JPS60198452A - Surface wave probe device - Google Patents

Abstract

PURPOSE:To perform high-precision flaw detection while reducing the area of a water dipped type probe by employing a water column nozzle coupling system for the acoustic coupling of the water dipped type probe, fitting a partition film having a thin hole atop of a nozzle, and spouting water from the thin hole and wetting a contact surface. CONSTITUTION:The water column nozzle 13 made of plastic is provided to the lower part of the internal pipe of the water dipped type probe 11, the partition film 17 is fitted atop of it, and the thin hole 19 is bored. The probe 11 is provided with a feed water pipe 14 and water is flowed to the water column nozzle 13; and an external cylinder 15 is provided outside of the water column nozzle 13 to such the space 150 in the external cylinder 15. Then, the probe 11 is brought into contact with an objective body 20, the contact surface is wetted with water from the thin hole 19 of the partition film 17, and water staying on the contact surface is sucked through the external cylinder 15. Thus, ultrasonic flaw detection is performed on water column nozzle basis by using the partition film, so water wetting does not become excessive between the probe and objective body and the flaw detection is carried out easily with high precision while the contact surface of the probe is reduced in size even if the surface of objective body has undulations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a surface wave probe device used for inspecting defects on the surface of a test material using ultrasonic waves.

[Prior art]

FIG. 1 is a sectional view showing an example of a conventional surface wave probe device, which is described in Japanese Patent Publication No. 58-32695. In FIG. 1, a housing 1 has a shape that covers five sides of the probe 2 except for the acoustic projection surface, and has a U-shaped cross section.

Reference numeral 6 denotes a probe shoe attached to the lower end surface of the housing 1, which has a mouth-shaped opening into which the probe 2 can be inserted. This is a view of the child device viewed from the bottom side, and the bottom surface of the probe shoe has a plurality of first grooves 4 carved in four directions, and also surrounds the probe 2 and has a groove at the mouth. A plurality of second grooves 5 are carved in the shape of a letter, and the second grooves 5 communicate with the first grooves 4. A first flow channel 9 is a gap between the probe 2 and the housing 1 through which water flows in order to form a water film in the gap 8 between them. This gap 9 sucks the overflowing water from the water belly formed in the gap 8 between the probe 2t and the surface 7, 1- of the test material through the first flow channel 6, and drains it out of the probe device. It functions as a second flow channel for the drain sump.

In the above probe device, during flaw detection, the groove 4 and the surface 7 of the material to be inspected are
Along with the air 10 that is sucked in between the two, water that is about to drain out of the probe device is sucked and discharged out of the probe device through the entire groove 5 and second flow channel 9.

However, in conventional devices with such a configuration, the acoustic coupling between the probe and the specimen is a water film coupling method, so the external shape of the probe device in the planar direction is relatively large. Therefore, the circumference of the contact surface of the contact shoe that comes into contact with the test material is long, the spread of the contact surface is large, and the space in which a water film should form is large. Despite the fact that water is required, the suction effect of the vacuum device is poor,
Particularly when there are irregularities or ridges on the surface of the material to be inspected, there are problems in that suction becomes unstable and water removal becomes incomplete. In addition, if the material to be inspected has a curved surface, the probe shoe must have a curvature, so whenever the surface curvature of the material to be inspected changes, it is necessary to convert it to a shoe that matches the curvature. It also had the disadvantage that it was cumbersome.

[Object of the present invention] The present invention has been made by focusing on the problems of the conventional apparatuses as described above. The aim is to realize a surface wave probe device in which the suction effect does not change.

[Summary of the present invention] The surface wave probe device according to the present invention uses a water column coupling for acoustic coupling between the probe and the test material using a nozzle, and all soft plastic tubes are provided concentrically with the nozzle. A vacuum device is used to perform suction in the gap between the pipe and the soft plastic tube, and a soft rubber or polyethylene film with minute slits or pores throughout is installed at the tip of the nozzle to reduce the amount of water supplied. Feature 7! /X exists.

[Explanation based on examples]

FIG. 3 is a structural sectional view showing an example of the device according to the present invention. In this figure, reference numeral 11 is a probe holder, and reference numeral 12 is a water immersion probe mounted in a hole provided above the central axis CL of the probe holder 11. Reference numeral 16 denotes a water column nozzle made of, for example, a plastic tube attached to a hole provided at the bottom of the central axis CL. The plastic pipe used for the water column nozzle 16, which communicates with the provided water supply hole 14, is made so that the nozzle tip does not bend or deform due to contact with the surface of the test material 200. It is preferable to use a material that is extremely hard, such as nylon or a resin material such as Delrin.

15 is an outer cylinder made of a plastic tube fitted coaxially with the water column nozzle 16 below the probe holder 11;
A gap 150 having an annular cross section is formed between the outer cylinder 15 and the water column nozzle 13.

This gap 150 is in communication with a drainage hole 16 extending in the lower part of the probe holder 11 in a direction perpendicular to the central axis CL.

FIG. 4 is an enlarged explanatory view of the tip portion of the water column nozzle 13 shown in FIG. 6. The tip of the water column nozzle 16 is covered with a tip cap 18 having a material whose acoustic impedance is close to that of water, such as a thin urethane rubber film or polyethylene film 17. This membrane 17 is a membrane that restricts the tip of the water column nozzle 16 so that water does not flow out excessively from the tip of the nozzle, and at the same time, it allows water to act as an acoustic medium between the surface 20 of the material to be inspected and the membrane. A suitable number of pores 19 are provided in a portion of the membrane for supplying the water. Note that this film thickness is selected to be λ/4 or an odd multiple of λ/4 with respect to the wavelength λ of the ultrasonic wave.

In order to operate the surface wave probe device explained above,
As shown in FIG. 5, a needle valve 21 for minute flow rate adjustment is provided in the flow path of the water supply system and connected to a water supply source 30, for example, a head tank.

In addition, in FIG. 6, the reference numeral 26 is a bubble remover,
It consists of a poppet 24 and a coil spring 25. When the poppet 24 is pressed with a fingertip, the poppet lube sheet opens and water near the probe acoustic projection surface is discharged, and if air bubbles are present, they are removed together with the water.

In addition, the tip of the water column nozzle 16 and the tip of the outer cylinder 15 are
As shown in Figure 4, cutting diagonally and giving an angle at an angle corresponding to the angle of incidence that generates a surface wave is, needless to say, a condition for incandescence. It goes without saying that means are required to hold the tactile device at the required angle of incidence.

The operation of the apparatus according to this embodiment configured as above will be described next.

In FIG. 6, water supplied to the water supply port 14 forms a water column extending from the acoustic projection surface of the probe 12 to the diaphragm film 17 at the tip of the water column nozzle. Since the amount of water supplied is only to replenish the water flowing out from the pores 19 provided in the diaphragm 17, only a very small amount of water is required. The flow i is regulated by a needle valve 21 . The water flowing out from the pores 19 of the membrane 17 is
As shown in the figure, there is a minute void 1!1! between the surface 20 of the test material and the cutoff film 17! 'It penetrates and fills by surface tension.

At this time, the barrier membrane 17 is in almost intimate contact with the surface 20 of the test material due to the head pressure in the water column and the negative pressure caused by evacuation from the suction port, which will be described later. Overflowing water and residual water due to the relative movement of the nozzle tip with the test control surface 20 are sucked by vacuum exhaust applied to the gap 150 between the water bottle 15 and the outer peripheral surface of the water column nozzle 13, and are sucked into the suction port 16. It goes without saying that before starting the flaw detection, it is necessary to press the air bubble removal poppet 24 with your finger to remove air bubbles so that there are no air bubbles in the water column.

The device according to this embodiment is based on a water column coupling method using a water column nozzle, and improves the problem of water amount by using a sieve membrane and pores provided in the sieve membrane, which solves the problem of excessive water consumption in the nozzle method. This method is characterized by completely removing excess water, which is the biggest problem in surface wave flaw detection. -There is a possibility that the reflection from the surface of the test material due to the thin film, that is, the surface echo, may cause problems such as the waveform being slightly expanded. However, it often causes no problems at all.

In addition, in FIG. 4, an example has been described in which the barrier membrane 17 [pores 19 are provided to restrict the outflow water from the water column, but the outflow water can be restricted not only by the pores but also by minute slits. You can get the same effect.

Further, the cross-sectional shape of the inner wall of the probe holder 11 and the cross-sectional shapes of the water column nozzle 13 and the outer cylinder 15 can be appropriately deformed to a shape corresponding to the shape of the probe 12. For example, when the probe 12 is If it is circular, it may be circular, and if it is rectangular, it may be rectangular or oval.

[Effects of the present invention]

As explained above, the device according to the present invention achieves various effects as listed below.

Since it uses a medium water column bonding method, the area that comes into contact with the material to be tested is small, and even if the surface of the material to be tested has undulations, the suction effect will not change. 1. Even if the surface of the material to be inspected is curved, there is no need to completely replace the nozzle and outer cylinder unless the curvature changes significantly.

(Since flaw detection is carried out with the n+ L cut-off film in close contact with the surface of the test material, the amount of water interposed between the cut-off film and the surface of the test material is minimal, and excess water can be completely disposed of. .

(Curved) Since the area of the annular gap between the water column nozzle and the outer cylinder can be reduced, the suction port for vacuum suction is narrowed, so the suction effect is good and excess water is completely removed.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional surface wave probe device.
2 is a view of the surface wave probe device shown in FIG. 1 viewed from below, FIG. 3 is a sectional view of the surface wave probe device according to an embodiment of the present invention, and FIG. FIG. 5 is an enlarged explanatory view of the tip of the water column nozzle in the figure, and FIG. 5 is a schematic diagram of the water supply system of the surface wave probe device of FIG. 3. 11--Probe holder, 12--Probe, 16-
... Water column nozzle, 14 ... Water supply hole, 15 ... Outer cylinder,
150... Void, 17... Screen membrane, 19... Pore. Agent Patent Attorney Sanro Kimura Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] (1) A surface wave probe device in which the acoustic coupling between the probe and the test material is water column coupling using a nozzle, which is fitted coaxially with the nozzle with a slight gap between the probe and the sample. At the same time, a barrier membrane having minute slits or pores is provided at the tip of the nozzle, and the gap is communicated with a suction means so that surplus water remaining from the water flowing out from the tip of the nozzle can be sucked. A surface wave probe device characterized by: