JP2920101B2 - Dry isostatic pressing apparatus and dry isostatic pressing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry isostatic pressing apparatus and a dry isostatic pressing method for molding, for example, ceramic powder, metal powder and the like.

[0002]

2. Description of the Related Art In general, dry hydrostatic pressure molding (hereinafter referred to as CIP molding) includes steps of powder filling, pressurization, decompression, and removal of a compact, and is suitably used for molding a bottomed cylindrical shape. Can be

[0003] The molding process by CIP molding is shown in Figs.
This will be described with reference to FIG. First, as shown in FIG. 11, a molding powder A such as a ceramic powder or a metal powder is inserted into a molding space 8 in a pressure vessel 2 via a powder feeding nozzle 1.
Will be filled. Here, the pressure vessel 2 has therein a molding space 8 formed by a column-shaped mandrel 3, a cylindrical molding rubber mold 4, and a bottom punch 9 that supports the mandrel 3 from below. On the outer peripheral side of the rubber mold 4 in the circumferential direction, a pressure-medium sealing rubber 5 surrounding the molding rubber mold 4 is provided. The pressure vessel 2 is provided with a pressure medium inlet / outlet 6. Reference numeral 7 denotes a seal rubber holder.

[0004] The molding powder A inserted and filled into the molding space 8 in the pressure vessel 2 is inserted into a top punch 11 having a top rubber stopper 10 in the upper part of the pressure vessel 2 and then into FIG.
As shown in FIG. 2, the pressure medium sealing rubber 5 and the molding rubber mold 4 are pressurized by a pressure medium flowing from a high pressure pump (not shown) through a pressure medium inlet / outlet 6 via a pressure intensifier (not shown). Compression molded. After the completion of the compression molding, as shown in FIG.
To allow the molding rubber mold 4 to be restored,
As shown in FIG. 14, the bottomed cylindrical molded body 12 is taken out of the pressure vessel 2 by raising the top punch 11 and lowering the bottom punch 9.

[0005] Incidentally, the cylindrical molded product manufactured as described above may require high wall thickness accuracy depending on the purpose of use. For example, in the case of a β-alumina tube used in a sodium-sulfur battery, the thickness of the tube differs depending on the portion, that is, if there is uneven thickness, the penetration of sodium ions increases in a thin portion which is advantageous in terms of electric resistance. . Therefore, only the thin portion is selectively used, which results in accelerated deterioration of the β-alumina tube.
Further, in a thin portion, the heat resistance and mechanical strength of the β-alumina tube are reduced, which is not preferable. Therefore, in the β-alumina tube, it is preferable to minimize uneven thickness.

[0006]

SUMMARY OF THE INVENTION However, CI
In P molding, since the mandrel is supported in a cantilever manner, it is difficult to support the axis of the mandrel in parallel with the axis of the molded rubber mold, and this has caused uneven thickness of the molded product. .

In the CIP molding apparatus, it is necessary to provide a clearance between the molding rubber mold and the sealing rubber for the convenience of mounting the sealing rubber on the sealing rubber holder. Therefore, even if the axis of the mandrel can be supported in parallel with the axis of the molded rubber mold, it is difficult to match the axis of the mandrel with the axis of the molded rubber mold due to the existence of these clearances. , Causing uneven thickness.

Conventionally, in order to prevent such uneven thickness, conventionally, a metal foil having a predetermined thickness is interposed between a bottom punch and a part of a contact surface of a bottom ram that supports the bottom punch, so that the mandrel can be axially connected to the bottom punch. A method of adjusting the deviation in the angle of the axis of the molded rubber mold has been adopted.

However, in the above method, the insertion position of the metal foil may slightly change during the adjustment, and it has been difficult to accurately adjust the angle of the axis of the mandrel.
In addition, the surface contact between the bottom punch and the bottom ram becomes impossible due to the insertion of the metal foil, and the force at the time of pressurization is concentrated on the point contact portion between the metal foil insertion portion and the outer punch on the opposite side. Becomes Therefore, there has been a problem that the thickness of the metal foil gradually changes, and the bottom punch and the bottom ram undergo plastic deformation in the metal foil insertion portion and the point contact portion, thereby changing the inclination of the mandrel.
Furthermore, this method is a method for making the axis of the mandrel parallel to the axis of the molded rubber mold, and it is not possible to match the axes of both, so that it is not possible to completely prevent uneven thickness. Was.

[0010]

Means for Solving the Problems The present invention has been made in view of such a situation, and an object of the present invention is to reduce the thickness deviation of a bottomed cylindrical molded body to 0.2 mm or less. It is an object of the present invention to provide a dry isostatic pressing apparatus and a dry isostatic pressing method.

That is, according to the present invention, a rubber mold for molding, a columnar mandrel disposed therein, and a bottom punch disposed below the rubber mold for molding and supporting the mandrel in a cantilever manner After filling the raw material powder into the space formed by the rubber mold for molding, the mandrel, and the bottom punch, the cylindrical body with the bottom is formed by applying hydrostatic pressure with a pressure medium from the outer peripheral side of the rubber mold for molding. This is a dry hydrostatic pressure molding device that performs molding of the mold, and eliminates the deviation in the angle between the axis of the molding rubber mold and the axis of the mandrel by adjusting the fixing angle of the bottom punch with respect to the molding rubber mold. After that, by adjusting the fixing position of the mandrel to the bottom punch, there is provided a dry-type isostatic pressing apparatus that matches the axis of the rubber mold for molding with the axis of the mandrel.

The dry isostatic pressing apparatus further includes a bottom ram that supports the bottom punch, the bottom punch being connected to the bottom ram on a side opposite to the side on which the mandrel is mounted, and the bottom punch and the bottom ram. It is preferable to eliminate the deviation in the angle between the axis of the rubber mold for molding and the axis of the mandrel by interposing an inclined plate having a predetermined inclination between them.

In the above-mentioned dry type isostatic pressing apparatus, the mandrel is mounted on the bottom punch by inserting one end of the mandrel into an insertion hole provided in the bottom punch. It passes through the center of the molding surface and has a length in any one or two directions from the center. By fixing the mandrel to the bottom punch at a predetermined position in the insertion hole, the center of the rubber mold for molding is formed. It is preferable that the axis of the mandrel coincides with the axis of the mandrel.

Further, according to the present invention, there is provided a dry isostatic pressing method for forming a bottomed cylinder using the above-described dry isostatic pressing apparatus.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Thickness deviation in CIP molding of a bottomed cylindrical body is caused by the fact that the axis of a rubber mold for molding does not coincide with the axis of a mandrel. There are two modes in which the two do not coincide with each other: a case where there is a deviation in the angle between the two (FIG. 2), and a case where the positions of the two components are displaced (FIG. 3).

In the present invention, by adjusting the fixed angle of the bottom punch supporting the mandrel in a cantilever manner with respect to the rubber mold for molding, the deviation in the angle between the axis of the rubber mold for molding and the axis of the mandrel is adjusted. Has been resolved.
Further, by adjusting the fixing position of the mandrel to the bottom punch, it is possible to make the axis of the rubber mold for molding coincide with the axis of the mandrel.

In order to adjust the fixed angle of the bottom punch, a bottom ram, which is a support member of the bottom punch, is connected to the bottom punch on the side opposite to the side on which the mandrel is mounted, and the bottom ram is placed between the bottom punch and the bottom ram. It is preferable to interpose an inclined plate having a predetermined inclination.

FIG. 4 shows an example of an inclined plate used in the present invention. The inclined plate 19 has an inclination 21 corresponding to a deviation in the angle between the axis of the molding rubber mold 4 and the axis of the mandrel 3. The size of the slope 21 is determined by making a prototype without using the slope plate and measuring the thickness deviation. As shown in FIG.
Is in surface contact with the lower surface of the bottom punch 9 and the upper surface of the bottom ram 20, so that the molding pressure is appropriately dispersed and no excessive pressure is applied to a specific portion of the inclined plate 19.
It is preferable that the inclined plate 19 has a hole 22 at the center and has a disk shape. Hole 22
Is provided for passing a projection 18 provided on the bottom punch 9 to fix the bottom punch 9 at a predetermined position on the bottom ram 20 and a through bolt 23 for reinforcing the fixing of the mandrel 3. As the material of the inclined plate 19, SKD-based or SKH-based hardened steel or the like is suitably used.

Further, in order to adjust the fixing position of the mandrel to the bottom punch, an insertion hole passing through the center of the molding surface and having a length in any one or two directions from the center is formed in the bottom punch. Preferably, the mandrel is fixed to the bottom punch at a predetermined position in the insertion hole.

By doing so, the axis of the mandrel adjusted in parallel with the axis of the rubber mold for molding by the inclined plate can completely coincide with the axis of the rubber mold for molding. The width of the insertion hole must be the size of the diameter of the mandrel insertion shaft plus some clearance so that the mandrel can move only in the length direction of the insertion hole, and the length of the insertion hole is , 0.5 to the width of the insertion hole
It is preferable that the size is added with 1.0 mm.

The position of the mandrel to be fixed in the insertion hole is determined by producing a prototype with the molded body fixed at an arbitrary position and measuring the size of the uneven thickness. That is, by measuring the thickness of the uneven thickness, it is determined how much the mandrel should be moved from the position of the mandrel at the time of trial production of the molded body.

As shown in FIG. 6, if the length of the insertion hole 15 is extended only in one direction, the mandrel 3 can be
The mandrel 3 can be easily moved to the center of the molding surface, and the mandrel 3 can be moved in accordance with the degree of uneven thickness with reference to the center after trial production of the molded body in that state. There is an advantage.

When extending the length of the insertion hole in two directions from the center of the molding surface of the bottom punch, as shown in FIG.
It is preferable to extend in opposite directions on one straight line.

The mandrel is, for example, as shown in FIGS.
And is fixed at a predetermined position in the insertion hole 15. Further, a through bolt 23 penetrating the bottom ram 20 and the bottom punch 9 and an insertion shaft 16 of the mandrel 3 are provided.
The mandrel 3 is reinforced by screwing the lower end thereof and fixing the through bolt 23 to the bottom surface of the bottom ram 13 by the fixing nut 24.

[0025]

Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiments, but the present invention is not limited to these embodiments.

Using the above-described CIP molding apparatus, the outer diameter 4
A bottomed cylindrical molded body having a size of 7.0 mm, an inner diameter of 42.7 mm, and a height of 435 mm was produced. This molded article is used as a β-alumina tube for a sodium-sulfur battery.

FIG. 1 shows the structure of a CIP molding apparatus used for molding. In the CIP molding apparatus 14 shown in FIG. 1, a cylindrical rubber mold 4 and a columnar mandrel 3 are disposed inside the pressure vessel 2, and a top punch is provided on each of the upper and lower parts of the rubber mold 4. 11 and a bottom punch 9 are provided. The molding space 8 is formed by the inner peripheral surface of the molding rubber mold 4, the peripheral surface of the mandrel 3, the lower surface of the top punch 11, and the upper surface of the bottom punch 9. On the outer peripheral surface of the molding rubber mold 4, a pressure-medium sealing rubber 5 is arranged so as to surround the molding rubber mold 4.

The mandrel 3 is mounted on the bottom punch 9 via an insertion hole 15 provided on the upper surface of the bottom punch 9. The insertion hole 15 has an oval shape extending in one direction from the center of the bottom punch 9, and has a width obtained by adding a clearance of 0.02 mm or less to the diameter of the insertion shaft 16 of the mandrel 3, The length is 0.5m from the width of the insertion hole 15.
m larger. The insertion shaft 16 of the mandrel 3 has two sides,
It is clamped by a stud 17 provided in the length direction of the insertion hole 15. The mandrel 3 is fixed by the bottom ram 13.
Of the mandrel 3 and the lower end of the insertion shaft of the mandrel 3 are screwed together.

The bottom punch 9 is supported by a bottom ram 20 via a projection 18 provided on its lower surface, and an inclined plate 19 is provided between the bottom punch 9 and the bottom ram 20.
Is installed.

First, in order to measure the degree of uneven thickness, as shown in FIG. 8, a mandrel 3 was fixed to the center of the bottom punch 9 and a molded body was prototyped using a parallel plate 25 having no inclination.

The measurement of uneven thickness was performed as follows. First, the thickness was measured at 16 points provided at regular intervals on the outer periphery at positions of 30 mm and 350 mm from the bottom of the molded body. Next, the difference between the maximum value and the minimum value of the wall thickness at each position was calculated and defined as an uneven wall thickness value. The point indicating the maximum value and the point indicating the minimum value always have a positional relationship facing each other on the circumference.

At a position 30 mm from the bottom of the tube, the maximum and minimum wall thicknesses are 2.142 mm and 1..
892 mm, and therefore, the uneven thickness value was 0.250 mm. The maximum value and the minimum value of the wall thickness at a position 350 mm from the pipe bottom are 2.195 mm and 1.
875 mm, and therefore, the thickness deviation value was 0.320 mm.

The magnitude and direction of the deviation in the angle between the axis of the molding rubber mold and the axis of the mandrel indicate the difference between the thickness deviation values between the above two measurement positions and the maximum and minimum values. The inclination and the installation direction of the inclined plate were determined based on the values.

Further, the moving distance of the mandrel in the insertion hole was determined based on the thickness deviation value at each measurement position. In this embodiment, since the insertion hole has an oval shape extending in one direction from the center of the bottom punch 9,
The moving distance of the mandrel is determined as the moving distance from the center of the bottom punch 9.

The adjustment of the thickness deviation was performed as follows. First,
An inclined plate having an inclination corresponding to the magnitude of the angle shift is prepared, and as shown in FIG. 9, the direction in which the mandrel 3 is inclined in FIG. 8 matches the maximum thickness portion 26 of the inclined plate 19. As described above, the inclined plate 19 is provided between the bottom punch 9 and the bottom ram 13.

Next, by turning the bottom punch 9, the direction in which the long axis of the insertion hole 15 extends is adjusted to the position where the molded body exhibits the maximum thickness, and the position of the mandrel 3 is moved by the calculated moving distance. Then, the axis of the rubber mold for molding and the axis of the mandrel were aligned as shown in FIG.

By adjusting the thickness deviation as described above, the thickness deviation of the molded body could be suppressed to 0.2 mm or less. In addition, it was possible to suppress the change with time of the thickness deviation observed when the metal foil was used.

[0038]

According to the present invention, the deviation in the angle between the axis of the molding rubber mold and the axis of the mandrel is eliminated by adjusting the fixing angle of the bottom punch that supports the mandrel in a cantilever manner. I have. Further, by adjusting the fixing position of the mandrel to the bottom punch, it is possible to make the axis of the rubber mold for molding coincide with the axis of the mandrel. Therefore, the uneven thickness of the bottomed cylindrical molded body is 0.2 mm
The control can be performed as follows. For example, it is possible to prevent deterioration of the β-alumina tube of the sodium-sulfur battery and decrease in heat resistance and mechanical strength.

If the fixed angle of the bottom punch is adjusted using the inclined plate, the inclined plate is in surface contact with the bottom punch and the bottom ram, so that the molding pressure is appropriately dispersed. Therefore, it is possible to prevent a situation in which the inclined plate or the like does not deform and the uneven thickness changes with time.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an example of a CIP molding apparatus according to the present invention.

FIG. 2 is an explanatory view showing one mode of mismatch between the axis of a molding rubber mold and the axis of a mandrel.

FIG. 3 is an explanatory view showing another mode in which the axis of the rubber mold for molding does not coincide with the axis of the mandrel.

4A is a plan view and FIG. 4B is a side view showing an example of an inclined plate.

FIG. 5 is a sectional view of the bottom ram used in the CIP molding apparatus shown in FIG. 1, taken along line AA.

6A is an explanatory cross-sectional view and FIG. 6B is a cross-sectional view taken along a line BB, showing an example of a connection portion between a mandrel and a bottom punch.

7A is a cross-sectional explanatory view and FIG. 7B is a cross-sectional view taken along the line CC, showing another example of a connection portion between the mandrel and the bottom punch.

FIG. 8 is a schematic diagram showing a relationship between a mandrel axis and a molded rubber mold axis before an inclined plate is mounted.

FIG. 9 is a schematic diagram showing a relationship between a mandrel axis and a molded rubber mold axis after the inclination plate is mounted.

FIG. 10 is a schematic diagram illustrating a relationship between a mandrel axis and a molded rubber mold axis after the mandrel is moved.

FIG. 11 is an explanatory sectional view showing a powder filling step of the CIP molding method.

FIG. 12 is an explanatory sectional view showing a pressing step of the CIP molding method.

FIG. 13 is an explanatory sectional view showing a pressure reducing step of the CIP molding method.

FIG. 14 is an explanatory cross-sectional view showing a molded product removing step of the CIP molding method.

[Explanation of symbols]

1 ... powder feeding nozzle, 2 ... pressure vessel, 3 ... mandrel,
4 ... molding rubber mold, 5 ... pressure medium sealing rubber, 6 ... pressure medium inlet / outlet, 7 ... seal rubber holder, 8 ... molding space, 9
... Bottom punch, 10 ... Top rubber stopper, 11 ... Top punch, 12 ... Molded body, 13 ... Bottom ram, 14 ...
CIP molding device, 15 insertion hole, 16 mandrel insertion shaft, 17 stud bolt, 18 protrusion, 19 ...
Inclined plate, 20: bottom ram, 21: inclined, 22
... Hole of inclined plate, 23 ... Through bolt, 24 ...
Fixing nut, 25: Parallel plate, 26: Maximum wall thickness of inclined plate.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-89465 (JP, A) JP-A-5-285926 (JP, A) JP-A-5-169415 (JP, A) 126505 (JP, A) Japanese Utility Model Hei 2-6196 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B28B 3/00 102

Claims (4)

(57) [Claims] 1. A rubber mold for molding, a columnar mandrel disposed therein, and a bottom punch disposed below the rubber mold for molding and supporting the mandrel in a cantilever manner. After filling the raw material powder into the space formed by the rubber mold for molding, the mandrel, and the bottom punch, a hydrostatic pressure is applied from the outer peripheral side of the rubber mold for molding by a pressure medium to form the bottomed cylindrical body. A dry hydrostatic pressure molding apparatus for performing molding, wherein an angle between an axis of the molding rubber mold and an axis of the mandrel is adjusted by adjusting a fixing angle of the bottom punch with respect to the molding rubber mold. And then adjusting the fixing position of the mandrel to the bottom punch so that the axis of the rubber mold for molding and the axis of the mandrel coincide with each other. Dry hydrostatic pressing apparatus that. 2. A bottom ram supporting the bottom punch, wherein the bottom punch is connected to the bottom ram on a side opposite to a side on which the mandrel is mounted, and a predetermined inclination is provided between the bottom punch and the bottom ram. 2. The dry isostatic pressing apparatus according to claim 1, wherein an inclination between the axis of the rubber mold for molding and the axis of the mandrel is eliminated by interposing an inclined plate having: 3. The mandrel is mounted on the bottom punch by inserting one end of the mandrel into an insertion hole provided in the bottom punch, and the insertion hole passes through a center of a molding surface of the bottom punch, The mandrel has a length in any one or two directions from the center, and the mandrel is fixed to the bottom punch at a predetermined position in the insertion hole, so that the axis of the rubber mold for molding and the mandrel are fixed. The dry isostatic pressing apparatus according to claim 1 or 2, wherein the axis coincides with the axis. 4. A dry isostatic press using the dry isostatic press according to any one of claims 1, 2 and 3. Molding method.