JPS61266189A - Ceramic contact tip for arc welding and its production - Google Patents

Abstract

PURPOSE:To prevent the sticking of spatters, etc. by constituting a contact tip base body of ceramics, forming the part for feeding power to a wire of a good electrical conductor and providing a coating layer consisting of TiC, etc. on the surface of the contact tip. CONSTITUTION:The contact tip body 1 is constituted oft the ceramics having the characteristics including >=0.02cal/cm.sec. deg.C heat conductivity, <=7.3X10<-6>/ deg.C coefft. of thermal expansion and >=2,500kg/cm<2> bending strength. The coating layer 3 consisting of the good electrical conductor is formed of a copper alloy or Ni alloy and the coating layer 6 consisting of TiC, TiN or Ti(C+N) is formed on the surface of the body 1. The coating layer 6 is formed of the material having extremely high hardness and low reactivity with the spatters and therefore the sticking of the spatters is prevented. Since the body 1 is made of the ceramics, the life is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a ceramic contact tip used in arc welding that has low spatter adhesion, a long life, and is reusable, and a method for manufacturing the same.

[Prior Art] Conventional contact tips for arc welding are mainly made of copper alloy or aluminum alloy, but since the surface of the contact tip is metal, spatter scattered during arc welding can be caused by thermochemical reactions, etc. The contact tips for arc welding may be damaged due to the fact that they accumulate on the surface of the contact tip and cause clogging, and the contact tip is annealed and softened by the radiated heat during welding, accelerating the wear of the tip of the contact tip due to the wire passing through. Its lifespan was extremely short.

As a method to solve the above-mentioned problems,
A method of protecting the nozzle part of a contact tip with a ceramic guide as described in Japanese Utility Model Application No. 26630, Japanese Utility Model Application Publication No. 59-49478, or Japanese Utility Model Application Publication No. 57-8248, or Japanese Utility Model Application Publication No. 50-76021 A method of coating a contact chip with ceramic has been proposed as described in Japanese Utility Model Application Publication No. 57-160887 KE.

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 scattered over a wide area. there were.

On the other hand, the method of coating the contact tip with ceramic is
This solves the problems of complicating the structure and protecting the entire chip from sputter adhesion, and the inventors also believe that PVD
We developed a ceramic coating method for contact chips using the CVD method or the CVD method, and filed an application as Utility Model Application No. 59-163202.

However, even in the above-mentioned ceramic-coated contact tip, since the base body itself is made of metal, especially copper alloy or aluminum alloy, wear resistance deteriorates due to annealing softening in the ceramic coating and annealing softening due to radiated heat during arc welding. There was a natural limit to its lifespan. Furthermore, once the nozzle becomes unusable due to clogging or wear, 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 921 AzlO as a solution to the above-mentioned problem.

He invented and previously filed an application for an arc welding contact tip made of ceramic such as SiC or Si 3 N 4 and having the inner wall of the wire guide hole coated with a good electrical conductor.

This invention solved the problem of wear and reuse of the nozzle part due to annealing softening, and significantly extended the life of the contact tip.However, regarding spatter adhesion during welding, it is significantly larger than that of metal contact tips. Although this has been greatly reduced, the problem of sputter adhesion still remains as the ceramic is somewhat reactive with sputtering mainly containing Fe.

[Problems to be Solved by the Invention] The present invention provides a ceramic contact tip for arc welding that simultaneously solves the problem of clogging due to spatter adhesion and the problem of wear resistance as described above, and can be repeatedly regenerated, and its contact. The purpose is to provide a manufacturing method that allows chips to be manufactured stably and reliably.

[Means for solving problems]

The present invention is based on extensive research into means for solving the above-mentioned problems.
As a result, we changed the standard concept that arc welding contact tips are made of metal, which is a good electrical conductor, and instead made the arc welding contact tip base 1 shown in Fig. 1 out of ceramic, and only the part that supplies power to the wire was made of ceramic. Good electrical conductor 3
In addition to the above-mentioned invention of the prior application by the present inventors, as shown in FIG. Tic, TiN or Ti(C+N
) was completed based on the knowledge that the above-mentioned objective could be achieved by providing the coating layer 6.

Further, 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 liters.
+, 03. SiC type or 813N, etc. conductivity 0
．． 03 cab / Gll -813 (! @ 'Q
As described above, it is made of ceramic having physical properties of a thermal expansion coefficient of 7.3'XIO1/'C or less and a bending strength of 2500 Ky/ct1 or more, and the surface K of the base 1
PVT) method, CVD method, plasma spraying method, etc.
Sputtering mainly composed of e and TiC with low reactivity,
A coating layer 6 of TiN or Ti (C+N) is formed, and the inner wall K 111 of the wire guide hole 2 of the base body is made of copper alloy, N
By forming a coating layer of electrically conductive materials such as alloys, gold alloys, silver alloys, platinum alloys, and titanium alloys, arc welding can be used repeatedly with very little spatter during welding and without problems with wear. Ceramic contact chips for use in this process were obtained.

As a method for stably manufacturing the above-mentioned clay ceramic contact tip for arc welding, Tie
, TjN or Ti (C+N) using CVD method, PVD method V uses plasma method 1 (while forming coating layer 6,
Wire guide hole 2 of the ceramic contact chip base
A method of coating the inner wall of the substrate with a good electrical conductor, and then electroplating a good electrical conductor 3 using the coating layer made of the good electrical conductor as an electrode, and as shown in FIG. A method has been developed in which a pipe 4 of a good electrical conductor with a diameter approximately the same as that of the wire guide hole 2 is prepared in advance, and the pipe 4 is inserted into the guide hole 21L of the ceramic contact chip base 1.

As a method of electroplating a good electrical conductor on the inner wall of the guide hole of the ceramic contact tip described above, any known method of 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 plated with

(a) By CVD or PVD, T, which is an electrical conductor, is
After coating the inner wall of the guide hole with iC or TiN, etc., the coated electrically conductive layer of TiC or TiN is used as an electrode to conduct a process such as a Cu alloy, a Ni alloy, a silver thread alloy, a gold thread alloy, a platinum alloy, or a Ti alloy. How to electroplate a good electrical conductor.

(b) After coating the inner wall of the guide hole with metal powder in paste form or by gluing it, apply N2, /H.
A method in which an electrically conductive layer is formed on the inner wall of the guide hole by the so-called metallization method in which firing is performed in a vacuum or in a vacuum, and then a good electrical conductor is electroplated in the same manner as in (a). In this metallization method 1, a fine metal powder can be used, but if the substrate is an oxide ceramic such as A6.0°, Ni or M can be used.

, Cu, rllto-Mn, Ni, MO if the substrate is SiC-based, and M if the substrate is Si3N4-based.

Particularly good results are obtained with the combination of

(c) A method in which the inner wall of the guide hole is coated with an electrical conductor in advance by electroless plating, 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, it is preferable to use Ni or Cu.
Delicious.

Incidentally, the coating with the electrically conductive material may extend up to the threaded portion 7 in order to improve the power feeding effect.

[Effect]

In the present invention, the contact tip base for arc welding is made of ceramic with high hardness and excellent heat resistance, so compared to conventional metal contact tips, there is no problem of annealing softening during welding, and it is wear resistant. The quality is extremely good. In addition, in the present invention, the surface of the ceramic contact chip is coated with TiC, TiN, or T, which has extremely high hardness and has low reactivity with sputtering containing Fe as a main component.
Since the i(C+N) is coated, spatter does not adhere during welding.

Even if -d ivy adheres, 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 friction caused by the wire passing through and becomes unable to supply power to the wire, the contact tip base will not be damaged. The contact tip base body can be used repeatedly by recoating it with a good electrical conductor without becoming unusable.

As the material for the contact tip substrate 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 cannot be avoided. As a result of repeated research and experiments, we found that 921A/, 01. SiC and 81. N4
Thermal conductivity such as 0.03Ca'/Cnl''S
eC*Te゛ or more, thermal expansion coefficient 7.3X10'14■:J
It has been found that by selecting a ceramic with physical properties such as lower bending strength of 2500 Kg/611 or more, it is possible to obtain an extremely long-life arc welding contact tip that does not crack even after repeated use over a long period of time. did.

That is, in arc welding, the contact tip is repeatedly subjected to local heating and rapid heating, and when considering the mechanism by which cracks occur in the contact tip due to the thermal shock, the following can be said.

A ceramic contact tip may crack during arc welding if 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 portion and its vicinity.

That is, the temperature of the welded portion is around 1200°C, and the temperature of the contact tip is 200 to 300°C due to radiated heat from the welding part and self-arc heat during power supply. In a contact chip having 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 internal stress. Therefore, in order to prevent cracking due to thermal shock during arc welding, that is, to prevent the internal stress caused by the difference in thermal expansion of each part from exceeding the bending strength, it is necessary to select a material with high thermal conductivity. By reducing the temperature gradient in each part, by selecting a material with a small coefficient of thermal expansion, the amount of thermal expansion in each part is reduced and the absolute value of the difference in the amount of thermal expansion is reduced, and by selecting a material with high bending strength. It is possible to select .

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 was 0.03ca//(fn*
see * ℃ or higher, thermal expansion coefficient is 7.3 x 10
When a contact tip base for arc welding is made of ceramic material that has the physical properties of -'1/℃ and bending strength of 2500Kf/C-, it has the effect that no cracks occur even during long-term repeated arc welding. That's what I got.

Table 1 The radiated heat inside the contact chip 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 effects of the method for manufacturing the ceramic contact tip 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 sputtered particles, is formed on the surface of the ceramic contact chip substrate 1. As a means, CV
Any method such as D method, PVD method, or plasma spraying method can be adopted, but when CVD method or PVD method is adopted, the coating layer is thin, about several micrometers, but the surface roughness is high, and even if it is as it is, the surface The advantage is that there is less spatter adhesion due to the spatter trapping phenomenon caused by the unevenness of the coating.On the other hand, when plasma spraying is used, the coating layer can be made thicker than 100μ, but the surface roughness of the coating layer is rough. It is necessary to polish to a degree of 20S or less, preferably 0.5 to 288 degrees.

By the way, the relationship between the surface roughness of a ceramic contact chip and the surface roughness when each coating method is adopted is shown below.
It will look like Table 2.

Table 2 In the second invention, the electrically conductive coating that will eventually become the power supply material is formed by efficient electroplating, but as a pretreatment, the inner wall of the guide hole and, if necessary, the threaded part are coated with the coating. Although it is treated to coat the electrical conductor,
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 it is necessary to compare the electrodes in advance.

In addition, the areas 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 contact tip base made of seven lamics. The advantage of this method is that it does not require a complicated plating process as in the second invention, and it is a relatively simple process of manufacturing the pipe by machining and fitting the pipe into the guide hole of the ceramic contact chip base. The following points can be mentioned: the pipe can be manufactured using the same method, and the worn pipe can be easily removed and replaced with a new pipe during recycling. - Another major advantage of this manufacturing method is that the pipe can be assembled into the ceramic contactor/tip base in a work-hardened or heat-hardened state, which reduces pipe wear during arc welding. This is something that can be done.

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, and then cast molding, press molding, or in-die extrusion molding is used. Since it is disadvantageous from a cost perspective to process the threaded part of the base by raw machining, etc., it is disadvantageous in terms of cost. The molding method is @6
It is advantageous to employ injection molding as shown in the flow sheet of the figure.

<Example> (a) Manufacturing of ceramic contact chip substrate 92'
16 hiffio, an organic binder was added to the powder in the composition ratio shown below, and as shown in Fig. 4, the mixture was heated and kneaded and granulated using a mouth to obtain molding material granules, and the molding material was injected under the following molding conditions. This method was used to form the contact tip substrate for arc welding.

The contact tip base for arc welding of the above-mentioned form was subjected to a lubricant treatment under the following conditions, and then fired to produce a contact tip base for arc welding.

Degreasing conditions - (room temperature) ~80℃ 3Hrs80~360℃
5℃/Hr j6o℃ 2Hrs retention ↓ Cooling firing conditions (air) - (Room temperature 1-1550℃ 7Hrs1
550℃]) Hold fr ↓ Allow to cool (b) Ti on the ceramic contact chip substrate surface
c. Formation of a TiN or Ti(C+N) coating layer: The surface of the seven ramic contact chip substrate made of 92% kltos prepared in the above process was coated by CVD method, P
TiC by vI) method and plasma spraying method.

A coating 1- of TiN and Ti (C+N) was formed.

(c) Coating the inner wall of the wire guide hole of the lamic contact chip base with a good electrical conductor. On the outer surface of the ceramic contact chip on which the above-mentioned 'piC, TiN or Tl (C+N) coating layer has been formed, a masking layer 7 is applied to the inner wall of the wire guide hole. After electrolessly plating Ni on only the tank, the Ni electroless plating layer is used as a cathode,
Electroplated under the following conditions, 0.1-0.3 m
A Cu coating layer with a thickness of m was formed on the inner wall of the wire guide (20)' hole.

Bath Composition Plating Conditions) Welding Test The arc welding contact tips prepared in the above steps were subjected to welding tests under conditions similar to actual arc welding described below, and the results are shown in Table 3.

However, the lifespan of a Cu contact chip is the time until clogging occurs due to sputter adhesion.Example 2 (a) Production of ceramic contact chip substrate St, N
4. Mix an organic binder with the following composition ratio to the powder of 4.
As shown in the figure, a molding material was obtained by heating kneading and heating extrusion granulation, and the molding material was molded into the shape of a contact tip base for arc welding by an injection method under the following conditions. Force 850Ky/crl Temperature
220° C. Mold temperature: 25° C. Injection time: 5 sec Cooling time: 5 sec The produced contact tip base for arc welding was degreased and fired under conditions of fertilization.

Degreasing conditions □ RT ~80℃ 3Hrs80
℃ 〜550℃ 5℃/Hr 550℃ 1211rs held ↓ Cooling firing conditions (under N2 pressure) RT 〜800℃ 3
Hrs800℃～1500℃2Hrs 1500℃～1800℃6Hrs 1800℃ Hold for 2Hrs ↓ Cooling (b) Ti on the surface of the seven ramic contact chip substrate
c. Formation of TiN and Ti(C'+N) coating layers.
TiC, by VD method, PVD method and plasma spraying method.
A coating layer of TiN and Ti (C+N) was formed.

(c) Insertion of electrically conductive pipe into wire guide hole of ceramic contact chip base Cu-Cr-Zr alloy (Cr: 1%, Cu 99%)
A pipe with an outer diameter of 1.90 + nrnφ and an inner diameter of 1.3, with an inner diameter of 1 and 3, was prepared using a ladle with a guide hole 3 (hole diameter 1.90 mmφ) of the contact tip base 1 similar to that made in Example 1.
) was forcibly inserted into the guide hole with a punch so that it was brought into close contact with the inner surface of the guide hole, thereby manufacturing a clay lamic contact tip for arc welding.

The same welding test as in Example 1 was conducted on the arc welding contact tip manufactured by this process, and the results are shown in Table 4.

In the above examples, the ceramic contact chip substrates are made of 92'A At203 and 813N4, respectively, but even if SiC is selected as the material for the ceramic contact chip substrates, the same performance as in Examples 1 and 2 can be obtained. It has been confirmed that a contact tip for arc welding can be obtained.

〔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 the contact tip made of ceramic. Furthermore, 'I' has extremely high hardness and low reactivity with sputtering on its surface.
We have developed a new type of ceramic contact tip for arc welding, in which the inner wall of the wire hole is coated with iC, TiN, or Ti (C+N) and a good electrical conductor as a power supply material, and a method for manufacturing the same, and moreover, the present invention has the above-mentioned structure. By using ceramic contact tips for arc welding, it is possible to simultaneously solve the problems of spatter adhesion, wear, and recycling and reuse, which were problems when using conventional arc welding contact tips. Therefore, it can be said that the application effect of the present invention in the arc welding industry field is extremely large.

[Brief explanation of the drawing]

Figure 1 is a diagram in which a good electrical conductor is formed in the wire guide hole of a ceramic contact tip for arc welding, and Figure 2 is a diagram in which a coating layer of a good electrical conductor is formed on the inner wall of the guide hole in the base of a ceramic contact tip for arc welding, and a coating layer of a good electrical conductor is formed on the surface of the base. Figures 3 to 5 show a diagram showing a case where a pipe with good electrical conductivity is inserted into a guide hole, and Figure 6 shows a manufacturing flow sheet for a base body of a ceramic contact tip for arc welding. It is a diagram.

Claims (6)

[Claims] (1) 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. Ceramic contact tip. (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.
．． 3×10^-^61/℃ or less and bending strength 2500
The ceramic contact tip for arc welding according to claim 1, characterized in that it is made of ceramic having physical properties of Kg/cm^3 or more. (3) The ceramic substrate is 92% Al_2O_3, S
Claim 1 or 2, characterized in that the ceramic is selected from iC-based and Si_3N_4-based ceramics.
Ceramic contact tip for arc welding as described in . (4) 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 as described in . (5) Manufacture of a ceramic contact tip for arc welding consisting of a ceramic contact tip 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 tip base. In the method, TiC, TiN, or Ti (C+N) is applied to the surface of a ceramic contact chip substrate prepared in advance by CVD, PVD, or plasma spraying.
After forming a coating layer, the inner wall of the wire guide of the ceramic contact chip base is coated with an electrical conductor, and then the coating layer of the electrical conductor is used as an electrode to plate a good electrical conductor. manufacturing method. (6) Manufacture of a ceramic contact tip for arc welding consisting of a ceramic contact tip 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 tip base. In the method, TiC, TiN, or Ti (C+N) is applied to the surface of a ceramic contact chip substrate prepared in advance by CVD, PVD, or plasma spraying.
1. A method for producing a ceramic contact tip for arc welding, which comprises: forming a coating layer, and then inserting a pipe of good electrical conductivity having an outer diameter approximately the same as the wire guide hole diameter of the ceramic contact tip base.