A laser scanning instrument for measuring the inner diameter of a pipe

Abstract

This invention relates to a laser scanning detector for the inner diameter of a pipe. The detector includes a laser rangefinder, a rotating mechanism, a shaft, a positioning device, and a controller. The laser rangefinder measures the distance between itself and a target object. The rotating mechanism is fixedly connected to the laser rangefinder and drives it to rotate at a predetermined measuring angle. The positioning device is slidably connected to the rotating mechanism, supporting it and ensuring that the rotation axis of the rotating mechanism is always parallel to the central axis of the pipe. The controller processes the signals transmitted by the laser rangefinder and controls the operation of the rotating mechanism. This laser scanning detector for the inner diameter of a pipe, by supporting the rotating mechanism with the positioning device, ensures that the laser emission direction of the laser rangefinder is always parallel to the central axis of the pipe being measured. Furthermore, the controller automatically measures the inner wall of the pipe, improving both the efficiency and accuracy of the inner wall detection.

Description

Technical Field

[0001] This invention relates to the field of pipe inspection equipment technology, and in particular to a laser scanning instrument for detecting the inner diameter of pipes. Background Technology

[0002] Artillery is one of the most common weapons in modern warfare, and the firepower of an army is inextricably linked to the quality of its artillery. Modern artillery research and production have extremely stringent standards and requirements for materials and processes. In particular, the gun barrel, a critical component, requires extensive use of carbon-nickel-chromium-platinum alloy steel. Furthermore, the smelting and processing of gun steel is highly complex, necessitating careful consideration of various technical aspects such as resistance to high temperatures, high pressures, and wear.

[0003] After the gun barrel is manufactured, its performance needs to be tested to ensure that the shells can be fired safely and accurately. Once in use, the high temperature, high speed, and high pressure generated by the shell firing will cause varying degrees of wear on the barrel. Therefore, testing the ovality of the barrel's inner diameter, the degree of wear on the inner wall, and the actual inner diameter of the barrel is particularly important.

[0004] In the pipe body measurement that extends from gun barrel inspection, most measurements focus on the actual inner diameter of the pipe. Existing pipe body inspection devices struggle to achieve accurate measurement of the inner wall of the pipe, and the inspection process is cumbersome and inefficient. Summary of the Invention

[0005] Therefore, it is necessary to provide a laser scanning instrument for detecting the inner diameter of pipes to address the problem of low accuracy in pipe inner diameter scanning detection.

[0006] A laser scanning detector for pipe inner diameter includes a laser rangefinder, a rotating mechanism, a shaft, a positioning device, and a controller.

[0007] A laser rangefinder sensor emits a laser detection signal and measures the distance between itself and the target object by receiving the echo signal scattered by the target object. A rotating mechanism is fixedly connected to the laser rangefinder sensor and drives it to rotate according to a predetermined ranging angle. A positioning device is slidably connected to the rotating mechanism and supports it, ensuring that the rotation axis of the rotating mechanism is always parallel to the central axis of the tube. A controller processes the signals transmitted by the laser rangefinder sensor and controls the operating state of the rotating mechanism. Specifically, the controller is used for:

[0008] a. Obtain the standard inner diameter of the pipe body, and then obtain the corresponding distance measuring angle from a conversion table based on the standard inner diameter. The conversion table represents the mapping relationship between the standard inner diameter and the distance measuring angle.

[0009] b. Based on the ranging angle, the rotating mechanism drives the laser ranging sensor to rotate one revolution, acquiring the distance measured after each ranging angle rotation. The distance is the distance from the laser ranging sensor to the inner wall of the tube in the laser emission direction. Assuming the ranging angle is θ0, the rotating mechanism drives the laser ranging sensor to rotate θ0 each time, detecting a total of 2π / θ0 distance signals.

[0010] c. Obtain the rotation radius of the laser rangefinder. Add the rotation radius to each measured interval to obtain the half-sine of the measurement. Assume the rotation radius is r, and the measured interval is denoted as A. i (i = 1, 2, 3, ..., n), then a half-chord can be represented as:

[0011] C i =a i +r, (i=1,2,3,...,n).

[0012] d. Add the two half-chords measured every 180° to form the chord length, and select the chord with the longest length as the inner diameter of the tube. Chord length B i It can be represented as:

[0013] B i =C i +C i+180 , (i=1,2,3,...,n / 2).

[0014] If the m-th chord is the longest, then B m That is, the diameter, B m Passing through the center of the circle, the virtual diameter D can be represented as:

[0015] D = B m .

[0016] The aforementioned laser scanning detector for pipe inner diameter uses a controller that can convert manual measurement into intelligent automatic measurement. It precisely controls the angle of each rotation, quickly measures and records the distance measured by the laser rangefinder, and calculates the actual inner diameter of the pipe through a set program or processing module to determine whether the wear of the pipe exceeds a preset standard. This not only improves the efficiency of pipe inner wall detection but also improves the accuracy of the detection.

[0017] In one embodiment, the laser rangefinder includes a laser emitter and an optical sensor. The laser emitter emits a laser detection signal. The optical sensor receives the laser echo signal and records the time elapsed from laser emission to laser reception, thereby calculating the distance between the target object and the laser rangefinder based on the angle and duration of the received echo signal.

[0018] In one embodiment, the rotating mechanism includes a stepper motor, a cantilever, and a conductive slip ring. One side of the cantilever is fixedly connected to a laser rangefinder sensor, and the other side is fixedly connected to the output shaft of the stepper motor. This cantilever is used to mount the laser rangefinder sensor onto the stepper motor, ensuring that the laser emission direction of the laser rangefinder sensor is always perpendicular to the rotation axis of the stepper motor. The rotation axis of the stepper motor is set to be parallel to the central axis of the tube, thereby controlling the laser emission direction of the laser rangefinder sensor to always be perpendicular to the central axis of the tube, thus detecting the entire circular cross-section of the tube and reducing detection errors.

[0019] In one embodiment, one end of the conductive slip ring is fixedly connected to the cantilever, and the other end is fixedly connected to the stepper motor. The input end of the conductive slip ring is connected to the laser rangefinder, and the output end is connected to the controller. The conductive slip ring not only transmits the power output from the stepper motor, indirectly controlling the rotation of the laser rangefinder, but also transmits the signal detected by the laser sensor to the controller. By installing the conductive slip ring, the laser rangefinder remains connected to the controller throughout its rotation, maintaining the stability of signal transmission.

[0020] In one embodiment, the shaft is fixedly connected to the stepper motor, and the shaft is parallel to the rotation axis of the stepper motor.

[0021] In one embodiment, the positioning device includes a positioning cylinder, an umbrella-shaped bracket, and a nut. The positioning cylinder is coaxially arranged with and slidably connected to the outside of the shaft to achieve a sliding connection between the positioning device and the rotating mechanism. One end of the umbrella-shaped bracket is rotatably connected to one end of the positioning cylinder, and the other end abuts against the nut. The other end of the positioning cylinder is provided with external threads for screwing the nut in.

[0022] In one embodiment, a spring is placed between the umbrella-shaped bracket and the nut. The spring is coaxially positioned on the outside of the positioning cylinder, with one end abutting against the umbrella-shaped bracket and the other end abutting against the nut. The spring can transform the rigid contact between the nut and the umbrella-shaped bracket into a flexible contact. This avoids direct wear when the nut and the umbrella-shaped bracket abut against each other, and at the same time, it can convert the driving force of the nut into the elastic force of the spring, acting as a buffer between the nut and the umbrella-shaped bracket. This allows the umbrella-shaped bracket to maintain its installation stability while avoiding damage caused by rigid contact, thereby extending the service life of the umbrella-shaped bracket.

[0023] In one embodiment, the umbrella-shaped support includes a slip ring and multiple folding triangular rods. The slip ring is slidably connected to the positioning cylinder and abuts against a spring. The multiple folding triangular rods are alternately arranged in opposite directions and are evenly distributed on the outside of the positioning cylinder. Each folding triangular rod has one end rotatably connected to the slip ring and the other end rotatably connected to the positioning cylinder. The straight lines containing the two ends of each folding triangular rod are always parallel to the central axis of the positioning cylinder. Furthermore, the plane containing each folding triangular rod passes through the central axis of the positioning cylinder.

[0024] In one embodiment, the folding triangular rod includes a long rod and a short rod. The long rod and the short rod are rotatably connected to each other. In half of the folding triangular rods, one end of the long rod is rotatably connected to one end of the positioning cylinder, the other end of the long rod is rotatably connected to one end of the short rod, and the other end of the short rod is rotatably connected to a slip ring. In the other half of the folding triangular rods, one end of the long rod is rotatably connected to a slip ring, the other end of the long rod is rotatably connected to the short rod, and the other end of the short rod is rotatably connected to the positioning cylinder. When the umbrella-shaped bracket opens outward, the multiple folding triangular rods open outward, forming multiple support points equidistant from the central axis of the positioning cylinder. Because the folding triangular rods are alternately arranged in opposite directions, the multiple support points can form two sets of parallel and rotationally symmetrical equilateral polygons, thereby forming two expansion supports on the outside of the positioning cylinder, thus supporting the positioning cylinder to make the positioning cylinder coaxial with the tube body to be tested.

[0025] In one embodiment, the long rod and the short rod are rotatably connected via a pin and a pulley. Each of the long and short rods has a U-shaped end, with the U-shaped end of the short rod positioned outside the U-shaped end of the long rod. The pin is fixedly connected to the U-shaped end of the short rod and rotatably connected to the U-shaped end of the long rod, thus achieving the rotatable connection between the long and short rods. A pulley is rotatably connected to the outside of the pin. The pulley is positioned inside the U-shaped end of the long rod. The central axis of the pulley is perpendicular to the folding triangular rod it is attached to, and the outer diameter of the pulley is greater than the thickness of the U-shaped ends of both the long and short rods. By using the pulley, when the umbrella-shaped bracket retracts inward, the pulley contacts the positioning cylinder first, ensuring that the angle between the long and short rods is always less than 180°, facilitating the opening of the folding triangular rod. When the umbrella-shaped bracket opens outward, the pulley contacts the inner wall of the tube first, preventing wear between the long or short rod and the inner wall of the tube. Furthermore, the pulley can rotate outside the pin, avoiding rigid contact with the inner wall of the tube, reducing its own wear, and extending the service life of the umbrella-shaped bracket.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. This invention uses a controller to convert manual measurement into intelligent automatic measurement, precisely control the angle of each rotation, quickly measure and record the distance measured by the laser rangefinder, and calculate the actual inner diameter of the tube through a set program or processing module to determine whether the wear of the tube exceeds a preset standard. This not only improves the efficiency of tube inner wall detection, but also improves the accuracy of detection.

[0028] 2. This invention uses a positioning device and a shaft to support the stepper motor, ensuring that the rotation axis of the stepper motor is always parallel to the central axis of the tube to be measured. This ensures that the laser emission square of the laser rangefinder is always perpendicular to the central axis of the tube, allowing for the measurement of the complete circumference of the tube cross-section and improving measurement accuracy.

[0029] 3. By setting a conductive slip ring, the present invention can keep the laser rangefinder sensor connected to the controller during the rotation of the laser rangefinder sensor, thus maintaining the stability of signal transmission.

[0030] 4. By setting a spring between the nut and the umbrella bracket, the present invention can avoid direct wear when the nut and the umbrella bracket come into contact, and at the same time, it can convert the driving force of the nut into the elastic force of the spring, which serves as a buffer between the nut and the umbrella bracket. This allows the umbrella bracket to maintain the stability of the installation while avoiding damage caused by rigid contact, thereby extending the service life of the umbrella bracket.

[0031] 5. The present invention uses multiple folding triangular rods arranged alternately in opposite directions, so that the multiple support points of the folding triangular rods form two sets of parallel and rotationally symmetrical equilateral polygon vertices, thereby forming two expansion supports on the outside of the positioning cylinder, thereby supporting the positioning cylinder so that the positioning cylinder is coaxial with the tube body to be tested.

[0032] 6. This invention, by incorporating pulleys on the folding triangular rod, ensures that when the umbrella-shaped bracket retracts inward, the pulleys contact the positioning cylinder, maintaining an angle between the long and short rods that is always less than 180°, facilitating the opening of the folding triangular rod. When the umbrella-shaped bracket opens outward, the pulleys first contact the inner wall of the tube, preventing wear between the long or short rods and the inner wall. Furthermore, the pulleys can rotate outside the pin, avoiding rigid contact with the inner wall of the tube, reducing their own wear, and extending the service life of the umbrella-shaped bracket. Attached Figure Description

[0033] Figure 1 This is a three-dimensional structural diagram of the laser scanning detector for the inner diameter of a tube according to Embodiment 1 of the present invention;

[0034] Figure 2 for Figure 1 Schematic diagram of a laser scanning detector for the inner diameter of a central tube;

[0035] Figure 3 for Figure 1 Three-dimensional structural diagram of the rotating mechanism;

[0036] Figure 4 for Figure 3 A cross-sectional schematic diagram of the rotating mechanism;

[0037] Figure 5 for Figure 1 A three-dimensional structural diagram of the positioning device;

[0038] Figure 6 This is a flowchart of the test method of the tube diameter laser scanning detector according to Embodiment 2 of the present invention;

[0039] Figure 7 for Figure 6 A planar schematic diagram of multiple coordinate points;

[0040] Figure 8 for Figure 6 A graph showing the spacing data collected when the number of measurement points is 800.

[0041] Figure 9 for Figure 6 A schematic diagram of the virtual central angle;

[0042] Figure 10 for Figure 6 A schematic diagram of the central angle of the mid-beam;

[0043] Figure 11 This is a flowchart of the pipe wall wear detection method based on a laser scanning detector according to Embodiment 4 of the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0047] Example 1

[0048] Please see Figure 1 , Figure 2 and Figure 3 , Figure 1 This is a three-dimensional structural diagram of the laser scanning detector for the inner diameter of the tube in this embodiment; Figure 2 for Figure 1 Three-dimensional structural diagram of the rotating mechanism; Figure 3 for Figure 2A cross-sectional schematic diagram of the rotating mechanism. The laser scanning detector for the inner diameter of the tube includes a laser rangefinder 1, a rotating mechanism 2, a shaft 4, a positioning device 3, and a controller 5.

[0049] The laser rangefinder 1 is used to emit a laser detection signal and measure the distance between itself and the target object by receiving the echo signal scattered by the target object. The laser rangefinder 1 includes a laser emitter and an optical sensor. The laser emitter emits the laser detection signal. The optical sensor receives the laser echo signal and records the time elapsed from laser emission to laser reception, and then calculates the distance between the target object and the laser rangefinder 1 based on the angle and duration of the received echo signal.

[0050] The laser rangefinder sensor 1 can be a triangular reflective displacement sensor, such as the ILD1420 sensor, with a detection range of 50mm to 150mm and a repeatability of 4μm. The ILD1420 sensor is suitable for temperatures ranging from -20℃ to 50℃, meeting the detection requirements for pipe diameters from 100mm to 155mm. Triangular reflective displacement sensors offer higher accuracy and faster detection efficiency, effectively improving measurement efficiency while ensuring measurement accuracy.

[0051] Laser rangefinder 1 can also be equipped with an industrial-grade high-precision rangefinder. Compared with the triangular reflective displacement sensor, the industrial-grade high-precision rangefinder has a larger range, but its accuracy is only 1.0 mm, which is suitable for the detection of pipes with larger diameters.

[0052] The rotating mechanism 2 is fixedly connected to the laser rangefinder 1 and is used to drive the laser rangefinder 1 to rotate according to a predetermined ranging angle. During the measurement of the inner diameter of the tube, since it is difficult to directly measure the tube diameter, the detector in this embodiment measures the inner diameter of the tube circumferentially, and then analyzes and calculates the actual size of the inner diameter of the tube based on the multiple measured data. To ensure measurement accuracy, the error between any two consecutive measurement points must not exceed a preset maximum error value. Therefore, the detector in this embodiment uses an equal-angle measurement method to complete the circumferential detection of the tube cross-section. To meet measurement accuracy requirements, the rotating mechanism 2 uses a stepper motor 21 to drive the laser rangefinder 1 to rotate. Specifically, the rotating mechanism 2 includes a stepper motor 21, a cantilever 22, and a conductive slip ring 23.

[0053] One side of the cantilever 22 is fixedly connected to the laser rangefinder 1, and the other side is fixedly connected to the output shaft of the stepper motor 21. The cantilever 22 can be plate-shaped, such as a square or round plate, used to mount the laser rangefinder 1 on the stepper motor 21, ensuring that the laser emission direction of the laser rangefinder 1 is always perpendicular to the rotation axis of the stepper motor 21. The rotation axis of the stepper motor 21 is set to be parallel to the central axis of the tube, thereby controlling the laser emission direction of the laser rangefinder 1 to always be perpendicular to the central axis of the tube, thus detecting the entire circular cross-section of the tube and reducing detection errors. The stepper motor 21 can rotate a fixed angle according to the input control signal, and then calculates the angle of each rotation according to the preset number of measurement points, driving the laser rangefinder 1 to rotate by one ranging angle each time, and measuring the corresponding distance. In this embodiment, the minimum step angle of the stepper motor 21 is 0.45°, which can meet the detection requirements of 800 detection points, thus meeting the detection requirements of tubes with a diameter of 100mm to 155mm. The stepper motor 21 can be a 42BYGH3413B4K type hollow shaft stepper motor 21, with an output shaft outer diameter of 10mm and a front shaft length of 25mm. Of course, in other embodiments, stepper motors 21 with other signals can also be selected, as long as they can meet the measurement requirements of the minimum step angle.

[0054] One end of the conductive slip ring 23 is fixedly connected to the cantilever 22, and the other end is fixedly connected to the stepper motor 21. The input end of the conductive slip ring 23 is connected to the laser rangefinder 1, and the output end is connected to the controller 5. The conductive slip ring 23 not only transmits the power output from the stepper motor 21, indirectly controlling the rotation of the laser rangefinder 1, but also transmits the signal detected by the laser sensor to the controller 5.

[0055] The laser rangefinder 1 requires not only its own power supply but also signal communication with the controller 5. Therefore, in practical applications, the laser rangefinder 1 needs to maintain a continuous connection with the controller 5. If a wire is used for this connection, the wire will rotate with the stepper motor 21, potentially becoming entangled on the output shaft of the stepper motor 21, causing signal interference or even damage to the wire. The conductive slip ring 23, also known as a conductive ring, current collector ring, or current bus ring, uses built-in brushes to ensure that the outer ring is fixedly connected to the stepper motor 21 while the inner shaft rotates, maintaining conductivity between the outer ring and the inner shaft. By using the conductive slip ring 23, the laser rangefinder 1 remains connected to the controller 5 throughout its rotation, maintaining stable signal transmission. A six-channel miniature conductive slip ring 23 can be used, offering high insulation, and the wire length can be customized to meet precise pipe diameter requirements. Of course, in other embodiments, other types of conductive slip rings 23 can also be selected, such as LPM-12U miniature cap-type conductive slip rings, etc.

[0056] Shaft 4 is fixedly connected to stepper motor 21, and shaft 4 is parallel to the rotation axis of stepper motor 21. In practical applications, the detector may need to measure different depths inside the tube separately. Shaft 4 drives the motor to translate, thereby moving the laser rangefinder 1 to the position to be measured inside the tube. Alternatively, multiple different positions inside the tube can be measured to improve the accuracy of the tube's inner diameter measurement. It is important to note that shaft 4 should always remain parallel to the central axis of the tube during the driving process.

[0057] Please combine Figure 4 , it is Figure 1 A three-dimensional structural diagram of the positioning device 3. The positioning device 3 is slidably connected to the rotating mechanism 2, supporting the rotating mechanism 2 and ensuring that the rotation axis of the rotating mechanism 2 is always parallel to the central axis of the tube body. The positioning device 3 includes a positioning cylinder 31, an umbrella-shaped bracket 33, and a nut. The positioning cylinder 31 is coaxially arranged with the shaft 4 and slidably connected to the outside of the shaft 4 to achieve a sliding connection between the positioning device 3 and the rotating mechanism 2. One end of the umbrella-shaped bracket 33 is rotatably connected to one end of the positioning cylinder 31, and the other end abuts against the nut. The other end of the positioning cylinder 31 is provided with external threads for screwing the nut.

[0058] The positioning cylinder 31 is a cylinder with uniform thickness and a smooth surface. The shaft 4 can slide smoothly inside the positioning cylinder 31. The end of the umbrella-shaped bracket 33 that is pressed against the nut can also slide smoothly outside the positioning cylinder 31. When the nut rotates clockwise outside the positioning cylinder 31, it can drive the umbrella-shaped bracket 33 to open outward, thereby fixing the positioning cylinder 31 inside the tube. When the nut rotates counterclockwise, the umbrella-shaped bracket 33 is reset by elastic force, and the positioning device 3 can be removed from the tube.

[0059] To reduce wear during the opening and closing of the umbrella bracket 33, a spring 32 can be installed between the umbrella bracket 33 and the nut. The spring 32 is coaxially positioned on the outside of the positioning cylinder 31, with one end abutting against the umbrella bracket 33 and the other end abutting against the nut. The spring 32 transforms the rigid contact between the nut and the umbrella bracket 33 into a flexible contact. This avoids direct wear when the nut and umbrella bracket 33 abut against each other, and simultaneously converts the driving force of the nut into the elastic force of the spring 32, acting as a buffer between the nut and the umbrella bracket 33. This ensures the umbrella bracket 33 maintains its installation stability while preventing damage caused by rigid contact, thereby extending the service life of the umbrella bracket 33.

[0060] The positioning cylinder 31, nut, spring 32, and umbrella bracket 33 can be made of metal, plastic, or wood. To ensure the accuracy of the detection and reduce wear between the positioning device 3 and the cylinder during the measurement process, this embodiment uses a stainless steel positioning cylinder 31, nut, spring 32, and umbrella bracket 33.

[0061] The umbrella-shaped support 33 includes a conductive slip ring and multiple folding triangular rods. The conductive slip ring is slidably connected to the positioning cylinder 31 and abuts against the spring 32. The multiple folding triangular rods are arranged alternately in opposite directions and are evenly distributed on the outside of the positioning cylinder 31. Each folding triangular rod has one end rotatably connected to the conductive slip ring and the other end rotatably connected to the positioning cylinder 31. The straight lines containing the two ends of each folding triangular rod are always parallel to the central axis of the positioning cylinder 31. Furthermore, the plane containing each folding triangular rod passes through the central axis of the positioning cylinder 31.

[0062] The folding triangular rod includes a long rod 332 and a short rod 331. The long rod 332 and the short rod 331 are rotatably connected to each other. In half of the folding triangular rods, one end of the long rod 332 is rotatably connected to one end of the positioning cylinder 31, and the other end of the long rod 332 is rotatably connected to one end of the short rod 331. The other end of the short rod 331 is rotatably connected to the conductive slip ring. In the other half of the folding triangular rods, one end of the long rod 332 is rotatably connected to the conductive slip ring, and the other end of the long rod 332 is rotatably connected to the short rod 331. The other end of the short rod 331 is rotatably connected to the positioning cylinder 31. When the umbrella-shaped bracket 33 opens outward, multiple folding triangular rods open outward, forming multiple support points equidistant from the central axis of the positioning cylinder 31. Because the folding triangular rods are alternately arranged in opposite directions, the multiple support points can form two sets of parallel and rotationally symmetrical equilateral polygons, thereby forming two expansion supports on the outside of the positioning cylinder 31, thus supporting the positioning cylinder 31 so that the positioning cylinder 31 is coaxial with the tube body to be tested. When the umbrella-shaped bracket 33 is folded inward, the connection between the long rod 332 and the short rod 331 moves closer to the outer wall of the positioning cylinder 31 and maintains a preset distance gap with the positioning cylinder 31 to avoid the long rod 332 and the short rod 331 being on the same straight line, so as to facilitate the folding triangular rod to open outward.

[0063] The long rod 332 and the short rod 331 are rotatably connected via a pin 334 and a pulley 333. Specifically, each of the long rod 332 and the short rod 331 has a U-shaped end, with the U-shaped end of the short rod 331 positioned outside the U-shaped end of the long rod 332. The pin 334 is fixedly connected to the U-shaped end of the short rod 331 and rotatably connected to the U-shaped end of the long rod 332, thus achieving the rotatable connection between the long rod 332 and the short rod 331. To prevent wear between the long rod 332 or the short rod 331 and the inner wall of the tube when the folding triangular rod is opened outward, a pulley 333 is rotatably connected to the outside of the pin 334. The pulley 333 is positioned inside the U-shaped end of the long rod 332. The central axis of the pulley 333 is perpendicular to the folding triangular rod it is attached to, and the outer diameter of the pulley 333 is greater than the thickness of the U-shaped ends of the long rod 332 and the short rod 331. By setting pulley 333, when the umbrella-shaped bracket 33 retracts inward, pulley 333 first contacts the positioning cylinder 31, ensuring that the angle between the long rod 332 and the short rod 331 is always less than 180°, facilitating the opening of the folding triangular rod. When the umbrella-shaped bracket 33 opens outward, pulley 333 first contacts the inner wall of the tube, preventing wear between the long rod 332 or the short rod 331 and the inner wall of the tube. Furthermore, pulley 333 can rotate outside the pin 334, avoiding rigid contact with the inner wall of the tube, reducing its own wear, and extending the service life of the umbrella-shaped bracket 33.

[0064] By installing the positioning device 3, the shaft 4 can slide stably inside the positioning cylinder 31. Thus, when the driving rotating mechanism 2 is translated, the rotation axis of the shaft 4 and the rotating mechanism 2 is always parallel to the central axis of the tube, so that the laser emission direction of the laser range sensor 1 is always perpendicular to the central axis of the tube, thereby improving the accuracy of the tube's inner diameter measurement.

[0065] Controller 5 processes the signals transmitted by laser rangefinder 1 and controls the operating state of rotating mechanism 2. Specifically, controller 5 is used for:

[0066] a. Obtain the standard inner diameter of the pipe body, and then obtain the corresponding distance measuring angle from a conversion table based on the standard inner diameter. The conversion table represents the mapping relationship between the standard inner diameter and the distance measuring angle.

[0067] The tube body is generally designed with a standard diameter during manufacturing, which is the ideal diameter for the tube body. Based on the rotation radius of the laser rangefinder 1, the ranging angle corresponding to measuring tube bodies of different diameters can be calculated, thereby improving detection efficiency while ensuring measurement accuracy.

[0068] b. Based on the ranging angle, control the rotation mechanism 2 to drive the laser ranging sensor 1 to rotate one revolution, and obtain the distance measured after each ranging angle rotation of the laser ranging sensor 1. The distance is the distance from the laser ranging sensor 1 to the inner wall of the tube in the laser emission direction.

[0069] Assuming the ranging angle is θ0, the rotating mechanism 2 drives the laser ranging sensor 1 to rotate by θ0 each time, detecting a total of 2π / θ0 distance signals.

[0070] c. Obtain the rotation radius of laser rangefinder 1. Add the rotation radius to each measured interval to obtain the half-chord of the measurement.

[0071] Assuming the radius of rotation is r, the measured distance is denoted as A. i (i = 1, 2, 3, ..., n), then a half-chord can be represented as:

[0072] C i =A i +r, (i=1,2,3,...,n).

[0073] d. Add the two half-chords measured every 180° to form the chord, and select the chord with the longest length as the inner diameter of the tube.

[0074] chord length B i It can be represented as:

[0075] B i =C i +C i+180 .

[0076] As defined by diameter, the longest line connecting the two endpoints of a circle is the diameter, which also passes through the center of the circle. In this embodiment, the number of measurement points is recorded as 800, so the angle of each motor rotation is 360° / 800 = 0.45°. The detector obtains a distance between itself and the inner wall of the tube for every 0.45° rotation within the tube, denoted as {A}. n}(n=0, 1, 2, 3, …, 799). The corresponding chord length is denoted as {B}. n}(n=0,1,2,…,399). If the m-th chord is the longest among the 400 chords, then B m That is, the diameter, B m Passing through the center of the circle, the virtual diameter D can be represented as:

[0077] D = B m .

[0078] When manually measuring the inner wall of a pipe, it's necessary to control the motor to run at a fixed angle each time, record the data detected by the laser rangefinder 1 in real time, and determine whether there is severe wear on the inner wall of the pipe based on a large amount of data. This not only makes it difficult to control the measurement accuracy but also results in a relatively large amount of operation and calculation, leading to low detection efficiency. The controller 5 can convert manual measurement into intelligent automatic measurement, precisely control the angle of rotation each time, quickly measure and record the distance measured by the laser rangefinder 1, and calculate the actual inner diameter of the pipe through a set program or processing module to determine whether the wear of the pipe exceeds a preset standard. This not only improves the efficiency of pipe inner wall detection but also enhances the accuracy of the detection.

[0079] Based on the application of controller 5 in actual measurement, this embodiment also provides a laser scanning detection system for the inner diameter of a pipe. The laser scanning detection system includes: an acquisition module, a signal control module, and a calculation module.

[0080] The signal acquisition module is used to acquire the rotation radius of the detector and the distance signal of each measurement. The rotation radius of the detector can be directly obtained from the detector's specifications and can be directly input by the inspector.

[0081] The calculation module is used to calculate the actual inner diameter of the pipe cross-section based on the acquired multiple spacing signals, and at the same time calculate the change in inner diameter based on the spacing signals, and input the actual inner diameter information and the change information into the signal control module respectively.

[0082] The judgment module is used to determine whether the inner wall of the pipe meets the standard based on the actual inner diameter of the pipe and the amount of change in the inner diameter, and outputs a qualified signal or an unqualified signal to the signal control module according to the judgment result.

[0083] The signal control module receives the spacing signal measured by the detector each time, and outputs a rotation angle signal after receiving each spacing signal, thereby controlling the detector to rotate by a preset angle. The signal control module is also used to output a detection completion signal after the detector has rotated one full revolution.

[0084] Example 2

[0085] Before the laser scanning detector for pipe inner diameter in Example 2 is put into use, its performance needs to be tested to determine the minimum number of measurement points required for measuring the inner diameter of pipes with different diameters. Based on the method for detecting wear on the inner wall of pipes in Example 1, this example provides a testing method for a laser scanning detector for pipe inner diameter.

[0086] Please see Figure 1 This is a flowchart of the method for detecting the wear condition of the inner wall of the pipe in this embodiment. The method for detecting the wear condition of the inner wall of the pipe includes the following steps:

[0087] S1: Calculate the minimum number of measurement points required to cover the entire inner circumference of the pipe based on the pipe diameter and the laser beam diameter of the scanning detector. Calculate the scanner's ranging angle based on the minimum number of measurement points, and measure the distance from the scanner itself to the inner wall of the pipe for each ranging angle rotation.

[0088] During manufacturing, pipe bodies are typically designed with a standard caliber, representing the ideal caliber for pipe production. However, in actual production, caliber errors due to manufacturing precision are unavoidable. Therefore, after pipe body manufacturing, the inspection of the finished product is crucial. Taking a gun barrel as an example, the gun barrel guides the projectile. Besides requiring sufficient rigidity to support the projectile's launch, it also has strict requirements for its inner diameter and rifling. Therefore, the inner wall of the gun barrel must be precisely inspected after production. A laser scanning inspection instrument can perform a circumferential scan of the pipe's inner wall to obtain multiple inner diameter data points, which can then be used to determine whether the inner diameter meets the standard. Furthermore, after the gun barrel is put into use, to ensure the safety and stability of projectile launch, the wear condition of the inner diameter needs to be precisely inspected to ensure that the projectile can be launched along the predetermined trajectory.

[0089] To ensure measurement accuracy, simplify the measurement process, and improve efficiency, the laser scanning detector first needs to be tested to determine the number of points the scanner should measure under different aperture conditions. During the initial testing phase, to guarantee measurement accuracy, the maximum ranging angle required for the scanner to rotate and cover the entire inner diameter needs to be calculated.

[0090] Assume the standard diameter of the pipe is D. s The beam diameter is L, and the distance between the scanner's rotation axis and the central axis of the tube is no greater than d. s The maximum ranging angle covering the entire inner diameter is the minimum central angle corresponding to the beam diameter, and the maximum ranging angle θ is... h Expressed as:

[0091] θ h =arccos[2(D s +d s ) 2 -L 2 ] / 2D s d s .

[0092] In actual testing, to facilitate the measurement of the pipe's inner diameter, the number of measurement points is set to an even number. Therefore, the actual number of measurement points is:

[0093] N h ≥2π / θ h .

[0094] The actual ranging angle is:

[0095] θ f =2π / N h .

[0096] S2: Obtain the rotation radius of the laser scanning detector. Based on the rotation radius, map the collected intervals one by one into a planar coordinate system to obtain multiple coordinate points. Fit these coordinate points to a circle, and obtain the center of the circle as the virtual center. The distance from each coordinate point to the origin is equal to the sum of the corresponding interval and the rotation radius. The angle formed by the direction from the origin to each coordinate point and the positive direction of the horizontal axis is equal to the corresponding angular offset. The angular offset is the angle between the laser scanning detector and its initial position.

[0097] The specific method for obtaining the virtual center is as follows:

[0098] S21: Obtain the distance between the laser emission point and the rotation axis of the detector as the rotation radius. Add the rotation radius to each measured interval to form a virtual half-chord.

[0099] Assuming the radius of rotation is r, and the n intervals of the measurement are denoted as dataset A. i (i = 1, 2, 3, ..., n). The corresponding virtual half-chord can then be denoted as C. i (i=1, 2, 3,...,n), and

[0100] C i =A i +r.

[0101] S22: Map the virtual radius one by one to form multiple coordinate points in the plane coordinate system. The distance from the coordinate point to the origin is equal to the length of the virtual radius, and the angle between the direction from the origin to the coordinate point and the positive direction of the horizontal axis is equal to the corresponding angular offset.

[0102] Please refer to the diagram. Let the origin be the rotation center of the detector, denoted as O2. The solid circle in the diagram represents the circle fitted by multiple coordinate points, with the virtual center denoted as O1. The dashed circle represents the scanning path of the detector. Assuming the initial distance measurement coordinates of the detector are P0, the distance from O2 to any coordinate point P is the virtual half-chord, and ∠P0O2P is the angular offset.

[0103] S23: Using the origin as the center, connect two coordinate points every 180° to form a line segment, which is a virtual chord. Calculate the length of each virtual chord. Then the chord length B is... i Represented as:

[0104] B i =C i +C i+180 .

[0105] S24: Select the chord with the longest length as the virtual diameter, then the midpoint of the virtual diameter is the virtual center.

[0106] As defined by diameter, the longest line connecting the two endpoints of a circle is the diameter, which also passes through the center of the circle. In this embodiment, the number of measurement points is recorded as 800, so the angle of each motor rotation is 360° / 800 = 0.45°. The detector obtains a distance between itself and the inner wall of the tube for every 0.45° rotation within the tube, denoted as {A}. n}(n=0, 1, 2, 3, ..., 799). The corresponding chord length is denoted as {B}. n}(n=0,1,2,...,399). If the m-th chord is the longest among the 400 chords, then B m That is, the diameter, B m The circle passes through the center, and its midpoint is the virtual center O1. Then the virtual diameter D and the maximum virtual radius R are expressed as:

[0107] D = B m ,

[0108] R = D / 2.

[0109] S3: Calculate the virtual radius of the gun barrel using the law of cosines based on the coordinate values ​​of each coordinate point.

[0110] S31: When the coordinate point is exactly on the virtual diameter, directly calculate the distance between the two coordinate points and take half of it as the virtual radius.

[0111] Please refer to the diagram; it is [B]. m The chord is defined as the virtual diameter D0, the two endpoints of the diameter are denoted as K and K', the angle between the direction from the origin to any coordinate point P and the virtual diameter is denoted as the initial position rotation angle θ, and the angle between the direction from the virtual center to the coordinate point P and the virtual diameter is denoted as the virtual central angle β.

[0112] When coordinate point P lies exactly on the virtual diameter, the virtual radius O1P is exactly half of the virtual diameter, denoted as:

[0113] O1P=(H K +H K+N ) / 2.

[0114] S32: When the coordinate point is not on the virtual diameter, the distance from the virtual center to the coordinate point is calculated using the cosine theorem and used as the virtual radius.

[0115] When the coordinate point P is not on the virtual diameter, if 0° < θ < 180°, then in ΔO1O2P, according to the Law of Cosines, we know that:

[0116]

[0117] Given that R is the largest virtual half-chord, then

[0118] O1O2 = RH k =(H k +H k+n ) / 2-H k .

[0119] The virtual radius can then be expressed as:

[0120]

[0121] Among them, H K H is the distance from O2 to K. K+N H is the distance from O2 to K'. P Let θ be the distance from O2 to P, and θ be the angle between O2P and O2K.

[0122] If 180° < θ < 360°, and the laser beam strikes the inner wall of the tube at point P', then in ΔO1O2P',

[0123] According to the Law of Cosines:

[0124]

[0125] After sorting, we get:

[0126]

[0127] Since cosπ = -1, therefore

[0128] cos(π-θ)=cos(θ-π)=-cos(θ)

[0129] Therefore, within the entire circumference of the measured cross section, the general formula for calculating the theoretical radius of any coordinate point P from the virtual center is as follows:

[0130]

[0131] S4: Based on the virtual radius, use the sine theorem to calculate the angle between the direction from the origin to each coordinate point and the positive direction of the vertical axis as the corresponding virtual central angle.

[0132] To obtain the profile of the cross-section and understand the wear distribution of the tested section of the barrel, it is necessary to further solve for the virtual central angle corresponding to each data point and the virtual center.

[0133] The specific method for calculating the virtual central angle is as follows:

[0134] S41: When the coordinate point is exactly located on the virtual diameter, the angle between the direction from the origin to the coordinate point and the diameter is 0° or 180°, and the central angle of the coordinate point is also 0° or 180°.

[0135] S42: When the coordinate point is not on the virtual diameter, the central angle is calculated using the sine theorem.

[0136] If 0° < θ < 180°, then in ΔO1O2P, by the Law of Sines, we can obtain:

[0137]

[0138] Right now

[0139]

[0140] After sorting, we get:

[0141]

[0142] If 180° < θ < 360°, and the laser beam strikes the inner wall of the tube at point P', then in △O1O2P', according to the law of sines:

[0143]

[0144] Right now

[0145]

[0146] After sorting, we get:

[0147]

[0148] After summarizing the above virtual central angle β, we can obtain:

[0149]

[0150] S5: Calculate the actual number of measurement points based on the virtual radius and the laser divergence angle of the laser scanning detector, and then calculate the actual rotation angle of the stepper motor for each measurement based on the actual number of measurement points.

[0151] S51: Obtain the diameter of the laser beam emitted by the laser displacement sensor.

[0152] S52: Take the laser beam diameter as the beam chord and calculate the central angle of the beam chord in the circle as the beam central angle.

[0153] Because the rotation axis of the detector may not be collinear with the central axis of the tube during the measurement process, although the diameter of the laser beam remains constant and the arcs covered on the measured cross-section of the tube are approximately equal, the distance between the two measurement points formed by the laser on the inner wall of the tube will still be different in two adjacent measurements. Therefore, in order to ensure that the laser points completely cover the measured cross-section of the tube, it is necessary to first measure the minimum central angle corresponding to the arcs covered by all laser points.

[0154] Assume the laser beam diameter is L, the distance from the laser displacement sensor to the measurement point is s, the rotation radius of the laser displacement sensor is r, and the arc covered by the laser beam on the measured cross section is AB. Since L approximates a point, △AOB can be considered as an isosceles triangle with corresponding leg lengths as follows:

[0155] OA=OB≈s+r

[0156] By the Law of Cosines, in a triangle with side lengths a, b, and c, if the angle opposite to c is C, then:

[0157] cosC=(a 2 +b 2 -c 2 ) / 2ab

[0158] In triangle AOB, ∠AOB is the central angle θ of the light beam. l , can be expressed as:

[0159] θ l =arccos(((s+r) 2 +(s+r) 2 -L 2 ) / 2(s+r).

[0160] S53: The theoretical number of measurement points is calculated based on the beam center angle to determine the number of measurement points required for the laser displacement sensor to cover the entire radial direction of the rocket launcher barrel opening.

[0161] The measuring range of the detector should cover the entire cross-section being measured; therefore, the theoretical number of measurement points N0 can be expressed as:

[0162] N0≥2π / min(θ l )

[0163] Wherein, min(θ) l ) is the minimum value among all beam central angles.

[0164] In this embodiment, the diameter of the measured circular cross-section is 120mm, the beam diameter L is 0.17mm, and the measurement spacing s ranges from 40mm to 60mm. Since the measured circular cross-section is within the sensor's measurement range, we can obtain:

[0165] 50mm≤s+r≤70mm

[0166] Correspondingly,

[0167] θ l ∈(0.0025,0.0034)

[0168] but

[0169] N0≥2π / min(θ l )≈2520

[0170] Therefore, for a 120mm diameter pipe, theoretically, at least 2520 data points need to be detected at equal angles to achieve full coverage measurement.

[0171] Within the measuring range of the instrument, the theoretical number of measurement points was calculated for multiple pipes of different diameters, and the correspondence between the pipe diameter and the number of measurement points is shown in Table 1.

[0172] Table 1. Correspondence between theoretical pipe diameter and number of measurement points

[0173]

[0174]

[0175] S54: Set the maximum error distance between any two adjacent detection points. Calculate the number of measurement points required for the laser scanning detector to measure the radial direction of the complete gun barrel based on the maximum error distance. Then, use the ratio of the circumferential angle to the actual number of measurement points as the actual rotation angle.

[0176] In actual measurements, the more measurement points there are, the longer the total measurement time will be, given a fixed detection time per point. To achieve a balance between scanning cycle and detection accuracy, the phase of laser irradiation on the inner wall of the tube during actual measurements needs to be considered.

[0177] If a maximum error distance δ is set between two adjacent points, then the actual rotation angle θ0 can be expressed as:

[0178] θ0 = 2π / N1, N1 ≥ 2π / (θ l +θ δ )

[0179] θ δ =arccos(((s+r) 2 +(s+r) 2 -δ 2 ) / 2(s+r)

[0180] Where N1 is the actual number of measurement points, δ is the maximum error distance, and θ δ This is the central angle corresponding to the maximum error distance.

[0181] During the barrel inspection process, even very small cracks can block reflected light and cause errors in the data. Therefore, δ = 0.5 mm is set, and the corresponding relationship between the barrel diameter and the number of measurement points is shown in Table 2:

[0182] Table 2 Correspondence between Actual Pipe Diameter and Number of Measurement Points

[0183]

[0184] Considering the accuracy of motor rotation angle in actual measurements, and to improve the detection efficiency of the barrel inner wall while ensuring detection accuracy, 800 points can be selected as the actual measurement points for barrel diameters between 100mm and 155mm. Accordingly, the selected stepper motor should achieve a minimum step angle of 0.45° to achieve a measurement accuracy of 800 steps per revolution.

[0185] Example 3

[0186] To detect the wear condition of the inner wall of a pipe, or to perform a comprehensive scan of the inner wall of the pipe, this embodiment further provides a pipe wall wear detection device based on a laser scanning detector.

[0187] Based on the tube diameter laser scanning detector in Example 1, this example provides a tube wall wear detection device based on the laser scanning detector.

[0188] Unlike Embodiment 1, the tube inner diameter laser scanning detector not only needs to monitor the entire circular cross-section of the inner wall of the tube by rotating one revolution, but also needs to translate within the tube according to a preset translation amount. Therefore, a translation mechanism is added to the tube inner diameter laser scanning detector. Specifically, the tube inner diameter laser scanning detector includes a laser rangefinder, a rotation mechanism, a translation mechanism shaft, and a positioning device. More specifically, an electric cylinder is fixedly connected to the end of the shaft away from the stepper motor, thereby driving the stepper motor to translate multiple times within the tube to be measured according to the preset translation amount.

[0189] Example 4

[0190] Based on the pipe wall wear detection device based on a laser scanning detector in Example 3, this example provides a pipe wall wear detection method based on a laser scanning detector.

[0191] The pipe wall wear detection method based on a laser scanning inspection instrument includes the following steps:

[0192] S1: The detector moves within the tube to be tested according to a preset translation amount. After each translation, the detector rotates one full revolution according to a preset measuring angle. Each time the detector rotates one measuring angle, it measures the distance between itself and the inner wall of the tube.

[0193] Theoretically, pipe wall wear detection should cover the entire inner surface of the pipe wall. However, in practice, due to the maximum allowable error in the pipe wall inner diameter measurement standard, interval measurements can be used to measure partial points on the pipe wall instead of full coverage measurements. This simplifies the detection process and improves the efficiency of pipe wall inspection while ensuring accuracy.

[0194] Based on the diameter and depth of the pipe to be tested, and by introducing the maximum error value, the actual number of points required for the detector during the actual testing process can be calculated. To simplify the testing steps, this embodiment adopts a step-by-step rotation measurement method for accurate testing of the inner wall of the pipe. Based on the laser beam diameter and depth error of the detector, the number of translations required for the detector to measure the entire inner wall of the pipe is calculated, and the displacement of each translation is then calculated. The detector translates sequentially according to the displacement, and after each translation, measures the entire circular cross-section of the inner wall of the pipe. Based on the beam diameter and the distance error between measurement points, the number of measurement points required for the detector to measure the entire circular cross-section of the pipe is calculated, and the measuring angle of each rotation of the detector is then calculated. The detector rotates one revolution after each translation according to the measuring angle, and after each rotation, the distance between itself and the inner wall of the pipe is collected, thus obtaining multiple distance data.

[0195] S2: Calculate the actual inner diameter of the detector at its current position based on the multiple spacing data collected by the detector for each rotation and the rotation radius of the detector.

[0196] The actual inner diameter is obtained as follows:

[0197] S21: Obtain the rotation radius of the detector and superimpose the rotation radius and spacing data to form a virtual half-chord.

[0198] During the rotation of the detector, since the laser emission point of the laser rangefinder sensor and the rotation axis of the detector may not be on the same straight line, it is necessary to first obtain the distance between the laser emission point and the rotation axis as the rotation radius. The rotation radius can generally be obtained directly from the detector's model information, or it can be obtained through actual measurement. The sum of the measured distance data and the rotation radius is considered as the actual distance from the rotation center to the inner wall of the tube. Mapping all the distance data at the current position to a plane coordinate system yields multiple data points. The distance from each data point to the origin is equal to the actual distance from the rotation center to the inner wall of the tube, which can be considered as a virtual half-chord. The angle formed by the straight line connecting each data point to the origin and the positive direction of the horizontal axis is the angle between the laser emission direction and the initial laser direction when measuring that distance, i.e., the angular offset.

[0199] S22: The two virtual half-strings measured at 180° intervals are superimposed to form a virtual string.

[0200] If we construct a virtual circle that just covers all the coordinate points in a plane coordinate system, then any two virtual half-chords spaced 180° apart are full chords passing through the origin, denoted as virtual chords.

[0201] S23: Select the virtual string with the longest length as the actual inner diameter.

[0202] As defined by the circle, the diameter of the chord passing through any point inside the circle is the longest. Therefore, among the multiple virtual chords obtained, the one with the longest length can be regarded as the actual inner diameter at the corresponding position on the inner wall of the tube.

[0203] S3: Determine whether the actual inner diameter exceeds a preset inner diameter range. If yes, output an unqualified signal; otherwise, proceed to S4.

[0204] Due to limitations in existing processes and considering the practical applications of the pipe, there may be a certain error between the actual inner diameter and the standard inner diameter of the pipe. The actual inner diameter of the pipe is judged based on its rated standard inner diameter range. Pipes exceeding the standard inner diameter range are considered unqualified.

[0205] S4: Calculate the virtual inner diameter corresponding to each spacing data based on the spacing data, and then calculate the rate of change of the virtual inner diameter.

[0206] At any translational position, in addition to the measured actual inner diameter, the pipe may also have a certain degree of ellipticity or protrusions. Therefore, besides determining whether the pipe's inner diameter exceeds the standard range, it is also necessary to assess the smoothness of the pipe's inner diameter. If there are protrusions or depressions on the inner wall of the pipe that exceed the specifications, a significant difference will be formed between two consecutive test points.

[0207] The method for calculating the rate of change of the virtual inner diameter is as follows:

[0208] S41: Calculate the difference between each virtual inner diameter and the previous virtual inner diameter.

[0209] S42: Calculate the rate of change based on the difference and the actual inner diameter.

[0210] Then the rate of change is v i1 Represented as:

[0211] v i =δ i / D, (i=2, 3, 4,..., n

[0212] Where, δ i Let be the difference between the i-th virtual inner diameter and the (i-1)-th virtual inner diameter, D be the actual inner diameter, and n be the number of rotations of the measuring instrument in one revolution.

[0213] S5: Determine if the rate of change exceeds a preset threshold range. If yes, output an unqualified signal. Otherwise, continue to determine if the measurement is complete. If the measurement is complete, proceed to S6. Otherwise, return to S1.

[0214] If the rate of change exceeds the preset threshold range, it indicates that there are protrusions or depressions on the inner wall of the barrel. After the barrel is put into use, due to the irreversible wear caused to the barrel wall by shell firing, a comprehensive inspection of the inner wall of the barrel is required after each use to avoid accidents and ensure the safe and accurate firing of shells.

[0215] The method for determining whether the measurement has been completed is as follows:

[0216] S51: Record the number of translations each time the detector moves.

[0217] S52: Calculate the total number of translations based on the preset translation amount and total measurement distance.

[0218] S53: Determine if the total number of translations has been reached. If yes, output "Measurement complete". Otherwise, output "Measurement incomplete".

[0219] The detector needs to be moved from one end of the pipe to the other for precise inspection of the inner wall. During this process, the detector moves at equal intervals multiple times to improve accuracy. After all the data has been measured, further processing is required; therefore, the inspection process can be confirmed as complete beforehand.

[0220] S6: Calculate the rate of change of the actual inner diameter (2) based on the actual inner diameter at each location. Determine if the rate of change (2) exceeds a preset threshold range (2). If so, output an unqualified signal. Otherwise, proceed to S7.

[0221] In pipeline measurement, in addition to determining whether the circumferential inner diameter at each location exceeds the standard inner diameter range, it is also necessary to determine whether the axial inner diameter variation of the pipe's inner wall exceeds the standard inner diameter range. To simplify the judgment process, the changes in multiple actual inner diameters are judged first, and then the virtual diameters with different angular offsets are judged.

[0222] The calculation method for the rate of change 2 is as follows:

[0223] S61: Calculate the difference between each actual inner diameter and the previous inner diameter.

[0224] S62: Calculate the rate of change two based on the difference and the standard inner diameter.

[0225] Then the rate of change is v j1 Represented as:

[0226] v j =δ j / D0, (j = 2, 3, 4, ..., m)

[0227] Where, δ j Let D0 be the difference between the j-th actual inner diameter and the (j-1)-th actual inner diameter, where D0 is the standard inner diameter and m is the total number of translations.

[0228] S7: Calculate the rate of change of the virtual radius at each angular offset based on the virtual radius at each location with the same angular offset. Determine if the rate of change exceeds a preset threshold. If yes, output a non-compliant signal; otherwise, output a compliant signal. Here, the angular offset is the angle between the detector's laser emission direction and the initial laser emission direction.

[0229] The calculation method for the rate of change 3 is as follows:

[0230] S71: Divide the intervals of the same angular offset measurements into the same set.

[0231] S72: Calculate the difference between each virtual inner diameter in each set and the virtual inner diameter at the previous position.

[0232] S73: Calculate the rate of change based on the difference and the standard inner diameter.

[0233] The rate of change is expressed as:

[0234] v kl =δ kl / D0, (k = 2, 3, 4, ..., n), (l = 2, 3, 4, ..., m)

[0235] Where, δ kl It is the difference between the virtual inner diameter of the detector after rotating k times at the first position and the virtual inner diameter after rotating k times at the (l-1)th position.

[0236] This embodiment collects multiple spacing data points along the circumferential and axial directions of the inner wall of the pipe, calculates the rate of change of the inner diameter of the pipe at each detection location, determines whether the inner diameter of the pipe is within the range of the standard inner diameter, and thus determines whether the inner wall of the pipe is qualified. This embodiment comprehensively considers the accuracy and efficiency of the inner wall detection, introduces the error range of the standard inner diameter, and maintains the measurement accuracy of the inner wall of the pipe with the fewest possible measurements.

[0237] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0238] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A laser scanning instrument for detecting the inner diameter of a pipe, characterized in that, It includes: A laser rangefinder is used to emit a laser detection signal and measure the distance between itself and the target object by receiving the echo signal scattered by the target object. A rotating mechanism, which is fixedly connected to the laser rangefinder, is used to drive the laser rangefinder to rotate; A positioning device, slidably connected to the rotating mechanism, is used to support the rotating mechanism and ensure that the rotation axis of the rotating mechanism is always parallel to the central axis of the tube; and Controller, which is used for: a. Obtain the standard inner diameter of the tube body, and obtain the corresponding ranging angle from the standard inner diameter using a conversion table; wherein, the conversion table is used to characterize the mapping relationship between the standard inner diameter and the ranging angle; b. Control the rotation mechanism to drive the laser ranging sensor to rotate one revolution according to the ranging angle; obtain the distance measured by the laser ranging sensor after each ranging angle rotation; the distance is the distance from the laser ranging sensor to the inner wall of the tube body in the laser emission direction; c. Obtain the rotation radius of the laser ranging sensor; add the rotation radius to each measured distance to obtain a half-chord; d. Add the two half-chords measured every 180° to obtain a chord; select the chord with the longest length as the inner diameter of the tube body; The method for determining the ranging angle includes the following steps: S1: Calculate the minimum number of measurement points required to cover the entire inner wall of the pipe based on the pipe diameter and the laser beam diameter of the scanning detector; calculate the ranging angle of the scanner based on the minimum number of measurement points; measure the distance from the scanner itself to the inner wall of the pipe each time the scanner rotates by a ranging angle. S2: Obtain the rotation radius of the laser scanning detector, and map the collected multiple spacings one by one into a plane coordinate system according to the rotation radius to obtain multiple coordinate points; fit the multiple coordinate points into a circle, and obtain the center of the circle as the virtual center; wherein, the distance from each coordinate point to the origin is equal to the sum of the corresponding spacing and the rotation radius; the angle formed by the direction from the origin to each coordinate point and the positive direction of the horizontal axis is equal to the corresponding angular offset; S3: Calculate the virtual radius of the tube using the law of cosines based on the coordinate values ​​of each coordinate point; S4: Based on the virtual radius, use the sine theorem to calculate the angle between the direction from the origin to each coordinate point and the positive direction of the vertical axis as the corresponding virtual central angle; S5: Calculate the actual number of measurement points based on the virtual radius and the laser beam diameter of the laser scanning detector; then calculate the ranging angle for each measurement based on the actual number of measurement points.

2. The laser scanning detector for pipe inner diameter according to claim 1, characterized in that, The laser ranging sensor includes a laser emitter and an optical sensor; the laser emitter is used to emit a laser detection signal; the optical sensor is used to receive the laser echo signal scattered by the target object and record the time elapsed from emitting the laser to receiving the laser.

3. The laser scanning detector for pipe inner diameter according to claim 2, characterized in that, The rotating mechanism includes a stepper motor and a cantilever; one side of the cantilever is fixedly connected to the laser rangefinder; the other side of the cantilever is fixedly connected to the output shaft of the stepper motor; the laser emission direction of the laser rangefinder is perpendicular to the central axis of the stepper motor.

4. The laser scanning detector for pipe inner diameter according to claim 3, characterized in that, The rotating mechanism also includes a conductive slip ring; the conductive slip ring is fixedly connected between the stepper motor and the cantilever; the input end of the conductive slip ring is connected to the laser rangefinder; the output end of the conductive slip ring is connected to the controller; the conductive slip ring is used to transmit the power output by the stepper motor to the cantilever and transmit the distance signal detected by the laser rangefinder to the controller.

5. The laser scanning detector for pipe inner diameter according to claim 3, characterized in that, The detector also includes a shaft; the shaft is fixedly connected to the stepper motor, and the shaft is parallel to the rotation axis of the stepper motor.

6. The laser scanning detector for pipe inner diameter according to claim 5, characterized in that, The positioning device includes a positioning cylinder, an umbrella-shaped bracket, and a nut; the positioning cylinder is coaxial with the shaft and slidably connected to the outside of the shaft; one end of the umbrella-shaped bracket is rotatably connected to one end of the positioning cylinder; the other end of the umbrella-shaped bracket abuts against the nut; and the other end of the positioning cylinder is provided with an external thread for screwing the nut.

7. The laser scanning detector for pipe inner diameter according to claim 6, characterized in that, The positioning device also includes a spring, one end of which abuts against the nut and the other end of which abuts against the umbrella-shaped bracket; the spring is used to convert the rigid contact between the nut and the umbrella-shaped bracket into a flexible contact.

8. The laser scanning detector for pipe inner diameter according to claim 7, characterized in that, The umbrella-shaped support includes a slip ring and multiple folding triangular rods; the slip ring is coaxial with the positioning cylinder and slidably connected to the outside of the positioning cylinder; the slip ring abuts against the spring; the multiple folding triangular rods are alternately arranged in opposite directions on the outside of the positioning cylinder; each of the multiple folding triangular rods has one end rotatably connected to the slip ring and the other end rotatably connected to the positioning cylinder; the multiple folding triangular rods and the slip ring together form an umbrella-shaped structure.

9. The laser scanning detector for pipe inner diameter according to claim 8, characterized in that, The folding triangular rod includes a long rod and a short rod; the long rod and the short rod are rotatably connected; when the umbrella-shaped bracket opens outward, the connection point of the long rod and the short rod forms two sets of support points of different depths on the inner wall of the tube, and the two sets of support points form two congruent polygons perpendicular to the central axis of the tube, so that the shaft is always parallel to the central axis of the tube; when the umbrella-shaped bracket retracts inward, the connection point of the long rod and the short rod is close to the positioning cylinder, and a gap of not less than a preset distance is maintained between them.

10. The laser scanning detector for the inner diameter of a pipe according to claim 9, characterized in that, The folding triangular rod also includes a pin and a pulley; each of the short rod and the long rod has one end configured as a U-shape; the U-shaped end of the short rod is located outside the U-shaped end of the long rod; the pin is fixedly connected to the inside of the U-shaped end of the short rod and rotatably connected to the U-shaped end of the long rod; the pulley is rotatably connected to the pin and is located inside the U-shaped end of the long rod; the central axis of each pulley is perpendicular to the corresponding folding triangular rod; the outer diameter of the pulley is greater than the thickness of the U-shaped ends of the short rod and the long rod.

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