Pressure-displacement dual-sensing cooperative rear axle oil seal intelligent pressing system

Abstract

This invention relates to the field of oil seal press-fitting inspection technology, and particularly to a rear axle oil seal intelligent press-fitting system with pressure-displacement dual-sensor coordination. The system includes a press-fitting actuator, an oil seal pressure head, a press-fitting force sensor, a displacement sensor, and a control unit. The control unit comprises: a press-fitting reference establishment module, an inlet section resistance trajectory acquisition module, an interference section resistance trajectory acquisition module, a limit section resistance trajectory acquisition module, and a press-fitting result judgment module. These modules are connected via wired or wireless means. This invention improves the reliability of rear axle oil seal press-fitting quality judgment by synchronously acquiring press-fitting pressure and displacement values, identifying inlet events, interference establishment events, and limit contact events based on the pressure-displacement change process, and combining the event chain integrity, event sequence, displacement interval, pressure change direction, and limit section stability.

Description

Technical Field

[0001] This invention relates to the field of oil seal press-fitting and testing technology, specifically to a rear axle oil seal intelligent press-fitting system with pressure-displacement dual sensing collaboration. Background Technology

[0002] The rear axle oil seal is a crucial component in the rear axle assembly, used for sealing the lubricating medium and isolating external impurities. It typically requires press-fitting equipment to insert the oil seal into the oil seal mounting hole in the rear axle housing. The quality of the oil seal press-fit directly affects the sealing reliability and service life of the rear axle assembly. Insufficient press-fit depth, misalignment during press-fitting, or localized hardening during the process can easily lead to uneven stress on the oil seal lip, abnormal sealing surface contact, and consequently, leakage, premature wear, or subsequent assembly failure.

[0003] In existing rear axle oil seal press-fitting processes, methods such as post-press-fitting height detection, single-endpoint displacement control, or single-endpoint pressure judgment are commonly used to confirm whether the oil seal has been successfully press-fitted. These methods primarily focus on the final state after press-fitting and are insufficient to reflect the force changes and movement of the oil seal during its entry into the mounting hole, gradual pressing, and approach to the internal limiting structure of the mounting hole. Therefore, when the oil seal experiences issues such as skewed entry, partial jamming, springback unloading, or insufficient contact with the limiting structure during press-fitting, existing detection methods are prone to misjudgment.

[0004] For example, when an oil seal is pressed in at an angle, the outer edge may prematurely generate significant contact resistance with the inner wall of the mounting hole, causing the pressing pressure to reach the set value, but the oil seal as a whole is not in the correct posture. When the oil seal is not fully pressed in, local frictional resistance may also cause the pressing pressure to rise temporarily, leading the system to mistakenly believe that the pressing is in place. Furthermore, if there is slow sinking or rebound in the later stages of pressing, it is difficult to identify this in a timely manner based solely on the endpoint position or endpoint pressure. Therefore, the existing method cannot simultaneously ensure both proper pressing placement and correct pressing posture, easily resulting in unqualified oil seals entering subsequent assembly stages.

[0005] In addition, the press-fitting equipment is also affected by factors such as micro-vibration of the actuator, sensor fluctuations, short pauses and workpiece clamping errors during operation. The existing judgment method based on a single threshold has limited ability to distinguish the above interferences, and it is easy to misjudge normal fluctuations as abnormalities, or misjudge abnormal resistance as normal pressing results, which affects the consistency and reliability of the quality inspection of the rear axle oil seal press-fitting.

[0006] Therefore, how to accurately identify whether the pressing is in place, whether the pressing posture is abnormal, and whether it is stable after pressing during the pressing process of rear axle oil seal is an urgent technical problem to be solved in the field of automated pressing of rear axle oil seal. Summary of the Invention

[0007] To address the aforementioned issues, this invention provides a rear axle oil seal intelligent press-fitting system with pressure-displacement dual-sensor collaboration. By synchronously acquiring press-fitting pressure and displacement values, identifying entry events, interference fit events, and limit contact events based on the pressure-displacement change process, and combining the event chain integrity, event sequence, displacement interval, pressure change direction, and limit segment stability to output the press-fitting results, the reliability of rear axle oil seal press-fitting quality assessment is improved.

[0008] This invention adopts the following technical solution: a pressure-displacement dual-sensor coordinated intelligent press-fitting system for rear axle oil seals, comprising a press-fitting actuator, an oil seal pressure head, a press-fitting force sensor, a displacement sensor, and a control unit, characterized in that the control unit comprises:

[0009] The press fitting reference establishment module is used to establish press fitting coordinate axes, obtain pressure-displacement synchronous trajectory, and determine the entry event based on the pressure-displacement synchronous trajectory;

[0010] The inlet section resistance trajectory acquisition module is used to read the pressure growth direction and displacement propulsion direction after the inlet event, determine the interference establishment event, and use the trajectory between the inlet event and the interference establishment event as the inlet section resistance trajectory.

[0011] The interference segment resistance trajectory acquisition module is used to receive the interference establishment event, continue to read the unit displacement pressure increment in the pressure-displacement synchronous trajectory, determine the positive continuing pressing interval, and acquire the interference segment termination data point and the interference segment resistance trajectory.

[0012] The limit section resistance trajectory acquisition module is used to further identify limit contact events based on the interference section resistance trajectory, acquire the limit section resistance trajectory based on the limit contact events, and generate the limit section stability result based on the limit section pressure fluctuation amplitude and the limit section residual propulsion amount.

[0013] The pressing result judgment module is used to generate a pressing event chain based on the inlet event, interference fit event, and limit contact event, and output the pressing quality judgment result according to whether the pressing event chain meets the event integrity condition, event sequence condition, displacement interval condition, pressure change direction condition, and limit section stability condition.

[0014] As a further description of the above technical solution: the method for obtaining the pressure-displacement synchronous trajectory includes:

[0015] The pressure sensor and displacement sensor are triggered to perform synchronous sampling using the same control clock;

[0016] The press displacement value at the same sampling time and press pressure value Binding to form pressure-displacement synchronous data points All pressure-displacement synchronization data points are arranged in ascending order of sampling time to obtain the pressure-displacement synchronization trajectory C.

[0017] As a further description of the above technical solution: the method for determining the entry event includes:

[0018] During the non-contact operation period before the pressing begins, the pressing pressure value is read. This forms a baseline sequence of inlet pressures, and the average inlet pressure is calculated. and standard deviation of inlet pressure ;

[0019] The inlet trigger pressure is determined based on the pressure fluctuations before the inlet and the resolution of the pressurization force sensor. ;

[0020] The pressure values ​​were read point by point along the pressure-displacement synchronous trajectory C in the increasing direction of the sampling time. Find the sampling point that first satisfies the following formula: ; ;

[0021] in, This represents the pressing pressure value at the i-th sampling time. This represents the inlet trigger pressure; k = 1, 2, ..., K-1; where K represents the number of inlet continuous confirmation points; Indicates the first The pressing pressure value at each sampling time.

[0022] The minimum sampling point number that satisfies the above conditions is denoted as... and the corresponding sampling time Press-fit displacement value and press pressure value Confirmed as an entry event The entry event includes the entry event establishment time, the entry event establishment displacement, and the entry event establishment pressure.

[0023] As a further description of the above technical solution: the method for determining the over-extension event includes:

[0024] The data point corresponding to the entry event is taken as the first reserved sampling point. For any pressure-displacement synchronous data point after the entry event, it is determined whether it is a valid pressure sampling point based on the pressure displacement value.

[0025] Starting from the first valid pressurization sampling point after the entry event, read the pressurization pressure value corresponding to the two adjacent valid pressurization sampling points in sequence to determine whether the adjacent interval is a positive pressure increase interval, a pressure not effectively increase interval, or a reverse unloading interval.

[0026] Read the pressing displacement values ​​corresponding to two adjacent valid pressing sampling points in sequence to determine whether the adjacent interval is a positive displacement advance interval or a pressing head retraction interval;

[0027] When no less than M consecutive effective pressing sampling points correspond to adjacent intervals that are all positive displacement advance intervals, and no less than M-1 of them are positive pressure increase intervals, and no reverse unloading intervals and pressure head retraction intervals appear in the continuous interval, the continuous interval is determined as a continuous positive pressing interval.

[0028] When the first continuous positive pressing interval is identified, the last valid pressing sampling point in the continuous positive pressing interval is determined as the interference establishment event. The interference establishment event includes the interference establishment time, interference establishment displacement, and interference establishment pressure.

[0029] As a further description of the above technical solution: the method for determining the positive continuation pressing interval includes:

[0030] The data point corresponding to the interference establishment event is taken as the starting data point of the interference segment. The starting data point of the interference segment is taken as the first retained sampling point after interference. Subsequent pressure-displacement synchronous data points are read, and the effective pressing sampling point after interference is determined based on the pressing displacement value.

[0031] Read the effective pressing sampling points of two adjacent interference fits in sequence, and calculate the unit displacement pressure increment of the effective pressing sampling point after interference fit relative to the previous effective pressing sampling point after interference fit.

[0032] The preset interference increment range is used to continuously read the unit displacement pressure increment starting from the first effective pressing sampling point after the interference establishment event. When no less than N consecutive unit displacement pressure increments are all within the preset interference increment range, and the corresponding adjacent effective pressing sampling points after interference all maintain an increasing pressing displacement value and the pressing pressure value does not decrease beyond the preset unloading pressure threshold, this continuous interval is determined as the positive continuing pressing interval.

[0033] As a further description of the above technical solution: the method for obtaining the termination data point of the interference segment includes:

[0034] Continue reading the effective pressing sampling points after interference along the forward pressing interval; when the unit displacement pressure increment remains within the preset interference increment range, continue extending the forward pressing interval; when the unit displacement pressure increment is higher than the upper limit of the preset interference increment range for the first time for no less than 2 consecutive sampling intervals, and the cumulative pressing displacement increase from the sampling point that is higher than the upper limit of the preset interference increment range to the next two consecutive effective pressing sampling points after interference is less than the preset limit displacement increment, the last effective pressing sampling point before the corresponding position is determined as the interference segment termination data point.

[0035] As a further description of the above technical solution: the method for obtaining the interference section resistance trajectory includes:

[0036] In the pressure-displacement synchronous trajectory C, all pressure-displacement synchronous data points between the sampling point corresponding to the interference establishment event and the termination data point of the interference segment are extracted to form the interference segment resistance trajectory.

[0037] As a further description of the above technical solution: the method for identifying limit contact events includes:

[0038] Using the termination data point of the interference section resistance trajectory as the sampling point to be retained before the limit, continue to read subsequent pressure-displacement synchronous data points to determine the candidate point of pressure surge;

[0039] Starting from the candidate point of sudden pressure rise, continue to read the subsequent R consecutive pressure-displacement synchronous data points, and calculate the increase in press displacement and the decrease in press pressure value between two adjacent pressure-displacement synchronous data points in turn.

[0040] When the increase in displacement of a single press in R consecutive pressure-displacement synchronous data points is not greater than the preset limit displacement increment, and the decrease in pressure value of each press is not greater than the preset unloading pressure threshold, the candidate point for pressure surge is determined to simultaneously meet the conditions of pressure surge and displacement propulsion tending to stabilize.

[0041] The first candidate point for a pressure surge that simultaneously satisfies the conditions of a sudden pressure increase and a stable displacement advance is identified as a limit contact event. The limit contact event includes the limit contact time, the limit contact displacement, and the limit contact pressure.

[0042] As a further description of the above technical solution: the method for determining candidate points of pressure surge includes:

[0043] The effective sampling point for limit identification is determined based on the increase in press-fit displacement value;

[0044] Starting from the termination data point of the interference section resistance trajectory, the pressing pressure value and pressing displacement value corresponding to the two adjacent limit identification valid sampling points are read sequentially. When the unit displacement pressure increment of the subsequent limit identification valid sampling point relative to the previous limit identification valid sampling point is greater than the limit trigger increment threshold, the subsequent limit identification valid sampling point is determined as a pressure surge candidate point.

[0045] As a further description of the above technical solution: the method for generating the stability result of the limiting segment includes:

[0046] Read all pressing pressure values ​​in the resistance trajectory of the limiting section, calculate the difference between the maximum pressure value and the minimum pressure value of the limiting section, and use this difference as the pressure fluctuation amplitude of the limiting section.

[0047] Read the press-fit displacement values ​​corresponding to the start and end points of the resistance trajectory of the limiting section, and use the difference between the two as the residual propulsion amount of the limiting section;

[0048] When the pressure fluctuation amplitude of the limiting section is not greater than the preset limiting pressure fluctuation threshold, and the residual propulsion of the limiting section is not greater than the preset limiting residual displacement threshold, the pressure of the limiting section is determined to be stable.

[0049] When the pressure fluctuation amplitude of the limit section is greater than the preset limit pressure fluctuation threshold, or the residual propulsion of the limit section is greater than the preset limit residual displacement threshold, it is determined that the rear axle oil seal has not formed a stable limit contact.

[0050] As a further description of the above technical solution: the method for generating the press-fit event chain includes:

[0051] Read the entry event, interference set-up event, and limit contact event, and arrange them in ascending order of occurrence time to generate a press-fit event chain.

[0052] As a further description of the above technical solution: the method for outputting the pressing quality judgment result includes:

[0053] The pressing quality judgment results include pressing in place and pressing in the correct position, pressing in place but not in place, and pressing abnormality.

[0054] When the press-fitting event chain satisfies the event integrity condition, event sequence condition, displacement interval condition, pressure change direction condition, and limit section stability condition, the press-fitting result is output as complete and properly pressed.

[0055] When both the entry event and the interference establishment event are identified, but the limit contact event is not identified, the output result is "not in position".

[0056] When the entry event, interference establishment event, and limit contact event are all identified, but the condition for the limit segment to remain stable is not met, the result of not being in position is output.

[0057] When the entry event is not identified, the interference fit event is not identified, the event sequence condition is not met, the displacement interval condition is not met, or the pressure change direction condition is not met, the press fitting abnormal result will be output.

[0058] The beneficial effects of this invention are as follows:

[0059] This application addresses the misjudgment issues caused by relying solely on manual visual inspection, post-press height detection, and endpoint displacement or pressure assessment during the rear axle oil seal press-fitting process. It provides process-oriented identification of the press-fitting state of the oil seal after it enters the mounting hole. By simultaneously collecting press-fitting pressure and displacement values, identifying entry events, interference fit events, and limit contact events based on the pressure-displacement change process, and combining the event chain integrity, event sequence, displacement interval, pressure change direction, and the stability of the limit segment to output the press-fitting result, it avoids misjudging the press-fitting as qualified due to increased local frictional resistance, skewed hard mounting, or incomplete press-fitting, thus improving the accuracy of judging the rear axle oil seal press-fitting position. Attached Figure Description

[0060] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0061] Figure 1 A module connection diagram of a pressure-displacement dual-sensor coordinated intelligent press-fitting system for rear axle oil seals provided by the present invention;

[0062] Figure 2 The flowchart of the method for determining an over-interference establishment event provided by the present invention;

[0063] Figure 3 This is a flowchart of the method for identifying limit contact events provided by the present invention;

[0064] Figure 4 The flowchart for judging the pressing quality provided by the present invention;

[0065] Figure 5 A schematic diagram of the pressure-displacement synchronization trajectory provided for this invention. Detailed Implementation

[0066] To make the technical means, creative features, objectives, and effects of this invention readily understandable, the invention is further described below with reference to specific illustrations. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0067] Please see Figures 1-5 The present invention provides a technical solution: a pressure-displacement dual-sensor coordinated intelligent press-fitting system for rear axle oil seals, including a press-fitting actuator, an oil seal pressure head, a press-fitting force sensor, a displacement sensor, and a control unit.

[0068] The press-fitting actuator is used to drive the press head to press the rear axle oil seal into the rear axle oil seal mounting hole.

[0069] The press-fit force sensor is installed between the output end of the press-fit actuator and the oil seal pressure head, and is used to collect the press-fit pressure value of the oil seal pressure head acting on the rear axle oil seal. The unit of the press-fit pressure value should be Newton, and the symbol is N.

[0070] The displacement sensor is installed between the fixed frame and the moving pressure head assembly to collect the axial feed position of the oil seal pressure head along the axis of the rear axle oil seal mounting hole.

[0071] The control unit includes:

[0072] Press-fitting reference establishment module: Establishes a press-fitting coordinate axis, binds the zero point of the pressure head displacement and the zero point of the pressure to the reference of the mounting hole inlet face, synchronously collects press-fitting displacement values ​​and press-fitting pressure values, forms a pressure-displacement synchronous trajectory, and determines the inlet event based on the pressure-displacement synchronous trajectory; in some implementations, the implementation steps include:

[0073] Methods for constructing the pressure-displacement synchronous trajectory C include:

[0074] To establish a press-fit coordinate axis, specifically, the rear axle housing is fixed on the press-fit fixture, so that the axis of the rear axle oil seal mounting hole coincides with the axis of motion of the press head; the end face of the rear axle oil seal mounting hole is used as the reference for the inlet end face of the mounting hole, the center point of the reference for the inlet end face of the mounting hole is used as the origin of the press-fit coordinate axis, and the direction of motion of the press head toward the inside of the mounting hole is used as the positive direction of the press-fit displacement.

[0075] When the pressure head is not in contact with the oil seal and the press-fitting actuator is stationary, the original pressure value of the press-fitting force sensor is continuously collected to obtain the zero-point calibration sequence of the pressure and determine the zero-point value of the press-fitting force.

[0076] The method for calculating the zero point value of the pressing force is as follows: ;

[0077] ;

[0078] in, Indicates the zero-point value of the pressing force; This indicates the number of sampling points in the zero-point pressure calibration sequence; This represents the original pressure value of the pressure sensor corresponding to the qth sampling point.

[0079] In the subsequent pressing process, the pressing pressure value is obtained by subtracting the zero point value of the pressing force from the original pressure value output in real time by the pressing force sensor.

[0080] A displacement calibration block with an axial height equal to the distance from the front end face of the oil seal inlet hole to the pressure-bearing end face of the pressure head is placed at the reference position of the mounting hole inlet end face. The pressure head is then driven to approach the displacement calibration block at a low speed. When the pressure value is... Achieve calibrated contact pressure At that time, read the raw displacement value of the displacement sensor and record it as the zero displacement value. Calibrate the contact pressure. It is five times the resolution of the pressure sensor.

[0081] The resolution of the press-fit force sensor is the smallest change in press-fit pressure that the press-fit force sensor and its acquisition circuit can stably distinguish, and the unit is N. The resolution of the press-fit force sensor is determined according to the calibration certificate, product manual or minimum display scale value of the acquisition system of the press-fit force sensor.

[0082] In the subsequent pressing process, the pressing displacement value is obtained by subtracting the zero displacement value from the original displacement value output by the displacement sensor in real time.

[0083] The pressure sensor and displacement sensor are triggered by the same control clock to perform synchronous sampling, and the sampling period is denoted as . The i-th sampling time is denoted as .

[0084] in, ;in, Indicates the i-th sampling time; Indicates the start time of the press-fit data collection; Indicates the synchronous sampling period; i represents the sampling point number.

[0085] The press displacement value at the same sampling time and press pressure value Binding to form pressure-displacement synchronous data points All pressure-displacement synchronization data points are arranged in ascending order of sampling time to obtain the pressure-displacement synchronization trajectory C.

[0086] Specifically, ,in, This represents the i-th pressure-displacement synchronization data point; Indicates the sampling time; Indicates the press-fit displacement value; This indicates the pressure value used for press-fitting.

[0087] Methods for determining inlet events based on pressure-displacement synchronous trajectories include:

[0088] During the non-contact operation period before the pressing begins, the pressing pressure value is read. This forms a baseline sequence of inlet pressures, and the average inlet pressure is calculated. and standard deviation of inlet pressure .

[0089] The inlet trigger pressure is determined based on the pressure fluctuations before the inlet and the resolution of the pressurization force sensor. .

[0090] Methods for determining the inlet trigger pressure include:

[0091] ;

[0092] in, Indicates the inlet trigger pressure; This represents the average pressure before the inlet; ΔF represents the standard deviation of the pressure before inlet; ΔF represents the pressure resolution of the pressure sensor; max represents taking the larger of the two values ​​in parentheses.

[0093] By setting the above, the inlet trigger pressure is made higher than the pressure fluctuation limit of the non-contact operation range, thus avoiding misidentification of the pressure head idling vibration as oil seal inlet contact.

[0094] The pressure values ​​were read point by point along the pressure-displacement synchronous trajectory C in the increasing direction of the sampling time. Find the sampling point that first satisfies the following formula:

[0095] ; ;

[0096] in, This represents the pressing pressure value at the i-th sampling time. This represents the inlet trigger pressure; k = 1, 2, ..., K-1; where K represents the number of continuous inlet confirmation points, and the value of K is not less than 3; Indicates the first The pressing pressure value at each sampling time.

[0097] The minimum sampling point number that satisfies the above conditions is denoted as... and the corresponding sampling time Press-fit displacement value and press pressure value Confirmed as an entry event .

[0098] The entry event includes the entry event establishment time, the entry event establishment displacement, and the entry event establishment pressure. The entry event establishment displacement is the pressing displacement value corresponding to the minimum sampling point, and the entry event establishment pressure is the pressing pressure value corresponding to the minimum sampling point.

[0099] The entry event As the starting point of the subsequent inlet section resistance trajectory, the subsequent press-fit displacement minus the inlet event location yields the inlet press-fit displacement after the inlet.

[0100] In this embodiment, by setting a pressing force sensor between the output end of the pressing actuator and the oil seal pressing head, and setting a displacement sensor between the fixed frame and the moving pressing head assembly, the control unit can synchronously acquire the pressing pressure value and axial feed position during the oil seal pressing process, thereby forming a pressure-displacement synchronous trajectory. Compared with the method of judging only based on the end pressure or end displacement, the present invention can completely reflect the dynamic change process of the oil seal from inlet contact to interference pressing and then to limit contact, improving the completeness of the pressing process perception.

[0101] Furthermore, by binding the zero pressure point and zero displacement point to the reference of the mounting hole inlet face, and determining the inlet trigger pressure based on the average pressure before the inlet, the standard deviation of the pressure before the inlet, and the resolution of the pressurization force sensor, the influence of pressure head idle stroke vibration, pressure zero drift, and fluctuations in the non-contact operating range on inlet identification can be effectively eliminated, making the establishment position and establishment time of the inlet event more accurate, and providing a unified reference for subsequent inlet section, interference section, and limit section analysis.

[0102] Inlet segment resistance trajectory acquisition module: used to read the pressure growth direction and displacement propulsion direction after the inlet event, determine the interference fit establishment event, and use the trajectory between the inlet event and the interference fit establishment event as the inlet segment resistance trajectory; in some implementations, the implementation steps include:

[0103] Read the sampling point number corresponding to the entry event in the pressure-displacement synchronization trajectory C, and extract the pressure-displacement synchronization data points in ascending order of sampling time after the sampling point number to form the post-entry analysis sequence; each data point in the post-entry analysis sequence includes the sampling time, the pressure displacement value and the pressure value.

[0104] In the post-entry analysis sequence, pressure-displacement synchronous data points are read in ascending order of sampling time. The data point corresponding to the entry event is taken as the first retained sampling point. For any pressure-displacement synchronous data point after the entry event, if the increase in the press displacement value of the data point relative to the press displacement value of the previous retained sampling point is greater than twice the resolution of the displacement sensor, the data point is determined as a valid press sampling point and is taken as a new retained sampling point. If the increase in the press displacement value of the data point relative to the press displacement value of the previous retained sampling point is not greater than twice the resolution of the displacement sensor, the data point is taken as a repeated sampling point near the same press position and is not used to determine the direction of pressure increase and displacement propagation.

[0105] The resolution of the displacement sensor is determined based on the calibration certificate, product manual, or minimum display resolution of the control unit's acquisition channel.

[0106] By screening effective pressing sampling points as described above, duplicate sampling data caused by short pauses in the pressing head, servo micro-vibrations, and small fluctuations in the sensor can be eliminated, thus avoiding mistaking pressure jitter near the same pressing position as pressure increasing with displacement.

[0107] Starting from the first valid pressurization sampling point after the entry event, the pressurization pressure values ​​corresponding to two adjacent valid pressurization sampling points are read sequentially. When the increase in pressurization pressure value from the previous valid pressurization sampling point to the next valid pressurization sampling point is greater than three times the resolution of the pressurization force sensor, the adjacent interval is marked as a positive pressure increase interval. When the increase in pressurization pressure value is not greater than three times the resolution of the pressurization force sensor, the adjacent interval is marked as a pressure non-increase interval. When the decrease in pressurization pressure value of the next valid pressurization sampling point relative to the pressurization pressure value of the previous valid pressurization sampling point is greater than a preset unloading pressure threshold, the adjacent interval is marked as a reverse unloading interval.

[0108] The pressing displacement values ​​corresponding to two adjacent valid pressing sampling points are read sequentially. When the increase in pressing displacement value from the previous valid pressing sampling point to the next valid pressing sampling point is greater than twice the resolution of the displacement sensor, the adjacent interval is marked as the positive displacement advance interval. When the decrease in pressing displacement value of the next valid pressing sampling point relative to the pressing displacement value of the previous valid pressing sampling point is greater than the preset retraction displacement threshold, the adjacent interval is marked as the pressing head retraction interval. The positive displacement advance interval is used to confirm that the rear axle oil seal continues to enter the mounting hole along the mounting hole axis, and the pressing head retraction interval is used to eliminate misjudgments caused by pressing interruption or re-pressing after unloading.

[0109] It should be noted that the preset unloading pressure threshold is determined based on the resolution of the pressing force sensor and the pressure fluctuation at the inlet section of a qualified pressing sample, specifically the larger of five times the resolution of the pressing force sensor and twice the maximum pressure fluctuation at the inlet section of a qualified pressing sample; the preset retraction displacement threshold is three times the resolution of the displacement sensor. Through these settings, the noise from the pressing force sensor, brief pauses in the pressing head, and micro-vibrations in the displacement will not be misinterpreted as reverse unloading or pressing head retraction, while simultaneously enabling the identification of actual unloading, oil seal rebound, and re-pressing states occurring during the pressing process.

[0110] Starting from the first valid pressurization sampling point after the inlet event, a continuous positive pressurization interval is searched according to the arrangement order of the valid pressurization sampling points. When the adjacent intervals corresponding to at least M consecutive valid pressurization sampling points are all positive displacement propulsion intervals, and at least M-1 of these adjacent intervals are positive pressure growth intervals, and no reverse unloading intervals or pressure head retraction intervals appear in this continuous interval, the continuous interval is determined as a continuous positive pressurization interval. M is the number of interference fit confirmation points, and the value of M is not less than 4.

[0111] When the first continuous positive press interval is identified, the last valid press sampling point in the continuous positive press interval is determined as the interference establishment event.

[0112] The interference fit event includes the interference fit time, interference fit displacement, and interference fit pressure. The interference fit displacement is the press-fit displacement value corresponding to the effective press-fit sampling point, and the interference fit pressure is the press-fit pressure value corresponding to the effective press-fit sampling point. The interference fit event indicates that the outer periphery of the rear axle oil seal and the inner wall of the rear axle oil seal mounting hole transition from inlet-guided contact to stable interference contact, and the press-fit resistance begins to increase continuously with the press-fit displacement.

[0113] In the pressure-displacement synchronization trajectory C, all pressure-displacement synchronization data points between the sampling point corresponding to the entry event and the sampling point corresponding to the interference establishment event are extracted to form the entry segment resistance trajectory.

[0114] The inlet section resistance trajectory includes the inlet event establishment time, the interference establishment time, and the pressing displacement value and pressing pressure value corresponding to each sampling time between the two. It is used to characterize the process of the rear axle oil seal entering the mounting hole from the mounting hole inlet end face reference and completing the interference establishment before the introduction resistance changes.

[0115] Interference Segment Resistance Trajectory Acquisition Module: This module receives the interference establishment event, continues reading the unit displacement pressure increment in the pressure-displacement synchronous trajectory, determines the positive continuing compression interval, and acquires the interference segment termination data point and the interference segment resistance trajectory. In some implementations, the steps include:

[0116] The data point corresponding to the interference establishment event is taken as the starting data point of the interference segment; after the starting data point of the interference segment, the pressure-displacement synchronization data points are read in ascending order of sampling time.

[0117] Obtain the sequence of effective pressing sampling points after interference fit. Specifically, take the starting data point of the interference fit segment as the first retained sampling point after interference fit, and continue to read subsequent pressure-displacement synchronous data points. When the increase in pressing displacement value of the current pressure-displacement synchronous data point relative to the pressing displacement value of the previous retained sampling point after interference fit is greater than twice the resolution of the displacement sensor, the current pressure-displacement synchronous data point is determined as an effective pressing sampling point after interference fit and is used as a new retained sampling point after interference fit. When the increase is not greater than twice the resolution of the displacement sensor, the current pressure-displacement synchronous data point is used as a repeated sampling point near the same pressing fit position and is not included in the calculation of unit displacement pressure increment.

[0118] Read the effective pressing sampling points of two adjacent interference fits in sequence, and calculate the unit displacement pressure increment of the effective pressing sampling point after interference fit relative to the previous effective pressing sampling point after interference fit. .

[0119] Specifically, ;

[0120] in, This represents the unit displacement pressure increment corresponding to the effective press-fit sampling point after the i-th interference fit; This represents the pressing pressure value corresponding to the effective pressing sampling point after the i-th interference fit; This indicates the pressing pressure value corresponding to the effective pressing sampling point after the previous interference fit; This represents the pressing displacement value corresponding to the effective pressing sampling point after the i-th interference fit; This indicates the pressing displacement value corresponding to the effective pressing sampling point after the previous interference fit.

[0121] The unit displacement pressure increment Used to characterize the increase in axial press-fit resistance generated by the rear axle oil seal within a unit press-fit displacement.

[0122] The preset interference increment range starts from the first effective press-fit sampling point after the interference establishment event, and continuously reads the unit displacement pressure increment. When at least N consecutive unit displacement pressure increments are all within the preset interference increment range, and the corresponding adjacent effective pressing sampling points after interference all maintain an increasing pressing displacement value and the pressing pressure value does not decrease beyond the preset unloading pressure threshold, this continuous interval is determined as the positive continuing pressing interval. N is the number of positive pressing confirmation points, and the value of N is not less than 4. The method for setting the preset interference increment range includes: selecting qualified pressing samples of rear axle oil seals of the same specification, extracting the unit displacement pressure increment during their stable interference pressing stage, calculating the average interference increment and the interference increment fluctuation amplitude of the qualified pressing samples; subtracting twice the interference increment fluctuation amplitude from the average interference increment to obtain the lower limit of the interference increment, and adding twice the interference increment fluctuation amplitude to the average interference increment to obtain the upper limit of the interference increment, thereby forming the preset interference increment range. The preset interference increment range is used to characterize the resistance growth range when the rear axle oil seal is in a normal interference fit pressing state.

[0123] The interference increment fluctuation amplitude is the maximum absolute deviation of the unit displacement pressure increment during the stable interference pressing stage in the qualified press-fit sample from the mean interference increment.

[0124] The qualified press-fit samples are historical samples of the same specification rear axle oil seals that have passed the press-fit depth test, end face flatness test, and sealing appearance test after press-fitting. The number of samples shall not be less than 10.

[0125] Continue reading the effective pressing sampling points after interference along the forward pressing interval; when the unit displacement pressure increment remains within the preset interference increment range, continue extending the forward pressing interval; when the unit displacement pressure increment is higher than the upper limit of the preset interference increment range for the first time for no less than 2 consecutive sampling intervals, and the cumulative pressing displacement increase from the sampling point that is higher than the upper limit of the preset interference increment range to the next two consecutive effective pressing sampling points after interference is less than the preset limit displacement increment, the last effective pressing sampling point before the corresponding position is determined as the interference segment termination data point, and the data points thereafter are used as the starting identification data points for subsequent limit contact events.

[0126] In the pressure-displacement synchronous trajectory C, all pressure-displacement synchronous data points between the sampling point corresponding to the interference establishment event and the termination data point of the interference segment are extracted to form the interference segment resistance trajectory.

[0127] The interference section resistance trajectory includes the press-fit displacement value, press-fit pressure value, and unit displacement pressure increment corresponding to each sampling time within the interference section. It is used to characterize the continuous press-fit resistance change process when the outer periphery of the rear axle oil seal and the inner wall of the rear axle oil seal mounting hole are in a stable interference fit, and serves as the basic data for subsequent identification of limit contact events.

[0128] In this embodiment, after the inlet event, based on the screening of effective pressing sampling points, the determination of pressure growth direction, and the determination of displacement propagation direction, a continuous positive pressing interval is identified, and the end of the continuous positive pressing interval is determined as the interference fit establishment event. This method can distinguish between normal inlet resistance growth and abnormal states such as short pauses in the pressure head, servo micro-vibration, unloading rebound, and heavy pressing, avoiding misjudging pressure fluctuations near the same pressing position as the oil seal having entered a stable interference fit state.

[0129] Furthermore, after the interference fit event is established, the unit displacement pressure increment is calculated and compared with the preset interference increment range. This can identify the continuous resistance growth process when the rear axle oil seal is in a stable interference fit. When the unit displacement pressure increment is higher than the upper limit of the preset interference increment range for at least two consecutive sampling intervals and the subsequent displacement increase decreases, it can provide an accurate starting data point for limit contact identification, thereby improving the reliability of limit contact event identification.

[0130] The limit segment resistance trajectory acquisition module is used to further identify limit contact events based on the interference segment resistance trajectory, acquire the limit segment resistance trajectory based on the limit contact events, and generate a limit segment stability result based on the limit segment pressure fluctuation amplitude and the limit segment residual propulsion. In some embodiments, the implementation steps include:

[0131] Methods for identifying limit contact events include:

[0132] The termination data point of the interference section resistance trajectory is read in the pressure-displacement synchronous trajectory C, and the pressure-displacement synchronous data points after this termination data point are used as limit contact identification data; each data point in the limit contact identification data includes the sampling time. Press-fit displacement value and press pressure value .

[0133] The termination data point of the interference section resistance trajectory is used as the sampling point to be retained before the limit, and subsequent pressure-displacement synchronous data points are read.

[0134] When the increase in the press displacement value of the current pressure-displacement synchronization data point relative to the press displacement value of the previous pre-limit retention sampling point is greater than twice the resolution of the displacement sensor, the current pressure-displacement synchronization data point is determined as a valid sampling point for limit identification and is used as a new pre-limit retention sampling point; when the increase is not greater than twice the resolution of the displacement sensor, the current pressure-displacement synchronization data point is used as a repeated sampling point near the same press position, which is only used for subsequent short-range holding trajectory analysis and not for judging the starting point of pressure surge.

[0135] From the resistance trajectory of the interference segment C o Starting from the termination data point, the pressing pressure value and pressing displacement value corresponding to the two adjacent limit recognition valid sampling points are read sequentially; when the unit displacement pressure increment of the subsequent limit recognition valid sampling point relative to the previous limit recognition valid sampling point is greater than the limit trigger increment threshold, the subsequent limit recognition valid sampling point is determined as a pressure surge candidate point.

[0136] If the pressure drop exceeds the preset unloading pressure threshold, the limit contact recognition will stop and the current pressing process will be marked as an abnormal unloading process.

[0137] The method for setting the limit trigger increment threshold is as follows: read the unit displacement pressure increment in the interference section resistance trajectory and calculate the interference section resistance trajectory C. o The average value and the maximum normal fluctuation value of the unit displacement pressure increment within the interference section are used as the limit trigger increment threshold. The limit trigger increment threshold is used to distinguish between the normal increase in interference resistance and the sudden pressure rise after the oil seal end face contacts the limit step. The maximum normal fluctuation value is the maximum absolute deviation of each unit displacement pressure increment within the interference section relative to the average value.

[0138] Starting from the candidate point of sudden pressure increase, continue to read the subsequent R consecutive pressure-displacement synchronous data points, and calculate the increase in press displacement and the decrease in press pressure value between two adjacent pressure-displacement synchronous data points in turn; where the decrease in press pressure value is the press pressure value of the previous pressure-displacement synchronous data point minus the press pressure value of the next pressure-displacement synchronous data point.

[0139] When the increase in displacement during a single press-fitting operation in any of the R consecutive pressure-displacement synchronization data points is no greater than the preset limit displacement increment, and the decrease in pressure value during each press-fitting operation is no greater than the preset unloading pressure threshold, the candidate point for a pressure surge is determined to simultaneously satisfy the conditions of a pressure surge and a stable displacement advance. R is the number of limit confirmation points, and its value is not less than 3.

[0140] The first candidate point for pressure surge that simultaneously satisfies the conditions of pressure surge and displacement propulsion stabilization is identified as the limit contact event. The limit contact event includes the limit contact time, limit contact displacement, and limit contact pressure. The limit contact displacement and limit contact pressure are the press-fit displacement value and press-fit pressure value of the candidate point for pressure surge corresponding to the limit contact event, respectively.

[0141] Methods for obtaining the resistance trajectory of the limiting segment include:

[0142] After the limit contact event is determined, the control oil seal head is kept in its current position or the current pressing force is maintained for a preset holding time; during the preset holding time, the pressing displacement value and pressing pressure value are continuously collected synchronously to form the limit section resistance trajectory.

[0143] The preset holding time is determined according to the synchronous sampling cycle, so that the resistance trajectory of the limit section contains at least 5 consecutive pressure-displacement synchronous data points; when the equipment cycle time allows, the preset holding time is 0.5s.

[0144] The resistance trajectory of the limiting section includes the press-fit displacement value and press-fit pressure value corresponding to each sampling time after the limiting contact event, which is used to characterize the pressure holding state and residual propulsion state after the rear axle oil seal contacts the limiting step.

[0145] Methods for generating results that maintain stability of the limit segment include:

[0146] Read all pressing pressure values ​​in the resistance trajectory of the limiting section, calculate the difference between the maximum pressure value and the minimum pressure value of the limiting section, and use this difference as the pressure fluctuation amplitude of the limiting section.

[0147] Read the press-fit displacement values ​​corresponding to the start and end points of the resistance trajectory of the limiting section, and use the difference between the two as the residual propulsion amount of the limiting section.

[0148] When the pressure fluctuation amplitude of the limit section is not greater than the preset limit pressure fluctuation threshold, and the residual propulsion of the limit section is not greater than the preset limit residual displacement threshold, it is determined that the pressure of the limit section remains stable, and thus it is determined that the rear axle oil seal is installed in place.

[0149] When the pressure fluctuation amplitude of the limit section is greater than the preset limit pressure fluctuation threshold, or the residual propulsion of the limit section is greater than the preset limit residual displacement threshold, it is determined that the rear axle oil seal has not formed a stable limit contact, and thus the result of not being in place is output.

[0150] It should be noted that the preset limit displacement increment is three times the resolution of the displacement sensor, or twice the maximum single displacement increase of the limit section of a qualified press-fit sample, whichever is greater; the preset limit pressure fluctuation threshold is five times the resolution of the press-fit force sensor, or twice the maximum pressure fluctuation amplitude of the limit section of a qualified press-fit sample, whichever is greater; the preset limit residual displacement threshold is three times the resolution of the displacement sensor, or twice the maximum residual propulsion of the limit section of a qualified press-fit sample, whichever is greater. By setting these thresholds, normal sensor fluctuations and pressure head micro-vibrations will not be misjudged as incomplete positioning, and abnormal states such as the oil seal not yet contacting the limit step, insufficient limit contact, and continued slow sinking after press-fitting can be identified.

[0151] The pressing result determination module is used to generate a pressing event chain based on the inlet event, interference fit event, and limit contact event, and output the pressing quality determination result according to whether the pressing event chain meets the event integrity condition, event sequence condition, displacement interval condition, pressure change direction condition, and limit segment stability condition. In some implementations, the implementation steps include:

[0152] Methods for generating a press-fit event chain include:

[0153] The system reads the entry event, interference fit establishment event, and limit contact event, and simultaneously reads the resistance trajectory of the entry section, interference fit section, and limit contact section. The identified entry events, interference fit establishment events, and limit contact events are arranged in ascending order of their occurrence time to generate a press-fit event chain. This press-fit event chain characterizes the continuous press-fit process of the rear axle oil seal, from the contact mounting hole inlet, establishing the outer peripheral interference fit, to the limit step within the contact mounting hole.

[0154] Methods for determining whether a press-fit event chain meets the event integrity criteria include:

[0155] When the entry event, interference set-up event, and limit contact event are all identified, the press-fit event chain is determined to meet the event integrity condition; when any of the entry event, interference set-up event, and limit contact event is not identified, the press-fit event chain is marked as an incomplete event chain, and the press-fit stage corresponding to the missing event is recorded. The press-fit stage includes the entry section, the interference section, and the limit section.

[0156] Methods for determining whether a pressing event chain satisfies the event sequence condition include:

[0157] If the press-fit event chain meets the event integrity condition, read the entry event establishment time, interference establishment time, and limit contact time, and read the entry event displacement, interference establishment displacement, and limit contact displacement. If the entry event establishment time is earlier than the interference establishment time, the interference establishment time is earlier than the limit contact time, and the entry event displacement is less than the interference establishment displacement and the interference establishment displacement is less than the limit contact displacement, the press-fit event chain is determined to meet the event sequence condition. If the above time sequence or displacement sequence is not met, the press-fit event chain is marked as an abnormal sequence event chain, and it is determined that the press-fitting process of the rear axle oil seal has the risk of event reversal, press-fitting interruption, or false triggering.

[0158] Methods for determining whether a press-fitting event chain satisfies the displacement interval condition include:

[0159] When the press-fit event chain meets the event integrity condition, the inlet to interference displacement interval is determined based on the inlet event occurrence displacement and interference establishment displacement, and the interference to limit displacement interval is determined based on the interference establishment displacement and limit contact displacement. When the inlet to interference displacement interval is within the preset inlet transition displacement range and the interference to limit displacement interval is within the preset interference press-fit displacement range, the press-fit event chain is determined to meet the displacement interval condition. When the inlet to interference displacement interval is less than the lower limit of the preset inlet transition displacement range, it is determined that the rear axle oil seal generates hard resistance too early after entering the mounting hole.

[0160] When the interval between the inlet and the interference displacement is greater than the upper limit of the preset inlet transition displacement range, it is determined that the rear axle oil seal inlet is not sufficiently introduced or the interference is delayed; when the interval between the interference and the limit displacement is less than the lower limit of the preset interference press-in displacement range, it is determined that the rear axle oil seal has a risk of skew and hard top.

[0161] When the interval between the interference fit and the limit displacement is greater than the upper limit of the preset interference fit displacement range, it is determined that there is a risk that the rear axle oil seal may not contact the limit step according to the predetermined path.

[0162] The preset inlet transition displacement range and the preset interference press-in displacement range are determined based on the design press-in depth of the rear axle oil seal of the same specification and qualified press-fit samples. Specifically, the inlet to interference displacement interval and interference to limit displacement interval of qualified press-fit samples are statistically analyzed, and the corresponding mean value minus twice the standard deviation is taken as the lower limit, and the corresponding mean value plus twice the standard deviation is taken as the upper limit.

[0163] The methods for satisfying the pressure change direction condition include:

[0164] Read the effective pressure sampling points in the resistance trajectory of the inlet section. When there is no adjacent pressure drop exceeding the preset unloading pressure threshold in the inlet section, and the number of positive pressure growth intervals is not less than two-thirds of the total number of adjacent intervals in the inlet section, the pressure change direction of the inlet section is determined to be normal.

[0165] Read the pressing pressure value in the interference section resistance trajectory. When there is no adjacent pressure drop exceeding the preset unloading pressure threshold in the interference section resistance trajectory, it is determined that the direction of pressure change in the interference section is normal.

[0166] Read the pressing pressure value in the resistance trajectory of the limit section. When the pressure fluctuation amplitude of the limit section after the limit contact event is not greater than the preset limit pressure fluctuation threshold, it is determined that the pressure change direction of the limit section is normal.

[0167] When the inlet section, interference section, and limit section all meet the normal pressure change direction, the pressure change direction condition is determined to be met.

[0168] If the normal pressure change direction is not met at any stage, the condition for the pressure change direction is determined to be unmet, and the corresponding abnormal stage is recorded.

[0169] Methods for determining whether the limit segment remains stable include:

[0170] The stability determination result of the resistance trajectory of the limiting section is read. The stability determination result includes the pressure fluctuation amplitude of the limiting section and the residual propulsion of the limiting section. When the pressure fluctuation amplitude of the limiting section is not greater than the preset limiting pressure fluctuation threshold and the residual propulsion of the limiting section is not greater than the preset limiting residual displacement threshold, it is determined that the condition for the limiting section to remain stable is met.

[0171] When the pressure fluctuation amplitude of the limiting section exceeds the preset limiting pressure fluctuation threshold, or the residual advance amount of the limiting section exceeds the preset limiting residual displacement threshold, the limiting section is determined to be unstable. The stability of the limiting section indicates that the rear axle oil seal has formed stable contact with the limiting step within the mounting hole, and during the short-range holding process, there has been no further sinking due to the residual advance amount of the limiting section exceeding the preset limiting residual displacement threshold, and no unloading fluctuation due to the pressure fluctuation amplitude of the limiting section exceeding the preset limiting pressure fluctuation threshold.

[0172] Methods for outputting press-fit quality judgment results include:

[0173] The pressing quality judgment results include pressing in place and in the correct position, pressing in place but not in place, and pressing abnormality.

[0174] When the press-fitting event chain satisfies the event integrity condition, event sequence condition, displacement interval condition, pressure change direction condition, and limit segment stability condition, the output result shows that the press-fitting is in place and pressed correctly.

[0175] When both the entrance event and the interference establishment event are recognized and the limit contact event is not recognized, an out-of-position result is output; when the entrance event, the interference establishment event, and the limit contact event are all recognized but the condition of the limit segment remaining stable is not satisfied, an out-of-position result is output; when the entrance event is not recognized, the interference establishment event is not recognized, the event sequence condition is not satisfied, the displacement interval condition is not satisfied, or the pressure change direction condition is not satisfied, a press-fitting abnormality result is output.

[0176] In this embodiment, the pressure sudden increase candidate points are identified by using the limit trigger increment threshold in the limit segment, and the stability of the limit contact is judged by combining the displacement increase amount and the pressure decrease amount of the subsequent continuous sampling points, which can effectively distinguish the normal increase of the interference press-fitting resistance from the pressure sudden increase after the oil seal end face contacts the limit step. Thus, situations such as the oil seal not yet contacting the limit step, insufficient limit contact, continuous sinking after press-fitting, and abnormal unloading can be identified.

[0177] Furthermore, a press-fitting event chain is generated based on the entrance event, the interference establishment event, and the limit contact event, and the press-fitting quality judgment result is output by comprehensively considering the event integrity, event sequence, displacement interval, pressure change direction, and the stability of the limit segment. Thus, the present invention can not only judge whether the rear axle oil seal is press-fitted in place, but also judge whether the press-fitting process is straight, reducing the risk of misjudging skewed press-fitting, out-of-position press-fitting, and abnormal press-fitting as qualified, and improving the consistency, traceability, and automation level of the rear axle oil seal press-fitting quality detection.

[0178] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A pressure-displacement dual-sensor coordinated intelligent press-fitting system for rear axle oil seals, comprising a press-fitting actuator, an oil seal pressure head, a press-fitting force sensor, a displacement sensor, and a control unit, characterized in that, The control unit includes: The press fitting reference establishment module is used to establish press fitting coordinate axes, obtain pressure-displacement synchronous trajectory, and determine the entry event based on the pressure-displacement synchronous trajectory; The inlet section resistance trajectory acquisition module is used to read the pressure growth direction and displacement propulsion direction after the inlet event, determine the interference establishment event, and use the trajectory between the inlet event and the interference establishment event as the inlet section resistance trajectory. The interference segment resistance trajectory acquisition module is used to receive the interference establishment event, continue to read the unit displacement pressure increment in the pressure-displacement synchronous trajectory, determine the positive continuing pressing interval, and acquire the interference segment termination data point and the interference segment resistance trajectory. The limit section resistance trajectory acquisition module is used to further identify limit contact events based on the interference section resistance trajectory, acquire the limit section resistance trajectory based on the limit contact events, and generate the limit section stability result based on the limit section pressure fluctuation amplitude and the limit section residual propulsion amount. The pressing result judgment module is used to generate a pressing event chain based on the inlet event, interference fit event, and limit contact event, and output the pressing quality judgment result according to whether the pressing event chain meets the event integrity condition, event sequence condition, displacement interval condition, pressure change direction condition, and limit section stability condition.

2. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 1, characterized in that, The method for obtaining the pressure-displacement synchronous trajectory includes: The pressure sensor and displacement sensor are triggered to perform synchronous sampling using the same control clock; The press displacement value at the same sampling time and press pressure value Binding to form pressure-displacement synchronous data points All pressure-displacement synchronization data points are arranged in ascending order of sampling time to obtain the pressure-displacement synchronization trajectory C.

3. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 2, characterized in that, The method for determining the entry event includes: During the non-contact operation period before the pressing begins, the pressing pressure value is read. This forms a baseline sequence of inlet pressures, and the average inlet pressure is calculated. and standard deviation of inlet pressure ; The inlet trigger pressure is determined based on the pressure fluctuations before the inlet and the resolution of the pressurization force sensor. ; The pressure values ​​were read point by point along the pressure-displacement synchronous trajectory C in the increasing direction of the sampling time. Find the sampling point that first satisfies the following formula: ; ; in, This represents the pressing pressure value at the i-th sampling time. The inlet trigger pressure is represented by k = 1, 2, ..., K-1; where K represents the number of inlet continuous confirmation points. Indicates the first The pressing pressure value at each sampling time; The minimum sampling point number that satisfies the above conditions is denoted as... and the corresponding sampling time Press-fit displacement value and press pressure value Confirmed as an entry event The entry event includes the entry event establishment time, the entry event establishment displacement, and the entry event establishment pressure.

4. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 1, characterized in that, The method for determining the over-excess establishment event includes: The data point corresponding to the entry event is taken as the first reserved sampling point. For any pressure-displacement synchronous data point after the entry event, it is determined whether it is a valid pressure sampling point based on the pressure displacement value. Starting from the first valid pressurization sampling point after the entry event, read the pressurization pressure value corresponding to the two adjacent valid pressurization sampling points in sequence to determine whether the adjacent interval is a positive pressure increase interval, a pressure not effectively increase interval, or a reverse unloading interval. Read the pressing displacement values ​​corresponding to two adjacent valid pressing sampling points in sequence to determine whether the adjacent interval is a positive displacement advance interval or a pressing head retraction interval; When no less than M consecutive effective pressing sampling points correspond to adjacent intervals that are all positive displacement advance intervals, and no less than M-1 of them are positive pressure increase intervals, and no reverse unloading intervals and pressure head retraction intervals appear in the continuous interval, the continuous interval is determined as a continuous positive pressing interval. When the first continuous positive pressing interval is identified, the last valid pressing sampling point in the continuous positive pressing interval is determined as the interference establishment event. The interference establishment event includes the interference establishment time, interference establishment displacement, and interference establishment pressure.

5. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 4, characterized in that, The method for determining the positive continuation of the push-in interval includes: The data point corresponding to the interference establishment event is taken as the starting data point of the interference segment. The starting data point of the interference segment is taken as the first retained sampling point after interference. Subsequent pressure-displacement synchronous data points are read, and the effective pressing sampling point after interference is determined based on the pressing displacement value. Read the effective pressing sampling points of two adjacent interference fits in sequence, and calculate the unit displacement pressure increment of the effective pressing sampling point after interference fit relative to the previous effective pressing sampling point after interference fit. The preset interference increment range is used to continuously read the unit displacement pressure increment starting from the first effective pressing sampling point after the interference establishment event. When no less than N consecutive unit displacement pressure increments are all within the preset interference increment range, and the corresponding adjacent effective pressing sampling points after interference all maintain an increasing pressing displacement value and the pressing pressure value does not decrease beyond the preset unloading pressure threshold, this continuous interval is determined as the positive continuing pressing interval.

6. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 5, characterized in that, The method for obtaining the termination data point of the interference segment includes: Continue reading the effective pressing sampling points after interference along the forward pressing interval; when the unit displacement pressure increment remains within the preset interference increment range, continue extending the forward pressing interval; when the unit displacement pressure increment is higher than the upper limit of the preset interference increment range for the first time for no less than 2 consecutive sampling intervals, and the cumulative pressing displacement increase from the sampling point that is higher than the upper limit of the preset interference increment range to the next two consecutive effective pressing sampling points after interference is less than the preset limit displacement increment, the last effective pressing sampling point before the corresponding position is determined as the interference segment termination data point.

7. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 6, characterized in that, The method for obtaining the interference segment resistance trajectory includes: In the pressure-displacement synchronous trajectory C, all pressure-displacement synchronous data points between the sampling point corresponding to the interference establishment event and the termination data point of the interference segment are extracted to form the interference segment resistance trajectory.

8. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 7, characterized in that, The method for identifying limit contact events includes: Using the termination data point of the interference section resistance trajectory as the sampling point to be retained before the limit, continue to read subsequent pressure-displacement synchronous data points to determine the candidate point of pressure surge; Starting from the candidate point of sudden pressure rise, continue to read the subsequent R consecutive pressure-displacement synchronous data points, and calculate the increase in press displacement and the decrease in press pressure value between two adjacent pressure-displacement synchronous data points in turn. When the increase in displacement of a single press in R consecutive pressure-displacement synchronous data points is not greater than the preset limit displacement increment, and the decrease in pressure value of each press is not greater than the preset unloading pressure threshold, the candidate point for pressure surge is determined to simultaneously meet the conditions of pressure surge and displacement propulsion tending to stabilize. The first candidate point for a pressure surge that simultaneously satisfies the conditions of a sudden pressure increase and a stable displacement advance is identified as a limit contact event. The limit contact event includes the limit contact time, the limit contact displacement, and the limit contact pressure.

9. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 8, characterized in that, The method for determining candidate points of pressure surge includes: The effective sampling point for limit identification is determined based on the increase in press-fit displacement value; Starting from the termination data point of the interference section resistance trajectory, the pressing pressure value and pressing displacement value corresponding to the two adjacent limit identification valid sampling points are read sequentially. When the unit displacement pressure increment of the subsequent limit identification valid sampling point relative to the previous limit identification valid sampling point is greater than the limit trigger increment threshold, the subsequent limit identification valid sampling point is determined as a pressure surge candidate point.

10. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 1, characterized in that, The method for generating the stability result of the limiting segment includes: Read all pressing pressure values ​​in the resistance trajectory of the limiting section, calculate the difference between the maximum pressure value and the minimum pressure value of the limiting section, and use this difference as the pressure fluctuation amplitude of the limiting section. Read the press-fit displacement values ​​corresponding to the start and end points of the resistance trajectory of the limiting section, and use the difference between the two as the residual propulsion amount of the limiting section; When the pressure fluctuation amplitude of the limiting section is not greater than the preset limiting pressure fluctuation threshold, and the residual propulsion of the limiting section is not greater than the preset limiting residual displacement threshold, the pressure of the limiting section is determined to be stable. When the pressure fluctuation amplitude of the limit section is greater than the preset limit pressure fluctuation threshold, or the residual propulsion of the limit section is greater than the preset limit residual displacement threshold, it is determined that the rear axle oil seal has not formed a stable limit contact.

11. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 1, characterized in that, The method for generating the press-fit event chain includes: Read the entry event, interference set-up event, and limit contact event, and arrange them in ascending order of occurrence time to generate a press-fit event chain.

12. The intelligent press-fitting system for rear axle oil seals with pressure-displacement dual-sensor coordination according to claim 1, characterized in that, Methods for outputting press-fit quality judgment results include: The pressing quality judgment results include pressing in place and pressing in the correct position, pressing in place but not in place, and pressing abnormality. When the press-fitting event chain satisfies the event integrity condition, event sequence condition, displacement interval condition, pressure change direction condition, and limit section stability condition, the press-fitting result is output as complete and properly pressed. When both the entry event and the interference establishment event are identified, but the limit contact event is not identified, the output result is "not in position". When the entry event, interference establishment event, and limit contact event are all identified, but the condition for the limit segment to remain stable is not met, the result of not being in position is output. When the entry event is not identified, the interference fit event is not identified, the event sequence condition is not met, the displacement interval condition is not met, or the pressure change direction condition is not met, the press fitting abnormal result will be output.

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