JP5359945B2 - Temperature control method and temperature control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature control method and a temperature control apparatus that in a process of successively performing a heating treatment after a surface treatment of a steel plate, are able to perform the heating treatment by means of a suitable heating power irrespective of a change in reflectivity of a steel-plate surface caused by a seam of the steel plate. <P>SOLUTION: When measuring a temperature of a steel plate 1, which undergoes a heating treatment, by means of a radiation thermometer 5, and performing feedback control of a heating power during the heating treatment by means of a temperature controller 10 based on the temperature of the steel plate 1, in predetermined sections before and after a seam of the steel plate 1, a power average circuit 11 fixes the heating power to an average heating power during the predetermined period immediately before the seam of the steel plate 1. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a temperature control method and a temperature control apparatus in a process of continuously performing a heat treatment after a surface treatment of a steel sheet.

  As conventional temperature feedback (hereinafter referred to as “FB”) control technology, for example, those described in Patent Documents 1 and 2 are known. Patent Document 1 describes that the heater is continuously turned on until the output reaches an arbitrary constant value, the output is raised, and the PID operation is started when the output reaches an arbitrary constant value. Patent Document 2 describes that the setting is switched from the temperature rise setting voltage to the heat retention setting voltage when the temperature approaches the target temperature, and PID control is performed after a predetermined time has elapsed.

  As described above, in the conventional temperature FB control, the deviation between the measured temperature record and the target temperature is obtained, and various heating sources are adjusted by PID control or the like so that the deviation converges. It is a major premise that the temperature is measured with accuracy. However, when measuring temperatures without contact due to problems such as surface scratches, radiation thermometers are often used, and depending on the surface properties of the object to be measured, a high-precision temperature is required unless the emissivity is set appropriately. If the measurement is not possible, it is mirror-like and the emissivity is low, it is often not practical.

JP 60-163102 A JP-A-11-54251

  When surface treatment is performed by continuously bringing a roll coater or the like into contact with a steel plate, the surface treatment equipment such as a roll coater is retracted away from the steel plate to protect the equipment before and after the joint of the steel plate. The portion before and after the joint becomes an unprocessed portion. The part remains a mirror-like body of the original plate and has a low emissivity. Therefore, in the radiation thermometer set in accordance with the emissivity of the processing unit, the measured value is lower than the actual temperature.

  For this reason, if the temperature FB control is continued in this state, the temperature becomes higher than the target temperature as a result, and there is a problem if there is a temperature upper limit constraint in relation to the film forming conditions and the heat resistance temperature of peripheral equipment. In the techniques described in Patent Documents 1 and 2 described above, similar to general temperature FB control, only control based on measured temperature results is performed. There is no effect.

  Therefore, in the present invention, in the process of continuously performing the heat treatment after the surface treatment of the steel plate, the heat treatment is performed at an appropriate heating temperature regardless of the change in the reflectance of the steel plate surface caused by the joint of the steel plates. It is an object of the present invention to provide a temperature control method and a temperature control device that can perform the above-described operation.

  The temperature control method of the present invention is a temperature control method of a process in which the joined steel plates are continuously passed and the heat treatment after the surface treatment is performed, and the temperature of the heat treated steel plate is measured with a radiation thermometer. When the feedback control of the heating power in the heat treatment is performed based on the temperature of the steel sheet, the heating power is fixed at an average heating power in a predetermined period immediately before the joint of the steel sheets in a predetermined section before and after the joint of the steel sheets. And

  According to the present invention, in the predetermined section before and after the joint of the steel plates, the heating power is fixed at the average heating power of the predetermined period immediately before the joint of the steel plates, so the change in the reflectance of the steel sheet surface before and after the joint of the steel plates The influence can be eliminated, and heat treatment with an appropriate heating power can be performed.

  Here, when the heat treatment conditions change before and after the joints of the steel plates, the heating power is model-calculated based on the conditions of the heat treatments, and heating is performed with the heating power model-calculated in a predetermined section before and after the joints of the steel plates. It is desirable to process.

  Thus, even when the heat treatment conditions change before and after the joint of the steel plates, the heat treatment is performed with the heating power that is model-calculated based on the heat treatment conditions. It can respond to changes in heating power.

  The temperature control device of the present invention is a temperature control device of a heating device that continuously heats the joined steel plates and performs the heat treatment after the surface treatment, and measures the temperature of the steel plates heat-treated by the heating device. A radiation thermometer, a temperature control controller for feedback control of the heating power in the heating device based on the temperature of the steel plate measured by the radiation thermometer, and the heating power by the heating device in a predetermined section before and after the joint of the steel plates And a power average circuit that fixes the average heating power for a predetermined period immediately before the joint.

  According to the present invention, in the predetermined section before and after the joint of the steel plates, the heating power in the heating device is fixed with the average heating power of the predetermined period immediately before the joint of the steel plates, so the reflectance of the steel sheet surface before and after the joint of the steel plates The influence of this change can be eliminated, and a heat treatment with an appropriate heating power can be performed.

  In addition, the temperature control device of the present invention calculates the heating power based on the heat treatment conditions when the heat treatment conditions change before and after the joints of the steel plates, and the model in a predetermined section before and after the joints of the steel plates. It is desirable to further include a required power calculation model for controlling the heating device with the calculated heating power.

  Thus, even if the heat treatment conditions change before and after the joint of the steel plates, the heat treatment conditions change by performing the heat treatment with the heating device with the heating power that is model-calculated based on the heat treatment conditions. Can cope with a large change in heating power.

(1) When the temperature of the heat-treated steel sheet is measured with a radiation thermometer and the heating power in the heat treatment is feedback-controlled based on the temperature of the steel sheet, the heating power is measured in a predetermined section before and after the joint of the steel sheets. By fixing with the average heating power of the predetermined period immediately before the joint, in the process of performing the heat treatment after the surface treatment of the steel sheet continuously, regardless of the change in the reflectance of the steel sheet surface due to the joint of the steel sheet, Since it is possible to perform a heat treatment with an appropriate heating power, the product mismatch range can be minimized.

(2) When the heat treatment conditions change before and after the joint of the steel plates, the heating power is model-calculated based on the conditions of the heat treatment, and heating is performed with the heating power model-calculated in a predetermined section before and after the joint of the steel plates. By processing, it can cope with a large change in heating power due to changes in heat treatment conditions before and after the joint of steel plates, and minimizes the product mismatch range even when processing various products continuously Can be

It is a schematic block diagram of the steel plate surface treatment line in embodiment of this invention. It is a perspective view which shows the joint part of the joined steel plate. It is explanatory drawing which shows an example of the switching timing of control by the temperature control apparatus in this embodiment.

FIG. 1 is a schematic configuration diagram of a steel sheet surface treatment line in an embodiment of the present invention.
As shown in FIG. 1, a steel sheet surface treatment line according to an embodiment of the present invention includes a transport roller 2 that transports a steel sheet 1, and a roll coater 3 that contacts the steel sheet 1 and applies a coating liquid to perform surface treatment. A heater 4 as a heating device that heat-treats the steel sheet 1 coated with the coating liquid, a radiation thermometer 5 that measures the temperature of the steel sheet 1 heat-treated by the heater 4 in a non-contact manner, And a temperature control device 6 for controlling the heating power.

  Since the steel plate 1 is continuously processed in the steel plate surface treatment line, it is joined by welding or the like. FIG. 2 shows a joint portion of the steel plate 1. The roll coater 3 is for continuously applying the coating liquid to the steel sheet 1 as a contact state, and for protecting the equipment around the joint (hereinafter referred to as “welding point”) 1a of the steel sheet 1. And retracted away from the steel plate 1 and brought into a non-contact state. The heater 4 is for heating the steel sheet 1 to which the coating liquid has been applied by resistance heating, infrared heating, near infrared heating, or the like, and performing drying or film formation after the surface treatment.

  The temperature control device 6 includes a temperature control controller 10 that performs feedback control on the heating power in the heater 4 based on the temperature of the steel plate 1 measured by the radiation thermometer 5, and the heater 4 in a predetermined section around the welding point 1 a of the steel plate 1. The heating power is calculated based on the power average circuit 11 for fixing the heating power with the average heating power for a predetermined period immediately before the welding point 1a of the steel plate 1 and the conditions for the heat treatment, and in a predetermined section before and after the welding point 1a of the steel plate 1. And a required power calculation model 12 for controlling the heater 4 with the calculated heating power.

  The temperature controller 10 performs feedback control of the heating power by the heater 4 based on the temperature of the steel plate 1 measured by the radiation thermometer 5 and the temperature target value. As described above, in the steel plate surface treatment line in the present embodiment, the temperature control controller is used in the portion (hereinafter referred to as “surface treatment portion”) 1b where the coating liquid is applied onto the steel plate 1 by the roll coater 3. The heater 4 is controlled by 10.

  The power average circuit 11 controls the heater 4 in a portion (hereinafter referred to as “untreated portion”) 1 c where the coating liquid around the welding point 1 a of the steel plate 1 is not applied. The power average circuit 11 calculates an average heating power for a predetermined period (during Tsec) immediately before the welding point 1a of the steel plate 1. The power average circuit 11 controls the heater 4 when the heat treatment conditions do not change around the welding point 1a of the steel plate 1.

  The required power calculation model 12 controls the heater 4 in place of the power average circuit 11 when the heat treatment conditions change in the untreated portion 1c around the welding point 1a of the steel plate 1. The required power calculation model 12 is a heat treatment condition such as a steel plate size (plate width, plate thickness), a plate passing speed (line speed), a specific heat, a heating efficiency, a temperature target value, and a required temperature rise obtained from an inlet side temperature. From this, the required power (output value) of the heater 4 as the heating power is model-calculated and output to the heater 4.

  In the temperature control device 6 configured as described above, the surface treatment unit 1b other than the predetermined section before and after the welding point 1a of the steel plate 1 can measure an accurate temperature with the radiation thermometer 5, and therefore the temperature controller 10 performs normal temperature feedback control. The heater 4 is controlled. And in the untreated part 1c of the predetermined area before and behind the welding point 1a of the steel plate 1, the power average circuit 11 fixes the heating power of the heater 4 with the average heating power of the predetermined period just before the welding point 1a of the steel plate 1.

  FIG. 3 shows an example of control switching timing by the temperature control device 6 in the present embodiment. The welding point 1a of the steel plate 1 is tracked by line master control, and the following switching timing is calculated from the position of the welding point 1a, the position of each device such as the roll coater 3 and the heater 4, and the line speed.

  3A is 30 seconds before the welding point 1a reaches the roll coater 3, and is a stable region of the heater 4. FIG. The power average circuit 11 obtains the average value of the heating power of the heater 4 for 30 seconds from when the welding point 1a reaches the roll coater 3 until it reaches the roll coater 3. B is the timing at which the roll coater 3 is released (coating is stopped) 1.5 seconds before the welding point 1a reaches the roll coater 3 (determined from the required operation time of the roll coater 3 and the tracking error).

  Further, C is a timing at which the roll coater 3 is pressure-bonded (resume coating) 0.5 seconds after the welding point 1a passes through the roll coater 3 (determined from the time required for operation of the roll coater 3 and a tracking error). D is the timing at which the welding point 1a reaches the heater 4, and the control by the temperature control means 6 is changed from the normal temperature FB control by the temperature controller 10 to the control by the power average circuit 11 or the required power calculation model 12. It is timing. In addition, D should just be before the untreated part 1c of the steel plate 1 reaches the radiation thermometer 5. Further, when the length of the heater 4 on the line is shorter than the length of the unprocessed portion 1c before the welding point 1a (the right side of the welding point 1a in FIG. 2), the heater 4 is further changed to the near side. E returns to the normal temperature FB control by the temperature controller 10 two seconds after the welding point 1a passes the radiation thermometer 5 on the exit side of the heater 4 (determined from the time required for operation of the roll coater 3 and tracking error). It is timing.

  That is, in the temperature control device 6 in the present embodiment, the temperature feedback control is temporarily turned off at a portion where the temperature is measured normally several m before the welding point 1a, and the output average value to the heater 4 within a certain time immediately before turning off. Hold with. Thereafter, the process by the temperature feedback control is resumed several m after passing through the welding point 1a, and the temperature feedback control is resumed when the temperature can be measured again.

  Thus, in the temperature control device 6 in the present embodiment, the temperature of the heat-treated steel plate 1 is measured by the radiation thermometer 5 and the heating power in the heat treatment is feedback controlled based on the temperature of the steel plate 1. In the predetermined section before and after 1 welding point 1a, the heating power is fixed at the average heating power for a predetermined period immediately before welding point 1a of steel plate 1, and therefore the change in reflectance of the surface of steel plate 1 before and after welding point 1a of steel plate 1 is changed. The influence can be eliminated, and heat treatment with an appropriate heating power can be performed.

  Therefore, in the temperature control device 6 in the present embodiment, in the process of continuously performing the heat treatment after the surface treatment of the steel plate 1, regardless of the change in the reflectance of the surface of the steel plate 1 due to the joint of the steel plates 1, it is appropriate. Since it is possible to perform a heat treatment with an appropriate heating power, the product mismatch range can be minimized.

  Further, in this temperature control device 6, when the heat treatment conditions change around the welding point 1 a of the steel plate 1, the heating power is model-calculated based on the heat treatment conditions by the required power calculation model 12, and the steel plate 1 Since the heat treatment is performed with the heating power calculated in the model in the predetermined section before and after the welding point 1a, it is possible to cope with a large change in the heating power accompanying the change in the heat treatment condition before and after the welding point 1a of the steel plate 1. Even when various products are processed continuously, the product mismatch range can be minimized.

  The temperature control method and the temperature control apparatus of the present invention provide an appropriate heating power regardless of a change in the reflectance of the steel sheet surface caused by the joint of the steel sheets in the process of continuously performing the heat treatment after the surface treatment of the steel sheets. It is useful as a method and apparatus for performing a heat treatment by the above.

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Conveyance roller 3 Roll coater 4 Heater 5 Radiation thermometer 6 Temperature control apparatus 10 Temperature control controller 11 Power average circuit 12 Required power calculation model

Claims (4)

It is a temperature control method of a process of performing continuous heat treatment after surface treatment by continuously passing the joined steel plates,
The temperature of the heat-treated steel sheet is measured with a radiation thermometer, and when the heating power in the heat treatment is feedback controlled based on the temperature of the steel sheet , it remains a mirror-like body before and after the joint of the steel sheets , A temperature control method, wherein the heating power is fixed at an average heating power for a predetermined period immediately before a joint of the steel plates in a predetermined section where the emissivity is low . When the conditions of the heat treatment change before and after the joint of the steel plates, calculate the heating power based on the conditions of the heat treatment , remain the mirror-like body before and after the joint of the steel plates , emissivity The temperature control method according to claim 1, wherein the heat treatment is performed with the heating power calculated by the model in a predetermined section where the temperature is low . It is a temperature control device of a heating device for continuously performing the heat treatment after the surface treatment by continuously passing the joined steel plates,
A radiation thermometer for measuring the temperature of the steel sheet heat-treated by the heating device;
A temperature control controller that feedback-controls the heating power in the heating device based on the temperature of the steel sheet measured by the radiation thermometer;
A power average circuit that remains a mirror-like body before and after the joint of the steel plates and fixes the heating power by the heating device in a predetermined section with a low emissivity with an average heating power for a predetermined period immediately before the joint of the steel plates. Including temperature control device. When the conditions of the heat treatment change before and after the joint of the steel plates, the heating power is model-calculated based on the conditions of the heat treatment , remains a mirror-like body before and after the joint of the steel plates , and the emissivity temperature control device further comprises claim 3 wherein the required power calculation model for controlling the heating device in the model calculated heating power in a low predetermined interval.

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