JPS5811319B2 - Irregular molding method using hot isostatic pressing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding method using a hot isostatic press method suitable for molding various complex irregularly shaped products.

The hot isostatic pressing method (hereinafter referred to as H
IP law) is widely known and attracting attention.

Compared to conventional sintering methods, alloy sintering using this method not only produces a sintered body with a more homogeneous structure and density and superior mechanical properties, but also allows sintering at low temperatures. It has certain characteristics.

However, in the conventional HIP method, when processing the raw material powder to be processed by sealing it in a capsule, the capsule is formed into a product shape, so when trying to obtain a product with a complex irregular shape, the capsule becomes complicated. It is expensive and the increase in manufacturing costs cannot be disputed, and the HIP method requires complicated operations in the degassing and sealing process, which is considered an important problem in terms of product quality, so it cannot necessarily be said to be a sufficient method. However, there was room for improvement.

Therefore, the present inventors have conducted various studies on methods for easily manufacturing irregularly shaped products that are virtually difficult to obtain using the conventional HIP method without deteriorating product quality, and as a result, Previously, we proposed a method to obtain irregularly shaped products by arranging a mold etc. in a capsule to match the product shape and filling the space formed therewith with raw material powder.

The present invention further develops this idea and aims to provide a method for manufacturing more effectively and more three-dimensionally shaped products.

Another object of the present invention is to facilitate the removal of the product after HIP processing and molding, and to relatively improve the value of the product by selecting the material.

Therefore, the present invention utilizes a relatively simple type of capsule and a modified female segment structure made of a material that has a different thermal expansion from the raw powder material to be processed, and in particular contracts under HIP conditions. Furthermore, a secondary feature is that the mold release effect on each contact surface within the capsule is improved when the segment is used.

Below, the details of the molding method of the present invention will be explained step by step. First, the first point of the present invention is to provide a capsule of a simple type, and to arrange a female mold inside the capsule according to the shape of the finished product to be molded. It is important to consider the combination with the segment structure that will be used.

The capsule used in the present invention is made of metal, glass, etc. into a simple mold, and conventional capsules can be used.

On the other hand, the number of segments disposed within the capsule may be one or more, and the segments may be appropriately combined vertically to form a structure for producing an uneven product.

This segment material has plasticity when the raw material powder of the product to be molded is molded by HIP processing, so it can be freely plastically deformed, and it reliably applies isostatic hydrostatic pressure to the powder material to be processed. A material that can be homogeneously sintered to a density of
It is preferable that the material be easily released from the mold after P treatment, or be a material that is easy to grind, cut, and process.

Of course, as mentioned above, this material causes plastic deformation, so reuse is not considered at all.Usually, this material includes mild steel, stainless steel, glass, cast materials, and processed metals. However, glass is the most effective.

They are appropriately selected and used in consideration of the coefficient of thermal expansion with respect to the raw material powder to be treated.

The unit shape of this segment is not necessarily constant, and various shapes such as round, square, disc, trapezoid, etc., or lengths of appropriate length are used depending on the shape of the finished product. is arranged as a female segment structure that conforms to the shape of the product.

The difference in thermal expansion between the segment and the powder molded product increases the shrinkage of the segment after HIP treatment, resulting in peeling of the two,
That is, it is important for improving the mold release effect.

However, in order to facilitate separation between the segment structure and the powder molded body, between the segments, and between the segments and the capsule, a release agent is appropriately used.

The mold release material may be a material that forms a coating layer, such as glass welded, alumina, silica, etc., or a mixture of other ceramics coated.

FIG. 1 shows a capsule configuration for obtaining, for example, a spur gear, in which segments are arranged in the capsule as described above, where 1 is a capsule, 2 is a segment, 3 is a raw material powder to be processed, and 4 is a mold release material. shown respectively.

FIG. 2 shows an embodiment of the capsule according to the present invention in which the female space as described above is formed in two stages within the capsule 1 with a partition plate 5 interposed, and as shown in the figure, the segments are assembled vertically like building blocks to create a boss. It is possible to easily form a gear shape having a section.

Further, FIG. 3 shows another embodiment of the capsule according to the present invention, in which a long segment is arranged in the center of the capsule 1 to form a female space, and the raw material powder 3 to be processed is filled in the capsule. .

In this case as well, a mold release material is appropriately coated on the outer periphery of the segment structure 2 to achieve a mold release effect.

At this time, the operation becomes easier by dividing the segment structure in advance into shapes that can be easily divided and removed after processing, as shown in FIG.

In addition, when the segment mold part is inside the molded body as shown in Fig. 3, it is preferable that the segment mold material shrinks more than the molded body when the HIP condition is changed to room temperature and normal pressure. The difference becomes a factor in segment material selection.

Each of the above explanations is a state before HIP processing of a capsule in which segments are arranged in the capsule to correspond to a female mold, but after filling the female mold space with raw material powder to be processed, degassing and sealing are performed as usual. The molded product is then placed in a furnace under a high-temperature Takada atmosphere and subjected to HIP treatment to obtain the desired molded product.

Note that the capsule may be subjected to the HIP treatment process without passing through the degassing process.

The molded body obtained in this way is homogeneous with no difference in density between the inside and outside of the sintered body, with isostatic pressure being reliably applied to the product shape by plastic deformation of the segment material having plasticity, and up to a high density of 100%. made as something.

Thereafter, the capsule is removed and the female mold of the segment structure is removed to form the final finished product.

Note that as a means for removing the female segment structure, machining or the like is applied as appropriate depending on the segment constituent material.

For example, if the capsule is easily released after removing the capsule, a HIP product can be obtained as is.

Segments that are difficult to release from the mold are removed by machining.

Although glass and the like can be removed by heating and further subjected to acid treatment, etc., there is no need to particularly limit the method of such removal work.

Note that this segment structure focuses on applying isostatic pressure to the molded body and is designed to cause plastic deformation, so reuse is not considered at all.

Thus, compared to products obtained by conventional HIP processing, products with more irregular shapes can be easily obtained.

Next, an example of implementation using the molding method of the present invention will be listed.

(Example) A mild steel capsule container with an inner diameter of 72 mm, a depth of 80 mm, and a thickness of 2 mm was prepared, and a mild steel round bar segment with a diameter of 20 mm was placed in the center of the container, and a mild steel segment was placed at the 6th equal dividing point on the circumferential surface of the container. The mold members were arranged in a female mold arrangement, the cross-sectional shape of which is shown in FIG.

At this time, an alumina-based scale inhibitor called Metroseal (trademark) was applied as a mold release agent to the inner surface of the capsule container and each segment of the round bar shape.

Next, the remaining space of the capsule container is filled with high-speed steel powder (steel type T15), and then a lid is welded to the container to seal it, and hot isostatic pressing is performed under the conditions shown in Figure 5. provided.

In addition, in FIG. 5, the area surrounded by dotted lines shows the pressure rise and fall accompanying the temperature rise or fall.

After performing the HIP treatment as described above, the sample was annealed, and after the annealing, it was cut to a thickness of about 5 mm, and the central round bar and mold material were removed by the effect of a mold release agent.

The cross-sectional shape of the obtained product is shown in FIG.

Although it has been difficult to obtain such spur gear shaped articles in the past, they are easily obtained and the quality is uniform, which is unique to HIP products.

As described above, according to the present invention, it is possible to easily obtain irregularly shaped articles by using a simple type of capsule and simply arranging plastic segments according to the product shape under HIP treatment conditions. By arbitrarily selecting the arrangement of segments, it is possible to easily and easily manufacture irregularly shaped products that would be difficult or extremely expensive to create using conventional HIP processing.
Together with the reduction in capsule cost, this has the remarkable effect of significantly reducing product costs.

Moreover, in the method of the present invention, the capsule itself is extremely simple;
It is easy to form a wide variety of products just by considering the arrangement of the segments, and the segment material is
Since it undergoes plastic deformation under IP processing conditions, it deforms freely during processing and reliably applies isostatic pressure to the powder material filled inside the capsule, making it possible to mold a high-density, homogeneous product. In addition, due to the difference in thermal expansion between the segments and the powder compact, the product can be removed extremely easily after HIP treatment, increasing the efficiency of HIP treatment.
It is an outstanding dog that contributes to its generalization.

[Brief explanation of drawings]

FIG. 1 is a plan sectional view showing an example of a capsule in the method of the present invention, FIG. 2 is a side sectional view of a capsule according to another embodiment,
FIG. 3 is a plan sectional view showing another modified example of the capsule structure, FIG. 4 is a plan sectional view showing a modified example of the segment, FIG. 5 is a chart showing HIP processing conditions, and FIG. 6 is the product. It is a figure showing an example. 1... Capsule, 2... Segment,
3... Raw material powder to be processed, 4... Release material.

Claims (1)

[Claims] 1. In a method of manufacturing a molded product from a powder material using a hot isostatic pressing method, a relatively simple-shaped capsule is used as the capsule 1, and the powder material to be processed and the coefficient of thermal expansion are contained inside the capsule. A segment 2 made of a material that is different in shape and has plasticity under hot isostatic pressing conditions and is freely plastically deformed is arranged so as to correspond to a female mold with respect to the shape of the finished product to be molded,
Next, the remaining space is filled with the raw material powder 3 to be processed, followed by hot isostatic pressure treatment, and then the capsule 1 and the female mold 2 having the segment structure are removed. Molding method. 2. The method for molding irregular shapes by hot isostatic pressing according to claim 1, wherein the segment material is glass that freely deforms plastically under hot isostatic pressing conditions. 3. The hot isostatic press according to claim 1 or 2, wherein a mold release material 4 made of a glass welding layer is interposed on the contact surface between the inner surface of the capsule 1 and the powder material filled therein. Irregular molding method. 4. By hot isostatic pressing according to any one of claims 1 to 3, in which a plurality of female segment structures are stacked in one capsule 1 via a partition plate 5. Irregular molding method. 5. An irregular molding method using a hot isostatic press as described in each of claims 1 to 4, wherein the female segment structure is removed by machining.