JPH0380598B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wet cold isostatic pressurizing device, and is used in the fields of powder metallurgy and ceramics in conjunction with mold molding methods, cast molding methods, etc. Ru.

(Prior technology) There are two types of cold isostatic pressing (hereinafter sometimes abbreviated as CIP): a dry method and a wet method. The principle, application, and fields of use are detailed in the R&D/Kobe Steel Technical Report (Vol. 31, Vol. 31, published on January 30, 1981). No. 1), pages 45 to 47.

That is, in the conventional example 1, as shown in each figure in FIG. Pressure medium 6 supplied from
As a result, molding is performed with isostatic pressure up to the required molding pressure (see Fig. 5, 2), and the axial pressure at that time is borne by the press frame 1, and after pressure molding, the pressure is The pressure medium 6 is discharged and the pressure is reduced to atmospheric pressure to complete the molding. (See Figure 5 3).

As a result of this series of pressure molding, the volume of the powder shrinks by 50 to 60% as shown in FIG.

The loading of the powder and the removal of the molded body are carried out by moving the press frame 1 using a press frame moving cylinder 9 and by raising the upper lid using an upper lid lifting cylinder 8.

Figure 6 shows the operation circuit (water pressure device) of the CIP device mentioned above.
The pressure ports have a high pressure port 7a and a low pressure port 7B, respectively, and a water supply pump 11 and a low pressure pump 1.
2, high pressure pump 13, pressure reducing valve 14, water supply and drainage valve 1
5, a tank 16 for the pressure medium 6, a drainage pump 17, a drainage valve 18, etc.

That is, as shown in Figure 7, 150
Focusing on the fact that powder shrinks by 40 to 50% at a low pressure of about Kg・f/cm ² , the low-pressure pump 12 has a large discharge rate of about 150 Kg・f/cm ² and a small discharge rate that pressurizes it to the final molding pressure. Due to the two-stage pressure increase using the high-pressure pump 13,
This is intended to shorten the molding time.

Further, as a second conventional example, there is a rubber press described in Japanese Utility Model Application Publication No. 51-123287.

In other words, two molding containers are installed in a press frame in which upper and lower platens are connected to each other by a column, and the frame is shared, and the same molding pressure can be switched and applied to the two molding containers. There is a technique in which a hydraulic device is provided and the hydraulic device is shared.

(Problems to be Solved by the Invention) In Conventional Example 1, when molding is performed in series from low pressure to high pressure in one molding container 3, the volumetric shrinkage rate is generally 50 to 50, as shown by A, B, and C in FIG. Under isostatic pressure at 60%, the powder is enclosed in a rubber mold of diameter D and length L using the internal method and pressure-molded.
0.74D~0.79D, length is 0.74L~0.79L.

Furthermore, if the apparent density is very small, the 7th
As shown by D in the figure, the volume shrinkage rate is as high as 90%, and the diameter is 0.46D and 0.46L.

However, since the molded container is determined by the original dimensions D and L, that is, the internal dimensions D and L of the rubber mold; As a result, the entire device including the upper cover, lower cover, press frame, etc. becomes larger and more expensive. In this case, the rubber mold is also greatly deformed under high pressure, so the life of the rubber mold is greatly reduced. ;Since the container efficiency decreases, the operating rate of the high-pressure pump increases significantly, increasing the need for maintenance. ;A large diameter high pressure seal is required. ;Also, when using one CIP device to pressure mold multiple types of compacts, such as large compacts that are pressed at low pressure and small compacts that are pressurized at high pressure, the CIP device will adjust the maximum diameter and maximum molding pressure of the compacts. Because it depends on
It becomes a very wasteful device.

In addition, in conventional example 2, although one hydraulic device and press frame can be shared for multiple molded containers, it is not possible to pressure mold each container at different pressures, and there is Since a plurality of molded containers are arranged side by side in the horizontal direction, the center of the press frame and the center of each container do not necessarily match, and the press axial force that acts during pressure molding is ultimately applied to the press frame. Therefore, there was a problem that the axial force bearing balance of the press frame was disrupted due to the above-mentioned center mismatch.

On the other hand, if an attempt is made to ensure sufficient proof strength even in the event of the above-mentioned imbalance, the size of the press frame will be increased.

Although the present invention shares one hydraulic device and press frame, it is possible to perform pressure molding at different pressures corresponding to a plurality of molded containers with different molding pressures and container inner diameters, and moreover, it is possible to perform pressure molding at different pressures corresponding to a plurality of molded containers with different molding pressures and container inner diameters. The purpose is to provide a CIP device that guarantees balance.

(Means for Solving the Problems) The present invention includes a plurality of molded containers, one hydraulic device that supplies pressure medium to each of the molded containers, depressurizes and drains the water, and one press that takes charge of press axial force. In order to achieve the above-mentioned purpose in a wet cold isostatic pressurizing device comprising a frame,
The following technical measures have been taken:

That is, in the present invention, the molded container includes a plurality of molded containers having different molding pressures and container inner diameters, and the molding pressure is lower as the container inner diameter becomes larger, and the hydraulic device has different molded containers corresponding to the respective molded containers. The press frame is provided with a switching means for supplying a pressure medium under pressure, and the press frame is configured to supply a pressure medium to the plurality of molded containers.
It is characterized by being provided so that it can be individually engaged and detached.

(Function) According to the present invention, as shown in FIGS. 1 and 2,
With the press frame 20 retracted toward the high-pressure side molding container 12 by its moving cylinder 22, the low-pressure side upper lid 13 is opened, and the large-diameter rubber mold 18 pre-filled with powder 17 is inserted into the low-pressure side molding container 11. Attach to.

Next, the upper end side of the molding container 11 is closed with the low-pressure side upper lid 13, the press frame 20 is moved to the low-pressure side to take a position that can take the press axial force, and then preforming is performed by applying pressure with the low-pressure pump 35. Let's do it.

After the preforming is completed, the pressure medium in the low pressure side molding container 11 is depressurized and drained, the rubber mold 18 is taken out from the low pressure side molding container 11, and the preformed body 17A in the rubber mold 18 is transferred to the small diameter rubber mold 19. .

Next, the small-diameter rubber mold 19 is attached to the high-pressure side molding container 12 in the same manner as the low-pressure side described above, and the high-pressure pump 36 presses and molds it to the final molding pressure. To,
A predetermined molded body is obtained.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 and 2.

In FIG. 2, a low-pressure side molded container 11 and a high-pressure side molded container 12 are installed side by side on a pedestal 10, and the inner diameter of the former container 11 is larger than the inner diameter of the latter container 12.

The molded container 12 has a two-layer shrink-fit structure of a thick-walled cylinder, and compressive stress, which is advantageous in terms of strength, is generated in the inner cylinder where the maximum stress occurs by shrink-fitting, and the container 1
The structure is designed to prevent high tensile stress from occurring when a molding pressure (internal pressure) corresponding to 2 is applied, and to improve fatigue strength.

Upper and lower lids 13, 13A, 14, and 14A having seals 13B, 13C, 14B, and 14C are removably fitted into the upper and lower openings of the molded containers 11 and 12, respectively. They can be inserted into the upper openings of the molding containers 11 and 12 by lifting cylinder devices 15 and 16, respectively, and the rubber mold 1 in which the powder 17 is sealed is inserted into the upper openings of the molding containers 11 and 12, respectively.
8 and 19 can be inserted and removed from each upper opening.

The press frame 20, which carries the press axial force acting on each molded container 11, 12,
In this illustrated example, a press frame 20 having a laminated plate structure and a portal shape is mounted on a traveling carriage 21. The upper and lower lids of both containers 11 and 12 are moved through the expansion and contraction of a cylinder device 22. 13,13A,1
4 and 14A are exemplified as those that can be freely engaged and disengaged.

In addition, the press frame 20 is of the traveling type, as well as
It is also possible to use a so-called swiveling type device, in which a swiveling shaft is provided on the side of the pedestal 10, and the container 11 and 12 can be freely engaged and detached from each other by being swiveled about this swiveling shaft.

An air vent valve 2 is provided on each of the upper lids 13 and 14.
The lower lids 13A, 14A have air vent ports 23A, 24A connected to the lower lids 3, 24, respectively, and pressure medium ports 26, 27 connected to the hydraulic device 25, respectively.

Referring to FIG. 1, there is schematically shown an example of a hydraulic device 25, ie an operating circuit for supplying, pressurizing, depressurizing, draining, etc. the pressure medium.

In FIG. 1, the pressure medium 29 in the pressure medium tank 28 is sent by a water supply pump 30 to a supply circuit 32 having a water supply/drainage switching valve 31, and branch liquid feeding circuits 32, 33 after the water supply/drainage switching valve 31 are each provided with a switching valve 32A. , 33A are provided so that liquid can be sent to the pressure medium port 26 of the low-pressure side molded container 11 and the pressure medium port 27 of the high-pressure side molded container 12, respectively.

A low pressure pump 35 is provided in the middle of the supply circuit 32 via a bypass circuit 34, and therefore,
For example, 150
The pressure of the pressure medium 29 can be increased to about Kg·f/cm ² .

The increased pressure can be detected by the sensor 32B. By keeping the pressure medium 29 from the water supply pump 30 in communication with the high-pressure side molded container 12 by blocking the switching valve 32A and communicating the switching valve 33A. , the liquid is sent from the pressure medium port 27 via the branched liquid feeding circuit 33, and then the branched liquid feeding circuit 33 and the water supply pump 30
A high pressure pump or pressure intensifier 3 installed between the discharge side of
6 to a predetermined molding pressure, e.g. 1000Kg・f/cm ²
It is possible to increase the pressure up to ~2000Kg・f/cm ² .

That is, in the pressure intensifier 36, a parent piston 36B is fitted into a parent cylinder 36A, a pair of piston rams 36C having a smaller diameter protrude from the parent piston 36B, and fitted into the child cylinder 36D, and a pair of piston rams 36C are inserted into the child cylinder 36D side. A check valve 36E is provided, and the main piston 36B is slid to either side by hydraulic pressure to generate a load of 1000 to 2000 kg depending on the area difference.
The pressure can be increased to f/cm ² and the liquid is simultaneously sent to the other child cylinder 36D. The pressure at this time can be detected by the sensor 33B.

Further, the drain side circuit 37 of the water supply/drainage switching valve 31 is equipped with a drain valve 38 and a drain pump 39, and after a predetermined pressure molding is performed in the molding containers 11, 12, the pressure medium 29 is recovered into the tank 28. Furthermore, the water pressure device 25 is equipped with the above-mentioned pressure boost pump means, that is, two pumps 35 and a pressure booster 36 in this example, in which the discharge pressure and discharge amount are different, and the lower the pressure, the greater the discharge amount. In addition, a primary pressure reducing valve 40 and a secondary pressure reducing valve 41 to prevent molded products from cracking during pressure reduction.
is provided, and both the primary pressure reduction and the secondary pressure reduction are reduced by a throttle valve, and the pressure reduction speed can be changed depending on the throttle condition, and when the pressure is reduced to a preset pressure by the primary pressure reduction valve 40, the pressure is shifted to the secondary pressure reduction. has been done.

Therefore, in the embodiments of FIGS. 1 and 2,
The rubber mold 18 containing the powder 17 is attached to the low-pressure side molded container 11, air is removed, and the press frame 20 is engaged with the upper and lower lids 13, 13A. Preliminary pressure molding is then performed.

After pressure molding, the rubber mold 18 from which the pressure medium has been drained is taken out, and the preformed product 17A is charged into the high-pressure side rubber mold 19.

In this case, if the rubber mold is easily deformable, such as latex rubber, there is no need to change the rubber mold.

The rubber mold 19 with the preform is installed in the high-pressure side molding container 12, the press frame 20 is engaged,
After going through the necessary steps such as air removal, the molded container 1
By supplying a pressure medium 29 into the inside of 2 and raising the pressure to the final molding pressure, isotropic pressure molding is performed here, and a predetermined molded product is obtained by passing through a pressure reduction step and a drainage step.

Furthermore, on the high pressure side, the powder 17 is placed in the rubber mold 19.
Of course, it is also possible to encapsulate the material and press-form it independently.

FIG. 3 shows another embodiment of the present invention, in which a low-pressure side molded container 11 and a high-pressure side molded container 12 arranged side by side are made slidable together with upper and lower lids on a pedestal 10 by a moving cylinder 42, and a press frame 20 is fixed in place, and molded containers 11 and 12 are attached to this press frame 20 so as to be freely switchable.

In the embodiment shown in FIG. 3, a pressure intensifier 36 is further provided in the upper part of the press frame 20 as a piston pressurizing structure.

That is, the press cylinder 43 is attached to the press frame 20, a piston 44 that fits therein is provided, and a small diameter piston portion 45 is provided on the upper lid side.

Therefore, when the pressure medium from the water supply pump 30 shown in FIG.
For example, 6000-10000Kg・f/cm ² due to the area difference between
It is possible to boost the pressure up to

In addition, in the case of the low pressure side molded container 11, slide it to the piston 44 position, and
With the lower end of the press frame 20 engaged with the upper lid 13, the press frame 20 carries the press axial force through hydraulic pressure.

The rest of the structure is the same as the embodiment shown in FIG.

FIG. 4 shows another embodiment of the present invention, in which the upper lid can also be used for both the low-pressure side molded container 11 and the high-pressure side molded container 12. The large diameter portion 44 and the latter container 1
2 is formed into a two-stage structure, and each seal 44A, 45A is also provided, and the upper lid lifting cylinder device 46 is connected to both molded containers 1.
It is provided between 1 and 12 so that it can not only be raised and lowered but also rotated freely, and the rest of the configuration is the same as in FIGS. 1 and 2. Note that when three or more molded containers are provided, it is clear that a stepped structure that matches the inner diameter of each container is used.

In addition, in the above example, two molded containers were illustrated, but this may be two or more, and in short,
Any material that can perform low-pressure molding and high-pressure molding individually or sequentially from preforming (low pressure) to final molding by sharing a press frame and a hydraulic device may be used.

(Effect of the invention) According to the invention, the powders A, B, and
If the low pressure side in C and D is 150Kg・f/cm ² , the diameter will be as follows.

(Low pressure side shrinkage rate) x High pressure side shrinkage rate = (Overall shrinkage rate) A0.84×0.94≒0.79D B0.82×0.87≒0.71D C0.80×0.90≒0.71D D0.58×0.80≒0.46D , compared to conventional molding from low to high pressure in one molding container, it requires less strength on the high pressure side.
It becomes 0.33 to 0.71 times, which makes it possible to miniaturize the device.

Specific examples of the effects of the present invention will be described below. The most common powder C (see Figure 7, volumetric shrinkage rate is 55% at 200Kgf/cm ² and 65% at 1500Kgf/cm ² )
A block with a cylindrical diameter (φ950mm after CIP) is
Considering the case of molding at 1500Kgf/ ^cm2 , if the pressure is molded to the final pressure in one container as in the conventional method, the filling diameter of the powder is ^950/3 √1-0.65≒1350, so the rubber Considering the dimensions of the mold,
The inner diameter of the CIP container must be at least 1500mm. However, the low pressure side container (200Kgf/cm ² ) of one example of the present invention
After primary forming, high pressure side container (1500Kgf/cm ² )
When performing secondary molding at 200Kgf/ ^cm2 ,
Since the diameter is 1350× ³ √1−0.55≒1030 mm, it is sufficient that the inner diameter of the high-pressure container for secondary forming is 1200 mm. Generally, the inner and outer diameter ratio of a 1500Kgf/ ^cm2 container is approximately
1.5, and that of 200Kgf/cm ² is less than 1.2,
The press frame for the high-pressure side can be used as is on the low-pressure side, and by sharing the pressurization and depressurization equipment, the desired effect can be achieved simply by adding a low-pressure container to the high-pressure CIP. Furthermore, if we show the effect in concrete numbers,
Since the axial force of the device is proportional to the square of the inner diameter of the container, in the case of the device of the present invention, (1200/1500) ² =
0.64 times, which is less than 1/2 when compared with the equipment weight (the press frame, which accounts for about 1/2 of the equipment weight, has a gate-shaped structure, so the axial force x frontage [proportional to the container inner diameter]) is 3 times the container inner diameter ratio. It becomes effective by multiplying).
Even when compared in terms of equipment prices, it is approximately 0.6 times as expensive.
Furthermore, as mentioned above, the fact that the larger the inner diameter of the container is, the lower the molding pressure is is not just a matter of design, but has important implications for the CIP molding process, and should be considered for each target powder in conjunction with the number of molding stages (number of containers).・It is determined.

The present invention is particularly effective when the proportion of large products in the total production volume is low, since the initial investment amount can be reduced, and because the container is small, regular size molding can be performed at low running costs and high cycles. .

Furthermore, since the shrinkage rate on the high pressure side is reduced, deformation of the rubber mold can be reduced, and the life of the rubber mold can be improved.

Appropriate container diameters and pressures can be combined to minimize equipment capacity.

Since the press frame can be individually engaged and detached from multiple molded containers, the press axial force that acts during pressure molding must be borne by aligning the center of the molded container with the center of the frame. becomes possible,
The frame strength and the like can be made appropriate, and the press frame can be downsized without any problem, and the degree of freedom in designing the entire device can be expanded and the cost can be reduced.

Since the present invention has the above-mentioned effects, it has great advantages when put to practical use as a wet cold isostatic pressure device.

[Brief explanation of drawings]

The drawings show the present invention and a conventional example. Fig. 1 is a conceptual diagram of the overall structure of the embodiment of the present invention, Fig. 2 is an elevational sectional view of the molded container portion, and Fig. 3 is an elevational view of the second embodiment. 4 is an elevational sectional view of the third embodiment, FIG. 5 is an elevational sectional view showing the steps of the conventional example, and FIG. 6 is a concept of the overall configuration of the conventional example. 7 are graphs showing the compressibility properties of powder in terms of the relationship between molding pressure and volumetric shrinkage. 11...Low pressure side molded container, 12...High pressure side molded container, 17...Powder, 17A...Preformed product, 1
8, 19...Rubber mold, 20...Press frame,
25...Hydraulic device, 30...Water pump, 32
A, 32B...Switching valve, 35...Low pressure pump, 3
6...High pressure pump (pressure booster).

Claims (1)

[Claims] 1. A press frame that is equipped with a plurality of molded containers, one hydraulic device that supplies pressure medium to each of the molded containers, depressurizes it, and drains water, and one press frame that takes charge of press axial force. In the wet cold isostatic pressurizing device, the molded containers include a plurality of containers having different molding pressures and container inner diameters, and in which the molding pressure is lower as the container inner diameter becomes larger, and the hydraulic device is configured to control each molded container. The wet cold isostatic pressurizing method is characterized in that the press frame is provided with switching means for supplying pressure media at different pressures corresponding to the above, and the press frame is provided in a manner that can be freely engaged with and detached from the plurality of molded containers. Pressure device.