JPS6140563A - Ultrasonic inspection for press-fit part - Google Patents

Abstract

PURPOSE:To enable sensitive reception of a reflected wave due to a vertically cracked defect discriminated from those from press fit starting and finishing ends and the like, by emitting an ultrasonic wave to a press-fit part to receive reflected waves toward the cource different from the incident course. CONSTITUTION:A shaft 1 and an outer ring 2 and fastened together by shrink fitting and has a press-fit surface 12. As an impuse voltage 5a is generated with a pulser circuit 5, an ultrasonic pulse beam is of Is of transverse wave mode is transmitted from an angle beam probe 3. When there is no defect at the position 12S, reflected waves Rs of transverse wave mode are generated dominantly and received with the probe 3. On the other hand, when a vertical defect Fs is caused, a reflected wave RSF of transferse wave mode due to the defect is generated while a reflected wave RLF of longitudinal wave mode is generated and received with an ultrasonic probe 4 for longitudinal waves. Then, a defect signal RLF of longitudinal wave mode reaching a received signal amplifier 6 is selected with a gate circuit 7 and shown on a display unit 8. Thus, the existence of a defect is detected at the press-fit part.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an ultrasonic inspection method for a test object formed by press-fitting, such as a member of a rotating machine, an axle, etc. The present invention relates to an ultrasonic inspection method suitable for detecting defects by distinguishing between reflected waves and press-in echoes.

[Background of the invention]

It is well known that ultrasonic flaw detection has been used as a means of non-destructively detecting defects such as cracks that occur at the boundary between two members that have been conventionally fixed using methods such as shrink fitting, or press-fit parts. It is. However, even if there is no defect at all in the press-fit part, there is a problem in that reflected waves are generated at the press-fit start end or the press-fit end, and therefore it is judged as if a defect has occurred.
This was a hindrance when testing the part concerned.

[Purpose of the invention]

The purpose of the present invention is to detect the reflected waves from the press-fit starting end or the press-fit end, etc., which are the second obstacle to detecting defects in press-fit parts, as described above.
An object of the present invention is to provide an ultrasonic inspection method effective for detecting the above-mentioned defects by separately sensing so-called press-fit echoes and reflected waves mainly due to vertical warp-like defects that tend to occur at the start and end of press-fit. be.

[Summary of the invention]

As a model for the mechanism of the generation of the above-mentioned press-fit echo, the present invention considers that the press-fit start and end points correspond to the corners of the solid medium for ultrasonic waves.
This research is based on the discovery of an effective method for detecting defects by clarifying the differences in the ultrasonic reflection phenomenon when a crack-like defect exists in the area and when it does not.

In order to explain the ultrasonic reflection phenomenon in the press-fit part, which is the basis of the present invention, Figure 1 shows (a) no defect, (b) defect at the press-fit start end, and (C) defect at the press-fit end. We have modeled and shown each case where .

In the same figure (a), the starting end 128 and the terminal end 1 of the press-fit surface 12 where the shaft part 1 and the outer ring part 2 are press-fitted by shrink fitting or the like.
2E and the ultrasonic incident wave Is.

When Ig is incident, it is assumed that the press-fit surface 12 has the property of being semi-continuous acoustically and also has the property of being semi-boundary. At this time, both ends 12S and 12B of the press-fitting surface form a corner of the solid medium, so when the incident ultrasonic waves Is and Ig are incident on these points, two ends are formed at the tips of the corners, respectively. Subsequent so-called edge echoes RIB and R12z will occur.

This is a phenomenon known as press-fit echo in the field of ultrasonic flaw detection technology, and is an obstacle to detecting defects in corners.

It is now clear that when a transverse wave mode is used for the incident wave Is or (E), the end echo 128 or R12p is mainly a transverse wave mode, and its directional direction covers a wide angular range.

FIG. 1(b) shows that when there is a warp-like defect FB in a direction almost perpendicular to the press-fitting surface 12 at the starting end 128 of the press-fitting part, the incident of the ultrasonic beam 8 causes a reflected wave Rs in the transverse mode and a reflected wave in the longitudinal mode. FIG. 3 is a diagram showing a phenomenon that causes RLg.

Figure 1 (C) shows the phenomenon that even when a defect FE exists at the end 1.2E of the press-fit part, a reflected wave RhE in the longitudinal mode is generated along with a reflected wave RE in the transverse wave mode, similar to the case in (b) above. It shows.

As described above, the present invention is directed to vertical rib defects Fa at the press-fitting part.
, Fg, the incident waves Is, Ia in transverse mode
Focusing on the phenomenon in which a reflected wave RL[l, R+LE is generated in a longitudinal wave mode, the present invention provides a means for detecting a defect by receiving the signal of the reflected wave of the defect while distinguishing the signal of the press-fit echo.

In addition, in FIGS. 2 and 3, if the direction of the incident beam Is in the transverse wave mode is expressed by the angle θ1 with respect to the normal line of the press-fit surface 12, the direction in which the reflected wave Rr in the longitudinal wave mode is reflected is the direction of the reflection from the press-fit surface. If the angle with the 120 normal is 61, θl and θ,
The relationship shown in FIG. 4 is obtained by calculating the angle of reflection of the ultrasonic wave propagating through the steel material by the press-fit surface 12 and the defective surface F. However, FIGS. 2 and 3, which show the reflection paths that lead to this relationship, represent the cases where θ1 is larger than 45 degrees and the case where θ1 is smaller than 45 degrees, respectively. Further, Rs is a reflected wave in a transverse wave mode caused by the defect F.

The method and apparatus for ultrasonic inspection of a press-fitted part according to the present invention is characterized in that the transmitter and receiver are set so that the relationship between θ and θ shown in FIG. 4 is almost satisfied. There is.

Furthermore, as shown in FIG. 5, when the incident angle θ1 of the ultrasonic beam 8 is approximately 45 degrees, the waves reflected by the defect F include an angle θr1 smaller than 45 degrees and an angle θ larger than 45 degrees. Longitudinal wave modes RLI and RIL2 occur in both two angular directions. Numerical experiments on reflection phenomena have also revealed that the waves of both RL1 and RL2 are in an antiphase relationship with each other. Such characteristic phenomena are also applied to provide one practical condition included in the present invention.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG.

1 is a shaft portion, and 2 is an outer ring portion, both of which are fixed to each other by shrink fit and have a press-fit surface 12. Reference numeral 3 denotes a diagonal beam for transmitting a transverse wave mode ultrasonic pulse beam I8 in the direction of the θ cup, that is, toward the starting end 128 of the press-fit part currently being inspected, and for receiving the reflected transverse wave Rs arriving from the same direction. An angular probe 4 is a longitudinal wave ultrasonic probe that senses the longitudinal wave mode reflected wave RL8 generated by reflection at the defect FB located at the position 128.
11 Now, when an impulse voltage 5a for generating an ultrasonic pulse is generated in the pulser circuit 5 and applied to the probe 3, the beam Is of the ultrasonic pulse in the transverse wave mode is sent out from the probe. . If the position 128 is healthy with no defects, only the reflected wave R11, which is mostly in transverse wave mode, is generated here, follows the same path as the transmitted beam Is, is received by the probe 3 again, and the received signal is It becomes 3a. However, since no reflected wave in the longitudinal mode toward the probe 4 is generated, no received signal at the probe 4 appears.

On the other hand, if a nearly perpendicular defect F8 occurs at the position 128, the defect generates a reflected wave Ray in the transverse wave mode and a reflected wave RL F in the 1 longitudinal wave mode,
It is received by the probe 4. The directional direction of the reflected wave RL F at this time is related to the incident angle θ of the beam Is of the ultrasonic pulse, and is the angular direction θ1, which is related in FIG. The location where the image will be displayed is determined.

Next, the time tBL from when the transverse wave mode ultrasonic pulse Is is sent from the probe to when the longitudinal wave mode reflected wave RLF is received by the probe 4 is P3PP PrF3 fgL" + □ Vll VL Especially, As shown in Fig. 7, P3*P41 PF is the ultrasonic transmission and reception position in probe 3 and probe 4, respectively, PF is the position of defect Fs, and Vll and VL are the outer ring portions to be inspected, respectively. For example, in FIG. 6, after the pulser circuit 5 generates the transmission signal 5a, the defective signal RLF in the longitudinal wave mode that arrives at the reception signal amplifier 6 after a time tsLD is selected. By activating the gate circuit 7 provided with a timer (G) to output the defect signal 7a and displaying the arrival of the RILP signal on the display device 8, the existence of a defect in the press-fitted part is automatically detected. can be detected.

Another embodiment of the present invention will be described with reference to FIG.

Starting end 12 of the press-fitting part of the object 2 at an incident angle of 45 from the wave transmitter 3
When the beam Ill of the ultrasonic pulse in the transverse wave mode is transmitted toward the defect F in 8, the defect generates reflected waves RL P 1 and RLF2 in the longitudinal wave mode, which are received by the probes 41 and 42, respectively. .

The R t F t signal 41a received at 41 is converted into the R b P 2 signal 42a (10) received at 42 by the delay circuit 9.
. . and amplified by received signal amplifiers 61 and 62 to obtain signals 61a and 62a. As described in the explanation of FIG. 5, the reflected wave ratios LFI and RLP2 are in an antiphase relationship with each other, so that the signal 61a.

By performing phase discrimination on 62a by the phase discriminator 10, the presence of the defect F is displayed on the display device 8.

〔Effect of the invention〕

As mentioned above, by applying the ultrasonic inspection method and device for press-fit parts according to the present invention, it is possible to eliminate the problem of shrinkage, which has traditionally been difficult to accurately detect the presence or absence of defects due to the generation of press-fit echoes. This makes it possible to clearly detect defects, especially crack-like defects, that occur on or near the fixed surface due to defects.

For example, inspection of defects in equipment and structures such as axles for railway vehicles, rolling rolls, generators, etc., in which a ring-shaped member is fixed to the shaft body by shrink fit;
Confirmation of soundness, etc. can be performed non-destructively. Therefore, it is no longer necessary to inspect defects that involve disassembling or incising the specimen, which has been unavoidable in the past, and the inspection cost and time required can be significantly reduced. The effect of the surface is enormous.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the mode of ultrasonic reflection at the press-fitted part, which is the basis of the present invention, Figs. 2 and 3 are explanatory diagrams of the reflection path of ultrasonic waves due to defects forming corners, and Fig. 4 5 is a diagram showing the relationship between the angle of incidence of ultrasonic waves and the angle of reflection at a corner, FIG.
7 is an explanatory diagram of one embodiment of the present invention, FIG. 7 is a diagram showing the paths of transmitted and received waves corresponding to the embodiment of FIG. 6, and FIG. 8 is an explanatory diagram of another embodiment of the present invention. 1...Shaft part, 2...Outer ring part, 12...Press-fitting part, 1
2S... Press-fitting part start end, 12E... Press-fitting part end, 3.
... Ultrasonic wave transmitter, 4... Ultrasonic wave receiver for longitudinal waves, Is
...Incident wave in transverse wave mode, RL...Reflected wave in longitudinal wave mode, θ, ...7th Old $8 Patent Commissioner Manabu Shiga Case Display 1982 Patent Application No. 162336 Invention Name: Ultrasonic inspection method for press-fit parts

Claims (1)

[Claims] 1. An ultrasonic wave transmitter is provided at one position on the surface of a subject having a press-fitting part, and ultrasonic waves are made to enter the press-fitting part,
An ultrasonic inspection method for a press-fitted part, characterized in that the presence or absence of a defect in the press-fitted part is detected by receiving a reflected wave directed toward a path different from the path of incidence at another position on the surface of the object to be inspected. . 2. An ultrasonic inspection method for a press-fitted part according to claim 1, wherein the incident ultrasonic wave toward the press-fitted part is a transverse wave, and the received reflected wave is a longitudinal wave. 3. In the method described in claim 2, a wave transmitter is provided so that the incident angle of the ultrasonic wave toward the press-fitting part with respect to the press-fitting surface is smaller than 45 degrees, and the reflected wave is received. 1. An ultrasonic inspection method for a press-fitted part, characterized in that the wave receiver is provided so that the direction of orientation of the wave receiver is at an angle greater than the incident angle with respect to the press-fit surface. 4. In the method described in claim 2, a wave transmitter is provided so that the incident angle of the ultrasonic wave toward the press-fitting part with respect to the press-fitting surface is larger than 45 degrees, and the reflected wave is received. 1. A method for ultrasonic inspection of a press-fitted part, characterized in that the wave receiver is provided so that the direction of orientation of the wave receiver is at an angle smaller than the incident angle with respect to the press-fit surface. 5. In the method according to claim 2, the incident angle of the ultrasonic wave toward the press-fitting part with respect to the press-fitting surface is set to approximately 45
The transmitter is installed so that the wave receiver receives the reflected wave, and the direction of the receiver that receives the reflected wave is set at an angle greater than or equal to 45 degrees, or both at an angle relative to the press-fit surface. An ultrasonic inspection method for a press-fitted part, characterized by providing a corrugator. 6. In the method described in claim 5, the transmitter is arranged such that the direction of orientation of the receiver for receiving reflected waves is both at an angle smaller than 45 degrees and an angle greater than 45 degrees with respect to the press-fit surface. At least one pair of wave receivers are provided between the two wave receivers, and a means for discriminating that the phases of signals of reflected waves received by each wave receiver are inverted from each other is used. Sonic testing method. 7. In the method according to any one of claims 3 to 5, ultrasonic waves are transmitted from a wave transmitter, and reflected waves reflected by a defect in the press-fitted part of the object are transmitted to a receiver. 1. An ultrasonic inspection method for a press-fitted part, characterized in that the presence of a defect is determined based on a signal appearing at a temporal position reaching .