JPH07150203A - Forming die for rubber press - Google Patents

Abstract

PURPOSE:To provide a forming die for rubber press, in which a forming body having high dimensional precision can be formed and also, the service life of the elastic mold can be extended. CONSTITUTION:The inner surface 3a of a metallic die 2 has >=3.0mu ten point average roughness (Rz) and the ruggedness crossing at almost the right angle to the shrinking direction of the rubber mold. Powdery material is always made to shrunk in the crossing direction at almost the right angle by shrinking the rubber mold, and the shrinking degree of the powdery material is not developed to the difference in the radial direction.

Description

Detailed Description of the Invention

[0001]

The present invention relates to CIP (Cold I).
The present invention relates to a rubber press molding die suitable for use in a rubber press molding method (isostatic molding method) such as a so-static press molding method.

[0002]

2. Description of the Related Art As a general rubber press molding die used in a CIP molding method, there is known one in which a cavity having a predetermined shape is formed by an inner surface of a rubber elastic die and an inner surface of a metal rigid die. (Japanese Patent Laid-Open No. 62-224498)
Issue). In such a rubber press molding die, powder is filled in the cavity, and in this state, it is put into the pressure medium of the cold isostatic press. Then, by increasing the pressure of the pressure medium, it is possible to form the isotropic powder through the contraction of the elastic mold.

[0003]

However, in the conventional molding die for rubber press, in order to reduce the processing cost of the rigid die, there are cases where the rigid die that has been processed by a lathe, a milling machine or the like is used. In this case, as shown in FIGS. 9A and 9B, on the inner surface 90a of the rigid die 90, scratches (irregularities) 91 which are not necessarily determined in the direction substantially orthogonal to the contraction direction of the elastic die are generated by the lathe or the like. . Rigid mold 9 having such inner surface 90a
When 0 is used as a rubber press forming die together with an elastic die (not shown) to form powder, the elastic die shrinks, which causes a difference in the degree of shrinkage of the powder in the radial direction. That is, if the unevenness 91 exists only partially in the contraction direction of the elastic type, the powder moves in the direction along the unevenness 91 under a small resistance force and greatly contracts, and the unevenness 9
In the direction orthogonal to 1, the powder moves under a large resistance force and shrinks slightly. For this reason, for example, if a columnar molded body is molded, the molded body that is in contact with the inner surface 90a has different degrees of shrinkage between the direction of the unevenness 91 and the direction orthogonal to this, so that the molded body is The end face is distorted into an ellipse or the like, and accurate dimensional accuracy cannot be obtained.

Further, in the conventional rubber press molding die,
Since the powder filled in the cavity contacts the inner surface of the rigid mold with a low resistance force, the inner surface of the rigid mold may be mirror-finished from the viewpoint of facilitating the molding. In this case, since the inner surface of the rigid mold has a uniformly low coefficient of friction, the powder that contacts the inner surface of the rigid mold can move with a smaller resistance force than the powder that does not contact the inner surface of the rigid mold. The portion of the molded body that was in contact with the sheet tends to excessively shrink. Therefore, for example, if a cylindrical molded body is molded, the end surface of the molded body has a small diameter, and accurate dimensional accuracy cannot be obtained. Further, in this case, since the portion of the molded body that is in contact with the inner surface of the rigid mold causes excessive shrinkage, the elastic mold is locally largely deformed in the vicinity of the boundary with the rigid mold, which causes early deterioration of the elastic mold. Will also occur.

The present invention has been made in view of the above conventional circumstances, and provides a rubber press molding die capable of molding a molded body with high dimensional accuracy and extending the life of an elastic die. The purpose is to

[0006]

A rubber press molding die according to claim 1 is a rubber press molding die in which a cavity having a predetermined shape is formed by an inner surface of an elastic die and an inner surface of a rigid die. The inner surface is characterized in that it has a ten-point average roughness (Rz) of 3.0 μm or more and has irregularities substantially orthogonal to the contraction direction of the elastic mold.

According to a second aspect of the present invention, there is provided a rubber press forming die in which a cavity having a predetermined shape is formed by an inner surface of an elastic die and an inner surface of a rigid die, wherein the inner surface of the rigid die is 3 in Rz. It is characterized in that it is 0.0 μm or more and has random irregularities.

[0008]

[Action]

(1) When the powder is molded by the rubber press molding die according to claim 1, since the inner surface of the rigid mold has irregularities substantially orthogonal to the contraction direction of the elastic mold, the powder contracts by the elastic mold. Is always contracted in a direction substantially orthogonal to the unevenness,
The degree of shrinkage of the powder does not differ in the radial direction. Therefore, for example, in the case of molding a columnar molded body, the portion of the molded body in contact with the inner surface does not differ in the degree of shrinkage in the radial direction, that is, the direction of irregularities and the direction orthogonal to this, The end face is not easily distorted into an ellipse.

Further, in this case, since the inner surface of the rigid die has irregularities that are substantially orthogonal to the contracting direction of the elastic die, the inner surface of the rigid die has a high friction coefficient in the contracting direction of the elastic die and is always substantially orthogonal to the irregularity. The powder moved in the direction moves and contracts under a large resistance force. If the inner surface of the rigid mold has an Rz of 3.0 μm or more, this resistance is almost equal to the resistance when the powder not in contact with the inner surface contracts. For this reason, the powder contacting the inner surface of the rigid mold can move with a resistance force almost equal to that of the powder not contacting the inner surface of the rigid mold, and the portion of the molded body contacting the inner surface of the rigid mold causes excessive shrinkage. Never. Therefore, for example, if a cylindrical molded body is molded, the end surface of the molded body does not have a small diameter.

Further, in this case, since the portion of the molded body which is in contact with the inner surface of the rigid die does not excessively shrink, the deformation of the elastic die hardly changes even near the boundary with the rigid die. (2) When powder is molded by the rubber press molding die according to claim 2, since the inner surface of the rigid die has random irregularities, the elastic die shrinks so that the powder always shrinks beyond the irregularities. As a result, the degree of shrinkage of the powder does not differ in the radial direction. For this reason, for example, if a columnar molded body is molded, the portion of the molded body that is in contact with the inner surface does not differ in the degree of shrinkage in the radial direction, and the end surface of the molded body is unlikely to be distorted into an ellipse or the like.

Further, in this case, since the inner surface of the rigid die has random irregularities, the inner surface of the rigid die has a uniformly high coefficient of friction, and the powder that is constantly moved over the irregularity has a large resistance force. Move and contract with. If the inner surface of the rigid mold has an Rz of 3.0 μm or more, this resistance is almost equal to the resistance when the powder not in contact with the inner surface contracts. For this reason, the powder contacting the inner surface of the rigid mold can move with a resistance force almost equal to that of the powder not contacting the inner surface of the rigid mold, and the portion of the molded body contacting the inner surface of the rigid mold causes excessive shrinkage. Never. Therefore, for example, if a cylindrical molded body is molded, the end surface of the molded body does not have a small diameter.

Further, in this case, since the portion of the molded body which is in contact with the inner surface of the rigid die does not excessively shrink, the deformation of the elastic die hardly changes even near the boundary with the rigid die. In addition, in this rubber press molding die, it is relatively easy to form random irregularities on the inner surface of the rigid die by shot blasting or the like.

[0013]

【Example】

(Example 1) The molding die for a rubber press of Example 1 embodies claim 1. This rubber press molding die is for molding a columnar molding, and as shown in FIG. 1, a cylindrical rubber die 1 as an elastic die and a rigid die for closing both openings of the rubber die 1. And the metal molds 2 and 2. The metal molds 2 and 2 have protrusions 3 and 3 having an outer diameter substantially equal to the inner diameter of the rubber mold 1. Thus, a cylindrical cavity is formed by the inner surface 1a of the rubber mold 1 and the inner surfaces 3a, 3a of the protrusions 3, 3.

Inner surface 3 of the convex portions 3 and 3 of the metal molds 3 and 3.
As shown in FIGS. 2A and 2B, a plurality of concentric circular groove-shaped concavities and convexities are formed on a and 3a by press working. Rz of each inner surface 3a, 3a is 3.0 due to each unevenness.
It is made more than μm. In the rubber press molding die, the powder P is filled in the cavity, and in this state, the powder P is put into the pressure medium of the cold isostatic pressing device. Then, by increasing the pressure of the pressure medium, the isotropic powder P can be molded through the radial contraction of the rubber mold 1.

At this time, the inner surfaces 3a, 3a of the metal molds 2, 2 are
Has a concavo-convex that is substantially orthogonal to the contracting direction of the rubber mold 1, the contraction of the rubber mold 1 always causes the powder P to contract in a direction substantially perpendicular to the concavo-convex, and the degree of contraction of the powder P is There is no difference in the radial direction. Therefore, the inner surfaces 3a, 3
The portion of the molded body that was in contact with a does not differ in the degree of shrinkage in the radial direction, that is, the direction of the unevenness and the direction orthogonal to this,
The end face of the molded body is unlikely to be distorted into an ellipse or the like.

Further, since the inner surfaces 3a, 3a of the metal molds 2, 2 have irregularities substantially orthogonal to the contracting direction of the rubber mold 1,
The inner surfaces 3a, 3a of the metal molds 2, 2 have a high friction coefficient in the contraction direction of the rubber mold 1, and the powder P that is always moved in a direction substantially orthogonal to the unevenness moves and contracts under a large resistance force. . For this reason, the portions of the molded body that are in contact with the inner surfaces 3a, 3a of the metal molds 2, 2 do not excessively shrink, and the molded body does not have a small end surface.

Further, since the parts of the molded body which are in contact with the inner surfaces 3a, 3a of the metal molds 2, 2 do not excessively shrink, the rubber mold 1 is deformed even near the boundary between the metal molds 2, 2. Almost unchanged. Therefore, with this rubber press molding die, it is possible to mold a molded body with high dimensional accuracy and to extend the life of the rubber mold 1. (Embodiment 2) The molding die for rubber press of Embodiment 1 embodies claim 2.

This rubber pressing mold is also for molding a columnar molded body, and as shown in FIGS. 3A and 3B, the inner surfaces 5a of the convex portions 5, 5 of the metal molds 4, 4 are formed. ,
A plurality of random irregularities are formed on 5a by shot blasting. Each inner surface 5a, 5a has an Rz of 3.0 μm or more due to each unevenness. Other configurations are the same as those in the first embodiment.

Powder P is produced by the rubber press molding die.
When the molding is performed, since the inner surfaces 5a, 5a of the metal molds 4, 4 have random irregularities, the powder P always shrinks beyond the irregularities due to the contraction of the rubber mold 1,
The degree of shrinkage of the powder P does not differ in the radial direction. For this reason, the degree of shrinkage does not differ in the portions of the molded body which are in contact with the inner surfaces 5a, 5a, and the molded body is less likely to be distorted into an elliptical end surface or the like.

Further, since the inner surfaces 5a, 5a of the metal molds 4, 4 have random irregularities, the inner surface 5 of the metal molds 4, 4 is
a and 5a have a uniformly high friction coefficient, and the powder P that is constantly moved over the irregularities moves and contracts under a large resistance force. For this reason, the portions of the molded body which are in contact with the inner surfaces 5a, 5a of the metal molds 4, 4 do not excessively shrink, and the molded body does not have a small end surface.

Further, since the parts of the molded body which are in contact with the inner surfaces 5a, 5a of the metal molds 4, 4 do not excessively shrink, the rubber mold 1 is deformed even near the boundary between the metal molds 4, 4. Almost unchanged. Therefore, also in this rubber press mold, it is possible to mold a molded body with high dimensional accuracy and to extend the life of the rubber mold 1. Further, in this rubber press forming die, the inner surfaces 5a, 5a of the metal dies 4, 4 are formed by shot blasting.
Since it is relatively easy to form the irregular asperities on a, the manufacturing cost of the molded body can be reduced. (Test) As shown in FIG. 4, a plurality of rubber press molding dies for molding a valve-shaped molded body are prepared. Each rubber press molding die is composed of a rubber die 6 having an inner surface of a valve outer shape as an elastic die, and metal dies 7a and 7b as rigid dies for closing both openings of the rubber die 6. Metal mold 7
a and 7b are formed by a quenching / tempering material of SKD61, and have a convex portion 8a having an outer diameter substantially equal to the outer diameter of the valve face.
8b. Thus, the inner surface 6a of the rubber mold 6,
A valve-shaped cavity is formed by the entire inner surface 9a of the convex portion 8a of the lower metal die 7a and the central area 9b of the inner surface of the convex portion 8b of the upper metal die 7b.

Similar to the first embodiment, by pressing, a plurality of concentric groove shapes are formed on the entire inner surface 9a of the convex portion 8a of the lower metal die 7a and the central area 9b of the inner surface of the convex portion 8b of the upper metal die 7b. To form irregularities. The respective rubber press molding dies differ in Rz of the inner surface entire area 9a and the inner surface central area 9b in the range of 0.8 to 25 μm. Further, as in the second embodiment, the entire inner surface 9a is formed by shot blasting.
And a plurality of random irregularities are formed on the inner surface central region 9b.

On the other hand, pure Ti powder and Al ₃ V powder were mixed with each other at 9:
A mixed powder P mixed at a weight ratio of 1 is prepared. A predetermined amount of this mixed powder P is weighed and filled in the cavity of each rubber press mold. Then, CIP molding is performed as in the first and second embodiments. FIG. 5 shows the amount of deviation (μm) from the average value of the diameter of the obtained molded body on the valve face surface. FIG. 6 shows the variation (μm) in diameter of the obtained molded body on the valve face surface.

From FIGS. 5 and 6, when Rz is less than 3.0 μm, that is, when it is close to a mirror surface, the friction coefficient of the unevenness of the entire inner surface 9a of the metal mold 7a is low, so that the mixed powder P moves with a low resistance force. However, it can be seen that the deviation amount and the variation of the average value of the diameter are large. Further, as a result, the portion of the molded body that is in contact with the entire inner surface 9a of the metal mold 7a undergoes excessive shrinkage, so that the rubber mold 6 is locally largely deformed in the vicinity of the boundary with the metal mold 7a. It can also be seen that the mold 6 is likely to be prematurely deteriorated.

Therefore, it is understood that Rz should be 3.0 μm or more in both cases of forming concentric groove-shaped irregularities and random irregularities. It is considered that when Rz is 3.0 μm or more, the resistance force of the mixed powder P contracted beyond the unevenness is almost equal to the resistance force of the mixed powder P not contacting the entire inner surface 9a when contracted, It is considered that this is because the mixed powder P that is in contact with the entire inner surface 9a moves with substantially the same resistance force as the mixed powder P that is not in contact with the entire inner surface 9a. (Other Examples) In the case where the inner surface is formed in a square shape in order to form a rectangular columnar shaped body, as shown in FIG. 8
As shown in (A), it is also possible to form random irregularities on the entire inner surface of the square.

When the inner surface is formed into an ellipse in order to form an elliptical columnar molded body, as shown in FIG. 7 (B), the concavities and convexities are formed into concentric elliptical grooves, or as shown in FIG. (B)
As shown in, random irregularities can be formed on the entire inner surface of the elliptical shape. Further, in the case where the inner surface is formed into a triangle in order to form a triangular columnar formed body, as shown in FIG. 7 (C), the concavities and convexities are formed into concentric triangular grooves, or as shown in FIG. 8 (C). As shown in, random irregularities can be formed on the entire inner surface of the triangle.

When the inner surface is formed in a hexagonal shape in order to form a hexagonal columnar molded body, as shown in FIG. 7 (D), the concavities and convexities are formed in concentric hexagonal groove shapes, Figure 8
As shown in (D), it is also possible to form random unevenness on the entire inner surface of the hexagon.

[0028]

As described in detail above, the rubber press molding die according to the first and second aspects adopts the structure described in the claims, and therefore a molded body with high dimensional accuracy can be molded. In addition, the life of the elastic type can be extended.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rubber press molding die according to a first embodiment.

2 is a plan view showing a metal mold of Example 1, FIG.
(B) is a sectional view.

FIG. 3 relates to a metal mold of Example 2, (A) is a plan view,
(B) is a sectional view.

FIG. 4 is a cross-sectional view of a rubber press molding die used in a test.

FIG. 5 is a graph showing a relationship between a ten-point average roughness and a deviation amount from an average value of diameters in a test.

FIG. 6 is a graph showing the relationship between ten-point average roughness and diameter variation in a test.

FIG. 7 is a plan view of an inner surface according to another embodiment.

FIG. 8 is a plan view of an inner surface according to another embodiment.

FIG. 9 relates to a metal mold of a conventional rubber press molding die,
(A) is a plan view and (B) is a sectional view.

[Explanation of symbols]

1, 6 ... Rubber type (elastic type) 1a, 6a ... Inner surface of rubber type (elastic type) 2, 4, 7a, 7b ... Metal type (rigid type) 3a, 5a, 9a, 9b ... Metal type (rigid type) Inside

[Procedure amendment]

[Submission date] April 18, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

Further, in the conventional rubber press molding die,
Since the powder filled in the cavity contacts the inner surface of the rigid mold with a low resistance force, the inner surface of the rigid mold may be mirror-finished from the viewpoint of facilitating the molding. In this case, since the inner surface of the rigid die has a uniformly low coefficient of friction, the powder in contact with the inner surface of the rigid die can move with a resistance force almost equal to that of the powder that does not contact the inner surface of the rigid die, causing contraction.
The amount is almost the same as the shrinkage of the powder that is not in contact with the inner surface of this rigid mold.
Will be equal. Dimensions of molded products molded by the rubber press method
Since the accuracy depends on the amount of shrinkage of the powder, the dimensional accuracy
The degree is the same level as the part that is not in contact with the inner surface.
It Especially when the dimensional accuracy of the end surface of the molded product is required.
It is difficult to achieve the required accuracy with the conventional method. Further, in this case, since the portion of the molded body that is in contact with the inner surface of the rigid mold causes excessive shrinkage, the elastic mold is locally largely deformed in the vicinity of the boundary with the rigid mold, which causes early deterioration of the elastic mold. Will also occur.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

Further, in this case, since the inner surface of the rigid die has irregularities that are substantially orthogonal to the contracting direction of the elastic die, the inner surface of the rigid die has a high friction coefficient in the contracting direction of the elastic die and is always substantially orthogonal to the irregularity. The powder moved in the direction moves and contracts under a large resistance force. If the inner surface of the rigid mold has an Rz of 3.0 μm or more, this resistance will not be the amount of movement of the powder.
Since the amount of shrinkage is small, the roundness of the end surface of the molded product
Dimensional accuracy is improved.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Further, in this case, since the inner surface of the rigid die has random irregularities, the inner surface of the rigid die has a uniformly high coefficient of friction, and the powder that is constantly moved beyond the irregularity has a large resistance force. Move and contract with. This resistance is, if the inner surface of the rigid type 3.0μm or more Rz, powder transfer
Since the amount of movement, that is, the amount of shrinkage is small,
Dimensional accuracy such as roundness is improved.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Further, since the inner surfaces 3a, 3a of the metal molds 2, 2 have irregularities substantially orthogonal to the contracting direction of the rubber mold 1,
The inner surfaces 3a, 3a of the metal molds 2, 2 have a high friction coefficient in the contraction direction of the rubber mold 1, and the powder P that is always moved in a direction substantially orthogonal to the unevenness moves and contracts under a large resistance force. . Therefore, the inner surface 3a of the metal mold 2 and 2, portions of the molded body in contact with the 3a is without causing excessive shrinkage, true
A molded product having good dimensional accuracy such as circularity can be obtained.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Further, since the inner surfaces 5a, 5a of the metal molds 4, 4 have random irregularities, the inner surface 5 of the metal molds 4, 4 is
a and 5a have a uniformly high friction coefficient, and the powder P that is constantly moved over the irregularities moves and contracts under a large resistance force. Therefore, the portions of the molded body that are in contact with the inner surfaces 5a and 5a of the metal molds 4 and 4 do not excessively shrink, and a molded body with good dimensional accuracy such as roundness can be obtained.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

Therefore, it is understood that Rz should be 3.0 μm or more in both cases of forming concentric groove-shaped irregularities and random irregularities. This is because if Rz is 3.0 μm or more, the movement of the powder during contraction will occur.
It is considered that this is because the dynamic amount, that is, the contraction amount becomes small . (Other Examples) In the case where the inner surface is formed in a square shape in order to form a rectangular columnar shaped body, as shown in FIG. 8
As shown in (A), it is also possible to form random irregularities on the entire inner surface of the square.

Claims (2)

[Claims] 1. A rubber press molding die in which a cavity having a predetermined shape is formed by an inner surface of an elastic die and an inner surface of a rigid die, wherein the inner surface of the rigid die has a ten-point average roughness of 3.0 μm or more. And a molding die for a rubber press, which has irregularities extending in a direction substantially orthogonal to the contracting direction of the elastic die. 2. A molding die for a rubber press in which a cavity having a predetermined shape is formed by an inner surface of an elastic die and an inner surface of a rigid die, wherein the inner surface of the rigid die has a ten-point average roughness of 3.0 μm or more. A molding die for a rubber press having random irregularities.