JPH07190912A - Heater for creep tester excellent in temperature retaining performance - Google Patents

Abstract

PURPOSE:To provide a system for controlling the temperature of a test piece within an error range of + or -2 deg.C with respect to a set temperature for a long time by automating the temperature regulation when a creep test is conducted, i.e., a metallic material is subjected to a long time test under a high temperature atmosphere. CONSTITUTION:An electric furnace comprising an upper zone ceramic heater 8, an intermediate zone ceramic heater 9, a lower zone ceramic heater 10, an R thermocouple 4 for detecting the atmospheric temperature, and R thermocouples 5, 6, 7 for detecting the temperature of a test piece is further provided with an electric furnace elevator 13 and an automatic temperature regulator in order to control the temperature of the for the set temperature in the range of 400-1000 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a creep test of a metal material in a high temperature atmosphere, and a soaking zone having a length of 100 mm and a test piece as a center is set at a temperature set in a range of 400 to 1000.degree. To a heating device for a creep tester capable of controlling and maintaining the temperature with an accuracy of ± 2 ° C or less.

[0002]

2. Description of the Related Art Conventionally, an electric furnace for creep test is 400
As for the temperature controller for controlling the temperature in the range of ℃ to 1000 ℃, the method of adjusting the current mainly by hand has been adopted. However, in this method, the temperature varies from ± 3 ° C. to ± 6 ° C. even if the current is subtly adjusted, so that it is necessary to monitor a person, and a temperature error occurs due to an individual difference. In addition, since the operation is mainly performed by human feeling, it may be heated to a temperature higher than the specified temperature, which is not an optimum device for maintaining a constant temperature, which is important in the creep test.

[0003]

As described above, when the conventional electric furnace and temperature control device are used, it takes a long time to stabilize the soaking zone of the electric furnace at the set temperature of ± 3 ° C to ± 6 ° C. Human intervention and monitoring was required. It is not possible to obtain highly reliable data unless the creep test is conducted under the basic conditions of the creep test, that is, the temperature is raised for 16 to 24 hours in order to achieve thermal equilibrium at the set temperature and kept at a uniform temperature. . In the temperature control with human intervention, highly reliable data cannot be obtained due to individual differences and errors due to each work.

The present invention is intended to solve the above-mentioned problems, and when a metal material is tested at a constant high temperature, the optimum electric furnace and the soaking temperature of the electric furnace are set within ± By providing an automatic temperature control device for controlling the temperature at 2 ° C. or lower, a heating device for a creep tester having excellent temperature holding performance is provided.

[0005]

The gist of the present invention is to include an elevating device for adjusting the position of an electric furnace with respect to a test piece, and to arrange a ceramics embedded heater in three parts in the length direction. , A tubular electric furnace for creep test, in which heating can be controlled independently, a thermocouple for detecting the ambient temperature in the electric furnace, and at the same time, the test piece is divided into three in the length direction to detect the temperature at each position. Three thermocouples and three temperature controls with a function to detect the disconnection and short circuit of the thermocouple while keeping the temperature of the test piece within the temperature range of 400 ° C to 1000 ° C with an accuracy of ± 2 ° C or less. The optimum PID value and the upper and lower limit values of the current according to the characteristics of the electric furnace are entered in advance for each set temperature, and the furnace atmosphere temperature and the temperature at each of the three points of the test piece are compared. Then, for each position of the electric furnace, A system for selecting the optimum data from the applied data and transmitting it to the temperature controller, and further preferably 3 for detecting the disconnection of the ceramic embedded heater arranged in three in the electric furnace. Heater for creep tester, which has excellent temperature retention performance, consisting of a heater burnout alarm, a detector that detects the breakage of the creep test piece, and a time meter that measures the time from the start to the end of the creep test. It is a device.

According to the apparatus of the present invention, in order to maintain the soaking temperature at a constant value, the ceramic embedded heater is placed on the upper part,
Tubular type electric furnace with internal structure arranged in middle and lower 3 zones, and temperature of 3 units with cascade control function to control ceramic embedded heaters in upper, middle and lower 3 zones 1: 1 Optimal PID with controller
± 2 ° C against the set temperature depending on the value and the optimum upper and lower limits of the current
Obtain reliable test data with temperature control within the range. That is, in the present invention, in order to stably maintain the soaking zone of the electric furnace with an accuracy of ± 2 ° C. or less, a tubular electric furnace in which ceramic embedded heaters are internally arranged in three zones in the upper, middle and lower parts, A lifting device for adjusting the positional relationship of the test piece fixed inside the electric furnace with the internal soaking zone of the electric furnace, and three R-types for measuring temperature data of the upper, middle and lower parts of the test piece Thermocouple 3, one R-type thermocouple for measuring atmospheric temperature data inside the soaking zone, and automatically controlling the current to the ceramic embedded heater based on the signal from the R-type thermocouple, It consists of a temperature controller that automatically controls the test temperature within ± 2 ° C.

[0007]

In the present invention, by adopting the electric furnace as shown in FIG. 1 and the control system as shown in FIG. 2, the soaking zone inside the electric furnace is set within the range of 400 ° C. to 1000 ° C. It will be held at 2 ° C or lower for a long time. When the temperature rises, the atmospheric temperature in the furnace rises before the temperature of the upper, middle and lower parts of the test piece fixed inside the electric furnace, so three zones were arranged in the upper, middle and lower parts of the electric furnace. The ceramic heater is controlled so that the temperature of the test piece does not exceed the preset temperature as a method of controlling when the atmospheric temperature in the furnace reaches the proportional band of the preset temperature. In order to keep the temperature stable at the set temperature, the optimum PID value and the current upper and lower limit values according to the characteristics of the electric furnace are input to the PC for data transmission, and each position of the electric furnace is set individually for each set temperature. From the input data, configure a system that transmits the optimum data to the temperature controller and make it a control method to maintain temperature,
Since the temperature of the atmosphere inside the furnace and the temperature of the test piece are constantly detected, the temperature of the test piece is automatically controlled so that the temperature of the test piece does not exceed ± 2 ° C even if either temperature fluctuates. It is kept below ± 2 ℃ in the temperature range up to ℃,
Optimal temperature control for creep test can be performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be described below based on embodiments with reference to the drawings. FIG. 1 shows a structural diagram of an electric furnace for a creep tester which is an embodiment of the present invention, and FIG. 2 shows a control system diagram of an automatic temperature control device.

The frame 1 is for holding the main body of the electric furnace and is provided with a lifting device 13. by this,
It is possible to adjust the positional relationship between the test piece 11 fixed to the pull rod 14 and the soaking zone 12 located in the central portion of the electric furnace case 3. That is, the test piece 11 can be accurately fixed to the central portion of the soaking zone 12 located in the central portion of the electric furnace.

The upper zone ceramics heater 8, the middle zone ceramics heater 9, and the lower zone ceramics heater 10 have the ability to heat from a temperature of 400 ° C. to 1000 ° C. set by the data transmission personal computer 15. The automatic temperature control device is equipped with an upper zone temperature controller 16, a middle zone temperature controller 17, and a lower zone temperature controller 18, which are independent of the three zones, and are installed in an electric furnace. The temperature control of each zone can be performed by the current temperature signals from the temperature detecting R thermocouple 4 and the test piece temperature detecting R thermocouples 5, 6 and 7.

Next, Table 1, Table 2 and FIG. 3 show temperature data obtained by conducting a temperature rise test using the electric furnace temperature automatic adjusting device having the above-mentioned structure. Table 1 is 450 ℃, 550 ℃, 750 ℃
The three types of temperature data are recorded every 6 hours for 66 hours. Table 2 shows 500 ° C, 80
It is data in which 66 hours of data are recorded every 6 hours with three kinds of temperature data of 0 ° C. and 1000 ° C. Also,
The upper and lower limit values of PID and current are slightly different depending on each temperature and each electric furnace, but they are the values acquired at the time of adjustment and the optimum values will be automatically selected after acquisition. It doesn't bother you. FIG. 3 is a graph of test piece temperature and ambient temperature data until reaching the set temperature.

In the method of the present invention, the temperature error with respect to the set temperature is within ± 2 ° C. for each zone as shown in Table 1, Table 2 and FIG.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

[0016]

[Table 4]

[0017]

According to the present invention, the condition of maintaining a constant temperature, which is most important when performing a creep test of a metal material, suppresses the temperature variation of about ± 3 ° C. to about ± 1 ° C. in the conventional case. You can Further, since it is an automatic control, it is possible to perform a highly reliable creep test under a temperature without individual differences and errors due to each work.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an electric furnace for creep test of the present invention and a schematic view of an automatic temperature control device.

FIG. 2 is a system diagram of a control system of the present invention.

FIG. 3 is a graph of test piece temperature and ambient temperature data until the set temperature of the present invention is reached.

FIG. 4 is a control flowchart of the present invention.

[Explanation of symbols]

 1 Frame 2 Refractory Brick Lid 3 Electric Furnace Case 4 R Thermocouple for Atmospheric Temperature Detection 5 R Thermocouple for Detecting Specimen Temperature (Upper) 6 R Thermocouple for Temperature Detection (Middle) 7 R Thermocouple for Temperature Detection (Lower) ) 8 upper zone ceramics heater 9 middle zone ceramics heater 10 lower zone ceramics heater 11 test piece 12 soaking zone 13 lifting device 14 pull rod 15 PC for data transmission 16 upper zone temperature controller 17 middle zone temperature controller 18 lower zone temperature controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Sekiguchi 20-1 Shintomi, Futtsu City, Chiba Prefecture Nippon Steel Co., Ltd. Corporate Technology Development Division (72) Inventor Toshimi Washiya 20-1 Shintomi, Futtsu City, Chiba Prefecture (72) Inventor Norihiko Ayabe 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Co., Ltd. Technical Development Division, Mishima Kosan Co., Ltd. (72) Iwahara Futtsu, Chiba Prefecture Shintomi 20-1 Nippon Steel Co., Ltd.Technology Development Division, Mishima Kosan Co., Ltd. (72) Inventor Kazushige Yamaguchi 20-1 Shintomi, Chiba Prefecture Shintomi Co., Ltd.Technology Development Division, Mishima Kosan Co., Ltd. In the company

Claims (1)

[Claims] 1. A creep test tubular mold including an elevating device for adjusting the position of an electric furnace with respect to a test piece, arranging ceramic embedded heaters in three divisions in a length direction, and capable of independently controlling heating. An electric furnace, a thermocouple for detecting an ambient temperature in the electric furnace, and three thermocouples for simultaneously detecting the temperature at each position by dividing the test piece into three in the length direction,
The temperature of the test piece is maintained within a temperature range of 400 ° C to 1000 ° C with an accuracy of ± 2 ° C or less, and three temperature controllers equipped with a function of detecting disconnection and short circuit of the thermocouple,
The optimum PID value and the upper and lower limit values of the current according to the characteristics of the electric furnace are input in advance for each set temperature, and the furnace atmosphere temperature and the temperature at each of the three points of the test piece are compared, A heating device for a creep tester with excellent temperature holding performance, which is composed of a system that selects optimum data from pre-input data for each position of the electric furnace and transmits it to the temperature controller.