JPH0618719Y2 - Dry rubber press machine equipped with rubber mold for deformation prevention - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is mounted on a dry rubber press device for filling powder in a rubber mold and performing pressure compression molding in a pressure container filled with a room temperature liquid pressure medium. The present invention relates to a deformation preventing rubber die, and relates to a dry rubber press device including the deformation preventing rubber die.

[Conventional technology]

The shape of the rubber mold for molding used in rubber pressing of powder includes a cylindrical type, a prismatic type, a flat type, a cylindrical type (including a metal core), a spherical type, a crucible type, a nozzle type, a complex type, and the like. There are various types, and they are usually long in the direction of the central axis and have a cylindrical shape with both ends open, and generally, a rubber mold having a cylindrical shape or a cylindrical shape is most often used. When performing pressure compression molding of powder, first attach a rubber mold in the shape of a cylinder to a rubber press device to fill the powder, and then open the opening with a material such as stainless steel, which is more rigid than the rubber material of the cylinder. The pressurizing step is performed after sealing with a thick lid even if it is made of a material or a rubber material having the same rigidity. In the rubber press device, the molding rubber mold is bent around the side surface of the cylindrical body by the protective cylinder via the sealing rubber mold that seals the liquid pressure medium, and becomes the liquid pressure medium that fills the periphery of the sealing rubber mold. When pressure is applied, the pressure is transmitted to the powder through the rubber mold and compression molding proceeds. A molded product can be obtained by lowering the pressure after performing the pressure molding for a predetermined time, but in order to support the ultra-high pressure during the pressure molding, the side surface of the device and the upper and lower surfaces have an extremely rigid pressure vessel, a top cover, A bottom cover and the like are provided respectively.

The pressure from the liquid pressure medium in the pressurizing molding process is first transmitted to the sealing rubber mold, then to the side surface of the molding rubber mold cylinder and then to the powder. Since the pressure applied to each part of the body is not uniform, the molded product made by the conventional rubber press machine does not have a similar size and shape to the rubber mold for molding, but also has an inconvenient shape that is not valuable as a product. The product is a molded product, and in the case of a cylindrical molded product, an elephant-shaped defect occurs at the end portion in almost proportion to the size of the molded product.

This deformation occurs through the flow of powder at the time of the initial low pressure in the molding pressurization process. When surface pressure is applied to the side surface of the rubber molding cylinder whose powder is filled and the opening is sealed in the rubber press machine, compression starts from the part with relatively low resistance near the center of the side surface of the cylinder. However, at this time, since the molding pressure is not yet sufficient, the powder flows, and the powder is pushed into both ends of the cylinder where the resistance is large and the compression is delayed, and the final shape is reached with this initial shape. Further, the fact that the contact surface of the powder does not normally slide also causes deformation of the molded product.

In the case of a combination of a molding rubber mold and a metal lid body that are commonly used in a conventional rubber press device, in the molding pressurizing step,
Due to the restraining force generated in the molding rubber mold near the metal lid, the amount of deformation of the rubber mold becomes non-uniform only in that part, making it difficult to apply isotropic pressure to the filled powder and mold it.
Also, in the step of reducing the pressure after molding, the compression force between the powder and the metal surface or between the powder and the molding rubber mold surface is different when the rubber mold is restored to its original shape, which complicates the molding (Green). Since various forces act and the molded product is lost as a result, there is a problem that the defective rate becomes high in mass production and the used part of the molded product is reduced.

[Problems to be solved by the invention]

The present invention aims to provide a rubber mold for preventing deformation of a dry rubber press device for obtaining a powder molded product having a desired shape, and in particular, a cylindrical or cylindrical powder molding whose both ends do not spread. An object of the present invention is to provide a dry rubber press device provided with a rubber mold for preventing deformation that gives an article in a good shape without defects.

[Means for solving problems]

According to the present invention, a cover (32, 34) is attached to each opening of both ends of a cylindrical rubber molding die (12) of a dry rubber press machine and sealed to form inside the rubber molding die (12). Spacers (24, 26) made of rigid bodies are inserted inside the openings of both ends of the powder filling chamber (18), and these spacers (24, 2)
6) The deformation preventing rubber molds (14, 16) are fitted inside and positioned, and the deformation preventing rubber molds (14, 16) are inserted into the molding rubber mold (12) and the spacers (24, 26). ) Provided is a dry rubber press device provided with a rubber mold for preventing deformation, which is formed of a foamable rubber or a soft rubber made of a softer elastic body.

The deformation preventing rubber mold of the present invention is formed of foaming rubber or soft rubber, but any other soft rubber substance may be used, and the softer rubber substance is more preferable. When actually used as a lid for a molding rubber mold, it is necessary to consider between the softness of the material rubber and the wall thickness of the lid, but a rubber substance with sufficient softness is required. So long as a normal thick lid is used, no inconvenience will occur. If a conventional metallic lid is used as the lid of the molding rubber mold, defective molding naturally occurs, but defective molding occurs even if hard rubber having a relatively high hardness is used. The entire lid of the molding rubber mold may be formed by the deformation preventing rubber mold of the present invention.
It is possible to form a part of the lid body (the side in contact with the filled powder) with the deformation preventing rubber mold of the present invention and the remaining part with a material having a high hardness such as metal or hard rubber. If at least a part of the lid on the side in contact with the body is the deformation preventing rubber mold of the present invention, defective molding does not occur.

The softness of the deformation-preventing rubber mold of the present invention correlates with the relative difference in softness between the molding rubber mold and the softness of the molding rubber mold. It is necessary to determine the material of the rubber mold for deformation prevention in consideration of the material of the mold. It is preferable that the deformation preventing rubber mold is made of foaming rubber or soft rubber that is softer than the molding rubber mold, and good results can be obtained by using any size rubber mold. For example, if the molding rubber mold is made of high hardness natural rubber (polyisoprene) and the lid is made of natural rubber of the same material, molding failure will occur, and the molding rubber mold will be made of polyurethane with hardness lower than that of natural rubber. Even if it is formed, if the lid is made of polyurethane of the same material, molding defects will occur, but if the molding rubber mold is made of natural rubber and the deformation prevention rubber mold of the entire lid is made of soft polyurethane foam. No defective molding occurs.Furthermore, if a rubber mold for molding is made of polyurethane having a hardness lower than that of natural rubber, and a rubber mold for deformation prevention is formed of soft polyurethane foam sponge as a part of the lid body, defective molding occurs. do not do.

[Action]

At the time of the initial low pressure during the molding pressurization step in the rubber press pressure compression molding, non-uniform pressure is applied to the powder filled in the powder filling chamber formed by the molding rubber mold and the lid, and at this time, the powder is baked. Since the binding is not perfect, the flow of powder is unavoidable and the molded product will be deformed. This is because the lid body made of highly rigid metal used in the past is a rubber for molding powder in the powder filling chamber. This is due to the restriction of the flow in the direction of the mold center axis. If the deformation preventing rubber mold of the present invention is used for the lid, the freedom of flow of the powder in the central axis direction is increased, and the powder flow in the central axis direction is smoothed during the molding pressurizing process. As a result, elephant-shaped defects do not occur at the end of the molded product. In particular, in the present invention, a powder filling chamber is formed inside the molding rubber mold, and a spacer made of a rigid body is inserted inside each opening of both ends of the powder filling chamber. By fitting and positioning the deformation-preventing rubber molds, the pressing force between the powder and the lid or between the powder and the molding rubber mold does not differ significantly, and the rubber mold returns to its original shape during the step-down process. A complicated force does not act on the molded product during the restoration process, and defects such as defects are suppressed.

〔Example〕

A specific configuration example of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to this example.

FIG. 1 is a sectional view of a dry rubber press device equipped with a deformation preventing rubber die according to the present invention. In a rubber press device, a powder filling chamber 18 is formed from a tubular molding rubber mold 12 having a metal core 10, an upper deformation preventing rubber mold 14 and a lower deformation preventing rubber mold 16 to form a molding rubber. The mold 12 is surrounded by a protective cylinder 22 via a sealing rubber mold 20, and the periphery of the sealing rubber mold 20 is filled with a liquid pressure medium (oil, water, oil-water emulsion, etc.). In this embodiment, inside the openings of both ends of the powder filling chamber, an upper spacer 24 and a lower spacer 26, which are made of a rigid material such as stainless steel, are inserted, and inside the spacers 24 and 26, respectively. The deformation preventing rubber molds 14 and 16 were fitted together. In addition, the deformation-preventing rubber mold uses foamed sponge-like rubber, which is extremely effective in preventing powder molding defects due to uneven deformation. The rubber mold for sealing was made of a rubber having strong tear strength, high elongation, high resilience, and oil and water resistant rubber. High pressure during pressurization process (42 when molding alumina)
A pressure vessel 28 is provided on the side surface of the apparatus, and a punch 30, a top cover 32, and a bottom cover 34 are provided on the upper and lower surface portions in order to support a pressure of 00 kg / cm ² ).

After the powder filling chamber 18 is filled with the powder, when the pressure is applied to the liquid pressure medium filled around the sealing rubber mold 20 and communicating with the pressure source through the through hole 36, the pressure is generated through the rubber mold. It is transmitted to the body and compression molding proceeds. Compression molding is carried out at a predetermined pressure for a predetermined time, and a molded product is obtained through a pressure reducing step. Core 10
By removing and pressing the rubber, a cylindrical molded product can be obtained.

[Effect of device]

"Release of elephant foot phenomenon" occurs when rubber pressing is performed with the dry rubber press device equipped with the rubber mold for deformation prevention configured as described above.
It is possible to obtain a straight cylindrical or columnar molded product having no outer periphery. That is, even if a simple rubber mold for forming a cylindrical body is used, a molded product such as a column or a pipe having no defective shape can be obtained, and the molded product is a uniform product without defective end dimension. Further, the molded product is free from defects, the defective rate is reduced, and the used part of the molded product can be effectively utilized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a dry rubber press device having a rubber mold for preventing deformation according to the present invention. 10: Core, 12: Molding rubber mold 14: Upper deformation preventing rubber mold 16: Lower deformation preventing rubber mold 18: Powder filling chamber, 20: Sealing rubber mold 22: Protection Cylinder, 24 ... upper spacer 26 ... lower spacer, 28 ... pressure vessel 30 ... punch, 32 ... top cover 34 ... bottom cover, 36 ... through hole

Claims (1)

[Scope of utility model registration request] 1. A rubber mold for cylindrical molding of a dry rubber press device.
Covers (32, 34) are attached to both end openings of (12) and sealed, and inside both end openings of the powder filling chamber (18) formed inside the molding rubber mold (12), respectively. While inserting the spacers (24, 26) made of a rigid body, these spacers (24, 2)
6) The deformation preventing rubber molds (14, 16) are fitted inside and positioned, and the deformation preventing rubber molds (14, 16) are inserted into the molding rubber mold (12) and the spacers (24, 26). ) A dry rubber press device provided with a rubber mold for preventing deformation, which is formed of a foamable rubber or a soft rubber made of a softer elastic body.