JPH0538545A - Induction heating apparatus - Google Patents

Abstract

PURPOSE:To make then umber of discharging of materials to be heated to the min. limit by heating the material to be heated to the prescribed temp. without uneven heating as less as possible at the time of restarting the operation after stopping. CONSTITUTION:A first heating coil 5 for heating a billet 2 with high frequency induction power from a first frequency induction inverter device 1 and a second heating coil 5 for heating the billet 2 heated with the first heating coil 3, with the high frequency induction power from a second high frequency induction inverter device 4 and pinch roll mechanism 6 for continuously carrying the billets 2 in both heating coils 3, 5, are provided. Then, a shifting command circuit 11 for outputting the command by starting the pinch roll mechanism 6 to carry the billet by distance having shorter than length of the second heating coil 5 at the time of reaching to the intermediate temp. between temp. TS of the billet 2 in the second heating coil in starting time of the second high frequency induction inverter device 4 and the finish heating temp. TE, is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating apparatus for forging, and more specifically, even if the material to be heated may stop in the heating coil during the processing of the material to be heated, the material to be heated is restarted. The present invention relates to an induction heating device that can uniformly heat a heating material to a predetermined temperature for forging.

[0002]

2. Description of the Related Art As a conventional apparatus of this type, one described in "Industrial heating" Vol. 27, No. 4 (published by the Japan Industrial Reactor Association in 1990) is known. The high-performance billet heater (induction heating device) described in this publication will be described with reference to FIGS. As shown in FIG. 4, this induction heating device includes a heating coil 3 for a low temperature region that heats a material (billet) 2 to be heated by high frequency power from a high frequency inverter device 1, and a billet heated by the heating coil 3. A heating coil 5 for a high temperature range for heating 2 to a predetermined temperature by high frequency power from a high frequency inverter device 4, and a pinch roller mechanism 6 for continuously transporting the billet 2 in both heating coils 3 and 5 Is configured. Further, this induction heating device includes a motor 7 that drives the pinch roller mechanism 6, a speed control device 8 that controls the rotation speed of the motor 7, and a control device 9 that controls the speed control device 8 and the high-frequency inverter devices 1 and 4, respectively. It has and.

Next, the operation will be described. First, the normal operation will be described. During the normal operation, the billet 2 is continuously conveyed by the pinch rotor mechanism 6 through the heating coil 3 for the low temperature region and the heating coil 5 for the high temperature region, and a predetermined temperature is maintained during the conveyance. After being heated to a temperature of about 1200 ° C. (usually around 1200 ° C.), it is discharged from the induction heating device and conveyed to a post-process (press device) not shown. During this normal operation, the billet 2 in both heating coils 3 and 5 is indicated by A in FIG.
The temperature rises from room temperature to a predetermined temperature through the smooth temperature rising process shown in. This heating pattern is determined by the power supply from the high-frequency inverter devices 1 and 4 to the heating coils 3 and 5 based on the control of the control device 9 including the warming operation described later.

Next, the operation at the time of abnormality will be described.
During the continuous operation of the induction heating device, if the press device in the subsequent process has a failure or the like and is stopped, the conveyance of the billet 2 from the induction heating device is immediately stopped. That is, the pinch roller mechanism 6 is stopped via the motor 7 based on a stop command from the speed control device 8 based on a command from the control device 9 to stop the conveyance of the billet 2, and the high frequency inverter devices 1 and 4 The power supply to the heating coils 3 and 5 is stopped. And if the failure of the press machine is recovered,
Restart the operation. When restarting the operation, each heating coil 3,
The temperature inside 5 has decreased as shown in FIG. 5B, and the longer the time until restarting, the greater the temperature decrease. Therefore, the temperature of the billet 2 discharged from the heating coil 5 for the high temperature region when the operation of the induction heating device is restarted has not reached the regular temperature (around 1200 ° C. in FIG. 5), and if it is left as it is, the press treatment in the subsequent step may be performed. Therefore, the billet 2 is discharged by a bypass device (not shown) before the pressing device. At this time, the induction heating device is brought into a heat retention operation state as described later.

In order to keep the induction heating device warm, the pinch roller mechanism 6 is stopped and the billet 2 is kept stationary. First, only the high-frequency inverter device 4 for the high temperature region is activated and the heating coil 5 is activated. Supply high frequency power. Thereby, the billet 2 having the heating coil 5 for the high temperature range therein is heated to raise the temperature. When the temperature of the billet 2 is increased, the heating coil 5 for the high temperature region is close to parallel in consideration of soaking so that the temperature rise is small. When the temperature of the billet 2 reaches the normal temperature rising curve shown in FIG.
The speed control device 8 operates based on the command to output a conveyance command to the motor 7 to rotate and drive the pinch roller mechanism 6 to restart the conveyance of the billet 2. Time to restart is 10
For a short time of about a minute, the temperature of the billet 2 in the heating coil 3 for the low temperature range is reduced to a small degree, and after the operation is restarted, the billet 2 has a predetermined temperature before being discharged from the heating coil 5 for the high temperature range. Is raised to a temperature close to.

[0006]

However, in the conventional induction heating apparatus, the temperature of the billet 2 discharged from the heating coil 5 for the high temperature range is raised to a state close to a predetermined temperature by performing the heat retention operation. However, the following problems still remained. That is, the heating coils 3 and 5 are generally divided into a plurality of blocks, and each block is wound with a coil as shown in FIG.
Since there is a part that is not heated between the blocks, the billet 2 is not heated in these parts even during the heat retention operation, and even when the heated part reaches a predetermined temperature, the non-heated part is still in the low temperature state. When the operation is restarted, the billet 2 is unloaded from the heating coil 5 for the high temperature region while partially forming the low temperature state, and the billet 2 discharged to the outside of the system increases. Moreover, generally, as the capacity of the induction heating device increases, the heating coils 3 and 5 also lengthen and the number of blocks increases, resulting in an increase in the number of billets 2 discharged at a low temperature.

The present invention has been made to solve the above-mentioned problems, and when the operation is resumed after the stop, the billet (material to be heated) is heated to a predetermined temperature as evenly as possible to reduce the number of materials to be discharged. An object is to provide an induction heating device that can be minimized.

[0008]

SUMMARY OF THE INVENTION An induction heating apparatus of the present invention comprises a first heating coil for heating a material to be heated by high frequency power from a first high frequency inverter device, and a material to be heated heated by the first heating coil. Second heating the high temperature to a predetermined temperature by high frequency power from the second high frequency inverter device
In an induction heating device including a heating coil and a transport device that continuously transports the heated materials in both heating coils, the heated material in the second heating coil when the second high-frequency inverter device is started. And a final heating temperature when an intermediate temperature is reached, the transfer apparatus is configured to start up the transfer device and output a command to transfer by a distance shorter than the length of the second heating coil. Is.

[0009]

According to the present invention, the material to be heated is heated by the second heating coil during the warming operation, and the temperature of the material to be heated in the second heating coil and the final heating temperature at the time of starting the second high frequency inverter device. When the intermediate temperature between the first heating coil and the second heating coil is reached, the movement command circuit is activated to start the transportation device, and the transportation device conveys the material to be heated for a distance shorter than the length of the second heating coil to be heated by the second heating coil. By heating the low temperature portion of the material to uniformly heat the material to be heated to the final heating temperature, it is possible to reduce the number of materials to be discharged to the outside of the system.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Based on the embodiments shown in FIGS. 1 to 3, the same or corresponding parts as in the conventional one will be designated by the same reference numerals, and the characteristics of the present invention will be mainly described. In each drawing, FIG. 1 is a circuit configuration diagram showing an embodiment of the induction heating device of the present invention, and FIG. 2 is a pattern showing a temperature rise pattern of a material to be heated when the induction heating device shown in FIG. 1 is used. FIG. 3 and FIG. 3 are time charts showing the conveyance state by the induction heating device shown in FIG.

As shown in FIG. 1, the induction heating apparatus of the present embodiment is similar to the conventional one, in which the billet 2 is heated by the high frequency power from the first high frequency inverter apparatus 1 for the low temperature range.
A heating coil 3, a second heating coil 5 for a high temperature region that heats the billet 2 heated by the first heating coil 3 to a predetermined temperature by the high frequency power from the second high frequency inverter device 4, and both of these heating coils 3 Billet 2 in 5
And a motor 7 for driving the pinch roller mechanism 6.
And a speed control device 8 for controlling the rotation speed of the motor 7, and a control device 9 for controlling the speed control device 8 and the high frequency inverter devices 1 and 4, respectively.

Thus, in the induction heating apparatus of this embodiment, the temperature detector 10 for measuring the temperature of the billet 2 in the second heating coil 5 and the activation of the second high frequency inverter unit 4 by the temperature detector 10. Temperature TS of billet 2 measured at time
And an intermediate temperature is calculated based on a final heating temperature TE (for example, around 1200 ° C. in the conventional example) set in advance, and the pinch roller mechanism 6 is started based on the input of the calculation result, and thereby the billet 2 And a movement command circuit 11 that outputs a command to convey the sheet by a distance shorter than the length of the second heating coil 5. Further, the induction heating device of the present embodiment is provided with a pinch roller rotation speed detector 12 that measures the transport distance of the billet 2.

That is, the movement command circuit 11 stores the temperature TS of the billet 2 measured at the time of starting the second high-frequency inverter device 4, and the conveyance during static heating is performed based on this temperature TS and the final heating temperature TE. Temperature T at which to perform
1, the intermediate temperature is calculated from T1 = (TS + TE) / 2, and when the temperature of the billet 2 in the second heating coil 5 reaches T1, a movement command is output to the speed control device 8 to pinch it via the motor 7. It is configured to drive the roller mechanism 6 to rotate. Then, the transport distance of the billet 2 transported by the pinch roller mechanism 6 is measured by the pinch roller rotation speed detector 12, exceeds the distance between blocks of the second heating coil 5 (usually 20 to 50 mm), and, for example, 1
It is transported by 00 mm. At this point, the movement command circuit 11 operates to output a stop command to the speed control device 8 to output the billet 2
Of the billet 2 is stopped by the second heating coil 5 to heat the low temperature portion located between the blocks to the final heating temperature TE.

As the movement command circuit 11, for example, a commercially available programmable controller can be used, and as the pinch roller rotation speed detector 12, for example, a rotary encoder or a proximity switch and a rotating disk are combined. It can be used.

Next, the operation of the induction heating apparatus of this embodiment will be described with reference to FIGS. During normal operation, as shown in FIG. 2A, the billet 2 is heated and heated in the same heating pattern as in the conventional case, and when the press device is stopped due to a failure or the like, the induction heating device is stopped in the same manner as in the conventional case and the temperature detector 10 The temperature of the billet 2 in the heating coil 5, which is measured by, decreases in the same pattern as the conventional one as shown in FIG. 2B.

When the operation of the press device is restarted, a command to that effect is output to the induction heating device, and the induction heating device outputs a start command from the control device 9 to the first high frequency inverter device 4 based on this command. When high frequency power is supplied to the second heating coil 5, the second heating coil 5 starts heating and raising the billet 2, and the temperature detector 10 measures the temperature TS of the billet 2. Movement command circuit 1
1 stores a temperature TS measured by the temperature detector 10, and this temperature TS and a preset final heating temperature T
The intermediate temperature T1 is calculated based on E, and when the temperature detector 10 measures this temperature T1, a drive command is output to the speed control device 8 as shown in FIG. Is driven to convey the billet 2 by 100 mm and stop. At this stop position, the first heating coil 3 and the second heating coil 5 heat the low temperature portion of each billet 2, that is, the non-heated portion between the blocks of the heating coil 5 to the final heating temperature TE, as shown in C of FIG. The normal operation is started and the subsequent billet 2 is heat-treated in a normal state. The billet 2 discharged from the outlet of the second heating coil 5 according to the moving distance (100 mm) during static heating cannot be pressed because the temperature is low, and the billet 2 is discharged to the outside of the system. Since the length of the billet is usually 100 to 200 mm, the number of billets 2 discharged to the outside of the system is about 1 to 2 and the number of billets 2 in the normal heating coil is 20.
Comparing with the number of billets being 50, the loss of one or two billets 2 is not a problem in operation.

As described above, according to this embodiment, the billet 2 in the heating coil 5 is conveyed to heat the non-heated portion located between the blocks of the heating coil 5 during the stationary heating in the heat retention operation. It is possible to supply the billet 2 to the pressing device in the next step by heating the billet 2 to the final heating temperature TE (1200 ° C.) while minimizing the uneven heating of the billet 2. In this case, since the degree of heating in each block is not uniform in one block, even if the billet 2 is moved during static heating, the billet 2 cannot be brought into a completely uniform heating state, but at 1200 ° C. On the other hand, the temperature variation is within the allowable range of about 30 ° C. at the most, and it does not pose a problem in the actual process.

In the above embodiment, the temperature T1 at which the billet 2 is moved during stationary heating is set to the temperature T1.
Although the average value of the stationary heating start temperature TS and the final heating temperature TE was taken, the temperature T1 may be a temperature substantially in the middle of these temperatures.

[0019]

As described above, according to the present invention, when the operation after the stop is restarted, the material to be heated can be heated to a predetermined temperature as evenly as possible to minimize the number of materials to be discharged. It is possible to provide an induction heating device that can do so.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of an induction heating device of the present invention.

FIG. 2 is a pattern diagram showing a temperature rising pattern of a material to be heated when the induction heating device shown in FIG. 1 is used.

FIG. 3 is a time chart showing a conveyance state by the induction heating device shown in FIG.

FIG. 4 is a circuit configuration diagram showing an example of a conventional induction heating device.

5 is a pattern diagram showing a heating pattern of a material to be heated when the induction heating device shown in FIG. 4 is used.

FIG. 6 is an explanatory diagram illustrating a block configuration of a heating coil of the induction heating device.

[Explanation of symbols]

 1 1st high frequency inverter device 2 Billet (material to be heated) 3 1st heating coil (for low temperature range) 4 2nd high frequency inverter device 5 2nd heating coil (for high temperature range) 11 Movement command circuit

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[Procedure amendment]

[Submission date] November 8, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

Next, the operation will be described. First, the normal operation will be explained. During normal operation, the billet 2
The pinch roller mechanism 6 continuously conveys the heating coil 3 for the low temperature region and the heating coil 5 for the high temperature region, and in the state where the temperature is raised to a predetermined temperature (usually around 1200 ° C.) while being conveyed. It is discharged from the induction heating device and conveyed to a post-process (press device) not shown. During this normal operation, the billet 2 in both heating coils 3 and 5 is indicated by A in FIG.
The temperature rises from room temperature to a predetermined temperature through the smooth temperature rising process shown in. This heating pattern is determined by the power supply from the high-frequency inverter devices 1 and 4 to the heating coils 3 and 5 based on the control of the control device 9 including the warming operation described later.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016] In Thus, at the time of resuming operation of the press, induction command to that effect to the heating apparatus is outputted, the induction heating device from the control device 9 based on the this Directive to the first high-frequency inverter unit 4 When a start command is output and high-frequency power is supplied to the second heating coil 5, the second heating coil 5 starts heating and raising the billet 2, and the temperature detector 10 measures the temperature TS of the billet 2. Movement command circuit 1
1 stores a temperature TS measured by the temperature detector 10, and this temperature TS and a preset final heating temperature T
The intermediate temperature T1 is calculated based on E, and when the temperature detector 10 measures this temperature T1, a drive command is output to the speed control device 8 as shown in FIG. Is driven to convey the billet 2 by 100 mm and stop. At this stop position, the first heating coil 3 and the second heating coil 5 heat the low temperature portion of each billet 2, that is, the non-heated portion between the blocks of the heating coil 5 to the final heating temperature TE, as shown in C of FIG. The normal operation is started and the subsequent billet 2 is heat-treated in a normal state. The billet 2 discharged from the outlet of the second heating coil 5 according to the moving distance (100 mm) during static heating cannot be pressed because the temperature is low, and the billet 2 is discharged to the outside of the system. Since the length of the billet is usually 100 to 200 mm, the number of billets 2 discharged to the outside of the system is about 1 to 2 and the number of billets 2 in the normal heating coil is 20.
Comparing with the number of billets being 50, the loss of one or two billets 2 is not a problem in operation.

Claims (1)

[Claims] 1. A first heating coil for heating a material to be heated by high-frequency power from a first high-frequency inverter device, and a material to be heated heated by the first heating coil are predetermined by high-frequency power from a second high-frequency inverter device. In an induction heating device comprising a second heating coil for heating to a temperature and a carrying device for continuously carrying a material to be heated in both heating coils, the second heating at the time of starting the second high frequency inverter device. A movement command circuit that outputs a command to start the above-mentioned transfer device when the temperature reaches an intermediate temperature between the temperature of the material to be heated in the coil and the final heating temperature and to transfer the transfer device for a distance shorter than the length of the second heating coil. An induction heating device characterized by being provided.