JPS60177116A - Method and device for measuring graphite spheroidization rate of molten cast iron - Google Patents

Abstract

PURPOSE:To measure exactly and quickly a graphite spheroidization rate by detecting the primary crystal-, supercooling- and eutectic temps. in spheroidization of a molten metal, classifying the temps. into four categories according to the presence or absence thereof, rearranging them into the classified linear relational equations by adding the primary crystal- and eutectic temps. of the original molten metal and determining respectively coeffts. by multiple regression analyses. CONSTITUTION:The temp. of a molten metal 1 is detected by a thermocouple 4 and a thermometer 6 and is converted to data by parallel-serial conversion 8. The data is put into a computer 10. The primary crystal temp. (TLO) and eutectic temp. (TEO) of the original molten metal are first measured. The molten metal is subjected to a spheroidization treatment and the primary crystal temp. (TL), supercooling temp. (TC) and eutetic temp. (TE) are measured. A spheroidization rate SG is expressed by the equation I in this case. Coeffts ABCDEF are determined by multiple regression analyses with many experiments. There is a case in which there are no primary crystal- and supercooling temps. of the spheroidization treatment and the coeffts. are determined by classifying the equations to four categories. The SG by the computer 10 is stored in a floppy disc 14 and is displayed on a printer 12 and a cathode ray tube CRT16. The spheroidization rate SG is exactly and quickly displayed by the data storage.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method and apparatus for measuring the graphite nodularity rate of molten cast iron subjected to graphite nodularization treatment over a wide range with high precision and high speed. Regarding.

The present invention quickly and accurately determines the graphite spheroidization rate before casting product cast iron and before pouring molten cast iron, so it can be used to improve cast iron production efficiency and product quality control. .

(Prior art) Accurately controlling the graphite nodularity in the cast iron manufacturing process is very important in terms of product quality control. Conventionally, the graphite nodularity rate of cast iron was generally measured. The following methods are known as methods for doing so.

The first method is to judge the spheroidization rate using a microscopic photograph of a cross section of a cast iron product manufactured from molten metal that has been subjected to the same spheroidization treatment, or a test material cast under the same conditions as the cast iron product. It is Buddha. Although this method is reliable in measuring the spheroidization rate, it has the disadvantage of requiring a long time for measurement. or,
Since the test is performed after pouring the molten metal, even if it is determined that the quality is poor, many products have already been cast, and all products formed from this molten metal will be considered defective. Therefore, there is a drawback that manufacturing efficiency is extremely low.

The second method is to take out a part of the molten metal after the graphite spheroidization treatment, measure the cooling curve of this molten metal, extract various features m of this cooling curve, and calculate the differences between these features. A method of estimating the spheroidization rate of graphite using a relational expression determined by multiple regression analysis with the spheroidization rate of graphite measured in advance for a large number of samples, that is, a thermal analysis method is known. However, conventional thermal analysis methods use a single empirical formula, and graphite There are some remote islands where the accuracy of measuring the spheroidization rate is poor. That is, it has not been possible to measure the spheroidization rate of graphite over a wide range with high precision.

(Object of the Invention) The present invention has been made to improve these drawbacks, and the present invention has been made to improve the graphite spheroidization treatment by taking into account the characteristics m of the cooling curve of the source water before ffl-51-. Based on the characteristics of the cooling curve of the molten metal after the spheroidization treatment, the measured cooling curve is classified into multiple predetermined classes, and the spheroidization rate of graphite is determined over a wide range by a linear function specified by each class. Another object of the present invention is to provide a method and apparatus for measuring the graphite nodularity of molten cast iron, which can be measured with high precision and at high speed.

[Structure of the invention]

The first invention involves taking out a part of Genyo before undergoing graphite spheroidization treatment, measuring the cooling curve of the extracted Motoyu, and determining the degree of primary crystallization of Motogata from the cooling curve. The eutectic temperature is detected, and then the source melt is subjected to graphite spheroidization treatment, a part of the molten metal after this treatment is taken out, the cooling curve of the taken out molten metal is measured, and from the cooling curve, the Detecting the primary crystal temperature, suitable cooling temperature, and eutectic temperature of the molten metal after the treatment, and classifying the cooling curve of the molten metal after the treatment according to the presence or absence of these temperatures, and determining the initial temperature and eutectic temperature of the source metal. , a linear function whose coefficients are different depending on the classification, with the primary crystal temperature, suitable cooling temperature, and eutectic temperature of the rB lagoon after treatment as variables, and the coefficients of the linear function for each classification are set in advance in a large number. The method consists of measuring the graphite nodularity of the molten metal after the above treatment using a linear function determined experimentally based on the correlation between the above variables and the graphite nodularity of the sample.

In the method of the present invention, the first characteristic point is to measure the cooling curve of the source water before graphite spheroidization treatment, and measure the graphite spheroidization rate from the primary crystal temperature and eutectic temperature obtained from the cooling curve. This is done as a variable for this purpose. The second characteristic point is that the primary crystal temperature, appropriate cooling temperature, and eutectic temperature are detected from the cooling curve of the molten metal after graphite spheroidization treatment, and these are used as variables to measure the graphite spheroidization rate. I'm here. Furthermore, the third
The feature is that the cooling curve is classified according to the presence or absence of the primary crystal temperature, suitable cooling temperature, and eutectic temperature, and the spheroidization rate of graphite is determined based on the linear function specified by the classification. That is, the spheroidization rate of graphite can be determined by the μ-order equation.

5G=A-TLO+B-TEO10-TL+D-TC+
E-TE+F...(1) Here, SG is the spheroidization rate of graphite, and TLO.

TEO is the initial temperature and eutectic temperature in the cooling curve of the source water, respectively. Further, TL, TO, and TE are the primary crystal temperature, appropriate cooling temperature, and eutectic temperature obtained from the cooling curve of the molten metal after the graphite spheroidization treatment, respectively. Zarani, A.
BIC, D, E, and F are coefficients of each variable, respectively.

These coefficients differ depending on the pre-classified class. or,
Each coefficient also includes O. These coefficients are based on the relationship between graphite nodularity measured by other methods (for example, Japan Foundry Foundry Association method CNIK method) and each of the above variables for cast iron products with different cast iron components or nodularization treatments. Correlation is measured and similar phrases are determined using multiple regression analysis.

The classification of the cooling curve of the present invention is generally preferably comprised of the following four classifications, but is not necessarily limited to the number of classifications.

The first type is a case in which the initial temperature, supercooled temperature, and eutectic temperature appear significantly on the cooling curve of the molten metal subjected to the spheroidization treatment at d3. The second type is a case where the appropriate cooling temperature is not detected, but the primary crystal temperature and the eutectic temperature are detected. Category 53 is a case where the primary crystal temperature is detected, and the appropriate cooling temperature and eutectic temperature are detected. In category 4, both the primary crystal temperature and the appropriate cooling temperature are not detected, and the eutectic temperature is detected. This is a case where only temperature is detected.

However, the second class and the fourth class have similar thread numbers in the 31 formula for the spheroidization rate, and can be combined into one class.

Here, the primary crystal temperature, suitable cooling temperature, and eutectic temperature are detected by finding the stagnation point of the cooling curve. This stagnation point is a point that exists in a section where the differential coefficient of the cooling curve exists within a certain range. Hereinafter, this section will be referred to as the stop Ni1 section. The distinction between initial product, supercooled, and eutectic is the order in which the stagnation section appears, the stagnation time, and after exiting the stagnation section, the cooling curve is upward or downward L5mmφX401111)1, and the stagnation section is a cold N1 curve This is defined as the range in which the differential coefficient of is present in the range of ±2.5°F/sec for 2.4 seconds or more. The primary crystal temperature is the first stagnation section, the stagnation section is smaller than 16 seconds, and is detected as the intermediate value of the stagnation section in which the curve moves downward after exiting the stagnation section. In addition, the appropriate cooling temperature is the minimum value of the first or second stagnation section in which the curve moves upward after escaping the stagnation section, or if the above conditions are not satisfied, ,
It is detected as the minimum value that appears before the eutectic temperature in the stagnation section where the eutectic temperature is detected.

In addition, the eutectic temperature is the second or third stagnation section, and is the maximum value of the stagnation section in which the curve changes downward after escaping the stagnation section, or the first and 16 second stagnation section. It is detected as the maximum value of the continuous stagnation section.

Although the above conditions are only examples and are not limited to these, each temperature of the initial product, subcooled temperature, and eutectic temperature can be detected with high precision when the above values are met.

Next, the second invention, a device for measuring graphite spheroidization rate of molten cast iron, has the following features: Temperature measurement 4! a control device that inputs the signal from the temperature measuring device and outputs the signal to the output device after predetermined processing; and an output device that inputs the signal from the control device and performs display based on the signal. The 1I11tIl device includes a stagnation point detection unit that detects a temperature stagnation point based on a signal from the temperature measurement device, and a stagnation point detection unit that detects a stagnation point of temperature based on a signal from the temperature measurement device, a stagnation point detection unit that determines whether the temperature is a temperature or a eutectic temperature; a class discrimination unit that determines the class to which the cooling curve belongs according to the determination result of the stagnation point detection unit; and a calculation unit that calculates the graphite nodularity rate using a linear function limited for each classification, the base number of each of the -order functions, and the graphite nodularity 51! The graphite spheroidization rate measuring device is characterized by comprising a storage section for storing the initial temperature of Motogata and the eutectic temperature of Motoyu, which were measured from the cooling curve of Motogata before i-processing.

This device has a temperature measuring device that measures a cooling curve, performs processing according to the first invention described above based on data obtained from the temperature measuring device, classifies the cooling curve, and produces graphite according to the classification. This is a device that calculates the spheroidization rate using an empirical formula to calculate the spheroidization rate and outputs the result. Further, each coefficient of the above-mentioned Keihan formula is stored in this device.

Hereinafter, the present invention will be explained in detail based on examples.

〔Example〕

The method of the present invention can be implemented by a computer device. Further, the device of the present invention can also be configured by a computer device, temperature detection means, output device, and the like. Therefore, specific embodiments of the method and apparatus of the present invention will be described below.

FIG. 1 is a block diagram showing the configuration of a measuring device according to a specific embodiment of the present invention. 2 is a cup for taking out a part of the molten metal and measuring its cooling curve; a thermocouple 4 made of alumel-chromel is installed at the bottom of the cup 2; the electromotive force generated by the thermocouple 4 is is input to the thermometer 6 via a conductor. The thermometer 6 converts the analog electromotive force every 0.4 seconds, converts it into a digital signal, and converts it into a binary coded decimal number (BCD).
It is output to the parallel/serial converter 8 as an encoded code expressed as . Parallel/serial converter 8 is BC
The D data is converted into serial data and output to the serial data input port of the microcomputer 10. Connected to the microcomputer 10 are a printer 12 and a CRT 16 that output predetermined measurement results, and a floppy disk device 14 that stores a predetermined program, the H1 formula, and its coefficients.

FIG. 2 is a flowchart showing the process performed by the microcomputer 10 used in the present invention. The microcomputer 10 starts execution from step 100 and performs various initial settings.

In step 102, a framework, graph axes, numerical values, scales, etc. for outputting data to the CRT 16 are displayed.

Step 104 is a subroutine for detecting that molten metal has been poured into the cup 2 and detecting the time to start measurement. Step 106 determines the return parameters from subroutine A and starts measurement when G=1. Step 108 is a stagnation point detection subroutine C which is the central processing.
Subroutine B, which performs various calculations, is executed. In step 110, return parameters for subroutine B are determined. If D=1, it means that a disconnection occurred in the temperature measuring device system during measurement, and step 114 is performed.
The process moves to step 102, erases the CRT screen, returns to step 102, and restarts the measurement from the beginning.

If the end is normal, the process moves to step 112, and the printer 1
2. Take a hard copy of the CRT16 and create one cooling curve.
The measurement of graphite spheroidization rate is completed.

FIG. 3 is a flowchart of the processing of subroutine A. Initial setting is performed at step 200 J3. Here, B is a parameter that stores the number of temperature measurements. In step 202, the temperature TP is read, and in step 204, a determination of TP -2472°F is made.

In the case of that value, it indicates that the input from the thermocouple 4 of the thermometer 6 is in an open state, which means that the thermocouple 4 is not connected normally, so the process returns to the main program in step 212. Then, the temperature reading and determination are repeated until the thermocouple 4 is connected to the temperature 316.

Next, the thermocouple 4 is connected to the thermometer 6, and its output is 24
When it becomes smaller than 72'F, the step becomes 206 and TP>
A determination of 1999 is made. If this condition is satisfied, it indicates that the molten metal has been poured into the cup 2, so in step 208 G=1 is set to indicate the beginning of measurement G), and in step 210, the temperature TP at that time is determined. T.P.
(0) and return to the main program. If the conditions are not met in step 206, this indicates that the molten metal has not been poured into the cup, so the process returns to the main program in step 214 and repeats the same routine until the molten metal is poured into the cup.

FIG. 4 is a flowchart showing the processing of subroutine B. Initialization is performed in step 300. The values set here, F and N, are each set to 0.

D is a flag for wire breakage detection, F is a flag for measurement completion, and N is a parameter that does not indicate the classification of the cooling curve. If it is determined in step 302 that F=1, step 30
Step 4 returns to the main program and the measurement ends 1°. In step 306, the value of B is updated by 1 and the number of temperature measurements is counted. At step 308 the temperature is read and the TP
(B), and the value is stored in the CRT in step 310.
The plot is displayed on 16. Next, in step 312, the difference T from the previously measured temperature is determined. That is, 0. of the cooling curve.
The rate of change for 4 seconds is 1c. Next, in step 313, the value of N is determined, and since it is initially O, the process moves to step 314, and the maximum value of the cooling curve is detected. That is, molten metal is poured into the cup 2, the temperature rises, the maximum temperature is recorded, and the maximum temperature is detected during the cooling process. If the maximum temperature is detected, step 316
Let the value of N be set to 1. If N is O, the highest temperature is detected by the repeating routine of steps 302-313-314-315-418-302 and N=1 is set. In step 320, it is determined that Δd≦15. If the conditions are not met, the process moves to step 322 and it is determined that the wire is broken. That is, there would normally not be a temperature change of more than 15 degrees Fahrenheit between two adjacent measurement intervals. If a wire breakage is detected, the value of D is determined in step 110 of the main program, and predetermined processing for wire breakage detection is performed. Further, step 322 is a step for determining the end of the measurement point. That is, TP(B)<
The measurement is completed when 2000°Fl or B>310 is satisfied. The test ends when the temperature of the molten metal in the cup drops below 2000'F or when the number of measurement points reaches 310 or above. Since this program reads data every 0°4 seconds, the measurement ends in 124 seconds.

Step 326 is a step of executing subroutine C for detecting the PP stagnation point of the curve. FIG. 5 is a flowchart showing the flow of this subroutine C. Further, FIG. 7 is a diagram showing the classification of cooling curves for determining the stop @i) point according to this program. Step 500 is a step for setting initial values, N1 is B, 4, N3
is set to O. N3 is a parameter for counting the number of stagnation points. Proceeding to step 502, the width of the temperature change four points before the current measurement point is determined. The width of this temperature change is determined by whether it is 1 or less. That is, specifically,
Since measurements are taken at 0.4 second intervals, the absolute value is 2.5°.
When the temperature gradient is less than F/Sec, it is determined that the point is within the stagnation zone. If it is a stagnation point, the process moves to step 504 and returns to subroutine B. If consecutive stagnation points are detected, steps 302 to 50
The routines 2-504-328-418-302 are repeated. Also, if it is not a stagnation point, steps 506 to 3
The routine from 28 to 418 to 302 to 506 is repeated.

Further, when the stagnation section, which is a set of stagnation points, is escaped from the stagnation section (1=1), it is determined in step 506 whether the curve after escaping is upward (U=1) or downward (LI=O). Next, in step 516, the temperature difference is determined by looking up the sequentially input data, and if it is a stagnation point, step 51
8, the number of stagnation points (N3), and the fli1 starting point of the stagnation point (
N1), the end point of the stagnation point (N7) is detected. Steps 512 and 514 do not show corresponding processing when the stagnation period starts from the first measurement. Next, step 52
If it is 0, it is determined whether or not it is a stagnation section. Step 5
If the determination at step 20 is YES, step 522 sets N=2, and step 524 returns. In other words, when the vehicle escapes from the stagnation point after stagnation points continue for more than 2 to 4 seconds,
That section is determined to be a stagnation section. It is remembered that N=2 is the first stagnation section. That is, Fig. 7 (a to e
), the first stagnation section has been detected.

In the case of the first stop jiff section, the process passes through the following steps and returns to step 328 of subroutine B. Depth 328 is the first stagnation section, and if the curve rises after escaping from the stagnation section, N
=10. Then, in step 332, the minimum temperature in the stagnation section is read, and in step 334, the appropriate cool humidity TC is determined.
Display on the RT 16 screen. That is, the appropriate cooling temperature is detected under the above conditions. In this case, the initial product ta[T
This shows the case where L is not detected, and the cooling curve is the seventh
The curve is not shown in any of the figures (f) to (j>).

In step 336, it is the first stagnation section, and if the curve falls after exiting the stagnation section and the stagnation time is less than 16 seconds, that is, 40 points in terms of the number of measurement points, the value of N is determined in step 338. Set to 20. Then, in step 339, the average temperature of the stagnation section is determined, and in step 340, T
Display L. In this case, the first stagnation section indicates the primary crystal temperature. That is, the cooling curve is shown in Figure 7 (a
) to (e).

In step 342, it is the first stagnation section, and the stagnation section 112
When the curve descends and the stagnation time is determined to be 16 seconds or more, the value of N is set to 30 in step 344, the highest humidity in the stagnation section is read in step 346, and TE is set in step 348. indicate.

In other words, in this case, there is no primary humidity and suitable cooling temperature, but only the eutectic temperature exists. The characteristics are shown in .

Next, subroutine D shown in step 350 detects only the temperature of the common product, but is a subroutine for categorizing the curves in more detail during the classification. FIG. 6 is a flowchart showing the flow of this subroutine D. In step 600, the minimum humidity is detected from the first point of the stagnation zone until the -rE temperature is detected. Then, this temperature is set as a suitable cooling temperature as TC.

If T O is smaller than TE in step 602, the temperature of this TC is determined to be the appropriate cooling temperature in step 604, and T
C is displayed and the process returns 1° in step 606. In this case, it means that the cold 11dll line has the characteristics shown in FIG. 7 (1 page).

If the determination in step 602 is no, step 60
8, read the lowest temperature from the eutectic temperature TE to the last point of the stagnation zone, and set it as TE2.

In step 610, 1' E lfi T E 2 +
If it is larger than 3, the process moves to step 612, sets the value of N to 90, and returns in step 614.

In this case, it means that the cooling curve has the characteristics shown in FIG. 7(i). In the opposite case, step 616
The process moves to step 618, sets the value of N to 80, and returns to step 618. This means that the cooling curve has a characteristic not shown in FIG. 7(j).

Next, in step 360, the spheroidization rate of graphite is evaluated according to the value of N.

Next, in step 362, the calculated SG price is displayed.

Next, when the first stagnation section is 16 seconds or less, the value of N is set to 10 or 20. Therefore, a routine similar to that described above will cause the second stop? Until the Il1 section is detected, the same processing as for the detection of the first stop section 811 described above is performed, and in the end, the process goes to step 526 83, and when the second stop section is detected, the value of N is set to 21 at step 528. Be hit. Further, if the value of N is 10, the value of N is set to 113, and if the second stagnation section is detected, the value of N is set to 11 in step 534. When the detection of the second stagnation section is completed, subroutine C is exited, and the nature of the stagnation section is determined in step 364. That is, in step 364, if the cooling curve rises after exiting the second stagnation zone, step 368
Then, the minimum humidity in the stagnation section is read, and step 37
0 sets the value of N to 50, and in step 372 the minimum temperature is displayed as TO. That is, in this case, the second
The stagnation section is determined to be at an appropriately cool temperature.

Next, in step 374, after the second stagnation section ends, if the curve falls, the maximum temperature in the stagnation section is read in step 376, the value of N is set to 60 in step 378, and the process moves to step 380.

In this case, the appropriate cooling temperature is not detected, and the second stagnation zone is assumed to be the eutectic temperature, and the process moves to step 380, which corresponds to FIGS. 7(C), (d), and (e). do. Subroutine D is a program for analyzing the properties of the eutectic point in more detail, as described above when N=30, and is processed according to the value of N shown in FIG.

Therefore, the explanation thereof will be omitted.

When the process moves to step 382, there is a first stagnation section and a second stagnation section, and at least the primary crystal temperature and the eutectic temperature are detected. In step 382, the spheroidization rate is calculated corresponding to the value of N, and in step 380
The spheroidization rate is displayed.

Next, in step 386, if the value of N is 11 and the curve falls when exiting the second stagnation zone, the maximum temperature in the stagnation zone is read in step 388, and the value of N is set to 12 in step 390. . In this case, the first stagnation section is determined to be a suitable cooling temperature because the curve rises after the stagnation section, and the second stagnation section is determined to be a eutectic temperature. That is,
This is the case with the characteristics shown in FIG. 7(f). Step 394
The values of TE and SG are displayed.

Next, step 396r: If the value of N is 11 and the curve rises after exiting the second stagnation section, step 398
Abnormal handling is performed. Such a case is highly unlikely.

In this manner, processing was performed on the curve having the first and second stagnation sections.

Next, when there is a third stagnation section, the detection of the stagnation section is the same as the processing for the first and second stagnation sections,
The value of N is set at step 3701:50.

That is, it is a case where it has a primary crystal temperature and an appropriate cooling temperature. Therefore, at step 538, the third stagnation section is detected, and at step 5710, the value of N is set to 51.

Therefore, in step 400, if the curve drops after the third stagnation period ends, the maximum temperature in the third stagnation period is read at the slab tube 402. That is, read the eutectic temperature.

At step 402, the value of N is set to 52, at step 406 the spheroidization rate is calculated, and at step 408 the value is displayed. In this case, the cooling curve is represented by the characteristic diagram shown in FIG. 7(a). That is, the initial product, supercooling, and eutectic temperatures are determined.

After the third stagnation section is detected in step 410, if the cooling curve rises, it is determined that there is an abnormality, and processing is performed in step 412.

In this way, all the cooling curves shown in FIG. 7 are classified.

In step 414, a disconnection is detected, and if a disconnection is detected, a flash display is given to the CRT 16 in step 416, the process returns to step 302 via step 418, and the process returns to the main program in step 304.

The formula used to determine the spheroidization rate is as follows: Class 1: When there is an initial temperature, supercooling, and eutectic temperature, (
N-52,60) 8G--0,33514XTL+3.65415XTC
-4,2933XTE+2112.4 Class 2... Initial product, when only eutectic temperature exists, (N-70,40) 8G-0,95477XTLO+10.41974xT
EO-6,10634x'T°L+6°79197XT
E-24543,1 3rd ￥A... only supercooling, eutectic temperature exists, (N
=12.30) SG--0,49921X1-LO+0.13294X
TEO+0.63908XTC- 1,49792xTE+2617.8 Class 4...When only eutectic temperature exists, (N-90,
80) SG-0,09701xTLO+1.23095xTE
O-2,66'802xTE+ 2928. 3 The results measured using the above program are shown in Figures 8 to 1.
Shown in Figure 4. Of these, FIG. 8 shows the measurement results of the cooling curve of the molten metal after treatment, and FIGS. 9 to 14 show the cooling curves of the molten metal after treatment. This is a definite result.

In addition, FIGS. 15 to 19 are respectively shown in FIGS. 9 to 13.
It is a micrograph showing the composition of a cross section of cast iron corresponding to the cooling curve in the figure. Based on these results, the Japan Foundry Association method (NI
When the spheroidization rate of graphite was measured using the K> method and compared with the results of the present invention, the measurement error of the spheroidization rate of graphite was within 5%.

〔Effect of the invention〕

In summary, the present invention is a process for spheroidizing graphite. A part of the molten metal is taken out, its cooling curve is measured, and the initial product, overcurrent, and eutectic temperatures are detected from the cooling curve, and the cooling curve is classified based on the presence or absence of these or their humidity relationship. Furthermore, the graphite spheroidization rate is measured by a linear function according to the classification, taking into account the initial product and eutectic temperatures obtained from the cooling curve measured by taking out a part of the source water before spheroidization treatment.

Therefore, according to the method and apparatus of the present invention, the spheroidization rate can be measured very accurately and quickly over a wide range. In addition, since the spheroidization rate can be measured accurately over a wide range, it is suitable for high-mix, low-volume production.

Further, since the measurement is performed in the state of the molten metal before casting, it is possible to prevent the occurrence of defective products, which has the effect of improving manufacturing efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a measuring device according to a specific embodiment of the present invention. FIG. 2 is a flowchart of one main program showing the processing of the computer used in the apparatus of this embodiment. 3, 4, 5, and 6 are flowcharts that do not show the processing of the length program. FIG. 7 is a diagram showing classified patterns of cooling curves. FIGS. 8 to 14 are graphs of experimental results measured using the apparatus of the same embodiment. FIGS. 15 to 19 are micrographs showing the cross-sectional structure of sample cast iron corresponding to FIGS. 9 to 13, which are the output results of the apparatus of the same example. Patent applicant Takaoka] Nigyo Co., Ltd. Agent Nakayama Shoji Co., Ltd. Patent attorney Hirodo Okawa Patent attorney Shudo Gagiya Patent attorney Akio Maruyama Figure 1 Figure 2 Figure 3 Figure 4 (b) Figure 15 Figure 16 Figure 17 Figure 18

Claims (2)

[Claims] (1) Take out a part of the source water before the graphite spheroidization treatment, measure the cooling curve of the extracted source water, and use the cooling curve to determine the primary temperature of the source water and the eutectic temperature of the source water. Next, the raw molten metal is subjected to graphite spheroidization treatment, a part of the molten metal after this treatment is taken out, the cooling curve of the molten metal taken out is measured, and from the cooling curve, it is determined that after the treatment Detecting the primary crystal temperature, appropriate cooling temperature, and eutectic temperature of the molten metal, classifying the cooling curve of the molten metal after the treatment according to the presence or absence of these temperatures, and determining the primary crystal temperature, eutectic temperature, and treatment of the source metal. A linear function whose coefficients differ depending on the classification, with the initial temperature, suitable cooling temperature, and eutectic temperature of the subsequent molten metal as variables, and the coefficients of the linear function for each classification are calculated in advance for a large number of samples. A method of measuring the graphite nodularity of the molten metal after the treatment using a linear function determined experimentally by the correlation between the above variables and the graphite nodularity. (2) a temperature measuring device that measures the temperature of the molten metal in a time series during the cooling process; a control device that inputs a signal from the temperature measuring device and outputs a signal to an output device after predetermined processing; A measuring device comprising an output device that inputs a signal from the control device and performs display based on the signal, the control device detecting a temperature stagnation point based on the signal output from the temperature measuring device. A stagnation point detection unit that detects a stagnation point; a stagnation point determination unit that determines whether the detected stagnation point is at a primary crystal temperature, an appropriate cooling temperature, or a eutectic temperature; a class discriminator that determines the class to which the cooling curve belongs; an arithmetic unit that calculates the graphite nodularity rate based on the linear function specified for each class according to the classification; Graphite spheroidization rate measurement characterized by comprising a storage unit for storing the base number, the primary crystal temperature of the motodan measured from the cooling curve of the motodan before the spheroidization treatment of graphite, and the eutectic temperature of the motodan. Device.