JP5508708B2 - Hot isostatic press - Google Patents

Description

  The present invention relates to a hot isotropic pressure pressurizing apparatus that heat-treats an object to be processed under a high-pressure gas atmosphere. The present invention relates to an isotropic pressure press.

  Generally, heat treatment is generally performed in a process (hereinafter also referred to as HIP process) in which the object to be treated is heated in a high-pressure gas atmosphere to crush and eliminate casting voids, gas pores, or residual pores in the sintered body. An isostatic pressurizing device (hereinafter also referred to as HIP device) is used. In a high-pressure gas atmosphere furnace typified by a hot isostatic press, a heating method using Joule heating that utilizes the electrical resistance of a conductive material is usually employed. The material of the heater element (hereinafter also simply referred to as a heater) used for this purpose is selected according to the furnace ambient temperature (treatment temperature) and the heat resistance of the heater material.

  That is, it is used by supplying heating power under conditions such that the temperature of the heater element is equal to or lower than the heat resistance temperature relative to the ambient temperature. Here, the heat-resistant temperature refers to a temperature at which a shape cannot be maintained due to creep deformation, or a temperature at which a reaction (reaction with an atmospheric gas or a melting reaction) occurs to stop functioning as a heater. The heater element is used at a temperature where the amount of heat released from the surface of the element and Joule heat generation due to current balance (equal). The heat radiation form from the heater element is mostly due to radiation in a vacuum furnace, and in an atmospheric furnace or an inert gas atmosphere heating furnace near atmospheric pressure, it is due to natural convection of radiation and air or gas.

  A hot isostatic pressurizing apparatus according to a conventional example will be described below with reference to FIGS. FIG. 4 is a view showing the structure of a hot isostatic pressing apparatus according to a conventional example, FIG. 5 is a view showing the surface load density with respect to the furnace temperature of the Fe—Al—Cr heater, and FIG. FIG. 7 is a diagram showing the allowable surface load density in a high-pressure and atmospheric-pressure nitrogen atmosphere of the heater, FIG. 7 is a diagram showing the relationship between the nitrogen gas flow rate and the heat transfer coefficient in the high-pressure and atmospheric-pressure nitrogen atmosphere, and FIG. It is sectional drawing of a container and an electric furnace.

  Normally, the hot isostatic pressing device (HIP device) according to the conventional example has a structure in which a resistance wire heating type electric furnace is accommodated inside a vertical cylindrical high-pressure vessel 102 as shown in FIG. ing. Inside the high-pressure vessel 102, resistance wire heating type heaters 103, 103, 103 are arranged in a plurality of stages in the vertical direction so as to surround the processing chamber 104, and between the upper and lower parts by natural convection of atmospheric gas. The temperature distribution is eliminated by heating all over the top and bottom. Further, the natural convection of the gas also causes the heat for heating and raising the temperature of the processing chamber 104 to be excessively dissipated out of the system. Therefore, a structure that surrounds the processing chamber 104 and the heaters 103, 103, 103 is employed (see Patent Document 1).

  Then, the heat generated by the heaters 103, 103, 103 is supplied to the high-pressure gas in the atmosphere and the object to be processed by radiation and radiation by natural convection, and the heaters 103, 103, 103 as heat sources are configured. Is always higher than the ambient gas, and the heat-resistant temperature of these heater element materials is the upper limit temperature. Therefore, as the processing temperature approaches the heat resistance temperature of the heater element material, the allowable surface load density decreases, and this must be avoided by increasing the surface area. That is, in order to secure the necessary electric power that can be input, it is necessary to increase the space of the heaters 103, 103, 103, and the volume occupied by the heaters 103, 103, 103 in the expensive high-pressure vessel 102 increases. I cannot help it.

As described above, the hot isostatic pressing apparatus according to the conventional example is mainly mainly radiating heat by natural convection of gas forming radiation and atmosphere. For this reason, the manufacturer that manufactures and sells the heater elements to be used provides the allowable surface load density with respect to the ambient temperature (= allowable heating power / heater surface area: W / cm ² ) as design data. Based on the data, the sectional shape and length of the heater element are calculated by calculating the surface area of the heater with respect to the heating power to be input.

For example, an Fe—Al—Cr-based heater material (Pyromax manufactured by Riken Corporation) will be described with reference to FIG. In FIG. 5, the curve indicated as PX-D has a heat resistance temperature at which creep deformation becomes remarkable, which is about 1300 ° C. Therefore, when the curve is higher than 1300 ° C., the allowable surface load density is 0 W / cm ² . Since this curve is for design and the safety factor is taken into consideration, it is assumed that it can be used in a shaded design range for a short time. In addition, the amount of heat release depends on the heat insulation of the furnace, so if the heat insulation is poor for the same furnace temperature, that is, if there is a large amount of heat release, it will be necessary to supply extra power to the heater. Therefore, the design range is indicated by a shaded area surrounding the above curve.

  Thus, the amount of heat released from the heater is determined by the natural convection heat transfer generated by the difference between the heater element temperature and the ambient temperature, and the radiant heat transfer between the surrounding structures and processed products. Is the same. A significant difference from the vicinity of the atmospheric pressure is that, in a high-pressure gas atmosphere of 100 MPa, the gas density is large and the specific heat is large, so that the amount of heat transferred by convection is large.

  That is, even at the same furnace temperature, the heat transfer coefficient of natural convection increases near atmospheric pressure and in a high-pressure gas atmosphere, and the heater element temperature becomes lower than that under atmospheric pressure even when the same power is applied. This means that even if the allowable surface load density for the same furnace temperature is increased, the difference between the ambient temperature and the heater element temperature is reduced, and the margin to the heat resistant temperature of the heater element is increased.

In the case of the heater of the HIP apparatus according to the conventional example, the heater element is usually used in a situation where a heat radiation phenomenon due to radiation and natural convection occurs. In fact, in the case of the PX-D material, the design data (Riken Co., Ltd., for use under atmospheric pressure) shows an allowable surface load density of 1 W / cm ² for a furnace temperature of 1200 ° C. as shown in FIG. Under the nitrogen gas atmosphere, as shown in FIG. 6, it is known that it is allowed up to about 10 W / cm ^2, and it is designed based on an empirical value of this surface load density.

  On the other hand, in recent years, there has been a strong demand for a compact apparatus, and a high-pressure vessel using a fan for forced convection is being used. The use of this fan is often adopted for the purpose of shortening the cooling time, but another advantage is that the allowable surface load density of the heater can be further increased.

  FIG. 7 shows the increase in the heat release due to forced convection as a relationship between the nitrogen gas flow rate and the heat transfer coefficient in a high pressure (100 MPa) and atmospheric nitrogen atmosphere. The horizontal axis is the flow velocity by forced convection. Under atmospheric pressure, the heat transfer coefficient increases by an order of magnitude even when the flow velocity is 20 m / sec or more. It can be seen that the value is two orders of magnitude greater than under atmospheric pressure.

Table 1 shows the heat transfer coefficient and forced convection in the case of natural convection in an atmospheric pressure state and a nitrogen gas atmosphere of 100 MPa when the atmospheric temperature is 1200 ° C. and the heater element temperature is 200 ° C. higher than the atmospheric temperature. The result of calculating the heat transfer coefficient (W / m ² K) when the flow rate is increased is shown. Incidentally, it can be read from this table that the flow rate of the atmospheric gas generated by natural convection corresponds to about 0.4 m / sec, and that of high pressure nitrogen corresponds to about 0.1 m / sec. Under a high-pressure nitrogen gas atmosphere, the heat transfer coefficient is increased to about 10 to 36 times that of natural convection by setting the flow rate to 1 to 5 m / sec by forced convection. That is, it is possible to input heating power 10 to 36 times the temperature difference (200 ° C.) of the same atmospheric temperature and heater element.

On the other hand, in recent years, it has been recognized that in a HIP apparatus targeting a processing temperature of around 500 ° C., it is possible to efficiently heat using convection of high-pressure gas at a temperature of around 500 ° C. As shown in FIG. A hot isostatic pressurization device 31 is proposed in which forced convection is caused by a fan 33 disposed below the processing chamber 34 to increase the amount of heat supplied from the base heater 35. (See Patent Document 2). However, in this case, if the fan 33 is stopped for some reason and the forced convection is interrupted, the temperature of the base heater 31 rapidly rises and exceeds the heat-resistant temperature due to a rapid decrease in the amount of heat removed. There is a risk that
JP 2007-309548 A JP 2003-336972 A

  In the hot isostatic pressing apparatus according to the conventional example, in which heat is transferred from the heater by natural convection and radiation to the object to be processed through a high-pressure atmospheric gas such as argon or nitrogen, the surface load density of the heater element is reduced. Since the limit is small and the surface area of the heater needs to be increased, the heater itself becomes large and cannot meet the recent demand for compactness. Further, since the heat resistant temperature of the Fe-Al-Cr alloy heater element is about 1300 ° C., the atmospheric temperature, that is, the furnace temperature, is about 200 ° C. lower than that in the case of an argon atmosphere of 100 MPa, that is, 1100 to 100 ° C. The upper limit is about 1130 ° C., and it is necessary to use another heater element material to generate a temperature higher than this.

However, when oxidation resistance is required, there is a problem that there is no material suitable for the heater element material other than an expensive material such as platinum. Further, this platinum also has a melting point of 1768 ° C., and the limit of the furnace temperature in the argon / oxygen mixed atmosphere of 100 MPa using platinum as the heater element is 1550 to 1570 ° C.
On the other hand, in the hot isostatic press apparatus according to the conventional example using the forced convection method that transfers the heat from the heater to the high-pressure atmospheric gas using a fan, the heater element is stopped when the fan stops for some reason. The temperature rises rapidly, causing troubles such as disconnection.

  Accordingly, an object of the present invention is to provide a hot isostatic pressing device capable of supplying a large heating power to a heater element and avoiding damage due to overheating of the heater element.

In order to achieve the above object, the means adopted by the hot isostatic pressing device according to claim 1 of the present invention includes a high-pressure vessel that accommodates an object to be treated, and a heating installed below the high-pressure vessel. A hot isostatic pressure comprising pressure medium gas forced convection means under the high pressure vessel for forcibly convection of the pressure medium gas heated by the heating means into the high pressure vessel. The pressurizing device is provided in the vicinity of the heating means, and includes a temperature measuring means for detecting an ambient temperature in the vicinity of the heating means, and the atmospheric temperature is overheated to a predetermined temperature or more. When the temperature measuring means detects, a protection means is provided for controlling to cut off or reduce the power supplied to the heating means to prevent overheating of the heating means ,
The pressure medium gas forced convection means is composed of an acoustic flow generator that generates an acoustic flow for stirring and circulating the pressure medium gas, and an ultrasonic transducer that vibrates the acoustic flow generator. It is what.

According to the hot isostatic pressing apparatus according to claim 1 of the present invention,
A pressure vessel for forcibly convection of the pressure medium gas heated by the heating means, into the high-pressure vessel. A hot isostatic pressurizing device provided with a medium gas forced convection means below the high-pressure vessel, the temperature measuring means being installed in the vicinity of the heating means and detecting the ambient temperature in the vicinity of the heating means And when the temperature measuring means detects that the ambient temperature is overheated to a predetermined temperature or higher, the power supplied to the heating means is cut off or reduced to prevent overheating of the heating means. Protective means for controlling in such a way that the pressure medium gas forced convection means generates an acoustic flow that agitates and circulates the pressure medium gas, and an ultrasonic vibration that vibrates the acoustic flow generator Composed of children and It becomes Te.

As a result, troubles such as melting of the heating means are suppressed, the supply of heat to both the object to be processed and the high-pressure gas is improved, and the heating time is shortened. In addition, the heating means can be designed with a higher surface load density, and the heating means can be made compact. Furthermore, even with the same heat generating means, the maximum temperature that can be generated can be increased as compared with the natural convection / radiation type according to the conventional example.
The supply of heat to both the object to be processed and the high-pressure gas is greatly improved and the heating time is shortened without causing a trouble that the heating means is melted. In addition, the heating means can be designed with a higher surface load density, and the heating means can be made compact. Furthermore, even with the same heating means, the maximum temperature that can be generated can be increased by 100 ° C. or more compared to the natural convection / radiation type according to the conventional example.
In addition to the problem of increasing the cost of the fan material associated with the installation of the agitating fan, it is possible to avoid problems such as bending stress and blurring, and space constraints such as fan drive motors.

First, the structure and operation of hot isostatic pressing apparatus according to the shape condition of the embodiment of Reference Example (HIP apparatus) will be described with reference to the accompanying drawings 1-3 below. 1 for illustrating the structure of isostatic pressing device hot in accordance with the form status of implementation of the reference example, schematic elevational sectional view showing a sectional elevation of an empty furnace condition, Figure 2 is in operation in FIG. 1 schematic elevational cross-sectional view for explaining the flow conditions of the high-pressure gas in the high pressure vessel, Figure 3 is for explaining the structure of hot isostatic pressing apparatus according to the shape condition of the present invention, empty furnace conditions FIG.

Hot isostatic pressing apparatus according to the shape condition of the embodiment of the reference example, a high-pressure cylinder 1, the upper lid 2, the interior of the pressure vessel consists of the lower lid 3, the field made a processing chamber of a heat insulating structure 4 5, a heater (heating means) 6 disposed in the heating chamber 6a at the lower end of the processing chamber 5, and a stirring fan (pressure medium) for generating forced convection disposed below the heater 6 in the heating chamber 6a. Gas forced convection means) 7 is provided. Hot isostatic pressing apparatus 1 according to the shape condition of the embodiment of the reference example, without performing the heating of the radiant heat by the process object from the side surface heater as shown in FIG. 4 was pre-mentioned, 1000 It enables processing up to a high temperature of ℃ or higher.

  During normal processing, shelves are installed in the processing chamber 5 as shown in FIG. 4 or FIG. 8, and a processing object is placed on each shelf. This example shows an empty state in which the processing chamber has neither a shelf nor an object to be processed, that is, an empty furnace state. In order to guarantee the heat history of all the processing objects stored in the processing chamber 5, the upper processing chamber temperature measuring member 9 a is usually provided at least near the upper end of the processing chamber 5. A lower processing chamber temperature measuring member 9b is attached in the vicinity of the lower end so that each temperature in the processing chamber 5 can be measured. Further, a heater overheating monitoring temperature measuring member (temperature measuring means) 10 is attached in the vicinity of the heater 6 of the heating chamber 6a so that the ambient temperature in the vicinity of the heater 6 can be measured.

The temperature detection signals detected by the upper processing chamber temperature measuring member 9a and the lower processing chamber temperature measuring member 9b are transmitted to a controller (not shown), and also by the upper and lower processing chamber temperature measuring members 9a, 9b. Protection means for protecting the heater 6 is provided by performing control to cut off or reduce the heating power to the heater 6 by the controller based on the detected temperature detected. Further, when the detected temperature detected by the upper processing chamber temperature measuring member 9a and the lower processing chamber temperature measuring member 9b has a temperature difference of a predetermined value or more, the controller drives the stirring fan 7 The rotational speed of the motor 8 is controlled to increase the convection speed of the high pressure gas so as to control the heat uniformity in the processing chamber 5.

  Reference numeral 14 denotes a pedestal provided with a gas flow hole 14a. A plurality of shelf boards (not shown) are installed on the pedestal, and a processing object is placed on each shelf board. The high-pressure gas heated by the heater 6 is stirred by the stirring fan 7 and then reaches the processing chamber 5 from the heating chamber 6a through the gas circulation hole 14a. In the temperature range up to about 1000 ° C., it is empirically known that the heat uniformity in the processing chamber 5 can be easily secured if the stirring fan 7 is driven at a speed higher than a certain speed. Here, reference numeral 12 denotes a gas introduction hole for introducing high-pressure gas into the high-pressure vessel, and reference numeral 13 denotes a water-cooling jacket for cooling the high-pressure cylinder 1. The water-cooling jacket 13 is supplied with cooling water. The cooling water inlet 13a and the cooling water outlet 13b for discharging are attached.

  When the heater 6 is energized in a high-pressure state, the high-pressure gas filled in the space in which the heater 6 is stored is heated to rise in the processing chamber 5, and a cylindrical rectifier cylinder that stores a processing object (not shown). Natural convection is generated such that the outer side of 11 is lowered and returned to the stirring fan 7 portion. That is, the flow by this natural convection draws a circulating flow as shown by arrows in FIG. The processing object in the processing chamber 5 is heated by the circulation of the high-pressure gas.

However, only natural convection has a heat transfer coefficient of about 100 W / m ² K, even as high-pressure nitrogen gas of 100 MPa, as described with reference to Table 1, The heat absorption efficiency from the surface of the heater element 6 is not sufficient. Therefore, while it takes time for heating, if a large electric power is applied as described above, heat dissipation from the heater element 6 is small, and the heater element 6 itself is overheated and tends to exceed the heat resistant temperature. The heater overheat monitoring temperature measuring member 10 installed in the heating chamber is installed to detect such a state, and the detected temperature detected by the heater overheat monitoring temperature measuring member 10 has a predetermined temperature. If it exceeds, it is comprised so that control which interrupts | blocks or reduces the supply heating electric power to the heater 6 may be performed by the said controller.

  In the heating chamber 6a, the portion where the heater element 6 is easily overheated corresponds to a portion where the gas flow due to natural convection is likely to stagnate and heat is likely to accumulate. That is, one of such portions is a portion where the upper space of the heater element 6 is not opened near the upper end of the heater element 6, and therefore, at least one heater overheating monitoring temperature measuring member is provided in such a portion. 10 is arranged. Specifically, when the agitating fan 7 is arranged as shown in FIGS. 1 and 2, the space located in front of the fan rotation shaft 8a tends to reduce the gas flow velocity. It is recommended to dispose the fan rotating shaft 8a above the nearby horizontal plane.

  Of course, the temperature measuring member 10 for monitoring the heater overheat is not limited to this one place, and it is preferable to install a plurality of places. As shown in FIGS. 1 and 2, in the heating chamber 6a, in addition to the fan rotation shaft 8a, the heater element 6 is disposed and a position far from the stirring fan 7 may be overheated. Therefore, it is realistic to arrange it at such a position. As the temperature measuring member 10 for monitoring the heater overheat, a small installation space is required, and it is recommended to use a thermocouple from the viewpoint of temperature measurement accuracy and reliability, but other means such as a resistance thermometer are used. May be.

In hot isostatic pressing apparatus according to the shape condition of the embodiment of the reference example, the stirring fan 7 as described above is driven by a fan drive motor 8, thereby forcing convection of the gas in the high pressure vessel. At this time, the flow of the high-pressure gas is formed so as to draw a circulation flow similar to the flow by the natural convection described above. Such forced convection originally acts in such a way as to further promote the phenomenon in which a flow due to natural convection is formed, so that a large amount of power is not required to drive the stirring fan 7.

  In addition, the structure of the stirring fan 7 is suitable for a so-called axial flow type (axial type) in which a high flow rate is easily obtained, and a material such as a molybdenum alloy that can withstand a high temperature of 1200 ° C. is used. It is common. By forced convection using such a stirring fan 7, the flow rate of the high-pressure gas can be easily set to 1 to 5 m / sec. As a result, as shown in Table 1, the heat transfer coefficient is drastically improved, the heat transfer from the heater element 6 is improved as well as the supply of heat to the object to be processed, and the heater element 6 is overheated. Can be prevented. As a result, even with the heater 6 using the same heater element material, the maximum ambient temperature (furnace temperature) can be obtained by using forced convection as in the present invention as compared with the case of the conventional natural convection type HIP apparatus. ) Can be brought closer to a temperature closer to the heat resistant temperature of the heater element material.

The hot isostatic pressing apparatus according to the shape condition of the embodiment of the reference example, a technical problem when adopting such a forced convection heater structure, some trouble occurs in stirred fan 7 It is important to add protection means for the heater 6 when forced convection of high pressure gas becomes unavailable. In other words, the stirring fan 7 is usually disposed below the heater 6 in the heating chamber 6a below the space of the processing chamber 5 because of the heat resistance of the constituent material and the drive motor 8. The adhering sand, rust, etc. are likely to fall and enter the bearing portion of the agitating fan 7 or the drive motor 8 to cause a trouble that the fan rotating shaft 8a does not rotate.

  In this way, when foreign matter such as rust or sand enters the bearing portion of the agitating fan 7 or the drive motor 8 and stops rotating, it is usually overloaded by a sensor such as an ammeter that detects overload. A signal is transmitted to the controller, and the power supplied to the drive motor 8 is cut off by a command from the controller, but a protection circuit is provided to cut off the supply of heating power to the heater 6 using the overload signal. Is also recommended.

<Example>
Natural convection, radiation type HIP apparatus according to the conventional example (Comparative Example), the forced convection type HIP apparatus according to the shape condition of the embodiment of Reference Example (Example), when using the same heater element material, it customary Table 2 shows the results of evaluation on the maximum ambient temperature. For example, in HIP processing of powder high-speed steel, high-pressure processing is performed at a normal temperature of about 1100 ° C., and an Fe—Al—Cr heater can be used. In this case, in the comparative example, since the maximum temperature of the atmosphere was about 1150 ° C., the life of the heater was not always sufficient, but in the example, the temperature could be increased to the maximum atmospheric temperature of 1250 ° C. Heating can be carried out with a margin temperature ΔT (= heat-resistant temperature−maximum ambient temperature), and there is no problem in practical life of the heater.

  In addition, in the hot isostatic pressing process for some oxide ceramics, an atmospheric gas in which oxygen is added to about 1 to 10% at a processing pressure of 100 MPa and a processing temperature of 1500 ° C. or higher is used. The only heater material that can be used in such a gas atmosphere is platinum or platinum rhodium alloy. In large HIP devices, the natural convection / radiation type according to the conventional example cannot increase the surface load density and increase the surface area, that is, a large amount. The problem of having to use platinum was generated.

Further, in the platinum rhodium alloy, the higher the element temperature, the more the rhodium volatilizes and the weight is reduced, and there is a problem that it reattaches to the wall of the furnace. And the trouble that the heater element 6 is melted does not occur. Similar results were obtained with a molybdenum alloy heater element to which molybdenum or La ₂ O ₃ having excellent heat resistance was added.

  By the way, when the hot isostatic pressing device is operated at the maximum temperature, that is, when the heater element 6 is supplied with electric power at a large surface load density, the rotation of the stirring fan 7 is stopped and forced convection is performed. If this becomes impossible and the state returns to the natural convection state, the temperature of the heater element 6 will rise rapidly, and in some cases, it will melt. Therefore, when the drive motor 8 is overloaded or the temperature detection signal value from the heater overheat monitoring temperature measuring member 10 becomes larger than a predetermined value, the supply current to the heater 6 is cut off or reduced. The protection device that performs the control is essential.

  Whether to cut off or reduce the supply current to the heater 6 is practically selected according to the heater element material. That is, in the case of the Fe—Al—Cr alloy shown in Table 2 or platinum or platinum alloy, since the heat resistance standard is melting, damage to the heater 6 due to overheating is immediate and fatal, Is preferred. On the other hand, in the case of pure molybdenum or molybdenum alloy or graphite that is not shown in Table 2 but is often used in HIP devices, the heater is instantly used at the operating temperature because the melting point is very high even if overheated. Since fusing is rare and operation is possible, a certain degree of protection can be realized by reducing the load.

In this case, the range of the supply current to be reduced depends on the operating pressure, but it can be evaluated by the heat transfer coefficient when forced convection changes to natural convection, and if it is a short time, As shown in Table 2, not the margin temperature ΔT = 200 ° C., but the forced convection allows the margin temperature ΔT = 100 ° C. Further, since the supplied power W is represented by W = I ² R, the current is evaluated by the square root of the power, and the protection of the heater 6 is realized by reducing the supplied current value to 1/3 to 1/6. However, if the power supply is reduced to this extent, the temperature will not drop sharply as long as it is 15 to 30 minutes after the temperature is maintained, not immediately after the temperature increase that requires power is completed and the temperature is maintained. In addition, it is possible to relieve a processed product that is damaged by a rapid temperature drop.

  In addition, it is preferable to install not only one location but the temperature measuring member 10 for heater overheat monitoring in multiple places. As in the example shown in FIGS. 1 and 2, it is practical to install the heater 6 in the heating chamber 6 a in which the heater 6 is housed, or at a position that is easily overheated or a position far from the position of the stirring fan 7. As a temperature measuring member used for the heater overheating monitoring temperature measuring member 10, a thermocouple is recommended from the viewpoint of installation space and temperature measuring accuracy, but other temperature measuring means may be used.

Next, a hot isostatic pressing apparatus according to the shape condition of the present invention will be described with reference to the accompanying Figure 3 below. Figure 3 is for explaining the structure of hot isostatic pressing apparatus according to the shape condition of the present invention, is a schematic sectional elevation view showing a sectional elevation of an empty furnace conditions.

Incidentally, when the shape condition of the present invention is different form on purpose of implementation of the above reference example, there are differences in the structure of the medium gas forced convection means, because other is exactly the same configuration, the pressure medium gas The description of the forced convection means and the configuration related thereto will be limited.

That is, the in the configuration of the pressure medium gas forced convection means according to the shape condition of the embodiment of the reference example, the heating chamber 6a, stirring fan 7 which is connected via a rotary shaft 8a to the drive motor 8 was equipped with hand, in the configuration of the pressure medium gas forced convection means according to the shape condition of the present invention, the heating chamber 6a, an acoustic flow generation section 18 for generating the acoustic streaming to stir and circulate the medium gas, the Pressure medium gas forced convection means comprising an ultrasonic transducer 19 for driving the acoustic flow generator 18 is provided.

  The acoustic flow generator 18 is for accelerating soaking of the processing chamber 5, and has a main horn 20 disposed in the center of the processing chamber 5 in a plan view, and a periphery of the main horn 20. The sub horn 21 is disposed on the horn.

  The main horn 20 and the sub horn 21 have a hollow or solid inside and have an inverted frustoconical shape. The diameter increases toward the tip. The main horn 20 and the sub horn 21 have large diameter portions (that is, tip portions) arranged so as to face upward, and a vibration surface (horn vibration surface) is formed at the tip. The material of the horn vibration surface is selected depending on the temperature of exposure, etc., but a metal material such as tungsten or molybdenum with high Young's modulus with little attenuation of sound waves, or a Ni-based superalloy, or silicon carbide, silicon nitride, etc. Heat-resistant ceramics can be used.

The ultrasonic transducer 19 is provided at the base end portion (lower end portion) of the main horn 20 and the sub horn 21 so as to have a one-to-one correspondence with each of the main horn 20 and the sub horn 21, and the surroundings are respectively viewed from above. It is surrounded by a heat insulating protective material 22 for preventing temperature rise due to radiant heat, and the heat insulating protective material 22 is fixed to the upper surface of the lower lid 3 through an attachment cover 23.
When a voltage is applied to the ultrasonic vibrators 19 to drive them, the main horns 20 and the sub horns 21 vibrate the horn vibration surfaces in the respective ultrasonic vibrators 19, and the sound is upwardly induced by this vibration. A straight wave (acoustic wave) is generated. This acoustic traveling wave generates a gas flow by the main horn 20 and the sub horn 21 from the heating chamber 6 a toward the processing chamber 5.

The gas flow caused by the main horn 20 mainly acts as an acceleration of the circulation flow in the processing chamber 5, and the gas flow caused by the sub horn 21 acts mainly as an acceleration of the circulation flow for cooling.
The ultrasonic vibrator 19 for the main horn 20 can be a Langevin type that uses plate-like piezoelectric elements stacked in the vibration direction, and is driven under a high frequency of about 1 MHz. As a thin single element type having a thickness of 10 mm or less can be used. When the single element type is used, the input power is limited, but there is an advantage that the ultrasonic vibrator 19 can be prevented from being overheated by heat conduction from the main horn 20.

On the other hand, the ultrasonic vibrator 19 for the sub horn 21 needs to be charged with a large amount of power in order to achieve the main purpose of generating a cooling circulation flow. It is preferable to use it. In this case, it is preferable to drive at a frequency of 20 to 30 kHz.
In the heating chamber 6a, an annular diffuser portion 25 is provided so as to protrude from the inner peripheral surface to the room at a predetermined height. The height at which the diffuser unit 25 is provided is disposed above and above the horn vibration surface of the main horn 20 of the acoustic flow generation unit 18 (that is, the horn disposed at the center of the processing chamber 5). It is positioned so as to be disposed between the top and bottom of the heater 6.

  An opening 25 a is formed at the center of the diffuser portion 25. The opening 25a is in a positional relationship facing the main horn 20 (a concentric relationship in plan view) and has a larger diameter (larger area) than the main horn 20. Therefore, when a gas flow that is an upward flow is generated in the main horn 20, the pressure medium gas existing below the diffuser portion 25 is drawn into the heating chamber 6 a and becomes a suction gas flow. The ejector effect is induced. Such suction gas flow promotes the generation of a gas flow (circulation flow in the processing chamber) by the main horn 20 and the generation of a gas flow (cooling circulation flow) by the sub horn 21 more efficiently. Is extremely effective in amplifying the signal.

It is to be noted that the edge of the opening 25a (that is, the protruding portion of the diffuser 25) is protruded in a rib shape with its entire circumference facing upward so that the ejector effect can be generated quickly and efficiently. It becomes more suitable.
Then, temperature detection signals detected by the upper processing chamber temperature measuring member 9a and the lower processing chamber temperature measuring member 9b are transmitted to a controller (not shown), and the upper processing chamber temperature measuring member 9a and the lower processing chamber temperature measurement are performed. When the temperature difference between the detected temperatures detected by the member 9b exceeds a predetermined value, the controller controls the ultrasonic vibrator 19 to be driven, so that the thermal uniformity of the processing chamber is maintained. ing.

Above-described above, according to the hot isostatic pressing apparatus according to the present invention, the use of the pressure medium gas forced convection means comprising acoustic flow generation section and the ultrasonic vibrator, preventing overheating protection means of the heater element With this function, both the supply of heat to the object to be processed and the supply of heat from the heater element to the high-pressure gas are greatly improved and the heating time is shortened without causing trouble that the heater blows. . In addition, as a result of the design that increases the surface load density of the heater, the heater can be made more compact, and the maximum temperature that can be generated even with a heater element of the same material is compared to the conventional natural convection / radiation type. The effect of being able to improve the temperature by 100 ° C. or more is greatly enjoyed, which greatly contributes to the expansion of the application field of the hot isostatic pressing device and the improvement of productivity.

For illustrating the structure of a hot isostatic pressing apparatus according to the shape condition of the embodiment of the reference example, it is a schematic sectional elevation view showing a sectional elevation of an empty furnace conditions. FIG. 2 is a schematic vertical sectional view for explaining a flow state of high-pressure gas in a high-pressure vessel during operation in FIG. 1. For illustrating the structure of a hot isostatic pressing apparatus according to the shape condition of the present invention, it is a schematic sectional elevation view showing a sectional elevation of an empty furnace conditions. It is a figure which shows the structure of the hot isostatic press apparatus which concerns on a prior art example. It is a figure which shows the surface load density with respect to the furnace temperature of a Fe-Al-Cr type | system | group heater. It is a figure which shows the allowable surface load density in the high pressure and atmospheric pressure nitrogen atmosphere of a Fe-Al-Cr type | system | group heater. It is a figure which shows the relationship between the nitrogen gas flow rate and heat transfer coefficient in a high pressure and atmospheric pressure nitrogen atmosphere. It is sectional drawing of the high pressure vessel and electric furnace which concern on another prior art example.

Explanation of symbols

1: high pressure cylinder, 2: upper lid, 3: lower lid,
4: Thermal insulation structure, 5: Processing chamber,
6: heater (heating means), 6a: heating chamber,
7: Stirring fan,
8: Drive motor, 8a: Fan rotation shaft,
9a: Upper processing chamber temperature measuring member, 9b: Lower processing chamber temperature measuring member,
10: Temperature measuring member for monitoring overheating of heater (temperature measuring means),
11: Rectifier cylinder, 12: Gas inlet,
13: Cooling water jacket, 13a: Cooling water inlet, 13b: Cooling water outlet,
14: Pedestal, 14a: Gas flow hole,
18: acoustic flow generator, 19: ultrasonic transducer,
20: Main horn, 21: Sub horn,
22: Thermal insulation protective material, 23: Mounting cover,
25: Diffuser part, 25a: Opening part

Claims (1)

A pressure vessel for forcibly convection of the pressure medium gas heated by the heating means, into the high-pressure vessel. A hot isostatic pressurizing device provided with a medium gas forced convection means below the high-pressure vessel, the temperature measuring means being installed in the vicinity of the heating means and detecting the ambient temperature in the vicinity of the heating means And when the temperature measuring means detects that the ambient temperature is overheated to a predetermined temperature or higher, the power supplied to the heating means is cut off or reduced to prevent overheating of the heating means. Protective means to control are provided ,
The pressure medium gas forced convection means is composed of an acoustic flow generator that generates an acoustic flow for stirring and circulating the pressure medium gas, and an ultrasonic transducer that vibrates the acoustic flow generator. A hot isostatic pressing device.

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