. 57-8248, the nozzle part of the contact chip is Method for protecting ceramic guides, or Japanese Utility Model Application Publication No. 50-76021,
A method of coating contact chips with ceramic has been proposed as described in Japanese Utility Model Application Publication No. 57-160887. However, the above-mentioned method of protecting the nozzle part with a ceramic guide not only complicates the structure of the contact chip and causes problems in terms of manufacturing costs, but also has the problem that the entire contact chip cannot be protected from spatter that is scattered over a wide area. It was hot. On the other hand, the method of coating contact chips with ceramic solves the problems of complicating the structure and protecting the entire chip from spatter adhesion. It was developed and previously filed as Utility Model Application No. 163202/1983 (see Japanese Utility Model Application No. 77175/1983). However, even in the ceramic-coated contact chip mentioned above, since the base itself is made of metal, especially copper alloy or aluminum alloy,
Due to the annealing softening in the ceramic coating and the annealing softening due to the radiant heat during arc welding, wear resistance decreased and there was a natural limit to the service life. Furthermore, once the nozzle becomes unusable due to clogging or abrasion, there is currently no way to recycle it and it is discarded, which is another major factor that increases the cost of arc welding. . In addition, the present inventors have developed a contact chip substrate made of 92% Al ₂ O ₃ to solve the above-mentioned problem.
Composed of ceramics such as SiC or Si ₃ N ₄ ,
He invented a contact chip for arc welding in which the inner wall of the wire guide hole was coated with a good electrical conductor, and filed an application earlier. This invention solves the problem of nozzle wear and reuse caused by annealing softening, and significantly extends the life of the contact tip.However, regarding spatter adhesion during welding, it is much more common than metal contact tips. Although the width has been reduced significantly, the problem of spatter adhesion still remains because the ceramic has some reactivity with spatters whose main component is Fe. [Problems to be Solved by the Invention] The present invention provides a ceramic contact chip for arc welding that simultaneously solves the problem of clogging due to adhesion of spatter and the problem of wear resistance as described above, and is reproducible repeatedly. The purpose of this invention is to provide a manufacturing method that allows chips to be manufactured stably and reliably. [Means for Solving the Problems] As a result of intensive research into means for solving the above-mentioned problems, the present invention changes the conventional concept that arc welding contact tips are made of metal, which is a good electrical conductor, and In addition to the invention of the earlier application by the present inventors, in which the arc welding contact chip base 1 shown in FIG. 1 is made of ceramic, and only the part that feeds power to the wire is made of a good electrical conductor 3, FIG. As shown, the above object is achieved by providing a coating layer 6 of TiC, TiN or Ti (C+N), which has low reactivity with sputtering mainly composed of Fe, on the surface of a ceramic contact chip base 1. It was completed based on the knowledge that Furthermore, to explain the specific configuration of the present invention in detail,
The base body 1 of the contact tip for arc welding is preferably made of 92% Al ₂ O ₃ , SiC-based or Si ₃ N ₄ with a thermal conductivity of 0.03 cal/cm・sec・℃ or higher and a thermal expansion coefficient of 7.3×.
10 ^-6 1/℃ or less and bending strength of 2500 kg/cm ² or more, and the surface of the base 1 is coated with Fe as the main component by PVD, CVD, plasma spraying, etc. TiC, TiN or Ti (C+N) with low spatter and reactivity
By forming a coating layer 6 of a good electrical conductor such as copper, copper alloy, Ni alloy, gold alloy, silver alloy, platinum alloy, titanium alloy, etc. on the inner wall of the wire guide hole 2 of the base, There is very little spatter adhesion during welding, and there are no problems with wear.
A ceramic contact chip for arc welding that can be used repeatedly is obtained. As a method for industrially stably manufacturing the ceramic contact chip for arc welding described above, TiC, TiN, or Ti (C+N) is applied to the surface of the ceramic contact chip base 1 prepared in advance.
Coating layer 6 by CVD method, PVD method or plasma method
and a third method in which the inner wall of the wire guide hole 2 of the ceramic contact chip base is previously coated with a good electrical conductor, and then electroplated with a good electrical conductor 3 using the coating layer made of the good electrical conductor as an electrode. As shown in the figure, a pipe 4 of a good electrical conductor with an outer diameter approximately the same as the diameter of the wire guide hole 2 of the ceramic contact chip base 1 is prepared in advance, and this pipe 4 is inserted into the guide hole 2 of the ceramic contact chip base 1. We have developed a method to do this. As a method for electroplating a good electrical conductor on the inner wall of the guide hole of the ceramic contact chip mentioned above, any known method for electroplating metal on ceramic can be adopted, but according to the research of the present inventors, the following method is used. It has been found that good results are reliably obtained when plating with (b) Is an electrical conductor by CVD method or PVD method
After coating the inner wall of the guide hole with TiC or TiN, etc., use the coated TiC or TiN electrically conductive layer as an electrode to conduct Cu-based alloy, Ni-based alloy, silver-based alloy, gold-based alloy, Platita-based alloy, or Ti-based A method of electroplating good electrical conductors such as alloys. (b) After coating the inner wall of the guide hole with metal powder in paste form or by gluing,
A method in which an electrically conductive layer is formed on the inner wall of the guide hole by a so-called metallization method in which firing is performed in N ₂ /H ₂ or in a vacuum, and then a good electrical conductor is electroplated in the same manner as in (a). In this metallization method, various metal powders can be used, but when the substrate is an oxide ceramic such as Al ₂ O ₃ , Ni, Mo, Cu, Mo-Mn, and when the substrate is SiC-based. Particularly good results are obtained with the combination of Ni, Mo and, if the substrate is Si ₃ N ₄ based, Mo. (c) A method in which the inner wall of the guide hole is coated with an electrical conductor in advance using an electroless plating method, and then electroplated in the same manner as in (a). The electrical conductor coated by this electroless plating method may be any metal as long as it has electrical conductivity, but from the viewpoint of stability and electrical conductivity, Ni or
Preferably Cu. Note that the coating with the electrically conductive material may extend up to the threaded portion 7 in order to improve the power feeding effect. [Function] In the present invention, since the contact tip base for arc welding is made of ceramic with high hardness and excellent heat resistance, there is no problem of annealing softening during welding compared to conventional metal contact tips. It has excellent wear resistance. In addition, in the present invention, the surface of the ceramic contact chip is further coated with TiC, TiN, or Ti (C+N), which has extremely high hardness and has low reactivity with spatter mainly composed of Fe.
Since it is coated with , there is less adhesion of spatter during welding, and even if spatter does adhere, it can be easily removed. Another great advantage of the present invention is that even if the electrically conductive material provided in the wire guide hole of the contact tip wears out due to the friction caused by the wire passing through it, making it impossible to supply power to the wire, the base of the contact tip will wear down and become unusable. The contact chip substrate can be used repeatedly by recoating it with a good electrical conductor. As for the material of the contact tip base 1 for arc welding of the present invention, any commercially available ceramic can be selected to obtain the desired effect, but the mechanism by which cracks occur in the ceramic contact tip during arc welding is As a result of repeated research and experiments, we found that 92
Thermal conductivity of % _{Al2O3 ,} SiC and _{Si3N4 etc.}
0.03cal/cm・sec.℃ or more, thermal expansion coefficient 7.3×
By selecting ceramics with physical properties of 10 ^-6 1/℃ or less and bending strength of 2500 kg/cm ² or more, we have created an extremely long-life arc welding contact tip that will not crack even after repeated use over long periods of time. It turned out that it was possible to obtain In other words, in arc welding, the contact tip repeatedly undergoes local heating and rapid heating.
Considering the mechanism by which cracks occur in the contact chip due to the thermal shock, the following can be said. When a ceramic contact tip cracks during arc welding, it is when the internal stress generated by heat exceeds the bending strength. In arc welding, the contact tip is repeatedly heated locally and rapidly as described above, and a large temperature gradient occurs in the heated area and its vicinity. That is, the temperature of the welded part is around 1200°C, and the temperature of the contact chip is 200 to 300°C due to the radiant heat and the self-arc heat during power supply. And in a contact chip with a temperature gradient,
Each part exhibits thermal expansion according to its heating temperature, and the difference in the amount of thermal expansion becomes a cause of generating internal stress. Therefore, in order to prevent cracking due to thermal shock during arc welding, that is, to ensure that the internal stress caused by the difference in thermal expansion of each part does not exceed the bending strength, a material with high thermal conductivity must be selected. This reduces the temperature gradient in each part, reduces the amount of thermal expansion in each part by selecting a material with a small coefficient of thermal expansion, reduces the absolute amount of difference in the amount of thermal expansion, and has high bending strength. One possibility is to select the material. Based on the above considerations, the present inventors conducted repeated experiments on various ceramics as shown in Table 1, and found that, as mentioned above, in particular, the thermal conductivity
0.03cal/cm・sec.℃ or more, thermal expansion coefficient 7.3×
When a contact chip base for arc welding is made from ceramic material with physical properties of 10 ^-6 1/℃ or less and a bending strength of 2500 kg/cm ² , no cracks will occur even during long-term repeated arc welding. It was effective.

[Table] Furthermore, in the present invention, an electrically conductive coating layer is provided on the inner wall of the guide hole of the ceramic contact tip base, and current is supplied to the welding wire through this coating layer, so that the radiated heat during arc welding is reduced. It is blocked by the contact chip base, and there is almost no decrease in wear resistance due to melting or annealing softening of the coating layer as a power supply material due to radiated heat. Next, the operation and effect of the method for manufacturing the ceramic contact chip for arc welding, which is the second and third invention of the present application, will be explained. In the second and third inventions, a coating layer 6 of TiC, TiN, or Ti (C+N), which has low reactivity with spatter particles, is formed on the surface of the ceramic contact chip substrate 1. CVD, PVD, or plasma spraying can be used as a method, but when CVD or PVD is used, the coating layer is as thin as a few micrometers, but the surface roughness is high and it remains as it is. However, it has the advantage that there is less adhesion of spatter due to the phenomenon of spatter being trapped due to surface irregularities.On the other hand, when plasma spraying is used, the coating layer can be thickened to more than 100μ, but because the surface of the coating layer is rough, It is necessary to polish to a surface roughness of 20 seconds or less, preferably about 0.5 to 2 seconds. Incidentally, Table 2 shows the relationship between the surface roughness of ceramic contact chips and the surface roughness when each coating method is adopted.

[Table] In the second invention, the electrically conductive coating that will eventually become the power supply material is formed by efficient electroplating. This is because the ceramic that makes up the contact chip base has low electrical conductivity, and it is difficult to apply electroplating directly to it. This is because, in order to apply electroplating to ceramic, the part to be plated must be made into an electrode in advance. In addition, parts coated by CVD, PVD, metallization, or electroless plating are free from contaminants such as oil and fat, and are activated by thermochemical treatment, making electroplating more effective. There is also. In the third invention, a contact tip for arc welding is manufactured by fitting a previously prepared pipe with good electrical conductivity into a guide hole of a ceramic contact tip base. The advantage of the manufacturing method is that it does not require a complicated plating process as in the second invention,
The pipe can be manufactured by a relatively simple operation of manufacturing the pipe by machining and fitting the pipe into the guide hole of the ceramic contact chip base, and the worn pipe can be easily removed and replaced with a new pipe. can be mentioned. Another method of this manufacturing method is
One major advantage is that the pipe can be incorporated into the ceramic contact tip substrate in a work-hardened or heat-hardened state, thereby reducing pipe wear during arc welding use. Regarding the manufacture of the ceramic contact chip base itself, in the same way as in the manufacture of ordinary ceramic products, ceramic powder is mixed with an organic binder and granulated, followed by casting, press molding, or in-die extrusion. It can be manufactured by molding a contact chip base using a molding method and then firing it. However, contact chips for arc welding are provided with threaded parts 7 and 8 for attachment, and these threaded parts are Since processing by machining or the like is disadvantageous in terms of cost, it is advantageous to employ injection molding as shown in the flow sheet of FIG. 6 as a method of molding such a ceramic contact chip substrate for arc welding. <Example> (a) Production of ceramic contact chip substrate An organic binder was added to 92% Al ₂ O ₃ powder in the composition ratio shown below, heat-kneaded and roll granulated as shown in Figure 4 to obtain molding material granules. Raw material composition Alumina (92% blended powder) Ethylene-vinyl acetate copolymer polybutyl methacrylate wax (Wax E) Sibutyl phthalate 100 (parts) 6.0 6.5 3.0 3.0 (parts) The molding material was as follows. It was formed into the shape of a contact chip base for arc welding using the injection molding method under molding conditions. Molding conditions Pressure Temperature Mold temperature Injection time Cooling time 700Kg/cm ² 170-180℃ 25℃ 5sec 20sec After degreasing the contact tip base for arc welding of the above-mentioned form under the following conditions, it is fired and arc welded. A contact chip substrate was created. Degreasing conditions - (room temperature) - 80℃ 3Hrs 80 - 360℃ 5℃/Hr 360℃ Hold for 2Hrs ↓ Cooling firing conditions (in air) - (Room temperature) - 1500℃ 7Hrs 1500℃ Hold for 1H ↓ Cooling (2) Ceramic to the contact chip substrate surface.
Formation of TiC, TiN or Ti (C+N) coating layer CVD onto the surface of the ceramic contact chip base made of 92% Al ₂ O ₃ composed in the above process.
TiC by method, PVD method and plasma spraying method.
A coating layer was formed with TiN and Ti (C+N). (c) Coating the inner wall of the wire guide hole of the ceramic contact chip base with a good electrical conductor Masking the outer surface of the ceramic contact chip on which the TiC, TiN or Ti (C+N) coating layer described above is formed, and coating only the inner wall of the wire guide hole. After electroless plating with Ni, using the Ni electroless plating layer as a cathode, electroplating was performed under the following conditions to form a Cu coating layer with a thickness of 0.1 to 0.3 mm on the inner wall of the wire guide hole. Bath composition Metsuki conditions Cuprous cyanide...120g/
Current density 3A/dm ^2Sodium cyanide...135g/PH 12.6 Caustic potash...25g/Bath temperature 80℃ Free cyanide caustic soda...10g/Time 1.5hr (d) Welding test The arc welding contact tip made in the above process was tested. Table 3 shows the results of a welding test conducted under conditions similar to actual arc welding described below. Welding conditions Voltage…22V Current…240A Number of welding workpieces 600 pieces/day Welding speed 800mm/min Welding length 80mm/1 piece

【table】

[Table] Life is the time until clogging occurs due to spatter adhesion Example 2 (a) Production of ceramic contact chip substrate An organic binder was mixed with Si ₃ N ₄ powder in the composition ratio shown below, as shown in Figure 4. The material for molding was obtained by heat kneading and heat extrusion granulation. Composition: Silicon nitride, blended powder (Si ₃ N ₄ ) Polystyrene methacrylate ester copolymer Ethylene-vinyl acetate copolymer Paraffin wax 56 Dimethyl stearcinate Starlate 100 [parts] 7.0 5.0 4.0 5.0 1.5 4.0 [parts] The molding material was molded into the shape of a contact chip base for arc welding by the injection method under the following conditions, and molding conditions - pressure 850 kg/cm ² temperature Temperature: 220°C Mold temperature: 25°C Injection time: 5 seconds Cooling time: 5 seconds The produced contact chip base for arc welding was degreased and fired under the following conditions.

[Table] (b) Ceramic contact chip substrate surface
Formation of TiC, TiN or Ti (C+N) coating layer TiC, TiN and Ti (C+N) are coated on the surface of the ceramic contact chip substrate prepared in the above process by CVD, PVD and plasma spraying.
A coating layer was formed. (c) Inserting a good electrical conductor pipe into the wire guide hole of the ceramic contact chip base Pipe 4 made of Cu-Cr-Zr alloy (Cr: 1%, Cu 99%) with an outer diameter of 1.90 mmφ and an inner diameter of 1.33 mmφ A flanged pipe with a flange 5 brazed thereto is inserted into the guide hole 3 (hole diameter 1.90 mmφ) of the contact chip base 1 similar to that made in Example 1.
A ceramic contact tip for arc welding was manufactured by forcibly inserting the tip into the guide hole with a punch and bringing it into close contact with the inner surface of the guide hole. A welding test similar to that in Example 1 was conducted on the arc welding contact chip manufactured by this process, and the results are shown in Table 4.

【table】

〔effect〕

As explained in detail above, the present invention changes the conventional concept that the base of a contact tip for arc welding should be made of a good electrical conductor such as a copper alloy, and instead consists of a base of a contact tip made of ceramic. Furthermore, TiC, TiN, or Ti, which has extremely high hardness and low reactivity with spatter, is added to the surface.
We have developed a new type of ceramic contact chip for arc welding in which the inner wall of the wire hole is coated with (C+N) and a good electrical conductor as a power supply material, and a method for manufacturing the same. By using a contact tip, it is possible to simultaneously solve the problems of spatter adhesion, wear, and reuse, which were problems when using conventional arc welding contact tips. It can be said that the effects of its use in the arc welding industry are extremely large.

[Brief explanation of the drawing]

Figure 1 shows a ceramic contact chip for arc welding in which a good electrical conductor is formed in the wire guide hole, and Figure 2 shows a ceramic contact chip for arc welding in which a coating layer of a good electrical conductor is formed on the inner wall of the guide hole in the base of the ceramic contact chip, and TiC is coated on the surface of the base. , TiN or Ti
(C+N) coating, FIGS. 3 to 5 are diagrams showing a pipe of good electrical conductor being inserted into a guide hole, and FIG. 6 is a diagram showing a manufacturing flow sheet for a base body of a ceramic contact chip for arc welding. DESCRIPTION OF SYMBOLS 1... Ceramic contact chip base for arc welding, 2... Guide hole, 3... Good electrical conductor coating layer, 4... Good electrical conductor pipe, 5... Flange,
6...TiC, TiN or Ti (C+N) coating layer, 7
...Screw part.

Claims (1)

[Claims] 1. A ceramic contact chip base having a coating layer of TiC, TiN or Ti (C+N), and a good electrical conductor coating layer provided on the inner wall of the wire guide hole of the contact chip base. Ceramic contact tip for arc welding. 2 The ceramic contact chip substrate has a thermal conductivity of 0.03 cal/cm・sec・℃ or more and a thermal expansion coefficient of 7.3×
The ceramic contact tip for arc welding according to claim 1, characterized in that it is made of ceramic having physical properties of 10 ^-6 1/°C or less and a bending strength of 2500 Kg/cm ² or more. 3. The ceramic contact chip for arc welding according to claim 1 or 2, wherein the ceramic base is selected from 92% Al ₂ O ₃ , SiC-based and Si ₃ N ₄ -based ceramics. . 4. According to any one of claims 1 to 3, wherein the electrically conductive coating layer is made of a copper alloy, a nickel alloy, a Ti alloy, a gold alloy, or a platinum alloy. Ceramic contact tip for arc welding. 5. A method for producing a ceramic contact chip for arc welding, comprising a ceramic contact chip base having a coating layer of TiC, TiN or Ti (C+N), and a good electrical conductor coating layer provided on the inner wall of the wire guide hole of the contact chip base. , onto the surface of the ceramic contact chip substrate prepared in advance by CVD, PVD, or plasma spraying.
After forming a coating layer of TiC, TiN or Ti (C+N), the inner wall of the wire guide of the ceramic contact chip base is coated with an electrical conductor, and then a good electrical conductor is plated using the coating layer of the electrical conductor as an electrode. A method for manufacturing ceramic contact chips for arc welding. 6. A method for manufacturing a ceramic contact chip for arc welding, comprising a ceramic contact chip base having a coating layer of TiC, TiN or Ti (C+N), and a good electrical conductor coating layer provided on the inner wall of the wire guide hole of the contact chip base. , onto the surface of the ceramic contact chip substrate prepared in advance by CVD, PVD, or plasma spraying.
A ceramic contact chip for arc welding characterized in that after forming a coating layer of TiC, TiN or Ti (C+N), a pipe of good electrical conductivity having an outer diameter approximately the same as the wire guide hole diameter of the ceramic contact chip base is inserted. manufacturing method.