JPS6345920B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure increasing/decreasing device in a cold isostatic pressurizing device.

Cold isostatic pressing equipment is attracting attention in the fields of powder metallurgy and ceramics.

This is because, since it is an isotropic pressing method, the density of the molded product is uniform and high, which not only approaches the true density but also improves mechanical properties.

By the way, in the case of a cold isostatic pressurization device, pressure increase and pressure reduction are necessary, and pressure increase (pressure increase) is usually performed using a low-pressure pump with a large discharge volume in the low-pressure region where the compressibility of powder is large. The pressure is increased by two pumps so that a high pressure pump with a small discharge amount is used in a high pressure region with a small compression ratio.

In addition, it is desirable to perform the depressurization separately for the primary and secondary parts to prevent cracking of the molded product at that time.

From this point of view, as disclosed in Japanese Patent Application Laid-Open No. 57-109597, in addition to controlling the decompression speed by throttling the valve, the applicant has decided to use water pressure/hydraulic pressure for materials that are prone to cracking, such as ceramics. We proposed a counter cylinder type pressure reducing device, which has been well received.

However, in the conventional example, a secondary pressure reducing device is used as an option in addition to a pressure intensifier, a pump, etc., and since it is a servo valve type, it is very expensive.

Further, since the secondary pressure reducing cylinder requires a capacity for expansion of the pressure medium in one stroke, the entire device tends to be large.

Therefore, in the present invention, in a cold isostatic pressing apparatus equipped with a reciprocating pressure intensifier, by using the pressure intensifier as a positive displacement pressure reducing device,
The purpose is to enable the decompression pattern to be changed arbitrarily. In addition to the above objects, the present invention can perform rapid pressurization during pressure increase by connecting an intermediate pressure (depressurization) cylinder to the pressure increase machine, and
It is an object of the present invention to make it possible to arbitrarily change the pressure reduction pattern by using a positive displacement type pressure reduction method in a low pressure region during pressure reduction.

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 3 show an embodiment according to the first feature of the invention, and FIGS. 4 and 5 show an embodiment according to the second feature of the invention.

1 to 3, powder or other material to be molded 2 is sealed in a high-pressure molding container 1 via a rubber bag or the like, and a pressure medium is supplied from a pressure medium supply port 3 formed in the container 1. It is said that pressure molding is possible in an isodirectional manner.

Reference numeral 4 denotes a reciprocating pressure intensifier, which includes a double-action hydraulic cylinder mechanism 5 and pressure medium cylinder mechanisms 8 and 9 attached to both sides of the hydraulic cylinder mechanism 5 via columns 6 and 7.

The hydraulic cylinder mechanism 5 has two ports 10, 1
1 to the cylinder tube 12 with the piston 13
are fitted in an oil-tight manner, and a pair of plungers 14 and 15 are coaxially connected to the piston 13.
It is a double action type that can be reciprocated by selectively supplying hydraulic pressure from 0 and 11.

Reference numeral 16 denotes a hydraulic pump, and the hydraulic pressure from the pump 16 is applied to each port 10 through a check valve 17, a switching solenoid valve 18, and a switching valve mechanism 19 represented by a solenoid valve through check valves 20 and 21, respectively. , 11 can be alternatively fed.

Each of the pressure medium cylinder mechanisms 8 and 9 consists of cylinder tubes 22 and 23 and plungers 24 and 25 fitted therein.
5 is connected to the end of each plunger 14, 15 of the corresponding hydraulic cylinder mechanism 5,
Furthermore, ports 22A and 23A formed in each cylinder tube 22 and 23 are connected to check valve 2, respectively.
Pressure medium (water) tanks 28, 29 via 6, 27
is communicated with.

Although the cylinder volumes of the pressure medium cylinder mechanisms 8 and 9 are the same, the hydraulic cylinder mechanism 5
The volume is smaller than that of the cylinder.

The pressure medium cylinder mechanisms 8, 9 are connected to the supply port 3 of the container 1 via a circuit 32 having check valves 30, 31, respectively, and the check valve 26 is connected to the check valve 31, and the check valve 27 is connected to the check valve 30. are short-circuited via short circuits 33A and 33B, respectively.

A pressure medium pressure detector 34 is provided in the circuit 32 and connected to a pressure indicator 37 via an amplifier 35 and a distributor 36.

Reference numeral 38 denotes a pressure setting device, which is used to set the depressurizing pressure medium pressure in advance, and compares the set pressure with the pressure medium pressure to set the switching solenoid valve 40 to the switching valve mechanism 19 side via the amplifier 39. It is configured to receive feedback to an electromagnetic relief valve 41 provided therewith.

That is, the relationship between pressure medium pressure P ₁ and hydraulic pressure P ₂ is, if packing resistance is ignored, from the pressure intensifier ratio K,
P ₁ = KP ₂ .

Using this relationship, the hydraulic pressure P ₂ is determined by the electromagnetic relief valve 4.
1, the pressure medium pressure _P1 can be controlled by program control.

In order to improve the precision of program control, the pressure medium pressure _P1 is detected by the detector 34, compared with a preset pressure, and feedback is applied to the electromagnetic relief valve 41 to compensate for the packing resistance. Therefore, back pressure is applied to the hydraulic cylinder mechanism 5.

Additionally, in FIGS. 1 to 3, 42 is a relief valve, which is provided between the switching solenoid valve 18 and the switching valve mechanism 19.

Reference numeral 43 designates an electromagnetic switching valve, which is provided in a circuit having a pressure accumulator 44 between the respective short circuits 33A, 33B and the discharge side of the check valve 17.

Reference numeral 45 indicates an ultra-high pressure throttle valve, and reference numeral 46 indicates an ultra-high pressure switching valve.

Next, the effect will be explained.

Figure 1 shows when the pressure is increased, and the solenoid switching valve 1
8, 43, and 40 are all in a demagnetized state, and the switching valve mechanism 19 is alternated as shown in the figure, so that the pressure oil from the hydraulic pump 16 is transferred to the left cylinder chamber of the hydraulic cylinder mechanism 5 through the port 11. The liquid is delivered.

Therefore, the piston 13 is slid to the right in the figure and pushes the plunger 25 of the pressure medium cylinder mechanism 9 through the plunger 15, where high pressure pressure medium is supplied by pushing open the check valve 31. The material 2 to be molded is sent back to the high-pressure molding container 1 through the port 3, and the molded material 2 sealed in the container 1 is isostatically pressed. On the other hand, as a result of this operation, the plunger 24 of the other pressure medium cylinder mechanism 9 is brought along with it, so that the cylinder chamber becomes so-called negative pressure, and the check valve 26 is pushed open to suck the pressure medium into the cylinder chamber. -ing

2 and 3 respectively show the time of pressure reduction. First, in FIG. 2, the electromagnetic switching valves 18 and 40 are excited, and the switching valve mechanism 19 and the electromagnetic switching valve 4 are energized.
By alternating groups 3 as shown in the figure,
Pressure oil from the hydraulic pump 16 is sent to the port 11 via the relief valve 42, causing the piston 13 to slide to the left.

As a result, the pressure medium cylinder mechanism 9 performs a suction action, and conversely, the pressure medium cylinder mechanism 8 performs a discharge action, so that the pressure of the pressure medium in the high-pressure molded container 1 is reduced.

The reduced pressure state in FIG. 3 shows the reduced pressure position when the hydraulic piston 13 of the hydraulic cylinder mechanism 5 is slid toward the right in the figure, and at this time, the pressure medium cylinder mechanism 8 is in the suction action. The pressure medium cylinder mechanism 9 performs the discharge action.

In either decompression pattern, the detector 34
By detecting the molding pressure and comparing it with the value preset by the setting device 38, and giving feedback to the electromagnetic relief valve 41 to adjust the set pressure,
This can be done freely by adjusting the speed of each plunger 24, 25.

4 and 5 are embodiments according to the second feature of the present invention, and since most of the main parts thereof are generally the same as the above-mentioned configuration, the common parts are indicated by common symbols, and the differences will be explained below. I will explain each point in detail.

One plunger 15 of the hydraulic cylinder mechanism 5
A connecting body 47 is attached to the plunger 25 of the corresponding pressure medium cylinder mechanism 9, and a plunger 51 of the pressure reducing cylinder mechanism 50 is connected to the connecting body 47 via a column 48 and a connecting body 49 so as to be freely interlocked. The plunger 51 is slidably inserted into a cylinder tube 52 having a port 52A.

The port 52A is communicated with the pressure medium tank 53 via a check valve 54, and is also communicated with the circuit 32 via a safety relief valve 55 and a switching valve 56.

Next, the operation of the configuration shown in FIGS. 4 and 5 will be explained.

First, FIG. 4 shows a state of pressure increase (maximum pressure increase). At the initial stage of pressure increase, the left side of the electromagnetic switching valve 43 is energized, the electromagnetic switching valves 18 and 40 are demagnetized, and the switching valve mechanism 19 is activated. By alternating the positions, rapid pressure increase can be achieved using the pressure reduction cylinder mechanism 50. This is because the cross-sectional area of the plunger 51 of the cylinder mechanism 50 is larger than the cross-sectional area of the plunger 25 of the pressure medium cylinder mechanism 9.

After the rapid pressure increase is carried out, the pressure oil from the hydraulic pump 16 is sent from the port 10 in the same way as shown in FIG. becomes high pressure, check valve 3
1 is pushed open and a high-pressure medium is supplied to the container 1 from the supply port 3, and the material to be molded 2 is subjected to isostatic pressure in the container 1 in the same direction. At this time, the solenoid valve 43 switching check valve 54 shown in FIG.
It is connected with no load.

For primary pressure reduction, the ultra-high pressure switching valve 46 is opened and the pressure reduction speed is adjusted by the opening degree of the throttle valve 45.For secondary pressure reduction, the solenoid valve 18, as shown in FIG. 43 and 40 are excited, the switching valve mechanism 19 is excited, the ultra-high pressure switching valve 56 is opened, and the pressure medium in the container 1 is introduced into the cylinder tube 52 to reduce the pressure. This is done by comparing the signals from the setter 38 and changing the set pressure of the electromagnetic relief valve 41, and this point is the same as in the previous example.

Note that the pressure medium cylinder mechanisms 8 and 9 are used during pressure increase, and are free during secondary pressure reduction.

The present invention is as described above, and as a pressure increasing/decreasing device for a cold isostatic pressurizing device, the pressure is reduced by a pair of pressure medium cylinder mechanisms that are operated in conjunction with the reciprocating movement of a hydraulic cylinder mechanism. can be done, which is
The device can be made more compact than the conventional secondary pressure reducing mechanism using an optional hydraulic-hydraulic opposed cylinder. It can also be used as a pressure booster, and can be set to reduce the pressure from the highest pressure.Since the comparison signal between the pressure medium pressure and the preset set pressure is fed back via the electromagnetic relief valve, it can be used as a servo booster. Unlike valves, there are fewer problems caused by dirt, and maintenance can be improved.

Furthermore, according to the second feature of the present invention, the pressure reduction cylinder mechanism enables high-speed pressure increase for one stroke, and the discharge amount can be increased to about 10 times the normal amount.

[Brief explanation of the drawing]

The drawings show embodiments of the invention and are shown in FIGS. 1 to 3.
The drawings are an example of the first feature of the present invention, in which Fig. 1 is an overall view showing the operating state during pressure increase, Figs. 2 and 3 are general views showing the operating state during pressure reduction, and Figs. is an example of the second feature of the present invention, and FIG.
FIG. 5 is an overall view showing the operating state during pressure reduction. 1... High-pressure molded container, 2... Material to be molded, 3...
...Pressure medium supply port, 5...Hydraulic cylinder mechanism, 8, 9
... Pressure medium cylinder mechanism, 14, 15 ... Each plunger of the hydraulic cylinder mechanism, 19 ... Switching valve mechanism, 26, 27, 30, 31 ... Check valve, 2
8, 29...pressure medium tank, 32...circuit, 41...
...Relief valve mechanism, 50...Reducing cylinder mechanism.

Claims (1)

[Claims] 1. Cold isostatic pressurization in which powder or other material to be molded 2 sealed in a high-pressure molding container 1 is molded by isodirectional pressurization of a hydrostatic medium within the container 1 In the device, a double-action hydraulic cylinder mechanism 5, which can be reciprocated by switching a switching valve mechanism 19, has cylinders on both sides of the double-action hydraulic cylinder mechanism 5, which are connected to pressure medium tanks 28 and 29 via check valves 26 and 27, respectively. Cylinder mechanisms 8 and 9 are provided, and the pressure medium cylinder mechanism 8,
Each of the plungers 14 and 15 of the hydraulic cylinder mechanism 5 is connected to each of the pressure medium cylinder mechanisms 8 and 9 via a circuit 32 to the high-pressure molded container 1 through check valves 30 and 31, respectively. The plungers 24 and 25 are interlocked so that when one increases the pressure, the other sucks pressure medium, and furthermore, the circuit pressure from the pressure medium pressure detector 34 and the preset pressure reduction medium pressure are connected to each other. A pressure increasing/decreasing device in a cold isostatic pressure pressurizing device, characterized in that the pressure is comparatively controlled and fed back to a relief valve mechanism 41 provided on the switching valve mechanism 19 side. 2. In a cold isostatic pressurizing device in which powder or other material to be molded 2 sealed in a high-pressure molding container 1 is molded by isodirectional pressurization of a hydrostatic medium within the container 1, a switching valve mechanism is used. Pressure medium cylinder mechanisms 8 and 9 are connected to pressure medium tanks 28 and 29 via check valves 26 and 27, respectively, on both sides of the double-action hydraulic cylinder mechanism 5, which can be reciprocated by switching 19. provided, the pressure medium cylinder mechanism 8,
Each of the plungers 14 and 15 of the hydraulic cylinder mechanism 5 is connected to each of the pressure medium cylinder mechanisms 8 and 9 via a circuit 32 to the high-pressure molded container 1 through check valves 30 and 31, respectively. The plungers 24 and 25 are interlocked so that when one increases the pressure, the other sucks pressure medium, and furthermore, one plunger 15 of the hydraulic cylinder mechanism 5 and a pressure medium cylinder on the side of the plunger 15 are connected to each other. A pressure reduction cylinder mechanism 50 is interlocked and connected to each of the plungers 25 of the mechanism 9, and the circuit pressure detected by the pressure medium pressure detector 34 and a preset pressure reduction pressure are compared and controlled to control the switching valve mechanism 19. A pressure increasing/decreasing device in a cold isostatic pressure pressurizing device, characterized in that the pressure is fed back to a relief valve mechanism 41 provided on the side.