JP2563843B2 - Instant joining method for nickel / titanium alloy moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for instantaneous joining of nickel / titanium based alloy moldings, and more specifically, to nickel / titanium based shape memory alloys and superelastic alloys that are difficult to join. The present invention relates to a new method in which a molding material can be locally instantly and firmly integrated with a nickel-based alloy material, and the applications of nickel-titanium shape memory alloys and superelastic alloy materials can be greatly expanded. Is.

[Conventional technology and technical problems to be solved]

As is well known, nickel-titanium type shape memory alloy is Nitinol (product name of Navy Weapons Research Institute: Nitino
As represented by l), the reversibility of deformation / restoration due to the temperature history of a given shape is extremely excellent, so that it is used in the medical field (eg, orthodontic wires, orthopedic bone connecting parts). , Clips for aneurysm surgery, etc.) and various component materials (for example, automatic air-conditioning devices for air conditioners, automatic window opening / closing devices for greenhouses, constant temperature chambers, antennas for spacecraft, etc.) In addition, nickel-titanium-based superelastic alloys are chemically stable and lightweight, and as a material for parts that require lightweightness and high springiness in mechanical devices,
There are expectations for its use.

However, these nickel / titanium-based shape memory alloys and superelastic alloys have poor metal bondability, and when such nickel / titanium-based alloy materials are bonded with a small bonding area, rivets, set screws, etc. A method of mechanically connecting with a fastener or plating a metal material that is easily bonded to the surface of the nickel-titanium alloy material and brazing through the plated metal has been adopted. . However, in addition to the former fastening method using rivets and set screws, joining the parts is very troublesome and inefficient.
There is a drawback that the joint parts rotate around the rivet shaft or the set screw shaft, and there is a drawback that the joint area cannot be made smaller than the thickness of the rivet shaft or the screw shaft. Further, in the latter brazing method using pretreatment plating, the joining strength depends on the adhesive force of the plating layer, and therefore, there is a drawback that the brazing method peels off from the plating layer when a too strong external force is applied.

The present invention has been made in view of the above-described drawbacks in the conventional technique for joining a nickel / titanium-based shape memory alloy or a superelastic alloy to dissimilar metals. It is a technical subject to provide a new method capable of joining very strongly to dissimilar metals.

Further, another technical problem of the present invention is that the nickel-titanium alloy molding material can be locally and instantaneously joined, and the portion other than the joining portion can be efficiently joined with almost no influence of the joining heat. It is an object of the present invention to provide a method for instantaneous joining of nickel-titanium alloy moldings that can be joined.

Further, another technical problem of the present invention is a high-precision joining method for a nickel / titanium-based alloy molding material, which has markedly superior joining strength as compared with the prior art, although the joining area can be extremely reduced. To provide.

[Means adopted for solving the problem]

The present inventor has paid attention to the fact that many of the other metal materials to which titanium / nickel-based shape memory alloys and superelastic alloys are to be joined are nickel-based alloys, and this common nickel component is fused by some method. If possible, we obtained the conviction that both metal materials would be strongly metallurgically bonded, and various experiments were conducted to verify this.
However, shape memory alloys and superelastic alloys, once subjected to a high temperature above a predetermined level, deteriorate the shape memory function and superelasticity function and hinder the achievement of the intended purpose. Experiments have shown that it is not allowed to heat up to near the melting point of nickel as it is generated and becomes brittle. In this way, the technical conditions for melting the nickel components of both metals and fusing the molten nickel components together without impairing the properties of the nickel-titanium shape memory alloy or superelastic alloy and joining the two metals. I was forced to repeat trial and error experiments in search of. And by accidental consequences, even in the case of nickel-titanium-based shape memory alloys and similar super-elastic alloys, if large thermal energy can be locally concentrated within a rapid and minute time, the heating zone It was possible to find out the fact that is limited to a narrow range and the metal properties of other parts are hardly affected.

Therefore, further proceeding, the present inventor stops the temperature rising portion of the metal in a narrow range limited to the joining target portion, instantaneously rapidly heats it to temporarily soften the heat, and When the two metal materials were pressed against each other at a high pressure at the moment of the softening treatment, they found a new fact that the two metals were strongly joined together.

Thus, the present inventor, when joining a predetermined local portion of a molding material made of a nickel-titanium alloy to a nickel-based alloy material, surrounds a portion of the two materials in an inert atmosphere in the vicinity of the joining target portion with a metal material. While increasing the heat dissipation by doing, while strongly pressing the parts to be joined,
Momentarily raise the temperature to near the melting temperature of nickel to temporarily heat-soften it, and at the moment when it is in this heat-softening state, the pressure acting on the joining target site causes local contact between both materials. By causing plastic flow and radiating the generated heat through the heat-dissipating metal material portion, a forged structure is formed at the contact portion of the both metal materials without adversely affecting the characteristics of the nickel-titanium alloy material. We have completed a method for instantaneous joining of nickel-titanium based alloy moldings that can be produced and metallurgically joined together.

〔Example〕

Hereinafter, specific examples of the present invention will be described with reference to Examples.
This will be described in more detail.

Example Titanium-nickel superelastic alloy (composition: Ni50-51%, T
i 49-50%, unavoidable impurities 0.5% or less) wire rod (φ1.4:
7cm in length, nickel-chromium alloy material (Ni80%, Cr1
Join the ends to a wire rod (φ2: length 10 cm) with 3% unavoidable impurities remaining).

First, high-frequency heating is performed in the vicinity of the joining target portion (end portion in this embodiment) in the wire of the above superelastic alloy to partially anneal, and then the oxidation adhered to the end of the wire to be joined. Remove impurities such as objects and fats and oils and keep them clean. Similarly, the nickel-chromium alloy wire is also cleaned by removing impurities such as oxides and oils on the surfaces of the parts to be joined.

Next, the super elastic alloy wire and the nickel-chromium alloy wire are arranged so that the parts to be joined (contact area: 2 mm ² ) are in contact with each other and fixed with a jig, and the parts are 20 kg / m 2.
While pressing with m ² pressure, chrome copper was wrapped around the part close to the part as a heat dissipation member, and in an inert gas (argon gas) atmosphere, a voltage of 3 V and a current (1,000 A) of 3 cycles of 0.05 were applied. When it was flowed for a second, both of the parts to be joined momentarily became incandescent and became a flexible state, and fused by pressure to be joined and integrated. By the way, the heat generation temperature of the joining target part at this time was 1300-1450 ℃.

Example Titanium-nickel-based shape memory alloy (composition: Ni40-60
%, Ti60-40%, Cu3%, unavoidable impurities 0.5% or less) wire rod (φ1.4: length 7 cm) and nickel-copper alloy material = monel
Metal (Ni63% or more, Cu21% or more) wire rod (φ2: Length 10
cm) was changed to 1,500 A only in the current value as in the case of the above-mentioned example, and the other conditions were the same, and as a result, an extremely strong joining effect was obtained.

The outline of the method of the present invention is generally as shown in the above Examples and, but the present invention is by no means limited to the above Examples, and various process additions or It is possible to delete it. For example, in the above-mentioned Examples and Examples, the nickel-titanium alloy molded material was partially annealed by high-frequency heating, but this was taken into consideration because of breakage due to pressure in the subsequent joining process. It is unnecessary as long as it can withstand the shape or size, and it is also possible to swell the parts to be joined of both metal materials to be joined into a bulge to promote heat concentration. In any case, it should be said to belong to the technical scope of the present invention.

〔Strength test〕

 The following tests were conducted on the samples of the above respective examples.

(1) Bending test 90 times before and after centering around the sample and the joint part of the sample
The sample was bent repeatedly in a reciprocating manner 240 times at a speed of 30 times per minute in an angle range of 180 ° each (total 180 °). It did not occur, and no elastic deterioration occurred.

(2) Tensile strength test When the tensile strength of the sample and the joint part of the sample was measured by a tensile tester (Shimadzu Corporation: AGS-A type), the following results were obtained. The test was carried out by sandwiching the sample and both ends of the sample with clamps of a tester and pulling the sample up and down around the joint.

i. Regarding the sample, when the tensile load reached 82.7 kgf, the sample was broken at the superelastic metal wire. This strength is practically effective and sufficient.

ii. Regarding the sample, when the tensile load reached 55.1 kgf, the nickel-copper alloy (monel metal) wire rod fractured. This strength is also practically effective and sufficient.

[Effect of the present invention]

As described in the above examples, according to the method of the present invention, the nickel component contained in the nickel-titanium alloy molding material and the nickel component contained in the nickel-base alloy material are heated at high pressure under a state of being heat-softened. Since pressing causes local plastic flow and presses the fresh layer surfaces against each other, both metal materials are metallurgically metalized with a thin fused layer based on a common nickel component being formed at the press contacting site. As a result of the fusion and integration, it has become possible to bond nickel-titanium alloy molding materials, which were previously believed to be difficult to bond, very strongly, even to dissimilar nickel-base alloy materials.

Further, in the present invention, although the nickel-titanium alloy molding material and the nickel-based alloy material are heated up to near the melting temperature of nickel, the temperature rising portion is limited to the local joining target portion At the moment of joining, the heat is radiated from the relevant part and the temperature is immediately lowered, so the heat-up time of the relevant part is extremely small, and therefore the nickel-titanium alloy having delicate and unique physical and chemical properties. (Shape memory alloys and superelastic alloys) are also metallurgically instantly joined without time to cause a chemical reaction.
Therefore, it is possible to perform the joining process very efficiently with almost no effect of the joining heat on the portions other than the joining portion.

Further, according to the present invention, a molding material composed of a nickel-titanium type shape memory alloy or a superelastic alloy, which has been conventionally considered difficult to bond to a dissimilar metal, is quickly and firmly bonded to a dissimilar alloy based on nickel. It becomes possible and the joint area can be made extremely small. Therefore, the applications of nickel-titanium type shape memory alloys and superelastic alloys can be greatly expanded to the fields of daily life ranging from industrial / military use to clothing, clothing and housing.

As described above, the present invention can dramatically expand the field of use of nickel-titanium alloy materials, which have been unavoidably limited in their applications because the joining technology has become a bottleneck, and their industrial utility value. Can be said to be extremely expensive.

Claims (3)

(57) [Claims] 1. Ni content is 60-40%, Ti content is 40-60%.
A method of joining a predetermined part of a molding material made of the nickel-titanium shape memory alloy or nickel-titanium superelastic alloy to a nickel-base alloy material, which is located in the inert atmosphere in the vicinity of the joining target portion of both materials. While enlarging the heat-dissipating property by enclosing the formed part with a metal material, while strongly pressing the parts to be joined, the temperature is temporarily raised to near the melting temperature of nickel to temporarily soften the heat. By causing a local plastic flow in both material contact portions by the pressure acting on the joining target portion at the moment of being in a heat-softened state, by radiating the generated heat through the metal material portion, A method for instantaneous joining of nickel-titanium based alloy moldings, characterized by forming a forged structure at a contact portion of the both metal materials and metallurgically joining and integrating the both metal materials. 2. The other nickel-base alloy material to which a molding material made of a nickel-titanium shape memory alloy or a nickel-titanium superelastic alloy is to be joined is a Ni-Cu alloy or a Ni-Cu alloy.
The instantaneous joining method for a nickel-titanium alloy molded material according to claim 1, which is a Mo alloy, a Ni-Cr alloy, or a Ni-Cr-Fe alloy. 3. A part to be joined of a molding material made of a nickel / titanium type shape memory alloy or a nickel / titanium type superelastic alloy is partially annealed in advance in advance. The method for instantaneous joining of nickel-titanium alloy moldings as described.