Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
  • G01N27/80—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating mechanical hardness, e.g. by investigating saturation or remanence of ferromagnetic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
  • B21B1/30—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a non-continuous process
  • B21B1/32—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a non-continuous process in reversing single stand mills, e.g. with intermediate storage reels for accumulating work
  • B21B1/34—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a non-continuous process in reversing single stand mills, e.g. with intermediate storage reels for accumulating work by hot-rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D11/00—Process control or regulation for heat treatments
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R33/00—Arrangements or instruments for measuring magnetic variables
  • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
  • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
  • G01R33/063—Magneto-impedance sensors; Nanocristallin sensors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/02—Iron or ferrous alloys
  • B23K2103/04—Steel or steel alloys
  • B23K2103/05—Stainless steel

Definitions

• the present invention relates generally to an on-line measuring system for the degree of transformation on a metallic material, and more particularly to an on-line measuring system for the degree of transformation on a metallic material in a steel- making process which is designed to measure the degree of transformation on a metallic material that would take place during cooling heat treatment thereon such as Run Out Table (ROT) and Accelerated Cooling Chamber (ACC).
• ROT Run Out Table
• ACC Accelerated Cooling Chamber
• phase transformation occurs from the high temperature stable phase of austenite to the low temperature stable phase such as ferrite, bainite and martensite (hereinafter will be commonly referred to as "ferrite").
• ferrite ferrite
• the hot rolling in the steel making process is performed by reheating a slab 11 in a reheating furnace 12 to a temperature suitable for rolling, extracting the reheated slab 11 from the reheating furnace 12, rolling the slab through a roughing mill 13 and a finishing mill 14 into a metallic material of strip 15, cooling the metal strip 15 on an ROT 16 with a cooling equipment 17 suitably to a target temperature through air and/or water cooling in order to obtain aimed mechanical properties, and coiling the cooled strip 15 on a down coiler 18.
• the cooling equipment 17 in the ROT 16 includes a number of banks 20 and 21 each having a plurality of headers, in which the banks 20 are disposed above the ROT 16, whereas the banks 21 are disposed under the ROT 16.
• the upper and lower banks 20 and 21 spray cooling water to cool down the metal strip 15.
• Such a cooling pattern generally starts from the leading banks and proceeds toward the down coiler 18 to cool down the metal trip 15, in which the banks 20 and 21 are adjusted in their opening ratio according to a desired coiling temperature.
• Such cooling heat treatment in the steel- making process is similarly applied to an Accelerated Cooling Chamber (ACC) of a plate-making process.
• ACC Accelerated Cooling Chamber
• FIG. 3 is a schematic view illustrating the inside structure of a typical ACC.
• cooling water 34 is sprayed through cooling water nozzles 32 installed in upper and lower portions of the ACC 30 onto top and bottom surfaces of the metal strip 33 to cool down it.
• the cooling unit of the ACC 30 is fed with high-pressure compressed air through an air compressor and water as well. Compressed air and water fed as such join together at one point of the individual cooling water nozzles 32. Then, water is sprayed at high speed and pressure and scatters into fine water particles by compressed air of high pressure, thereby forming mist.
• Such mist is injected at high speed, and thus sprayed at high speed onto the surface of the strip 33, cooling down the strip 33 quickly. Through such a cooling process, the heat-treated strip 33 can be sufficiently cooled down in a short time, thereby producing a structure of desired metallic phase.
• the hot rolled strip or plate undergoes phase transformation, finally achieving desired mechanical properties. That is, the ROT or ACC cools down a hot metallic material to discharge it at a low or moderate temperature, in which the metallic material is transformed from paramagnetic austenite to ferromagnetic ferrite. Through such phase transformation, mechanical properties of the metallic material are determined.
• the cooling heat treatment of steel making process is carried out in an extremely hostile environment. That is, an inside cooling unit sprays water in the form of laminar flow, which is then vaporized, and a hot rolled metal strip transported at a high speed (e.g., in the range from 700 mpm to 1,200 mpm) generates vibration.
• a high speed e.g., in the range from 700 mpm to 1,200 mpm
• any measuring instrument is not operated, and thus it is difficult to directly measure temperature and transformation in the process of ROT or ACC.
• the transformation of the metal strip has been estimated through temperature detection merely after the metal strip has passed through the cooling heat treatment and the cooling is finished.
• the cooling unit operated in the cooling heat treatment should ultimately control the degree of transformation rather than temperature, and thus measurement on the degree of transformation is inevitably demanded in the cooling heat treatment.
• Conventional measuring methods for transformation include a temperature measuring method, an X-ray diffraction method, an eddy current measuring method and so on.
• the temperature measuring method can detect phase transformation only indirectly, and thus acquire schematic information. Furthermore, it has drawbacks such as slow response time, poor precision and poor measuring performance with a radiation thermometer in a water-cooling environment.
• the eddy current method may provide precise measurement in a laboratory environment.
• this method is very sensitive to lift-off, i.e., the distance between the metallic material to be measured and an eddy current sensor, and thus can hardly acquire reliable results from actual working environment with various vibrations.
• Korean Utility Model Application No. 1995-20346 discloses a technique for measuring the degree of transformation by detecting a magnetic flux formed through energization to different frequency bands, outputting an electromotive signal based on the magnetic flux, filtering the electromotive signal with different band filters, and analyzing the filtered signal.
• Korean Patent Application No. 1996-41353 discloses a technique for measuring transformation rate by deciding the fraction of each phase based on X-ray diffraction analysis which is used to analyze the crystal structure.
• Korean Patent Application No. 1996-51639 discloses a technique for acquiring permeability by using a lift-off value, and then calculating the degree of transformation based on the permeability.
• 1996-67984 discloses a technique for measuring transformation rate by acquiring only the maximum value of a measurement voltage signal such as unit time.
• Japanese Patent Application Publication No. Hei 05-126798 discloses a system for measuring the degree of transformation by forcibly magnetizing a metallic material and then detecting the magnetic variation of the magnetized metallic material.
• these techniques need a systems to have a complicated structure, are rarely applicable to an extremely hostile environment such as ROT and ACC, and especially, and are inefficient to precisely measure the degree of transformation on a hot metallic material which is transported at a high speed.
• the present invention has been made to solve the foregoing problems of the prior art and therefore an object of certain embodiments of the present invention is to provide an on-line measuring system for the degree of transformation on a metallic material that would take place during cooling heat treatment that cools down the metallic material after hot rolling.
• Another object of certain embodiments of the invention is to provide an on-line measuring system for the degree of transformation on a metallic material which has a simple structure as well as excellent applicability in a case where the metallic material is transported at a high speed (e.g., in the range from 700 mpm to 1,200 mpm).
• an on-line measuring system for the degree of transformation on a hot metallic material moving in a cooling heat treatment which cools down the metallic material, comprising: a U-shaped yoke member having both ends extending toward but spaced from the metallic material and an opening formed on a surface thereof; first and second magnetic members arranged at both ends of the yoke member, respectively; a magnetic flux sensor for detecting a leakage magnetic flux leaking at the opening from a magnetic flux formed by the first and second magnetic members and flowing along a magnetic circuit composed of the first magnetic member, the metallic material, the second magnetic member and the yoke member; and an analyzer for measuring the degree of transformation on the metallic material according to the intensity of the detected leakage magnetic flux by using a preset relationship between the degree of transformation on the metallic material and a leakage magnetic flux intensity.
• the opening is extended from the surface of the yoke member to a depth that is 10 % to 30 %
• an on-line measuring system for the degree of transformation on a hot metallic material moving in a cooling heat treatment which cools down the metallic material comprising: a U-shaped yoke member having both ends extending toward but spaced from the metallic material and a slit formed to a predetermined depth from a surface thereof; first and second magnetic members arranged at both ends of the yoke member, respectively; at least one magnetic flux sensor arranged inside the slit, the sensor detecting the intensity of a leakage magnetic flux passing across the slit from a magnetic flux flowing along a magnetic circuit composed of the first magnetic member, the metallic material, the second magnetic member and the yoke member; and an analyzer for measuring the degree of transformation on the metallic material according to the intensity of the detected magnetic flux by using a preset relationship between the degree of transformation on the metallic material and a leakage magnetic flux intensity.
• the on-line measuring system may further comprise first and second metal members each for forming a magnetic path between each of the first and second magnetic members and the metallic material, wherein the magnetic flux sensor is adapted to detect the magnetic flux passing across the slit from the magnetic flux flowing along a magnetic circuit composed of the first magnetic member, the first metal member, the metallic material, the second metal member, the second magnetic member and the yoke member.
• the first and second metal members comprise a wire brush.
• the first and second metal members are preferably attached to outer portions of a housing corresponding to the both ends of the yoke member.
• the depth of the slit is 20 % to 80 % of the total depth of the yoke member.
• the on-line measuring system may further comprise a tube having a predetermined diameter arranged inside a housing, and a refrigerant is flown through the tube to perform cooling, in which the tube is arranged preferably to wind at least a portion of the yoke member including the slit.
• the on-line measuring system may further comprise a housing having an inner space containing a refrigerant therein, wherein the yoke member, the first and second magnetic members and the magnetic flux sensor are arranged inside the inner space of the housing.
• the refrigerant comprises one selected from a group consisting of cooling oil, cooling water and cooling gas.
• the housing may have an inlet pipe for introducing the refrigerant from outside and an outlet pipe for discharging the refrigerant to outside.
• an on-line measuring system for the degree of transformation on a hot metallic material moving in a cooling heat treatment which cools down the metallic material, comprising: a cylinder member having an inner space, the cylinder member being rotatable with outer surface in contact with the metallic material; a U-shaped yoke member having both ends extending toward an inner periphery of the cylinder member and an opening formed on a surface thereof; first and second magnetic members each having one end attached to each of the ends of the yoke member and the other end attached to an inner surface of the cylinder member; a magnetic flux sensor for detecting a leakage magnetic flux leaking at the opening from a magnetic flux formed by the first and second magnetic members and flowing along a magnetic circuit composed of the first magnetic member, the metallic material, the second magnetic member and the yoke member; and an analyzer for measuring the degree of transformation on the metallic material according to the intensity of the detected leakage magnetic flux by using a preset
• the opening is extended from the surface of the yoke member to a depth that is 10 % to 30 % of the total depth of the yoke member.
• the on-line measuring system may further comprise a plurality of the yoke member arranged in a width direction of the metallic material inside the inner space, wherein a plurality of the first and second magnetic members and a plurality of the magnetic flux sensor are attached to the yoke members, whereby the analyzer is adapted to calculate the degree of transformation on the metallic material according to magnetic flux intensities detected by the magnetic flux sensors.
• an on-line measuring system for the degree of transformation on a hot metallic material moving in a cooling heat treatment which cools down the metallic material, comprising: a cylinder member having an inner space, the cylinder member being rotatable with outer surface in contact with the metallic material; a U-shaped yoke member having both ends extending toward an inner periphery of the cylinder member and a slit formed to a predetermined depth from a surface thereof; first and second magnetic members each having one end attached to each of the ends of the yoke member and the other end attached to an inner surface of the cylinder member; at least one magnetic flux sensor arranged inside the slit, the sensor detecting the intensity of a leakage magnetic flux passing across the slit from a magnetic flux formed by the first and second magnetic members and flowing along a magnetic circuit composed of the first magnetic member, the metallic material, the second magnetic member and the yoke member; and an analyzer for measuring the degree
• the on-line measuring system may further comprise first and second ferromagnetic members each for forming a magnetic path between each of the first and second magnetic members and an inner surface of the cylinder member, wherein the magnetic flux sensor is adapted to detect the magnetic flux passing across the slit from the magnetic flux flowing along a magnetic circuit composed of the first magnetic member, the first ferromagnetic member, the metallic material, the second ferromagnetic member, the second magnetic member and the yoke member.
• the first and second ferromagnetic members are integrated with the yoke member and the first and second magnetic members.
• the on-line measuring system may further comprise a plurality of the yoke member arranged in a width direction of the metallic material inside the inner space, wherein a plurality of the first and second magnetic members and a plurality of the magnetic flux sensor are attached to the yoke members, whereby the analyzer is adapted to calculate the degree of transformation on the metallic material according to magnetic flux intensities detected by the magnetic flux sensors.
• the depth of the slit is 20 % to 80 % of the total depth of the yoke member.
• an on-line measuring system for the degree of transformation on a hot metallic material moving in a cooling heat treatment which cools down the metallic material, comprising: a cylinder member having an inner space, the cylinder member being rotatable with outer surface in contact with the metallic material; a U-shaped yoke member having both ends each attached to an inner surface of the cylinder member, the yoke member forming a magnetic path with the metallic material; first and second magnetic members each inserted into a portion of the yoke member, each of the magnetic members generating a magnetic flux to form the magnetic path through the yoke member; at least one magnetic flux sensor inserted into a different portion of the yoke member, the sensor detecting the intensity of the magnetic flux formed by the first and second magnetic members and flowing along a magnetic circuit composed of the first magnetic member, the metallic material, the second magnetic member and the yoke member; and an analyzer for measuring the degree of transformation on the
• the cylinder member preferably comprises a non-magnetic material.
• the cylinder member contains refrigerant therein.
• the refrigerant may comprise one selected from a group consisting of cooling oil, cooling water and cooling gas.
• the first and second magnetic members preferably comprises a Sm or Nb based permanent magnet
• the magnetic flux sensor preferably comprises a Hall element
• FIG. 1 is a process diagram illustrating a general hot rolling system
• FIG. 2 is a schematic configuration view illustrating a general ROT in a hot rolling system
• FIG. 3 is a schematic configuration view illustrating a general ACC in a hot rolling system
• FIG. 4 is a graph illustrating phase transformation and magnetic property change during cooling heat treatment according to the invention
• FIG. 5 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a first embodiment of the invention
• FIG. 6 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a second embodiment of the invention
• FIG. 7 is a detailed view illustrating a slit of the on-line measuring system shown in
• FIG. 6 [55] FIG. 8 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a third embodiment of the invention; [56] FIG. 9 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a fourth embodiment of the invention; [57] FIG. 10 is a view illustrating an exemplary arrangement of a cylinder member shown in FIGS. 8 and 9; [58] FIG. 11 (a) to (d) are views illustrating exemplary yoke members of on-line measuring systems for the degree of transformation on a metallic material according to the first to fourth embodiments of the invention; [59] FIG.
• FIG. 12 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a fifth embodiment of the invention
• FIG. 13 is a perspective view illustrating an exemplary arrangement of a yoke member of the on-line measuring system shown in FIG. 12.
• FIG. 4 is a graph illustrating phase transformation and magnetic property change during cooling heat treatment according to the invention.
• a hot-rolled metallic material such as a strip enters a cooling heat treatment process (e.g.,
• a cooling unit sprays a predetermined amount of cooling water onto top and underside surfaces of the metal strip, thereby cooling the metal strip.
• the metal strip of austenite is hot rolled, followed by high-speed transport to the cooling heat treatment process. In the cooling heat treatment process, the austenite metal strip is cooled down and discharged as ferrite.
• the metal strip right after hot rolling has a temperature of about
• the metal strip is austenite ( phase) with a permeability of 1.
• austenite phase phase
• ferrite phase is paramagnetic with a permeability of 1. That is, as the metal strip is cooled down to a temperature range not exceeding the transformation line A3, it begins to transform from austenite to ferrite.
• the present invention aims to measure the degree of transformation on the metal strip based on the principle that the metal strip shows significant change in magnetic properties (i.e., change in permeability from 1 to 70) during such transformation.
• the degree of transformation increases in proportion to the degree of cooling. This also indicates that the metal strip is more transformed from paramagnetic austenite to ferromagnetic ferrite.
• the lattice structure is transformed from the face-centered cubic structure to the body-centered cubic structure, followed by change in the metallic phase.
• the degree of transformation to ferrite can be calculated according to Equation 1 below:
• Transformation Rate (%) (Volume of phase)/(Volume of Total Metal) 100
• FIG. 5 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a first embodiment of the invention.
• the on-line measuring system 100 for the degree of transformation on a metallic material according to the first embodiment of the invention includes a housing 111 having an inner space, a yoke member 112 arranged in the inner space of the housing 111, first and second magnetic members 115 and 116, a leakage magnetic flux sensor 114 and an analyzer 117.
• the inner space of the housing 111 contains a certain type of refrigerant therein.
• Both ends of the yoke member 112 are extended toward but spaced at a predetermined distance from a metal strip 110, and an opening 113 is formed on the surface of the yoke member 112.
• the first and second magnetic members 115 and 116 are attached to the both ends of the yoke member 112, respectively.
• the leakage magnetic flux sensor 114 detects a leakage magnetic flux 119 that leaks at the opening 113 from a magnetic flux 118 flowing along a magnetic circuit composed of the first magnetic member 115, the metal strip 110, the second magnetic member 116 and the yoke member 112.
• the analyzer 117 analyzes a detection signal on the leakage magnetic flux to measure the degree of transformation on the metal strip 110.
• An inlet pipe 121 for introducing a refrigerant 123 from the outside and an outlet pipe 122 for discharging the refrigerant 123 to the outside are provided in the housing 111.
• the refrigerant 123 introduced through the inlet pipe 121 from the outside cools down the yoke member 112, the magnetic members 115 and 116 and the leakage magnetic flux sensor 114, and then is discharged through the outlet 122 to the outside.
• the refrigerant 123 may include cooling water, cooling gas and cooling oil.
• the magnetic members 115 and 116 may preferably be a typical permanent magnet, and more preferably be a permanent magnet capable of possessing a high energy product while stably working as a magnet at a high temperature.
• the magnetic members 115 and 116 may comprise a Samarium (Sm) or Niobium (Nb) based permanent magnet having a high Curie temperature and large maximum energy product.
• the magnetic members 115 and 116 form a magnetic flux path between the metal strip 110 and the yoke member 112. As shown in FIG. 5, the magnetic members 115 and 116 are lifted off at a predetermined interval from the metal strip 110 inside the housing 111. This makes it possible to perform on-line measurement. While the magnetic members 115 and 116 are arranged inside the housing according to the first embodiment of the invention, the magnetic members 115 and 116 may protrude out of the housing 111 in another embodiment of the invention.
• the leakage magnetic flux sensor 114 preferably includes a Hall element.
• the Hall element is a device using a voltage occurring in a direction perpendicular to a magnetic field and a current in a solid based on Hall effect originating from the interaction between the magnetic field and the current. Since the output of the Hall element is proportional to the product of the magnetic field and the current, the Hall element can be used for a magnetic field meter, a magnetic sensor, various ampere meters, a magnetic head, a microwave wattmeter and so on.
• the yoke member 112 is a substantially U-shaped ferrite member in order to help the magnetic flux path be formed efficiently. While FIG. 5 illustrates the U-shaped yoke member 112 as a preferred embodiment, the yoke member 112 may take any other structure or state that can facilitate the formation of a magnetic flux path.
• the opening 113 is formed with a predetermined size on the surface of the yoke member 112.
• the opening 113 is formed to intentionally leak a part of the magnetic flux formed through the yoke member 112 to the outside.
• the opening 113 is shown formed on the top center of the yoke member 112. However, this is merely an illustration, but the opening 113 can be formed on any portion of the surface of the yoke member 112.
• the opening 113 is not limited in shape, but should have a configuration and size (depth) necessary to leak the magnetic flux out of the magnetic circuit when formed in the yoke 112. If the opening 113 were formed too small, the magnitude of the leakage magnetic flux will be too small and thus the detection of the leakage magnetic flux will have a poor reliability.
• the opening 113 is formed on the surface of the yoke member 112 and extends inward to a depth that is 10% to 30% of the width of the yoke member 112.
• the on-line measuring system 100 for the degree of transformation on a metallic material according to the first embodiment of the invention will be described in more detail.
• the metal strip 110 is transformed from paramagnetic austenite ( phase) to ferromagnetic ferrite ( phase).
• a magnetic circuit is composed of the first and second magnetic members 115 and 116, the metal strip 110 and the yoke member 112, which in turn generates a magnetic flux 118.
• the magnetic flux 118 increases intensity gradually as the metal strip 110 transforms gradually from paramagnetic austenite to ferromagnetic ferrite. This originates from the fact that the value of a magnetic flux is changed in response to magnetic reluctance change when a material transforms in a magnetic circuit, and is substantially identical with the principle that change in the resistance of an electric circuit causes current change.
• the opening 113 formed on the surface of the yoke member 112 allows a part of the magnetic flux 118 formed through the first and second magnetic members 115 and 116, the metal strip and the yoke member 112 to leak out. That is, the magnetic flux 118 flows through the inside and surface of the yoke member 112, but when the opening 113 is formed as shown, leaks in part out of the opening 113. Then, the leakage magnetic flux sensor 114 detects such leakage magnetic flux leaking at the opening 113.
• the magnetic flux 118 is increased in the intensity, which flows along the magnetic circuit composed of the first magnetic member 115, the metal strip 110, the second magnetic member 116 and the yoke member 112, and accordingly, the magnitude of leakage magnetic flux 119 leaking out of the opening 113 increases also. Therefore, when the leakage magnetic flux sensor 114 generates a detection signal upon detecting the leakage magnetic flux 119, the intensity of the detection signal increases gradually in proportion to the transformation of the metal strip 110.
• the analyzer 117 determines the degree of transformation on the metal strip through analysis on a relationship between the intensity of the detected leakage magnetic flux and the degree of transformation.
• the analyzer 117 may be realized as a microprocessor or software, and those skilled in the art may adopt a software to realize the analyzer.
• the analyzer 117 may receive the detection signal from the leakage magnetic flux sensor 114 by wire communication and by wireless communication as well.
• a plurality of the on-line measuring system for the degree of transformation on a metallic material according to the invention may be installed in plural points in the ROT or ACC to measure the degree of transformation on a material at the individual points.
• FIG. 6 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a second embodiment of the invention.
• the on-line measuring system 200 for the degree of transformation on a metallic material according to the second embodiment of the invention includes a housing 211 having an inner space, a yoke member 212 arranged in the inner space of the housing 211, first and second magnetic members 216 and 217, at least one magnetic flux sensor 215 and an analyzer 224.
• the inner space of the housing 211 contains a certain type of refrigerant therein.
• Both ends of he yoke member 212 are extended toward but spaced at a predetermined distance from a metal strip 210, and a slit 213 is formed on the surface of the yoke member 212.
• the first and second magnetic members 216 and 217 are attached to the both ends of the yoke member 212, respectively.
• the magnetic flux sensor 215 is arranged inside the slit 213 to detect a magnetic flux 219 passing across the slit 213 out of a magnetic flux 220 on a magnetic circuit constructed of the first magnetic member 216, a first metal member 218, the metal strip 210, a second metal member 219, the second magnetic member 217 and the yoke member 212.
• the analyzer 270 analyzes a magnetic flux detection signal from the magnetic flux sensor 215 to measure the degree of transformation on the metal strip 210.
• the on-line measuring system 200 for the degree of transformation on a metallic material further includes first and second metal members 218 and 219 each arranged between each of the first and second magnetic members 216 and 217 and the metal strip 210.
• Each of the first and second metal members 218 and 219 is arranged between each of the first and second magnetic members 216 and 217 and the metal strip 210 in order to help a magnetic flux path be effectively formed between each of the first and second magnetic members 216 and 217 and the metal strip 210.
• the magnetic flux path is formed through the first magnetic member 216, the first metal member 218, the metal strip 210, the second metal member 219, the second magnetic member 217 and the yoke member 212, and a magnetic flux is generated on the magnetic flux path.
• the first and second metal members 218 and 219 are preferably a brush having a plurality of steel wires bound together or a roller (not shown) having a circular cross section.
• the first and second metal members 218 and 219 may adopt any other structures that can effectively form a magnetic flux path between each of the first and second magnetic and the metal strip 210.
• the first and second wire brushes or rollers adopt wires of ferromagnetic material, and have a predetermined value of rigidity and elasticity capable of sustaining the weight of the yoke member 112. Furthermore, the first brush or roller is attached to the first magnetic member 216 and the second brush or roller is attached to the second magnetic member 217. The first and second brushes or rollers are configured to contact the metal strip 210 and absorb any bending of the moving metal strip 210 which would be caused from the plate deformation thereof.
• the slit 213 may be formed in any portion of the surface of the yoke member 212.
• FIG. 7 is a detailed view illustrating the slit of the on-line measuring system shown in FIG. 6.
• the slit 213 is formed at a depth D in the yoke member 212.
• the depth D of the slit 213 is preferably in the range from 20 to 80% of the width of the yoke member 212.
• the magnetic flux passes across the slit 213 through a small area, and thus the reliability of magnetic flux detected by the Hall sensor is lowered.
• a board 214 is inserted into the slit 213, and at least one magnetic flux sensor 215 is provided on the board 214.
• the magnetic flux sensor 215 is realized as a Hall sensor that detects the intensity of the magnetic flux based on Hall effect.
• the board 214 is inserted into the slit 213 to be parallel with the inner surface of the slit 213.
• an electric circuit connected to at least one of the magnetic flux sensor 215 is formed on the board 214, and set to transmit an intensity signal detected by the magnetic flux sensor 215 to the analyzer 224.
• the magnetic flux path is formed gradually through the first magnetic member 216, the metal strip 210, the second magnetic member 217 and the yoke member 212.
• the magnetic flux 220 occurs on the magnetic flux path, and its intensity increases gradually as the cooling is carried on, that is, phase transformation proceeds from paramagnetic structure to ferromagnetic structure.
• the magnetic flux 220 occurring on the magnetic circuit flows inside the yoke member 212, and in a case where the deep slit 213 is formed as in the drawing, the magnetic flux 221 passes across the slit 213.
• the magnetic flux 221 leaking from and passing through the slit 213 is detected by the at least one magnetic flux sensor 215. Then, the analyzer 224 determines the degree of transformation on the metal strip 210 through analysis on the relationship between the intensity of the detected magnetic flux and the degree of transformation. In a case where at least two of the magnetic flux sensor 215 are provided, the analyzer 224 calculates an average of the detected magnetic flux intensities, and determines the degree of transformation on the metal strip 210 through analysis on the relationship between the average magnetic flux intensity and the degree of transformation.
• FIG. 8 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a third embodiment of the invention.
• the on-line measuring system 300 for the degree of transformation on a metallic material according to the third embodiment of the invention includes a cylinder member 311 having an inner space, a yoke member 312 arranged inside the inner space of the cylindrical member 311, first and second magnetic members 315 and 316, a leakage magnetic flux sensor 314 and an analyzer 317.
• the cylinder member 311 rotates with the outer circumference thereof in contact with the surface of a metal strip 310 that is being transported in the cooling heat treatment.
• Both ends of the yoke member 312 are extended toward but spaced at a predetermined distance from the inner surface of the cylindrical member 311, and an opening 313 is formed on the surface of the yoke member 212.
• the first and second magnetic members 315 and 316 are attached to the both ends of the yoke member 312, respectively.
• the leakage magnetic flux sensor 314 detects a leakage magnetic flux 319 that leaks at the opening 313 out of a magnetic flux 318 flowing along a magnetic circuit composed of the first magnetic member 315, the metal strip 310, the second magnetic member 316 and the yoke member 312.
• the analyzer 317 analyzes a detection signal on the leakage magnetic flux to determine the degree of transformation on the metal strip 310.
• FIG. 9 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a fourth embodiment of the invention.
• the on-line measuring system 400 for the degree of transformation on a metallic material according to the fourth embodiment of the invention includes a cylinder member 411 having an inner space, first and second magnetic members 416 and 417, at least one magnetic flux sensor 415 and an analyzer 419.
• the cylinder member 411 is adapted to rotate with the outer circumference thereof in contact with the surface of a metal strip 410 that is being transported in the cooling heat treatment.
• Both ends of the yoke member 412 are extended toward but spaced at a predetermined distance from the inner surface of the cylindrical member 411, and a slit 413 is formed at a predetermined depth in the surface of the yoke member 212.
• Each of the first and second magnetic members 416 and 417 is attached at one end to one end of the yoke member 412, and at the other end to the inner surface of the cylindrical member 411.
• the magnetic flux sensor 415 detects a magnetic flux that passes across the slit 413 out of a magnetic flux 418 flowing along a magnetic circuit composed of the first magnetic member 416, the metal strip 410, the second magnetic member 417 and the yoke member 412.
• the analyzer 417 determines the degree of transformation on the metal strip 410 based on the intensity of the detected magnetic flux above by using a preset relationship between magnetic flux intensity and the degree of transformation on a metal strip.
• the on-line measuring system 300, 400 for the degree of transformation on a metallic material contacts the hot metal strip 310, 410 after hot rolling to measure the degree of transformation of the metal strip 310, 410, and thus may preferably need a cooling unit for the measuring system.
• the cylinder member 311 and 411 of this invention may contain refrigerant in the inner space.
• the refrigerant serves to cool the yoke member 312, 412, the first and second magnetic members 315 and 316, 416 and 417, and the magnetic flux sensor 314, 415 and so on, and examples thereof may include cooling water, cooling gas, cooling oil and so on.
• the cylinder member 311, 411 is sealed, a tube (not shown) having a predetermined diameter is installed inside the cylinder member, and a specific type of refrigerant (e.g., cooling water, cooling gas and cooling oil) is flown through the tube to perform cooling.
• a specific type of refrigerant e.g., cooling water, cooling gas and cooling oil
• the cooling tube may have any shape and be inserted into any position.
• the tube is preferably arranged to wind at least a portion of the yoke member 312, 412 including the opening 313 or the slit 413 where the magnetic flux sensor 314, 415 sensitive to heat is located.
• the cooling unit can be provided according to the afore-mentioned embodiments.
• FIG. 10 is a perspective view illustrating an exemplary arrangement of the cylinder member of the transformation measuring system according to the third and fourth embodiments of the invention.
• the cylinder member 311, 411 of the transformation measuring system 300, 400 contacts the surface of the metal strip 310, 410 that is transported by a plurality of feed rolls 41 to 43 during the cooling heat treatment, and as the metal strip 310, 410 moves, rotates by friction against the metal strip 310, 410.
• those components for measuring the transformation of the metal strip 310, 410 according to the invention are arranged in the inner space of the cylinder member 311, 411.
• several sets of the components for measuring the transformation of the metal strip according to the invention may be arranged inside the cylinder member 311, 411. More preferably, these sets may be arranged in the width direction of the metal strip 310, 410.
• the cylinder member 311, 411 is preferably made of a non-magnetic material, and more preferably, of austenite based stainless materials. This is because that the stainless materials do not have magnetic influence on the magnetic flux path formed through the first and second magnetic members and the metal strip as shown in FIG. 4. Furthermore, the cylinder member 311, 411 is arranged preferably in the width direction in order to measure the degree of transformation the metal strip 310, 410 across the width thereof.
• a suitable slip ring may be installed in one end of the cylinder member 311, 411 in order to introduce a power lines necessary for the actuation of the magnetic flux sensor 314, 415 and draw out a signal line from the magnetic flux sensor 314, 415.
• the detection signals may be transmitted to the analyzer 317, 419 after first amplification and filtering, if necessary, by a terminal box installed adjacent to the cylinder member 311, 411.
• the analyzer 317, 419 may be realized as a microprocessor or software, and those skilled in the art can realize the analyzer 317, 419 using a certain program. Furthermore, the analyzer 317, 419 may receive the detection signal from the magnetic flux sensor 314, 415 by not only wire communication but also wireless communication.
• a plurality of the on-line measuring system for the degree of trans- formation on a metallic material according to the invention may be installed in a plurality of points in the cylinder member 311, 411 to measure the degree of transformation on a material at the individual points.
• the cylinder member 311, 411 rotates in response to the movement of the metal strip 310, 410.
• the yoke member 312, 412 attached to the inside surface of the cylinder member 311, 411 has both ends directed to the metal strip 310, 410, the flux generated by the first and second magnetic members 314 and 316, 416 and 417 forms a magnetic flux path.
• the intensity of a leakage magnetic flux leaking at the opening 313 or the intensity of a magnetic flux passing across the slit 413 is measured, and based on a relationship between the detected magnetic flux intensity and the degree of transformation, the degree of transformation on the metal strip 310, 410 is measured on-line.
• FIG. 11 (a) to (d) are views illustrating exemplary yoke members of on-line measuring systems for the degree of transformation on a metallic material according to the first to fourth embodiments of the invention.
• both ends of the yoke member 312 may have a shape of a rectangle or fan.
• FIG. 11 (a) to (d) show illustrative examples of the yoke member 312 of the invention, but the yoke member 312 may adopt any shape that allows the degree of transformation on the metal strip to be measured more precisely using the magnetic flux on the magnetic flux path formed through yoke member 312.
• first and second magnetic members 316 and 317 are attached to the inner surface of the cylinder member 311.
• the first and second magnetic members 316 and 317 are suitably configured to have a curvature radius the same as that of the inner surface of the cylinder member 311, and thus can be attached stably and efficiently to the inner surface of the cylinder member 311.
• first and second ferromagnetic members are arranged between the first and second magnetic members 316 and 317 and the inner surface of the cylinder member 311, it is also preferable that the first and second ferromagnetic members are suitably configured to have a curvature radius the same as that of the inner surface of the cylinder member 311.
• the yoke member 312 and the first and second magnetic members 316 and 317 are preferably formed as an integral body. More preferably, the first and second magnetic members 316 and 317 are attached to the yoke member 312 to form the integral body, which has fan-shaped lateral portions. The arc of the fan attached to the inner surface of the cylinder member 311 has a curvature radius the same as that of the latter.
• the yoke member 312, the first and second magnetic members 316 and 317 attached to the yoke member 312 and first and second ferromagnetic members (not shown) each attached to each of the first and second magnetic members 316 and 317 are provided as an integral body. More preferably, the integral body including the yoke member 312, the first and second magnetic members 316 and 317 and the first and second ferromagnetic members (not shown) has fan- shaped lateral portions. The arc of the fan attached to the inner surface of the cylinder member 311 has a curvature radius the same as that of the latter.
• 312 may be exemplified by various shapes, and formed in any points on the surface of the yoke member 312.
• FIG. 12 is a schematic configuration view illustrating an on-line measuring system for the degree of transformation on a metallic material according to a fifth embodiment of the invention.
• the on-line measuring system 500 for the degree of transformation on a metallic material according to the fifth embodiment of the invention includes a cylinder member 511 having an inner space, a U-shaped yoke member 512, first and second magnetic members 516 and 517, at least one magnetic flux sensor 515 and an analyzer 519.
• the cylinder member 511 rotates with the outer surface in contact with a metal strip 510.
• the yoke member 512 has both ends attached to the inner surface of the cylinder member 511, and cooperates with the metal strip 510 to form a magnetic flux path.
• the first and second magnetic members 516 and 517 are inserted into a portion of the yoke member 512, and serve to generate a magnetic flux for forming the magnetic flux path through the yoke member 512.
• the magnetic flux sensor 515 is inserted into another portion of the yoke member, and serves to detect the intensity of a magnetic flux 518 flowing along the magnetic flux path composed of the first magnetic member 516, the yoke member 512, the second magnetic member 517 and the metal strip 510.
• the analyzer 519 analyzes the degree of transformation on the metal strip 510 according to the intensity of the detected magnetic flux by using a preset relationship between a magnetic flux intensity and the degree of transformation on a metal strip.
• the on-line measuring system 500 for the degree of transformation on a metallic material according to the fifth embodiment of the invention as shown in FIG. 5 is compared with the measuring systems 300 and 400 for the degree of transformation on a metallic material as shown in FIGS. 8 and 9, the arrangement of the first and second magnetic members 315 and 315 and of the magnetic flux sensor 315 of the fifth embodiment is more or less different from those of the third and fourth embodiments, but the degree of transformation on the metal strip is measured based on the same principle. Thus, the measuring process will not be described further in detail. That is, in the on-line measuring system 500 for the degree of transformation as shown in FIG.
• the first and second magnetic members 516 and 517 generate the magnetic flux 518, which forms a magnetic flux path 510 along the yoke member 512 and the metal strip 510. Then, the intensity of the magnetic flux is detected by the magnetic flux sensor 515, and based on the detection result of the magnetic flux sensor 515, the analyzer 519 determines the degree of transformation on the metal strip 510 according to the magnetic flux intensity.
• the various embodiments of the invention it is most important for the various embodiments of the invention to arrange the magnetic members such that the magnetic flux path can be efficiently generated between the yoke member and the metal strip and to detect effectively the intensity of the magnetic flux along the magnetic flux path.
• the embodiments of the invention may be realized in various forms in order to efficiently produce the magnetic flux path and to effectively detect the magnetic flux intensity.
• FIG. 13 is a perspective view illustrating an exemplary arrangement of the yoke member of the on-line measuring system shown in FIG. 12.
• both ends each have preferably fan-shaped lateral portions.
• the arc of the fan attached to the inner surface of the cylinder member 511 has a curvature radius the same as that of the latter. In this way, the magnetic flux path can be formed along a closed circuit for a predetermined time period or more during the rotation of the cylinder member 511, and a secure attachment onto the inner periphery of the cylinder member 511 can be made.

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