JPH03264174A - Instantaneous joining method of nickel/titanium alloy molding material - Google Patents

Abstract

PURPOSE:To metallurgically join and integrate the parts to be joined of both materials at an extreme speed by instantaneously heating up the parts to be joined near to the melting temp. of nickel in an inert gaseous atmosphere and pressing and joining the parts to be joined to each other by a high pressure. CONSTITUTION:The end part of a wire consisting of a titanium/nickel superelastic alloy is joined to the end part of a wire consisting of a nickel/ chromium alloy material. The part near the part to be joined of the superelastic alloy wire is subjected to high frequency heating and is partially annealed. The impurities, such as oxides, sticking to the end part to be joined are then removed. The parts to be joined are so fixed by jigs as to come into contact with each other and while these parts are kept pressed by a prescribed pressure, chromium copper is wound as a heat radiating member in the part proximate to these parts, a current is passed thereto in the inert gaseous atmosphere. Both of the parts to be joined are instantaneously heated white to a resilient state and are fused by the pressure, by which the parts to be joined are joined and integrated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an instant bonding method for forming nickel-titanium alloy materials, and more specifically, a method for instantly bonding nickel-titanium-based shape memory alloys and superelastic alloys, which are difficult to bond. This relates to a new method that can locally and firmly instant-bond and integrate a powerful forming material into a nickel-based alloy material, greatly expanding the applications of nickel-titanium-based shape memory alloys and superelastic alloy materials. is possible.

[Prior art and technical issues to be solved] As is well known, the nickel-titanium based shape memory alloy is Nitinol (product name of the U.S. Naval Ordnance Research Institute: N<f, 4noL).
), the reversibility of deformation and restoration due to the temperature history of a given shape is extremely excellent.
In the medical field (e.g., orthodontic wire, orthopedic bone connection parts, arterial layer surgery clips, etc.) and the field of various parts and materials (e.g., automatic air blowing angle adjustment devices for air conditioners, greenhouses, constant temperature rooms, etc.) Efforts are being made to develop applications for automatic window opening/closing devices, spacecraft antennas, etc.), and nickel-titanium-based superelastic alloys are also being used in mechanical devices because they are chemically stable and lightweight. It is expected to be used as a material for parts that require light weight and high elasticity.

However, these nickel-titanium-based shape memory alloys and superelastic alloys have poor metallurgical bonding properties, and when joining such nickel-titanium alloy materials with a small joint area, it is necessary to use rivets, set screws, etc. The methods used were to connect them mechanically using fasteners, or to plate the surface of the nickel-titanium alloy material with a metal material that is easy to bond to, and to braze through the plated metal. .

However, the former method of fastening using rivets and set screws is extremely troublesome and inefficient to join parts, and has the disadvantage that the joined parts rotate around the rivet shaft and set screw pongee. Moreover, there was a drawback that the joint area could not be made smaller than the thickness of the rivet shaft or screw shaft.

In addition, in the latter brazing method using pre-treatment plating,
Since the bonding strength depends on the adhesion force of the plating layer, there is a drawback that it will peel off from the plating layer if too strong external force is applied to it.

The present invention was made in view of the above-mentioned difficulties in the conventional technology for joining nickel-titanium-based shape memory alloys and superelastic alloys to dissimilar metals.
The technical objective is to provide a new method that can extremely firmly bond titanium-based alloy formed materials to dissimilar metals.

In addition, another technical problem of the present invention is that nickel-titanium alloy formed materials can be locally instantaneously joined, and moreover, it is possible to efficiently join nickel-titanium alloy molded materials with almost no effect of joining heat on parts other than the joining site. An object of the present invention is to provide an instant joining method for nickel-titanium alloy formed materials that can be joined.

Furthermore, another technical object of the present invention is to achieve high-precision joining of nickel-titanium alloy molded materials, which has significantly superior joining strength compared to conventional techniques, even though the joining area can be made extremely small. We are here to provide you with a method.

[Means adopted to solve the problem]

The present inventor focused on the fact that most of the metal materials to which titanium-nickel based shape memory alloys and superelastic alloys are to be joined are nickel-based alloys, and sought to fuse these common nickel components in some way. If it is possible,
We were confident that these two metal materials would bond strongly metallurgically, and conducted various experiments to verify this. However, when shape memory alloys and superelastic alloys are exposed to high temperatures above a certain level, their shape memory function and superelasticity deteriorate, making it difficult to achieve the intended purpose.Moreover, the formation of intermetallic compounds in the joints occurs. It was discovered through experiments that it was impossible to heat the material to a temperature close to the melting point of nickel, as this caused the material to become brittle. In this way, the technical conditions for joining both metals by melting the nickel components of both metals and fusing the molten nickel components with each other without impairing the properties of nickel-titanium-based shape memory alloys and superelastic alloys. We were forced to repeat trial-and-error experiments in search of the solution. As a result of a coincidence, if a nickel-titanium shape memory alloy or a superelastic alloy of the same type can rapidly and locally concentrate a large amount of thermal energy within a minute time, then We were able to ascertain the fact that the shoulder area is limited to a narrow range and has almost no effect on the overall shoulder characteristics of other areas.

Therefore, the inventor of the present invention went further and limited the temperature-raising part of the metal to only the target part to be joined, caused that part to instantaneously and rapidly generate heat, and temporarily changed it to a thermoplastic state. By pressing the two metal materials together under high pressure for a moment while they were in a flexible state, they discovered that the two metals were indeed firmly bonded.

Thus, when joining a predetermined local part of a molded material made of a nickel-titanium alloy to a nickel-based alloy material, the present inventor instantaneously heats the part of the two materials to be joined in an inert atmosphere near the melting temperature of nickel. By employing metallurgical means of heating the parts to be joined together under high pressure in a thermally flexible state by raising the temperature to a temperature of They achieved a method for instantly joining nickel-titanium alloy molded materials, and succeeded in solving the technical problems mentioned above.

〔Example〕

Hereinafter, the specific contents of the present invention will be explained in more detail by giving examples.

Example ■ Titanium-nickel superelastic alloy (composition: Ni50-51
%, Ti 49-50%, unavoidable impurities o, s%
(below) A wire rod (φ1.4: length 7cm) is joined at its ends to a wire rod (φ2: length 10an) made of a nickel-chromium alloy material (Ni 80%, Cr 13L residual unavoidable impurities).

First, high-frequency heating is applied to the vicinity of the part of the wire of the superelastic alloy to be joined (in this example, the end) to partially anneal it, and then the oxidation that has adhered to the end of the wire to be joined is Keep it clean by removing impurities such as dirt, oil, etc. Similarly, the nickel-chromium alloy wire is cleaned by removing impurities such as oxides and oil from the surface of the parts to be joined.

Next, the superelastic alloy wire rod and the nickel-chromium alloy wire rod are arranged so that the parts to be joined (contact area: 2 mm) are in contact with each other and fixed with a jig, and the parts are
While pressing with a pressure of 1.5 kg/mm'', a chrome film was wrapped around the part close to the area as a heat dissipation member, and in an inert gas (argon gas) atmosphere, 3 cycles of current (1, 0OOA') was flowed for 0.05 seconds, both of the parts to be welded instantaneously became incandescent, became flexible, and were fused under pressure to become a joined body.Incidentally, the heat generation temperature of the parts to be welded at this time was 13
The temperature was 00-1450°C.

Example ■ Titanium-nickel shape memory alloy (composition: Ni40-8
0%, Ti 60-40%, Cu 3%, unavoidable impurities 0.5% or less) wire rod (φ1.4 = length 70) and nickel-copper alloy material = moneL metaLcNi 6
3% or more, Cu 2111 or more) wire rod (φ2: length 10 cm) was bonded with the current value changed to 1,500 A from the case of Example ① above, and the other conditions were the same. A strong bonding effect was obtained.

Although the outline of the method of the present invention is generally as shown in the above embodiments and (2), the present invention is by no means limited to the above-mentioned embodiments, and various process steps may be modified within the scope of the claims. For example, in Examples ① and ② above, the nickel-titanium alloy molded material was partially annealed by high-frequency heating, but this may cause breakage due to pressure during the subsequent joining process. It is not necessary if it can withstand the shape or size, and the parts to be joined of both metal materials to be joined are made to bulge out in a slightly protruding shape to promote heat concentration. It should be said that any of these cases falls within the technical scope of the present invention.

〔Strength test〕

The following test was conducted using the sample obtained in Example (1) and the sample (2) obtained in Example (2) above.

(1) Bending test sample ■ and sample ■ back and forth 90 degrees around the joint site
Although the bending was repeated 240 times at a rate of 30 times per minute in an angular range of No deformation occurred, and no elastic deterioration occurred.

(2) Tensile strength test The tensile strength of the bonded portion of sample ■ and sample ■ was measured using a tensile tester (Meio Shimadzu Corporation: ^as-A type), and the following results were obtained. The test was carried out by clamping both ends of sample (1) and sample (2) with the clamps of the testing machine and pulling them up and down centering on the joint.

Regarding sample (i), when the tensile load reached 82.7] arf, the superelastic metal wire broke. This strength is practically effective and sufficient.

Regarding soil and sample (2), when the tensile load reached 55.1 kg f, the nickel-copper alloy (moneL metal) wire broke.

This strength is also effective and sufficient for practical use.

C. Effects of the present invention] As explained above using the examples, according to the method of the present invention, the nickel component contained in the nickel-titanium alloy molded material and the nickel component contained in the nickel-based alloy material were softened by heating. Since they are pressed under high pressure under such conditions, the common nickel component becomes the base, and the mutual structures fuse and become metallurgically integrated, which was previously believed to be difficult to join. This makes it possible to extremely firmly bond nickel-titanium alloy molded materials to dissimilar nickel-based alloy materials.

In addition, in the present invention, although the temperature of the nickel/titanium alloy molded material and the nickel-based alloy material is raised to near the melting temperature of nickel, the temperature increase is limited to the local welding target region. Since the temperature rise occurs over a very short period of time, it has become possible to perform the bonding process efficiently at a very high speed, with almost no effect of bonding heat on areas other than the bonding site.

Furthermore, according to the present invention, it is now possible to quickly and firmly join nickel-titanium alloy molded materials, which have conventionally been considered difficult to join with dissimilar metals, even to nickel-based dissimilar alloys, while reducing the joining area. Because they can be made extremely small, it has become possible to greatly expand the uses of nickel-titanium-based shape memory alloys and superelastic alloys from industrial and military applications to everyday life, including clothing, food, and housing.

In this way, the present invention can dramatically expand the field of application of nickel-titanium alloy materials, whose applications have traditionally been unavoidably limited due to the bottleneck in bonding technology, and improve its industrial application advantages. The value can be said to be extremely high.

Claims (4)

[Claims] (1) When joining a predetermined local part of a formed material made of a nickel-titanium alloy to a nickel-based alloy material, the part to be joined of both materials is rapidly brought to a temperature close to the melting temperature of nickel in an inert atmosphere. By raising the temperature and pressing the parts to be joined together in a thermo-flexible state under high pressure,
An instant bonding method for nickel-titanium alloy formed materials, which is characterized by metallurgically joining and integrating both metal materials. (2) The nickel-titanium alloy has a Ni content of 60~
It is a shape memory alloy or a superelastic alloy with a Ti content of 40% and 40% to 60%, and the nickel-based alloy material to which it is to be joined is a Ni-Cu alloy, a Ni-Mo alloy, a N
The instant joining method for a nickel-titanium alloy molded material according to claim 1, which is an i-Cr alloy or a Ni-Cr-Fe alloy. (3) A claim in which the part of the formed material made of a nickel-titanium alloy to be joined is partially annealed in advance (
1) or (2), the instant joining method for nickel-titanium alloy molded materials. (4) A heat dissipation part is formed by covering the part of the formed material made of a nickel-titanium alloy close to the part to be welded and the part of the nickel-based alloy material close to the part to be welded with a heat conductive metal material. , any one of claims (1) to (3), wherein only the parts to be joined are heated rapidly and instantaneously to near the nickel melting temperature while suppressing overheating of parts other than the parts to be joined, thereby metallurgically joining and integrating the parts. A method for instant joining of nickel-titanium alloy molded materials as described in one of the above.