JPS5837101A - Generating method for hydrostatic pressure - Google Patents

Abstract

PURPOSE:To generate uniform hydrostatic pressure by laminating and combining in an axial direction elastic bodies of the same quality which differ in hardness, restraining the deformation in a circumferential direction from the outside and applying pressure in the axial direction. CONSTITUTION:A powder molding 4 enclosed with a rubber mold 2 and elastic bodies 3a, 3a' is contained in a cylindrical die 1, and is pressurized with a pressurizing rod 5, whereby hydrostatic pressure is generated. Here, the uniform hydrostatic pressure is obtained by laminating and combining the bodies 3a, 3a' differing in hardness alternately >=2 layers. It is equally avilable to laminate and combine the bodies 3a, 3a' differing in the modulus of longitudinal elasticity alternately in >=2 layers. Thus the uniform hydrostatic pressure is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of generating uniform hydrostatic pressure using an elastic body, and in particular, a method suitable for generating uniform pressure by combining two or more types of elastic bodies. Regarding the method.

Conventionally, known methods for generating hydrostatic pressure include a method of pressurizing water or oil using a pump, or a method of heating gas to a high temperature and utilizing the generated expansion force. The most common method is to generate hydrostatic pressure, but the capacity of a pressurizing pump is limited, and large-scale equipment is required to generate high pressure. In addition, the method using the expansion force of gas is generally a high temperature hydrostatic pressure generator ()lIp-1 (Ol Illo
It is possible to obtain a uniform pressure of 2000 Kgf/cnP or more using a device called Iitatic press. However, the method of generating hydrostatic pressure using expansion force is as shown in FIG. In this method, a powder 4 wrapped in an elastic body 3 is stored and pressurized with a pressurizing rod 5 to generate hydrostatic pressure. This method is possible if you have a device that can apply a high load such as a press.
It has the characteristic that a pressure of ~4000Kgf/;- can be easily obtained. However, since the pressure medium is a heteroelastic body with water, there is a drawback that the pressure distribution is not uniform, that is, perfect hydrostatic pressure is not achieved. For this reason, problems such as partially different densities occur during powder molding, for example.

An object of the present invention is to combine two or more types of elastic bodies in a method of applying pressure using an elastic body as a pressure medium.
It is an object of the present invention to provide a method for generating hydrostatic pressure that can apply a highly uniform pressure.

In the method shown in Fig. 1, when a load is applied from the top to a single elastic body, the pressure generated on the inner surface of the mold 1 is highest at the restrained part between the pressurized iron surface A and the mold bottom surface B. high,
The pressure distribution decreases toward the center. The reason for this is as follows.

When applying positive pressure to a cylindrical mold IK as shown in Fig. 1 using an elastic body, that is, when trying to deform it, the total amount of work Wa required is equal to the work WR required to deform the elastic body and the cylinder shape. Processing required to deform only mold 1 4
It is considered that it is the sum of IWc.

Wa=W*+Wc ・・・・・・・・・・・・
......(11Here, if P is the total load and PR is the load during uniaxial compression of the elastic body, equation (1) is / Pads = = / P ds + / π old pdS
...Dan...(2) becomes OOO. Here, S is the displacement amount of the pressure rod 5, R,
is the radius of the elastic body 3, and p is the pressure on the inner surface of the cylindrical mold 1. Therefore, when both ends are restrained, the relationship between the axial pressure p with respect to the cross-sectional area before deformation and the lateral pressure p acting on the inner surface of the cylindrical mold 1 is given by the following equation.

1' @ ” p heat + 1), (p-pm-pm) ・
...Old... (3) On the other hand, the force and strain during free uniaxial compression of various elastic bodies are shown in Figure 2, where pII and strain are in a proportional relationship.In Figure 1, the curve represents hard elasticity. Curve 2 is for an elastic body of medium hardness, and curve 3 is for a soft elastic body.

Further, as shown in FIG. 3(a), for example, when a cylindrical elastic body is subjected to a load from the top and is allowed to freely deform (b), a large strain usually occurs toward the center. Therefore, from the relationship of equation (3), the lateral pressure p decreases in direction toward the center as shown by e→. When a load is applied to a single elastic body in this way, it is extremely difficult to obtain a uniform pressure distribution.

The present invention allows uniform pressure to be obtained even when using an elastic body. The basis of the invention is to keep pm constant in equation (3). Specifically, as shown in Figure 2, a method of combining two or more types of elastic bodies with different amounts of strain (g = g□, #x) in order to obtain the same axial compressive stress p, = p. It is. By this method, the amount of strain in the axial direction can be made uniform, I)m in equation (3) is constant at each part, and a uniform lateral pressure p can be obtained.

In this method of applying a load to an elastic body and generating pressure, it is possible to create a uniform pressure inside a container or mold by combining two or more types of elastic bodies with different hardnesses or longitudinal elastic modulus. In other words, it becomes possible to generate hydrostatic pressure.

Combinations of elastic bodies are shown in FIGS. 4 to 6.

FIG. 4 shows a method of obtaining uniform pressure or hydrostatic pressure by alternately laminating two or more layers of the same type of elastic bodies 3m and 3a' having different hardnesses. FIG. 5 shows a method of obtaining uniform pressure or hydrostatic pressure by alternately stacking two or more layers of elastic bodies 3b, 3b' having different longitudinal elastic modulus. 6th
The figure shows a method for obtaining uniform hydrostatic pressure by laminating similar elastic bodies 30, 3c' with different hardnesses and elastic bodies 3C'' with different longitudinal elastic modulus.

[Example 1] This will be explained with reference to FIG.

Powder 4, which was a mixture of iron powder and aluminum powder at a weight ratio of 6:4, was filled into a silicone rubber (hardness: 40@) space with a space of 4×15×60×. Surround this rubber mold with 3 layers of silicone rubber (hardness 5G) with a diameter of 100m and a thickness of 20wm.
) and silicone rubber 3a/(hard [60@) were alternately laminated in a total of 5 layers, and a load of 184 tons was applied to the top of the rubber. Considering the pressure transmission efficiency of the combined rubber, this load would generate a pressure of approximately 2600 to 9f/6I/I. The shape of the powder molded product is 3.1■
It was 31.5m.

Compared to the rubber space shape, this shape has approximately 50 mm on each side.
%, proving that hydrostatic pressure was generated. In addition, when we measured the density of the blocks cut out from each part of the molded product, the density of the upper and lower parts was 95.3% of the theoretical value, and that of the central part was 95.2%, indicating that extremely uniform molding was achieved. It was done.

On the other hand, the same mixed powder was filled into the same rubber mold, the periphery was covered with silicone rubber (hardness 60@) having a diameter of 100 fi and a total thickness of 200 m, and a load of 190 mm was applied to the top of the rubber. At this time, as a result of measuring the density of each part, the upper and lower parts of the molded product were 95.3% of the theoretical value, and the central part was 92.6%.
%, there was uneven molding. .

[Example 2] A pipe joint was processed using the method of the present invention.

The method is shown in FIG. 7, where 5 is a pressure rod, 6 is a rod, 7 is a surface plate, and 8 is a mold. The shape of the elastic body used was an outer diameter of 117.8 sam, an inner diameter of 80 mm, a thickness of 20 m, and the combinations and loads are as shown in Table 1. The pipe for processing the joint has a nominal outer diameter of 127 mm and a thickness of 4.5 mm.
It is a carbon steel pipe of m. The state of deformation at the end of the tube at this time is shown in FIG.

As is clear from Table 1, the pressure distribution is much more constant when processing using a combination of silicone rubber and metal or silicone rubber and urethane rubber than when processing using a single elastic body. A good joint can be obtained.

As explained above, according to the present invention, since uniform deformation can be given to an object, a powder compact with uniform density can be obtained in powder compaction.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of the conventional method of generating pressure using an elastic body, Figure 2 is a stress/strain diagram of elastic bodies with different hardness, and Figure 3 is the strain and strain generated on the inner surface of the cylinder in the conventional method. Fig. 4 is a longitudinal cross-sectional view of a method for generating uniform or hydrostatic pressure by combining elastic bodies of the same type with different hardnesses, and Fig. 5 is a diagram showing a method for generating uniform or hydrostatic pressure by combining elastic bodies with different longitudinal elastic modulus. A vertical cross-sectional view of a method for generating uniform or hydrostatic pressure. Figure 6 is a vertical cross-sectional view of a method for generating uniform or hydrostatic pressure by combining elastic bodies with different hardness and elastic bodies with different longitudinal elastic modulus. Figure 7 is a vertical cross-sectional view of a method for generating uniform or hydrostatic pressure. An explanatory diagram of an embodiment of a method of obtaining a good joint without using a mold by combining bodies, and FIG. 8 is a diagram showing the shape of a tube end formed by the method shown in FIG. 7. . 1.8...Mold, 2...Rubber mold, 3.3m, 3a'
. 3b, 3b', 3C, 3C', 3C"... Elastic body, 4... Powder molded body, 5... Pressure rod. Agent: Patent attorney Toshiyuki Usuda 1 Figure □ ¥52 Figure vl Mi No. 3I￥] (A) 8th 41￥] Fan 5I2] Fig. 6

Claims (1)

[Claims] 1. In a method of applying an axial load to an elastic body, restraining deformation of the elastic body in the circumferential direction from the outside, and applying pressure inside the restraint body, the elastic body is A hydrostatic pressure generation method characterized by generating uniform pressure by combining and laminating. 2. A method for generating hydrostatic pressure according to item 1, characterized in that a uniform pressure is generated by laminating and combining homogeneous elastic bodies having different hardnesses in the axial direction. 3. A method for generating hydrostatic pressure according to item 1, characterized in that a uniform pressure is generated by laminating and combining two or more types of elastic bodies having different hardnesses or Young's moduli in the axial direction. 4. In the method described in item 1, two or more kinds of homogeneous elastic bodies with different hardnesses and two or more kinds of elastic bodies with different Young's moduli are laminated in the axial direction.
A method of generating hydrostatic pressure that, when combined, produces a very uniform pressure.