JPS62163936A - Measuring method for temperature in furnace of hot isostatic pressing unit - Google Patents

Abstract

PURPOSE:To enable more accurate and stable measurement of temperature, by selecting a temperature measuring wavelength not subjected to absorption by a low boiling point metal beforehand to measure the temperature by the wavelength. CONSTITUTION:A radiation light at the tip of an end-closed pipe is focused by an optical system 1 and the wavelength other than the absorption wavelengths of a low melting point metal is selected by a filter 2, then, the wavelength is transmitted through an optical fiber or the like and converted into electricity by a signal processor 4 to output a temperature. This eliminates overlapping of the absorption with a temperature measuring wavelength even in the presence of a gas of a low boiling point metal. Therefore, correct temperature measurement is possible regardless of glass for a processing capsule in the furnace.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for measuring the temperature inside a furnace of a hot isostatic pressure (hereinafter abbreviated as HIP) device, particularly for use in temperature measurement. This invention relates to a method for measuring the temperature inside the furnace of the above-mentioned HIP apparatus, which has been improved in the wavelength range.

(Prior art) HIP equipment is a device that uses the synergistic effect of high temperature and high pressure to perform pressure sintering of powder, removal of defects in sintered and forged products, and diffusion bonding. Its industrial use has been attracting attention, and recently its application has expanded to high-temperature overheads of 1700° C. to 2100° C. for engineering ceramics.

By the way, temperature control inside the high-temperature, high-pressure furnace in such equipment is extremely important for processing effectiveness, and therefore various temperature measurement means are installed to detect the temperature inside the furnace, and currently closed-end tubes are used. There has been talk of adopting radiation temperature measurement methods using this method.

FIGS. 4 and 7 show each side of a known HIP apparatus provided with such means for measuring the temperature within the furnace.

That is, FIG. 4 uses a closed-end tube (15) and an optical fiber (16), and places the closed-end tube (15) on the lower M (13) of a high-pressure container (11) containing a heat insulating layer (12). HIP with sample stand (14) installed! The tube is installed so that its tip is located at the area to be measured in the furnace chamber defined by the heat insulating layer (12), and the heat radiation from the closed-end tube is transmitted through the optical fiber (16) at the bottom of the closed-end tube. A device led outside the furnace and connected to a measurement system consisting of a radiation thermometer (17) (Japanese Patent Laid-Open No. 60-13332)
(Refer to Publication No. 7) In order to introduce the emitted light from the closed-end tube (15) into the optical fiber (16), there is a method of directly inputting it into the optical fiber (16) as shown in Fig. 5, or a method as shown in Fig. 6. There is a method of focusing light onto an optical fiber (16) using a collimator (20) using a lens (19).On the other hand, Fig. 7 shows a method of focusing the light onto an optical fiber (16) using a collimator (20) using a lens (19). Install the circular tubes (30) (31) so that their upper ends are located outside the processing chamber, and connect the measurement terminals (32) (33) of the radiation thermometer to the open ends of the elongated circular tubes (30).
(31) Adjust and attach it so that the focus is on the upper end, and guide it through the measurement terminals (32) and (33) to the temperature converter (36) in the HIP device, thereby transmitting an output corresponding to the temperature to the high-pressure container. The processing chamber temperature automatic control device (38) is taken out to the outside via the lead wire (37)
The upper and lower heaters (4) are controlled by the Cyrisk control device (39), etc.
0) A device designed to control (41) (Unexamined Japanese Patent Publication No. 6
0-144627).

By the way, in the above-mentioned temperature measurement method, in which the emitted light from the tip of the closed-end tube is directly incident on the optical fiber, the closed-end tube (15
) Thermal radiation from the side wall enters, which is added to the thermal radiation from the tip, causing an error in temperature measurement at the tip.

Therefore, means to eliminate such errors were investigated, and as a result of experiments, it was found that if the detection wavelength was set to 0.6 μm or less, it was possible to suppress the temperature measurement error in the vicinity of 2000° C. to 1% or less. However, this does not apply when the field of view is limited to the tip of the closed-end tube using a collimator or the like.

However, on the other hand, although the temperature measurement error decreases as the wavelength becomes shorter, there is a limit on the short wavelength side due to limitations of optical materials, and 0.
It was found that it is difficult to detect a particle size of 2 μm or less, and that a particle size of 0.3 μm or less is suitable.

Moreover, as a result of calculating the wavelength dependence of temperature resolution for a target of 1000°C with a time constant of 1 second on the premise that a photon counting method using a photomultiplier tube (PM) is used, in order to make the temperature resolution higher than IK, It was also found that the thickness must be 0.3 μm or more.

Therefore, from these points, the specific detection wavelength of the radiation thermometer is actually in the range of 0.3 μm to 0.6 μm, however, if the field of view is limited to the temperature measurement point using a collimator etc., it will exceed 0.3 μm. The temperature is measured as a range of .

However, there is no mention of the spectral characteristics of the synchrotron radiation used for temperature measurement, other than that it is a black body or a gray body.

Therefore, when the radiation light from an actual HIP device is spectrally analyzed, clear absorption is observed as shown in FIG. This is absorption caused by low-boiling metals evaporated from the furnace-processed materials or capsule glass in the HRP equipment, but this is because low-boiling metals are evaporated from the inside of a high-temperature closed container like the HRP equipment. If there is, the low-boiling metal will evaporate during the temperature rise and become a gas, which will float inside the container without being discharged from the container.

Therefore, when performing radiation temperature measurement, absorption occurs by the metal gas present in the optical path between the temperature measurement target point and the collimator.

However, conventional temperature measurement methods do not assume temperature measurement under conditions where absorption occurs as described above, and the wavelengths used for metal gas absorption and temperature measurement may overlap, resulting in large errors.

(Problems to be Solved by the Invention) The present invention deals with the actual situation such as ridges, and specifically aims to eliminate the above-mentioned defects by selecting the temperature measurement wavelength and to enable more accurate and stable temperature measurement. This is the purpose.

(Means for Solving the Problems) That is, the present invention, which is compatible with the above objects and achieves the effects, is characterized in that, in the temperature measuring method of the HIP device as described above, in particular, the absorption of low boiling point metals is The purpose of this method is to select a temperature measurement wavelength that avoids this and perform temperature measurement at that wavelength.

Of course, the temperature measurement wavelength is 0.3 μm to 0.6 μm as mentioned above.
Needless to say, if the field of view is limited to the temperature measurement point using a collimator, etc., it is in the range of 0.3 μm or more, and it is important to select a wavelength that is beyond the absorption of low boiling point metals. This is easily accomplished by using a filter and setting its transmission wavelength range to a wavelength range other than the absorption wavelength of the low boiling point metal.

(Function) As mentioned above, by selecting a wavelength that avoids the absorption of low-boiling point metals and measuring the temperature, even if there is vaporized low-boiling point metal gas in the HIP device, its absorption is avoided, and the closed-end pipe The emitted light from the tip is accurately received and accurate measurements are performed.

(Example) Hereinafter, specific embodiments of the temperature measuring method according to the present invention will be further described based on the accompanying drawings.

FIG. 1 is a schematic diagram of an optical system related to the temperature measurement method of the present invention,
(1) is a condensing optical system such as a collimator, (2) is a filter, (3) is a light receiving unit, and (4) is a signal processing device. After concentrating the light in (1) and selecting a wavelength other than the absorption wavelength of low-boiling point metals in filter (2), the wavelength is transmitted through an optical fiber (not shown), etc., and photoelectrically transmitted by signal processing device (4). The conversion is performed and the temperature output is used for temperature display or heater control as required.

It is an important point of the present invention that the wavelength is determined by the filter (2) in the above process, and the absorption wavelength of the low boiling point metal to be avoided here is determined as follows.

(b) Select a metal that evaporates at the expected usage temperature.

(II) Since the majority of atoms are in the ground state at a temperature comparable to that of a HIP device (~2500K), a spectral wavelength that is excited from the ground state is selected.

etc.

Further, there is no particular limitation on the temperature measurement method, and any means may be used as long as it avoids absorption wavelengths as described above.

In the above embodiment, filter (2) is used, but since the filter cannot be selected in the case of a spectroscopic thermometer, a table (6) of absorption wavelengths must be stored in advance as shown in Fig. 2. , the data corresponding to the absorption wavelength may be removed.

In this case, it is possible to skip wavelength scanning.

In the figure, (5) indicates a spectrometer.

In this way, even if a low boiling point metal gas is present, temperature measurement can be performed without being affected by the metal gas.

(Effects of the Invention) As described above, the present invention avoids the absorption wavelength of low boiling point metals in measuring the temperature inside the furnace of a HIP device, and measures the temperature at other wavelengths. Conventionally, the presence of gases caused by evaporation of metals overlaps with absorption depending on the temperature measurement wavelength range, reducing the incoming radiant energy and causing temperature measurement errors. The absorption does not overlap with the temperature measurement wavelength even if the temperature is measured. Therefore, accurate temperature measurement is possible that is unaffected by the presence of gas and is independent of the glass for the furnace processing capsule, etc., and the temperature measurement accuracy of the HIP device is improved. It is expected that this method will have a significant effect on improving industrial performance and promoting the industrial use of this equipment.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams showing the main parts of the temperature measurement method of the present invention, Figure 3 is a closed-end tube emitted light spectral distribution chart, and Figure 4 is an example of a HIP device to which the temperature measurement method of the present invention is applied. A cross-sectional schematic diagram showing
5 and 6 are schematic diagrams of each optical system used in the device shown in FIG. 3, and FIG. 7 is a schematic diagram of main parts showing another example of an F (IP device) to which the method of the present invention is applied. (1)... Optical system. (2)... Filter. (3)... Light receiving section. (4)... Signal processing device. (5)... Spectrometer. (6)... ...Absorption wavelength table. Patent applicant Kobe Steel, Ltd., 2. - Agent Patent attorney Yasushi Miyamoto -'-゛・, -1-2
・' Capital 1 concave lip 2 Aoi 3 figure Ryocho (n?n) between y Aishikan g elbow cursor Imaichi Hana 4 figure

Claims (1)

[Claims] 1. Install a closed-end tube in the high-pressure furnace of the hot isostatic pressurization device,
In this method, the thermal radiation at the tip of the closed-end tube is focused by an optical system and guided to a signal processing device to measure the temperature inside the furnace. 1. A method for measuring the temperature inside a furnace of a hot isostatic pressurizing device, which avoids the wavelength at which absorption occurs and measures the temperature at a detection wavelength other than that.