High-strength stress shot blasting process for high-stress plate spring

Abstract

The invention relates to the technical field of plate spring stress shot blasting treatment, in particular to a high-stress plate spring high-strength stress shot blasting process which comprises the following steps that steel shots meeting the requirements for components and sizes are obtained, and impurities on the surface of a plate spring are pretreated; based on the size and material data of the plate spring, a plate spring shot blasting control model is established; and target shot blasting parameters of shot blasting equipment are preset based on the plate spring shot blasting control model. According to the high-stress plate spring high-strength stress shot blasting process, a plate spring shot blasting control model is constructed, and target shot blasting parameters of shot blasting equipment are preset based on the model. In the process, the size, the material characteristics and the expected shot blasting effect of the plate spring are fully considered, so that the setting of shot blasting parameters is more accurate and scientific. Compared with a traditional mode that shot blasting parameters are determined according to experience or simple tests, the process can remarkably improve the stability and consistency of the shot blasting effect, and it is ensured that each shot blasting treatment can achieve the expected effect.

Description

Technical Field

[0001] The invention relates to the technical field of leaf spring stress shot blasting treatment, in particular to a high-stress leaf spring high-strength stress shot blasting process. Background Art

[0002] High-strength stress shot blasting process for high-stress leaf springs is an advanced surface treatment technology that uses high-speed projectile flow to impact the metal surface, thereby generating a cyclic plastic strain layer, causing favorable changes in the microstructure of the layer, and introducing a residual compressive stress field in the surface layer. This process can significantly improve the fatigue strength and stress corrosion cracking resistance of metal materials and their springs, thereby improving the reliability and durability of the product.

[0003] In the field of metal surface treatment, shot blasting has been widely used in the surface cleaning, strengthening and modification of various metal materials. The traditional shot blasting process mainly uses high-speed projectiles to impact the metal surface to remove surface dirt, oxide layer, etc., and to produce a certain compressive stress layer to improve the material's fatigue resistance.

[0004] For high-stress leaf springs, the existing shot blasting process can improve its surface quality and stress state to a certain extent, but it has the following shortcomings:

[0005] Shot blasting parameter settings lack precision: Traditional shot blasting processes often rely on experience or simple tests to determine shot blasting parameters, such as shot blasting intensity, coverage, shot blasting time, etc. This approach lacks scientificity and systematicity, and it is difficult to ensure the stability and consistency of the shot blasting effect.

[0006] Insufficient residual stress control: High-stress leaf springs need to withstand large loads and stresses during use, so the control of their residual stress is extremely demanding. The existing shot blasting process has deficiencies in residual stress control, making it difficult to achieve precise regulation of residual stress inside leaf springs. Summary of the invention

[0007] In view of the technical problems existing in the prior art, the present invention provides a high-stress leaf spring high-intensity stress shot blasting process to solve the problem of poor accuracy and insufficient residual stress control in the above-mentioned shot blasting process.

[0008] 本发明解决上述技术问题的技术方案如下： A high-stress leaf spring high-strength stress shot blasting process comprises the following steps:

[0009] Obtain steel shots that meet the composition and size requirements, and pre-treat the impurities on the surface of the leaf spring;

[0010] Based on the size and material data of leaf spring, a leaf spring shot blasting control model is established;

[0011] Based on the leaf spring shot blasting control model, the target shot blasting parameters of the shot blasting equipment are preset;

[0012] Real-time detection of leaf spring shot blasting effect, and feedback to the leaf spring shot blasting control model to correct the target shot blasting parameters in real time;

[0013] Heat treatment is performed on the leaf spring after shot blasting to control the depth and distribution of residual stress in the leaf spring.

[0014] Based on the above technical solution, the present invention can also be improved as follows.

[0015] Further, the size data includes length, width and thickness data;

[0016] The material data includes carbon content, alloy element ratio, and hardness data;

[0017] The shot blasting parameters include shot blasting intensity, coverage, shot blasting time and medium temperature.

[0018] Furthermore, the leaf spring shot blasting control model includes: a shot blasting intensity and leaf spring deformation and residual stress distribution model, a coverage model, and a shot blasting time and medium temperature model.

[0019] Furthermore, the establishment of the shot blasting intensity, leaf spring deformation and residual stress distribution model includes the following steps:

[0020] According to the material properties of leaf springs and the dynamic effects during shot blasting, a dynamic stress-strain relationship model is constructed;

[0021] The kernel function h(τ) reflecting the memory effect of the material is obtained by fitting the experimental data;

[0022] Substituting the kernel function h(τ) into the dynamic stress-strain relationship formula, the mathematical model describing the deformation behavior of the leaf spring is obtained:

[0023] The dynamic stress-strain relationship formula is:

[0024]

[0025] h(τ) is the kernel function of the material memory effect;

[0026] τ is the time delay;

[0027] t is the current time;

[0028] σ(t) represents the stress at time t;

[0029] E represents the elastic modulus of the material;

[0030] ∈(t) represents the strain at time t;

[0031] According to the shape, size, speed and impact angle of the shot blasting medium, a residual stress calculation model is constructed;

[0032] Determine the function fi (parameter i) and weight coefficient αi that describe the contribution of each influencing factor to stress distribution;

[0033] The function fi (parameter i) and weight coefficient αi are optimized through multivariate regression analysis, machine learning and other methods;

[0034] Substitute the optimized function and weight coefficient into the residual stress calculation formula to obtain the mathematical model describing the residual stress distribution of the leaf spring.

[0035] The residual stress calculation formula is:-

[0036]

[0037] in,

[0038] σ r is the residual stress;

[0039] σ a is the applied stress;

[0040] σ e is the elastic recovery stress;

[0041] f i (parameter i) is the function of the contribution of the i-th influencing factor to the stress distribution;

[0042] a i is the weight coefficient of the influencing factor;

[0043] According to the deformation amount and residual stress distribution target value of leaf spring, the shot peening strength control model is constructed;

[0044] Determine PID control parameters Kp, Ki, Kd, ​​and adjust them through system identification or trial and error;

[0045] The PID control algorithm is applied to the shot blasting intensity control model to adjust the shot blasting intensity in real time according to the leaf spring deformation and residual stress distribution;

[0046] The PID control algorithm formula is:

[0047]

[0048] in,

[0049] u(t) is the adjustment amount of shot blasting intensity);

[0050] e(t) is the difference between the current deformation or residual stress distribution and the target value;

[0051] kp , k i , k d are the proportional, integral and derivative gain coefficients respectively.

[0052] Furthermore, the establishment of the coverage model includes the following steps:

[0053] Calculate the coverage rate of the leaf spring surface covered by the shot blasting medium after shot blasting;

[0054] The coverage calculation formula is:

[0055]

[0056] C: coverage;

[0057] N: the number of shot blasting media;

[0058] A: average coverage area of ​​each shot blasting medium;

[0059] S: total surface area of ​​leaf spring;

[0060] d: The diameter of the shot blasting medium.

[0061] Further, the establishment of the shot blasting time and medium temperature model includes the following steps:

[0062] Adjust the shot blasting time and medium temperature according to the surface roughness and microstructure changes of the leaf spring;

[0063] Construct the surface roughness variation formula:

[0064] Ra=f(t,T);

[0065] Construct the formula for microstructure change:

[0066] ΔH=g(t,T);

[0067] Ra: surface roughness;

[0068] t: shot blasting time;

[0069] T: medium temperature;

[0070] ΔH: microhardness change.

[0071] Further, the steps of pre-treating the impurities on the surface of the leaf spring are as follows:

[0072] Use oil cleaning agent to clean the oil on the surface of the leaf spring;

[0073] Use a steel brush to remove dry soil and rust from the leaf spring surface;

[0074] Immerse the leaf spring in a phosphating solution for phosphating treatment;

[0075] Electrostatic dust removal equipment is used to perform electrostatic dust removal on the surface of the leaf spring.

[0076] Furthermore, when the leaf spring shot blasting effect is detected in real time, a laser scanner and an ultrasonic thickness gauge are used to monitor the roughness, coverage, and residual stress distribution indicators of the leaf spring surface in real time.

[0077] Further, the heat treatment of the leaf spring after shot blasting comprises the following steps:

[0078] Heat the leaf spring to a certain temperature, keep it warm for a period of time, and then cool it naturally to room temperature;

[0079] The leaf spring is quenched or tempered immediately after deformation;

[0080] After the leaf spring is heated to a certain temperature, it is quickly transferred to an isothermal quenching medium, kept for a certain period of time, and then taken out for air or oil cooling;

[0081] The leaf spring is preloaded so that its deformation exceeds the possible deformation during operation, and is kept warm for a certain period of time in an environment higher than the operating temperature.

[0082] Moreover, the high-stress leaf spring high-strength stress shot blasting process provided by the present invention has at least the following beneficial effects compared with the prior art:

[0083] By building a shot blasting control model, accurately presetting the shot blasting parameters, and detecting the shot blasting effect in real time for dynamic adjustment, it is ensured that the surface of the leaf spring reaches the expected roughness, coverage and residual stress distribution, thereby improving the strength and durability of the leaf spring.

[0084] Pretreatment steps such as oil cleaning, steel brush rust removal, phosphating and electrostatic dust removal are adopted to thoroughly clean the surface of the leaf spring, improve its surface roughness, provide high-quality substrate conditions for shot blasting, and ensure the success of shot blasting effect and subsequent heat treatment.

[0085] 1. The high-strength stress shot blasting process for high-stress leaf springs builds a leaf spring shot blasting control model and presets the target shot blasting parameters of the shot blasting equipment based on the model. In this process, the size, material properties and expected shot blasting effect of the leaf spring are fully considered, making the setting of shot blasting parameters (such as shot blasting intensity, coverage, shot blasting time, etc.) more accurate and scientific. Compared with the traditional method of determining shot blasting parameters based on experience or simple experiments, this process can significantly improve the stability and consistency of the shot blasting effect, ensuring that each shot blasting treatment can achieve the expected effect.

[0086] 2. In view of the extremely high requirements for residual stress control of high-stress leaf springs, the high-strength stress shot blasting process for high-stress leaf springs monitors the shot blasting effect in real time and feeds back to the shot blasting control model to achieve real-time correction of the shot blasting parameters. At the same time, combined with the heat treatment process, the residual stress of the leaf spring after shot blasting is further regulated. In this process, the impact of the shot blasting medium on the surface of the leaf spring and the influence of heat treatment on the internal structure of the leaf spring are fully considered, so that the distribution and depth of the residual stress are accurately regulated. This process can meet the strict requirements of high-stress leaf springs for residual stress during use and improve their fatigue strength and stress corrosion cracking resistance.

[0087] 3. The high-strength stress shot blasting process for high-stress leaf springs not only solves the shortcomings of the traditional shot blasting process in terms of shot blasting parameter setting and residual stress control, but also significantly improves the surface quality and stress state of high-stress leaf springs by optimizing shot blasting parameters and heat treatment processes. The application of this process can significantly improve the reliability and durability of the product and extend the service life of the product. At the same time, this process also provides new ideas and methods for the field of metal surface treatment, promoting the progress and development of metal surface treatment technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0089] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0090] It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrally formed structure. For ordinary technicians in this field, the specific meanings of such terms in this patent can be understood according to specific circumstances.

[0091] like Figure 1 As shown, the high-stress leaf spring high-intensity stress shot blasting process designed by the present invention comprises the following steps:

[0092] Obtain steel shots that meet the composition and size requirements, and pre-treat the impurities on the surface of the leaf spring;

[0093] Based on the size and material data of leaf spring, a leaf spring shot blasting control model is established;

[0094] Based on the leaf spring shot blasting control model, the target shot blasting parameters of the shot blasting equipment are preset;

[0095] Real-time detection of leaf spring shot blasting effect, and feedback to the leaf spring shot blasting control model to correct the target shot blasting parameters in real time;

[0096] Heat treatment is performed on the leaf spring after shot blasting to control the depth and distribution of residual stress in the leaf spring.

[0097] First, steel shots that meet the requirements are selected to pre-treat the surface of the leaf spring to remove impurities. Then, a shot blasting control model is established based on the size and material characteristics of the leaf spring, and the target parameters of the shot blasting equipment are preset based on the model. During the shot blasting process, the shot blasting effect is detected in real time, and the shot blasting parameters are dynamically adjusted based on the feedback results to ensure the shot blasting effect. Finally, the leaf spring after shot blasting is heat treated to accurately control the residual stress depth and distribution of the leaf spring, so as to meet the requirements of high-strength stress.

[0098] As an implementation method, the size data includes length, width and thickness data;

[0099] The material data includes carbon content, alloy element ratio, and hardness data;

[0100] The shot blasting parameters include shot blasting intensity, coverage, shot blasting time and medium temperature.

[0101] First, the key dimension data (length, width, thickness) and material data (carbon content, alloy element ratio, hardness) of the leaf spring are collected. These data provide the basis for establishing the shot blasting control model. Then, according to this model, the shot blasting parameters are preset, including shot blasting intensity, coverage, shot blasting time and medium temperature. These parameters directly determine the effect of shot blasting. During the shot blasting process, the shot blasting effect is monitored in real time, and the feedback data is sent back to the shot blasting control model to achieve real-time adjustment and optimization of the shot blasting parameters to ensure that the shot blasting treatment achieves the predetermined goal.

[0102] Specifically, the leaf spring shot blasting control model includes: a shot blasting intensity and leaf spring deformation and residual stress distribution model, a coverage model, and a shot blasting time and medium temperature model.

[0103] The first is the shot blasting intensity and leaf spring deformation and residual stress distribution model, which predicts the deformation degree and residual stress distribution of the leaf spring under different shot blasting intensities based on the size and material data of the leaf spring; the second is the coverage model, which is used to calculate and optimize the coverage of the steel shot on the surface of the leaf spring during the shot blasting process to ensure that the shot blasting effect is uniform and sufficient; the last is the shot blasting time and medium temperature model, which determines the optimal shot blasting time and medium temperature based on the shot blasting intensity, coverage and specific needs of the leaf spring, so as to avoid excessive or insufficient shot blasting while ensuring efficiency.

[0104] As an implementation method, the establishment of the shot blasting intensity, leaf spring deformation and residual stress distribution model includes the following steps:

[0105] According to the material properties of leaf springs and the dynamic effects during shot blasting, a dynamic stress-strain relationship model is constructed;

[0106] The kernel function h(τ) reflecting the memory effect of the material is obtained by fitting the experimental data;

[0107] Substituting the kernel function h(τ) into the dynamic stress-strain relationship formula, the mathematical model describing the deformation behavior of the leaf spring is obtained:

[0108] The dynamic stress-strain relationship formula is:

[0109]

[0110] h(τ) is the kernel function of the material memory effect;

[0111] τ is the time delay;

[0112] t is the current time;

[0113] σ(t) represents the stress at time t;

[0114] E represents the elastic modulus of the material;

[0115] ∈(t) represents the strain at time t;

[0116] Based on the material properties of leaf springs and the dynamic effects during shot blasting, a mathematical model describing the relationship between stress and strain of materials during shot blasting is constructed. This model takes into account the memory effect of the material, that is, the internal stress state of the material will change over time after being subjected to external force.

[0117] By fitting the experimental data, a kernel function h(τ) reflecting the material memory effect is obtained. This function describes the law of how the internal stress state of the material changes with time after being subjected to external force.

[0118] Substituting the kernel function h(τ) into the dynamic stress-strain relationship formula, a mathematical model describing the deformation behavior of the leaf spring during shot blasting is obtained. This model can predict the deformation of the leaf spring under different shot blasting intensities.

[0119] According to the shape, size, speed and impact angle of the shot blasting medium, a residual stress calculation model is constructed;

[0120] Determine the function fi (parameter i) and weight coefficient αi that describe the contribution of each influencing factor to stress distribution;

[0121] The function fi (parameter i) and weight coefficient αi are optimized through multivariate regression analysis, machine learning and other methods;

[0122] Substitute the optimized function and weight coefficient into the residual stress calculation formula to obtain the mathematical model describing the residual stress distribution of the leaf spring.

[0123] The residual stress calculation formula is:-

[0124]

[0125] in,

[0126] σ r is the residual stress;

[0127] σ a is the applied stress;

[0128] σ e is the elastic recovery stress;

[0129] f i (parameter i) is the function of the contribution of the i-th influencing factor to the stress distribution;

[0130] a i is the weight coefficient of the influencing factor;

[0131] According to the shape, size, speed and impact angle of the shot blasting medium, a mathematical model for calculating the residual stress of the leaf spring is constructed. This model takes into account the contribution of multiple influencing factors to the stress distribution and optimizes these influencing factors through methods such as multivariate regression analysis or machine learning.

[0132] According to the deformation amount and residual stress distribution target value of leaf spring, the shot peening strength control model is constructed;

[0133] Determine PID control parameters Kp, Ki, Kd, ​​and adjust them through system identification or trial and error;

[0134] The PID control algorithm is applied to the shot blasting intensity control model to adjust the shot blasting intensity in real time according to the leaf spring deformation and residual stress distribution;

[0135] The PID control algorithm formula is:

[0136]

[0137] in,

[0138] u(t) is the adjustment amount of shot blasting intensity);

[0139] e(t) is the difference between the current deformation or residual stress distribution and the target value;

[0140] k p , k i , k d are the proportional, integral and derivative gain coefficients respectively.

[0141] Based on the deformation and residual stress distribution target values ​​of the leaf spring, a shot blasting intensity control model is constructed. This model uses a PID control algorithm to adjust the shot blasting intensity in real time according to the difference between the current deformation or residual stress distribution and the target value to achieve the desired process effect.

[0142] As an implementation method, the establishment of the coverage model includes the following steps:

[0143] Calculate the coverage rate of the leaf spring surface covered by the shot blasting medium after shot blasting;

[0144] The coverage calculation formula is:

[0145]

[0146] C: coverage;

[0147] N: the number of shot blasting media;

[0148] A: average coverage area of ​​each shot blasting medium;

[0149] S: total surface area of ​​leaf spring;

[0150] d: The diameter of the shot blasting medium.

[0151] Calculate the coverage of the leaf spring surface covered by the shot blasting media after shot blasting. This coverage is calculated based on the number of shot blasting media, the average coverage area of ​​each shot blasting medium, and the total surface area of ​​the leaf spring. The coverage reflects the degree of treatment of the leaf spring surface by the shot blasting media, which is of great significance for controlling the quality and effect of shot blasting.

[0152] As an implementation method, the establishment of the shot blasting time and medium temperature model includes the following steps:

[0153] Adjust the shot blasting time and medium temperature according to the surface roughness and microstructure changes of the leaf spring;

[0154] Construct the surface roughness variation formula:

[0155] Ra=f(t,T);

[0156] Construct the microstructure change formula:

[0157] ΔH=g(t,T);

[0158] Ra: surface roughness;

[0159] t: shot blasting time;

[0160] T: medium temperature;

[0161] ΔH: microhardness change.

[0162] First, it is clear that the goal of the model is to predict and control the surface roughness and microstructure changes of leaf springs during shot peening.

[0163] Shot peening time (t) and medium temperature (T) were selected as independent variables because these two parameters directly affect the surface quality of leaf springs during shot peening process.

[0164] The surface roughness change formula Ra=f(t,T) is constructed to describe the influence of shot blasting time and medium temperature on the surface roughness of leaf springs.

[0165] The microstructure change formula ΔH=g(t,T) is constructed to describe the influence of shot blasting time and medium temperature on the change of microhardness of leaf spring.

[0166] These two formulas are the core of the model, which express the relationship between the independent variables (shot blasting time, medium temperature) and the dependent variables (surface roughness, microhardness change) through mathematical relationships.

[0167] The shot blasting time and medium temperature are adjusted according to the initial surface roughness and microstructure of the leaf spring and the desired surface quality target.

[0168] Through experiments or simulation methods, the surface roughness and microhardness change data at different shot blasting times and medium temperatures are collected.

[0169] These data are used to fit and optimize the mathematical model and determine the functional relationship f and g in the formula.

[0170] The accuracy of the model was verified to ensure that it could accurately predict the changes in surface roughness and microhardness for different blasting times and media temperatures.

[0171] The model is applied in actual production to set appropriate shot blasting time and medium temperature according to the desired surface quality target to achieve high-quality shot blasting of leaf springs.

[0172] The principle of establishing the shot blasting time and medium temperature model is based on a deep understanding of the surface roughness and microstructure changes of leaf springs. By constructing a mathematical model and optimizing parameters, scientific control of the shot blasting process can be achieved.

[0173] As an implementation method, the steps of pre-treating impurities on the surface of the leaf spring are as follows:

[0174] Use oil cleaning agent to clean the oil on the surface of the leaf spring;

[0175] Use a steel brush to remove dry soil and rust from the leaf spring surface;

[0176] Immerse the leaf spring in a phosphating solution for phosphating treatment;

[0177] Electrostatic dust removal equipment is used to perform electrostatic dust removal on the surface of the leaf spring.

[0178] Use oil cleaning agent to utilize chemical or physical action to effectively remove grease, oil and other pollutants on the surface of leaf springs.

[0179] Use a steel brush or other physical tool to remove dry soil, rust and other attachments on the surface of the leaf spring through mechanical friction. This step can further clean the surface of the leaf spring and improve its surface roughness to a certain extent, which is conducive to the adhesion and uniformity of the shot blasting medium in subsequent treatment.

[0180] The leaf spring is immersed in the phosphating solution, and a dense phosphating film is formed on the surface of the leaf spring through chemical reaction. This phosphating film can not only enhance the corrosion resistance and wear resistance of the leaf spring surface, but also improve its bonding strength with subsequent coatings or treatment layers, providing protection for the long-term use of the leaf spring.

[0181] Electrostatic dust removal equipment is used to completely remove tiny dust particles and floating dust on the surface of the leaf spring using the principle of electrostatic adsorption. This step is the final step of the pretreatment process, which can ensure that the surface of the leaf spring reaches a very high degree of cleanliness and provide the best substrate conditions for subsequent shot blasting and high-intensity stress treatment.

[0182] As an implementation mode, when the leaf spring shot blasting effect is detected in real time, a laser scanner and an ultrasonic thickness gauge are used to monitor the roughness, coverage, and residual stress distribution indicators of the leaf spring surface in real time.

[0183] The laser scanner emits a laser beam and receives the reflected light. According to the intensity, angle or phase change of the reflected light, it can accurately measure the tiny fluctuations on the surface of the leaf spring, thereby calculating the surface roughness. This non-contact measurement method has the characteristics of high precision and high efficiency, and can reflect the improvement of the surface roughness of the leaf spring by shot blasting in real time.

[0184] Combined with image processing technology, the laser scanner can also collect and analyze images of the leaf spring surface after shot blasting, and evaluate the coverage of the leaf spring surface by the shot blasting media by calculating the area ratio of different grayscale values ​​or color areas in the image. This helps to ensure that the shot blasting process achieves the expected uniformity and integrity.

[0185] When measuring the thickness of leaf springs, the ultrasonic thickness gauge can simultaneously detect the change in the speed of ultrasonic waves propagating inside the material, which is closely related to the residual stress state inside the material. By analyzing the propagation speed and reflection characteristics of ultrasonic waves, the residual stress distribution on the surface of the leaf spring can be indirectly calculated. This method has the advantages of being non-destructive and having a wide range of applications, and can monitor the impact of shot blasting on the residual stress of leaf springs in real time.

[0186] As an embodiment, the heat treatment of the leaf spring after shot blasting includes the following steps:

[0187] Heat the leaf spring to a certain temperature, keep it warm for a period of time, and then cool it naturally to room temperature;

[0188] The leaf spring is quenched or tempered immediately after deformation;

[0189] After the leaf spring is heated to a certain temperature, it is quickly transferred to an isothermal quenching medium, kept for a certain period of time, and then taken out for air or oil cooling;

[0190] The leaf spring is preloaded so that its deformation exceeds the possible deformation during operation, and is kept warm for a certain period of time in an environment higher than the operating temperature.

[0191] The leaf spring is heated to a certain temperature (usually lower than the critical temperature of the material) and kept warm for a period of time. The purpose of this step is to homogenize the internal structure of the leaf spring, reduce internal stress, and prepare for the subsequent heat treatment steps.

[0192] After naturally cooling to room temperature, the structure and performance of the leaf spring are initially adjusted, providing a stable foundation for subsequent deformation processing.

[0193] The leaf spring is immediately quenched or tempered after deformation. Quenching is to heat the leaf spring to above the critical temperature and then cool it quickly to increase its hardness and strength. Tempering is to heat the leaf spring to a certain temperature after quenching and then cool it slowly to eliminate quenching stress and improve toughness and plasticity.

[0194] After the leaf spring is heated to a certain temperature, it is quickly transferred to an isothermal quenching medium (such as a salt bath, oil bath, etc.), kept for a certain period of time, and then taken out for air cooling or oil cooling. The characteristic of isothermal quenching is that the temperature of the quenching medium is constant, which can reduce the quenching stress and avoid deformation and cracking of the leaf spring.

[0195] Preload the leaf spring so that its deformation exceeds the possible deformation during operation. This step is called "pre-deformation treatment" and aims to generate a certain amount of prestress inside the leaf spring through preloading, thereby reducing deformation during operation.

[0196] Then, the spring is kept at a temperature higher than the working temperature for a certain period of time. The purpose of this step is to further stabilize the structure and performance of the pre-deformed leaf spring at high temperature, while eliminating or reducing the internal stress caused by the pre-deformation.

[0197] It should be noted that, in this article, the terms "include", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0198] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0199] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A high-stress leaf spring high-strength stress shot blasting process, characterized in that: The following steps are involved: Obtain steel shots that meet the composition and size requirements, and pre-treat the impurities on the surface of the leaf spring; Based on the size and material data of leaf spring, a leaf spring shot blasting control model is established; Based on the leaf spring shot blasting control model, the target shot blasting parameters of the shot blasting equipment are preset; Real-time detection of leaf spring shot blasting effect, and feedback to the leaf spring shot blasting control model to correct the target shot blasting parameters in real time; Heat treatment is performed on the leaf spring after shot blasting to control the depth and distribution of residual stress in the leaf spring.

2. The high-strength stress shot blasting process for high-stress leaf springs according to claim 1 is characterized in that: The size data includes length, width and thickness data; The material data includes carbon content, alloy element ratio, and hardness data; The shot blasting parameters include shot blasting intensity, coverage, shot blasting time and medium temperature.

3. The high-strength stress shot blasting process for high-stress leaf springs according to claim 2 is characterized in that: The leaf spring shot blasting control model includes: a shot blasting intensity and leaf spring deformation and residual stress distribution model, a coverage model, and a shot blasting time and medium temperature model.

4. The high-strength stress shot blasting process for high-stress leaf springs according to claim 3 is characterized in that: The establishment of the shot blasting intensity, leaf spring deformation and residual stress distribution model comprises the following steps: According to the material properties of leaf springs and the dynamic effects during shot blasting, a dynamic stress-strain relationship model is constructed; The kernel function h(τ) reflecting the memory effect of the material is obtained by fitting the experimental data; Substituting the kernel function h(τ) into the dynamic stress-strain relationship formula, the mathematical model describing the deformation behavior of the leaf spring is obtained: The dynamic stress-strain relationship formula is: h(τ) is the kernel function of the material memory effect; τ is the time delay; t is the current time; σ(t) represents the stress at time t; E represents the elastic modulus of the material; ∈(t) represents the strain at time t; According to the shape, size, speed and impact angle of the shot blasting medium, a residual stress calculation model is constructed; Determine the function fi (parameter i) and weight coefficient αi that describe the contribution of each influencing factor to stress distribution; The function fi (parameter i) and weight coefficient αi are optimized through multivariate regression analysis, machine learning and other methods; Substitute the optimized function and weight coefficient into the residual stress calculation formula to obtain the mathematical model describing the residual stress distribution of the leaf spring. The residual stress calculation formula is:- in, σ r is the residual stress; σ a is the applied stress; σ e is the elastic recovery stress; f i (parameter i) is the function of the contribution of the i-th influencing factor to the stress distribution; a i is the weight coefficient of the influencing factor; According to the deformation amount and residual stress distribution target value of leaf spring, the shot peening strength control model is constructed; Determine PID control parameters Kp, Ki, Kd, ​​and adjust them through system identification or trial and error; The PID control algorithm is applied to the shot blasting intensity control model to adjust the shot blasting intensity in real time according to the leaf spring deformation and residual stress distribution; The PID control algorithm formula is: in, u(t) is the adjustment amount of shot blasting intensity); e(t) is the difference between the current deformation or residual stress distribution and the target value; k p , k i , k d are the proportional, integral and derivative gain coefficients respectively.

5. The high-strength stress shot blasting process for high-stress leaf springs according to claim 3 is characterized in that: The establishment of the coverage model includes the following steps: Calculate the coverage rate of the leaf spring surface covered by the shot blasting medium after shot blasting; The coverage calculation formula is: C: coverage; N: the number of shot blasting media; A: average coverage area of ​​each shot blasting medium; S: total surface area of ​​leaf spring; d: The diameter of the shot blasting medium.

6. The high-strength stress shot blasting process for high-stress leaf springs according to claim 3, characterized in that: The establishment of the shot blasting time and medium temperature model comprises the following steps: Adjust the shot blasting time and medium temperature according to the surface roughness and microstructure changes of the leaf spring; Construct the surface roughness variation formula: Ra=f(t,T); Construct the formula for microstructure change: ΔH=g(t,T); Ra: surface roughness; t: shot blasting time; T: medium temperature; ΔH: microhardness change.

7. The high-strength stress shot blasting process for high-stress leaf springs according to claim 1, characterized in that: The steps of pre-treating impurities on the surface of the leaf spring are as follows: Use oil cleaning agent to clean the oil on the surface of the leaf spring; Use a steel brush to remove dry soil and rust from the leaf spring surface; Immerse the leaf spring in a phosphating solution for phosphating treatment; Electrostatic dust removal equipment is used to perform electrostatic dust removal on the surface of the leaf spring.

8. The high-strength stress shot blasting process for high-stress leaf springs according to claim 1, characterized in that: When the leaf spring shot blasting effect is detected in real time, a laser scanner and an ultrasonic thickness gauge are used to monitor the roughness, coverage, and residual stress distribution indexes of the leaf spring surface in real time.

9. The high-strength stress shot blasting process for high-stress leaf springs according to claim 1, characterized in that: The heat treatment of the leaf spring after shot blasting comprises the following steps: Heat the leaf spring to a certain temperature, keep it warm for a period of time, and then cool it naturally to room temperature; The leaf spring is quenched or tempered immediately after deformation; After the leaf spring is heated to a certain temperature, it is quickly transferred to an isothermal quenching medium, kept for a certain period of time, and then taken out for air or oil cooling; The leaf spring is preloaded so that its deformation exceeds the possible deformation during operation, and is kept warm for a certain period of time in an environment higher than the operating temperature.

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