Patent Application
20070266866
A description will now be given of embodiments of the present invention.
An isostatic press 1 according to the present embodiment is used for warm isostatic pressing which carries out a processes in which an isostatic pressure is applied via a pressure medium in a temperature range from 100° C. to 300° C. to a workpiece W. The isostatic press 1 includes a high pressure vessel 2, a heat insulator 3 which is stored within the high pressure vessel 2, a heating unit 4 which heats the high pressure vessel 2, and a pressure medium supplying device 5 which introduces the pressing medium inside the high pressure vessel 2, as shown in
The high pressure vessel 2 includes a cylindrical vessel 7 which is formed thick, and an upper closure 8 and a lower closure 9 which detachably close respectively top and bottom openings of the vessel 7 in a liquid tight manner. The pressurized container 2 is formed as a hollow column as a whole.
Though upward and downward axial forces are applied respectively to the upper closure 8 and the lower closure 9 by an internal pressure which acts when the pressure medium is supplied inside the high pressure vessel 2, the upper closure 8 and the lower closure 9 are supported by a press frame (not shown).
The heating unit 4 includes a jacket 11 which is provided on an outer periphery of the vessel 7 of the high pressure vessel 2, and a heater 12 which is connected to top and bottom ends of the jacket 11 via pipes. The vessel 7 of the high pressure vessel 2 and the inside of the high pressure vessel 2 are heated by the circulation of a heating medium between the heater 12 and the jacket 11.
A heat insulator 3 includes a cylindrical heat insulating vessel 14, a top heat insulating closure 15 which closes a top opening of the heat insulating vessel 14, and a bottom heat insulating closure 16 which closes a bottom opening of the heat insulating vessel 14. The heat insulator 3 is formed as a hollow column as a whole. The bottom heat insulating closure 16 is placed on a top surface of the lower closure 9 of the high pressure vessel 2.
It should be noted that the top heat insulating closure 15 may be mounted on a bottom surface of the upper closure 8 of the high pressure vessel 2 so as to be inserted along with the upper closure 8 into a top portion of an inside of the vessel 7 of the high pressure vessel 2. Moreover, it is possible to configure a vessel with a bottom which integrates the heat insulating vessel 14 and the bottom heat insulating closure 16 with each other.
With this configuration, a working zone R which contains a workpiece W is formed in a space surrounded by the heat insulator 3. Moreover, the heat insulator 3 is stored in the high pressure vessel 2 while gaps are provided respectively between the heat insulating vessel 14 and the high pressure vessel 2, and between the top heat insulating closure 15 and the upper closure 8 of the high pressure vessel 2, thereby forming a pressure medium introducing space S which can introduce the pressure medium between the heat insulator 3 and the high pressure vessel 2.
A through hole 15a is formed at a position through which an axis passes vertically at the center of the working zone R in a portion approximately at the center of the top heat insulating closure 15. The pressure medium introducing spate S is caused to communicate with the working zone R via the through hole 15a. It should be noted that it is only necessary to provide the through hole 15a on a top portion of the heat insulator 3, and the through hole 15a may not be provided on the top heat insulating closure 15. Moreover the shape of the through hole 15a is not necessarily round.
Moreover, a pressure medium introducing opening 18 which communicates the a bottom end portion of the pressure medium introducing space S and the pressure medium supplying device 5 with each other is formed on the lower closure 9 of the high pressure vessel 2. The pressure medium supplying device 5 includes a compressor pump which press-feeds the pressure medium at a relatively low temperature to the pressure medium introducing space S, and the like. Though the pressure medium introducing opening 18 is preferably at the bottom end of the pressure medium introducing space S, it is only necessary to provide the pressure medium introducing opening 18 in a bottom portion, and the pressure medium introducing opening 18 may be provided on a side surface of the high pressure vessel 2.
In the present embodiment, water is employed as the pressure medium. A mixture of water and water-soluble oil, or silicon oil also may be used.
The present embodiment is configured as described above. A description will now be given of processing steps using the isostatic press 1 according to the present invention.
In the warm isostatic pressing using the isostatic press 1 according to the present embodiment, the workpiece W is first stored in the working zone R, and a heating and pressurizing step then starts. Heating and pressurizing are not carried out at the same time, and are to be carried out independently in this heating and pressurizing step.
The heating is carried out by circulating the heating medium heated by the heater 12 through the jacket 11.
The pressurizing is carried out by operating the pressure medium supplying device 5, introducing the pressure medium at a high pressure into the pressure medium introducing space S from the pressure medium supply device 5 through the pressure medium introducing opening 18, and flowing the pressure medium from the pressure medium introducing space S into the working zone R inside the heat insulator 3 through the through hole 15a.
On this occasion, the pressure medium at a relatively low temperature introduced from the pressure medium supplying device 5 into the high pressure vessel 2 first flows into the bottom end portion of the pressure medium introducing space S. The pressure medium is then heated by heat exchange with the high pressure vessel 2 which has been sufficiently heated by the heating medium in the jacket 11, while the pressure medium rises in the pressure medium introducing space S. The pressure medium then flows into the working zone R through the through hole 15a. On this occasion, since the working zone R is formed by the heat insulator 3, heat exchange hardly occurs between the inside and outside of the working zone R via the heat insulator 3, and the temperature state of the working zone R provided inside the heat insulator 3 is not disturbed by the introduction of the pressure medium. Moreover, the pressure medium at the relatively low temperature is sufficiently heated by being mixed with the pressure medium heated to a high temperature while being present in the pressure medium introducing space S, and by exchanging heat with the high pressure vessel 2. As a result, even if the temperature state in the pressure medium introducing space S is disturbed by the introduction of the pressure medium at the relatively low temperature in the high pressure vessel 2, the pressure medium introducing space S will return to a desired temperature state relatively soon.
As a result, even if the pressure medium at the relatively low temperature is press-fed into the high pressure vessel 2 from the pressure medium supplying device 5 in order to further pressurize from a predetermined pressure state, the predetermined temperature state is maintained in the working zone R.
Moreover, the vessel 7 of the high pressure vessel 2 is kept to the high temperature by the heating medium in the jacket 11 and the pressure medium at the high temperature, the high pressure vessel 2 provides a high heat retention capability.
When the working zone R has reached a temperature and pressure state required for the workpiece W after the above step, the heating and pressurizing step is completed, and the processing proceeds to a maintaining step. The temperature and pressure state in the working zone R is maintained to the temperature and pressure state required for the workpiece W for a certain period in the maintaining process. The processing of the workpiece W in the working zone R completes thorough a cooling process subsequently.
According to the present embodiment, though the pressure medium at the relatively low temperature is used for pressurizing, the temperature state is not disturbed by the introduction of the pressure medium in the working zone R. Therefore, the temperature state in the working zone R is extremely stable. Moreover, since both the high pressure vessel 2 and the pressure medium are efficiently heated, the processing of the workpiece W at the stable temperature accuracy is also promoted.
Moreover, not only are the pressure medium and the high pressure vessel 2 efficiently heated via the heating medium in the jacket 11, but also is the vessel 7 maintained at the high temperature by the heating medium and the pressure medium at the high temperature, since the vessel 7 is externally heated by the heating medium and the inside thereof is in contact with the pressure medium at the high temperature, as for the high pressure vessel 2. Thus, high pressure vessel 2 consequently provides high heat retention capability. As a result, the temperature accuracy inside the high pressure vessel 2 containing the working zone R is stable, which also increases the temperature accuracy inside the working zone R.
Moreover, since the pressure medium supplying device 5 introduces the pressure medium at a relatively low temperature, it is not necessary to provide a sealing device withstanding a high pressure and a high temperature, which involves technically difficult, at a connection portion between the pressure medium supplying device 5 and the pressure medium introducing opening 18 and the like. Therefore, a configuration in which a known sealing device is provided at the connection portion sufficiently prevents the pressure medium from leaking, resulting in a simpler device configuration and a reduction in the manufacturing cost.
According to the present embodiment, the pressure medium introducing space S is connected to a pressure medium circulating device 21 which circulates the pressure medium inside the pressure medium introducing space S as shown in
The pressure medium circulating device 21 includes a pipeline 24. The pipeline 24 includes a pressure medium outflow pipe 22 which is formed in the upper closure 8, and communicates with the pressure medium introducing space S at a position opposing to the through hole 15a in the top heat insulating closure 15, and a pressure medium inflow opening 23 which is formed in the lower closure 9, and communicates with the bottom end portion of the pressure medium introducing space S. A heating device 25 for heating the pressure medium passing the pipeline 24 is provided in the course of the pipeline 24.
According to the present embodiment, the pressure medium is heated by the heating device 25 while the pressure medium in the pressure medium introducing space S is circulated through the pressure medium circulating device 21 during the heating in the heating and pressurizing step. As a result, the pressure medium is maintained at a high temperature.
Moreover, since the pressure medium is heated to a high temperature by the heating device 25, the high pressure vessel 2 is heated from the inside via the pressure medium, resulting in a reduction in the setup time of the press, and an increase in the heat retention capability of the high pressure vessel 2.
As shown in
The bottom heat insulating closure 16 includes a through hole 16a which passes through from the inside to the outside of the working zone R on the center axis passing vertically at the center of the working zone R at a position corresponding to the through hole 15a in the top heat insulating closure 15. The second pipeline 27 communicates with the through hole 16a.
According to the present embodiment, it is possible to introduce the pressure medium heated to a high temperature by the heating device 25 into the working zone R without introducing into the pressure medium introducing space S, by operating the selector valve 28 to communicate the heating device 25 and the second pipeline 27 with each other. With this configuration, it is possible to efficiently heat the inside of the working zone R and the workpiece W contained in the working zone R. Since the second pipeline 27 communicates with the through hole 16a formed on the axis passing vertically at the center of the working zone R, the pressure medium flowing out into the working zone R from the through hole 16a evenly diffuse radially outward in the radial direction. As a result, the temperature state radially outward in the working zone R is not biased by the introduction of the pressure medium at the high temperature.
Moreover, it is possible to supply the pressure medium introducing space S with the pressure medium heated to the high temperature by the heating device 25 as in the second embodiment, by operating the selector valve 28 to communicate the heating device 25 and the first pipeline 26 with each other. As a result, it is possible to reduce the setup time of the press, and to increase the heat retention capability of the high pressure vessel 2.
Though the embodiments of the present invention have been detailed above, the present invention is not limited to the above embodiments. For example, if there is employed a configuration where the jacket 11 is provided on the upper closure 8 and the lower closure 9 of the high pressure vessel 2, and the heating medium is caused to pass through the jacket 11 to heat the covers, it is possible to provide the same effects as these embodiments. Moreover, the pressure medium introducing opening 18, the pressure medium inflow opening 23, the first pipeline 26, and the second pipeline 27 may be provided on the vessel 7 of the high pressure vessel 2 as long as they communicate with the bottom end portion of the pressure medium introducing space S.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-141903 | May 2006 | JP | national |
