JPH1024396A - Secondary pressure reducing device for static pressurizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable general applicability of a standardized device without affecting capacity change of a static pressuring device so as to reduce device's cost, to simplify device's maintenance and to reduce device's space. SOLUTION: This device in which after primary pressure reducing is executed by a primary pressure reducing circuit and successively secondary pressure reducing is executed, is constituted of a pump circuit in which a stop valve 13 for feed/drain and variable discharge quantity type fluid pump 1 arranged in series are connected in parallel to the primary pressure reducing circuit, a secondary pressure reducing/throttling circuit in which a stop valve 5 for secondary pressure reducing and a mechanical throttling means 6 with fixing throttling/opening arranged in series are connected in parallel to a secondary pressure reducing/throttling circuit and a pressure reducing control means which executes the operation control including discharge quantity adjustment of the fluid pump 1 and the opening/closing control of stop valve 13 for feed/drain and a stop valve 5 for secondary pressure reducing based on the pressure reducing program set beforehand.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary depressurizing device in a hydrostatic pressing device used for powder molding and the like, and more particularly, to a secondary depressurizing device which is performed following a primary depressurizing process after hydrostatic pressing. The present invention relates to an improved proposal of a decompression means.

[0002]

2. Description of the Related Art A depressurizing means after pressure molding in a cold isostatic press is roughly classified into a depressurizing method using a depressurizing cylinder represented by Japanese Patent Publication No. 59-18159. And a pressure reducing method using a throttle valve. The latter pressure-reducing method using a throttle valve, the pressure value of the high-pressure molding container,
It is difficult to set an arbitrary decompression pattern because it depends on the amount of the powder to be molded, etc., and the throttle valve is worn by the erosion mechanism itself during use, causing the throttle valve opening to change. However, there is a drawback that the reproducibility is lost and stable control cannot be performed, and the use thereof has been avoided. These disadvantages are particularly serious in pressure molding, such as in the case of powder molding, which causes a sudden change in pressure and leads to breakage of the powder molded product. In other words, the reason why the pressure reduction at 200 kgf / cm ² or less, in which the specification of the pressure reduction pattern and the precision and reproducibility are particularly required, is considered fatal.

[0003] The former type of decompression system using a decompression cylinder has been made in order to solve the above-mentioned drawbacks, and in summary, it controls the movement of a piston of a decompression cylinder connected to a high-pressure molding vessel (pressure vessel). By doing so, pressure control during pressure reduction is performed with high accuracy. That is, while comparing the pressure of the pressure vessel with a preset pressure reducing pattern, if the pressure of the pressure vessel is low, the piston of the pressure reducing cylinder is pushed in to increase the pressure, and if the pressure of the pressure vessel is high, the piston of the pressure reducing cylinder is pushed down. I try to reduce the pressure by pulling. In addition, since there is no portion where the fluid flows violently, there is an advantage that wear due to erosion or the like does not occur.

[0004]

In the above-described decompression system using a decompression cylinder, if the hydrostatic pressure pressurization device is increased in size due to an increase in the capacity of the pressure vessel, the capacity of the decompression cylinder is also increased. The problem is that it is economically disadvantageous as a result of rising costs. A hydraulic servo valve is used to control the pressure reducing cylinder.However, to use the servo valve with high responsiveness, it is necessary to increase the cleanliness of the hydraulic oil. Another problem is that the maintenance cost increases. Furthermore, servo valves and filter accessories are expensive,
It is economically disadvantageous. In addition, a large space for installing the pressure reducing cylinder is required, and disadvantages cannot be avoided from the viewpoint of space saving.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a hydraulic medium which is used for hydrostatic pressurization without requiring a pressure reducing cylinder. By realizing a decompression device with a simplified fluid pressure circuit, it is possible to use a standardized device without being affected by the change in capacity of the hydrostatic pressure press device and reduce the cost of the device. Another object of the present invention is to provide a secondary depressurizing device in a hydrostatic pressurizing device capable of simplifying maintenance and saving space.

[0006]

The present invention has the following configuration to achieve the above object. That is, the present invention encapsulates the material to be molded in a high-pressure molding container,
In a hydrostatic pressurizing apparatus for press-forming a material to be formed by hydrostatic pressure pressurization in the container, a primary depressurization was performed by a primary depressurization circuit having a mechanical drawing means 14 after the press-forming. A supply / discharge opening / closing valve 13 and a variable discharge type hydraulic medium pump 1
Are connected in series to the primary pressure reducing circuit, and a secondary pressure reducing opening / closing valve 5 and a mechanical throttle means 6 having a fixed throttle opening are connected in series. A secondary pressure reducing throttle circuit connected in parallel to the hydraulic medium pump 1,
A pressure reduction control means for performing operation control including adjustment of the discharge amount of the hydraulic medium pump 1 and opening / closing of the supply / discharge on / off valve 13 and the secondary pressure reduction on / off valve 5 based on a preset pressure reduction program; The secondary depressurization on-off valve 5 is opened when the primary decompression is completed, and the hydraulic pressure medium pump 1 opens the secondary decompression on-off valve 5
The discharge amount is adjusted so that the discharge pressure rises up to the secondary pressure reduction start pressure based on the pressure reduction program, and then the discharge amount is adjusted so as to gradually reduce the pressure. The valve is opened when the discharge pressure of the pressure-medium pump 1 reaches the secondary pressure-reduction start pressure.
The throttle opening is set so that the hydraulic medium pump 1 can increase the discharge pressure to the secondary pressure reduction start pressure at an intermediate discharge amount less than the maximum discharge amount. It is a secondary decompression device.

The present invention also provides a hydrostatic pressurizing apparatus for sealing a material to be molded in a high-pressure molding container and performing pressure molding of the material to be molded by hydrostatic pressure in the container. An apparatus for performing a secondary pressure reduction after a primary pressure reduction is performed by a primary pressure reduction circuit provided with a mechanical throttle means 14, comprising a supply / discharge on-off valve 13 and a constant discharge type hydraulic medium pump. 1 is connected in series with the primary pressure reducing circuit through a series, and a secondary pressure reducing on-off valve 5 and a mechanical throttle means 16 capable of adjusting the throttle opening are connected in series. A secondary pressure reducing throttle circuit connected in parallel to the hydraulic medium pump 1; an operation control of the hydraulic medium pump 1; a throttle opening adjustment of the mechanical throttle means 16; Opening / closing control of the next pressure reducing on-off valve 5 is performed based on a preset pressure reducing program. The secondary pressure reducing on-off valve 5 is opened when the primary pressure reduction is completed, and the hydraulic medium pump 1 is in front of and after the secondary pressure reducing on-off valve 5 is opened. The supply / discharge on / off valve 13 is opened when the discharge pressure of the hydraulic medium pump 1 reaches the secondary pressure-reduction start pressure, and the mechanical restrictor 16 operates based on the pressure-reduction program. A secondary depressurizing device in a hydrostatic pressurizing device, wherein the throttle opening is adjusted so that the discharge pressure of the pressure medium pump 1 increases to a secondary depressurization start pressure and then gradually decompresses.

The present invention also provides a hydrostatic pressurizing apparatus for sealing a material to be molded in a high-pressure molding container and performing pressure molding of the material by hydrostatic pressure in the container. This is a device for performing secondary pressure reduction after primary pressure reduction is performed by a primary pressure reduction circuit provided with a mechanical throttle means 14, and a variable discharge type hydraulic medium pump 1 is connected in series. The hydraulic medium pump includes a pump circuit connected in parallel to the primary pressure reducing circuit, a secondary pressure reducing on-off valve 5, and a mechanical throttle means 16 capable of adjusting the throttle opening in series. 1, a secondary pressure reducing throttle circuit connected in parallel with 1, an operation control including a discharge amount adjustment of the hydraulic medium pump 1, a throttle opening degree adjustment of the mechanical throttle means 16, a supply / discharge opening / closing valve 13 and a secondary pressure reducing Opening / closing control of the on-off valve 5 is performed based on a preset pressure reducing program. The secondary pressure reducing on-off valve 5 is opened when the primary pressure reduction is completed, and the hydraulic medium pump 1 is in front of and after the secondary pressure reducing on-off valve 5 is opened. The supply / discharge opening / closing valve 13 is opened when the discharge pressure of the hydraulic medium pump 1 reaches the secondary pressure reduction start pressure, and at least the hydraulic medium pump 1 and the mechanical throttle means 16 are opened. On the other hand, at least one of the discharge amount and the throttle opening is adjusted so that the discharge pressure of the hydraulic medium pump 1 increases to the secondary pressure reduction start pressure and then gradually decreases based on the pressure reduction program. This is a secondary decompression device in the hydrostatic pressurization device.

According to the present invention, in each of the above-described secondary pressure reducing devices, the supply / discharge on / off valve 13 in the pump circuit allows the flow of the liquid supply from the hydraulic medium pump 1 side, and allows the flow from the high pressure forming container side. It comprises a pilot operated check valve provided so as to prevent the flow of drainage, and the hydraulic medium pump 1 is a pressure forming pump which is also used for secondary pressure reduction.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. A molding material such as a powder group is sealed in a processing chamber 11 in a high-pressure molding container 10 realized by a pressure vessel sealed by an upper lid 8 and a lower lid 9, and high-pressure water and other liquids in the processing chamber 11. For a hydrostatic pressurizing apparatus in which a material to be formed is press-formed by supplying a pressurized medium and applying hydrostatic pressure by pressurizing the pressurized medium, a primary depressurizing opening / closing valve 15 and a throttle valve as mechanical throttle means 16 are provided. Are connected in series, and a secondary pressure reducing device according to the present invention is additionally provided.

In the secondary pressure reducing device, a supply / discharge opening / closing valve 13 for supplying / discharging the hydraulic medium and a variable discharge amount type hydraulic medium pump 1 capable of changing the discharge amount are interposed in series. A secondary pressure reducing throttle circuit in which a secondary pressure reducing on-off valve 5 and a mechanical throttle means 6 realized by a throttle valve having a fixed throttle opening are connected in series; It is configured to include an operation control including a discharge amount adjustment of the pump 1 and a decompression control means for performing an on-off valve 13 for supply / discharge and an on-off control of the on-off valve 5 for secondary pressure based on a preset decompression program.

A pump circuit is connected in parallel to the primary pressure reducing circuit. The secondary pressure reducing throttle circuit is connected in parallel to the hydraulic medium pump 1. On the other hand, the pressure reduction control means is formed by a control circuit having the pump discharge amount setting device 2 and the pressure reduction program setting device 3 as components, and connects the supply / discharge on-off valve 13 and the discharge port of the hydraulic medium pump 1 to each other. A hydraulic medium pressure signal from the pressure gauge 4 connected to the connected pipe 12 is received as an input element, and a drive output is given to a motor for the hydraulic medium pump 1 to perform rotation control.

In this embodiment, the supply / discharge opening / closing valve 13 in the pump circuit allows the flow of the supply liquid from the hydraulic medium pump 1 side and prevents the flow of the discharge liquid from the high pressure forming container side. The pilot-operated check valve provided as described above is used. On the other hand, the hydraulic medium pump 1 is a pressure forming pump for making the inside of the processing chamber 11 a high-pressure atmosphere, and is also used for secondary pressure reduction. It is also used as a dual purpose.

The operation of the secondary pressure reducing device thus constructed will be described. In FIG. 1, after the pressurizing process is performed in the processing chamber 11, the primary pressure reducing on-off valve 15 is opened to open the primary pressure reducing device. The primary decompression is performed by the secondary decompression throttle valve 14 to reduce the pressure in the processing chamber 11 to the secondary decompression start pressure. Upon completion of the primary pressure reduction, the primary pressure reduction on-off valve 15 is closed. Subsequently, the process is shifted to the secondary pressure reduction process.

First, the secondary pressure reducing on-off valve 5 is opened, and the hydraulic medium pump 1 and the hydraulic medium tank 7 are communicated by the pipe 12. Next, the hydraulic medium pump 1 is driven, and the discharge amount of the hydraulic medium pump 1 is increased until the pressure measured by the pressure gauge 4 reaches the secondary pressure reduction start pressure. Here, the throttle valve as the mechanical throttle means 6 is provided so that the hydraulic medium pump 1 can increase the discharge pressure to the secondary pressure reduction start pressure at the stage of the intermediate discharge amount less than the maximum discharge amount. The throttle opening is set in advance. When the pressure measured by the pressure gauge 4 reaches the secondary pressure reduction start pressure, the supply / discharge on-off valve 13 is forcibly opened by a pilot operation, and the processing chamber 11, the hydraulic medium pump 1, and the hydraulic medium tank 7 are connected by piping. 12 and the secondary pressure reduction is started.

If the measured pressure is low while comparing the pressure set in the pressure reducing program setting device 3 with the pressure measured by the pressure gauge 4, a command to increase the pump discharge amount is issued to the pump discharge amount setting device 2. To increase the discharge amount of the hydraulic medium pump 1. Conversely, when the measured pressure is high, a command to lower the pump discharge amount is issued to the pump discharge amount
Lower the discharge amount. By performing such control,
The pressure in the processing chamber 11 is controlled according to a preset pressure pattern.

[0017]

FIG. 2 is a circuit diagram showing an apparatus according to another embodiment of the present invention. The other embodiment shown in FIG. 2 is similar to the embodiment shown in FIG. 1 and corresponding members are denoted by the same reference numerals. It should be noted that the hydraulic medium pump 1 is a constant discharge type pump having a constant discharge amount, and that the mechanical restricting means 16 in the secondary pressure reducing restrictor circuit adjusts the degree of opening of the restrictor. For example, it may be a variable throttle valve, and the pressure reducing control means may be a pressure reducing program setting device 3
And a throttle valve opening setter 17 which is formed by a control circuit which receives a hydraulic pressure signal from the pressure gauge 4 as an input element and controls the variable throttle valve 16 to increase or decrease the throttle opening. The point of providing an output is the same as that of the embodiment shown in FIG.

Referring to the operation of the other embodiment of the apparatus constructed as described above, referring to FIG. 2, after the pressurizing process is performed in the processing chamber 11, the primary pressure reducing on-off valve 15 is opened to The primary decompression is performed by the secondary decompression throttle valve 14 to reduce the pressure in the processing chamber 11 to the secondary decompression start pressure. Upon completion of the primary pressure reduction, the primary pressure reduction on-off valve 15 is closed. Subsequently, the process is shifted to the secondary pressure reduction process.

First, the secondary pressure reducing on-off valve 5 is opened, and the hydraulic medium pump 1 and the hydraulic medium tank 7 are communicated by the pipe 12. Next, the hydraulic medium pump 1 is driven, and the variable throttle valve 1 is moved until the pressure measured by the pressure gauge 4 reaches the secondary pressure reduction start pressure.
Squeeze 6. When the pressure measured by the pressure gauge 4 reaches the secondary pressure reduction start pressure, the supply / discharge on-off valve 13 is forcibly opened by a pilot operation, and the processing chamber 11, the hydraulic medium pump 1, and the hydraulic medium tank 7 are connected by piping. 12 and the secondary pressure reduction is started.

While comparing the pressure set in the pressure reducing program setting device 3 with the pressure measured by the pressure gauge 4, if the measured pressure is low, the variable throttle valve 1 is set in the throttle valve opening degree setting device 17.
A command to reduce the degree of opening of 6 is issued, and the degree of restriction of the variable throttle valve 16 is reduced. Conversely, when the measured pressure is high, a command to increase the opening of the variable throttle valve 16 is issued to the throttle valve opening setting device 17 to increase the degree of throttle of the variable throttle valve 16. By performing such control, the processing chamber 11 can be controlled according to a preset pressure pattern.
To control the pressure.

Although the structure and operation of the other embodiments have been described above, the present invention uses a variable discharge pump for the hydraulic medium pump 1 of the pump circuit in addition to the above two embodiments.
A device using a variable throttle opening type throttle unit as the mechanical throttle unit of the secondary pressure reducing throttle circuit may be used. In this case, for example, compared to the pressure set in the pressure reducing program setter 3, When the measured pressure is low, the discharge amount of the hydraulic medium pump is increased, or the opening degree of the mechanical restricting means is reduced, and when the measured pressure is high, the opening degree of the mechanical restricting means is increased, or when the hydraulic medium pump is discharged. By performing control so as to reduce the amount, the pressure in the processing chamber 11 can be controlled according to a set pressure pattern, and such modifications are naturally included in the scope of the present invention. .

[0022]

As is apparent from the above description, the present invention constitutes a secondary pressure reducing device by a device having a simple structure in which a hydraulic medium pump and mechanical throttle means such as a throttle valve are combined. By realizing the decompression device that does not require the decompression cylinder, the following excellent effects can be obtained. (1) Even if the capacity of the hydrostatic pressurizing device is increased, a standardized secondary depressurizing device having the same structure can be used regardless of this, so that a device having a low device cost can be widely used. Therefore, reduction in apparatus cost can be realized by standardizing the members. (2) The use of simple valves such as open / close valves, check valves, and throttle valves eliminates the need for servo valves, and can also be used as a hydraulic medium pump for pressure molding, reducing equipment costs. I do. In addition, since the cleanliness of the hydraulic oil can be kept within a normal range, the maintenance becomes very easy and the apparatus maintenance cost can be reduced. (3) Installation space is reduced because no pressure reducing cylinder is used.

[Brief description of the drawings]

FIG. 1 is a device circuit diagram according to an embodiment of the present invention.

FIG. 2 is a device circuit diagram according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hydraulic medium pump 2 ... Pump discharge amount setting device 3 ... Decompression program setting device 4 ... Pressure gauge 5 ... Second decompression opening / closing valve 6 ... Mechanical throttle means 7 ... Hydraulic medium tank 8 ... Top cover 9 ... Bottom cover DESCRIPTION OF SYMBOLS 10 ... High-pressure molding container 11 ... Processing chamber 12 ... Piping 13 ... Supply / discharge on-off valve 14 ... Mechanical restricting means 15 ... Primary pressure reducing on-off valve 16 ... Mechanical restricting means 17 ... Restrictor valve opening degree setting device

Claims (4)

[Claims] 1. A molding material is sealed in a high-pressure molding container,
In a hydrostatic pressurizing apparatus for press-forming a material to be formed by hydrostatic pressure pressurization in the container, a primary depressurization was performed by a primary depressurization circuit having a mechanical drawing means 14 after the press-forming. A supply / discharge opening / closing valve 13 and a variable discharge type hydraulic medium pump 1
Are connected in series to the primary pressure reducing circuit, and a secondary pressure reducing opening / closing valve 5 and a mechanical throttle means 6 having a fixed throttle opening are connected in series. A secondary pressure reducing throttle circuit connected in parallel to the hydraulic medium pump 1,
A pressure reduction control means for performing operation control including adjustment of the discharge amount of the hydraulic medium pump 1 and opening / closing of the supply / discharge on / off valve 13 and the secondary pressure reduction on / off valve 5 based on a preset pressure reduction program; The secondary depressurization on-off valve 5 is opened when the primary decompression is completed, and the hydraulic pressure medium pump 1 opens the secondary decompression on-off valve 5
The discharge amount is adjusted so that the discharge pressure rises up to the secondary pressure reduction start pressure based on the pressure reduction program, and then the discharge amount is adjusted so as to gradually reduce the pressure. The valve is opened when the discharge pressure of the pressure-medium pump 1 reaches the secondary pressure-reduction start pressure.
The throttle opening is set so that the hydraulic medium pump 1 can increase the discharge pressure to the secondary pressure reduction start pressure at an intermediate discharge amount less than the maximum discharge amount. Secondary decompression device. 2. A molding material is sealed in a high-pressure molding container,
In a hydrostatic pressurizing apparatus for press-forming a material to be formed by hydrostatic pressure pressurization in the container, a primary depressurization was performed by a primary depressurization circuit having a mechanical drawing means 14 after the press-forming. This is a device for performing a secondary pressure reduction subsequently, and a supply / discharge on-off valve 13 and a constant discharge type hydraulic medium pump 1 are connected in parallel to the primary pressure reduction circuit via a series connection. A secondary pressure reducing throttle circuit in which a pump circuit, a secondary pressure reducing opening / closing valve 5 and a mechanical throttle means 16 capable of adjusting the throttle opening are connected in parallel to the hydraulic medium pump 1 via a serial connection. Operation control of the hydraulic medium pump 1 and mechanical throttling means 16
And a pressure reducing control means for controlling the opening / closing of the supply / discharge opening / closing valve 13 and the secondary pressure reducing / opening valve 5 based on a preset pressure reducing program. When the primary pressure reduction is completed, the valve is opened, the hydraulic medium pump 1 is driven before and after the opening of the secondary pressure reduction on-off valve 5, and the supply / discharge on-off valve 13 is connected to the hydraulic medium pump 1 Discharge pressure is 2
The valve is opened when the next pressure reduction start pressure is reached, and the mechanical restricting means 16 reduces the pressure gradually after the discharge pressure of the hydraulic medium pump 1 increases to the secondary pressure reduction start pressure based on the pressure reduction program. And a secondary pressure reducing device in the hydrostatic pressurizing device, wherein a throttle opening is adjusted. 3. A molding material is sealed in a high-pressure molding container,
In a hydrostatic pressurizing apparatus for press-forming a material to be formed by hydrostatic pressure pressurization in the container, a primary depressurization was performed by a primary depressurization circuit having a mechanical drawing means 14 after the press-forming. A pump circuit for performing a secondary pressure reduction subsequently and successively, the pump circuit being connected in parallel to the primary pressure reduction circuit through a discharge amount variable type hydraulic medium pump 1 in series;
A secondary pressure reducing throttle circuit connected in parallel to the hydraulic medium pump 1 through a secondary pressure reducing on-off valve 5 and a mechanical throttle means 16 capable of adjusting the throttle opening degree in series; Medium pump 1
Control, which controls the opening degree of the mechanical throttle means 16 and the opening / closing control of the supply / discharge on-off valve 13 and the secondary decompression on-off valve 5 based on a preset decompression program. Means for opening and closing the secondary pressure reducing valve 5
Is opened when the primary pressure reduction is completed, the hydraulic medium pump 1 is driven before and after the opening of the secondary pressure reduction on-off valve 5, and the supply / discharge on-off valve 13 is Pump 1 discharge pressure is 2
The valve is opened when the next pressure reduction start pressure is reached, and at least one of the hydraulic medium pump 1 and the mechanical throttle means 16 is configured to reduce the discharge pressure of the hydraulic medium pump 1 to 2 based on the pressure reduction program.
So as to gradually reduce the pressure after rising to the next decompression start pressure,
A secondary depressurizing device in a hydrostatic pressurizing device, wherein at least one of a discharge amount and a throttle opening is adjusted. 4. A supply / discharge on-off valve 13 in a pump circuit.
However, the hydraulic pump 1 is provided with a pilot operated check valve provided to allow the flow of the liquid supply from the hydraulic medium pump 1 side and to prevent the flow of the drainage from the high pressure molding container side.
4. The secondary depressurizing device in the hydrostatic pressurizing device according to claim 1, wherein is a pressure forming pump which is also used for secondary depressurizing.