JP2011202223A - Device for detecting rotational speed of roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for detecting rotational speed of a roller which can highly accurately detect rotational speed of a roller in a bath.SOLUTION: The device for detecting rotational speed of a roller includes: a permanent magnet provided at a roller installed in a molten metal and rotating together with the roller; a detection part detecting a magnetic field formed by the permanent magnet; and a protection part formed by a non-magnetic body which is not eroded by the molten metal and enclosing the detection part. The distance between the permanent magnet and the detection part in a radial direction of the roller is set to be 5 to 20 mm. Since the detection part is disposed in a position of 5 to 20 mm distance from the permanent magnet in a state intercepted from the molten metal, the magnetic field of the permanent magnet can be detected in a high level and rotational speed of the roller can be highly accurately measured. Since the detection part is intercepted from the molten metal, the life of the detection part can be made long.

Description

  The present invention relates to a roll rotation speed detection device that measures the rotation speed of a roll installed in a metal bath.

  A continuous hot dip plating apparatus for metal strips (for example, steel strips) is a steel roll that is pulled up in the vertical direction from a sink roll for changing the traveling direction of the steel strip in a plating bath filled with molten metal such as zinc. An upper and lower support roll that sandwiches the band is disposed, and a wiping nozzle is provided outside the plating bath. In this continuous hot dipping apparatus, the steel strip introduced obliquely downward into the plating bath passes through while being sandwiched between the upper and lower support rolls after its traveling direction has been changed vertically upward by the sink roll. The molten metal adhering to the surface is wiped off by the wiping nozzle and controlled to a predetermined basis weight.

  In such a production line of molten metal-plated steel strip, plating is unevenly adhered to the steel strip or wrinkles are generated due to vibrations caused by the roller bearings and slips generated between the roll and the steel strip. It is a problem to do. For this reason, the occurrence of slip is monitored by detecting the rotational speed of the roll.

  For example, Patent Document 1 discloses a roll rotation speed in a bath in which a permanent magnet is disposed on a roll in a metal bath and the magnetic force of the permanent magnet is detected by a detection sensor provided outside the bath to detect the rotation speed of the roll in the bath. A detection device is disclosed. By providing a detection sensor for detecting the rotation speed of the roll in the bath outside the bath, the detection sensor is prevented from being immersed in a high-temperature bath, thereby preventing the product life of the detection sensor from being reduced. Patent Document 2 discloses a bath in which a permanent magnet is disposed on a roll in a metal bath, and a transmission means for transmitting the magnetic force of the permanent magnet to the detection sensor is provided between the detection sensor and the permanent magnet provided outside the bath. An intermediate roll rotation speed detection device is disclosed. By providing such a transmission means, it is possible to detect the rotation speed of the roll in the bath even when the permanent magnet and the detection sensor are spaced apart.

JP 2007-291431 A JP 2009-97019 A

  However, in Patent Document 1, since the detection sensor is installed outside the bath, the distance between the permanent magnet provided on the roll in the bath and the detection sensor is large. For this reason, there is doubt whether the magnetic force of the permanent magnet can be sufficiently detected at the detection position by the detection sensor. Moreover, in the said patent document 2, since the magnetic force of a permanent magnet is transmitted to a detection position by a transmission means, it is thought that the subject in patent document 1 is improved. However, the level of the detection signal of the detection sensor depends on the magnetic force of the permanent magnet. When the magnetic force of the permanent magnet is increased, the interval between adjacent permanent magnets cannot be reduced, and the resolution is lowered. As a result, it becomes difficult to detect the rotation speed of the roll in the bath with high accuracy by the detection sensor. Moreover, even if it is the structure which detects a magnetism outside a bath like patent document 2, the influence of magnetic forces (for example, electromagnetic damping device, peripheral motors, etc.) other than the magnetic field of the permanent magnet installed in the bath roll is exerted. There is also a possibility of receiving. In this case, it is considered that the detection sensor may adversely affect the detection of the rotation speed of the roll in the bath.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved roll rotation capable of detecting the rotation speed of the roll in the bath with high accuracy. It is to provide a speed detection device.

  In order to solve the above problems, according to one aspect of the present invention, a permanent magnet provided on a roll installed in a molten metal and rotating together with the roll, and a detection unit for detecting a magnetic field formed by the permanent magnet, A protective portion that is formed of a nonmagnetic material that is not eroded by the molten metal and surrounds the detection portion, and the distance between the permanent magnet and the detection portion in the radial direction of the roll is 5 to 20 mm. A roll rotation speed detection device is provided.

  According to the present invention, the detection unit is surrounded by the protection unit made of a material that is not eroded by the molten metal, and the detection unit and the permanent magnet are arranged to face each other. That is, the detection unit is disposed at a position where the distance from the permanent magnet is 5 to 20 mm while being shielded from the molten metal. Thus, since the distance between the detection unit and the permanent magnet can be made closer, the detection unit can detect the magnetic field of the permanent magnet at a high level and can measure the rotation speed of the roll with high accuracy. . Moreover, since the detection part is shielded from the molten metal, the life of the detection part can be extended.

  Here, the protection part can also include an insertion part into which a coolant that cools the detection part flows from the outside, and a discharge part that discharges the coolant from the internal space of the protection part. The coolant that has flowed in from the insertion portion circulates in the internal space of the protection portion and is discharged from the discharge portion. Thus, by cooling the space in which the detection unit is arranged with the coolant, the detection unit can detect the magnetic field of the permanent magnet at a higher level.

  Moreover, it is preferable to use any one of a molybdenum-added material, a ceramic, and a cobalt-based metal as a material for the protective portion. By using these materials, the protection part can be prevented from being eroded by the molten metal, and the detection part can be reliably shielded from the molten metal.

  Further, the detection unit may be configured to include a coil wound around an axis of a magnetic body, and output the inductance of the coil that is changed by a magnetic field formed by a permanent magnet as a detection value. When the permanent magnet rotates as the roll rotates, the inductance of the coil changes. The roll rotation speed detection device can acquire the rotation speed of the permanent magnet, that is, the roll, based on the inductance change of the coil.

  Moreover, in order to solve the said subject, according to another viewpoint of this invention, it is provided in the roll installed in the molten metal, and detects the magnetic field formed with the permanent magnet which rotates with a roll, and a permanent magnet. A detection unit, and a protection unit that is formed of a nonmagnetic material that is not eroded by the molten metal and surrounds the detection unit, and the distance between the permanent magnet and the detection unit in the radial direction of the roll is such that the permanent magnet and the detection unit are There is provided a roll rotation speed detection device characterized in that it is not less than a minimum distance that does not contact and not more than a maximum distance at which a detection part can detect a predetermined or more magnetic field.

  According to the present invention, the detection unit is surrounded by the protection unit made of a material that is not eroded by the molten metal, and the detection unit and the permanent magnet are arranged to face each other. That is, the detection unit is cut off from the molten metal, and the distance from the permanent magnet is not less than the minimum distance at which the permanent magnet and the detection unit do not contact each other and not more than the maximum distance at which the detection unit can detect a predetermined magnetic field or more. It is arranged at the position. When the permanent magnet comes into contact with the detection unit, the rotation speed of the roll cannot be detected. In addition, when the detection unit cannot detect a magnetic field exceeding a predetermined value, that is, when a sufficient signal / noise ratio cannot be obtained, the rotation speed of the roll cannot be detected with high accuracy. Accordingly, the rotation speed of the roll can be detected by setting the upper limit value of the distance between the detection unit and the permanent magnet in this way. In the roll rotation speed detection device of the present invention, since the distance between the detection unit and the permanent magnet can be made closer, the detection unit can detect the magnetic field of the permanent magnet at a high level, and the rotation speed of the roll can be accurately detected. Can be measured. Moreover, since the detection part is shielded from the molten metal, the life of the detection part can be extended.

  As described above, according to the present invention, it is possible to provide a roll rotation speed detection device capable of detecting the rotation speed of the roll in the bath with high accuracy.

It is a schematic diagram which shows the continuous hot dipping apparatus concerning embodiment of this invention. It is a side view which shows the arrangement | positioning state of the roll rotational speed detection apparatus of the roll in bath concerning the embodiment. It is a rear view of FIG. 2 which shows the arrangement | positioning state of the roll rotational speed detection apparatus of the roll in bath concerning the embodiment. It is explanatory drawing which shows the positional relationship of the magnet part and sensor part of a roll rotational speed detection apparatus. It is a partially cutaway sectional view showing the configuration of the roll rotation speed detecting device according to the same embodiment. It is a top view which shows the structure of the roll rotational speed detection apparatus concerning the embodiment. It is sectional drawing in the cutting line AA of FIG. It is a simulation result which shows the sensor output of a sensor part when changing the rotational speed and sensor temperature of a roll in the case of fixing sensor / magnet space | interval d to 10 mm. It is a simulation result which shows the sensor output of a sensor part when changing the rotational speed and sensor temperature of a roll in the case of fixing sensor / magnet space | interval d to 20 mm. It is a graph which shows the relationship between sensor temperature and sensor output amplitude at the time of fixing sensor / magnet space | interval d to 10 mm. It is a simulation result which shows the relationship between the sensor / magnet space | interval d and a sensor output. It is a simulation result which shows the relationship between sensor / magnet space | interval d and a sensor output amplitude.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[Construction of continuous hot dipping equipment]
First, a continuous hot dipping apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing a continuous hot dipping apparatus 1 according to the present embodiment.

  As shown in FIG. 1, a continuous hot dipping apparatus 1 is an apparatus for continuously adhering molten metal to the surface of a steel strip 2 by immersing the steel strip 2 in a plating bath 3 filled with molten metal. It is. The continuous hot dipping apparatus 1 includes a bathtub 4, a snout 5, a sink roll 6, a pair of upper and lower support rolls 7 and 8, a gas wiping nozzle 9, and a pair of touch rolls 10 and 11.

  The steel strip 2 is an example of a metal strip to be plated with molten metal. In the present embodiment, an example of the steel strip 2 will be described. However, the metal strip of the present invention is not limited as long as it is a strip-shaped metal material to be plated. The molten metal is generally a corrosion-resistant metal such as zinc, lead-tin, or aluminum, but may be other metal used as a plating metal. Typical examples of the hot dip galvanized steel strip obtained by plating the steel strip 2 with a molten metal include a galvanized steel strip and an alloyed galvanized steel strip, but may be other types of galvanized steel strip. .

  The bathtub 4 stores the plating bath 3 made of the molten metal. The snout 5 is inclined so that one end thereof is immersed in the plating bath 3.

  The sink roll 6 is disposed at the lowermost position in the plating bath 3 and has a larger roll diameter than the support rolls 7 and 8. The sink roll 6 changes the direction of the steel strip 2 introduced through the snout 5 and obliquely downward into the plating bath 3 in the vertical direction.

  The support rolls 7 and 8 are disposed above the sink roll 6 in the plating bath 3 and are disposed so as to sandwich the steel strip 2 pulled up from the sink roll 6 in the vertical direction from both the left and right sides. The support rolls 7 and 8 are rotatably supported by bearings (not shown) (for example, slide bearings, rolling bearings, etc.). The support rolls 7 and 8 according to the present embodiment are non-driven, and rotate following the steel strip 2 that is passed through at high speed. The support rolls 7 and 8 may be driven by a motor or the like.

  The gas wiping nozzle 9 is provided outside the plating bath 3 and blows gas to the surface of the steel strip 2 pulled up from the plating bath 3 in the vertical direction to wipe off excess molten metal. Thereby, the basis weight of the molten metal with respect to the steel strip 2 can be controlled to an appropriate amount. The touch rolls 10 and 11 are disposed above the gas wiping nozzle 9 and support the steel strip 2 sandwiched from both sides. In addition, the continuous hot dipping apparatus 1 can also be set as the structure which does not provide the touch rolls 10 and 11. FIG.

  Here, operation | movement of the continuous hot dipping apparatus 1 of the said structure is demonstrated. The continuous hot dipping apparatus 1 moves the steel strip 2 in the longitudinal direction by a drive source (not shown) and passes each part in the apparatus. The steel strip 2 is introduced obliquely downward into the plating bath 3 through the snout 5 and circulates around the sink roll 6 so that its traveling direction is converted upward in the vertical direction. Next, the steel strip 2 rises while being sandwiched between the support rolls 7 and 8 and is pulled out of the plating bath 3. At this time, the shape of the steel strip 2 is corrected by the support rolls 7 and 8, and warpage in the width direction is suppressed. Thereafter, the steel strip 2 pulled out of the plating bath 3 is controlled to a predetermined basis weight by wiping away excess molten metal by the gas wiping nozzle 9 and reaches the touch rolls 10 and 11. In this way, the continuous hot dipping apparatus 1 continuously immerses the steel strip 2 in the plating bath 3 and performs plating with the molten metal.

[Configuration of roll rotation speed detection device]
Next, based on FIGS. 2-7, the structure of the roll rotational speed detection apparatus 100 concerning this embodiment is demonstrated. Below, although the roll rotational speed detection apparatus 100 concerning this embodiment is demonstrated in order to detect the rotational speed of the support roll 8 of the continuous hot dipping apparatus 1, the other support roll 7 and sink roll are demonstrated. It is also possible to install it as a measure of the rotational speed of the roll in the bath immersed in the plating bath 3 such as 6. When the rotational speed of the non-driven roll is measured, the occurrence of roll slip can be found from the measured rotational speed of the roll. Moreover, when measuring the rotational speed of a drive-type roll, it can be determined whether the rotation is synchronizing with the moving speed of the steel strip 2 from the measured rotational speed of the roll.

  In addition, FIG. 2 is a side view which shows the arrangement | positioning state of the roll rotational speed detection apparatus 100 of the roll in a bath concerning this embodiment. FIG. 3 is a rear view of FIG. 2 showing an arrangement state of the roll rotation speed detection device 100 for the in-bath roll according to the present embodiment. FIG. 4 is an explanatory diagram showing a positional relationship between the magnet unit 110 and the sensor unit 120 of the roll rotation speed detection device 100. FIG. 5 is a partially cutaway cross-sectional view showing the configuration of the roll rotation speed detection device 100 according to the present embodiment. FIG. 6 is a plan view showing a configuration of the roll rotation speed detection device 100 according to the present embodiment. FIG. 7 is a cross-sectional view taken along line AA in FIG. Here, FIG. 2 shows a state in which the support roll 8 shown in FIG. 3 is removed. 2, 3 and 5, the cables 124a and 124b and the sheath wire 125 are collectively shown as reference numeral 127 as wiring.

  2 to 4, the roll rotation speed detection device 100 according to the present embodiment detects the rotation speed of the magnet unit 110 provided at one end of the rotation shaft 8a of the support roll 8 and the magnet unit 110. The sensor unit 120 includes a protection unit 130 that surrounds the sensor unit 120. Since the sensor unit 120 according to the present embodiment is disposed in the plating bath 3 in a state surrounded by the protection unit 130, it is not immersed in the molten metal. In addition, the sensor unit 120 according to the present embodiment is provided so as to be suspended from the lid unit 132 in order to avoid contact with the main body unit 131 of the protection unit 130 that contacts high-temperature molten zinc.

  The magnet part 110 includes an annular base part 112 provided on the rotating shaft of the roll so as to rotate together with the roll, and a plurality of permanent magnets 114 provided on the peripheral side surface of the base part 112. In the present embodiment, eight permanent magnets 114 are provided at equal intervals in the circumferential direction of the base 112, but the present invention is not limited to this example, and at least one permanent magnet 114 is provided. Just do it.

  The sensor unit 120 is a detection unit provided to face the peripheral side surface of the magnet unit 110. The sensor unit 120 is a magnetic force sensor that can detect a magnetic field change that detects the rotation speed of the support roll 8 by detecting the magnetic force of the magnet unit 110 that rotates together with the support roll 8. Since the sensor unit 120 is surrounded by the protection unit 130, the sensor unit 120 is not immersed in the molten metal. Thereby, the product life of the sensor part 120 can be lengthened.

  As shown in FIG. 7, the sensor unit 120 according to the present embodiment includes a coil 121, a magnetic core 122, a bobbin 123, a sensor cable 124, and a sheath thermocouple 125. The coil 121 is a heat-resistant magnet wire and is wound around a magnetic core 122 that is an axis of a magnetic material supported by the bobbin 123. The inductance of the coil 121 changes according to the magnetic field of the permanent magnet 114 of the magnet unit 110. The coil 121 is connected to the sensor cable 124. The sensor cable 124 includes cables 124 a and 124 b connected to both ends of the coil 121, and the inductance of the coil 121 output from the cables 124 a and 124 b drawn to the outside of the protection unit 130 calculates the rotation speed of the roll. Detection signal.

  The sensor unit 120 calculates the rotation speed of the roll based on the change in the detection signal (voltage proportional to the inductance). More specifically, the rotation speed of the roll is calculated by detecting an inductance change due to the magnetic characteristics of the coil core material (magnetic material) when an external magnetic field of the coil 121 is applied. The detection signal (voltage) is small when the coil 121 is not facing the permanent magnet 114 of the magnet unit 110, and is large when the coil 121 is facing the permanent magnet 114. In addition, the magnetic material used as the coil core material has a characteristic that the permeability decreases exponentially as the external magnetic field increases.

  The sensor unit 120 obtains a sensor output signal that changes depending on the presence or absence of the permanent magnet 114 of the magnet unit 110 facing the coil 121 based on a relationship in which the inductance of the coil 121 is proportional to the magnetic permeability of the coil core material. The sensor output signal has a characteristic of exponentially decreasing as the external magnetic field increases. And when the magnet part 110 rotates, according to the change of the inductance of the coil 121, a sensor output signal will change to a sine wave form.

  The sheath thermocouple 125 is provided to measure the temperature of the space where the sensor unit 120 that detects the rotation speed of the roll exists. When the sensor unit 120 is placed in a high temperature environment, the wiring of the sensor cable 124 and the like is oxidized, the life of the sensor unit 120 is shortened, and the magnetic field detection accuracy is also lowered. In the sensor unit 120 according to the present embodiment, the temperature is monitored by the sheath thermocouple 125 so that the sensor unit 120 is not placed in a high temperature environment. The temperature in the protection unit 130 is adjusted by flowing a coolant into the protection unit 130. A cooling structure for cooling the sensor unit 120 will be described later. The detection value obtained by the sheath thermocouple 125 is acquired through the sheath wire 125 a drawn out of the protection unit 130.

  The protection part 130 is a guard member that shields the sensor part 120 from the molten metal. The protection unit 130 is formed of a nonmagnetic material that is not eroded by a molten metal such as molten zinc. Examples of such a material include, for example, stainless steel such as SUS316, SUS317, SUH38, and SUH661, which is improved in corrosion resistance and pitting corrosion resistance by adding molybdenum, heat resistant steel, ceramic such as sialon, Trivalloy (registered trademark), There are cobalt-based metals such as Stellite (registered trademark). As shown in FIGS. 2 and 3, a part of the protection part 130 is immersed in the plating bath 3, but is not eroded by the molten metal because it is made of the above material. Thereby, the sensor part 120 accommodated in the inside of the protection part 130 can be reliably shielded from the molten metal.

  The protection part 130 is formed in a cylindrical shape, for example, and houses the sensor part 120 therein as shown in FIG. The protection unit 130 is held by the holding unit 140 so that the sensor unit 120 faces the magnet unit 110 provided on the rotation shaft of the roll with a predetermined distance. At this time, the protection part 130 is provided so as to be substantially orthogonal to the center line of the cylinder extending in the longitudinal direction of the protection part 130 and the tangential direction of the outer periphery of the base part 112 of the magnet part 110. The holding part 140 is supported by a roll support part 150 fixed to the continuous hot dipping apparatus 1.

  More specifically, as shown in FIG. 7, the protection unit 130 includes a cylindrical main body 131 whose one end is sealed and a lid 132 that seals the other end of the main body 131. The other end of the main body portion 131 and the lid portion 132 are fixed in close contact with a bolt 133 via a plain washer. Thereby, the internal space of the protection part 130 is shielded from the molten metal, and the molten metal can be prevented from entering the inside. The lid part 132 is formed with a lid cylindrical part 132 a that houses the sensor part 120. The lid cylindrical portion 132 a is formed integrally with the lid portion 132 and extends from the center portion of the lid portion 132 in the longitudinal direction of the main body portion 131. One end side of the lid cylindrical portion 132a facing the magnet portion 110 is sealed in the same manner as the main body portion 131. On the other hand, the other end side of the lid cylindrical portion 132a is provided with a discharge pipe 136 for drawing out the wiring and the like of the sensor portion 120, and communicates with the outside. A passage hole 132b for moving the coolant is formed on the peripheral side surface of the lid cylindrical portion 132a.

  In addition, the lid 132 is provided with an insertion tube 134 for allowing a coolant for cooling the sensor unit 120 to flow into the protective part 130, adjacent to the lid cylindrical part 132 a in the radial direction of the lid 132. The insertion tube 134 is a tubular member that opens at both ends. The coolant that has flowed in from the outside through the insertion tube 134 moves through the internal space of the main body 131 as shown by the dashed arrows in FIG. 7, enters the internal space of the lid cylindrical portion 132a from the passage hole 132b, and is discharged from the discharge tube. It is discharged from 136 to the outside. Here, as a coolant, inert gas, such as air and nitrogen gas, can be used, for example. In addition, by making members such as the main body part 131 and the lid cylindrical part 132a of the protection part 130 into a cylindrical shape, the flow path of the cooling fluid can be clarified, and the sensor part 120 can be reliably cooled.

  The roll rotation speed detection device 100 according to the present embodiment protects the sensor unit 120 with the protection unit 130 and increases the sensor output amplitude of the sensor unit 120 by bringing the magnet unit 110 and the sensor unit 120 closer to each other. be able to. The distance (also referred to as “sensor / magnet interval”) d between the magnet unit 110 and the sensor unit 120 in the tangential direction of the outer periphery of the base unit 112 shown in FIG. 4 is set to about 5 to 20 mm. If the distance d is less than 5 mm, the magnet unit 110 and the protection unit 130 surrounding the sensor unit 120 may come into contact with each other. On the other hand, if the distance d is greater than 20 mm, the sensor output amplitude by the sensor unit 120 decreases, and the rotation speed of the roll cannot be detected with high accuracy.

  In addition, the roll provided with the magnet unit 110 may cause a shake of about several mm in the radial direction. Considering this, in order to avoid the contact between the magnet unit 110 and the sensor unit 120 and to detect the rotation speed of the roll with high accuracy, the distance d between the magnet unit 110 and the sensor unit 120 is about 15 to 20 mm. It is desirable to set to.

  Note that the upper limit value of the distance d may be set to the maximum distance at which a magnetic field of a predetermined value or more can be detected by the sensor unit 120 of the permanent magnet 114 of the magnet unit 110. This is because the rotational speed of the roll cannot be detected with high accuracy when the sensor unit 120 cannot detect a magnetic field of a predetermined value or more, that is, when a sufficient signal / noise ratio cannot be obtained. The signal / noise ratio detected by the sensor unit 120 depends on the magnetic field strength of the permanent magnet 114, the distance to the adjacent permanent magnet 114, the sensor sensitivity, the temperature, and the like. For this reason, the upper limit of the distance d is appropriately set based on these conditions. In addition, increasing the distance d may reduce the sensor output amplitude by the sensor unit 120 and may be affected by noise. In this case, the sensor output amplitude can be increased by increasing the number of turns of the coil of the sensor unit 120 described later.

  As described above, the roll rotation speed detection device 100 according to the present embodiment has a cooling structure that cools the sensor unit 120. The bath temperature of the plating bath 3 is usually as high as about 450 to 460 ° C. In such an environment, the detection performance of the sensor unit 120 is degraded, so that the temperature of the space in which the sensor unit 120 is disposed is lowered by the coolant from the temperature in the bath. Thereby, the sensor output amplitude of the sensor unit 120 can be kept high.

[simulation result]
<1. Verification of sensor output amplitude of the sensor unit when the rotation speed of the roll and the sensor temperature are changed when the sensor / magnet interval d is fixed>
A simulation was performed to verify the effect of the roll rotation speed detection device 100 according to the present embodiment. First, the distance (sensor / magnet interval) d between the magnet unit 110 and the sensor unit 120 is fixed, and the rotation speed of the roll provided with the magnet unit 110 and the temperature (sensor temperature) of the arrangement space of the sensor unit 120 are changed. The sensor output amplitude of the sensor unit 120 when verified was verified. The results are shown in FIGS. FIG. 8 is a simulation result when the distance d between the magnet unit 110 and the sensor unit 120 is fixed to 10 mm, and FIG. 9 is a simulation when the distance d between the magnet unit 110 and the sensor unit 120 is fixed to 20 mm. It is a result. FIG. 10 is a graph showing the relationship between the sensor temperature and the sensor output amplitude when the distance d between the magnet unit 110 and the sensor unit 120 is fixed to 10 mm.

  In this simulation, it is assumed that the sensor unit 120 guarded by the protection unit 130 is placed in a bath at about 460 ° C. It is assumed that the magnet unit 110 is provided with eight permanent magnets 114 at equal intervals in the circumferential direction. The rotation speed of the roll was measured for four cases of 50 rpm, 100 rpm, 150 rpm, and 200 rpm. Of these, 200 rpm, which has the highest rotation speed, is the maximum speed that is desired to be detected in the actual machine. The sensor temperature was measured in five cases: in the atmosphere (about 18 ° C.) and in the bath (about 215 ° C., about 280 ° C., about 355 ° C., about 420 ° C.). At the highest sensor temperature (about 420 ° C.), the sensor unit 120 is not cooled.

  The sensor output signal output from the sensor unit 120 has a waveform like a sine wave as shown in FIGS. One peak of this waveform corresponds to one permanent magnet 114 of the magnet unit 110. When the magnet unit 110 rotates and the permanent magnet 114 approaches the sensor unit 120, the sensor output signal output from the sensor unit 120 gradually decreases. When the permanent magnet 114 approaches the sensor unit 120 most, the sensor output signal is minimum. Become. And if the magnet part 110 rotates and the permanent magnet 114 is separated from the sensor part 120, the sensor output signal which the sensor part 120 outputs will become large gradually. That is, when the magnet unit 110 rotates together with the roll, the strength of the magnetic field of the permanent magnet 114 detected by the sensor unit 120 changes. From the period of the waveform of the sensor output signal, the time required for the roll to rotate by the distance of the adjacent interval between the permanent magnets 114 can be acquired, and the rotation speed of the roll can be calculated.

  In this simulation, the change in the magnitude of the sensor output amplitude, which is the sensor output of the sensor unit 120, when the roll rotation speed or the sensor temperature is changed was verified. First, in the case where the distance d between the magnet unit 110 and the sensor unit 120 shown in FIG. 8 is fixed to 10 mm, the magnitude of the sensor output amplitude is not changed even if the rotation speed of the roll is changed with the sensor temperature kept constant. There was little change. Thus, according to the roll rotation speed detection device 100 according to the present embodiment, it can be seen that a stable detection signal is output by the sensor unit 120 regardless of the rotation speed of the roll.

  When the sensor temperature is changed, as shown in FIGS. 8 and 10, the sensor output amplitude increases as the sensor temperature increases from room temperature to about 215 ° C., but the sensor temperature is about 215 ° C. As it becomes higher, the sensor output amplitude becomes smaller. That is, when the sensor unit 120 is placed in the bath, the sensor output amplitude output from the sensor unit 120 increases when the sensor unit 120 is sufficiently cooled, and the roll rotation speed can be measured with high accuracy. Become. In addition, the sensor output amplitude is increased by cooling the sensor unit 120 inside the protection unit 130, so that the signal / noise ratio can be improved.

  Next, in the case where the distance d between the magnet unit 110 and the sensor unit 120 shown in FIG. 9 is fixed to 20 mm, the same result as in FIG. 8 is obtained. That is, even if the rotation speed of the roll is changed while keeping the sensor temperature constant, the magnitude of the sensor output amplitude hardly changes, so that a stable detection signal is output by the sensor unit 120 regardless of the rotation speed of the roll. I understand that Further, when the sensor temperature is changed, the sensor output amplitude increases as the sensor temperature increases, but the sensor output amplitude decreases as the sensor temperature becomes higher than about 215 ° C. From this, it can be seen that the sensor output amplitude output from the sensor unit 120 increases when the sensor unit 120 is sufficiently cooled, and the rotation speed of the roll can be measured with high accuracy. In addition, the sensor output amplitude is increased by cooling the sensor unit 120 inside the protection unit 130, so that the signal / noise ratio can be improved.

  Here, comparing the waveforms of the detection signals in FIG. 8 and FIG. 9, it can be seen that the sensor output amplitude is larger when the distance d between the magnet unit 110 and the sensor unit 120 is 10 mm than when the distance d is 20 mm. Thus, by arranging the magnet unit 110 and the sensor unit 120 as close as possible, the sensor output amplitude output from the sensor unit 120 is increased, and the rotation speed of the roll can be measured with high accuracy.

<2. Relationship between sensor / magnet distance d and sensor output amplitude>
In order to verify in more detail the relationship between the distance (sensor / magnet spacing) d between the magnet unit 110 and the sensor unit 120 and the sensor output amplitude, the rotational speed of the roll or the distance d was changed while keeping the sensor temperature constant. The magnitude of the sensor output amplitude was measured. The experimental results are shown in FIG. 11 and FIG. FIG. 11 is a simulation result showing the relationship between the sensor / magnet interval d and the sensor output amplitude. FIG. 12 is a simulation result showing the relationship between the sensor / magnet interval d and the sensor output amplitude. The sensor output amplitude values shown in FIGS. 11 and 12 are examples.

  In this simulation, it is assumed that the sensor unit 120 is not cooled and the sensor unit 120 guarded by the protection unit 130 is disposed in a bath at about 460 ° C. It is assumed that the magnet unit 110 is provided with eight permanent magnets 114 at equal intervals in the circumferential direction. At this time, the sensor unit when the rotation speed of the roll is changed to 50 rpm, 100 rpm, 150 rpm, and 200 rpm, and the distance d between the magnet unit 110 and the sensor unit 120 is changed to 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm. 120 detection signals output were obtained by simulation.

  As shown in FIG. 11, the sensor output amplitude is the largest when the distance d between the magnet unit 110 and the sensor unit 120 is 5 mm, and the sensor output amplitude becomes smaller as the distance d increases. In this simulation, when the distance d exceeds 20 mm, the sensor output amplitude is smaller than 10 mV. In this case, since there is a possibility that the rotation speed of the roll cannot be detected with high accuracy, it is desirable that the sensor output amplitude is increased to 10 mV or more by increasing the number of turns of the coil to increase the sensor output amplitude. Thereby, even when the upper limit value of the distance d is set to be approximately the same as the arrangement interval (arc length) of the permanent magnets 114 of the magnet unit 110, a sufficient sensor output amplitude can be acquired.

  From the above two simulations, it was found that the sensor output amplitude of the sensor unit 120 can be increased by reducing the distance d between the magnet unit 110 and the sensor unit 120 as much as possible. In addition, it is understood that by cooling the sensor unit 120 disposed in the bath, the sensor output amplitude of the sensor unit 120 can be increased, and the rotation speed of the roll can be detected with high accuracy. It was.

  The roll rotation speed detection device 100 according to the embodiment of the present invention has been described above. According to the roll rotation speed detection device 100, the magnet unit 110 that rotates together with the roll is provided to detect the rotation speed of the roll, and the sensor unit 120 that detects the magnetic field formed by the permanent magnet 114 of the magnet unit 110 is a magnet. Place in the bath close to section 110. Thereby, the amplitude of the detection signal output from the sensor unit 120 can be increased, and the rotation speed of the roll can be measured with high accuracy. At this time, since the sensor part 120 is guarded by the protection part 130 and is shielded from the molten metal, it is possible to prevent a decrease in life due to erosion by the molten metal.

  In addition, the roll rotation speed detection device 100 of this embodiment includes a cooling structure that cools the sensor unit 120. Thereby, since the level of the detection signal output from the sensor unit 120 can be improved, the rotation speed of the roll can be measured with higher accuracy.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, in the above embodiment, the shape of the protection unit 130 is a cylindrical shape, but the present invention is not limited to such an example. For example, the shape of the main body 131 when it is cut in a direction orthogonal to the longitudinal direction of the protection part 130 may be a polygonal shape such as a quadrangle. In the above embodiment, the discharge pipe 136 is used as a wiring outlet and a coolant outlet. However, the present invention is not limited to this example, and a wiring outlet and a coolant outlet are provided. You may do it.

DESCRIPTION OF SYMBOLS 1 Continuous hot dipping apparatus 2 Steel strip 3 Plating bath 4 Bath 5 Snout 6 Sink roll 7, 8 Support roll 8a Roll axis 9 Gas wiping nozzle 10, 11 Touch roll 100 Roll rotational speed detection apparatus 110 Magnet part 112 Base part 114 Permanent Magnet 120 Sensor part 121 Coil 122 Magnetic core 123 Bobbin 124 Sensor cable 125 Sheath thermocouple 127 Wiring 130 Protection part 131 Body part 132 Lid part 132a Lid cylindrical part 134 Insertion pipe 136 Discharge pipe 140 Holding part 150 Roll support part

Claims (5)

A permanent magnet which is provided in a roll installed in the molten metal and rotates with the roll;
A detection unit for detecting a magnetic field formed by the permanent magnet;
A protection part that is formed of a non-magnetic material that is not eroded by the molten metal and surrounds the detection part;
With
The roll rotation speed detection device according to claim 1, wherein a distance between the permanent magnet and the detection unit in a radial direction of the roll is 5 to 20 mm. The protective part is
An insertion part into which a coolant for cooling the detection part flows from the outside;
A discharge part for discharging the coolant from the internal space of the protection part;
The roll rotation speed detection device according to claim 1, comprising:   3. The roll rotation speed detection device according to claim 1, wherein a material of the protection unit is any one of a molybdenum additive material, a ceramic, and a cobalt-based metal. The detection unit is composed of a coil wound around an axis of a magnetic material,
The roll rotation speed detection device according to any one of claims 1 to 3, wherein an inductance of the coil that changes depending on a magnetic field formed by the permanent magnet is output as a detection value. A permanent magnet which is provided in a roll installed in the molten metal and rotates with the roll;
A detection unit for detecting a magnetic field formed by the permanent magnet;
A protection part that is formed of a non-magnetic material that is not eroded by the molten metal and surrounds the detection part;
With
The distance between the permanent magnet and the detection unit in the radial direction of the roll is equal to or greater than a minimum distance at which the permanent magnet and the detection unit do not contact each other and equal to or less than a maximum distance at which a predetermined or more magnetic field can be detected by the detection unit. A roll rotation speed detection device, characterized in that

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