Manufacturing method of main valve piston of shock absorber electromagnetic valve

Abstract

This invention relates to the field of shock absorber technology and discloses a method for manufacturing the main valve piston of a shock absorber solenoid valve. The method includes: reading a set clamping force and generating a pre-deformed initial feed path trajectory of the grinding wheel based on a deformation amplitude function; constructing a grinding health index during the grinding process and adjusting cutting parameters accordingly to prevent burns; constructing a thermo-mechanical coupling model based on the accumulated heat during grinding, 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; machining the main valve piston based on the corrected feed path trajectory of the grinding wheel, and performing dual dimensional and magnetic determination on the machined main valve piston; performing magnetic repair on main valve pistons that are dimensionally acceptable but magnetically unacceptable. This invention improves the sealing performance and electromagnetic response speed of the main valve piston by introducing a reverse compensation and thermo-mechanical coupling mechanism and repairing the hidden damage to magnetic conductivity caused by residual stress.

Description

Technical Field

[0001] This invention relates to the field of shock absorber technology, specifically to a method for manufacturing the main valve piston of a shock absorber solenoid valve. Background Technology

[0002] As a crucial component of the automotive suspension system, the performance of shock absorbers directly impacts a vehicle's ride comfort and handling stability. In high-performance continuously damped control (CDC) shock absorbers, the solenoid valve master piston is the core component responsible for both motion and electromagnetic response. This piston is typically made of soft magnetic materials such as DT4C electrical pure iron and is designed with a thin-walled structure to reduce moment of inertia. The geometric precision (e.g., roundness) of the master valve piston directly determines its sealing performance with the valve body and its damping characteristics, while its electromagnetic properties (permeability) determine the shock absorber's response speed to road condition signals.

[0003] Currently, machining the outer diameter of such thin-walled pistons relies on high-precision CNC cylindrical grinding machines. However, these machines often neglect the elastic deformation of the thin-walled piston during clamping and the high heat effect during grinding. Furthermore, they fail to consider the residual stress introduced into the piston surface by mechanical friction and heat during grinding. This results in significant accuracy errors and slow electromagnetic response in the actual machined workpiece. Specifically:

[0004] Regarding physical clamping, due to the thin wall thickness and weak rigidity of the piston, non-uniform elastic deformation occurs when clamping force is applied. Although a perfect circle is achieved through grinding under clamping conditions, the piston will spring back to a non-circular shape once the clamp is released, causing the final product's roundness to exceed the tolerance range. In terms of thermal deformation, the instantaneous high temperature generated during grinding easily causes the workpiece to expand. If grinding is performed according to the expanded dimensions, the actual dimensions will be smaller than the target dimensions after cooling and shrinking, resulting in overcutting errors. This dimensional error directly increases the clearance between the main valve piston and the valve body, reducing the main valve piston's sealing performance and leading to oil leakage or insufficient damping force in the shock absorber. Furthermore, the residual stress generated during grinding can cause latent damage to the magnetic conductivity of the main valve piston surface, resulting in a main valve piston with acceptable dimensions but slow electromagnetic response and sluggish damping adjustment after installation in the shock absorber. Therefore, a manufacturing method for the main valve piston of the shock absorber solenoid valve is urgently needed to solve these problems. Summary of the Invention

[0005] To address the problems in related technologies, this invention provides a method for manufacturing the main valve piston of a shock absorber solenoid valve, thereby overcoming the aforementioned technical problems in existing related technologies.

[0006] To solve the aforementioned technical problem, the present invention is achieved through the following technical solution:

[0007] 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.

[0008] 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:

[0009]

[0010] In the formula, Inscribed angle The grinding wheel command radius 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.

[0011] 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:

[0012] ;

[0013] 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.

[0014] 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:

[0015]

[0016] 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.

[0017] 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.

[0018] 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:

[0019] ;

[0020] 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.

[0021] 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:

[0022] ;

[0023] In the formula, This is the corrected grinding wheel feed path trajectory. This is the thermal compensation gain coefficient.

[0024] 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:

[0025] Measure the actual outer diameter of the machined workpiece using a laser diameter gauge , set the allowable deviation of the dimension , and obtain the target outer diameter of the main valve piston determined during the design phase ; If , determine that the main valve piston is scrapped; if , determine that grinding needs to continue dimension; if , determine that the dimension of the main valve piston is qualified;

[0026] Measure and obtain the Barkhausen noise characteristic amplitude using a Barkhausen noise probe , and set the magnetic threshold ; If , determine that the main valve piston is qualified and end the grinding process; if , determine that the magnetism is unqualified and trigger the magnetic repair mechanism

[0027] As a preferred embodiment of the method for manufacturing the main valve piston of the shock absorber solenoid valve according to the present invention, wherein the magnetic repair mechanism specifically includes: calculating the thickness of the stress layer to be removed , wherein is the stress layer depth coefficient; calculating the expected size of the workpiece after repair , if , determine that the main valve piston is scrapped and no longer repaired, otherwise, perform magnetic repair of the main valve piston by optical grinding and polishing

[0028] In a second aspect, an embodiment of the present invention provides a manufacturing system for the main valve piston of a shock absorber solenoid valve, specifically including: an initial reverse machining modeling module, configured to calculate the elastic deformation field caused by the clamping force according to the set clamping force, and generate an initial feed path trajectory of the 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 burns; 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, perform dual determination of size and magnetism on the processed main valve piston, and perform magnetic repair on the main valve piston with qualified size but unqualified magnetism

[0029] The present invention has the following beneficial effects:

[0030] 1. This invention addresses the problem of non-circular elastic deformation of thin-walled pistons under the action of clamps such as three-jaw expansion clamps. By establishing an initial reverse machining model, a non-circular contour complementary to the shape of the deformation under force is introduced to generate the initial feed path trajectory of the grinding wheel. The elastic rebound after the clamp is released is offset by a preset geometric deviation, so that the thin-walled workpiece can automatically recover to a high-precision circle when it is unclamped. This solves the problem in the prior art that the workpiece is rounded when clamped but rebounds excessively after being released.

[0031] 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.

[0032] 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.

[0033] 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

[0034] 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.

[0035] Figure 1 The present invention provides a flowchart of a method for manufacturing the main valve piston of a shock absorber solenoid valve.

[0036] 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.

[0037] 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

[0038] 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

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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:

[0043] S1. Establish the initial reverse machining model and generate the initial feed path trajectory of the pre-deformed grinding wheel.

[0044] 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:

[0045] S11. Load the DT4C piston blank 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.

[0046] 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:

[0047]

[0048] 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.

[0049] 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:

[0050] ;

[0051] 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.

[0052] 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. .

[0053] 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.

[0054] 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:

[0055] 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. :

[0056]

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 same set of test data for known grinding wheel conditions (sharp, dull, burned), several candidate grinding wheels were selected. 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.

[0061] 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.

[0062] 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:

[0063] S31. Calculate the cumulative heat of the workpiece, the expression is:

[0064] ;

[0065] In the formula, For a moment The accumulated heat of the main valve piston; Main spindle power.

[0066] S32. Estimate the surface temperature rise of the workpiece; the expression is as follows:

[0067] ;

[0068] 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 is fusible.

[0069] S33. Calculate the radial thermal expansion, the expression of which is:

[0070] ;

[0071] 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.

[0072] 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.

[0073] S34. Radial thermal expansion value calculated above The feed path trajectory is corrected in real time, and its expression is:

[0074] ;

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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:

[0079] 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. ;

[0080] 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.

[0081] like This indicates that the dimensions are too large and further grinding is required. Dimensions are determined, and then electromagnetic performance is assessed.

[0082] like If the workpiece dimensions are found to be acceptable, the electromagnetic performance assessment can proceed directly.

[0083] In this embodiment 1, the allowable deviation of dimensions Obtained through experimental calibration, the specific method is as follows: First, in the design stage, according to the mating relationship of the main valve assembly of the shock absorber, determine the minimum sealing requirements and the maximum assembly clearance between the main valve piston, the valve body, and the guide sleeve, and obtain the theoretically allowable outer diameter tolerance range; Second, in the process verification stage, select at least 30 trial-produced pistons, process them under different grinding heat states and different compensation conditions respectively, and record their actual outer diameters after cooling to room temperature. At the same time, install these pistons into the actual shock absorber valve body for assembly and functional testing, and focus on evaluating whether there are leaks, jams, or abnormal damping responses; Then, take the samples with completely normal functions as the effective sample set, conduct statistical analysis on their outer diameter deviations, and take the lower confidence limit of the deviation distribution (for example, 99% confidence level) as the size safety boundary to obtain the allowable deviation of the final size for online determination 。

[0084] S42. Electromagnetic property determination: The system controls the Barkhausen noise (MBN) probe to approach the surface of the workpiece to detect the characteristic amplitude of the Barkhausen noise of the workpiece, and records it as 。且 与材料表面的残余应力 呈相关关系,其中残余应力 常导致 下降,从而降低导磁率,可通过以下公式体现:

[0085] ;

[0086] 式中, 为残余应力转换系数,用于表征单位巴克豪森噪声幅值变化所对应的残余应力变化量; 为应力零偏修正项,用于补偿在零残余应力或基准应力状态下,由材料初始磁性能、探头安装条件及磁化电路引入的系统性偏移量。

[0087] 设定磁性阈值 ;若 ,判定工件合格,结束加工;若 ,判定磁性不合格,触发磁性修复机制。

[0088] In this Embodiment 1, the magnetic threshold 通过实验标定获得,具体方法如下:首先在与生产一致的装夹与检测条件下,采集大量试件的巴克豪森噪声(MBN)特征值 及对应的参考残余应力 ;然后基于线性模型建立 与 的回归映射,并由设计允许的最大残余应力 Calculate the corresponding magnetic threshold To balance detection rate and false alarm rate, ROC curve analysis was used, and a threshold maximizing the Youden index was selected. Finally, an appropriate safety margin was added in the production environment and verified through trial operation, thus completing the process. Confirmation and periodic recalibration are necessary to ensure the reliability and repeatability of magnetic determination under different operating conditions and time scales.

[0089] S43. Magnetic Repair Mechanism: The system calculates the required stress layer thickness to be removed based on the MBN difference. Its expression is:

[0090] ;

[0091] In the formula, This represents the stress layer depth coefficient.

[0092] In this embodiment 1, the stress layer depth coefficient The results were obtained through experimental calibration, using the following method: First, a main valve piston specimen consistent with the actual machining conditions was selected. Under conventional grinding parameters, a certain degree of residual grinding stress was artificially introduced to adjust its Barkhausen noise characteristic amplitude. Significantly below the magnetic threshold Subsequently, while maintaining the clamping and inspection conditions, a light grinding and polishing method with an extremely low feed rate was used to remove material in multiple rounds, with each round removing a known thickness. (e.g., 0.5-1), and measure the corresponding value immediately after each round. Then, statistical analysis. The trend of change with the increase of cumulative removed thickness is determined when First reply or more Cumulative thickness removed at time This thickness is considered as the equivalent residual stress layer depth of the specimen. Based on this, the above process is repeated for multiple specimens, and the average proportional relationship is used to obtain the stress layer depth coefficient. ,in This represents the initially detected Barkhausen noise amplitude. The amplitude obtained through this calibration method... It can directly convert the deviation of magnetic index into the thickness of the stress layer that needs to be removed, which avoids the complex inversion of the residual stress distribution and ensures that the amount of repair work has a clear physical basis and engineering operability.

[0093] S44. Calculate the expected dimensions of the repaired workpiece and pre-determine whether the workpiece dimensions are acceptable. Specifically:

[0094] Calculate the expected dimensions of the repaired workpiece. :

[0095] ;

[0096] If , it is predicted that the size of the workpiece after repair is too small, and the workpiece is directly determined to be scrapped without further repair to save processing time; otherwise, it is predicted that the size of the workpiece after repair is qualified, and the repair is started.

[0097] S45. The system starts the optical grinding and polishing method with an extremely low feed rate to remove the stress layer thickness of the workpiece , and detects and re-performs size and magnetic determination again. If the size after repair , and , the workpiece is determined to be qualified; if or , the workpiece is determined to be 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 perform maintenance.

[0098] In this Embodiment 1, the system performs double determination of size and magnetism, and reversely calculates the stress layer thickness when the magnetism is unqualified, and decides whether to perform optical 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 size is determined to be qualified, but the measured Barkhausen noise characteristic amplitude , which is lower than the magnetic threshold , and the magnetic conductivity performance is determined to be damaged. The system calculates the stress layer thickness to be removed according to the calibrated stress layer depth coefficient . Furthermore, the size of the workpiece after predicted repair is calculated . Since , it meets the minimum limit size requirement, and the system determines that the workpiece has repair value and starts optical grinding repair. The above example quantifies the stress layer thickness to be removed due to magnetic defects and predicts the repair feasibility. While eliminating the surface residual stress to restore the magnetic conductivity performance, it avoids size over-tolerance and scrapping caused by blind repair, ensuring that the finally manufactured main valve piston has both excellent sealing performance and sensitive electromagnetic response speed, and effectively solves the problem of damping adjustment hysteresis caused by hidden magnetic damage in the prior art. Embodiment 2

[0099] This is the second embodiment of the present invention. On the basis of Embodiment 1, a manufacturing system for the main valve piston of a shock absorber solenoid valve is further disclosed, as shown in Figure 3As 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:

[0100] 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 radial thermal expansion value of the workpiece in real time is calculated by combining the thermophysical parameters of the material. 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.

[0101] 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.

[0102] 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 for manufacturing the main valve piston of a shock absorber solenoid valve, characterized in that, include: Read the set clamping force and generate the initial feed path trajectory of the pre-deformed grinding wheel based on the deformation amplitude function related to the clamping force; During the grinding process, acoustic emission signals and spindle power are collected in real time to construct a grinding health index, and cutting parameters are adjusted according to the grinding health index to prevent burns. A thermo-mechanical coupling model is constructed based on the accumulated heat during the grinding process. The radial thermal expansion value of the main valve piston is calculated, and the initial feed path trajectory of the grinding wheel is corrected in real time to obtain the corrected feed path trajectory of the grinding wheel. The main valve piston is machined based on the modified grinding wheel feed path trajectory, and the machined main valve piston is subjected to dual judgment of size and magnetism. For main valve pistons with qualified size but unqualified magnetism, magnetic repair is performed.

2. The method for manufacturing the main valve piston of the shock absorber solenoid valve according to claim 1, characterized in that, 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 grinding wheel command radius 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 method for manufacturing the main valve piston of the shock absorber solenoid valve according to claim 2, characterized in that, 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.

4. The method for manufacturing the main valve piston of the shock absorber solenoid valve according to claim 1, characterized in that, 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.

5. The method for manufacturing the main valve piston of the shock absorber solenoid valve according to claim 4, characterized in that, Adjusting 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.

6. The method for manufacturing the main valve piston of the shock absorber solenoid valve according to claim 1, characterized in that, 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.

7. The method for manufacturing the main valve piston of the shock absorber solenoid valve according to claim 6, characterized in that, The specific formula for the corrected 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.

8. The method for manufacturing the main valve piston of the shock absorber solenoid valve according to claim 1, characterized in that, The machined main valve piston undergoes dual dimensional and magnetic determination, 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 was determined that grinding was required to continue. Size; if The piston size of the main valve is deemed to be acceptable. The Barkhausen noise characteristic amplitude is measured 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 ends; If , it is determined that the magnetism is unqualified and the magnetic repair mechanism is triggered.

9. The method for manufacturing the main valve piston of the shock absorber solenoid valve according to claim 8, characterized in that, The magnetic repair mechanism specifically includes: calculating the thickness of the stress layer to be removed. ,in, The stress layer depth factor is used to calculate the expected dimensions of the repaired workpiece. ,like If the main valve piston is deemed unusable and will not be repaired, then magnetic repair of the main valve piston will be performed using a light polishing method.

10. A manufacturing system for the main valve piston of a shock absorber solenoid valve, employing the manufacturing method for the main valve piston of a shock absorber solenoid valve according to any one of claims 1 to 9, characterized in that, include: The initial reverse machining modeling module is used to calculate the elastic deformation field caused by the clamping force based on the set clamping force, and generate the pre-deformed initial feed path trajectory of the grinding wheel accordingly. The grinding process health monitoring module is used 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 burns. The thermo-coupling compensation module is used to construct a thermo-coupling model based on the accumulated heat during 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 feed path trajectory of the grinding wheel. The dual judgment and repair module is used to process the main valve piston based on the corrected grinding wheel feed path trajectory, and to perform dual judgment on the dimensions and magnetism of the processed main valve piston. For main valve pistons with qualified dimensions but unqualified magnetism, magnetic repair is performed.

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