JP6197811B2 - Steel plate scale remaining judgment device and scale remaining judgment method - Google Patents

Description

  The present invention relates to a remaining scale determination apparatus and a remaining scale determination method for a steel sheet.

  It is well known that in the hot rolling process of steel, a scale which is a kind of oxide film is formed on the surface portion of the steel plate. This scale becomes a cause of various defects in all the steel plates from thin steel plates to thick steel plates, and a scale removal process (descaling) is appropriately performed in the rolling process and the pickling line in the lower process.

  Thick steel plates are appropriately controlled during hot rolling, and controlled rolling is performed to achieve a certain material by adjusting the temperature of the steel plate. In order to prevent them from remaining, descaling is performed before the controlled cooling, in which high-pressure water is sprayed on the plate surface through nozzles to separate and remove the scales. This is because if the cooling becomes non-uniform, it affects the hardness and elongation performance of the surface layer portion, and the uniformity of the material cannot be maintained.

  However, when a descaling failure occurs due to some trouble such as a nozzle failure or insufficient water pressure, a so-called scale residue, in which the scale remains on the thick steel plate, occurs. For this reason, in order to suppress the performance degradation of a thick steel plate, it is calculated | required to determine the presence or absence of a scale remainder.

  As a method for determining the presence or absence of the remaining scale, an optical method of irradiating light on the plate surface and capturing the reflected light with a camera, a visual inspection by a person, or the like is known. Further, when attention is paid to the fact that the scale is a metal oxide as a base material, the electrical conductivity of the scale portion is lower than that of the base material. Similarly to steel plates, copper oxide has a lower electrical conductivity than the base metal, and therefore, in Patent Document 1, the thickness of the copper oxide layer formed on the surface of the copper plate is measured using a probe-type electrical resistance measurement method. The technique of measuring by is disclosed.

JP 2002-62115 A

  By the way, when manufacturing a thick steel plate, a harmless pseudo pattern may occur on the surface of the plate, in addition to the scale, such as when the uneven pattern on the plate surface is formed in a streak shape or simply as a stain. For this reason, the above-described optical technique and visual inspection can find a suspicious scale including the pseudo pattern, but it is difficult to distinguish the scale from the pseudo pattern.

  Further, the scale includes an oxide film having a thickness of about several μm. For this reason, in the method of measuring the thickness of the scale using a laser displacement meter, ultrasonic waves, or the like, it is difficult to detect the scale because the thickness is comparable to the surface roughness.

  Therefore, an attempt was made to determine the scale residue of the thick steel plate by the probe-type electrical resistance measurement method described in Patent Document 1. However, if the technique disclosed in Patent Document 1 is used as it is for determining the remaining scale of a thick steel plate, the relationship between the remaining scale and the electrical resistance value is not always constant, and the remaining scale cannot be determined.

  The present invention has been made in view of the above circumstances, and is a steel plate scale remaining determination device and scale residue that can accurately detect the scale remaining on the surface of the steel plate by a probe-type electrical resistance measurement method. An object is to provide a determination method.

  The steel plate remaining scale determination device according to the present invention has a predetermined current value capable of suppressing the reduction of the scale formed on the steel plate to a plurality of probes that are in contact with the surface of the steel plate to be processed. A current value control means for energizing a current, an electrical resistance calculation means for measuring a voltage between the probes, and measuring an electrical resistance of the steel sheet using the measured voltage and the predetermined current value; and When the electrical resistance value of the steel sheet measured by the electrical resistance calculating means is larger than a predetermined threshold value, the steel sheet has scale remaining determining means for determining that the steel sheet has a scale remaining and fails. It is characterized by.

  In the steel sheet scale remaining determining device, the plurality of probes form channels arranged in a line at predetermined intervals along the longitudinal direction of the steel plate, and the channels are adjacent to each other in the longitudinal direction. It is preferred that the needles are electrically coupled.

  In the steel sheet scale remaining determining device, a plurality of the channels are arranged at predetermined intervals in the width direction of the steel plate, and the current value control means is configured to perform a current division of the predetermined current value for each channel in a time-sharing manner. The electrical resistance calculation means measures the electrical resistance value for each channel, and the scale remaining judgment means judges that the channel is rejected for each channel when the electrical resistance value is larger than the predetermined threshold value. It is preferable to do.

  In the steel sheet scale remaining determination device, the scale remaining determining means determines that the scale width is rejected when both of the two channels adjacent in the width direction are determined to be rejected. Is preferred.

  In the steel sheet scale remaining determination device, it is preferable that the probe has a width-direction interval of the steel plate set to be equal to or less than half of a scale width to be determined as failure.

  In the steel sheet scale remaining determination device, the predetermined current value is preferably a value included in a range of 1 μA to 100 μA.

  The method for determining the remaining scale of a steel sheet according to the present invention has a predetermined current value capable of suppressing the reduction of the scale formed on the steel sheet to a plurality of probes that are in contact with the surface of the steel sheet to be processed. A current value control step of supplying a current; an electric resistance calculation step of measuring a voltage between the probes; and measuring an electric resistance of a steel sheet using the measured voltage and the predetermined current value; When the electrical resistance value of the steel sheet measured by the resistance calculating step is larger than a predetermined threshold value, the steel sheet includes a scale remaining determining step that determines that the steel sheet has a scale remaining and fails. To do.

  In the steel sheet scale remaining judgment method, the current value control step includes arranging the plurality of probes in a line at a predetermined interval along the longitudinal direction of the steel plate and electrically connecting adjacent probes in the longitudinal direction. A current of the predetermined current value is supplied to each of the plurality of channels arranged in a plurality of intervals at predetermined intervals in the width direction in a time-sharing manner for each channel, The resistance calculating step includes a step of measuring the electric resistance value for each channel, and the scale remaining determining step includes a step of determining a failure for each channel when the electric resistance value is larger than the predetermined threshold value. It is preferable to include.

  In the method for determining the remaining scale of the steel sheet, in the remaining scale determining step, if both of the two channels adjacent in the width direction are determined to be rejected, the scale is determined to be rejected with respect to the width of the scale. It is preferable to contain.

  In the steel sheet scale remaining determination method, it is preferable that the current value control step includes a step of controlling the predetermined current value to a value included in a range of 1 μ to 100 μA.

  According to the present invention, a scale generated on the surface of a steel sheet can be detected with high accuracy by a probe-type electric resistance measurement method. In addition, when measuring the electrical resistance value of the steel sheet, it is controlled to a predetermined current value that suppresses the reduction phenomenon that occurs on the oxide scale, so that the reduction reaction proceeds and the electrical resistance difference between the scale and the steel sheet can be suppressed. . Therefore, it is possible to measure the electrical resistance value caused by the scale, and it is possible to improve the determination accuracy of the remaining scale by determining that there is a remaining scale when the electrical resistance value exceeds a predetermined threshold value.

FIG. 1 is a flowchart showing a remaining scale determination process flow for a steel sheet in the present embodiment. FIG. 2 is a diagram schematically illustrating a steel sheet scale remaining determination device according to the present embodiment. FIG. 3 is a skeleton diagram showing an arrangement example of a plurality of probes. FIG. 4A is a side view showing the probe head viewed from the direction of arrow A shown in FIG. FIG. 4B is a front view showing the probe head viewed from the direction of arrow B shown in FIG. FIG. 5 is a model diagram schematically showing the test apparatus. FIG. 6 is a line graph showing an example of the test result.

  Hereinafter, with reference to the drawings, a steel sheet scale remaining determination device according to an embodiment of the present invention will be described in detail.

  FIG. 2 is a schematic diagram showing a steel sheet scale remaining determination device in the present embodiment. FIG. 3 is a skeleton diagram showing an arrangement example of a plurality of probes. As shown in FIG. 2, a steel sheet scale remaining determination device (hereinafter simply referred to as “determination device”) 1 includes a measuring device 3 that measures an electrical resistance value R of a thick steel plate 2 to be processed, and a lead wire 4. And a plurality of probes 5 electrically connected to the measuring device 3 and a probe head 6 from which the plurality of probes 5 protrude from the opposite side facing the plate surface 2a of the thick steel plate 2. It is configured.

  The determination device 1 detects the scale S present on the plate surface 2a by a probe-type electric resistance measurement method. That is, the electrical resistance value R of the thick steel plate 2 is measured by passing a current of a predetermined current value Ia through the thick steel plate 2 in a state where the tips 5 are in contact with the plate surface 2a. The electronic control unit 10 provided in the device 3 determines the presence or absence of the scale S. Details of the electronic control unit 10 will be described later.

As shown in FIG. 3, the scale S has a streak shape extending in the longitudinal direction of the thick steel plate 2. This is because the scale (oxide film) generated on the thick steel plate 2 in the hot rolling process remains on the plate surface 2a due to a descaling failure or the like. The main component of the scale S is magnetite (Fe ₃ O ₄ ).

  As an example of descaling, high-pressure water is sprayed from a plurality of nozzles arranged in the width direction of the thick steel plate 2 toward the plate surface 2a while passing the thick steel plate 2 through the production line, and the scale is changed from the plate surface 2a. It may be peeled off and removed. In that case, when a failure occurs in any one of the nozzles arranged side by side, the scale S is generated at the same position in the width direction on the plate surface 2a. Therefore, the scale S has a width (scale width) W and extends in a streak shape along the longitudinal direction (through plate direction) of the thick steel plate 2. The descaling failure occurs due to various factors such as movement of the plate surface 2a to a position (height) where high-pressure water does not reach due to flapping of the thick steel plate 2 in the plate, and insufficient water pressure. That is, the scale width W may be not constant, thick, or narrow. The scale width W may be as large as about 200 mm.

  Therefore, the probe head 6 is provided with 20 rows of six probes 5a, 5b, 5c, 5d, 5e, and 5f arranged in a line in the longitudinal direction in the width direction. All 120 probes 5 are arranged at a distance d in the longitudinal direction and a distance g in the width direction. Thereby, 120 probes 5 can be simultaneously brought into contact with a predetermined area of the plate surface 2a.

  In addition, the six probes 5a, 5b, 5c, 5d, 5e, and 5f form one channel Ch. That is, all 20 channels Ch1 to Ch20 are formed in the probe head 6, and the channels are arranged at a gap g in the width direction. In short, the determination device 1 is configured such that any one of the channels Ch contacts the streak scale S and the six probes 5a and 5b included in one channel Ch with respect to the scale S extending in the longitudinal direction thereof. , 5c, 5d, 5e, and 5f are in contact with each other.

  For example, the longitudinal interval d can be set to 5 mm and the width interval g can be set to 4 mm. In particular, the width direction interval g is set to a size equal to or less than half of the harmful scale width W to be detected by the determination device 1. Assuming that the harmful scale width W desired to be detected is 10 mm, the width direction interval g may be set to 5 mm or less. When such a harmful scale S actually occurs, two channels Ch adjacent in the width direction touch the scale S. In this case, the predetermined area of the plate surface 2a that can be measured at one time by the determination apparatus 1 is 25 mm in length in the longitudinal direction d (= 5 mm) × 5 and 76 mm in width in the width direction g (= 4 mm) × 19. It becomes a square shape.

  Although not shown, the probe 5 has a spring function. The tip of each probe 5 protrudes about 5 mm from the opposing surface of the probe head 6 by the elastic force of the spring. Since each spring contracts by pressing the probe head 6 against the thick steel plate 2 so that the opposing surface is in contact with the plate surface 2a, the tips of all the probes 5 can be brought into contact with the plate surface 2a with certainty. . Furthermore, the method of pressing the facing surface of the probe head 6 against the plate surface 2a may be either manual or automatic. In the case of manual operation, the probe head 6 is provided with a gripping portion such as a rod (not shown). And when a suspicious thing with scale S is discovered in the visual inspection, the traveling of the thick steel plate 2 is stopped, the gripping part of the probe head 6 is grasped, and the suspicious thing with the scale S (including a harmless pseudo pattern). The opposing surface is pressed against the plate surface 2a so as to be positioned at the center of the probe head 6 in the width direction. In the case of automatic operation, the probe head 6 is moved by a servo motor or the like so that the suspicious scale S is located directly below the line, and lowered to press the opposing surface against the plate surface 2a. The electrical resistance value R may be measured after detecting that the steel plate 2 has been contacted by stopping the automatic lowering by attaching a limiter switch to the facing surface. Since it is dangerous for people to approach when the temperature of the thick steel plate 2 exceeds 200 ° C., safety is high in the case of automatic.

  Next, an electric circuit (measurement circuit) for measuring the electric resistance value R of the thick steel plate 2 will be described with reference to FIG. 4A is a side view when the probe head 6 is viewed from the direction of arrow A in FIG. 3, and FIG. 4B is a view when the probe head 6 is viewed from the direction of arrow B in FIG. FIG.

  In the example shown in FIG. 4 (a), a two-terminal measurement circuit including six probes 5a, 5b, 5c, 5d, 5e, and 5f in the first channel Ch1 is formed. In the determination apparatus 1, a single probe 5 is connected to a current source 7 and a voltmeter 8 through a lead wire 4 to serve as a current-carrying probe and a voltage measuring probe. A circuit including the first channel Ch1 is electrically connected to the current source 7 and the voltmeter 8 by the multiplexer 9 provided in the measuring device 3 to form a measuring circuit.

  In the measurement circuit, the current I flowing from the current source 7 flows from the upstream lead wire 4a to the thick steel plate 2 through the first probe 5a, the second probe 5b, and the third probe 5c. Then, a current flows from the energized thick steel plate 2 to the downstream lead wire 4b through the fourth probe 5d, the fifth probe 5e, and the sixth probe 5f and reaches the current source 7. The voltmeter 8 measures a voltage value V between the first to third probes 5a, 5b, and 5c and the fourth to sixth probes 5d, 5e, and 5f.

  Three of the first to third probes 5a, 5b, 5c on the upstream side are electrically coupled by the upstream lead wire 4a. Further, the four fourth to sixth probes 5d, 5e, 5f on the downstream side are electrically coupled by the downstream lead wire 4b. That is, in this measurement circuit, the terminal portion that contacts the thick steel plate 2 is branched on the upstream side and the downstream side of the current source 7, and the branched portion is constituted by one channel Ch.

  For example, there is a possibility that foreign matter such as dust is placed on the plate surface 2 a and happens to be located at the contact point between the probe 5 and the thick steel plate 2. Since the electrical resistance value R increases between the probe 5 and the thick steel plate 2 due to the foreign matter, the two-terminal method consisting of only two probes of the conventional configuration detects the electrical resistance value R increased by the foreign matter. By doing so, it is erroneously determined that there is a remaining scale. According to this determination apparatus 1, since the three probes 5 are electrically coupled, for example, even when foreign matter exists between the second probe 5b and the thick steel plate 2, the other first The electrical resistance value R of the thick steel plate 2 can be measured at a location where no foreign matter is present by the probe 5a and the third probe 5c. As described above, the determination device 1 can suppress erroneous determination due to foreign matter and improve the detection accuracy of the scale S. Furthermore, in the conventional configuration, when an erroneous determination is made due to foreign matter, the electrical resistance value R must be measured again by shifting the contact location between the probe and the thick steel plate. According to this determination apparatus 1, since the three electrically coupled probes 5 are in contact at three different points on the plate surface 2a, the scale S can be detected with a single measurement. . In addition, since the number of lead wires 4 can be reduced in the two-terminal method compared to the four-terminal method, the determination apparatus 1 can be configured in a simple structure.

  As shown in FIG. 4B, in the determination apparatus 1, time division processing is performed while sequentially switching the first to twentieth channels Ch1 to Ch20 by the multiplexer 9, and the electrical resistance value R is calculated for each channel Ch.

  In the example shown in FIG. 4B, the circuit including the first channel Ch <b> 1 becomes a measurement circuit by the multiplexer 9. In this case, circuits other than the first channel Ch1, such as a circuit including the second channel Ch2 and a circuit including the twentieth channel Ch20, are electrically connected from the current source 7 (not shown in FIG. 4B). Blocked.

  For example, in the conventional method for finding the scale S by visual inspection, the scale width W is measured by placing a scale on the plate surface 2a after the scale S is found, thereby reducing the performance of the thick steel plate 2 with respect to the product specifications. It was determined that it was larger than the harmful scale width W. Even if the visual inspection is a process after the thick steel plate 2 is sheared to a predetermined product dimension value, the temperature of the plate surface 2a may exceed 200 ° C., so safety needs to be considered. Therefore, according to the determination device 1, since all the 20 channels Ch1 to Ch20 are provided side by side at the width direction interval g, the presence or absence of the scale S can be determined, and the scale width W is harmful to the scale S. Can be determined. Thereby, the detection process of the scale S can be reduced, and safety can be improved.

  Next, the electronic control unit 10 will be described in detail. The electronic control unit 10 is mainly composed of a microcomputer, and is configured to execute a calculation according to a predetermined program based on input data and data stored in advance. That is, the electrical resistance value R of the thick steel plate 2 is calculated based on data input from the probe head 6 by the electronic control unit 10. The electronic control unit 10 may be connected to a storage device (not shown) so as to be able to transmit and receive data.

  The electronic control unit 10 includes a current value control unit 11, an electrical resistance calculation unit 12, a remaining scale determination unit 13, and a time division processing unit 14. The current value control unit 11 performs control so that a current having a predetermined current value Ia flows from the current source 7. The electrical resistance calculation unit 12 calculates the electrical resistance value R for each channel Ch using the predetermined current value Ia and the voltage value V measured by the voltmeter 8. The remaining scale determination unit 13 determines that there is a remaining scale when the electrical resistance value R calculated by the electrical resistance calculation unit 12 is greater than a predetermined threshold value α for determination. The time division processing unit 14 controls the multiplexer 9 and forms a measurement circuit for each channel Ch by time division processing. For example, the electrical connection is switched to the adjacent channel Ch in the width direction so that the first channel Ch1 is switched to the second channel Ch2, and then the second channel Ch2 is switched to the third channel Ch3. In short, under the control of the time division processing unit 14, the current value control 11 can energize the probe 5 with a current having a predetermined current value Ia by time division for each channel.

  Next, with reference to FIG. 1, the scale remaining determination process flow executed by the determination apparatus 1 will be described. The determination apparatus 1 energizes the plurality of channels Ch with a predetermined current value Ia for each channel Ch by time division under the control of the electronic control unit 10 (step S1). For example, the predetermined current value Ia is set to 10 μA. Further, the voltmeter 8 measures the voltage value V between the probes 5 for each channel Ch, and calculates the electrical resistance value R for each channel Ch based on the predetermined current value Ia and the voltage value V (step S2). .

  The determination apparatus 1 determines whether or not the electrical resistance value R for each channel Ch is larger than a predetermined threshold value α for determination (step S3). This predetermined threshold value α can be set to 500Ω, for example. Step S3 is processing means for determining the presence or absence of the scale S.

  If the negative determination is made in step S3 because the electrical resistance value R is equal to or less than the predetermined threshold value α for determination, this control routine is terminated. In this case, it is determined that there is no scale S in the portion of the plate surface 2a touched by the channel Ch.

  If the electrical resistance value R is greater than the predetermined threshold value α for determination and the determination is positive in step S3, the determination device 1 determines that there is a scale S on the plate surface 2a portion touched by the channel Ch. A pass determination is made (step S4).

In addition, the determination device 1 determines whether or not the two channels Ch _n and Ch _{n + 1} that are adjacent in the width direction have been successively determined to be rejected (step S5). For example, if the electrical resistance value R in the second channel Ch2 exceeds the predetermined threshold value 500Ω and the electrical resistance value R in the third channel Ch3 exceeds the predetermined threshold value 500Ω, a negative determination is made in step S5. This step S5 is a processing means for determining whether or not the width of the scale S is a harmful scale width W having a size over two channels Ch _n and Ch _{n + 1} adjacent in the width direction.

  For example, when the harmful scale width W is set to 10 mm and the width direction gap g between the channels Ch is set to 4 mm, the harmful scale S can be reliably determined by making a positive determination in step S5 described above. It can be detected. The determination device 1 can determine not only the presence / absence of the scale S but also the harmful scale width W.

If the failure determination is negative in step S5 because the failure determination is not continuous for two channels Ch _n and Ch _{n + 1} that are adjacent in the width direction, the control routine ends. In this case, in the thick steel plate 2, the scale S having a harmful scale width W exceeding 10 mm does not exist on the plate surface 2a.

When the failure determination is made positive in step S5 because the failure determination is continued for two channels Ch _n and Ch _{n + 1} adjacent in the width direction, the scale S having a harmful scale width W is the thick steel plate 2. Is determined to be present on the plate surface 2a (step S6). In step S6, a failure determination is made for the scale width W.

  Note that steps S1 to S4 described above may be executed in a time-sharing manner, and a failure determination can be made for each channel Ch. Therefore, the result of the failure determination for the measurement circuit including the first channel Ch1 is temporarily stored in the storage means, and then the storage means is referred to when the determination for the measurement circuit including the second channel Ch2 is made as a failure determination. The determination in step S5 may be performed.

  Furthermore, the determination apparatus 1 may be provided with a notification unit (not shown) for reporting the above-described steps S4 and S6. Information that can be used to identify that the scale S having a harmful scale width W has been detected when affirmative determination is made in step S5 described above, and can be notified from the notification unit, for example, with sound or light. Furthermore, when a negative determination is made in step S3 described above, information indicating that the scale S has been detected may be notified from the notification unit using identifiable information.

  Next, with reference to FIG. 5 and FIG. 6, the results of a test performed for examining the predetermined current value Ia that can determine the presence or absence of the scale S by the two-terminal method will be described. FIG. 5 is a model diagram showing the test apparatus. FIG. 6 is a line graph showing the test results with the horizontal axis representing the current test value Iex and the vertical axis representing the measured electrical resistance value Rex. The solid line shown in FIG. 6 passes through a black dot indicating the measured value Rex at each test value Iex.

  In the thick steel plate 2 for testing, a scale S having a thickness of several μm and a width of several mm is intentionally formed on the plate surface 2a. As shown in FIG. 5, one channel Ch (six probes 5 a to 5 f) is brought into contact with the scale S while the thick steel plate 2 is stopped. A distance d between the probes 5a to 5f in the longitudinal direction is 5 mm. In addition, the surface temperature of the thick steel plate 2 is 200 degrees C or less. Since the test model shown in FIG. 5 has the same configuration as that of the determination apparatus 1 described above, the reference numerals are cited in FIG.

  As the test method, the test current flowing from the current source 7 is set to an arbitrary test value Iex within the test range of 0.001 mA to 1000 mA. That is, the test value Iex is set to an arbitrary fixed value from the minimum value 0.001 mA (1 μA) to the maximum value 1000 mA (1A). And the measured value Rex with respect to each test value Iex is measured with the voltmeter 8. FIG. In this case, the test current is supplied from the first probe 5a, the second probe 5b, and the third probe 5c through the scale S and the thick steel plate 2 to the fourth probe 5d, the fifth probe 5e, and the sixth probe. It flows to 5f. Note that the minimum value of the test Iex can be set to 0.001 mA as a current value that does not receive ambient noise.

  As shown in FIG. 6, when the test value Iex is the minimum value 0.001 mA, the measured value Rex is about 1400Ω, which is the maximum value. When the test value Iex was the maximum value of 1000 mA, the measured value Rex was 0Ω, which was the minimum value. Further, when the test value Iex is near 100 mA, the measured value Rex is almost equal to zero, and becomes zero when the test value Iex exceeds 100 mA.

Here, attention is paid to the graph shape shown by the solid line connecting the black dots in FIG. 6, that is, the change in the measured value Rex with respect to the change in the test value Iex. As the test value Iex increases, the measured value Rex decreases. This is because, as the test value Iex is increased, the reduction phenomenon of magnetite (Fe ₃ O ₄ ), which is the main component of the scale S, is promoted.

  Further, the measured value Rex did not show a constant change with respect to the change of the test value Iex. Specifically, when the test value Iex is in the range from the minimum value 0.001 mA to around 0.1 mA, the measured value Rex changes slowly at about 1250 to 1400Ω. When the test value Iex becomes larger than 0.1 mA, the measured value Rex decreases more rapidly than when the test value Iex is 0.1 mA or less. It can be predicted that the reduction phenomenon of the scale S is promoted when the test value Iex is around 1 mA. When the test value Iex exceeds 100 mA, the measurement value Rex becomes zero despite the presence of the scale S. In short, if an excessive current is applied to the scale S, the scale S is reduced, so that the difference in electrical resistance between the thick steel plate 2 and the scale S becomes small, and it becomes difficult to measure the target electrical resistance value R. .

  From the test result, in the determination apparatus 1, the predetermined current value Ia can be set within a range of 0.001 m to 0.1 mA (1 μ to 100 μA). If a predetermined current value Ia within this range is supplied from the current source 7, it can be predicted that the electrical resistance value R will be within the range of about 1200 to 1400Ω when there is a scale residue on the plate surface 2a. That is, the predetermined current value Ia within the range is a current value that can suppress the reduction of the scale S that is an oxide. Furthermore, as shown in FIG. 6, when the measured value Rex exceeds about 500Ω, the decrease of the measured value Rex becomes gentle, so that the predetermined threshold value α for determination described above can be set to a value near 500Ω.

  The two-terminal method can reduce the number of lead wires 4 compared to the four-terminal method, but is affected by the contact resistance between the probe 5 and the thick steel plate 2 and the electrical resistance of the lead wire 4. Therefore, from the test results shown in FIG. 6, for example, if the energizing current of the current source 7 is set to 10 μA and the predetermined threshold value α for failure determination is set to 500Ω, it is not necessary to consider the influence of the contact resistance and lead wire resistance In addition, the presence or absence of the scale S can be accurately detected by the two-terminal method. In particular, when the electrical resistance value R is measured by a plurality of channels, the two-terminal method can reduce the number of lead wires 4 compared to the four-terminal method, so that the structure of the determination device 1 is complicated and enlarged. Can be suppressed.

  As described above, according to the steel sheet scale remaining determination device of the present embodiment, the scale remaining generated on the surface of the thick steel plate can be detected with high accuracy by a probe-type electrical resistance measurement method. In addition, when measuring the electrical resistance value of a thick steel plate by the probe method, the electrical current difference between the scale residue and the thick steel plate is controlled because the current is controlled to a value that suppresses the reduction phenomenon that occurs in the oxide scale residue. Can be reduced. This makes it possible to accurately determine that a scale residue having a thickness of about several μm exists on the thick steel plate based on the electrical resistance value.

  In addition, since the electrical resistance value is measured in a state where the probe and the thick steel plate are in multipoint contact, even if there is a foreign material between one probe and the surface of the thick steel plate, It is possible to suppress erroneous determination due to the increased electrical resistance value. Furthermore, it is possible to determine the presence or absence of the remaining scale with a single measurement for a predetermined area of the plate surface, and to determine a harmful scale width that can degrade the performance of the thick steel plate.

  Note that the remaining scale determination apparatus and the remaining scale determination method for a steel sheet according to the present invention are not limited to the specific examples described above, and can be appropriately changed without departing from the object of the present invention.

  For example, in the present invention, the number of probes 5 that are electrically coupled is not limited to three, and may be any number as long as it is two or more.

  Moreover, in this invention, you may be comprised so that the scale remainder of a steel plate may be determined by the four terminal method. In the determination apparatus 1 of the four-terminal method, a plurality of probes 5 are electrically coupled exclusively for energization and connected to a current source 7, and a plurality of probes 5 are electrically coupled exclusively for voltage measurement. Connected to the voltmeter 8. In the four-terminal method, the number of lead wires 4 is increased as compared with the two-terminal method, but the probe 5 is not affected by the contact resistance with the thick steel plate 2 or the electrical resistance of the lead wire 4. Therefore, according to the determination apparatus 1 configured by the four-terminal method, it is possible to measure the electric resistance value R with higher accuracy.

  Furthermore, the opposing surface of the probe head 6 and the plate surface 2a may not be in contact with each other, and only the tip of the probe 5 may be in contact with the plate surface 2a. For example, when each probe 5 has a spring function, even if the probe 5 has moved to the inside of the probe head 6 due to the load received from the plate surface 2a, the tip of the probe 5 remains protruding from the opposing surface. You may be comprised so that it may become.

  In addition, in the above-described embodiment, the example in which the measuring device 3 and the probe head 6 are configured separately has been described. However, in the present invention, the measuring device 3 is built in the probe head 6. It may be configured as an integral structure. In the above-described embodiment, the processing target is described as a thick steel plate. However, the present invention is not limited to a thick steel plate, and may be a thin steel plate as long as the processing target is a steel plate.

DESCRIPTION OF SYMBOLS 1 Steel plate scale remaining judgment device 2 Thick steel plate 3 Measuring device 5 Probe 6 Probe head S Scale

Claims (10)

Current value control means for applying a current of a predetermined current value capable of suppressing reduction of the scale formed on the steel plate to a plurality of probes in contact with the surface of the steel plate to be processed;
An electrical resistance calculation means for measuring a voltage between the probes, and measuring an electrical resistance of the steel sheet using the measured voltage and the predetermined current value;
When the electrical resistance value of the steel sheet measured by the electrical resistance calculating means is greater than a predetermined threshold value, the steel sheet includes scale remaining determining means for determining that the steel sheet has a scale remaining and fails. An apparatus for determining the remaining scale of a steel sheet. The plurality of probes form channels arranged in a row at predetermined intervals along the longitudinal direction of the steel plate,
The steel sheet scale remaining determination device according to claim 1, wherein in the channel, the probes adjacent in the longitudinal direction are electrically coupled to each other. A plurality of the channels are arranged at predetermined intervals in the width direction of the steel plate,
The current value control means energizes the current of the predetermined current value in time division for each channel,
The electrical resistance calculation means measures the electrical resistance value for each channel,
The said scale remaining determination means is a scale remaining determination apparatus of the steel plate of Claim 2 which performs failure determination for every said channel, when the said electrical resistance value is larger than the said predetermined threshold value. 4. The scale remaining determination means, when both of the two adjacent channels in the width direction are determined to be unsuccessful, the scale remaining determination means makes a failure determination with respect to the scale width. Steel plate scale remaining judgment device.   5. The scale remaining judgment device for a steel sheet according to claim 1, wherein the probe has a spacing in the width direction of the steel sheet set to half or less of a scale width to be judged as rejected. .   6. The steel sheet scale remaining determination device according to claim 1, wherein the predetermined current value is a value included in a range of 1 μ to 100 μA. A current value control step of energizing a plurality of probes in contact with the surface of the steel plate to be treated with a current of a predetermined current value capable of suppressing reduction of the scale formed on the steel plate; and
An electrical resistance calculation step of measuring a voltage between the probes and measuring an electrical resistance of a steel sheet using the measured voltage and the predetermined current value;
And a remaining scale determining step for determining that the steel sheet has a scale remaining when the electrical resistance value of the steel sheet measured by the electrical resistance calculating step is greater than a predetermined threshold value. A method for determining the remaining scale of a steel sheet. In the current value control step, the plurality of probes are arranged in a line at a predetermined interval along the longitudinal direction of the steel sheet, and a channel electrically connecting the adjacent probes in the longitudinal direction includes: Including a step of energizing the current of the predetermined current value in a time-sharing manner for each channel with respect to a plurality of channels arranged at a predetermined interval in the width direction,
The electrical resistance calculation step includes a step of measuring the electrical resistance value for each channel,
The method of determining a remaining scale of a steel sheet according to claim 7, wherein the remaining scale determining step includes a step of determining a failure for each channel when the electrical resistance value is greater than the predetermined threshold value.   The scale remaining determination step includes a step of determining a failure with respect to the width of the scale when both of the two channels adjacent in the width direction are determined to be failed. The method for determining the remaining scale of the steel sheet according to claim 8.   The method of determining a remaining scale of a steel sheet according to any one of claims 7 to 9, wherein the current value control step includes a step of controlling the predetermined current value to a value included in a range of 1 µ to 100 µA. .

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