A large-size shell segment form tolerance automatic measuring device and method
By designing an automatic measurement device for the form and position tolerances of large-size shell sections, and employing non-contact measurement and multi-sensor technology, the problem of complex and low-precision form and position tolerance detection of large-size rocket shell sections has been solved, achieving efficient and accurate form and position tolerance measurement, especially accurate characterization of tail fin centripetal force.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CAPITAL AEROSPACE MACHINERY
- Filing Date
- 2022-11-15
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies for detecting the form and position tolerances of large-size rocket body sections are complex and have low accuracy, which cannot meet the requirements of high-density and high-quality launches.
An automatic measurement device for the form and position tolerances of large-size shell sections is designed, including a measuring turntable and a sensor group. It adopts a non-contact measurement method, acquires shell section feature data through multiple sensors, and uses the least squares method to fit parameters such as roundness and flatness. In particular, a method for measuring the centripetal force of the tail fin is proposed.
It enables efficient and accurate measurement of geometric tolerances such as roundness, flatness, parallelism, coaxiality, and tail fin centripetality of large-size shell products, improving measurement efficiency and accuracy and meeting the requirements of high-density launch.
Smart Images
Figure CN115950384B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of launch vehicle technology, specifically relating to a device and method for automatic measurement of form and position tolerances of large-size shell sections. Background Technology
[0002] like Figure 1 The shell sections of currently operational launch vehicles mainly adopt a skin frame truss structure. The skin 22 is riveted to the upper frame 21, lower frame 24 and stringers to form a cylindrical shell section. The tail fin 23 is riveted to the outer side of the four quadrants of the shell section after the shell section is assembled. The tail fin is composed of wedge-shaped inclined surfaces with a certain included angle and is formed by riveting the skin. The shell section has a diameter of 3350mm and a height of 5000mm, which is a typical large-size shell section structure. This skin frame truss structure has relatively weak rigidity. The product is prone to deformation during riveting and assembly, which affects the product's size and positional accuracy. Therefore, after the shell section is riveted and assembled, the product's external dimensions and positional tolerances must be measured.
[0003] Currently, the form and position tolerance inspection of such large rocket body sections mainly utilizes tools such as dial indicators, vernier calipers, and micrometers, and is performed manually on a rotatable platform. This common contact measurement method is cumbersome, time-consuming, labor-intensive, and prone to errors for ultra-large products. It is significantly affected by human factors, resulting in low measurement efficiency and low accuracy, which cannot meet the current high-density, high-quality launch requirements.
[0004] Currently, digital methods for measuring the form and position of large-sized workpieces include coordinate measuring machines (CMMs) and 3D scanners. However, CMMs used for measuring such large workpieces are expensive and require specific factory environments. 3D scanners typically require multiple target points to be affixed to the product and need to be manually operated, resulting in high labor intensity for measuring such large-scale workpieces. Furthermore, there are foreign embargoes and a lack of domestically available large-scale specialized measurement equipment for rocket body shell sections. Therefore, there is an urgent need to develop an automatic measurement device for the form and position tolerances of large-sized shell sections to improve the measurement efficiency and accuracy of rocket body shell sections and meet the launch requirements of the rocket model. Summary of the Invention
[0005] The purpose of this invention is to overcome the above-mentioned defects and provide an automatic measurement device and method for the form and position tolerances of large-size shell sections. This invention solves the technical problems of complex and low-precision existing methods for detecting the form and position tolerances of large-size rocket shell sections. This invention can measure the external dimensions and form and position tolerances of products, such as roundness, flatness, parallelism, coaxiality, tail fin centripetal force, product height, and product diameter.
[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0007] This invention belongs to the field of measurement equipment and solution research technology. It is used for measuring the form and position tolerances of cylindrical and conical shell products with diameters ranging from Φ1000 to 3350 mm and heights ≤5000 mm. The measurement items mainly include the flatness of the upper and lower end faces, the roundness of the upper and lower end frames, the parallelism of the upper and lower end faces, the coaxiality of the upper and lower frames, the centripetal force of the tail fin, the product height, diameter, and other form and position tolerances and external dimensions.
[0008] An automatic measurement device for the form and position tolerances of large-size shell segments includes a measuring turntable and a sensor group;
[0009] The measuring turntable is used to support the shell segment being measured and to drive the shell segment to rotate at a constant speed.
[0010] The sensor group includes an upper end face measurement sensor, a lower end face measurement sensor, a tail fin measurement sensor, and an end frame measurement sensor;
[0011] The upper end face measurement sensor is aligned with the upper end face of the shell segment being measured, and is used to acquire feature data of the upper end face of the shell segment being measured when the shell segment being measured rotates.
[0012] The lower end face measurement sensor is aligned with the lower end face of the shell section being measured, and is used to acquire feature data of the lower end face of the shell section being measured when the shell section being measured rotates.
[0013] The tail fin measurement sensor is used to acquire feature data of the tail fin center plane when the measured shell section is fixed.
[0014] The end frame measurement sensor is aligned with the cylindrical surface of the upper or lower end frame of the shell segment being measured, and is used to acquire feature data of the cylindrical surface of the upper or lower end frame when the shell segment being measured rotates.
[0015] Furthermore, when acquiring feature data of the center plane of the tail fin, several evenly distributed measuring blocks are installed on the top of the wedge-shaped tail fin of the measured shell section.
[0016] The measuring block is in the shape of a cube or cuboid. The bottom surface of the measuring block is provided with a wedge-shaped groove that matches the shape of the top of the tail fin. The center line of the wedge-shaped groove passes through the center point of the bottom surface of the measuring block. The fit between the wedge-shaped groove and the top of the tail fin enables the measuring block to be fixedly installed on the top of the tail fin.
[0017] The tail fin measurement sensor is aligned with the vertical side of the measurement block to obtain the feature data of the vertical side of the measurement block. Based on the feature data of the vertical side of the measurement block, the feature data of the center plane of the tail fin is obtained.
[0018] Furthermore, it also includes a column mechanism and a measuring arm;
[0019] The column structure is fixed to the ground;
[0020] The measuring arm is mounted on the column mechanism and can move vertically or horizontally relative to the column mechanism;
[0021] The upper end face measurement sensor, tail fin measurement sensor, and end frame measurement sensor are mounted on the measurement arm, while the lower end face measurement sensor is fixedly supported on the ground using a bracket.
[0022] Furthermore, two tail fin measurement sensors are mounted on the measuring arm. The use of two sensors is primarily to reduce sensor travel distance, thereby reducing the length of the measuring arm and meeting structural strength requirements. Otherwise, the measuring arm would be very long, leading to severe deformation and a large structural size. The third displacement sensor 10 and the fourth displacement sensor 11 are positioned horizontally, approximately half the length of the tail fin. The fore-and-aft distance is equal to the measuring arm distance multiplied by tan(p). The angle P is determined based on the maximum measurable distance (range) of the sensors and the width of the tail fin, ensuring that the sensors do not interfere with the tail fin and remain within their measurement range.
[0023] An automatic measurement method for the form and position tolerances of large-size shell segments, implemented using the aforementioned automatic measurement device for the form and position tolerances of large-size shell segments, includes:
[0024] The upper end face measurement sensor is aligned with the upper end face of the shell segment being measured, and acquires the feature data of the upper end face of the shell segment being measured as the shell segment is rotated.
[0025] The lower end face measurement sensor is aligned with the lower end face of the shell section being measured, and acquires the feature data of the lower end face of the shell section being measured as the shell section is rotated.
[0026] When the tail fin measurement sensor is fixed in the shell section being measured, it acquires characteristic data of the center plane of the tail fin.
[0027] The end frame measurement sensor is aligned with the cylindrical surface of either the upper or lower end frame of the shell segment being measured. As the shell segment being measured rotates, it acquires the cylindrical surface feature data of that end frame. Then, it moves vertically to align with the cylindrical surface of the other end frame of the shell segment being measured, and acquires the cylindrical surface feature data of that end frame as the shell segment being measured rotates.
[0028] Furthermore, the aforementioned automatic measurement method for the form and position tolerances of large-size shell segments also includes:
[0029] The flatness of the upper and lower end faces of the shell section under test is obtained based on the feature data of the upper end face and the lower end face of the shell section under test, respectively.
[0030] The parallelism error of the upper and lower end faces is obtained based on the flatness of the upper and lower end faces of the shell section being measured.
[0031] The roundness error of the shell segment under test is obtained based on the feature data of the upper frame cylindrical surface and the feature data of the lower frame cylindrical surface.
[0032] The coaxiality error of the shell section being measured is obtained from the roundness error of the shell section being measured.
[0033] The centripetal force of the tail fin is obtained based on the characteristic data of the center plane of the tail fin. The centripetal force of the tail fin is the degree of offset between the center plane of the tail fin and the center line of the measured shell segment.
[0034] Furthermore, the method for obtaining the roundness error of the measured shell segment based on the feature data of the upper frame cylindrical surface and the lower frame cylindrical surface is as follows:
[0035] Using the feature data of the upper and lower cylindrical surfaces of the frame, the least squares circles of the upper and lower frames are fitted respectively by the least squares method. The difference between the maximum and minimum distances from each point on the circumference of the upper or lower frame to the least squares circle is calculated to obtain the roundness error of the shell segment being measured.
[0036] Furthermore, when acquiring feature data of the center plane of the tail fin, the tail fin measurement sensor first installs the tail fin onto the shell section being measured and rotates it together with the shell section being measured to a specific angle.
[0037] The specific angle is determined based on the tail fin width and the range of the tail fin measuring sensor to avoid interference between the tail fin and the measuring arm, while ensuring that the tail fin is within the range of the tail fin measuring sensor.
[0038] Furthermore, when the tail fin measurement sensor is fixed in the measured shell section, the method for acquiring feature data of the tail fin center plane is as follows:
[0039] Several evenly distributed measuring blocks are installed on the top of the wedge-shaped tail fin of the shell section being measured;
[0040] The measuring block is in the shape of a cube or cuboid. The bottom surface of the measuring block is provided with a wedge-shaped groove that matches the shape of the top of the tail fin. The center line of the wedge-shaped groove passes through the center point of the bottom surface of the measuring block (the middle position of the wedge-shaped groove is exactly at half the thickness of the measuring block). The cooperation between the wedge-shaped groove and the top of the tail fin enables the measuring block to be fixedly installed on the top of the tail fin.
[0041] The tail fin measurement sensor is aligned with the vertical side of the measurement block. When the measured shell section is fixed, the tail fin measurement sensor moves in a straight line with equal intervals along the horizontal direction, taking one step and stopping at a time, to obtain the feature data of the vertical side of the measurement block. The feature data of the vertical side of the measurement block is added to half the thickness of the measurement block, and then the linear equation of the tail fin centerline is fitted as the feature data of the tail fin center plane.
[0042] The tail fin has a symmetrical wedge-shaped structure, and the line of intersection of the two wedge-shaped slopes is denoted as the tail fin centerline.
[0043] Furthermore, the method for obtaining the tail fin's centripetal force based on the characteristic data of the tail fin's center plane is as follows:
[0044] Let A be the center of the least squares circle of the lower frame. Project A vertically onto the horizontal plane where the centerline of the tail fin is located, and record the projection point as A'. Calculate the distance between A' and the centerline of the tail fin, and take this distance as the centripetal force of the tail fin. The distance between A' and the centerline of the tail fin can be regarded as the degree of offset between the center plane of the tail fin and the centerline of the measured shell segment.
[0045] The centerline of the tail fin is obtained based on the linear equation of the tail fin centerline.
[0046] When acquiring feature data of the tail fin center plane, the tail fin measurement sensor uses several measuring blocks mounted on the top of the tail fin section being measured. The sensor aligns with these blocks to acquire vertical side feature data. The measured distance data is then added to half the thickness of the measuring blocks to fit a linear equation for the tail fin centerline. Using the measuring blocks eliminates the need to measure the tail fin thickness, avoiding thickness errors and improving measurement accuracy. Because the bottom surface of the measuring blocks, where they are mounted on the top of the tail fin, has wedge-shaped grooves with dimensions and angles matching those of the tail fin top, the position of the measuring blocks reflects the tail fin centerline position.
[0047] Compared with the prior art, the present invention has the following advantages:
[0048] (1) This invention creatively proposes a measuring device and method for large-size cylindrical and conical shell products with diameters of Φ1000~Φ3350mm and heights of 0~5000mm, which can realize the measurement of the product's roundness, flatness, parallelism, coaxiality, tail fin centripetality, product height, product diameter and other external dimensions and geometric tolerances.
[0049] (2) The present invention adopts a non-contact measurement method, which collects shell feature data by specially setting multiple measuring heads, so as to realize continuous measurement of the equipment. It does not need to avoid protruding components on the shell product, and is not affected by the target material, color or angle, and has high enough accuracy to meet the measurement requirements.
[0050] (3) The present invention specifically proposes a method for measuring the centripetal force of the tail fin, which can accurately characterize the degree of offset of the center plane of the tail fin relative to the center line of the measured shell section, which is beneficial to improving the accuracy of the product.
[0051] (4) The present invention uses a measuring block to measure the centripetal force of the tail fin. The tail fin measuring sensor is aligned with the measuring block to obtain the side feature data of the measuring block in the vertical direction and fit the linear equation of the tail fin centerline. The technical effect of evaluating the centripetal force of the tail fin is achieved by calculating the distance from the projection of the center of the least square circle of the lower frame to the linear equation of the tail fin centerline. Attached Figure Description
[0052] Figure 1 Three-view diagram of the shell section of a launch vehicle;
[0053] Figure 2 This is an overall structural diagram of the automatic measurement device for the form and position tolerances of large-size shell sections according to the present invention;
[0054] Figure 3 This is a schematic diagram of the flatness measurement of the upper frame of the present invention;
[0055] Figure 4 This is a schematic diagram of the flatness measurement of the lower frame of the present invention;
[0056] Figure 5 This is a schematic diagram of the roundness measurement of the present invention;
[0057] Figure 6 This is a schematic diagram of the tail fin centripetal measurement of the present invention;
[0058] Figure 7 This is a schematic diagram illustrating the least squares circle fitting method of the present invention;
[0059] In the figure, 1-measuring turntable, 3-column mechanism, 4-measuring arm, 5-shell section under test, 6-first displacement sensor, 7-second displacement sensor, 8-fifth displacement sensor, 9-sixth displacement sensor, 10-third displacement sensor, 11-fourth displacement sensor, 12-tail fin, 13-measuring block, 21-upper frame, 22-skin, 23-tail fin, 24-lower frame. Detailed Implementation
[0060] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.
[0061] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.
[0062] Based on the structural characteristics of the rocket body shell section, the measurement items and the measurement accuracy requirements, and considering the economy and the special-purpose nature of the equipment, this invention designs a large-size shell section form and position tolerance automatic measurement device to improve measurement efficiency. It adopts a non-contact measurement method, sets up multiple measuring heads to collect shell section feature data, and processes these data to obtain the shell section product dimensions and form and position tolerances.
[0063] like Figure 2 The device of this invention comprises three parts: a mechanical body, an electrical system, and a measurement data processing system. The mechanical body of the measuring equipment consists of a measuring turntable 1, a measuring head, a column mechanism 3, and a measuring arm 4, and has rotational, vertical, and horizontal movement functions. Figure 2As shown, the measuring turntable 1 is mainly used to support shell segments 5 of different sizes, allowing them to rotate 360° freely. The measuring arm 4 can move vertically and horizontally along the column mechanism 3, and a measuring head is mounted on the measuring arm 4. Multiple measuring heads are installed at different positions on the measuring arm according to measurement requirements to acquire the shape feature data of the shell segments. The measuring head uses a laser displacement sensor, replacing the original measuring tools such as micrometers and dial indicators. The equipment can continuously measure without needing to avoid protruding components on the shell segment. The sensor is not affected by the target material, color, or angle, and has sufficiently high accuracy to meet the measurement requirements. After the acquired shell segment shape feature data is processed by the measurement data processing system, the measurement results of the shell segment's roundness, flatness, parallelism, coaxiality, tail fin centripetal force, product height, and product diameter are obtained. The above mechanism realizes non-contact measurement of the shell segment's external dimensions and geometric tolerances. The measuring head described in this invention includes a sensor.
[0064] The specific implementation process is as follows: Figure 2 , 3 As shown, the shell section within the measurement range is installed on the measuring turntable 1. The measuring turntable 1 can rotate the shell section at equal angles. The column mechanism 3 drives the measuring head to move vertically. The column mechanism 3 is equipped with a grating ruler to obtain the vertical position data of the measuring head. The measuring arm 4 drives the measuring head to move horizontally. The measuring arm 4 is equipped with a grating ruler to obtain the horizontal position data of the measuring head. The measuring head uses a laser displacement sensor. To realize the measurement of various form and position tolerances of the shell section, six displacement sensors are provided, which are installed at different positions on the measuring arm 4.
[0065] During measurement, the first displacement sensor 6 (upper end face measurement sensor) acquires the feature data of the upper end face of the shell segment; the second displacement sensor 7 (end frame measurement sensor) acquires the feature data of the cylindrical surfaces at the upper and lower end frames of the shell segment; the tail fin centripetal force is used to evaluate the degree of offset between the tail fin center plane and the shell segment centerline. Before measurement, the measuring block 13 is installed on the upper end face of the tail fin 12, and the third displacement sensor 10 and the fourth displacement sensor 11 (tail fin measurement sensor) acquire the feature data of the side of the measuring block. The fifth displacement sensor 8 and the sixth displacement sensor 9 (lower end face measurement sensor) are respectively installed on the support under the measuring table to acquire the feature data of the lower end frame end face of shell segments with different diameters. After special calculation processing, the shell segment shape feature data are used to obtain the measurement results of the shell segment's roundness, flatness, parallelism, coaxiality, tail fin centripetal force, product height, and product diameter.
[0066] This invention enables automatic measurement of the external dimensions and geometric tolerances of cylindrical, conical, and shell segments with diameters of Φ1000~3350mm and heights ≤5000mm, including roundness, flatness, parallelism, coaxiality, tail fin centripetal force, product height, and product diameter. The measurement accuracy meets the requirements, and the measurement efficiency is significantly improved.
[0067] Example:
[0068] The main mechanical body of the measuring device consists of a measuring turntable 1, a measuring head, a column mechanism 3, and a measuring arm 4. The measuring turntable 1 can drive the housing to rotate at equal angles. The column mechanism 3 drives the measuring head to move vertically. A grating ruler is installed on the column mechanism 3 to obtain the vertical position data of the measuring head. The measuring arm 4 drives the measuring head to move horizontally. A grating ruler is installed on the measuring arm 4 to obtain the horizontal position data of the measuring head. A non-contact measurement method is adopted. The measuring head uses a laser displacement sensor (other similar measuring heads can also be used), eliminating the need to avoid protruding components on the housing section. To achieve the measurement of various form and position tolerances of the housing, six displacement sensors are provided, which are installed at different positions on the measuring arm 4. During measurement, the first displacement sensor 6 acquires the feature data of the upper end face of the housing; the second displacement sensor 7 acquires the feature data of the cylindrical surfaces at the upper and lower end frames of the housing; the tail fin centripetal is used to evaluate the degree of offset between the tail fin center plane and the housing centerline. Before measurement, a special measuring block is installed on the upper end face of the tail fin, and the third displacement sensor 10 and the fourth displacement sensor 11 acquire the feature data of the side of the measuring block. The fifth displacement sensor 8 and the sixth displacement sensor 9 are respectively mounted on the support below the measuring turntable 1 to acquire the characteristic data of the lower frame end face of shells with different diameters. After special calculation and processing, the above shell shape characteristic data yields measurement results for the shell segment's roundness, flatness, parallelism, coaxiality, tail fin centripetal force, product height, and product diameter. The specific measurement method is as follows:
[0069] 1) Flatness measurement of upper and lower end faces
[0070] like Figure 3 As shown, the flatness error is obtained by data collected by the first displacement sensor 6 on the measuring arm 4. The first displacement sensor 6 is installed on the front end face of the measuring arm 4. During the process of the measuring turntable 1 driving the shell to rotate at equal angular intervals, the characteristic data of the upper end face of the shell section are collected, such as... Figure 4 As shown, the fifth displacement sensor 8 and the sixth displacement sensor 9 are respectively installed on the support platform. During the rotation of the shell section, they are used to collect the feature data of the lower end face of the shell with diameters of 3350mm and 2250mm, respectively. According to the evaluation principle of flatness error detection in GB / T1958-2004 "Technical Specification for Geometric Measurement of Products (GPS) - Regulations for the Inspection of Shape and Position Tolerances", the flatness of the upper and lower end faces of the shell section is calculated based on the least squares method.
[0071] 2) Measurement of parallelism between upper and lower end faces
[0072] Parallelism error falls under the category of positional error of related elements. According to the evaluation principle of parallelism error detection in GB / T1958-2004 "Technical Specification for Geometric Quantities of Products (GPS) - Regulations for the Inspection of Shape and Position Tolerances", parallelism measurement uses the data of flatness measurement of the upper and lower end faces to obtain the parallelism error.
[0073] 3) Measurement of roundness of upper and lower frame
[0074] like Figure 5 As shown, the roundness error is obtained by data collected by the second displacement sensor 7 on the measuring arm 4. The second displacement sensor 7 is installed on the side of the measuring arm. During the rotation of the shell by the measuring turntable 1 at equal angular intervals, the characteristic data of the cylindrical surface at the upper and lower end frames of the shell are collected respectively. The measurement section of the outer surface of the cylinder is selected. The difference between the radius of each point on the measurement section and the radius of the starting point during one revolution is calculated. Through data processing, the least squares circle is fitted using the least squares method. The roundness error of the measured shell section is obtained by the difference between the maximum distance and the minimum distance from each point on the circumference of the upper or lower end frame to the least squares circle. Figure 7 .
[0075] 4) Measurement of coaxiality between the upper and lower end faces
[0076] Coaxiality is a measurement of positioning error within the context of related elements. Based on the evaluation principles of coaxiality error detection in GB / T1958-2004 "Technical Specifications for Geometric Measurements of Products (GPS) - Regulations for the Inspection of Shape and Position Tolerances" and the coaxiality measurement methods in Q / Y381-2010 "Measurement of Coaxiality of Large-Scale Shells," coaxiality measurement utilizes data from the roundness measurements of the upper and lower end frames to obtain the coaxiality error.
[0077] 5) Tail fin centripetal measurement
[0078] The tail fin centripetal force of this invention is used to evaluate the degree of offset between the center plane of each tail fin and the center line of the shell on the horizontal plane. Because the tail fin is a wedge-shaped, symmetrical structure, such as... Figure 1 As shown, the intersection of the two inclined planes is angle α. This intersection (hereinafter referred to as the tail fin centerline) lies on the center plane of the tail fin. Therefore, the centripetal force of the tail fin can be approximately evaluated using the distance from the center of the shell to the intersection of the two inclined planes. For example... Figure 6As shown, during measurement, the tail fin is mounted on the shell section being measured and rotates together with the shell section to a specific angle. The rotation angle of the tail fin is determined based on the tail fin width and the range of the tail fin measurement sensor to avoid interference between the tail fin and the measuring arm 4, while ensuring that the distance between the tail fin and the sensor is within the range of the tail fin measurement sensor. Several measuring blocks 13 are mounted on the top of the tail fin of the shell section being measured. The third displacement sensor 10 and the fourth displacement sensor 11 are aligned with the outer side of the measuring blocks and follow the measuring arm 4 in a horizontal linear motion with equal intervals, step by step, to acquire the feature data of the outer side of the measuring blocks 13. The measuring blocks 13 are cubes or cuboids in shape. A wedge-shaped groove is carved in the middle of one side (bottom end) of the tail fin, and the size and angle of the wedge-shaped groove are consistent with the size and angle of the tail fin top. The measuring blocks 13 are mounted on the top of the tail fin through the wedge-shaped groove and fit against the two inclined surfaces of the tail fin top. The measuring blocks 13 are evenly distributed on the top of the tail fin, and the number of measuring blocks 13 is determined according to the size of the tail fin and the requirements for measurement data acquisition. The present invention designs the measuring block 13 into several small blocks, which is beneficial to reflect the manufacturing error of the tail fin itself, and improves portability. It can be flexibly adjusted according to the tail fin size.
[0079] Because the measuring block 13 has a wedge-shaped groove cut into one side of the tail fin's top, and the size and angle of the wedge groove are consistent with the size and angle of the tail fin's top, the position of the measuring block can reflect the tail fin's centerline position. Using the measuring block 13 eliminates the need to measure the tail fin's thickness, avoiding thickness errors and improving measurement accuracy and convenience. The measured distance data is added to half the thickness of the measuring block 13 to fit a linear equation for the tail fin's centerline.
[0080] The centripetal force of a tail fin is evaluated by calculating the distance between the center of the lower frame's roundness and the tail fin's centerline on a horizontal plane, based on the linear equation of the lower frame's roundness. The centripetal force of each of the other tail fins is measured using the same method. This invention uses the center of the lower frame's roundness to evaluate the tail fin's centripetal force because: firstly, the shell section is machined using the lower frame as a reference; and secondly, the distance between the lower frame and the top of the tail fin is relatively large, allowing for a more accurate reflection of the error in the tail fin's centripetal force.
[0081] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
[0082] The contents not described in detail in this specification are common knowledge to those skilled in the art.
Claims
1. An automatic measurement device for the form and position tolerances of large-size shell segments, characterized in that, It includes a measuring turntable (1) and a sensor group (2); The measuring turntable (1) is used to support the shell section being measured and to drive the shell section being measured to rotate at a constant speed; The sensor group (2) includes an upper end face measurement sensor, a lower end face measurement sensor, a tail fin measurement sensor, and an end frame measurement sensor; The upper end face measurement sensor is aligned with the upper end face of the shell segment being measured, and is used to acquire feature data of the upper end face of the shell segment being measured when the shell segment being measured rotates. The lower end face measurement sensor is aligned with the lower end face of the shell section being measured, and is used to acquire feature data of the lower end face of the shell section being measured when the shell section being measured rotates. The tail fin measurement sensor is used to acquire feature data of the tail fin center plane when the measured shell section is fixed. The end frame measurement sensor is aligned with the cylindrical surface of the upper end frame or the cylindrical surface of the lower end frame of the shell segment being measured, and is used to acquire feature data of the cylindrical surface of the upper end frame or the cylindrical surface of the lower end frame when the shell segment being measured rotates. When acquiring the characteristic data of the center plane of the tail fin, several uniformly distributed measuring blocks (13) are installed on the top of the wedge-shaped tail fin of the shell section being measured. The measuring block (13) is a cube or cuboid. The bottom surface of the measuring block (13) is provided with a wedge-shaped groove that matches the shape of the top of the tail fin. The center line of the wedge-shaped groove passes through the center point of the bottom surface of the measuring block (13). The cooperation between the wedge-shaped groove and the top of the tail fin enables the measuring block (13) to be fixedly installed on the top of the tail fin. The tail fin measurement sensor is aligned with the vertical side of the measurement block (13) to obtain the feature data of the vertical side of the measurement block (13), and the feature data of the center plane of the tail fin is obtained based on the feature data of the vertical side of the measurement block (13).
2. The automatic measurement device for form and position tolerances of large-size shell segments according to claim 1, characterized in that, It also includes a column mechanism (3) and a measuring arm (4); The column mechanism (3) is fixed to the ground; The measuring arm (4) is mounted on the column mechanism (3) and can move vertically or horizontally relative to the column mechanism (3); The upper end face measurement sensor, tail fin measurement sensor and end frame measurement sensor are mounted on the measurement arm (4), and the lower end face measurement sensor is fixedly supported on the ground by a bracket.
3. The automatic measurement device for form and position tolerances of large-size shell segments according to claim 1, characterized in that, Two tail fin measurement sensors are mounted on the measuring arm (4).
4. An automatic measurement method for the form and position tolerances of large-size shell segments, characterized in that, This is achieved using the automatic measurement device for the form and position tolerances of large-size shell segments as described in any one of claims 1-3, comprising: The upper end face measurement sensor is aligned with the upper end face of the shell segment being measured, and acquires the feature data of the upper end face of the shell segment being measured as the shell segment is rotated. The lower end face measurement sensor is aligned with the lower end face of the shell section being measured, and acquires the feature data of the lower end face of the shell section being measured as the shell section is rotated. When the tail fin measurement sensor is fixed in the shell section being measured, it acquires characteristic data of the center plane of the tail fin. The end frame measurement sensor is aligned with the cylindrical surface of either the upper or lower end frame of the shell segment being measured. As the shell segment being measured rotates, it acquires the cylindrical surface feature data of that end frame. Then, it moves vertically to align with the cylindrical surface of the other end frame of the shell segment being measured, and acquires the cylindrical surface feature data of that end frame as the shell segment being measured rotates.
5. The automatic measurement method for form and position tolerances of large-size shell segments according to claim 4, characterized in that, Also includes: The flatness of the upper and lower end faces of the shell section under test is obtained based on the feature data of the upper end face and the lower end face of the shell section under test, respectively. The parallelism error of the upper and lower end faces is obtained based on the flatness of the upper and lower end faces of the shell section being measured. The roundness error of the shell segment under test is obtained based on the feature data of the upper frame cylindrical surface and the feature data of the lower frame cylindrical surface. The coaxiality error of the shell section being measured is obtained from the roundness error of the shell section being measured. The centripetal force of the tail fin is obtained based on the characteristic data of the center plane of the tail fin. The centripetal force of the tail fin is the degree of offset between the center plane of the tail fin and the center line of the measured shell segment.
6. The automatic measurement method for form and position tolerances of large-size shell segments according to claim 5, characterized in that, The method for obtaining the roundness error of the measured shell segment based on the feature data of the upper and lower cylindrical surfaces is as follows: Using the feature data of the upper and lower cylindrical surfaces of the frame, the least squares circles of the upper and lower frames are fitted respectively by the least squares method. The difference between the maximum and minimum distances from each point on the circumference of the upper or lower frame to the least squares circle is calculated to obtain the roundness error of the shell segment being measured.
7. The automatic measurement method for form and position tolerances of large-size shell segments according to claim 5, characterized in that, When acquiring feature data of the center plane of the tail fin, the tail fin measurement sensor first installs the tail fin onto the shell section being measured and rotates it together with the shell section being measured to a specific angle. The specific angle is determined based on the width of the tail fin and the range of the tail fin measuring sensor to avoid interference between the tail fin and the measuring arm (4), while ensuring that the tail fin is within the range of the tail fin measuring sensor.
8. The automatic measurement method for form and position tolerances of large-size shell segments according to claim 6, characterized in that, When the tail fin measurement sensor is fixed in the shell section being measured, the method for acquiring feature data of the tail fin center plane is as follows: Several evenly distributed measuring blocks (13) are installed on the top of the wedge-shaped tail fin of the shell section being measured. The measuring block (13) is a cube or cuboid. The bottom surface of the measuring block (13) is provided with a wedge-shaped groove that matches the shape of the top of the tail fin. The center line of the wedge-shaped groove passes through the center point of the bottom surface of the measuring block (13). The cooperation between the wedge-shaped groove and the top of the tail fin enables the measuring block (13) to be fixedly installed on the top of the tail fin. The tail fin measurement sensor is aligned with the vertical side of the measurement block (13). When the measured shell section is fixed, the tail fin measurement sensor moves in a straight line with equal intervals along the horizontal direction, stopping and starting at each step, to obtain the feature data of the vertical side of the measurement block (13). The feature data of the vertical side of the measurement block (13) is added to half the thickness of the measurement block (13), and the linear equation of the tail fin centerline is fitted as the feature data of the tail fin center plane. The tail fin has a symmetrical wedge-shaped structure, and the line of intersection of the two wedge-shaped slopes is denoted as the tail fin centerline.
9. The automatic measurement method for form and position tolerances of large-size shell segments according to claim 8, characterized in that, The method for obtaining the centripetal force of the tail fin based on the characteristic data of the tail fin's center plane is as follows: Let A be the center of the least squares circle of the lower frame. Project A vertically onto the horizontal plane where the centerline of the tail fin is located, and record the projection point as A'. Calculate the distance between A' and the centerline of the tail fin, and take this distance as the centripetal force of the tail fin. The centerline of the tail fin is obtained based on the linear equation of the tail fin centerline.