JPH0711015B2 - Method for manufacturing elastic member mainly composed of intermetallic compound - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an elastic member such as a spring mainly composed of an intermetallic compound and a method for manufacturing the elastic member.

[Prior Art] Conventional springs or raw materials of elastic members exhibiting properties similar to springs are generally metals such as steel or non-metals such as FRP. However, recently, attention has been paid to an intermetallic compound which is lightweight and has excellent properties such as heat resistance and oxidation resistance. As an example of the intermetallic compound, TiAl, Ti ₃ , Al, Al
Known are ₃ , ₃ , Ti, Ni ₃ , Al and TiNi having a shape memory effect. There is an example of coil spring manufacturing by bending in TiNi, but although TiNi has the better formability among intermetallic compounds, multiple heat treatments (softening annealing) are required for actual forming Therefore, it is far more difficult to form a spring than metal. Further, it was considered difficult to put the spring into practical use in other intermetallic compounds.

Further, it is also considered to perform molding in advance before forming the intermetallic compound. For example, as disclosed in JP-A-61-270353, those in which an intermetallic compound having a desired shape is obtained by hot-pressing a raw material of an intermetallic compound and then firing it, and JP-A-62-70531. As can be seen in the publication, it is proposed that the raw material of the intermetallic compound is degassed and then treated under predetermined molding pressure and temperature conditions.

[Problems to be Solved by the Invention] Even if preforming is performed before forming an intermetallic compound as in the above-mentioned prior art, it is not possible to obtain a product such as a coil spring that requires bending with large deformation. It was possible.
The reason is that the three-dimensional object made of the raw material of the intermetallic compound is poor in uniformity in the state before the formation of the intermetallic compound as compared with a normal metal material, and may include many vacancies and defects. This is because the deformation tends to be non-uniform, and the plastic deformation due to the large bending process cannot withstand the elongation.

Therefore, it is an object of the present invention to provide a manufacturing method capable of manufacturing an elastic member mainly composed of an intermetallic compound and having a desired shape without any problem.

[Means for Solving the Problems] The method of the present invention, which has been developed to achieve the above object, comprises a step of obtaining a raw material containing a plurality of elements mixed in a composition ratio for forming an intermetallic compound, and A step of obtaining a mixed pressure-bonded body by applying a pressing force; a step of locally pressing the mixed pressure-bonded body by sandwiching the mixed pressure-bonded body with an inner mold and an outer mold, and pressing the outer mold with one end side of the mixed pressure-bonded body. From the other end side while relatively moving along the inner mold to plastically deform the mixed pressure-bonded body in the pressing portion, to obtain a molded body having a desired shape, and the molded body. And a treatment step under a temperature condition in which an intermetallic compound is formed.

Examples of the elastic member are, for example, a coil spring, a leaf spring, a torsion bar, or a member exhibiting properties similar to a spring. As for the substance forming the intermetallic compound, at least one element may be a metal.

The raw material needs to be mainly composed of a metal material, but may partially include an intermetallic compound. Further, an appropriate element or compound may be added for the purpose of improving various properties as a spring or the purpose of facilitating molding. The above raw material need not be a lump of pure metal,
It may be a solid solution or a composite formed by plating or the like. The form of the raw material before mixing is powder,
They are flakes, wire rods, foils, etc.

As for the mixing method and the crimping method, when the raw material is in the form of powder or flakes, the mixture is extruded by a V-type mixer, a ball mill, a mixer or the like, or is crimped by a hot press or CIP. Alternatively, the mixed raw materials may be packed in a metal pipe and forged by a swaging machine to a predetermined outer diameter.

In the case of a linear raw material, the raw material wires may be bundled or twisted together, and then the wires may be pressed together using a wire drawing machine or the like. In the case of a foil-shaped raw material, the foils may be laminated in the thickness direction or rolled in a state of being laminated and then pressure-bonded by rolling.

The mixed crimped body obtained by the above process has a considerably nonuniform structure as compared with a normal metal material, and may have many defects and holes therein. Local progress. Therefore, it is difficult to bend it with a predetermined curvature.

Therefore, in the present invention, the mixed pressure-bonded body is locally pressed by a mold made of, for example, a core metal and rollers, and the mixed pressure-bonded body is gradually bent while relatively moving the pressing portion along the mold. By doing so, a molded product having a desired shape is obtained.

[Operation] Since the mixed pressure-bonded body is molded as described above, the deformation zone of the mixed pressure-bonded body can be sufficiently shortened, and moreover, most of the deformation zone can be bent in a restrained state, so that the deformation zone cracks. It is possible to mold the mixed pressure-bonded body into a desired shape without causing problems such as progress of deformation and uneven deformation. Further, since a compressive force is applied to the mixed pressure-bonded body by the mold simultaneously with bending, there is also an effect of crushing the holes existing in the mixed pressure-bonded body.

The forming process may be performed cold, but the forming process may be performed warm to reduce the deformation resistance during forming.
In the case of warm forming, it is preferable that the temperature is not higher than the temperature at which the intermetallic compound is formed, but if the forming is completed in a short time such that the intermetallic compound is formed in a part of the structure, the intermetallic compound is formed. Molding may be performed at a temperature higher than the temperature.

A pre-molding heat treatment may be performed before carrying out the molding step. This treatment is, for example, annealing performed in vacuum. By performing the pre-molding heat treatment, the processing strain generated when the mixed pressure-bonded body is manufactured is removed. In addition, the deformation resistance at the time of molding is reduced, and the pressure-bonded surface of the mixed pressure-bonded body is strengthened by diffusion, so that the strength can be improved. The pre-molding heat treatment also has the effect of diffusing or removing the impurity components of the mixed pressure-bonded body. The pre-molding heat treatment is performed in the air, an inert gas, a vacuum atmosphere, or a combination of these atmospheres. The treatment temperature is generally lower than the temperature at which the intermetallic compound is formed, but if the heating is for a short time to the extent that the intermetallic compound is formed on a part of the pressure-bonded surface, it is higher than or equal to the temperature at which the intermetallic compound is formed. I don't care.

The molded body that has been plastically processed into the desired shape through the molding step is heated to a temperature at which an intermetallic compound is formed. This heat treatment causes diffusion or self-combustion sintering to form an intermetallic compound. The heating temperature is in the temperature range below the solidus of the intermetallic compound. The above temperature must be maintained for a certain period of time to finish the formation of the intermetallic compound. It takes a long time when the temperature is low. Further, in order to reduce the number of voids, the molded body may be heated to a temperature at which the intermetallic compound is formed or higher while being pressurized.

After the intermetallic compound is formed, heat treatment may be performed after the compound formation, if necessary. By performing this heat treatment, it is possible to reduce vacancies, promote homogenization of the structure, and further diffuse impurities or remove impurities. The treatment temperature is in the temperature range below the solidus line of the intermetallic compound. This heat treatment (heat treatment after formation of the intermetallic compound) may be performed in the air, but more preferable results may be obtained if it is performed in an inert gas or vacuum atmosphere. Also, these atmospheres may be combined. Depending on the material, this heat treatment may be carried out under pressure with an appropriate pressure means.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. An example of the manufacturing process shown in FIG.
Raw material mixing step 1, mixed pressure-bonded body manufacturing step 2, pre-molding heat treatment step 3 performed as necessary, and molding step 4
And a heat treatment step 5 of heating to the formation temperature of the intermetallic compound
And a heat treatment step 6 and a finishing step 7 which are carried out as necessary after the compound formation.

In the raw material mixing step 1, the Al powder of 350 mesh or less produced by the gas atomizing method and the sponge Ti powder of 350 mesh or less were replaced with Ar gas at a weight ratio of Ti: Al = 37.2%: 62.8%. Mix using a dry ball mill.

Next, in the manufacturing step 2 of the mixed crimp body, the mixed powder is packed in a stainless steel pipe having an outer diameter of 20 mm and a wall thickness of 0.5 mm,
Reduce diameter to 8mm by rotary aging machine. Then, the pipe is scraped off by cutting. In this way, the linear mixed crimped body (in this case, green compact)
Is obtained. After performing the first swaging process, the mixed pressure-bonded body is reduced in diameter to an outer diameter φ1 mm by a second swaging process. In addition, you may make it remove the processing strain at the time of manufacturing a mixed pressure bonding body by implementing the heat treatment process 3 of annealing etc. after the said process 2.

In the molding step 4, the mixed pressure-bonded body A is coiled using the molding apparatus 10 shown in FIG. The device 10 is configured to include a cored bar 11 as an example of an inner die, a head 12, a roller 13 as an example of an outer side, a chuck 14, and the like. The cored bar 11 and the head 12 can be brought into contact with and separated from each other in the axial direction, and are integrally rotated in the same direction and at the same rotational speed by a drive mechanism (not shown). The roller 13 has a function of pressing the mixed pressure-bonded body A against the cored bar 11 to gradually bend it and a predetermined compression force P.

A coil spring molded body 1A ′ to be molded is formed on the outer peripheral portion of the cored bar 11.
The spiral groove 15 corresponding to the pitch is provided. The roller 16 facing the spiral groove 15 is also provided with a groove 16. A desired cross-sectional shape is formed in the width direction of these grooves 15 and 16. For example, in FIG.
Is a circular cross section, and the cross-sectional shapes of the grooves 15 and 16 are substantially semicircular. The grooves 15 and 16 can be omitted.

Since the roller 13 is rotatably provided, the frictional force between the mixed pressure-bonded body A and the roller 13 can be reduced. In addition, it is possible to suppress problems such as excessive deformation and damage when the mixed pressure-bonded body A is bent. Further, the force required to rotate the cored bar 11 while bending the mixed pressure-bonded body A can be reduced.

In order to coil the mixed pressure-bonded body A using the above-mentioned molding apparatus 10, the chuck is performed with the core metal 11 and the head 12 stopped.
14 holds the end of the mixed pressure-bonded body A. Then, the mixed pressure-bonded body A is pressed against the groove 15 of the cored bar 11 by the roller 13.

Rotate the core metal 11 and the head 12 as a unit to rotate the roller 13 and the core metal 11
While pressing the mixed pressure-bonded body A locally between and,
At a, the mixed pressure-bonded body A is bent along the core metal 11. Further, the roller 13 is moved in the axial direction of the cored bar 11 in accordance with the pitch of the spiral groove 15 to guide the mixed pressure-bonded body A so that the mixed pressure-bonded body A is wound around the spiral groove 15.

After the coiling is completed, the roller 13 is separated from the core metal 11 and the chuck 14 releases the restraint of the compact A ′. Then, the head 12 is separated from the core metal 11 and the molded body A'is
The outer peripheral portion is held by a holder (not shown), and the cored bar 11 is rotated in the opposite direction to that at the time of coiling, whereby the coil-shaped molded body A'is removed from the cored bar 11.

Coil-shaped molded body A'obtained by the molding step 4
Is the heating device shown in FIG. 3 in the heat treatment step 5.
It is placed in 20 and heated to a temperature at which an intermetallic compound is formed. The heating device 20 includes a pot 22 made of pressure-resistant stainless steel filled with silica sand 21, a cantal heater 23 which is a coil-shaped resistance heating element built in the pot 22, a thermocouple 24 for temperature detection, and a stainless steel. It is configured by including a lid 25 made of metal and a pressurizing means 26 such as a hydraulic cylinder for pressurizing the lid 25.

Inside the heater 23 housed in the pot 22, the coil-shaped molded body A'is set, and 150 kgf / cm ^{2 is applied} by the pressing means 26.
Pseudo isotropic pressure is applied. And 700 ℃ by heater 23
Heat up to. At this time, the temperature of the coil-shaped molded body A'is measured by the thermocouple 24. When the coil-shaped compact A ′ was heated to the above temperature, heat generation due to self-combustion sintering to form an intermetallic compound was observed. In addition, by using HIP, HP, etc., pressurizing using gas, powder or liquid,
Alternatively, the pressure may be mechanically applied.

After the intermetallic compound is formed, the compact A ′ is kept at 900 ° C. while maintaining the above pressure, and the heat treatment step 6 for 2 hours is performed.
I do. By carrying out this heat treatment step 6, it is possible to reduce the pores contained in the molded body A ′, promote the homogenization of the structure, and further diffuse the impurities or remove the impurities.

Wire diameter 1mm, coil average diameter 12m
A coil spring mainly composed of an intermetallic compound having m and 10 turns was obtained. This coil spring shows that Al ₃ Ti
It was found to consist of the intermetallic compound of It was confirmed that this coil spring maintains its original shape completely even after unloading after being subjected to a compressive deformation of 5 mm at 700 ° C., and that it exhibits a good spring action.

The coil spring obtained through the above manufacturing process may be subjected to the finishing process 7. For example, barrel processing makes the spring surface smooth. Alternatively, the spring surface is polished by machining, or the shape is modified by removing or cutting surface scratches or surface layers, or by grinding. Further, the durability of the spring can be further enhanced by performing the shot peening to generate the residual compression capacity in the surface layer of the spring.

The mixed pressure-bonded body A may be plastically worked into a desired shape by using a molding apparatus 30 as shown in FIG. The molding device 30 includes a fixed roller 31 as an example of an inner mold,
A movable roller 33 as an example of an outer die attached to the holder 32, a chuck 34 for holding the mixed pressure-bonded body A, and the like are provided. The movable roller 33 is configured to be rotatable about a shaft 35 and revolve around the fixed roller 31 about the shaft 35. One end side of the mixed pressure-bonded body A is constrained by the fixed roller 31 by the chuck 34, and the movable roller 33 rolls in the direction of the arrow F in the figure, so that the mixed pressure-bonded body A is locally located between the fixed roller 31 and the movable roller 33. Is pressed by. And by being bent in the pressing portion 31a,
Molding is performed with a curvature according to the outer diameter of the fixed roller 31.

A movable roller, such as the molding device 40 shown in FIG.
The movable roller 33 is rolled in the outer peripheral direction of the fixed die 31 in a state in which the pressing force in the direction of the arrow P ₁ shown in the figure is applied to the mixed pressure-bonded body A by the 33, so as to form the curvature according to the outer peripheral shape of the fixed die 31. You may do it.

The molding apparatus 50 shown in FIG. 6 includes a fixed die 51 and a pressing member 52. The fixed die 51 in the illustrated example includes a non-circular molding surface 53 having a curvature corresponding to the shape of the molding A ′ to be molded. The pressing member 52 functions to press the mixed pressure-bonded body A against the fixed mold 51. The pressing member 52 has a molding surface 53.
When the mixed pressure-bonded body A is pressed against, the contact point with respect to the mixed pressure-bonded body A moves along the molding surface 53.
The manufacturing method of the present invention is not limited to the method shown in the above-mentioned embodiment, and can be applied to other compositions other than Ti-Al system. The same applies to systems that form other intermetallic compounds.

The present invention can be similarly applied to the case of manufacturing an elastic body other than the coil spring.

[Effect of the Invention] According to the present invention, in the method for manufacturing an elastic member mainly composed of an intermetallic compound, the deformation region of the mixed pressure-bonded body is sufficiently increased in the step of molding the mixed pressure-bonded body which is the material of the elastic member into a desired shape. Since it can be shortened and it can be bent while most of the deformation area is constrained, a mixed crimped body is desired without causing problems such as cracking in the deformation area or uneven deformation. Can be molded to a curvature of. In addition, since the compressing force is locally applied to the mixed pressure-bonded body by the inner mold and the outer mold at the same time as bending, there is also an effect of crushing the holes existing in the mixed pressure-bonded body to a smaller size. For this reason, bending work with large deformation such as a coil spring can be performed without any problem, and an elastic member mainly composed of an intermetallic compound, which has not been available in the past, can be obtained.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing one embodiment of the method of the present invention, and FIG.
FIG. 3 is a perspective view of an apparatus for forming a mixed crimp body, FIG. 3 is a cross-sectional view of a heating apparatus, and FIGS. 4 to 6 are schematic views showing other examples of apparatuses for forming a mixed crimp body. . A: mixed crimped body, A '... molded body, 10 ... molding device,
11 ...... core metal (mold), 13 ... roller (mold), 20 ... heating device, 23 ... heater, 26 ... pressurizing means, 30 ... molding device,
31 …… Roller (type), 33 …… Roller (type), 40,50 ……
Molding equipment, 51 ... Mold, 52 ... Holding member.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-99425 (JP, A) JP-A-3-188230 (JP, A)

Claims (2)

[Claims] 1. A step of obtaining a raw material containing a plurality of elements mixed in a composition ratio for forming an intermetallic compound, and a step of obtaining a mixed pressure-bonded body by applying a pressure to the raw materials.
While pressing the mixed pressure-bonded body between the inner mold and the outer mold and locally pressing the mixed pressure-bonded body, the outer mold is moved along the inner mold from one end side to the other end side of the mixed pressure-bonded body at the pressing portion. A step of plastically deforming the mixed pressure-bonded body in the pressing portion while relatively moving, to obtain a molded body having a desired shape; and a step of treating the molded body under a temperature condition in which an intermetallic compound is formed. A method for manufacturing an elastic member mainly composed of an intermetallic compound, comprising: 2. A mold used for molding the mixed pressure-bonded body comprises a core metal as the inner mold and a pressing member as the outer mold. The pressing member and the core metal. 2. The mixed pressure-bonded body is bent along the core by moving the pressing member relatively in the circumferential direction of the core while locally pressing the mixed pressure-bonded body between the pressure-bonded body and the core. A method for producing an elastic member mainly composed of the intermetallic compound described above.