A rapid detection method for abnormal roundness of large diameter cylinders

Abstract

The present invention discloses a rapid detection method for the roundness abnormal area of ​​a large-diameter cylinder, comprising the following steps: using the laser non-contact measurement mode of a total station to automatically and uniformly determine n measuring points on the inner surface of the cylinder along the 360° direction; establishing a measuring station through a backsight point, establishing a coordinate system, and determining the coordinates of each measuring point; performing automatic roundness calculation based on the obtained measuring point coordinates to obtain a roundness detection result, and outputting the roundness of the large-diameter cylinder, the coordinates of the roundness abnormal point, and the roundness abnormal area. The present invention combines the non-contact automatic measurement mode of a high-precision total station with the roundness automatic calculation program, and can realize the on-site rapid detection of the roundness of a large-diameter cylinder, and by increasing the density of measuring points inside the cylinder, the measurement accuracy of abnormal points and abnormal areas can be greatly improved, and has the advantages of simple on-site operation, rapidity, high efficiency, and high accuracy.

Description

Technical Field

[0001] The invention relates to a method for quickly detecting an abnormal roundness area of ​​a large-diameter cylinder. Background Art

[0002] During the production, transportation, installation and operation of large diameter cylinders, one or more roundness abnormal areas may appear due to some reasons, so that the relevant requirements for equipment acceptance and operation are not met. The most typical example is the support cylinder of a wind turbine, such as Figure 1 As shown, with the gradual increase of unit power, the diameter develops from the original 2m to the current 12m, or even larger. Its processing, transportation and operation may cause its roundness to fail to meet the current standard requirement of 1% "Wind Turbine Tower" GB / T19072.

[0003] In actual projects, serious accidents such as transportation, installation or overturning may cause abnormal roundness of the cylinder. At this time, it is necessary to conduct on-site inspection of the roundness and abnormal points of the wind turbine cylinder to find the exact location and range of the abnormal area. In actual projects, large-diameter cylinders may have one or more abnormal roundness areas, such as Figure 2 shown.

[0004] At present, although there are commonly used quantitative detection methods for roundness error assessment of large-diameter cylinders in the industrial field, the following two methods are usually used: part rotation method and indirect measurement method of three-point distance measurement around the circle.

[0005] The rotary axis method compares the circular trajectory (ideal circle) formed by one rotation of the axis in the precision axis system with the measured circle. The difference in the radius of the two circles is converted into an electrical signal by an electrical length sensor. After circuit processing and electronic computer calculation, the roundness error is indicated by the display instrument, or the profile of the measured circle is recorded by the recorder. The rotary axis method has two forms: sensor rotation and worktable rotation. The former is suitable for high-precision roundness measurement, and the latter is often used to measure small workpieces.

[0006] The indirect measurement method of three-point distance measurement on a circle often places the workpiece to be measured in a V-shaped block for measurement. During measurement, the workpiece to be measured is rotated in the V-shaped block for one circle, and the maximum and minimum indications are read from the micrometer. Half of the difference between the two indications is the roundness error of the outer circle of the workpiece to be measured. This method is suitable for measuring outer or inner circles with odd edge shape errors. Two V-shaped blocks with two angles of 90°, 120° or 72°, 108° are usually used for measurement. However, since most detection equipment is expensive, large in size and weight, and both the three-coordinate machine (indirect measurement method of three-point distance measurement on a circle) and the roundness meter (part rotation method) have high requirements for the operating environment, they usually need to set up a separate metrology room, which is not suitable for on-site online detection, and it is difficult to quickly and accurately locate the roundness abnormal area and abnormal points. For cylinders with larger diameters, the existing technology is difficult to operate or cannot be measured.

[0007] Up to now, there are many patents related to detecting the roundness of large-diameter cylinders. For example, the utility model patent document CN211042165U is a device that can detect the roundness of large cylinders online, and proposes a device that can detect the roundness of large cylinders online. Its innovation lies in: the device includes a base, two sets of roller supports, two rollers, two transmission motors, a distance sensor, a Hall switch sensor and a host computer; the beneficial technical effect is: a device and method that can detect the roundness of large cylinders online are proposed, and the scheme can detect the roundness of large cylinders online, which is particularly suitable for industrial site use. However, in many cases, the large-diameter cylinders produced from the factory have been put into actual projects and are not easy to disassemble. The utility model CN211042165U is only suitable for use in factories. Compared with the traditional factory method of detecting roundness, it has certain advantages, but it is not suitable for actual projects. Moreover, it is obviously impractical to bring the roundness detection equipment of the patent to the site for detection.

[0008] Patent document CN117516335A, a method, tooling and combined structure for measuring the roundness of a large cylinder or cylindrical structure, discloses a method, tooling and combined structure for measuring the roundness of a large cylinder or cylindrical structure, and belongs to the field of industrial measurement technology. The measuring method includes: fixing multiple measuring tools at the corresponding positions at both ends of the workpiece; determining the theoretical initial value of the workpiece radius extension R extension; determining the coordinates of the predetermined points so that the actual distance between each predetermined point and the center of the workpiece end is R extension; setting a measuring line to measure the actual distance between each measuring line and the outer surface of the workpiece; determining the roundness of the workpiece by the actual outer diameter of the workpiece; the measuring tool includes a fastening assembly and a positioning assembly connected to each other, and the positioning assembly is provided with a reflector for positioning the predetermined point; the measuring combined structure includes multiple measuring tools arranged at both ends of the workpiece; the measuring lines corresponding to the same equally divided positions at both ends of the workpiece are parallel. Measuring the outer surface roundness of a large cylinder from the outside significantly reduces the difficulty of the measurement operation, has a higher measurement accuracy, and more conveniently measures the roundness of a large cylinder. This patent can solve the technical problem of roundness measurement of a large cylinder with an internal obstruction or internal structure to a certain extent. However, this patent is only applicable to factory roundness detection and is still not suitable for on-site roundness detection. Although it solves the problem of internal obstructions to a certain extent, sometimes the external environment of the cylinders that have been put into use in projects is harsh, and the method provided by this patent is not applicable. Moreover, this patent can only detect roundness, and does not involve how to quickly find abnormal areas and abnormal points of large-diameter cylinders.

[0009] Patent document CN111102906A provides a method and device for detecting the roundness of a large-aperture cylinder, and provides a method and device for detecting the roundness of a cylinder, which can solve the problems of poor accuracy, non-intuitive results and low efficiency in measuring the roundness of a cylinder in the prior art. The cylinder roundness measuring device includes a positioning bracket, an arc positioning rod, a vertical scale rod, a vertical clamp, a detachable centering shaft and a swinging diameter rod, wherein: the positioning bracket is used to locate the plane height of the arc to be measured; the arc positioning rod is used to locate the starting point of the arc to be measured; the vertical scale is perpendicular to the arc positioning rod, and is used to determine the straight line where the center of the arc is located; the vertical clamp is used to ensure the vertical relationship between the arc positioning rod and the vertical scale; the detachable centering shaft is used for connection after the arc center is determined; the swinging diameter rod is used to rotate 360° in the circumference to prepare for close-range determination of the degree of depression or protrusion of an irregular arc. This patent visually confirms the roundness of the detected arc by the degree of intersection between the free end and the arc surface during the rotation of the swinging radial rod. Although the operation is relatively simple, it can only work when the roundness error of the cylinder is large. The accuracy is not guaranteed, and a good operating environment must be provided. When the cylinder has been installed and there are obstructions inside the cylinder, this method is not applicable. Moreover, the method provided by the patent requires the production of different positioning brackets, arc positioning rods, vertical scales, vertical clamps, detachable centering shafts, and swinging radial rods according to the size of the cylinder for each detection, which is very inconvenient. Summary of the invention

[0010] In order to solve the above technical problems, the present invention provides a method for quickly detecting abnormal roundness areas of large-diameter cylinders with simple operation and high accuracy.

[0011] The present invention proposes a technical solution to solve the above technical problem: a method for quickly detecting the abnormal roundness area of ​​a large-diameter cylinder, comprising the following steps:

[0012] Step 1: Place the three frames in the cylinder, place the total station on the tripod, and after debugging is normal, adjust the objective lens of the total station to a horizontal level;

[0013] Step 2: Use the laser non-contact measurement mode of the total station to automatically and evenly determine n measuring points along the 360° direction on the inner surface of the cylinder;

[0014] Step 3: Establish a measuring station through the backsight point, establish a coordinate system, and determine the coordinates of each measuring point;

[0015] Step 4: Automatically calculate the roundness based on the obtained measuring point coordinates to obtain the roundness detection result, and output the roundness of the large-diameter cylinder, the coordinates of the roundness abnormal point and the roundness abnormal area.

[0016] In the above-mentioned method for rapid detection of abnormal roundness areas of large-diameter cylinders, in step 2, the measurement accuracy can be improved by increasing the number of measuring points.

[0017] The specific process of the above-mentioned method for rapid detection of abnormal roundness of large-diameter cylinders is as follows:

[0018] 4-1) Select 3 measuring point coordinates from all the measuring point coordinates as a group, and calculate all the center points and diameters according to the three-coordinate measurement method;

[0019] 4-2) Set the judgment standard according to the roundness specification of the cylinder of the wind turbine, and determine the three coordinate points that meet the judgment standard as qualified points;

[0020] 4-3) Repeat steps 4-1) and 4-2), traverse all combinations of selecting 3 measuring points from n measuring points, and obtain all qualified points. The remaining points other than the qualified points are judged as abnormal points, and the area formed by adjacent abnormal points is the roundness abnormal area.

[0021] In the above-mentioned method for rapid detection of abnormal roundness area of ​​large-diameter cylinder, in step 4-1), the measurement process of three-coordinate measurement method is as follows:

[0022] 4-1-1) Let A, B, and C be three random measurement points on the inner surface of the cylinder obtained through measurement. The coordinates of the three measurement points A, B, and C are A: (x1, y1), B: (x2, y2), and C: (x3, y3);

[0023] 4-1-2) Connect AB and BC, and make the perpendicular bisector L1 of AB and the perpendicular bisector L2 of BC. Then L1 and L2 can be expressed as:

[0024]

[0025]

[0026] 4-1-3) Let L1 = L2, and the coordinates of the center of the circle O: (x, y) are expressed as:

[0027]

[0028]

[0029] 4-1-4) Calculate the diameter D of the circle determined by the three measuring points A, B, and C i , i represents the calculated diameter number, diameter D i The calculation expression is:

[0030]

[0031] In the above-mentioned method for rapid detection of abnormal roundness of large-diameter cylinders, in step 4-2), the judgment criteria are:

[0032] According to the requirements of GB / T19072 "Wind Turbine Tower", the roundness tolerance requirements for any section of the cylinder are:

[0033] (D max -D min ) / D min ≤0.01 (6)

[0034] D max D is the maximum diameter measured; min is the minimum diameter measured; D non Design the diameter of the cylinder to be tested;

[0035] According to the roundness specification of the cylinder of the wind turbine, when the diameter calculation difference is less than 1% of the design diameter of the cylinder being tested, the area is qualified, and the three measuring points involved in the calculation are all qualified points, namely:

[0036] (D i -D non ) / D non ≤0.01 (7)

[0037] If the calculated diameter difference is greater than 1% of the designed diameter of the tested cylinder, the area is temporarily determined as an abnormal area. If any of the three measuring points involved in the calculation have been previously judged as qualified points, they are still considered qualified points. The remaining measuring points are judged as abnormal points, and the area formed by adjacent abnormal points is judged as an abnormal area.

[0038] In the above-mentioned method for rapid detection of abnormal roundness of large-diameter cylinders, in step 4-3), each combination is calculated to obtain a diameter D i , the diameter D is calculated according to the number of different measuring points n i , by calculating the combination number formula The diameter calculation quantity is:

[0039]

[0040] The beneficial effects of the present invention are:

[0041] 1. Compared with the existing method that can only be detected in the factory, the present invention can realize the rapid detection of the abnormal area of ​​roundness of large-diameter cylinders on site, that is, it is only equipped with a high-precision total station and a computer. The equipment is light and easy to carry, and can realize the rapid detection of abnormal points and abnormal areas on site.

[0042] 2. The present invention combines the non-contact automatic measurement mode of a high-precision total station with an automatic roundness calculation program, and can realize on-site rapid detection of the roundness of a large-diameter cylinder.

[0043] 3. The present invention can greatly improve the measurement accuracy of abnormal points and abnormal areas by increasing the density of measuring points inside the cylinder, and has the advantages of simple on-site operation, fast and efficient, and high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a photo of the wind turbine tower collapsing.

[0045] Figure 2 Schematic diagram of the abnormal roundness area of ​​a large-diameter cylinder, where (a) is a schematic diagram of a single abnormal area, and (b) is a schematic diagram of a plurality of abnormal areas.

[0046] Figure 3 It is a flow chart of the present invention.

[0047] Figure 4 This is the plan view of the total station layout inside the cylinder.

[0048] Figure 5 Schematic diagram of total station testing.

[0049] Figure 6 Schematic diagram for roundness calculation.

[0050] Figure 7 Schematic diagram of determining the center of a circle for three-coordinate measurement.

[0051] Figure 8 Schematic diagram of the roundness tolerance requirements for any section.

[0052] Fig. 9 Schematic diagram of qualified points in CAD simulation of an abnormal area, where the measurement points in (a) are 5, 6, and 8, and the measurement points in (b) are 1, 6, and 7.

[0053] Fig.10 Schematic diagram of abnormal points in CAD simulation, where the measurement points in (a) are 1, 2, and 8, the measurement points in (b) are 3, 6, and 7, and the measurement points in (c) are 1, 4, and 7.

[0054] Fig.11 Schematic diagram of abnormal points in CAD simulation of two abnormal areas.

[0055] Fig.12 Schematic diagram of increasing the density of measuring points, where (a) is a schematic diagram of the inability to detect abnormal areas due to too few measuring points, and (b) is a schematic diagram after the number of measuring points is increased. DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0057] like Figure 3As shown, a method for quickly detecting the abnormal roundness area of ​​a large-diameter cylinder comprises the following steps:

[0058] Step 1: If Figure 4 As shown, place the three frames in the cylinder and the high-precision total station on the tripod. After normal debugging, adjust the objective lens of the total station to be horizontal.

[0059] Step 2: If Figure 5 As shown, the laser non-contact measurement mode of the total station is used to automatically and evenly determine n measuring points along the 360° direction on the inner surface of the cylinder, and the number of measuring points n is greater than or equal to 8.

[0060] Step 3: Establish a measuring station through the backsight point, establish a coordinate system, and determine the coordinates of each measuring point.

[0061] Step 4: Automatically calculate the roundness based on the obtained measuring point coordinates to obtain the roundness detection result, and output the roundness of the large-diameter cylinder, the coordinates of the roundness abnormal point and the roundness abnormal area.

[0062] like Figure 6 As shown, the specific process of step 4 is:

[0063] 4-1) Select 3 measuring point coordinates from all the measuring point coordinates as a group, and calculate all the center points and diameters according to the three-coordinate measurement method.

[0064] In step 4-1), the measurement process of the three-coordinate measurement method is as follows:

[0065] 4-1-1) Figure 7 As shown, let A, B, and C be three random measuring points on the inner surface of the cylinder obtained by measurement, and the coordinates of the three measuring points A, B, and C are A: (x1, y1), B: (x2, y2), and C: (x3, y3);

[0066] 4-1-2) Connect AB and BC, and make the perpendicular bisector L1 of AB and the perpendicular bisector L2 of BC. Then L1 and L2 can be expressed as:

[0067]

[0068]

[0069] 4-1-3) Let L1 = L2, and the coordinates of the center of the circle O: (x, y) are expressed as:

[0070]

[0071]

[0072] 4-1-4) Calculate the diameter D of the circle determined by the three measuring points A, B, and C i, i represents the calculated diameter number, diameter D i The calculation expression is:

[0073]

[0074] 4-2) Set the judgment criteria according to the roundness specification of the cylinder of the wind turbine, and determine the three coordinate points that meet the judgment criteria as qualified points.

[0075] In step 4-2), the judgment criteria are:

[0076] like Figure 8 As shown in the figure, according to the requirements of GB / T19072 "Wind Turbine Tower", the roundness tolerance requirements for any section of the cylinder are:

[0077] (D max -D min ) / D min ≤0.01 (6)

[0078] D max D is the maximum diameter measured; min is the minimum diameter measured; D non Design the diameter of the cylinder to be tested;

[0079] According to the roundness specification of the cylinder of the wind turbine, when the diameter calculation difference is less than 1% of the design diameter of the cylinder being tested, the area is qualified, and the three measuring points involved in the calculation are all qualified points, namely:

[0080] (D i -D non ) / D non ≤0.01 (7)

[0081] If the calculated diameter difference is greater than 1% of the designed diameter of the tested cylinder, the area is temporarily determined as an abnormal area. If any of the three measuring points involved in the calculation have been previously judged as qualified points, they are still considered qualified points. The remaining measuring points are judged as abnormal points, and the area formed by adjacent abnormal points is judged as an abnormal area.

[0082] 4-3) Repeat steps 4-1) and 4-2), traverse all combinations of selecting 3 measuring points from n measuring points, and obtain all qualified points. The remaining points other than the qualified points are judged as abnormal points, and the area formed by adjacent abnormal points is the roundness abnormal area.

[0083] In step 4-3), each combination is calculated to obtain a diameter D i , the diameter D is calculated according to the number of different measuring points n i , by calculating the combination number formula The diameter calculation quantity is:

[0084]

[0085] Example

[0086] 1. CAD simulation and result analysis of abnormal area:

[0087] In order to study the location of the unfavorable point of the cylinder after it is damaged, an abnormal area is taken as an example and the abnormal area detection and identification process is simulated by CAD, as shown in Table 1.

[0088] Table 1 A roundness abnormal area detection process

[0089]

[0090] The quick identification process is as follows:

[0091] (1) Take 8 points on average in the cylinder, there are 56 cases in total. The following are representative cases: Fig. 9 For example;

[0092] (2) Fig. 9 The solid circle in the middle is the section of the cylinder that has not been damaged. Assume that the design diameter of the cylinder being tested is 200. The dotted semicircle is the section of the cylinder that is deformed after being damaged. Assume that the diameter of the section after being damaged is 200.4. The solid line is the line connecting the three coordinates, and the dotted line is the perpendicular bisector of the two connecting lines.

[0093] (3) Fig. 9 As shown in (a), the diameter obtained by combining points 5, 6, and 8 is 200, which is equal to the design diameter of the cylinder being tested (there is an error in actual engineering, that is, the point that is less than 1% of the design diameter of the cylinder being tested is considered a qualified point), which means that points 5, 6, and 8 are qualified points;

[0094] (4) Similarly, Fig. 9 Points 1, 6, and 7 in (b) are qualified points;

[0095] (5) Fig.10 As shown in (a), the diameter obtained by combining points 1, 2, and 8 is 215.9, which is larger than the designed diameter of the cylinder being tested. The error is 8.0%, indicating that there is an abnormal point. Fig. 9 (a) Fig. 9 (b) It can be seen that points 1, 5, 6, 7, and 8 are qualified points. Excluding the qualified points means that point 2 is an abnormal point.

[0096] (6) Similarly, Fig.10 (b) Fig.10 Points 3 and 4 in (c) are the locations of outliers.

[0097] CAD simulation and result analysis of multiple abnormal areas:

[0098] Large diameter cylinders may have multiple abnormal points due to machining errors, and the above method can also be used to find the location of unfavorable points. Here we take two abnormal areas as an example, such as Fig.11 As shown in Table 2, CAD is used to simulate the abnormal area detection and identification process.

[0099] Table 2 Multiple roundness anomaly area detection methods

[0100]

[0101] Analysis of test results with increased measurement point density:

[0102] Sometimes there are abnormal areas in large diameter cylinders. Because too few points are taken on large diameter cylinders, the abnormal areas cannot be detected, such as Fig.12 (a) As shown in Figure 2, this problem can be solved by increasing the number of measuring points, as follows.

[0103] (1) Take 16 and 8 points on average in the cylinder respectively, assuming that the design diameter of the cylinder to be tested is 200;

[0104] (2) Fig.12 As shown in (a), the diameter obtained by combining points 1, 2, and 3 is 200, which is equal to the design diameter of the cylinder being tested, and the error is 0, indicating that points 1, 2, and 3 are qualified points, while the area composed of points 1, 2, and 3 has an abnormal area;

[0105] (3) Fig.12 As shown in (b), the diameter obtained by combining points 2, 4, and 6 is 185.4, which is smaller than the designed diameter of the cylinder being tested, and the error is 7.3%, indicating that there is an abnormal point here.

[0106] The results of the above CAD simulation examples show that increasing the density of measuring points can greatly improve the accuracy of detecting abnormal areas. The greater the density of measuring points, the higher the accuracy of detection.

Claims

1. A method for rapid detection of abnormal roundness of large diameter cylinders, characterized in that: The following steps are involved: Step 1: Place the three frames in the cylinder, place the total station on the tripod, and after debugging is normal, adjust the objective lens of the total station to a horizontal level; Step 2: Use the laser non-contact measurement mode of the total station to automatically and evenly determine n measuring points along the 360° direction on the inner surface of the cylinder; In step 2, the measurement accuracy can be improved by increasing the number of measurement points; Step 3: Establish a measuring station through the backsight point, establish a coordinate system, and determine the coordinates of each measuring point; Step 4: Automatically calculate the roundness based on the obtained measuring point coordinates to obtain the roundness detection result, and output the roundness of the large-diameter cylinder, the coordinates of the roundness abnormal point and the roundness abnormal area; The specific process of step 4 is as follows: 4-1) Select 3 measuring point coordinates from all the measuring point coordinates as a group, and calculate all the circle centers and diameters according to the three-coordinate measurement method; 4-2) Set the judgment standard according to the roundness specification of the cylinder of the wind turbine, and determine the three coordinate points that meet the judgment standard as qualified points; In step 4-2), the judgment criteria are: According to the requirements of GB / T19072 "Wind Turbine Tower", the roundness tolerance requirements for any section of the cylinder are: (D max -D min ) / D min ≤0.01 (6) D max D is the maximum diameter measured; min is the minimum diameter measured; D non Design the diameter of the cylinder to be tested; According to the roundness specification of the cylinder of the wind turbine, when the diameter calculation difference is less than 1% of the design diameter of the cylinder being tested, the area is qualified, and the three measuring points involved in the calculation are all qualified points, namely: (D i -D non ) / D non ≤0.01 (7) If the calculated diameter difference is greater than 1% of the designed diameter of the cylinder being tested, the area is temporarily determined as an abnormal area. If any of the three measuring points involved in the calculation is previously judged as a qualified point, it is still considered a qualified point, and the remaining measuring points are judged as abnormal points. The area formed by adjacent abnormal points is judged as an abnormal area; 4-3) Repeat steps 4-1) and 4-2), traverse all combinations of selecting 3 measuring points from n measuring points, obtain all qualified points, and the remaining points other than the qualified points are judged as abnormal points. The area formed by adjacent abnormal points is the roundness abnormal area; In step 4-3), each combination is calculated to obtain a diameter D i , the diameter D is calculated according to the number of different measuring points n i , by calculating the combination number formula The diameter calculation quantity is:

2. The rapid detection method for abnormal roundness of a large diameter cylinder according to claim 1 is characterized in that: In step 4-1), the measurement process of the three-coordinate measurement method is as follows: 4-1-1) Let A, B, and C be three random measurement points on the inner surface of the cylinder obtained through measurement. The coordinates of the three measurement points A, B, and C are A: (x1, y1), B: (x2, y2), and C: (x3, y3); 4-1-2) Connect AB and BC, and make the perpendicular bisector L1 of AB and the perpendicular bisector L2 of BC. Then L1 and L2 can be expressed as: 4-1-3) Let L1 = L2, and the coordinates of the center of the circle O: (x, y) are expressed as: 4-1-4) Calculate the diameter D of the circle by measuring the three points A, B, and C i , i represents the calculated diameter number, diameter D i The calculation expression is:

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