高强铝合金磨削表面创成机制与工艺参数优化OA

High-strength aluminum alloys represent a class of critical materials extensively utilized in the aerospace industry,primarily due to their exceptional specific strength,commendable corrosion resistance,and favorable machinability.Among them,the 2214 aluminum alloy is a prominent choice for structural components.Nevertheless,a comprehensive understanding of the surface generation mechanisms during grinding processes—a pivotal finishing operation—remains elusive.This knowledge gap is particularly evident concerning the intricate and competing interplay between strain rate sensitivity,which may lead to material hardening,and thermal softening behavior,which facilitates plastic flow.To bridge this gap,the present study employs a fundamental single-grit scratching approach to investigate the 2214 high-strength aluminum alloy,aiming to elucidate the underlying material removal mechanisms and its explicit dependence on key scratching parameters. For the experimental methodology,it was designed to isolate and simulate the fundamental interaction between a single abrasive grain and the workpiece.Scratching tests were conducted using a precisely engineered diamond indenter with a well-defined geometry.This setup was integrated within a Computer Numerical Control(CNC)grinding machine,ensuring high-precision control over kinematic parameters.A comprehensive suite of diagnostic tools,including a white light interferometer for topographical analysis,an optical microscope for morphological observation,and a high-resolution force sensor for dynamic measurement,was employed to characterize both the kinematic and dynamic aspects of the process.To systematically model and optimize the process,Response Surface Methodology(RSM)was implemented.This statistical technique enabled the development of robust mathematical models that correlated critical input parameters(e.g.,scratching speed,depth,feed rate)with two pivotal output responses:Material Removal Fraction(av)and the Scratch Force Coefficient(q).It is noteworthy that av was quantitatively characterized by measuring the cross-sectional area of the scratch groove at its deepest point,representing the volumetric material removal efficiency.Concurrently,the scratch force coefficient,a parameter indicative of the specific energy and friction during deformation,was derived from the measured normal force normalized by the projected contact area. The experimental results yield significant insights.A central finding is that the scratching linear speed exerts the most profound influence on both av and the scratch force coefficient.This dominance is attributed to a fundamental transition in the material response mechanism:at lower speeds,the predominant mode is plastic ploughing and side-flow,whereas at elevated speeds,the high strain rates promote a shift towards more efficient brittle chip formation and ejection.Furthermore,a critical observation is the consistent reduction in the scratch force coefficient with increasing scratching speed.This phenomenon strongly suggests that within the high-strain-rate deformation zone,the thermal softening effect—whereby frictional heat reduces the material's flow stress—becomes the dominant factor,overwhelming the competing effect of strain rate hardening.Through the application of RSM optimization algorithms,an optimal set of scratching parameters is identified that simultaneously maximizes av and minimizes the scratch force coefficient.Subsequent validation experiments confirm the model's efficacy,demonstrating a 2.3%enhancement in av and a 1.7%reduction in the scratch force coefficient compared with baseline pre-optimized conditions. In conclusion,this research provides seminal mechanistic insights into the material removal behavior of the 2214 aluminum alloy during grit interaction.It unequivocally reveals that the resultant surface formation during grinding is governed by a complex synergy between strain rate effects and the thermal-mechanical response of the material.The developed second-order regression model establishes a quantitative and predictive framework for anticipating material behavior under a wide spectrum of grinding conditions.The findings offer substantial theoretical significance for understanding high-strain-rate deformation in alloys and possess considerable practical value for optimizing industrial grinding processes,ultimately leading to improved surface integrity,extended tool life,and enhanced manufacturing efficiency for high-strength aluminum components in aerospace and other high-tech sectors.