JPH03188230A - Elastic member essentially consisting of intermetallic compound and its manufacture - Google Patents

Abstract

PURPOSE:To easily manufacture an elastic member by an intermetallic compound by mixing plural elements in a compositional ratio to form an intermetallic compound, subjecting the mixture to swaging into a mixed press- adhered body having the shape of a bar, a wire or a plate, thereafter forming it into the shape of the elastic member and executing heating. CONSTITUTION:For example, Al powder and Ti powder are mixed so that a compositional ratio to form an intermetallic compound such as TiAl, Ti3Al or the like will be regulated, which is satisfactorily mixed and pulverized by a dry ball mill or the like. The mixed powder of Ti and Al is subjected to swaging by a rotary swaging machine and is worked into the shape of a bar. Swaging is furthermore executed to reduce the bar-shaped body into a bar- shaped mixed press-adhered body which is tightly adhered and having few pores on the surface layer, which is formed into a desired spring shape. The spring-shaped formed body is charged to a heating apparatus and is heated to a temp. at which an intermetallic compound of Al and Ti is formed, so that a spring-shaped member by an intermetallic compound such as TiAl, Ti3Al or the like can easily be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an elastic member such as a spring mainly composed of an intermetallic compound, and a method for manufacturing the same.

[Prior Art] The raw materials for conventional springs or elastic members that exhibit spring-like properties are generally metals such as steel or FRP.
It was a non-metal such as. However, recently, attention has been focused on intermetallic compounds that are lightweight and have excellent properties such as heat resistance and oxidation resistance. Examples of intermetallic compounds include TiAl, T1
3 Al, A13 Tl, N13 Al, and old Ti having a shape memory effect are known.

There are examples of coil spring manufacturing using bending for Ti-formed Ti, but although Ti-formed has good formability among intermetallic compounds, the actual forming process requires multiple heat treatments (softening annealing). It is much more difficult to form springs than metals. Furthermore, it has been thought that it is difficult to apply other intermetallic compounds to springs that require large bending processes, such as coil springs.

It has also been considered to perform molding in advance at the material stage before forming the intermetallic compound. For example, JP-A-61
As seen in Japanese Patent Publication No. 270353, an intermetallic compound having a desired shape is obtained by hot-pressing the raw material of the intermetallic compound and then firing it, and as seen in Japanese Patent Application Laid-open No. 70531/1983. It has been proposed that the intermetallic compound raw material be degassed and then processed under predetermined molding pressure and temperature conditions.

[Problem to be solved by the invention] Even if preforming is performed before forming the intermetallic compound as in the prior art described above, it is impossible to apply it to springs that require large plastic working such as coil springs. Met. This is because the three-dimensional object made from the raw material of the intermetallic compound is less uniform in the state before forming the intermetallic compound than a normal metal shrine, and may contain many pores and defects. This is because deformation tends to be uneven when plastic working such as tensioning is performed, resulting in extremely poor working performance.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an elastic member and a method for manufacturing the same, which can produce an elastic member of a desired shape mainly made of an intermetallic compound without any problems.

[Means for Solving the Problems] The present invention, developed to achieve the above object, reduces the cross-sectional area by swaging a raw material containing a plurality of elements mixed in a composition ratio that forms a metal stage compound. is reduced to obtain a rod-shaped, linear or plate-shaped mixed crimped body, and this mixed crimped body is formed into a desired elastic member shape, and then treated under temperature conditions that will form an intermetallic compound. It is something.

Examples of elastic members include coil springs, leaf springs, torsion bars, washers that exhibit spring-like properties, fastening members, and the like. The substances that make up the intermetallic compound are
It is sufficient that at least one element is a metal.

The raw material needs to be mainly composed of a metal material, but may partially contain an intermetallic compound. Further, appropriate elements or compounds may be added for the purpose of improving various properties as an elastic member or facilitating molding. The raw material does not need to be a pure metal lump, and may be a solid solution or a composite made by plating or the like. The form of the raw materials before mixing is powder.

They are flakes, wires, foils, etc.

When the raw materials are in the form of powder or flakes, the raw materials are mixed using, for example, a V-type mixer, a ball mill, a mixer, or the like.

If the raw material is linear, the wires may be bundled or twisted together, for example. In the case of foil-shaped raw materials, for example, the foils are rolled up one on top of the other.

The mixed raw materials are packed into a suitable enveloping member such as metal or synthetic resin, and forged using a swaging machine until a predetermined working degree is reached. In this specification, the degree of processing refers to the ratio of the cross-sectional area of the mixed material before processing to the cross-sectional area of the mixed pressed body after processing.

In addition, since a strong mixture can be obtained by twisting the wires together when the raw material is in the form of a wire, or by winding the wires together when the raw material is in the form of a foil, the above-mentioned wrapping member is not necessarily required. In order to increase the strength of these mixtures, the mixture may be preliminarily compressed by drawing the mixture into a wire if the raw material is in the form of a wire, or by rolling the mixture if the raw material is in the form of a foil. good.

Similarly, when the raw material is in the form of powder or flakes, the mixture may be preliminarily compressed by isostatic pressing, -axial pressing, extrusion, swaging, rolling, etc. in order to improve the strength of the mixture. In such a case, it is not necessarily necessary to provide a covering member in which mixed raw materials are filled in advance before forging to a predetermined working degree using the swaging machine.

[Function] In order to reduce the pores in the mixed raw materials and press the raw materials together as firmly as possible, it is preferable to add as much deformation as possible to the mixed raw materials. From this point of view, it is easy for the swaging machine to have a large degree of processing, which meets the purpose of the present invention.

Moreover, since the swaging process has the effect of sufficiently crushing the mixed raw materials when the cross-sectional area is reduced, the contact area of the mixed raw materials can be increased, and good pressing force (sealing force) can be obtained.

This leads to improved processing performance when molding into a desired elastic member shape.

Furthermore, since the structure is refined, a high-strength intermetallic compound spring can be obtained. When the mixed raw material that has undergone swaging processing is fed into the die of the swaging machine, the cross-sectional area is gradually reduced from one end to the other, and deaeration is promoted, and at the same time, the pores are sufficiently crushed. It will be done.

The degree of processing by the swaging machine is determined depending on the shape, size, filling rate, etc. of the mixed raw materials.

As a guideline for the degree of processing, it is preferable to process until the porosity of the mixed pressed body after reducing the cross-sectional area becomes 5% or less in terms of volume fraction.

As the degree of processing increases, the degree of rubbing and crushing of the mixed raw materials increases, which improves adhesion and increases the contact area, improving processing performance when forming into a spring shape.

Note that even if the porosity is the same, the presence of large pores will reduce processing performance, so the distribution of pore diameters is also an important factor for processing performance in addition to porosity. Therefore, it is necessary to evaluate the pore diameter in addition to the porosity.
There is a positive correlation that the higher the degree of processing, the more the pores collapse and the lower the porosity, and the smaller the pore diameter, so even if the degree of processing is determined based on the porosity, which is easy to manage, it is not practical in practice. no problem.

Swaging processing reduces the cross-sectional area of the material in the longitudinal direction while strongly hammering the surface of the material with a die, and is particularly effective in crushing pores in the surface layer. That is, the porosity of the surface layer tends to be smaller than that of the center, and when a porosity of 5% or less is obtained, almost no pores exist in the surface layer. Conversely, if the degree of processing is such that the porosity exceeds 5%, the collapse and adhesion of the mixed raw materials will be insufficient, and not only will the porosity be high, but large pores will also be present, which is undesirable.

The swaging process may be performed cold, but it may also be performed warmly by heating the process by an appropriate method in order to reduce the deformation resistance during processing and enhance the above effects. In the case of warm forming, it is preferable that the temperature is below the temperature at which intermetallic compounds are formed, but if the processing is completed in a short enough time to form intermetallic compounds in a part of the structure, intermetallic compounds will not be formed. The molding may be performed at a warm temperature higher than the temperature.

The rod-shaped (linear) mixed crimped body obtained by the swaging process is molded into a desired shape such as a coil spring. It is then heated to a temperature at which intermetallic compounds are formed. This heat treatment causes diffusion or self-combustion sintering and the formation of intermetallic compounds. The heating temperature is in the temperature range below the solidus line of the intermetallic compound. To complete the formation of intermetallic compounds, it is necessary to maintain the above temperature for a certain period of time. The lower the temperature, the longer it takes. Further, in order to further reduce the number of pores, the material may be heated to a temperature higher than the temperature at which an intermetallic compound is formed while the material is kept under pressure.

After the intermetallic compound is formed, a post-formation heat treatment may be performed as necessary. By performing this heat treatment, the number of pores can be further reduced, the uniformity of the structure can be promoted, and impurities can be diffused or removed. The treatment temperature is in the temperature range below the solidus line of the intermetallic compound. Although this heat treatment may be performed in the air, more preferable results may be obtained if it is performed in an inert gas or vacuum atmosphere. Furthermore, these atmospheres may be combined. Depending on the material, this heat treatment may be performed under pressure using an appropriate pressure means.

[Example] An example of the present invention will be described below with reference to the drawings. An example of the manufacturing process shown in FIG. 1 includes a raw material mixing process 1, a manufacturing process 2 of the mixed and pressed body using a swaging machine, a pre-forming heat treatment process 3 performed as necessary, and Pre-processing step 4 such as irregular cross-section processing,
It consists of a forming step 5 in which it is formed into a desired spring shape, a heat treatment step 6 in which it is heated to a temperature for forming an intermetallic compound, a heat treatment step 7 after the compound is formed, and a finishing step 8, which are carried out as necessary.

In the raw material mixing step 1, A1 powder of 350 mesh or less produced by gas atomization method and sponge Ti powder of 350 mesh or less were mixed in weight fraction T i :
A 1-37.17: So that the ratio is 82.83,
Mixing is performed using a dry ball mill purged with Ar gas.

Next, in step 2 of manufacturing a mixed press-bonded body, the mixed powder is used as an example of a covering member having an outer diameter of φ20 arffl.

It is packed in a stainless steel pipe with an inner diameter of 19 gm and a wall thickness of 0.5 a+g, and then subjected to a first swaging process using, for example, the rotary swaging machine 9 shown in FIG. 2 to reduce the outer diameter to 8II11. After that, the pipe is scraped off by cutting, and a rod-shaped mixed crimped body A is formed.
get. Note that the material of the pipe may be other than stainless steel or may be other than metal. In short, any material that can withstand swaging processing is sufficient.

Note that, if the raw material is in the form of a wire, a strong mixture can be obtained by twisting the wires together, or if the raw material is in the form of a foil, by winding them in layers, so the metal pipe described above is not necessarily required. In order to increase the strength of these mixtures, the mixture may be compressed by drawing the mixture into a wire if the raw material is in the form of a wire, or by rolling the mixture if the raw material is in the form of a foil.

Similarly, when the raw material is in the form of powder or flakes, the strength of the mixture is improved by compressing it by isostatic pressing, -axial pressing, extrusion, swaging, rolling, etc., so such pre-compression is recommended. When applying,
A pipe filled with mixed raw materials is not necessarily required when the cross-sectional area is reduced by the rotary squaring machine.

An example of the structure of the rotary swaging machine 9 is that a split die pair is provided inside a group of rollers arranged in the circumferential direction, and this die pair is rotated at high speed by a spindle. It has a structure in which the outer end is hammered by a group of rollers, causing the material to be plastically deformed and reduced in diameter, similar to forging.

After performing the first swaging process, the mixed crimped body A is reduced in diameter to an outer diameter of φ1■ by a second swaging process. The porosity was 1% or less.

Microscopic photographs of the metal structure of the mixed crimped body A subjected to the series of swaging processes described above are shown in Figs. M5 to Fig. 10. Figure 5 (400x magnification) and Figure 6 (100x magnification)
0 times) are the structures when the cross-sectional area is reduced from an outer diameter of 19 mm to 18 II m. Processing degree is 1
．． It is 1. In this photo, what looks white is AI,
The gray color is Ti1, and the pores appear black.

Figure 7 (400x magnification) and Figure 8 (1000x magnification) show the metal structure when the cross-sectional area is reduced to an outer diameter of φ4txtx.
times). The porosity is approximately 2%. The processing degree is 22.6.

Furthermore, the metal structure reduced to an outer diameter of φ1■ is shown in FIG. 9 (magnification: 400 times) and FIG. 10 (magnification: 1000 times).

It can be seen that the porosity is approximately 1% or less, and the gray Ti particles are fine. The processing degree is 361.

By performing the above-mentioned swaging process, the porosity is significantly reduced, and there are almost no pores, especially in the surface layer, and the raw materials are sufficiently crushed to form a strong adhesion state. Among these, conventional processing methods (extrusion,
Whereas the mixed crimped body produced by rolling, drawing, etc.) did not have sufficient adhesion and contained many defects such as pores, by applying the swaging process of this example, it was possible to It is now possible to provide excellent workability that cannot be seen in other materials. In other words, it has become possible to easily manufacture intermetallic compound springs that have been subjected to large plastic working, which was previously thought to be difficult to manufacture, and it has also become possible to apply the present invention to coil springs and the like.

The mixed crimped body A obtained in the crimping process 2 may be subjected to a heat treatment process 3 before molding. This step 3 is, for example, annealing carried out in a roaring atmosphere, and is effective in removing processing distortion that occurs when manufacturing the mixed crimped body A, and reduces deformation resistance during forming in forming step 5, which will be described later. can be done.

Moreover, the crimping surface of the mixed crimped body A becomes strong due to the diffusion, and the strength can be improved.

It also has the effect of removing impurity components from the mixed press-bonded body. This step 3 is performed in air, inert gas, vacuum atmosphere, or a combination of these atmospheres. The processing temperature is generally below the temperature at which intermetallic compounds are formed, but if the heating is short enough to form an intermetallic compound on a part of the bonded surface, it may be above the temperature at which an intermetallic compound is formed. It doesn't matter. This heat treatment may be performed before the swaging process, during the swaging process, before preprocessing, or before spring forming. Pre-processing process 4
In this case, it is also possible to form the mixed pressed body A by forging 1 machining or the like to obtain a desired cross-sectional shape.

In forming step 5 for imparting a desired spring shape,
- For example, coiling of the mixed press-bonded body A is performed using a forming apparatus 10 as shown in FIG.

This device 10 includes a core metal 11, a roller 13, a chuck 14, and the like. The roller 13 has the function of pressing the mixed pressure-bonded body A against the core metal 11 and bending it, and applying a predetermined compressive force P.

- As an example, in FIG. 3, a spiral groove 15 is provided on the outer periphery of the core bar 11 in accordance with the pitch and curvature of the coil spring molded body A' to be molded.

Above pre-processing step 4. The molding step 5 may be performed cold, but may also be performed warm in order to reduce the deformation resistance during molding. In the case of warm forming, it is preferable that the temperature is below the temperature at which intermetallic compounds are formed, but if forming is completed in a short time that forms intermetallic compounds in a part of the structure, intermetallic compounds will not be formed. The molding may be performed at a warm temperature higher than the temperature.

In a heat treatment step 6, the coiled molded body A' obtained in the above-mentioned forming step 5 is placed in a heating device 20 illustrated in FIG. 4 and heated to a temperature at which an intermetallic compound is formed. This heating device 20 includes a pressure-resistant stainless steel bot 22 filled with silica sand 21, and a Kanthal heater 23 which is a coil-shaped resistance heating element built into the bot 22.
, a thermocouple 24 for temperature detection, and a stainless steel lid 2
5, and a pressurizing means 26 such as a hydraulic cylinder for pressurizing the M2S.

A coil-shaped molded body A' is set inside the heater 23 housed in the pot 22, and the coil-shaped molded body A' is
A pseudo-isotropic pressure of 0 kg1'/am2 is applied.

Then, it is heated to 700° C. by the heater 23.

At this time, the temperature of the coiled compact A' is measured by a thermal lightning pair 24. When the coiled compact A' was heated to the above temperature, heat generation due to the formation of intermetallic compounds due to self-combustion sintering was observed. Note that the pressure may be applied using gas, powder, or liquid, or may be applied mechanically, such as HIP\)HP.

After the intermetallic compound is formed, the molded body A' is held at 90θ°C while the above pressure is maintained, and heat treatment step 7 is performed for 2 hours. By performing this heat treatment step 7, the pores contained in the molded body A' can be further reduced, the uniformity of the structure can be promoted, and impurities can be diffused or removed.

Through the above series of steps, a coil spring mainly composed of an intermetallic compound having a wire diameter of 1■■, a coil average diameter of 12a+m, and a number of turns of 10 was obtained. The results of X-ray analysis revealed that this coil spring was made of an intermetallic compound of Ali T1. This coil spring completely maintains its original shape even after being compressed for 5 inches at 700°C and then unloaded.
It was confirmed that it exhibited good spring action.

Note that the coil spring obtained through the above manufacturing process may be subjected to finishing process 8. For example, the spring surface is made smooth by barrel processing. Alternatively, the spring surface may be polished by mechanical processing, or the shape may be modified by removing surface scratches 1, such as the surface layer, or by cutting, grinding, or the like.

Further, by performing shot peening to generate compressive residual stress in the surface layer of the spring, the durability of the spring can be further improved.

[Effects of the Invention] According to the present invention, it is possible to easily and accurately form an elastic member mainly made of an intermetallic compound into a desired shape, which was previously thought to be difficult or impossible to manufacture. This makes it easier to apply to spring shapes that require large plastic working, such as coil springs.

[Brief explanation of drawings]

Fig. 1 is a process explanatory diagram showing one embodiment of the method of the present invention;
The figure is a perspective view showing an example of a swaging machine, Figure 3 is a perspective view of a device for coiling mixed crimped bodies, Figure 4 is a sectional view of a heating device, and Figure 5 is an outer diameter of φ19mm to φ18I.
A photograph of the metal structure of a mixed crimped body whose cross-sectional area has been reduced to Im, magnified 400 times with a microscope. Figure 6 is a photograph of the same metal structure as in Figure 5, magnified 1000 times with a microscope. Figure 7 is a photograph of φ4 mm. Figure 8 is a photo of the same metal structure as in Figure 7, magnified 1000 times using a microscope. Figure 9 is φll1ll.
Figure 10 shows the same metal structure as Figure 9, magnified 400 times under a microscope.
This is a photograph enlarged 000 times. A: Mixed pressed body, A': Molded body, 9: Swaging machine, 10: Molding device, 20: Heating device.

Claims (3)

[Claims] (1) A mixed crimped body is obtained by swaging a raw material containing multiple elements mixed in a composition ratio that forms an intermetallic compound, and the mixed crimped body is molded into a desired shape to form an intermetallic compound. An elastic member mainly composed of an intermetallic compound, characterized in that the material is treated under temperature conditions that cause the formation of an intermetallic compound. (2) Fill a covering member with raw materials containing multiple elements mixed in a composition ratio that forms an intermetallic compound, perform a swaging process to obtain a mixed pressed body, and shape this mixed pressed body into a desired shape. 1. A method for producing an elastic member mainly composed of an intermetallic compound, the method comprising forming the elastic member and then treating the elastic member under temperature conditions that allow the formation of an intermetallic compound. (3) Manufacturing an elastic member mainly composed of an intermetallic compound according to claim 2, wherein the cross-sectional area of the pressed mixed body is reduced by the swaging process until the porosity of the pressed mixed body becomes 5% or less. Method.