JP2016164538A - Hardened layer depth measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hardened layer depth measurement device that offers improved measurement accuracy.SOLUTION: A detection coil 2 comprises a detection core portion 21 to be placed on a work W between legs 111 that form an excitation core portion 11, and a detection coil portion 22 wound around the detection coil portion 21. Where a dimension "a" is in a vertical direction to a surface of the work W, a dimension "b" is perpendicular to the vertical direction, and a dimension "c" is perpendicular to the dimensions "a" and "b", the detection core portion 21 is wound by the detection coil portion along a direction of the dimension "c", and the dimension "a" is smaller than the dimension "b".SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hardened layer depth measuring device that measures the depth of a hardened layer formed on a surface by quenching a workpiece.

In order to increase the strength of the metal, it is known to harden the workpiece such as steel by induction hardening. By hardening the workpiece, a hardened layer is formed on the workpiece surface.
Since mechanical properties change according to the depth of the hardened layer, quenching is performed under preset processing conditions, and quality inspection after manufacturing is performed. Conventionally, as a method for inspecting whether or not the workpiece has been properly quenched, there has been a method for inspecting an arbitrarily extracted workpiece. In this method, inspection takes time and inspection is performed. The target workpiece cannot be used as a product.

As a device for measuring the depth of the hardened layer formed on the surface of the workpiece, a magnetizer that magnetizes the workpiece, a detection coil that detects an induced magnetic field generated by the magnetizer, an output voltage value of the detection coil, and the workpiece There is a conventional example provided with a quenching depth specifying means for deriving the quenching depth of a workpiece from known magnetic property information on an equivalent material (Patent Document 1).
In the conventional example of Patent Document 1, the magnetizer has a structure in which a coil for excitation is wound around a portion of the yoke that is U-shaped in a side view and faces a workpiece, and a detection coil is provided at the leg of the yoke. It has been.

International Publication No. 2012/057224

In the conventional example of Patent Document 1, the yoke has a gate shape having a pair of legs whose opening side faces the workpiece and a base that connects the legs. When an electric current is passed through the excitation coil provided at the base, the magnetic flux flows in the order of one leg, the workpiece, the other leg, and the base. Along with this, a spatial magnetic flux is generated near the surface of the workpiece.
When detecting the spatial magnetic flux with the detection coil, since the detection coil is provided at the base of one leg of the yoke, not only the spatial magnetic flux but also the magnetic flux generated inside the yoke will be detected. Is not enough.
Therefore, a hardened layer depth measuring device that can further improve the measurement accuracy is desired.

  The objective of this invention is providing the hardened layer depth measuring apparatus which can improve a measurement precision.

In order to improve the measurement accuracy, the present inventor considered separating the detection coil and the excitation coil and arranging the detection coil on the workpiece, and further proceeded to examine the configuration of the detection coil and the excitation coil. It came.
Here, as the hardened layer depth increases, the value of the detection voltage detected by the detection coil increases. In order to further improve the detection accuracy, it is important to increase the slope of the calibration curve indicated by the effective hardened layer depth and the detection voltage. By increasing the slope of the calibration curve, the hardened layer depth can be easily separated.
In order to increase the slope of the calibration curve, the present inventor conducted various simulations and experiments. First, it was considered to change only the size of the detection coil, but it was not possible to accurately measure the hardened layer depth. Thus, as a result of examining the shape of the detection core portion of the detection coil, a preferable result could be obtained by making the vertical dimension a of the detection core portion smaller than the dimension b.

  The hardened layer depth measuring device of the present invention is a device for measuring the depth of a hardened layer formed on the surface by quenching a work, and generates an magnetic flux to magnetize the work, and the excitation A detection coil that detects a magnetic flux generated by the coil, and the excitation coil includes a portal-shaped excitation core portion having a leg end facing the workpiece, and an excitation wound around the excitation core portion. A coil portion for detection, and the detection coil is disposed between the leg portions of the excitation core portion, the detection core portion disposed on the workpiece, and the detection coil wound around the detection core portion A coil portion, and the detection core portion has a dimension perpendicular to the surface of the workpiece as a, a dimension perpendicular to the perpendicular direction as b, and the dimension a and the dimension b. If the dimension orthogonal to each is c, along the direction of the dimension c Serial detection coil portion is wound, dimension a is characterized by less than the dimension b.

In the present invention, when a current is passed through the exciting coil section, a magnetic flux is generated inside the portal-shaped exciting core and the workpiece, and a spatial magnetic flux is generated on the surface of the workpiece along with the magnetic flux. This spatial magnetic flux is detected by a detection coil. The voltage detected by the detection coil differs depending on the depth of the hardened layer formed on the workpiece surface, and the depth of the hardened layer is measured based on this detected voltage.
In other words, in the present invention, when the detection coil portion is wound along the dimension c, the dimension a is smaller than the dimension b, so that the spatial magnetic flux can be easily detected by the detection coil, and the measurement accuracy is further improved. It will be.

In the hardened layer depth measuring apparatus, the detection core part is preferably formed in a rectangular parallelepiped shape.
With this configuration, the detection core can be easily manufactured.

In the hardened layer depth measuring device, the dimension a is preferably 1.2 mm or less.
The inventor of the present application changed the lengths of the dimension a, the dimension b, and the dimension c, and verified the measurement accuracy. As a result, even if the dimension b and the dimension c were changed, the measurement accuracy was not greatly affected, but it was found that the measurement accuracy was greatly changed by changing the dimension a. In this case, it has been experimentally found that the measurement accuracy improves as the dimension a decreases.
When the dimension a exceeds 1.2 mm, the detection coil becomes large, and accordingly, the excitation coil also becomes large.

In the hardened layer depth measuring apparatus, it is preferable that the detection core portion is composed of a non-oriented electrical steel sheet.
In this configuration, the non-oriented electrical steel sheet has uniform magnetic characteristics in all directions, so that the measurement accuracy can be improved also from this point.

BRIEF DESCRIPTION OF THE DRAWINGS The whole hardened layer depth measuring apparatus concerning one Embodiment of this invention is shown, (A) is a front view, (B) is a side view. The expansion perspective view of a detection coil. It is a figure for demonstrating the flow of the magnetic flux of a hardened layer depth measuring apparatus, (A) is a figure in case the hardened layer is formed in the surface of a workpiece | work, (B) is a hardened layer formed in the surface of a workpiece | work. Figure if not. The perspective view which shows the simulation model of a hardened layer depth measuring apparatus. (A) (B) (C) is a graph which shows the relationship between a hardening layer depth and a change rate, respectively as a simulation result. Schematic of the hardened layer depth measuring apparatus used in experiment. Schematic which shows an experimental apparatus. (A) is a graph of a calibration curve showing the relationship between the effective hardened layer depth determined by the first experiment and the detected voltage, and (B) is the effective hardened layer depth determined by the second experiment and the detected voltage. It is a graph of a calibration curve showing the relationship.

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of a cured layer depth measuring apparatus according to this embodiment.
FIG. 1 (A) shows the front surface of the cured layer depth measuring device, and FIG. 1 (B) shows the side surface of the cured layer depth measuring device.
1A and 1B, a hardened layer depth measuring device is a device for measuring the depth of a hardened layer H formed on the surface by quenching a workpiece W, and an exciting coil 1 for generating magnetic flux. And a detection coil 2 that detects the magnetic flux generated by the excitation coil 1 and a holding member 3 that holds the excitation coil 1 and the detection coil 2 together.

The exciting coil 1 magnetizes the workpiece W, and includes a portal-shaped exciting core portion 11 in front view and an exciting coil portion 12 provided in the exciting core portion 11.
The exciting core portion 11 has a pair of leg portions 111 whose front end faces the workpiece W, and a base portion 110 that connects the base end portions of the leg portions 111, and the material is a U-shaped plane. Or a soft magnetic body having the same shape.
The length along the surface of the workpiece W in front of the exciting core 11 is l, the dimension in the direction perpendicular to the surface of the workpiece W is m, and the width of the leg 111 is n.
The exciting coil unit 12 is wound around the base 110, and the end thereof is connected to a power supply device (not shown).

The detection coil 2 includes a rectangular parallelepiped detection core portion 21 disposed between the leg portions 111 of the excitation core portion 11 and a detection coil portion 22 wound around the detection core portion 21.
The detection core portion 21 is a laminate of a plurality of planar rectangular silicon steel plates or a soft magnetic body having the same shape. FIG. 2 shows an enlarged view of the detection coil 2.
In FIG. 2, the detection core 21 has a dimension perpendicular to the surface of the workpiece W (see FIG. 1), a dimension perpendicular to the vertical direction, b, dimension a and dimension b. When each orthogonal dimension is c, the detection coil portion 22 is wound along the length direction of the dimension c. Here, the dimension a, the dimension b, and the dimension c are in a relationship of a <c, b <c.
In FIG. 1, the detection core portion 21 is arranged on the workpiece W so that the length direction thereof is along the length direction of the base portion 110 at an intermediate position between the pair of leg portions 111.
The positions of the detection core 21 and the surface of the workpiece W are set as appropriate, but the detection core 21 is preferably in contact with the surface of the workpiece W.
The detection coil unit 22 is wound along the length direction of the detection core unit 21, and its end is connected to an arithmetic device (not shown). The calculation device calculates the depth of the hardened layer H of the workpiece W based on the voltage (signal) output from the detection coil unit 22.

A part of the outer peripheral surface of the holding member 3 is formed along the cross-sectional shape of the workpiece W. In the present embodiment, the holding member 3 is formed in a cylindrical shape having a semicircular cross section.
A part of the exciting coil portion 12 is exposed from the surface of the holding member 3 that forms a semicircular string. The detection coil 2 is arranged so as to be flush with a tangent of a predetermined point on the arc surface of the holding member 3.
The holding member 3 is made of an epoxy resin or other synthetic resin.
In the present embodiment, the holding member 3 has a positioning portion 3A for positioning with respect to the workpiece W. The shape of the positioning portion 3 </ b> A is appropriately set in relation to the shape with the workpiece W, but may be a protrusion along the axial direction of the exciting coil portion 12, for example.

Next, the measurement principle of this embodiment will be described with reference to FIG. FIG. 3 is a diagram for explaining the flow of magnetic flux of the hardened layer depth measuring apparatus. In addition, illustration of the holding member 3 is abbreviate | omitted in FIG.
FIG. 3A shows the case where the hardened layer H is formed on the surface of the workpiece W. The hardened layer H of the workpiece W has a lower magnetic permeability than the non-hardened layer. In the workpiece W having the hardened layer H formed on the surface, when the exciting coil portion 12 is energized, a large magnetic flux M1 is generated along the U-shaped front shape of the exciting core portion 11, and a closed loop is formed together with the magnetic flux M1. The magnetic flux M21 which comprises is generated. The magnetic flux M21 is generated only in the hardened layer H having a low magnetic permeability, and is smaller than the magnetic flux M1.

FIG. 3B shows a case where a hardened layer is not formed on the surface of the workpiece W. The entire magnetic permeability including the surface of the workpiece W is uniform. In the workpiece W, when the exciting coil portion 12 is energized, a large magnetic flux M1 is generated along the U-shaped front shape of the exciting core portion 11, and a magnetic flux M22 constituting a closed loop is generated together with the magnetic flux M1. Since the workpiece W has a uniform magnetic permeability regardless of the depth, the magnetic flux M22 is generated not only on the surface of the workpiece W. Therefore, the magnetic flux M22 is the same size as the magnetic flux M1.
Regardless of the presence or absence of the hardened layer H, a spatial magnetic flux N1 is generated on the surface of the workpiece W along with the magnetic flux M1. Although the spatial magnetic flux N1 is detected by the detection coil 2, the spatial magnetic flux N1 is large in the work W on which the hardened layer H is formed on the surface, and is small in the work W on which the hardened layer H is not formed on the surface. That is, the magnitude of the spatial magnetic flux N1 changes in proportion to the depth of the hardened layer H, and the depth of the hardened layer H can be measured by detecting this with the detection coil 2.

Based on FIG. 4, it will be described by simulation that the measurement accuracy of the depth of the hardened layer H of the workpiece W can be improved by specifying the shape of the detection core portion 21.
FIG. 4 shows a state in which the hardened layer depth measuring device is mounted on the workpiece W. In the hardened layer depth measuring apparatus shown in FIG. 4, only half of the exciting coil 1 is shown.
Conditions for simulation Work W: A work W having grooves with different depths of the hardened layer H is assumed.
The hardened layer depth is 2mm shallow model and 4mm deep model.
Excitation coil 1:
Excitation core 11: silicon steel plate
Length 30mm x Height 15mm
Leg width: 5mm

Detection coil 2:
Detection core 21: Silicon steel plate (non-oriented electrical steel plate)
Dimensional change condition: Pattern for examining the effect of dimension a: See Table 1
Pattern for studying the effect of dimension b: see Table 2
Pattern for studying the effect of dimension c: see Table 3 Excitation conditions: 20 Hz, 0.5 A
Analysis method: 3D frequency response analysis Electromagnetic characteristics: See Table 4

The result of the simulation performed under the above conditions is shown in FIG.
FIG. 5 is a graph showing the relationship between the cured layer depth and the rate of change as a simulation result. Here, the rate of change is {(detection voltage of deeper product−detection voltage of shallower product) / detection voltage of shallower product} × 100 [%].
5A shows the influence of the dimension a, FIG. 5B shows the influence of the dimension b, and FIG. 5C shows the influence of the dimension c.
FIG. 5A shows the result of simulation performed under the conditions shown in Table 1. The change rate when the dimension a is 0.4 mm is indicated by P1, the change rate when the dimension a is 0.8 mm is indicated by P2, and the change rate when the dimension a is 1.2 mm is indicated by P3.

As shown in FIG. 5A, the slope of the graph of the change rate P1 is the largest, the slope of the graph of the change rate P3 is the smallest, and the slope of the graph of the change rate P2 is between these.
In general, in order to improve measurement accuracy, it is preferable that the detection voltage and the cured layer depth have a proportional relationship in which the detected voltage increases linearly as the cured layer depth increases. Thus, when there is a proportional relationship between the detection voltage and the hardened layer depth, the hardened layer depth can be separated from the detected voltage. On the other hand, when the detection voltage does not change even when the hardened layer depth is deep, or when the detection voltage decreases when the hardened layer depth is deep, the hardened layer depth cannot be separated from the detection voltage.

From the above, it can be seen that the measurement accuracy improves as the dimension a decreases.
This is because when the dimension a is reduced, the amount of the magnetic flux floating in the space entering the detection core portion 21 is reduced, and the ratio of the magnetic flux leaking from the workpiece W is relatively increased.
On the contrary, if the dimension a is larger than 1.2 mm, the inclination of the graph becomes small, and not only the measurement accuracy cannot be sufficiently improved, but also the detection coil 2 becomes large and the apparatus cannot be sufficiently downsized. . When the dimension a is smaller than 0.4 mm, it can be easily assumed that the measurement accuracy is improved as compared with the case of 0.4 mm, but when the dimension a is smaller than 0.2 mm, the detection core portion 21 is manufactured. It becomes difficult.

FIG. 5B shows the result of simulation performed under the conditions shown in Table 2. The change rate when the dimension b is 0.75 mm is indicated by Q1, the change rate when it is 1.5 mm is indicated by Q2, and the change rate when it is 3.0 mm is indicated by Q3.
As shown in FIG. 5B, the slope of the graph of the change rate Q1 is small, the slope of the graph of the change rate Q3 is large, and the slope of the graph of the change rate Q2 is between them, but the difference between these is slight. It is.
Therefore, although the degree of influence of the dimension b is somewhat low, the rate of change slightly increases as the dimension b increases.
This is because when the dimension b is shortened, the gap with the workpiece W is reduced at both ends of the detection core portion 21, and the magnetic flux leaking from the workpiece W is likely to enter the detection core portion 21 to detect a change in the hardened layer depth. It is because it seems that it became easy to do.

FIG. 5C shows the result of simulation performed under the conditions shown in Table 3. The rate of change when the dimension c is 5.5 mm is indicated by R1, the rate of change when the dimension is 7.5 mm is indicated by R2, and the rate of change when the dimension c is 9.5 mm is indicated by R3.
As shown in FIG. 5C, the change rate R1, the change rate R2, and the change rate R3 are substantially on the same line.
Therefore, there is almost no influence of the dimension c.
This is because even if the dimension c changes, the ratio of the magnetic flux floating in the space to the magnetic flux leaking from the work W and the gap between the detection core portion 21 and the work W are considered to be substantially unchanged.

An experiment will explain that the depth of the hardened layer H of the workpiece W can be measured by the hardened layer depth measuring device of the present embodiment.
In this experiment, a plurality of workpieces W having different depths of the hardened layer H were prepared, and the detected voltage was measured with a hardened layer depth measuring device.
FIG. 6 shows a state in which the hardened layer depth measuring device used in the experiment is mounted on the workpiece W.
In FIG. 6, the workpiece W used in the experiment is a groove machining workpiece, and the cross-sectional shape thereof has a substantially semicircular inner peripheral surface. A concave guide groove WG is provided on a straight line WL passing through the center O of the semicircular inner circumference and orthogonal to the chord. In this experiment, two positions B and C that are separated from each other by a predetermined angle α (45 °) with respect to the straight line WL connecting the circle center O and the guide groove WG are measurement positions.

[Work W]
Target work: Grooving work Material: Carbon steel Limit hardness: 446HV
Work level: Hardened layer H is shallow, usually 3 patterns in total.
Effective hardened layer depth specification:
Work W with a hardened layer H shallow:
Effective hardened layer depth at point B 3.15mm
Effective hardened layer depth at point C 2.71 mm
Hardened layer H is normal work W:
Effective hardened layer depth at point B 3.25 mm
Effective hardened layer depth at point C 3.04mm
Work W with deep hardened layer H:
Effective hardened layer depth at point B 3.77 mm
Effective hardened layer depth at point C 3.74mm
Here, the effective hardened layer depth refers to a depth corresponding to the limit hardness from the surface.

[Hardened layer depth measuring device]
Excitation core section 11:
Shape of one silicon steel sheet: dimension l = 30 mm, dimension m = 15 mm, leg width dimension n = 5 mm, thickness t = 0.2 mm
25 silicon steel plates are stacked to form the exciting core 11 (the thickness of the entire core is 5 mm).
Excitation coil section 12: 165 turns of 0.45 mm line Detection coil section 22: 100 turns of 0.07 mm line Holding member 3:
Material: Epoxy resin Molding method: An actual work W is used as a mold, and an epoxy resin is injected into the mold. Before the epoxy resin is cured, the exciting coil 1 and the detection coil 2 after winding are embedded. Thereafter, the epoxy resin is cured.

In this experiment, a first experiment and a second experiment were performed in which the dimensions of the detection core portion 21 were changed.
Detection core unit 21:
First experiment Shape of one silicon steel sheet: dimension c = 7.5 mm, dimension b = 1.5 mm, thickness t = 0.2 mm
Four silicon steel plates are stacked to constitute the detection core portion 21 (the thickness of the entire core = the dimension a is 0.8 mm).
Second experiment Shape of one silicon steel plate: dimension c = 9.0 mm, dimension b = 3.0 mm, thickness t = 0.2 mm
Two silicon steel plates are stacked to constitute the detection core portion 21 (the thickness of the entire core = the dimension a is 0.4 mm).

[Experimental device]
FIG. 7 shows an outline of the experimental apparatus. In addition, illustration of the holding member 3 is abbreviate | omitted in the hardened layer depth measuring apparatus of FIG.
In FIG. 7, a resistor 4 and a bipolar power source 5 are connected to the exciting coil 1 of the hardened layer depth measuring device, and a frequency generator 6 is connected to the bipolar power source 5. A signal amplifier 7 is connected to the detection coil 2 of the hardened layer depth measuring apparatus. An oscilloscope 8 is connected to the resistor 4 and the signal amplifier 7.
Resistor 4: 1Ω resistor made by connecting 22 metal film resistors 1 / 4W22Ω in parallel Bipolar power supply 5: Quadrant bipolar power supply (BWS40-7.5) manufactured by Takasago Manufacturing Co., Ltd.
Frequency generator 6: NF Circuit Design Block Co., Ltd. Function Generator DF1906
Signal amplifier 7: NF Circuit Design Block Co., Ltd. Isolation amplifier 5325
Oscilloscope 8: Tektronix Osloscope TDS3054B
Excitation condition: Frequency 20Hz Excitation current 0.5A
Measurement method: Measurement was performed at two positions, position B and position C, at a work level having an effective hardened layer depth of 3 patterns. In this measurement, excitation is performed according to the excitation conditions, and the effective value of the detection voltage waveform output from the detection coil 2 is read by the oscilloscope 8.

[Experimental result]
FIG. 8A is a graph of a calibration curve showing the relationship between the effective hardened layer depth determined by the first experiment and the detected voltage.
FIG. 8A shows an experimental value S1 of the detection voltage obtained in three patterns of the effective hardened layer depth at the positions B and C, and an approximate straight line SL1 of a calibration curve obtained based on these experimental values S1. Is shown.
The approximate straight line SL1 is expressed by Equation 1 with y = 1.8572x + 52.288.
Among the measurement errors of the experimental value S1 with respect to the approximate straight line SL1, the maximum value SM1 is 0.22 mm, and the minimum value SN1 is −0.19 mm. That is, the measurement error with respect to the approximate straight line SL1 is −0.19 mm to 0.22 mm. Among the repeated measurement variations, the maximum value SO1 (n = 5) is 0.49 mV.

FIG. 8B is a graph of a calibration curve showing the relationship between the effective hardened layer depth obtained by the second experiment and the detected voltage.
FIG. 8B shows the experimental value S2 of the detection voltage obtained in three patterns of the effective hardened layer depth at the positions B and C, and the approximate straight line SL2 of the calibration curve obtained based on these experimental values S2. Is shown.
The approximate straight line SL2 is expressed by Equation 2 with y = 3.3928x + 116.3.
Among the measurement errors of the experimental value S2 with respect to the approximate straight line SL2, the maximum value SM2 is 0.09 mm, and the minimum value SN2 is −0.08 mm. That is, the measurement error with respect to the approximate straight line SL2 is −0.08 mm to 0.09 mm. The maximum value SO2 (n = 5) of the repeated measurement variation is 0.50 mV.

  Comparing the above first experiment with the second experiment in which the dimension a is reduced and the dimension b and the dimension c are increased compared to the first experiment, the slope of the approximate straight line SL1 and the approximate straight line SL2 is From the comparison with Equation 2, it can be seen that the second experiment is large. The maximum measurement error (n = 5) of the hardened layer depth is -0.19 mm to 0.22 mm in the first experiment, while -0.08 mm to 0.09 mm in the second experiment. Therefore, the second experiment in which the value of the dimension a was smaller than that of the first experiment was small. In addition, the maximum value of variation due to repeated measurement is 0.49 mV in the first experiment and 0.50 mV in the second experiment, and thus does not change substantially.

Therefore, in this embodiment, the following effects can be achieved.
(1) The detection coil 2 includes a detection core portion 21 disposed between the legs 111 constituting the excitation core portion 11 and disposed on the workpiece W, and a detection coil wound around the detection core portion 21. Therefore, the detection coil 2 is arranged at a position away from the excitation coil 1, and the influence of the magnetic flux flowing in the excitation core unit 11 is less likely. Therefore, in this embodiment, the measurement accuracy can be increased as compared with the conventional case.

(2) The detection core 21 has a dimension perpendicular to the surface of the workpiece W as a, a dimension perpendicular to the perpendicular direction as b, and a dimension perpendicular to the dimensions a and b as c. Then, since the detection coil portion is wound along the direction of the dimension c and the dimension a is smaller than the dimension b, the spatial magnetic flux is easily detected by the detection coil 2, and the measurement accuracy is further improved. become.

(3) Since the detection core portion 21 is formed in a rectangular parallelepiped shape by laminating a plurality of plates, the detection core portion 21 can be easily manufactured.
(4) Since the detection core portion 21 is composed of a non-directional electrical steel sheet having uniform magnetic characteristics in all directions, the measurement accuracy can be improved also in this respect.

(5) Since the excitation coil 1 and the detection coil 2 are integrated by the holding member 3, the excitation coil 1 and the detection coil 2 are positioned by the holding member 3. Installation work of 1 and the detection coil 2 becomes easy. And since it can measure in the state in which the exciting coil 1 and the detection coil 2 were positioned, it can prevent that a measurement precision falls.

(6) Since the holding member 3 is formed of an epoxy resin or other synthetic resin, the holding member 3 can be easily formed simply by pouring the molten synthetic resin into the container. The formed holding member 3 is not short-circuited or broken during use because the exciting coil portion 12 and the detection coil portion 22 are fixed.

(7) Since the holding member 3 has the positioning portion 3A for positioning with respect to the workpiece W, the excitation coil 1 and the detection coil 2 move while maintaining an appropriate position with respect to the workpiece W, and thus more accurate. High measurement can be performed.

The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the embodiment, the detection core portion 21 is formed in a rectangular parallelepiped shape. However, in the present invention, the specific shape of the detection core portion 21 is limited as long as the dimension a is smaller than the dimension b. It is not a thing. For example, the detection core 21 may have an elliptical cross section.

  In the present invention, it is not always necessary to provide the holding member 3 itself. Even if it is a case where the holding member 3 is provided, it is not limited to the structure of the said embodiment. For example, the shape of the holding member 3 is not limited to the shape of the above embodiment, and may be a rectangular parallelepiped shape, a cylindrical shape, a triangular prism shape, or the like.

  DESCRIPTION OF SYMBOLS 1 ... Excitation coil, 11 ... Excitation core part, 110 ... Base part, 111 ... Leg part, 12 ... Excitation coil part, 2 ... Detection coil, 21 ... Detection core part, 22 ... Detection coil part, 3 ... Holding Member, 3A ... positioning part, a ... dimension, b ... dimension, c ... dimension, H ... hardened layer, W ... workpiece

Claims (4)

An apparatus for quenching a workpiece and measuring the depth of a hardened layer formed on the surface,
An excitation coil that magnetizes the workpiece by generating magnetic flux and a detection coil that detects the magnetic flux generated by the excitation coil, and the excitation coil is a portal-shaped excitation whose leg tip faces the workpiece A core portion for excitation, and an exciting coil portion wound around the exciting core portion,
The detection coil has a detection core portion disposed between the legs of the excitation core portion and disposed on the workpiece, and a detection coil portion wound around the detection core portion,
The detection core portion has a dimension perpendicular to the surface of the workpiece, a, a dimension perpendicular to the vertical direction, b, and a dimension perpendicular to the dimension a and the dimension b, respectively. Then, the detection coil portion is wound along the direction of the dimension c,
The dimension a is smaller than the dimension b. The hardened layer depth measuring apparatus characterized by the above-mentioned. In the hardened layer depth measuring apparatus according to claim 1,
The detection core portion is formed in a rectangular parallelepiped shape. In the hardened layer depth measuring apparatus according to claim 2,
The said dimension a is 1.2 mm or less. The hardened layer depth measuring apparatus characterized by the above-mentioned. In the hardened layer depth measuring apparatus according to claim 2 or 3,
The detection core part is made of a non-oriented electrical steel sheet. A hardened layer depth measuring apparatus.

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