TWI874652B - Control method for continuous heat treatment equipment - Google Patents

Abstract

[Problem to be solved] The application discloses a control method for continuous heat treatment equipment that can achieve good temperature uniformity in the width direction in total. [Solution] The continuous heat treatment equipment 1 is provided with a first heating section, a second heating section and a third heating section, which are arranged along a conveyance direction F of a metal member, a control section that controls a first output power, a second output power and a third output power output to each of the first heating section, the second heating section and the third heating section, respectively, and a first measurement section that measures a first voltage and a first current in the first heating section. The first heating section, the second heating section and the third heating section are solenoidal induction heating, transverse induction heating and resistance heating, respectively. The control section rationally proportions the output share of each heating section, and also calculates a equivalent impedance in a parallel resonance circuit based on the first voltage and first current, and controls the first output power so that the first output power decreases when the equivalent impedance becomes larger than a threshold value.

Description

Control method of continuous heat treatment equipment

The present invention relates to a control method for a continuous heat treatment device for continuously performing heat treatment on a metal component.

Electromagnetic induction heating can achieve rapid temperature rise and instant temperature regulation because it causes the metal component to generate heat by induction current. Electromagnetic induction heating is roughly divided into solenoid type and transverse type. The solenoid type is to arrange a heating coil wound into a solenoid shape around the metal component, and let the alternating current flow in the heating coil, so that it generates an induced current on the surface of the metal component, thereby heating the metal component. The transverse type is configured as follows: a pair of heating coils are separated in the thickness direction of the metal component and arranged opposite to each other to sandwich the metal component, so that the alternating magnetic field generated by the heating coils penetrates in the thickness direction of the metal component.

Patent document 1 discloses a heating device, which has a transverse induction heating part and a solenoid induction heating part. The transverse induction heating part can compensate for the temperature non-uniformity in the width direction caused by the roller cooling water due to rolling delay, and the solenoid induction heating part can compensate for the temperature non-uniformity in the length direction.

Patent document 2 discloses the following method: by using transverse and solenoid induction heating sections provided in the preheating belt of the continuous annealing equipment, the thin steel plate is preheated to a temperature 200°C lower than the preheating temperature (lower than the Curie temperature Tc of the thin steel plate) and the preheating temperature. In addition, Patent document 2 discloses the method of providing a heating belt and a uniform heating belt on the downstream side of the preheating belt. Prior art documents Patent document

Patent document 1: Japanese Patent Publication No. 2003-290812 Patent document 2: Japanese Patent Publication No. 2016-98420

Invention Problems to be Solved

Although the solenoid type has excellent temperature uniformity in the width direction of the metal component, when the temperature of the metal component rises and approaches the Curie temperature of the metal component, the relative magnetic permeability of the metal component decreases significantly, so the penetration depth of the induced current becomes deeper. As a result, in a thinner metal component, the induced current flowing on the front side of the metal component and the induced current flowing on the back side cancel each other out, which greatly reduces the heating efficiency. In contrast, in the horizontal type, although it is difficult to be affected by the thickness of the metal component, because the induced current is concentrated at the ends of the width direction of the metal component, the ends are overheated, so the temperature uniformity of the width direction of the metal component is worse than that of the solenoid type.

In Patent Document 1, although it is intended to compensate for temperature non-uniformity by using a lateral induction heating unit and a solenoid induction heating unit, it is difficult to say that sufficient temperature uniformity can be obtained for a thin metal component.

Patent Document 2 only discloses a method of rapidly heating a thin steel sheet to near the Curie temperature by a solenoid-type induction heating unit, but does not disclose a method for achieving overall good control of the temperature uniformity in the width direction in a continuous annealing device.

Therefore, the subject of the present invention is to provide a control method for continuous heat treatment equipment that can achieve good temperature uniformity in the width direction orthogonal to the conveying direction of metal components. Means for solving the subject

In order to solve the above-mentioned problem, the control method of a continuous heat treatment device of one aspect of the present invention is characterized in that: the aforementioned continuous heat treatment device comprises: a first heating part, a second heating part and a third heating part, which are arranged in sequence and continuously along the conveying direction of the metal component; a control part, which controls the first output power, the second output power and the third output power output to the aforementioned first heating part, the aforementioned second heating part and the aforementioned third heating part respectively; and a first measuring part, which measures the first voltage and the first current in the aforementioned first heating part, The aforementioned first heating part, the aforementioned second heating part and the aforementioned third heating part are respectively a solenoid induction heating part, a lateral induction heating part and a resistance heating part, In the aforementioned continuous heat treatment equipment, the aforementioned control unit calculates the equivalent impedance in the parallel resonant circuit based on the aforementioned first voltage and the aforementioned first current measured by the aforementioned first measuring unit, and controls the aforementioned first output power so that when the calculated aforementioned equivalent impedance becomes larger than the threshold value, the aforementioned first output power is reduced. Effect of the invention

According to the present invention, when the equivalent impedance in the parallel resonant circuit of the first heating unit (i.e., the solenoid induction heating unit) becomes larger than the threshold value, the first output power is reduced. In other words, the first output power is reduced in advance before the temperature of the metal component heated by the first heating unit reaches the Curie temperature of the metal component. In this way, since the heating by the solenoid induction heating unit can be maintained in a state where the temperature of the metal component is lower than the Curie temperature of the metal component, and the temperature uniformity of the solenoid induction heating unit in the width direction orthogonal to the conveying direction is excellent, the temperature uniformity in the width direction can be made good as a whole.

The form used to implement the invention

Hereinafter, the implementation form of the control method of the continuous heat treatment equipment 1 of the present invention will be described with reference to the drawings.

[Implementation] A control method of a continuous heat treatment device 1 of an implementation is described with reference to FIGS. 1 to 4. FIG. 1 is a three-dimensional diagram schematically illustrating a continuous heat treatment device 1 of an implementation. FIG. 2 is a block diagram of the continuous heat treatment device 1 shown in FIG. 1. FIG. 3 is a flow chart for determining the optimal setting value in the continuous heat treatment device 1. FIG. 4 is a flow chart for operating the continuous heat treatment device 1.

[Overall structure of continuous heat treatment equipment] As shown in FIG1 , the continuous heat treatment equipment 1 has a first heating section 10, a second heating section 20 and a third heating section 30, and the heating sections 10, 20, 30 are sequentially and continuously arranged from the upstream side to the downstream side along the conveying direction F of the metal component 3. The continuous heat treatment equipment 1 performs continuous heat treatment (e.g., continuous annealing treatment) while conveying the metal component 3 in the conveying direction F through a conveying roller (not shown). The metal component 3 as a workpiece can be, for example, a thin metal sheet (e.g., a steel sheet) or a long metal strip obtained by rolling a metal sheet. The thickness of the metal component 3 is, for example, 0.1 mm to 5 mm.

A first temperature sensor 16 is provided on the downstream side of the conveying direction F of the first heating section 10 (the discharge side of the first heating section 10). The first temperature sensor 16 is a radiation thermometer that measures the discharge side temperature of the central portion in the width direction W of the metal member 3 (i.e., the first discharge side temperature) in a point-like manner. A second temperature sensor 26 is provided on the downstream side of the conveying direction F of the second heating section 20 (the discharge side of the second heating section 20). The second temperature sensor 26 measures while scanning the discharge side temperature of the metal member 3 in the width direction W orthogonal to the conveying direction F (i.e., the second discharge side temperature). The second temperature sensor 26 may be, for example, a scanning pyrometer. A third temperature sensor 36 is provided on the downstream side of the third heating section 30 in the conveying direction F (the discharge side of the third heating section 30). The third temperature sensor 36 measures the discharge side temperature of the metal member 3 (i.e., the third discharge side temperature) while scanning the width direction W perpendicular to the conveying direction F. The third temperature sensor 36 may be, for example, a scanning pyrometer.

As shown in FIG. 2 , the continuous heat treatment apparatus 1 includes a first heating unit 10 , a second heating unit 20 , a third heating unit 30 , a first temperature sensor 16 , a second temperature sensor 26 , a third temperature sensor 36 , and a control unit 5 .

The first heating unit 10 is a solenoid induction heating unit, and includes a first heating coil 12, a first power source 13, a first output power control unit 14, and a first measuring unit 18. The first heating coil 12 is a coil wound around the metal component 3. The first power source 13 outputs a first output power of high-frequency alternating current to the first heating coil 12. The first output power control unit 14 controls the first output power output to the first heating coil 12 by the first power source 13. An alternating magnetic field is generated by the first heating coil 12 in a manner that penetrates the cross section of the metal component 3 in the long side direction, and an induced current is generated on the front, back, and side of the metal component 3 by the alternating magnetic field. Furthermore, the metal member 3 is heated by Joule heat based on the induced current and the resistance of the metal member 3. The first measuring unit 18 measures the first voltage and the first current of the first output power output to the first heating coil 12. The control unit 5 controls to obtain the measured values of the measured first voltage and the first current, and the memory unit 7 stores the measured values.

The second heating unit 20 is a transverse induction heating unit, and includes a second heating coil 22, a second power source 23, and a second output power control unit 24. The second heating coil 22 is a pair of heating coils separated in the thickness direction of the metal component 3 and arranged opposite to each other so as to sandwich the metal component 3. The second power source 23 outputs the second output power of high-frequency alternating current to the second heating coil 22. The second output power control unit 24 controls the second output power output to the second heating coil 22 by the second power source 23. The alternating magnetic field generated from the second heating coil 22 penetrates in the thickness direction of the metal component 3. An induced current is generated on the surface of the metal component 3 by this alternating magnetic field, and the metal component 3 is heated by Joule heat based on the induced current and the resistance of the metal component 3.

The third heating section 30 is a resistance heating section, and has a heating heater 32, a third power source 33, and a third output power control section 34. The heating heater 32 is a resistance heating element. The third power source 33 outputs the third output power of the alternating current to the heating heater 32. The third output power control section 34 controls the third output power output to the heating heater 32 by the third power source 33. In the third heating section 30, the metal component 3 is heated by indirect resistance heating, and the indirect resistance heating is heating in which the heat energy generated by energizing the heating heater 32 is transferred to the metal component 3.

The control unit 5 controls each heating unit of the continuous heat treatment device 1, specifically, the first heating unit 10, the second heating unit 20, and the third heating unit 30. The control unit 5 is, for example, a computer, and includes: a computing unit (CPU: central processing unit) 6, and a memory unit (memory such as ROM or RAM) 7.

The memory unit 7 performs the following memory operation, for example. That is, the memory unit 7 stores various programs for executing the heat treatment in each of the first heating unit 10, the second heating unit 20, and the third heating unit 30. The memory unit 7 stores data on the heat treatment object, i.e., various metal components 3 (e.g., Curie temperature, heat content, specific resistance, width, thickness, or heat treatment conditions), or the first rated output power of the first heating unit 10, the second rated output power of the second heating unit 20, and the third rated output power of the third heating unit 30. The memory unit 7 memorizes the temperature data (the first discharge side temperature, the second discharge side temperature, and the third discharge side temperature) measured by the first temperature sensor 16, the second temperature sensor 26, and the third temperature sensor 36. The memory unit 7 memorizes the first calculation formula for calculating the first temperature unevenness in the width direction W of the first heating unit 10 from the temperature rise range in the first heating unit 10 (the first discharge side temperature-the first inlet side temperature). The memory unit 7 memorizes the second calculation formula for calculating the second temperature unevenness in the width direction W of the second heating unit 20 from the temperature rise range (second unloading side temperature - second loading side temperature) in the second heating unit 20. The memory unit 7 memorizes the third calculation formula for calculating the size T of the final temperature unevenness in the width direction of the metal component 3 unloaded from the third heating unit 30 (hereinafter referred to as the third temperature unevenness) based on the heat treatment conditions of the metal component 3, the third rated output power, the calculated accumulated temperature unevenness caused by induction heating, etc.

The calculation unit 6 performs the following calculations, for example. That is, the calculation unit 6 calculates respectively: the first output power output to the first heating unit 10, the second output power output to the second heating unit 20, and the third output power output to the third heating unit 30. The calculation unit 6 calculates the optimal setting value that makes the size T of the third temperature unevenness smaller than the allowable value based on the Curie temperature of the metal component 3 and the heat treatment conditions. Specifically, the optimal setting value is the setting value related to the first discharge side temperature, the second discharge side temperature, the first output power, the second output power, and the third output power. The calculation unit 6 calculates the equivalent impedance based on the first voltage and the first current measured by the first measuring unit 18. The calculation unit 6 calculates the threshold value based on the material of the metal member 3 and the width dimension of the metal member 3 in the width direction W perpendicular to the conveying direction F. In this way, the threshold value can be optimized according to the material and width dimension of the metal member 3.

The solenoid type induction heating part as the first heating part 10 has the following problem: although the temperature uniformity in the width direction W of the metal member 3 is excellent, when the thickness of the metal member 3 is thin, when the temperature of the metal member 3 approaches its Curie temperature, the heating efficiency is greatly reduced. That is, the penetration depth of the induced current is in the following relationship: proportional to the square root of the resistivity of the metal member 3 and inversely proportional to the square root of the relative magnetic permeability of the metal member 3. When the temperature of the metal member 3 rises and approaches the Curie temperature of the metal member 3, the relative magnetic permeability of the metal member 3 is greatly reduced, so the penetration depth of the induced current becomes deeper. As a result, when the thickness of the metal component 3 is relatively thin, the induced current flowing on the front side of the metal component 3 and the induced current flowing on the back side will cancel each other out, thereby significantly reducing the heating efficiency.

The horizontal induction heating part as the second heating part 20 does not reduce the heating efficiency even if the thickness of the metal component 3 becomes thinner, but there is the following problem: because the induction current is concentrated at the end of the width direction W of the metal component 3 and the end is overheated, the temperature uniformity in the width direction W will be worse than that of the solenoid type.

Although the resistance heating part as the third heating part 30 has excellent temperature uniformity in the width direction W of the metal component 3 and the heating efficiency does not decrease even if the thickness of the metal component 3 becomes thinner, it is difficult to perform rapid temperature increase and decrease operations.

In this way, since the solenoid induction heating unit 10, the transverse induction heating unit 20 and the resistance heating unit 30 have their own strengths and weaknesses, the method for achieving good control of the temperature uniformity in the width direction W of the metal component 3 will be described with reference to Figures 3 and 4.

[Control method of continuous heat treatment equipment] Figure 3 is a flow chart for determining the optimal setting value in the continuous heat treatment equipment 1. Figure 4 is a flow chart for operating the continuous heat treatment equipment 1.

In FIG. 3 , before the continuous heat treatment equipment 1 is operated, a step for determining the optimal setting value is started, and the aforementioned optimal setting value is the optimal setting value for heat treating a metal component 3 of a certain material in the continuous heat treatment equipment 1 (step S1). In step S2, the control unit 5 calculates how many degrees Celsius the first discharge side temperature of the first heating unit 10 should be set to based on the Curie temperature of the metal component 3 stored in the memory unit 7. In step S3, the control unit 5 calculates the first output power to be output to the first heating unit 10 based on the width or thickness of the metal component 3 stored in the memory unit 7 and the heat treatment conditions (including the heat content difference). In step S4, the control unit 5 calculates the second outlet side temperature of the second heating unit 20 (in other words, a temperature similar to the temperature of the metal component 3 carried into the third heating unit 30) based on the heat treatment conditions stored in the memory unit 7 and the third rated output power of the third heating unit 30.

In step S5, the control unit 5 calculates the second output power to be output to the second heating unit 20 according to the width or thickness of the metal member 3 and the heat treatment conditions (including the heat content difference) stored in the memory unit 7. In step S6, the control unit 5 calculates the first temperature unevenness of the first heating unit 10 and the second temperature unevenness of the second heating unit 20 from the first calculation formula and the second calculation formula stored in the memory unit 7. In addition, the control unit 5 controls to calculate the square root of the sum of the squares of the calculated first temperature unevenness and the second temperature unevenness, and stores the calculated square root of the sum of the squares in the memory unit 7 as the accumulated temperature unevenness caused by induction heating.

In step S7, the control unit 5 calculates the third output power to be output to the third heating unit 30 based on the width or thickness of the metal component 3 and the heat treatment conditions (including the heat content difference) stored in the memory unit 7, and calculates the size T of the third temperature unevenness from the third calculation formula similarly stored in the memory unit 7.

In step S8, the control unit 5 determines whether the magnitude T of the third temperature variation is smaller than the allowable value.

When the third temperature unevenness T is greater than the allowable value in step S8, the control unit 5 proceeds to step S9, and determines whether the third output power of the third heating unit 30 has reached the upper limit, that is, the third rated output power. When the third output power of the third heating unit 30 has not reached the upper limit in step S9, the control unit 5 sets the third output power of the third heating unit 30 to be higher (step S10). Furthermore, the control unit 5 returns to step S4, and calculates the temperature of the metal component 3 carried into the third heating unit 30.

When the third output power of the third heating unit 30 has reached the upper limit in step S9, the process proceeds to step S13, and the control unit 5 determines whether the first discharge side temperature of the first heating unit 10 has reached the limit temperature. When the first discharge side temperature of the first heating unit 10 has reached the limit temperature in step S13, the control unit 5 reports a setting error and terminates the setting process (step S16). In addition, the limit temperature is a temperature lower than the Curie temperature at which the relative magnetic permeability of the metal component 3 becomes 1, and is a temperature at which the heating efficiency is greatly reduced.

When the first discharge side temperature of the first heating unit 10 does not reach the limit temperature in step S13, the control unit 5 is set to increase the first discharge side temperature of the first heating unit 10, and the first output power is calculated by comparing the first discharge side temperature of the first heating unit 10 with the method of the above paragraph number [0029] (step S14). In step S15, the control unit 5 determines whether the first output power of the first heating unit 10 has reached the upper limit, that is, the first rated output power.

When the first output power of the first heating part 10 has not reached the upper limit in step S15, the process returns to step S3, and the control part 5 calculates the output power of the first heating part 10. When the first output power of the first heating part 10 has reached the upper limit in step S15, the process proceeds to step S16, and the control part 5 notifies a setting error and ends the setting process.

When the third temperature unevenness T is smaller than the allowable value in step S8, the control unit 5 stores the calculated first discharge side temperature and second discharge side temperature, and the first output power, the second output power, and the third output power in the memory unit 7 (step S11). That is, the control unit 5 calculates the first discharge side temperature, the second discharge side temperature, the first output power, the second output power, and the third output power in advance according to the Curie temperature of the metal component 3 and the heat treatment conditions, so that the third temperature unevenness T becomes smaller than the allowable value, and stores the respective optimal setting values in the memory unit 7. Thus, by using the optimal setting value calculated in advance as the initial value when operating the continuous heat treatment equipment 1, the size T of the third temperature unevenness can be made smaller than the allowable value.

Furthermore, in step S12, the process of determining the optimal setting value in the continuous heat treatment apparatus 1 is terminated.

FIG. 4 is a flow chart showing a case where the first heating coil 12 and a capacitor (not shown) form a parallel resonant circuit.

In FIG. 4 , the step for operating the continuous heat treatment equipment 1 is started (step S21). In step S22, the control unit 5 sets the optimal setting values stored in the memory unit 7 (i.e., the first discharge side temperature and the first output power of the first heating unit 10, the second discharge side temperature and the second output power of the second heating unit 20, and the third output power of the third heating unit 30), and the target discharge side temperature of the third heating unit 30. In step S23, the control unit 5 obtains the measured values of the first voltage and the first current output to the first heating coil 12 through the first measuring unit 18. In step S24, the control unit 5 calculates the equivalent impedance based on the measured values of the first voltage and the first current measured in step S23.

In step S25, the control unit 5 determines whether the calculated equivalent impedance is greater than the threshold value. When the equivalent impedance calculated in step S24 is greater than the threshold value, the control unit 5 is set to lower the first discharge side temperature of the first heating unit 10 (step S26). In step S27, the control unit 5 calculates the first output power of the first heating unit 10 and the second output power of the second heating unit 20 according to the first discharge side temperature of the first heating unit 10 set in step S26. Therefore, in steps S26 and 27, when the calculated equivalent impedance is greater than the threshold value, the control unit 5 controls the first output power to reduce the first output power of the first heating unit 10. Then, the process returns to step S23, and the control unit 5 obtains the measurement values of the first voltage and the first current output to the first heating coil 12 through the first measuring unit 18.

When the equivalent impedance calculated in step S25 is below the threshold value, the control unit 5 measures the size T of the final temperature unevenness (i.e., the third temperature unevenness) in the width direction of the metal component 3 removed from the third heating unit 30 through the third temperature sensor 36 (step S28). In step S29, the control unit 5 determines whether the size T of the third temperature unevenness is smaller than the allowable value.

When the magnitude T of the third temperature unevenness is smaller than the allowable value in step S29, the process returns to step S23, and the control unit 5 obtains the measured values of the first voltage and the first current output to the first heating coil 12 through the first measuring unit 18.

When the third temperature unevenness T is greater than the allowable value in step S29, the process proceeds to step S30, and the control unit 5 determines whether the third output power of the third heating unit 30 has reached the upper limit, i.e., the third rated output power. When the third output power of the third heating unit 30 has not reached the upper limit in step S30, the control unit 5 sets the third output power of the third heating unit 30 to be higher (step S31). Thus, since the proportion of the third heating unit 30 (i.e., the resistance heating unit) with excellent temperature uniformity increases, the temperature uniformity in the width direction W is improved.

In step S32, the control unit 5 calculates the temperature of the metal component 3 carried into the third heating unit 30. In step S34, the control unit 5 calculates the first output power of the first heating unit 10 and the second output power of the second heating unit 20 according to the second carry-out side temperature calculated in step S32 (i.e., similar to the temperature of the metal component 3 carried into the third heating unit 30). Then, the control unit 5 returns to step S23, and the control unit 5 obtains the measured values of the first voltage and the first current output to the first heating coil 12 through the first measuring unit 18.

When the third output power of the third heating unit 30 has reached the upper limit in step S30, the process proceeds to step S35, and the control unit 5 determines whether the first discharge side temperature of the first heating unit 10 has reached the limit temperature. When the first discharge side temperature of the first heating unit 10 has reached the limit temperature in step S35, the control unit 5 notifies to slow down the conveying speed (step S37). Then, the process returns to step S34, and the control unit 5 calculates the first output power of the first heating unit 10 and the second output power of the second heating unit 20, respectively.

When the temperature of the first outlet side of the first heating unit 10 does not reach the critical temperature in step S35, the control unit 5 is set to increase the temperature of the first outlet side of the first heating unit 10 (step S36). In this way, since the proportion of the first heating unit 10 (i.e., the solenoid induction heating unit) with excellent temperature uniformity in the width direction W increases, the temperature uniformity in the width direction W can be improved. Then, returning to step S34, the control unit 5 calculates the first output power of the first heating unit 10 and the second output power of the second heating unit 20 respectively.

Except for some abnormal situation such as calculation error, the continuous heat treatment equipment 1 will be operated continuously according to the flow chart of FIG. 4 .

[Variation] The control method of the continuous heat treatment equipment 1 of the variation will be described with reference to FIG. 5. FIG. 5 is a flow chart showing the variation when the continuous heat treatment equipment 1 is operated.

FIG. 5 is a flow chart showing a case where the first heating coil 12 and a capacitor (not shown) form a series resonant circuit.

In FIG. 5 , the step for operating the continuous heat treatment equipment 1 is started (step S41). In step S42, the control unit 5 sets the optimal setting values stored in the memory unit 7 (i.e., the first discharge side temperature and the first output power of the first heating unit 10, the second discharge side temperature and the second output power of the second heating unit 20, and the third output power of the third heating unit 30), and the target discharge side temperature of the third heating unit 30. In step S43, the control unit 5 obtains the measured values of the first voltage and the first current output to the first heating coil 12 through the first measuring unit 18. In step S44, the control unit 5 calculates the equivalent impedance based on the measured values of the first voltage and the first current measured in step S43.

In step S45, the control unit 5 determines whether the calculated equivalent impedance is smaller than the threshold value. When the equivalent impedance calculated in step S44 is smaller than the threshold value, the control unit 5 is set to lower the first discharge side temperature of the first heating unit 10 (step S46). In step S47, the control unit 5 calculates the first output power of the first heating unit 10 and the second output power of the second heating unit 20 according to the first discharge side temperature of the first heating unit 10 set in step S46. Therefore, in steps S46 and 47, when the calculated equivalent impedance is larger than the threshold value, the control unit 5 controls the first output power to reduce the first output power of the first heating unit 10. Then, returning to step S43, the control unit 5 obtains the measurement values of the first voltage and the first current output to the first heating coil 12 through the first measuring unit 18.

When the equivalent impedance calculated in step S45 is above the threshold value, the control unit 5 measures the size T of the final temperature unevenness (i.e., the third temperature unevenness) in the width direction of the metal component 3 removed from the third heating unit 30 through the third temperature sensor 36 (step S48). In step S49, the control unit 5 determines whether the size T of the third temperature unevenness is smaller than the allowable value.

When the magnitude T of the third temperature unevenness is smaller than the allowable value in step S49, the process returns to step S43, and the control unit 5 obtains the measured values of the first voltage and the first current output to the first heating coil 12 through the first measuring unit 18.

When the third temperature unevenness T is greater than the allowable value in step S49, the process proceeds to step S50, and the control unit 5 determines whether the third output power of the third heating unit 30 has reached the upper limit, i.e., the third rated output power. When the third output power of the third heating unit 30 has not reached the upper limit in step S50, the control unit 5 sets the third output power of the third heating unit 30 to be higher (step S51). Thus, since the proportion of the third heating unit 30 (i.e., the resistance heating unit) with excellent temperature uniformity increases, the temperature uniformity in the width direction W is improved.

In step S52, the control unit 5 calculates the temperature of the metal component 3 carried into the third heating unit 30. In step S54, the control unit 5 calculates the first output power of the first heating unit 10 and the second output power of the second heating unit 20 according to the second carry-out side temperature calculated in step S52 (i.e., similar to the temperature of the metal component 3 carried into the third heating unit 30). Then, the control unit 5 returns to step S43, and the control unit 5 obtains the measured values of the first voltage and the first current output to the first heating coil 12 through the first measuring unit 18.

When the third output power of the third heating unit 30 has reached the upper limit in step S50, the process proceeds to step S55, and the control unit 5 determines whether the first discharge side temperature of the first heating unit 10 has reached the limit temperature. When the first discharge side temperature of the first heating unit 10 has reached the limit temperature in step S55, the control unit 5 notifies to slow down the conveying speed (step S57). Then, the process returns to step S54, and the control unit 5 calculates the first output power of the first heating unit 10 and the second output power of the second heating unit 20, respectively.

When the temperature of the first outlet side of the first heating unit 10 does not reach the critical temperature in step S55, the control unit 5 is set to increase the temperature of the first outlet side of the first heating unit 10 (step S56). In this way, since the proportion of the first heating unit 10 (i.e., the solenoid induction heating unit) with excellent temperature uniformity in the width direction W increases, the temperature uniformity in the width direction W can be improved. Then, returning to step S54, the control unit 5 calculates the first output power of the first heating unit 10 and the second output power of the second heating unit 20 respectively.

Except for some abnormal situation such as calculation error, the continuous heat treatment equipment 1 will be operated continuously according to the flow chart of Figure 5.

Although the present invention has been described with reference to specific implementation forms or values, the present invention is not limited to the above-mentioned implementation forms and can be implemented with various modifications within the scope of the present invention.

The first heating unit 10 does not necessarily have to be composed of a single heating zone, and may be divided into a plurality of heating zones and arranged in series in the conveying direction F. The second heating unit 20 and the third heating unit 30 may also be each arranged in series in the conveying direction F, similarly to the first heating unit 10 .

The present invention and its implementation are summarized as follows.

The control method of a continuous heat treatment device 1 of one embodiment of the present invention is characterized in that the continuous heat treatment device 1 comprises: A first heating section 10, a second heating section 20 and a third heating section 30, which are sequentially and continuously arranged along the conveying direction F of the metal component 3; A control section 5, which controls the first output power, the second output power and the third output power output to the first heating section 10, the second heating section 20 and the third heating section 30 respectively; and A first measuring section 18, which measures the first voltage and the first current in the first heating section 10, The first heating section 10, the second heating section 20 and the third heating section 30 are respectively a solenoid induction heating section, a lateral induction heating section and a resistance heating section, In the continuous heat treatment equipment 1, the control unit 5 calculates the equivalent impedance in the parallel resonant circuit according to the first voltage and the first current measured by the first measuring unit 18, and controls the first output power so that when the calculated equivalent impedance becomes larger than the threshold value, the first output power is reduced.

According to the control method, when the equivalent impedance in the parallel resonant circuit of the first heating unit 10 (i.e., the solenoid induction heating unit) becomes larger than the threshold value, the first output power is reduced. In other words, the first output power is reduced in advance before the temperature of the metal component 3 heated by the first heating unit 10 reaches the Curie temperature of the metal component 3. In this way, since the heating by the solenoid induction heating unit can be maintained in a state where the temperature of the metal component 3 is lower than the Curie temperature of the metal component 3, and the temperature uniformity of the solenoid induction heating unit in the width direction W orthogonal to the conveying direction F is excellent, the temperature uniformity in the width direction W can be made good as a whole. Furthermore, since the heating efficiency is greatly reduced when the temperature of the metal component 3 reaches near the Curie temperature, the threshold value of the equivalent impedance can be selected to be a value before reaching the Curie temperature.

Another aspect of the present invention is characterized in that the continuous heat treatment device 1 comprises: A first heating section 10, a second heating section 20 and a third heating section 30 are sequentially and continuously arranged along the conveying direction F of the metal component 3; A control section 5, which controls the first output power, the second output power and the third output power output to the first heating section 10, the second heating section 20 and the third heating section 30 respectively; and A first measuring section 18, which measures the first voltage and the first current in the first heating section 10, The first heating section 10, the second heating section 20 and the third heating section 30 are respectively a solenoid induction heating section, a lateral induction heating section and a resistance heating section, In the continuous heat treatment equipment 1, the control unit 5 calculates the equivalent impedance in the series resonant circuit according to the first voltage and the first current measured by the first measuring unit 18, and controls the first output power so that when the calculated equivalent impedance becomes smaller than the threshold value, the first output power is reduced.

According to the control method, when the equivalent impedance in the series resonant circuit of the first heating unit 10 (i.e., the solenoid induction heating unit) becomes smaller than the threshold value, the first output power is reduced. In other words, the first output power is reduced in advance before the temperature of the metal component 3 heated by the first heating unit 10 reaches the Curie temperature of the metal component 3. In this way, since the heating by the solenoid induction heating unit can be maintained in a state where the temperature of the metal component 3 is lower than the Curie temperature of the metal component 3, and the temperature uniformity of the solenoid induction heating unit in the width direction W orthogonal to the conveying direction F is excellent, the temperature uniformity in the width direction W can be made good as a whole.

In addition, in a control method of a continuous heat treatment device 1 in an embodiment, the threshold value is calculated based on the material of the metal component 3 and the width dimension of the metal component 3 in the width direction W orthogonal to the conveying direction F.

According to the above-mentioned implementation form, the threshold value can be optimized according to the material and width size of the metal component 3.

Furthermore, in a control method of a continuous heat treatment device 1 in an embodiment, the continuous heat treatment device 1 is provided with a third temperature sensor 36, and the third temperature sensor 36 measures the third temperature unevenness in the width direction W orthogonal to the conveying direction F of the metal component 3 before being carried out from the third heating section 30. The control section 5 determines whether the size T of the third temperature unevenness is greater than the allowable value, and controls the third output power to increase the third output power when the size T of the third temperature unevenness is greater than the allowable value.

According to the above-mentioned implementation form, since the proportion of the third heating part 30 (i.e., the resistance heating part) with excellent temperature uniformity will become larger, the temperature uniformity in the width direction W will be improved.

Furthermore, in a control method of a continuous heat treatment device 1 in one embodiment, the control unit 5 determines whether the third output power becomes the third rated output power of the third heating unit 30, and controls the first output power so that when the third output power becomes the third rated output power, the temperature of the outlet side of the first heating unit 10 becomes higher.

According to the above-mentioned implementation form, since the proportion of the first heating part 10 (i.e., the solenoid induction heating part) with excellent temperature uniformity in the width direction W becomes larger, the temperature uniformity in the width direction W can be improved.

The control method of the continuous heat treatment equipment 1 of another aspect of the present invention is characterized in that: the continuous heat treatment equipment 1 comprises: A first heating section 10, a second heating section 20 and a third heating section 30, which are arranged in sequence and continuously along the conveying direction F of the metal component 3; A control section 5, which controls the first output power, the second output power and the third output power output to the first heating section 10, the second heating section 20 and the third heating section 30 respectively; and A third temperature sensor 36, which measures the third temperature unevenness in the width direction W orthogonal to the conveying direction F of the metal component 3 before it is conveyed from the third heating section 30, The first heating unit 10, the second heating unit 20 and the third heating unit 30 are respectively a solenoid induction heating unit, a transverse induction heating unit and a resistance heating unit. In the continuous heat treatment equipment 1, the control unit 5 calculates in advance the optimal setting values related to the first discharge side temperature of the first heating unit 10, the second discharge side temperature of the second heating unit 20, the first output power, the second output power and the third output power according to the Curie temperature of the metal component 3 and the heat treatment conditions, so that the size T of the third temperature unevenness becomes smaller than the allowable value.

According to the above control method, the third temperature unevenness T of the metal component 3 removed from the third heating section 30 can be made smaller than the allowable value by using the optimal setting value calculated in advance as the initial value when the continuous heat treatment equipment 1 is operated.

1: Continuous heat treatment equipment 3: Metal component 5: Control unit 6: Calculation unit 7: Memory unit 10: 1st heating unit (solenoid induction heating unit) 12: 1st heating coil 13: 1st power supply 14: 1st output power control unit 16: 1st temperature sensor 18: 1st measurement unit 20: 2nd heating unit (lateral induction heating unit) 22: 2nd heating coil 23: 2nd power supply 24: 2nd output power control unit 26: 2nd temperature sensor 30: 3rd heating unit (resistance heating unit) 32: Heating heater 33: 3rd power supply 34: 3rd output power control unit 36: 3rd temperature sensor F: Conveying direction T: The size of the third temperature unevenness (the final temperature unevenness in the width direction of the metal component removed from the third heating section) W: Width direction S1~S16, S21~S32, S34~S37, S41~S52, S54~S57: Steps

FIG. 1 is a perspective view schematically illustrating a continuous heat treatment apparatus of an embodiment. FIG. 2 is a block diagram of the continuous heat treatment apparatus shown in FIG. 1 . FIG. 3 is a flow chart for determining the optimal setting value in the continuous heat treatment apparatus. FIG. 4 is a flow chart for operating the continuous heat treatment apparatus. FIG. 5 is a flow chart for a variation of operating the continuous heat treatment apparatus.

S21~S32,S34~S37: Steps

Claims (6)

A control method for a continuous heat treatment device, wherein the continuous heat treatment device comprises: A first heating unit, a second heating unit and a third heating unit, which are sequentially and continuously arranged along the conveying direction of the metal component; A control unit, which controls the first output power, the second output power and the third output power output to the first heating unit, the second heating unit and the third heating unit, respectively; and A first measuring unit, which measures the first voltage and the first current in the first heating unit, The first heating unit, the second heating unit and the third heating unit are respectively a solenoid induction heating unit, a lateral induction heating unit and a resistance heating unit, In the aforementioned continuous heat treatment equipment, the aforementioned control unit calculates the equivalent impedance in the parallel resonant circuit according to the aforementioned first voltage and the aforementioned first current measured by the aforementioned first measuring unit, and controls the aforementioned first output power so that when the calculated aforementioned equivalent impedance becomes larger than the threshold value, the aforementioned first output power is reduced. A control method for a continuous heat treatment device, wherein the continuous heat treatment device comprises: A first heating unit, a second heating unit and a third heating unit, which are sequentially and continuously arranged along the conveying direction of the metal component; A control unit, which controls the first output power, the second output power and the third output power output to the first heating unit, the second heating unit and the third heating unit, respectively; and A first measuring unit, which measures the first voltage and the first current in the first heating unit, The first heating unit, the second heating unit and the third heating unit are respectively a solenoid induction heating unit, a lateral induction heating unit and a resistance heating unit, In the aforementioned continuous heat treatment equipment, the aforementioned control unit calculates the equivalent impedance in the series resonant circuit according to the aforementioned first voltage and the aforementioned first current measured by the aforementioned first measuring unit, and controls the aforementioned first output power so that when the calculated aforementioned equivalent impedance becomes smaller than the threshold value, the aforementioned first output power is reduced. A control method for a continuous heat treatment apparatus as claimed in claim 1 or 2, wherein the threshold value is calculated based on the material of the metal component and the width dimension of the metal component in a width direction perpendicular to the conveying direction. A control method for a continuous heat treatment device as claimed in claim 1, wherein the continuous heat treatment device is provided with a third temperature sensor, the third temperature sensor measures the third temperature unevenness of the metal component in the width direction orthogonal to the conveying direction before it is removed from the third heating section, the control section determines whether the size of the third temperature unevenness is above the allowable value, and controls the third output power to increase the third output power when the size of the third temperature unevenness is above the allowable value. A control method for a continuous heat treatment device as claimed in claim 4, wherein the control unit determines whether the third output power becomes the third rated output power of the third heating unit, and controls the first output power so that when the third output power becomes the third rated output power, the temperature of the outlet side of the first heating unit becomes higher. A control method for a continuous heat treatment device, the continuous heat treatment device comprising: A first heating unit, a second heating unit and a third heating unit, which are sequentially and continuously arranged along the conveying direction of the metal component; A control unit, which controls the first output power, the second output power and the third output power output to the first heating unit, the second heating unit and the third heating unit respectively; and A third temperature sensor, which measures the third temperature unevenness of the metal component in the width direction orthogonal to the conveying direction before the metal component is conveyed from the third heating unit, The first heating unit, the second heating unit and the third heating unit are respectively a solenoid induction heating unit, a lateral induction heating unit and a resistance heating unit, In the above-mentioned continuous heat treatment equipment, the above-mentioned control unit calculates in advance the optimal setting values related to the first discharge side temperature of the above-mentioned first heating unit, the second discharge side temperature of the above-mentioned second heating unit, the above-mentioned first output power, the above-mentioned second output power, and the above-mentioned third output power according to the Curie temperature of the above-mentioned metal component and the heat treatment conditions, so as to make the size of the above-mentioned third temperature unevenness smaller than the allowable value.

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