JPS62219507A - Control method of annealing temperature of iron core for electric apparatus - Google Patents

Abstract

PURPOSE:To control the output of an inverter by inverter control means using the results of a sought true mean annealing temperature and the heating conditions of an iron core by removing the periodic variation due to the thickness of the iron core from the temperature data measured by optical temperature measuring means and by averaging. CONSTITUTION:The data of the temperature measured by temperature measuring means 3 of an iron core 2 which is moving in a heating coil are stored in the memory 13 of a microcomputer 10 in every arbitrary sampling time Ts and an artificial mean annealing temperature Xd is sought and stored after the data of the temperature of the thickness L of 1-2 iron cores 2 are obtained. After the second measurement, a temperature XL wherein a previously set normally generated dispersion temperature DELTAX is reduced from the Xd is calculated to remove the temperature data except the normally generated dispersion temperature. Temperature data B for the temperature which is lower than the temperature XL from sampled temperature data are made void. A mean annealing temperature X near a true value is sought by averaging again when the stored number of the above-mentioned artificial mean annealing temperatures became (n).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an annealing temperature control method in an induction heating apparatus mainly used for annealing cores of electrical equipment such as small electric motors and small transformers.

BACKGROUND OF THE INVENTION Iron cores for electrical equipment are often annealed after being punched to improve the efficiency of the equipment. This annealing is usually called residual stress relief annealing or strain relief annealing, and is annealed at 750°C to 850°C for 1 to 2 hours, and when all steps such as cooling are included, the temperature is 10 to 12%. It generally takes time.

Therefore, various annealing methods using induction heating devices as heating means have been proposed. That is, JP-A-58-210412
No. 5 discusses frequency and input power as heating conditions, and JP-A-59-123719 discusses the relationship between temperature and time as heating conditions, and JP-A-59-1430
Issue 26 is about annealing equipment. In these conventional examples, when annealing the iron core by induction heating, it is necessary to control the wet layer of the iron core to 720° C. or more and 850° C. or less.

However, when the iron core is moved through a heating tube and the heated iron core temperature is actually measured, the iron core temperature fluctuates by 1.5 degrees depending on the thickness of the iron core. . This means that when heating the iron cores individually in the heating coil, the distance between the iron cores is 0.5~
Since there is a gap of 1.0 mm, a phenomenon occurs in which the optical temperature measuring means for measuring the core temperature does not indicate the true core temperature. Therefore, when simply averaging the measured core temperature data, the true average annealing temperature cannot be obtained, so the output of the heating inverter is controlled based on this result.t)
It is difficult to set the temperature to a specified level, and when calculating the inverter output for the deviation between the optimum annealing temperature and the average annealing temperature, it is difficult to calculate the inverter output for the deviation between the optimum annealing temperature and the average annealing temperature. Because of the large temperature changes that occur, the individual cores are not annealed at a uniform temperature, and from that point of view,
I have to say that I am extremely dissatisfied.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the present invention eliminates periodic fluctuations caused by the thickness of the iron core from the temperature data measured by the optical temperature measuring means, and calculates the average temperature data. The true average annealing temperature is obtained by calculating the true average annealing temperature, and the output of the inverter is controlled by the inverter control means based on the result and the heating condition data of the iron core.

Function The present invention stores temperature data obtained by measuring the annealing temperature of the iron core using an optical temperature measuring means, and extracts periodic temperature data that is not the true temperature generated for each thickness of the iron core from the stored temperature data. By removing and averaging the true average annealing temperature, the deviation between the determined average annealing temperature and the preset optimal annealing temperature is calculated, and the iron core moves within the heating coil. The amount of heat required to reach the maximum annealing temperature is determined by the speed at which the annealing is performed and the weight of the core, so that the output of the inverter is controlled and the core is heated to a predetermined temperature.

EXAMPLE Hereinafter, one example of the present invention (1) will be described with reference to the drawings.

FIG. 1(a) is a temperature curve obtained by measuring the temperature of the iron core while the iron core is moving within the heating coil, using an optical temperature measuring means such as an infrared thermometer. According to the temperature curve, temperature variations that are not true temperatures occur due to temperature variations in the iron core and gaps between the iron cores. Therefore, in the present invention, periodic temperature variations depending on the thickness of the iron core are removed, and averaging processing is performed using true temperature data. In addition, the first
In the figure (A), A indicates analog data obtained by optical temperature measuring means, T indicates the moving time of each core, and A' indicates temperature data obtained by the core gap.

Figure 1 (b) shows sampled temperatures. Temperature data obtained by measuring the temperature of the iron core while the iron core is moving inside the heating coil using a temperature measuring means is measured at an arbitrary sampling time T.
Each S is stored in the memory section of the microcomputer,
After collecting temperature data for one or two pieces of iron core thickness L,
The pseudo average annealing temperature χd is determined and stored.

(1 to 2) In order to delete temperature data other than the normally occurring temperature variations from the temperature data sampled every 15 hours by the means, 1 is obtained by subtracting the normally occurring temperature variations Δχ from χd.
Calculate the quality and let the temperature be χL. Temperature data B is invalidated for temperatures less than χL from the sampled temperature data, and χ
Find d+1 and memorize it. Pseudo-average annealing temperature χd of the n-th core that successively moves in the heating coil
+n is obtained by comparing it with χL +n -1 and stored.

When the number of pseudo average annealing temperatures stored reaches the nth time, averaging is performed again to obtain an average annealing temperature χ that is close to the true value.

χd+I+ χd+2+−-1− χd+nχ 0
---When the number of pseudo average annealing temperatures stored is equal to or higher than the n+1th time, the oldest temperature data is deleted from memory, the newest temperature data is stored, and the averaging is performed so that the true value is always maintained. An average annealing temperature close to can be determined.

The sampling time 1.8 is 0.05 seconds to 0.1 seconds, and the normally occurring temperature variation is 15.degree. C. to 20.degree. C. according to an analysis of measured temperatures.

In addition, the number n of x+l stored before re-averaging should not be set to a constant number (it is preferable that it can be changed based on data on the thickness of the core and the speed at which the core moves through the heating coil).The above average annealing temperature calculation The process is shown in the flowchart of FIG.

Next, the temperature deviation Δ'F is determined from the average annealing temperature ("-F" and the set optimum annealing temperature), and the output of the inverter for induction heating is controlled so as to eliminate 8T.

In other words, since the average annealing temperature eliminates temperature changes due to short-term disturbances and periodic temperature changes due to gaps between the iron cores, the optimum annealing temperature can have a minimum range of annealing temperatures. , exceeding the annealing temperature range,
Alternatively, if it is below, ΔT is determined and the inverter output P (kw) corresponding to 8T is calculated.

P=IXS+cXΔT However, pm! Ix: Maximum output (kw) of induction heating inverter 3
max: Maximum speed at which the iron core moves within the heating coil (m
m 7 minutes) b: Correction coefficient depending on the shape and material of the iron core S: Speed at which the iron core moves within the heating coil (mm 7 minutes) C
: Coefficient for converting T into inverter output to temperature deviation.

Inverter output P is calculated using the equation shown above. The correction coefficient 1) and C are experimentally determined values, and B is about 0 to 30 culm degree, and C is about 0.7 to 1.3.

Therefore, there are several dozen cores inside the heating coil, and the temperature of the core near the heating coil is increasing, and the temperature of the core near the exit has reached the annealing completion temperature. The heated state becomes the optimum annealing temperature by controlling the inverter output in accordance with the temperature deviation ΔT.

FIG. 3 is an explanatory diagram of an annealing temperature control device for manufacturing an electrical equipment core for carrying out the present invention. As shown in the figure, the iron core 2 that continuously passes through the ulnoid heating coil 1 is gradually heated while passing through the heating coil 1, and reaches its maximum temperature near the outlet of the heating coil 1. An infrared thermometer 3, which is an example of optical temperature measuring means, is placed near the outlet of the heating coil 1 to measure the temperature of the iron core. The temperature measurement result is input to the A/D converter 5 via the optical-to-electrical converter 4, and is converted from an analog value to a digital value. The result is stored in the memory section 13 in the microcomputer 10 constituting the inverter control means, and T is determined as the temperature deviation by the average annealing temperature calculation process shown in FIG.

In order to calculate the induction heating inverter output, the speed of passing through the heating coil 1 is measured by a pulse signal generator 6, which is an example of speed detection means, and the pulse signal generator 6 is used as a pulse signal generator 6.
Convert it to a coefficient value, and send the result to the microcomputer 1.
0 and the coefficient necessary for calculating the inverter output, for example, the induction heating inverter maximum output Pm+lx (
kw), a coefficient for converting the temperature deviation ΔT into an inverter output, etc. are input to the microcomputer 10 from a floppy disk, which is an example of external auxiliary storage means.

Furthermore, for coefficients to be changed arbitrarily, keyboard 1
1, and the results are displayed on the display 12, allowing the input values and calculation results to be confirmed.

According to the heating conditions described above, an inverter output control signal is input from the microcomputer 10 to the heating inverter 8 through the D/A converter 9, and the inverter output is adjusted.

Effects of the Invention As described above, in the present invention, temperature changes due to short-term disturbances of the iron core and periodic temperature changes due to gaps between the iron cores are removed, the true average annealing temperature is determined, and from the average annealing temperature, In order to determine the deviation from the optimum annealing temperature and control the inverter output based on the result, all the iron cores passing through the heating coil are kept within a predetermined temperature range.
As a result, stable annealing is possible without defects due to insufficient or excessive cutting temperatures, ensuring the advantages of annealing using induction heating, and providing iron cores of good quality at low prices. can.

[Brief explanation of drawings]

Figure 1 (a) is a diagram showing analog actual measurement results of the core annealing temperature near the heating coil, Figure 1 (b) is a diagram showing the sampled temperature, and Figure 2 is a diagram showing the average annealing temperature calculation process. A diagram showing flowchart 1, and FIG. 3 are diagrams 111192 showing an embodiment of the present invention. 1... Heating coil, 2... Iron core, 3...
. . . Optical temperature measurement means, 4 . . . Optical-electrical converter, 5 . . . A/D converter, 6 . ...Pulse counter, 8.
... Heating inverter, 9 ... D/A converter, 10 ... Microcomputer, 11.
... Keyboard, 12 ... Display, 13 ... Memory section, 14 ... Floppy disk. Name of agent Patent attorney Toshio Nakao (1 person) Figure 1 (a) (b) Figure 2

Claims (2)

[Claims] (1) When continuously annealing the iron core of electrical equipment using the induction heating method, the temperature is measured by an optical temperature measuring means that measures the annealing temperature of the iron core, and the temperature data is stored. When calculating the average annealing temperature by
By removing periodic fluctuations due to core thickness,
Annealing temperature control for an electrical equipment iron core, which calculates a true average annealing temperature and controls an induction heating inverter output means so as to eliminate a deviation between an optimum annealing temperature preset for the iron core and the average annealing temperature. Method. (2) When controlling the output of the induction heating inverter, calculations are performed based on deviations based on conditions such as the speed at which the core moves within the heating coil, the shape of the core, and the material of the core. The method for controlling the annealing temperature of an electrical equipment core.