JP4377845B2 - Coil burnout prevention method for jacket roll - Google Patents

Description

  The present invention relates to a method for preventing coil burnout of a jacket roll used for heating a steel plate in a production line for damping steel plate, galvanized steel plate and the like.

  In production lines such as vibration-damping steel sheets and galvanized steel sheets, jacket rolls (Patent Document 1) are used to convey steel sheets while heating them to a predetermined temperature. This jacket roll includes a fixed-side coil holder having a plurality of coils with iron cores, and a roll shell rotatably supported on the outer periphery thereof, and a heat medium is placed in a vacuum state in a jacket chamber formed in the roll shell. It is sealed and has a heat pipe effect. In a long jacket roll for conveying steel plates, the coil is divided into a plurality of pieces in the longitudinal direction of the roll.

  When an AC power source is energized to the coil, a magnetic flux is generated. Due to the action of the magnetic flux, an induced current is generated in the roll shell and the roll shell generates heat. The roll shell makes the temperature distribution in the longitudinal direction uniform by the heat pipe effect of the jacket chamber, and the entire roll is heated to a uniform temperature. Although the roll shell is cooled by the contact with the steel plate, a roll temperature sensor is installed on the inner peripheral surface of the roll shell, and the roll shell is maintained at the target temperature by automatically controlling the amount of current supplied to the coil.

However, although such temperature control is performed and the roll temperature is maintained at about 220 ° C., for example, an accident that the coil burns out occurs. There is a possibility that the temperature of the coil has risen beyond the heat resistance temperature (about 480 ° C.) of the coil wire made of aluminum due to burnout. Such an accident was not predicted by the manufacturer. Coil burnout of the jacket roll caused the steel sheet production line to stop, so an immediate countermeasure was required.
JP 2002-110334 A

  Accordingly, an object of the present invention is to provide a method capable of reliably preventing a coil burnout accident that could not be avoided by conventional roll temperature control.

  As a result of repeated studies such as measuring the temperature of each part in the jacket roll in order to achieve the above object, the present inventor has found the following facts. That is, when the roll shell temperature is maintained at 220 ° C., the iron core of the new coil is heated to about 430 ° C., but does not exceed the heat resistance temperature of the coil (about 480 ° C.). We don't have any problems. However, when the iron core ages and its iron loss increases, the iron core of the coil is heated by Joule heat, and the temperature may rise by 50 ° C. or more than the new iron core to exceed the heat resistance temperature of the coil wire. Then, the coil wire in contact with the iron core is softened and the insulation coating is destroyed, resulting in coil burning due to a ground fault. Such temperature rise of the coil iron core has been conventionally ignored, and no means for detecting it has been incorporated.

The present invention has been completed based on the above findings, and the invention of claim 1 is a temperature sensor between the inner peripheral surface of each coil of the jacket roll having a plurality of coils and the outer peripheral surface of the iron core. A temperature sensor is also installed between the inner peripheral surface of the roll shell and the outer peripheral surface of the coil to measure the iron core temperature during energization, and the iron when the jacket roll rises to the equilibrium point The core temperature is compared with a reference temperature, and an alarm is output when the temperature difference between the two exceeds a threshold value.

According to the invention of claim 2, a temperature sensor is attached to the iron core between the inner peripheral surface of each coil of the jacket roll having a plurality of coils and the outer peripheral surface of the iron core, and the iron core temperature during operation is online. At the same time, a temperature sensor is attached to the roll between the inner peripheral surface of the roll shell and the outer peripheral surface of the coil to measure the roll temperature, and the power supplied to each coil is adjusted so that the roll temperature becomes the set temperature. While controlling the sum, the power distribution to the coils having a relatively high iron core temperature is relatively reduced.

According to the invention of claim 1, the coil between the inner peripheral surface of the coil of the jacket roll and the outer peripheral surface of the iron core, and between the inner peripheral surface of the roll shell and the outer peripheral surface of the coil, which has not been measured conventionally. By measuring the iron core temperature during energization and grasping the temperature rise from the reference temperature, the progress of deterioration of the iron core can be known. For this reason, necessary accident prevention measures including the method of claim 2 can be taken. Measurement can be performed online or offline.

  According to the invention of claim 2, while maintaining the roll temperature at the set temperature, the power distribution to the coil having a relatively high iron core temperature is reduced and the coil is distributed to the coil having a relatively low iron core temperature. The temperature rise of the coil whose core deterioration has progressed can be suppressed and coil burnout can be prevented. Even if the distribution of current to each coil is changed in this way, the jacket roll has a jacket chamber with a heat pipe function, so the temperature distribution of the roll is kept uniform, and there is no problem in heating the steel plate. Does not occur.

  FIG. 1 is a cross-sectional view showing an example of a configuration of a jacket roll that is an object of the present invention. 1 is a coil holder on a fixed side, and 2 is a roll shell that is rotatably supported by a bearing 3 on its outer periphery. A plurality of coils 5 each having an iron core 4 are provided on the outer periphery of the coil holder 1. In this embodiment, five coils 5 are arranged, but the number is arbitrary. A jacket chamber 6 is formed in the roll shell 2, and a heat medium is sealed in a vacuum state to constitute a heat pipe. For this reason, the temperature of the roll shell 2 is kept almost constant in any part. The above configuration is the same as the conventional product.

In the present embodiment, two roll temperature sensors 7 are attached between the inner peripheral surface of the roll shell 2 and the outer peripheral surface of the coil 5, and the inner peripheral surface of each coil 5 and the outer periphery of the iron core 4. A temperature sensor 8 is also mounted between the surface and the roll temperature and the iron core temperature during the energization operation are measured.

FIG. 2 is a graph schematically showing changes in the iron core temperature of the AB2 coils 5 detected by the temperature sensor 8. The temperature is initially room temperature, but the iron core temperature of each coil 5 is gradually raised by energizing and preheating until the roll shell 2 reaches 220 ° C. in preparation for operation. However, the temperature rise curve of the iron core temperature varies as shown in the figure due to the difference in position and capacity of each coil 5. In this embodiment, the iron core temperature of each coil 5 at the timing of the operation ready, and stored as a reference temperature T _0.

Although the operation shifts to the operation after the preheating is completed, the roll shell 2 is removed by contact with the steel plate, so the heat amount corresponding to the heat is supplied to keep the temperature of the roll shell 2 (measured value of the roll temperature sensor 7) constant. Therefore, the control device increases the energization amount to each coil 5. As a result, the temperature of the roll shell 2 is constant, the iron core temperature of each coil 5 as shown in FIG. 2 is gradually raised, and finally reaches the equilibrium point T _1.

To obtain the equilibrium point T ₁ of the at Atsushi Nobori is used differentiating circuit example, it is assumed that the temperature rise value per a certain sampling time has reached the equilibrium point T ₁ if it is less than a predetermined value. Sampling every 10 seconds in this embodiment on average 6 times, and it is judged that the value has reached the equilibrium point T ₁ if it is within 1 ℃ compared to the previous value. Then an equilibrium point T ₁ of the iron core temperature of each coil 5 as compared to the reference temperature T _0, and outputs an alarm when the temperature difference T ₁ -T ₀ of both exceeds a threshold value. The iron core temperature of the coil A shown in the graph of FIG. 2 has a temperature difference T ₁ -T ₀ of about 190 ° C., but the iron core temperature of the coil B has a temperature difference T ₁ -T ₀ of 300 ° C. Since it reaches the threshold value of 280 ° C., an alarm is output. Of course, these specific numerical values differ depending on the structure of the individual jacket rolls and operating conditions, and are not limited to the above numerical values.

  Thus, according to the first aspect of the present invention, it is possible to detect an aged deterioration state of the iron core 4 on-line from a change in the iron core temperature of each coil 5, and it is necessary if the progress of the deterioration is confirmed. By taking accident prevention measures, coil burnout of the jacket roll during operation can be prevented.

The reference temperature T ₀ may be a unique temperature. In addition to the timing of preheating to keep the roll surface temperature constant before the operation as described above, all outputs of the temperature sensors 8 are all output. It is also possible to store the output of each temperature sensor 8 at a timing when the temperature enters a certain range (timing at which the temperature in the roll becomes equivalent to room temperature) or the like, and set the reference temperature T ₀ . However, if the reference temperature T ₀ is taken at the timing of completion of preheating as in the embodiment, the influence of the arrangement of each coil 5 and the output difference can be canceled and only the rise in the core temperature due to energization during operation can be accurately detected. preferable.

In the above-described embodiment, the iron core temperature is measured online during the energization operation, but the same measurement can be performed offline. In that case, temperature control is performed by applying a virtual load to the roll surface by a method such as air blowing or by applying a constant output power to each coil 5 to measure the temperature rise width (T ₁ -T ₀ ). In this case, the temperature before heating is taken as the reference temperature T ₀ , and the deterioration progress of the iron core 6 can be accurately grasped by displaying T ₁ -T ₀ over time.

  In the invention of claim 1 described above, the jacket roll is prevented from being burned out by diagnosing the deterioration state of the iron core, but according to the invention of claim 2, the jacket roll in which the deterioration of the iron core has progressed, The lifetime can be extended. That is, as shown in FIG. 3, the distribution ratio to each coil 5 is fixed when performing constant temperature control so that the temperature of the roll shell 2 detected by the roll temperature sensor 7 is constant. The energization amount was distributed regardless of the deterioration of the iron core. On the other hand, in the invention of claim 2, the total power supplied to each coil 5 is controlled so that the roll temperature becomes the set temperature, but the distribution ratio to each coil 5 is set to iron. Change according to the deterioration of the lead.

  FIG. 4 is a diagram showing a first embodiment of the invention of claim 2. Like the invention of claim 1, a temperature sensor 8 is attached to the iron core 4 of each coil 5, and the iron core temperature during operation is online. When the measured temperature exceeds the set temperature, the output power to the coil 5 is stored and used as the threshold value of the coil 5. Then, the limiter restricts the electric power exceeding the threshold from being supplied to the coil 5.

  For example, when the iron core temperature of the central coil 5 exceeds a set value, when more power is required to maintain the roll temperature constant, the other coil to which the limiter does not act is added. Distribute evenly. According to this method, since the output of the coil 5 having a high iron core temperature indication value can be restricted while maintaining the roll temperature constant, the coil can be used properly according to the deterioration state of the iron core, and the life can be extended.

  FIG. 5 is a diagram showing a second embodiment of the invention of claim 2, wherein the average value of the indicated values of each iron core temperature measured by the temperature sensor 8 is obtained, and the deviation from the actual temperature of each temperature sensor 8 is obtained. An example of performing output distribution with weights is shown. For example, when the temperatures of five coils are the values shown in the upper column of Table 1, the average temperature is 2 ° C., and the deviation between the average temperature and the actual temperature is the value shown in the middle column. Therefore, for example, the temperature distribution ratio is determined by the equation 1 + α × (thermometer average value−thermometer instruction value). Here, when α = 1/50, the temperature distribution ratio is as shown in the lower column of Table 1.

  When the temperature distribution is performed in this manner, the output of the No. 3 coil decreases, and the output of the other coils increases accordingly. Thereby, the iron core temperature can be made asymptotic to the average value. In this example, proportional control with α as the proportional gain is adopted. However, load distribution can be more evenly distributed by using an idea that the steady-state deviation can be made zero by introducing integral control. . In this way, various logics can be used to change the distribution ratio, but by changing the distribution of the energization power according to the iron core temperature, the burden on the coil with advanced iron core deterioration is reduced, and the jacket The coil can be prevented from being burned out.

It is sectional drawing which shows an example of a jacket roll. It is a graph of the iron core temperature explaining invention of Claim 1. It is explanatory drawing of the temperature constant control conventionally performed. It is explanatory drawing which shows 1st Embodiment of invention of Claim 2. It is explanatory drawing which shows 2nd Embodiment of invention of Claim 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coil holder 2 Roll shell 3 Bearing 4 Iron core 5 Coil 6 Jacket chamber 7 Roll temperature sensor 8 Temperature sensor

Claims (3)

A temperature sensor is attached between the inner peripheral surface of each coil of the jacket roll having a plurality of coils and the outer peripheral surface of the iron core, and a temperature sensor is also provided between the inner peripheral surface of the roll shell and the outer peripheral surface of the coil. Measures the temperature of the iron core while it is installed , compares the iron core temperature when the jacket roll is heated and reaches the equilibrium point with the reference temperature, and outputs an alarm when the temperature difference between the two exceeds the threshold A method for preventing coil burnout of a jacket roll. A temperature sensor is attached to the iron core between the inner peripheral surface of each coil of the jacket roll having a plurality of coils and the outer peripheral surface of the iron core, and the temperature of the iron core during operation is measured online . A temperature sensor is attached to the roll between the peripheral surface and the outer peripheral surface of the coil, the roll temperature is measured, and the total amount of power supplied to each coil is controlled so that the roll temperature becomes the set temperature. A method for preventing coil burnout of a jacket roll, characterized by relatively reducing power distribution to a coil having a relatively high temperature.   The jacket roll includes a fixed coil holder having a plurality of coils with iron cores and a roll shell rotatably supported on the outer periphery thereof, and the heat medium is hermetically sealed in a jacket chamber formed in the roll shell in a vacuum state. 3. The method for preventing coil burnout of a jacket roll according to claim 1 or 2, wherein the coil roll has the structure described above.

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