细长轴的尺寸误差补偿研究

为了减小细长轴加工中产生的尺寸误差,建立了细长轴在径向力作用下的力学模型、车刀受切削热时的热变形模型,推导了一个与细长轴参数相关的尺寸误差公式。介绍了一种细长轴尺寸误差补偿法,将该误差补偿法与让刀量尺寸误差公式相结合,运用于细长轴数控车削实验。实验结果表明,通过该补偿法能显著减小加工尺寸误差,提高了细长轴的加工精度。     

七轴并联机床加工汽轮机叶片技术及其工作空间干涉检查研究

并联机构自从1980年就应用于机器人作业,但是第一台并联机床却出现在14年以后.目前,研究并联机床在铣削加工能力方面的文献很少,文章着力于研究并联机床在铣削加工尤其是加工自由曲面的能力.文中描述了并联机床在铣削加工汽轮机叶片的实际应用. 研究了基于UG CAD/CAM铣削汽轮机叶片技术,并考虑了并联机床粗加工和半精加工的效率和精加工的精度控制.UG CAM产生的刀具轨迹文件,不能直接被并联机床数控系统识别,所以必须进行后置处理,文中提出了面向七轴并联机床的刀具轨迹后置处理技术,以生成并联机床CNC系统可读的加工代码.最后为了避免机床在加工中的干涉,针对七轴并联机床的特性,提出了快速工作空间检查算法.     

叶轮在MasterCAM软件中的轨迹设置与VERICUT优化加工

分析叶轮五轴数控加工工艺和加工内容,应用MasterCAM X6软件生成叶轮五轴粗加工轨迹、叶轮扩槽及轮毂精加工轨迹、叶片精加工轨迹。在VERICUT仿真软件中进行机床设置、添加刀具库、添加毛坯、添加叶轮加工数控程序、设置碰撞及干涉颜色显示、程序优化等操作,经仿真得到无碰撞、无过切的五轴叶轮。     

锥形螺旋叶片参数化建模与五轴刀路生成

根据锥形螺旋叶片的形成,推导出锥形等螺距螺旋线参数建模所用公式,应用CAD软件绘制出螺旋线,通过单截面线双导动线“扫掠”的方法生成螺旋泵所需的螺旋曲面。对叶片进行加工工艺分析,应用多轴加工软件HyperMILL进行五轴加工工艺规划,选择合适的五轴加工机床、叶片五轴数控加工方法、加工刀具、装夹定位方式、设定五轴高速加工工艺参数,生成螺旋叶片粗加工和精加工的五轴高速加工刀具路径和机床加工代码,有效地减少了加工步骤,提高了螺旋叶片的加工表面质量和加工效率。     

细长套筒零件加工工艺优化

为提高加工效率,设计车床尾部卡盘,一次装夹完成外圆及端面加工。针对细长内孔,设计钻镗结合刀具,实现粗加工和精加工一次完成,减少转序成本和时间,并保证了加工精度。     

细长轴的双刀车削加工方法

为了解决细长轴零件由于长径比大、刚性差,受切削力作用易产生弯曲变形,严重影响加工质量的问题,提出了双车刀同时切削的方法,运用梁理论建立模型,采用有限元法分析了细长轴的横向位移;经实践得出,双刀车削方法能有效的提高加工精度和车削工作效率,降低单位能耗;并介绍了刀具安装难点与解决方法.     

基于平底铣刀的螺旋锥齿轮齿面加工轨迹规划

针对当前螺旋锥齿轮采用专用机床及刀盘加工时，设备价格高昂且通用性不强的问题，提出采用平底铣刀在通用五轴机床上进行螺旋锥齿轮加工。通过齿轮啮合原理和包络加工原理构建螺旋锥齿轮参数化模型，规划出采用平底铣刀端铣的粗加工轨迹，以及采用平底铣刀侧铣凹凸两侧面的半精加工及精加工轨迹，并对获得的刀具轨迹进行齿面加工仿真。结果表明加工表面相对均匀，能够实现在五轴机床上加工螺旋锥齿轮，提高了大规格或单件小批量齿轮加工的通用性和经济性。     

双电主轴双刀车削车铣复合中心的切削振动特征分析

由于车铣复合中心对细长轴的车削加工方法采用的是双电主轴夹持,双刀对置车削.通过对车铣复合中心的切削测试,得出车锐复合中心双电主轴的旋转特性,单刀车削加工特征以及双刀对置加工特性.测试加工状态下的刀具和工件的振动特性,为加工参数的确定以及机床精度的调整和改善提供参考.     

五轴数控旋风铣削机床加工螺纹的误差补偿研究

基于小误差运动假设,分析了五轴旋风铣削机床误差运动和补偿运动间的相互关系,建立了考虑工件热胀冷缩时进行其空间5个误差量计算的数学模型,为五轴旋风铣床用于螺纹精加工时的误差实时插补提供了理论基础,也是建立考虑工件热变时通用五轴旋风铣床误差实时插补数学模型及以旋风铣削精加工质量为目标函数、约束于多变量的数学模型的第一步.     

非刚性轴组合加工方法研究

介绍了非刚性轴切削变形组合加工原理，即采用切刀刃和轴表面冷态塑性变形来保证非刚性轴的精度，设计了车削组合加工装置，建立了组合加工数学模型，通过实验得出了影响加工误差的因素。     

长轴表面滚压加工装置的设计

由于长轴的刚性差、热变形大等原因,磨削长轴过程中极易产生弯曲和振动,以至于无法得到理想的表面粗糙度和形状精度.采用滚压加工的方法对长轴表面进行光整加工,提出长轴滚压装置的结构方案,滚轮对称地布置,使被加工长轴的受力更加均匀,克服了传统磨削加工的缺点.设计滚压装置、滚压工具和合理的滚轮的具体结构,并进一步分析滚轮对表面粗...     

A comprehensive dynamic cutting force model for chatter prediction in turning

This paper presents a model of the dynamic cutting force process for the three-dimensional or oblique turning operation. To obtain dynamic force predictions, the mechanistic force model is linked to a tool–workpiece vibration model. Particular attention was paid to the inclusion of the cross-coupling between radial and axial vibrations in the force model. The inclusion of this cross-coupling facilitates prediction of the unstable–stable chatter phenomenon which usually occurs in certain cases of finish turning due to process non-linearity. The dynamic force model developed was incorporated into a computer program to obtain time-saving chatter predictions. Experimental tests were performed on AISI 4140 steel workpieces to justify the chatter predictions of the dynamic cutting process model in both the finishing and roughing regimes. Experimental results corroborate the unstable–stable chatter predictions of the model for different cases of finish machining. In addition, experimental results also confirmed the accuracy of chatter predictions for various cases of rough turning.     

State of the art in hard turning

Hard turning is gaining grounds for machining hardened steels as it has several benefits over grinding. There are several issues, which should be understood and dealt with, to achieve successful performance of the process. Researchers have worked upon several aspects related to hard turning. The present work is an effort to review some of these works and to understand the key issues related to process performance. The review shows that the type of tool material, cutting edge geometry and cutting parameters affect the process efficiencies in terms of tool forces, surface integrities integrity, and white layer. Adequate machine rigidity is a must essential to minimize the process inaccuracies. Also moreover, for finish hard turning, where the depth of cut is less than the nose radius of the tool, the forces deviate from the conventional trends as the radial force component is the maximum and axial force component becomes minimum. The present work finally lists down certain areas that can be taken up for further research in hard turning.     

A fast tool servo design for precision turning of shafts on conventional CNC lathes

A technique for precision turning of shafts on conventional CNC turning centers is presented. The shaft is semi-turned on a conventional CNC lathe. The precision finish turning operation is delivered by a piezoelectric based fast tool servo which is mounted on the same CNC lathe's turret. The precision tool tip motion is delivered by a proposed sliding mode controller which is robust to changes in the cutting process and hysteresis in the piezo actuator. Sliding mode controller is also quick to compensate the cutting force disturbances, and keeps the tool tip at the desired location within the displacement measurement sensor resolution (±0.1 μm). The fast tool servo system is packaged in a PC, and its effectiveness is demonstrated on a bearing location turning.     

偏心轴的磨削及配重平衡

采用在重型卧车上粗加工和半精加工,在磨床上精加工的办法加工偏心轴。用数控镗床定心解决了定心精度问题,用固定配重A和可调整配重块B解决了配重平衡问题。     

自动冷镦机离合器制动器结构优化设计

介绍改进冷镦机离合器制动器的安装位置和密封。     

叶轮转轴断裂分析

叶轮转轴在工作中断裂,通过对故障转轴及其断口进行宏微观检查、砂轮越程槽圆角半径测量、金相组织观察、化学成分分析、力学性能测试等,对断裂原因进行分析,并对转轴相关零组件进行完整性分析。结果表明：转轴断口性质为疲劳断裂,裂纹源在砂轮越程槽底部;叶轮偏载是导致转轴发生疲劳断裂的主要原因;转轴的强度和硬度偏高,对裂纹萌生和扩展有较大的促进作用;建议转轴调质前粗车台阶或调整热处理制度,改善裂纹源处组织,提高转轴疲劳寿命。     

Investigation of machining performance in high-pressure jet assisted turning of Inconel 718: An experimental study

This paper investigates the application of the high-pressure jet assistance (HPJA) in rough turning of Inconel 718 with coated carbide tools. The region of operability, which sets the boundaries of the process parameters, has been experimentally determined using the tool–material pair (TMP) methodology. The assessment of HPJA machining performance is based on response surface methodology (RSM), which integrates a design of experiment (DOE) and a regression modelling technique for fitting a model to experimental. This leads to a new insight into the influence of the cutting process on chip breakability, cutting forces, contact length, surface finish and tool temperature, which are the key machining performance measures.     

Turning of advanced Ni based alloys obtained via powder metallurgy route

Nickel based alloys (RR_X) manufactured via powder route are considered the next generation materials that can offer increased efficiency of gas turbine engines. Their chemistry and mechanical properties indicate even lower machinability than the current disc alloys. The paper reports on specifics when rough and finish turning these new Ni based alloys. Tool life, surface finish, workpiece surface integrity and residual stress distributions have been used as multi-objective quality criteria to assess the capability of shaping RR_X alloys. The optimised cutting parameters/route was then employed to produce surfaces in low cycle fatigue samples to demonstrate machining capability to Airworthiness Authorities.     

基于Pro/E的小带冠导叶片数控加工研究与实现

基于Pro/E研究小带冠导叶片多轴数控加工方法。分析其工艺过程,得到叶片粗、精加工时刀具路径和加工效果图。结果表明,该方法具有一定工程实用价值。