A method and system for detecting the sealing performance of a pneumatic cylinder

Abstract

This invention discloses a method and system for testing the sealing performance of pneumatic cylinders, relating to the field of pneumatic cylinder testing technology. The method includes: performing multi-dimensional non-destructive testing on seamless steel pipe raw materials for the pneumatic cylinder to obtain raw material fingerprint data; establishing a structural mapping relationship between the raw material and the pneumatic cylinder to obtain structural correction parameters for the pneumatic cylinder; conducting alternating pressure tests on the pneumatic cylinder and acquiring dynamic sealing performance data of the cylinder in real time; performing temperature effect compensation and structural elasticity compensation processing to obtain actual leakage pressure change data and calculate the theoretical leakage rate after material compensation; performing deviation analysis between the measured leakage rate and the theoretical leakage rate, outputting the sealing performance test results based on the deviation results, and identifying the leakage cause as a defect in the raw material structure or an assembly process defect. This method solves the technical problem of insufficient accuracy in the sealing performance testing of pneumatic cylinders in existing technologies, achieving the technical effect of improving the accuracy of sealing performance testing.

Description

Technical Field

[0001] This invention relates to the field of pneumatic cylinder testing technology, specifically to a method and system for testing the sealing performance of pneumatic cylinders. Background Technology

[0002] As a critical pressure-bearing component of pneumatic actuators, the sealing performance of pneumatic cylinders directly affects the output stability, energy utilization efficiency, and operational safety of pneumatic systems. In practical applications, pneumatic cylinders operate under alternating pressure and reciprocating motion conditions for extended periods. Even minor leaks or seal failures can lead to decreased system efficiency, abnormal equipment vibration, or even functional failure. Current technologies typically test the sealing performance of pneumatic cylinders using static pressure tests or simple pressure holding tests, determining compliance by monitoring pressure drop or leakage. However, these testing methods are often based on single operating conditions or static testing, failing to adequately consider the impact of differences in the internal microstructure of raw materials, elastic deformation characteristics, and temperature variations on leakage behavior. Furthermore, during the analysis of test results, it is often difficult to distinguish between leaks caused by structural defects in raw materials and defects in the assembly process, resulting in insufficient accuracy and limited defect localization capabilities. Summary of the Invention

[0003] This application provides a method and system for testing the sealing performance of pneumatic cylinders, which solves the technical problem of insufficient accuracy in the testing of the sealing performance of pneumatic cylinders in the prior art.

[0004] The first aspect of this application provides a method for testing the sealing performance of a pneumatic cylinder, the method comprising: Multidimensional non-destructive testing is performed on seamless steel pipe raw materials based on pneumatic cylinders to obtain raw material fingerprint data. A structural mapping relationship between the raw material and the pneumatic cylinder is established based on the raw material fingerprint data to obtain structural correction parameters for the pneumatic cylinder, including elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient. The pneumatic cylinder undergoes alternating pressure testing under operating conditions, and dynamic sealing performance data of the cylinder is collected in real time, including instantaneous leakage, pressure drop, and fluctuations in kinetic friction. Temperature influence compensation and structural elasticity compensation are applied to the collected dynamic sealing performance data to obtain actual leakage pressure change data. The actual leakage pressure change data and the structural correction parameters are input into a pre-constructed sealing performance prediction model to calculate the theoretical leakage rate after material compensation. Deviation analysis is performed between the measured leakage rate and the theoretical leakage rate. Based on the deviation results, the sealing performance test results are output, and the cause of leakage is identified as a structural defect in the raw material or a defect in the assembly process.

[0005] A second aspect of this application provides a system for testing the sealing performance of a pneumatic cylinder, the system comprising: The system comprises the following modules: Non-destructive testing module: Performs multi-dimensional non-destructive testing on the seamless steel pipe raw material of the pneumatic cylinder to obtain raw material fingerprint data; Parameter establishment module: Establishes a structural mapping relationship between the raw material and the pneumatic cylinder based on the raw material fingerprint data, obtaining structural correction parameters for the pneumatic cylinder, including elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient; Performance testing module: Conducts alternating pressure tests on the pneumatic cylinder, acquiring dynamic sealing performance data in real time, including instantaneous leakage, pressure drop, and fluctuations in kinetic friction; Calculation module: Performs temperature influence compensation and structural elasticity compensation processing on the acquired dynamic sealing performance data to obtain actual leakage pressure change data. The actual leakage pressure change data and the structural correction parameters are input into a pre-constructed sealing performance prediction model to calculate the theoretical leakage rate after material compensation; Analysis module: Performs deviation analysis between the measured leakage rate and the theoretical leakage rate, outputs sealing performance test results based on the deviation results, and identifies the leakage cause as a raw material structural defect or assembly process defect.

[0006] One or more technical solutions provided in this application have at least the following technical effects or advantages: First, multi-dimensional non-destructive testing is performed on the seamless steel pipe raw material of the pneumatic cylinder to obtain raw material fingerprint data. Next, a structural mapping relationship between the raw material and the pneumatic cylinder is established based on the raw material fingerprint data, yielding structural correction parameters for the pneumatic cylinder, including elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient. Then, the pneumatic cylinder undergoes alternating pressure testing, and dynamic sealing performance data is collected in real time, including instantaneous leakage, pressure drop, and fluctuations in kinetic friction. Further, temperature influence compensation and structural elasticity compensation are applied to the collected dynamic sealing performance data to obtain actual leakage pressure variation data. This actual leakage pressure variation data and the structural correction parameters are input into a pre-constructed sealing performance prediction model to calculate the theoretical leakage rate after material compensation. Finally, a deviation analysis is performed between the measured leakage rate and the theoretical leakage rate. Based on the deviation results, the sealing performance test results are output, and the cause of leakage is identified as either a structural defect in the raw material or a defect in the assembly process. This method solves the technical problem of insufficient accuracy in the sealing performance testing of pneumatic cylinders in existing technologies, achieving the technical effect of improving the accuracy of sealing performance testing. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 A schematic flowchart of a method for testing the sealing performance of a pneumatic cylinder provided in an embodiment of this application; Figure 2 This is a schematic diagram of a pneumatic cylinder sealing performance testing system provided in an embodiment of this application.

[0009] Figure labeling: Non-destructive testing module 11, parameter establishment module 12, performance testing module 13, calculation module 14, analysis module 15. Detailed Implementation

[0010] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0011] Example 1, as Figure 1 As shown, this application provides a method for testing the sealing performance of a pneumatic cylinder, wherein the method includes: Multidimensional non-destructive testing was performed on seamless steel pipe raw materials based on pneumatic cylinders to obtain raw material fingerprint data.

[0012] Furthermore, obtaining raw material fingerprint data includes: Multidimensional non-destructive testing is performed on the seamless steel pipe raw material of the pneumatic cylinder, including ultrasonic testing, eddy current testing and surface profile spectrum analysis, to obtain raw material test data including elastic modulus deviation parameters, wall thickness uniformity parameters, internal surface roughness spectrum characteristic parameters and micro-defect density parameters; based on the raw material test data, the raw material fingerprint data is constructed.

[0013] Preferably, the seamless steel pipe raw materials for pneumatic cylinders are batch numbered and barcode identified, and an axial-circumferential two-dimensional spatial coordinate system is established. The steel pipe is divided into several detection units along the axial direction according to a preset length ΔL (e.g., 10mm~50mm), and detection zones are divided along the circumferential direction according to a preset angle Δθ (e.g., 5°~15°) to form a spatial grid index for the positioning and fusion of subsequent detection data.

[0014] Based on this, multi-dimensional non-destructive testing is performed on the raw materials of seamless steel pipes: Ultrasonic testing: A multi-channel phased array ultrasonic testing system is used to continuously scan along the axial direction of the steel pipe. The echo time difference and echo amplitude information are obtained by emitting longitudinal and transverse wave signals. The actual wall thickness of each testing unit is calculated based on the sound velocity calibration data, and the difference is calculated with the design wall thickness to obtain the wall thickness uniformity parameter. At the same time, the local elastic modulus value of the material is deduced from the ultrasonic wave propagation time and echo attenuation characteristics, and compared with the standard elastic modulus to obtain the elastic modulus deviation parameter. Defect size inversion analysis is performed on the echo anomaly area to form internal defect distribution data.

[0015] Eddy current testing: A rotating differential eddy current probe is used to scan the inner and outer surfaces of the steel pipe and collect the induced impedance change signal in real time; by frequency domain filtering and phase discrimination algorithm, the crack signal and the microstructure change signal are separated, and the number of defects per unit area in the detection area is statistically analyzed to obtain the micro-defect density parameter; at the same time, the signal amplitude and phase offset are analyzed to form surface conductivity anomaly distribution data.

[0016] Surface profile spectrum analysis: The inner surface of the steel pipe is continuously scanned along the axial direction using a high-precision laser displacement sensor or an internal bore profile scanner to collect the original profile height data; the profile height data is detrended and bandpass filtered, and then subjected to fast Fourier transform to obtain the roughness spectrum curve; parameters such as the amplitude of the main frequency component, the frequency band energy distribution, and the roughness arithmetic mean are extracted from the spectrum curve to form the inner surface roughness spectrum characteristic parameters.

[0017] After completing the above multidimensional detection, the ultrasonic detection data, eddy current detection data, and surface profile spectrum data are aligned and fused according to the spatial grid index. A multidimensional feature vector containing elastic modulus deviation parameters, wall thickness uniformity parameters, internal surface roughness spectrum characteristic parameters, and micro-defect density parameters is constructed for each detection unit. The multidimensional feature vector is normalized and outlier is removed to finally form raw material fingerprint data that can uniquely characterize the physical properties and microstructure characteristics of the batch of seamless steel pipe raw materials.

[0018] Based on the raw material fingerprint data, a raw material-pneumatic cylinder structure mapping relationship is established to obtain the pneumatic cylinder structure correction parameters, which include elastic expansion correction coefficient, microchannel formation probability coefficient and sealing contact matching correction coefficient.

[0019] During the pneumatic cylinder manufacturing process, the axial position and circumferential angle of the seamless steel pipe raw material are encoded and recorded. The material source location is simultaneously retained during cutting, turning, and honing processes, thus establishing a one-to-one correspondence between the spatial coordinates of the raw material and the structural coordinates of the finished pneumatic cylinder. The elastic modulus deviation parameter, wall thickness uniformity parameter, internal surface roughness spectrum characteristic parameter, and micro-defect density parameter from the raw material fingerprint data are mapped to the corresponding cylinder structural units, constructing a structural mapping model that includes the distribution of material physical properties. Based on this structural mapping model, a radial elastic expansion finite element simulation is performed under rated operating pressure conditions, comparing the radial expansion under actual material parameter conditions with the expansion under standard material conditions. The elastic expansion correction coefficient is obtained by calculating the ratio of the quantities. A microscopic surface model of the sealing contact is constructed based on the characteristic parameters of the inner surface roughness spectrum and the micro-defect density parameters. The probability value of forming a continuous leakage channel within a unit contact length is obtained through peak-valley statistical analysis and probability calculation, and the microchannel formation probability coefficient is determined. A sealing contact pressure distribution model is established by combining the wall thickness uniformity parameters, the micro-defect density parameters and the sealing ring design dimensions. The sealing contact matching correction coefficient is obtained by calculating the degree of matching between the actual contact pressure distribution and the standard contact pressure distribution. Finally, the elastic expansion correction coefficient, the microchannel formation probability coefficient and the sealing contact matching correction coefficient are normalized and output as the structural correction parameters of the pneumatic cylinder.

[0020] Furthermore, the structural correction parameters for the pneumatic cylinder are obtained, including: Based on the structural mapping relationship between the pneumatic cylinder structure and the seamless steel pipe raw material, a structural mapping model is constructed. According to the relationship between the raw material fingerprint data and the positional distribution of the raw material, the structural mapping model of the fingerprint data is projected to construct the raw material-pneumatic cylinder structure mapping relationship. Based on the raw material-pneumatic cylinder structure mapping relationship, the physical property mapping analysis of the raw material of the pneumatic cylinder structure is performed to obtain the physical property distribution of the pneumatic cylinder structure. Based on the physical property distribution, corresponding compensation and correction are performed to obtain the structural correction parameters.

[0021] First, based on the detection grid division results of seamless steel pipe raw materials in the axial and circumferential directions, a correspondence rule between the spatial coordinates of the raw material and the structural coordinates of the finished cylinder is established during the pneumatic cylinder processing. The cutting section position, inner hole processing area, and sealing contact area are divided into structural units, constructing a three-dimensional structural mapping model containing axial position, circumferential angle, and wall thickness level information. Then, according to the relationship between the raw material fingerprint data and the spatial distribution of the raw material, the elastic modulus deviation parameter, wall thickness uniformity parameter, inner surface roughness spectrum characteristic parameter, and micro-defect density parameter are projected onto the corresponding cylinder structural units, realizing the spatial projection of the fingerprint data in the structural mapping model and forming a raw material-pneumatic cylinder structural mapping relationship. Based on this, each structure... The material physical properties of each unit are analyzed. The radial deformation sensitivity of each unit is calculated based on the elastic modulus distribution. The micro-leakage sensitivity of the sealing contact interface is calculated based on the roughness spectrum characteristics and micro-defect density. The degree of local compressive stress concentration is analyzed based on the wall thickness uniformity parameter, thereby obtaining the physical property distribution map of the overall structure of the pneumatic cylinder. Finally, based on the physical property distribution, compensation and correction calculations are performed under rated operating pressure and sealing contact conditions to determine the compensation amount for gap change caused by material elasticity, the correction amount for microchannel formation probability, and the correction amount for sealing contact pressure distribution. The corresponding calculation results are normalized to obtain the elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient, which are used as the structural correction parameters of the pneumatic cylinder.

[0022] Furthermore, based on the physical property distribution, corresponding compensation and correction are performed to obtain the structural correction parameters, including: Based on the elastic modulus deviation parameter and wall thickness uniformity parameter in the raw material fingerprint data, a pressure radial expansion simulation analysis of the pneumatic cylinder operation is performed to determine the pressure change relationship of elastic expansion, and elastic expansion compensation correction is performed to obtain the elastic expansion correction coefficient. According to the influence relationship of the internal surface roughness spectrum characteristic parameter on the formation of micro-leakage channels, a micro-channel formation probability compensation analysis is performed to determine the micro-channel formation probability coefficient. According to the influence of micro-defect density parameter and internal hole size accuracy on the sealing contact pressure distribution, a sealing contact matching compensation correction is performed to obtain the sealing contact matching correction coefficient. The elastic expansion correction coefficient, micro-channel formation probability coefficient, and sealing contact matching correction coefficient are used as the structural correction parameters.

[0023] First, by using the elastic modulus deviation and wall thickness uniformity parameters from the raw material fingerprint data, an axisymmetric structural model of the pneumatic cylinder under internal pressure is established in a three-dimensional finite element simulation platform. Boundary conditions of rated maximum and minimum working pressures are applied, and the radial displacement of the cylinder's inner wall under different pressure levels is calculated. A pressure-radial expansion function curve is then established. The ratio of the radial expansion under actual material parameters to the theoretical expansion under standard material parameters is calculated to obtain an elastic expansion correction coefficient reflecting the degree of influence of material elasticity differences. Second, based on the dominant frequency amplitude, peak-valley height distribution, and frequency band energy density in the internal surface roughness spectrum characteristic parameters, a microscopic interface model of the sealing contact is constructed. The number of continuous peak-valley paths within a unit contact length is statistically analyzed. The probability of forming a through-channel microleakage under a given contact pressure is calculated using a microfluidic permeation model, and the probability coefficient of microchannel formation is determined through probability normalization. Next, based on micro-defect density parameters and internal bore dimensional tolerance data, a sealing ring-cylinder contact pressure distribution model is established. By calculating the deviation index (e.g., root mean square error or contact stress uniformity coefficient) between the actual contact pressure distribution curve and the design standard contact pressure curve, sealing contact matching compensation correction is performed to obtain the sealing contact matching correction coefficient. Finally, the elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient are uniformly dimensioned and normalized to serve as structural correction parameters for the pneumatic cylinder, used for subsequent sealing performance prediction and deviation determination.

[0024] The pneumatic cylinder is subjected to alternating working pressure tests, and dynamic sealing performance data of the cylinder is collected in real time. The dynamic sealing performance data includes instantaneous leakage, pressure drop and fluctuation of motion friction.

[0025] Furthermore, the pneumatic cylinder is subjected to alternating operating pressure tests, and dynamic sealing performance data of the cylinder is collected in real time, including: Based on the working scenario of the pneumatic cylinder, the maximum and minimum pressure values ​​of the alternating working conditions are determined; an alternating working conditions test is applied to the pneumatic cylinder, including cyclically loading and unloading the pressure between the maximum and minimum pressure values ​​at a set frequency; during the execution of the alternating test, the instantaneous leakage, pressure change, and piston rod motion friction fluctuation are collected in real time to obtain the dynamic sealing performance data.

[0026] First, based on the design parameters and actual usage scenarios of the pneumatic cylinder (e.g., rated working pressure, ultimate pressure, and typical start-stop frequency), determine the maximum and minimum pressure values ​​for the alternating working pressure. The maximum pressure value should not exceed the safe upper limit of the design rated pressure, and the minimum pressure value should be close to atmospheric pressure or the minimum working pressure. Then, install the pneumatic cylinder under test on a sealing performance test bench. Apply pressure to the inside of the cylinder using a programmable air source control system and a proportional pressure regulating valve. Perform periodic loading and unloading operations between the maximum and minimum pressure values ​​at a set frequency (e.g., 0.1Hz~5Hz) to create an alternating pressure environment simulating actual working conditions. During the alternating test... During the process, high-precision pressure sensors are arranged at the intake end and inside the cylinder cavity to collect pressure change curves and calculate pressure drop data in real time. At the same time, high-sensitivity mass flow meters or micro-flow sensors are set at the exhaust end or sealing monitoring end to continuously collect the volume or mass flow rate of leaked gas per unit time to obtain instantaneous leakage data. During the reciprocating motion of the piston rod, a tension-compression force sensor or friction detection module is set at the piston rod drive end to collect friction change signals in real time, forming a friction fluctuation curve. Finally, the instantaneous leakage, pressure change, and friction fluctuation data are time-synchronized and uniformly sampled to construct complete dynamic sealing performance data for subsequent compensation and analysis.

[0027] Temperature influence compensation and structural elasticity compensation are applied to the collected dynamic sealing performance data to obtain the actual leakage pressure change data. The actual leakage pressure change data and the structural correction parameters are then input into the pre-constructed sealing performance prediction model to calculate the theoretical leakage rate after material compensation.

[0028] During the pressure alternation test, temperature sensors were installed on the outer wall of the pneumatic cylinder cavity and at the inlet end to collect real-time data on gas temperature and cylinder wall temperature. Based on the ideal gas law or a corrected model of the actual gas, the impact of temperature changes on the cavity pressure readings was calculated, and the pressure change component caused by temperature fluctuations was removed from the original pressure change data to achieve temperature impact compensation. Secondly, based on the aforementioned elastic expansion correction coefficient and the pressure-radial expansion relationship curve obtained from finite element simulation, the effective volume change of the cavity caused by the elastic deformation of the cylinder under the current test pressure was calculated, and the pressure change component corresponding to this volume change was subtracted from the compensated pressure data to complete the structural elastic compensation process. After temperature compensation and structural elasticity compensation, the actual leakage pressure change data caused only by actual leakage behavior is obtained. Subsequently, the actual leakage pressure change data is combined with structural correction parameters (including elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient) to form an input vector, which is input into a pre-constructed sealing performance prediction model. The sealing performance prediction model is established based on a physical leakage mechanism model or a regression model trained with historical samples, and is used to characterize the functional mapping relationship between material properties and leakage rate. The model calculates the theoretical leakage rate curve under the condition of considering material differences and structural compensation according to the input parameters, and outputs the theoretical leakage rate after material compensation, which is used for subsequent deviation analysis and sealing performance determination.

[0029] Furthermore, temperature effect compensation and structural elasticity compensation are applied to the collected dynamic sealing performance data to obtain the actual leakage pressure change data, including: Based on the cylinder material properties and structural parameters, the elastic expansion of the cylinder caused by pressure changes is analyzed, and the corresponding pressure changes are removed from the dynamic sealing performance data. Based on the dynamic pressure data and synchronously acquired temperature measurements, the impact of temperature changes on the pressure readings is calculated, and the pressure data is compensated. The dynamic sealing performance data after elastic expansion and temperature compensation processing is used as the actual leakage pressure change data.

[0030] First, based on the cylinder material properties, including elastic modulus and Poisson's ratio, and structural parameters including inner diameter, wall thickness, and effective cavity length, a cylinder stress analysis model under internal pressure is established. The theoretical radial expansion of the cylinder inner wall is calculated under the corresponding pressure conditions at each moment, and further converted into the change in effective cavity volume. Based on the correspondence between cavity volume change and pressure change, the pressure change component caused by the cylinder's elastic expansion is calculated, and this pressure change is removed from the original dynamic pressure data, thus completing structural elastic compensation. Second, gas temperature data is simultaneously collected during the pressure alternation test. Based on the gas state relationship, the influence of temperature change on the cavity pressure reading is calculated under the condition that the gas mass remains constant, and this temperature influence component is subtracted from the pressure data after structural compensation, achieving temperature influence compensation. Finally, the pressure change data after simultaneous structural elastic compensation and temperature compensation is used as the actual leakage pressure change data, reflecting only the pressure attenuation characteristics caused by actual leakage behavior, for subsequent leakage rate calculation and sealing performance analysis.

[0031] Furthermore, the actual leakage pressure variation data and the structural correction parameters are input into a pre-built sealing performance prediction model to calculate the theoretical leakage rate after material compensation, including: The actual leakage pressure change data and the structural correction parameters are used as input vectors and fed into the pre-built sealing performance prediction model. Combining structural characteristics and material parameters, the dynamic leakage pressure is mapped to the theoretical leakage rate, and the theoretical leakage rate after material compensation is output. The pre-built sealing performance prediction model calculates the theoretical leakage rate curve after considering material differences based on trained or pre-set physical laws.

[0032] First, the actual leakage pressure change data is organized chronologically to form a continuous pressure decay data sequence. This sequence is then combined with the test time interval and the effective volume parameter of the cylinder cavity to construct dynamic pressure change characteristics. Simultaneously, the elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient in the structural correction parameters are normalized to ensure they are in a unified dimensional system with the pressure change characteristics, forming the input data set for the prediction model. Subsequently, this input data set is fed into a pre-constructed sealing performance prediction model. This model, based on fluid leakage mechanisms and historical calibration data, describes the mapping relationship between material properties, structural state, and leakage behavior. Internally, the model combines cylinder structural parameters, material physical properties, and pressure decay rate to compensate and correct the equivalent leakage channel area. It also calculates the theoretical leakage volume change rate under current material conditions based on gas flow laws, outputting the theoretical leakage rate curve after material compensation. This prediction model can be trained using historical sample data or constructed based on preset physical laws and parameter calibration. It generates theoretical leakage rate results considering material differences and structural correction factors, providing a benchmark for subsequent deviation analysis and sealing performance judgment.

[0033] The measured leakage rate is compared with the theoretical leakage rate. Based on the deviation results, the sealing performance test results are output, and the cause of leakage is located as a defect in the raw material structure or a defect in the assembly process.

[0034] First, based on the actual leakage pressure change data combined with the effective volume of the cylinder cavity and the test time parameters, the pressure decay rate is converted into a measured leakage rate data sequence. Then, the measured leakage rate and the theoretical leakage rate after material compensation are aligned point-by-point and the difference is calculated within the same time interval to obtain leakage rate deviation data. Furthermore, the overall average deviation, peak deviation, and fluctuation amplitude are calculated to form a comprehensive deviation evaluation result. This comprehensive deviation evaluation result is compared with a preset deviation threshold range. When the deviation is within the allowable range and the fluctuation is stable, the sealing performance is determined to be at a qualified level. When the deviation approaches the threshold or there are local abnormal peaks, it is determined to be at a warning level. When the deviation exceeds the allowable threshold... If the leakage rate is within the acceptable range or there is a persistent abnormal peak, it is judged as unqualified. After the sealing level is determined, the contribution decomposition analysis is performed by combining the microchannel formation probability coefficient and the sealing contact matching correction coefficient in the structural correction parameters. When the theoretical compensation is sufficient but the measured leakage rate is still significantly high and the microchannel formation probability coefficient is low, the cause of leakage is determined to be assembly process defect. When the microchannel formation probability coefficient is high and consistent with the deviation change trend, the cause of leakage is determined to be raw material structural defect. When both types of correction coefficients show abnormality and contribute significantly to the deviation, it is determined to be the coupling effect of raw material structural defect and assembly process defect, thereby realizing the output of sealing performance test results and accurate location of leakage cause.

[0035] Furthermore, a deviation analysis is performed between the measured leakage rate and the theoretical leakage rate, including: Based on the actual leakage pressure change data and the cylinder cavity volume, the pressure change is converted into a measured leakage rate; the difference between the measured leakage rate and the theoretical leakage rate after material compensation is calculated to obtain the deviation result.

[0036] Preferably, the pressure decay per unit time is obtained based on the actual leakage pressure change data, and combined with the effective volume parameters of the pneumatic cylinder cavity and the test time interval, the pressure change is converted into the gas volume change per unit time according to the gas state relationship, thereby obtaining the measured leakage rate data sequence within the corresponding time period; after completing the calculation of the measured leakage rate, the measured leakage rate and the theoretical leakage rate after material compensation are aligned at the same time node, and the instantaneous deviation value is obtained by calculating the difference point by point, and the average deviation, maximum deviation and deviation fluctuation amplitude are further statistically analyzed to form an overall deviation result, which is used for subsequent sealing performance judgment and defect location analysis.

[0037] Furthermore, based on the deviation results, the sealing performance test results are output, and the cause of leakage is located as a defect in the raw material structure or an assembly process defect, including: The deviation results are compared with deviation thresholds to determine the sealing performance level. A deviation within the allowable range without local anomalies is considered a qualified level; a deviation within the allowable range but with local microchannels or abnormal friction fluctuations is a warning level; and a deviation exceeding the allowable range or with local leakage spikes is a non-qualified level. Based on the deviation analysis results, and combining the contribution decomposition of the microchannel formation probability coefficient and the sealing contact matching correction coefficient in the structural correction parameters, the cause of leakage is located. Specifically, when the deviation rate meets the deviation threshold and the microchannel formation probability coefficient is less than the probability threshold, the leakage cause is determined to be a microstructural defect in the raw material; when the deviation rate exceeds the deviation threshold and the sealing contact matching correction coefficient is less than the matching threshold, the leakage cause is determined to be an assembly process defect; when the deviation rate exceeds the deviation threshold and simultaneously satisfies both the microchannel formation probability coefficient and the sealing contact matching correction coefficient being less than the matching threshold, the leakage is determined to be a coupling effect between raw material structural defects and assembly process defects.

[0038] Preferably, the obtained overall deviation result is compared and analyzed with a preset deviation threshold range, wherein the preset deviation threshold is determined based on historical qualified sample statistical data or standard operating condition test data; when the deviation between the measured leakage rate and the theoretical leakage rate is within the allowable range and the deviation curve has no continuous abnormal fluctuations or local peaks, the sealing performance level is determined to be qualified; when the deviation is within the allowable range but there are microchannel characteristic fluctuations or abnormal friction fluctuations in a local time period, it is determined to be a warning level; when the overall deviation exceeds the allowable range or there are continuous local leakage peaks, it is determined to be unqualified.

[0039] After determining the sealing level, the contribution of structural correction parameters is further decomposed based on the deviation analysis results. By analyzing the influence weights of the microchannel formation probability coefficient and the sealing contact matching correction coefficient on the theoretical leakage rate, the source of deviation is determined. When the deviation rate meets the deviation threshold and the microchannel formation probability coefficient is lower than the preset probability threshold, it indicates that there is an abnormality in the material microstructure but the assembly matching degree is normal, and the cause of leakage is determined to be a defect in the microstructure of the raw material. When the deviation rate exceeds the deviation threshold and the sealing contact matching correction coefficient is lower than the preset matching threshold, it indicates that the sealing contact pressure distribution is abnormal, and the cause of leakage is determined to be a defect in the assembly process. When the deviation rate exceeds the deviation threshold and the microchannel formation probability coefficient is lower than the probability threshold and the sealing contact matching correction coefficient is lower than the matching threshold at the same time, it is determined to be the coupling effect of the raw material structural defect and the assembly process defect, thereby realizing the output of sealing performance test results and the accurate location of the cause of leakage.

[0040] In summary, the embodiments of this application have at least the following technical effects: First, multi-dimensional non-destructive testing is performed on the seamless steel pipe raw material of the pneumatic cylinder to obtain raw material fingerprint data. Next, a structural mapping relationship between the raw material and the pneumatic cylinder is established based on the raw material fingerprint data, yielding structural correction parameters for the pneumatic cylinder, including elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient. Then, the pneumatic cylinder undergoes alternating pressure testing, and dynamic sealing performance data is collected in real time, including instantaneous leakage, pressure drop, and fluctuations in kinetic friction. Further, temperature influence compensation and structural elasticity compensation are applied to the collected dynamic sealing performance data to obtain actual leakage pressure variation data. This actual leakage pressure variation data and the structural correction parameters are input into a pre-constructed sealing performance prediction model to calculate the theoretical leakage rate after material compensation. Finally, a deviation analysis is performed between the measured leakage rate and the theoretical leakage rate. Based on the deviation results, the sealing performance test results are output, and the cause of leakage is identified as either a structural defect in the raw material or a defect in the assembly process. This method solves the technical problem of insufficient accuracy in the sealing performance testing of pneumatic cylinders in existing technologies, achieving the technical effect of improving the accuracy of sealing performance testing.

[0041] Example 2, based on the same inventive concept as the method for testing the sealing performance of a pneumatic cylinder in the foregoing examples, such as... Figure 2 As shown, this application provides a sealing performance testing system for pneumatic cylinders, wherein the system includes: Non-destructive testing module 11: Performs multi-dimensional non-destructive testing on the seamless steel pipe raw material of the pneumatic cylinder to obtain raw material fingerprint data; Parameter establishment module 12: Establishes a structural mapping relationship between the raw material and the pneumatic cylinder based on the raw material fingerprint data to obtain structural correction parameters for the pneumatic cylinder, including elastic expansion correction coefficient, microchannel formation probability coefficient, and sealing contact matching correction coefficient; Performance testing module 13: Performs alternating pressure testing on the pneumatic cylinder and collects dynamic sealing performance data of the cylinder in real time, including instantaneous leakage, pressure drop, and motion friction fluctuation; Calculation module 14: Performs temperature influence compensation and structural elasticity compensation processing on the collected dynamic sealing performance data to obtain real leakage pressure change data, inputs the real leakage pressure change data and the structural correction parameters into a pre-constructed sealing performance prediction model, and calculates the theoretical leakage rate after material compensation; Analysis module 15: Performs deviation analysis between the measured leakage rate and the theoretical leakage rate, outputs sealing performance test results based on the deviation results, and locates the cause of leakage as raw material structural defects or assembly process defects.

[0042] Furthermore, the nondestructive testing module 11 is used to perform the following methods: Multidimensional non-destructive testing is performed on the seamless steel pipe raw material of the pneumatic cylinder, including ultrasonic testing, eddy current testing and surface profile spectrum analysis, to obtain raw material test data including elastic modulus deviation parameters, wall thickness uniformity parameters, internal surface roughness spectrum characteristic parameters and micro-defect density parameters; based on the raw material test data, the raw material fingerprint data is constructed.

[0043] Furthermore, the parameter establishment module 12 is used to perform the following method: Based on the structural mapping relationship between the pneumatic cylinder structure and the seamless steel pipe raw material, a structural mapping model is constructed. According to the relationship between the raw material fingerprint data and the positional distribution of the raw material, the structural mapping model of the fingerprint data is projected to construct the raw material-pneumatic cylinder structure mapping relationship. Based on the raw material-pneumatic cylinder structure mapping relationship, the physical property mapping analysis of the raw material of the pneumatic cylinder structure is performed to obtain the physical property distribution of the pneumatic cylinder structure. Based on the physical property distribution, corresponding compensation and correction are performed to obtain the structural correction parameters.

[0044] Furthermore, the parameter establishment module 12 is used to perform the following method: Based on the elastic modulus deviation parameter and wall thickness uniformity parameter in the raw material fingerprint data, a pressure radial expansion simulation analysis of the pneumatic cylinder operation is performed to determine the pressure change relationship of elastic expansion, and elastic expansion compensation correction is performed to obtain the elastic expansion correction coefficient. According to the influence relationship of the internal surface roughness spectrum characteristic parameter on the formation of micro-leakage channels, a micro-channel formation probability compensation analysis is performed to determine the micro-channel formation probability coefficient. According to the influence of micro-defect density parameter and internal hole size accuracy on the sealing contact pressure distribution, a sealing contact matching compensation correction is performed to obtain the sealing contact matching correction coefficient. The elastic expansion correction coefficient, micro-channel formation probability coefficient, and sealing contact matching correction coefficient are used as the structural correction parameters.

[0045] Furthermore, the performance testing module 13 is used to perform the following methods: Based on the working scenario of the pneumatic cylinder, the maximum and minimum pressure values ​​of the alternating working conditions are determined; an alternating working conditions test is applied to the pneumatic cylinder, including cyclically loading and unloading the pressure between the maximum and minimum pressure values ​​at a set frequency; during the execution of the alternating test, the instantaneous leakage, pressure change, and piston rod motion friction fluctuation are collected in real time to obtain the dynamic sealing performance data.

[0046] Furthermore, the calculation module 14 is used to perform the following method: Based on the cylinder material properties and structural parameters, the elastic expansion of the cylinder caused by pressure changes is analyzed, and the corresponding pressure changes are removed from the dynamic sealing performance data. Based on the dynamic pressure data and synchronously acquired temperature measurements, the impact of temperature changes on the pressure readings is calculated, and the pressure data is compensated. The dynamic sealing performance data after elastic expansion and temperature compensation processing is used as the actual leakage pressure change data.

[0047] Furthermore, the calculation module 14 is used to perform the following method: The actual leakage pressure change data and the structural correction parameters are used as input vectors and fed into the pre-built sealing performance prediction model. Combining structural characteristics and material parameters, the dynamic leakage pressure is mapped to the theoretical leakage rate, and the theoretical leakage rate after material compensation is output. The pre-built sealing performance prediction model calculates the theoretical leakage rate curve after considering material differences based on trained or pre-set physical laws.

[0048] Furthermore, the analysis module 15 is used to perform the following methods: Based on the actual leakage pressure change data and the cylinder cavity volume, the pressure change is converted into a measured leakage rate; the difference between the measured leakage rate and the theoretical leakage rate after material compensation is calculated to obtain the deviation result.

[0049] Furthermore, the analysis module 15 is used to perform the following methods: The deviation results are compared with deviation thresholds to determine the sealing performance level. A deviation within the allowable range without local anomalies is considered a qualified level; a deviation within the allowable range but with local microchannels or abnormal friction fluctuations is a warning level; and a deviation exceeding the allowable range or with local leakage spikes is a non-qualified level. Based on the deviation analysis results, and combining the contribution decomposition of the microchannel formation probability coefficient and the sealing contact matching correction coefficient in the structural correction parameters, the cause of leakage is located. Specifically, when the deviation rate meets the deviation threshold and the microchannel formation probability coefficient is less than the probability threshold, the leakage cause is determined to be a microstructural defect in the raw material; when the deviation rate exceeds the deviation threshold and the sealing contact matching correction coefficient is less than the matching threshold, the leakage cause is determined to be an assembly process defect; when the deviation rate exceeds the deviation threshold and simultaneously satisfies both the microchannel formation probability coefficient and the sealing contact matching correction coefficient being less than the matching threshold, the leakage is determined to be a coupling effect between raw material structural defects and assembly process defects.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for testing the sealing performance of a pneumatic cylinder, characterized in that, The method includes: Multidimensional non-destructive testing of seamless steel pipe raw materials based on pneumatic cylinder barrels was carried out to obtain raw material fingerprint data; A raw material-pneumatic cylinder structure mapping relationship is established based on raw material fingerprint data to obtain pneumatic cylinder structure correction parameters, including elastic expansion correction coefficient, microchannel formation probability coefficient and sealing contact matching correction coefficient. The pneumatic cylinder is subjected to alternating working pressure tests, and dynamic sealing performance data of the cylinder is collected in real time. The dynamic sealing performance data includes instantaneous leakage, pressure drop and fluctuation of motion friction. Temperature influence compensation and structural elasticity compensation are performed on the collected dynamic sealing performance data to obtain the actual leakage pressure change data. The actual leakage pressure change data and the structural correction parameters are input into the pre-constructed sealing performance prediction model to calculate the theoretical leakage rate after material compensation. The measured leakage rate is compared with the theoretical leakage rate. Based on the deviation results, the sealing performance test results are output, and the cause of leakage is located as a defect in the raw material structure or a defect in the assembly process.

2. The method for testing the sealing performance of a pneumatic cylinder according to claim 1, characterized in that, Obtain raw material fingerprint data, including: Multidimensional non-destructive testing was performed on the seamless steel tube raw material of the pneumatic cylinder, including ultrasonic testing, eddy current testing and surface profile spectrum analysis, to obtain raw material test data including elastic modulus deviation parameters, wall thickness uniformity parameters, internal surface roughness spectrum characteristic parameters and micro-defect density parameters. Based on the raw material testing data, the raw material fingerprint data is constructed.

3. The method for testing the sealing performance of a pneumatic cylinder according to claim 2, characterized in that, The structural correction parameters for the pneumatic cylinder were obtained, including: Based on the structural mapping relationship between the pneumatic cylinder structure and the seamless steel pipe raw material, a structural mapping model is constructed. Based on the relationship between the raw material fingerprint data and the location distribution of the raw materials, a structural mapping model of the fingerprint data is projected to construct the structural mapping relationship between the raw materials and the pneumatic cylinder. Based on the raw material-pneumatic cylinder structure mapping relationship, the physical property mapping analysis of the raw material of the pneumatic cylinder structure is performed to obtain the physical property distribution of the pneumatic cylinder structure. Based on the physical property distribution, corresponding compensation and correction are performed to obtain the structural correction parameters.

4. The method for testing the sealing performance of a pneumatic cylinder according to claim 3, characterized in that, Based on the physical property distribution, corresponding compensation and correction are performed to obtain the structural correction parameters, including: Based on the elastic modulus deviation parameter and wall thickness uniformity parameter in the raw material fingerprint data, pressure radial expansion simulation analysis of pneumatic cylinder operation is carried out to determine the pressure change relationship of elastic expansion, perform elastic expansion compensation correction, and obtain elastic expansion correction coefficient. Based on the influence of the characteristic parameters of the internal surface roughness spectrum on the formation of micro-leakage channels, a micro-channel formation probability compensation analysis is performed to determine the micro-channel formation probability coefficient. Based on the influence of micro-defect density parameters and inner hole size accuracy on the sealing contact pressure distribution, sealing contact matching compensation correction is performed to obtain sealing contact matching correction coefficient; The elastic expansion correction coefficient, the microchannel formation probability coefficient, and the sealing contact matching correction coefficient are used as the structural correction parameters.

5. The method for testing the sealing performance of a pneumatic cylinder according to claim 1, characterized in that, The pneumatic cylinder was subjected to alternating pressure tests under operating conditions, and dynamic sealing performance data of the cylinder was collected in real time, including: Based on the working scenario of the pneumatic cylinder, determine the maximum and minimum pressure values ​​under alternating working conditions; The pneumatic cylinder is subjected to an alternating working pressure test, which includes cyclically loading and unloading the pressure between the maximum and minimum pressure values ​​at a set frequency. During the alternating test, the instantaneous leakage, pressure change, and piston rod friction fluctuation are collected in real time to obtain the dynamic sealing performance data.

6. The method for testing the sealing performance of a pneumatic cylinder according to claim 5, characterized in that, Temperature effect compensation and structural elasticity compensation are applied to the collected dynamic sealing performance data to obtain the actual leakage pressure change data, including: Based on the cylinder material properties and structural parameters, analyze the cylinder elastic expansion caused by pressure changes, and remove the corresponding pressure changes from the dynamic sealing performance data. Based on dynamic pressure data and synchronously acquired temperature measurements, the impact of temperature changes on pressure readings is calculated, and the pressure data is compensated accordingly. The dynamic sealing performance data, after undergoing elastic expansion and temperature compensation treatment, is used as the actual leakage pressure change data.

7. The method for testing the sealing performance of a pneumatic cylinder according to claim 6, characterized in that, The actual leakage pressure variation data and the structural correction parameters are input into a pre-built sealing performance prediction model to calculate the theoretical leakage rate after material compensation, including: The actual leakage pressure change data and the structural correction parameters are used as input vectors and fed into the pre-built sealing performance prediction model. Combining structural characteristics and material parameters, the dynamic leakage pressure is mapped to the theoretical leakage rate, and the theoretical leakage rate after material compensation is output. The pre-built sealing performance prediction model calculates the theoretical leakage rate curve after considering material differences, based on trained or pre-set physical laws.

8. The method for testing the sealing performance of a pneumatic cylinder according to claim 6, characterized in that, Deviation analysis was performed between the measured leakage rate and the theoretical leakage rate, including: Based on the actual leakage pressure change data and the cylinder cavity volume, the pressure change is converted into a measured leakage rate. The deviation result is obtained by calculating the difference between the measured leakage rate and the theoretical leakage rate after material compensation.

9. The method for testing the sealing performance of a pneumatic cylinder according to claim 1, characterized in that, Based on the deviation results, the sealing performance test results are output, and the cause of leakage is located as either a defect in the raw material structure or a defect in the assembly process, including: The deviation results are compared with the deviation threshold to determine the sealing performance level. If the deviation is within the allowable range and there are no local abnormalities, it is a qualified level; if the deviation is within the allowable range but there are local microchannels or friction fluctuation abnormalities, it is a warning level; if the deviation exceeds the allowable range or there are local leakage peaks, it is an unqualified level. Based on the deviation analysis results, and combined with the contribution decomposition of the microchannel formation probability coefficient and the sealing contact matching correction coefficient in the structural correction parameters, the cause of leakage is located. When the deviation rate meets the deviation threshold and the microchannel formation probability coefficient is less than the probability threshold, the cause of leakage is determined to be a microstructural defect in the raw material. When the deviation rate exceeds the deviation threshold and the sealing contact matching correction coefficient is less than the matching threshold, the cause of leakage is determined to be an assembly process defect. When the deviation rate exceeds the deviation threshold, and at the same time the microchannel formation probability coefficient is less than the probability threshold and the sealing contact matching correction coefficient is less than the matching threshold, it is determined to be a coupling effect between raw material structural defects and assembly process defects.

10. A system for testing the sealing performance of a pneumatic cylinder, characterized in that, A method for testing the sealing performance of a pneumatic cylinder according to any one of claims 1-9, the system comprising: Non-destructive testing module: Performs multi-dimensional non-destructive testing on seamless steel pipe raw materials based on pneumatic cylinders to obtain raw material fingerprint data; Parameter establishment module: Based on the raw material fingerprint data, establish the raw material-pneumatic cylinder structure mapping relationship to obtain the structural correction parameters of the pneumatic cylinder. The structural correction parameters include elastic expansion correction coefficient, microchannel formation probability coefficient and sealing contact matching correction coefficient. Performance testing module: Performs alternating pressure tests on the pneumatic cylinder and collects dynamic sealing performance data of the cylinder in real time. The dynamic sealing performance data includes instantaneous leakage, pressure drop and fluctuation of motion friction. Calculation module: Performs temperature effect compensation and structural elasticity compensation on the collected dynamic sealing performance data to obtain the actual leakage pressure change data. Inputs the actual leakage pressure change data and the structural correction parameters into the pre-built sealing performance prediction model to calculate the theoretical leakage rate after material compensation. Analysis module: Performs deviation analysis between measured leakage rate and theoretical leakage rate, outputs sealing performance test results based on deviation results, and identifies the cause of leakage as defects in raw material structure or assembly process.

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