JP2018021800A - Grinding burn inspection method for workpiece, and grinding burn inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding burn inspection method capable of detecting full-range grinding burn in a grinding processing portion of a workpiece on which grinding processing has been performed, through a non-destructive inspection and a grinding burn inspection device.SOLUTION: A grinding burn inspection method includes: a first acquisition step S10 for acquiring a first output voltage V1 in accordance with a high frequency excitation current Hi1; a second acquisition step S20 for acquiring a second output voltage V2 in accordance with a low frequency excitation current Li1; a reference value setting step S50 for setting a reference value Bm based on the first output voltage V1 and the second output voltage V2; a third acquisition step S60 for acquiring a third output voltage V3 in accordance with the high frequency excitation current Hi1; a fourth acquisition step S70 for acquiring a fourth output voltage V4 in accordance with the low frequency excitation current Li1; and a first discrimination step S100 for discriminating the presence/absence of full-range grinding burn based on the reference value Bm, an average value Av3 of the third output voltage V3 and an average value Av3 of the fourth output voltage V4.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a grinding burn inspection method and a grinding burn inspection apparatus for a workpiece.

  Conventionally, various techniques have been disclosed for detecting non-destructive inspection of local grinding burns in which grinding burns occur in a part of the range of the ground parts with respect to a workpiece subjected to grinding processes (for example, Patent Documents). 1 and 2).

JP2013-224916A JP 2011-106932 A

  However, in recent years, not only the above-mentioned local burn, but also the presence / absence of full-range grinding burn in which grinding burn occurs over the entire range of the processed part of the ground workpiece is required to be inspected by nondestructive inspection. .

  The present invention has been made in view of such circumstances, and a grinding burn inspection method and grinding of a workpiece capable of detecting a full-range grinding burn in a grinding portion of a ground workpiece by nondestructive inspection. An object is to provide a burn inspection device.

  In the grinding burn inspection method for a workpiece according to the present invention, an eddy current is generated by an exciting current inside a ground workpiece to be inspected, and the inspection target is based on an output voltage corresponding to the generated eddy current. The presence or absence of grinding burn in the surface layer portion of the processed part of the workpiece is determined. A grinding burn inspection method includes a first acquisition step of obtaining a first output voltage when the eddy current is generated by a high-frequency excitation current inside a predetermined position of a reference workpiece having no grinding burn, A second acquisition step of acquiring a second output voltage when the eddy current is generated by a low-frequency excitation current inside the predetermined position of the reference workpiece; the first output voltage and the second output voltage; A reference value setting step for setting a reference value for determining whether or not the entire range grinding burn occurs over the entire range of the predetermined inspection area of the workpiece to be inspected, and the inspection target A third acquisition step of acquiring a third output voltage when the eddy current is generated by the high-frequency excitation current within the entire range of the predetermined inspection area of the workpiece of the workpiece, and the workpiece of the inspection object All of the predetermined inspection areas A fourth acquisition step of acquiring a fourth output voltage when the eddy current is generated by the low-frequency excitation current in the interior, and the reference value, the average value of the third output voltage, and the fourth output voltage And a first determination step of determining the presence or absence of the entire range grinding burn based on the average value.

  In this way, the first output voltage at the surface layer part acquired according to the eddy current generated in the predetermined position of the reference workpiece without grinding burn due to the high frequency excitation current and the low frequency excitation current, and at a position deeper than the surface layer part. Based on the second output voltage in a certain deep layer portion, a reference value for determining the presence or absence of full-range grinding burn is set. Further, for the workpiece to be inspected, the third output voltage corresponding to the first output voltage and the fourth output voltage corresponding to the second output voltage are acquired as in the reference workpiece. At this time, the first output voltage and the third output voltage are output voltages at the surface layer portion of the workpiece. For this reason, the first output voltage is an output voltage including a variation due to a variation that differs for each base material.

  Further, when grinding burn has occurred in the surface layer portion, the third output voltage is an output voltage including a variation due to different variations for each base material and a variation due to grinding burn. Therefore, if the first output voltage is used as a reference value and an attempt is made to determine the presence or absence of grinding burn of the entire range of the workpiece by comparing the reference value with the third output voltage, the variation due to the variation of the base material in the surface layer of the workpiece It is difficult to discriminate from the fluctuation due to the grinding burn generated in the surface layer portion, and it is difficult to accurately determine the entire range grinding burn.

  However, in the present invention, when setting the reference value, not only the first output voltage but also the second output voltage in the deep layer including only the variation due to the variation of the base material is used to determine the presence or absence of the entire range grinding burn. Use. Also, the output voltage obtained from the workpiece for comparison with the reference value is not only the third output voltage, but also the fourth output voltage that is not affected by grinding burn and includes only the fluctuation due to the variation of the base material. . Therefore, the reference value can be set as a reference value that cancels out the variation due to the variation in the base material based on the first output voltage and the second output voltage. Further, the output voltage acquired from the workpiece for comparison with the reference value can also be set to an output voltage that offsets the variation due to the variation of the base material based on the third output voltage and the fourth output voltage. That is, since the presence or absence of the entire range grinding burn in the surface layer portion is determined based on the reference value and the output voltage (based on the third output voltage and the fourth output voltage) that do not include fluctuation due to variations in the base material, An accurate determination result that is not affected by variations can be obtained.

  Further, the grinding burn inspection apparatus for a workpiece according to the present invention generates an eddy current by an excitation current inside the ground workpiece to be inspected, and based on the output voltage corresponding to the generated eddy current. A grinding burn inspection device that determines whether or not grinding burn has occurred in a surface layer portion of a processing part of a workpiece to be inspected, and the grinding burn inspection device includes a sensor and a control unit. The sensor outputs a first output voltage and a second output voltage when the eddy current is generated by a high frequency excitation current and a low frequency excitation current inside a predetermined position of a reference workpiece not having grinding burn. And a third output voltage and a fourth output voltage when the eddy current is generated by the high frequency excitation current and the low frequency excitation current within the entire range of the predetermined inspection area of the workpiece to be inspected. Get the output voltage.

  The control unit is a full-range grinding burn that generates a grinding burn over the entire range of a predetermined inspection region of the workpiece to be inspected based on the first output voltage and the second output voltage acquired by the sensor. A reference value calculation unit for calculating a reference value for determining the presence or absence of the output, an average value calculation unit for calculating an average value of the third output voltage and the fourth output voltage acquired by the sensor, and the calculation. And a first determination unit that determines the presence or absence of the entire range grinding burn based on the reference value and the average values of the third output voltage and the fourth output voltage. With this inspection device, it is possible to accurately determine the presence or absence of the entire range grinding burn of the workpiece, as in the grinding burn inspection method of the workpiece.

It is a schematic diagram of the grinding burn inspection device of a work of a first embodiment. It is a graph explaining an example of the characteristic of a 1st output voltage. It is a graph explaining an example of the characteristic of the 2nd output voltage. It is a flowchart of the inspection method of the full range grinding burn in 1st embodiment. It is a schematic diagram of the grinding burn inspection apparatus of the workpiece of 2nd embodiment. It is a graph which shows the characteristic of the amplitude level (output value) obtained when frequency-analyzing the waveform of a 5th output voltage. It is a flowchart of the inspection method of the local grinding burn in 2nd embodiment. It is a figure which shows the waveform of the 5th output voltage for every rotation phase angle of the workpiece of the test object which a sensor head acquires. It is a figure which shows the waveform of the amplitude level for every frequency of the workpiece of a test object.

<1. First embodiment>
(1-1. Outline of grinding burn inspection device)
The outline | summary of the grinding burn inspection apparatus 1 of the workpiece which concerns on 1st embodiment of this invention is demonstrated. The grinding burn inspection apparatus 1 shown in FIG. 1 covers the entire range of a predetermined inspection area Ar1 in the workpiece 2B to be inspected among the workpieces 2 whose outer peripheral surfaces are ground by a machine tool (grinding machine). It is an apparatus that inspects (detects) the occurrence of full-range grinding burn, which is a grinding burn of a predetermined amount or more.

  The workpiece 2 has the above-described workpiece 2B to be inspected (hereinafter referred to only as the workpiece 2B) and a reference value B for determining the presence or absence of full-range grinding burn in the grinding portion of the workpiece 2B. And a reference workpiece 2A for setting a reference value used for setting. The predetermined inspection area Ar1 and the entire range will be described in detail later.

  The grinding burn inspection apparatus 1 inspects the grinding burn of the workpiece 2B by a magnetic nondestructive inspection using magnetism generated by eddy current. When inspecting grinding burn of a workpiece by magnetic non-destructive inspection, the inspection device normally supplies an excitation current set to a high frequency to the primary coil of the sensor and generates a magnetic field (magnetic field). ) Is applied to the workpiece, and eddy current is induced at a depth (surface layer portion) corresponding to the frequency of the high-frequency excitation current.

  Thereafter, the primary coil and the workpiece are relatively moved, and the output voltage of the eddy current that changes due to this movement is detected and acquired by the secondary coil of the sensor. Then, at the portion where the grinding burn has occurred, the presence / absence of the grinding burn is determined based on the magnitude of the output voltage whose value is reduced compared to before the occurrence of the grinding burn.

  However, when the workpiece has “whole range grinding burn”, the output voltage at the surface layer portion obtained by the grinding burn inspection apparatus 1 is usually in the full range compared to the case where the workpiece does not have grinding burn. It has been found that it decreases almost uniformly over the period. For this reason, for example, the output voltage at the surface layer of a normal workpiece (reference workpiece) without grinding burn (whole grinding burn) is used as a reference value, and the reference value and the output voltage at the surface layer of the workpiece 2B are simply Even if compared to the above, it is not easy to distinguish between the variation in the output voltage due to the variation of each base material and the variation in the output voltage that is uniformly shifted in the entire range due to the entire range grinding burn. As a result, it may be difficult to determine whether there is full-range grinding burn. Hereinafter, the grinding burn inspection apparatus 1 for a workpiece capable of determining whether or not there is a full-range grinding burn based on the above circumstances will be described in detail.

  In the present embodiment, the reference workpiece 2A is a normal workpiece having no grinding burn in the surface layer portion after the outer peripheral surface is ground. In the present embodiment, the workpiece 2 is intended for a cylindrical or columnar member (for example, an outer ring of a bearing) that is a magnetic material and is carburized and quenched. However, the workpiece 2 is not limited to carburizing and quenching, and may be a quenching quenching. Further, other processing may be performed.

(1-2. Configuration of Workpiece Grinding Burn Inspection Device)
First, the structure of the grinding burn inspection apparatus 1 for a workpiece according to the first embodiment will be described with reference to FIGS. 1, 2A, 2B, and 3. FIG. As shown in FIG. 1, the grinding burn inspection device 1 includes a magnetic sensor 10 (corresponding to “sensor” of the present invention), a rotation support unit 20, and a control device 30 (corresponding to “control unit” of the present invention). , And the main constituent.

  The magnetic sensor 10 includes a sensor body 11, a sensor head 12, a measuring device 13, a touch sensor 14, and a sensor feed mechanism 15. Excitation currents (high-frequency excitation current Hi1 and low-frequency excitation current Li1) set at two different frequencies are alternately supplied to the sensor body 11 from a supply unit 31 of the control device 30 described later. The sensor body 11 supplies the excitation current to a primary coil (not shown) of the sensor head 12.

  The sensor head 12 generates a magnetic field (magnetic field) by the high frequency excitation current Hi1 and the low frequency excitation current Li1 alternately supplied to the primary coil, and the generated magnetic field is generated on the outer peripheral surfaces of the reference workpiece 2A and the workpiece 2B. Sequentially applied over the entire range of the predetermined position P1 or the predetermined inspection region Ar1 (the entire circumference in the circumferential direction of the outer peripheral surface), and eddy currents are induced in two locations with different depths. Thereby, the sensor head 12 has the first output voltage V1 and the third output voltage V3 with respect to the reference workpiece 2A and the workpiece 2B at the penetration depth (surface layer portion and deep layer portion) corresponding to the frequency of the excitation current. , Second output voltage V2, and fourth output voltage V4.

  The first output voltage V1 is acquired by inducing an eddy current at the surface layer portion of the reference workpiece 2A by the high-frequency excitation current Hi1. Further, the third output voltage V3 is obtained by inducing an eddy current in the surface layer portion of the workpiece 2B by the high-frequency excitation current Hi1. Further, the second output voltage V2 is acquired by inducing an eddy current in the deep layer portion of the reference workpiece 2A by the low frequency excitation current Li1. Further, the fourth output voltage V4 is acquired by inducing an eddy current in the deep layer portion of the workpiece 2B by the low frequency excitation current Li1. The values of the first output voltage V1, the third output voltage V3, the second output voltage V2, and the fourth output voltage V4 change according to the state (deformed state) of the reference workpiece 2A and the workpiece 2B. Has characteristics.

  That is, at the predetermined position P1 or the predetermined area Ar1 (surface layer portion) on the outer peripheral surface of the reference workpiece 2A or the workpiece 2B to which the magnetic field by the high-frequency excitation current Hi1 is applied by the sensor head 12, the first output voltage V1. Or the third output voltage V3 (waveform) is acquired by the secondary coil (not shown) of the sensor head 12. The predetermined position P1 or the predetermined area Ar1 on each outer peripheral surface of the reference workpiece 2A or the workpiece 2B is, as shown in FIG. 1, the width direction of the outer peripheral surfaces of the reference workpiece 2A and the workpiece 2B (that is, It is a position or region over the entire circumference (one round) in the center in the axial direction). That is, the whole range is a range of 360 ° when expressed by the rotation phase angle of the reference workpiece 2A or the workpiece 2B.

  However, the present invention is not limited to this, and the predetermined position P1 or the predetermined inspection area Ar1 of the reference workpiece 2A or the workpiece 2B is not the center in the width direction of the outer peripheral surface, but any one other than the center in the width direction. It may be the entire circumference in the circumferential direction at the position. Further, the predetermined position P1 of the reference workpiece 2A may not be the entire circumference in the circumferential direction of the outer peripheral surface, but may be a part in the circumferential direction. Furthermore, the predetermined position P1 of the reference workpiece 2A may be one point on the outer peripheral surface.

  Further, in the reference workpiece 2A to which the magnetic field (magnetic field) by the low-frequency excitation current Li1 is applied by the sensor head 12, and in the predetermined position P1 on the outer peripheral surface of the workpiece 2B or inside the predetermined inspection area Ar1 (deep layer portion). The second output voltage V2 (waveform) or the fourth output voltage (waveform) is acquired by the secondary coil (not shown) of the sensor head 12.

  The first output voltage V1 to the fourth output voltage V4 detected and acquired by the sensor head 12 are the reference workpiece 2A and the workpiece 2B with the sensor head 12 inducing eddy currents in the surface layer portion and the deep layer portion, respectively. And the output voltage of the induced electromotive force generated in the eddy current when the sensor head 12 (sensor body 11) is relatively moved.

  As shown in FIG. 1, the measuring device 13 receives the first output voltage V <b> 1 to the fourth output voltage V <b> 4 detected by the sensor head 12 from the sensor main body 11 via the signal line. And the measuring apparatus 13 outputs this 1st output voltage V1-4th output voltage V4 to the 1st acquisition part 32 of the control apparatus 30 mentioned later as a detected value of the magnetic sensor 10. FIG.

  The touch sensor 14 is a contact-type sensor provided at the base end portion of the sensor head 12 inside the sensor body 11. The touch sensor 14 includes a spring 14a that urges the sensor head 12 to the workpiece 2 with a predetermined urging force (pressing force). The sensor head 12 is always in contact with the workpiece 2 by the spring 14a. The touch sensor 14 detects whether the sensor head 12 is in contact or non-contact with the workpiece 2 based on the expansion / contraction state of the spring 14a. The touch sensor 14 outputs the detected contact information of the tip of the sensor head 12 to the control device 30 (not shown).

  The sensor feed mechanism 15 is provided in the rear part of the sensor body 11 (on the side opposite to the workpiece 2 with respect to the sensor body 11), and holds the sensor body 11 so as to be movable in the axial direction of the workpiece 2. The sensor feed mechanism 15 is constituted by, for example, a ball screw and a servo motor or a hydraulic mechanism. The sensor feed mechanism 15 is a moving unit that moves the sensor body 11 relative to the workpiece 2 so as to vary the distance between the workpiece 2 and the sensor body 11.

  Then, the sensor feed mechanism 15 detects a movement direction position (a radial direction position in the workpiece 2) of the holding portion that holds the sensor body 11 from a servo motor (not shown). The position sensor 15 a outputs position information of the sensor body 11 detected from the servo motor to the control device 30. Thereby, the control device 30 detects the separation distance (clearance) of the sensor head 12 from the inspection surface based on the contact information of the sensor head 12 by the touch sensor 14 and the position information of the sensor main body 11 by the sensor feed mechanism 15.

  The rotation support unit 20 includes drive wheels 21 and an adjustment wheel 22 and supports the workpiece 2 to be rotatable. The drive wheel 21 contacts the outer peripheral surface of the workpiece 2 and rotates the workpiece 2 by being driven to rotate by a motor (not shown). The drive wheel 21 has an encoder 21a that detects the rotational position of a motor (not shown).

  The encoder 21 a outputs the detected rotational position information of the motor to the control device 30. As a result, the control device 30 determines the circumferential phase (rotation phase) of the sensor head 12 with respect to the workpiece 2 based on the shape information including the diameter and circumference of the workpiece 2 as the initial information and the rotational position information of the motor. Is detected. The adjustment wheel 22 supports the workpiece 2 together with the drive wheels 21 and is driven to rotate by a frictional force with the outer peripheral surface of the workpiece 2.

  As shown in FIG. 1, the control device 30 (control unit) includes a supply unit 31, a first acquisition unit 32, a reference value calculation unit 33, a second acquisition unit 34, an average value calculation unit 35, And a determination unit 36.

  The supply unit 31 is connected to the sensor main body 11 via the measuring device 13 and supplies the high frequency excitation current Hi1 and the low frequency excitation current Li1 to the sensor main body 11, respectively. The high-frequency excitation current Hi1 is an excitation current having a frequency included in a frequency band in which the surface layer portions of the reference workpiece 2A and the workpiece 2B have a penetration depth. This frequency is set to a range higher than 100 kHz and lower than 1.0 MHz, and is set to 250 kHz in the present embodiment. In the workpiece 2, the surface layer portion has a depth in a range where grinding burn can occur by grinding the outer peripheral surface of the workpiece 2.

  Further, the low frequency excitation current Li1 is an excitation current having a frequency included in a frequency band in which a deep layer portion below the surface layer portion has a penetration depth. This frequency is set to a range lower than 100 kHz and higher than 0.1 kHz, and is set to 500 Hz in the present embodiment. The deep layer portion has a depth that does not cause grinding burn even when grinding is performed on the outer peripheral surface of the workpiece 2. That is, the deep layer portion mainly has only the characteristics of the base material.

  The first acquisition unit 32 is connected to the measurement device 13. The first acquisition unit 32 acquires the first output voltage V1 in the surface layer portion and the second output voltage V2 in the deep layer portion of a plurality of (for example, five) normal reference workpieces 2A that do not have grinding burn. The method for obtaining the first output voltage V1 and the second output voltage V2 from the reference workpiece 2A is as described above. The first acquisition unit 32 is connected to the reference value calculation unit 33 and outputs the acquired first output voltage V <b> 1 and second output voltage V <b> 2 to the reference value calculation unit 33. At this time, the number of reference workpieces 2A from which the first output voltage V1 and the second output voltage V2 are acquired may be one, but the larger the number, the better.

  The reference value calculation unit 33 determines the predetermined workpiece 2B to be inspected based on the first output voltage V1 (see FIG. 2A) and the second output voltage V2 (see FIG. 2B) acquired by the sensor head 12 (magnetic sensor 10). A reference value Bm is calculated for determining whether or not there is a full range grinding burn that causes grinding burn over the entire range of the inspection area Ar1 (see FIG. 1).

The reference value calculation unit 33 calculates a reference value B that is a basis for setting the reference value Bm based on the following equation (1).
[Equation 1] B = Av1-Av2 (1)
Av1: Average value of the first output voltage V1 Av2: Average value of the second output voltage V2

  At this time, the reference value B is obtained by subtracting the average value Av2 of each second output voltage V2 from the average value Av1 of each first output voltage V1 for each reference workpiece 2A. In the present embodiment, normally, the average value Av1 of the first output voltage V1 is larger than the average value Av2 of the second output voltage V2. For this reason, the reference value B is obtained as a positive value suitable as the reference value by the expression (1). Further, by subtracting the average value Av2 of each second output voltage V2 from the average value Av1 of the first output voltage V1, a variation due to variations in the base material included in both the first output voltage V1 and the second output voltage V2 is obtained. Is offset.

  In the present embodiment, the maximum reference value B among the plurality of reference values B calculated in this way is set as the reference value Bm. However, the present invention is not limited to this mode, and the reference value Bm may be an output voltage corresponding to 3σ, 4σ, or the like after obtaining the variation (σ) of the plurality of calculated reference values B. The set reference value Bm is output to the first determination unit 36 and stored.

  In addition, the reference value B is not limited to the above-described aspect, and the reference value B is an absolute value | Av1 | of the average value Av1 of each first output voltage V1 to an average value Av2 of each second output voltage V2 for each reference workpiece 2A The absolute value | Av2 | may be subtracted. Also by this, the reference value B is obtained as a positive value suitable as the reference value.

  The second acquisition unit 34 is connected to the measurement device 13. The second acquisition unit 34 acquires from the measurement device 13 the third output voltage V3 in the surface layer portion of the workpiece 2B acquired by the sensor head 12 (magnetic sensor 10) and the fourth output voltage V4 in the deep layer portion. The method for obtaining the third output voltage V3 and the fourth output voltage V4 from the workpiece 2B is as described above. The second acquisition unit 34 is connected to the average value calculation unit 35. Then, the acquired third output voltage V3 and fourth output voltage V4 are output to the average value calculator 35.

  The average value calculator 35 calculates the average values Av3 and Av4 over the entire range of the third output voltage V3 and the fourth output voltage V4 (the entire outer peripheral surface of the workpiece 2B). The average values Av3 and Av4 may be obtained by any calculation method.

  The first determination unit 36 determines the presence or absence of full-range grinding burn based on the calculated reference value Bm and the average values Av3 and Av4 of the third output voltage V3 and the fourth output voltage V4. Specifically, depending on the magnitude of the reference value Bm and the difference obtained by subtracting the absolute value | Av4 | of the average value Av4 of the fourth output voltage V4 from the absolute value | Av3 | of the average value Av3 of the third output voltage V3. Determine if there is grinding burn on the entire area. That is, when the following formula (2) is satisfied, it is determined that the workpiece 2B has full-range grinding burn.

[Expression 2] Bm <| Av3 |-| Av4 | (2)
Bm: Reference value Av3: Average value of the third output voltage V3 Av4: Average value of the fourth output voltage V4

  In addition, when grinding burn has arisen in the surface layer part, the 3rd output voltage V3 tends to fall, and it may become a negative value. For this reason, in the above equation (2), the average value of the third output voltage V3 and the fourth output voltage V4 are both absolute values, thereby making the difference a positive value and establishing a comparison with the reference value Bm. .

  Further, the third output voltage V3 and the fourth output voltage V4 are obtained by subtracting the absolute value | Av4 | of the average value Av4 of the fourth output voltage V4 from the absolute value | Av3 | of the average value Av3 of the third output voltage V3. The variation due to the variation of the base material included in the

  The difference between the average values Av3 and Av4 of the third output voltage V3 and the fourth output voltage V4 to be compared with the reference value Bm is not limited to the above aspect, and may be obtained by | Av4-Av3 |. Also, in each rotational phase of the workpiece 2B, an average value of | v4-v3 | is calculated for each output voltage value v3, v4 of the corresponding third output voltage V3 and fourth output voltage V4 to obtain a reference You may compare with value Bm. Further, an average value of (v4-v3) may be calculated for each output voltage value v3, v4 and compared with the reference value Bm. In any case, a corresponding effect can be expected.

(1-3. Inspection method for grinding burn of the entire range of the workpiece)
Next, an inspection method for the entire range grinding burn of the workpiece will be described based on the flowchart of FIG. The grinding burn inspection method using the grinding burn inspection apparatus 1 according to the first embodiment is grinding burn of a predetermined amount or more over the entire range of the predetermined inspection area Ar1 in the workpiece 2B to be inspected that has been ground. Inspect whether full-range grinding burn has occurred. In performing the following inspection, the control device 30 controls the rotation support unit 20 to rotate the reference workpiece 2A and the workpiece 2B at a predetermined number of rotations.

  In step S10 (first acquisition step), the first output voltage V1 is acquired. Therefore, first, the control device 30 controls the supply unit 31 to supply the high frequency excitation current Hi1 to the sensor head 12. Thereby, the sensor head 12 applies a magnetic field to a predetermined part of the position P1 on the outer peripheral surface of the reference workpiece 2A, and induces an eddy current in the surface layer (inside) of the reference workpiece 2A. At this time, the sensor head 12 is in contact with a predetermined position P1 on the outer peripheral surface of a normal reference workpiece 2A that does not have grinding burn.

  Then, when the reference workpiece 2A and the sensor head 12 are relatively moved, the first output voltage V1 is generated in the surface layer portion, and the sensor head 12 acquires the generated first output voltage V1. At this time, the first output voltage V1 of the normal reference workpiece 2A is an output voltage including a variation due to variations in the base material in the surface layer portion. The acquired first output voltage V <b> 1 is input to the measurement device 13 via the sensor body 11. Thereafter, the acquired first output voltage V <b> 1 is output from the measurement device 13 to the first acquisition unit 32 of the control device 30 and stored in the first acquisition unit 32.

  Next, in step S20 (second acquisition step), in the first acquisition step S10, the control device 30 controls the supply unit 31 immediately after acquisition of the first output voltage V1 is completed at a part of the predetermined position P1. The low frequency excitation current Li1 is supplied to the sensor head 12. Thereby, the sensor head 12 applies a magnetic field to the reference workpiece 2A, and induces an eddy current in the deep layer portion (inside) of the reference workpiece 2A.

  Then, relative movement between the reference workpiece 2A and the sensor head 12 generates a second output voltage V2 in the deep layer, and the sensor head 12 acquires the generated second output voltage V2. At this time, like the first output voltage V1, the second output voltage V2 of the normal reference workpiece 2A is an output voltage including a variation due to variations in the base material in the deep layer portion. The acquired second output voltage V <b> 2 is input to the measurement device 13 via the sensor body 11. Thereafter, the acquired second output voltage V <b> 2 is output from the measurement device 13 to the first acquisition unit 32 of the control device 30 and stored in the first acquisition unit 32. In addition, in the above, you may reverse the process order of process S10 (1st acquisition process) and process S20 (2nd acquisition process).

  In step S30 (first confirmation step), the acquisition of the first output voltage V1 and the second output voltage V2 in step S10 and step S20 is within the predetermined range P1 of the predetermined outer peripheral surface of the reference workpiece 2A. It is confirmed whether or not the process has been completed. In the present embodiment, it is assumed that the entire range is one round (360 degrees) in the circumferential direction of the outer peripheral surface of the reference workpiece 2A.

  If acquisition of the 1st output voltage V1 and the 2nd output voltage V2 is performed over the whole range of an outer peripheral surface, processing of process S40 will be performed next. If not performed over the entire range, the processes of S10 to S30 are repeated until it is confirmed in step S30 that the entire range has been performed.

  In step S40 (second confirmation step), the number of reference workpieces 2A for which acquisition of the first output voltage V1 and the second output voltage V2 has been completed is confirmed. If the number of reference workpieces 2A for which acquisition of the first output voltage V1 and the second output voltage V2 has been completed has reached a preset number (for example, five), the process of step S50 is performed next. If the preset number has not been reached, the processes of S10 to S40 are repeated until the number of completed reference workpieces 2A reaches the preset number. In addition, what is necessary is just to set arbitrarily the number of the reference | standard workpieces 2A which acquire 1st output voltage V1 and 2nd output voltage V2. As the number of the reference workpieces 2A increases, the reliability with respect to the reference value B set later increases, but the measurement costs more, so the practitioner may set it himself.

  In the above description, whether or not the reference workpiece 2A is actually a normal workpiece without grinding burn is obtained after acquiring the first output voltage V1 and the second output voltage V2 in steps S10 to S40. The corresponding reference workpiece 2A may be confirmed by performing a destructive inspection by etching, for example. Then, it is only necessary to use only the workpiece that has not actually been burned as the reference workpiece 2A, and use the first output voltage V1 and the second output voltage V2 corresponding thereto as the output voltage of the reference workpiece 2A. In addition, it is not restricted to the said aspect, Before performing the process of process S10 (1st acquisition process) and process S20 (2nd acquisition process), the confirmation test | inspection that it is a normal product was performed, and it was confirmed as a normal product A workpiece may be prepared as the reference workpiece 2A.

  In step S50 (reference value setting step), the reference value calculation unit 33 calculates and sets the reference value Bm. The reference value Bm is a reference value for determining the presence / absence of the entire range grinding burn over the entire range of the predetermined inspection area Ar1 of the workpiece 2B to be inspected. Specifically, first, average values Av1 and Av2 of the first output voltage V1 and the second output voltage V2 of the plurality of reference workpieces 2A stored in the first acquisition unit 32 are obtained. Then, a reference value B, which is the difference between the average value Av1 of the first output voltage V1 and the average value Av2 of each second output voltage V2 for each reference workpiece 2A, is calculated based on the above equation (1).

  The difference (reference value B) between the average values Av1 and Av2 obtained in this way is based on the first output voltage V1 and the second output voltage V2 of the normal reference workpiece 2A, and variations in the base material. The output voltage is eliminated by canceling the minutes. And let the largest difference be the reference value Bm used by this embodiment among a plurality of obtained differences (reference value B). The reference value Bm is output to the first determination unit 36 of the control device 30. Steps S10 to S50 are steps for setting the reference value Bm based on the first output voltage V1 and the second output voltage V2.

  Next, in step S60 (third acquisition step), the third output voltage V3 is acquired. For this reason, as in step S <b> 10, the control device 30 controls the supply unit 31 to supply the high-frequency excitation current Hi <b> 1 to the sensor head 12. Thereby, the sensor head 12 applies a magnetic field to a part of the predetermined inspection area Ar1 on the outer peripheral surface of the workpiece 2B, and induces an eddy current in the surface layer portion (inside) of the workpiece 2B.

  Then, the workpiece 2B and the sensor head 12 move relative to each other to generate a third output voltage V3 on the surface layer portion, and the sensor head 12 acquires the generated third output voltage V3. At this time, the third output voltage V3 of the workpiece 2B is an output voltage including only the variation due to the variation of the base material in the surface layer portion of the workpiece 2B, or the variation due to the variation of the base material and the variation due to grinding burn. is there. The acquired third output voltage V3 is input to the measuring device 13 via the sensor body 11. The third output voltage V3 acquired by the sensor head 12 is output to the second acquisition unit 34 of the control device 30 via the measurement device 13 and stored in the second acquisition unit 34.

  In step S70 (fourth acquisition step), immediately after the acquisition of the third output voltage V3 is completed in a part of the predetermined inspection area Ar1 on the outer peripheral surface of the workpiece 2B in step S60, the control device 30 supplies the supply unit 31. And the low-frequency excitation current Li1 is supplied to the sensor head 12. Thereby, the sensor head 12 applies a magnetic field to the inspection area Ar1 of the workpiece 2B, and induces an eddy current in the deep layer portion (inside) of the workpiece 2B.

  Then, when the workpiece 2B and the sensor head 12 are relatively moved, the fourth output voltage V4 is generated in the deep layer portion, and the sensor head 12 acquires the generated fourth output voltage V4. At this time, the fourth output voltage V4 is an output voltage including only a variation due to variations in the base material in the deep layer portion of the workpiece 2B. The acquired fourth output voltage V4 is input to the measurement device 13 via the sensor body 11. Thereafter, the acquired fourth output voltage V4 is output from the measurement device 13 to the second acquisition unit 34 of the control device 30 and stored in the second acquisition unit 34. In addition, in the above, you may reverse the process order of process S60 (3rd acquisition process) and process S70 (4th acquisition process).

  In step S80 (third confirmation step), as in step S30, acquisition of the third output voltage V3 and the fourth output voltage V4 in the third acquisition step S60 and the fourth acquisition step S70 is performed on the preset workpiece 2B. It is confirmed whether the process has been completed over the entire range of the predetermined inspection area Ar1 on the outer peripheral surface. In the present embodiment, the entire range is one round (360 degrees) in the circumferential direction of the outer peripheral surface of the workpiece 2B.

  If acquisition of the 3rd output voltage V3 and the 4th output voltage V4 is performed over the perimeter of the peripheral direction of an outer peripheral surface, processing of process S90 will be performed next. Unless the acquisition of the third output voltage V3 and the fourth output voltage V4 is performed over the entire circumference in the circumferential direction of the outer peripheral surface, it can be confirmed that it has been performed over the entire circumference in the step S80. The processes of S60 to S80 are repeated.

  In step S90 (average value calculation step), the average value calculation unit 35 acquires the third output voltage V3 and the fourth output voltage V4 from the second acquisition unit 34, and calculates the third output voltage V3 and the fourth output voltage V4. The average values Av3 and Av4 over the entire range (the entire outer periphery) are calculated. As described above, the steps S60 to S90 are steps for obtaining the average values Av3 and Av4 of the third output voltage V3 and the fourth output voltage V4.

  Next, in step S100 (first determination step), the first determination unit 36 determines the presence or absence of full-range grinding burn based on the reference value Bm and the average values Av3 and Av4. Specifically, the determination is made based on the magnitude of the reference value Bm and the difference between the average value Av3 and the average value Av4. That is, when the above formula (2) is satisfied, it is determined that the workpiece 2B has a full-range grinding burn (step S102). When the above formula (2) is not satisfied, it is determined that the workpiece 2B does not have the entire range grinding burn (step S104).

  At this time, as described above, the reference value Bm is data from which fluctuations due to variations in the base material are removed. For (| Av3 | − | Av4 |), the variation due to the variation of the base material is removed for the same reason as the reference value Bm. That is, since the determination is made based on the “reference value Bm” and “| Av3 | − | Av4 |” from which the variation due to the variation of the base material is removed, the variation due to the entire range grinding and burning that the average value Av3 has is excellent. It can be extracted and the presence / absence of grinding / burning of the entire range can be accurately determined.

  When it is determined in steps S100, S102, and S104 whether or not the entire range grinding burn of one workpiece 2B is determined, the next workpiece 2B is inspected for the presence of full range grinding burn. In this case, the process for the workpiece 2B may be started from step S60 (third acquisition step). And the process (process) from S10 to S104 is repeatedly carried out until the inspection of all the workpieces 2B requiring the inspection is completed. As described above, steps S100, S102, and S104 are steps for determining the entire range grinding burn based on the reference value B and the average values Av3 and Av4.

  In the above embodiment, the reference value is set in steps S10 to S50. However, the present invention is not limited to this mode. The reference value Bm may be set in any way. For example, it may be set in advance in another place and the set value may be used.

<2. Second embodiment>
(2-1. Outline of grinding burn inspection device)
Next, a second embodiment will be described with reference to FIGS. The grinding burn inspection apparatus 100 according to the second embodiment also accurately detects local grinding burns in which grinding burns occur in a part of the entire range of the outer peripheral surface of the workpiece 2B as compared with the first embodiment. It is an inspection device that can be used. For this reason, the grinding burn inspection apparatus 100 is added with a configuration for detecting local grinding burn with respect to the grinding burn inspection apparatus 1 of the first embodiment, and is otherwise the same as the grinding burn inspection apparatus 1. . Therefore, only the changing part will be described, and detailed description of other similar parts will be omitted. Moreover, about the same structure, the same code | symbol may be attached | subjected and demonstrated.

  When detecting local grinding burn, the inspection is performed using only the high-frequency excitation current Hi1. For this reason, it is simpler than the case where the full range grinding burn is detected using the high frequency excitation current Hi1 and the low frequency excitation current Li1 as in the grinding burn inspection device 1 of the first embodiment. Further, the local grinding burn can be detected at a higher speed than the grinding burn inspection apparatus 1 that uses the low-frequency excitation current Li1 to detect the entire range grinding burn. For this reason, in the second embodiment, in order to efficiently perform the inspection, after all the local grinding burns of the workpiece 2B are inspected, the entire range grinding burn is detected only for non-defective products that did not have the local grinding burn.

  The reason why the full-range grinding burn is detected only for a good product that has not been subjected to local grinding burn is because there is full-range grinding burn in the workpiece 2B determined as “no local grinding burn”. This is because there are cases in which local grinding burn is not determined. In other words, when the entire range grinding burn has occurred in the workpiece 2B, if the output value for each frequency is calculated by performing frequency analysis (Fast Fourier Transform (FFT)) on the fifth output voltage V5, the output value is normal. This is because the result may be the same as the product. Further, when detecting local grinding burn, it is not necessary for the workpiece to use a normal reference workpiece 2A having no grinding burn. Also in this respect, local grinding burn can be inspected in a short time.

  Generally, when there is grinding burn on the workpiece 2, the output voltage (induced electromotive force) decreases as described in the first embodiment. However, as described above, the output voltage also decreases due to variations in the base material. The inventor calculates the amplitude level (corresponding to the “output value” of the present invention) by analyzing the frequency of the output voltage obtained by inducing eddy current by the high-frequency excitation current Hi 1, and grinding the workpiece 2 and the base material. We found that the variation can be isolated. Therefore, the local grinding burn of the workpiece 2 is inspected based on the amplitude level obtained by frequency analysis of the output voltage detected by the grinding burn inspection apparatus 100.

(2-2. Details of grinding burn inspection device)
In the grinding burn inspection device 100, the control device 30 controls the supply unit 31, and supplies the high-frequency excitation current Hi1 to the sensor head 12 of the magnetic sensor 10 (corresponding to a sensor). The sensor head 12 sequentially applies a magnetic field to the entire range of the predetermined inspection area Ar1 of the workpiece 2B to be inspected (the entire circumference in the circumferential direction of the outer peripheral surface), and an eddy current is applied to the surface layer (inside) of the workpiece 2B. To induce. At this time, the sensor head 12 may or may not be in contact with the outer peripheral surface of the workpiece 2B.

  Then, the relative movement between the workpiece 2B and the sensor head 12 generates a fifth output voltage V5 on the surface layer portion, and the sensor head 12 acquires the generated fifth output voltage V5. The acquired fifth output voltage V5 is input to the measurement device 13 via the sensor body 11, and then output from the measurement device 13 to the first acquisition unit 32 of the control device 30 and stored in the first acquisition unit 32. The The fifth output voltage V5 is the same as the third output voltage V3 in the first embodiment.

  As shown in FIG. 4, the control unit 30 further includes an output value calculation unit 37, a storage unit 38, and a second determination unit 39. The output value calculation unit 37 is connected to the first acquisition unit 32 and the second determination unit 39. The output value calculation unit 37 acquires the waveform of the fifth output voltage V5 acquired by the magnetic sensor 10 from the first acquisition unit 32, performs frequency analysis, and calculates an amplitude level (output value) for each frequency. The output value calculation unit 37 outputs the calculated amplitude level (output value) to the second determination unit 39.

  The storage unit 38 is connected to the second determination unit 39. The storage unit 38 stores a threshold value of an amplitude level (output value) for determining whether or not the workpiece 2B is locally burned. The threshold value may be set by evaluating a normal product in advance and stored in the storage unit 38. As a method for setting the threshold, first, the waveform of the fifth output voltage V5 is subjected to frequency analysis (Fast Fourier Transform (FFT)) to obtain an amplitude level (output value) for each frequency. Then, this processing is performed on the plurality of workpieces 2B, and the maximum value among the acquired amplitude levels (output values) for the plurality of frequencies is set as a threshold (see FIG. 5).

  The second determination unit 39 is equal to or higher than the frequency F1 (see FIGS. 5 and 8) of the amplitude level (output value) for each frequency obtained by the output value calculation unit 37, and exceeds the threshold value read from the storage unit 38. In this case, it is determined that there is a local grinding burn in which a grinding burn of a predetermined amount or more occurs in a part of the entire range of the predetermined inspection area Ar1 in the surface layer portion of the workpiece 2B to be inspected.

(2-3. Local grinding burn inspection method)
As described above, in the second embodiment, all the workpieces 2B to be inspected are first inspected for local burn. Thereafter, the entire range grinding burn of the first embodiment is inspected. Since full-range grinding burn is the same as that of the first embodiment, description thereof is omitted. An inspection method for local grinding burn by the grinding burn inspection apparatus 100 will be described with reference to the flowchart of FIG.

  In step S110 (fifth acquisition step), the fifth output voltage V5 is detected and acquired. The acquisition method is as described above, and is the same as the acquisition method of the third output voltage V3. At this time, the fifth output voltage V5 is an output voltage including only a variation due to the variation of the base material in the surface layer portion of the workpiece 2B, or a variation due to the variation of the base material and a variation due to grinding burn.

  The acquired fifth output voltage V5 is input to the measuring device 13 via the sensor body 11. Thereafter, the acquired fifth output voltage V <b> 5 is output from the measurement device 13 to the first acquisition unit 32 of the control device 30 and stored in the first acquisition unit 32.

  In step S120 (calculation step), the waveform of the fifth output voltage V5 shown in FIG. 7 is subjected to frequency analysis (Fast Fourier Transform (FFT)) to calculate an output value for each frequency. Of the waveform of the fifth output voltage V5 indicated by the one-dot chain line in FIG. 7, portions B11, B12, and B13 whose values are decreasing show fluctuations due to variations in the base material, and the value of the fifth output voltage V5 decreases. The portions A11, A12, A13, and A14 that are present indicate fluctuations due to grinding burn. As described above, the waveform of the fifth output voltage V5 includes the variation due to the variation of the base material and the variation due to the grinding burn. Therefore, the reaction due to the variation of the base material and the grinding burn only with the waveform of the fifth output voltage V5. It is difficult to distinguish the reaction due to.

  FIG. 8 shows the amplitude level (output value) for each frequency of the workpiece 2B obtained by fast Fourier transform of the fifth output voltage V5 (induced electromotive force) shown in FIG. And the control apparatus 30 compares an amplitude level and a threshold value in the frequency area | region of 1 Hz or more.

  In step S130 (second determination step), when the amplitude level (output value) for each frequency exceeds a preset threshold value, in step S140, the workpiece 2B has the entire range of the predetermined inspection area Ar1 in the surface layer portion. It is determined that a part of (the entire outer peripheral surface) has a local grinding burn of a predetermined amount or more. If the amplitude level does not exceed the threshold value, it is determined in step S150 that there is no local grinding burn.

  However, as described above, in the step S150, the workpiece 2B determined as “no local grinding burn” may include a workpiece having the entire range grinding burn. In other words, when the entire range grinding burn has occurred in the workpiece 2B, if the output value for each frequency is calculated by performing frequency analysis (Fast Fourier Transform (FFT)) on the fifth output voltage V5, the output value is normal. The result may be equivalent to the product.

  Therefore, after all the inspections of the local grinding burn of the workpiece 2B are completed, only the workpiece 2B which has been determined to be a good product without the local grinding burn in step S150 is subjected to the full-range grinding burn described in the first embodiment. Perform an inspection. Thereby, all the local grinding burns and all-range grinding burns can be detected. As described above, the grinding burn inspection apparatus 100 can detect the local grinding burn on the workpiece 2B in a short time by the processes of steps S110 to S150.

<3. Other>
In addition, according to said 1st, 2nd embodiment, although the workpiece 2 was a cylindrical or column-shaped member, it is not restricted to this, An output voltage is acquired by the sensor head 12, and grinding burning is carried out. As long as the inspection can be performed, it may be formed in any shape. For example, the workpiece 2 may be a planar member. Moreover, the member which has a wavy surface may be sufficient. Also by these, the same effect as the above-mentioned embodiment is acquired.

  Moreover, according to said 1st embodiment, the sensor head 12 demonstrated as what acquires an output voltage in the state which always contacted the workpiece 2. FIG. However, it is not limited to this aspect. The sensor head 12 may be of a type that acquires an output voltage in a non-contact state with the workpiece 2. This also provides a reasonable effect.

  In the grinding burn inspection method of the second embodiment, it has been described that the inspection of the entire range grinding burn is performed after the inspection of the local grinding burn is completed. This is because local grinding burns are more likely to occur than full-range grinding burns, so that abnormal products can be efficiently extracted by inspecting local grinding burns first. However, depending on various conditions such as processing conditions, the full-range grinding burn may be more likely to occur than the local grinding burn. In such a case, the full-range grinding burn inspection may be performed prior to the local grinding burn inspection. In other words, after the entire range grinding burn inspection is performed first, the local grinding burn inspection may be performed on the workpiece 2B determined to be non-defective.

  Further, in the grinding burn inspection method of the second embodiment, when performing the local grinding burn inspection, the threshold value is set in another place, and the set value is stored in the storage unit 38 for inspection. . However, it is not limited to this aspect. The threshold value may be set in the process of the grinding burn inspection method.

<4. Effects according to the embodiment>
According to the above-described embodiment, the grinding burn inspection method generates an eddy current by an exciting current in the ground workpiece 2B to be inspected, and inspects the inspection object based on the output voltage corresponding to the generated eddy current. The presence or absence of grinding burn in the surface layer portion of the processed part of the workpiece is determined. A first acquisition step S10 for acquiring a first output voltage V1 when an eddy current is generated by a high-frequency excitation current Hi1 inside a predetermined position of the reference workpiece 2A that does not have grinding burn, and a reference workpiece 2A The second acquisition step S20 for acquiring the second output voltage V2 when the eddy current is generated by the low frequency excitation current Li1 in the predetermined position P1, and the first output voltage V1 and the second output voltage V2. A reference value setting step S50 for setting a reference value Bm for determining whether or not the entire range of grinding burn is generated over the entire range of the predetermined inspection area Ar1 of the workpiece 2B to be inspected, and the inspection target A third acquisition step S60 for acquiring a third output voltage V3 when an eddy current is generated by the high-frequency excitation current Hi1 within the entire range of the predetermined inspection area Ar1 of the workpiece 2B, and the workpiece 2 to be inspected A fourth acquisition step S70 for acquiring the fourth output voltage V4 when the eddy current is generated by the low frequency excitation current Li1 within the entire range of the predetermined inspection area Ar1, the reference value Bm, and the third output voltage V3. First determination step S100 for determining the presence or absence of the entire range grinding burn based on the average value Av3 and the average value Av3 of the fourth output voltage V4.

  As described above, the first output in the surface layer portion obtained according to the eddy current generated in the predetermined position P1 (surface layer portion) of the reference workpiece 2A without grinding burn by the high frequency excitation current Hi1 and the low frequency excitation current Li1. Based on the voltage V1 and the second output voltage V2 in the deep layer portion that is deeper than the surface layer portion, a reference value Bm for determining the presence or absence of full-range grinding burn is set. Further, for the workpiece 2B to be inspected, the third output voltage V3 corresponding to the first output voltage V1 and the fourth output voltage V4 corresponding to the second output voltage V2 are the same as the reference workpiece 2A. To get. At this time, the first output voltage V1 and the third output voltage V3 are output voltages at the surface layer portion of the workpiece.

  For this reason, the first output voltage V1 is an output voltage including a variation due to variations that differ for each base material. The third output voltage V <b> 3 is an output voltage including a variation due to variation different for each base material and a variation due to grinding burn when grinding burn occurs in the surface layer portion. Therefore, when the first output voltage V1 is used as a reference value and an attempt is made to determine whether or not the entire range of the workpiece 2B is burned by grinding by comparing the reference value with the third output voltage V3, the base material of the surface layer of the workpiece 2B It is difficult to distinguish between the fluctuation due to variation and the fluctuation due to grinding burn generated in the surface layer portion, and it is difficult to accurately determine the entire range grinding burn.

  However, in the present invention, when setting the reference value, not only the first output voltage V1 but also the second output voltage V2 in the deep layer portion including only the variation due to the variation in the base material is used to determine whether or not the entire range is ground and burned. Used for judgment. Further, the output voltage acquired from the workpiece 2B for comparison with the reference value Bm is not only the third output voltage V3 but also the fourth output voltage V4 that is not affected by grinding burn and includes only the variation due to the variation of the base material. Also used together.

  Therefore, the reference value Bm can be set as the reference value Bm that cancels out the variation due to the variation of the base material based on the first output voltage V1 and the second output voltage V2. The output voltage acquired from the workpiece 2B to be inspected for comparison with the reference value Bm is also based on the third output voltage V3 and the fourth output voltage V4. Is possible. That is, since the presence or absence of the entire range grinding burn in the surface layer portion is determined based on the reference value Bm and the output voltage (based on the third output voltage V3 and the fourth output voltage V4) that do not include fluctuation due to the variation of the base material. Accurate determination results that are not affected by variations in the base material can be obtained.

  Further, according to the inspection method of the above embodiment, in the reference value setting step S50, the reference value Bm is set based on the average value Av1 of the first output voltage V1 and the average value Av2 of the second output voltage V2. As a result, the reference value Bm can be easily set, and even if there are specific points in a part of the first output voltage V1 and the second output voltage V2, it can be set favorably as the reference value Bm.

  Further, according to the inspection method of the above embodiment, in the first determination step S100, depending on the magnitude of the reference value Bm and the difference between the average value Av3 of the third output voltage V3 and the average value Av4 of the fourth output voltage V4. Determine if there is grinding burn on the entire area. As a result, the reference value Bm is compared with the difference in a state in which the variation due to the variation in the base material is removed, so that an accurate determination result of the entire range grinding burn can be obtained.

  Further, according to the inspection method of the above embodiment, the reference workpiece 2A and the workpiece 2B to be inspected are columnar or cylindrical, and the machining site is the outer peripheral surface. Thereby, since the output voltage can be acquired in a stable state while rotating the workpiece around the axis, an accurate determination result can be obtained.

  Further, according to the grinding burn inspection method of the second embodiment, compared to the first embodiment, an eddy current is further generated by the high frequency excitation current Hi1 inside the entire inspection area Ar1 of the workpiece 2B to be inspected. A fifth acquisition step S110 for acquiring the fifth output voltage V5 when the signal is generated, a calculation step S120 for calculating an output value for each frequency by frequency analysis of the waveform of the fifth output voltage V5, and an output value for each frequency When the value exceeds a threshold value for each frequency corresponding to the output value, a local area where grinding burn of a predetermined amount or more occurs in a part of the entire range of the predetermined inspection area Ar1 in the surface layer portion of the workpiece 2B to be inspected. A second determination step S130 for determining that there is grinding burn. Thereby, even if there is variation in the base material of the workpiece 2B, the local grinding burn can be detected with high accuracy.

  In addition, according to the above embodiment, the grinding burn inspection devices 1 and 100 generate an eddy current by an excitation current inside the ground workpiece to be inspected, and based on the output voltage corresponding to the generated eddy current. Then, the presence or absence of grinding burn in the surface layer portion of the processed part of the workpiece to be inspected is determined. The grinding burn inspection devices 1 and 100 include a magnetic sensor 10 (sensor) and a control device 30 (control unit).

  The magnetic sensor 10 includes a first output voltage V1 when an eddy current is generated by a high frequency excitation current Hi1 and a low frequency excitation current Li1 in a predetermined position P1 of the reference workpiece 2A that does not have grinding burn. A third case in which the second output voltage V2 is acquired and an eddy current is generated by the high frequency excitation current Hi1 and the low frequency excitation current Li1 within the entire range of the predetermined inspection area Ar1 of the workpiece 2B to be inspected. The output voltage V3 and the fourth output voltage V4 are acquired.

  Further, the control device 30 (control unit) grinds over the entire range of the predetermined inspection area Ar1 of the workpiece 2B to be inspected based on the first output voltage V1 and the second output voltage V2 acquired by the magnetic sensor 10. A reference value calculation unit 33 for calculating the reference value Bm for determining whether or not there is a full range grinding burn in which burning occurs, and average values Av3 of the third output voltage V3 and the fourth output voltage V4 acquired by the magnetic sensor 10 , Av4 is calculated, and the whole range grinding burn is determined based on the calculated reference value Bm and the average values Av3, Av4 of the third output voltage V3 and the fourth output voltage V4. A first determination unit 36. Thereby, in the inspection result of the workpiece 2B obtained by the grinding burn inspection apparatus 1,100, an effect equivalent to the effect on the inspection result of the workpiece 2B obtained by the grinding burn inspection method can be obtained.

  Further, according to the grinding burn inspection device 100 of the second embodiment, the magnetic sensor 10 (sensor) is a predetermined inspection region Ar1 of the workpiece 2B to be inspected, compared to the grinding burn inspection device 1 of the first embodiment. The fifth output voltage V5 is obtained when an eddy current is generated by the high-frequency excitation current Hi1 within the entire range. The control device 30 (control unit) corresponds to an output value calculation unit 37 that performs frequency analysis on the waveform of the fifth output voltage V5 acquired by the magnetic sensor 10 (sensor) and calculates an output value for each frequency, and the output value. A storage unit 38 for storing a threshold value for each frequency to be performed, and a surface layer portion of the workpiece 2B to be inspected when an output value for each frequency exceeds a threshold value for each frequency corresponding to the output value stored in the storage unit 38 And a second determination unit 39 that determines that there is local grinding burn in which a predetermined amount or more of grinding burn is generated in a part of the entire range of the predetermined inspection area Ar1. Thereby, in the inspection result of the workpiece 2B obtained by the grinding burn inspection apparatus 100, an effect equivalent to the effect on the inspection result of the workpiece 2B obtained by the grinding burn inspection method of the second embodiment is obtained.

  DESCRIPTION OF SYMBOLS 1,100 ... Grinding burn inspection apparatus 2, 2A, 2B ... Workpiece, 10 ... Sensor (magnetic sensor), 30 ... Control part (control apparatus), 31 ... Supply part, 32 ... First acquisition unit, 33 ... Reference value calculation unit, 34 ... Second acquisition unit, 35 ... Average value calculation unit, 36 ... First determination unit, 37 ... Output Value calculation unit, 38 ... storage unit, 39 ... second determination unit, Ar1 ... inspection region, Av1, Av2, Av3, Av4 ... average value, Bm ... reference value, Hi1 ...・ High frequency excitation current, Li1 ... Low frequency excitation current, P1 ... Position, S10 ... First acquisition step, S20 ... Second acquisition step, S50 ... Reference value setting step, S60 ... -Third acquisition step, S70 ... Fourth acquisition step, S90 ... Average value calculation step S100 ... first determination step, S110 ... fifth acquisition step, S120 ... calculation step, S130 ... second determination step, V1 ... first output voltage, V2 ... second output Voltage, V3 ... third output voltage, V4 ... fourth output voltage, V5 ... fifth output voltage.

Claims (7)

An eddy current is generated by an excitation current in the ground workpiece to be inspected, and the grinding burn in the surface layer portion of the processing site of the workpiece to be inspected is generated based on the output voltage corresponding to the generated eddy current. A method for inspecting grinding burn to determine presence or absence,
A first acquisition step of acquiring a first output voltage when the eddy current is generated by a high-frequency excitation current inside a predetermined position of a reference workpiece having no grinding burn;
A second acquisition step of acquiring a second output voltage when the eddy current is generated by a low-frequency excitation current inside the predetermined position of the reference workpiece;
Based on the first output voltage and the second output voltage, a reference value for determining the presence or absence of full-range grinding burn in which grinding burn occurs over the entire range of a predetermined inspection region of the workpiece to be inspected. A reference value setting process to be set;
A third acquisition step of acquiring a third output voltage when the eddy current is generated by the high-frequency excitation current inside the entire range of the predetermined inspection area of the workpiece to be inspected;
A fourth acquisition step of acquiring a fourth output voltage when the eddy current is generated by the low frequency excitation current inside the entire range of the predetermined inspection region of the workpiece to be inspected;
Based on the reference value, the average value of the third output voltage and the average value of the fourth output voltage, a first determination step of determining the presence or absence of the entire range grinding burn,
A grinding burn inspection method for a workpiece, comprising: In the reference value setting step,
2. The grinding burn inspection method for a workpiece according to claim 1, wherein the reference value is set based on an average value of the first output voltage and an average value of the second output voltage. In the first determination step,
The workpiece according to claim 1, wherein presence or absence of the entire range grinding burn is determined based on a magnitude between the reference value and a difference between an average value of the third output voltage and an average value of the fourth output voltage. Grinding burn inspection method.   The grinding burn inspection method for a workpiece according to any one of claims 1 to 3, wherein the reference workpiece and the workpiece to be inspected are columnar or cylindrical, and the processed portion is an outer peripheral surface. . The grinding burn inspection method is:
further,
A fifth acquisition step of acquiring a fifth output voltage when the eddy current is generated by the high-frequency excitation current inside the entire range of the predetermined inspection area of the workpiece to be inspected;
A calculation step of calculating an output value for each frequency by frequency analysis of the waveform of the fifth output voltage;
When the output value for each frequency exceeds a threshold value for each frequency corresponding to the output value, a predetermined amount is included in a part of the entire range of the predetermined inspection region in the surface layer portion of the workpiece to be inspected A second determination step for determining that there is local grinding burn in which the above grinding burn occurs;
A grinding burn inspection method for a workpiece according to claim 1, comprising: An eddy current is generated by an excitation current in the ground workpiece to be inspected, and the grinding burn in the surface layer portion of the processing site of the workpiece to be inspected is generated based on the output voltage corresponding to the generated eddy current. A grinding burn inspection device for determining the presence or absence of
The grinding burn inspection device includes a sensor and a control unit,
The sensor is
While obtaining a first output voltage and a second output voltage when the eddy current is generated by a high frequency excitation current and a low frequency excitation current inside a predetermined position of a reference workpiece that does not have grinding burn, Acquire the third output voltage and the fourth output voltage when the eddy current is generated by the high-frequency excitation current and the low-frequency excitation current within the entire range of the predetermined inspection area of the workpiece to be inspected. And
The controller is
Based on the first output voltage and the second output voltage acquired by the sensor, it is determined whether or not there is a full range grinding burn in which grinding burn occurs over the entire range of a predetermined inspection region of the workpiece to be inspected. A reference value calculation unit for calculating a reference value for
An average value calculation unit for calculating each average value of the third output voltage and the fourth output voltage acquired by the sensor;
A first determination unit that determines the presence or absence of the entire range grinding burn based on the calculated reference value and the average values of the third output voltage and the fourth output voltage;
A grinding burn inspection device for workpieces. In the grinding burn inspection device,
further,
The sensor is
Obtaining a fifth output voltage when the eddy current is generated by the high-frequency excitation current within the entire range of the predetermined inspection area of the workpiece to be inspected;
The controller is
An output value calculation unit that performs frequency analysis on the waveform of the fifth output voltage acquired by the sensor and calculates an output value for each frequency;
A storage unit for storing a threshold value for each frequency corresponding to the output value;
When the output value for each frequency exceeds the threshold value for each frequency corresponding to the output value stored in the storage unit, all of the predetermined inspection area in the surface layer part of the workpiece to be inspected A second determination unit that determines that there is a local grinding burn in which a predetermined amount or more of the grinding burn occurs in a part of the range;
A grinding burn inspection device according to claim 6, comprising: