JPS6362874B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-temperature hydrostatic pressure device, and more particularly to a method for controlling a heater that efficiently and responsively controls the temperature and power of an electric heater incorporated in a high-temperature, high-pressure container. .

High-temperature isostatic pressure equipment is increasingly being used in the industrial production field of cemented carbide, nickel-based superalloy aircraft parts, etc., but the heating equipment in this case generally uses an electric heater as an element. In most cases, the temperature inside the high-temperature, high-pressure vessel is controlled to a predetermined temperature by performing feedback power control in order to match the set temperature with the actual temperature.

However, depending on the material of the heating element of a heater installed in a high-temperature, high-pressure container, the power surface load density of the heater element increases in a high-temperature atmosphere, resulting in creep deformation, evaporation of alloy components, element wear, and Accidents such as melting due to these things occur, so in practical terms, it is necessary to operate while ensuring a sufficient lifespan, and there is a natural limit to the input power, which causes the temperature to rise quickly. It is not permissible to input more power than necessary.

However, in general-purpose feedback power control, depending on the difference between the set temperature (target temperature) and the actual temperature (temperature feedback signal), the heater receives the maximum power determined by its impedance and power supply. There is a good chance that
Since this maximum power may reach a dangerous range that is considered undesirable in terms of heater life, special measures must be taken to control the heating of the electric heater.

From this point of view, the present applicant previously filed a patent application filed in 1983 for a control method for electric heaters that extends the life of the electric heater and controls the electric heater so that maximum heating capacity is exhibited within the above-mentioned limitations.
This was proposed in No. 9256.

In this method, as shown as a block circuit in FIG. 2, a target time/temperature value is given by a program temperature setter 7, and this signal and a thermocouple temperature sensor 4 installed in a high-temperature, high-pressure vessel 1 are detected. The electric power input to the heater 2 is controlled based on the deviation signal obtained by comparing the signal corresponding to the actual execution temperature. When the maximum input power to the heater 2 reaches a limited range, temperature control is performed while suppressing the heater input power within the range of the value set by the maximum input power setting device 8. The purpose of can be achieved.

However, since the method according to FIG. 2 also includes a priority circuit 17 that switches between normal temperature control and power control with power limitation depending on the temperature range, the method shown in FIG. In such a power control range, the accuracy of temperature control is poor, and it is difficult to guarantee whether the temperature inside the high-temperature, high-pressure container is correctly set to a predetermined temperature.

In view of the above-mentioned problems with the control method proposed earlier, the present invention provides heating control for heaters that can complement these problems and is efficient and responsive. This has been done to provide an improved method for performing

However, in order to achieve the above object, the present invention has the following features:
In particular, it is necessary to compare the set temperature from the program temperature setting device, which presets the heating pattern to give the relationship between temperature and time inside the high-temperature and high-pressure vessel, and the actual temperature (detected temperature) inside the high-temperature and high-pressure vessel. a first power control circuit that issues a command corresponding to the power;
The former command is connected to a second power control circuit that outputs a command according to the maximum input power for the detected temperature by a maximum input power setting device that presets the relationship between the maximum allowable input power and the temperature of the heater. The set power obtained by the second power control circuit is compared with the detected power, and the deviation signal is inputted to the power supply section to control the heating heater. It is characterized by a method in which the power supplied to the vessel is cascade-controlled by temperature control commands within the range of the maximum allowable input power, and temperature control is always performed regardless of the temperature range to which the actual temperature inside the high-temperature and high-pressure vessel belongs. This makes it possible to work together with power control.

Hereinafter, examples of the present invention will be described in detail based on drawings illustrating a specific apparatus for carrying out the method of the present invention.

In FIG. 1, 1 is a high temperature and high pressure vessel,
A heater 2 that receives controlled power from a power supply section 9 is built in, and an inert gas such as argon is sealed under high pressure as a pressure medium to heat the accommodated workpiece (not shown) at high temperatures. A high temperature hydrostatic device is formed that processes under hydrostatic pressure.

This high-temperature, high-pressure container 1 is equipped with a temperature sensor 4 such as a thermocouple so that the temperature inside the container 1 can be actually measured.

The power supply section 9 includes a thyristor 14 whose phase angle is controlled by a thyristor gate control device 10.
It is formed so as to be able to supply the required electric power to the heater 2 via the transformer 16.

The high-temperature hydrostatic pressure device is provided with four circuits, a power detection circuit, a temperature detection circuit, a first power control circuit, and a second power control circuit, in connection with the power supply section 9. The control system controls the power supplied from the power supply unit 9 to a predetermined value.

The power detection circuit includes a detection section 3 consisting of a current transformer 5 that detects the current flowing through the heater 2 and a voltage transformer 6 that also detects the applied voltage, and a current value and a voltage value obtained by the detection section 3. A power converter 1 calculates the actual power value of the heater 2 by integrating the values, converts it into a power signal _e2 of an appropriate value, and outputs the power signal e2.
The power signal e ₂ is input to the comparator 11.

On the other hand, the temperature detection circuit is composed of a temperature sensor 4 as a detection section, and a temperature converter 13 that converts the detected value of the sensor 4 into an amount of electricity proportional to the temperature and outputs it as a temperature signal _e1 . , the temperature signal
e ₁ is configured to be input to the first power control circuit.

The first power control circuit includes a program temperature setting device 7;
A command signal issued from the programmed temperature setting device 7, which includes the temperature controller 15 as an element and can preset a heating pattern P for giving a relationship of temperature change with respect to time in the high-temperature/high-pressure container 1. After comparing the temperature signal e ₃ with the temperature signal e ₁ from the temperature detection circuit, the temperature controller 15 outputs a command signal e ₄ corresponding to the required power and inputs it into the second power control circuit.

On the other hand, the second power control circuit is a command circuit including a maximum input power setter 8 and a power regulator 11, and separates a dangerous area that adversely affects the life of the heater 2 from other safe areas. The maximum input power setting device 8 is capable of presetting the relationship between the maximum allowable input power and the ambient temperature of the heater 2 based on the input power-temperature diagram.
When the command signal e ₄ is input to the input device, a setting signal e ₅ matching the allowable maximum input power corresponding to the temperature at that time is generated, and this setting signal e ₅
and the power signal e ₂ are matched by the power regulator 11 to produce a command signal e ₆ of the thyristor gate control device 10.
is now output.

In this way, the first power control circuit and the second power control circuit are connected in cascade such that the command signal _e4 of the former can determine the setting signal _e5 of the latter, and the input power is controlled by the temperature control command. cascade control.

To describe the heating control method according to the present invention using the heater control system configured as described above, when the temperature inside the high-temperature and high-pressure vessel 1 is lower than the set value (e ₃ > e ₁ ),
When the temperature of the heater 2 does not reach the dangerous temperature range of the heater element, the maximum input power setting device 8
outputs a proportional signal whose value is not suppressed, which becomes the setting signal e ₅ and compares it with the detected power signal e _2. The deviation signal e ₆ corresponds to the maximum power determined by both the impedance of the power supply and the heater element. As a result of inputting the command signal to the thyristor gate control device 10, the maximum electric power is applied to the heater 2, and temperature control is performed to quickly raise the temperature to the target value.

When the temperature inside the high-temperature, high-pressure container 1 rises due to the heater 2 and reaches a region where the maximum input power to the heater 2 is restricted, the maximum input power setting device 8 sets the temperature based on the input power-temperature diagram. A signal suppressed to a predetermined value is output, which becomes the setting signal _e5 , and therefore, the comparison deviation signal _e6 contains a value that limits the input power to the range of the maximum allowable input power value at the temperature at that time. is input to the thyristor gate control device 10 as a command signal corresponding to the command signal.

As a result, temperature control is performed by applying the maximum allowable power within a range that does not shorten the life of the heater 2.

In this way, it is possible to appropriately perform normal temperature control by supplying maximum power and power control with power limitation and temperature control, depending on the temperature situation at the time, and it is possible to always maintain temperature control. Accuracy is now guaranteed.

As is clear from the above description, the present invention has the following features:
Regardless of the height of the temperature range to which the actual temperature inside the high-temperature/high-pressure container 1 belongs, cascade control is performed that allows temperature control and power control to always operate in parallel. It is possible to control the temperature so that the target value can be quickly reached while avoiding excessive input power that can lead to a short lifespan.
It is possible to prevent the heater element of the heater 2 from deteriorating and melting, thereby extending the life of the heater to the maximum extent, resulting in significant improvements in terms of management and operating costs.

Moreover, since the electric power of the heater 2 is controlled so that its maximum capacity is exhibited while taking into account the lifespan, the atmospheric temperature inside the high-temperature and high-pressure vessel 1 is controlled with a small time delay, and therefore the loss is reduced. In addition, since temperature control is performed at the same time, strict temperature control is possible and highly accurate operation is guaranteed.

[Brief explanation of drawings]

FIG. 1 is an electrical system diagram for controlling the heater of a high-temperature hydrostatic pressure device according to the method of the present invention, and FIG. 2 is an electrical system diagram for controlling the heater of a high-temperature hydrostatic pressure device according to the conventional method for controlling the heater. . 1... High temperature and high pressure container, 2... Heater, 7... Program temperature setting device, 8... Maximum input power setting device, 9
...Power supply section.

Claims (1)

[Claims] 1 In a high-temperature hydrostatic pressure device that hydrostatically processes a workpiece using an inert gas as a pressure medium in a high-temperature, high-pressure container 1 in which a heating heater 2 that receives controlled power from a power supply section 9 is built-in, the heating Heater 2
a circuit for detecting the electric power supplied to the high-temperature high-pressure vessel 1, a circuit for detecting the temperature inside the high-temperature high-pressure vessel 1, and a program temperature setting that presets a heating pattern for giving a relationship of temperature to time inside the high-temperature high-pressure vessel 1. A first power control circuit that compares the set temperature from the heater 7 with the detected temperature and outputs a command corresponding to the required power, and the relationship between the maximum allowable input power and the temperature of the heater 2 are set in advance. A second power control circuit that outputs a command according to the maximum input power with respect to the detected temperature is provided by the maximum input power setting device 8 in relation to the power supply section 9, and a A cascade connection is made to the second power control circuit so that the set value of the latter can be determined by the command of the former, and the set power obtained by the second power control circuit is compared with the detected power. A method for controlling a heater, characterized in that a deviation signal is input to the power supply section 9, and the power supplied to the heater 2 is controlled in cascade according to a temperature control command within the range of maximum allowable input power.