【作者】 马跃；

【导师】 宗文俊；

【作者基本信息】 哈尔滨工业大学 ， 机械工程（专业学位）， 2021， 硕士

【摘要】 超精密加工指能加工出具有纳米级表面粗糙度和亚微米级几何形状精度表面的技术。用单晶金刚石刀具进行的切削过程通常被称为单点金刚石切削加工,是实现超精密加工的一种重要方式,它最初的发展主要集中在能源和国防相关需求的光学加工。如今,单点金刚石切削加工已经有了更广泛的应用,包括国防和商业应用领域的精密光学自由曲面制造,以及功能性表面的制造。微圆弧金刚石刀具是刀尖圆弧半径小于100μm的圆弧刃金刚石刀具,可以用来加工光学表面和微结构表面。用其加工光学表面可以减少加工残留,减轻衍射光学元件的遮挡效应。微结构表面是功能性表面的一种实现方式,常用于液晶显示器中的背光板,通过光学散射原理使画面更清晰。正弦微结构是波长10μm,幅值5μm的表面结构,波长越小,幅值越大,需要使用的刀尖圆弧半径越小。由于刀具刀尖圆弧半径很小,所以在加工过程中容易产生刀具磨损,从而导致加工出的工件的表面质量变差,达不到生产要求。刀具寿命主要和刀具磨损有关,当刀具磨损到一定的程度,加工出工件的表面质量达不到生产要求时,刀具即失效。在生产实践中,能够事先知道刀具的使用寿命,可以指导生产者何时换刀,提高生产效率。本文主要围绕微圆弧金刚石刀具的使用寿命进行系统的研究,具体包括以下几个方面:首先,研究了微圆弧金刚石刀具切削6061铝合金磨损形式和磨损机理。在PG3B行星型钻石刀具研磨机上制备了高质量的微圆弧金刚石刀具,使用制备好的刀具在哈工大自主研制的超精密四轴机床上进行切削6061铝合金实验,使刀具出现一定程度的磨损。使用扫描电镜观察刀具表面形貌,发现刀具磨损的形式主要是后刀面磨损。对刀具磨损部位进行X射线能谱分析,结果表明未发生扩散磨损。使用针尖增强激光共聚焦拉曼光谱系统对金刚石结构进行检测,未发现金刚石向石墨的相变;在本文实验条件下,刀具切削6061铝合金的磨损机理主要是机械磨损。其次,确定了微圆弧金刚石刀具切削6061铝合金使用寿命评价指标。在超精密四轴机床上使用制备好的刀具对6061铝合金工件端面进行车削,每车削一段距离,对工件面粗糙度Sa和刀具表面波纹度Wa进行测量。建立磨损模型,通过刀尖圆弧波纹度推导出了磨损带宽度和磨损体积。得到了切削路程、刀具刀尖圆弧波纹度、工件加工表面粗糙度、刀具磨损量(磨损带宽度和磨损体积)之间的关系,多维度地确定了刀具使用寿命评价指标。最后基于切削用量和刀具几何参数对微圆弧金刚石刀具使用寿命进行评价。基于切削用量,建立了三因素三水平的正交试验,得到了刀具使用寿命方程。根据该方程可以预测刀具寿命,并且得到了切削用量对使用寿命的影响规律。基于刀具的几何参数,得到了刀具前、后角对刀具使用寿命的影响规律。更多还原

【Abstract】 Ultra-precision machining refers to technologies that enable the machining of surfaces with nanometer-level surface roughness and sub-micron geometric shape accuracy.The cutting process with single crystal diamond tools,often referred to as single point diamond machining,is an important way to achieve ultra-precision machining,and its initial development was focused on optical machining for energy and defense-related needs.Today,single point diamond machining has a wider range of applications,including precision optical freeform fabrication for defense and commercial applications,as well as for functional surfaces.Micro-arc diamond tools are circular-edge diamond tools with tip radii less than 100 μm that can be used to machine optical and microstructured surfaces.Machining optical surfaces with them can reduce diffraction effects.Microstructured surfaces are a way to realize functional surfaces and are often used in backlight panels in LCDs to make the picture clearer by the principle of optical scattering.A sinusoidal microstructure is a surface structure with a wavelength of 10 μm and an amplitude of 5 μm.The smaller the wavelength and the larger the amplitude,the smaller the radius of the tool tip arc that needs to be used.Since the tool tip arc radius is very small,tool wear is easily generated during machining,which leads to poor surface quality of the machined workpiece and failure to meet production requirements.Tool life is mainly related to tool wear,when the tool wears to a certain extent,the surface quality of the machined workpiece does not meet the production requirements,the tool will fail.In the production practice,to know the tool life in advance,can guide the producer when to change the tool,improve production efficiency.This paper focuses on a systematic study of the service life of micro-arc diamond tools,which includes the following aspects.Firstly,the wear form and wear mechanism of micro-arc diamond tools cutting 6061 aluminum alloy are studied.Several high-quality micro-arc diamond tools were prepared on a PG3 B planetary diamond tool grinding machine,and the prepared tools were used to cut 6061 aluminum alloy on an ultra-precision four-axis machine tool developed by HIT for experiments,which caused a certain degree of tool wear.The surface morphology of the tool was observed by scanning electron microscope,and it was found that the tool wear was mainly in the form of rear tool surface wear.X-ray energy spectrum analysis of the tool wear area showed that no diffuse wear occurred.The diamond structure was examined using a pinpoint-enhanced laser confocal Raman spectroscopy system,and no phase change from diamond to graphite was found;under the experimental conditions of this paper,the wear mechanism of the tool cutting 6061 aluminum alloy is mainly chemical wear,and mechanical wear also exists.Secondly,the evaluation index of the service life of micro-arc diamond tools cutting 6061 aluminum alloy was determined.The prepared tools were used to turn the end face of 6061 aluminum alloy workpiece on an ultra-precision four-axis machine tool,and the workpiece face roughness Sa and tool surface ripple degree Wa were measured at each turning distance.A wear model was established,and the width of the wear zone and the wear volume were derived from the tool tip surface corrugation.The relationship between cutting distance,micro-arc diamond tool tip circular corrugation,workpiece surface roughness,and micro-arc tool wear(wear band width and wear volume)was obtained,and the tool life evaluation index was determined in a multi-dimensional way.Finally,the service life of micro-arc diamond tools was evaluated based on cutting dosage and tool geometry parameters.Based on the cutting dosage,a three-factor,three-level orthogonal test was established to obtain the tool life equation.Based on this equation,the tool life can be predicted and the effect of cutting dosage on the service life is obtained.Based on the geometric parameters of the tool,the influence law of the front and back angles of the tool on the tool life was obtained.更多还原