石英玻璃旋转超声铣削表面质量研究

探索了高频旋转超声铣削石英玻璃的工艺规律与材料去除机理,检测分析了加工表面粗糙度与表面形貌,借助Matlab平台建模仿真了进给速度和主轴转速对磨粒运动轨迹的影响规律,研究了进给速度、主轴转速、切削宽度以及切削深度对加工表面质量的影响规律与机理。进给速度增大会导致刀具上的单颗金刚石磨粒的切削速度增大,参与切削的摆线平面投影运动轨迹变长,使表面粗糙度随进给速度增加先增大后减小;表面粗糙度值随主轴转速的增大总体上呈现出先减小后增大的趋势,主轴转速为3 000 r/min时铣削表面粗糙度最小;表面粗糙度值随切削宽度增大先增大后减小,切削宽度直接决定相邻刀具路径对应加工区域重叠范围,进而产生不同的磨粒划刻加工叠加效果;随切削深度增大,表面粗糙度值呈现出先增大后减小再增大的趋势,铣削过程中超声振动与切削深度配合产生的近成形表面材料去除模式对表面质量具有关键性作用。研究工作可为石英玻璃旋转超声铣削加工提供一定的工艺基础。     

陶瓷基复合材料旋转超声加工特性研究

针对陶瓷基复合材料加工方法的优势和不足,采用旋转超声加工方法对陶瓷基复合材料进行加工,完成旋转超声加工方法与传统加工方法的对比试验。试验表明,钻削力随着主轴转速的增加而减小,随进给速度的增加而增加;扭矩随着主轴钻速的增加而减小,随进给速度的增加而增加;工件表面粗糙度随着主轴转速和进给速度的增加先降低后增加。超声加工方法获得的钻削力、扭矩和表面粗糙度均优于传统加工方法。     

高体积分数SiCp/Al复合材料旋转超声铣磨加工的试验研究

由于大量高硬度增强相SiC颗粒的存在,高体积分数铝基碳化硅（SiCp/Al）复合材料的机械加工十分困难。旋转超声加工被认为是加工这种材料的有效方法。通过超声辅助划痕试验,分析高体积分数SiCp/Al复合材料旋转超声铣磨加工的材料去除机理。在超声振动的作用下,材料中铝基体发生塑性变形,其表面得到夯实;SiC增强相被锤击成细小的颗粒而发生脱落,形成较大的空洞。由于材料加工的缺陷大多产生于SiC颗粒的去除过程中,SiC颗粒的去除方式对加工表面的质量起着决定性的作用,选择合适的工艺参数可以有效提高加工表面质量。旋转超声加工工艺特征试验表明,超声振动可有效降低切削力;主轴转速对轴向切削力的影响最大,其次是进给速度,切削深度对轴向切削力的影响较小;另外主轴转速对表面质量的影响效果也最大,并随主轴转速的增大表面粗糙度增大。因此在加工过程中,可以适当加大切削深度,在保证加工质量的基础上,选择较大的进给速度,在保证刀具寿命的前提下,选择合适的主轴转速,以获得较优的加工表面质量和加工效率。     

侧铣削参数对TC4钛合金表面粗糙度及材料去除率的影响

侧铣采用铣刀侧刃对工件进行铣削,是一种重要的数控加工方式,常用于直纹面零件.针对TC4钛合金的侧铣削加工,开展了主轴转速、进给速度、切削深度、切削宽度的四因素三水平正交试验,分析侧铣削参数对切削力、表面粗糙度及材料去除率的影响.试验结果表明,切削深度和主轴转速对切削力和表面粗糙度的影响较大,进给速度次之,切削宽度最小.切削深度和切削宽度的增大会显著提高材料去除率,在主轴转速为600r/min,进给速度为220mm/min,切削深度为5mm,切削宽度为0.4mm时,侧铣TC4钛合金的表面粗糙度质量较好且材料去除率较大.     

CFRP/铝合金叠层构件旋转超声钻削温度研究

碳纤维复合材料(CFRP)/铝合金叠层的钻孔机理不同于单层材料钻孔,铝合金切屑在排出孔外过程中因切削温度过高会烧伤CFRP孔壁。为了改善CFRP叠层构件加工质量,将旋转超声钻削技术(RUM)引入到该材料的加工中。针对叠层构件钻削温度过高的问题,开展了旋转超声钻削试验研究,阐明了主轴转速、进给速度及超声振幅对钻削温度的影响规律。采用多元回归分析,分别建立了CFRP和铝合金的钻削温度指数预测模型。通过对比预测值和试验值,验证了钻削温度模型构建的合理性和有效性。     

CFRP/Ti叠层材料的钻削力变化趋势及振动特性

为了研究钻削参数对CFRP/Ti叠层材料钻削力的影响及钻削过程中的振动特性,采用正交试验的方法对叠层材料进行了一体化钻削试验。采用测力仪对加工过程中的钻削力进行测量,并通过对钻削力的分析,研究了钻削过程中的振动特性。结果表明,扭矩和轴向力随主轴转速升高而减小,随进给速度的升高而增大,且进给速度对钻削力的影响强于主轴转速对其的影响。加工过程中取较高的主轴转速,较低的进给速度将保证孔的加工质量。在CFRP/Ti叠层材料加工过程中,加工至两材料接触面的位置时,存在剧烈的切削振动现象。     

碳纤维复合材料超声磨削工艺的研究

在总结国内外大量文献资料的基础上,利用自行研制的超声振动系统对碳纤维复合材料进行了磨削试验,研究不同加工参数对切削力和工件表面质量的影响,并对超声磨削机理进行了分析。结果表明:随着主轴转速的加快,切削力和表面粗糙度值减小;随着切削深度的增大或进给速度的加快,切削力和表面粗糙度值增大。与传统磨削加工相比,在加工参数相同的条件下,超声辅助加工时工件所受的切削力和表面粗糙度值更小。     

304不锈钢的超声振动辅助微孔钻削试验研究

通过304不锈钢的100μm微孔超声辅助钻削试验,研究了超声振动辅助钻削的理论未变形钻削厚度,钻削轴向力与加工参数的关系,孔壁的表面质量,微孔入口处的毛刺以及加工后钻头刃部的状态,结果表明:超声振动辅助钻削在入钻后为连续切削;超声振动辅助可以明显改善微孔表面质量和入口处毛刺的尺寸,减小钻头刃部积屑馏的形成;钻削轴向力随进给速度和单次钻削深度的增加而增大,随主轴转速的升高而减小。     

TC18钛合金车削加工的切削力和表面粗糙度

采用正交试验法对TC18钛合金进行了车削试验,使用直观分析法、经验模型分析法和极差分析法研究了主轴转速、进给深度和切削深度对切削力和表面粗糙度的影响。结果表明:和进给深度、主轴转速相比,切削深度对切削力的影响最大,随着切削深度的增加切削力不断增大;进给深度对表面粗糙度的影响最大,切削深度的影响次之,主轴转速的影响最小;在切削力和表面粗糙度的指数经验模型中,拟合程度较高的为主切削力(Fz)的参数模型,且显著程度相对较高。     

基于刀具-工件接触率的固结磨粒旋转超声加工的工具受力分析

在旋转超声加工中,刀具磨损往往决定着工件的加工质量和刀具的寿命。考虑到刀具的磨损主要与刀具受力有关,因此引入刀具-工件接触率概念从理论上解释了主轴转速、进给速度和振幅对旋转超声加工中刀具受力的影响规律,理论分析发现主轴转速,振幅的增大以及进给速度的减小可以降低主轴切削力,利用有限元仿真软件DEFORM对单颗磨粒的受力情况进行了仿真,得到的仿真结果验证了刀具-工件接触率概念解释结果的正确性,同时也证明了单颗粒磨粒DEFORM仿真的可行性。     

Mathematical model for cutting force in rotary ultrasonic face milling of brittle materials

Rotary ultrasonic machining of brittle materials, such as glass, ceramics, silicon, and sapphire, has been explored in a large number of experimental and theoretical investigations. Mechanistic models have been developed to predict the material removal rate or cutting force in the rotary ultrasonic machining of brittle materials. However, most merely describe the rotary ultrasonic machining process of drilling holes in brittle materials. There are no reports on the development of a cutting force model for flat surface rotary ultrasonic machining, i.e., rotary ultrasonic face milling. This paper presents a mathematical model for the cutting force in the rotary ultrasonic face milling of brittle materials under the assumption that brittle fracture removal is the primary mode of material removal. Verification experiments are conducted for the developed cutting force model and show that the trends of input variables for the cutting force agree well with the trends of the developed cutting force model. The developed cutting force model can be applied to evaluate the cutting force in the rotary ultrasonic face milling of brittle materials.     

Optimum design of cam-roller follower mechanism using a new evolutionary algorithm

Selection of tooling to perform specific operations like drilling and milling on ceramic materials using rotary ultrasonic machining process is an important aspect to meet stringent dimensions on workpiece as well as intended performance of tool. This phenomenon is more critical for micro rotary ultrasonic machining. In the present study, an effort was made to do micro drilling operation of Ø0.3 mm tool with varying geometry, having different wall thicknesses and abrasive grain sizes using design of experiments. The effect of tool-based parameters like grain size and wall thickness has been studied on axial cutting force, radial cutting force, tool wear, edge chipping area and taper. After examining axial and radial cutting forces, it has been concluded that lower wall thickness (80 μm) tool is good for drilling operation; and higher wall thickness (100 μm) tool is good for milling operation under same material removal rate conditions. It has been also investigated that lower wall thickness (80 μm) tool has less edge chipping area and less taper and can impart high drilling depth as compared to higher wall thickness (100 and 150 μm) tool. It is also concluded that lesser grain size (15 μm) tools are advantageous in terms of edge chipping area and cutting force for drilling and milling operations as compared to higher grain size (30, 35 and 45 μm) tool at constant material removal rate. Higher grain size tools have been broken at 1.13 mm³/h material removal rate conditions due to bad profile accuracy. But higher grain size tools have worked fairly well at less material removal rate condition. Higher grain size tools produced less wear. Tool wear was found minimum in higher wall thickness (100 μm) tool having higher abrasive grain size (30 μm). Using inferred results, Ø0.3 mm drilling experiments have been carried out on six aerospace ceramic materials. Also, groove of 0.5 mm size using Ø0.3 mm optimised tool has been successfully carried out in sintered SiC.     

An analytical model of rotary ultrasonic milling

Rotary ultrasonic machining is currently being used as a manufacturing method for advanced ceramic materials, but its complexity has hindered its acceptance in industry. For this technology to gain wider acceptance, it must first be scientifically better understood. The majority of published rotary ultrasonic machining (RUM) papers studied the effect of RUM process parameters on machining performance and removal mechanisms for drilling of circular holes. In industries such as aerospace, the production of advanced turbine components requires machining of complex 3D features using milling strategies. The objective of this paper will be to present a new physical model based on rotary ultrasonic milling which will help provide a better scientific understanding of the process. This will be accomplished by first modeling the macro kinematics between the tool and material followed by the modeling of micro kinematics between the individual diamond grains and the material. In addition, a force model for predicting machining process forces will also be introduced and validated based on a set of experiments. The physical models will help determine the relationships between input parameters, cutting parameters, and process output parameters for rotary ultrasonic milling.     

超声振动钻削SiC颗粒增强铝基复合材料时的切削力研究

采用超声振动钻削的方法对金属基复合材料进行孔加工。在自行研制的超声钻削设备的基础上使用不同材质的硬质合金麻花钻,对不同含量的SiC颗粒增强铝基复合材料(SiCp/Al)进行了普通钻削与超声振动钻削的对比试验,并分析比较了加工中切削力的变化规律。试验表明,超声振动钻削可以降低切削力,在一定程度上改善钻削机理。     

Investigation on thrust force in rotary ultrasonic drilling of CFRP using Brad drill

Abstract

The carbon fiber reinforced plastic (CFRP) has been widely used in manufacturing industry due to its excellent mechanical and physical properties. Brad drill, as a representative of new-type structural drills, is applied in processing of CFRP. Meantime, rotary ultrasonic drilling (RUD) is regarded as a superior method for machining composite materials, due to its outstanding performance in lowering thrust force and improving processing quality. However, there are few reports about RUD with Brad drill in CFRP drilling. In this study, the theoretical model of thrust force for RUD of CFRP using Brad drill is developed. The dynamic uncut chip thickness and average uncut chip thickness in RUD are obtained based on kinematic characteristics analysis. After that, the structure of Brad drill is analyzed and thrust force of the cutting lip is molded. Then a theoretical model is proposed to predict the thrust force. Finally, pilot experiments are conducted for the model verification. Experimental results show that the trends of thrust force agree well with the thrust force model and the prediction error is less than 10%.     

Investigation on the bonding strength patterns of ultrasonic vibration tools and influence on working performance during rotary ultrasonic grinding

During rotary ultrasonic grinding process, working performance of ultrasonic vibration tools varies according to the bonding patterns between diamond grit and bond. In order to understand the influence of ultrasonic vibration tools on working performance, bonding patterns and bonding strength of ceramic-bonded, iron-bonded, and bronze-bonded tools were investigated. Influence of bonding strength on cutting force, tool wear, surface quality, and edge breakout were studied, coupled with the characteristics of ultrasonic vibration tools. The results show that cutting force in Z axis and tool wear reduce with the increase of bonding strength while the surface quality and edge breakout become worse.     

振幅对超声振动钻削力的影响研究

超声复合机械加工机理与普通切削加工有本质的区别。主要表现在超声加工是一种脉冲式切削加工,对延长刀具寿命、提高表面加工质量、改善刀具切削性能有很大意义。其本身的优良性能已经被国内外专家学者所认可。但是超声振动振幅的大小对孔的钻削质量和刀具寿命的影响非常重要。文中自行设计了一套超声复合钻削装置,且对超声钻削加工装置设计中存在的问题和关键工艺进行了分析,并对不同振幅对钻削力与扭矩的影响进行了对比研究。实验结果对超声加工有一定的指导作用。     

钛合金高速旋转超声椭圆振动侧铣削切屑特征和刀具磨损研究

难加工材料钛合金在采用传统铣削方式时,随着切削速度的增加,切削力和切削温度都迅速增加,使得切削条件恶化并加速刀具磨损,从而导致刀具过早失效。将超声椭圆振动加工技术引入到高速铣削中,进行了钛合金高速旋转超声椭圆振动侧铣削试验。从切屑特征以及刀具后刀面磨损两个方面研究了高速超声椭圆振动铣削参数匹配对钛合金加工的影响。首先基于高速超声椭圆振动铣削过程中刀具-工件的运动学特点推导出高速超声椭圆振动铣削加工参数与振动参数间的匹配关系,然后利用本实验室自行研制的超声椭圆振动铣削装置进行了不同参数匹配关系下的验证性切削试验。试验结果表明：合理的参数匹配使得超声椭圆振动铣削在高速条件下依然能够实现分离型断续切削加工。相比普通铣削加工,分离型的高速超声椭圆振动铣削能够获得更加微细的切屑,切削热能够被及时地带走;良好的切削条件使得刀具的后刀面磨损均匀而缓慢,从而延长刀具的使用寿命;高速超声椭圆振动铣削能够有效地提高生产效率。     

旋转超声磨削加工中刀具结合剂类型与加工性能的关系

实验分析了硬脆材料旋转超声磨削过程中刀具结合剂类型对加工性能的影响以便提高加工精度和加工表面的完整性.首先,采用能谱分析研究了铁基、陶瓷基和青铜基3种超声振动刀具中结合剂与金刚石颗粒的把持形式,并根据相同加工工艺条件下刀具磨损形式确定了把持力大小.然后,结合超声振动刀具特性,通过旋转超声磨削加工实验研究刀具结合剂类型与切削力、刀具磨损量、加工表面完整性的关系,并对实验结果进行了分析.实验结果表明:相对于陶瓷基和青铜基结合剂超声振动刀具,铁基结合剂超声振动刀具把持力最大,Z轴切削力平均值最小(为46.8 N);加工18 000 mm3材料后,刀具轴向磨损量最小(为0.1 mm);而陶瓷基结合剂超声振动刀具加工表面质量最好,表面粗糙度最大值为21.79 μm.结果证实铁基超声振动刀具适用于粗加工,陶瓷基超声振动刀具则适用于精加工.     

Experimental investigation of surface and geometrical characteristics of rotary ultrasonic drilling of soda glass

Edge-chipping, surface roughness and dimensional accuracy are crucial quality aspects of drilled holes in hard-to-cut material such as glass, ceramics and carbon fiber reinforced plastics. In this article, an experimental study was conducted to investigate the quality measures of holes produced by rotary ultrasonic drilling (RUD) and conventional drilling. Edge-chipping width at tool exit side, the surface roughness (Ra and Rz), out-of-roundness, cylindricity error and hole conicity were the main responses when drilling soda glass using diamond abrasive tools and a cutting fluid. Statistically designed experiments were carried out for rotary ultrasonic and conventional drilling (CD) at two levels of tool feed rate (0.6 and 6?mm/min), spindle speed (3,000 and 8,000?rpm) and tool particles-concentration. Analysis of variance was used to define the significant factors and their interactions and build models for predicting the responses. The results showed that reducing the chipping, surface roughness and roundness error. The normal tool concentration showed a substantial effect in improving the surface quality and reducing the hole-geometrical errors.