JPS6291807A - Measuring method for depth of surface reformed layer by ultrasonic wave - Google Patents

Abstract

PURPOSE:To measure depth of a surface reformed layer with a high accuracy by transmitting diagonally an incident ultrasonic wave to the surface reformed layer and measuring its reflection time. CONSTITUTION:An attenuation suppressing body 8 is allowed to contact closely to an attenuation suppressing film 8'. Subsequently, an ultrasonic probe 1 is placed on a surface formed layer 6 and an incident ultrasonic wave is transmitted diagonally from a transmitting vibrator 3. An emitted ultrasonic wave W1' which has reached right under a shielding body 9 and has been reflected by the surface of the reformed layer 6 is received by a receiving vibrator 4. Also, an emitted ultrasonic wave W2' which has been reflected by an interface 11 of the reformed layer 6 and a body 7 is also received by the vibrator 4. Also, an emitted ultrasonic wave W3' which has reached the vicinity of the shielding body 9 and has been reflected by the surface of the reformed layer 6 collides against the shielding body 9 and its transmission to the vibrator 4 side is obstructed. Accordingly, by making the ultrasonic wave W3' which is not contributed to a measurement ineffective, the measuring accuracy is improved. Also, the time extending from the oscillation to the reception of the ultra sonic wave W1' and W2' is measured, and from this measuring time, the depth of the surface reformed layer 6 is derived with a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION A6 Object of the Invention (1) Industrial Application Field The present invention relates to a method for measuring the depth of a surface-modified layer using ultrasonic waves.

(2) Conventional technology Conventionally, when measuring the depth of a surface-modified layer of a metal member, such as a surface hardening layer, a chill layer, an alloy layer formed by diffusion coating, etc., a test piece is cut out from the metal member and tested. Techniques used include polishing the cut surface of a piece and observing the polished surface using a microscope, or measuring the hardness of the polished surface with a microhardness meter.

(3) Problems to be Solved by the Invention However, according to the above method, there is a problem in that a large number of steps are required to measure the depth of the modified layer.

In view of the above, an object of the present invention is to provide a non-destructive method for measuring the depth of a surface-modified layer that uses ultrasonic waves and eliminates the need for operations such as cutting out and polishing a test piece.

B0 Structure of the Invention (1) Means for Solving Problems The present invention is a method for measuring the depth of a surface-modified layer formed on the surface of a main body and having a structure different from that of the main body, comprising: An incident ultrasonic wave is transmitted obliquely to the surface modified layer, the incident ultrasonic wave is reflected at the interface between the surface modified layer and the main body, and the output ultrasonic wave is emitted from the surface modified layer due to the reflection. The method is characterized in that the time from the transmission of the incident ultrasonic wave to the reception of the emitted ultrasonic wave is measured, and the time is converted into the depth of the surface modified layer.

(2) Effect Since the incident ultrasonic waves are made obliquely incident on the surface modified layer, the time resolution from the emission of the incident ultrasonic waves to the reception of the emitted ultrasonic waves is good, and the time from the emission to the reception can be accurately measured. can do. By converting this measurement time into the depth of the surface modified layer, the depth can be determined with high accuracy.

(3) Embodiment FIG. 1 shows an ultrasonic probe 1 used for carrying out the present invention, in which a transducer holder 2 includes a transmitting transducer 3 and a receiving transducer 4. is retained. The transmitting transducer 3 is arranged at an angle so that the incident ultrasonic waves emitted therefrom can obliquely enter the surface modified layer 6 of the metal member 5, and the receiving transducer 4 are disposed obliquely so that they can receive the obliquely emitted outgoing ultrasonic waves that are reflected at the interface 11 between the surface-modified N6 and the main body 7, and both transducers 3.4 are It has a symmetrical arrangement with respect to the bisector.

Further, a damping suppressor 8 made of synthetic resin such as acrylic resin is fixed to the vibrator holder 2 . The attenuation suppressor 8 suppresses attenuation of incident and outgoing ultrasonic waves while allowing them to pass through. In order to suppress attenuation, it is necessary to prevent air propagation of both ultrasonic waves. In order to satisfy this requirement, the damping suppressor 8 is brought into close contact with the transmitting surface 3a of the transmitting vibrator 3, the receiving surface 4a of the receiving vibrator 4, and the surface of the surface modified layer 6.

The vibrator holder 2 is placed on the bisector between both vibrators 3 and 4.
and cork, rubber, etc. so as to divide the damping suppressor 8 into two.
A shielding body 9 made of synthetic resin or the like is provided. This shield 9 prevents the receiving transducer 4 from receiving emitted ultrasonic waves that do not contribute to measurement due to reflection of incident ultrasonic waves on the surface of the surface-modified layer 6 .

Both transducers 3.4 are connected to an oscillograph IO, and the oscillograph 10 records received ultrasonic waves as waveforms over time.

Next, depth measurement of the surface modified layer 6 will be explained.

The sliding surface of the sliding member 5 made of gray cast iron (JIS Fe12) as a metal member is subjected to high-temperature heating such as plasma heating or laser heating to re-melt the sliding surface and then cooled to form a chilled structure. It is composed of a surface modified layer 6. The metal weave of the main body 7 remains a gray cast iron structure.

An organic solvent such as ethylene glycol, machine oil, etc. is applied to the surface of the surface modified layer 6 to form a thin attenuation suppressing film 8', thereby smoothing the surface of the surface modified layer 6.

The ultrasonic probe 1 is connected to the attenuation suppressing body 8 by an attenuation suppressing film 8'.
is placed on the surface modified layer 6 in close contact with the surface of the substrate. In this case, the attenuation suppressing film 8' prevents air from entering between the attenuation suppressing body 8 and the surface modified layer 6.

An incident ultrasonic wave with a frequency of 5 to 20 MHz is obliquely transmitted from the transmitting vibrator 3 and transmitted through the attenuation suppressor 8 and the attenuation suppressing film 8'. Among the incident ultrasonic waves, the outgoing ultrasonic waves Wl' associated with the waves Wl that reach directly below the shielding body 9 and are reflected on the surface of the surface modified layer 6 are transmitted through the attenuation suppressing film 8' and the attenuation suppressing body 8 and are received. received by the transducer 4.

Also, among the incident ultrasonic waves, the waves that are incident on the surface modified layer 6 are
The emitted ultrasonic wave W2' generated by the reflection of z at the interface 11 between the surface modified layer 6 and the main body 7 is transmitted through the attenuation suppressing film 8' and the attenuation suppressing body 8, and is received by the receiving transducer 4. be done.

Furthermore, the W of the incident ultrasonic waves that reaches the vicinity of the shielding body 9
The emitted ultrasonic wave W3' generated by the reflection of the ultrasonic wave W3' on the surface of the surface modified layer 6 collides with the shielding body 9 and is blocked from transmitting to the receiving transducer 4 side. The measurement accuracy is improved by disabling the ultrasonic wave W3'.

As described above, the incident ultrasonic wave W5. W2
is incident on the surface modified layer 6 obliquely, so that the surface modified layer 6
Incident ultrasonic wave W at the surface and the interface 11 between it and the body 7
The time resolution of l and W2 is improved. Also, the damping suppressor 8
and the incident ultrasonic waves W,, W! due to the attenuation suppression layer 8'. Also, since the air propagation of the emitted ultrasonic waves W1' and WZ' is prevented and their attenuation is suppressed, the reduction in the amount of ultrasonic waves received by the receiving transducer 4 is suppressed.

Outgoing ultrasonic waves W, ' received by the receiving transducer 4
, Wg' are recorded as waveforms by the oscillograph 10.

FIG. 2 shows the waveforms of the oscilloscope 10. The a wave is generated when the incident ultrasonic wave W1 is reflected on the surface of the surface modified layer 6, and the b wave is generated when the incident ultrasonic wave W2 is reflected between the surface modified layer 6 and the main body. This occurs due to reflection at the interface 11 with 7. Therefore, by finding the difference between the generation time T2 of the b wave and the generation time T1 of the a wave, the difference between the emission of the incident ultrasonic wave W2 and the output ultrasonic wave Wz'
The time until reception is measured.

FIG. 3 is a graph showing the relationship between the time from transmission to reception and the depth of the surface number tl. For example, time T2 and T,
If the difference is 1 μsec, the depth of the surface modified layer 6 is approximately 1 μsec.
．． It is converted to 2 cranes. Such a graph can be obtained by repeatedly applying the above measurement method to various test pieces having different depths of the surface modification layer and whose depths are known.

The depth measurement of the surface modified N6 by the ultrasonic probe 1 is as follows:
It is particularly effective when the depth of the layer 6 is in the range of 0.3 to 3.0 mm, and the measurement error is ±0.05 mm, which is highly accurate.

In this case, the incident angle of the incident ultrasonic wave W2 at the interface 11 between the surface modified layer 6 and the main body 7 (reflection angle of the emitted ultrasonic wave W2')
It is appropriate that α and the angle β between the slope and the bottom surface of the damping suppressor 8 are respectively 10 to 30°. In the ultrasonic probe 1, α and β are each set to approximately 21″.

FIG. 4 shows a modification of the ultrasonic probe 1, in which the attenuation suppressor 8
Transmitting and receiving transducers 3 and 4 are embedded inside.

C1 Effects of the Invention According to the present invention, it is possible to provide a non-destructive method for measuring the depth of a surface modified layer that uses ultrasonic waves to facilitate measurement work and obtain highly accurate values. can.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view showing the implementation state of the measuring method of the present invention;
Figure 2 is an oscillograph waveform diagram, Figure 3 is a graph showing the relationship between the depth of the surface modification layer and the time from transmission to reception of ultrasound, and Figure 4 is a longitudinal cross-section of a modified example of the ultrasound probe. It is a front view. w,, W2. W3...Incoming ultrasound, W,', Wt'. W='...Emission ultrasonic wave, ■...Ultrasonic probe, 3... Transmission transducer, 3a.
... Transmission surface, 4... Reception transducer, 4a... Receiving surface, 6... Surface modified layer, 7... Main body, 8... Damping suppressor, 9... Shielding body , 11... Interface Figure 1 (psec) Figure 4

Claims (1)

[Claims] A method for measuring the depth of a surface modified layer formed on the surface of a main body that has a different structure from that of the main body, the method comprising: transmitting incident ultrasound obliquely to the surface modified layer; Receiving an emitted ultrasonic wave that is reflected at the interface between the surface modified layer and the main body and emitted from the surface modified layer due to the reflection, and the time from transmission of the incident ultrasonic wave to reception of the emitted ultrasonic wave. A method for measuring the depth of a surface modified layer using ultrasonic waves, the method comprising measuring the time and converting the time to the depth of the surface modified layer.