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) and (4) 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.

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.

6. 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 a vertex of a curved surface of the curved surface acoustic transmission wedge (2) is located on a 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 an included angle between a perpendicular line passing through the vertex of the curved surface and the central line of the incident sound beam is an incident angle of the ultrasonic probe body (1).

7. The design method of the curved surface acoustic transmission wedge for the small-diameter pipe circumferential ultrasonic detection according to claim 1, characterized in that 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 acoustic transmission wedge (2), wherein the critical radius r of the curved surface acoustic transmission wedge (2) is_FaceComprises 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_FaceWhen 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.

8. The design method of the curved surface acoustic-transparent wedge for the small-diameter pipe circumferential ultrasonic detection according to claim 1, wherein the offset of the curved surface acoustic-transparent wedge (2) relative to the ultrasonic incident point of the plane acoustic-transparent wedge comprises a horizontal direction offset δ 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).

Background

The small diameter pipes such as heating surface pipes for power station boilers are made by making steel ingots or solid pipe blanks into hollow pipes through perforation, and then hot rolling, cold rolling or cold drawing. In the production process, if the quality control is not good, the base metal of the small-diameter pipe generally easily generates longitudinal linear defects, the existence of the defects can bring hidden troubles to the safe operation of a boiler, cracks are easy to be initiated and expanded at the defects until the leakage of the small-diameter pipe on a heating surface causes unplanned shutdown accidents. The longitudinal linear defects of the small-diameter pipes can be detected by adopting surface detection methods such as eddy current, magnetic powder or penetration in a manufacturing plant, but for the small-diameter pipes on the heating surface of the in-service boiler, because the pipe rows are dense, the space between the pipes is small, the detection space is limited, eddy current detection, magnetic powder or penetration detection are inconvenient to implement, a detection blind area exists, and the defects are easy to miss detection.

At present, aiming at the longitudinal linear defect of the small-diameter pipe, the commonly adopted method is ultrasonic detection: the wafer in the ultrasonic probe is excited by an ultrasonic detector to generate ultrasonic longitudinal waves, the longitudinal waves are subjected to wave mode conversion on a detection interface through an acoustic-transparent wedge block, the ultrasonic longitudinal waves are converted into transverse waves, surface waves, creeping waves and the like to enter the small-diameter tube, the small-diameter tube is circumferentially scanned by moving the probe, and the detection of longitudinal linear defects is completed. Because the surface curvature of the small-diameter tube is larger, the coupling contact of the plane sound-transmitting wedge of the common probe on the outer surface of the small-diameter tube is theoretically a line, the coupling condition is not good enough, most of sound beams emitted by a wafer cannot enter a workpiece, the position randomness of a probe contact line is larger, the probe contact line changes along with the change of detection time and detection parts, and the human influence factor is larger, so that a method is necessary to be invented, the sound-transmitting wedge during the circumferential ultrasonic detection of the small-diameter tube is designed, the coupling condition is improved, the line contact during the detection is changed into surface contact, and the detection stability and the defect positioning accuracy are improved.

Disclosure of Invention

The invention aims to provide a method for designing a curved surface acoustic wedge for circumferential ultrasonic detection of a small-diameter pipe, which can effectively avoid the problems of poor coupling, difficulty in fixing a detection position and large human error when a small-diameter pipe is detected by using a planar acoustic wedge, improve the coupling condition, change the linear contact during detection into surface contact, and improve the stability of detection and the accuracy of defect positioning.

In order to achieve the purpose, the method for designing the curved surface sound-transmitting wedge for the circumferential ultrasonic detection of the small-diameter pipe 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) and 6) calculating the offset of the ultrasonic incident point of the curved surface sound-transmitting wedge relative to 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 for the circumferential ultrasonic detection of the small-diameter pipe.

The parameters of the ultrasonic probe body corresponding to the curved surface sound transmission wedge comprise the side length of a square wafer in the ultrasonic probe body and the incident angle of the ultrasonic probe body;

the combination mode of the curved surface sound-transmitting wedge and the corresponding ultrasonic probe body is detachable or embedded integrally.

The curved surface sound-transmitting wedge is made of machine glass or high polymer materials.

The curvature radius of the curved surface sound-transmitting wedge is equal to the curvature radius of the outer surface of the small-diameter pipe to be detected.

The vertex of the curved surface acoustic transmission wedge curved surface is positioned on the central line of an incident sound beam of the square wafer in the ultrasonic probe body, the vertex of the curved surface is an incident point of the ultrasonic probe body, and the included angle between the perpendicular 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.

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, wherein the critical radius r of the curved surface sound-transmitting wedge_FaceComprises the following steps:

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

when the curvature radius r of the curved surface sound-transmitting wedge is more than or equal to r_FaceAnd if not, the ultrasonic sound beam generated by the square wafer in the ultrasonic probe body can not be completely covered.

The offset of the curved surface sound-transmitting wedge 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, 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, the following steps are provided:

δ＝d·tan(α) (5)

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

The invention has the following beneficial effects:

the design method of the curved surface acoustic wedge for the circumferential ultrasonic detection of the small-diameter pipe comprises the steps of judging whether an ultrasonic sound beam generated by a square wafer in an ultrasonic probe body can be completely covered by the curved surface of the curved surface acoustic wedge or not, calculating the offset of the curved surface acoustic wedge relative to an ultrasonic incident point of a plane acoustic wedge, accurately tracing the transmission path of the ultrasonic wave during detection, improving the accuracy of defect positioning, replacing the traditional plane acoustic wedge with the curved surface acoustic wedge, avoiding the problems of poor coupling, difficulty in fixing the detection position and large artificial error existing in the process of detecting the small-diameter pipe by using the plane acoustic wedge, improving the coupling condition, changing the line contact during detection into the surface contact, and further improving the accuracy of detection.

Drawings

FIG. 1 is a flow chart of the present invention;

fig. 2 is a schematic view of a detachable sound-transmitting wedge and an ultrasonic probe body 1 in combination;

fig. 3 is a schematic view of a combination mode of the integrated embedded type sound-transmitting wedge and the ultrasonic probe body 1;

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

fig. 5 is a schematic diagram of the deviation of the ultrasonic wave incidence point of the curved surface acoustic-transparent wedge 2 relative to the plane acoustic-transparent wedge.

Wherein, 1 is the ultrasonic probe body, 2 is curved surface sound-transmitting wedge, 3 is fastening screw, 4 is square wafer, 5 is the small diameter pipe of examining.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

referring to fig. 1, the method for designing the curved surface acoustic wedge for circumferential ultrasonic detection of the small-diameter pipe, provided by the invention, comprises the following steps:

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

the parameters of the ultrasonic probe body 1 corresponding to the curved surface sound-transmitting 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;

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

the combination mode of the curved surface acoustic transmission wedge 2 and the corresponding ultrasonic probe body 1 is detachable or integrally embedded, wherein the curved surface acoustic transmission wedge 2 and the ultrasonic probe body 1 are connected through a fastening screw 3 in the detachable combination mode, a coupling agent is coated on the contact area of the curved surface acoustic transmission wedge 2 and the ultrasonic probe body 1, and the small-diameter pipe circumferential detection probe is integrally formed, referring to fig. 2; in an integrated embedded combination mode, the curved surface acoustic transmission wedge 2 and the ultrasonic probe body 1 are integrally packaged in the probe protection shell, and are not detachable, as shown in fig. 3.

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

the curved surface sound-transmitting wedge 2 is made of machine glass or high polymer materials, the propagation speed of the ultrasonic longitudinal wave in the organic glass is about 2700m/s, and the propagation speed of the ultrasonic longitudinal wave in the high polymer materials is about 1400 m/s.

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

the curvature radius of the curved surface sound-transmitting wedge 2 is equal to the curvature radius of the outer surface of the small-diameter pipe 5 to be detected.

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

the vertex of the curved surface acoustic-transparent wedge 2 is positioned on the central line of the incident sound beam of the square wafer 4 in the ultrasonic probe body 1, the vertex of the curved surface is the incident point of the ultrasonic probe body 1, and refer to a point A in fig. 4 and a point A in fig. 5₂The angle between the perpendicular line passing through the vertex of the curved surface and the center line of the incident sound beam is the incident angle of the ultrasonic probe body 1, which is referred to as the incident angle α shown in fig. 4 and 5.

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;

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 sound-transmitting wedge as far as possible, and if the ultrasonic sound beam cannot be completely covered due to the small radius of the curved surface of the sound-transmitting wedge, the coverage area should be maximized as far as possible. Referring to fig. 4, the ultrasonic sound beam is not completely covered by the curved surface of the curved surface sound-transmitting wedge 2; referring to fig. 5, the ultrasonic beam is completely covered by the curved surface of the curved surface 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 surface sound-transmitting wedge 2, wherein the critical radius r of the curved surface sound-transmitting wedge 2_FaceComprises the following steps:

where 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 curvature radius r of the curved surface sound-transmitting wedge 2 is more than or equal to r_FaceWhen 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.

For example: when the side length a of the wafer is 6mm and the incident angle α of the sound beam of the ultrasonic probe body 1 is 64 °, r can be calculated_FaceWhen the radius of the curved surface is 29.64mm or more, that is, the radius of the curved surface is 29.64mm or more, the parallel sound beam can be completely covered by the curved surface of the curved surface sound-transmitting wedge 2, that is, the small diameter tube to be tested, under the designed wafer and the designed incident angle.

7) And 6), 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 incident point offset includes a horizontal direction offset δ and a depth direction offset d, and referring to fig. 5, when the sound-transmitting wedge is a plane, the incident point of the ultrasonic wave emitted from the square wafer 4 is a₁(ii) a When the sound-transmitting wedge is a curved surface with radius r, the incident point of the ultrasonic wave emitted by the square wafer 4 is deviated to the point A₂Point A₁And point A₂The projection length of the connecting line at the horizontal position of the bottom surface of the curved surface sound-transmitting wedge 2 isThe offset delta of the incident point in the horizontal direction is the offset d of the incident point in the depth direction along the radial projection length of the sound-transmitting wedge curved surface, and the calculation can be carried out according to the following formula, specifically, according to whether the ultrasonic sound beam generated by the square wafer 4 in the ultrasonic probe body 1 can be completely covered by the sound-transmitting wedge curved surface:

when the ultrasonic sound beam can be completely covered by the sound-transmitting wedge curved surface, the following steps are provided:

d＝δ·cot(α) (3)

when the ultrasonic sound beam can not be completely covered by the sound-transmitting wedge curved surface, 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, α is the incident angle of the sound beam of the ultrasonic probe body 1, and r is the curvature radius of the curved surface acoustic transmission wedge 2.

For example: selecting heated surface small-diameter tubes of 3 typical specifications of phi 45mm, phi 51mm and phi 63.5mm, the curvature radii r of the corresponding acoustic wedges are 22.5mm, 25.5mm and 31.75mm respectively, the side length a of the square wafer 4 in the ultrasonic probe body 1 is 6mm, and when the incident angle alpha of the ultrasonic probe body 1 is 60 degrees, 62 degrees and 64 degrees respectively, the calculation results of the horizontal direction offset delta of the incident point, the depth direction offset d and whether the ultrasonic sound beam can be completely covered by the curved surface of the acoustic wedge are shown in table 1.

TABLE 1