JPS6112961B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes a hot isostatic press molding method (hereinafter referred to as HIP).
With this method, irregularly shaped articles with complex shapes can be easily formed, and conventionally there were various problems.
New irregularly shaped articles that facilitate release after HIP treatment
It concerns the HIP Act.

Several proposals have already been made regarding the HIP method for irregularly shaped articles, such as hollow articles or articles with complex external shapes, and one of the representative methods is to turn the capsule itself into an irregularly shaped article using a special processing method. This method involves molding the capsule into a corresponding shape, filling the inside with raw material powder such as ceramics or metal, and performing HIP processing, but the molding of the capsule itself is extremely complicated;
Furthermore, even after the HIP treatment, there was a problem in that the mold release operation to remove the complicatedly shaped capsules was also accompanied by difficulties. Therefore, as a method to solve this problem, the applicant first placed a spacer inside a simple-shaped capsule to form a space corresponding to the shape of the irregularly shaped article, filled the inside with raw material powder, and performed HIP processing. ,
We proposed a method to remove the spacer after HIP treatment. This method makes it extremely easy to manufacture capsules, and the spacer can be easily extracted if it has a simple shape, so it is a relatively reasonable method, but if the spacer itself is required to have a complex shape. However, it is impossible to remove the spacer immediately, and therefore, its use has been limited to spacers that can have a simple shape.

The present invention relates to an improvement of the HIP method using this spacer, and aims to make it possible to easily remove the spacer regardless of its shape. When filling the raw material powder into the irregular space formed in the capsule and performing HIP processing, the material of the spacer should be selected such that at least its outer layer has a melting point higher than the HIP processing temperature and lower than the melting point of the irregular shaped article (raw material powder). After the HIP treatment, the spacer is melted and flowed out by heating at a temperature higher than the melting point of the spacer and lower than the melting point of the irregularly shaped article.

The specific contents of the present invention will be explained below.
It should be noted that the present invention is not limited to the embodiments shown in the contents exemplified below and the claims, and it goes without saying that any embodiment can be adopted without departing from the idea of the present invention. do not have.

FIG. 1 is a sectional view showing a basic embodiment of the present invention, in which a spacer 2 as a core is placed inside a capsule 1 made of a normal material such as metal or glass, and the capsule 1 and spacer 2 are The figure shows a state in which the raw material powder 3 is filled into the irregular space formed by the method and sealed by a conventional method. Here, at least the outer layer of the spacer 2 is made of a metal with a melting point higher than the HIP treatment temperature and lower than the melting point of the raw material powder 3, and the raw material powder 3 is made of iron-based material such as high speed steel, low alloy steel, or iron powder. In the case of metal powder, the spacer 2 is made of copper, copper alloy, aluminum, aluminum alloy, etc., and is formed into a predetermined shape by subjecting these materials to appropriate processing such as cutting or pressing. The object to be treated thus obtained is subjected to HIP according to the conventional method.
During the HIP process, care must be taken to prevent the spacer 2 from melting and entering between the particles of the raw powder 3 or reacting with the raw powder 3 to form an alloy layer. Set the temperature to a temperature lower than the melting point of Spacer 2, for example, if the spacer is made of copper, the melting point is 1083℃, so approximately
The temperature may be 1050°C or lower, or if the spacer is made of aluminum, the melting point is 660°C, so the temperature may be approximately 630°C or lower. Typically, the HIP processing temperature is
A temperature of about 1000 to 1100℃ is generally used, but according to research by the present inventors, a temperature of 350℃ is used for iron-based metal powder.
It has been experimentally confirmed that 99% or more densification can be achieved even at a temperature of about 100%, so there is no technical problem in lowering the HIP treatment temperature depending on the type of spacer. However, lowering the temperature may require slightly higher HIP pressure or
Because the processing time needs to be slightly longer, there may be cases where high pressure cannot be applied due to the specifications of the HIP equipment, or if the HIP
If it is desired to shorten the processing cycle, it is preferable to adopt a method suitable for shortening the processing cycle.

Furthermore, if the shape of the spacer becomes complex, forming it by cutting becomes extremely complicated work, so in such cases, it is recommended to form the spacer by a casting method that is suitable for molding complex shapes. You can also do it. In this case, it is desirable to keep the casting cost as low as possible, so a metal with a low melting point such as lead or a lead alloy is preferable, but lead and lead alloys have a melting point of about 190°C to 327°C and are used in the method described above. Since the melting point is too low, as shown in Figure 2, a material with a melting point lower than the HIP processing temperature, such as lead, is used in the outer layer 2b, which is formed into a predetermined shape with an easily processable thin plate made of a material with a melting point higher than the HIP processing temperature. The inner layer portion 2a may be cast from a metal having a melting point to form the spacer 2 with an integrated composite structure. This casting method is generally called cloth casting, and it goes without saying that after casting using this method, the sprue is sealed with the metal that forms the outer layer so that the inner layer is not exposed.

Furthermore, since the above-mentioned lead and lead alloys have extremely good formability, they are first formed into a predetermined spacer shape by mechanical processing such as pressing, and then the surface is coated with
It is also possible to make a spacer with a composite structure by coating it with a metal having a melting point higher than the HIP treatment temperature by means such as plating.

When such a spacer having a composite structure is used, there is no problem even if the low melting point metal of the inner layer portion 2a melts, so the temperature may be raised linearly to a predetermined temperature.

Although the above example is an example in which the spacer is formed from solid metal (molten material), it is also possible to form the spacer from powder. For example, it is possible to use ordinary powder forging to form a metal powder with a melting point lower than the HIP processing temperature, such as Cu powder or Al powder, into a predetermined shape to form a spacer, but in order to omit this forming process, the following method is used. method can also be adopted. That is, as shown in FIG. 3, a mold 4 made of paper or a thin synthetic resin plate into a predetermined shape is placed inside a capsule 1, the inside of the mold 4 is filled with metal powder 5 to serve as a spacer, and the outer periphery of the mold 4 is filled with raw materials. This is a method of filling powder 3. In this method, mold 4 decomposes and carbonizes during the HIP process, but this carbide layer acts to prevent the reaction between the spacer and the raw material powder.
Extremely effective. In addition, gases such as hydrogen and oxygen are generated by the decomposition of type 4, but most of these gases are absorbed into the spacer or product metal, so these gas components are contained in the product. If this is not preferable, the metal powder 5 forming the spacer may have a higher ability to absorb these gases than the raw material powder 3. That is, when the raw material powder 3 is an iron-based metal, the spacer may be formed of a material with high oxygen absorption capacity such as Al powder, or may be appropriately mixed with Al powder. In this case, an appropriate amount of Ti, which has a high absorption capacity, may be mixed into the metal powder forming the spacer.

Using the spacer configured as above, the raw material powder encapsulated in the capsule is subjected to HIP treatment and densified to more than 99% of its true density, and the capsule is removed by appropriate means such as cutting. If the spacer has the shape shown, it is impossible to extract it mechanically. Therefore, in the present invention, HIP
The spacer is melted and flowed out by heating the shaped article to a temperature below its melting point and above the melting point of the spacer. If the spacer is removed in this way, it can be separated from the product very easily no matter what shape the spacer has, and the product will not be damaged.

In particular, if this heating temperature is made to match the heat treatment temperature of the HIP product, the spacer will be removed (mold released) during the product heat treatment process, so a special process for removing the spacer will be unnecessary. Needless to say, in order to employ this method, the spacer material must be a metal with a melting point below the heat treatment temperature of the HIP product.

In addition, when using a spacer with a composite structure as shown in FIG. 2, if there is no problem with leaving the outer layer part 2b, or if it is desirable to leave it, the outer layer part 2b It is also possible to open one end and allow only the low melting point metal inside to flow out. In this case, the material of the outer layer portion 2b is
Any metal with a melting point higher than the HIP treatment temperature is sufficient.
In particular, it does not need to be below the melting point of the HIP product.

Depending on the combination of the spacer and product metal, a reaction may occur at the interface during the HIP process, so to prevent this, a commonly used mold release agent is applied to the outer surface of the spacer. It is necessary to use a material that prevents the reaction between the two.

Although the above example shows a core as a typical example of a spacer, the present invention is not limited to this, and a plurality of spacers are arranged around the raw material powder, as in the case of forming the trough of a gear. Of course, it can also be applied to HIP molding of any other product.

As explained above, in the present invention, at least the outer layer of the spacer is formed of a metal whose melting point is higher than the HIP treatment temperature and lower than that of the product, and this is melted and flowed out after the HIP treatment. The mold release work after treatment is extremely easy, and the spacer does not melt during the HIP treatment, and when it is melted and removed afterwards, it does not infiltrate into the product due to the HIP treatment, so the properties of the HIP material are not impaired. As a result, HIP molding of irregularly shaped articles, which was previously considered difficult, becomes extremely easy, and the fields of application of HIP technology can be significantly expanded.

Also, if the melting temperature of the spacer matches the heat treatment temperature (not the melting point temperature) of the HIP product,
Since mold release is performed during the heat treatment stage, the mold release work that was conventionally performed manually is essentially omitted, making it easier to continuousize and automate the HIP product manufacturing process.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of the object to be processed used in the present invention, Fig. 2 is a sectional view showing another example of the spacer used in the invention, and Fig. 3 is a sectional view showing the object to be processed used in the invention. It is a sectional view showing other examples. 1... Capsule, 2... Spacer, 3... Raw material powder.

Claims (1)

[Scope of Claims] 1. After placing a spacer 2 in a capsule 1 to form a space corresponding to the shape of the product, filling the space with a raw material powder 3 made of ceramic or metal powder, and sealing the capsule 1. When molding a shaped article by performing densification treatment by hot isostatic pressing and then removing capsule 1 and spacer 2, at least the outer layer of said spacer 2 is heated to the hot isostatic pressing temperature. After hot isostatic press molding, the spacer 2 is melted and flowed out by heating to a temperature higher than the melting point of the spacer and lower than the melting point of the irregular shaped article. 1. A method for hot isostatic pressing of irregularly shaped articles. 2. A composite structure in which the spacer 2 is composed of an inner layer part 2a made of a metal with a melting point lower than the hot isostatic pressure treatment temperature and an outer layer part 2b made of a metal higher than the hot isostatic pressure treatment temperature and lower than the melting point of the irregular shaped article. A hot isostatic pressing method for a profiled article according to claim 1. 3 The spacer 2 has a composite structure composed of an inner layer part 2a made of a metal with a melting point lower than the hot isostatic pressure treatment temperature and an outer layer part 2b made of a metal with a melting point higher than the hot isostatic pressure treatment temperature, and the inner layer part 2a A method for hot isostatic pressing of a irregularly shaped article according to claim 1 or 2, wherein only a part of the product is melted and flowed out. 4. The method for hot isostatic pressing of a irregularly shaped article according to any one of claims 1 to 3, wherein the spacer is formed of metal powder. 5. The hot isostatic pressing method for a irregularly shaped article according to claim 4, wherein the metal powder constituting the spacer contains a metal powder that has a higher oxygen and hydrogen absorption capacity than the raw material powder. 6. Hot isostatic pressure of the irregular shaped article according to any one of claims 1 to 5, wherein a material is interposed between the spacer and the raw material powder to prevent a reaction between the two during hot isostatic pressure treatment. Molding method.