【作者】 张涛；

【导师】 王素娟； 姚洪辉；

【作者基本信息】 广东工业大学 ， 机械工程（专业学位）， 2022， 硕士

【摘要】 在21世纪,超精密加工已成为关键的先进制造技术之一,可实现亚微米形状精度和纳米表面粗糙度,其制造的微结构功能表面在电子,信息技术,光学,生物医学等领域的应用越来越广泛。目前,超精密切削和车削研究中,通常认为被加工表面为光滑表面,忽略了精加工的被加工表面存在微观不平度,即半精加工所形成的表面微观形貌。半精加工表面的微观不平度通常在微米级别,这对于微米级材料去除的超精密加工过程是不可忽略的,因为被加工表面微观不平度(下文简称微观不平度)的存在会影响实际切削厚度、改变微切削过程中的应力分布,从而影响其表面生成。而切削力是影响工件加工表面质量、切削热、切削振动和刀具磨损等的主要因素。因此,本课题研究微观不平度对超精密切削力的影响机制,建立超精密切削力动态预测模型,为进一步研究表面生成提供理论基础和指导。主要研究内容如下:(1)基于超精密切削机理和超精密切削力影响因素的研究,考虑切削参数、刀具参数、工件材料性能、最小切削厚度效应建立正交切削力模型。通过超精密正交切削实验使用遗传算法和有限元方法优化并确定模型参数。结果表明:切削深度对主切削力的影响大于推力;模型计算值与实验值的良好一致性验证了模型的准确性。(2)引入微观不平度研究超精密切削机理和材料去除机理,揭示微观不平度对微切削过程中切削厚度的影响,建立基于微观不平度的超精密切削力动态模型,并进行不同微观不平度表面的正交切削实验,采用功率谱密度(PSD)分析微观不平度表面和微沟槽表面的截面频率。实验结果与理论结果都表明微观不平度的存在不仅仅影响切削力还会影响表面生成,并且影响程度随着微观不平度表面的残留高度增加而变大;同时,对比切削力的测量结果与动态模型的预测结果,两者具有较好的一致性,验证了所建立的切削力动态模型的有效性。(3)综合考虑车削轨迹与微观不平度的关系,在已建立的正交切削力动态模型基础上,引入微观不平度与切削方向之间夹角(0°、45°、90°和135°)的影响,建立适用不同夹角的切削力动态模型。并进一步考虑车削半精加工微观不平度形貌、车削刀尖轨迹和刀具参数建立超精密车削力模型,最后通过改变半精加工参数提供不同表面微观形貌进行精加工实验。结果表明:车削过程中,随着微观不平度与切削方向夹角的变化,切削力按照一定的周期发生波动,同时变形区域应力分布呈现动态变化(270Mpa-350Mpa),影响瞬时切削力和工件表面生成,且在夹角为0°和90°时切削力的波动幅度达到最大约0.2N和最小0N;超精密车削力模型预测结果和实验结果的对比进一步验证了所建立模型的有效性和适用性。更多还原

【Abstract】 In the 21 st century,ultra-precision machining has become one of the key advanced manufacturing technologies,which can achieve sub-micron shape accuracy and nano surface roughness,and its manufactured microstructure functional surfaces are increasingly used in the fields of electronics,information technology,optics,biomedicine,etc.Currently,in ultraprecision cutting and turning research,the machined surface is usually considered as smooth surface,which ignores the micro-waviness of machined surface in finishing,i.e.,the surface micro topography formed by semi-finishing.The micro-waviness of semi-finished surface is usually at micron level,which is not negligible for the ultra-precision machining process of micron-level material removal,because the existence of the micro-waviness of machined surface(hereinafter referred to as micro-waviness)affects actual cutting thickness,changes the stress distribution in micro cutting process,thus affects its surface generation.Cutting force is the main factor affecting the workpiece surface quality,cutting heat,cutting vibration and tool wear.Therefore,this research investigates the mechanism of micro-waviness on the ultraprecision cutting force and establishes a dynamic prediction model of ultra-precision cutting force to provide a theoretical basis and guidance for further research on surface generation.The main studies are as follows:(1)Based on the study of ultra-precision cutting mechanism and the influence factors of ultra-precision cutting force,an orthogonal cutting force model is established considering cutting parameters,tool parameters,workpiece material properties,and minimum cutting thickness effect.Ultra-precision orthogonal cutting experiments are conducted to determine and optimize model parameters using genetic algorithm and finite element method.The results show that the influence of depth of cut on the main cutting force is greater than the thrust force;the accuracy of the model was verified by the good consistency between the calculated and experimental values of the model.(2)Micro-waviness is introduced to study the ultra-precision cutting mechanism and material removal mechanism,and the influence of micro-waviness on the cutting thickness in the micro-cutting process is revealed to establish a dynamic model of ultra-precision cutting force based on micro-waviness.Orthogonal cutting experiments with different microwaviness surfaces are conducted to analyze the cross-sectional frequencies of micro-waviness surfaces and micro-groove surfaces using power spectral density(PSD).The experimental and theoretical results show that the existence of micro-unevenness not only affects the cutting force but also affects the surface generation,and the degree of influence becomes larger as the residual height of the micro-uneven surface increases;meanwhile,the comparison of the cutting force measurement results and the prediction results of the dynamic model shows a good agreement,which verifies the validity of the established dynamic model of cutting force.(3)Considering the relationship between turning trajectory and micro-waviness,on the basis of the established orthogonal cutting force dynamic model,the influence of the angle(0°,45°,90° and 135°)between micro-waviness and cutting direction is introduced to establish the dynamic model of cutting force which is suitable for different angles,and further consider micro-waviness topography of turning semi-finishing,tool tip turning trajectory and tool parameters to establish ultra-precision turning force model.Finally,the finishing experiments are carried out by changing the semi-finishing parameters to provide different micro-waviness surface.The results show that during the turning process,with the change of micro-waviness and the angle of cutting direction,the cutting force fluctuates according to a certain period while the stress distribution in the deformation area shows dynamic changes(270Mpa-350Mpa),which affects the instantaneous cutting force and workpiece surface generation,and the fluctuation of cutting force reaches a maximum of about 0.2N and a minimum of 0N at the angle of 0° and 90°;the comparison of the predicted results of the ultra-precision turning force model and the experimental results further verifies the validity and applicability of the established model.更多还原