JPH04126993A - Deciding method for deterioration of adiabatic layer of hot isotropic pressurizer - Google Patents

Abstract

PURPOSE:To eliminate means for measuring electric to be applied to a heater and to decide aging deterioration of an adiabatic layer by calculating a furnace chamber temperature drop time constant from a temperature in a furnace chamber and a measuring time point, and deciding deterioration of the layer. CONSTITUTION:Pressure medium gas is heated by a heater 4 in a furnace chamber 3, high temperature and high pressure medium gas is operated at a material 5 to be treated, and treated. A thermocouple 6 for measuring the temperature in the furnace chamber is connected to a thermoelectric converter 7, and a thyristor 8 controls power to be applied to the heater 4 through a transformer 9. A temperature regulating meter 11 has a comparator 12, a PID controller 13, compares a set temperature from a temperature setter 10 with a measured temperature from the converter 7, and so controls the thyristor 8 through a thyristor control unit 14 that the temperature in the furnace becomes the set temperature. A calculator 16 measures the temperature in the chamber 3 at a plurality of time points by the thermocouple 6 after the material 5 is completely treated, a furnace chamber temperature drop time constant is calculated from the measured temperature in the chamber 3 and the measured time, and when the time constant becomes a predetermined value or less, it is decided as the deterioration of an adiabatic layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for determining deterioration of a heat insulating layer of a hot isostatic pressurizing device.

(Prior art) High-pressure pressure gas is charged into a high-pressure container, a heat insulating layer is placed inside the high-pressure container to form a furnace chamber, and the pressure gas is heated by a heater placed inside the furnace chamber. There is a hot isostatic pressurizing device (hereinafter referred to as a HIP device) that processes a workpiece placed in a furnace chamber by applying high temperature and high pressure pressure medium gas.

Conventionally, as a method for determining the deterioration of the heat insulating layer of an HTP device, the steady-state holding power of the heater is recorded for each operation, and the deterioration of the ρ1 layer is determined from the change. That is, as shown in FIG. 5, the steady state holding power refers to the heater input power that becomes approximately constant within 30 to 60 minutes from the start of maintaining the temperature and pressure. In other words, it is the power input to the heater immediately before the heater is turned off. This steady-state holding power varies depending on the processing conditions (temperature and pressure holding conditions), but if the processing conditions are the same, it will be a substantially constant value regardless of the presence or absence of a workpiece.

When the heat insulating layer deteriorates, the steady-state holding power tends to increase, as shown in FIG. 6, even under the same processing conditions. Therefore, deterioration of the heat insulating layer can be determined from the change in the steady state power.

(Problems to be Solved by the Invention) In order to automate the conventional determination of deterioration of a heat insulating layer based on changes in steady state power, a means for measuring the power input to the heater is essential. Physically, if enough time passes while maintaining the temperature and pressure, the heat balance becomes steady and the power value becomes approximately constant.

However, depending on the setting of the temperature holding time, for example, if the holding time set for the time constant of the furnace (including the product to be processed) is short, the electric power will be reduced to a constant value of 5. Even so, it is quite possible that the furnace is not in a steady state. The apparent steady power at this time is not necessarily the power value in the steady state of the furnace.

Therefore, since the steady state holding power is not the true steady state holding power when the holding time is short, even if deterioration is determined based on the transition of this power, the determination accuracy is not accurate.

In view of these conventional problems, the present invention provides an HIP device that can determine the power input to the heater without requiring a means to measure it, and can reliably determine the correct value even if the processing conditions change. The purpose of this invention is to provide a method for determining a heat insulating layer.

(Means for Solving the Problems) The present invention, as a first means for achieving this purpose, introduces a high-pressure pressure medium gas into a high-pressure vessel 1, and arranges a heat insulating layer 2 inside the high-pressure vessel 1 to provide a furnace chamber. 3, heat is applied to the workpiece 5 placed in the furnace chamber 3 by heating the pressure gas with the heater 4 placed in the furnace chamber 3, and the heat is applied to the workpiece 5 placed in the furnace chamber 3 with high-temperature, high-pressure pressure gas. In the method for determining the deterioration of the heat insulating layer of the isostatic pressurizing device, when the temperature in the furnace chamber 3 is lowered after the processing of the workpiece 5, the temperature inside the furnace chamber is measured four times at a plurality of times, A furnace chamber temperature drop time constant is calculated from the measured temperature in the furnace chamber 3 and the time when the four measurements were made, and the calculated furnace chamber temperature drop time constant is equal to or higher than a predetermined value. In some cases, it is determined that the heat insulating layer 2 has deteriorated (deterioration determination method described as step ① [phase] in FIG. 4).

Further, the present invention provides, as a second means, a high-pressure pressure medium gas is introduced into the high-pressure vessel 1, and a heat insulating layer is placed inside the high-pressure vessel 1.
A heater placed in the furnace chamber 3 heats the pressure medium gas to apply high-temperature and high-pressure pressure medium gas to the workpiece 5 placed in the furnace chamber 3. In a method for determining deterioration of a heat insulating layer of a hot isostatic pressing device that performs processing by
When the temperature in the furnace chamber 3 is lowered after the processing of the workpiece 5 is finished, the temperature in the furnace chamber 3 is measured at a plurality of points, and the temperature in the furnace chamber 3 is calculated based on the total temperature in the furnace chamber 3. The calculation process for calculating the furnace chamber temperature drop time constant from the time is performed multiple times, and the furnace chamber temperature decrease time constant of each calculated time is determined in advance as It is determined that the heat insulating layer 2 has deteriorated when the value has changed to 2 (deterioration determination method described as step @ [phase] in Fig. 4).
.

(Example) Hereinafter, the example of the present invention will be described in detail based on the drawings.
In the figure, reference numeral 1 denotes a high-pressure vessel, into which a high-pressure pressure medium gas is introduced, and a heat insulating layer 2 is arranged to form a furnace chamber 3.
That's what I'm saying. Reference numeral 4 denotes a heater placed in the furnace chamber 3. By heating the pressure medium gas by this heater 4, the high temperature and high pressure pressure medium gas is applied to the workpiece 5 placed in the furnace chamber 3 to perform processing. It looks like this. Reference numeral 6 denotes a thermoelectric pair for measuring the temperature inside the furnace, which is connected to a thermoelectric converter 7. Reference numeral 8 denotes a cyrisk, which is used to control the electric power input to the heater 4 via the transformer 9. 10 is a temperature setting device for setting the temperature inside the furnace, 11 is a temperature controller, a comparison section 12, a PID
The control unit 13 compares the set temperature from the temperature setting device 10 and the measured temperature from the thermoelectric converter 7, and controls the thyristor 8 via the thyrisk control unit 4 so that the temperature inside the furnace becomes the set temperature. configured to control. 15 is A
/D converter for converting the furnace temperature signal into a digital signal. 16 is an arithmetic unit, which is a processing unit 5
After the completion of the second process; when lowering the temperature in the furnace chamber 3,
As shown in the figure, the temperature decrease characteristic B of the deterioration 8 of the heat insulating layer 2 is larger than the initial temperature decrease characteristic A.
, B is used to determine the deterioration of the heat insulating layer 2. That is, this measures the temperature in the furnace chamber 3 at multiple points in time using a thermocouple 6, calculates the furnace chamber temperature drop time constant T from the furnace chamber temperature and the measurement time, and calculates the furnace chamber temperature drop time constant T from the furnace chamber temperature and the measurement time. When the constant becomes less than a predetermined value, or when the calculation process is performed multiple times, the furnace room temperature drop time constant T of each time becomes a predetermined value compared to the furnace room temperature drop time constant of other times. When the above changes occur, it is determined that the heat insulating layer 2 has deteriorated.

The furnace room temperature drop time constant T is calculated as follows. Now, ui i=o, 1,...N: Measured temperature inside the furnace (uo: temperature inside the furnace when the heater is turned off) T
: Furnace chamber temperature drop time constant, i-0,1,...N: Measurement time (to
= 0), the temperature drop curve in the furnace chamber 3 is as follows.

ui +lJo・−ν −−−−−[phase] [phase]
U on both sides of the equation. Divide by and then take the logarithm of both sides, N, (-)−−1・−=−−−−−−−−−■uo
It becomes T.

Here, αr = 42(-) 1=1,...
・, NT-β, then α1-β1 + −−−−0. That is, β is determined as the slope of the linear relationship between α3 and L.

Therefore, the collected data (α, 1.) is subjected to linear regression using the method of least squares, and its slope β and further T can be determined.

Note that the linear regression method is not limited to the least squares method, and other methods may be used.

Further, the time constant T can be found by taking two points, but since there is a measurement error, it is actually desirable to take about the IO point.

Next, the operation will be explained with reference to the flowcharts of FIGS. 3 and 4. When the temperature in the furnace chamber is lowered after the processing of the workpiece is completed, when a heater off pulse signal is received as a sequence signal from the temperature setting device 10 (step ■), the thermocouple 6 and thermoelectric converter 7 Measure the temperature inside the
Start collecting the temperature drop data (step ■). Note that this data collection may be performed immediately after the start of the temperature drop, but since the pressure medium gas in the furnace chamber 3 is removed after a while after the start of the temperature drop, it is possible to collect this data from the start of the temperature drop. It may be started after a certain amount of time has elapsed. First, the temperature U inside the furnace chamber 3 when the heater is turned off. After measuring Δ (step ■), measure the temperature in the furnace chamber 3 at that point several times every time Δ elapses, and measure the temperature (step ■■
). Then, when the number of measurements reaches a value sufficient for calculation using the least squares method (step ■), the time constant T of the furnace room temperature below the knee is determined from the data of the furnace room temperature at each measurement time and the measurement time.
Calculate (step ”■).

On the other hand, ΔTm of the furnace chamber temperature drop time constant 'F, ]×, Tm1
n1lle are determined in advance (step (2)), and the calculated constant TJ is compared with them to determine the deterioration of the heat insulating layer 2 by 1']1. For example, if the time constant is predetermined
If it is smaller than the m1n value, it is determined that there is an abnormality in the heat insulating layer 2 (step ■ [phase]). It should be noted that the abnormality determined in this step (2) [phase] is the deterioration of the heat insulating layer 2 over time.

Also, find the difference ΔT=IT, -Tj-+l between the time constant TJ of each time and the previous time constant T, -1 (step ■
), if the value ΔT changes to become larger than a predetermined ΔTmax, it is determined that the heat insulating layer 2 is abnormal (step @[phase]). On the other hand, the abnormality determined in this step @■ is a sudden deterioration such as damage to the heat insulating layer 2, unlike the abnormality determined in step ■ [phase]. and,
When it is determined that there is an abnormality, an alarm is displayed, etc.

In addition, although the linear regression by the least squares method was explained as an example in the embodiment, the present invention is not limited to this.

Also, due to issues such as accuracy, in practice it is preferable to measure the temperature multiple times and take the average, but theoretically, if the temperature at two or three points at different times is deviated by 1, the temperature will drop. It is possible to determine the constant 'F.

In this case, for each temperature at 2 or 3 points, do not use the temperature measured once, but calculate the average value of the temperature measured 2 or 3 times before and after each point. Each average value may be used as the temperature at each time point. Furthermore, the temperature drop time constant T expressed as the denominator of the exponential part of the exponential function may be calculated using other mathematical methods, such as using another linear regression method.

Furthermore, when measuring the temperature, the temperature drop time constant changes when the article 5 is inserted, so it is necessary that the article 5 be in a stable state.

Therefore, it is particularly effective when processing the same product repeatedly or when switching between multiple furnaces. Note that when replacing the furnace, dry firing is always performed to remove moisture, so the data from this time can be used.

(Effects of the Invention) According to the present invention as claimed in claim (1), the deterioration of the heat insulating layer is determined by calculating the time constant of temperature drop in the furnace chamber from the temperature in the furnace chamber and the time of its measurement, so that it is possible to determine the deterioration of the heat insulating layer. This method has the advantage that the deterioration of the 1lIi thermal layer over time can be determined without requiring a means for measuring the power input to the heater, and that the determination accuracy can also be accurate.

According to the present invention according to claim (2), sudden abnormal deterioration of the heat insulating layer can be determined.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing changes in temperature drop characteristics, Fig. 3 and Fig. 4 are flowchart 1, and Fig. 5 is a conventional example. The characteristic diagram, FIG. 6, is a record of the constant state holding power. 1... High pressure vessel, 2... Heat insulation layer, 3... Furnace chamber, 4
...Hitor, 5...Processed product, 16...Arithmetic device. -ka skin q]

Claims (2)

[Claims] (1) Introducing high-pressure pressure medium gas into the high-pressure container (1), and placing a heat insulating layer (2) inside the high-pressure container (1) to create a furnace chamber (
3) By heating the pressure medium gas with the heater (4) placed in the furnace chamber (3), high temperature and high pressure pressure medium is applied to the workpiece (5) placed in the furnace chamber (3). In a method for determining deterioration of a heat insulating layer of a hot isostatic pressurizing device that performs processing by applying gas, when lowering the temperature in the furnace chamber (3) after the processing of the processed product (5), Measure the temperature in the furnace chamber at multiple points in time, calculate the furnace chamber temperature drop time constant from the measured temperature in the furnace chamber (3) and the time of the measurement, and calculate the calculated furnace chamber temperature drop time constant. A method for determining deterioration of a heat insulating layer of a hot isostatic pressurizing device, characterized in that it is determined that the heat insulating layer (2) has deteriorated when a constant becomes equal to or less than a predetermined value. (2) Introducing high-pressure pressure medium gas into the high-pressure container (1), and arranging a heat insulating layer (2) inside the high-pressure container (1) to create a furnace chamber (
3) By heating the pressure gas with a heater placed in the furnace chamber (3), high temperature and high pressure pressure gas is applied to the workpiece (5) placed in the furnace chamber (3). In a method for determining the deterioration of a heat insulating layer of a hot isostatic pressurizing device that performs processing, the temperature in the furnace chamber (3) is lowered at multiple points in time after the processing of the product to be processed (5) is completed. , the temperature inside the furnace chamber (3) is measured, and the calculation process of calculating the furnace chamber temperature drop time constant from the measured temperature inside the furnace chamber and the time of the measurement is performed multiple times. Heat insulation layer (2) is determined to have deteriorated when the time constant of temperature drop in the furnace chamber changes by a predetermined value or more compared to the time constant of temperature drop in the furnace chamber at other times. A method for determining deterioration of a heat insulating layer of an isostatic pressurizing device.