Phased array probe for nondestructive testing of hollow axle

Abstract

The invention discloses a phased array probe for nondestructive testing of a hollow axle, and relates to the technical field of nondestructive testing. Comprising a cylindrical probe frame, a composite array element group arranged on the cylindrical probe frame, and a first annular conical surface reflection structure and a second annular conical surface reflection structure which are coaxial with the cylindrical probe frame and are located at two axial end sides, and reflection surfaces of the first annular conical surface reflection structure and the second annular conical surface reflection structure are oppositely arranged; the first array element is used for emitting ultrasonic longitudinal waves vertically incident to the inner wall of the hollow axle; the second array element and the third array element are respectively arranged on two end surfaces of the cylindrical probe frame and are used for transmitting ultrasonic longitudinal waves facing the adjacent annular conical surface reflection structure along the axial direction; the annular conical surface reflection structure totally reflects the ultrasonic longitudinal waves, and the ultrasonic longitudinal waves are converted into ultrasonic transverse waves on the hollow axle interface and refracted into the interior. According to the scheme, through the three-array-element composite layout and the annular conical surface reflection structure, the defects of the inner wall and the inner deep layer of the hollow axle can be synchronously, efficiently and accurately detected.

Description

Technical Field

[0001] This application relates to the field of nondestructive testing technology, and in particular to a phased array probe for nondestructive testing of hollow axles. Background Technology

[0002] Hollow axles, as core load-bearing components of high-speed rail transit vehicles, are prone to defects such as internal wall cracks and fatigue damage due to long-term exposure to alternating loads. Non-destructive testing of these axles is an important guarantee for driving safety, and the mainstream testing method at present is ultrasonic testing technology.

[0003] Current ultrasonic testing methods for hollow axles mostly employ single-element angled probes with mechanical rotation mechanisms for circumferential scanning, or use ordinary linear phased array probes for fixed-angle testing. The mechanical rotation scanning method requires a motor to drive the probe rotation, resulting in low testing efficiency. Existing technologies require a long testing time for a single hollow axle, and the rotation mechanism is prone to wear after prolonged use, leading to a decrease in scanning accuracy. Ordinary linear phased array probes, due to their simple element layout and limited beam coverage, cannot simultaneously meet the needs of 360° circumferential coverage of the hollow axle's inner wall and targeted testing of defects at different depths (such as surface cracks, internal inclusions, and fatigue damage). Therefore, how to achieve efficient and accurate simultaneous detection of the hollow axle's inner wall and deep internal defects, while simplifying the testing mechanism to avoid accuracy loss due to mechanical wear, has become a pressing technical problem to be solved. Summary of the Invention

[0004] This application provides a phased array probe for non-destructive testing of hollow axles. Through a three-element composite layout and an annular conical reflective structure, it can simultaneously, efficiently and accurately detect deep defects on the inner wall of hollow axles without mechanical rotation.

[0005] In a first aspect, embodiments of this application provide a phased array probe for non-destructive testing of hollow axles, comprising: a cylindrical probe frame, a composite array element group disposed on the cylindrical probe frame, and a first annular conical surface reflection structure and a second annular conical surface reflection structure coaxial with the cylindrical probe frame and located at both axial ends of the cylindrical probe frame with their reflecting surfaces facing each other; the composite array element group includes a first array element, a second array element, and a third array element; the first array element is used to emit ultrasonic longitudinal waves perpendicularly incident on the inner wall of the hollow axle; the first array element includes a phased array element disposed on the cylindrical probe frame. The probe holder has a first piezoelectric crystal group on its circumferential side, comprising multiple elongated piezoelectric crystals with gaps between adjacent elongated first piezoelectric crystals. A second and third array element are respectively disposed on two end faces of the cylindrical probe holder, with the second array element closer to the first annular conical reflective structure and the third array element closer to the second annular conical reflective structure. The second array element's second piezoelectric crystal group is used to emit ultrasonic longitudinal waves along the axial direction of the cylindrical probe holder towards the first annular conical reflective structure; the third array element's third piezoelectric crystal group is used to emit ultrasonic longitudinal waves along the axial direction of the cylindrical probe holder towards the first annular conical reflective structure. The cylindrical probe holder's axis faces the ultrasonic longitudinal wave of the second annular conical reflective structure; the second array element includes a second piezoelectric crystal group arranged in a ring, and the third array element includes a third piezoelectric crystal group arranged in a ring; both the second and third piezoelectric crystal groups consist of multiple elongated fan-shaped annular piezoelectric crystals spaced apart along the circumferential direction of their corresponding end faces, and the multiple elongated fan-shaped annular piezoelectric crystals are arranged to form an annular profile, with gaps between adjacent fan-shaped annular piezoelectric crystals; the first and second annular conical reflective structures are respectively used for total reflection. The ultrasonic longitudinal waves emitted by the second and third piezoelectric crystal groups are totally reflected and incident on the hollow axle interface at an angle θ1 greater than the first critical angle β1 and less than the second critical angle β2. At the hollow axle interface, they are converted into ultrasonic transverse waves and obliquely refracted at an angle θ2 into the interior of the hollow axle. θ2>θ1, sinβ1=v1 / v2, sinβ2=v1 / v3; v1 is the sound velocity of the longitudinal wave on the phased array probe side, v2 is the sound velocity of the longitudinal wave in the hollow axle, and v3 is the sound velocity of the transverse wave in the hollow axle.

[0006] This solution achieves a multi-dimensional breakthrough in hollow axle detection through the synergistic design of a three-element composite layout and a ring-shaped conical reflective structure: the first element on the circumferential side can directly emit vertical longitudinal waves to cover the entire 360° circumference of the inner wall, avoiding the decrease in accuracy caused by wear of the rotating mechanism without mechanical rotation; the second and third elements at both ends of the axis, after being reflected by the ring-shaped conical surface, can accurately convert the longitudinal waves into transverse waves that meet the critical angle requirements, realizing the detection of deep internal defects; the synchronous operation of the three elements not only solves the problem of low efficiency of traditional single-element probes, but also overcomes the defect of incomplete beam coverage of ordinary phased array probes, achieving one-stop accurate detection of inner wall and deep defects, significantly improving detection efficiency and accuracy.

[0007] In conjunction with the first aspect, in the first possible implementation of the first aspect, the elongated piezoelectric wafer in the first piezoelectric wafer group is a rectangular elongated shape with a planar or curved surface.

[0008] This solution adapts to different testing scenarios through flexible wafer shape design: curved rectangular strip wafers can closely fit the circumferential sides of the cylindrical probe holder, reducing energy loss during sound wave emission and improving the consistency of sound waves in inner wall testing; flat rectangular strip wafers reduce processing difficulty, facilitating mass production and assembly maintenance. The availability of two shapes enhances the probe's applicability, allowing for flexible selection based on the inner diameter specifications and testing accuracy requirements of the hollow axle, balancing testing effectiveness and production economy.

[0009] In conjunction with the first aspect, in a second possible implementation of the first aspect, the elongated fan-shaped piezoelectric wafers in the second and third piezoelectric wafer groups are planar elongated fan-shaped piezoelectric wafers.

[0010] The planar elongated fan-shaped ring-shaped wafer structure has two advantages: First, the planar shape facilitates the ring-shaped arrangement at equal intervals on the end face of the cylindrical probe holder, ensuring uniform energy distribution of the axially emitted ultrasonic longitudinal waves and avoiding the deviation of reflected sound waves caused by wafer tilting; second, the fan-shaped contour can maximize the use of end face space, realizing the arrangement of multiple wafers within a limited area, ensuring the sound beam coverage range, simplifying the assembly and positioning process of the wafers and probe holder, and improving production efficiency and structural stability.

[0011] In conjunction with the first aspect, in a third possible implementation of the first aspect, the phased array probe further includes: sealing rings located at both ends, and an oil injection hole and an oil outlet hole; the sealing rings are used to form a first sealed space with the first annular conical reflective structure, the second annular conical reflective structure, and the inner wall of the hollow axle when the phased array probe enters the hollow axle; the oil injection hole is used to inject coupling oil into the first sealed space; the oil outlet hole is used to discharge residual air in the first sealed space when coupling oil is injected through the oil injection hole, and after the first sealed space is filled with coupling oil, if coupling oil continues to be injected through the oil injection hole, excess coupling oil and residual air in the first sealed space can flow out from the oil outlet hole.

[0012] This solution constructs a reliable coupling and sealing system for shell-less scenarios: the first sealing space forms a closed area with the inner wall of the axle through the sealing ring, and the cooperation of the oil injection hole and the oil outlet hole realizes the complete process of "venting-injecting oil-draining excess oil", which effectively avoids the interference of residual air in the sealing space on the propagation of sound waves, and ensures that the coupling oil is fully filled and free of air bubbles; excess coupling oil can be discharged through the oil outlet hole to prevent excessive pressure in the sealing space from causing leakage of the sealing ring, improve the coupling stability of the probe during the moving detection process, and ensure the reliability of the detection results.

[0013] In conjunction with the first aspect, in the fourth possible implementation of the first aspect, the phased array probe further includes: a housing; the housing is fitted onto the outside of the cylindrical probe frame, the first annular conical reflective structure and the second annular conical reflective structure are located at both ends of the housing and are sealed to the inner wall of the housing to form a sealed cavity, the sealed cavity being filled with coupling oil.

[0014] The addition of the outer shell enables integrated protection of the core components of the probe: the sealed cavity formed by the outer shell and the annular conical reflective structure can be pre-filled with coupling oil to provide a stable medium for ultrasonic propagation and avoid damage caused by direct contact between the core array elements and the external environment; at the same time, the outer shell can buffer vibration and impact during the detection process, protect the positional accuracy of the piezoelectric crystal assembly and the reflective structure, and extend the service life of the probe; the design of the sealed cavity also simplifies the coupling preparation process for on-site detection and improves the convenience of detection.

[0015] In conjunction with the first aspect, the fifth possible implementation of the first aspect also includes a sealing ring; the sealing ring is sleeved on both ends of the outer shell, and when the phased array probe enters the hollow axle, the sealing ring forms a second sealing space with the outer peripheral surface of the outer shell and the inner wall of the hollow axle.

[0016] This solution constructs a dual-sealing protection mechanism: the second sealing space formed by the sealing ring on the outer periphery of the shell, together with the internal sealing cavity, forms a "double protection" that prevents external impurities from entering the shell and contaminating the core components. It also ensures that the coupling oil is replenished through the second sealing space when there is a slight leakage in the internal sealing cavity, so as to ensure that the detection process is not interrupted. The dual-sealing design significantly improves the probe's adaptability to complex detection environments, and is especially suitable for hollow axle detection under harsh conditions such as oil and dust.

[0017] In conjunction with the first aspect, the sixth possible implementation of the first aspect further includes an oil injection hole and an oil outlet hole; the oil injection hole is used to inject coupling oil into the second sealed space; the oil outlet hole is used to discharge residual air in the second sealed space when coupling oil is injected through the oil injection hole, and after the second sealed space is filled with coupling oil, if coupling oil continues to be injected through the oil injection hole, the excess coupling oil in the second sealed space and the residual air in the second sealed space can flow out from the oil outlet hole.

[0018] The solution optimizes the coupling oil filling logic for the second sealed space: the synergistic effect of the oil injection hole and the oil outlet hole ensures that the coupling oil in the second sealed space is filled without air bubbles, avoiding air from affecting the propagation of sound waves between the outer shell and the inner wall of the axle; the design for venting excess coupling oil and residual air prevents the sealing ring from deforming or failing due to excessive pressure in the second sealed space, further enhancing the reliability of the double seal and enabling the probe to maintain a stable coupling effect during long-term continuous detection.

[0019] In conjunction with the first aspect, in the seventh possible implementation of the first aspect, the cone angle α2 of the first annular conical reflective structure and the second annular conical reflective structure ranges from 35° to 50°, where α2 is the included angle between the conical surface and the axis of the cylindrical probe frame.

[0020] The cone angle range of 35° to 50° is precisely calculated acoustically: this angle range ensures that the axial ultrasonic longitudinal waves emitted by the second and third array elements, after reflection, are incident on the axle interface at an angle θ1 greater than the first critical angle β1 and less than the second critical angle β2, accurately realizing the conversion of longitudinal waves to transverse waves; if the cone angle is too large, the incident angle of the reflected sound wave will easily exceed the critical angle range, and an effective transverse wave cannot be formed; if the cone angle is too small, the transverse wave refraction angle θ2 will be insufficient, making it difficult to cover the deep area of ​​the axle; a reasonable cone angle range provides key acoustic assurance for deep defect detection.

[0021] In conjunction with the first aspect, in the eighth possible implementation of the first aspect, the value range of the refraction angle θ2 is 40°~50°.

[0022] A refraction angle of 40° to 50° is the optimal range for hollow axle inspection: when the transverse wave at this angle propagates inside the axle, it can avoid the near-surface blind zone and cover the core area in the axle wall thickness direction, providing good identification of defects of different depths, such as surface cracks, internal inclusions, and fatigue damage. If the refraction angle is too large, it will easily lead to excessively deep beam focusing, affecting the detection rate of shallow defects; if the refraction angle is too small, the coverage range will be limited, making it difficult to detect deep defects. This range of values ​​balances detection coverage and defect identification accuracy, improving the overall detection capability of the probe.

[0023] In conjunction with the first aspect, in the ninth possible implementation of the first aspect, the first piezoelectric wafer group includes 64 elongated piezoelectric wafers, which are uniformly arranged along the circumference of the cylindrical probe holder; the second piezoelectric wafer group includes 32 elongated fan-shaped annular piezoelectric wafers, which are arranged at equal central angle intervals along the circumferential direction of the corresponding end face of the cylindrical probe holder; the third piezoelectric wafer group includes 32 elongated fan-shaped annular piezoelectric wafers, which are arranged at equal central angle intervals along the circumferential direction of the corresponding end face of the cylindrical probe holder.

[0024] This solution achieves precise detection through optimized wafer quantity and arrangement: 64 elongated wafers are evenly arranged circumferentially to form a high-density sound beam coverage, which can identify tiny cracks in the inner wall; 32 fan-shaped wafers are arranged with equal central angles on their end faces to ensure that the axially emitted sound waves are uniform throughout the circumference, forming a transverse wave detection field without blind spots after reflection; the 64:32:32 quantity ratio ensures detection resolution while avoiding signal interference and increased costs caused by too many wafers, achieving a balance between detection performance and economy. Attached Figure Description

[0025] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1A is a schematic diagram of the core structure of a phased array probe used for non-destructive testing of hollow axles in one embodiment of this application; Figure 1B yes Figure 1A A schematic diagram of the sound wave propagation emitted by the second element in the array; Figure 1C yes Figure 1A A schematic diagram of the sound wave propagation emitted by the first element in the array; Figure 2 This is a schematic diagram of the core structure of a phased array probe with a housing for non-destructive testing of hollow axles in one embodiment of this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0028] It should be understood that the term "multiple" in this invention refers to two or more. In the description of this invention, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist, for example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, to facilitate a clear description of the technical solutions of this application, terms such as "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that terms such as "first" and "second" do not limit the quantity or execution order, and that "first" and "second" do not necessarily imply differences.

[0029] In existing ultrasonic testing technologies for hollow axles, the mainstream solutions fall into two categories: one is a single-element angled probe combined with a mechanical rotation mechanism to achieve circumferential scanning. This solution relies on a motor to drive the probe rotation, and it typically takes about 10 minutes to test a single hollow axle, which is inefficient. Furthermore, after long-term use, the rotation mechanism is prone to wear due to friction, leading to deviation in the scanning trajectory and directly affecting the testing accuracy. The other category is a common linear phased array probe, whose array elements are mostly arranged in a single direction, and the sound beam coverage can only focus on a single dimension (such as only covering the inner wall or only covering the shallow layer). It cannot simultaneously meet the requirements of 360° full circumferential testing of the hollow axle's inner wall and the detection of deep internal defects (such as fatigue damage in the middle of the wall thickness or internal inclusions), which easily leads to missed defects. The fundamental reason is that existing probes have not been designed with an appropriate array element layout and sound wave conversion mechanism for the structural characteristics of hollow axles, which are "cylindrical cavities + full dimensional coverage in the wall thickness direction".

[0030] To address the aforementioned deficiencies in existing technologies, this application provides a phased array probe for non-destructive testing of hollow axles. The core solution involves using a cylindrical probe frame as the base carrier, constructing a three-element composite layout with "side + end" elements (the first element is located on the circumferential side, and the second and third elements are located at the axial ends). At the axial ends of the probe frame, annular conical reflective structures (first and second annular conical reflective structures) are configured, coaxial with the axis and facing each other. The first element emits vertical longitudinal waves to detect the inner wall of the hollow axle, while the second and third elements emit axial longitudinal waves that are converted into transverse waves after total reflection by the annular conical surfaces to detect deep internal defects in the hollow axle. Full circumferential coverage is achieved without mechanical rotation, and a sealed coupling structure (which can be shellless, e.g.) is used. Figure 1A (as shown) or with a casing (such as) Figure 2 As shown in the figure), this solution ensures the stability of the detection process. It fundamentally solves the problems of "low efficiency, easy wear and tear, and incomplete coverage" of existing technologies, and realizes the synchronous, efficient and accurate detection of hollow axle inner wall and deep internal defects.

[0031] The following is in conjunction with the appendix Figure 1A , Figure 1B and Figure 1CThis application describes one embodiment of a phased array probe for non-destructive testing of a hollow axle 100. The phased array probe for non-destructive testing of the hollow axle uses a cylindrical probe holder 109 as its base carrier. The cylindrical probe holder 109 is equipped with a composite array element group. Specifically, a three-element composite layout of "side + ends" is constructed on the cylindrical probe holder 109 (the first element 107 is located on the circumferential side of the cylindrical probe holder, and the second / third elements 106 are respectively located at the two ends of the cylindrical probe holder 109). Furthermore, a coaxial, facing-opposing first annular conical reflective structure 104 and a second annular conical reflective structure 108 are configured at both axial ends of the cylindrical probe holder. Figure 1C As shown in the middle region S2, the first array element 107 is used to emit ultrasonic longitudinal waves that are vertically incident on the inner wall of the hollow axle 100; the first array element includes a first piezoelectric crystal group disposed on the circumferential side of the cylindrical probe holder, the first piezoelectric crystal group includes a plurality of elongated piezoelectric crystals 1071, and gaps are provided between adjacent elongated first piezoelectric crystals; it should be noted that the gaps between adjacent elongated first piezoelectric crystals mean that the adjacent elongated first piezoelectric crystals are not seamlessly connected, and there are gaps between them. The second and third array elements 106 are respectively disposed on the two end faces of the cylindrical probe holder 109, with the second array element close to the first annular conical reflective structure 104 and the third array element close to the second annular conical reflective structure 108. The second array element includes a second piezoelectric crystal group, and the third array element includes a third piezoelectric crystal group. The second piezoelectric crystal group of the second array element is used to emit ultrasonic longitudinal waves along the axial direction of the cylindrical probe holder 109 toward the first annular conical reflective structure 104; the third piezoelectric crystal group of the third array element is used to emit ultrasonic longitudinal waves along the axial direction of the cylindrical probe holder 109 toward the second annular conical reflective structure 108. The structure 108 is an ultrasonic longitudinal wave; the second array element includes a second piezoelectric crystal group arranged in a ring, and the third array element includes a third piezoelectric crystal group arranged in a ring; both the second and third piezoelectric crystal groups are composed of multiple elongated fan-shaped piezoelectric crystals 1061 arranged at intervals along the circumferential direction of their corresponding end faces, and the multiple elongated fan-shaped piezoelectric crystals are arranged to form a ring outline, with gaps between adjacent fan-shaped piezoelectric crystals; it should be noted that the gaps between adjacent fan-shaped piezoelectric crystals mean that the adjacent fan-shaped piezoelectric crystals are not seamlessly connected, and there are gaps between them.

[0032] The first annular conical reflective structure 104 and the second annular conical reflective structure 108 are used for total reflection of the ultrasonic longitudinal waves emitted by the second and third piezoelectric wafer groups, respectively. Figure 1BAs shown in region S1, the angle of the incident longitudinal wave is α1. The cone angle α2 of the first annular conical reflector 104 and the second annular conical reflector 108 ranges from 35° to 50°, where α2 is the angle between the conical surface and the axis of the cylindrical probe frame. After total reflection, the ultrasonic longitudinal wave is incident at the hollow axle interface at an angle θ1 greater than the first critical angle β1 and less than the second critical angle β2. At the hollow axle interface, it is converted into an ultrasonic transverse wave and obliquely refracted at an angle θ2 into the interior of the hollow axle; θ2>θ1, sinβ1=v1 / v2, sinβ2=v1 / v3; v1 is the sound velocity of the longitudinal wave on the phased array probe side, v2 is the sound velocity of the longitudinal wave in the hollow axle, and v3 is the sound velocity of the transverse wave in the hollow axle. The refraction angle θ2 ranges from 40° to 50°. In some possible implementations, the first piezoelectric wafer group includes 64 elongated piezoelectric wafers, which are uniformly arranged along the circumference of the cylindrical probe holder 109; the second piezoelectric wafer group includes 32 elongated fan-shaped piezoelectric wafers, which are arranged at equal central angle intervals along the circumferential direction of the corresponding end face of the cylindrical probe holder; the third piezoelectric wafer group includes 32 elongated fan-shaped piezoelectric wafers, which are arranged at equal central angle intervals along the circumferential direction of the corresponding end face of the cylindrical probe holder.

[0033] During the inspection, the 64 elongated piezoelectric crystals of the first array element 107 emit ultrasonic longitudinal waves. The ultrasonic longitudinal waves are incident vertically on the inner wall and near-surface area of ​​the hollow axle 100. The reflected signals are received by the piezoelectric crystals and transmitted to the acquisition card, realizing 360° full-circumference defect detection of the inner wall.

[0034] The second element emits an axial longitudinal ultrasonic wave, which is directed toward the first annular conical reflective structure 104 and is totally reflected, forming a reflected longitudinal ultrasonic wave. This longitudinal ultrasonic wave is incident on the inner surface of the hollow axle at an angle θ1 satisfying β1<θ1<β2, and is converted into a transverse ultrasonic wave at the inner surface of the incident hollow axle. The refraction angle θ2 of the transverse ultrasonic wave satisfies 40°~50° and θ2>θ1.

[0035] Similarly, the ultrasonic longitudinal wave emitted by the third element is also converted into an ultrasonic transverse wave after total reflection by the second annular conical reflector structure 108.

[0036] The ultrasonic transverse wave propagates deep into the hollow axle 100. When it encounters an internal defect, it is reflected. The reflected signal returns to the second or third array element through the original path and is then transmitted to the acquisition card for analysis, thus realizing the detection of deep defects.

[0037] In some possible implementations, the elongated piezoelectric wafers in the first piezoelectric wafer group are rectangular strips with planar or curved surfaces.

[0038] In some possible implementations, the elongated fan-shaped piezoelectric wafers in the second and third piezoelectric wafer groups are planar elongated fan-shaped piezoelectric wafers.

[0039] In some possible implementations, the first annular conical reflective structure 104 is connected to one end of the cylindrical probe 109, which has a second array element, via a connecting structure 105.

[0040] like Figure 1A As shown, during testing, the phased array probe can be fixed to the external traction mechanism through the connector 102. Activating the traction mechanism can pull the phased array probe into the hollow shaft 100 and move the phased array probe within the hollow shaft 100.

[0041] The external acquisition card connects to the phased array probe via connector 101, such as... Figure 1A As shown, sealing rings 103 are provided at both ends of the phased array probe. An oil injection hole A′ and an oil outlet hole A are also provided at one end.

[0042] The sealing ring 103 is used to form a first sealed space with the first annular conical reflective structure 104, the second annular conical reflective structure 108, and the inner wall of the hollow axle 100 when the phased array probe enters the hollow axle. The oil injection hole A′ and the oil outlet hole A communicate with the first sealed space; for example, small holes can be provided on the first annular conical reflective structure 104. The oil injection hole A′ is used to inject coupling oil into the first sealed space; the oil outlet hole A′ is used to expel residual air in the first sealed space when coupling oil is injected through the oil injection hole A′, and after the first sealed space is filled with coupling oil, if coupling oil continues to be injected through the oil injection hole, excess coupling oil and residual air in the first sealed space can flow out through the oil outlet hole. This prevents excessive pressure in the first sealed space from causing leakage of the sealing ring 103 and ensures the coupling stability of sound wave propagation.

[0043] It should be noted that when the testing environment is clean (free of dust and oil), the following method should be used. Figure 1A The shell-less design shown is suitable for use in harsh testing environments (dust, oil, etc.). Figure 2 The design with an outer shell is shown. For example, in some possible implementations, the outer shell can be made of 304 stainless steel with a wall thickness controlled within 2mm. At the same time, the sealed cavity between the inner side of the outer shell and the cylindrical probe holder 210 is filled with coupling oil that matches the longitudinal wave velocity v1 on the probe side. The acoustic impedance of the outer shell 208 forms a continuous transition with the acoustic impedance of the coupling oil and the hollow axle 200. The energy loss of the sound wave penetrating the outer shell 208 after reflection by the annular conical reflector structure is less than 3%, and the interference on the propagation path, angle and phase of the total reflection wave is within the allowable range of ultrasonic detection error. That is, the influence of the outer shell on the total reflection wave is negligible and does not affect the final detection accuracy.

[0044] like Figure 2 As shown, in another embodiment, the phased array probe further includes: a housing 208; the housing 208 is sleeved on the outside of the cylindrical probe frame 210, the first annular conical reflective structure 204 and the second annular conical reflective structure 209 are respectively located at both ends of the housing and are sealed to the inner wall of the housing to form a sealed cavity, which is filled with coupling oil.

[0045] The phased array probe also includes a sealing ring 203; the sealing ring 203 is sleeved on both ends of the housing. When the phased array probe is fixed to the external traction mechanism through the connector 202 and is pulled into the hollow axle 200, the sealing ring 203, the outer peripheral surface of the housing 208, and the inner wall of the hollow axle form a second sealing space.

[0046] In some possible implementations, an oil injection port and an oil outlet port are also included. The oil injection port is used to inject coupling oil into the second sealed space; the oil outlet port is used to expel residual air in the second sealed space when coupling oil is injected through the oil injection port, and after the second sealed space is filled with coupling oil, if coupling oil continues to be injected through the oil injection port, excess coupling oil and residual air in the second sealed space can flow out through the oil outlet port. The oil injection port and oil outlet port can be located at one end of the phased array probe, for example, they can be set to... Figure 2 The left end of the phased array probe (not shown in the figure) is provided with an outlet that communicates with the oil injection hole and the oil outlet hole.

[0047] and Figure 1B The structure is similar in the middle. Figure 2The phased array probe 210 frame is equipped with a composite array element group. Specifically, a three-element composite layout of "side + ends" is constructed on the cylindrical probe frame 209 (the first array element 207 is located on the circumferential side of the cylindrical probe frame, and the second / third array elements 206 are located at the ends of the cylindrical probe frame 210 respectively). A coaxial, facing first annular conical reflective structure 204 and a second annular conical reflective structure 209 are configured at both ends of the cylindrical probe frame. The first array element 207 is used to emit ultrasonic longitudinal waves that are perpendicularly incident on the inner wall of the hollow axle 200. The first array element includes a first piezoelectric crystal group located on the circumferential side of the cylindrical probe frame. The first piezoelectric crystal group includes multiple elongated piezoelectric crystals 2071, with gaps between adjacent elongated first piezoelectric crystals. It should be noted that the gaps between adjacent elongated first piezoelectric crystals mean that the adjacent elongated first piezoelectric crystals are not seamlessly connected; there are gaps between them. The second and third array elements 206 are respectively disposed on the two end faces of the cylindrical probe holder 210, with the second array element close to the first annular conical reflective structure 204 and the third array element close to the second annular conical reflective structure 209. The second piezoelectric crystal group is used to emit ultrasonic longitudinal waves along the axial direction of the cylindrical probe holder 210 toward the first annular conical reflective structure 204; the third piezoelectric crystal group is used to emit ultrasonic longitudinal waves along the axial direction of the cylindrical probe holder 210 toward the second annular conical reflective structure 209. The second array element includes a second piezoelectric crystal group arranged in a ring, and the third array element includes a third piezoelectric crystal group arranged in a ring. Both the second and third piezoelectric crystal groups are composed of multiple elongated fan-shaped annular piezoelectric crystals 2061 arranged at intervals along the circumferential direction of the corresponding end faces, and the multiple elongated fan-shaped annular piezoelectric crystals are arranged to form an annular outline, with gaps between adjacent fan-shaped annular piezoelectric crystals. It should be noted that the gaps between adjacent fan-shaped annular piezoelectric crystals mean that the adjacent fan-shaped annular piezoelectric crystals are not seamlessly connected, and there are gaps between them.

[0048] See Figure 1BThe first annular conical reflector structure 204 and the second annular conical reflector structure 209 are used for total reflection of the ultrasonic longitudinal waves emitted by the second and third piezoelectric crystal groups, respectively. The incident longitudinal wave has an angle of α1. The cone angle α2 of the first annular conical reflector structure 204 and the second annular conical reflector structure 209 ranges from 35° to 50°, where α2 is the angle between the conical surface and the axis of the cylindrical probe frame. The total reflected ultrasonic longitudinal wave is incident on the hollow axle interface at an angle θ1 greater than the first critical angle β1 and less than the second critical angle β2. It is converted into an ultrasonic transverse wave at the hollow axle interface and obliquely refracted at an angle θ2 into the interior of the hollow axle. θ2>θ1, sinβ1=v1 / v2, sinβ2=v1 / v3; v1 is the sound velocity of the longitudinal wave on the phased array probe side, v2 is the sound velocity of the longitudinal wave in the hollow axle, and v3 is the sound velocity of the transverse wave in the hollow axle. The range of the refraction angle θ2 is 40°~50°. In some possible implementations, the first piezoelectric wafer group includes 64 elongated piezoelectric wafers, which are uniformly arranged along the circumference of the cylindrical probe holder 109; the second piezoelectric wafer group includes 32 elongated fan-shaped piezoelectric wafers, which are arranged at equal central angle intervals along the circumferential direction of the corresponding end face of the cylindrical probe holder; the third piezoelectric wafer group includes 32 elongated fan-shaped piezoelectric wafers, which are arranged at equal central angle intervals along the circumferential direction of the corresponding end face of the cylindrical probe holder.

[0049] In some possible implementations, the elongated piezoelectric wafers in the first piezoelectric wafer group are rectangular strips with planar or curved surfaces.

[0050] In some possible implementations, the elongated fan-shaped piezoelectric wafers in the second and third piezoelectric wafer groups are planar elongated fan-shaped piezoelectric wafers.

[0051] This embodiment achieves a multi-dimensional breakthrough in hollow axle detection through the synergistic design of a three-element composite layout and a ring-shaped conical reflective structure: the first element on the circumferential side can directly emit vertical longitudinal waves to cover the entire 360° circumference of the inner wall, avoiding the decrease in accuracy caused by wear of the rotating mechanism without mechanical rotation; the second and third elements at both ends of the axis, after being reflected by the ring-shaped conical surface, can accurately convert the longitudinal waves into transverse waves that meet the critical angle requirements, realizing the detection of deep internal defects; the synchronous operation of the three elements not only solves the problem of low efficiency of traditional single-element probes, but also overcomes the defect of incomplete beam coverage of ordinary phased array probes, achieving one-stop accurate detection of inner wall and deep defects, significantly improving detection efficiency and accuracy.

[0052] The above-described embodiments are optional embodiments provided by this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the technical scope disclosed in this application should be included within the protection scope of this application.

Claims

1. A phased array probe for non-destructive testing of hollow axles, characterized in that, include: A cylindrical probe frame, a composite array element set on the cylindrical probe frame, and a first annular conical surface reflection structure and a second annular conical surface reflection structure that are coaxial with the cylindrical probe frame and located at both ends of the cylindrical probe frame with their reflecting surfaces facing each other; The composite array element group includes a first array element, a second array element, and a third array element; The first array element is used to emit ultrasonic longitudinal waves that are vertically incident on the inner wall of the hollow axle; the first array element includes a first piezoelectric crystal group disposed on the circumferential side of the cylindrical probe holder, the first piezoelectric crystal group includes a plurality of elongated piezoelectric crystals, and a gap is provided between adjacent elongated first piezoelectric crystals; The second array element and the third array element are respectively disposed on the two end faces of the cylindrical probe frame, with the second array element close to the first annular conical reflective structure and the third array element close to the second annular conical reflective structure; the second piezoelectric crystal group of the second array element is used to emit ultrasonic longitudinal waves along the axial direction of the cylindrical probe frame toward the first annular conical reflective structure; the third piezoelectric crystal group of the third array element is used to emit ultrasonic longitudinal waves along the axial direction of the cylindrical probe frame toward the second annular conical reflective structure; the second array element includes a second piezoelectric crystal group arranged in a ring, and the third array element includes a third piezoelectric crystal group arranged in a ring; both the second and third piezoelectric crystal groups are composed of multiple elongated fan-shaped annular piezoelectric crystals spaced apart along the circumferential direction of the corresponding end faces, and the multiple elongated fan-shaped annular piezoelectric crystals are arranged to form an annular profile, with gaps provided between adjacent fan-shaped annular piezoelectric crystals; The first and second annular conical reflective structures are used to totally reflect the ultrasonic longitudinal waves emitted by the second and third piezoelectric wafer groups, respectively. The totally reflected ultrasonic longitudinal waves are incident on the hollow axle interface at an angle θ1 greater than the first critical angle β1 and less than the second critical angle β2. They are converted into ultrasonic transverse waves at the hollow axle interface and obliquely refracted at an angle θ2 into the interior of the hollow axle. θ2>θ1, sinβ1=v1 / v2, sinβ2=v1 / v3. v1 is the sound velocity of the longitudinal wave on the phased array probe side, v2 is the sound velocity of the longitudinal wave in the hollow axle, and v3 is the sound velocity of the transverse wave in the hollow axle.

2. The phased array probe for non-destructive testing of hollow axles according to claim 1, characterized in that, The elongated piezoelectric wafers in the first piezoelectric wafer group are rectangular strips with planar or curved surfaces.

3. The phased array probe for non-destructive testing of hollow axles according to claim 1, characterized in that, The elongated fan-shaped piezoelectric wafers in the second and third piezoelectric wafer groups are planar elongated fan-shaped piezoelectric wafers.

4. The phased array probe for non-destructive testing of hollow axles according to claim 1, characterized in that, The phased array probe also includes: sealing rings at both ends, as well as an oil injection hole and an oil outlet hole; The sealing ring is used to form a first sealing space with the first annular conical reflective structure, the second annular conical reflective structure, and the inner wall of the hollow axle when the phased array probe enters the hollow axle; The oil injection hole is used to inject coupling oil into the first sealed space; The oil outlet is used to discharge residual air in the first sealed space when coupling oil is injected through the oil injection hole, and after the first sealed space is filled with coupling oil, if the oil injection hole continues to inject coupling oil, the excess coupling oil and residual air in the first sealed space can flow out from the oil outlet.

5. The phased array probe for non-destructive testing of hollow axles according to claim 1, characterized in that, The phased array probe also includes: a housing; The outer shell is fitted onto the outside of the cylindrical probe frame. The first annular conical reflective structure and the second annular conical reflective structure are located at both ends of the outer shell and are sealed to the inner wall of the outer shell to form a sealed cavity. The sealed cavity is filled with coupling oil.

6. The phased array probe for non-destructive testing of hollow axles according to claim 5, characterized in that, It also includes a sealing ring; the sealing ring is sleeved on both ends of the housing, and when the phased array probe enters the hollow axle, the sealing ring, the outer peripheral surface of the housing, and the inner wall of the hollow axle form a second sealing space.

7. The phased array probe for non-destructive testing of hollow axles according to claim 6, characterized in that, It also includes an oil filling hole and an oil outlet hole; The oil injection hole is used to inject coupling oil into the second sealed space; The oil outlet is used to discharge residual air in the second sealed space when coupling oil is injected through the oil injection hole, and after the second sealed space is filled with coupling oil, if the oil injection hole continues to inject coupling oil, the excess coupling oil and residual air in the second sealed space can flow out from the oil outlet.

8. The phased array probe for non-destructive testing of hollow axles according to any one of claims 1 to 7, characterized in that, The cone angle α2 of the first and second annular conical reflective structures ranges from 35° to 50°, where α2 is the angle between the conical surface and the axis of the cylindrical probe frame.

9. The phased array probe for non-destructive testing of hollow axles according to claim 8, characterized in that, The refraction angle θ2 ranges from 40° to 50°.

10. The phased array probe for non-destructive testing of hollow axles according to claim 9, characterized in that, The first piezoelectric wafer group includes 64 elongated piezoelectric wafers, which are uniformly arranged along the circumference of the cylindrical probe frame; the second piezoelectric wafer group includes 32 elongated fan-shaped piezoelectric wafers, which are arranged at equal central angle intervals along the circumferential direction of the corresponding end face of the cylindrical probe frame; the third piezoelectric wafer group includes 32 elongated fan-shaped piezoelectric wafers, which are arranged at equal central angle intervals along the circumferential direction of the corresponding end face of the cylindrical probe frame.

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