WO2022195788A1 - 硬度演算装置、硬度測定システム、硬度演算方法及び硬度演算プログラム - Google Patents
硬度演算装置、硬度測定システム、硬度演算方法及び硬度演算プログラム Download PDFInfo
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- WO2022195788A1 WO2022195788A1 PCT/JP2021/010947 JP2021010947W WO2022195788A1 WO 2022195788 A1 WO2022195788 A1 WO 2022195788A1 JP 2021010947 W JP2021010947 W JP 2021010947W WO 2022195788 A1 WO2022195788 A1 WO 2022195788A1
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- 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
Definitions
- the present invention relates to a hardness calculation device, a hardness measurement system, a hardness calculation method, and a hardness calculation program.
- SSC sulfide stress cracking
- Patent Document 1 As a technique for measuring the hardness of the surface layer of steel, for example, there is a method of roughly estimating the hardness of steel based on multiple electromagnetic properties (Patent Document 1).
- the present invention has been made in view of the circumstances described above, and provides a hardness calculation device, a hardness measurement system, a hardness calculation method, and a hardness calculation program capable of calculating hardness information of an object to be measured with high accuracy. .
- the inventors measured the feature quantities that change depending on the properties of the steel, such as the electromagnetic properties of the surface layer of the steel, under various conditions for various types of steel. As a result, the inventors have found that the feature quantity to be measured depends on the hardness of the surface layer of the steel material, and also depends on the stress state or magnetic force state of the surface layer. In other words, even if the hardness of the surface layer is a predetermined value, the measured feature amount differs if the stress state or the like changes. Even if no external force is applied to the surface layer of the steel material, different residual stresses or residual magnetism can occur depending on the portion due to differences in cooling conditions in the manufacturing process.
- the measured feature amounts differ due to differences in residual stress or residual magnetism.
- the inventors have found that the correlation between the feature amount and the hardness, residual stress, or residual magnetism of the surface layer of the steel differs depending on the type of the feature amount to be measured. Based on these facts, the inventors measure one or more types of feature amounts, and obtain hardness information based on the correlation between each of the one or more types of feature amounts and hardness and residual stress or residual magnetism. I came to the knowledge that I can do it.
- a hardness calculation device relates to hardness at a measurement position based on a detection result of at least one of a current value and a voltage value detected by a detection coil in response to application of a magnetic field to an object to be measured.
- a hardness calculation device for calculating hardness information which is information, in response to application of a first alternating magnetic field having a first frequency and a second alternating magnetic field having a second frequency lower than the first frequency to the object to be measured a feature quantity calculation unit that calculates one or more feature quantities that change with respect to the hardness at the measurement position based on the detection result detected by the method; and based on the one or more feature quantities, the hardness information and a hardness calculation unit that calculates the (2)
- the feature quantity may be a characteristic value that can be calculated based on at least one of current waveform, voltage waveform, magnetic characteristics, and impedance loop.
- the hardness information is the hardness of the surface layer of the measurement object at the measurement position
- the feature quantity is the hardness and residual stress or residual magnetism of the measurement object.
- the hardness calculator has a correlation change region that changes in a correlative manner with respect to each, and the hardness calculation unit calculates the correlation change region in the correlation change region for each of the plurality of feature amounts obtained in advance according to the species to be measured.
- the hardness of the surface layer at the measurement position may be calculated based on the correlation between the feature amount, the hardness of the object to be measured, and at least one of residual stress and residual magnetism.
- the hardness information is the hardness of the surface layer of the measurement object at the measurement position, and the feature amount is a value with respect to residual stress or residual magnetism at the measurement position. may further include a dead band region where is constant.
- the hardness information is whether or not the hardness at the second measurement position changes with respect to the hardness at the first measurement position, and the feature amount is the hardness of the measurement object. and the residual stress or the residual magnetism.
- the hardness information is calculated based on the tendency of change in each of the plurality of feature amounts calculated respectively in each of may include at least two of the feature amounts exhibiting the same trend of change with respect to and exhibit opposite trends of change with respect to change of the other.
- the hardness calculation unit uses a learned model that has learned the correlation between the feature amount and the hardness information to calculate the feature at the measurement position of the measurement target.
- the hardness information may be calculated based on the volume measurements.
- the hardness calculation unit calculates the hardness information based on the plurality of feature values and the chemical components and/or manufacturing conditions to be measured.
- a hardness measurement system includes high-frequency magnetic field applying means for applying a first alternating magnetic field having a first frequency to the object to be measured; A low-frequency magnetic field applying means for applying a second alternating magnetic field having a second low frequency, and detecting a magnetic field from the measurement object obtained when each of the first alternating magnetic field and the second alternating magnetic field is applied.
- a detection coil, detection means for detecting at least one of a current value or a voltage value flowing through the detection coil, and the hardness calculation device according to any one of (1) to (7) above may be provided.
- a hardness calculation method based on a detection result including at least one of a current value and a voltage value detected by a detection coil in response to application of a magnetic field to a measurement object, the hardness at the measurement position.
- a hardness calculation method for calculating hardness information that is information relating to the application of a first alternating magnetic field having a first frequency and a second alternating magnetic field having a second frequency lower than the first frequency to the measurement object calculating one or more feature amounts that change with respect to the hardness at the measurement position based on the detection results detected accordingly, and calculating the hardness information based on one or more of the feature amounts; Including.
- a hardness calculation program calculates the hardness at a measurement position based on a detection result including at least one of a current value and a voltage value detected by a detection coil in response to application of a magnetic field to an object to be measured.
- a hardness calculation program for calculating hardness information which is information about A feature quantity calculation means for calculating one or more feature quantities that change with respect to the hardness at the measurement position based on the detection result detected in response to the application of the hardness, based on the feature quantity, It functions as hardness information means for calculating information.
- a hardness calculation device capable of calculating hardness information of an object to be measured with high accuracy.
- FIG. 1 is a schematic diagram showing a hardness measurement system
- FIG. FIG. 3 is an explanatory diagram showing a BH loop and feature quantities showing the relationship between magnetic field intensity and magnetic flux density
- FIG. 4 is an explanatory diagram showing detected current waveforms and feature quantities
- FIG. 4 is an explanatory diagram showing detected voltage waveforms and feature amounts
- FIG. 4 is an explanatory diagram showing an AC voltage waveform to be applied
- FIG. 4 is an explanatory diagram showing distortion represented by an amplitude normalized by a fundamental wave based on a detected current waveform
- FIG. 10 is an explanatory diagram showing the maximum amplitude and minimum amplitude of amplitude represented by the distance from the origin in the impedance loop of the impedance complex plane
- FIG. 4 is an explanatory diagram showing the impedance loop width at 3% reduction of the maximum amplitude and the impedance loop width at 10% reduction of the maximum amplitude in the impedance loop of the impedance complex plane;
- FIG. 4 is an explanatory diagram showing maximum phases and minimum phases in an impedance loop on an impedance complex plane; Maximum incremental permeability in relationship between voltage and incremental permeability, average incremental permeability, incremental permeability at zero external magnetic field, magnetizing voltage at maximum incremental permeability, magnetizing voltage at maximum incremental permeability of 75%, maximum increment It is explanatory drawing which shows the asymmetry of the magnetizing voltage at the time of the magnetic permeability of 50%, the magnetizing voltage at the time of the maximum incremental magnetic permeability of 25%, and an incremental magnetic permeability.
- FIG. 2 is a block diagram showing hardware constituting a hardness calculation device
- FIG. FIG. 5 is a diagram showing a pattern having a correlation in which the feature amount increases as the stress of the surface layer of the steel material at the measurement position increases, and the feature amount decreases as the hardness of the surface layer of the steel material at the measurement position increases.
- FIG. 10 is a diagram showing a pattern having a correlation in which the feature amount increases as the stress increases, and the feature amount increases as the hardness increases.
- FIG. 10 is a diagram showing patterns having a correlation in which the feature amount decreases as the stress increases and the feature amount decreases as the hardness increases.
- FIG. 10 is a diagram showing patterns having a correlation in which the feature amount decreases as the stress increases and the feature amount increases as the hardness increases.
- FIG. 10 shows a pattern with .
- the feature value decreases as the stress increases, and the feature value decreases as the hardness increases.
- FIG. 10 shows a pattern with .
- the feature value decreases as the stress increases, and the feature value increases as the hardness increases.
- FIG. 10 is a diagram showing patterns with relationships; In the stress range of tensile stress, there is a dead zone area, and in the stress range other than the dead zone area, the feature value decreases as the stress decreases, and the feature value decreases as the hardness increases.
- FIG. 10 is a diagram showing a pattern;
- FIG. 3 is a block diagram showing functional units that constitute the hardness calculation device;
- FIG. 4 is a flow diagram for explaining a hardness calculation method;
- FIG. 10 is a first determination table showing the relationship between combinations of increases and decreases in two types of feature amounts and the tendency of change (increase and decrease) in stress and hardness;
- FIG. 10 is a second determination table showing the relationship between combinations of increases and decreases in two types of feature amounts and the tendency of change (increase and decrease) in stress and hardness;
- FIG. 11 is a third determination table showing the relationship between combinations of increases and decreases in two types of feature amounts and the tendency of change (increase and decrease) in stress and hardness;
- FIG. 11 is a fourth determination table showing the relationship between combinations of increases and decreases in two types of feature amounts and the tendency of change (increase and decrease) in stress and hardness;
- FIG. FIG. 12 is a block diagram showing the functional configuration of a control unit according to the third embodiment;
- FIG. FIG. 11 is a flow diagram for explaining a method for detecting a hardness change portion according to the third embodiment;
- FIG. 1 is a schematic diagram showing the hardness measurement system of this embodiment.
- the hardness measurement system 1 of the first embodiment calculates hardness information based on a feature quantity measuring device 10 and a feature quantity that varies depending on the properties of the surface layer of an object to be measured (for example, a steel material 101).
- a hardness calculation device 20 is provided. The hardness calculation device 20 calculates hardness information based on the detection result of at least one of the current value and the voltage value detected by the detection coil 15 in response to the application of the magnetic field to the object to be measured.
- the hardness information is information about the hardness at the measurement position of the object to be measured.
- the hardness information may be the hardness of the surface layer of the measurement target (here, the steel material 101) at the measurement position, and whether there is a change (difference) in the hardness at the second measurement position with respect to the hardness at the first measurement position of the measurement target.
- the hardness includes hardness quantified by various tests.
- Vickers hardness by Vickers hardness test For example, Vickers hardness by Vickers hardness test, Brinell hardness by Brinell hardness test, Knoop hardness by Knoop hardness test, Rockwell hardness by Rockwell hardness test, etc. specified by international standards or Japanese Industrial Standards etc. .
- these hardnesses do not need to be values measured by the test method for measuring each hardness, and if the correlation is known in advance, the measured value can be obtained based on the results measured by the rebound tester Alternatively, the measured value obtained in the rebound test itself may be used as an index of hardness.
- An example of measuring the Vickers hardness will be described below. Hereinafter, Vickers hardness is simply referred to as hardness.
- the hardness measurement system 1 includes high-frequency magnetic field applying means (high-frequency excitation coil 112H) for applying a first alternating magnetic field having a first frequency to the object to be measured, and a second magnetic field lower than the first frequency to the object to be measured.
- a low-frequency magnetic field applying means (low-frequency exciting coil 112L) for applying a second alternating magnetic field having a frequency, and a magnetic field from a measurement object obtained when each of the first alternating magnetic field and the second alternating magnetic field is applied is detected. It comprises a detection coil 15 and detection means (for example, an ammeter, a voltmeter, etc., not shown) that detects at least one of a current value and a voltage value flowing through the detection coil 15 .
- the feature amount includes, for example, a feature amount that changes under the influence of the properties of the surface layer of the object to be measured when a magnetic field is applied to the surface layer of the object to be measured, which includes a magnetic material such as the steel material 101 .
- the feature quantity may be a characteristic value that can be calculated based on at least one of current waveform, voltage waveform, magnetic characteristics, and impedance loop.
- the said characteristic amount may be called an electromagnetic characteristic. A case will be described below in which the object of measurement is the steel material 101 and the feature amount is the electromagnetic properties of the surface layer of the steel material 101 .
- the feature quantity measuring device 10 is a device that measures the feature quantity obtained from, for example, a BH loop of a steel material 101 or the like. The feature amount will be described later.
- the BH loop is a magnetic characteristic curve showing the relationship between the strength H of the magnetic field periodically applied to the surface layer of the steel material 101 and the magnetic flux density B generated on the surface layer of the steel material 101 by the applied magnetic field. is.
- the feature amount measuring apparatus 10 includes a magnetizer 11, an oscillator 12, an excitation power supply 13, a magnetic field calculation unit 14, a detection coil 15, a magnetic flux density calculation unit 16, a hysteresis curve calculation unit 17, and a feature calculation unit. a portion 18;
- the magnetizer 11 has a yoke 111 and an excitation coil 112 .
- the excitation coils 112 include a high-frequency excitation coil 112H that applies a first alternating magnetic field having a first frequency to the steel material 101 (measurement object), and a high-frequency excitation coil 112H that applies a first alternating magnetic field having a second frequency lower than the first frequency to the steel material 101 (measurement object). and a low-frequency excitation coil 112L that applies two alternating magnetic fields.
- the high-frequency excitation coil 112H and the low-frequency excitation coil 112L may be separate coils, or may be a single coil.
- the excitation coil 112 may also serve as the detection coil 15, which will be described later.
- the exciting coil 112 can be applied with an alternating current from the exciting power source 13 and can detect the induced current and voltage generated according to the change in the magnetic flux ⁇ .
- the U-shaped yoke 111 has a trunk portion 111b and a pair of iron core portions 111a formed at both ends of the trunk portion 111b.
- the pair of iron core portions 111a are arranged so that their tip surfaces, which are magnetic poles, face the surface of the surface layer of the steel material 101 to be measured.
- the exciting coil 112 is wound around each of the iron core portions 111a.
- the high-frequency excitation coil 112H and the low-frequency excitation coil 112L are separate coils, the high-frequency excitation coil 112H is wound around one iron core portion 111a, and the low-frequency excitation coil 112L is wound around the yoke 111.
- a probe (not shown) may be arranged in the space between the yoke 111 and the steel material 101 without being connected. The arrangement of the high frequency excitation coil 112H and the low frequency excitation coil 112L may be reversed.
- the high-frequency excitation coil 112H and the low-frequency excitation coil 112L are separate coils, either one of them may also serve as the detection coil 15, or both may serve as the detection coil 15 as well.
- the yoke 111 has a strength H depending on the magnitude of the alternating current on the surface layer of the steel material 101 arranged at the position facing the iron core portion 111a by the alternating current flowing through the exciting coil 112. can generate a magnetic field of
- the excitation coil 112 includes the high-frequency excitation coil 112H and the low-frequency excitation coil 112L, it is possible to generate alternating magnetic fields with different frequencies on the surface layer of the object to be measured. Therefore, it is possible to obtain a variety of feature quantities that are the basis for calculation of hardness information and that are highly correlated with hardness information and residual stress or residual magnetism (hereinafter sometimes simply referred to as “stress”). Therefore, hardness information can be calculated with high accuracy.
- the oscillator 12 outputs a signal with a frequency corresponding to the target frequency of the alternating current.
- the oscillator 12 applies a first alternating magnetic field having a first frequency to the steel material 101 and a second alternating magnetic field having a second frequency lower than the first frequency. outputs a sinusoidal signal with a second lower frequency superimposed thereon.
- the oscillator 12 outputs a sinusoidal waveform signal in which a second frequency lower than the first frequency is superimposed on the first frequency, so various current waveforms, voltage waveforms, magnetic characteristics, impedance loops, etc. can be obtained. Based on these, various calculable feature amounts can be obtained, and feature amounts highly correlated with hardness information and stress can be detected. Therefore, hardness can be calculated with high precision.
- the excitation power supply 13 outputs alternating current to the excitation coil 112 according to the frequency of the signal received from the oscillator 12 . Also, the excitation power supply 13 can set the magnitude of the alternating current to be output, that is, the amplitude of the alternating current.
- the magnetic field calculator 14 detects the magnitude of the alternating current output from the exciting power source 13 to the exciting coil 112, and calculates the magnitude of the steel material 101 from the magnitude of the detected alternating current, the previously stored number of turns of the exciting coil 112, and the like.
- the strength H of the magnetic field generated on the surface layer of is calculated.
- the magnetic field calculator 14 outputs the calculated strength H of the magnetic field to the hysteresis curve calculator 17 .
- the detection coil 15 detects magnetic flux ⁇ generated in the steel material 101 .
- the sensing coil 15 may comprise an ammeter or voltmeter that senses the current or voltage in the circuit leading to the sensing coil 15 .
- the ammeter is provided in series with the detection coil 15 .
- a voltmeter is provided in parallel with the detection coil 15 .
- the detection coil 15 is, for example, wound around at least one tip portion of the pair of iron core portions 111a so as to surround the tip surface serving as a magnetic pole.
- the magnetic flux ⁇ generated in the gap between the magnetic pole and the surface of the steel material 101 changes depending on the magnetic field generated by the magnetizer 11 and the state of the surface layer of the steel material 101 .
- the excitation coil 112 may also serve as the detection coil 15 .
- the excitation coil 112 that also serves as the detection coil 15 may be wound singly around either one of the pair of iron core portions 111a. That is, the excitation coil 112 having both the function of applying an alternating magnetic field and the function of detecting an induced current or voltage may be provided independently at the tip of one of the pair of iron core portions 111a.
- the magnetic flux density calculation unit 16 calculates the magnetic flux density B based on the current or voltage detected by the detection coil 15, the number of turns of the detection coil 15 obtained in advance, the cross-sectional area of the detection coil 15, and the like.
- the magnetic flux density calculator 16 outputs the calculated magnetic flux density B to the hysteresis curve calculator 17 .
- the hysteresis curve etc. calculation unit 17 calculates a hysteresis curve etc. (see FIGS. 2A to 2I), such as current waveform, voltage waveform, Compute magnetic properties or impedance loops.
- the hysteresis curve calculation unit 17 calculates the intensity of the magnetic field representing the magnetic characteristics based on the strength H of the magnetic field output from the magnetic field calculation unit 14 and the magnetic flux density B output from the magnetic flux density calculation unit 16, for example.
- a BH loop representing the relationship between the height H and the magnetic flux density B is calculated.
- the hysteresis curve calculation unit 17 calculates a hysteresis curve such as a current waveform, a voltage waveform, and an impedance loop based on the current or voltage detected by the detection coil 15, for example.
- FIGS. 2A to 2I are schematic diagrams of feature amounts.
- 2A to 2I show examples of current waveforms, voltage waveforms, magnetic characteristics, or impedance loops calculated by the hysteresis curve calculating section 17 based on the detected current or voltage.
- FIG. 2A is an explanatory diagram showing a BH loop showing the relationship between magnetic field strength H and magnetic flux density B and characteristic quantities.
- FIG. 2B is an explanatory diagram showing detected current waveforms and feature amounts.
- a curve in which small loops SL which are a plurality of small BH loops corresponding to the first frequency, are superimposed on a large loop LL, which is a large BH loop corresponding to a second frequency lower than the first frequency.
- LL large loop LL
- FIG. 2C is an explanatory diagram showing detected voltage waveforms and feature amounts.
- the maximum magnetization voltage Vmag (V) is obtained from the voltage waveform shown in FIG. 2C.
- FIG. 2D is an explanatory diagram showing an AC voltage waveform to be applied.
- FIG. 2E is an explanatory diagram showing the distortion factor K (%) represented by the amplitude normalized by the fundamental wave based on the detected current waveform.
- A1 indicates the amplitude of the fundamental wave
- A3 indicates the amplitude of the third harmonic
- A5 indicates the amplitude of the fifth harmonic
- A7 indicates the amplitude of the seventh harmonic.
- Figures 2F through 2H plot the high frequency impedance obtained in a local region of the waveform of Figure 2D over one low frequency period.
- FIG. 2F is an explanatory diagram showing the maximum amplitude Zmax( ⁇ ) and the minimum amplitude Zmin( ⁇ ) of the amplitude represented by the distance from the origin in the impedance loop of the impedance complex plane. From FIG.
- FIG. 2F is an explanatory diagram showing the average amplitude Zmean( ⁇ ) obtained by loop-averaging the amplitudes represented by the distance from the origin.
- FIG. 2G is an explanatory diagram showing the impedance loop width W3Z ( ⁇ ) when the maximum amplitude Zmax is decreased by 3% and the impedance loop width W10Z ( ⁇ ) when the maximum amplitude Zmax is decreased by 10% in the impedance loop on the impedance complex plane.
- FIG. 2H is an explanatory diagram showing the maximum phase ⁇ max (rad) and the minimum phase ⁇ min (rad) in the impedance loop of the impedance complex plane. Note that an average phase ⁇ a (rad) obtained by averaging phases in a loop may be derived based on FIG. 2H.
- a characteristic quantity of the surface layer of the steel material 101 to be measured can be obtained from a hysteresis curve or the like, that is, a current waveform, a voltage waveform, a magnetic characteristic or an impedance loop, which is the basis for calculating such a characteristic quantity.
- examples of feature quantities include residual magnetic flux density Br, coercive force Hc, magnetic permeability ⁇ , and the like.
- the residual magnetic flux density Br is the magnetic flux density B at the point R2 at which the magnetic field intensity H is decreased from the point R1 at which the magnetic field intensity H is maximized in the large loop LL to zero.
- the coercive force Hc indicates the strength H of the magnetic field at the point R3 where the direction of the magnetic field is reversed and the magnetic flux density B becomes zero.
- the magnetic permeability ⁇ indicates the slope of the large loop curve at an arbitrary magnetic field strength H, that is, the change rate of the magnetic flux density B change ⁇ B with respect to the magnetic field strength H change ⁇ H.
- the feature quantity is not limited to the residual magnetic flux density Br, the coercive force Hc, and the magnetic permeability ⁇ as long as it is a feature quantity detected according to the change in the strength of the magnetic field.
- the feature amount is, for example, a current waveform, a voltage waveform, a magnetic characteristic, or an impedance loop detected and calculated by the magnetic flux density calculation unit 16. Characteristics that can be calculated based on can be a value.
- the feature amount calculation unit 18 calculates one or more feature amounts that change with respect to the hardness at the measurement position.
- the feature amount calculator 18 may extract a plurality of types of feature amounts from the hysteresis curve such as the BH loop and the impedance loop calculated by the hysteresis curve calculator 17 .
- the feature quantity calculator 18 extracts, for example, the residual magnetic flux density Br and the coercive force Hc from the BH loop.
- the present invention is not limited to this, and instead of the residual magnetic flux density Br or the coercive force Hc, the feature amount calculation unit 18 may detect only one type of other feature amount, and detect two types of feature amounts in different combinations. and may detect three or more types of feature amounts.
- the feature amount calculation unit 18 outputs one or a plurality of extracted feature amounts to the hardness calculation device 20 .
- FIG. 3 is a block diagram showing hardware constituting the hardness calculation device 20 of the first embodiment.
- the hardness calculation device 20 includes a controller 21 including a processor 200 such as a CPU (Central Processing Unit) and a memory 201 connected via a bus.
- the hardness calculation device 20 executes a program.
- the hardness calculation device 20 functions as a device having a control section 21, an output section 22 and a storage section 23 by executing a program. All or part of each function of the hardness calculation device 20 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).
- ASIC Application Specific Integrated Circuit
- PLD Programmable Logic Device
- FPGA Field Programmable Gate Array
- the program may be recorded on a computer-readable recording medium.
- the program may be recorded in memory 201 .
- Computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs and CD-ROMs, and storage devices such as hard disks incorporated in computer systems.
- the program may be transmitted over telecommunications lines.
- the output unit 22 outputs various information.
- the output unit 22 outputs, for example, hardness at an arbitrary position on the surface of the steel material 101 measured by the feature amount measuring device 10 .
- the output unit 22 may acquire the positional information on the steel material 101 and display the positional information and the information on hardness in association with each other. Further, the output unit 22 may visually display information regarding hardness on a plane representing the steel material 101 based on the position information and hardness using numerical values or colors.
- the output unit 22 includes, for example, a display device such as a CRT (Cathode Ray Tube) display, a liquid crystal display, or an organic EL (Electro-Luminescence) display.
- the output unit 22 may be configured as an interface that connects these display devices to its own device.
- the storage unit 23 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device.
- the storage unit 23 stores various information about the feature amount measuring device 10 .
- the storage unit 23 stores, for example, correlations between each of the plurality of types of feature amounts measured by the feature amount measuring device 10 and hardness and stress (for example, patterns shown in FIGS. 4A to 4H, FIGS. 7A to 7D ) is stored. Details of the correlation between the feature quantity, hardness, and stress are shown below.
- FIGS. 4A to 4H are graphs schematically exemplifying patterns of correlations between feature quantities, stress (residual stress or residual magnetism), and hardness used in the hardness calculation device 20 of the first embodiment.
- FIGS. 4A to 4H schematically illustrate the pattern of the correlation between the feature quantity and the residual stress and hardness. The same applies to the schematic examples of patterns of correlation.
- the horizontal axis represents the stress of the surface layer of the steel material in the measured portion
- the vertical axis represents the size of the target feature amount.
- Graphs from FIG. 4A to FIG. 4H show the relationship between the stress and the feature value by changing the hardness.
- FIG. 4A through 4H stress is shown with positive values for tensile stress and negative values for compressive stress.
- Each graph from FIG. 4A to FIG. 4H shows two types of hardness, high hardness indicated by solid line and low hardness indicated by dotted line, but not limited to this, three or more types may be indicated by
- the probability of constants a i and bi used in equation (5 ) described later increases, and the hardness can be estimated with high accuracy.
- the patterns shown in FIGS. 4A, 4B, 4C and 4D show a trend of simple increase or decrease.
- the pattern shown in FIG. 4A has a correlation that the feature amount increases as the stress of the surface layer of the steel material at the measurement position increases, and the feature amount decreases as the hardness of the surface layer of the steel material at the measurement position increases.
- feature quantities that apply to the pattern shown in FIG. 4A include the maximum magnetization voltage Vmag, residual magnetic flux density Br, and the like.
- the pattern shown in FIG. 4B has a correlation that the feature amount increases as the stress increases, and the feature amount increases as the hardness increases. Examples of features that apply to the pattern shown in FIG.
- the pattern shown in FIG. 4B includes the maximum incremental permeability DZmax, the average incremental magnetic permeability DZmean, the incremental magnetic permeability DZr, the average amplitude Zmean, and the maximum amplitude Zmax.
- the pattern shown in FIG. 4C has a correlation that the feature amount decreases as the stress increases and the feature amount decreases as the hardness increases.
- the pattern shown in FIG. 4D has a correlation in which the feature amount decreases as the stress increases and the feature amount increases as the hardness increases. Examples of features that apply to the pattern shown in FIG. 4D are the maximum magnetizing current Imag, the magnetizing voltage Ucdz at the maximum incremental permeability, and the like.
- the patterns shown in FIGS. 4E, 4F, 4G, and 4H show patterns in which the feature amount is substantially constant with respect to stress in a partial stress range.
- the pattern shown in FIG. 4E has a dead zone region (a region in which the feature amount is substantially constant or at the same level even if the stress changes; the same shall apply hereinafter) M1 in a partial stress range that becomes compressive stress.
- M1 a region in which the feature amount is substantially constant or at the same level even if the stress changes; the same shall apply hereinafter
- M1 in a partial stress range that becomes compressive stress.
- the stress range other than the dead zone region M1 there is a correlation that the feature amount increases as the stress increases, and the feature amount increases as the hardness increases. Examples of features that apply to the pattern shown in FIG. There is a width W10Z and the like.
- the pattern shown in FIG. 4F has a dead zone region M in a partial range of compressive stress.
- the feature amount decreases as the stress increases, and the feature amount decreases as the hardness increases.
- Examples of feature amounts that apply to the pattern shown in FIG. 4F include the magnetizing voltage DU75dz at the maximum incremental permeability of 75%, the magnetizing voltage DU50dz at the maximum incremental permeability of 50%, and the magnetizing voltage DU25dz at the maximum incremental permeability of 25%.
- the pattern shown in FIG. 4G has a dead zone region M2 in a partial stress range that becomes compressive stress. In the stress range other than the dead zone region M2, there is a correlation that the feature amount decreases as the stress increases, and the feature amount increases as the hardness increases.
- Examples of feature amounts that apply to the pattern shown in FIG. 4G include average phase ⁇ a, minimum phase ⁇ min, maximum phase ⁇ max, and the like.
- the pattern shown in FIG. 4H has a dead zone region M in the stress range of tensile stress. In the stress range other than the dead zone region M, there is a correlation that the feature amount decreases as the stress decreases, and the feature amount decreases as the hardness increases.
- An example of the feature amount that applies to the pattern shown in FIG. 4H is the minimum amplitude Zmin.
- the pattern of the correlation between the feature quantity and the stress and hardness may differ for each feature quantity (electromagnetic properties). Therefore, it is necessary to confirm the pattern of the correlation between the feature amount and the stress and hardness for each feature amount.
- the pattern of the correlation is not limited to the patterns shown in FIGS. 4A to 4H, and there are various patterns depending on the presence of a range of stresses in which there is no change in the feature amount or at the same level, the degree of inclination, etc. Existing.
- instead of the combination of linear correlations shown in FIGS. 4A to 4H there are cases where there is a curvilinear correlation represented by a quadratic curve, an inversely proportional curve, or the like.
- Equation (3) The correlation between the feature quantity shown in FIGS. 4A to 4H and the stress and hardness is expressed by Equation (3) as follows.
- P i f i ( ⁇ , Hv) (3) however, i: Code indicating the type of each feature quantity f i : Function indicating correlation
- P i Each feature quantity ⁇ : Stress at each position where the feature quantity is measured
- Hv Hardness at each position where the feature quantity was measured
- the feature quantity has a correlation change region N (N1, N2) that changes in a correlative manner with respect to each of the hardness and residual stress or residual magnetism of the object to be measured.
- the correlation change region N is a feature quantity region that monotonically increases or decreases with respect to both the hardness of the object to be measured and the residual stress or residual magnetism of the object to be measured.
- FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D show feature quantities having a correlation change region N that changes in correlation with each of hardness and stress to be measured over the entire area.
- FIG. 4E, FIG. 4F, FIG. 4G and FIG. 4H have a correlation change region N in which the feature amount changes in a correlation with each of the hardness and stress to be measured in a partial region of stress. It shows the feature quantity.
- the stress range shows a different correlation for each stress range.
- formula can be set.
- an equation showing a different correlation for each hardness range may be set with the hardness range as a condition.
- Such a correlation shown for each type of feature quantity can be obtained by preparing standard pieces of the same steel grade with different stress states and hardness in advance and measuring the feature quantity for each.
- the standard piece of the same steel type refers to a steel material having the same composition as the target steel material and having the same thickness and manufactured under the same manufacturing conditions. Details will be described in detail in the preparation process described later.
- Correlation information indicating the correlation for each type of feature amount as described above is stored in the storage unit 23 .
- the storage unit 23 stores correlation information indicating respective correlations of a plurality of types of feature quantities in the form of equations (4) and (5).
- it is not limited to this, and may be stored in the form of formula (3) including relational expressions other than linear expressions, or graphs such as those shown in FIGS. 4A to 4H may be stored in table format It may be configured and stored by a set of numerical values.
- FIG. 5 is a block diagram showing functional units constituting the hardness calculation device 20.
- the control unit 21 has a feature quantity acquisition unit 211 , a correlation acquisition unit 212 and a hardness calculation unit 213 .
- the feature amount acquisition unit 211 acquires a plurality of types of feature amounts output from the feature amount calculation unit 18 for each measurement unit (each measurement at the same measurement position) by the feature amount measurement device 10 .
- the feature quantity acquisition unit 211 acquires the residual magnetic flux density Br and the coercive force Hc.
- the correlation acquisition unit 212 acquires correlation information corresponding to the type of feature amount acquired by the feature amount acquisition unit 211 .
- the hardness calculator 213 calculates hardness information based on one or more feature amounts calculated by the feature amount calculator 18 .
- the hardness calculation unit 213 calculates hardness information based on one or more feature amounts acquired by the feature amount acquisition unit 211 and correlation information acquired by the correlation acquisition unit 212 corresponding to the types of feature amounts. can be calculated.
- the hardness calculation unit 213 calculates hardness information based on the plurality of types of feature amounts acquired by the feature amount acquisition unit 211 and the correlation information acquired by the correlation acquisition unit 212 corresponding to the types of feature amounts.
- the relational expressions relating to these unknowns can be expressed as a plurality of types of features.
- the hardness Hv is obtained from two features, for example, the residual magnetic flux density Br and the coercive force Hc.
- the control unit 21 outputs the calculated hardness Hv to the output unit 22 .
- control unit 21 performs not only the case of acquiring the feature amount from the feature amount measuring device 10 and calculating the hardness, but also the preprocessing for acquiring the feature amount, for example, the process executed by the feature amount calculating unit 18, the history curve
- the processing and the like executed by the equality calculation unit 17 may be collectively executed instead of the feature quantity measuring device 10 .
- the correlation acquisition unit 212 acquires correlation information stratified according to the type of measurement target (for example, steel type) according to the type of measurement target, and the hardness calculation unit measures using the measured feature amount.
- the hardness of the surface layer at the location may be calculated. This makes it possible to eliminate the difference in species to be measured that affects the calculation of hardness.
- the hardness calculation unit 213 may calculate hardness information based on the chemical component to be measured and/or manufacturing conditions in addition to one or more feature amounts. This enables more accurate calculation.
- FIG. 6 shows the flow of the hardness calculation method of the first embodiment.
- the hardness calculation method of the first embodiment is information about the hardness at the measurement position based on the detection result including at least one of the current value and the voltage value detected by the detection coil 15 in response to the application of the magnetic field to the measurement object. It calculates hardness information.
- the hardness calculation method is based on the detection result detected in response to the application of a first alternating magnetic field having a first frequency and a second alternating magnetic field having a second frequency lower than the first frequency to the object to be measured. calculating one or a plurality of feature amounts that change with respect to hardness in and calculating the hardness information based on the one or more feature amounts. As a result, the hardness information of the object to be measured can be calculated with high accuracy.
- the hardness calculation method of the first embodiment includes a preparation step S1, a feature amount measurement step S2, and a hardness acquisition step S3.
- the preparation step S1 includes a standard piece measurement step S11 and a correlation information storage step S12.
- the standard piece measuring step S11 a plurality of standard pieces of the same steel type as the steel material 101 to be measured and having known surface layer stress ⁇ and hardness Hv are prepared with different stress ⁇ or hardness Hv.
- the material from which the standard piece is cut is heated and cooled so that the state of the fine structure is made different.
- the stress state is made different for each of these standard pieces having different hardnesses Hv.
- a standard piece is placed in a testing machine capable of applying an external force to generate a predetermined compressive stress or tensile stress (residual stress).
- each type of feature amount is measured for the surface layer of each prepared standard piece.
- the method of measuring the feature amount is the same as the feature amount measurement step S2, which will be described later, so the description is omitted.
- equations (3), (4), and (5), or the figure Graphs such as those shown in FIGS. 4A to 4H are acquired as correlations between each feature amount, stress, and hardness, which are represented by a set of numerical values in a table format or the like. Furthermore, in the correlation information storage step S12, among the correlations between the acquired feature values and the stress and hardness, the feature value having a correlation in which the amount of change in the feature value with respect to the change in stress is constant for any hardness is selected. Extract.
- the correlation in which the amount of change in the feature amount with respect to the change in stress is constant at any hardness is, for example, the relationships shown in FIGS. 4A, 4B, 4C, and 4D.
- the amount of change in the feature amount with respect to the stress change is constant regardless of the hardness of the steel material. If it is included in the range, it may be extracted as a feature amount having a correlation such that the amount of change in the feature amount with respect to the change in stress is constant at any hardness. Then, in the correlation information storage step S12, the correlation information representing the correlation between the type of the feature amount and the stress or hardness is stored in the storage unit 23 .
- the feature amount of the surface layer is measured at each measurement position on the surface of the steel material 101 to be measured by the feature amount measurement device 10 .
- alternating current is supplied from the excitation power supply 13 to generate a magnetic field including a first alternating magnetic field having a first frequency and a second alternating magnetic field having a second frequency lower than the first frequency.
- the surface of the steel material 101 is scanned with the magnetizer 11 so that the positions of the magnetic pole faces of the magnetizer 11 are different.
- the magnetic flux ⁇ at that time is detected by the detection coil 15 .
- current waveforms, voltage waveforms, magnetic characteristics, hysteresis curves such as impedance loops, and the like shown in FIGS. 2A to 2I are obtained at each measurement position, and feature quantities are obtained.
- the measured feature quantity is output from the feature quantity measurement device 10 to the hardness calculation device 20 .
- a feature amount acquisition step S31 and a hardness calculation step S32 are performed.
- the feature amount acquisition step S ⁇ b>31 the feature amount acquisition unit 211 acquires a plurality of types of feature amounts at each measurement position from the feature amount measurement device 10 .
- the feature quantity at each measurement position that the feature quantity acquisition unit 211 acquires from the feature quantity measurement device 10 may be one (single) as long as it is a pattern that does not change according to changes in stress at any hardness. .
- the feature quantity at each measurement position that the feature quantity acquisition unit 211 acquires from the feature quantity measurement device 10 may be of a plurality of types.
- the plurality of types of feature values acquired here may have a correlation such that the amount of change in the feature value with respect to the change in stress is constant for any hardness.
- residual magnetic flux density Br and coercive force Hc are acquired as characteristic quantities.
- the hardness Hv is calculated based on the plurality of types of feature quantities acquired in the feature quantity acquisition step S31 and the corresponding correlation information acquired in the correlation information storage step S12.
- equations (4) and (5) are expressed as equation (6) below by substituting equation (5) for ⁇ i in equation (4).
- the hardness calculation program of the first embodiment is based on the detection result including at least one of the current value and the voltage value detected by the detection coil in response to the application of the magnetic field to the measurement object. It is a hardness calculation program for calculating information.
- the hardness calculation program causes the computer to detect a first alternating magnetic field having a first frequency and a second alternating magnetic field having a second frequency lower than the first frequency to the object to be measured.
- a hardness calculation program for functioning as feature amount calculation means for calculating one or more feature amounts that change with respect to hardness at a measurement position, and hardness information means for calculating hardness information based on the calculated feature amounts. is. As a result, the hardness information of the object to be measured can be calculated with high accuracy.
- the hardness calculation device 20 the hardness measurement system 1, the hardness calculation method, and the hardness calculation program of the first embodiment, a plurality of types of feature quantities correlated with stress and hardness, respectively, are measured.
- the hardness can be obtained with high accuracy by removing the influence of stress.
- multiple types of feature quantities measured by the feature quantity measurement device 10 are added to the corresponding equations (4) and (5), and a plurality of relational expressions with two unknowns, stress and hardness, are added. can ask. Therefore, the hardness can be obtained with high accuracy by subtracting the stress from these relational expressions.
- the hardness information is the hardness of the surface layer of the measurement target (for example, the steel material 101) at the measurement position.
- the hardness calculation device 20 of the second embodiment applies a first alternating magnetic field having a first frequency and a second frequency lower than the first frequency to the object to be measured, as in the first embodiment.
- a feature amount calculator 18 that calculates one or more feature amounts that change with respect to the hardness at the measurement position based on the detection result detected by the detection coil 15 in response to the application of the second alternating magnetic field.
- the feature quantity includes a dead zone region M (M, M1, M2) whose value is substantially constant with respect to the residual stress or residual magnetism at the measurement position. I'm in.
- the feature quantity has a dead zone region M in which the change in the feature quantity is substantially constant with respect to at least stress or magnetic force, and the stress state (or magnetic force) of the surface layer of the steel material to be measured in the dead band region M state) is included, hardness information can be obtained without being affected by the stress state (or magnetic force state).
- the dead zone region M in which the feature quantity is substantially constant is not limited to the stress range (or the magnetic force range) in which the change in the feature quantity is zero with respect to the change in stress or magnetic force. It also includes a pattern in which the feature amount changes with respect to changes in stress (or magnetic force) within a range that does not affect the pattern. A case where the feature quantity has a dead zone region with respect to stress and the stress is in the dead zone region will be exemplified below.
- Equation (9) the correlation between the feature quantity and hardness is given by Equation (9) as follows.
- P i f i (Hv) (9) however, i: Code indicating the type of feature quantity f i : Function indicating correlation
- P i Feature quantity Hv: Hardness at each position where the feature quantity was measured
- the stress (or magnetic force) variation range ⁇ is represented by the following formula (12). ⁇ P i / ⁇ i (12)
- the predetermined stress range is a range in which the feature amount is substantially constant with respect to the stress. can be determined by the difference ( ⁇ 2 - ⁇ 1 ) between the lower limit ⁇ 1 and the upper limit ⁇ 2 indicating that is equal to or less than ⁇ .
- the hardness calculation device 20 has a selection unit that selects a feature quantity in which the residual stress or residual magnetism at the measurement position is within the dead zone region M.
- the hardness calculation unit 213 of the control unit 21 provided in the hardness calculation device 20 calculates hardness information based on the feature amount selected by the selection unit.
- the hardness calculation device 20 according to the second embodiment includes a selection unit that selects a feature quantity in which the residual stress or residual magnetism at the measurement position is within the dead zone region M.
- the type of feature amount having a dead zone region M in which the value is substantially constant with respect to the residual stress or residual magnetism within a predetermined range that includes the residual stress or residual magnetism of the surface layer of the steel material 101 . Therefore, the hardness can be obtained with high accuracy from the feature quantity selected by the selection unit without depending on the residual stress or residual magnetism variation in the predetermined range.
- the stress adjustment process may be performed before the feature quantity measurement process S2.
- stress is applied to the surface layer of the steel material 101 to be measured to change the stress state.
- the stress adjustment process as a method of applying stress to the surface layer of the steel material 101, for example, the surface of the surface layer of the steel material 101 is subjected to shot blasting. Thereby, a large residual compressive stress can be applied to the surface layer of the steel material 101 compared to the steel material 101 before the stress adjustment process is performed.
- the steel material 101 before the stress adjustment process has a portion in which tensile stress is generated as residual stress and a portion in which compressive stress is generated, the entirety can be put into a state in which compressive stress is generated. .
- the method of applying stress to the surface layer of the steel material 101 is not limited to this. It may apply stress or compressive stress.
- the hardness information is whether or not the hardness at the second measurement position changes with respect to the hardness at the first measurement position.
- the hardness calculation device 20 of the third embodiment has a first alternating magnetic field having a first frequency and a second A feature amount calculator 18 that calculates one or more feature amounts that change with respect to the hardness at the measurement position based on the detection result detected by the detection coil 15 in response to the application of the second alternating magnetic field having a frequency. ing.
- the feature quantity is a correlation change region N (N1, N2 )have.
- the hardness calculation unit 213 provided in the control unit 21 in the hardness calculation device 20 of the third embodiment calculates a plurality of Hardness information is calculated based on the change tendency of each feature amount.
- the plurality of feature quantities calculated by the hardness calculation unit 213 exhibit the same change tendency with respect to changes in either stress or hardness, and are opposite to each other with respect to changes in the other. contains at least two feature quantities that indicate the trend of change in Then, by comparing the measurement results at the two measurement positions for such a combination of two types of feature amounts, and paying attention to what kind of combination of changes results, the hardness between the two measurement positions can be determined. It can be determined whether or not it is a changing part.
- these two features may be a combination of the maximum magnetization voltage Vmag showing the trend shown in FIG. 4A and the maximum incremental magnetic permeability DZmax showing the trend shown in FIG. 4B.
- the maximum magnetizing voltage Vmag and the maximum incremental magnetic permeability DZmax are calculated at each of the first and second measurement positions. Then, between the first measurement position and the second measurement position, when the maximum magnetizing voltage Vmag tends to decrease and the maximum incremental magnetic permeability DZmax tends to increase, for example, a determination table as shown in FIG. 7C Accordingly, it can be determined that there is a portion with high hardness (hardened portion) between the first measurement position and the second measurement position.
- the storage unit 23 stores each of the plurality of types of feature values measured by the feature value measuring device 10, information indicating whether the stress increases or decreases, and information indicating whether the stress increases or decreases.
- a judgment table is stored in which information indicating a trend or a decreasing trend is associated with each other. Details of the feature amount and the determination table are shown below.
- the tendency of feature quantity change with respect to stress change and hardness change that is, whether the feature quantity tends to increase or decrease with increasing stress, or tends to increase with increasing hardness or decreasing trend depends on the type of feature amount.
- the pattern of the correlation between the feature quantity and the stress and hardness may be different for each feature quantity. Therefore, it is necessary to confirm the pattern of the correlation between the feature amount and the stress and hardness for each feature amount.
- FIGS. 7A to 7D are determination tables showing the change tendency (increase/decrease) of stress and hardness for each combination of increase/decrease of two kinds of feature values.
- FIG. 7A to FIG. 7D are determination tables showing the relationship between combinations of two types of increase/decrease in feature amounts and the tendency of change (increase/decrease) in stress and hardness.
- FIG. 7A is a first determination table.
- FIG. 7B is a second determination table.
- FIG. 7C is a third determination table.
- FIG. 7D is a fourth determination table.
- the combination of the two types of feature quantities showing the correlation in FIGS. 4A and 4C that is, both show the same tendency of decreasing with increasing hardness, and increasing with increasing stress
- a combination of two types of feature quantities showing the correlation of FIGS. On the other hand, if both of them show the same tendency of increasing, the range showing the same tendency can be arranged in the determination table shown in FIG. 7C.
- the range showing the same tendency can be arranged in the determination table shown in FIG. 7D.
- a combination of tendencies regarding hardness and stress in two types of feature amounts is used, but a combination of tendencies regarding hardness and stress in three or more types of feature amounts may be used.
- the feature quantity shown in FIG. 4E has a dead zone region M1 and a correlation change region N1.
- the feature amount shown in FIG. 4G has a dead zone region M2 and a correlation change region N2.
- the feature amount shown in FIG. 4G has a dead zone region M2 and a correlation change region N2.
- the feature quantity shown in 4G also increases. Moreover, when the hardness is lowered, the feature amount shown in FIG. 4E is decreased, and the feature amount shown in FIG. 4G is also decreased. On the other hand, when the stress increases, one characteristic amount increases and the other characteristic amount decreases. In this way, two types of stress (either stress or hardness) that show the same tendency with respect to changes in hardness and opposite tendencies with respect to changes in stress (either stress or hardness) By comparing the measurement results at two measurement positions for a combination of feature amounts and paying attention to what kind of combination of changes, the hardness change part, that is, the part where the hardness is high (hardened part) and It can be determined whether or not it is a portion with low hardness (softened portion).
- the hardness calculation device 20 can detect the change tendency of each of the plurality of feature quantities calculated at each of the first measurement position and the second measurement position in the correlation change region N.
- a hardness calculation unit 213 is provided for calculating hardness information based on the above.
- the hardness change at different measurement positions on the object to be measured can be obtained with high accuracy from the calculated feature amount. Therefore, for example, an abnormal portion (position) can be identified from the obtained hardness change using a predetermined threshold value as a criterion, and processing such as cutting the identified abnormal portion can be performed.
- the hardness calculation unit 213 may have a determination table that defines combinations of stress and hardness change tendencies for at least two feature amounts, and presence or absence of hardness changes according to the combinations.
- the hardness calculator 213 may be configured to calculate hardness information based on the determination table. As a result, using the determination table, it is possible to obtain the hardness change at different measurement positions on the object to be measured with high accuracy.
- FIG. 8 is a block diagram showing the functional configuration of the control section 31 of the third embodiment.
- the control unit 31 has a feature quantity acquisition unit 311 , a determination table acquisition unit 312 and a determination unit 313 .
- the feature amount acquisition unit 311 acquires at least two types of feature amounts output from the feature amount calculation unit 18 for each measurement unit (each measurement at the same measurement position) by the feature amount measurement device 10 .
- the feature quantity acquisition unit 311 acquires the residual magnetic flux density Br and the coercive force Hc.
- the determination table acquisition unit 312 acquires a determination table corresponding to the combination of types of feature amounts acquired by the feature amount acquisition unit 311 .
- the determination table shown in FIG. 7A is acquired.
- the determination unit 313 determines the reference measurement position. Determine if the hardness has changed, ie increased or decreased.
- it may be determined whether the stress has changed with respect to the reference measurement position, that is, whether the stress has increased or decreased.
- the reference measurement position may be a predetermined reference position, or the previous measurement position may always be updated as the reference measurement position.
- FIG. 9 is a flowchart for explaining the method of detecting a hardness change portion according to the third embodiment.
- the method for detecting a hardness change portion includes a preparation step S30, a feature amount measurement step S40, and a determination step S50.
- the preparation step S30 includes a standard piece measurement step S301 and a correlation information storage step S302.
- the standard piece measurement step S301 as in the first preparation step of the first and second embodiments, a standard piece of the same steel type as the steel material 101 to be measured and whose surface layer stress ⁇ and hardness Hv are known in advance A plurality of pieces are prepared with different stress ⁇ or hardness Hv.
- each type of feature amount is measured for the surface layer of each prepared standard piece.
- the feature amount measurement method is the same as the feature amount measurement step S2 in the first and second embodiments.
- graphs such as those shown in FIGS. 4A to 4H are converted into numerical values in a table format based on the feature values, stress and hardness of each standard piece obtained in the standard piece measurement step S301. Obtain the correlation between each feature quantity represented by a set or the like and the stress and hardness. Then, based on the sorted correlation results, a determination table as shown in FIGS. 7A to 7D is created.
- the feature amount measurement device 10 measures the feature amount of the surface layer at each measurement position on the surface of the steel material 101, as in the feature amount measurement step S2 of the first and second embodiments.
- a feature amount acquisition step S501 As shown in FIG. 9, in the determination step S50, a feature amount acquisition step S501, a determination table acquisition step S502, and a hardness change determination step S503 are performed.
- the feature amount acquisition step S ⁇ b>501 the feature amount acquisition unit 211 acquires at least two types of feature amounts at each measurement position from the feature amount measurement device 10 .
- residual magnetic flux density Br and coercive force Hc are acquired as characteristic quantities.
- a determination table corresponding to the combination of types of feature amounts acquired in the feature amount acquisition step S501 is acquired from the storage unit 23.
- a hardness change portion is placed at the measurement position based on the feature amount acquired in the feature amount acquisition step S501, the reference value of the feature amount, and the corresponding determination table acquired in the determination table acquisition step S502. determine whether there is Note that the reference value of the feature amount is the reference value of the same type of feature amount as the feature amount acquired in the feature amount acquisition step S501. Note that the reference value of the feature amount is acquired in advance. Then, it is determined whether the feature amount at the measurement position measured with respect to the reference value of the feature amount has increased or decreased. Then, the increase/decrease results for the two types of feature amounts are applied to the determination table. This is compared with the hardness of the standard piece to determine whether the hardness has increased or decreased. The reference value of the feature quantity has a hardness similar to that of the hardness change portion. Therefore, by performing the above determination, it is possible to determine whether or not the measured portion is the hardness change portion.
- the detection target is a hardened part and the determination table shown in FIG. 7A is used as the determination table will be described.
- a standard piece having a hardness equivalent to the hardened portion is prepared.
- the feature amount acquired in the feature amount acquisition step S501 is compared with the measured feature amount of the standard piece. As a result of the comparison, if both the feature amounts (1) and (2) have increased, the site having the feature amount acquired in the feature amount acquisition step S501 is determined to be a hardened part. Similarly, when the comparison result shows that both the feature amounts (1) and (2) have decreased, the site having the feature amount acquired in the feature amount acquisition step S501 is determined not to be a hardened part. The same applies when the detection target is the softened portion.
- a standard piece having hardness corresponding to the softened portion is prepared. Then, the feature amount acquired in the feature amount acquisition step S501 and the feature amount of the standard piece are compared. As a result of the comparison, if both the feature amounts (1) and (2) have increased, it is determined that the part having the feature amount acquired in the feature amount acquisition step S501 is not the softened portion. Similarly, if both the feature amounts (1) and (2) are reduced as a result of the comparison, the part having the feature amount acquired in the feature amount acquisition step S501 is not determined to be the softened portion.
- various feature amounts may be measured while changing the stress state of the standard piece for the surface layer of the standard piece having hardness corresponding to the hardness change portion.
- Various measured feature amounts may be recorded as various reference values.
- the two types of feature quantities are , by showing different trends of the same trend and the opposite trend, in the judgment step, the measurement result measured at the measurement position and the reference value measured in the preparation step are compared to determine whether the same trend or the opposite trend It is possible to determine whether or not the hardness has changed based on whether or not there is a change in hardness, thereby eliminating the influence of the change in stress and detecting the hardness change portion with high accuracy.
- the hardness information is, for example, information that makes it possible to determine whether or not the hardness at the measurement position of the object to be measured is within a specified hardness range.
- the hardness information is not limited to information that enables determination of whether or not the hardness at the measurement position of the object to be measured is within a prescribed hardness range.
- machine learning may be used to find the correlation between the feature amount and the hardness information.
- the hardness calculation unit 213 calculates hardness information based on the measured value of the feature amount at the measurement position of the measurement target using a learned model that has learned the correlation between the feature amount and the hardness information. .
- the hardness calculation unit 213 includes a learning unit (not shown) that performs learning of a learning model using a combination of a feature amount that is an input sample and hardness information that is an output sample as a learning data set.
- the hardness information as an output sample is information that makes it possible to determine whether or not the hardness at the measurement position of the object to be measured is within a specified hardness range.
- the learning data set may be stored in the storage unit 23 .
- the learning unit determines whether the output value from the learning model matches the output sample. Note that if the error between the output value and the output sample is within a predetermined value, it may be determined that they match. If the output value from the learning model does not match the output sample, the above learning process is repeated until the output value from the learning model matches the output sample. Thereby, the learning model can be optimized, and the learning model can be trained to create a trained model. When the output value from the learning model matches the output sample, the hardness calculation unit 213 stores the learned model optimized by learning in the storage unit 23, for example.
- the trained model learns the correlation between feature values and hardness information. Then, when the feature quantity measured at the measurement position of the measurement target is input, the robot is trained to output hardness information corresponding to the feature quantity. Therefore, when the feature amount at the measurement position of the measurement target is input to the learned model, the learned model calculates hardness information at the measurement position of the measurement target having the feature amount. Thereby, hardness information can be calculated with higher accuracy.
- the feature amount that changes depending on the properties of the surface layer of the steel material 101 is not limited to the feature amount of the surface layer of the steel material 101 .
- the hardness measurement system 1 is not limited to calculating hardness.
- the hardness measurement system 1 may measure stress information in addition to hardness information.
- the hardness measurement system 1 may function as a stress measurement system that measures stress information instead of hardness information.
- Hardness measuring system 10 Characteristic quantity measuring device 11 Magnetizer 12 Oscillator 13 Excitation power source 14 Magnetic field calculator 15 Detection coil 16 Magnetic flux density calculator 17 History curve calculator 18 Feature quantity calculator 20 Hardness calculator 101 Steel material 111 Yoke 111a Iron Core portion 111b Body portion 112 Exciting coil 112H High-frequency exciting coil 112L Low-frequency exciting coil 213 Hardness calculator
Abstract
Description
(1)本発明の一態様に係る硬度演算装置は、測定対象に対する磁界の印加に応じて検出コイルで検出される電流値又は電圧値の少なくとも一方の検出結果に基づいて、測定位置における硬度に関する情報である硬度情報を演算する硬度演算装置であって、前記測定対象に第一周波数を有する第一交番磁界及び前記第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出される前記検出結果に基づいて、前記測定位置における硬度に対して変化する1又は複数の特徴量を算出する特徴量算出部と、1又は複数の前記特徴量に基づいて、前記硬度情報を算出する硬度算出部と、を備える。
(2)上記(1)において、前記特徴量は、電流波形、電圧波形、磁気特性又はインピーダンスループの少なくともいずれか1つに基づいて算出可能な特性値であってよい。
(3)上記(1)又は(2)において、前記硬度情報は、前記測定対象の前記測定位置における表層の硬度であり、前記特徴量は、前記測定対象の硬度と残留応力又は残留磁気との各々に対してそれぞれ相関的に変化する相関変化領域を有し、前記硬度算出部は、前記測定対象の種に応じて予め求められた複数の前記特徴量の各々について、前記相関変化領域における前記特徴量と、前記測定対象の硬度と、残留応力又は残留磁気の少なくともいずれか一つとの相関関係に基づいて、前記測定位置における表層の硬度を算出してよい。
(4)上記(1)又は(2)において、前記硬度情報は、前記測定対象の前記測定位置における表層の硬度であり、前記特徴量は、前記測定位置における残留応力又は残留磁気に対して値が一定となる不感帯領域をさらに含んでよい。
(5)上記(1)又は(2)において、前記硬度情報は、第1の測定位置の硬度に対する第2の測定位置の硬度の変化の有無であり、前記特徴量は、前記測定対象の硬度と残留応力又は残留磁気との各々に対してそれぞれ相関的に変化する相関変化領域を有し、前記硬度算出部は、前記相関変化領域における、前記第1の測定位置及び前記第2の測定位置の各々においてそれぞれ算出された複数の前記特徴量の各々の変化傾向に基づいて、前記硬度情報を算出するよう構成されており、複数の前記特徴量は、応力又は硬度のうちいずれか一方の変化に対して互いに同一の変化傾向を示すとともに、いずれか他方の変化に対して互いに逆の変化傾向を示す少なくとも2つの前記特徴量を含んでよい。
(6)上記(1)又は(2)において、前記硬度算出部は、前記特徴量と前記硬度情報との相関関係を学習した学習済みモデルを用いて、前記測定対象の前記測定位置における前記特徴量の測定値に基づいて、前記硬度情報を算出してよい。
(7)上記(1)から(6)のいずれかにおいて、前記硬度算出部は、複数の前記特徴量と、前記測定対象の化学成分及び/又は製造条件とに基づいて、前記硬度情報を算出してよい。
(8)本発明の一態様に係る硬度測定システムは、前記測定対象に第一の周波数を有する第一交番磁界を印加する高周波磁界印加手段と、前記測定対象に、前記第一の周波数よりも低い第二の周波数を有する第二交番磁界を印加する低周波磁界印加手段と、前記第一交番磁界及び前記第二交番磁界の各々を印加したときに得られる前記測定対象からの磁界を検出する検出コイルと、前記検出コイルに流れる電流値又は電圧値の少なくとも一方を検出する検出手段と、上記(1)から(7)のいずれかの硬度演算装置と、を備えてよい。
(9)本発明の一態様に係る硬度演算方法は、測定対象に対する磁界の印加に応じて検出コイルで検出される電流値又は電圧値の少なくとも一方を含む検出結果に基づいて、測定位置における硬度に関する情報である硬度情報を算出する硬度演算方法であって、前記測定対象に第一周波数を有する第一交番磁界及び前記第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出される前記検出結果に基づいて、前記測定位置における硬度に対して変化する1又は複数の特徴量を算出し、1又は複数の前記特徴量に基づいて、前記硬度情報を算出する、ことを含む。
(10)本発明の一態様に係る硬度演算プログラムは、測定対象に対する磁界の印加に応じて検出コイルで検出される電流値又は電圧値の少なくとも一方を含む検出結果に基づいて、測定位置における硬度に関する情報である硬度情報を算出する硬度演算プログラムであって、コンピュータを、前記測定対象に第一周波数を有する第一交番磁界及び前記第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出される前記検出結果に基づいて、前記測定位置における硬度に対して変化する1又は複数の特徴量を算出する特徴量算出手段、及び、前記特徴量に基づいて、前記硬度情報を算出する硬度情報手段として機能させる。
以下、本発明に係る第1実施形態について図1から図8を参照して説明する。図1は本実施形態の硬度測定システムを示す模式図である。
(硬度測定システム)
図1に示すように、第1実施形態の硬度測定システム1は、特徴量測定装置10と、測定対象(例えば、鋼材101)の表層の性状によって変化する特徴量に基づいて硬度情報を演算する硬度演算装置20を備えている。硬度演算装置20は、測定対象に対する磁界の印加に応じて検出コイルで15検出される電流値又は電圧値の少なくとも一方の検出結果に基づいて、硬度情報を演算する。
なお、硬度とは、様々な試験によって定量される硬度を含む。例えば、国際規格又は日本工業規格等で規定された、ビッカース硬さ試験によるビッカース硬度、ブリネル硬さ試験によるブリネル硬度、ヌープ硬さ試験によるヌープ硬度、ロックウェル硬さ試験によるロックウェル硬度等である。また、これらの硬度は、各硬度を測定する試験方法によって測定される値である必要はなく、予め相関関係が分かっていれば、リバウンド式試験機によって測定された結果に基づいて測定値を得てよく、リバウンド式試験で得られる測定値そのものを硬度の指標として用いてよい。以下、ビッカース硬度を測定するものを例として説明する。なお、以下、ビッカース硬度を、単に、硬度と称する。
以下、測定対象を鋼材101とし、上記特徴量が、鋼材101の表層の電磁気特性である場合について説明する。
図1に示すように、特徴量測定装置10は、例えば、鋼材101のBHループ等から得られる特徴量を測定する装置である。特徴量については後述する。なお、BHループとは、鋼材101の表層に周期的に印加される磁界の強さHと、印加された磁界により鋼材101の表層に生じた磁束密度Bとの関係を示す磁気特性曲線のことである。特徴量測定装置10は、磁化器11と、発振器12と、励磁電源13と、磁界演算部14と、検出コイル15と、磁束密度演算部16と、履歴曲線等演算部17と、特徴量算出部18とを備えている。
なお、励磁コイル112は、後述の検出コイル15を兼ねていてよい。この場合、励磁コイル112は、励磁電源13からの交流電流を印加できるとともに、磁束Φの変化に応じて発生する誘導電流及び電圧を検出できる。
U字形状のヨーク111は、胴部111bと、胴部111bの両端に形成された一対の鉄芯部111aとを有している。一対の鉄芯部111aは、磁極となる先端面を測定対象である鋼材101の表層の表面に対向して配される。励磁コイル112は、鉄芯部111aのそれぞれに巻かれている。なお、高周波励磁コイル112H及び低周波励磁コイル112Lが、それぞれ別のコイルである場合、高周波励磁コイル112Hを一方の鉄芯部111aに巻かれた状態にし、低周波励磁コイル112Lをヨーク111に巻かれることなく、ヨーク111と鋼材101との間の空間に配置されるプローブ(不図示)としてよい。高周波励磁コイル112Hと低周波励磁コイル112Lとの配置は、これとは逆であってよい。高周波励磁コイル112H及び低周波励磁コイル112Lが、それぞれ別のコイルである場合、いずれか一方で検出コイル15を兼ねてよく、両方で検出コイル15をかねてもよい。
このような構成により、ヨーク111は、励磁コイル112に交流電流が流れることで、鉄芯部111aと対向する位置に配された鋼材101の表層に、交流電流の大きさに応じた強さHの磁界を発生させることができる。また、励磁コイル112は、高周波励磁コイル112Hと、低周波励磁コイル112Lと、を備えているので、測定対象の表層に、異なる周波数の交番磁界を発生させることができる。よって、硬度情報の演算の基礎となり、硬度情報と、残留応力又は残留磁気(以下、単に、「応力」という場合がある。)との相関性の高い特徴量を多様に取得できる。よって、硬度情報を高精度で演算できる。
検出コイル15は、例えば、一対の鉄芯部111aの少なくとも一方の先端部分に、磁極となる先端面を囲むように巻かれている。磁化器11によって発生する磁界と鋼材101の表層の状態とにより、磁極と鋼材101の表面とのギャップに発生する磁束Φは変化する。そして、検出コイル15には、この磁束Φの時間変化に応じて電磁誘導により電流及び電圧が発生する。
なお、前述のように、検出コイル15は、励磁コイル112で兼ねてよい。この場合、検出コイル15を兼ねた励磁コイル112は、単独で、一対の鉄芯部111aのいずれか一方の先端部分に巻かれていてよい。すなわち、一対の鉄芯部111aのいずれか一方の先端部分に、交番磁界を印加する機能と、誘導電流又は電圧を検出する機能との両方を兼ねた励磁コイル112を、単独で設けてよい。
履歴曲線等演算部17は、例えば、磁界演算部14から出力された磁界の強さHと、磁束密度演算部16から出力された磁束密度Bとに基づいて、磁気特性を表す、磁界の強さHと磁束密度Bとの関係を示すBHループを演算する。また、履歴曲線等演算部17は、例えば、検出コイル15で検出された電流又は電圧に基づいて、電流波形、電圧波形及びインピーダンスループ等の履歴曲線等を演算する。
このような特徴量を演算する基となる履歴曲線等、すなわち、電流波形、電圧波形、磁気特性又はインピーダンスループにより、測定対象である鋼材101の表層の特徴量を得ることができる。
次に、硬度演算装置20について説明する。
図3は、第1実施形態の硬度演算装置20を構成するハードウェアを示すブロック図である。
図3に示すように、硬度演算装置20は、バスで接続されたCPU(Central Processing Unit)等のプロセッサ200とメモリ201とを備える制御部21を備えている。硬度演算装置20は、プログラムを実行する。硬度演算装置20は、プログラムの実行によって制御部21、出力部22及び記憶部23を備える装置として機能する。なお、硬度演算装置20の各機能の全て又は一部は、ASIC(Application Specific Integrated Circuit)やPLD(Programmable Logic Device)やFPGA(Field Programmable Gate Array)等のハードウェアを用いて実現されてよい。プログラムは、コンピュータ読み取り可能な記録媒体に記録されてよい。プログラムは、メモリ201に記録されてよい。コンピュータ読み取り可能な記録媒体とは、例えばフレキシブルディスク、光磁気ディスク、ROM、CD-ROM等の可搬媒体、コンピュータシステムに内蔵されるハードディスク等の記憶装置である。プログラムは、電気通信回線を介して送信されてよい。
図4Aから図4Hまでのグラフは、横軸を測定した部分の鋼材の表層の応力とし、縦軸を対象となる特徴量の大きさとして示している。図4Aから図4Hまでのグラフは、応力と特徴量との関係を、硬度を変えて示している。図4Aから図4Hまでにおいて、応力は、引張応力を正の値とし、圧縮応力を負の値として示されている。図4Aから図4Hまでの各グラフは、硬度の種類を、実線で示された高い硬度及び点線で示された低い硬度の2種類で示しているが、これに限るものではなく、3種類以上で示すものとしてよい。各グラフで示す硬度の種類を増加させることによって、後述する式(5)で用いられる定数ai、biの確からしさが高まり、精度よく硬度を推定することができる。
図4Aに示すパターンは、測定位置における鋼材の表層の応力が大きくなるにつれて特徴量も大きくなり、また、測定位置における鋼材の表層の硬度が高くなるにつれて特徴量は小さくなる相関関係を有している。図4Aに示すパターンに当てはまる特徴量の例としては、最大磁化電圧Vmag、残留磁束密度Br等がある。
図4Bに示すパターンは、応力が大きくなるにつれて特徴量も大きくなり、また、硬度が高くなるにつれて特徴量も大きくなる相関関係を有している。図4Bに示すパターンに当てはまる特徴量の例としては、最大増分透磁率DZmax、平均増分透磁率DZmean、増分透磁率DZr、平均振幅Zmean、最大振幅Zmax等がある。
図4Cに示すパターンは、応力が大きくなるにつれて特徴量は小さくなり、また、硬度が高くなるにつれて特徴量は小さくなる相関関係を有している。
図4Dに示すパターンは、応力が大きくなるにつれて特徴量は小さくなり、また、硬度が高くなるにつれて特徴量も大きくなる相関関係を有している。図4Dに示すパターンに当てはまる特徴量の例としては、最大磁化電流Imag、最大増分透磁率時の磁化電圧Ucdz等がある。
図4Eに示すパターンは、圧縮応力となる一部の応力範囲で、不感帯領域(応力が変化しても特徴量が略一定又は同等レベルである領域。以下同じ。)M1を有している。そして、その不感帯領域M1以外の応力範囲では応力が大きくなるにつれて特徴量も大きくなり、また、硬度が高くなるにつれて特徴量も大きくなる相関関係を有している。図4Eに示すパターンに当てはまる特徴量の例としては、ひずみ率K、3次高調波振幅A3、最大振幅Zmaxの3%減でのインピーダンスループ幅W3Z、最大振幅Zmaxの10%減でのインピーダンスループ幅W10Z等がある。
図4Fに示すパターンは、圧縮応力となる一部の範囲で、不感帯領域Mを有している。そして、その不感帯領域M以外の応力範囲では、応力が大きくなるにつれて特徴量は小さくなり、また、硬度が高くなるにつれて特徴量は小さくなる相関関係を有している。図4Fに示すパターンに当てはまる特徴量の例としては、最大増分透磁率75%時の磁化電圧DU75dz、最大増分透磁率50%時の磁化電圧DU50dz、最大増分透磁率25%時の磁化電圧DU25dz等がある。
図4Gに示すパターンは、圧縮応力となる一部の応力範囲で、不感帯領域M2を有している。そして、その不感帯領域M2以外の応力範囲では、応力が大きくなるにつれて特徴量は小さくなり、また、硬度が高くなるにつれて特徴量も大きくなる相関関係を有している。図4Gに示すパターンに当てはまる特徴量の例としては、平均位相φa、最小位相φmin、最大位相φmax等がある。
図4Hに示すパターンは、引張応力となる応力範囲で、不感帯領域Mを有している。そして、その不感帯領域M以外の応力範囲では、応力が小さくなるにつれて特徴量は小さくなり、また、硬度が高くなるにつれて特徴量は小さくなる相関関係を有している。図4Hに示すパターンに当てはまる特徴量の例としては、最小振幅Zmin等がある。
Pi=fi(σ、Hv) ・・・・・(3)
ただし、
i :各特徴量の種類を示す符号
fi:相関関係を示す関数
Pi:各特徴量
σ:特徴量を各測定位置における応力
Hv:特徴量を測定した各位置における硬度
Pi=αi・σ+βi ・・・・・(4)
βi=ai・Hv+bi ・・・・・(5)
ただし、
i :特徴量の種類を示す符号
Pi:各特徴量
αi、ai、bi:特徴量ごとに求められる定数
σ:特徴量を測定した各位置における応力
Hv:特徴量を測定した各位置における硬度
なお、図4E、図4F、図4G及び図4Hに示すように、応力の範囲によって相関関係が異なる場合には、応力の範囲を条件として、応力の範囲ごとに異なる相関関係を示す式を設定してよい。同様に、硬度の範囲によって相関関係が異なる場合には、硬度の範囲を条件として硬度の範囲ごとに異なる相関関係を示す式を設定してよい。このような特徴量の種類ごとに示される相関関係は、予め同一の鋼種の標準片について、応力状態及び硬度を異なるものを準備し、それぞれについて特徴量を測定することによって得ることができる。ここで、同一の鋼種の標準片とは、対象となる鋼材と成分が同一であって、同一の製造条件で製造された同じ厚さの鋼材をいう。詳細については後述する準備工程で詳細に説明する。以上のような特徴量の種類ごとの相関関係を示す相関情報は、記憶部23に記憶されている。例えば、第1実施形態では、式(4)及び式(5)の形式により、複数種類の特徴量のそれぞれの相関関係を示す相関情報が記憶部23に記憶されている。なお、これに限られず、一次式以外となる関係式も含めて式(3)の形式により記憶されてよく、あるいは、図4Aから図4Hまでに示されるようなグラフをテーブル形式で示された数値の集合により構成し記憶していてよい。
図5は、硬度演算装置20を構成する機能部を示すブロック図である。
図5に示すように、制御部21は、特徴量取得部211と、相関関係取得部212と、硬度算出部213とを有する。
特徴量取得部211は、特徴量測定装置10による測定単位ごと(同一の測定位置での測定ごと)に、特徴量算出部18から出力された複数種類の特徴量を取得する。例えば、特徴量取得部211は、残留磁束密度Brと保磁力Hcとを取得する。
相関関係取得部212は、特徴量取得部211で取得された特徴量の種類と対応した相関情報を取得する。
硬度算出部213は、特徴量算出部18で算出した1又は複数の特徴量に基づいて、硬度情報を算出する。硬度算出部213は、特徴量取得部211で取得された1又は複数の特徴量と、特徴量の種類と対応して相関関係取得部212で取得された相関情報とに基づいて、硬度情報を算出してもよい。硬度算出部213は、特徴量取得部211で取得された複数種類の特徴量と、特徴量の種類と対応して相関関係取得部212で取得された相関情報とに基づいて、硬度情報を算出してもよい。
上記式(3)、又は、式(4)及び式(5)で示されるように、求めるべき未知数が、硬度Hv及び応力σの2つであれば、これら未知数に関する関係式を複数種類の特徴量、例えば、残留磁束密度Brと保磁力Hcの2つの特徴量により、硬度Hvを求める。
制御部21は、求めた硬度Hvを出力部22に出力する。なお、制御部21は、特徴量測定装置10から特徴量を取得して硬度を演算する場合だけでなく、特徴量を取得する前処理、例えば、特徴量算出部18で実行する処理、履歴曲線等演算部17で実行する処理等を、特徴量測定装置10の代わりにまとめて実行してよい。
次に、硬度測定システム1によって実施される第1実施形態の硬度演算方法について説明する。図6は、第1実施形態の硬度演算方法のフローを示している。
硬度演算方法は、測定対象に第一周波数を有する第一交番磁界及び第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出される検出結果に基づいて、測定位置における硬度に対して変化する1又は複数の特徴量を算出し、1又は複数の前記特徴量に基づいて、前記硬度情報を算出することを含んでいる。これにより、測定対象の硬度情報を高い精度で演算できる。
標準片測定工程S11では、測定対象となる鋼材101と同一鋼種であって、予め表層の応力σ及び硬度Hvが既知の標準片を、応力σ又は硬度Hvが異なるようにして複数準備する。各標準片において硬度Hvを異ならせるためには、例えば、標準片を切り出す材料について、加熱及び冷却を実施し、微細な組織の状態を異ならせることで実現できる。このようにして微細な組織の状態を異ならせた複数の標準片について、ビッカース硬さ試験により硬度Hvを測定することで、異なる値で硬度Hvが既知である標準片を得ることができる。これら硬度Hvの異なる標準片それぞれについて、さらに応力状態を異ならせる。応力状態を異ならせる方法としては、例えば外力を加えることが可能な試験機に標準片を設置して、所定の圧縮応力又は引張応力(残留応力)を生じさせることで実現できる。
さらに、相関情報記憶工程S12では、取得した各特徴量と応力及び硬度との相関関係のうち、いずれの硬度においても応力の変化に対する特徴量の変化量が一定となる相関関係を有する特徴量を抽出する。いずれの硬度においても、応力の変化に対する特徴量の変化量が一定となる相関関係とは、例えば、図4A、図4B、図4C及び図4Dに示されるような関係である。なお、図4E、図4F、図4G及び図4Hに示されるような相関関係を有する特徴量であっても、鋼材の応力が、いずれの硬度においても応力の変化に対する特徴量の変化量が一定となる範囲に含まれている場合には、いずれの硬度においても応力の変化に対する特徴量の変化量が一定となる相関関係を有する特徴量として抽出してよい。
そして、相関情報記憶工程S12では、特徴量の種類と、応力又は硬度との相関関係を表す相関情報を記憶部23に記憶する。
特徴量取得工程S31では、特徴量取得部211が特徴量測定装置10から各測定位置における複数種類の特徴量を取得する。特徴量取得部211が特徴量測定装置10から取得する各測定位置における特徴量は、いずれの硬度においても応力の変化に応じて変化しないパターンであれば、一つ(単一)であってよい。特徴量取得部211が特徴量測定装置10から取得する各測定位置における特徴量は、複数種類であってよい。なお、ここで取得する複数種類の特徴量は、いずれの硬度においても応力の変化に対する特徴量の変化量が一定となる相関関係を有していればよい。第1実施形態では、例えば、特徴量として残留磁束密度Brと保磁力Hcとを取得する。
すなわち、式(4)及び式(5)は、式(4)のβiに式(5)を代入することにより、以下の式(6)のように示される。
Pi=αi・σ+ai・Hv+bi ・・・・・(6)
そして、一方の(第一の)特徴量P1における定数αi、ai、biをそれぞれα1、a1、b1とし、他方の(第二の)特徴量P2における定数αi、ai、biをそれぞれα2、a2、b2とすると、取得されたBr及びHcについて以下の式(7)及び式(8)を得ることができる。
P1=α1・σ+a1・Hv+b1 ・・・・・(7)
P2=α2・σ+a2・Hv+b2 ・・・・・(8)
そして、式(7)及び式(8)から、σを控除することにより、硬度Hvを求めることができる。なお、さらに一以上の異なる特徴量P3,P4・・・を取得して、対応する関係式を得るものとしてよい。この場合には、2つの未知数に対して、3つ以上の関係式を得ることができる。そして、得られた硬度Hvと応力σの結果を3つの関係式に代入し、各特徴量Piとの誤差が最小となるように最小二乗法により繰り返し計算することで、特徴量の測定時における誤差を補正することができる。
次に、第1実施形態の硬度演算プログラムについて説明する。
第1実施形態の硬度演算プログラムは、測定対象に対する磁界の印加に応じて検出コイルで検出される電流値又は電圧値の少なくとも一方を含む検出結果に基づいて、測定位置における硬度に関する情報である硬度情報を算出する硬度演算プログラムである。硬度演算プログラムは、コンピュータを、測定対象に第一周波数を有する第一交番磁界及び第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出される検出結果に基づいて、測定位置における硬度に対して変化する1又は複数の特徴量を算出する特徴量算出手段、及び、算出した特徴量に基づいて、硬度情報を算出する硬度情報手段として機能させるための硬度演算プログラムである。これにより、測定対象の硬度情報を高い精度で演算できる。
以下、本発明に係る第2実施形態について説明する。以下、第1実施形態と共通する部分については同じ符号を付すか、説明を省略する場合がある。
図1に示すように、第2実施形態の硬度演算装置20は、第1実施形態と同様に、測定対象に第一周波数を有する第一交番磁界及び第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出コイル15で検出される検出結果に基づいて、測定位置における硬度に対して変化する1又は複数の特徴量を算出する特徴量算出部18を備えている。
特徴量は、図4E、図4F、図4G及び図4Hに示されるように、測定位置における残留応力又は残留磁気に対して値が略一定となる不感帯領域M(M,M1,M2)を含んでいる。
Pi=fi(Hv) ・・・・・(9)
ただし、
i :特徴量の種類を示す符号
fi:相関関係を示す関数
Pi:特徴量
Hv:特徴量を測定した各位置における硬度
Pi=ai・Hv+bi ・・・・・(10)
ただし、
i :特徴量の種類を示す符号
Pi:特徴量
ai、bi:特徴量ごとに求められる定数
Hv:特徴量を測定した各位置における硬度
ΔPi=ai・ΔHv/2 ・・・・・(11)
Δσ≦ΔPi/αi ・・・・・(12)
そして、硬度演算装置20に備わる制御部21の硬度算出部213は、選択部で選択された特徴量に基づいて、硬度情報を算出する。
このように、第2実施形態に係る硬度演算装置20は、測定位置の残留応力又は残留磁気が不感帯領域Mに入っている特徴量を選択する選択部を備えている。これにより、鋼材101の表層の残留応力又は残留磁気が含まれる所定範囲で、残留応力又は残留磁気に対して値が略一定となる不感帯領域Mを有する種類の特徴量を選択できる。よって、所定範囲における残留応力又は残留磁気のばらつきに依存せずに、選択部で選択された特徴量から硬度を精度高く求めることができる。
以下、本発明に係る第3実施形態について説明する。以下、第1実施形態又は第2実施形態と共通する部分については同じ符号を付すか、説明を省略する場合がある。
図1において、第3実施形態の硬度演算装置20は、第1実施形態及び第2実施形態と同様に、測定対象に第一周波数を有する第一交番磁界及び第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出コイル15で検出される検出結果に基づいて、測定位置における硬度に対して変化する1又は複数の特徴量を算出する特徴量算出部18を備えている。
特徴量は、図4Aから図4Hまでに示されるように、測定対象(鋼材101)の硬度と残留応力又は残留磁気との各々に対してそれぞれ相関的に変化する相関変化領域N(N1,N2)を有している。
そして、このような2種類の特徴量の組み合わせについて2箇所の測定位置における測定結果を比較し、どのような変化の組み合わせとなっているかに注目することで、2箇所の測定位置の間が硬度変化部であるかどうかを判定することができる。
例えば、これら2つの特徴量として、図4Aで表される傾向を示す最大磁化電圧Vmagと、図4Bで表される傾向を示す最大増分透磁率DZmaxとの組み合わせが挙げられる。
この場合、第1の測定位置及び第2の測定位置の各々において、最大磁化電圧Vmagと最大増分透磁率DZmaxを算出する。
そして、第1の測定位置と第2の測定位置との間で、最大磁化電圧Vmagが減少傾向であり、最大増分透磁率DZmaxは増加傾向である場合、例えば、図7Cに示すような判定テーブルに従って、第1の測定位置及び第2の測定位置との間に硬度が高くなっている部分(硬化部)があることを判定できる。
いいかえると、特徴量と、応力及び硬度との相関関係のパターンは、特徴量ごとに異なる関係となる場合がある。そのため、特徴量ごとに、特徴量と、応力及び硬度との相関関係のパターンを確認する必要がある。
図7Aから図7Dまでは、2種類の特徴量の増減の組み合わせと、応力及び硬度の変化傾向(増減)との関係を示す判定テーブルである。図7Aは、第1の判定テーブルである。図7Bは、第2の判定テーブルである。図7Cは、第3の判定テーブルである。図7Dは、第4の判定テーブルである。
例えば、図4Eに示される特徴量は、不感帯領域M1と、相関変化領域N1を有する。また、図4Gに示される特徴量は、不感帯領域M2と、相関変化領域N2とを有する。ここで、相関変化領域N1と相関変化領域N2とが重なる応力範囲では、2箇所の測定位置で比較して、硬度が高くなった場合には、図4Eに示される特徴量は増大し、図4Gに示される特徴量も増大する。また、硬度が低くなった場合には、図4Eに示される特徴量は減少し、図4Gに示される特徴量も減少する。一方、応力が増大する場合には、一方の特徴量は増大し、他方の特徴量は減少する。このように、硬度(応力または硬度のうちいずれか一方)の変化に対して同一傾向を示すとともに、応力(応力または硬度のうちいずれか他方)の変化に対しては逆傾向を示す2種類の特徴量の組み合わせについて2箇所の測定位置における測定結果を比較し、どのような変化の組み合わせとなっているかに注目することで、硬度変化部、すなわち硬度が高くなっている部分(硬化部)及び硬度が低くなっている部分(軟化部)であるかどうかを判定することができる。
図8は、第3実施形態の制御部31の機能構成を示すブロック図である。
図8に示すように、制御部31は、特徴量取得部311と、判定テーブル取得部312と、判定部313とを有する。
特徴量取得部311は、特徴量測定装置10による測定単位ごと(同一の測定位置での測定ごと)に、特徴量算出部18から出力された少なくとも2種類の特徴量を取得する。例えば、第3実施形態では、特徴量取得部311は、残留磁束密度Brと保磁力Hcとを取得する。
判定テーブル取得部312は、特徴量取得部311で取得された特徴量の種類の組み合わせと対応した判定テーブルを取得する。例えば、第3実施形態では、図7Aに示す判定テーブルを取得する。
判定部313は、特徴量取得部311で取得された特徴量と、特徴量の種類と対応して判定テーブル取得部312で取得された判定テーブルとに基づいて、基準となる測定位置に対して硬度が変化、すなわち高くなったか、低くなったかを判定する。また、合わせて基準となる測定位置に対して応力が変化、すなわち応力が大きくなったか、小さくなったかを判定してもよい。ここで、基準となる測定位置は、予め決めた基準位置としてよく、常に前回の測定位置を基準となる測定位置として更新するものとしてもよい。
次に、制御部31によって実施される第3実施形態の硬度変化部検出方法について説明する。図9は、第3実施形態の硬度変化部検出方法を説明するフロー図である。
標準片測定工程S301では、第1実施形態及び第2実施形態の第一準備工程と同様に、測定対象となる鋼材101と同一鋼種であって、予め表層の応力σ及び硬度Hvが既知の標準片を、応力σまたは硬度Hvが異なるようにして複数準備する。
相関情報記憶工程S302では、標準片測定工程S301において得られた、各標準片の特徴量と、応力及び硬度に基づいて、図4Aから図4Hまでに示されるようなグラフをテーブル形式の数値の集合等で示した各特徴量と応力及び硬度との相関関係を取得する。そして、整理した相関関係の結果から図7Aから図7Dまでに示すような判定テーブルを作成する。
特徴量取得工程S501では、特徴量取得部211が特徴量測定装置10から各測定位置における少なくとも2種類の特徴量を取得する。第3実施形態では、例えば、特徴量として残留磁束密度Brと保磁力Hcとを取得する。
判定テーブル取得工程S502では、特徴量取得工程S501で取得された特徴量の種類の組み合わせと対応した判定テーブルを記憶部23から取得する。
以下、本発明に係る第4実施形態について説明する。以下、第1実施形態から第3実施形態と共通する部分については同じ符号を付すか、説明を省略する場合がある。
第4実施形態において、硬度情報は、例えば、測定対象の測定位置の硬度が規定の硬度範囲内の硬度を有するか否かの判別を可能とする情報である。なお、硬度情報は、測定対象の測定位置の硬度が規定の硬度範囲内の硬度を有するか否かの判別を可能とする情報に限られない。
ここで、特徴量と硬度情報との相関関係を求めるのに機械学習を用いてよい。硬度算出部213(図5参照)は、特徴量と硬度情報との相関関係を学習した学習済みモデルを用いて、測定対象の測定位置における特徴量の測定値に基づいて、硬度情報を算出する。
例えば、鋼材101の表層の性状によって変化する特徴量は、鋼材101の表層の特徴量に限られない。本発明の実施形態において、硬度測定システム1は、硬度を演算する場合に限られない。例えば、硬度測定システム1は、硬度情報に加えて応力情報を測定することとしてよい。また、硬度測定システム1は、硬度情報に代えて応力情報を測定する応力測定システムとして機能してよい。
10 特徴量測定装置
11 磁化器
12 発振器
13 励磁電源
14 磁界演算部
15 検出コイル
16 磁束密度演算部
17 履歴曲線等演算部
18 特徴量算出部
20 硬度演算装置
101 鋼材
111 ヨーク
111a 鉄芯部
111b 胴部
112 励磁コイル
112H 高周波励磁コイル
112L 低周波励磁コイル
213 硬度算出部
Claims (10)
- 測定対象に対する磁界の印加に応じて検出コイルで検出される電流値又は電圧値の少なくとも一方の検出結果に基づいて、測定位置における硬度に関する情報である硬度情報を演算する硬度演算装置であって、
前記測定対象に第一周波数を有する第一交番磁界及び前記第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出される前記検出結果に基づいて、前記測定位置における硬度に対して変化する1又は複数の特徴量を算出する特徴量算出部と、
1又は複数の前記特徴量に基づいて、前記硬度情報を算出する硬度算出部と、を備える硬度演算装置。 - 前記特徴量は、電流波形、電圧波形、磁気特性又はインピーダンスループの少なくともいずれか1つに基づいて算出可能な特性値である請求項1に記載の硬度演算装置。
- 前記硬度情報は、前記測定対象の前記測定位置における表層の硬度であり、
前記特徴量は、前記測定対象の硬度と残留応力又は残留磁気との各々に対してそれぞれ相関的に変化する相関変化領域を有し、
前記硬度算出部は、前記測定対象の種に応じて予め求められた複数の前記特徴量の各々について、前記相関変化領域における前記特徴量と、前記測定対象の硬度と、残留応力又は残留磁気の少なくともいずれか一つとの相関関係に基づいて、前記測定位置における表層の硬度を算出する請求項1又は請求項2に記載の硬度演算装置。 - 前記硬度情報は、前記測定対象の前記測定位置における表層の硬度であり、
前記特徴量は、前記測定位置における残留応力又は残留磁気に対して値が一定となる不感帯領域をさらに含む請求項1又は請求項2に記載の硬度演算装置。 - 前記硬度情報は、第1の測定位置の硬度に対する第2の測定位置の硬度の変化の有無であり、
前記特徴量は、前記測定対象の硬度と残留応力又は残留磁気との各々に対してそれぞれ相関的に変化する相関変化領域を有し、
前記硬度算出部は、前記相関変化領域における、前記第1の測定位置及び前記第2の測定位置の各々においてそれぞれ算出された複数の前記特徴量の各々の変化傾向に基づいて、前記硬度情報を算出するよう構成されており、
複数の前記特徴量は、応力又は硬度のうちいずれか一方の変化に対して互いに同一の変化傾向を示すとともに、いずれか他方の変化に対して互いに逆の変化傾向を示す少なくとも2つの前記特徴量を含む請求項1又は請求項2に記載の硬度演算装置。 - 前記硬度算出部は、
前記特徴量と前記硬度情報との相関関係を学習した学習済みモデルを用いて、前記測定対象の前記測定位置における前記特徴量の測定値に基づいて、前記硬度情報を算出する請求項1又は請求項2に記載の硬度演算装置。 - 前記硬度算出部は、複数の前記特徴量と、前記測定対象の化学成分及び/又は製造条件とに基づいて、前記硬度情報を算出する請求項1から請求項6のいずれか1項に記載の硬度演算装置。
- 前記測定対象に第一の周波数を有する第一交番磁界を印加する高周波磁界印加手段と、
前記測定対象に、前記第一の周波数よりも低い第二の周波数を有する第二交番磁界を印加する低周波磁界印加手段と、
前記第一交番磁界及び前記第二交番磁界の各々を印加したときに得られる前記測定対象からの磁界を検出する検出コイルと、
前記検出コイルに流れる電流値又は電圧値の少なくとも一方を検出する検出手段と、
請求項1から請求項7のいずれか1項に記載の硬度演算装置と、を備える硬度測定システム。 - 測定対象に対する磁界の印加に応じて検出コイルで検出される電流値又は電圧値の少なくとも一方を含む検出結果に基づいて、測定位置における硬度に関する情報である硬度情報を算出する硬度演算方法であって、
前記測定対象に第一周波数を有する第一交番磁界及び前記第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出される前記検出結果に基づいて、前記測定位置における硬度に対して変化する1又は複数の特徴量を算出し、
1又は複数の前記特徴量に基づいて、前記硬度情報を算出する、ことを含む硬度演算方法。 - 測定対象に対する磁界の印加に応じて検出コイルで検出される電流値又は電圧値の少なくとも一方を含む検出結果に基づいて、測定位置における硬度に関する情報である硬度情報を算出する硬度演算プログラムであって、
コンピュータを、
前記測定対象に第一周波数を有する第一交番磁界及び前記第一周波数よりも低い第二の周波数を有する第二交番磁界の印加に応じて検出される前記検出結果に基づいて、前記測定位置における硬度に対して変化する1又は複数の特徴量を算出する特徴量算出手段、及び、
前記特徴量に基づいて、前記硬度情報を算出する硬度情報手段として機能させるための硬度演算プログラム。
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