JPH0467136B2 - - Google Patents

Description

Detailed Description of the Invention The present invention applies temperature and gas pressure simultaneously to improve compression molding and sintering of metal powder, improving internal defects in precision castings, improving internal defects in ceramic parts, or molding and sintering. The present invention relates to a temperature detection device for a hot isostatic pressurizing device suitable for carrying out.

Hot isostatic pressing equipment has already been used by tool manufacturers and others to treat internal defects in cemented carbide tools, and is gaining a proven track record.However, in recent years, the scope of application has expanded as the development of new materials such as ceramics and cermets progresses. It is thought that it will gradually grow. The hot isostatic pressurization device has a structure that incorporates a heating furnace inside a high-pressure container.
The heating furnace usually has a vertical cylindrical processing chamber, and a heating element is disposed surrounding the processing chamber. Since this heating furnace is operated under high gas pressure, it is more likely to cause temperature unevenness in the upper and lower directions compared to a heating furnace that is operated under normal atmospheric pressure. The heating element is divided and the temperature is controlled for each divided heating element. For this temperature control, a method is used in which a temperature sensor is provided in the processing chamber and the amount of power supplied to the heating element in each area is controlled based on the output of the temperature sensor, and a thermocouple is used as the temperature sensor.

Generally, an optical temperature measuring meter (such as a two-color high temperature type) is used in a heating furnace operated under atmospheric pressure, but this temperature measuring meter cannot be used in a hot isostatic pressurizing device. This is because a hot isostatic pressurization device has a heating furnace inside a high-pressure container, and in order to measure the temperature inside the heating furnace, it is necessary to provide a transparent window in the high-pressure container. However, it is difficult to achieve this under the current laws and regulations, and this method is virtually impossible.

Currently available thermocouples include chromel alumel type for low temperature range, platinum rhodium type (~1800°C) and tungsten rhenium type (~2200°C) for high temperature range. For low-temperature ranges, chromel-alumel-based sheath thermocouples are inexpensive and have a long life, making them practical; however, in high-temperature ranges around 2000°C, their lifespans are short and they are expensive, so hot isostatic pressure is recommended. Increases the processing cost of the equipment. Furthermore, thermocouples for use in high temperature ranges are not only expensive and have a short lifespan, but also their thermoelectromotive force values change significantly over time, especially in high temperature ranges. On the other hand, when using a thermocouple as a temperature sensor, an insulating material is not required. In the range of 1500 to 1600℃, alumina is used, and in temperatures above 1600℃, boron nitride (BN), beryllia (BeO), etc. are used, but beryllia is said to be harmful to living organisms, so it cannot be used at present. BN is an extremely high-performance insulating material. However, the insulation resistance of BN drops rapidly in the high temperature range of 1800°C or higher, and accurate measurements can only be made up to about 1800°C.

As is clear from the above, the drawbacks of the current high-temperature range temperature sensor (thermocouple) for a heating furnace for a hot isostatic pressurizing device are (1) that it is expensive; (2) It has a short lifespan. (3) in fact
It can only measure up to 1800℃ (there is no good insulation material). It is a point.

The present invention addresses the above-mentioned problems, and is to install an elongated cylindrical tube with its upper end closed in a vertical cylindrical heating furnace processing chamber, with the upper end placed inside the processing chamber and the open end on the opposite side placed outside the processing chamber. The measurement terminal of an optical thermometer is adjusted and attached to the open end of the tube so as to focus on the upper end of the tube, and the measurement terminal is placed in a high-pressure container surrounding each of the above sections. A conversion device was installed to convert the optical signal output from the terminal into an electrical signal, and the conversion device was connected to an automatic processing chamber temperature control device installed outside the high-pressure container via a lead wire that penetrated the high-pressure container. This relates to a temperature detection device for a heating furnace for a hot isostatic pressure heating device, and its purpose is to use an optical thermometer to detect temperatures of 1800°C or higher without impairing its durability. An object of the present invention is to provide an improved temperature detection device for a heating furnace for a hot isostatic pressurization device that can accurately measure temperature.

Next, the temperature detection device for a heating furnace for a hot isostatic pressurizing device of the present invention will be explained with reference to an embodiment shown in FIGS. 1, 2, 3, and 4.
is the yoke frame, 2 is the high pressure cylinder, 3 is the upper lid, 4
is the lower lid, 5 is the pedestal, 6 is the high-pressure cylinder moving cylinder, 7 is the upper lid gas seal, 8 is the lower lid gas seal,
9 is a heating furnace, 10 is a processing chamber (area within the broken line), 1
1 is a heating body (heater), 12 is a heat insulating layer, 13 is a hearth, 14 is a heating body power supply lead wire, 15 is a heating body power supply electrode, 16 is a pressurizing chamber, 17 is an upper section heating body, 18 is a 20 is a slender circular tube for temperature measurement in the lower section; 21 is an elongated circular tube for temperature measurement in the lower section; 22 is an optical terminal for temperature measurement in the upper section; 23 is an optical terminal for temperature measurement in the lower section; 24 is the upper section. 25 is an optical signal cable for the lower section, 26 is an electrical signal cable, 27 is an electrical signal cable seal portion, 28 is a power supply contactor, 29 is a contactor mount, 3
0 is a converter, 31 is a processing chamber temperature automatic control device, 32 is a thyristor control device, 33 is a gas supply nozzle, 34 is a power supply cable, and hot isostatic pressurization device 0 is fitted into the high pressure cylinder 2 and its upper and lower ends. A high-pressure container consisting of an upper lid 3 and a lower lid 4 that fit together, and a yoke frame 1 that supports the axial force generated in the upper and lower directions when gas is pumped into the pressurized chambers in these parts 2, 3, and 4; The heating furnace 9 is removably housed in the pressurized chamber, and the gas is
The gas is fed under pressure into the pressurizing chamber through a gas supply nozzle 33 from a device (not shown) such as a pressure booster. On the other hand, power is supplied to the heating furnace from the power supply cable 34 through the heating element power supply electrode 15. Also, the heating furnace 9
For removal from and import into a high-pressure container,
Operate the high-pressure cylindrical moving cylinder 6 in the expansion and contraction direction,
The high-pressure cylinder 2 is taken out from the yoke frame 1 (see the position indicated by the two-dot chain line in FIG. 1), and the test is carried out. In addition, the upper ends of the closed slender circular tubes (the slender circular tube 20 for the upper section and the slender circular tube 21 for the lower section) are arranged in the processing chamber 10, and the open end on the opposite side is used for temperature measurement. Optical terminals (terminal 22 for the upper section and terminal 23 for the lower section) are attached and placed outside the processing chamber 10, and the output signals from the optical terminals 22 and 23 are connected to an optical signal cable such as an optical fiber (upper section terminal 22 and lower section terminal 23). The optical signal installed in the pressurizing chamber 16 is inputted via the section cable 24 and the lower section cable 25) to a converter 30 that converts it into an electrical signal. The power is taken out of the high-pressure container and inputted to the thyristor control device 32 that controls the electric power of the heating element 11 (upper section heating element 17 and lower section heating element 18) via the processing chamber temperature automatic control device 31. Ward heating element 17,1
8 are controlled by respective temperature sensors.

The temperature detection device for a heating furnace for a hot isostatic pressurization device of the present invention is configured as described above, and can accurately measure the temperature of a desired location using an optical thermometer. In other words, when using an optical thermometer such as a two-color photothermometer in a hot isostatic pressurization device, it is necessary to focus on the location where the temperature is to be measured. It is best to place a solid body with a certain area and measure its temperature.

In the present invention, the slender circular tubes 20, 2 with closed upper ends
Attach optical terminals 22 and 23 to the opening end of 1,
The upper end is placed at the location where the temperature is to be measured in the processing chamber, the optical terminals 22 and 23 are focused on the upper end, and the slender circular tubes 20 and 2
The temperature of the upper end portion is measured from the lower side through the inside of 1 using optical terminals 22 and 23. At that time, high-pressure gas is violently convected in the processing chamber, and the delicate pressure distribution of the high-pressure gas causes refraction, making it difficult to accurately measure the temperature. The temperature measurement path is isolated from convection, allowing for accurate temperature measurement without the temperature measurement accuracy being degraded by convection. Another feature of the present invention is that the signal is extracted from the high-pressure container to the outside. That is, in order to extract signals from the high-pressure container to the outside, cables, lead wires, etc. must be sealed with high-pressure gas. On the other hand, in order to extract the optical signal to the outside, it is possible to use an optical fiber as a cable, but the optical fiber may be damaged during operation at the high-pressure gas sealing part, which poses a safety problem.
Furthermore, there are legal restrictions on the use of glass in high-pressure seals. However, in the present invention, the pressurizing chamber 16
Converter 3 that converts optical signals into electrical signals inside
0 (main body of the two-color photothermometer), and connect the optical terminal 22,
The optical signal output from 23 is input to the converter 30 via optical fiber optical signal cables 24 and 25, and after converting the optical signal into an electrical signal, this electrical signal is taken out of the high-pressure vessel. ,
The electrical signal cable may be a metal wire, and the seal part 27
It can also be handled with the same seal as in the case of the conventional thermocouple method.

Therefore, according to the temperature detection device for a heating furnace for a hot isostatic pressurization device of the present invention, it is possible to accurately measure temperatures of 1800°C or higher using an optical thermometer without damaging its durability. be.

A specific example of the temperature detection device of the present invention will be explained as follows. [Specific example ()] Using a graphite elongated circular tube, the maximum temperature is 2200
The temperature sensor was installed in a heating furnace for hot isostatic pressurization equipment with a maximum pressure of 2000 Kg/cm ² and a temperature of 2100°C.
A holding operation was performed for 2 hours at a pressure of 2000 Kg/cm ² and the practicality of the temperature sensor for controlling the heating element was confirmed. That is, it was confirmed that the fluctuation in the side temperature value due to the convection inside the circular tube, which was initially expected, stopped within 2 to 5 degrees Celsius at 2100 degrees Celsius. In addition, the phenomenon in which the lens of the optical terminal becomes cloudy also occurs when the optical terminal is in a low temperature area (~150℃).
This did not occur because it was placed in This temperature sensor is currently in use, and compared to thermocouples,
It is expected that the lifespan will be about 100 to 1000 times longer (as long as there is no damage to the slender circular tube or optical terminal lens), and the cost of hot isostatic pressure treatment in high temperature ranges will be lower. It is effective in reducing [Specific example ()] Using a molybdenum elongated circular tube, the maximum temperature is 1600
When tests similar to those in the specific example were conducted in a low-temperature heating furnace for hot isostatic pressurization at a maximum pressure of 2000 Kg/cm ² at a maximum pressure of 2000 Kg/cm 2 , similar evaluations of accuracy, life, etc. were obtained. In addition, tungsten, superalloy,
SUS, etc., alumina, zirconia, etc. in an oxidizing atmosphere, silicon carbide, etc. in a high-temperature furnace.
Various materials can also be used, such as silicon nitride.

[Brief explanation of the drawing]

Figure 1 is a side view showing a hot isostatic pressurizing device;
FIG. 2 is another side view, FIG. 3 is a vertical cross-sectional view showing an embodiment of the temperature detection device for a heating furnace for a hot isostatic pressurizing device according to the present invention, and FIG. 4 is a conversion device and a processing chamber thereof. FIG. 3 is a side view showing an automatic temperature control device portion. 1 to 4...high pressure container, 10...processing chamber, 20,
21...Elongated circular tube, 22, 23...Measurement terminal, 2
6... Lead wire, 30... Conversion device, 31... Processing chamber temperature automatic adjustment device.

Claims (1)

[Claims] 1 A slender circular tube with its upper end closed is placed in a vertical cylindrical heating furnace processing chamber so that the upper end is located inside the processing chamber and the open end on the opposite side is located outside the processing chamber, and the open end is located outside the processing chamber. A measurement terminal of an optical thermometer is attached to the end of the tube so that it focuses on the upper end of the tube, and the optical signal output from the measurement terminal is converted into an electrical signal in a high-pressure container surrounding each part. 1. A hot isostatic pressurizing device, comprising: a conversion device for converting into a high-pressure container, and the conversion device and an automatic processing chamber temperature control device provided outside the high-pressure container are connected via a lead wire that passes through the high-pressure container. Temperature detection device for heating furnaces.