JPH01250115A - Temperature controller for electric furnace - Google Patents

Abstract

PURPOSE:To keep the temperature of a processing object at a fixed level by changing the set temperature value according to the processing objects. CONSTITUTION:An mV generator 3 subtracts about 99% electromotive force from the electromotive force generated by a master thermocouple 2 set approximate to a processing object X. Then the subtracted electromotive force is amplified by a DC amplifier 4. Based on this amplified electromotive force, a temperature controller 5 changes the set temperature value or decides whether rise or the fall of the temperature. The relevant signal is sent to a programmable controller 6 for selection of the temperature rising/falling speeds set previously and the held temperatures. Then a temperature controller 7 for PID control increases/reduces the set temperature level or keeps this. The temperature of a a thermocouple 8 set at the side of a heater 9 of an electric furnace 1 is controlled based on the controller of the controller 7. As a result, the set temperature value is changed according to the object X and the temperature of the object X is kept at a fixed level.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an apparatus for controlling temperature in an electric furnace in accordance with a process object.

(Conventional technology and its problems) When processing materials in an electric furnace, in normal production equipment, the heat capacity of the electric furnace must be increased due to the relationship with the throughput or to obtain stability of the furnace. are doing.

If an electric furnace has a large heat capacity, it will overshoot when trying to reach the target temperature in a certain amount of time.

Also, if you try to avoid overshoot, the target temperature will not be reached within a certain amount of time.

For this reason, control is performed using PID values in order to avoid overshoot, minimize hunting, and precisely control the electric furnace temperature.

However, even when the set value is the same, the actual temperature usually differs depending on the amount of heat stored in the furnace, and the temperature set value must be changed in order to maintain a constant temperature.

(Purpose of the Invention) The present invention was made to solve the above-mentioned problems, and is an electric furnace for controlling the temperature of an electric furnace by changing the temperature set value according to the material to be processed and keeping the material temperature constant. The object of the present invention is to provide a furnace temperature control device.

(Means for Solving the Problems) The electric furnace temperature control device of the present invention for solving the above-mentioned problems includes a master thermocouple provided close to the workpiece in an electric furnace, and a master thermocouple connected to the master thermocouple. an mV generator that is connected in a pair and subtracts about 99% of the thermoelectromotive force from the electromotive force generated by the master thermocouple; a DC amplifier that is connected to the mV generator and amplifies the subtracted electromotive force; A temperature controller that determines the temperature state near the processed material with respect to the temperature set value using a connected and amplified electromotive force and outputs a signal; A programmer full controller that selects a pre-installed heating rate, cooling rate, or temperature maintenance is connected to the programmable controller to set the temperature set value according to the selected heating rate, cooling rate, or temperature maintenance. It consists of a PID-controlled temperature controller that changes or maintains the temperature, and a thermocouple on the heater side of the electric furnace connected to the temperature controller.

(Function) According to the electric furnace temperature control device of the present invention having the above configuration, when a material to be processed is processed in the electric furnace, the thermoelectromotive force is approximately reduced by the mV generator from the electromotive force generated by the master thermocouple close to the material to be processed. 99% is subtracted, this subtracted electromotive force is amplified by a DC amplifier, and based on this amplified electromotive force, the temperature controller changes the target temperature, in other words, changes to the temperature set value, i.e. increases, decreases, or holds. The signal is sent to the programmable controller, which selects the preset temperature increase rate, temperature decrease rate, and temperature hold, and then the PD control temperature controller increases or decreases the temperature set point. Or, based on this, the temperature of the thermocouple on the heater side of the electric furnace is controlled, and the temperature becomes constant.

(Embodiment) An embodiment of the electric furnace temperature control device according to the present invention will be described with reference to the drawings. The figure is a block diagram of an electric furnace temperature control device, where 1 is an electric furnace and 2 is a master thermocouple provided close to the processed material X in the electric furnace 1. 3 is an mV generator connected to the master thermocouple 2, which subtracts about 99% of the thermoelectromotive force generated by the master thermocouple 2. 4
is a DC amplifier connected to the mV generator 3, which amplifies the electromotive force subtracted above. Reference numeral 5 denotes a temperature controller connected to the DC amplifier 4, which uses the amplified electromotive force to determine the temperature state near the object to be processed, and outputs a signal to change or hold the temperature set value via a relay. It is something. Reference numeral 6 denotes a programmable controller connected to the temperature controller 5, which selects a preset temperature increase rate, temperature decrease rate, or temperature maintenance by inputting a temperature setting value change signal or a holding signal. Reference numeral 7 denotes a PID-controlled temperature controller connected to the programmable controller 6, which issues a signal to change or maintain the temperature set value according to the temperature increase rate, temperature decrease rate, or temperature maintenance selected by the programmable controller 6. It is something. 8 is a thermocouple on the heater 9 side of the electric furnace, and a PID-controlled temperature controller 7
The electric furnace temperature is raised, lowered, or maintained at the current value by signals from the electric furnace.

According to the electric furnace temperature control device of the embodiment configured as described above, when the material to be treated 39mV is subtracted by mV generator 3 to maintain 39.4mV, this subtracted electromotive force of 40μV is amplified by DC amplifier 4, and relay type temperature control is performed based on this amplified electromotive force of 40μV. Total 5
is set as neutral N within the range of 40 μV ± 5 μ■, and when it exceeds this, H1 will drop, so a change to the temperature set value, that is, whether to increase, decrease, or hold, is determined, and the relay changes to H. , NSL is generated and sent to the programmable controller 6, and the temperature increase rate, temperature decrease rate, and temperature maintenance of N mode, N mode, and L mode are selected according to the temperature setting change program pattern. In this example, the set value of temperature increase and temperature decrease rate is lOμV/...
This causes the PID-controlled temperature controller 7 to maintain the temperature set value of 39.4mV±lOμV, and based on this, the temperature of the thermocouple 8 on the heater 9 side of the electric furnace 1 is controlled. and the temperature becomes constant.

(Effects of the Invention) As can be seen from the above explanation, according to the electric furnace temperature control device of the present invention, when a material is processed in an electric furnace, the temperature setting is changed depending on the material to be processed to maintain a constant temperature. The effect is that it can be done.

[Brief explanation of the drawing]

The figure is a block diagram of the electric furnace temperature control device of the present invention. Applicant Tanaka Kikinzoku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. In an electric furnace, about 99% of the thermoelectromotive force is subtracted from the electromotive force generated by the master thermocouple installed close to the processed material and the master thermocouple connected to the master thermocouple.
a V generator, a DC amplifier connected to the mV generator to amplify the subtracted electromotive force, and a temperature state near the object to be processed relative to the temperature set value determined by the amplified electromotive force connected to the DC amplifier; a temperature controller that outputs a signal; a programmable controller that is connected to the temperature controller and selects a pre-installed temperature increase rate, temperature decrease rate, or temperature maintenance by inputting a temperature setting value change signal or holding signal; A PID-controlled temperature controller that is connected to the programmable controller and changes or maintains a temperature set value according to a selected heating rate, cooling rate, or temperature maintenance, and a heater side of an electric furnace connected to the temperature controller. An electric furnace temperature control device consisting of a thermocouple.