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CN-121994134-A - Method for measuring dimension of inner wall of long and narrow metal pipeline

CN121994134ACN 121994134 ACN121994134 ACN 121994134ACN-121994134-A

Abstract

The invention relates to a method for measuring the size of the inner wall of a long and narrow metal pipeline, which comprises the steps of placing a camera outside the end B of the long and narrow metal pipeline, focusing a lens of the camera to the end B of the pipeline, collecting pipeline images, extracting the inner contour of the end A of the long and narrow metal pipeline according to the collected pipeline images, obtaining the number of diameter pixels of the end A of the long and narrow metal pipeline, calibrating the size of the pixels, placing a carrier capable of moving along the axial direction of the pipeline inside the long and narrow metal pipeline, arranging a laser capable of emitting two concentric ring laser at the front end of the carrier, emitting the laser towards the camera, opening the laser and the camera, controlling the carrier to uniformly move from the end A of the pipeline to the end B, acquiring the pipeline images collected by the camera in real time in the moving process of the carrier, and acquiring the size of each position of the inner wall of the long and narrow metal pipeline according to the collected pipeline images and the calibrated pixel size. The measuring method has low cost and high measuring efficiency, and can reduce the manufacturing difficulty of measuring equipment.

Inventors

  • GONG YUEQIANG
  • QI ZHENNING

Assignees

  • 浙江康帕斯流体技术股份有限公司

Dates

Publication Date
20260508
Application Date
20260331

Claims (7)

  1. 1. The method for measuring the size of the inner wall of the long and narrow metal pipeline is characterized by comprising the following steps of: The method comprises the steps of 1, marking the head end and the tail end of a long and narrow metal pipeline as an A end and a B end respectively, placing a camera outside the B end of the long and narrow metal pipeline, arranging a lens of the camera towards the inside of the long and narrow metal pipeline, overlapping the lens of the camera with the central axis of the long and narrow metal pipeline, focusing the lens of the camera to the B end outlet of the long and narrow metal pipeline when a carrier capable of moving along the axial direction of the pipeline is not placed in the long and narrow metal pipeline, collecting pipeline images, extracting the inner contour of the A end of the long and narrow metal pipeline according to the collected pipeline images, obtaining the number of diameter pixels of the A end of the long and narrow metal pipeline, calibrating the pixel size, and obtaining the calibrated pixel size ; Step 2, a carrier capable of moving along the axial direction of the pipeline is placed in the long and narrow metal pipeline, and a laser capable of emitting two concentric annular lasers is arranged at the front end of the carrier, wherein one annular laser is a positioning laser ring, the other annular laser is a measuring laser ring for measuring the inner contour of the long and narrow metal pipeline, the positioning laser ring is a laser inner ring, the measuring laser ring is a laser outer ring, and the laser emits laser towards a camera; step 3, opening the laser and the camera, controlling the carrier to uniformly move from the end A to the end B of the long and narrow metal pipeline, acquiring pipeline images acquired by the camera in real time in the moving process of the carrier, and according to the acquired pipeline images and the calibrated pixel size The dimensions of each location of the inner wall of the elongated metal tube are obtained.
  2. 2. The method for measuring the inner wall size of an elongated metal tube according to claim 1, wherein the pixel size after calibration in step 1 The calculation formula of (2) is as follows: Wherein, the Is the diameter of the end A of the long and narrow metal pipeline, The unit of (a) is a unit of length, Is the number of diameter pixels at the a end of the elongated metal tube.
  3. 3. The method for measuring the dimension of the inner wall of the long and narrow metal pipeline according to claim 1, wherein the step 3 further comprises the following steps before the carrier moves: and acquiring a pipeline image by using a camera, judging whether the laser is right opposite to the camera according to the currently acquired pipeline image, and adjusting the laser to enable the laser to be right opposite to the camera if the laser is not right opposite to the camera, wherein when the laser is right opposite to the camera, the central axis of the laser is overlapped with the central axis of the camera.
  4. 4. The method for measuring the dimension of the inner wall of the long and narrow metal pipeline according to claim 3, wherein the specific process of judging whether the laser is opposite to the camera in the step 3 is as follows: setting the central position of an acquired pipeline image as an origin O ́, extracting an inner ring contour, and obtaining a major axis pixel a, a minor axis pixel b and the central coordinate of the inner ring through ellipse fitting; If the long axis pixel a and the short axis pixel b of the inner ring are not equal, or the center coordinates of the inner ring are not the origin O ́, it is indicated that the laser is not facing the camera.
  5. 5. The method for measuring the dimension of the inner wall of the long and narrow metal pipeline according to claim 4, wherein the specific process of adjusting the laser in the step 3 is as follows: if the long axis pixel a and the short axis pixel b of the inner ring are not equal, the laser is arranged according to a set included angle The adjustment is carried out so that the adjustment is carried out, So that the major axis pixel a and the minor axis pixel b of the adjusted inner ring are equal; If the center coordinate of the inner ring is not the origin O ́, the laser is translated so that the center coordinate of the inner ring is the origin O ́.
  6. 6. The method for measuring the inner wall size of an elongated metal tube according to any one of claims 3 to 5, wherein the specific process of obtaining the size of each position in step 3 is as follows: Taking a focus of a camera as an origin, setting the axial direction of the long and narrow pipeline as a Z axis, setting the radial direction of the long and narrow pipeline as an X axis, setting the radial direction of the long and narrow pipeline as a Y axis, and establishing a three-dimensional coordinate system, wherein the X axis, the Z axis and the Y axis are mutually perpendicular; when the laser is positioned at the position Z on the Z axis, the pipeline image acquired by the camera is recorded as , The laser comprises a laser inner ring and a laser outer ring, and is used for pipeline image Threshold segmentation is carried out to obtain two concentric rings, and the radius of the inner ring of the concentric rings is obtained as , In pixels, the position of the laser in the pipeline The calculation formula of (2) is as follows: Wherein, the For the actual diameter of the laser inner ring, For the length of the elongated metal tube, And The units of (a) are all length units; In the form of pipeline images The origin of (a) is taken as the center, the edge of the outer ring is extracted, and each point and each other point of the edge of the outer ring are calculated Distance between centers according to each point of the edge of the outer ring Calculating the distance of the center to obtain the outline size of the actual long and narrow metal pipeline under the interface; Record the first edge of the outer ring Dots and dots The distance between the centers is , In pixels, under the interface of the outer ring The actual size of the outline of the long and narrow metal pipeline corresponding to the point is , , Units of (2) Is the same in units of (a).
  7. 7. The method for measuring the inner wall size of the long and narrow metal pipeline according to any one of claims 1 to 5, wherein the carrier is a wheeled trolley or a sliding block, a guide rail is arranged along the axial direction of the long and narrow metal pipeline, and the sliding block is connected to the guide rail in a sliding manner.

Description

Method for measuring dimension of inner wall of long and narrow metal pipeline Technical Field The invention relates to the field of dimension measurement, in particular to a method for measuring the dimension of the inner wall of an elongated metal pipeline. Background At present, according to different application scenes, the method and equipment for measuring the inner contour of the long and narrow pipeline are required to meet the requirements of precision, efficiency, measurement environment adaptability and the like, and the common method can be divided into contact measurement, optical measurement, acoustic measurement, electromagnetic measurement, combined measurement and the like according to the technical principle. The method is based on the principle of reflection, refraction or interference of light, realizes non-contact measurement, is suitable for pipelines with clear surface characteristics, has the advantages of non-contact, high speed and slightly lower precision, is influenced by the cleanliness of the inner wall of the pipeline, needs a special detection crawler, obtains the inner wall information of the pipeline by utilizing the sound wave propagation characteristic, is suitable for the pipeline with opaque or complex structure, can measure the internal layering defect, the thinning of the pipe wall, the inner profile morphology of the pipeline from the outer wall of the pipeline, but needs auxiliary sound waves such as couplant and the like to penetrate the pipeline, has lower resolution, is suitable for the rapid detection of the surface and the near surface defect of the pipeline based on electromagnetic induction or eddy current effect, can detect the surface defect of the pipeline without couplant, has high material conductivity requirement, has low measurement precision and cannot obtain complete profile data. The combined measurement rule is to complement the technical advantages of the above-mentioned multiple techniques, solve the limitation of a single method, such as laser-ultrasonic fusion detection, acquire high-precision geometric outline by laser scanning, synchronously evaluate wall thickness and internal defects by ultrasonic detection, and generate a complete three-dimensional model after data fusion. In summary, the method for measuring the dimension of the inner wall of the long and narrow metal pipeline at the present stage is mainly based on a pipeline detection robot (such as a snake-shaped robot and a crawler), and laser radars, ultrasonic probes, industrial cameras and the like are integrated on the pipeline detection robot, so that the measuring precision is high, the equipment value is high, the investment is high at one time, and the crawler with different specifications is manufactured according to the requirements of inner pipe diameters with different diameters. Further improvements are needed in terms of detection hardware cost, measurement efficiency. Disclosure of Invention The invention aims to solve the technical problem of providing a method for measuring the dimension of the inner wall of an elongated metal pipeline, which is low in cost and high in measurement efficiency. The technical scheme adopted by the invention for solving the technical problems is that the method for measuring the dimension of the inner wall of the long and narrow metal pipeline is characterized by comprising the following steps: The method comprises the steps of 1, marking the head end and the tail end of a long and narrow metal pipeline as an A end and a B end respectively, placing a camera outside the B end of the long and narrow metal pipeline, arranging a lens of the camera towards the inside of the long and narrow metal pipeline, overlapping the lens of the camera with the central axis of the long and narrow metal pipeline, focusing the lens of the camera to the B end outlet of the long and narrow metal pipeline when a carrier capable of moving along the axial direction of the pipeline is not placed in the long and narrow metal pipeline, collecting pipeline images, extracting the inner contour of the A end of the long and narrow metal pipeline according to the collected pipeline images, obtaining the number of diameter pixels of the A end of the long and narrow metal pipeline, calibrating the pixel size, and obtaining the calibrated pixel size ; Step 2, a carrier capable of moving along the axial direction of the pipeline is placed in the long and narrow metal pipeline, and a laser capable of emitting two concentric annular lasers is arranged at the front end of the carrier, wherein one annular laser is a positioning laser ring, the other annular laser is a measuring laser ring for measuring the inner contour of the long and narrow metal pipeline, the positioning laser ring is a laser inner ring, the measuring laser ring is a laser outer ring, and the laser emits laser towards a camera; step 3, opening the laser and the camera, controlling the carrier to uniformly mov