JPH0698442B2 - Induction heating method - Google Patents

Description

The present invention relates to an induction heating method for heating a material to be heated in a forging line.

[Prior Art] FIG. 3 shows a conventional induction heating apparatus disclosed in, for example, JP-A-53-90035. In the figure, (1) is an induction heating coil for induction heating while feeding a material (2) to be heated,
(3) is a feeding device, which is constituted by a pinch roller. (4) is an electric motor for driving the feeding device (3),
(5) is a controller for controlling the electric motor (4), and (6) is a rotation command relay for issuing a rotation command to the controller for controlling the electric motor (5), which has a contact (6a) which is closed by excitation. (7) is a power control device that applies power to the induction heating coil (1), (8) is a power application command relay that issues a power application command to the power control device (7), and is a contact point that is closed by excitation. It has (8a). (9) is each relay (6)
It is a programmable controller that controls (8).

Next, the operation will be described. In Figure 3 and Figure 4, the induction heating coil (1), when a failure other than the forging device of the feed device, Fig. 4 (b) the controller at time t ₁ as shown in (5) by connexion motor ( The rotation of 4) is lowered to slow the feeding of the material to be heated (2).

At the same time, the electric power control device (7) lowers the electric power supplied to the induction heating coil (1) at time t _{1 as} shown in FIG. Then, when an operation restart command is issued at time t ₂ , steady power is supplied to the induction heating coil (1) to restart the transportation. But,
As shown in FIG. 4 (c), the temperature rise of the heated material (2) is delayed.

When the induction heating device fails, the programmable controller (9) demagnetizes the relays (6) and (8) to stop the feeding device (3) at time t _{1 as} shown in FIG. 4 (e). and by connexion stops the power control unit (7) the power supply of FIG. 4 to the induction heating coil at time t ₁ as shown in (d) (1). When at time t ₂ resuming operation command exits, the relay (6) (8) starts to feed the exciter (3) is conveyed, operating power to the induction heating coil (1) is applied to resume To be done. However, as shown in FIG. 4 (f), since the temperature of the heated material (2) during the operation stop is large, the temperature increase of the heated material (2) after the restart is delayed as compared with the former case.

[Problems to be Solved by the Invention]

Since the conventional induction heating method is as described above,
There is a problem that a large amount of waste material is discharged when carrying out the heat retention operation while transporting the heat target material, or when the transport of the heat target material is stopped and the power supply to the induction heating coil is also stopped.

The present invention has been made to solve the above problems, and provides an induction heating method that can reduce the waste of the material to be heated.

[Means for Solving the Problems]

The induction heating device according to the present invention is configured such that the conveyance of the material to be heated corresponding to the stop time is stopped and the stationary heating for applying the electric power to the induction heating coil is performed when the operation is restarted.

[Action]

In the induction heating device according to the present invention, the material to be heated reaches the regular temperature quickly by performing stationary heating when the operation is restarted, so the amount of waste material to be heated is reduced.

Example of Invention

An embodiment of the present invention will be described below. The structure is the same as the conventional one shown in FIG. The programmable controller (9) is provided with a table in which the operation stop time and the stationary heating time (electric power before the operation stop) are associated with each other based on actual measurement data as shown in FIG.

Next, the operation of the present invention will be described. In FIG. 3, when a failure occurs at time t ₁ in FIG. 2 (a) when the induction heating coil (1) is operated by applying a predetermined voltage, electric power to the induction heating coil (1) is increased. The feeding and feeding of the feeding device (3) is stopped. When the re-operation command is issued at time t _2, the stop time T ₁ of the from time t ₁ to t ₂ stores programmable controller (9), a stationary heating time T ₂ corresponding to the stop time T ₁ Read from the table and perform static heating. During this time, the conveying speed of the second view the material to be heated as shown in (b) (2) is zero, that is, stops, is conveyed at the same speed as before the stop at time t ₃ after static heating time T ₂ has elapsed Be started. The temperature of the material to be heated (2) drops from time t ₁ to t ₂ as shown in FIG. 2 (c), but it does not reach the temperature before operation stop during the stationary heating time T _2. Be heated.

In the above embodiment, the electric power applied to the induction heating coil (1) during static heating was the same as the electric power before the operation was stopped, but the first electric power suitable for the material, shape, size, etc. of the material to be heated or environmental conditions. It is possible to prepare a table similar to that shown in the figure and read the static heating time T ₂ corresponding to the stop time T ₁ to set the static heating.

〔The invention's effect〕

As described above, according to the present invention, when the material to be heated is present in the induction heating coil, the power supply to the induction heating coil is stopped. Since the stationary heating is performed, the material to be heated that has passed through the induction heating coil is heated to a predetermined temperature, so that the amount of waste can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a table of stop time vs. static heating time provided in a programmable controller (9) showing one embodiment of the present invention, and FIG. 2 is a time chart for explaining one embodiment of the present invention. FIG. 3 is a configuration diagram showing a configuration to which a conventional method and an embodiment of the present invention are applied, and FIG. 4 is a time chart for explaining the conventional method. In the figure, (1) is an induction heating coil and (2) is a material to be heated. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A material for continuously heating a material to be heated in an induction heating coil to heat it to a predetermined temperature, wherein the material to be heated is retained in the induction heating coil while being retained therein. After stopping the transfer and the power supply to the induction heating coil, a predetermined power is supplied to the induction heating coil while stopping the transfer of the material to be heated when restarting the operation, and the supplied power and the stop time are The method for induction heating is characterized in that the heating of the material to be heated is started after stationary heating for a time calculated from the above.