JPS63228589A - Control of bullet heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a heating control device for a fermentation heating device, and particularly to a control device for a billet heater.

B0 Summary of the Invention The present invention provides a heating device that transfers a billet, which is a member to be heated, into a heating furnace equipped with an induction heating coil using an inverter as an input power source and heats the billet by induction, based on heating conditions and measurement results. The present invention provides a control device flt that can perform appropriate heating control by calculating the output power of an inverter and controlling the inverter based on this calculated value.

C0 Conventional Technology Inverter devices are widely used as a power supply source for billet heaters for forging. An example of such a billet heater for forging? ! Shown in Figures 3 to 5. In the figure, 1 is a charging chute, 2 is a cylindrical billet that is an object to be heated, and 3 is a conveyor that conveys the billet 2 supplied from the charging chute 1. Reference numeral 4 designates pinch rolls disposed on the conveying downstream side of the conveyor 3 for transporting the billets 2 into the induction heating furnace 5. The on-site heating furnace 5 includes a furnace core tube 6 and heating coils 7a to 7C provided on the outer peripheral surface of the furnace core tube 6. Reference numeral 8 denotes a power supply section for supplying power to the heating coils 7a to 7C, which is comprised of an inverter, a load matching circuit, and the like. 9 is a thermometer for measuring the temperature of the heated billet.

Figure 3 shows the state at the start of heating, Figure 4 shows the state during steady heating, and Figure 5 shows the state at the end of heating. It shows. Charging chute 1
The billet 2 supplied to the conveyor 3 from
A pair of pinch rolls 4
It is sent into the induction 47IO thermal furnace 5 by the following steps. The nine billets 2 fed into the furnace inlet 5a are pushed by the subsequent billets fed by the pinch rolls 4 and move toward the outlet 5b at a constant speed in the furnace, while being induction heated by the heating coil 7 and gradually rising in temperature. Then, the temperature is raised to a predetermined temperature at the outlet section 5b of the furnace, and the material is discharged from the discharge shaker 10 and sent to the next process, a forging machine.

As shown in Figure 3, the number of billets 2 gradually increases in the induction heating furnace 5 at the start of heating.

Therefore, in this state, in order to reach the outlet 5b of the induction heating furnace 5 and bring the temperature of the nine billets 2 to a predetermined value, the power supplied to the heating coil must be gradually increased as the number of billets in the furnace increases. Control is required.

In addition, Figure @5 shows the state W14 at the end of heating, and the push rod 1
Billet 2 in the furnace using 1 tube together? An example of transporting to the exit portion 5b is shown. In this state, control is required to gradually reduce the electric power supplied to the heating filter 7 as the number of billets 2 in the furnace decreases.

However, the power input pattern for front-end processing and rear-end processing is no more than a scheduled operation of inverter output based on empirical operational data, and a general solution based on size cannot be determined, resulting in poor accuracy.

D0 Problems to be Solved by the Invention Conventionally, the power at the start and end of heating is often controlled based on empirical data. It is difficult to raise the temperature and it is affected by external disturbances. Therefore, the billet in an emergency state at the start or end of the process will not be heated to within the specified temperature range and will become a defective product that cannot be used as a baked and cooled material. was.

In addition, in operations where the same billet is heated and forged in bulk to produce large quantities, defective products are only a problem of looseness that reduces the material yield, but when the number of production lots of the same billet is small, there is a problem in material yield. was there. In other words, billet heaters began to be used for heating for forging in high-mix, low-volume production lines that produced the required items at the required time and in the required quantity, eliminating the need for pre-made product inventory. This poses a major problem in terms of yield because heating starts and ends frequently as billets are switched each time the size, paper type, or heating temperature changes. Therefore, in such high-mix, low-volume production operations, while quickly changing the forging mold, the operating conditions of the billet in the billet heater are accurately changed, and the billet is not wasted to be fed to the forging machine. is required.

Rounding means and function for solving the E0 problem The present invention has been made in view of the above-mentioned problems. Based on the temperature of The electric loss value in the electric circuit is calculated based on the capacity value, and the inverter is controlled based on these calculated values.

G. Embodiment FIG. 1 shows a control system (11) for a billet heater for forging according to an embodiment of the present invention. 11 is an AC power source, 12 is a power switch, and 13 is a transformer. 14 is an AC power source. A converter that converts to DC power, 16 is an inverter,
=ry Connected to the inverter 14 via reactors 15a and 15b, and converts the MR purchased power into high frequency AC power. 17
is a load matching circuit, which includes an impedance matching with the inverter 16, a matching transformer 18°, a capacitor switch 19, and a capacitor 201! L.

It consists of heating coils 20b and 21, and a tank circuit is formed by these heating coils 21 and capacitors 20'a and 20b. Reference numeral 22 denotes an induction heating furnace, and this induction heating furnace n is provided with a heating coil 21 consisting of coils 21&, 21b, and 21c and a detection section O. This detection section 23 is equipped with a speed sensor 24 for detecting the billet's approach speed and an induction A first temperature measuring section 25a for measuring the billet temperature at the inlet part of the heating furnace, a second temperature measuring part 25b for measuring the temperature of the induction heating furnace 22, and at the exit part of the induction heating furnace 22. It is constituted by a third temperature measuring section 26 for measuring the entire temperature of the billet. The first temperature measuring section 25a is a temperature sensor that detects the temperature of the billet at the entrance of the induction heating furnace n, and the second temperature measuring section 25b detects the temperature representative of the furnace body in the induction heating furnace. It is a temperature sensor. The temperature measurement section 26 of the WJ3 includes a temperature sensor 261 and 26b that detects the temperature of the billet located at the outlet of the induction heating furnace η.

27 is a signal converter, and a speed sensor 24. All the detection signals of the first temperature measurement section 25a@2, the temperature measurement section 25b of the second temperature measurement section 25, and the third temperature measurement section 26 are input, and these detection signals are converted into calculation signals. 28 is an arithmetic unit, which basically operates based on the signal from the signal converter 4 and various condition signals, the first arithmetic unit, and the operation signal of the first arithmetic unit and other condition signals. A second calculation unit 3 performs calculation processing based on the
Consists of 0.

32 is a signal conversion section of Wc2, l! The calculation signal Sv't of the calculation unit 30 of No. 2 is output as the gate signal S9.

In the control device having the above configuration, when the power switch 12 is turned on, the converter 14 operates to convert AC power to DC power. Further, the DC power is converted into AC power of a predetermined frequency by an inverter 16, and the AC power is supplied to the heating coil 21 through a load matching circuit. Induction heating furnace 2
2, the entrance speed of the billet is measured by the speed sensor 24 and the temperature sensor 25a.

The temperatures of the billet at the inlet and outlet are detected at 26&, 26b, and the temperature of the induction heating furnace η is controlled based on these detection signals.

Temperature control is carried out based on the following theoretical formula.

P = K x R2xn/Nx51x (T4-82
) ・(1)act I WRAD=2×((Tz+273)' (T3+
273) ')...(2) 3x (T
2-TC) ...(3]WELC=4X (f
XVC) 2=<41P I NV=P n+WELC
-rs) where P&. th The heating power required to raise the temperature of the billet, the diameter of the R billet, N the total number of billets inserted into the induction heating furnace, nh the number of billets being inserted into the heating furnace, the exit part of the T4fl heating furnace 22. WRAD is the power loss corresponding to the radiation loss, T2 is the calculated material temperature value, and T3 is the measured heating furnace temperature value. In addition, WCON is the power loss corresponding to the conduction heat loss, Tc is the temperature setting value of the coil, Sl is the moving speed of the billet, S2 is the detected value of the temperature of the billet at the inlet of the heating furnace, and Pn is the temperature value to be transferred to the heating coil. input power, PINV
is the output y/<-p.

The signal converter 27 of the river 1 inputs the speed detection signal S1+temperature detection signal S2+83+84 and outputs it to the arithmetic unit. Note that S4 is the actual temperature of the billet at the outlet of the heating furnace detected by the third temperature measuring section 26. The first calculation unit 29 executes calculations of equations (1) to (3) under the conditions of 4 with the calculation signal Sδ, the billet diameter R2, the number n of billets located in the heating coil, and the set temperature.
) input power to the heating coil Pn? calculate.

Pn=Pact+WRAD+Wc0N ''° (6) Furthermore, the second arithmetic processing unit 30 calculates the data signal S6 corresponding to equation (6), the capacitance value C of the tank circuit in the load matching circuit 17, the voltage vc of the tank circuit, and The required output power P I NVt' of the inverter is calculated by calculating equations (4) and (5) as the total frequency f condition, and this PI
A calculation signal S7 corresponding to NV is output. The second signal conversion unit 32 converts the calculation output signal 57-I of the second calculation unit 30 into
k input, output gate signal S9, and inverter 16.
This controls the output power of the induction heating furnace n, thereby controlling the entire temperature of the induction heating furnace n.

In addition, in the above calculation control, the difference between the heating set temperature T4 of the billet and the actual heating temperature detection value S4 is measured, and the PI"D control correction amount of the inverter output is calculated and determined based on the difference. When the heating temperature of the billet at the outlet changes due to disturbance, the chain line calculation unit 31 is used to correct the PID control amount, and (7) the total calculation is performed based on the output of the calculation processing unit 31.

P I NV + ΔP I NV - (7) In formula (7), Δ
PINV is a control correction amount for the inverter output power based on the difference between billet heating set temperature T4 and temperature detection signal S4. By controlling the output power of the inverter 16 based on the above equation (7), the temperature of the billet at the outlet of the induction heating furnace 22 can be controlled more precisely.

In the vA degree control described above, the total number of billets inserted is the number of billets in the furnace in a steady state, and is determined by the length of the billet. The number of billets in the coil is the number of billets in the furnace, and at the start and end of the process, a counting mechanism is provided to keep track of the number of bits in the furnace.
Alternatively, the number of coils in the coil may be calculated as time passes.

This is a representative temperature value found by integrating the temperature of the billet rising between the inlet and outlet of the material source Iff furnace, and it is preferable to find it as a pattern in advance for each type of heating condition. The furnace temperature is also the same as the material temperature.

Regarding the fill temperature, since cooling water is passed through the heating coil, the amount of heat carried away by this cooling water is the largest. It is good to be able to ask for it. Furthermore, the constants in each equation are predetermined as constant values or values related to setting conditions. When measuring the temperature of a billet only on the circumferential surface, n1 degrees is not good, so it is appropriate to use a temperature measuring means that measures the front and rear cross sections and the outer diameter surface of the billet, as shown in Figure 2.

That is, as shown in FIG. 2, the temperature sensors 26a and 26b are arranged on two intersecting lines (7,
When the billet 2 moves in the direction of the arrow in the figure, the temperature sensor 26
Temperature sensor 26bH detects the temperature at the front surface and the temperature at the outer diameter of the billet 2, and the temperature at the outer diameter and rear surface of the billet 2 is detected by the temperature sensor 26bH.

As shown in Figures 4 to WJ6, if there is a gap between the furnaces corresponding to the divided heating coils 7m, 7b, and 7c, and the gap is open, the temperature inside the induction heating furnace will decrease at that part. Since non-linear parts occur in the distribution, etc., and cause errors during control using the above calculation formula, it is preferable to eliminate gaps by connecting the furnace core tubes together or plugging the gaps with refractory cement. In this way, by eliminating all the gaps between the furnace core tubes, at the same time, the open part to the atmosphere in the middle of the heating furnace is eliminated, so that the amount of oxidation on the outer surface of the billet can be reduced.

H2 Effects of the Invention The present invention supplies electric power to the heating coil according to the amount of billet inserted into the heating furnace, and calculates the electric power for temperature rise and the heat loss in the heating furnace depending on the dimensions of the member to be heated.

Feed speed, number of heated members in the coil.

Calculated based on furnace temperature, inlet temperature and furnace outlet temperature,
Further, the electric loss in the electric circuit is calculated based on the voltage and frequency applied to the resonant circuit and the capacity of the power factor correction capacitor to calculate the total inverter output, and the inverter is controlled based on the inverter output and the furnace temperature. It is something.

Therefore, according to the present invention, it is possible to appropriately control the heating power in response to various conditions of the heated member during the heat treatment process of the heated member, and it is possible to completely eliminate the need for baking and cooling materials, thereby improving the yield. At the same time, effects such as being able to obtain a heating material optimal for forging processing can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a control device for a billet heater for forging according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a temperature sensor used in the control device of this embodiment. 3, 4, and 5 are schematic configuration diagrams of a heating device to which the present invention is applied. 16... Inverter, 17... Tank circuit, 18...
...Induction coil, 20a, 20b...Capacitor, 2
1. -...Heating coil which is a heater, 22...Induction heating furnace, 23...Detection unit, 24...Speed sensor, 25
a, 25b, 26a, 26b...temperature sensor,
Grave...Wc1 computing unit, 30...Second computing unit, 3
1...@3 calculation section.

Claims (2)

[Claims] (1) A billet heater control method that supplies electric power to a heating coil of a heating furnace via an inverter, and transfers a billet, which is a member to be heated, into the heating furnace and heats the billet by induction. Based on the dimensions, the moving speed, the number of billets in the heating furnace, the temperature of the billets at the inlet of the heating furnace and the heating set temperature of the billets at the exit, the temperature in the heating furnace and the coil temperature,
A power value for heating the billet and a power value corresponding to heat loss due to radiation and conduction in the heating furnace are calculated, and based on these calculated values, a power value for raising the temperature of the billet and each of the heat loss amounts are calculated. The power input to the heating coil, which is the sum of the power loss value due to The electric loss value in the electric circuit is calculated, and the total electric power value of the electric power input to the heating coil and the electric loss value is calculated, and A method for controlling a billet heater, characterized in that the output power of the inverter is controlled according to the total power value for a state of processing or the like. (2) In a control method for a billet heater, which supplies electric power to a heating coil of a heating furnace via an inverter, and transfers a billet, which is a member to be heated, into the heating furnace and heats the billet by induction, the shape of the billet is Based on the dimensions, the moving speed, the number of billets in the heating furnace, the temperature of the billets at the inlet of the heating furnace and the heating set temperature of the billets at the exit, the temperature in the heating furnace and the coil temperature,
A power value for heating the billet and a power value corresponding to heat loss due to radiation and conduction in the heating furnace are calculated, and based on these calculated values, a power value for raising the temperature of the billet and each of the heat loss amounts are calculated. The power input to the heating coil, which is the sum of the power loss value due to Calculate the amount of electricity loss in the electric circuit by calculation, and calculate the total power value of the power input to the heating coil and the amount of electricity loss, and calculate the amount of electricity according to the total power value. In addition to controlling the output power of the inverter, the difference between the heating set temperature and the actual temperature of the billet at the outlet of the heating furnace is detected, and if there is a difference between the heating set temperature and the actual temperature, the temperature difference is detected. A control method for a billet heater, comprising: correcting an inverter output based on a signal of the inverter; and controlling output power of the inverter in accordance with the correction signal.