JPH0152676B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention provides an electric furnace such as a material testing machine.
Regarding a device for adjusting the temperature and temperature distribution of a heated body, in particular, an electric furnace having a plurality of heaters, a plurality of heated body temperature detectors attached to a heated body charged into the furnace; A furnace temperature detector is installed separately in the furnace away from the heated object, and the output signal of each temperature detector and the output signal of the temperature setting device are compared and calculated by a calculator. The heater is controlled based on the output signal of the body temperature detector, and when keeping warm, the heater is controlled based on the output signal of the furnace temperature detector.
It automatically adjusts the temperature of the heated body.

In general, material testing machines for testing the strength and other properties of materials at specific temperatures use electric furnaces that charge a test piece, heat it, raise the temperature, and then maintain it at a constant temperature. ing.

Conventionally, temperature control devices for electric furnaces have two types: one that detects the temperature inside the furnace and controls the power supplied to the heater, and the other that directly detects the temperature of the heated body and controls the power supplied to the heater. There was also a control method. However, the temperature inside the furnace and the temperature of the heated object do not necessarily match, and the temperature distribution of each part of the heated object is not necessarily constant. It is not possible to adjust the temperature of the heated object.

On the other hand, methods that directly detect and control the temperature of the heated object can accurately adjust the temperature of the heated object under normal conditions, but the heated object may be significantly deformed or destroyed. In this case, the temperature detector is separated from the heated object and the actual temperature of the heated object is not detected and shows a different value. Therefore, in either method, temperature control is incomplete and causes errors in material test results.
There was a risk that its reliability would be lost.

This invention solves the above-mentioned problems in a temperature adjustment device for an electric furnace. SUMMARY OF THE INVENTION An object of the present invention is to provide a heated body temperature adjusting device for an electric furnace that can accurately adjust the temperature and temperature distribution of a heated body; Heated element temperature in electric furnaces that can adjust the temperature of the heated element even if the heated element temperature detector is separated from the heated element and indicates a value different from the actual temperature due to deformation or destruction of the heated element. Another object of the present invention is to provide an adjustment device, and a further object of the present invention is to provide a highly reliable material testing machine that can perform tests while maintaining a constant temperature distribution of a heated body.

That is, the present invention provides an electric furnace 2 having a plurality of heaters 1a, 1b, and 1c as in the illustrated embodiment. A plurality of heated object temperature detectors 4a, 4b, 4c that detect temperatures; an in-furnace temperature detector 5 that is placed separately from the heated object 3 in the electric furnace 2 and detects the furnace temperature; a temperature setting device 6 for setting the temperature of the body 3; and the heated body temperature detectors 4a, 4.
b, 4c, a furnace temperature detector 5, and a temperature setting device 6 are connected, and each heated body temperature detector 4a, 4b,
The output signal of the temperature setting device 4c and the setting signal of the temperature setting device 6 are compared, and each heater 1a, 1b, 1 is adjusted according to the deviation.
Calculate the power to be supplied to c and output the heater power control signal, and when the deviation reaches a predetermined value or less, the output signal of each heated body temperature detector 4a, 4b, 4c and the furnace temperature detector From the output signal of 5, the difference between the heated body temperature and the furnace temperature and each heater 1a, 1b,
1c is calculated, and then based on the output signal of the furnace temperature detector 5 and the temperature difference, the power to be supplied to each heater 1a, 1b, 1c is calculated while maintaining the power ratio. The present invention relates to a heated body temperature adjusting device for an electric furnace 2, characterized in that it is provided with a computing unit 7 that outputs a heater power control signal.

The present invention will be explained below based on the drawings. 1st
The figure is a block diagram showing the configuration of an embodiment of the present invention. An electric furnace 2 having a plurality of heaters 1a, 1b, and 1c has a test piece 3, which is to be tested in a high temperature state, inserted therein as a heated body. A plurality of heated body temperature detectors 4a, 4b, and 4c are attached to the test piece 3 to detect the temperature of each part thereof. Also, in this electric furnace 2, a test piece 3
A furnace temperature detector 5 is installed at a location away from the furnace. These temperature detectors 4a, 4b, 4c, 5
Generally, a thermocouple is used. Heated object temperature detectors 4a, 4b, 4c and furnace temperature detector 5
is connected to the arithmetic unit 7 via an analog switch 8 and an analog-to-digital converter 9. The analog switch 8 connects each temperature detector 4a, 4b, 4
It is composed of changeover switches 8a, 8b, 8c, and 8d for sequentially switching the output signals of c and 5.
Switch selection circuit 1 connected from computing unit 7
Switching is performed by a selection signal from 1. Further, a temperature setting device 6 for setting the temperature of the test piece 3 is connected to the calculator 7. Furthermore, heater power control circuits 12a, 12 for controlling each heater 1a, 1b, 1c are provided on the output side of the arithmetic unit.
The heater power control circuits 12a, 12b, 12c are connected to digital-to-analog converters 13a, 13b, 13c, respectively.
Thyristor drive circuits 14a, 14b, 14c and thyristors 15a, 15b, 15c are provided. When adjusting the temperature, the temperature to be maintained for the test piece 3 is set by the temperature setting device 6. Analog signals output from the heated body temperature detectors 4a, 4b, 4c and the furnace temperature detector 5 are sequentially scanned by an analog switch 8 that is switched in response to a selection signal from a switch selection circuit 11, and - After being converted into a digital signal through the digital converter 9, it is input to the arithmetic unit 7. The computing unit 7 first detects each heated body temperature detector 4a, 4.
The signals from b and 4c are compared with the setting signal of the temperature setting device 6, and if there is a deviation, the electric power to be supplied to each heater 1a, 1b, 1c of the electric furnace 2 is calculated according to the deviation, and the electric power to be supplied to each heater 1a, 1b, 1c of the electric furnace 2 is To control the power, it outputs a digital signal corresponding to the power to be supplied. After this digital signal is converted into an analog signal by digital-to-analog converters 13a, 13b, 13c, thyristor drive circuits 14a, 1
Thyristors 15a, 15b,
15c to send power to heaters 1a, 1b, and 1c.

When the test piece 3 is heated in this way and the temperature rises to near the set temperature, the heated body temperature detectors 4a, 4
When the deviation between the signals from b and 4c and the setting signal of the temperature setting device 6 becomes extremely small and becomes equal to or less than a predetermined value, the computing unit 7 determines that the temperature increase is completed. When the temperature rise is completed, the computing unit 7 detects the heated body temperature detector 4
Based on the signals from a, 4b, and 4c and the signal from the furnace temperature detector 5, the temperature difference between each part of the test piece 3 and the furnace temperature is detected, and each heater 1 is detected for heat retention.
Calculate the ratio of power to be supplied to a, 1b, and 1c,
Thereafter, based on the signal from the furnace temperature detector 5, a heater power control signal is outputted to maintain the temperature of the test piece 3 constant while maintaining the power supply ratio to each heater 1a, 1b, 1c.

As described above, according to this device, in the temperature raising process, the heaters 1a, 1b, 1c are controlled based on the detection signals of the heated object temperature detectors 4a, 4b, 4c, so the temperature of the test piece 3 can be adjusted accurately and quickly. Adjustments can be made. In addition, during the heat retention process, the furnace temperature detector 5
Since the heaters 1a, 1b, 1c are controlled based on the detection signal of , 4c are far apart and show a different value from the actual value, there will be no problem; the temperature difference between the test piece temperature and the furnace temperature is calculated in advance, so the test can be continued while maintaining the same temperature. There is no risk of error.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, 1a, 1b, 1c are heaters, 2
3 is an electric furnace, 3 is a test piece, 4a, 4b, 4c are heated object temperature detectors, 5 is an in-furnace temperature detector, 6 is a temperature setting device, and 7 is a computing unit.

Claims (1)

[Claims] 1. In an electric furnace having a plurality of heaters, a plurality of heated body temperature detectors are attached to the heated body charged into the electric furnace to detect the temperature of the heated body, and An in-furnace temperature detector that is placed separately from the heating element to detect the in-furnace temperature, a temperature setting device to set the temperature of the heated object, the heated object temperature detector, the in-furnace temperature detector, and the temperature setting device. is connected, compares the output signal of each heated object temperature detector and the setting signal of the temperature setting device, calculates the power to be supplied to each heater according to the deviation, and outputs the heater power control signal. death,
And, when the deviation reaches a predetermined value or less, the difference between the temperature of the heated body and the temperature inside the furnace and the information to be supplied to each heater are determined from the output signal of each heated body temperature detector and the output signal of the furnace temperature detector. A calculator that calculates a power ratio, then calculates the power to be supplied to each heater based on the output signal of the furnace temperature detector and the temperature difference while maintaining the power ratio, and outputs a heater power control signal. A heated body temperature adjustment device for an electric furnace, characterized by comprising: