Cylindrical workpiece inner diameter detection device and detection method

Abstract

A sensor laser source, a first plane mirror, a second mirror and a sensor receiver are sequentially arranged along a light path direction, the first plane mirror changes an initial light path to enable primary reflection laser to enter a to-be-detected cylindrical workpiece, the second mirror is located in the to-be-detected cylindrical workpiece, and the sensor receiver is located in the to-be-detected cylindrical workpiece to enable the primary reflection laser to enter the to-be-detected cylindrical workpiece. The primary reflection laser is subjected to secondary reflection to the inner side wall of the to-be-detected cylindrical workpiece to obtain tertiary reflection laser, the tertiary reflection laser is received and subjected to quartic reflection, and the quartic reflection laser enters a sensor receiver. The invention further provides a detection method based on the cylindrical workpiece inner diameter detection device. Through the design of the device for detecting the inner diameter of the cylindrical workpiece and the corresponding testing method, the problem that the point laser displacement sensor cannot receive returned light when a workpiece with a small size or a large size is processed is solved, and the applicability and the stability of testing are improved.

Description

Technical Field

[0001] The invention relates to the field of measurement technology, and in particular to a cylindrical workpiece inner diameter detection device and a detection method. Background Art

[0002] In modern industrial production, the measurement of cylindrical workpieces is particularly important. Such workpieces include but are not limited to pipes, hubs, and hole parts. With the continuous complexity and precision of mechanical equipment, the requirements for workpiece inspection are also continuously increasing. Especially in the measurement of inner diameter, sometimes the accuracy requirement even reaches the millimeter level or higher. In addition, the detection of inner surface defects and whether the workpiece is deformed have also become key factors that cannot be ignored. Therefore, it is particularly important to accurately and efficiently detect parameters such as the inner diameter of the workpiece.

[0003] Among many measurement methods, non-contact measurement technology is widely used because it can avoid damage or deformation caused by direct contact with the workpiece. However, in practical applications, due to the difference in workpiece size, point laser displacement sensors often face many challenges in the data acquisition process. For example, when the workpiece is large and the measurement accuracy is high, the high-precision point laser displacement sensor may encounter the problem of insufficient distance measurement; when dealing with smaller workpieces, the limitation of the measurement space may make it impossible to adjust the distance between the sensor and the workpiece to the effective working range. Therefore, the CMOS sensor may not be able to receive the returned light signal.

[0004] In view of the above challenges, we urgently need a new type of measurement device that can effectively solve the difficulties brought by measuring under different sizes and environmental conditions. This device should not only have high accuracy and high efficiency, but also be flexible to adapt to a variety of sizes to ensure reliable detection results in various complex situations. Summary of the invention

[0005] In order to solve the problems of the prior art, the present invention proposes a cylindrical workpiece inner diameter detection device and a detection method. The introduction of the cylindrical workpiece inner diameter detection device solves the problem that traditional detection devices are difficult to adapt to the detection of cylindrical workpieces of different sizes. Based on the cylindrical workpiece inner diameter detection device proposed in this scheme, we also propose a detection method with high adaptability, which further improves the accuracy of detection.

[0006] In the first aspect, the present invention proposes a cylindrical workpiece inner diameter detection device, which is characterized in that it includes a sensor laser source 1, a first plane reflector 2, a second reflector 3 and a sensor receiver 4 in sequence along the optical path direction; wherein:

[0007] The sensor laser source 1 and the sensor receiver 4 are located outside the cylindrical workpiece to be measured;

[0008] The first plane mirror 2 will change the initial optical path generated by the sensor laser source 1, so that the initially reflected laser enters the cylindrical workpiece to be measured;

[0009] The second mirror 3 is located inside the cylindrical workpiece to be measured, and the initially reflected laser is reflected twice to the inner side wall of the cylindrical workpiece to be measured to obtain the three - times reflected laser, and the three - times reflected laser is received and reflected four times, so that the four - times reflected laser enters the sensor receiver 4.

[0010] As a further solution, the included angle between the second mirror 3 and the central axis of the cylindrical workpiece to be measured is α 2 , α 2 is not equal to 0.

[0011] As a further solution, the α 2 is equal to 45 degrees.

[0012] As a further solution, the first plane mirror 2 and / or the second mirror 3 is a plane mirror.

[0013] As a further solution, a rotating table is provided at the bottom of the second mirror.

[0014] As a further solution, the included angle between the first plane mirror 2 and the central axis of the cylindrical workpiece to be measured is less than the included angle between the laser beam and the central axis of the cylindrical workpiece to be measured and less than 90 degrees.

[0015] As a further solution, the sensor receiver 4 can select any one of a CMOS sensor, a CCD sensor, and a photoelectric sensor to receive the four - times reflected laser.

[0016] In a second aspect, the present solution also proposes a method for detecting the inner diameter of a cylindrical workpiece, and the specific steps are as follows:

[0017] S1: Parameter definition: Set the reflection point of the laser generated by the sensor laser source 1 on the first plane mirror 2 as the first reflection point O 1 , set the reflection point of the initially reflected laser on the second mirror 3 as the second reflection point O, measure the vertical distance a from the sensor laser source 1 to the horizontal direction of O, measure the vertical distance b from O 1 to the horizontal direction of O, measure the included angle α 1 between the laser beam generated by the sensor laser source 1 and the central axis of the cylindrical workpiece, measure the included angle β between the first plane mirror 2 and the central axis of the cylindrical workpiece to be measured, and the point laser displacement sensor outputs the displacement L;

[0018] S2: Construct the distance formula from point O to the contour of the cylindrical workpiece to be measured:

[0019] ρ = L * cos(2β - α 1 ) - a * secα1 *cos(2β-α 1 )+b*secα 1 *cos(2β-α 1 )-b;

[0020] Among them, ρ is the distance from point O to the contour of the cylindrical workpiece to be measured;

[0021] S3: The inner diameter detection device of the cylindrical workpiece to be measured is rotated horizontally with point O as the center to obtain the distance and angle from the contour of the cylindrical workpiece to be measured to point O, which is recorded as the contour data set, and Cartesian coordinates are established with point O as the origin. The contour data set is substituted into the polar coordinate formula (ρ n cos a,ρ n sin a) to obtain the contour coordinate group, divide the contour coordinate group into at least 3 equal subsets according to the angle order, arbitrarily select three non-repeating subsets and randomly extract a contour point from each of them, and obtain the center coordinates of the three contour points. After repeating N times, a center coordinate group containing N center coordinates is obtained, where N is a natural number greater than 0, n represents the nth contour point, and a n represents the angle of the nth contour point, ρ n Indicates the distance from the nth point O to the contour of the cylindrical workpiece;

[0022] S4: The center coordinate group, Threshold, EPS, and Minpts threshold are input through the DBSCAN clustering algorithm to judge and output the cylindrical workpiece state and the precise center coordinates of the qualified cylindrical workpiece, and calculate and output the cylindrical workpiece radius group.

[0023] As a further solution, the steps to obtain the coordinates of the center of the three-point contour point are:

[0024] First, extract any contour point, identify the subset group number to which the contour point belongs, remove the subset, and continue to randomly extract any contour point until the coordinates A of the three contour points are obtained. a (x a ,y a ), Ab(x b ,y b ), A c (x c ,y c ), where a, b, and c are arbitrary angles;

[0025] Then, let the coordinates of the center of the circle be (h, k) and the radius be r, and substitute the coordinates of the contour points into the equation of the circle to obtain a system of linear equations:

[0026] Find the coordinates of the center of the circle (h, k).

[0027] As a further solution, the steps to obtain Threshold are as follows: according to the simulation data of the inner diameter of the cylindrical workpiece, set the test accuracy and maximum error; repeat S1-S2 to obtain the circle center coordinate group, first set the Minpts threshold to twice the dimension of the data set, and the K value to Minpts threshold-1, and obtain the EPS value through the K-distance graph of the circle center coordinate group, input the circle center coordinate group, EPS, and Minpts threshold into the DBSCAN clustering algorithm, and obtain the percentage of the largest cluster to the total number of points, which is the Threshold, where the K value represents the number of nearest neighbors considered when calculating the K-distance of each point;

[0028] As a further solution, the steps to obtain the EPS value through the K-distance graph are: calculate the distances of all points to their kth nearest neighbors and sort them, draw the sorted K-distance graph, and the value of the inflection point of the curve is the EPS value.

[0029] As a further solution, the center coordinates of the cylindrical workpiece are output through the following steps: determine whether the percentage of the number of center coordinate points in the largest cluster output by the DBSCAN clustering algorithm to the total number of center coordinate points is greater than the Threshold. If it is greater, output the center coordinates of the densest point in the largest cluster as the center coordinates of the cylindrical workpiece.

[0030] As a further solution, the radius of the cylindrical workpiece is given by the formula Calculate and obtain the cylindrical workpiece radius data set, remove outliers, and then find the average value of the cylindrical workpiece radius data set, which is the cylindrical workpiece radius, where r is the cylindrical workpiece radius, x a is the horizontal coordinate of any contour point, y a is the ordinate of any contour point, x b is the horizontal coordinate of the center of the cylindrical workpiece, y b is the ordinate of the center of the cylindrical workpiece.

[0031] As a further solution, when outputting the state of the cylindrical workpiece, first check whether the percentage of the number of circle center coordinate points in the largest cluster to the total number of circle center coordinate points is greater than the Threshold. If it is greater, the cylindrical workpiece is considered qualified; otherwise, the cylindrical workpiece is considered deformed.

[0032] As a further solution, when the cylindrical workpiece inner diameter detection method detects planes at different heights, first, M planes are selected from the cylindrical workpiece for detection, where M is a natural number greater than 1. If all M planes are qualified, the cylindrical workpiece is considered qualified; if any plane P is unqualified, the plane P needs to be re-detected, and the plane P above it is extracted according to the set accuracy. 1 and the lower plane P 2 If plane P, upper plane P 1 and the lower plane P 2If all the planes are qualified, the cylindrical workpiece is judged to be qualified; if any one of the planes is unqualified, the cylindrical workpiece is judged to be unqualified;

[0033] In the cylindrical workpiece judged as unqualified, if the upper plane P 1 and the lower plane P 2 If the upper plane P 1 and the lower plane P 2 If all of them are unqualified, the cylindrical workpiece is regarded as a deformed cylindrical workpiece. 1 Or the lower plane P 2 If any one of the planes is qualified, the upper and lower planes of the unqualified plane will be sampled again for inspection according to the accuracy requirements. If both the upper and lower planes are qualified, it is determined to be a defective cylindrical workpiece; if any one of the upper and lower planes is unqualified, it is determined to be a deformed cylindrical workpiece.

[0034] Beneficial Effects

[0035] In this solution, we have successfully solved the problem that the sensor receiver 4 cannot receive the return light when processing small or large workpieces by carefully configuring the first plane reflector 2 and the second reflector 3 and formulating corresponding test methods. This progress fully ensures the applicability and stability of the entire measurement system on workpieces of different sizes.

[0036] Specifically, the setting of the first plane reflector 2 changes the initial optical path, so that the light can enter the interior of the cylindrical workpiece to be measured at a better angle. At the same time, the second reflector 3 ensures that the incoming light can fall on the inner surface of the cylindrical workpiece to be measured, and receives the return light to smoothly return to the sensor receiver 4. This series of designs and configurations enables high-precision detection on workpieces that could not be accurately measured in the past. Furthermore, we have further optimized the detection technology and improved the flexibility and accuracy of detection by designing a detection method specifically for the inner diameter detection device of cylindrical workpieces.

[0037] Through these technical improvements, we not only overcome the impact of size limitations on measurement capabilities, but also significantly expand our measurement capabilities and application scenarios within different workpiece size ranges. This means that whether in industrial production, quality control, or scientific research experiments, we can more flexibly deal with workpieces of various sizes and shapes, provide more accurate and reliable measurement results, and thus improve the application value and efficiency of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0039] Figure 1 Schematic diagram of the optical path and auxiliary lines of the cylindrical workpiece inner diameter detection device in Embodiment 1;

[0040] Figure 2 Schematic diagram of the optical path and auxiliary lines of the cylindrical workpiece inner diameter detection device in Embodiment 2;

[0041] Figure 3 Schematic diagram of the optical path and auxiliary lines of Comparative Example 1;

[0042] Figure 4 Schematic diagram of the optical path and auxiliary lines of Comparative Example 4;

[0043] Figure 5 Schematic diagram of the detection of the standard cylindrical workpiece in Embodiment 1.

[0044] Where 1 - laser; 2 - first plane mirror; 3 - second mirror; 4 - point laser displacement sensor; 5 - cylindrical workpiece to be measured. Specific implementation manners

[0045] For the convenience of understanding, the present invention will be described more comprehensively below, and embodiments of the present invention are given, but the scope of the present invention is not limited thereby.

[0046] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0047] In the first aspect, the present solution proposes a cylindrical workpiece inner diameter detection device, which is characterized in that, along the optical path direction, it sequentially includes a sensor laser source 1, a first plane mirror 2, a second mirror 3 and a sensor receiver 4; where:

[0048] The sensor laser source 1 and the sensor receiver 4 are located outside the cylindrical workpiece to be measured;

[0049] The first plane mirror 2 changes the initial optical path generated by the sensor laser source 1, so that the initially reflected laser enters the inside of the cylindrical workpiece to be measured;

[0050] The second mirror 3 is located inside the cylindrical workpiece to be measured, and reflects the initially reflected laser twice to the inner side wall of the cylindrical workpiece to be measured to obtain a three - times reflected laser, and receives the three - times reflected laser for a fourth reflection, so that the four - times reflected laser enters the sensor receiver 4.

[0051] In the actual detection process, we often face the situation that the distance between the sensor and the workpiece cannot be adjusted to the range due to insufficient distance measurement or inability to adjust the distance between the sensor and the workpiece to within the distance measurement range. Therefore, we carefully set the first plane reflector 2 and the second reflector 3 to solve the problem that the sensor receiver 4 cannot receive the return beam. With the cooperation of the first plane reflector 2 and the second reflector 3, the laser beam is smoothly introduced into the interior of the cylindrical workpiece to be measured and falls on the inner wall of the cylindrical workpiece to be measured, and then returns to the sensor receiver 4; the setting of the first plane reflector 2 ensures that the laser beam is introduced into the interior of the cylindrical workpiece to be measured. Combined with the carefully set second reflector 3, this solution solves the problem that the traditional measuring device cannot measure the cylindrical workpiece whose inner diameter exceeds or is less than the test range, thereby improving the flexibility of the optical path and the accuracy of the measurement. Further, after three reflections, the laser beam enters the sensor receiver 4 after four reflections, thereby realizing the accurate measurement of the inner diameter. With the cooperation of the first reflector and the second reflector, we solved the problem that the sensor receiver 4 cannot receive the return beam, improved the accuracy of the entire inner diameter detection device, and provided reliable technical support for high-precision industrial measurement.

[0052] As a further solution, the angle between the second reflector 3 and the central axis of the cylindrical workpiece to be measured is α 2 , α 2 Not equal to 0.

[0053] As a further solution, the α 2 Equal to 45 degrees to ensure the optimal propagation path of the laser inside the cylindrical workpiece to be measured, thereby improving the accuracy and reliability of inner diameter measurement.

[0054] As a further solution, the first plane reflector 2 and / or the second reflector 3 is a plane reflector.

[0055] As a further solution, the angle between the first plane reflector 2 and the central axis of the cylindrical workpiece to be measured is smaller than the angle between the laser beam and the central axis of the cylindrical workpiece to be measured and smaller than 90 degrees to ensure that the laser beam falls on the first plane reflector 2.

[0056] As a further solution, a rotating platform is provided at the bottom of the second reflecting mirror 3 .

[0057] As a further solution, the sensor receiver 4 can select any one of a CMOS sensor, a CCD sensor, and a photoelectric sensor to receive the four-times reflected laser.

[0058] Secondly, this scheme also proposes a method for detecting the inner diameter of a cylindrical workpiece, and the specific steps are as follows:

[0059] S1: Parameter definition: Set the reflection point of the laser generated by the sensor laser source 1 on the first plane reflector 2 to be the first reflection point O1 , set the reflection point of the first reflected laser on the second reflector 3 as the second reflection point O, measure the vertical distance a from the sensor laser source 1 to O in the horizontal direction, and measure O 1 The vertical distance b to the horizontal direction of O, the angle α between the laser beam generated by the sensor laser source 1 and the center axis of the cylindrical workpiece 1 , measure the angle β between the first plane reflector 2 and the central axis of the cylindrical workpiece to be measured, and the point laser displacement sensor outputs the displacement L;

[0060] S2: Construct the distance formula from point O to the contour of the cylindrical workpiece to be measured:

[0061] ρ=L*cos(2β-α 1 )-a*secα 1 *cos(2β-α 1 )+b*secα 1 *cos(2β-α 1 )-b;

[0062] Among them, ρ is the distance from point O to the contour of the cylindrical workpiece to be measured;

[0063] S3: The inner diameter detection device of the cylindrical workpiece to be measured is rotated horizontally with point O as the center to obtain the distance and angle from the contour of the cylindrical workpiece to be measured to point O, which is recorded as the contour data set, and Cartesian coordinates are established with point O as the origin. The contour data set is substituted into the polar coordinate formula (ρ n cos a n , ρ n sin a n ) to obtain a contour coordinate group, divide the contour coordinate group into at least 3 equal subsets according to the angle order, arbitrarily select three non-repeating subsets and randomly extract a contour point from each of them, and obtain the center coordinates of the three contour points. After repeating N times, a center coordinate group containing N center coordinates is obtained, where N is a natural number greater than 0, n represents the nth contour point, and a n represents the angle of the nth contour point, ρ n Indicates the distance from the nth point O to the contour of the cylindrical workpiece;

[0064] S4: The center coordinate group, Threshold, EPS, and Minpts threshold are input through the DBSCAN clustering algorithm to judge and output the cylindrical workpiece state and the precise center coordinates of the qualified cylindrical workpiece, and calculate and output the cylindrical workpiece radius group.

[0065] The displacement L returned by the cylindrical workpiece inner diameter detection device proposed in this scheme needs further processing. Figure 1 The optical path of the cylindrical workpiece inner diameter detection device proposed in this scheme is shown, as well as the idea of ​​constructing the distance formula proposed in step S2. Figure 1 In the example, S is the light source, S' is the mirror image point of S, and O 1 , O`, O``, are respectively the reflection points on the first plane reflector 1MN and the second reflector 2PQ, A is the point where the light hits the inner surface of the cylindrical workpiece to be measured, A` is the mirror point of A, and B is the point where the light falls on the sensor receiver 4;

[0066] According to the mirror symmetry point obtained by the secondary mirror restoration and the optical principle, the displacement L output by the sensor at this time is the length of S`A`, SD is the height difference from the light source S to the reflection point O, O`E is the height difference from the first reflection point O` to the second reflection point O, and the angle ∠DSO` is recorded as α. In S1, we have obtained the length of SD, O`E and α 1 and β parameters, at this time, if we take any point O on the second reflector 3, the distance OC from O to AC is the data we need;

[0067] First, extend SO` to intersect CD at point F, draw lines SG and SG` parallel to MN through S and S` respectively, draw a line S`H parallel to SD and MI through S`, and draw a perpendicular line OJ through O to CD.

[0068] In △SDF, SD = a, ∠DSF = α, ∠D = 90°;

[0069] ∴SF=SD*secα=a*secα, ∠SFD=90°-α;

[0070] In △O`EF, O`E=b, ∠SFD=90°-α, ∠O`EF=90°;

[0071] ∴O`F=O`E*csc(90°-α)=b*csc(90°-α);

[0072] ∴SO`=SF-O`F=a*secα-b*csc(90°-α);

[0073] From the symmetry, it is easy to obtain: S`O`=SO`=a*secα-b*csc(90°-α);

[0074] Again∵S`H∥MI, S`G`∥MO`;

[0075] ∴∠HS`G`=∠IMO`=β;

[0076] Similarly, we can get: ∠DSG=β, then ∠GSO`=α-β;

[0077] From the symmetry, it is easy to get: ∠O`S`G`=GSO`=α-β;

[0078] Then ∠HS`O`=β-(α-β)=2β-α;

[0079] Again∵S`H∥O`E;

[0080] ∴∠EO`O=∠HS`O`=2β-α;

[0081] In △EO`O, O`E=b, ∠EO`O=2β-α, ∠O`EO=90°;

[0082] ∴O`O=O`E*sec(2β-α)=b*sec(2β-α);

[0083] Then, from the symmetric relationship and the above derivation, it is easy to obtain: OA = OA` = S`A`-S`O`-O`O = L-[a*secα-b*csc(90°-α)]-b*sec(2β-α);

[0084] From the symmetry, it is easy to get: ∠AOC=∠O`OJ, and from OJ∥O`E, we can know that ∠O`OJ=∠EO`O;

[0085] ∴∠AOC=2β-α, combined with △AOC, OA and ∠C are known, we can get:

[0086] OC=OA*cos∠AOC=ρ

[0087] =[La*secα+b*csc(90°-α)-b*sec(2β-α)]*cos(2β-α)

[0088] =L*cos(2β-α)-a*secα*cos(2β-α)+b*secα*cos(2β-α)-b;

[0089] At this time, the distance ρ from point O to the contour of the cylindrical workpiece to be measured is obtained.

[0090] On this basis, we further established a coordinate system with point O as the coordinate origin and constructed a center coordinate group. By combining the center coordinate group with the DBSCAN clustering algorithm, we finally obtained the center coordinates and radius of the cylindrical workpiece to be measured.

[0091] As a further solution, the steps to obtain the coordinates of the center of the three-point contour point are:

[0092] First, extract any contour point, identify the subset group number to which the contour point belongs, remove the subset, and continue to randomly extract any contour point until the coordinates A of the three contour points are obtained. a (x a ,y a ), Ab(x b ,y b ), A c (x c ,yc ), where a, b, and c are arbitrary angles;

[0093] Then, let the center of the circle be (h, k) and the radius be r, and substitute the coordinates of the contour points into the equation of the circle to obtain the linear equation system:

[0094] Find the coordinates of the center of the circle (h, k).

[0095] As a further solution, the steps to obtain Threshold are as follows: according to the simulation data of the inner diameter of the cylindrical workpiece, set the test accuracy and maximum error; repeat S1-S2 to obtain the circle center coordinate group, first set the Minpts threshold to twice the dimension of the data set, and the K value to Minpts threshold-1, and obtain the EPS value through the K-distance graph, and input the circle center coordinate group, EPS, and Minpts threshold into the DBSCAN clustering algorithm to obtain the percentage of the largest cluster to the total number of points, which is the Threshold, where the K value represents the number of nearest neighbors considered when calculating the K-distance of each point;

[0096] As a further solution, the steps to obtain the EPS value through the K-distance graph are: calculate the distances of all points to their kth nearest neighbors and sort them, draw the sorted K-distance graph, and the value of the inflection point of the curve is the EPS value.

[0097] As a further solution, the center coordinates of the cylindrical workpiece are output through the following steps: judging whether the percentage of the center coordinate points in the largest cluster output by the DBSCAN clustering algorithm to the total center coordinate points is greater than the Threshold, if so, outputting the center coordinates of the densest point in the largest cluster as the center coordinates of the cylindrical workpiece;

[0098] As a further solution, the radius of the cylindrical workpiece is given by the formula Calculate and obtain the cylindrical workpiece radius data set, remove outliers, and then find the average value of the cylindrical workpiece radius data set, which is the cylindrical workpiece radius, where r is the cylindrical workpiece radius, x a is the horizontal coordinate of any contour point, y a is the ordinate of any contour point, x b is the horizontal coordinate of the center of the cylindrical workpiece, y b is the ordinate of the center of the cylindrical workpiece.

[0099] As a further solution, when outputting the state of the cylindrical workpiece, first check whether the percentage of the number of circle center coordinate points in the largest cluster to the total number of circle center coordinate points is greater than the Threshold. If it is greater, the cylindrical workpiece is considered qualified, otherwise, the cylindrical workpiece is considered deformed.

[0100] When the cylindrical workpiece inner diameter detection method detects planes at different heights, first, M planes are selected from the cylindrical workpiece for detection, where M is a natural number greater than 1. If all M planes are qualified, the cylindrical workpiece is considered qualified; if any plane P is unqualified, the plane P needs to be re-detected, and the plane P above it is extracted according to the set accuracy. 1 and the lower plane P 2 If plane P, upper plane P 1 and the lower plane P 2 If all the planes are qualified, the cylindrical workpiece is judged to be qualified; if any one of the planes is unqualified, the cylindrical workpiece is judged to be unqualified;

[0101] In the cylindrical workpiece judged as unqualified, if the upper plane P 1 and the lower plane P 2 If the upper plane P 1 and the lower plane P 2 If all of them are unqualified, the cylindrical workpiece is regarded as a deformed cylindrical workpiece. 1 Or the lower plane P 2 If any one of the planes is qualified, the upper and lower planes of the unqualified plane will be sampled again for inspection according to the accuracy requirements. If both the upper and lower planes are qualified, it is determined to be a defective cylindrical workpiece; if any one of the upper and lower planes is unqualified, it is determined to be a deformed cylindrical workpiece.

[0102] Example 1

[0103] The cylindrical workpiece inner diameter detection device detects larger cylindrical workpieces.

[0104] A CMOS sensor is used as the sensor receiver 4, and the inner diameter optical path diagram of a cylindrical workpiece with a large size is detected by a cylindrical workpiece inner diameter detection device. Figure 1 , where S is the light source, S' is the mirror point of S, and O 1 , O`, O``, are respectively the reflection points on the first plane reflector 1MN and the second reflector 2PQ, A is the point where the light hits the inner surface of the cylindrical workpiece to be measured, A` is the mirror point of A, and B is the point where the light falls on the sensor receiver 4;

[0105] The SD was measured as a, O 1 O is b, ∠DSO 1 =α 1 , the angle between the first plane reflector 2 and the central axis of the cylindrical workpiece to be measured is β.

[0106] Construct the distance formula from point O to the contour of the cylindrical workpiece to be measured:

[0107] ρ=L*cos(2β-α 1)-a*secα 1 *cos(2β-α 1 )+b*secα 1 *cos(2β-α 1 )-b, and find ρ.

[0108] like Figure 5 As shown in the figure, a point is randomly selected in the cylindrical workpiece and recorded as point O. The point laser displacement sensor tests the distance from point O to the contour every time it rotates one degree. After one rotation, a total of 360 distances ρ from point O to the contour of the cylindrical workpiece are obtained. The obtained contour data group is recorded as the contour data group [ρ 1 , 2 、······ρ 360 ], import the contour data set and point O into the computer, and establish a Cartesian coordinate system with point O as the origin of the coordinate system, and bring the angle and contour data set into the polar coordinate formula (ρ n cos a n , ρ n sina n ), and obtain the contour coordinate group [A 1 (ρ 1 cos1°,ρ 2 sin1°), A 2 (ρ 2 cos2°,ρ 2 sin2°)、···A 360 (ρ 360 cos360°, ρ 360 sin360°)];

[0109] The contour coordinate group is divided into twelve subsets at every 30°, denoted as group 1, group 2, ..., group 12, and a contour point A is randomly selected from the twelve groups. 57 ((ρ 57 cos57°,ρ 57 sin57°), identify group number 2, and extract the next contour point A from the remaining groups 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 129 ((ρ 129 cos129°,ρ 129 sin129°)) identifies the group number as group 5, and extracts the third contour point A from the remaining groups 1, 3, 4, 6, 7, 8, 9, 10, 11, and 12 243 ((ρ 243 cos243°,ρ 243 sin243°)), A 57 ((ρ 57 cos57°,ρ 57sin57°))、A 129 ((ρ 129 cos129°,ρ 129 sin129°))、A 243 ((ρ 243 cos243°,ρ 243 Sin243°)) is substituted into the circle equation, and the center of the circle is set to B. 1 (h 1 ,k 1 ), with a radius of r 1 , we obtain the system of equations:

[0110]

[0111] Use the matrix to find the coordinates of the center of the circle as B 1 (h 1 , k 1 ), repeatedly extract 1000 groups of three contour points to obtain a circle center coordinate group consisting of 1000 circle center points with known coordinates [B 1 (h 1 , k 1 ), B 2 (h 2 , k 2 )``````B 1000 (h 1000 , k 1000 )] Set K to 3, set Minpts to 4, and Threshold to 95%, draw the K distance graph of the circle center coordinate group to obtain EPS, and use the DBSCAN clustering algorithm to process the circle center coordinate group [B 1 (h 1 , k 1 ), B 2 (h 2 , k 2 )``````B 1000 (h 1000 , k 1000 )], and obtain the largest cluster, and calculate the ratio of the number of points in the largest cluster to the total number of points.

[0112] If the ratio is greater than 95%, the center coordinates (x 心 ,y 心 ), the center coordinate (x 心 ,y 心 ) and contour coordinate group [A 1 (ρ 1 cos1°,ρ 2 sin1°), A 2 (ρ 2 cos2°,ρ 2 sin2°)、···A 360(ρ 360 cos360°, ρ 360 sin360°)] into the formula Obtain the cylindrical workpiece radius data set (r 1 、r 2 、r 3 ······、r 360 ), remove z outliers, Output the radius r of the cylindrical workpiece.

[0113] Example 2

[0114] The cylindrical workpiece inner diameter detection device detects cylindrical workpieces with smaller sizes.

[0115] The test steps of Example 2 are the same as those of Example 1, except that the optical path diagram for detecting the inner diameter of a cylindrical workpiece with a smaller size is different. Figure 2 , where S is the light source, S` is the mirror point of S, O1, O`, O`` are respectively the reflection points on the first plane reflector 1MN and the second reflector 2PQ, A is the point where the light hits the inner surface of the cylindrical workpiece to be measured, A` is the mirror point of A, and B is the point where the light falls on the sensor receiver 4;

[0116] It is measured that SD is a, O1O is b, ∠DSO1=α1, and the angle between the first plane reflector 2 and the central axis of the cylindrical workpiece to be measured is β.

[0117] The SD was measured as a, O 1 O is b, ∠DSO 1 =α 1 , the angle between the first plane reflector 2 and the central axis of the cylindrical workpiece to be measured is β.

[0118] Construct a distance formula from point O to the contour of the cylindrical workpiece to be measured, and the derivation process is the same as in Example 1:

[0119] ρ=L*cos(2β-α 1 )-a*secα 1 *cos(2β-α 1 )+b*secα 1 *cos(2β-α 1 )-b, and find ρ.

[0120] A point is randomly selected in the cylindrical workpiece and recorded as point O. The laser displacement sensor measures the distance from point O to the contour every time it rotates one degree. After one rotation, a total of 360 distances ρ from point O to the contour of the cylindrical workpiece are obtained. The obtained contour data group is recorded as the contour data group [ρ 1 , 2 、······ρ 360], import the contour data set and point O into the computer, and establish a Cartesian coordinate system with point O as the origin of the coordinate system, and bring the angle and contour data set into the polar coordinate formula (ρ n cosa n , ρ n sina n ), and obtain the contour coordinate group [A 1 (ρ 1 cos1°,ρ 2 sin1°), A 2 (ρ 2 cos2°,ρ 2 sin2°)、···A 360 (ρ 360 cos360°, ρ 360 sin360°)];

[0121] The contour coordinate group is divided into twelve subsets at every 30°, denoted as group 1, group 2, ..., group 12, and a contour point A is randomly selected from the twelve groups. 57 ((ρ 57 cos57°,ρ 57 sin57°), identify group number 2, and extract the next contour point A from the remaining groups 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 129 ((ρ 129 cos129°,ρ 129 sin129°)) identifies the group number as group 5, and extracts the third contour point A from the remaining groups 1, 3, 4, 6, 7, 8, 9, 10, 11, and 12 243 ((ρ 243 cos243°,ρ 243 sin243°)), A 57 ((ρ 57 cos57°,ρ 57 sin57°))、A 129 ((ρ 129 cos129°,ρ 129 sin129°))、A 243 ((ρ 243 cos243°,ρ 243 Sin243°)) is substituted into the circle equation, and the center of the circle is set to B. 1 (h 1 ,k 1 ), with a radius of r 1 , we obtain the system of equations:

[0122]

[0123] Use the matrix to find the coordinates of the center of the circle as B 1 (h 1 , k 1 ), repeatedly extract 1000 groups of three contour points to obtain a circle center coordinate group consisting of 1000 circle center points with known coordinates [B 1 (h 1 , k 1 ), B 2 (h 2 , k 2 )``````B 1000 (h 1000 , k 1000 )] Set K to 3, set Minpts to 4, and Threshold to 95%, draw the K distance graph of the circle center coordinate group to obtain EPS, and use the DBSCAN clustering algorithm to process the circle center coordinate group [B 1 (h 1 , k 1 ), B 2 (h 2 , k 2 )······B 1000 (h 1000 , k 1000 )], and obtain the largest cluster, and calculate the ratio of the number of points in the largest cluster to the total number of points.

[0124] If the ratio is greater than 95%, the center coordinates (x 心 ,y 心 ), the center coordinate (x 心 ,y 心 ) and contour coordinate group [A 1 (ρ 1 cos1°,ρ 2 sin1°), A 2 (ρ 2 cos2°,ρ 2 sin2°)、···A 360 (ρ 360 cos360°, ρ 360 sin360°)] into the formula Obtain the cylindrical workpiece radius data set (r 1 、r 2 、r 3 ······、r 360 ), remove z outliers, Output the radius r of the cylindrical workpiece.

[0125] like Figure 2It can be seen from the optical path and auxiliary line schematic diagrams of Example 1 and Example 2 that when the cylindrical workpiece inner diameter detection device proposed in this scheme is used to detect a cylindrical workpiece with a smaller size, the distance from any point O in the cylindrical workpiece to the contour of the cylindrical workpiece can also be obtained, thereby realizing the detection of the inner diameter of the cylindrical workpiece with a smaller size.

[0126] Comparative Example 1

[0127] Only the second reflector 3 is set to detect the inner diameter of a cylindrical workpiece with a larger size. The optical path diagram is shown in Figure 3 shown.

[0128] Comparative Example 2

[0129] Depend on Figure 3 , Figure 4 It can be observed that, compared with Examples 1 and 2, Comparative Example 1-2 in which only the second reflector 3 is provided cannot receive the returned light, making it impossible to perform subsequent measurements. This indicates that in the present solution, the first plane reflector 2 and the second reflector 3 are indispensable for measuring cylindrical workpieces with different inner diameters, and that only relying on the second reflector 3 cannot achieve testing of all situations.

[0130] The technical features of the above-described embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-described embodiments are not 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. Although the embodiments of the present invention have been shown and described above, it can be understood that the above-described embodiments are exemplary and cannot be understood as limitations of the present invention. Those of ordinary skill in the art can change, modify, replace and deform the above-described embodiments within the scope of the present invention. In addition, those of ordinary skill in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples without contradiction.

Claims

1. A cylindrical workpiece inner diameter detection device, characterized in that: Along the optical path direction, it includes a sensor laser source (1), a first plane reflector (2), a second reflector (3) and a sensor receiver (4) in sequence; wherein: The sensor laser source (1) and the sensor receiver (4) are located outside the cylindrical workpiece to be measured; The first plane reflector (2) changes the initial light path generated by the sensor laser source (1) so that the first reflected laser enters the interior of the cylindrical workpiece to be measured; The second reflector (3) is located inside the cylindrical workpiece to be measured, reflects the first reflected laser light for a second time to the inner wall of the cylindrical workpiece to be measured to obtain a third reflected laser light, and receives the third reflected laser light for a fourth time, so that the fourth reflected laser light enters the sensor receiver (4).

2. The cylindrical workpiece inner diameter detection device according to claim 1, characterized in that: The included angle between the second reflector (3) and the central axis of the cylindrical workpiece to be measured is α2, and α2 is not equal to 0.

3. The cylindrical workpiece inner diameter detection device according to claim 2, characterized in that: α2 is equal to 45 degrees.

4. The cylindrical workpiece inner diameter detection device according to claim 1, characterized in that: The first plane reflector (2) and / or the second reflector (3) are plane reflectors, and a rotating platform is provided at the bottom of the second reflector.

5. The cylindrical workpiece inner diameter detection device according to claim 1, characterized in that: The angle between the first plane reflector (2) and the central axis of the cylindrical workpiece to be measured is smaller than the angle between the laser beam and the central axis of the cylindrical workpiece to be measured and is smaller than 90 degrees.

6. The cylindrical workpiece inner diameter detection device according to claim 1, characterized in that: The sensor receiver (4) is selected from any one of a CMOS sensor, a CCD sensor, and a photoelectric sensor and is used for receiving four-times reflected laser light.

7. A method for detecting the inner diameter of a cylindrical workpiece, characterized in that: Using the cylindrical workpiece inner diameter detection device according to any one of claims 1 to 6, the following steps are completed: S1: Parameter definition: Set the reflection point of the laser generated by the sensor laser source (1) on the first plane reflector (2) as the first reflection point O1, set the reflection point of the first reflected laser on the second reflector (3) as the second reflection point O, measure the vertical distance a from the sensor laser source (1) to O in the horizontal direction, measure the vertical distance b from O1 to O in the horizontal direction, measure the angle α1 between the laser beam generated by the sensor laser source (1) and the central axis of the cylindrical workpiece, measure the angle β between the first plane reflector (2) and the central axis of the cylindrical workpiece to be measured, and the point laser displacement sensor outputs the displacement L; S2: Construct the distance formula from point O to the contour of the cylindrical workpiece to be measured ρ=L*cos(2β-α1)-a*secα1*cos(2β-α1)+b*secα1*cos(2β-α1)-b; Among them, ρ is the distance from point O to the contour of the cylindrical workpiece to be measured; S3: The inner diameter detection device of the cylindrical workpiece to be measured is rotated horizontally with point O as the center to obtain the distance and angle from the contour of the cylindrical workpiece to be measured to point O, which is recorded as the contour data set, and a Cartesian coordinate system is established with point O as the origin. The contour data set is brought into the polar coordinate conversion formula (ρ n cos a n , ρ n sin a n ) to obtain a contour coordinate group, divide the contour coordinate group into at least 3 equal subsets according to the angle order, arbitrarily select three non-repeating subsets and randomly extract a contour point from each of them, and obtain the center coordinates of the three contour points. After repeating N times, a center coordinate group containing N center coordinates is obtained, where N is a natural number greater than 0, n represents the nth contour point, and a n represents the angle of the nth contour point, ρ n Indicates the distance from the nth point O to the contour of the cylindrical workpiece; S4: The center coordinate group, Threshold, EPS, and Minpts threshold are input through the DBSCAN clustering algorithm to judge and output the cylindrical workpiece state and the precise center coordinates of the qualified cylindrical workpiece, and calculate and output the cylindrical workpiece radius.

8. The method for detecting the inner diameter of a cylindrical workpiece according to claim 7, characterized in that: The steps to obtain the coordinates of the center of the three-point contour point are: First, extract any contour point, identify the subset group number to which the contour point belongs, remove the subset, and continue to randomly extract any contour point until the coordinates A of the three contour points are obtained. a (x a ,y a ), Ab(x b ,y b ), A c (x c ,y c ), where a, b, and c are arbitrary angles; Assume the coordinates of the center of the circle are (h, k), the radius is r, and substitute the coordinates of the contour points into the equation of the circle to obtain the linear equation system: Obtain the coordinates of the center of the circle (h, k); The steps to obtain Threshold are as follows: according to the simulation data of the inner diameter of the cylindrical workpiece, set the test accuracy and maximum error; repeat S1-S2 to obtain the circle center coordinate group, first set the Minpts threshold to twice the dimension of the data set, and the K value to Minpts threshold-1, and obtain the EPS value through the K-distance graph of the circle center coordinate group, input the circle center coordinate group, EPS, and Minpts threshold into the DBSCAN clustering algorithm, and obtain the percentage of the largest cluster to the total number of points, which is the Threshold, where the K value represents the number of nearest neighbors considered when calculating the K-distance of each point; The steps to obtain the EPS value through the K-distance graph are: calculate the distance from all points to their kth nearest neighbors and sort them, draw the sorted K-distance graph, and the value of the inflection point of the curve is the EPS value.

9. The method for detecting the inner diameter of a cylindrical workpiece according to claim 7, characterized in that: The center coordinates of the cylindrical workpiece and the radius group of the cylindrical workpiece are output through the following steps: judging whether the percentage of the center coordinate points in the largest cluster output by the DBSCAN clustering algorithm to the total center coordinate points is greater than the Threshold, if it is greater, outputting the center coordinates of the densest point in the largest cluster as the center coordinates of the cylindrical workpiece; The radius of the cylindrical workpiece is given by the formula Calculate and obtain the cylindrical workpiece radius data set, remove outliers, and then find the average value of the cylindrical workpiece radius data set, which is the cylindrical workpiece radius, where r is the cylindrical workpiece radius, x a is the horizontal coordinate of any contour point, y a is the ordinate of any contour point, x b is the horizontal coordinate of the center of the cylindrical workpiece, y b is the ordinate of the center of the cylindrical workpiece.

10. The method for detecting the inner diameter of a cylindrical workpiece according to claim 7, characterized in that: When outputting the status of a cylindrical workpiece, first check whether the percentage of the number of circle center coordinate points in the largest cluster to the total number of circle center coordinate points is greater than the Threshold. If it is greater than the Threshold, the cylindrical workpiece is considered qualified, otherwise it is considered that the cylindrical workpiece is deformed. When the method for detecting the inner diameter of a cylindrical workpiece detects planes of different heights, first, M planes are selected from the cylindrical workpiece for detection, where M is a natural number greater than 1. If all M planes are qualified, the cylindrical workpiece is considered qualified; if any plane P is unqualified, the plane P needs to be re-detected, and the upper plane P1 and the lower plane P2 are extracted for detection according to the set accuracy. If plane P, the upper plane P1 and the lower plane P2 are all qualified, the cylindrical workpiece is judged to be qualified; if any plane is unqualified, the cylindrical workpiece is judged to be unqualified; Among the cylindrical workpieces judged as unqualified, if both the upper plane P1 and the lower plane P2 are qualified, the cylindrical workpiece is regarded as a defective cylindrical workpiece; if both the upper plane P1 and the lower plane P2 are unqualified, the cylindrical workpiece is regarded as a deformed cylindrical workpiece. If any one of the upper plane P1 or the lower plane P2 is qualified, the upper and lower planes of the unqualified plane are extracted again for inspection according to the accuracy requirements. If both the upper and lower planes are qualified, it is determined to be a defective cylindrical workpiece. If any of the upper and lower planes is unqualified, it is determined to be a deformed cylindrical workpiece.

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