CN113406213B - Curved surface sound-transmitting wedge design method for circumferential ultrasonic detection of small-diameter pipe - Google Patents

Abstract

The invention discloses a method for designing a curved surface sound-transmitting wedge for circumferential ultrasonic detection of a small-diameter pipe, which comprises the following steps of: 1) Determining parameters of the ultrasonic probe body corresponding to the curved surface acoustic transmission wedge; 2) Determining a combination mode of the curved surface sound-transmitting wedge and the ultrasonic probe body; 3) Determining materials of the curved surface sound-transmitting wedge; 4) Determining the radius of the curved surface sound-transmitting wedge; 5) Determining the position of the curved surface vertex of the curved surface sound-transmitting wedge; 6) Judging whether the ultrasonic sound beam generated by the square wafer in the ultrasonic probe body can be completely covered by the curved surface of the curved surface sound-transmitting wedge; 7) The method can effectively avoid the problems of poor coupling, difficult fixation of a detection position and large artificial error when the plane acoustic transmission wedge is used for detecting the small-diameter pipe, can effectively improve the coupling condition, changes the linear contact during detection into the surface contact, and improves the stability of detection and the accuracy of defect positioning.

Description

A Design Method of Curved Surface Acoustic Wedge for Circumferential Ultrasonic Testing of Small-diameter Pipes

technical field

The invention belongs to the field of non-destructive testing of thermal power plants, and in particular relates to a design method of a curved sound-transmitting wedge for circumferential ultrasonic testing of small-diameter tubes.

Background technique

Small-diameter tubes such as heating surface tubes for power plant boilers are made of steel ingots or solid tube billets through perforation to make capillary tubes, and then hot-rolled, cold-rolled or cold-drawn. In the production process, if the quality control is not good, the base metal of the small-diameter tube is generally prone to longitudinal linear defects. The existence of such defects will bring hidden dangers to the safe operation of the boiler. Cracks are easy to initiate and expand here, until the small-diameter tube on the heating surface The leak caused an unplanned outage. Longitudinal linear defects of small-diameter tubes can be detected by surface inspection methods such as eddy current, magnetic particle or infiltration in the manufacturing plant. However, for small-diameter tubes on the heating surface of in-service boilers, due to dense tube rows and small spacing between tubes, the detection space is limited. Eddy current testing, magnetic particle or penetrant testing are all inconvenient to implement, and there are detection blind spots, which may easily cause defects to be missed.

At present, for the longitudinal linear defects of small-diameter tubes, the more commonly used method is ultrasonic testing: the ultrasonic detector is used to excite the wafer in the ultrasonic probe to generate ultrasonic longitudinal waves, and the longitudinal waves are transformed into transverse waves by the sound-transmitting wedge at the detection interface. , surface waves, creeping waves, etc. enter the inside of the small-diameter tube, and scan the small-diameter tube in a circumferential direction by moving the probe to complete the detection of longitudinal linear defects. Due to the large surface curvature of the small-diameter tube, the coupling contact of the plane sound-transmitting wedge of the ordinary probe on the outer surface of the small-diameter tube is theoretically a line, and the coupling condition is not good. Most of the sound beam emitted by the chip cannot enter the workpiece, and the probe touches the line. The randomness of the position is relatively large, and it changes with the change of detection time and detection position, and the human influence factor is also large. Therefore, it is necessary to invent a method to design the sound-transmitting wedge during the circumferential ultrasonic detection of small-diameter pipes to improve the coupling. Conditions, change the line contact during detection to surface contact, improve the stability of detection and the accuracy of defect location.

Contents of the invention

The object of the present invention is to provide a method for designing a curved sound-transmitting wedge for circumferential ultrasonic detection of small-diameter pipes, which can effectively avoid poor coupling and difficulty in fixing the detection position when using a plane sound-transmitting wedge to detect small-diameter pipes , The problem of large human error, improve the coupling conditions, change the line contact during detection to surface contact, improve the stability of detection and the accuracy of defect location.

In order to achieve the above purpose, the design method of the curved sound-transmitting wedge for circumferential ultrasonic detection of small-diameter pipes according to the present invention includes the following steps:

1) Determine the parameters of the ultrasonic probe body corresponding to the curved sound-transmitting wedge;

2) Determine the combination mode of the curved surface sound-transmitting wedge and the body of the ultrasonic probe;

3) Determine the material of the curved surface acoustic wedge;

4) Determine the curved surface radius of the curved sound-permeable wedge;

5) Determine the position of the apex of the curved surface of the sound-permeable wedge;

6) Judging whether the ultrasonic sound beam produced by the square chip in the ultrasonic probe body can be completely covered by the curved surface of the curved sound-permeable wedge;

7) According to the judgment result of step 6), calculate the offset of the ultrasonic incident point of the curved sound-transmitting wedge relative to the plane sound-transmitting wedge, and complete the design of the curved sound-transmitting wedge for circumferential ultrasonic testing of small diameter pipes.

The parameters of the ultrasonic probe body corresponding to the curved surface acoustic wedge include the side length of the square chip in the ultrasonic probe body and the incident angle of the ultrasonic probe body;

The combination of the curved sound-transmitting wedge and the corresponding ultrasonic probe body is detachable or integrated.

The material of the curved sound-permeable wedge is organic glass or polymer material.

The radius of curvature of the curved sound-permeable wedge should be equal to the radius of curvature of the outer surface of the small-diameter tube to be tested.

The vertex of the curved sound-transmitting wedge surface is located on the center line of the incident sound beam of the square chip in the ultrasonic probe body, the vertex of the curved surface is the incident point of the ultrasonic probe body, and the angle between the vertical line passing through the vertex of the curved surface and the center line of the incident sound beam is the ultrasonic probe The incident angle of the body.

The ultrasonic sound beam generated by the square chip in the ultrasonic probe body can be completely covered by the curved surface of the curved sound-transmitting wedge, wherein the critical radius r of the curved surface of the curved sound-transmitting wedge _is :

Wherein, a is the side length of the square wafer in the ultrasonic probe body, and α is the incident angle of the ultrasonic probe body sound beam;

_When the radius of curvature of the curved sound-transmitting wedge r≥r, the ultrasonic sound beam generated by the square chip in the ultrasonic probe body is completely covered by the curved surface of the curved sound-transmitting wedge, otherwise, it cannot be completely covered.

The offset of the ultrasonic incident point of the curved sound-transmitting wedge relative to the plane sound-transmitting wedge includes the horizontal offset δ and the depth offset d;

Among them, when the ultrasonic sound beam can be completely covered by the curved surface of the curved sound-permeable wedge, then there is

d=δ·cot(α) (3)

When the ultrasonic sound beam cannot be completely covered by the curved surface of the curved sound-permeable wedge, then:

δ＝d·tan(α) (5)

Wherein, a is the side length of the square chip in the body of the ultrasonic probe, α is the incident angle of the sound beam of the body of the ultrasonic probe, and r is the radius of curvature of the curved surface of the sound-transmitting wedge.

The present invention has the following beneficial effects:

The method for designing the curved sound-transmitting wedge for circumferential ultrasonic detection of small-diameter pipes according to the present invention is to determine whether the ultrasonic sound beam generated by the square wafer in the ultrasonic probe body can be completely covered by the curved surface of the curved sound-transmitting wedge during specific operations. And use this to calculate the offset of the ultrasonic incident point of the curved surface acoustic wedge relative to the plane acoustic wedge, so that the transmission path of the ultrasonic wave can be accurately traced during inspection, and the accuracy of defect location is improved. At the same time, the curved surface acoustic wedge is used to replace the traditional plane Acoustic wedge, to avoid the problems of poor coupling, difficult to fix the detection position, and large human error in the detection of small-diameter pipes by using planar acoustic wedges, improve the coupling conditions, change the line contact during detection to surface contact, and further improve the detection accuracy.

Description of drawings

Fig. 1 is a flowchart of the present invention;

Fig. 2 is a schematic diagram of the combination of the detachable sound-transmitting wedge and the ultrasonic probe body 1;

Fig. 3 is a schematic diagram of the combination of the integrated embedded sound-transmitting wedge and the ultrasonic probe body 1;

Fig. 4 is a schematic diagram when the ultrasonic sound beam cannot be completely covered by the curved surface of the curved sound-transmitting wedge 2;

Fig. 5 is a schematic diagram of the deviation of the ultrasonic incident point when the curved sound-transmitting wedge 2 is relative to the plane sound-transmitting wedge.

Among them, 1 is the body of the ultrasonic probe, 2 is the curved sound-transmitting wedge, 3 is the fastening screw, 4 is the square chip, and 5 is the small-diameter tube to be inspected.

Detailed ways

The present invention is described in further detail below in conjunction with accompanying drawing:

Referring to Fig. 1, the method for designing a curved sound-transmitting wedge for circumferential ultrasonic testing of small-diameter pipes according to the present invention includes the following steps:

1) Determine the parameters of the ultrasonic probe body 1 corresponding to the curved sound-transmitting wedge 2;

The parameters of the ultrasonic probe body 1 corresponding to the curved sound-transmitting wedge 2 include the side length of the square chip 4 in the ultrasonic probe body 1 and the incident angle of the ultrasonic probe body 1;

2) Determine the combination mode of the curved sound-transmitting wedge 2 and the ultrasonic probe body 1;

The combination of the curved sound-transmitting wedge 2 and the corresponding ultrasonic probe body 1 is a detachable or integrated embedded type, wherein, in the detachable combination, the curved-surface sound-transmitting wedge 2 and the ultrasonic probe body 1 are connected by fastening screws 3 , and apply coupling agent on the contact area of the two to form a small-diameter tube circumferential detection probe as a whole. For disassembly, refer to Figure 3.

3) Determine the material of the curved sound-transmitting wedge 2;

The material of the curved sound-transmitting wedge 2 is organic glass or polymer material. The propagation velocity of ultrasonic longitudinal wave in the organic glass is about 2700m/s, and the propagation velocity of ultrasonic longitudinal wave in polymer material is about 1400m/s.

4) Determine the curved surface radius of the curved surface sound-transmitting wedge 2;

The radius of curvature of the curved sound-permeable wedge 2 should be equal to the radius of curvature of the outer surface of the small-diameter tube 5 to be tested.

5) Determine the position of the vertex of the curved surface sound-transmitting wedge 2;

The apex of the curved sound-transmitting wedge 2 is located on the center line of the incident sound beam of the square chip 4 in the ultrasonic probe body 1, and the apex of the curved surface is the incident point of the ultrasonic probe body 1, referring to point A in Fig. 4 and point A in Fig. 5 _2. The angle between the vertical line passing through the vertex of the curved surface and the centerline of the incident sound beam is the incident angle of the ultrasonic probe body 1, from the incident angle α marked in Figs. 4 and 5.

6) judging whether the ultrasonic sound beam produced by the square chip 4 in the ultrasonic probe body 1 can be completely covered by the curved surface of the curved sound-transmitting wedge 2;

Try to ensure that the ultrasonic sound beam generated by the square chip 4 in the ultrasonic probe body 1 can be completely covered by the curved surface of the sound-permeable wedge. If the radius of the curved surface of the sound-permeable wedge cannot completely cover the ultrasonic sound beam, try to maximize the coverage area. Referring to FIG. 4 , the ultrasonic sound beam is not completely covered by the curved surface of the curved sound-transmitting wedge 2 ; referring to FIG. 5 , it is the case where the ultrasonic sound beam is completely covered by the curved surface of the curved sound-transmitting wedge 2 .

The ultrasonic sound beam generated by the square wafer 4 in the ultrasonic probe body 1 can be completely covered by the curved surface of the curved sound-transmitting wedge 2, wherein the critical radius r of the curved surface of the curved sound-transmitting wedge 2 _is :

Wherein, a is the side length of the square wafer 4 in the ultrasonic probe body 1 , and α is the incident angle of the sound beam of the ultrasonic probe body 1 .

When the radius of curvature of the curved acoustic wedge 2 _is r≥r, the ultrasonic sound beam generated by the square chip 4 in the ultrasonic probe body 1 is completely covered by the curved surface of the curved acoustic wedge 2 , otherwise, it cannot be completely covered.

For example: when the side length a of the chip is a=6mm, and the incident angle of the sound beam of the ultrasonic probe body 1 is α=64°, it can be calculated that _r =29.64mm, that is, when the radius of the curved surface is greater than or equal to 29.64mm, the designed chip and incident Under the angle, the parallel sound beam can be completely covered by the curved surface of the curved sound-permeable wedge 2, that is, it can be completely covered by the small-diameter tube under inspection.

7) Calculate the offset of the ultrasonic incident point of the curved sound-transmitting wedge 2 relative to the plane sound-transmitting wedge according to the judgment result of step 6), and complete the design of the curved sound-transmitting wedge 2 for circumferential ultrasonic testing of small-diameter pipes.

The incident point offset includes a horizontal offset δ and a depth offset d. Referring to Fig. 5, when the sound-transmissive wedge is a plane, the incident point of the ultrasonic waves emitted by the square wafer 4 is A ₁ ; when the sound-transparent wedge is a radius When r is a curved surface, the incident point of the ultrasonic waves emitted by the square chip 4 is shifted to point _A2 , and the projection length of the line connecting point _A1 and point _A2 on the horizontal part of the bottom surface of the curved sound-transmitting wedge 2 is the horizontal deviation of the incident point. The displacement δ, the projected length along the radial direction of the sound-transmitting wedge surface is the depth direction offset d of the incident point, which can be determined according to whether the ultrasonic sound beam generated by the square chip 4 in the ultrasonic probe body 1 can be completely covered by the sound-transmitting wedge surface , calculated according to the formula:

When the ultrasonic sound beam can be completely covered by the sound-permeable wedge surface, then:

d=δ·cot(α) (3)

When the ultrasonic sound beam cannot be completely covered by the sound-permeable wedge surface, there are:

δ＝d·tan(α) (5)

Wherein, a is the side length of the square chip 4 in the ultrasonic probe body 1, α is the incident angle of the sound beam of the ultrasonic probe body 1, and r is the radius of curvature of the curved surface of the sound-transmitting wedge 2.

For example, if three typical specifications of small-diameter tubes on the heating surface of Φ45mm, Φ51mm, and Φ63.5mm are selected, the corresponding sound-transmitting wedge curvature radii r are 22.5mm, 25.5mm, and 31.75mm respectively, and the square chip 4 in the ultrasonic probe body 1 When the side length a is 6 mm, and the incident angle α of the ultrasonic probe body 1 is respectively selected as 60°, 62°, and 64°, whether the horizontal offset δ of the incident point, the depth offset d, and whether the ultrasonic sound beam can be sound-transparent The calculation results of the complete coverage of the wedge surface are shown in Table 1.

Table 1

Claims (5)

1. A method for designing a curved surface sound-transmitting wedge for circumferential ultrasonic detection of a small-diameter pipe is characterized by comprising the following steps:

1) Determining parameters of the ultrasonic probe body (1) corresponding to the curved surface acoustic transmission wedge (2);

2) Determining a combination mode of the curved surface sound-transmitting wedge (2) and the ultrasonic probe body (1);

3) Determining the material of the curved surface sound-transmitting wedge (2);

4) Determining the radius of the curved surface sound-transmitting wedge (2);

5) Determining the position of the curved surface vertex of the curved surface sound-transmitting wedge (2);

6) Judging whether the ultrasonic sound beam generated by the square wafer (4) in the ultrasonic probe body (1) can be completely covered by the curved surface of the curved surface sound-transmitting wedge (2);

7) Calculating the offset of the curved surface sound-transmitting wedge (2) relative to the ultrasonic incident point of the plane sound-transmitting wedge according to the judgment result of the step 6), and finishing the design of the curved surface sound-transmitting wedge (2) for the circumferential ultrasonic detection of the small-diameter pipe;

the vertex of the curved surface sound-transmitting wedge (2) is positioned on the central line of an incident sound beam of the square wafer (4) in the ultrasonic probe body (1), the vertex of the curved surface is an incident point of the ultrasonic probe body (1), and the included angle between the vertical line passing through the vertex of the curved surface and the central line of the incident sound beam is the incident angle of the ultrasonic probe body (1);

the ultrasonic sound beam generated by the square wafer (4) in the ultrasonic probe body (1) can be completely covered by the curved surface of the curved surface sound-transmitting wedge (2), wherein the critical radius r of the curved surface sound-transmitting wedge (2) _Face Comprises the following steps:

wherein a is the side length of a square wafer (4) in the ultrasonic probe body (1), and alpha is the incident angle of the sound beam of the ultrasonic probe body (1);

when the curvature radius r of the curved surface sound-transmitting wedge (2) is more than or equal to r _Face When the ultrasonic probe is used, the ultrasonic sound beam generated by the square wafer (4) in the ultrasonic probe body (1) is completely covered by the curved surface of the curved surface sound-transmitting wedge (2), otherwise, the ultrasonic sound beam cannot be completely covered;

the offset of the curved surface sound-transmitting wedge (2) relative to the ultrasonic incident point of the plane sound-transmitting wedge comprises a horizontal direction offset delta and a depth direction offset d;

wherein, when the ultrasonic sound beam can be completely covered by the curved surface of the curved surface sound-transmitting wedge (2), the ultrasonic sound beam has

d＝δ·cot(α) (3)

When the ultrasonic sound beam can not be completely covered by the curved surface of the curved surface sound-transmitting wedge (2), the following steps are provided:

δ＝d·tan(α) (5)

wherein a is the side length of the square wafer (4) in the ultrasonic probe body (1), alpha is the incident angle of the sound beam of the ultrasonic probe body (1), and r is the curvature radius of the curved surface sound-transmitting wedge (2).

2. The method for designing the curved surface acoustic transmission wedge for the circumferential ultrasonic detection of the small-diameter pipe according to claim 1, wherein the parameters of the ultrasonic probe body (1) corresponding to the curved surface acoustic transmission wedge (2) comprise the side length of the square wafer (4) in the ultrasonic probe body (1) and the incident angle of the ultrasonic probe body (1).

3. The design method of the curved surface acoustic transmission wedge for the circumferential ultrasonic detection of the small-diameter pipe according to claim 1, wherein the combination mode of the curved surface acoustic transmission wedge (2) and the corresponding ultrasonic probe body (1) is detachable or integrally embedded.

4. The design method of the curved surface acoustic transmission wedge for the small-diameter pipe circumferential ultrasonic detection according to claim 1, wherein the material of the curved surface acoustic transmission wedge (2) is machine glass or a high polymer material.

5. The method for designing the curved surface acoustic wedge for the circumferential ultrasonic detection of the small-diameter pipe according to claim 1, wherein the curvature radius of the curved surface acoustic wedge (2) is equal to the curvature radius of the outer surface of the small-diameter pipe (5) to be detected.

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