Terahertz nondestructive testing device and method for nonmetal pipeline

Abstract

The invention provides a non-metallic pipeline terahertz nondestructive testing device and method, and belongs to the field of non-metallic pipeline defect detection.The nondestructive testing device comprises a terahertz probe, an axial scanning unit and an annular stepping unit; the terahertz probe is arranged on the axial scanning unit, and the incidence direction of the bottom of the terahertz probe is perpendicular to the surface of the to-be-detected pipe section; the axial scanning unit is arranged in the length direction of the to-be-detected pipe section and is configured to be capable of driving the terahertz probe to do constant-speed reciprocating motion in the length direction of the to-be-detected pipe section at a preset axial scanning speed; the annular stepping unit is connected with the axial scanning unit and is configured to drive the axial scanning unit to move by a preset annular length in the annular direction of the to-be-measured pipe section at a preset annular scanning speed. Through the detection device provided by the invention, terahertz three-dimensional nondestructive detection of the on-site non-metal pipeline can be realized, and a foundation is laid for defect detection, evaluation and life prediction of the non-metal pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of non-metallic pipeline defect detection, and in particular to a non-metallic pipeline terahertz non-destructive detection device and a non-metallic pipeline terahertz non-destructive detection method. Background Art

[0002] With the rapid development of economy and society, non-metallic pipelines are more and more widely used in oil and gas fields. In addition, environmental protection projects, water supply projects, urban gas projects, etc. are also increasingly using non-metallic pipelines, and the safety of non-metallic pipelines is also attracting more and more attention. Compared with other metal pressure-bearing equipment, non-metallic pipelines do not have systematic and mature non-destructive testing methods and standards, which makes non-metallic pipeline defect detection a difficult problem.

[0003] Terahertz radiation refers to electromagnetic waves with a frequency of 0.1 to 10 THz (1 THz = 1012 Hz), which has the characteristics of high perspective, low energy level, wide frequency band, rich carrying capacity, high signal-to-noise ratio, high resolution, etc. It has strong penetration into non-metallic materials and is used in the field of non-destructive testing of non-metallic materials, with broad application prospects. At present, there are endless terahertz non-destructive testing equipment products at home and abroad, but they are mainly concentrated in the fields of aerospace flat materials, biomedicine and security inspection. There is no special terahertz on-site non-destructive testing equipment for non-metallic pipelines. Summary of the invention

[0004] In view of the technical problem that there is a lack of dedicated terahertz on-site non-destructive testing equipment for non-metallic pipelines in the prior art, the present invention provides a terahertz non-destructive testing device and method for non-metallic pipelines. The detection device can realize terahertz three-dimensional non-destructive testing of on-site non-metallic pipelines, laying a foundation for defect detection, evaluation and life prediction of non-metallic pipelines.

[0005] To achieve the above-mentioned purpose, the present invention provides, on one hand, a terahertz nondestructive testing device for non-metallic pipelines, the nondestructive testing device comprising a terahertz probe, an axial scanning unit and a circumferential stepping unit; the terahertz probe is arranged on the axial scanning unit, and the incident direction of the bottom of the terahertz probe is perpendicular to the surface of the pipe section to be tested; the axial scanning unit is arranged along the length direction of the pipe section to be tested, and is configured to drive the terahertz probe to perform uniform reciprocating motion along the length direction of the pipe section to be tested at a predetermined axial scanning speed; the circumferential stepping unit is connected to the axial scanning unit, and is configured to drive the axial scanning unit to move a predetermined circumferential length along the circumferential direction of the pipe section to be tested at a predetermined circumferential scanning speed; wherein the pipe section to be tested is a non-metallic pipeline operated on site.

[0006] In an exemplary embodiment of the present invention, the axial scanning unit may include an axial stepping track, a probe fixture and a first scanning drive module; wherein the axial stepping track is arranged in parallel above the pipe section to be measured, and the length of the axial stepping track is greater than the axial length of the pipe section to be measured; the probe fixture is slidably connected to the axial stepping track, and is configured to be able to clamp and fix the terahertz probe, and adjust the clamping height and clamping angle of the terahertz probe; the first scanning drive module is connected to the probe fixture, and is configured to be able to control the probe fixture to perform uniform reciprocating motion on the axial stepping track at a predetermined axial scanning speed.

[0007] In an exemplary embodiment of the present invention, the circumferential stepping unit may include a circumferential transmission track and a second scanning drive module; the circumferential transmission track is sleeved on the surface of the pipe segment to be measured, and the circumference of the circumferential transmission track is less than or equal to the outer circumference of the pipe segment to be measured; the second scanning drive module is connected to the axial scanning unit and is configured to control the axial scanning unit to move a predetermined circumferential length along the circumferential direction of the pipe segment to be measured at a predetermined circumferential scanning speed.

[0008] In an exemplary embodiment of the present invention, the annular transmission track may be a telescopic structure.

[0009] In an exemplary embodiment of the present invention, the nondestructive testing device may further include a tool support, one end of the tool support is fixedly connected to the circumferential stepping unit, and the other end of the tool support is fixedly connected to the ground.

[0010] In an exemplary embodiment of the present invention, the nondestructive testing device may further include a rigidity enhancer, which is connected to the annular stepping unit and contacts the surface of the pipe section to be tested, and is configured

[0011] In order to enhance the axial deformation strength of the pipe section to be tested.

[0012] In an exemplary embodiment of the present invention, the rigidity enhancer is straight-line or T-shaped.

[0013] On the other hand, the present invention provides a terahertz nondestructive testing method for non-metallic pipelines. The nondestructive testing method is implemented by the above-mentioned nondestructive testing device, and includes the following steps: adjusting the clamping angle of the terahertz probe so that the incident direction of the terahertz signal is perpendicular to the surface of the pipe section to be tested; controlling the axial scanning unit to drive the terahertz probe to perform axial scanning along a first axial movement direction at a predetermined axial scanning speed; controlling the circumferential stepping unit to drive the axial scanning unit to move a predetermined circumferential length along the circumferential direction of the pipe section to be tested at a predetermined circumferential scanning speed; controlling the axial scanning unit to drive the terahertz probe to perform axial scanning along a second axial movement direction at a predetermined axial scanning speed, wherein the first axial movement direction is opposite to the second axial movement direction; repeating the above steps until the scanning path of the terahertz probe covers the defect distribution area of ​​the pipe section to be tested.

[0014] In another exemplary embodiment of the present invention, the nondestructive testing method may further include: adjusting the clamping height and the clamping angle of the terahertz probe according to the focal size of the terahertz probe so that the focus of the terahertz signal is located at the center of the wall thickness of the pipe section to be tested.

[0015] In another exemplary embodiment of the present invention, the nondestructive testing method may further include: determining a predetermined axial scanning speed based on an axial scanning resolution and a data acquisition frequency.

[0016] In another exemplary embodiment of the present invention, the nondestructive testing method may further include: determining a predetermined circumferential scanning speed based on the circumferential scanning resolution, the axial scanning length, and the axial scanning speed.

[0017] Through the technical solution provided by the present invention, the present invention has at least the following technical effects:

[0018] (1) In view of the circumferential shape of non-metallic pipes, the non-destructive testing device of the present invention is designed with axial scanning and circumferential stepping functions to achieve local surface scanning of non-metallic pipes;

[0019] (2) In view of the characteristics of non-metallic pipes with thin diameters and high flexibility, the non-destructive testing device of the present invention is designed with a pipe axial stiffness enhancement structure, which greatly reduces the deformation of the non-metallic pipe and ensures the stability of the tooling and data accuracy during the scanning process;

[0020] (3) In view of the requirement that the terahertz non-destructive testing signal is perpendicular to the surface of the structure, the non-destructive testing device of the present invention is designed with a probe clamping structure, which ensures that the terahertz signal is incident perpendicular to the surface of the structure and is kept at an optimal distance from the surface of the structure through an adjustable clamping structure;

[0021] (4) In view of the complexity and uncertainty of the on-site excavation environment, the non-destructive testing device of the present invention is designed with a tooling support structure to ensure the stability of the tooling during the scanning process, reduce tooling vibration, and avoid the influence of structural vibration on the detection process;

[0022] (5) The present invention can realize terahertz three-dimensional non-destructive testing of non-metallic pipelines on site, laying a foundation for defect detection, evaluation and life prediction of non-metallic pipelines.

[0023] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0025] Figure 1 A schematic diagram of the structure of a non-metallic pipeline terahertz non-destructive testing device provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the use process of the non-metallic pipeline terahertz non-destructive testing device provided by an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the scanning path of a terahertz probe provided in an embodiment of the present invention.

[0028] Description of Reference Numerals

[0029] 1-axial stepping track, 2-probe fixture, 3-terahertz probe, 4-circumferential drive, 5-circumferential transmission track, 6-pipe section to be tested, 7-rigidity enhancer, 8-tool support, 9-soil, 10-scanning path, 11-defect distribution area. DETAILED DESCRIPTION

[0030] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0032] In the present invention, unless otherwise specified, the directional words used, such as "upper, lower, top, bottom", are usually used to describe the relative positional relationship of the components in terms of the directions shown in the drawings or in terms of the vertical, perpendicular or gravity directions. "First", "second", etc. are only used for the convenience of description and distinction, and cannot be understood as indicating or implying relative importance.

[0033] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installation", "connection", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a direct connection, or an indirect connection; it can be a wired connection, or a wireless connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0034] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0035] Embodiment 1

[0036] The first embodiment of the present invention provides a terahertz nondestructive testing device for non-metallic pipelines, which includes a terahertz probe, an axial scanning unit, and a circumferential stepping unit. The terahertz probe is arranged on the axial scanning unit, and the incident direction of the bottom of the terahertz probe is perpendicular to the surface of the pipe section to be tested. Since the terahertz nondestructive testing technology belongs to non-contact indirect imaging, it can perform three-dimensional scanning and imaging of the structure, but requires the terahertz signal transmitter to be perpendicular to the surface of the structure during the scanning process. Therefore, the terahertz probe should be fixedly installed on the axial scanning unit at an angle that keeps the signal incident direction perpendicular to the defect distribution area of ​​the pipe section to be tested.

[0037] In order to ensure that the installation angle of the terahertz probe can be adjusted at any time, the terahertz probe can be movably connected to the axial scanning unit. For example, the terahertz probe can be connected to the axial scanning unit by a rotating shaft, a latch, a buckle, a hinge, etc. in a manner that allows relative rotation (or movement) to achieve adjustment of the installation angle of the terahertz probe.

[0038] The axial scanning unit is arranged along the length direction of the pipe section to be measured, and is used to drive the terahertz probe to perform uniform reciprocating motion along the length direction of the pipe section to be measured at a predetermined axial scanning speed.

[0039] The circumferential stepping unit is movably connected to the axial scanning unit, and is used to drive the axial scanning unit to move a predetermined circumferential length along the circumferential direction (ie, circumferential direction) of the pipe section to be measured at a predetermined circumferential scanning speed.

[0040] Further, in this embodiment, the axial scanning unit may include an axial stepping track, a probe fixture and a first scanning drive module. The axial stepping track is arranged in parallel above the pipe section to be measured, and the length of the axial stepping track is greater than the axial length of the pipe section to be measured. The probe fixture is slidably connected to the axial stepping track, and is used to clamp and fix the terahertz probe, and adjust the clamping height and clamping angle of the terahertz probe. The first scanning drive module is connected to the probe fixture, and is used to control the probe fixture to perform uniform reciprocating motion on the axial stepping track at a predetermined axial scanning speed.

[0041] Further, in this embodiment, the circumferential stepping unit may include a circumferential transmission track and a second scanning drive module. The circumferential transmission track is sleeved on the surface of the pipe section to be measured, and the circumference of the circumferential transmission track is less than or equal to the outer circumference of the pipe section to be measured. The second scanning drive module is connected to the axial scanning unit, and is used to control the axial scanning unit to move a predetermined circumferential length along the circumferential direction of the pipe section to be measured at a predetermined circumferential scanning speed.

[0042] For example, the annular transmission track can be a circular arc track mounted on the pipe section to be tested, and the arc length range of the annular transmission track can just cover the defect distribution area of ​​the pipe section to be tested. When the axial scanning unit moves from the starting point of the annular transmission track to the end point of the annular transmission track, the terahertz probe can just complete the non-destructive detection of the defect distribution area of ​​the pipe section to be tested. Of course, the present invention is not limited to this, and other external structures such as circular rings, square frames, etc. can also be applied to the annular transmission track of the present invention, as long as the annular transmission track can meet the requirements of driving the axial scanning unit to perform terahertz detection along the circumference of the pipe section to be tested.

[0043] In addition, the annular transmission track of the present embodiment can be configured as a telescopic structure so that the annular transmission track

[0044] The circumference of the channel can be adjusted according to the outer diameter of the pipe section to be measured.

[0045] Here, it should be noted that the pipe section to be tested in this embodiment refers to a part of non-metallic pipes with surface defects that are operated on-site in environmental protection projects, water supply projects, urban gas projects, etc.

[0046] In this embodiment, in view of the circular shape of the pipe section to be tested and the non-detachable and movable characteristics, an axial scanning unit and an annular stepping unit are designed to respectively realize the surface scanning of the defect distribution area of ​​the non-metallic pipeline. The non-destructive testing device can be used as a special terahertz non-destructive testing scanning tool for non-metallic pipelines in environmental protection projects, water supply projects, urban gas projects and other sites.

[0047] Embodiment 2

[0048] A second embodiment of the present invention provides a non-metallic pipeline terahertz nondestructive testing device, which includes a terahertz probe, an axial scanning unit, a circumferential stepping unit, and a rigidity enhancer.

[0049] The terahertz probe is fixedly mounted on the axial scanning unit, and the incident direction of the terahertz probe is perpendicular to the pipe section to be measured, so as to perform three-dimensional scanning and imaging of the pipe section to be measured.

[0050] The circumferential stepping unit is fixed around the surface of the pipe section to be measured, and is used to drive the terahertz probe to move along the circumference of the pipe section to be measured, and is also used to enhance the circumferential stiffness of the pipe section to be measured.

[0051] The axial scanning unit is arranged along the axial direction of the pipe section to be measured and is slidably connected with the annular stepping unit to drive the terahertz probe to move along the axial direction of the pipe section to be measured.

[0052] The rigidity enhancer is fixedly connected to the annular stepping unit and contacts the surface of the pipe section to be tested, and is used to enhance the axial deformation strength of the pipe section to be tested. In other words, the left and right ends of the rigidity enhancer can be fixedly connected to the annular stepping unit, and the bottom surface of the rigidity enhancer can be closely attached to the surface of the pipe section to be tested, thereby enhancing the axial deformation strength of the pipe section to be tested and preventing the pipe section to be tested from deforming. Here, the number of rigidity enhancers can be set to multiple, and they are arranged along the circumference of the pipe section to be tested.

[0053] Furthermore, in this embodiment, the rigidity enhancer may be a linear reinforcing rib, or a T-shaped nylon plate.

[0054] In this embodiment, axial scanning and circumferential stepping functions are designed in view of the circular shape of the non-metallic pipe, so as to realize local surface scanning of the non-metallic pipe. At the same time, in view of the thin diameter and high flexibility of the non-metallic pipe, a pipe axial stiffness enhancement structure is designed to greatly reduce the deformation of the non-metallic pipe and ensure the stability of the tooling and data accuracy during the scanning process.

[0055] Embodiment 3

[0056] A third embodiment of the present invention provides a non-metallic pipeline terahertz nondestructive testing device, which includes a terahertz probe, an axial scanning unit, a circumferential stepping unit, a rigidity enhancer, and a tooling support.

[0057] The terahertz probe is fixedly mounted on the axial scanning unit, and the incident direction of the terahertz probe is perpendicular to the pipe section to be measured, so as to perform three-dimensional scanning and imaging of the pipe section to be measured.

[0058] The circumferential stepping unit is fixed around the surface of the pipe section to be measured, and is used to drive the terahertz probe to move along the circumference of the pipe section to be measured, and is also used to enhance the circumferential stiffness of the pipe section to be measured.

[0059] The axial scanning unit is arranged along the axial direction of the pipe section to be measured and is slidably connected with the annular stepping unit to drive the terahertz probe to move along the axial direction of the pipe section to be measured.

[0060] The rigidity enhancer is fixedly connected to the annular stepping unit and contacts the surface of the pipe section to be tested, so as to enhance the axial deformation strength of the pipe section to be tested.

[0061] One end of the tooling support is fixedly connected to the circumferential stepping unit, and the other end of the tooling support is fixedly connected to the ground, and is used to fix the circumferential stepping unit.

[0062] Furthermore, in this embodiment, the tool support may be configured as a telescopic structure so that the length of the tool support can be adjusted according to the height of the pipe section to be measured from the ground.

[0063] In this embodiment, axial scanning and circumferential stepping functions are designed in view of the circular characteristics of the non-metallic pipe, so as to realize the local surface scanning of the non-metallic pipe; in view of the thin diameter and high flexibility of the non-metallic pipe, a pipe axial stiffness enhancement structure is designed to greatly reduce the deformation of the non-metallic pipe and ensure the stability of the tooling and data accuracy during the scanning process; at the same time, in view of the complexity and uncertainty of the on-site excavation environment, a tooling support structure is designed to ensure the stability of the tooling during the scanning process, reduce the vibration of the tooling, and avoid the influence of structural vibration on the detection process.

[0064] Embodiment 4

[0065] A fourth embodiment of the present invention provides a terahertz nondestructive testing method for non-metallic pipelines. The nondestructive testing method is implemented by the above-mentioned nondestructive testing device and includes the following steps:

[0066] Step S101: adjusting the clamping angle of the terahertz probe so that the incident direction of the terahertz signal is perpendicular to the surface of the pipe section to be tested.

[0067] Step S102: controlling the axial scanning unit to drive the terahertz probe to perform axial scanning along a first axial moving direction at a predetermined axial scanning speed.

[0068] Step S103: Subsequently, the circumferential stepping unit is controlled to drive the axial scanning unit to move a predetermined circumferential length along the circumference of the pipe section to be measured at a predetermined circumferential scanning speed.

[0069] Step S104: Subsequently, the axial scanning unit is controlled to drive the terahertz probe to perform axial scanning along the second axial moving direction at a predetermined axial scanning speed.

[0070] The first axial movement direction is opposite to the second axial movement direction. In other words, assuming that the pipe segment to be tested has a first end and a second end (for example, a left end and a right end) distributed along the length direction, if the first axial movement direction is a direction of linear movement from the first end of the pipe segment to be tested to the second end of the pipe segment to be tested, then the second axial movement direction is a direction of linear movement from the second end of the pipe segment to be tested to the first end of the pipe segment to be tested.

[0071] Step S105: repeat the above steps S102 to S104 until the scanning path of the terahertz probe covers the defect distribution area of ​​the pipe section to be tested.

[0072] Furthermore, in this embodiment, step S101 further includes: adjusting the clamping height and the clamping angle of the terahertz probe according to the focal size of the terahertz probe so that the focus of the terahertz signal is located at the center of the wall thickness of the pipe section to be measured.

[0073] Further, in this embodiment, in step S102 and step S104, the predetermined axial scanning speed may be determined based on the axial scanning resolution and the data acquisition frequency.

[0074] Further, in this embodiment, in step S103, the predetermined circumferential scanning speed may be determined based on the circumferential scanning resolution, the axial scanning length, and the axial scanning speed.

[0075] Embodiment 5

[0076] The fifth embodiment of the present invention provides a non-metallic pipeline terahertz non-destructive testing device and a method of using the same.

[0077] Specifically, the non-metallic pipeline terahertz nondestructive testing device proposed in this embodiment includes: a terahertz probe, an axial scanning unit, a circumferential stepping unit, a rigidity enhancer and a tooling support.

[0078] It should be noted that the axial scanning unit is the axial scanning unit described in the above embodiment, and the circumferential stepping unit is the circumferential stepping unit described in the above embodiment. The axial scanning unit is the axial scanning transmission structure of the terahertz probe, and the circumferential stepping unit is the circumferential scanning transmission structure of the terahertz probe. In addition, the rigidity enhancer is a structure for enhancing the axial rigidity of the pipe section to be detected, and the tooling support is a structure for vertically supporting the axial scanning unit, the circumferential stepping unit and the pipe section with detection, which is used to prevent the deformation of the pipeline caused by the additional load of the device.

[0079] The axial scanning unit includes an axial scanner (that is, the first scanning drive module), a probe fixture and an axial stepping track. Among them, the probe fixture is a clamping device for the terahertz probe, which can clamp and fix the probe, and has the function of adjusting and fixing the probe height and clamping angle. The axial stepping track is a straight guide track, which is a power device for the probe to scan axially. The length of the axial stepping track is greater than the axial length of the pipe section to be measured, and the probe fixture can be installed, and the probe fixture can only move axially along the track, and the probe fixture can be controlled to reciprocate uniformly along a straight line at a predetermined axial scanning speed. The axial scanner is a linear motor, which is used to provide power to the probe fixture for uniform reciprocating motion along the axial stepping track.

[0080] The circumferential stepping unit includes two annular transmission tracks, two annular steppers (that is, the second scanning drive module) and two annular drivers. Among them, the circumference of the annular transmission track can be adjusted according to the outer diameter of the pipeline to be tested, and can be fixed around the surface of the non-metallic pipeline to increase the annular stiffness of the pipeline. The two annular steppers are two annular linear motors, which are used to provide the axial scanning unit with power for circumferential movement along the pipe section to be tested. The two annular drivers are respectively installed on two annular tracks, and can move along the annular transmission tracks according to the set speed, and are assembled with the assembled axial scanning unit to form a simply supported beam structure, thereby driving the axial scanning unit to move as a whole along the pipeline circumference at a predetermined circumferential scanning speed at a certain time interval, completing the circumferential stepping scan during the scanning process.

[0081] The rigidity enhancer is a linear reinforcement rib, and its main function is to cooperate with the annular transmission track to enhance the axial deformation stiffness of the pipeline, ensure the axial straightness of the pipe section to be tested, and keep the vertical distance between the terahertz probe and the pipe surface constant during axial scanning, avoiding abnormal scanning signals caused by pipeline deformation.

[0082] The tooling support is two length-adjustable supports, and its main function is to maintain the height of the pipe section to be tested and prevent signal errors caused by tooling jitter during the detection process. One end of the tooling support can be vertically assembled and connected to the annular stepping unit, and the other end can be vertically fixedly connected to the ground, thereby playing the role of supporting the detection device. For example, the other end of the tooling support can be set to a sharper end face, which can be supported by inserting into the soil. For another example, the other end of the tooling support can be directly fixedly connected to the ground by a fixed connection method such as a thread, a bolt, or a screw.

[0083] Furthermore, in this embodiment, the nondestructive testing device may further include: a controller connected to the axial scanning unit and the circumferential stepping unit, and used to control the axial scanning speed and the circumferential scanning speed.

[0084] This embodiment also provides a method for using a terahertz nondestructive testing device for non-metallic pipelines, which mainly includes processes such as tooling assembly, support adjustment, control line connection, scanning parameter setting, and defect scanning.

[0085] The first step is tooling assembly.

[0086] i) First, the installation length of the circumferential stepping unit is selected according to the outer diameter of the pipe section to be measured. Specifically, the axial stepping track is selected according to the length of the pipe section to be measured, and is assembled with the probe fixture into an axial scanning unit.

[0087] ii) Secondly, two annular steppers are fixedly installed on both sides of the pipe section to be measured, so that the spacing between them is equal to the installation distance of the axial stepper track, and the axial connection line of the two annular drivers is parallel to the axis of the pipe section to be measured.

[0088] iii) Finally, the two ends of the assembled axial scanning unit are respectively connected to the two annular drivers to form a simply supported beam structure, and the terahertz probe is installed on the probe fixture.

[0089] The second step is support adjustment.

[0090] i) For the pipe section to be tested with greater flexibility, multiple rigidity enhancers are fixedly connected vertically to two annular transmission tracks at certain intervals to keep the axis of the pipe section to be tested straight and not prone to bending and deformation. Avoid defective parts when installing the rigidity enhancers.

[0091] For the pipe section to be tested with less flexibility, if the axis of the pipe section is straight and will not bend or deform under the gravity of the tooling, the rigidity enhancer may not be used.

[0092] ii) The upper ends of the two tool supports are connected to the bottom of the two annular transmission tracks respectively, and the bottom ends are fixed in the soil by insertion. By adjusting the height of the tool supports, the pipe section to be tested is kept flush with the pipes on both sides in the axial direction.

[0093] The third step is to connect the control lines.

[0094] Insert the axial stepping control line into the axial motion input interface of the controller, and insert the control line of the circumferential drive into the circumferential motion input interface of the controller to complete the connection between the axial scanning unit, the circumferential stepping unit and the controller.

[0095] The fourth step is to set scanning parameters.

[0096] i) According to the focal size of the terahertz probe, adjust the clamping angle and clamping height of the terahertz probe so that the terahertz signal is incident perpendicular to the surface of the pipeline to be tested and the signal focus is located exactly in the center of the wall thickness of the pipeline to be tested, so as to obtain the best scanning effect.

[0097] ii) Set the axial scanning speed x and the circumferential stepping speed y in the control system.

[0098] The axial scanning speed x is related to the data acquisition rate f and the axial scanning resolution k1, and is calculated according to formula (1). The circumferential stepping speed y is related to the circumferential resolution k2, the axial scanning speed x and the axial scanning length L, and is calculated according to formula (2).

[0099] x=k1×f (1)

[0100]

[0101] Among them, x is the axial scanning speed, y is the circumferential scanning speed, f is the data acquisition rate, k1 is the axial scanning resolution, k2 is the circumferential scanning resolution, and L is the axial scanning length.

[0102] Step 5: Defect scanning.

[0103] Start the controller, set the data acquisition system parameters according to the defect range, axial scanning speed and circumferential stepping time, and click to start the tooling scanning and terahertz detection system. The axial scanning unit drives the terahertz probe to move axially at the set axial scanning speed. When the probe completes a line along the axial scanning, the circumferential stepping unit drives the axial scanning unit as a whole to move a step length along the circumferential direction. The axial scanning unit drives the terahertz probe to scan in the opposite axial direction. During the scanning process, the data collector records and stores the terahertz reflected wave.

[0104] The above steps are repeated until the scanning path of the terahertz probe covers the defect distribution area of ​​the pipe section to be tested, and the terahertz two-dimensional scanning of the pipe section to be tested is completed.

[0105] In view of the lack of special scanning tooling for terahertz non-destructive testing of non-metallic pipelines, the existing equipment cannot be applied to the defects of on-site pipeline non-destructive testing. This embodiment combines the material and structural characteristics of non-metallic pipelines and the special requirements of terahertz scanning to design a tooling suitable for on-site terahertz non-destructive testing scanning. Through the functions of axial scanning, circumferential stepping, structural stiffness enhancement and tooling support, a non-metallic pipeline terahertz non-destructive testing device is designed to realize the automated terahertz scanning of on-site non-metallic pipelines, reduce the impact of the tooling on the pipeline bearing capacity, and ensure the stability of the scanning process and the accuracy of the data. This embodiment can realize terahertz three-dimensional non-destructive testing of non-metallic pipelines on site, laying a foundation for defect detection, evaluation and life prediction of non-metallic pipelines.

[0106] Embodiment 6

[0107] The sixth embodiment of the present invention provides a non-metallic pipeline terahertz non-destructive testing device and a method of using the same.

[0108] Taking urban gas polyethylene pipeline as an example, a terahertz non-destructive testing device for non-metallic pipelines includes: an axial scanning unit, a circumferential stepping unit, a terahertz probe, a tooling support and a rigidity enhancer.

[0109] Please refer to Figure 1 The pipe section 6 to be tested is a polyethylene pipe for urban gas, with a diameter of 300 mm and a wall thickness of 30 mm. There are pore defects inside the pipe body. The defect distribution area 11 is in the range of 100 mm in axial length and 12:00 to 2:00 in circumferential distribution.

[0110] The axial scanning unit consists of an axial scanner, an axial stepping track 1 and a probe fixture 2. The axial scanner is a linear motor, which is used to provide the probe fixture with power for uniform reciprocating motion along the axial stepping track. The probe fixture 2 is mounted on the linear motor and is used to clamp and fix the terahertz probe 3. The axial stepping track 1 is a motor track, and the motor track length is 300 mm and the motor track width is 20 mm.

[0111] The circumferential stepping unit is composed of a circumferential stepper, a circumferential driver 4 and a circular transmission track 5. The circumferential stepper is two circular linear motors, which are used to provide the axial scanning unit with power for circumferential movement of the pipe section to be measured. The circumference of the circular transmission track 5 is consistent with the outer circumference of the pipe section to be measured 6, and the width is 20mm. The circumferential driver 4 is the driving module of the motor, which is arranged on the circular transmission track 5 and connected to the circumferential stepper, and is used to drive the axial scanning unit as a whole to move a certain distance along the circular transmission track under the power drive of the circular linear motor.

[0112] The rigidity enhancer 7 is a nylon plate with a T-shaped cross section, and the length of the rigidity enhancer is 300 mm, the width of the rigidity enhancer is 20 mm, and the thickness of the rigidity enhancer is 10 mm. There are 4 rigidity enhancers in total, which can be assembled with the annular transmission track 5 through threads to enhance the axial deformation rigidity of the pipeline and ensure the axial straightness of the pipe section to be tested.

[0113] The tool support 8 is a cylindrical metal rod with telescopic function. The top of the tool support can be connected to the annular transmission track 5 through a thread; the bottom of the tool support is a three-point support structure with sharp legs that can be inserted into the soil 9 for fixation. The adjustable height of the tool support is 200mm to 1000mm.

[0114] This embodiment also includes the use of the non-metallic pipeline terahertz non-destructive testing device, please refer to Figure 2 The method of using the detection device mainly includes tooling assembly, support adjustment, control line connection, scanning parameter setting, defect scanning and other processes.

[0115] The first step is tooling assembly.

[0116] The installation length of the annular transmission track is selected as 942 mm according to the outer diameter of the pipeline to be tested, and the length of the axial stepping track is selected as 300 mm according to the length of the defect distribution area of ​​the pipeline section to be tested, and it is assembled with the probe fixture into an axial scanner.

[0117] Two annular steppers are fixedly installed on both sides of the pipe section to be tested, so that the spacing between them is equal to the installation distance of the axial stepper track, and the axial connection line of the two annular drivers is parallel to the axis of the pipe section to be tested.

[0118] The two ends of the assembled axial scanner are respectively connected to the two annular drivers by bolts to form a simply supported beam structure, and the terahertz probe is installed on the probe fixture.

[0119] The second step is support adjustment.

[0120] Since the diameter of the pipe section to be tested is small and its flexibility is large, a rigidity enhancer is required to increase the rigidity of the pipeline. The four rigidity enhancers are vertically fixed to the two annular transmission tracks according to the annular distribution of 12:00 / 3:00 / 6:00 and 9:00 respectively. The connection method adopts threaded connection, which not only improves the rigidity of the pipeline, but also avoids the defect distribution area of ​​12:00~2:00.

[0121] The upper ends of the two tooling supports are respectively connected to the bottom of the two annular transmission tracks through threaded fixings, and the triangular supporting structure at the bottom is fixed in the soil in an inserted manner.

[0122] In this embodiment, the distance between the bottom of the trench and the bottom of the pipeline to be tested is 300 mm, so the height of the tool support is adjusted to 300 mm so that the pipeline section to be tested is kept flush with the pipelines on both sides in the axial direction.

[0123] The third step is to connect the control lines.

[0124] In this embodiment, a terahertz probe of T-ray 5000 is used, and the tooling controller uses a tooling control module provided with the terahertz data acquisition controller, which can collect data according to the scanning rate of the scanning tooling and automatically identify and mark data of different scanning lines.

[0125] Insert the axial stepping control line into the X input terminal of the terahertz data acquisition controller, and insert the control line of the circumferential drive into the Y input terminal of the terahertz data acquisition controller to complete the connection between the tooling and the controller.

[0126] The fourth step is to set scanning parameters.

[0127] The focal size of the terahertz probe used in this embodiment is 100 mm. The clamping angle and clamping height of the terahertz probe are adjusted so that the terahertz signal is incident perpendicularly to the surface of the pipeline to be tested, and the distance between the bottom of the probe and the pipeline surface is 85 mm.

[0128] In this embodiment, the axial resolution and circumferential resolution are both 1 mm, the data acquisition frequency is 100 Hz, the axial scanning rate calculated according to formula (1) is 0.1 m / s, and the circumferential stepping speed calculated according to formula (2) is 0.67 m / s.

[0129] Therefore, the axial scanning speed x is set to 0.1 m / s and the circumferential stepping speed y is set to 0.67 m / s in the controller.

[0130] Step 5: Defect scanning.

[0131] Start the controller, set the data acquisition system parameters according to the defect range, axial scanning speed and circumferential step time, and click to start the tooling scanning and terahertz detection system.

[0132] like Figure 3 As shown, the axial scanning unit drives the terahertz probe to move axially at the set axial scanning speed; when the probe completes a line along the axial scanning, the circumferential stepping unit drives the axial scanning unit as a whole to move a step length along the circumferential direction; then, the axial scanning unit drives the terahertz probe to scan in the opposite axial direction, and during the scanning process, the data collector records and stores the terahertz reflected wave. Repeat the above steps until the scanning path 10 of the terahertz probe covers the defect distribution area 11 located in the direction of 12:00 to 3:00 on the pipe section 6 to be tested, and the terahertz two-dimensional scanning of the pipe section to be tested is completed.

[0133] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0134] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0135] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A terahertz nondestructive testing device for non-metallic pipelines, characterized in that: The nondestructive testing device includes a terahertz probe, an axial scanning unit and a circumferential stepping unit; The terahertz probe is arranged on the axial scanning unit, and the incident direction of the bottom of the terahertz probe is perpendicular to the surface of the pipe section to be measured; The axial scanning unit is arranged along the length direction of the pipe section to be measured, and is configured to drive the terahertz probe to perform uniform reciprocating motion along the length direction of the pipe section to be measured at a predetermined axial scanning speed; The circumferential stepping unit is connected to the axial scanning unit and is configured to drive the axial scanning unit to move a predetermined circumferential length along the circumferential direction of the pipe section to be measured at a predetermined circumferential scanning speed; Wherein, the pipe section to be tested is a non-metallic pipeline operating on site.

2. The non-metallic pipeline terahertz non-destructive testing device according to claim 1 is characterized in that: The axial scanning unit includes an axial stepping track, a probe fixture and a first scanning driving module; Wherein, the axial stepping track is arranged in parallel above the pipe section to be measured, and the length of the axial stepping track is greater than the axial length of the pipe section to be measured; The probe fixture is slidably connected to the axial stepping track and is configured to be able to clamp and fix the terahertz probe and adjust the clamping height and clamping angle of the terahertz probe; The first scanning driving module is connected to the probe fixture and is configured to control the probe fixture to perform uniform reciprocating motion on the axial stepping track at a predetermined axial scanning speed.

3. The non-metallic pipeline terahertz non-destructive testing device according to claim 1 is characterized in that: The circumferential stepping unit comprises a circumferential transmission track and a second scanning drive module; The annular transmission track is sleeved on the surface of the pipe section to be measured, and the circumference of the annular transmission track is less than or equal to the outer circumference of the pipe section to be measured; The second scanning driving module is connected to the axial scanning unit and is configured to control the axial scanning unit to move a predetermined circumferential length along the circumferential direction of the pipe section to be measured at a predetermined circumferential scanning speed.

4. The non-metallic pipeline terahertz non-destructive testing device according to claim 1 is characterized in that: The nondestructive testing device further comprises a tool support, one end of which is fixedly connected to the circumferential stepping unit, and the other end of which is fixedly connected to the ground.

5. The non-metallic pipeline terahertz non-destructive testing device according to claim 1 is characterized in that: The nondestructive testing device also includes a rigidity enhancer, which is connected to the annular stepping unit and contacts the surface of the pipe section to be tested, and is configured to enhance the axial deformation strength of the pipe section to be tested.

6. The non-metallic pipeline terahertz non-destructive testing device according to claim 5, characterized in that: The rigidity enhancer is straight-line or T-shaped.

7. A non-metallic pipeline terahertz non-destructive testing method, implemented by the non-destructive testing device according to any one of claims 1 to 6, characterized in that: The non-destructive testing method comprises: Adjust the clamping angle of the terahertz probe so that the incident direction of the terahertz signal is perpendicular to the surface of the pipe section to be tested; Controlling the axial scanning unit to drive the terahertz probe to perform axial scanning along a first axial moving direction at a predetermined axial scanning speed; Control the circumferential stepping unit to drive the axial scanning unit to move a predetermined circumferential length along the circumferential direction of the pipe section to be measured at a predetermined circumferential scanning speed; Controlling the axial scanning unit to drive the terahertz probe to perform axial scanning along a second axial moving direction at a predetermined axial scanning speed, wherein the first axial moving direction is opposite to the second axial moving direction; Repeat the above steps until the scanning path of the terahertz probe covers the defect distribution area of ​​the pipe section to be tested.

8. The terahertz nondestructive testing method for non-metallic pipelines according to claim 7 is characterized in that The nondestructive testing method further comprises: According to the focal size of the terahertz probe, adjust the clamping height and clamping angle of the terahertz probe so that the focus of the terahertz signal is located in the center of the wall thickness of the pipe section to be measured.

9. The non-metallic pipeline terahertz non-destructive testing method according to claim 7, characterized in that: The nondestructive testing method further comprises: The predetermined axial scanning speed is determined based on the axial scanning resolution and the data acquisition frequency.

10. The non-metallic pipeline terahertz non-destructive testing method according to claim 9, characterized in that: The nondestructive testing method further comprises: The predetermined circumferential scanning speed is determined based on the circumferential scanning resolution, the axial scanning length and the axial scanning speed.

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