Method for measuring posture of ship repair replacement pipe flange by using light pen

Abstract

The invention discloses a method for measuring the posture of a ship repair replacement pipe flange by using a light pen. The method comprises the following steps: firstly, dismounting a fixing bolt on each of flanges at two ends of a to-be-replaced pipe, then measuring coordinates of nine points on each of the flanges at the two ends of the to-be-replaced pipe by adopting a light pen, namely three points on the back surfaces of the flanges, three points on the outer contours of the flanges and three points on the inner walls of screw holes, and importing the measured coordinates into a computer; data such as the flange posture, the flange outer diameter, the bolt hole center circle diameter and the bolt hole diameter can be calculated through a computer program and then matched with a flange standard database, and accurate data such as the flange posture, the flange nominal size and the bolt number can be determined. The flange posture and other data can be used for three-dimensional reconstruction of a to-be-replaced pipe and flange positioning work of a numerical control reproduction machine. The measuring method can adapt to various complex ship building and repairing site environments, and is simple and quick to operate and high in precision.

Description

Technical Field

[0001] The present invention belongs to the field of mechanical maintenance and manufacturing such as ship maintenance, automobile maintenance, and aircraft maintenance using a light pen for measurement, and specifically relates to a method for measuring the posture of a pipe flange to be replaced in service during ship repair using a light pen. Background Art

[0002] Flanged pipes are widely used in industries such as shipbuilding, aerospace, automotive, high-speed rail, and construction. Currently, ship pipeline repairs require a template to be fabricated at the actual location on-site, then transported back to the workshop for replacement pipe fabrication. This replacement pipe requires repeated revisions, which is costly and time-consuming, significantly increasing the docking time required for repairs, raising maintenance costs and impacting both efficiency and economic benefits.

[0003] In order to solve the drawbacks of the current production method and realize digital production, a method of using a light pen to measure the flange posture of the replacement tube is proposed. That is, a light pen based on computer binocular vision measurement (also known as a portable three-dimensional coordinate measuring machine) is used to obtain the flange postures of the two ends of the replacement tube, which is then imported into the computer for calculation to complete the three-dimensional reconstruction of the replacement tube and output to a CNC reproduction machine for flange positioning.

[0004] Compared to traditional production methods, light pen measurement is a contact measurement method based on computer vision, offering fast measurement speed and high accuracy. Compared to rope measurement and photogrammetry, light pen measurement is more adaptable to complex on-site work environments. It only requires the light pen to be within the field of view of the binocular vision tracker.

[0005] Therefore, it is very necessary to provide a method for measuring the flange posture of the pipe to be replaced in service during ship repair using a light pen, which can accurately obtain the flange posture and specifications through a small number of measurement points, improve environmental adaptability, and reduce the complexity of maintenance. Summary of the Invention

[0006] The present invention aims to provide a method for measuring the posture of flanges at both ends of a replacement pipe without disassembling it. By measuring at least nine points on a single flange, the flange posture can be calculated through computer programming to ensure the installation accuracy of the replacement pipe, meeting the needs of pre-measurement and production of replacement pipes during ship pipe maintenance.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for measuring the posture of a pipe flange for ship repair replacement using a light pen comprises the following steps:

[0009] S1: equipped with binocular pencil measurement equipment;

[0010] S2: Use a binocular pencil measurement device to obtain the coordinates of points on different surfaces of the flange;

[0011] S3: Use the point on the back of the flange to obtain the equation of the plane on which the back of the flange is located;

[0012] S4: Using the points on the side of the flange, obtain the coordinates O of the center point and the outer diameter D of the back of the flange;

[0013] S5: Use the point inside the flange bolt hole and the coordinate of the back center point O to obtain the diameter K of the virtual circle where the flange bolt hole is located and the coordinate of the center of the bolt hole O K , bolt hole diameter L;

[0014] S6: By matching the flange outer diameter D, bolt hole center circle diameter K, and bolt hole diameter L with the flange standard database, the flange posture and flange model can be determined, and the flange thickness can be further obtained based on the flange model;

[0015] S7: Based on the flange thickness, the back side of the flange is translated along the normal direction of the flange surface by the flange thickness value to obtain the spatial posture of the flange sealing surface.

[0016] Based on the above technical solution, preferably, the number of measuring points on the back of the flange, the measuring points on the side of the flange, or the measuring points in the flange bolt holes is at least three.

[0017] Preferably, the content of step S3 is to record the coordinates of any three non-collinear points on the back of the flange as P i (x i ,y i ,z i ), i=1,2,3; the plane determinant of the flange back is as follows: Expanding the determinant, it can be converted into the standard form Ax+By+Cz+D=0, is the plane normal vector of the flange back surface.

[0018] Further preferably, the content of step S4 is to obtain the coordinates of any three non-collinear points on the side of the flange, denoted as P j (x j ,y j ,z j ), j=4,5,6; projected onto the back plane of the flange, the projection point is The center coordinates of the flange back are calculated using the following formula:

[0019] O=M -1 *b=(x o ,y o ,z o ),in:

[0020] Flange outer radius: Flange outer diameter D=2R.

[0021] Combine the plane expressions of the back of the flange to obtain the coordinates of the center of the bolt hole O K =(x ok ,y ok ,z ok ), the diameter of the virtual circle where the flange bolt hole is located is Bolt hole diameter is

[0022] Further preferably, when the number of points P on the back of the flange i (x i ,y i ,z i ) When there are more than three, i≤N, N>3, according to the plane equation of the flange back Ax+By+Cz+D=0, the plane normal vector of the flange back Let P i (x i ,y i ,z i ) to the plane: pass: A can be obtained, and similarly, B, C, and D can be obtained, and then the regression formula and flange normal vector of the flange back at N measuring points on the flange back can be obtained;

[0023] When there are more than three measuring points on the flange side, project the measuring points on each flange side onto the flange back, and use the projection point regression circle to obtain the flange center point coordinates or flange diameter.

[0024] Compared with the prior art, the method provided by the present invention for measuring the posture of a pipe flange for ship repair replacement using a light pen has the following beneficial effects:

[0025] (1) When replacing pipes during ship maintenance, there is no need to dismantle the pipes to be replaced. Instead, one bolt on each flange at both ends of the pipe (two bolts in total) needs to be removed to directly measure the in-service pipes. This allows measurement and pipe processing to be carried out before the ship enters the dock for maintenance, thus shortening the dock occupancy time.

[0026] (2) The coordinate accuracy of the light pen measurement point can be controlled within 0.5mm, ensuring the measurement accuracy of the ship repair replacement pipe and the subsequent assembly accuracy;

[0027] (3) The shape, size, number of branches and other factors of the pipeline have no effect on the measurement of flange posture by the light pen, which can meet different needs on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1The present invention provides a flow chart of a method for measuring the posture of a pipe flange during ship repair and replacement using a light pen.

[0029] Figure 2 The present invention is a schematic diagram of the selected positions of the measurement points of a method for measuring the posture of a pipe flange for ship repair replacement using a light pen.

[0030] Figure 3 The figure is a three-dimensional schematic diagram of flange posture reconstruction in a method for measuring the posture of a flange of a pipe for ship repair and replacement using a light pen according to the present invention. DETAILED DESCRIPTION

[0031] Traditional ship pipeline repairs require a prototype to be fabricated at the actual location on-site, then transported back to the workshop for replacement pipe fabrication. This replacement pipe also requires repeated revisions, which is costly and time-consuming, significantly increasing the docking period for repairs and raising maintenance costs, impacting repair efficiency and economic benefits. In light of this, the present invention provides a method for measuring the flange posture of a ship repair replacement pipe using a light pen. The light pen device measures the coordinates of at least nine points on the flange, and the flange posture is calculated through computer programming. This data is then matched against a standard flange library to obtain accurate data such as the flange posture, flange nominal dimensions, and bolt quantity, enabling rapid and accurate measurement of the flange posture.

[0032] like Figure 1 As shown, the present invention provides a method for measuring the posture of a pipe flange for ship repair replacement using a light pen, which specifically includes the following steps:

[0033] S1: Configure binocular pencil measurement equipment.

[0034] The light pen measuring device is a photoelectric coordinate measuring instrument for measuring large parts, fixtures, molds, castings and forgings. It uses photogrammetry technology. The camera measures the three-dimensional coordinates of multiple infrared light-emitting diodes (LEDs) embedded in the light pen to obtain the position and posture of the light pen in space, and converts them into the coordinate value of the measurement point.

[0035] S2: Use binocular pencil measuring equipment to measure the coordinates of points on the flange, including the non-collinear points on the back of the flange, the non-collinear points on the side of the flange, and the non-collinear points in the flange bolt holes. Figure 2 , Figure 2 A schematic diagram of the positions of different measuring points is provided. In this embodiment, the number of measuring points on the flange back, flange side, and flange bolt hole is at least three.

[0036] The non-collinearity here means that the measuring points on the back of the flange are not on the same straight line, the measuring points on the side of the flange are not on the same straight line, and the measuring points in the flange bolt holes are not on the same straight line.

[0037] S3: Use the point on the back of the flange to obtain the equation of the plane on which the back of the flange lies.

[0038] Step S3 is to obtain the coordinates of any three non-collinear points on the back of the flange, denoted as P i (x i ,y i ,z i ), i=1,2,3; the plane determinant of the flange back is as follows: Expanding the determinant, it can be converted into the standard form Ax+By+Cz+D=0, is the plane normal vector of the flange back surface.

[0039] S4: Use the points on the side of the flange to obtain the center point coordinates O and the outer diameter D of the back of the flange.

[0040] Step S4 is to obtain the coordinates of any three non-collinear points on the flange side, denoted as P j (x j ,y j ,z j ), j=4,5,6; projected onto the back plane of the flange, the projection point is The center coordinates of the flange back are calculated using the following formula: O = M -1 *b=(x o ,y o ,z o ),in: Flange outer radius: Flange outer diameter D=2R.

[0041] S5: Use the point inside the flange bolt hole and the coordinate of the back center point O to obtain the diameter K of the virtual circle where the flange bolt hole is located and the coordinate of the center of the bolt hole O K , bolt hole diameter L.

[0042] Step S5 is to remove a fixing bolt on the flange and measure the coordinates of any three non-collinear points on the inner wall of the flange bolt hole, which are recorded as P k (x k ,y k ,z k ), k=7,8,9; after projecting onto the back plane of the flange, the projection point is obtained Through the projection point P′ k The circle is represented by The combined result is: Abbreviated as Combining the plane expressions of the back of the flange, we get Then the coordinate of the center of the bolt hole is O K for The diameter of the virtual circle where the flange bolt hole is located is Bolt hole diameter is

[0043] Here we use the plane expression of the flange back and the projection point P' k The simultaneous result of the circle is obtained by calculating the coordinates of the center of the bolt hole O K , calculate the coordinates of the center of the bolt hole O K The distance between the center coordinates of the flange back side is used to obtain the radius of the virtual circle where the flange bolt hole is located; according to the center coordinates of the bolt hole O K The bolt hole radius is obtained by the distance from the projection coordinates of the measuring point on the inner wall of any flange bolt hole, and the diameter K of the virtual circle where the flange bolt hole is located and the bolt hole diameter L are further obtained.

[0044] S6: By matching the flange outer diameter D, bolt hole center circle diameter K, and bolt hole diameter L with the flange standard database, the flange posture and flange model can be determined, and the flange thickness can be further obtained based on the flange model.

[0045] For example, by determining the nominal pressure of the pipeline, the flange outer diameter D, the bolt hole spacing (i.e., the diameter K of the virtual circle where the flange bolt holes are located), the bolt diameter closest to the bolt hole diameter L, and the number of bolt holes, the corresponding nominal diameter and flange thickness of the flange can be obtained. For a single standard, the data of these flanges are one-to-one corresponding, so the flange model and thickness are unique.

[0046] S7: By using the flange thickness, the flange back is translated along the normal direction of the flange surface by the flange thickness value to obtain the spatial posture of the flange sealing surface. Figure 3 As shown in the figure, the spatial posture of the flange sealing surface is obtained by offsetting the flange back. The flange sealing surface is the fitting surface of the two flanges in a sealed connection.

[0047] In this embodiment, the number of the above-mentioned measuring points is 9 in total, in order to meet the minimum measuring points for the spatial posture of the flange sealing surface. If the flange posture accuracy needs to be improved, the number of points on the back of the flange, the side of the flange, or the points in the flange bolt hole can be further increased.

[0048] For example, if the flange normal accuracy needs to be improved, the number of points P on the back of the flange will be increased. i (x i ,y i ,z i ), i≤N, N>3, that is, N is an integer greater than 3, according to the plane equation of the flange back is Ax+By+Cz+D=0, the plane normal vector of the flange back Let P i (x i ,y i ,zi ) to the plane: pass: A can be obtained, and similarly, B, C, and D can be obtained, and then the regression formula and flange normal vector of the back side of the flange at N measuring points on the back side of the flange can be obtained, which can be obtained by referring to the method of step S3.

[0049] If the accuracy of the flange center point or diameter needs to be improved, the number of measuring points on the flange side is increased. After projecting to the back of the flange, the projection point regression circle is used to obtain the flange center point coordinates or flange diameter, which can be obtained by referring to the method in step S4.

[0050] If it is necessary to know the pipeline direction of the replacement pipe connected to the flange, additional measuring points are added to the pipeline and the pipeline axis fitting equation is obtained using the measuring points.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring the posture of a pipe flange during ship repair and replacement using a light pen, characterized by: The steps include: S1: equipped with binocular pencil measurement equipment; S2: Use a binocular pencil measurement device to obtain the coordinates of points on different surfaces of the flange; S3: Use the point on the back of the flange to obtain the equation of the plane on which the back of the flange is located; S4: Using the points on the side of the flange, obtain the coordinates O of the center point and the outer diameter D of the back of the flange; S5: Use the point inside the flange bolt hole and the coordinate of the back center point O to obtain the diameter K of the virtual circle where the flange bolt hole is located and the coordinate of the center of the bolt hole O K , bolt hole diameter L; S6: By matching the flange outer diameter D, bolt hole center circle diameter K, and bolt hole diameter L with the flange standard database, the flange posture and flange model can be determined, and the flange thickness can be further obtained based on the flange model; S7: Based on the flange thickness, the back side of the flange is translated along the normal direction of the flange surface by the flange thickness value to obtain the spatial posture of the flange sealing surface.

2. The method for measuring the posture of a pipe flange for ship repair and replacement using a light pen according to claim 1, characterized in that: The number of measuring points on the back of the flange, the side of the flange, or the bolt holes of the flange shall be at least three.

3. The method for measuring the posture of a pipe flange for ship repair and replacement using a light pen according to claim 2, characterized in that: The content of step S3 is to record the coordinates of any three non-collinear points on the back of the flange as P i (x i ,y i ,z i ), i=1,2,3; the plane determinant of the flange back is as follows: Expanding the determinant, it can be converted into the standard form Ax+By+Cz+D=0, is the plane normal vector of the flange back surface.

4. The method for measuring the posture of a pipe flange during ship repair and replacement using a light pen according to claim 3, characterized in that: Step S4 is to obtain the coordinates of any three non-collinear points on the flange side, denoted as P j (x j ,y j ,z j ), j=4,5,6; projected onto the back plane of the flange, the projection point is The center coordinates of the flange back are calculated using the following formula: O=M -1 *b=(x o ,y o ,z o ),in: Flange outer radius: Flange outer diameter D=2R.

5. The method for measuring the posture of a pipe flange for ship repair and replacement using a light pen according to claim 4, characterized in that: Step S5 is to remove a fixing bolt on the flange and measure the coordinates of any three non-collinear points on the inner wall of the flange bolt hole, which are recorded as P k (x k ,y k ,z k ), k=7,8,9; after projecting onto the back plane of the flange, the projection point is obtained Through the projection point P′ k The circle is represented by Combine the plane expressions of the back of the flange to obtain the coordinates of the center of the bolt hole O K =(x ok ,y ok ,z ok ), The diameter of the virtual circle where the flange bolt hole is located is Bolt hole diameter is 6. The method for measuring the posture of a pipe flange during ship repair and replacement using a light pen according to claim 5, characterized in that: When the point P on the back of the flange i (x i ,y i ,z i ) When there are more than three, i≤N, N>3, according to the plane equation of the flange back Ax+By+Cz+D=0, the plane normal vector of the flange back Let P i (x i ,y i ,z i ) to the plane: pass: A can be obtained, and similarly, B, C, and D can be obtained, and then the regression formula and flange normal vector of the flange back at N measuring points on the flange back can be obtained; When there are more than three measuring points on the flange side, project the measuring points on each flange side onto the flange back, and use the projection point regression circle to obtain the flange center point coordinates or flange diameter.

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