JP5039628B2 - Hydrostatic pressure mold - Google Patents

Description

  The present invention relates to an isostatic pressing mold, and more particularly to an isostatic pressing mold that can prevent cracks from occurring on the end face of a cylindrical ceramic molded body during pressing.

  An example of a method for pressure forming a cylindrical ceramic molded body such as a soot tube is isostatic pressing (hereinafter also referred to as “CIP molding”). Generally, CIP consists of each process of powder filling, pressurization, pressure reduction, and a molded object taking out, and is used suitably for shaping | molding of a cylindrical ceramic molded object (for example, refer nonpatent literature 1).

However, the CIP molding has a problem that cracks occur on the end face of the obtained cylindrical ceramic molded body.
P. J. et al. Edited by James, translated by Yoshiya Kaieda, "HIP and CIP", Nikkan Kogyo Shimbun, August 22, 1986, p99

  In order to prevent the occurrence of such cracks on the end face, a method of forming a portion corresponding to the end of the hydrostatic pressure molding die with rubber can be considered. However, since the rubber is deformed during pressure molding, the ceramic molded body There was a problem that the levelness of the end face of the glass was impaired. In this case, an end face processing step is further required.

  In addition, a lubricant or the like is applied to the portion of the hydrostatic pressure molding die that contacts the end surface of the ceramic molded body, and the end surface of the ceramic molded body at the time of molding and the portion that contacts the end surface of the hydrostatic pressure molding die A method of preventing the occurrence of cracks by reducing the friction between the two is also conceivable. However, in this method, since it is necessary to apply a lubricant or the like every time a ceramic molded body is manufactured, there is a problem that production efficiency is lowered and resources such as a lubricant need to be used in excess. .

  The present invention has been made in view of such problems of the prior art, and its object is to prevent the occurrence of cracks on the end face of a cylindrical ceramic molded body during pressure molding. An object of the present invention is to provide a hydrostatic pressure mold that can be used.

  To achieve the above object, the present invention provides the following hydrostatic pressure mold.

[1] A cylindrical cored bar, a lid part detachably disposed at one end of the cored bar, a bottom part disposed at the other end of the cored bar, the cored bar, A cylindrical molding rubber mold disposed from the lid portion to the bottom portion so as to form a space between the lid portion, a surface of the lid portion facing the core metal side, and the bottom portion Each of the surfaces facing the cored bar is a plane perpendicular to the cored bar, and diamond-like carbon is formed on the surface facing the cored bar side of the lid part, the bottom part, or both the lid part and the bottom part. A hydrostatic pressure mold with a membrane.

[2] The hydrostatic pressure molding die according to [1], wherein the diamond-like carbon film is disposed on surfaces of both the lid portion and the bottom portion facing the cored bar side.

[3] The hydrostatic pressure mold according to [1] or [2], wherein the diamond-like carbon film has a thickness of 0.1 to 20.0 μm.

  As described above, according to the hydrostatic pressure molding die of the present invention, since the diamond-like carbon film is disposed on the surface facing the metal core side of the lid portion, the bottom portion, or both the lid portion and the bottom portion, the ceramic molding is performed. When the body is molded, it is possible to reduce the friction between the end surface of the ceramic molded body and the portion in contact with the end surface of the isostatic pressing mold, thereby preventing the occurrence of cracks.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and is within the scope of the present invention. Based on this knowledge, it should be understood that design changes, improvements, etc. can be made as appropriate.

  As shown in FIG. 1, one embodiment of the hydrostatic pressure molding die of the present invention is a cylindrical cored bar 1 and a lid part detachably disposed on one end 1 a of the cored bar 1. 2 and the bottom 3 disposed at the other end 1b of the cored bar 1 and the cored bar 1 so as to form a space (forming space) V1 from the lid 2 to the bottom 3 Cylindrical molding rubber mold 4 provided, and a cylindrical hole with a plurality of through-holes disposed from cover 2 to bottom 3 so as to cover the outside of molding rubber mold 4 The outer cylinder part 5 is provided. The hydrostatic pressure molding die 100 of the present embodiment further includes a surface (inner surface of the lid portion) 2a facing the core metal 1 side of the lid portion 2 and a surface (inside of the bottom portion) facing the core metal 1 side of the bottom portion 3. The surface 3a is a plane orthogonal to the cored bar 1. Further, a diamond-like carbon (DLC) film 6 is disposed on the surfaces of the lid and the bottom facing the metal core (the inner surface 2a of the lid and the inner surface 3a of the bottom). Yes. FIG. 1 is a schematic view showing a cross section cut along a plane parallel to the central axis direction of one embodiment of the hydrostatic pressure molding die of the present invention.

  For example, when forming a cylindrical tub tube using the hydrostatic pressure molding die 100 of the present embodiment, first, the lid portion 2 is opened, the ceramic powder is filled into the molding space V1, and the lid portion 2 is closed. Thereafter, the hydrostatic pressure molding die 100 is placed in the pressure vessel 11, a pressurizing medium is press-fitted into the pressure vessel 11, and the molding rubber die 4 is pressed in the direction of the central axis to compress the ceramic powder. Thus, a cylindrical shaped body can be obtained. Thereafter, the pressurized medium is taken out from the inside of the pressure vessel 11, the molding rubber mold 4 is restored, the inside of the molding space V1 is returned to normal pressure, and the cylindrical molded body is taken out. Here, as the pressurizing medium, water containing anticorrosive and lubricating additives can be used. Moreover, it is preferable that the pressure when press-fitting a pressurizing medium is 50 to 200 MPa. When the pressure is lower than 50 MPa, compression molding may not be performed sufficiently. When the pressure is higher than 200 MPa, the apparatus may be overloaded. The pressurizing medium is supplied by a pressurizing pump.

  Thus, when forming a cylindrical molded body, the molded body molded at a high pressure expands in the radial direction and the vertical direction by the springback phenomenon when returning to normal pressure. At this time, since the end surface of the molded body is deformed while being pressed by the inner surface 2a of the lid and the inner surface 3a of the bottom, stress is concentrated on the end surface and cracks are generated. Such cracks are prominent when only ceramic powder obtained by finely pulverizing an insulator raw material such as porcelain stone, feldspar, clay, etc. is used without using an organic binder in consideration of environmental problems. On the other hand, when the hydrostatic pressure molding die 100 of this embodiment is used, the DLC film is disposed on the inner surface 2a of the lid and the inner surface 3a of the bottom, and the end surface of the molded body comes into contact with the DLC film. Therefore, the occurrence of cracks on the end surface of the molded body can be prevented by the effect of reducing friction between the end surface of the molded body and the DLC film when the molded body expands and deforms. Also, the surface 2a of the lid 2 facing the core 1 (the inner surface of the lid) and the surface 3a of the bottom 3 facing the core 1 (the inner surface of the bottom) 3a are all orthogonal to the core 1 Therefore, the obtained cylindrical molded body has a shape in which both end faces are parallel and orthogonal to the cylindrical inner peripheral surface. Thereby, for example, an excellent soot tube can be formed. Moreover, since the DLC film 6 is arrange | positioned in the inner surface 2a of a cover part and / or the inner surface 3a of a bottom part, the isostatic pressing mold 100 of this embodiment shape | molds ceramic powder, and forms a molded object. After the formation, when the molded body is taken out, the end face of the molded body and the surface of the DLC film are easily separated from each other. Therefore, it is necessary to apply a release agent to the inner surface 2a of the lid and / or the inner surface 3a of the bottom. Absent.

  In the hydrostatic pressure molding die 100 of this embodiment, the DLC film 6 is disposed on both the inner surface 2a of the lid and the inner surface 3a of the bottom. If any one of the end surfaces of the resulting molded body is prone to cracking depending on the state of the above, it is disposed only on the side where the crack is likely to occur (the inner surface 2a of the lid or the inner surface 3a of the bottom). May be.

  The film thickness of the DLC film is preferably 0.1 to 20.0 μm, and more preferably 1.0 to 10.0 μm. If it is thinner than 0.1 μm, wear may easily occur. If it is thicker than 20.0 μm, there is a possibility of peeling because the internal stress of the film is high. Moreover, although the manufacturing method of a DLC film is not restricted, It is preferable that it is formed by the CVD method and PVD method using plasma.

  In the hydrostatic pressure molding die 100 of the present embodiment, the length of the core metal 1 and the diameter of the cross section perpendicular to the central axis can be appropriately determined according to the size of the cylindrical molded body to be produced. For example, the core metal 1 having a thickness of 500 to 4000 mm can be suitably used. Moreover, the material of the metal core 1 is preferably a metal material such as ordinary steel.

  In the hydrostatic pressure molding die 100 of the present embodiment, the lid portion 2 and the bottom portion 3 have a disk shape in which the surfaces facing each other (the inner surface 2a of the lid portion and the inner surface 3a of the bottom portion) are flat. It is preferable. Further, as shown in FIG. 1, the lid portion 2 and the bottom portion 3 are provided with a molding rubber mold 4 and an outer cylinder portion 5 with a hole, so that a step is formed with respect to the disk shape. preferable. Moreover, the cover part 2 and the bottom part 3 may each be a laminate of a plurality of disk-shaped members. The lid 2 and the bottom 3 are preferably arranged such that their centers are located on the central axis of the cored bar 1. The thickness and outer diameter of the lid part 2 and the bottom part 3 can be appropriately determined according to the size of the cylindrical molded body to be produced. The material of the lid 2 and the bottom 3 is preferably a metal material such as ordinary steel.

  In the hydrostatic pressure molding die 100 of the present embodiment, the molding rubber die 4 is cylindrical and has a bottom portion from the lid portion 2 so as to form a space (molding space) V1 between the core metal 1. 3 are arranged. The molding space V <b> 1 is a space formed by being surrounded by the molding rubber mold 4, the core metal 1, the lid portion 2, and the bottom portion 3. The outer peripheral side of the molding rubber mold 4 is pressed by the pressure medium, deforms so as to be recessed toward the space inside the cylinder, and pressurizes the molding space V1. Thereby, the ceramic powder filled in the forming space V1 is formed into a cylindrical shape. The length of the molding rubber mold 4 is not particularly limited as long as it can be fixed to the lid portion 2 and the bottom portion 3 as shown in FIG. Further, the outer diameter of the molding rubber mold 4 can be appropriately determined according to the size of the cylindrical molded body to be produced. The thickness of the molding rubber mold 4 is preferably 5 to 30 mm. When the molding rubber mold 4 is attached to the lid portion 2 and the bottom portion 3, it is preferably attached by a method of fastening with a fixing band.

  The hydrostatic pressure molding die 100 of the present embodiment can be suitably used to produce a cylindrical soot tube having an outer diameter of 250 to 600 mm, an inner diameter of 50 to 300 mm, and a height of 500 to 4000 mm.

  The manufacturing method of the hydrostatic pressure mold 100 of the present embodiment is not particularly limited, and can be manufactured by a known metal processing, rubber molding method, and these assembling methods. As described above, the method for disposing the DLC film on the lid 2 or the bottom 3 is not limited to the manufacturing method, but it is preferable to use a CVD method using plasma or PVD.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
A disc-shaped lid portion having a diameter of 460 mm is disposed at one end portion of a cylindrical core metal having a length of 2000 mm × a diameter of 150 mm, and a disc-shaped bottom portion having the same diameter is disposed at the other end portion of the core metal, A cylindrical molding rubber mold is formed between the lid and the bottom by forming a space between the core and the base, and is fixed to the lid and the bottom by a method of fastening with a fixing band to cover the outside of the molding rubber mold. Thus, the cylindrical outer cylinder part with a hole was fixed to the cover part and the bottom part from the cover part to the bottom part, and the hydrostatic pressure molding die as shown in FIG. 1 was produced. In order to make the lid part detachable, it was not fixed to the core metal, and the bottom part was fixed to the core metal by bolting. A DLC film having a thickness of 3 μm was formed on the entire inner surface of the lid portion and the entire inner surface of the bottom portion (excluding the portion where the cored bar is disposed). The DLC film was formed by a pulse plasma CVD method. Moreover, both the inner surface of the cover part and the inner surface of the bottom part were planes orthogonal to the cored bar. The material of the cored bar, the lid part, the bottom part, and the outer cylinder part was ordinary steel. The material of the molding rubber mold was natural rubber. The evaluation of the preparation of the soot tube was performed by the following method. The results are shown in Table 1.

(Evaluation of tubule production)
Open the lid of the hydrostatic pressure mold, fill the molding space with ceramic raw material containing porcelain stone, feldspar, and clay, close the lid, and use the water as the pressurizing medium to remove the molding rubber mold A ceramic raw material was formed by press-fitting at 100 MPa between the cylindrical portion and a cylindrical soot tube was obtained. The obtained soot tube was cylindrical with an outer diameter of 360 mm, an inner diameter of 150 mm, and a height of 2000 mm. The state of occurrence of cracks on both end faces of the obtained soot tube was visually confirmed. The case where no crack was generated was “◯”, the case where the crack was reduced was “Δ”, the case where the crack was generated was “x”, and “◯” was passed.

(Comparative Example 1)
A hydrostatic pressure mold was prepared in the same manner as in Example 1 except that the inner surface of the lid and the inner surface of the bottom were plated with chrome without disposing a DLC film and applied with silicone oil. As in the case of Example 1, the fistula production evaluation was performed. The results are shown in Table 1.

(Comparative Example 2)
A hydrostatic pressure molding die was produced in the same manner as in Example 1 except that the inner surface of the lid and the inner surface of the bottom were plated with chromium without providing a DLC film and applied with a lubricating oil. As in the case of Example 1, the fistula production evaluation was performed. The results are shown in Table 1.

(Comparative Example 3)
The same as in Example 1 except that the DLC film was not disposed on the inner surface of the lid and the inner surface of the bottom, the surface was polished and the surface roughness was smoothed to 1/5, and chrome plating was applied. A hydrostatic pressure mold was prepared. As in the case of Example 1, the fistula production evaluation was performed. The results are shown in Table 1.

  From Table 1, it can be seen that the DLC film prevents cracks on the end face of the soot tube.

  A cylindrical ceramic molded body such as a soot tube can be used for pressure molding while preventing cracks on the end face.

It is a schematic diagram which shows the cross section cut | disconnected by the plane parallel to the central-axis direction of one Embodiment of the isostatic pressing mold of this invention.

Explanation of symbols

1: cored bar, 1a: one end, 1b: other end, 2: lid, 2a: inner surface of lid, 3: bottom, 3a: inner surface of bottom, 4: rubber mold for molding, 5: Outer cylinder with holes, 6: Diamond-like carbon film, 11: Pressure vessel, 100: Hydrostatic pressure molding die, V1: Molding space.

Claims (3)

Between the cylindrical cored bar, a lid part detachably disposed at one end of the cored bar, a bottom disposed at the other end of the cored bar, and the cored bar A cylindrical molding rubber mold disposed from the lid to the bottom so as to form a space;
Both the surface facing the cored bar side of the lid part and the surface facing the cored bar side of the bottom part are planes orthogonal to the cored bar,
A hydrostatic pressure molding die in which a diamond-like carbon film is disposed on a surface of the lid portion, the bottom portion, or both the lid portion and the bottom portion facing the cored bar side.   2. The hydrostatic pressure molding die according to claim 1, wherein the diamond-like carbon film is disposed on surfaces of both the lid portion and the bottom portion facing the cored bar side.   The hydrostatic pressure molding die according to claim 1 or 2, wherein the diamond-like carbon film has a thickness of 0.1 to 20.0 µm.

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