A plastic pipe wall thickness fluctuation on-line laser detection device and method

Abstract

The application relates to the technical field of plastic pipe wall thickness detection, in particular to a plastic pipe wall thickness fluctuation on-line laser detection device and method, which comprises an L-shaped fixed rack, an arc-shaped support frame for placing the pipe is arranged on a horizontal section of the fixed rack, a guide rod coaxial with the support frame is arranged through a vertical section of the fixed rack, two groups of inner support blocks which are symmetrically distributed and circumferentially uniformly arranged are arranged on the circumferential surface of the guide rod, the inner support blocks are radially movable and abut against the inner wall of the pipe; the guide rod is inserted into the pipe, the preliminary guiding, limiting and pre-straightening of the pipe are realized, the inner wall of the pipe is kept flat, a foundation is laid for subsequent detection, irregular bending of the pipe due to the flexibility of the pipe is effectively avoided, detection deviation is reduced, and orderly development of the detection work is ensured.

Description

Technical Field

[0001] This application relates to the technical field of plastic pipe wall thickness detection, and in particular to an online laser detection device and method for plastic pipe wall thickness fluctuation. Background Technology

[0002] In the plastics industry, producing high-quality pipes is crucial, especially given the extremely high requirements for consistent pipe wall thickness. Traditional methods for wall thickness measurement mainly include manual measurement and mechanical inspection, which are often insufficient in accuracy and efficiency. To improve inspection accuracy and efficiency, laser ranging technology has begun to be widely used in industrial inspection.

[0003] For example, patent application number 2025112439709 discloses a device for detecting the inner and outer diameters of TPU pipes. The device is equipped with a worktable, two sets of laser rangefinder sensors A and B, a base with a pipe positioning and clamping assembly and a support rod at the top of the worktable, and an output end of an electric push rod on both sides of the support rod connected to a mounting plate. The device forms a stable annular air curtain outside the laser rangefinder sensor A through airflow, reducing detection errors caused by environmental interference and improving the accuracy and reliability of the TPU pipe inner and outer diameter detection data.

[0004] Since TPU pipes also fall under the category of plastic pipes, the existing technology described above can be used to measure the inner and outer diameters of plastic pipes. The wall thickness of the plastic pipe can then be obtained by subtracting the inner and outer diameters. However, the following problems still exist: Because plastic pipes are flexible materials, the existing technology described above does not have corresponding limiting and straightening structures when measuring their inner and outer diameters. During the testing process, the plastic pipes are prone to irregular bending due to their flexibility, which directly leads to deviations in the coaxiality of the pipes. This results in significant errors in the inner and outer diameter measurement data, seriously affecting the accuracy and reliability of the final test results. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides an online laser detection device and method for wall thickness fluctuation of plastic pipes, employing the following technical solution: In a first aspect, an online laser detection device for wall thickness fluctuation of plastic pipes includes an L-shaped fixed frame, with an arc-shaped support frame for placing the pipe on the horizontal section of the fixed frame, and a guide rod coaxial with the support frame installed through the vertical section.

[0006] The guide rod has a coaxial clearance groove, and multiple internal laser rangefinders are evenly arranged circumferentially on the inner wall of the clearance groove.

[0007] The horizontal section of the fixed frame is equipped with a ring frame coaxial with the guide rod, and the inner side wall of the ring frame is equipped with an external laser rangefinder that corresponds one-to-one with the inner laser rangefinder.

[0008] The guide rod has two sets of symmetrically distributed, circumferentially evenly arranged inner support blocks on its circumferential surface, which move radially and press against the inner wall of the pipe.

[0009] Preferably, the guide rod has a through groove inside, a piston is slidably installed in the through groove, and a pressure reducing valve is provided.

[0010] The guide rod has a guide groove that corresponds to the inner support block and communicates with the through groove. The inner support block is slidably disposed in the guide groove, and the guide groove is provided with an elastic element for resetting the inner support block.

[0011] Preferably, the elastic element is a telescopic spring, with one end of the telescopic spring fixed to the inner wall of the guide groove and the other end fixed to the corresponding inner support block, and the inner support block does not collide with the telescopic spring when it moves.

[0012] Preferably, the end face of the inner support block that contacts the inner wall of the pipe is provided with ball bearings to reduce the friction between the pipe and the inner support block when the pipe moves.

[0013] Preferably, the support frame extends along the length of the horizontal section of the fixed frame, and the part corresponding to the clearance groove is provided with a partition to allow space for the measurement of the external laser rangefinder.

[0014] Preferably, a horizontal bar is installed on the vertical section of the fixed frame, a connecting frame is slidably mounted on the horizontal bar, and an elastic airbag coaxial with the support frame is installed at the bottom of the connecting frame.

[0015] The support frame is equipped with a pressure ring for compressing the elastic air bladder. The ring frame contains an L-shaped linkage rod. The horizontal section of the linkage rod is connected to the pressure ring, and the vertical section is used to fit with the pipe.

[0016] Preferably, the elastic airbag is connected to the air inlet of the through groove through a connecting pipe. The elastic airbag can only deform along the length of the horizontal section of the fixed frame, and its bottom is provided with a groove for making way for the connecting rod of the support frame.

[0017] Preferably, the guide rod has a transition channel and an annular groove inside. One end of the transition channel is connected to the annular groove, and the other end is connected to the part of the through groove located between the pressure reducing valve and the conical blocking block.

[0018] The side wall of the clearance slot away from the fixed frame is provided with an air jet channel that communicates with the annular groove.

[0019] Preferably, the inner wall of the clearance groove is provided with a dust collection groove, one end of which is located between adjacent inner laser rangefinders, and the other end extends through to the end of the guide rod away from the vertical section of the fixed frame, for communication with external negative pressure equipment.

[0020] Secondly, a detection method using an online laser detection device for wall thickness fluctuation of plastic pipes includes the following steps: S1, placing the pipe to be detected on a support frame, pushing the pipe to move so that the guide rod is inserted into the pipe to complete the initial guidance and pre-straightening of the pipe.

[0021] S2. The pipe push linkage rod drives the pressure ring to squeeze the elastic air bag. The gas enters the through groove through the connecting pipe, driving the inner support block to move radially and press against the inner wall of the pipe.

[0022] S3. When the pipe moves to the inspection area, the inner and outer laser rangefinders simultaneously detect the inner and outer diameters of the pipe and calculate the difference to obtain the wall thickness. The pressure reducing valve maintains the stability of the inner support block's supporting force, the air jet channel sprays air to remove impurities from the inner wall of the pipe, and the dust suction channel removes impurities.

[0023] S4. Continuously collect test data and compare it with standard values ​​to complete the full-length wall thickness fluctuation test of the pipe.

[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. The guide rod designed in this invention is inserted into the pipe to achieve preliminary guidance, positioning and pre-straightening of the pipe, keeping the inner wall of the pipe straight, laying the foundation for subsequent testing, effectively avoiding irregular bending of the pipe due to its own flexibility, reducing testing deviations, and ensuring the orderly conduct of testing work.

[0025] 2. The inner support block designed in this invention can move outward and press against the inner wall of the pipe, further improving the straightness of the inner wall of the pipe. This avoids the deviation of the detection beam caused by plastic bending and local deformation of the pipe from the source, ensuring that the synchronization error of the detection data of the inner and outer laser rangefinders is within the allowable range. At the same time, the pressure reducing valve cooperates with related components to stabilize the support force of the inner support block, prevent the pipe from shifting or the inner wall from sinking, and ensure the accuracy and reliability of the detection results.

[0026] 3. Excess high-pressure gas is ejected through the jet tank, which can remove impurities adhering to the inner wall of the pipe. The dust collection tank simultaneously removes suspended impurities, preventing impurities from obstructing the detection optical path or wearing down equipment parts. At the same time, the internal and external laser rangefinders work together to accurately obtain the pipe wall thickness, enabling continuous detection of the entire length of the pipe. It can also identify defects such as wall thickness deviation, improving the comprehensiveness and accuracy of the detection. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the three-dimensional installation structure between the present invention and the pipe.

[0028] Figure 2 This is a three-dimensional structural schematic diagram of the present invention.

[0029] Figure 3 This is a schematic diagram of the three-dimensional installation structure between the elastic airbag, guide rod, and ring frame of the present invention.

[0030] Figure 4 This is a schematic diagram of the three-dimensional installation structure between the ring frame, the inner laser rangefinder, the outer laser rangefinder, and the guide rod of the present invention.

[0031] Figure 5 This is a schematic diagram of the three-dimensional installation structure between the guide rod and the inner support block of the present invention.

[0032] Figure 6 This is the present invention. Figure 2 The main view.

[0033] Figure 7 This is a cross-sectional view of the guide rod of the present invention located near the relief groove (cut along the length of the horizontal section of the fixed frame).

[0034] Figure 8 This is a cross-sectional view (cut along the length of the horizontal section of the fixed frame) of the guide rod of the present invention after it has been rotated 30 degrees and is located near the clearance groove.

[0035] Figure 9 This is a cross-sectional view of the guide rod of the present invention located on the side of the clearance groove (cut along the length of the horizontal section perpendicular to the fixed frame). Explanation of reference numerals in the attached drawings: 1. Fixed frame; 100. Pipe; 2. Support frame; 3. Detection mechanism; 31. Guide rod; 311. Clearance groove; 32. Internal laser rangefinder; 33. Annular frame; 34. External laser rangefinder; 35. Internal support block; 312. Through groove; 313. Piston; 314. Pressure reducing valve; 315. Cavity 1; 316. Cavity 2; 11. Horizontal rod; 12. Connecting frame; 13. Elastic airbag; 14. Pressure-reducing ring; 15. Linkage rod; 16. Connecting pipe; 4. Transition channel; 41. Annular groove; 42. Conical blocking block; 43. Air jet groove; 44. Dust suction groove. Detailed Implementation

[0036] The following is in conjunction with the appendix Figures 1 to 9 This application will be described in further detail.

[0037] This application discloses an online laser detection device and method for wall thickness fluctuation of plastic pipes. By initially guiding and pre-straightening the pipe, the inner wall of the pipe is kept straight, laying the foundation for subsequent detection. This effectively avoids irregular bending of the pipe due to its own flexibility, reduces detection deviation, and ensures that the detection work is carried out in an orderly manner.

[0038] Reference Figure 1 as well as Figure 2An online laser detection device for wall thickness fluctuation of plastic pipes includes an L-shaped fixed frame 1. A support frame 2 for placing pipes 100 is provided on the horizontal section of the fixed frame 1. In addition, a detection mechanism 3 for detecting the wall thickness of pipes 100 is also installed on the fixed frame 1. The detection mechanism 3 includes a guide rod 31 for guiding and limiting pipes 100. The guide rod 31 is installed through the vertical section of the fixed frame 1. A clearance groove 311 coaxial with the guide rod 31 is provided on the guide rod 31. Multiple internal laser rangefinders 32 are evenly arranged in the circumference of the clearance groove 311. The internal laser rangefinders 32 are installed on the inner wall of the clearance groove 311 through connecting protrusions.

[0039] A ring frame 33 coaxial with the guide rod 31 is provided on the horizontal section of the fixed frame 1, and the ring frame 33 is installed on the horizontal section of the fixed frame 1 by a support rod. Multiple external laser rangefinders 34 corresponding one-to-one with the inner laser rangefinders 32 are evenly arranged on the inner sidewall of the ring frame 33. Two sets of symmetrically distributed inner support blocks 35 are arranged on the circumferential surface of the guide rod 31 along its length direction. The inner support blocks 35 are located on the surface of the guide rod 31 and on both sides of the relief groove 311, and multiple are evenly distributed along the circumference of the guide rod 31.

[0040] The support frame 2 extends along the length of the horizontal section of the fixed frame 1, and its cross-section is an arc-shaped structure coaxial with the guide rod 31. The part of the support frame 2 corresponding to the clearance groove 311 is separated to allow the external laser rangefinder 34 to measure, ensuring that the external laser rangefinder 34 can perform distance measurement on the bottom of the pipe 100. The support frame 2 is installed on the horizontal section of the fixed frame 1 through the connecting rod.

[0041] The clearance groove 311 is the testing area. When the pipe 100 moves to the testing area, the wall thickness is tested. In specific operation, the pipe 100 to be tested is moved onto the support frame 2 and pushed along the support frame 2. At this time, the guide rod 31 is inserted into the pipe 100. The guide rod 31 can perform preliminary guiding and limiting treatment on the pipe 100 and perform pre-straightening treatment on the pipe 100 so that the inner wall of the pipe 100 is in a straight state, in preparation for subsequent testing.

[0042] When the pipe 100 moves to the detection area, the inner support block 35 moves outward and supports the inner wall of the pipe 100, further improving the straightness of the inner wall of the pipe 100. This fundamentally avoids the deviation of the incident angle of the detection beam of the inner laser rangefinder 32 and the outer laser rangefinder 34 and the deviation of the reflection path caused by the plastic bending and local deflection deformation of the pipe 100. This ensures that the synchronization error of the two sets of detection data is within the allowable threshold range, and ensures the consistency and reliability of the subsequent dimensional detection results.

[0043] After the inner support block 35 supports the inner wall of the pipe 100, the inner and outer diameters of the pipe 100 are detected by the cooperation of the inner laser rangefinder 32 and the outer laser rangefinder 34. Then, the difference between the inner and outer diameters is calculated to obtain the wall thickness of the pipe 100.

[0044] To ensure that the inner support block 35 always supports and straightens the inner wall of the pipe 100, the pressure reducing valve 314 and the piston 313 provided in this invention cooperate to ensure that the inner support block 35 always abuts against the inner wall of the pipe 100. Specifically, the guide rod 31 has a through groove 312 inside, and the piston 313 is slidably arranged inside the through groove 312. The guide rod 31 has a guide groove that corresponds one-to-one with the inner support block 35 and communicates with the through groove 312. The inner support block 35 is slidably arranged inside the guide groove. The guide groove is provided with an elastic element for resetting the inner support block 35. The pressure reducing valve 314 is provided inside the through groove 312.

[0045] The elastic element is an existing telescopic spring (not shown in the figure). One end of the telescopic spring is installed on the inner wall of the guide groove, and the other end is installed on the corresponding inner support block 35. The inner support block 35 will not collide with the telescopic spring during movement. The end face of the inner support block 35 that contacts the inner wall of the pipe 100 is provided with ball bearings (not shown in the figure) to ensure that the friction between the inner wall of the pipe 100 and the inner support block 35 is reduced during the movement of the pipe 100. This prevents the friction between the pipe 100 and the inner support block 35 from being too large, which would prevent the pipe 100 from sliding on the inner support block 35. This ensures that the pipe 100 can move on the inner support block 35 so that the inner wall of the pipe 100 can move in an orderly manner to the detection area, and then the inner and outer diameters of the pipe 100 can be detected and processed sequentially.

[0046] A horizontal bar 11 is installed on the vertical section of the fixed frame 1. A connecting frame 12 is slidably installed on the horizontal bar 11 along its length. An elastic airbag 13 coaxial with the support frame 2 is installed at the bottom of the connecting frame 12. The bottom of the elastic airbag 13 is provided with a groove for making way for the connecting bar during its contraction. A pressure ring 14 for squeezing the elastic airbag 13 is slidably installed on the support frame 2 between the vertical section of the fixed frame 1 and the groove 311. An L-shaped linkage rod 15 is provided inside the ring frame 33. The horizontal section of the linkage rod 15 is installed on the pressure ring 14, and the vertical section of the linkage rod 15 is used to cooperate with the pipe 100.

[0047] The elastic airbag 13 is installed with a connecting pipe 16 that is connected to the vertical section of the fixed frame 1. The other end of the connecting pipe 16 passes through the vertical section of the fixed frame 1 and is connected to the air inlet of the through groove 312.

[0048] The elastic airbag 13 can only deform along the length of the horizontal section of the fixed frame 1. When the pressure reducing valve 314 reaches the maximum critical pressure, the inner support block 35 can press against the inner wall of the pipe 100. The part of the through groove 312 between the piston 313 and the connecting pipe 16 is provided with cavity one 315, and the part of the through groove 312 between the piston 313 and the pressure reducing valve 314 is provided with cavity two 316. In specific operation, when the pipe 100 contacts the linkage rod 15 and pushes the pressure-reducing ring 14 to move, the pressure-reducing ring 14 drives the elastic airbag 13 to compress. The gas generated by the compression of the elastic airbag 13 enters the cavity one 315 through the connecting pipe 16. At this time, the gas inside the cavity one 315 is compressed, which drives the piston 313 to move. The piston 313 moves and compresses the gas inside the cavity two 316 to expand. The gas expansion drives the inner support block 35 to move outward, so that the inner support block 35 presses against the pipe 100.

[0049] As the pipe 100 continues to be conveyed forward, the friction will drive the linkage rod 15 and the pressure ring 14 to move synchronously, and the elastic air bag 13 will be continuously compressed, pumping gas into the cavity 1 315. At this time, the air pressure in the cavity 1 315 continues to rise, pushing the piston 313 to move, and the gas inside the cavity 2 316 expands further. However, since the inner support block 35 is blocked by the inner wall of the pipe 100 and cannot continue to extend radially, the air pressure inside the cavity 2 316 will rise rapidly.

[0050] When the internal air pressure of cavity 2 316 reaches the preset maximum critical value of pressure reducing valve 314, pressure reducing valve 314 automatically opens to overflow, and excess gas in cavity 2 316 is discharged outward through pressure reducing valve 314 until the internal air pressure drops below the critical value, after which pressure reducing valve 314 automatically closes. This achieves dynamic balance of internal air pressure in cavity 2 316, and always keeps the radial support force of inner support block 35 stably controlled within the preset threshold. This prevents the inner wall of pipe 100 from denting and deforming due to excessive pressure, and also prevents support slippage and pipe 100 offset due to insufficient pressure. It ensures that during the testing process, pipe 100 always maintains coaxiality with inner laser rangefinder 32 and outer laser rangefinder 34, and the error is always within the preset threshold.

[0051] Repeating the above steps allows for the inspection of the remaining portion of pipe 100, thus completing continuous inspection of the entire length of pipe 100: at intervals, a set of inspection data is collected from the inner laser rangefinder 32 (detecting the relative position of the inner wall) and the outer laser rangefinder 34 (detecting the relative position of the outer wall). The difference between the two sets of data yields the actual wall thickness of pipe 100 at that inspection point. By comparing the wall thickness data of all inspection points with the standard wall thickness value, defects such as wall thickness deviation, local pits, and ellipticity deviation can be accurately identified.

[0052] The guide rod 31 has a transition channel 4 inside. In addition, the guide rod 31 also has an annular groove 41 inside. One end of the transition channel 4 is connected to the annular groove 41. A conical blocking block 42 is provided at the air outlet of the through groove 312. The other end of the transition channel 4 is connected to the through groove 312 and is located between the conical blocking block 42 and the pressure reducing valve 314. A jet groove 43 is provided between two adjacent inner support blocks 35 on the same side of the clearance groove 311 away from the side wall of the fixed frame 1. The jet groove 43 is connected to the annular groove 41.

[0053] A dust collection groove 44 is provided on the inner wall of the clearance groove 311 and between the adjacent inner laser rangefinders 32. The other end of the dust collection groove 44 passes through the inside of the guide rod 31 and leads to the end of the guide rod 31 away from the vertical section of the fixed frame 1.

[0054] When the air pressure in cavity 316 reaches the critical value of pressure reducing valve 314, the excess high-pressure gas is discharged from pressure reducing valve 314 and enters through groove 312. After being blocked by conical block 42, it smoothly enters transition channel 4 and then flows into annular groove 41 to achieve uniform distribution of circumferential air pressure. Finally, it is sprayed into the inner wall of pipe 100 through jet groove 43. The airflow impacts the inner wall of pipe 100 in an inclined direction, blowing away the attached oxide scale, iron filings, dust and other impurities from the inner wall surface.

[0055] After the jet is completed, the impurities blown off the inner wall are suspended in the cavity inside the pipe 100. At this time, the dust collection tank 44, which is connected to the external negative pressure device (not shown), generates negative pressure suction, which sucks all the suspended impurities into the dust collection tank 44. Finally, the impurities are discharged to the outside through the interface at the front end of the guide rod 31, so as to achieve complete collection of impurities, avoid impurities remaining inside the pipe 100 from blocking the detection optical path of the subsequent internal laser rangefinder 32, and prevent impurities from entering the equipment and causing wear on the parts.

[0056] Finally, the present invention also provides an online laser detection method for wall thickness fluctuation of plastic pipes, the method of use of which includes the following steps: S1: move the pipe 100 to be tested onto the support frame 2, push the pipe 100 along the support frame 2, so that the guide rod 31 is inserted into the inside of the pipe 100, and perform preliminary guidance, limiting and pre-straightening of the pipe 100 to ensure that the inner wall of the pipe is straight, in preparation for subsequent testing.

[0057] S2: When the pipe 100 moves to the detection area, the inner support block 35 moves outward and supports the inner wall of the pipe 100, further improving the straightness of the inner wall, avoiding deformation of the pipe 100 that could cause the detection beam to deviate, and ensuring that the synchronization error of the detection data is within the allowable range.

[0058] S3: After the inner support block 35 is stabilized, the inner and outer diameters of the pipe 100 are detected by the cooperation of the inner laser rangefinder 32 and the outer laser rangefinder 34. The difference between the two sets of data is used to obtain the wall thickness of the pipe 100. At the same time, the pressure reducing valve 314 and the piston 313 are used to maintain the stable support of the inner support block 35 on the inner wall.

[0059] S4: When the pipe 100 is continuously conveyed, excess gas is ejected through the jet vent 43 to clean impurities on the inner wall of the pipe 100, and the dust collection vent 44 collects and discharges the impurities; repeat the above actions to continuously collect test data and compare it with the standard value to complete the continuous test of the entire length of the pipe 100.

[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An online laser detection device for wall thickness fluctuation of plastic pipes, characterized in that: The device includes an L-shaped fixed frame (1), the horizontal section of which is provided with an arc-shaped support frame (2) for placing pipes (100), and the vertical section is provided with a guide rod (31) coaxial with the support frame (2). The guide rod (31) has a coaxial relief groove (311), and multiple internal laser rangefinders (32) are evenly arranged on the inner wall of the relief groove (311). The horizontal section of the fixed frame (1) is provided with a ring frame (33) coaxial with the guide rod (31), and the inner side wall of the ring frame (33) is provided with an outer laser rangefinder (34) corresponding to the inner laser rangefinder (32). The guide rod (31) has two sets of symmetrically distributed, circumferentially uniformly arranged inner support blocks (35) on its circumferential surface, which move radially and press against the inner wall of the pipe (100).

2. The online laser detection device for wall thickness fluctuation of plastic pipes according to claim 1, characterized in that: The guide rod (31) has a through groove (312) inside, a piston (313) is slidably provided in the through groove (312), and a pressure reducing valve (314) is provided. The guide rod (31) has a guide groove that corresponds one-to-one with the inner support block (35) and communicates with the through groove (312). The inner support block (35) is slidably disposed in the guide groove, and the guide groove is provided with an elastic element for resetting the inner support block (35).

3. The online laser detection device for wall thickness fluctuation of plastic pipes according to claim 2, characterized in that: The elastic element is a telescopic spring. One end of the telescopic spring is fixed to the inner wall of the guide groove, and the other end is fixed to the corresponding inner support block (35). The inner support block (35) does not collide with the telescopic spring when it moves.

4. The online laser detection device for wall thickness fluctuation of plastic pipes according to claim 1, characterized in that: The inner support block (35) is provided with ball bearings on the end face that contacts the inner wall of the pipe (100) to reduce the friction between the pipe (100) and the inner support block (35) when the pipe (100) moves.

5. The online laser detection device for wall thickness fluctuation of plastic pipes according to claim 1, characterized in that: The support frame (2) extends along the length of the horizontal section of the fixed frame (1), and the part corresponding to the clearance groove (311) is provided with a partition to make way for the measurement of the external laser rangefinder (34).

6. The online laser detection device for wall thickness fluctuation of plastic pipes according to claim 2, characterized in that: The vertical section of the fixed frame (1) is equipped with a horizontal bar (11), and a connecting frame (12) is slidably provided on the horizontal bar (11). An elastic airbag (13) coaxial with the support frame (2) is installed at the bottom of the connecting frame (12). The support frame (2) is slidably provided with a pressing ring (14) for squeezing the elastic airbag (13). The ring frame (33) is provided with an L-shaped linkage rod (15). The horizontal section of the linkage rod (15) is connected to the pressing ring (14), and the vertical section is used to cooperate with the pipe (100).

7. The online laser detection device for wall thickness fluctuation of plastic pipes according to claim 6, characterized in that: The elastic airbag (13) is connected to the air inlet of the through groove (312) through the connecting pipe (16). The elastic airbag (13) can only deform along the length of the horizontal section of the fixed frame (1), and its bottom is provided with a groove for making way for the connecting rod of the support frame (2).

8. The online laser detection device for wall thickness fluctuation of plastic pipes according to claim 2, characterized in that: The guide rod (31) is provided with a transition channel (4) and an annular groove (41) inside. One end of the transition channel (4) is connected to the annular groove (41), and the other end is connected to the part of the through groove (312) located between the pressure reducing valve (314) and the conical blocking block (42). The side wall of the clearance groove (311) away from the fixed frame (1) is provided with an air jet groove (43) that communicates with the annular groove (41).

9. The online laser detection device for wall thickness fluctuation of plastic pipes according to claim 1, characterized in that: The inner wall of the clearance groove (311) is provided with a dust suction groove (44). One end of the dust suction groove (44) is located between adjacent inner laser rangefinders (32), and the other end extends through to the end of the guide rod (31) away from the vertical section of the fixed frame (1) for communication with external negative pressure equipment.

10. A detection method using an online laser detection device for wall thickness fluctuation of plastic pipes as described in any one of claims 1-9, characterized in that: Includes the following steps: S1. Place the pipe (100) to be tested on the support frame (2), push the pipe (100) to move until the guide rod (31) is inserted into the pipe (100) to complete the initial guidance and pre-straightening of the pipe (100); S2. The pipe (100) pushes the linkage rod (15) to drive the pressure ring (14) to squeeze the elastic air bag (13). The gas enters the through groove (312) through the connecting pipe (16) to drive the inner support block (35) to move radially and press against the inner wall of the pipe (100). S3. When the pipe (100) moves to the detection area, the inner laser rangefinder (32) and the outer laser rangefinder (34) simultaneously detect the inner diameter and outer diameter of the pipe (100) and calculate the difference to obtain the wall thickness; the pressure reducing valve (314) maintains the stability of the support force of the inner support block (35), the air jet groove (43) sprays air to remove impurities from the inner wall of the pipe, and the dust suction groove (44) sucks up the impurities; S4. Continuously collect test data and compare it with the standard value to complete the full-length wall thickness fluctuation test of the pipe (100).

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