Manufacturing method for main valve piston of electromagnetic valve of shock absorber

Abstract

The invention relates to the technical field of shock absorbers, and discloses a shock absorber electromagnetic valve main valve piston manufacturing method which comprises the steps that set clamping force is read, and a pre-deformed grinding wheel initial feeding path track is generated based on a deformation amplitude function; a grinding health index is constructed in the grinding process, and cutting parameters are adjusted according to the grinding health index to prevent burn; a thermal-mechanical coupling model is built based on accumulated heat in the grinding process, the radial thermal expansion value of the main valve piston is calculated, and the initial feeding path track of the grinding wheel is corrected in real time; and the main valve piston is machined based on the corrected grinding wheel feeding path track, size and magnetism double judgment is carried out on the machined main valve piston, and magnetic repair is carried out on the main valve piston with the qualified size but the unqualified magnetism. By introducing a reverse compensation and thermal coupling mechanism and repairing hidden damage of residual stress to the magnetic conductivity, the sealing performance of the main valve piston is improved, and the electromagnetic response speed of the main valve piston is increased.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of shock absorbers, in particular to a manufacturing method of a main valve piston of a solenoid valve of a shock absorber. BACKGROUND

[0002] As an important component of the automobile suspension system, the performance of the shock absorber directly affects the ride comfort and handling stability of the vehicle. In a high-performance continuous damping control (CDC) shock absorber, the main valve piston of the solenoid valve is a core movement and electromagnetic response component. The piston is usually made of soft magnetic material such as DT4C electrical pure iron, and is designed as a thin-walled structure to reduce the movement inertia. The geometric accuracy (such as roundness) of the main valve piston directly determines the sealing performance and damping characteristics of the main valve piston and the valve body, and the electromagnetic performance (magnetic permeability) of the main valve piston determines the response speed of the shock absorber to road conditions.

[0003] At present, the outer diameter machining of such a thin-walled piston depends on a high-precision numerical control cylindrical grinder, but it often ignores the elastic deformation of the thin-walled piston when clamped and the high heat effect in the grinding process, and does not consider that the mechanical friction and thermal action in the grinding process will introduce residual stress on the surface of the piston, resulting in large accuracy error of the actual machined workpiece and slow electromagnetic response. Specifically: In terms of physical clamping, since the piston wall is thin and weak in rigidity, when the clamp applies clamping force, the piston will undergo non-uniform elastic deformation; although the grinding process reaches a true circle in the clamped state, once the clamp is loosened, the internal stress of the workpiece is released, and the piston will rebound back to a non-circular shape, resulting in the roundness of the final product exceeding the error range. In terms of thermal deformation, the instantaneous high temperature generated in the grinding process is easy to cause the workpiece to expand due to heat, and if the grinding is carried out according to the expanded size, after the workpiece cools and shrinks, the actual size will be smaller than the target size, thereby causing an overcut error; this size error will directly cause the gap between the main valve piston and the valve body to increase, reducing the sealing performance of the main valve piston, and further causing oil leakage or insufficient damping force of the shock absorber. In addition, the residual stress generated in the grinding process will have an implicit damage to the magnetic permeability of the surface of the main valve piston, resulting in that the machined main valve piston is qualified in size, but after being installed in the shock absorber, the electromagnetic response is slow and the damping adjustment is delayed. Therefore, there is an urgent need for a manufacturing method of a main valve piston of a solenoid valve of a shock absorber to solve the above problems. SUMMARY

[0004] In view of the problems in the related art, the application provides a manufacturing method of a main valve piston of a solenoid valve of a shock absorber to overcome the technical problems existing in the prior art.

[0005] To solve the technical problems, the application is implemented by the following technical scheme: In a first aspect, embodiments of the present invention provide a method for manufacturing the main valve piston of a shock absorber solenoid valve, specifically including: reading a set clamping force, generating a pre-deformed initial feed path trajectory of the grinding wheel based on a deformation amplitude function related to the clamping force; acquiring acoustic emission signals and spindle power in real time during the grinding process, constructing a grinding health index, and adjusting cutting parameters according to the grinding health index to prevent burns; constructing a thermo-mechanical coupling model based on the accumulated heat during the grinding process, calculating the radial thermal expansion value of the main valve piston, and correcting the initial feed path trajectory of the grinding wheel in real time to obtain a corrected feed path trajectory of the grinding wheel; machining the main valve piston based on the corrected feed path trajectory of the grinding wheel, and performing dual judgment on the dimensions and magnetism of the machined main valve piston, and performing magnetic repair on the main valve piston whose dimensions are qualified but whose magnetism is unqualified.

[0006] In a preferred embodiment of the method for manufacturing the main valve piston of the shock absorber solenoid valve according to the present invention, the specific formula for generating the initial feed path trajectory of the pre-deformed grinding wheel is as follows: In the formula, Inscribed angle The radius of the grinding wheel command at that location, The target design radius for the piston. For harmonic orders, To be compatible with clamping force The relevant deformation amplitude function, It is the deformed phase angle.

[0007] In a preferred embodiment of the manufacturing method for the main valve piston of the shock absorber solenoid valve according to the present invention, the deformation amplitude function is calibrated using an exponential saturation model, specifically expressed as follows: ; In the formula, Indicates the first First harmonic distortion amplitude, Indicates the first The limit of saturated deformation, The deformation sensitivity coefficient, This is the set value for the clamping force.

[0008] In a preferred embodiment of the manufacturing method for the main valve piston of the shock absorber solenoid valve according to the present invention, the formula for calculating the grinding health index is as follows: In the formula, For a moment Grinding health index For acoustic emission signals at time The power spectral density, For a moment spindle power, These are weighting coefficients. The normalization constant is and The frequency bands of interest for acoustic emission.

[0009] As a preferred embodiment of the manufacturing method of the main valve piston of the shock absorber solenoid valve according to the present invention, adjusting the cutting parameters according to the grinding health index to prevent burns specifically includes: setting a burn threshold. When the grinding health index When the system determines there is no risk of burns, it maintains the current processing parameters; when the grinding health index... When the system determines there is a risk of burns, it triggers an intervention mechanism: the intervention mechanism includes: the control system adjusting the radial feed speed. The pressure is lowered to reduce heat flux input, and the high-pressure cooling pump is simultaneously controlled to increase the coolant pressure for enhanced flushing, in order to remove blockages from the grinding wheel surface.

[0010] In a preferred embodiment of the manufacturing method of the main valve piston of the shock absorber solenoid valve according to the present invention, the formula for calculating the radial thermal expansion value of the main valve piston is as follows: ; In the formula, For a moment The radial thermal expansion of the main valve piston. is the coefficient of linear expansion of the material. The target design radius for the piston. For a moment The surface temperature rise of the main valve piston.

[0011] In a preferred embodiment of the method for manufacturing the main valve piston of the shock absorber solenoid valve according to the present invention, the specific formula for the modified grinding wheel feed path trajectory is as follows: ; In the formula, This is the corrected grinding wheel feed path trajectory. This is the thermal compensation gain coefficient.

[0012] In a preferred embodiment of the method for manufacturing the main valve piston of the shock absorber solenoid valve according to the present invention, the main valve piston is subjected to dual determination of dimensions and magnetism, specifically including: The actual outer diameter of the workpiece is measured using a laser diameter gauge. Set the allowable deviation of the dimensions And obtain the target outer diameter of the main valve piston determined during the design phase. ;like The main valve piston is deemed unusable; if , it is determined that grinding needs to continue dimensions; if , it is determined that the dimensions of the main valve piston are qualified; The Barkhausen noise characteristic amplitude is measured by using a Barkhausen noise probe , and a magnetic threshold is set ; if , it is determined that the main valve piston is qualified and the grinding process is ended; if , it is determined that the magnetism is unqualified and the magnetic repair mechanism is triggered.

[0013] As a preferred solution of the manufacturing method of the main valve piston of the shock absorber solenoid valve described in the present invention, wherein, the magnetic repair mechanism specifically includes: calculating the thickness of the stress layer to be removed , where is the stress layer depth coefficient; calculating the expected size of the workpiece after repair , if , it is determined that the main valve piston is scrapped and no longer repaired, otherwise, the magnetic repair of the main valve piston is performed by means of light grinding and polishing.

[0014] In a second aspect, an embodiment of the present invention provides a manufacturing system for a main valve piston of a shock absorber solenoid valve, specifically including: an initial reverse machining modeling module, configured to calculate an elastic deformation field caused by a set clamping force according to the set clamping force, and generate an initial feed path trajectory of a pre-deformed grinding wheel accordingly; a grinding process health monitoring module, configured to collect acoustic emission signals and spindle power in real time during the grinding process, construct a grinding health index, and adjust cutting parameters according to the grinding health index to prevent burning; a thermal-mechanical coupling compensation module, configured to construct a thermal-mechanical coupling model based on the cumulative heat during the grinding process, calculate the radial thermal expansion value of the main valve piston, and real-time correct the initial feed path trajectory of the grinding wheel to obtain a corrected feed path trajectory of the grinding wheel; a dual determination and repair module, configured to process the main valve piston based on the corrected feed path trajectory of the grinding wheel, and perform dual determination of dimensions and magnetism on the processed main valve piston, and perform magnetic repair on the main valve piston with qualified dimensions but unqualified magnetism.

[0015] The present invention has the following beneficial effects: 1. Aiming at the problem that the thin-walled piston generates non-circular elastic deformation under the action of fixtures such as three-jaw expansion chucks, the present invention solves the problem that the workpiece rebounds beyond the tolerance after being released by establishing an initial reverse machining model, introducing a non-circular profile complementary to the shape of the force-induced deformation to generate the initial feed path trajectory of the grinding wheel, and offsetting the elastic springback after releasing the fixture through the preset geometric deviation, so that the thin-walled workpiece can automatically return to a high-precision round shape in the unclamped state.

[0016] 2. This invention constructs a thermo-coupling model, calculating accumulated heat and radial thermal expansion based on spindle power integration, and corrects the grinding wheel feed path trajectory in real time. This mechanism counteracts the radial expansion effect caused by grinding heat, preventing over-cutting of the workpiece due to thermal expansion, and ensuring that the main valve piston maintains high-precision outer diameter dimensions after cooling to room temperature, thereby guaranteeing its sealing performance in the damper valve body. Simultaneously, this invention utilizes acoustic emission and power signals to construct a grinding health index, automatically reducing the feed rate and increasing the coolant pressure when a burn risk is detected, preventing workpiece surface burns caused by high heat flux.

[0017] 3. This invention introduces Barkhausen noise detection technology to quantitatively assess the decrease in magnetic permeability caused by residual grinding stress. For workpieces with acceptable dimensions but unacceptable magnetic properties, the thickness of the stress layer to be removed is calculated in reverse, and surface grinding repair is initiated under the premise of pre-judged dimensional safety. This not only saves workpieces on the verge of being scrapped due to hidden damage, but also ensures that the finished main valve piston has excellent electromagnetic response characteristics, solving the problems of slow electromagnetic response and delayed damping adjustment in finished shock absorbers.

[0018] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, the drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 The present invention provides a flowchart of a method for manufacturing the main valve piston of a shock absorber solenoid valve.

[0021] Figure 2 This invention provides a flowchart of a method for manufacturing the main valve piston of a shock absorber solenoid valve, which involves dual determination of dimensions and magnetism.

[0022] Figure 3 This invention provides a schematic diagram of a manufacturing system for the main valve piston of a shock absorber solenoid valve. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0024] Current manufacturing methods for main valve pistons often overlook the elastic deformation of thin-walled pistons during clamping and the high heat generated during grinding. During machining, when the fixture clamps the piston, it undergoes elastic deformation. Although it is rounded during grinding, it springs back to a non-circular shape once the fixture is released, causing the roundness to exceed the tolerance. Furthermore, the grinding heat easily causes the workpiece to expand upon heating and contract upon cooling, further leading to dimensional errors and reducing the sealing performance of the main valve piston. In addition, the residual stress generated during grinding can cause latent damage to the magnetic conductivity of the main valve piston surface. This results in a main valve piston that meets dimensional standards but exhibits slow electromagnetic response and sluggish damping adjustment after being installed in a shock absorber.

[0025] To solve the above technical problems, such as Figure 1 As shown, Embodiment 1 of the present invention provides a method for manufacturing the main valve piston of a shock absorber solenoid valve. Specifically, Embodiment 1 takes the processing scenario of the main valve piston of a certain type of high-performance CDC shock absorber as an example: the piston is made of DT4C electrical pure iron, with a designed outer diameter of 32mm and a wall thickness of 1.5mm, belonging to a typical thin-walled, weakly rigid, magnetically conductive part. The processing equipment is a high-precision CNC cylindrical grinding machine equipped with an acoustic emission sensor, a power monitoring module, and a Barkhausen noise probe, and the grinding wheel head (C-axis and X-axis) of the CNC cylindrical grinding machine can perform high-frequency linkage interpolation.

[0026] In the specific implementation of the above embodiment 1, firstly, the system reads the set clamping force and generates the initial feed path trajectory of the pre-deformed grinding wheel based on the deformation amplitude function related to the clamping force. This method introduces a non-circular profile that is complementary to the shape of the force deformation by presetting a high-order harmonic inverse component, which counteracts the elastic rebound after the clamp is released, so that the thin-walled piston can recover to a high-precision circle in the unclamped state, which helps to avoid geometric errors caused by elastic rebound after the clamp is released. Secondly, the acoustic emission signal and spindle power are collected in real time during the grinding process to construct a grinding health index, and the cutting parameters are adjusted according to the grinding health index to prevent burns. This method calculates the grinding health index and judges the risk of burns. When the system detects the risk of burns, it helps to prevent irreversible grinding burns on the workpiece surface by reducing the heat flux input and flushing with coolant. Then, a thermo-mechanical coupling model is constructed based on the accumulated heat during the grinding process to calculate the radial thermal expansion value of the main valve piston. The initial feed path trajectory of the grinding wheel is then corrected in real time to obtain the corrected feed path trajectory. This method, by superimposing a compensation amount linked to temperature rise in real time into the machining command, counteracts the radial expansion effect caused by grinding heat, ensuring that the main valve piston maintains high dimensional accuracy after cooling to room temperature. This avoids overcutting errors caused by inaccurate dimensions due to thermal expansion, thus solving the problem of reduced piston sealing performance due to thermal expansion and contraction in existing technologies. Finally, the main valve piston is machined based on the corrected feed path trajectory. The machined main valve piston undergoes dual dimensional and magnetic determination. For main valve pistons with acceptable dimensions but unacceptable magnetic properties, magnetic repair is performed. This method quantifies the thickness of the stress layer that needs to be removed from the magnetic defect and predicts the feasibility of repair. While eliminating residual surface stress to restore magnetic conductivity, it avoids dimensional defects caused by blind repair and ensures that the final manufactured main valve piston has both excellent sealing performance and sensitive electromagnetic response speed. It effectively solves the problem of damping adjustment hysteresis caused by latent magnetic damage in the prior art.

[0027] Furthermore, to better illustrate the technical solution of Embodiment 1 of the present invention, a method for remote fault diagnosis of a compressor based on real-time monitoring data is described in detail, specifically including the following: S1. Establish the initial reverse machining model and generate the initial feed path trajectory of the pre-deformed grinding wheel.

[0028] This step quantifies the elastic deformation caused by the clamping force and compensates for this deformation in advance in the machining instructions, thereby avoiding geometric errors caused by elastic rebound after the clamp is released. Specifically, it includes the following sub-steps: S11. The DT4C piston blank is loaded into the CNC cylindrical grinding machine fixture. In this embodiment 1, the CNC cylindrical grinding machine fixture uses a three-jaw expansion clamp to tighten the piston from the inner hole outwards. At the same time, the system reads the currently set clamping force. Considering that thin-walled parts will undergo elastic deformation in the form of a triangular circle under the action of three-point clamping force, the system needs to predict its deformation mode.

[0029] S12. The system calculates the elastic deformation field caused by the clamping force and generates the initial feed path trajectory of the pre-deformed grinding wheel accordingly. The specific formula is expressed as follows: In the formula, Inscribed angle The grinding wheel's command radius at that location; The target design radius for the piston is 16.000 mm in this embodiment; For harmonic orders, this embodiment uses a three-pronged tire expansion as an example. Primarily take 3 and its multiples; It is related to clamping force The deformation amplitude function exhibits a nonlinear positive correlation; It is the deformation phase angle. This formula introduces the inverse component of higher-order harmonics to pre-set a non-circular profile that is complementary to the shape of the deformation under force in the machining command. The purpose is that after the fixture is released and the elastic deformation is restored, the part can automatically spring back into a perfect circle.

[0030] For example, to accurately characterize the nonlinear elastic behavior of DT4C material, the deformation amplitude function in Example 1 is... The preferred calibration method is the exponential saturation model, which is specifically expressed as follows: ; In the formula, Indicates the first First harmonic distortion amplitude; Let be the calibration constant, representing the first . The limit of saturated deformation; is a calibration constant, representing the deformation sensitivity coefficient; This is the set value for the clamping force.

[0031] Furthermore, the calibration steps using the exponential saturation model are as follows: First, take at least 5 identical blanks and, under controlled clamping force... After clamping and measuring the outer contour of the device before and after unclamping, the amplitude values ​​of each harmonic are obtained by fitting the triangular amplitude measurement points. Secondly, the measured amplitudes of each harmonic were... and The data is subjected to nonlinear fitting to determine... , Finally, the fitting results are stored in the controller parameter library for subsequent online generation. .

[0032] In this embodiment 1, the system adjusts the clamping force according to the currently set clamping force. Combined with the pre-calibrated deformation amplitude function The corresponding harmonic deformation amplitudes are calculated, and then the initial feed path trajectory of the grinding wheel with reverse compensation is generated. Specifically, for example: setting the clamping force. The system calculates the third harmonic deformation amplitude based on the pre-stored DT4C material stiffness model. phase Substituting the formula for the initial feed path trajectory of the grinding wheel, in The command radius at 0°, 120°, and 240° (jaw positions) is 16.000 - 0.0025 = 15.9975 mm, while the radius between the two jaws is 16.0025 mm. The above example demonstrates how pre-set geometric deviations can be used to offset the elastic rebound after clamping and releasing, allowing thin-walled workpieces to automatically recover to a high-precision circle when unclamped. This helps avoid geometric errors caused by elastic rebound after clamping and releasing.

[0033] S2. During the grinding process, acoustic emission (AE) and spindle power are monitored in real time, and a grinding health index is introduced to adjust cutting parameters to prevent burns. Specific sub-steps are as follows: S21. During the grinding process, the system synchronously acquires the AE signal and spindle power, and pre-filters the AE signal with bandpass to eliminate low-frequency noise. To achieve standardized evaluation across working conditions, a grinding health index is defined. : In the formula, For acoustic emission signals at time The power spectral density is measured by the sensor; For a moment Spindle power; These are weighting coefficients; The normalization constant achieved through calibration is used to compensate for dimensional differences, ensuring that the cutting performance under standard cutting conditions is... ; , In this embodiment, the frequency band of interest for AE is... , This formula characterizes the situation where, when the abrasive grains are sharp, the high-frequency component of the abrasive AE is strong and the spindle power is low. The value is relatively high; when abrasive particles become passivated or burn out, friction causes the spindle power to increase and the high-frequency energy of the abrasive AE to decrease. The value decreased significantly.

[0034] S22. Further, perform burn assessment: set a burn threshold. When grinding health index When the system determines there is no risk of burns, it maintains the current processing parameters and directly executes step S3 to calculate the radial thermal expansion; when When the system determines there is a risk of burns, it triggers an intervention mechanism: for example, the control system adjusts the radial feed speed. Reduce the current setting to 50% to decrease heat flux input, and simultaneously control the high-pressure cooling pump to increase the coolant pressure to 5MPa for enhanced flushing to remove blockages from the grinding wheel surface. If the above measures are taken, after 3 seconds... Still below If the grinding wheel is severely dulled, the system will automatically stop grinding and retract the grinding wheel, triggering a dressing program. Machining will resume only after the grinding wheel dressing is complete. If the above measures are taken, grinding will resume after 3 seconds. Greater than or equal to Then continue with step S3 to calculate the radial thermal expansion.

[0035] In this embodiment 1, the burn threshold and normalization constant The results were obtained through experimental calibration, and the specific steps are as follows: First, at least 100 test pieces were prepared and ground under known grinding wheel conditions (sharp / dull / burned), while the acoustic emission power spectral density was collected simultaneously. With spindle power Then, under the same time window conditions, the ratio of the acoustic emission energy integral to the power normalization ratio is calculated. and in sharp grinding wheel condition The statistical median is used as a normalization constant. This makes the grinding health index corresponding to normal grinding conditions... The distribution is concentrated around 1; based on this, the passivation and burn states are merged into the damage class, and the sharp state is treated as the non-damage class, for different candidate thresholds. Statistical discrimination was performed, receiver operating characteristic (ROC) curves were plotted, and the burn threshold was selected by maximizing the difference between sensitivity and specificity. This ensures the statistical separability of the three types of grinding wheel states, keeping the probability of misclassification within an acceptable range for engineering purposes.

[0036] In this embodiment 1, the weighting coefficients The settings follow the principle of balancing power suppression and acoustic emission sensitivity, and are obtained through a combination of experimental calibration and statistical optimization. Specifically, the method involves: after completing the normalization constant... With burn threshold After calibration, based on the test data of the same set of known grinding wheel conditions (sharp, dull, burned), several candidate grinding wheels were selected respectively. Values ​​(e.g., scanning in steps of 0.1 within the range of 1.0 to 2.0) for each candidate Calculate the corresponding health indicators The statistical distribution characteristics of the burns under different states were analyzed. Then, with the optimization objective of maximizing inter-class separation and minimizing intra-class dispersion, evaluation indices were constructed, such as maximizing the ratio of the mean difference to the joint standard deviation between the sharp and burn states. Based on this, ROC curve analysis was further used to select the index that maximizes the burn detection rate under a fixed false alarm rate constraint. The value is used as the optimal weighting coefficient. This is determined using the method described above. It can suppress the excessive influence of large fluctuations in spindle power on the criteria while maintaining the sensitivity of high-frequency acoustic emission characteristics to changes in micro-cutting conditions, thereby ensuring the grinding health index. It has a stable, repeatable, and physically consistent discrimination capability under different grinding conditions.

[0037] In this embodiment 1, when the grinding health index is detected... When a burn risk is detected, the system takes measures such as reducing the feed rate from 0.02 mm / s to 0.01 mm / s and simultaneously controlling the high-pressure cooling pump to increase the coolant pressure to 5 MPa for enhanced flushing. This method calculates the grinding health index and assesses the burn risk. When the system detects a burn risk, reducing the heat flux input and using coolant flushing helps prevent irreversible grinding burns on the workpiece surface.

[0038] S3. Considering that the instantaneous thermal expansion of the workpiece caused by grinding heat may lead to overcutting, the system constructs a thermo-mechanical coupling model and calculates the radial thermal expansion value based on accumulated heat to correct the feed rate in real time. The steps for constructing the thermo-mechanical coupling model are as follows: S31. Calculate the cumulative heat of the workpiece, the expression is: ; In the formula, For a moment The accumulated heat of the main valve piston; Main spindle power.

[0039] S32. Estimate the surface temperature rise of the workpiece; the expression is as follows: ; In the formula, For a moment The surface temperature rise of the main valve piston; Heat transfer efficiency is the ratio of the actual heat absorbed by the workpiece to the heat generated by the machine tool. For the equivalent mass involved in heating; The specific heat of the material.

[0040] S33. Calculate the radial thermal expansion, the expression of which is: ; In the formula, For a moment Radial thermal expansion of the main valve piston; The coefficient of linear expansion of the material; The target design radius for the piston.

[0041] In this embodiment 1, the equivalent mass involved in heating... With heat transfer efficiency The parameters were estimated through experimental calibration, as follows: First, typical material parameters of DT4C electrical pure iron, including density, were obtained from the material handbook or supplier datasheet. Specific heat capacity Coefficient of linear expansion and thermal conductivity Then, determine the effective time window for power integration. Due to the thermal diffusivity of the material Estimating near-surface heating depth A common approximation of semi-infinite volume solutions can be used. The equivalent heated volume is then considered as an annular thin layer. (in For radius, (where axial length is the heating element), calculate the equivalent mass involved in the heating process. After obtaining Subsequently, the heat transfer efficiency was calibrated through controlled experiments. Specifically, in the selected Measuring spindle power integral Temperature rise near the workpiece surface The heat transfer efficiency is obtained by measuring and calibrating the temperature difference using a surface thermocouple, based on the law of conservation of energy. To improve robustness, repeated experiments were conducted for different cutting parameters / grinding wheel conditions to determine the optimal parameters. The mean and confidence interval, and the obtained The mean value is used as the initial value for the thermo-coupling model.

[0042] S34. Radial thermal expansion value calculated above The feed path trajectory is corrected in real time, and its expression is: ; In the formula, This is the corrected grinding wheel feed path trajectory; This represents the initial feed path trajectory of the grinding wheel; This is the thermal compensation gain coefficient.

[0043] In this embodiment 1, the thermal compensation gain coefficient Following the principle of balancing sufficient thermal deformation compensation with control stability, the method combines controlled heating experiments with closed-loop error analysis. Specifically, firstly, while keeping grinding parameters and clamping conditions constant, a specimen with the same material and structure as the one being machined is selected. By changing the feed rate in stages, different levels of grinding heat input are artificially introduced, and the corresponding cumulative heat is calculated. Meanwhile, the actual radial dimension deviation is obtained through online diameter measurement. Then, assuming complete compensation, the theoretical radial thermal expansion is calculated. and with Construct compensated prediction residuals for the moderating variables Subsequently, different candidates Statistical analysis was performed on the residuals (e.g., values ​​were taken in stages within the range of 0.2 to 1.0), and the values ​​that made the residual mean closest to zero and the variance smallest were selected, while not causing high-frequency oscillations in the trajectory. As the optimal value; ultimately, this The thermal compensation gain coefficient is solidified to the value within the current process window. This was determined using the calibration method described above. It can effectively offset the dimensional drift caused by grinding heat while avoiding excessive correction due to the uncertainty of the thermal model, thereby ensuring the dimensional stability and control robustness of the dynamic grinding process.

[0044] In this embodiment 1, the system calculates the radial thermal expansion value in real time. With thermal compensation gain coefficient The initial feed path of the grinding wheel is dynamically corrected to compensate for dimensional drift caused by grinding heat. Specifically, for example, at a certain moment during the grinding process... The system estimates the temperature rise of the workpiece surface based on accumulated heat. =50℃. The coefficient of linear expansion of DT4C material is known. Target radius =16.000mm, the theoretical radial thermal expansion is calculated. The system calls the calibrated thermal compensation gain coefficient. The actual compensation amount was calculated as follows: At this point, if the original position was... If the value is 16.000mm, then the corrected grinding wheel feed path trajectory The adjustment is set to 16.00864mm (i.e., controlling the grinding wheel retraction). The above example, by real-time superimposing a compensation amount linked to temperature rise in the machining command, counteracts the radial expansion effect caused by grinding heat, ensuring that the main valve piston maintains high dimensional accuracy even after cooling to room temperature. This avoids overcutting errors caused by inaccurate dimensions of the workpiece due to thermal expansion and contraction after cooling, thus solving the problem of reduced piston sealing caused by thermal expansion and contraction in existing technologies.

[0045] S4. Based on the corrected grinding wheel feed path trajectory The main valve piston is machined, and the finished workpiece undergoes dual dimensional and magnetic verification. For example... Figure 2 As shown, the specific steps include: S41. Workpiece Dimension Determination: The actual outer diameter of the workpiece is measured using a laser diameter gauge. Set the allowable deviation of the dimensions And obtain the target outer diameter of the main valve piston determined during the design phase. ; like This indicates that the outer diameter of the workpiece is too small, and the workpiece is deemed scrap and removed from the scrap area. like This indicates that the dimensions are too large and further grinding is required. Dimensions are determined, and then electromagnetic performance is assessed. like If the workpiece dimensions are found to be acceptable, the electromagnetic performance assessment can proceed directly.

[0046] In this embodiment 1, the allowable deviation of dimensions The method, obtained through experimental calibration, is as follows: First, during the design phase, based on the fit relationship of the main valve assembly of the shock absorber, the minimum sealing requirements and maximum assembly clearance between the main valve piston and the valve body and guide sleeve are determined, thus obtaining the theoretically permissible outer diameter tolerance range. Second, during the process verification phase, at least 30 prototype pistons are selected and processed under different grinding thermal states and different compensation conditions. Their actual outer diameters after cooling to room temperature are recorded. Simultaneously, these pistons are installed into the actual shock absorber valve body for assembly and functional testing, focusing on evaluating for any leakage, jamming, or abnormal damping response. Then, using samples with completely normal function as the effective sample set, statistical analysis is performed on their outer diameter deviations. The lower confidence limit of the deviation distribution (e.g., 99% confidence level) is taken as the dimensional safety boundary, yielding the final permissible dimensional deviation used for online judgment. .

[0047] S42. Electromagnetic Performance Determination: The system controls a Barkhausen noise (MBN) probe to approach the workpiece surface and detect the characteristic amplitude of the Barkhausen noise of the workpiece. After root mean square processing, the amplitude is recorded as follows: .and Is related to the residual stress on the material surface Among them, the residual stress Often causes To decrease, thereby reducing the permeability, which can be reflected by the following formula: ; In the formula, Is the residual stress conversion coefficient, used to characterize the change in residual stress corresponding to the change in the amplitude of unit Barkhausen noise; Is the stress zero-offset correction term, used to compensate for the systematic offset introduced by the initial magnetic properties of the material, the probe installation conditions, and the magnetization circuit under zero residual stress or reference stress state.

[0048] Set the magnetic threshold ; If , Determine that the workpiece is qualified and end the processing; if , Determine that the magnetism is unqualified and trigger the magnetic repair mechanism.

[0049] In this Embodiment 1, the magnetic threshold Is obtained through experimental calibration. The specific method is as follows: First, under the clamping and detection conditions consistent with production, collect the Barkhausen noise (MBN) characteristic values of a large number of test pieces And the corresponding reference residual stress ; Then establish a regression mapping between And Based on a linear model, and back-calculate the corresponding magnetic threshold From the maximum allowable residual stress Designed. To balance the detection rate and false alarm rate,辅以 ROC curve analysis and select the threshold that maximizes the Youden index on this basis. Finally, add an appropriate safety margin in the production environment and verify through trial operation to complete the confirmation and regular recalibration of To ensure the reliability and repeatability of magnetic determination under different working conditions and time scales.

[0050] S43. Magnetic repair mechanism: The system calculates the thickness of the stress layer to be removed according to the MBN difference , And its expression is: ; In the formula, Is the stress layer depth coefficient.

[0051] In this Embodiment 1, the stress layer depth coefficient Is obtained through experimental calibration. The method is as follows: First, select the main valve piston test piece consistent with the formal processing conditions, and artificially introduce a certain degree of grinding residual stress under the conventional grinding parameters to make its Barkhausen noise characteristic amplitude Significantly lower than the magnetic threshold ; Subsequently, while keeping the clamping and detection conditions unchanged, a fine grinding and polishing method with an extremely low feed rate is adopted to remove materials step by step in multiple rounds, and a known thickness is removed in each round (such as 0.5 - 1), and the corresponding is measured immediately after each round; Then, the change trend with the increase of the cumulative removal thickness is statistically analyzed to determine when the first recovery or exceeds , and the cumulative removal thickness at this time is regarded as the depth of the equivalent residual stress layer of the specimen; On this basis, the above process is repeated for multiple specimens, and the proportional relationship in the average sense is taken to obtain the stress layer depth coefficient , where is the amplitude of the Barkhausen noise detected initially. The obtained by this calibration method can directly convert the deviation of the magnetic index into the thickness of the stress layer to be removed, which not only avoids the complex inversion of the residual stress distribution but also ensures that the repair machining amount has a clear physical basis and engineering operability.

[0052] S44. Calculate the size of the workpiece after expected repair and pre - judge whether the workpiece size is qualified. Specifically: Calculate the size of the workpiece after expected repair : ; If , the size of the workpiece after expected repair is too small, and the workpiece is directly judged as scrapped without further repair to save machining time; Otherwise, the size of the workpiece after expected repair is qualified, and the repair is started.

[0053] S45. The system starts a fine grinding and polishing method with an extremely low feed rate to remove the stress layer thickness of the workpiece, and detects again and re - judges the size and magnetism. If the size after repair , and , the workpiece is judged as qualified; If or , the workpiece is judged as scrapped, and the workpiece is removed to the scrap area. And if N consecutive pieces (such as 5 pieces) are all unqualified, an alarm signal is sent for maintenance personnel to repair.

[0054] In this Embodiment 1, the system performs double - judgment of size and magnetism, and inversely calculates the stress layer thickness when the magnetism is unqualified, and decides whether to perform fine grinding repair by predicting the size safety after repair. Specifically, for example, the target outer diameter of the main valve piston is set, and the allowable deviation of the size . If the measured outer diameter of the workpiece after grinding The dimensions were deemed acceptable, but the measured Barkhausen noise characteristic amplitude was... Below the magnetic threshold The system determines that the magnetic permeability is impaired based on the calibrated stress layer depth coefficient. Calculate the thickness of the stress layer that needs to be removed. Then, the expected dimensions of the repaired workpiece are calculated. .because If the minimum dimensional requirements are met, the system determines that the workpiece is worth repairing and initiates a polishing repair. The above example quantifies the thickness of the stress layer to be removed due to magnetic defects and predicts repair feasibility. While eliminating residual surface stress to restore magnetic conductivity, it avoids dimensional defects caused by blind repairs, ensuring that the final manufactured main valve piston possesses both excellent sealing performance and sensitive electromagnetic response speed. This effectively solves the problem of damping adjustment hysteresis caused by latent magnetic damage in existing technologies. Example 2

[0055] As a second embodiment of the present invention, based on embodiment 1, a shock absorber solenoid valve main valve piston manufacturing system is also disclosed, such as... Figure 3 As shown, the system specifically includes: an initial reverse machining modeling module, a grinding process health monitoring module, a thermal coupling compensation module, and a dual judgment and repair module. The system runs in the control center of a CNC grinding machine equipped with a high-performance processor and memory. The specific functions and execution logic of each module are as follows: In implementation 2, firstly, the initial reverse machining modeling module is used to solve the problem of clamping deformation of thin-walled parts. This module is connected to the hydraulic fixture controller of the CNC grinding machine and reads the set clamping force in real time. It also internally stores a pre-calibrated deformation amplitude function for DT4C material. Before processing begins, this module determines the current clamping force. Calculate the amplitude of each harmonic distortion. The system calculates and generates the initial feed path trajectory of the pre-deformed grinding wheel. This trajectory includes pre-set concave compensation at the gripper positions and pre-set convex compensation at non-gripper positions, ensuring the workpiece springs back to a perfect circle when the clamp is released after grinding. Furthermore, the grinding process health monitoring module is electrically connected to the acoustic emission (AE) sensor and spindle power sensor installed on the CNC grinding machine, acquiring acoustic emission signals in real time during the grinding process. With spindle power Calculate the grinding health index Meanwhile, this module has built-in comparison logic; when it detects... Below the set burn threshold Immediately upon activation, a command is sent to the machine tool PLC to trigger the intervention mechanism: the radial feed rate is adjusted. The pressure is reduced to 50% of the current level to minimize heat input, and a command is simultaneously sent to the high-pressure cooling pump to increase the pressure to 5 MPa for enhanced flushing, preventing workpiece surface burns. The thermo-coupling compensation module is used to eliminate dimensional errors caused by thermal expansion and contraction. The background continuously monitors the spindle power. Perform integration to obtain the cumulative heat. The workpiece's real-time radial thermal expansion value is calculated by combining the material's thermophysical parameters. It communicates in real time with the interpolator of the CNC system to dynamically correct the feed path of the grinding wheel. By superimposing the retraction amount in real time, this module ensures that the actual size of the workpiece ground under thermal expansion conditions still meets the sealing requirements after cooling. The dual judgment and repair module reads the actual outer diameter of the workpiece measured by the laser diameter gauge. The module determines whether the workpiece should be scrapped or continue grinding, and, provided the dimensions are within acceptable limits, reads the Barkhausen noise value. The magnetic properties of the workpiece are determined. If the magnetic properties are unqualified, a magnetic repair mechanism is triggered to repair the workpiece. This ensures that the final manufactured main valve piston has both excellent sealing performance and sensitive electromagnetic response speed, solving the problem of damping adjustment lag caused by latent magnetic damage in the existing technology.

[0056] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0057] The preferred embodiments of the invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A method of manufacturing a main valve piston of a shock absorber solenoid valve, characterized by, Comprise: read the set clamping force, based on the deformation amplitude function related to the clamping force, generate the initial feed path trajectory of the pre-deformation grinding wheel; Real-time acquisition of acoustic emission signal and spindle power in the grinding process, construct the grinding health index, and adjust the cutting parameters according to the grinding health index to prevent burn; Based on the cumulative heat in the grinding process, a thermal coupling model is constructed to calculate the radial thermal expansion value of the main valve piston, and the initial feed path trajectory of the grinding wheel is corrected in real time to obtain the corrected grinding wheel feed path trajectory; Based on the corrected grinding wheel feed path trajectory, the main valve piston is machined, and the size and magnetic double judgment is performed on the machined main valve piston. The main valve piston with qualified size but unqualified magnetism is executed magnetic repair.

2. The shock absorber solenoid valve main valve piston manufacturing method according to claim 1, characterized by, The specific formula for generating the initial feed path trajectory of the pre-deformation grinding wheel is: In the formula, Inscribed angle The radius of the grinding wheel command at that location, The target design radius for the piston. For harmonic orders, To be compatible with clamping force The relevant deformation amplitude function, It is the deformed phase angle.

3. The shock absorber solenoid valve main valve piston manufacturing method according to claim 2, characterized by, The deformation amplitude function is calibrated by using an exponential saturation model, which is specifically represented as: ； wherein denotes the denotes the denotes the denotes the is a deformation sensitivity coefficient, is a set value for the clamping force.

4. The shock absorber solenoid valve main valve piston manufacturing method according to claim 1, characterized by, The calculation formula of the grinding health index is: wherein, is the grinding health index at time is the power spectral density of the acoustic emission signal at time is the main shaft power at time is the weighting coefficient, is the normalization constant, and is the acoustic emission concerned frequency band.​​​ 5. The shock absorber solenoid valve main valve piston manufacturing method according to claim 4, characterized by, Adjusting the cutting parameters to prevent burn according to the grinding health index specifically includes: setting a burn threshold ; when the grinding health index , the system determines that there is no burn risk, and the current machining parameters are maintained; when the grinding health index , the system determines that there is a burn risk, and triggers an intervention mechanism: the intervention mechanism includes: the control system reduces the radial feed speed to reduce the heat flux input, and synchronously controls the high-pressure cooling pump to increase the cooling liquid pressure for enhanced flushing to remove the blockage on the grinding wheel surface.

6. The shock absorber solenoid valve main valve piston manufacturing method according to claim 1, characterized by, The calculation formula of the radial thermal expansion value of the main valve piston is: ； wherein is the time is the radial thermal expansion of the main valve piston, is the material linear expansion coefficient, is the target design radius of the piston, is the time is the surface temperature rise of the main valve piston.

7. The shock absorber solenoid valve main valve piston manufacturing method according to claim 6, characterized by, The specific formula of the corrected grinding wheel feed path trajectory is: ； In the formula, is the corrected grinding wheel feed path trajectory, is the thermal compensation gain coefficient.

8. The shock absorber solenoid valve main valve piston manufacturing method according to claim 1, characterized by, The size and magnetic double judgment is performed on the machined main valve piston, which specifically includes: Measuring the actual outer diameter of the processed workpiece by means of a laser diameter measuring instrument , setting the allowable deviation of the size , and obtaining the target outer diameter of the main valve piston determined in the design stage ; if , determining that the main valve piston is scrapped; if , determining that grinding needs to continue ; if , determining that the size of the main valve piston is qualified Adopting the measurement of the Barkhausen noise probe to obtain the Barkhausen noise characteristic amplitude , and setting the magnetic threshold value ; if , determining that the main valve piston is qualified, and ending the grinding process; if , determining that the magnetism is unqualified, and triggering the magnetic repair mechanism.

9. The shock absorber solenoid valve main valve piston manufacturing method according to claim 8, characterized by, The magnetic repairing mechanism specifically comprises: calculating the stress layer thickness to be removed , wherein is a stress layer depth coefficient; calculating the workpiece size after expected repairing , if , determining that the main valve piston is scrapped and no longer repaired, otherwise, performing magnetic repairing of the main valve piston in a light grinding polishing mode.

10. A shock absorber electromagnetic valve main valve piston manufacturing system that adopts the shock absorber electromagnetic valve main valve piston manufacturing method according to any one of claims 1 to 9, characterized by, Comprise: An initial reverse machining modeling module is configured to calculate the elastic deformation field caused by the clamping force based on the set clamping force, and generate the initial feed path trajectory of the pre-deformation grinding wheel accordingly; A grinding process health monitoring module is configured to real-time acquisition of acoustic emission signal and spindle power in the grinding process, construct the grinding health index, and adjust the cutting parameters according to the grinding health index to prevent burn; A thermal coupling compensation module is configured to construct a thermal coupling model based on the cumulative heat in the grinding process, calculate the radial thermal expansion value of the main valve piston, and correct the initial feed path trajectory of the grinding wheel in real time to obtain the corrected grinding wheel feed path trajectory; A double judgment and repair module is configured to machine the main valve piston based on the corrected grinding wheel feed path trajectory, and perform size and magnetic double judgment on the machined main valve piston. The main valve piston with qualified size but unqualified magnetism is executed magnetic repair.

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