Automatic calibration device and method for smooth surface ring gauge

Abstract

The invention discloses a smooth surface ring gauge automatic calibration device and method.The device comprises a clamping and positioning unit, a visual identification unit, a measuring unit and a computer control system, and the measuring unit comprises a metering type coordinate measuring machine, an automatic calibration module and a temperature acquisition unit; the visual identification unit comprises a line laser visual sensor and an image processing module, the computer control system is used for realizing data transmission and cooperation among the modules or units, and the line laser visual sensor adopts a laser triangulation method to scan the 3D contour of the smooth surface ring gauge to obtain point cloud data; the image processing module identifies and analyzes the point cloud data to obtain geometric feature information of the smooth surface ring gauge, the automatic calibration module adjusts a measurement scheme in real time according to the geometric feature information, and the metering type coordinate measuring machine measures all parameters of the smooth surface ring gauge according to the adjusted measurement scheme. According to the invention, full-parameter, high-efficiency, high-precision and integrated automatic calibration of the smooth surface ring gauge can be realized.

Description

Technical Field

[0001] The invention belongs to the field of metrological calibration and detection, and particularly relates to an automatic calibration device and method for a smooth ring gauge. Background Art

[0002] As a physical measuring tool for controlling the limit dimensions of workpieces and reproducing the high-precision internal dimensions of various parts, the smooth ring gauge has measurement parameters including diameter, diameter variation, roundness, and straightness. In order to ensure the accuracy and reliability of the measurement values ​​of the smooth ring gauge in various industries, the smooth ring gauge needs to be regularly transferred or traced. Currently, related research focuses on improving the measurement accuracy of length measuring machines and improving temperature measurement systems. However, there is insufficient research on the automation of the overall calibration process of all parameters and the low measurement accuracy and efficiency of special limit dimensions. The existing technology measures the diameter and diameter variation of the smooth ring gauge by configuring a corresponding high-grade standard ring gauge with a high-precision length measuring instrument, and uses a roundness meter to measure roundness and straightness. However, it has the following limitations: 1) Due to the limited number of high-grade standard ring gauges, the consistency error of the double-hook machining of the length measuring instrument will gradually increase with the increase of the measuring stroke, ultimately affecting the accuracy of the measurement results; 2) When using the comparison method for measurement, the clamping of the smooth ring gauge will introduce secondary centering errors; 3) Due to the limitations of double-hook size processing, worktable travel, and load-bearing capacity, high-precision measurement capabilities cannot be achieved or guaranteed for smooth ring gauges smaller than φ15mm and larger than φ150mm; 4) In addition to measuring the diameter and variation of the smooth ring gauge, it is also necessary to further use a roundness meter to measure the straightness and roundness, and it is necessary to perform isothermal, secondary clamping, centering and leveling operations again, which has low measurement efficiency. Summary of the Invention

[0003] The purpose of the present invention is to provide a smooth ring gauge automatic calibration device and method to solve the problems existing in the prior art, which can realize full-parameter, high-efficiency, high-precision and integrated automatic calibration of the smooth ring gauge.

[0004] In order to achieve the above object, one aspect of the present invention provides an automatic calibration device for a smooth ring gauge, comprising a clamping and positioning unit, a visual recognition unit, a measuring unit and a computer control system. The measuring unit includes a metrological coordinate measuring machine, an automated calibration module, and a temperature acquisition unit; the visual recognition unit includes a line laser vision sensor and an image processing module; and a computer control system is connected to the metrological coordinate measuring machine, the automated calibration module, the temperature acquisition unit, the line laser vision sensor, and the image processing module to realize data transmission and collaboration among the metrological coordinate measuring machine, the automated calibration module, the temperature acquisition unit, the line laser vision sensor, and the image processing module; The clamping and positioning unit is installed on the movable worktable of the metrological coordinate measuring machine and is used to clamp and position the smooth surface ring gauge to be measured. The line laser vision sensor is installed above the movable worktable of the metrological coordinate measuring machine and cooperates with the movable worktable to scan the 3D contour of the smooth surface ring gauge using laser triangulation to obtain point cloud data. The image processing module uses an image recognition algorithm based on deep learning to identify and analyze the point cloud data of the 3D contour of the smooth surface ring gauge, obtain the geometric feature information of the smooth surface ring gauge, and transmit it to the automatic calibration module in real time. The automatic calibration module adjusts the measurement plan in real time according to the received geometric feature information of the smooth surface ring gauge. The metrological coordinate measuring machine performs measurement of all parameters of the smooth surface ring gauge according to the adjusted measurement plan. The temperature acquisition unit includes multiple temperature sensors installed on the metrological coordinate measuring machine and the smooth ring gauge being measured, which are used to monitor and collect the temperature changes of the environment during the measurement process in real time and transmit them to the automatic calibration module. The automatic calibration module corrects the measurement results of the smooth ring gauge based on the received ambient temperature changes.

[0005] Another aspect of the present invention provides a method for automatically calibrating a smooth ring gauge, which utilizes the above-mentioned device to automatically calibrate a smooth ring gauge, comprising: Place the smooth ring gauge on the clamping and positioning unit to complete the clamping, and align the center of the smooth ring gauge with the center of the measuring coordinate system; The movable worktable of the metrological coordinate measuring machine moves and collaborates with the line laser vision sensor to complete the 3D contour scanning of the smooth ring gauge. The image processing module extracts the geometric feature information and transmits it to the automated calibration module. The automated calibration module adaptively adjusts the measurement plan of the metrological coordinate measuring machine based on the received geometric feature information, and the metrological coordinate measuring machine performs full parameter measurement of the smooth ring gauge based on the adjusted measurement plan; The computer control system transmits the data measured by the metrological coordinate measuring machine to the certificate paperless entry system in real time. The certificate paperless entry system outputs the smooth ring gauge calibration report, thus completing the entire calibration activity of the smooth ring gauge from measurement to report output.

[0006] The automatic calibration device and method for smooth ring gauges of the above aspects of the present invention combine machine vision with coordinate measurement technology, overcoming the problems existing in traditional smooth ring gauge calibration, such as incomplete configuration of standard ring gauges, secondary clamping errors, consistency errors in double measuring hook processing, limited measurement range, and low measurement efficiency. Through one clamping, full-parameter, high-efficiency, high-precision, integrated automatic calibration can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the technical solutions of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts. Figure 1 This is a functional block diagram of an automatic calibration device for a smooth ring gauge according to an embodiment of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure of an automatic calibration device for a smooth ring gauge according to an embodiment of the present invention. DETAILED DESCRIPTION

[0008] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0009] One embodiment of the present invention provides an automatic calibration device for a smooth ring gauge. Figure 1 As shown, the automatic calibration device of the smooth ring gauge embodiment of the present invention includes a clamping and positioning unit, a visual recognition unit, a measuring unit and a computer control system, wherein the measuring unit includes a metrological coordinate measuring machine, a temperature acquisition unit and an automatic calibration module, and the visual recognition unit includes a line laser vision sensor and an image processing module.

[0010] like Figure 2 As shown, the metrological coordinate measuring machine 2, serving as the measuring body, is located at the center of the overall apparatus. A clamping and positioning unit 5 is mounted on the movable worktable 6 of the metrological coordinate measuring machine 2, used to clamp and position the smooth surface ring gauge to be measured. A line laser vision sensor 3 is mounted directly above the movable worktable 6 of the metrological coordinate measuring machine 2 to acquire three-dimensional (3D) profile information of the smooth surface ring gauge.

[0011] The visual recognition unit includes a line laser vision sensor 3 and an image processing module. The line laser vision sensor 3 works in conjunction with the movable worktable 6 of the metrological coordinate measuring machine 2, scanning the 3D contour of the smooth ring gauge using the laser triangulation measurement principle. The image processing module utilizes a deep learning-based image recognition algorithm to identify and analyze the collected point cloud data, accurately identifying key elements such as the smooth ring gauge's shape, size range, and special markings. It then isolates the smooth ring gauge's effective diameter and thickness, providing real-time information to the automated calibration module for adaptive calibration. Based on the smooth ring gauge feature information output by the visual recognition unit, the automated calibration module dynamically adjusts the measurement plan, including probe selection, path planning, and measurement point distribution. It then generates a new measurement program, driving the metrological coordinate measuring machine to perform full-parameter measurement tasks for different types of smooth ring gauges according to the measurement program. The full parameters of a smooth ring gauge include diameter size, diameter variation, roundness, and straightness measurement.

[0012] The clamping and positioning unit 5 uses a self-centering fixture to clamp various types of smooth ring gauges. By adjusting the servo motor's stepping torque and speed, accurate clamping and positioning are achieved, minimizing positioning errors and preventing interference with the metrological CMM probe. The self-centering fixture can utilize any centering principle and structure, such as air-floating or mechanical elastic centering, as long as it ensures clamping accuracy and compatibility with smooth ring gauges of varying shapes.

[0013] The temperature acquisition unit 4 is used to collect the real-time temperature of the smooth ring gauge and monitor ambient temperature fluctuations during the measurement process, thereby enabling temperature monitoring and correction of measurement results. Specifically, the ambient temperature acquisition unit may include multiple temperature sensors installed on the metrological coordinate measuring machine and the smooth ring gauge being measured. These sensors are used to monitor and collect ambient temperature changes during the measurement process in real time and transmit these changes to the automated calibration module. The automated calibration module then corrects the smooth ring gauge's measurement results based on the received ambient temperature changes.

[0014] The computer control system 1 is connected to the metrological coordinate measuring machine 2, the automatic calibration module, the temperature acquisition unit 4, the line laser vision sensor 3 and the image processing module, and is used to realize signal interaction, data transmission, collaboration and synchronization among the metrological coordinate measuring machine, the automatic calibration module, the temperature acquisition unit, the line laser vision sensor and the image processing module.

[0015] The automatic calibration device for smooth ring gauges according to an embodiment of the present invention may also include a paperless certificate entry system. This system processes the smooth ring gauge certificate data and is connected to a computer control system and a metrological coordinate measuring machine. The computer control system transmits data measured by the metrological coordinate measuring machine to the paperless certificate entry system in real time, completing the entire calibration process for the smooth ring gauge, from measurement to report output. The computer control system includes a data transmission module that enables efficient and accurate data connection and synchronization between the coordinate measuring machine and the paperless entry system, ensuring that calibration result data is transmitted to the paperless entry system in real time and in its entirety, while also ensuring the correct conversion of data formats. Data transmission is performed using a reliable network communication protocol, based on the data format requirements of both systems, using a specialized data interface program.

[0016] The automatic calibration device for a smooth ring gauge in an embodiment of the present invention utilizes the laser triangulation measurement principle and coordinate measurement technology to enable a line laser vision sensor to cooperate with a movable workbench and a self-centering fixture to scan the 3D contour of the smooth ring gauge, analyze the geometric features through an image processing module, and output data; at the same time, the automated calibration module generates a calibration program through the data output by the image processing module, and drives a metrological coordinate measuring machine to perform the measurement task, thereby realizing automated and high-precision measurement of all parameters of the smooth ring gauge.

[0017] An embodiment of the present invention further provides a method for automatically calibrating a smooth ring gauge. The method uses the automatic calibration device for a smooth ring gauge according to the embodiment of the present invention to automatically calibrate the smooth ring gauge, and includes the following stages: 1. Preparation before calibration Place the smooth ring gauge on the self-centering fixture and start the power supply of the self-centering fixture. At this time, the three-jaw support arm on the self-centering fixture completes the clamping under the interaction of the servo motor and the spiral mechanical structure, and aligns the center of the smooth ring gauge with the center of the measurement coordinate system.

[0018] 2. Image recognition stage Start the automated calibration module, trigger the movement of the movable worktable of the metrological coordinate measuring machine, and collaborate with the line laser vision sensor to complete the 3D contour scanning of the smooth ring gauge. The image processing module automatically measures key elements such as the size and thickness of the smooth ring gauge, and the output file is stored in the specified path in txt format for real-time reading by the automated calibration module.

[0019] 3. Calibration program generation and measurement task execution stage The automated calibration module adaptively adjusts the coordinate measuring machine's measurement program and path planning based on the received data information, generates a measurement plan, and the metrological coordinate measuring machine executes the measurement plan to complete the measurement of all parameters of the smooth ring gauge.

[0020] In one embodiment, the automated calibration module utilizes the LOAPRC command in the metrology-based coordinate measuring machine operating system (Quindos7) to automatically import information such as ring gauge height and inner and outer diameters generated by the image processing module. This information is read in real time and automatically integrated into the automated measurement program as variables to generate a calibration program. The calibration program includes importing external TXT text data, converting the TXT text data into character variables, processing the data into data types recognizable by Quindos7, assigning the imported data as variables to the ring gauge inspection program, generating inspection and measurement elements, and evaluating the fitting output of the measurement results.

[0021] By leveraging the image processing module and the metrological CMM operating system (Quindos7), using basic and highly operable TXT text data as the medium for information transmission, the traditional information transmission model, which relies on control cabinet systems with significant technical barriers and high costs, can be bypassed. This allows for the integration of diverse measuring and automation equipment, significantly improving measurement efficiency and reducing the integration cost of intelligent inspection automation systems. Ultimately, the metrological CMM performs calibration tasks to measure all parameters of the smooth ring gauge, including detection, acquisition, separation, extraction, fitting, and evaluation of the smooth ring gauge's surface profile.

[0022] 4. Data processing and transmission stage The computer control system connects to the coordinate measuring machine through a dedicated data interface, transmits the measurement data in real time and pushes it to the paperless certificate entry system, completing the entire closed-loop calibration of the smooth ring gauge from measurement to the synchronous output of the certificate report.

[0023] Before performing calibration, the method of the embodiment of the present invention also includes, in order to improve calibration accuracy, calibration of the coordinate measuring machine's geometric parameter errors, effective compensation of the probe diameter and detection errors, temperature monitoring and result correction, and optimization of the probe's detection speed and approach distance.

[0024] 1. Calibration of geometric parameter errors of coordinate measuring machines The calibration accuracy of the coordinate measuring machine (CMM) determines the measurement capability of the device described in this paper. Geometric parameter errors are classified according to their effects on the various degrees of freedom: three positional errors, six straightness errors, nine angular runout errors, and three perpendicularities between the three axes, for a total of 21 parameter errors. Because the functional relationships of these 21 parameter errors are complex and cannot be analyzed individually, calibration is performed separately in seven spatial directions to reflect the CMM's comprehensive error, providing significant representativeness. Compared to calibration using laser interferometers and gauge blocks, this method offers greater flexibility in spatial orientation and finer measurement intervals.

[0025] The calibration method of the embodiment of the present invention is based on the principle of spatial geometric similarity and a multi-parameter fitting algorithm. First, a 620mm step gauge is installed on the workbench of a coordinate measuring machine with a special fixture so that it forms a specific geometric relationship with the coordinate axis of the measuring machine. The probe of the coordinate measuring machine measures the various standard spacings of the step gauge according to the path predetermined by the calibration program to obtain a series of measurement data. By comparing these measurement data with the reference value of the step gauge, the measurement error is decomposed into the directions of the various motion axes of the measuring machine and the directions of the coupling between axes using the spatial geometric similarity transformation relationship. Then, a multi-parameter fitting algorithm is used to construct a geometric error model in each direction. This model can accurately describe the variation law of the geometric error of the measuring machine in different positions and postures. When actually measuring the smooth ring gauge, the corresponding error compensation value is extracted from the error model according to the coordinate information of the measuring point, and the measurement result is corrected in real time to ensure measurement accuracy.

[0026] In one embodiment, a step gauge is used at intervals of 20 mm, and calibration is performed in seven spatial directions through the cooperation of a computer control system and a measuring unit. The calibrated errors are compensated to the coordinate measuring machine, and the comprehensive error can be controlled within 0.6 μm, providing a higher measurement capability for the device of the present invention to achieve adaptive calibration of multi-specification smooth ring gauges.

[0027] Traditional calibration methods make it difficult to comprehensively and accurately quantify the geometric errors of complex coordinate measuring machines. The geometric parameter error calibration method of the embodiment of the present invention uses a step gauge with ultra-high precision and stability, combined with an advanced software compensation algorithm. It can accurately identify and subdivide the geometric parameter errors of the coordinate measuring machine in seven spatial directions, including tiny positioning errors, rotation errors, and inter-axis perpendicularity errors, etc., effectively breaking through the limitations of traditional calibration technology, greatly improving the accuracy and reliability of coordinate measuring machine geometric parameter calibration, and providing a solid foundation for subsequent high-precision measurement of smooth ring gauges.

[0028] 2. Effective compensation of probe diameter and detection errors Calibration of a smooth ring gauge requires a probe to detect the inner surface contour of the smooth ring gauge. Therefore, the effective diameter and shape errors of the probe will directly affect the final calibration accuracy of the smooth ring gauge. Therefore, it is necessary to correct the probe diameter and detection error before calibration to make the probe more suitable for the high-precision measurement requirements of the smooth ring gauge.

[0029] The traditional correction method uses a standard sphere and a corresponding calibration procedure, with the actual probe diameter and probing error programmed into the program. However, this calibration procedure uses the probe to detect the overall outline of the standard sphere, while the data programmed into the program is actually the probe's sphere diameter and sphericity. Calibration of the diameter and roundness of a smooth ring gauge operates in two dimensions, and using the calibrated sphere diameter and sphericity to approximate the diameter and roundness results in calibration errors.

[0030] To this end, the method of the present invention employs an in-situ calibration method. A stylus with a roundness error of less than 0.2 μm is selected as a reference stylus. A high-precision length measuring machine and roundness tester are used to measure the diameter and roundness error, respectively. By leveraging the open-source functionality of the metrological coordinate measuring machine (Quindos7) measurement operating system within the measurement unit, the measured diameter and roundness errors are written into a program to correct for the stylus' effective diameter and probing error. Subsequently, the method was validated by repeating the measurement 10 times using a calibrated standard ring gauge (roundness 0.5 μm, diameter 40.0001 mm). The measurement results are shown in Table 1.

[0031]

[0032] From the calibration results in Table 1, it can be seen that the differences between the diameter and roundness measurement results and the reference values ​​are all ≤0.2μm, which verifies the accuracy and feasibility of the in-situ calibration method.

[0033] By using the in-situ calibration method to calibrate the probe diameter and detection error, the true value of the roundness and the radial diameter of the probe can be cleverly separated from the spherical diameter, approximate sphericity diameter and roundness obtained by traditional calibration, providing reliable measurement accuracy for accurately measuring the roundness and straightness of the smooth ring gauge, making the probe more suitable for high-precision measurement needs.

[0034] 3. Temperature monitoring and result correction Ensuring constant temperature during the measurement process is the primary condition for achieving high-precision calibration of smooth ring gauges. The method of the embodiment of the present invention is based on heat conduction theory and multiple regression analysis algorithm. First, high-precision temperature sensors are reasonably arranged in key structural components of the coordinate measuring machine, such as coordinate axis guide rails, measured smooth ring gauges and other parts, to build a complete temperature sensing network as a temperature acquisition unit. The temperature data of each part is collected in real time through the network, and these data are transmitted to the automatic calibration module of the coordinate measuring machine. At the same time, the multiple regression analysis algorithm is used to establish a quantitative relationship model between temperature change and measurement error based on a large amount of experimental data and actual measurement data. During the measurement process, the temperature data monitored in real time is substituted into the relationship model, the measurement error caused by temperature is calculated, and the error is corrected by the automatic calibration module, thereby effectively separating the measurement error caused by temperature from the measurement results.

[0035] The method of the embodiment of the present invention adopts a temperature compensation optimization scheme based on a high-precision temperature sensing network and dynamic model correction. Taking into account the influence of temperature changes on measurement accuracy during the measurement process, multiple high-precision, high-response speed temperature sensors are used. The method can monitor the temperature changes of key parts of the coordinate measuring machine and the smooth ring gauge in real time and accurately, accurately quantify the measurement errors caused by temperature changes, and correct the measurement results in real time through an automated calibration module, effectively eliminating the interference of temperature changes on measurement accuracy, and significantly improving the measurement stability and accuracy of the coordinate measuring machine under different ambient temperatures.

[0036] In one embodiment, 10 temperature sensors are used, 9 of which are evenly distributed within the travel range of the X, Y, and Z axes of the metrological coordinate measuring machine, and 1 is attached to the optical ring gauge to be measured. The sensors are used to monitor and collect the temperature changes of the environment during the measurement process in real time. The measurement results are corrected according to formula (1), and the correction values ​​of the measurement results are written into the automatic calibration module and synchronously transmitted to the paperless certificate entry system. The actual temperature value and the compensation value are recorded in the electronic certificate. The entire correction process is completely embedded in the automatic calibration process and does not require manual intervention.

[0037] (1) Where: ——correction value of measurement result, mm; —nominal diameter of the smooth ring gauge, in mm; ——Temperature of the coordinate measuring machine scale, °C; ——Linear expansion coefficient of the coordinate measuring machine scale, mm / ℃; ——Temperature of smooth ring gauge, °C; ——Linear expansion coefficient of smooth ring gauge, mm / ℃.

[0038] The temperature variation range during the measurement process was controlled within (20 ± 0.5) °C. A smooth ring gauge with a diameter of φ320.022 mm was used to repeat the measurement 10 times. The measurement data before and after temperature variation correction were obtained, as shown in Table 2.

[0039]

[0040] The measurement data and comparison results in Table 2 show that the measurement results after temperature correction are closer to the reference values. Especially for large-scale smooth ring gauge measurements, it is particularly important to consider the temperature changes during the measurement process and the impact of the correction on the measurement results.

[0041] 4. Optimization of probe detection speed and approach distance As a key component of metrological coordinate measuring machines, the touch-trigger probe is crucial for reproducing high-precision measurements. In actual measurement, to improve efficiency, the probe often approaches the workpiece at a faster speed, then measures at a lower speed once it reaches the approach distance. The entire measurement process involves acceleration and deceleration, and the motion parameters fluctuate constantly. Dynamic errors in the probe are a major factor affecting measurement accuracy.

[0042] The method of the embodiment of the present invention measures a smooth ring gauge at different combinations of probing speeds and approach distances, collects performance indicator data on various aspects such as measurement accuracy, measurement time, and repeatability, analyzes the intrinsic relationship between probing speed, approach distance, and measurement performance indicators, derives the optimal probing speed and approach distance, and applies the optimized parameters to a coordinate measuring machine, thereby achieving high efficiency while meeting the requirements of high-precision measurement.

[0043] Traditional probing parameter settings often rely on experience, making it difficult to achieve global optimization. The method in this embodiment, through extensive experimental measurements, has collected extensive data on the relationship between probing speed, approach distance, and the measurement accuracy and range of smooth ring gauges. By using big data analysis techniques to uncover the underlying patterns in this data, it is possible to automatically identify the optimal matching combination of probing speed and approach distance, maximizing the dynamic measurement accuracy of the coordinate measuring machine (CMM), meeting the high-precision measurement requirements of smooth ring gauges across a wide range of sizes, and effectively improving measurement efficiency and quality.

[0044] In one embodiment, the probe speed is changed under different approach and retraction distance conditions, the effective diameter of the calibrated standard sphere (φ24.98604 mm) is measured, and the difference is compared to determine the optimal probe speed and approach distance parameters that need to be set for the probe. The test results are shown in Tables 3, 4, and 5.

[0045]

[0046] The test data in Tables 3, 4, and 5 demonstrate that the probe speed and approach distance parameters should be set consistently with those used during probe calibration. Furthermore, the probe speed has a far greater impact on measurement results than the approach distance, and this factor's influence on measurement results should be carefully considered in high-precision measurements. Based on this test data, the automated calibration module sets the probe speed and approach distance parameters consistent with those used during calibration to ensure that the probe's dynamic error remains stable within ±0.2μm during measurements using this device.

[0047] The following is a verification of the measurement capability of the automatic calibration device for a smooth ring gauge according to an embodiment of the present invention: 1. Verification of repeatability and stability of the device Measurement errors caused by the interaction between the line laser vision sensor and the metrological coordinate measuring machine, environmental factors during the measurement process, and measurement system drift can all affect the measurement results. First, the repeatability of the device was tested 10 times using three smooth ring gauges of different sizes within the measurement range. Second, the stability of a standard ring gauge (φ40.0001mm) was tested six times at different time points. The test results showed that the dispersion of the measurement repeatability and stability test results was ≤0.4μm, meeting the expected requirements.

[0048] 2. Accuracy verification based on second-class standard ring gauge Once the device's measurement repeatability and stability meet the expected requirements, accuracy verification using a secondary standard ring gauge is proposed to evaluate the device's calibration accuracy. Based on JJF 1117-2010, "Technical Specifications for Metrological Comparison," the normalized deviation (see Formula 2) is calculated to verify the accuracy of the calibration results. The comparison data for the device's calibration results are shown in Table 6.

[0049] (2) ——Normalized deviation, verification data <1, the result is satisfactory, verification data >1, the result is unsatisfactory.

[0050] ——calibration result of the device, mm; ——reference value of second-class standard ring gauge, mm; —Measurement uncertainty of the device, μm; ——Measurement uncertainty when tracing back to a second-class standard ring gauge, μm.

[0051]

[0052] From the comparison data of the calibration results and the verification results in Table 6, it can be seen that the En values ​​are all less than 1, the verification results are satisfactory, the calibration accuracy of the device meets the requirements, and its measurement capability U =0.6μm +3.3×10 -6 L ( k =2).

[0053] Compared with the prior art, the automatic calibration device for a smooth ring gauge according to the embodiment of the present invention has the following beneficial effects: (1) Expanded measurement range Compared with the existing calibration method of smooth ring gauges, which are limited by the measuring stroke of the length gauge grating scale and the minimum processing limit of the double measuring hooks, the measurement range is usually between φ15mm and φ150mm. The calibration technology of smooth ring gauges based on metrological coordinate measuring machines has broken through the measurement range limitations of traditional length gauges due to their own structure and probe limitations. The working stroke of the coordinate measuring machine grating scale determines the upper measurement limit of the smooth ring gauge, and the processing limit of the probe probe determines the lower measurement limit of the smooth ring gauge. At present, the processing limit of the probe probe can be as low as φ0.5mm, which can realize the measurement of smooth ring gauges from φ2mm to φ500mm, and the measurement range is significantly improved.

[0054] (2) The measurement is more representative Based on the relevant requirements of JJG 343-2012 "Verification Procedure for Smooth Limit Gauges" and JJG 894-1995 "Verification Procedure for Standard Ring Gauges", the use of a length measuring instrument requires measuring four positions of the smooth ring gauge in the upper and lower directions on the AB section, and the diameter variation is used to reflect the shape error of the smooth ring gauge. However, the position and wear of the smooth ring gauge in actual use are random. The control of the diameter variation cannot fully reflect the actual shape error of the smooth ring gauge, and its measuring points are not representative enough. In particular, smooth gauges used in the aerospace field (such as table rings and table parts) need to increase the measurement requirements of roundness and straightness to fully reflect their shape characteristics. The use of a metrological coordinate measuring machine can achieve uniform point detection or scanning throughout the entire measuring range of the smooth ring gauge, which can more intuitively and comprehensively reflect its shape error.

[0055] (3) Improved measurement efficiency The calibration items for smooth ring gauges include diameter size, diameter variation, roundness, and straightness. The traditional calibration method uses a length gauge to measure the diameter size and variation by comparing it with a standard ring gauge, then uses a roundness gauge for secondary clamping. After centering and leveling, the roundness and straightness are measured. For experienced operators, the measurement takes about 30 minutes per piece. However, the device of the embodiment of the present invention, by designing a self-centering fixture and a collaborative measurement system, can simultaneously complete the calibration of all parameters of diameter, diameter variation, roundness, and straightness in a single clamping of the smooth ring gauge. At the same time, the combination of visual recognition technology and adaptive calibration module also reduces the time of programming measurement parameters, making the overall measurement time about 3 minutes per piece, significantly improving measurement efficiency.

[0056] (4) Accurate and reliable measurement accuracy The self-centering fixture of the device of the embodiment of the present invention can realize the clamping and positioning of smooth ring gauges of different specifications, with a positioning accuracy of less than 0.3mm, effectively avoiding interference with the probe path, which is particularly important for measuring small-sized smooth ring gauges. The measurement process is unmanned, which can effectively reduce the impact of temperature fluctuations and air disturbances on the measurement results. The configured multi-channel temperature sensor can monitor the temperature changes during the three-axis coordinate measuring machine and smooth ring gauge measurement process in real time, and correct the measurement results using formula (1), significantly improving the measurement accuracy of large-size smooth ring gauges. The in-situ calibration method is used to effectively compensate for the probe diameter and roundness errors, greatly improving the measurement accuracy. As shown in Table 1, the difference between the diameter and roundness measurement results and the reference values ​​is ≤0.2μm, verifying the accuracy and feasibility of the in-situ calibration method. The measurement results of this device were verified based on the second-class standard ring gauge (see Table 6), En≤0.5, and the measurement results were accurate and reliable.

[0057] (5) Improve the level of automation and intelligence Developed based on the Quindos 7 open-source system, the automated calibration module, visual recognition, and coordinate measurement technologies combine to automate and intelligently implement the calibration process. The visual recognition system automatically captures the ring gauge's geometric features. The adaptive calibration module adjusts the measurement plan in real time based on this input, driving the coordinate measuring machine to perform the measurement task. The entire calibration process requires no human intervention. The collaborative operation of these modules transforms the calibration process from traditional manual operation to automated and intelligent one, reducing the impact of human factors on calibration results and improving the stability and reliability of measurement results.

[0058] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. An automatic calibration device for a smooth ring gauge, characterized in that: Including clamping and positioning unit, visual recognition unit, measuring unit and computer control system, The measuring unit includes a metrological coordinate measuring machine, an automated calibration module, and a temperature acquisition unit; the visual recognition unit includes a line laser vision sensor and an image processing module; and a computer control system is connected to the metrological coordinate measuring machine, the automated calibration module, the temperature acquisition unit, the line laser vision sensor, and the image processing module to realize data transmission and collaboration among the metrological coordinate measuring machine, the automated calibration module, the temperature acquisition unit, the line laser vision sensor, and the image processing module; The clamping and positioning unit is installed on the movable worktable of the metrological coordinate measuring machine and is used to clamp and position the smooth surface ring gauge to be measured. The line laser vision sensor is installed above the movable worktable of the metrological coordinate measuring machine and cooperates with the movable worktable to scan the 3D contour of the smooth surface ring gauge using laser triangulation to obtain point cloud data. The image processing module uses an image recognition algorithm based on deep learning to identify and analyze the point cloud data of the 3D contour of the smooth surface ring gauge, obtain the geometric feature information of the smooth surface ring gauge, and transmit it to the automatic calibration module in real time. The automatic calibration module adjusts the measurement plan in real time according to the received geometric feature information of the smooth surface ring gauge. The metrological coordinate measuring machine performs measurement of all parameters of the smooth surface ring gauge according to the adjusted measurement plan. The temperature acquisition unit includes multiple temperature sensors installed on the metrological coordinate measuring machine and the smooth ring gauge being measured, which are used to monitor and collect the temperature changes of the environment during the measurement process in real time and transmit them to the automatic calibration module. The automatic calibration module corrects the measurement results of the smooth ring gauge based on the received ambient temperature changes.

2. The device according to claim 1, wherein It also includes a paperless certificate entry system, which is connected to the computer control system and is used to receive measurement data of the metrological coordinate measuring machine from the computer control system in real time and output a smooth ring gauge calibration report.

3. The device according to claim 1 or 2, characterized in that The clamping and positioning unit is a self-centering fixture that can clamp and position smooth ring gauges of different specifications with a positioning accuracy of <0.3mm.

4. The device according to claim 1 or 2, characterized in that The measurement plan includes the selection of the probe, path planning and measurement point distribution. The full parameters of the smooth ring gauge include diameter size, diameter variation, roundness and straightness measurement.

5. A method for automatic calibration of a smooth ring gauge, characterized in that: Automatic calibration of a smooth ring gauge using the device according to any one of claims 1 to 4, comprising: Place the smooth ring gauge on the clamping and positioning unit to complete the clamping, and align the center of the smooth ring gauge with the center of the measuring coordinate system; The movable worktable of the metrological coordinate measuring machine moves and collaborates with the line laser vision sensor to complete the 3D contour scanning of the smooth ring gauge. The image processing module extracts the geometric feature information and transmits it to the automated calibration module. The automated calibration module adaptively adjusts the measurement plan of the metrological coordinate measuring machine based on the received geometric feature information, and the metrological coordinate measuring machine performs full parameter measurement of the smooth ring gauge based on the adjusted measurement plan; The computer control system transmits the data measured by the metrological coordinate measuring machine to the certificate paperless entry system in real time. The certificate paperless entry system outputs the smooth ring gauge calibration report, thus completing the entire calibration activity of the smooth ring gauge from measurement to report output.

6. The method according to claim 5, wherein Also includes: Using high-precision step gauges, through the mutual cooperation of computer control system and measuring unit, the geometric parameter errors of the metrological coordinate measuring machine are calibrated in 7 directions of space, and the calibrated errors are compensated to the metrological coordinate measuring machine.

7. The method according to claim 5 or 6, wherein: Also includes: The in-situ calibration method is adopted, and a stylus with a roundness error of less than 0.2μm is selected as the reference stylus. A high-precision length measuring machine and roundness meter are used to measure the diameter and roundness errors of the metrological coordinate measuring machine's probe respectively, and the measured diameter and roundness errors are compensated to the metrological coordinate measuring machine.

8. The method according to claim 5 or 6, wherein: Also includes: High-precision temperature sensors are placed on the grating scale of the metrological coordinate measuring machine and the smooth surface ring gauge to be measured, and the temperature data of each temperature sensor is monitored in real time and transmitted to the automated calibration module; A multiple regression analysis algorithm is used to establish a relationship model between temperature change and measurement error. During the measurement process, the real-time monitored temperature data is substituted into the relationship model to calculate the measurement error caused by temperature, and the measurement results are corrected through the automated calibration module.

9. The method according to claim 8, wherein Correct the measurement results according to the following formula: Where: —Correction value of measurement result; —nominal diameter of smooth ring gauge; — Temperature of the coordinate measuring machine scale; —Linear expansion coefficient of coordinate measuring machine scale; — Temperature of smooth ring gauge; —Linear expansion coefficient of smooth ring gauge.

10. The automatic calibration method for a smooth ring gauge according to claim 5 or 6, characterized in that: Also includes: The smooth ring gauge is measured at different combinations of probing speeds and approach distances, and measurement performance index data are collected. The intrinsic relationship among probing speed, approach distance and measurement performance index is analyzed, and the optimal probing speed and approach distance are derived as the optimization parameters of the probe of the metrological coordinate measuring machine.

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