JPH01286284A - Heating method of heated material by induction heating - Google Patents

Abstract

PURPOSE:To restrict the useless heating during waiting and the formation of a cooled hot material by measuring the temperature of a heated material after passed through a first induction heating coil, and controlling the supply capability of a second induction heating coil. CONSTITUTION:When a heat insulation is required, the ocsillation of inverters 2, 6 are stopped by a heat insulation signal. On receiving a resumption signal, the temperature up value to be increased by a coil 5 is calculated by a computing element 8 based on the signal of a temperature detector 7 disposed between induction heating coils 1, 5. Then, a processable feed rate is calculated from the applicable voltage of the inverter 6. The feed rate command is given to the motor for a carrier pinch roller 7 to make the inverter 6 output the maximum output, the outlet temperature of the coil 1 is compensated by the heating coil 5, and the heated material is heated to a determined temperature and taken out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of heating a material to be heated by induction heating during continuous feeding.

[Conventional technology]

Conventionally, unlike gas furnaces and heavy oil furnaces, when heating using electric energy, that is, induction heating, if electricity is supplied, the temperature will be equal to the heat radiation loss, that is, the supplied power will be lost as a loss. The temperature will rise to a point where the power is in equilibrium.

In Figures 4 and 5, (1) is an induction heating coil;
(2) is an inverter, (3) is a transformer noise, and (4) is a capacitor for improving the stupidity rate. Usually induction heating coil (1)
However, there was only one inverter (2) that supplied power. Therefore, as shown in FIG. 5, a larger amount of power is applied to the coil toward the entrance, and the power is reduced toward the exit, thereby eliminating temperature unevenness from the surface to the center. Therefore, in order to keep the temperature of the material inside the coil constant, it is necessary to increase the power toward the outlet where the temperature is higher, and reduce the power toward the entrance. A transformer path is installed in the coil to adjust the power. Furthermore, if this was done alone, the temperature would drop at the seam between the coils, where there is no heat generating means, so a slight feed was applied.

[Problem to be solved by the invention]

Conventional heating methods generate energy loss due to unnecessary heating during the stop period. Moreover, since the heated material is discharged outside the coil, the heated material generates scale, which poses the problem of degrading the quality of the forged product when it is reused.

The present invention has been made to solve the above-mentioned problems, and provides a heating method using induction heating that minimizes wasteful heating during standby and the generation of burnt material.

[Means to solve the problem]

In this invention, the induction heating coil is divided into a plurality of parts, and high-frequency heating power is supplied by an independent inverter to each part. A temperature detector is attached between each induction heating coil, and the power of the induction heating coil in the subsequent stage is controlled to control the temperature. Compensate.

[Effect]

In this invention, the temperature of the material to be heated that has passed through the first induction heating coil is measured and the power supplied to the second induction heating coil is controlled. maintain the temperature at a predetermined temperature.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In Figures 1 and 2, (1) to (4) are the same as before. (5) is an induction heating coil placed downstream of the induction heating coil (1), and (6) is an induction heating coil. (5)
An inverter (7) supplies power to the inverter, and a temperature detector (7) is placed between both induction heating coils to detect the temperature of the heated material (not shown) transferred by the skid rail 0. (8
) is a calculator that calculates the output power of the inverter (6) from the temperature detected by the temperature detector (7) and the set temperature of the heated material (not shown) when it exits the induction heating coil (5). Issue a control signal. (9) is the induction heating coil (1) (
5) A material to be heated (not shown) is transported by a skid rail provided in the interior. Oq is the pinch roller, the target is the feeding conveyor, and the rabbit is the pedestal.

Next, the operation will be explained. Now when you need to keep warm,
The oscillation of both inverters (2) and (6) is stopped by the heat retention signal. As shown in Figure 3, the temperature of the material inside the induction heating coils (1) and (5) is determined by the steady temperature rise pattern curve (a
) to the curve (υ), which varies depending on the stop time.When the signal to resume operation is received, the induction heating starts from the signal from the temperature sensor (7) installed between the induction heating coils (1) and (5). The temperature increase value Δθ that should be raised by the coil (5) is calculated. Next, the feed rate that can be processed is calculated from the power that can be applied by the inverter (6). The inverter (6) outputs the maximum output, and the heating coil (5) compensates the outlet temperature of the induction heating coil (1) to heat the induction heating coil (1) to a predetermined temperature. These calculations are performed by the arithmetic unit (8).

For example, if the final outlet temperature is 1.250°0, the coil (
1), the outlet temperature is 1000℃ compared to 1200℃ at steady state.
℃, 250℃ for a steady temperature increase of 50℃
The temperature increases by υ. -50 material 10004. /Hr treatment, if the specific gravity is 0.15Kca//"?"O, the net power required for the induction heating coil (5), 8.72Kw, becomes 43.6Kw, which is five times as much. The heat radiation loss is the same in both cases because the heating temperature is the same, and is approximately 16 Kw if the coil length of the induction heating coil (6) is 500 volts. Therefore, in order to obtain the same temperature increase value, if the applied power is constant, the feed rate S at steady state. On the other hand, the start-up feed speed Sx after warming is (1
)Formula%Formula% can be used. The inverter (2) supplies an output voltage VX commensurate with the feed, and the induction heating coil (1) supplies power that provides a steady temperature rise value. For example, the output voltage in steady state is V. Then, when Vx is expressed by formula (2), the temperature increase pattern during steady state is maintained. Therefore, the area where the material at the point where curve (b) and curve (a) overlap in FIG. 3 reaches the exit point of the coil (1) is the region in which the operation is performed at the start-up speed Sx after warming.

〔Effect of the invention〕

As described above (according to this invention), in the continuous feed 9-type induction heating device, the cold temperature is compensated for when the operation is stopped and restarted, thereby reducing wasted heat retention power. It is possible to suppress the generation of burnt materials.

[Brief explanation of the drawing]

Figure 1 shows a skeleton to which one embodiment of this invention is applied;
The figure is a front view showing the configuration of Fig. 1, Fig. 3 is an explanatory diagram showing the temperature increase pattern, Fig. 4 is a skeleton using the conventional method, and Fig. 5 is the power of the induction heating coil shown in Fig. 4. It is an explanatory diagram showing division of labor. In the figures, % (1) and (5) are induction heating coils, (2 and 6) are inverters, (7) are temperature detectors, and (8) are computing units. In addition, the same symbols in each figure are the same - or a corresponding portion.

Claims (1)

[Claims] (1) A first inverter and a first induction heating coil are connected, and a second inverter and a second induction heating coil are connected respectively, and the material to be heated is heated from the first induction heating coil to the second induction heating coil. The material to be heated is heated by induction while being transferred to a coil, the temperature of the material to be heated is detected between both induction heating coils, and the temperature of the material to be heated is determined from the temperature at which the material to be heated is taken out from the second induction heating coil and the detected temperature. A method for heating a material to be heated by induction heating, the method comprising determining the output power to a second inverter.