JPH07229705A - Quench hardened layer depth measuring method - Google Patents

Abstract

PURPOSE:To provide a quench hardened layer depth measuring method applicable to a work having the free-shape surface and capable of easily measuring the depth of a quench hardened layer at an accurate measurement position in the cross direction. CONSTITUTION:A longitudinal ultrasonic wave is transmitted into a quench hardened layer W1 from the surface while displacing a focal point in depth with a high frequency probe 2, and a surface reflected wave S from the surface and a boundary reflected wave R from a boundary B between a base material W0 and the quench hardened layer W1 are received by the high frequency probe 2. A relationship between the strength and the propagation time of the surface reflected wave S and the boundary reflected wave R is found and the depth of the quench hardened layer W1 from the surface is found from a difference between the propagation time of the surface-reflected wave and the propagation time of the boundary-reflected wave.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nondestructive method for measuring the depth from the surface of a quench hardened layer on a base material.

[0002]

2. Description of the Related Art Conventionally, an object to be measured (workpiece) is placed in a magnetic line of force generated by an exciting coil, and the phase difference of the detected current and the magnetic permeability of the hardened layer are used to determine the hardness of the hardened layer of the work from the surface. A device for nondestructively measuring depth is known (Japanese Utility Model Laid-Open No. 59-40805).

Further, a transverse ultrasonic wave is obliquely incident from the outer circumferential surface side of the roll-shaped work in the axial direction, and
By moving the ultrasonic wave incident point at multiple points in the axial or circumferential direction, collecting the backscattered waves corresponding to each ultrasonic wave incident point, and averaging the backscattered waves collected at the multiple points. A method is also known in which the backscattering pattern is obtained and the curing depth is measured from the discontinuity point of the obtained pattern (JP-A-60-205353).

[0004]

However, in each of the above conventional methods, the work is limited to those having a cylindrical surface such as a roll, and when the work has a free-form surface, It is difficult to apply. In particular, in the former method, the induced amount of the eddy current is changed depending on the surface shape of the work, and the depth of the hardened layer cannot be accurately measured.

Further, in the former method, even when applied to a work having a cylindrical surface, the width of the coil is limited, so that the accurate measurement position in the width direction cannot be determined, and the average value in the width direction is used. Only the depth from the surface of the quench hardened layer can be measured. Further, in the latter method, transverse wave ultrasonic waves are adopted in order to obtain sufficient sensitivity without having to displace the focal point in the depth direction. The data obtained by this has a relationship between the depth t from the surface and the intensity I of the backscattered wave, as shown in FIG. In this case, in order to measure the curing depth, the backscattered waves collected at a plurality of points are averaged by digital processing to obtain a backscattering pattern, and the discontinuity points (peak values) of the obtained pattern must be obtained. I won't. For this reason, in this method, the data processing is complicated by the averaging process and the data processing is required a plurality of times, so that the depth of the hardened layer cannot be easily measured.

In particular, when the hardened layer is formed by quenching, the hardened layer is formed by gradually hardening the base material to some extent in the depth direction from the base material. In the latter publication, the method of detecting inclusions and segregation in the metallographic structure using longitudinal ultrasonic waves is described as "announced at the 10th World Conference on Nondestructive Testing". Since the boundary with the base metal is clear and inclusions and the like are only detected by this method, the depth from the surface of the quench-hardened layer cannot be measured by this method alone.

Even when the latter method is applied to a work having a cylindrical surface, the surface roughness of the work has a great influence on the reflection condition of ultrasonic waves, and the surface roughness is not taken into consideration. It was also clarified that the depth from the surface of the hardened layer could not be measured accurately if measured. The first object of the present invention is applicable to a work having a free-form surface, and under an accurate measurement position in the width direction,
It is an object of the present invention to provide a method for measuring the depth of a quench-hardened layer, which can easily measure the depth of the quench-hardened layer.

A second object of the present invention is to solve the first problem and to provide a method for measuring the depth of a quench-hardened layer capable of measuring the depth of the quench-hardened layer more accurately. is there.

[0009]

[Means for Solving the Problems]

(1) The method for measuring the depth of a quench-hardened layer according to claim 1, wherein the depth from the surface of the quench-hardened layer on the base material of the workpiece is measured in the liquid, Transmitting longitudinal ultrasonic waves from the surface into the quench-hardened layer while displacing the focus in the depth direction by a transmitter, and the surface-reflected wave from the surface and the base material and the quench-hardened layer by the receiver. Boundary reflected wave from the boundary of is received, the relationship between the intensity of the surface reflected wave and the boundary reflected wave and the propagation time is obtained, and from the difference between the propagation time of the surface reflected wave and the propagation time of the boundary reflected wave. It is characterized in that the depth from the surface in the quench hardened layer is obtained.

(2) The depth measuring method according to claim 2 is the depth measuring method according to claim 1, wherein the surface roughness of the surface is a ten-point type surface roughness measuring method (Rz) whose unit is a micrometer (μm). ), The wavelength of the ultrasonic wave of the longitudinal wave is made equal to or more than the surface roughness. (3) The depth measuring method according to claim 3 is characterized in that, in the depth measuring method according to claim 1 or 2, the transmitting device is capable of displacing the focal point in the depth direction.

(4) The depth measuring method according to claim 4 is characterized in that in the depth measuring method according to claim 1, 2 or 3, the transmitter and the receiver are integrated. (5) The depth measuring method according to claim 5 is the depth measuring method according to any one of claims 1, 2, 3 or 4, wherein a reflecting means for reversing the boundary reflected wave is provided in the middle of the path of the boundary reflected wave. Is received by the transmitting device via the reflecting means.

(6) The depth measuring method according to claim 6 is the depth measuring method according to claim 1, 2, 3, 4 or 5, wherein different liquids are selectively provided between the oscillator and the surface of the transmitter. The liquid is characterized in that the liquid can be circulated through the liquid and the liquid capable of transmitting an ultrasonic wave of a desired wavelength is selected and the ultrasonic wave is transmitted. (7) The depth measuring method according to claim 7 is the method according to claim 1, 2, 3,
In the depth measuring method of 4, 5 or 6, the temperature of the liquid is measured in advance, and the distance from the surface of the focal point is displaced in the depth direction based on the measured value.

(8) The depth measuring method according to claim 8 is the depth measuring method according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the intensity of at least one of the surface reflected wave and the boundary reflected wave. Is detected and a warning signal is issued when the intensity is less than a threshold value.

[0014]

[Action]

(1) In the depth measuring method according to the first aspect of the present invention, first, the ultrasonic wave of a longitudinal wave is transmitted from the surface of the work into the quench-hardened layer by displacing the focus in the depth direction by the transmitting device. Since the focal point is the point where the intensity of ultrasonic waves becomes the strongest, if the focal point is located at the boundary between the base metal and the quench-hardened layer, the reflected wave will be received by the receiving device in response to structural changes such as crystal grains. To be done. Here, the reflected wave includes a surface reflected wave from the surface and a boundary reflected wave from the boundary between the base material and the quench-hardened layer.
The boundary reflected wave is generated by scattering of the incident ultrasonic waves because the structure structure such as crystal grains is expanded on the base material side of the boundary.

The data obtained by this method has a relationship between the intensity I of the surface reflected wave S and the boundary reflected wave R and the propagation time T, as shown in FIG. At this time, since the sensitivity of the longitudinal ultrasonic waves is increased by the focus, the boundary has a range in the depth direction from the base metal to some extent, and even the quench-hardened layer formed by gradually hardening at the boundary is formed. The surface reflection wave S and the boundary reflection wave R surely reflect the change in curing within the range. Then, the difference between the propagation time of the surface reflected wave S and the propagation time of the boundary reflected wave R, for example, the surface reflected wave S
Propagation start time T ₁ and boundary reflection wave R propagation start time T ₂
And the difference a is calculated. Here, since the sound velocity in the quench-hardened layer is a constant, the depth of the quench-hardened layer can be measured without averaging. For this reason, in this method, the data processing is simplified and one data processing is sufficient, so that the depth of the quench hardened layer can be easily measured.

Thus, this method is not limited to a work having a cylindrical surface such as a roll, and can be easily applied to a work having a free-form surface. Particularly, in this method, since the exciting current is not detected, the depth of the hardened layer can be accurately measured regardless of the surface shape of the work. Also, with this method,
The position at which the longitudinal ultrasonic wave is transmitted is specified by the transmitting device, an accurate measurement position is determined in the width direction, and the depth from the surface of the quench-hardened layer at the specific position in the width direction can be measured.

(2) In the depth measuring method according to the second aspect, the surface roughness of the surface is previously measured by Rz (μm), and the wavelength of the ultrasonic wave of the longitudinal wave is made equal to or larger than this surface roughness. According to the results of experiments by the inventors, ultrasonic waves having a wavelength smaller than the surface roughness of the surface are almost reflected by the surface, and a boundary reflected wave cannot be obtained. By doing so, the surface reflected wave and the boundary reflected wave can be reliably received.

(3) When the focal point is displaced in the depth direction by the transmitter, if the focal point cannot be displaced in the depth direction, it is necessary to change the position of the transmitter itself from the surface. At this time, if the distance between the transmitter and the surface is not measured one by one, the influence of the attenuation of the ultrasonic waves due to the liquid between the transmitter and the surface will change, and the reproducibility will not be exhibited, which is troublesome. Will be required. In addition, the positioning accuracy of the transmission device is likely to be accompanied by an error, and the proximity of the transmission device is limited.

On the other hand, in the depth measuring method according to the third aspect, since the transmitter can displace the focal point in the depth direction, the labor for positioning can be omitted, and the transmitter and the surface can be separated from each other. The attenuation of ultrasonic waves in the liquid between can be neglected. Further, it is possible to eliminate the positioning error and prevent the transmitter from being damaged or damaged due to being too close to the surface.

(4) In the depth measuring method according to the fourth aspect, since the transmitter and the receiver are integrated, it is not necessary to prepare a separate transmitter and receiver. (5) In the depth measuring method according to the fifth aspect, the reflecting means for reversing the course of the boundary reflected wave is provided in the course of the course. Therefore, since the boundary between the base material and the quench-hardened layer is inclined with respect to the surface, even if the surface reflected wave and the boundary reflected wave take different paths, the boundary reflected wave is received by the transmitting device via this reflecting means. It Therefore, it is not necessary to prepare a separate transmitter and receiver.

(6) When the surface roughness of the surface is measured in advance by Rz (μm) and the wavelength of the ultrasonic wave of the longitudinal wave is equal to or larger than this surface roughness, a plurality of transmitters having vibrators having different thicknesses are used. Prepare,
Although it is possible to select an oscillator that can emit an ultrasonic wave of a desired wavelength to emit an ultrasonic wave, this requires preparing a plurality of oscillators having vibrators of different thicknesses. In this respect, in the depth measuring method according to the sixth aspect, different liquids can be selectively circulated between the oscillator and the surface of the transmitter. Different liquids have different sound velocities of ultrasonic waves in the liquids, and therefore, by selecting the liquids, ultrasonic waves having a desired wavelength can be transmitted. Therefore, it is not necessary to prepare a plurality of transmitters having vibrators of different thicknesses in order to select a transmitter capable of transmitting an ultrasonic wave of a desired wavelength and transmit the ultrasonic wave.

(7) Even if the focal point is once located at the boundary between the base material and the quench-hardened layer, if the temperature of the liquid changes,
Since the sound velocity of the ultrasonic wave in the liquid is different, the refractive index of the ultrasonic wave propagating in the liquid changes, and the focus position once adjusted changes from the boundary. In this case, the longitudinal ultrasonic wave has a reduced sensitivity, and the depth of the quench-hardened layer cannot be accurately measured, so that the focal point needs to be displaced again in the depth direction.
Then, the reproducibility is not exhibited and it takes time.

On the other hand, in the depth measuring method according to the seventh aspect, the temperature of the liquid is measured in advance, and the distance from the surface of the focal point is displaced in the depth direction based on the measured value. Therefore, the focus is surely positioned at the boundary according to the temperature. here,
When the distance from the surface of the focal point is displaced in the depth direction according to the temperature of the liquid, if the transmitter cannot displace the focal point in the depth direction, it is necessary to change the position of the transmitter itself from the surface. . At this time, reproducibility is difficult to be exerted, and labor is required. In addition, the positioning accuracy of the transmission device is likely to be accompanied by an error, and the proximity of the transmission device is limited.

On the other hand, in the depth measuring method according to the third aspect, since the transmitter can displace the focal point in the depth direction, the labor for positioning can be omitted, and the transmitter and the surface can be separated from each other. The attenuation of ultrasonic waves in the liquid between can be neglected. Further, it is possible to eliminate the positioning error and prevent the transmitter from being damaged or damaged due to being too close to the surface.

(8) According to the results of experiments conducted by the inventors, in the depth measuring method according to any one of claims 1 to 7, when there is an adhered substance on the surface of the work, when the surface roughness of the work is rough, the liquid is When there is a suspended matter such as dust in the inside, or when the transmission device is deteriorated, the intensity of the reflected wave is significantly reduced or cannot be obtained. Therefore, in these cases, it is not possible to accurately measure the depth from the surface of the hardened layer, and in an extreme case, even though the hardened layer actually exists on the base metal, There is a possibility that it may be determined that there is no hardened layer.

On the other hand, in the depth measuring method according to the eighth aspect, the intensity of at least one of the surface reflected wave and the boundary reflected wave is detected, and the warning signal is issued when the intensity is less than the threshold value. Therefore, when there is an adhered substance on the surface of the work, a warning signal is issued and erroneous measurement can be avoided.

[0027]

【Example】

(Embodiment 1) In embodiment 1, claims 1, 3 and 4 are embodied. "Transmitting / Receiving Device" This method employs the ultrasonic sounding imaging device shown in FIG. In this ultrasonic exploration imaging apparatus, a focus type ultra-high frequency probe 2 is attached to a scanner 1a of a scanning device 1, and an ultrasonic measurement unit 3 is connected to the high frequency probe 2. The scanning device 1 and the ultrasonic measurement unit 3 are connected to the control device 4, and the ultrasonic measurement unit 3 is connected to the oscilloscope 3a. The control device 4 is connected to the data processing device 5, and the data processing device 5 is connected to the color hard copy 6 and the color CRT 7 and also connected to the monochrome CRT 9 via the image processing device 8.

The high frequency probe 2 is a transmitting / receiving device (ultrasonic sensor) in which the transmitting device and the receiving device according to the present invention are integrated. As shown in FIG. 2, the high frequency probe 2 includes three vibrators 2a each made of a piezoelectric element, and three acoustic lenses 2b mounted below each vibrator 2a. Each transducer 2a is connected to the switch 2 from the ultrasonic measurement unit 3.
It is connected to the lead wire 2d via the c
At d, the electric signal transmitted from the ultrasonic measuring unit 3 is converted into vibration to emit ultrasonic waves, and at the same time, the vibration of the received ultrasonic wave is converted into an electric signal and the lead wire 2d is used to make the ultrasonic measuring unit 3
Send to. At this time, the thickness of each transducer 2a determines the wavelength λ (frequency f) of the ultrasonic wave. All the vibrators 2a adopted here have the same thickness.

On the other hand, as shown in FIG. 3, each acoustic lens 2b has a concave lower surface, and bends the ultrasonic waves emitted from the vibrator 2a so as to concentrate them on the focal point F at a predetermined distance b. . At this time, the curvature of each acoustic lens 2b determines the distance b to the focus F. The acoustic lenses 2b adopted here have different curvatures. For this reason,
In this high-frequency probe 2, each transducer 2a and each acoustic lens 2b are selected by the selection of the switch 2c, whereby the focus F can be displaced in the depth direction. [Method of Measuring Hardened Hardened Layer Depth] As shown in FIG. 4, the work W is placed in the processing tank 1b filled with water 10 as the liquid in the ultrasonic probe imaging apparatus. This work W has a quench hardened layer W ₁ formed on a base material W ₀ made of JIS S53C having a planar surface.

First, in the high frequency probe 2, each transducer 2a and each acoustic lens 2b are selected by selecting the switch 2c.
Is selected, longitudinal ultrasonic waves are emitted from the surface of the work W into the quench hardened layer W ₁ while displacing the focus F in the depth direction. Then, when the focal point F is located at the boundary B between the base material W ₀ and the quench hardened layer W ₁ , the reflected wave is received by the high frequency probe 2 in response to the change in the structure of the crystal grains. Here, the reflected wave is composed of a surface reflected wave S from the surface and a boundary reflected wave R from the boundary B, as shown in FIG. The boundary reflection wave R is generated by the incident ultrasonic waves being scattered because the crystal grains are expanded. Therefore, since the surface reflected wave S and the boundary reflected wave R are received by the high frequency probe 2,
There is no need to prepare a separate transmitter and receiver. In addition, a part of the incident longitudinal ultrasonic wave is not reflected at the boundary B,
Exit downwards.

The data obtained by this method has a relationship between the intensity I of the surface reflected wave S and the boundary reflected wave R and the propagation time T, as shown in FIG. At this time, since the sensitivity of the longitudinal ultrasonic waves is increased by the focus F, the boundary B has a range in the depth direction from the base material W ₀ to some extent.
Even in the quench-hardened layer W ₁ formed by being gradually hardened by the above, the surface reflected wave S and the boundary reflected wave R surely reflect the change in hardening within the range. Then, in order to measure the depth x of the quench hardened layer W _1, the difference between the propagation starting time of the surface reflected wave S T ₁ and the propagation starting time of the boundary reflected wave R T ₂ a
Ask for.

Here, since the sound velocity v ₀ in the quench-hardened layer W ₁ is a constant, the following equation holds: v ₀ = 2x / a (1) From this equation (1), x = av _0/2 ... (2) is obtained by (2), the depth x from the surface of the quench hardened layer W ₁ is determined.

Therefore, in this method, the averaging process is not required, the data processing is simplified, and one data processing is sufficient. Therefore, the depth x of the quench hardened layer W ₁ can be easily measured. it can. Thus, this method is easy to apply even when the work W is a free surface. In particular,
In this method, since the exciting current is not detected, the depth of the hardened layer can be accurately measured regardless of the surface shape of the work W.

Further, in this method, the position at which the longitudinal ultrasonic waves are transmitted is specified by the high-frequency probe 2, the accurate measurement position is determined in the width direction, and the quench-hardened layer W at the specified position in the width direction is determined. The depth x from the surface of ₁ can be measured. Therefore, this method can be applied to the work W having a free-form surface, and the depth x of the quench-hardened layer W ₁ can be easily measured under the accurate measurement position in the width direction.

Further, in this method, since the high frequency probe 2 which can displace the focus F in the depth direction by selecting the switch 2c is employed, the following operation and effect can be exhibited. That is, in this method, since it is not necessary to change the position of the high-frequency probe 2 itself from the surface, the labor for positioning can be omitted. In addition, in Example 1, three transducers 2a and three acoustic lenses 2b are provided.
The high frequency probe 2 equipped with
When the focus F cannot be made to coincide with the boundary B depending on the curvature of b, it is necessary to change the position of the high frequency probe 2 itself from the surface. However, even in this case, compared to the case where the positioning is performed from the beginning, the labor for positioning can be omitted. It is also possible to employ a high frequency probe provided with a larger number of vibrators 2a and acoustic lenses 2b.

Further, in this method, since it is not necessary to change the position of the high frequency probe 2 itself from the surface, attenuation of ultrasonic waves in the water 10 can be ignored. further,
In this method, since it is not necessary to change the position of the high frequency probe 2 itself from the surface, it is possible to eliminate a positioning error and prevent damage and damage to the high frequency probe 2 due to being too close to the surface. You can (Embodiment 2) The second embodiment also embodies claims 1, 3 and 4. “Transmitting / Receiving Device and Receiving Device” In this method, as shown in FIG. 7, the same high-frequency probe 2 as the transmitting / receiving device and the two high-frequency probes as receiving devices as in the first embodiment. 11 and 11 are adopted. Each high-frequency probe 11 is composed of one transducer that is composed of the same piezoelectric element as that of the high-frequency probe 2 of the first embodiment, and one acoustic lens mounted below this transducer. Each high-frequency probe 11 is swingable around an incident point of a longitudinal ultrasonic wave.
Other configurations are the same as those in the first embodiment. [Method of Measuring Hardened Hardened Layer Depth] The work W is placed in the same manner as in Example 1, and the high frequency probe 2 displaces the focal point F in the depth direction to emit longitudinal ultrasonic waves. Then, the reflected wave is received by the high frequency probe 2 and the high frequency probe 11. At this time, since the surface reflected wave S is received by the high frequency probe 2, it is not necessary to prepare a separate transmitter and receiver for receiving the surface reflected wave S. Further, at this time, the surface reflected wave S and the boundary reflected wave R may take different paths due to the fact that the boundary B is inclined with respect to the surface due to quenching abnormality, and in this case as well, the high frequency probe 11 is shaken. By moving the boundary reflection wave R, the high-frequency probe 11
Received by.

By the data obtained by this method,
As in Example 1, quench-hardened layer W ₁The depth x of
It can be measured. So in this way
Shakes the high-frequency probe 11 to receive the boundary reflected wave R.
If moved, the same effect as that of the first embodiment can be obtained.
It (Embodiment 3) Embodiments 3 also embody claims 1, 3 and 4
are doing. "Transmitting / Receiving Device and Receiving Device"
As shown in FIG.
High-frequency probe 2 and a large number of high-frequency probes as receiving devices
The tentacle 12 is used. Each high frequency probe 12
From the piezoelectric elements similar to the high frequency probe 2 of Example 1, respectively.
It consists of one oscillator. Each high frequency probe 12 has a longitudinal wave
It is provided in the shape of a disk centered on the point of incidence of ultrasonic waves
It Other configurations are the same as those in the first embodiment. "Method of measuring depth of quench hardened layer" Same as in Example 1
Place the probe W, and use the high-frequency probe 2 to set the focus F in the depth direction.
It emits longitudinal ultrasonic waves while displacing to. And Takashi
The reflected wave is received by the wave probe 2 and the high frequency probe 12.
Be done. At this time, the surface reflected wave S is generated by the high frequency probe 2.
Since it is received, the reception of the surface reflected wave S is separate.
It is not necessary to prepare a transmitter and a receiver. Also, this
, The surface reflected wave S and the boundary reflected wave R follow different paths.
Any one of the high frequency probes 12 has a boundary
Receive the wave R.

By the data obtained by this method,
As in Example 1, quench-hardened layer W ₁The depth x of
It can be measured. So in this way
Requires no operation for receiving the boundary reflected wave R.
In addition, the same effect as that of the first embodiment can be obtained. (Fourth Embodiment) In the fourth embodiment, the claims 1, 3, 4 and 5 are defined.
It has been materialized. "Sending / receiving device" In this method, as shown in FIG.
A high frequency probe as the same transmitter / receiver as that of the first embodiment.
2 and two reflective glasses 13 as a reflection means are adopted.
are doing. Each reflection glass 13 has an incident point of longitudinal ultrasonic waves.
It is made swingable around the center. Other configurations are examples
Same as 1. "Method of measuring depth of quench hardened layer" Same as in Example 1
Place the probe W, and use the high-frequency probe 2 to set the focus F in the depth direction.
It emits longitudinal ultrasonic waves while displacing to. And Takashi
The reflected wave is received by the wave probe 2. At this time, the surface
Since the reflected wave S is received by the high frequency probe 2,
Regarding the reception of the reflected wave S, a separate transmitter and receiver are used.
No need to prepare. At this time, the boundary reflection wave R
The reflection glass 13 is shaken while the reflection glass 13 is being shaken.
Reverses the course of the boundary reflected wave R. Therefore, the surface
Even if the reflected wave S and the reflected wave R take different paths,
The reflected wave R passes through the reflection glass 13 and is transmitted by the high frequency probe 2.
Be received. Therefore, the reception of the boundary reflected wave R is also
There is no need to prepare a separate transmitter and receiver.

By the data obtained by this method,
As in Example 1, quench-hardened layer W ₁The depth x of
It can be measured. So in this way
Swings the reflection glass 13 to receive the boundary reflected wave R.
Then, the same effect as that of the first embodiment can be obtained. (Fifth Embodiment) In the fifth embodiment, the claims 1, 2, 3 and 4 are
It has been materialized. "Sending / receiving device" In this method, as shown in FIG.
And the high-frequency probe 14 as a transmitting / receiving device, and
Surface roughness measuring sensor fixed to the side of the high frequency probe 14.
15 and are adopted. The surface roughness measuring sensor 15 is an ultrasonic wave.
Consists of a roughness meter, surface roughness measuring device and switching control
It is connected to the device 16. Switching controller is high
It is connected to the switch 14c of the frequency probe 14.

As shown in FIG. 11, the high frequency probe 14 includes three vibrators 14a each made of a piezoelectric element, and three acoustic lenses 14b mounted below the vibrators 14a.
Consists of. Each transducer 14a has a thickness of the ultrasonic wavelength λ.
All have different thicknesses to determine (frequency f). Other configurations are the same as those in the first embodiment. [Method of Measuring Hardened Hardened Layer Depth] The work W is placed in the same manner as in Example 1, and the surface roughness of the surface is measured in advance by Rz (μm) by the ultrasonic waves transmitted from the surface roughness measurement sensor 15. This measurement result is transmitted from the surface roughness measuring device to the switching control device, and the switching control device selects the switch 14c which makes the wavelength λ of the longitudinal ultrasonic wave equal to or larger than this surface roughness, and the high frequency probe 14 The selected transducer 14a displaces the focal point F in the depth direction and emits a longitudinal ultrasonic wave. Here, the wavelength λ is selected by the following equation: λ = v / f (3) However, v is the sound velocity of ultrasonic waves. Then, the high frequency probe 14 receives the reflected wave. By doing so, the surface reflected wave S and the boundary reflected wave R can be reliably received.

By the data obtained by this method,
Even if the workpiece W has an uneven surface roughness because it is manufactured online, the depth x of the quench-hardened layer W ₁ can be easily and accurately measured. (Embodiment 6) In embodiment 6, claims 1, 2, 3, 4 and 6 are embodied. [Transmitting / Receiving Device] In this method, as shown in FIG. 12, a high-frequency probe 14 as the same transmitting / receiving device as that of the fifth embodiment, and below each transducer 14a of this high-frequency probe 14 are provided. It employs three nozzles (not shown) provided respectively. Each nozzle has water as liquid 2
0, ether 21 or glycerin 22 can flow out toward the surface. The other structure is the same as that of the fifth embodiment. [Method of Measuring Hardened Hardened Layer Depth] The work W is placed in the same manner as in Example 1, and the surface roughness of the surface is measured in advance by Rz (μm) by ultrasonic waves transmitted from a surface roughness measurement sensor (not shown). . Based on this measurement result, the switch 14c that makes the wavelength λ of the longitudinal ultrasonic wave in the liquid equal to or larger than this surface roughness is selected, and the selected transducer 14a of the high-frequency probe 14 causes the focus F
The ultrasonic wave of longitudinal wave is emitted while displacing in the depth direction. Here, the wavelength λ is selected by the above equation (3). In addition,
Sound speed v in water 20 is 1500 m / s, sound speed v in ether 21 is 985 m / s, sound speed v in glycerin 22
Is 1986 m / s. Therefore, if the frequency f is constant and the wavelength λ of the ultrasonic wave in the water 20 is set to “1”,
The wavelength λ in the ether 21 is “about 2/3”, and the wavelength λ in the glycerin 22 is “about 4/3”.

The high frequency probe 14 receives the reflected wave. At this time, if the liquid is different, the sound velocity of the ultrasonic waves in the liquid is different, so by selecting the liquid,
Ultrasonic waves having a desired wavelength λ can be emitted. In this way, the water 20, the ether 21, or the glycerin 22 capable of transmitting the ultrasonic wave of the desired wavelength λ is selected and the ultrasonic wave is transmitted. Therefore, it is not necessary to prepare a plurality of oscillators having different thicknesses.

Even with the data obtained by this method, the depth x of the quench-hardened layer W ₁ can be easily measured with high precision, as in the fifth embodiment. (Embodiment 7) In embodiment 7, claims 1, 4, and 7 are embodied. "Transmitting / Receiving Device" In this method, the ultrasonic probe device shown in FIG. 13 is adopted. In this ultrasonic probe, a high frequency probe 30 is attached to the scanner 1a of the scanning device 1. The high frequency probe 30 is a transmitter / receiver (ultrasonic sensor) in which the transmitter and the receiver according to the present invention are integrated. The high-frequency probe 30 is a commercially available one that includes a single oscillator (not shown) made of a piezoelectric element and a single acoustic lens mounted below the oscillator. Therefore, the high-frequency probe 30 cannot displace the focal point in the depth direction by itself.

A digital water thermometer 31 is provided in the processing tank 1b filled with water 10 as a liquid. An ultrasonic measurement unit 32 is connected to the high frequency probe 30, and the scanner 1 a is connected to the scanner control device 33. The scanner control device 33, the ultrasonic measurement unit 32, and the water temperature gauge 31 are connected to the data processing device 34. [Method of Measuring Hardened Hardened Layer Depth] The work W is placed as in the first embodiment. Then, the data processing device 34 moves the high frequency probe 30 in the depth direction via the scanner control device 33, thereby displacing the focus F in the depth direction and transmitting longitudinal ultrasonic waves.

At this time, as shown in FIG. 14, if the temperature of the water 10 has changed since the last measurement, the sound velocity of the ultrasonic waves in the water 10 is different, so that the ultrasonic waves propagating in the water 10 are different. The refractive index has changed, and the position of the previous focus F has changed from the boundary B. Therefore, the data processing device 33 performs data processing according to the flowchart shown in FIG. First,
In step S100, the water temperature (signal, the same applies hereinafter) is measured based on the output signal from the water temperature gauge 31. In step S101, the underwater sound velocity is calculated from the obtained water temperature based on the relationship between the water temperature (° C.) and the underwater sound velocity (m / s) stored in the ROM shown in FIG. Here, as shown in FIG. 17, ultrasonic waves are transmitted from the first medium (water) to the second medium (steel).
If the incident angle is θ ₁ , the exit angle is θ ₂ , the sound velocity in the first medium (water) is C ₁ , and the sound velocity in the second medium (steel) is C ₂ when entering the space, sin θ ₁ / Sin θ ₂ = C ₁ / C ₂ (4) Formula is established. Here, since the incident angle θ ₁ and the in-steel sound velocity C ₂ are constants, in step S102, the exit angle θ _{2 of the} ultrasonic wave entering the work W is calculated from the calculated underwater sound velocity C _1.
To calculate. Next, in step S103, the depth of focus from the calculated emission angle θ ₂ to the boundary B is calculated. Thus, in step S104, the high frequency probe 3 is transmitted via the scanner control device 33 based on the calculated depth of focus.
0 is corrected in the depth direction. In this way, the focal point F is surely positioned at the boundary B according to the water temperature.

After that, in step S105, the reflected wave is received by the high-frequency probe 30, and the depth x of the hardening layer W ₁ is measured. Therefore, in this method,
Even if the water temperature has changed since the last measurement, the quench hardening layer W
The depth x of ₁ can be measured accurately. (Embodiment 8) The eighth embodiment also embodies claims 1, 4, and 7. "Transmitting / Receiving Device" In this method, the digital water thermometer 31 is not provided in the processing tank 1b. The other structure is the same as that of the seventh embodiment. [Method of Measuring Hardened Hardened Layer Depth] The work W is placed as in the first embodiment. Then, the data processing device 34 moves the high frequency probe 30 in the depth direction via the scanner control device 33, thereby displacing the focus F in the depth direction and transmitting longitudinal ultrasonic waves.

At this time, if the temperature of the water 10 has changed since the last measurement, the sound velocity of the ultrasonic waves in the water 10 is different, so the refractive index of the ultrasonic waves propagating in the water 10 changes, and The position of the focal point F of is changed from the boundary B. For this reason,
The data processing device 33 detects the waveform T at the time of transmission in the relationship between the intensity I and the propagation time T shown in FIG. Further, the surface reflected wave S and the boundary reflected wave R are detected. Here, the distance between the high-frequency probe 30 and the surface of the work W is Δ
If z, Δz is determined as a coordinate by the scanner control device 33. Then, if the difference between the waveform T at the time of transmission and the propagation start time T ₁ of the surface reflected wave S is Δt, the underwater sound velocity C ₁ can be obtained by the formula C ₁ = Δz / Δt (5). In this way, from the calculated underwater sound velocity C ₁ , the focus F is surely set to the boundary B according to the water temperature, as in the seventh embodiment.
Is located in. After that, the high-frequency probe 30 receives the reflected wave and measures the depth x of the quench-hardened layer W ₁ .

Therefore, in this method, the depth x of the quench hardened layer W ₁ can be accurately measured without using the water temperature gauge 31, even if the water temperature has changed since the last measurement. (Embodiment 9) In embodiment 9, claims 1, 3, 4 and 7 are embodied. "Transmitting / Receiving Device" In this method, the ultrasonic probe device shown in FIG. 19 is adopted. In this ultrasonic probing apparatus, a high frequency probe 14 (see FIG. 10) capable of displacing the same focal point F in the depth direction as in the fifth embodiment is attached to the scanner 1a of the scanning apparatus 1. However, the surface roughness measuring sensor 15 is not provided. The high frequency probe 14 is connected to a data processing device 36 via a switching control device 35. The other structure is the same as that of the seventh embodiment. [Method for Measuring Hardened Hardened Layer Depth] The work W is placed in the same manner as in Example 1, and the high frequency probe 14 displaces the focal point F in the depth direction to emit longitudinal ultrasonic waves.

At this time, if the temperature of the water 10 has changed since the last time, the sound velocity of the ultrasonic waves in the water 10 is different, so the refractive index of the ultrasonic waves propagating in the water 10 changes, and The position of the focal point F of is changed from the boundary B. For this reason,
The data processing device 36 performs data processing according to the flowchart shown in FIG. First, in step S200, the water temperature is measured based on the output signal from the water temperature gauge 31. Then, similarly to the seventh embodiment, the underwater sound velocity is calculated from the water temperature in step S201, the emission angle θ ₂ is calculated from the underwater sound velocity C _{1 in} step S202, and the depth of focus is calculated from the emission angle θ _{2 in} step S203. Thus, step S
At 204, the switch 14c that can realize the focal length closest to the calculated focal depth is selected. In this way, the focal point F is surely positioned at the boundary B according to the water temperature.

Thereafter, in step S205, the depth x of the quench hardened layer W ₁ is measured. Therefore, also in this method, the depth x of the quench-hardened layer W ₁ can be accurately measured even if the water temperature has changed since the last measurement, as in the seventh embodiment. (Embodiment 10) In the embodiment 10, claims 1, 3, 4, and 8 are defined.
Is embodied in. "Transmitting / Receiving Device" This method employs the ultrasonic sounding imaging device shown in FIG. In this ultrasonic exploration imaging apparatus, the synchronization controller 40 is connected to the gate generator 41, the pulse voltage oscillator 42 and the horizontal axis sweeper 43, and the gate generator 41 and the pulse voltage oscillator 42 are connected to the receiver 44. . The receiver 44 and the horizontal axis sweeper 43 are connected to the cathode ray tube 45, the receiver 44 is connected to the level discriminator 46, and the level discriminator 46 is connected to the level setter 47. The same high-frequency probe 2 as in the first embodiment is connected to the pulse voltage oscillator 42 and the receiver 44. Other configurations are the same as those in the first embodiment. [Method of Measuring Hardened Hardened Layer Depth] The work W is placed in the same manner as in Example 1, and the high frequency probe 2 displaces the focal point F in the depth direction to emit longitudinal ultrasonic waves. Then, when the focal point F is located at the boundary B between the base material W ₀ and the quench hardened layer W ₁ , the high frequency probe 2 receives the reflected wave.

At this time, first, a gate signal is generated by the gate generator 41, and among the signals received by the receiver 44,
Only the surface reflected wave S is transmitted to the level discriminator 46. Then, the level discriminator 46 performs data processing according to the flowchart shown in FIG. That is, step S30
At 0, as shown in FIG. 23, the signal voltage level v of the surface reflected wave S is measured. Next, in step S301, the signal voltage level v of the surface reflected wave S is compared with the threshold value v ₀ set by the level setter 47.

Here, if v ≧ v _0, it is determined that the output of the high-frequency probe 2 is sufficient and that the ultrasonic waves emitted from the high-frequency probe 2 have reached the work W without being attenuated on the way. Then, the actual measurement is started in step S302. On the other hand, if v <v ₀ , if there is a deposit on the surface of the work W, if the surface roughness of the work W is rough, water 1
It is determined that the intensity of the surface reflected wave S has been significantly reduced or cannot be obtained due to the presence of a floating substance such as dust in 0, the deterioration of the high frequency probe 2, or the like, and step S30
Stop the measurement at 3. Then, in step S304, a warning signal is issued.

Thus, this method can avoid erroneous measurement. Further, it is possible to know the replacement time of the water 10 and the high frequency probe 2 in the treatment tank 1b, and
The work W having a rough surface can be removed from the line to improve product quality. In addition, each of the above Examples 1 to 1
In 6, 9 and 10, high frequency probes 2 and 1 having a plurality of transducers and acoustic lenses for displacing the focal point in the depth direction.
4 was adopted, but as shown in FIG.
0 is provided with a single first acoustic lens 51 having a convex lower surface, and a single second acoustic lens 52 having a concave lower surface is provided below the first acoustic lens 51. It is considered that the same effect can be obtained also by the high frequency probe in which the distance between the first acoustic lens 51 and the second acoustic lens 52 can be displaced.

In each of Examples 1 to 10, it is also possible to display the cross section of the quench-hardened layer W ₁ as an image by scanning the high-frequency probe along the work W. In addition, if the difference in crystal grains is patterned from the relationship between the intensity of the surface reflected wave S and the boundary reflected wave R and the propagation time according to each of Examples 1 to 10, it can be applied to the determination of the internal state of the work W. is there.

[0055]

【The invention's effect】

(1) Since the depth measuring method according to claim 1 employs the structure according to claim 1, it can be applied to a work having a free-form surface, and quenching is performed under an accurate measurement position in the width direction. The depth of the hardened layer can be easily measured. Therefore, with this method, the depth of the quench-hardened layer can be measured accurately and inexpensively.

(2) In the depth measuring method according to claim 2, since the surface reflected wave and the boundary reflected wave can be reliably received by the configuration of claim 2, in addition to the effect of claim 1, The depth of the quench hardened layer can be accurately measured. (3) According to the depth measuring method of claim 3, in addition to the effects of claims 1 and 2, due to the configuration of claim 3, labor for positioning the transmitter can be omitted. In addition, this method can eliminate the positioning error. in addition,
With this method, it is possible to prevent the transmitter from being damaged or broken due to being too close to the surface.

Therefore, the depth of the quench hardened layer can be measured more easily, and further cost reduction can be realized. (4) In the depth measuring method according to claim 4, since it is not necessary to prepare a separate transmitting device and receiving device due to the configuration of claim 4, in addition to the effects of claims 1 to 3, the quench hardening layer The depth can be measured more easily, and further cost reduction can be realized.

(5) In the depth measuring method according to the fifth aspect as well, the configuration of the fifth aspect eliminates the need to prepare a separate transmitting device and receiving device. Therefore, in addition to the effects of the first to fourth aspects, It is possible to more easily measure the depth of the quench-hardened layer and realize further cost reduction. (6) In the depth measuring method according to claim 6 as well, the configuration according to claim 6 eliminates the need to prepare a plurality of oscillator transmission devices having different thicknesses.
It is possible to more easily measure the depth of the quench-hardened layer and realize further cost reduction.

(7) In the depth measuring method according to claim 7, in addition to the effects of claims 1 to 6, according to the configuration of claim 7, even if the water temperature changes from the time of the previous measurement, the depth of the quench hardening layer is increased. Can be measured accurately. (8) According to the depth measuring method of claim 8, in addition to the effects of claims 1 to 7, the configuration of claim 8 can avoid erroneous measurement. Further, it is possible to know the replacement time of the liquid or the transmitter, and it is possible to improve the quality of the product by removing the work having a rough surface from the line.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an ultrasonic probe imaging apparatus according to a first embodiment.

FIG. 2 is a schematic cross-sectional view showing a high frequency probe according to a first embodiment.

FIG. 3 is a schematic cross-sectional view showing a main part of the high frequency probe according to the first embodiment.

FIG. 4 is a schematic cross-sectional view showing the method of Example 1.

5 is a schematic cross-sectional view showing the main parts of the method of Example 1. FIG.

FIG. 6 is a graph showing the relationship between the intensity of surface reflected waves and boundary reflected waves obtained by the method of Example 1 and the propagation time.

FIG. 7 is a schematic cross-sectional view showing the main parts of the method of Example 2.

FIG. 8 is a schematic cross-sectional view showing the main parts of the method of Example 3.

FIG. 9 is a schematic cross-sectional view showing the main parts of the method of Example 4.

FIG. 10 is a schematic cross-sectional view showing the main parts of the method of Example 5.

FIG. 11 is a schematic cross-sectional view showing a high frequency probe according to a fifth embodiment.

FIG. 12 is a schematic cross-sectional view showing the main parts of the method of Example 6.

FIG. 13 is a schematic diagram of an ultrasonic probe according to a seventh embodiment.

FIG. 14 is a schematic cross-sectional view showing the main parts of the method of Example 7.

FIG. 15 is a flowchart of a data processing device according to a seventh embodiment.

FIG. 16 is a graph showing the relationship between water temperature and underwater sound velocity according to the seventh embodiment.

FIG. 17 is a schematic diagram showing how an ultrasonic wave enters the second medium (steel) from the first medium (water) according to the seventh embodiment.

18A and 18B relate to Example 8; FIG. 18A is a graph showing the relationship between the intensity of the waveform at the time of transmission, the intensity of surface reflected waves and boundary reflected waves, and the propagation time; FIG. It is a schematic diagram showing a state.

FIG. 19 is a schematic diagram of an ultrasonic probe according to a ninth embodiment.

FIG. 20 is a flowchart of a data processing device according to a ninth embodiment.

FIG. 21 is a schematic view of a main part of an ultrasonic survey imaging device according to a tenth embodiment.

FIG. 22 is a flowchart of the level discriminator according to the tenth embodiment.

FIG. 23 is a graph showing the relationship between the signal voltage of the surface reflected wave and the boundary reflected wave obtained by the method of Example 10 and time.

FIG. 24 is a schematic cross-sectional view showing the main parts of a high-frequency probe according to another embodiment.

FIG. 25 is a graph showing the relationship between the depth from the surface and the intensity of backscattered waves obtained by a conventional method.

[Explanation of symbols]

W ... work W ₀ ... the base material W ₁ ...
Hardened layer x ... Depth 2, 14, 30 ... High frequency probe (transmitter / receiver) F ... Focus 11, 12 ... High frequency probe (receiver) S ... Surface reflected wave B ... Boundary R ... Boundary reflection Wave I ... Intensity T ... Propagation time a ... Difference lambda ... Wavelength 13 ... Reflective glass (reflection means) 10, 20, 21, 22 ... Liquid (10, 20 ... Water, 21
... ether, 22 ... glycerin)

Claims (8)

[Claims] 1. A method for measuring the depth of a quench-hardened layer in a liquid, the depth of the quench-hardened layer on a base material of a work being measured in a liquid, wherein a focal point is displaced in the depth direction by a transmitter. Transmitting a longitudinal ultrasonic wave from the surface into the quench-hardened layer, receiving a surface reflection wave from the surface and a boundary reflection wave from the boundary between the base material and the quench-hardened layer by a receiving device, The relationship between the surface reflection wave and the intensity of the boundary reflection wave and the propagation time is obtained, and the depth from the surface in the quench hardened layer is calculated from the difference between the propagation time of the surface reflection wave and the propagation time of the boundary reflection wave. A method for measuring the depth of a quench-hardened layer, characterized by obtaining. 2. The surface roughness of the surface is previously measured by a ten-point surface roughness measuring method with a unit of micrometer, and the wavelength of the ultrasonic wave of longitudinal wave is made equal to or more than the surface roughness. Item 2. A method for measuring the depth of a quench-hardened layer according to Item 1. 3. The method for measuring the depth of a quench-hardened layer according to claim 1, wherein the transmitting device is capable of displacing the focal point in the depth direction. 4. A method for measuring the depth of a quench-hardened layer according to claim 1, wherein the transmitter and the receiver are integrated. 5. A reflection means for reversing the path is provided in the course of the boundary reflection wave, and the boundary reflection wave is received by a transmitting device via the reflection means.
The method for measuring the depth of a quench-hardened layer according to 2, 3, or 4. 6. A different liquid can be selectively circulated between a vibrator and a surface of a transmitting device, and the liquid capable of transmitting an ultrasonic wave of a desired wavelength is selected to emit the ultrasonic wave. The method for measuring the depth of a quench-hardened layer according to claim 1, 2, 3, 4, or 5. 7. The temperature of the liquid is measured in advance, and the distance from the surface of the focal point is displaced in the depth direction based on the measured value, according to claim 1, 2, 3, 4, 5 or 6. Method for measuring the depth of quench-hardened layer. 8. The intensity of at least one of a surface reflected wave and a boundary reflected wave is detected, and a warning signal is issued when the intensity is less than a threshold value.
The method for measuring the depth of a quench-hardened layer according to 4, 5, 6 or 7.