基于无瞬心包络的微细铣刀螺旋槽刃磨分析*

螺旋沟槽属于复杂的空间螺旋面,砂轮与刀具的相对运动复杂,在微细立铣刀的制造过程中耗时最长、难度最大,精确、高效加工螺旋沟槽成为微细铣刀制造过程亟须解决的关键问题之一。基于无瞬心包络原理研究了微细铣刀螺旋沟槽的刃磨过程,提出一种微细螺旋铣刀轴向型线的计算模型,该模型避免了利用接触公法线求解时,因砂轮截形上的奇点和圆滑二次曲线导致无法求解的情况,计算过程与求解简单,适用于对砂轮廓形复杂时刃磨求解。在所建模型基础上分析了砂轮形状和加工参数对螺旋槽型形状的影响,以及砂轮摆角和前刀面宽度对径向前角的影响。通过刃磨验证了模型与分析的正确性,试验证明实际加工的微细铣刀沟槽截形与包络计算的沟槽型线几何形状参数吻合良好。     

钢珠对磁力抛光工艺影响规律的实验研究

磁力抛光机利用磁场的力量,引导磨具(磁针)做快速旋转运动而抛光工件。为了使磁力抛光机对45钢轴的抛光效果及效率更佳,从理论上分析了磁力抛光的工作原理、磁力抛光过程中磨具的运动方式和影响磁力抛光效率的因素,提出加入钢珠会提升抛光效果及效率,并对45钢轴进行磁力抛光实验。实验结果表明:加工频率、磁针长度均对抛光效果及效率有不同程度的影响;加入钢珠后,抛光效果及效率都有提升;最佳磁针与钢珠的质量混合比例为1∶3。     

Study on improving the trajectory to elevate the surface quality of plane magnetic abrasive finishing

This paper aims to improve the surface integrity and surface homogeneity with various trajectories by a newly self-designed experiment device. In the experiments, three kinds of polishing trajectories were studied with attached revolution motion to magnetic abrasive brush (MAB) based on conventional magnetic abrasive finishing (MAF) process. The surface roughness, the cross-sectional shape, and the 3D micro-morphology were chosen as the response variables to explore the feasibility and benefits of the proposed improving polishing method. The results show that the plane homogeneity and surface quality improved in varying degrees after improving the polishing trajectory. In addition, combining MAF theory to analyze related reasons, the trajectory expression of the magnetic abrasive particles (MAPs) was established and was simulated by Graph software. The theoretical analysis is consistent with the experimental results which indicated that analysis of polishing trajectory can be used to predict polishing results. Thus, it is feasible to plan polishing trajectory reasonable according to workpiece profile and surface quality requirements.     

平面磁力研磨轨迹的研究与分析

利用自行设计的试验装置,改善了磁力刷的研磨轨迹。结果表明:改善磁力刷研磨轨迹后,不仅可以减小表面粗糙度值、提高平面精度,还改善了研磨截面微观形状均匀性。另外,可通过采取理论分析的方法对研磨效果进行预测。     

微通道反应器沟槽底面的磨料水射流抛光研究

针对燃料电池微通道反应器的沟槽底面抛光技术难题,开展磨料水射流沟槽抛光仿真与试验研究.采用FLUENT软件,对不同工艺参数下沟槽底部剪切力分布进行了数值模拟;根据仿真结果进行316L不锈钢材料的单沟槽抛光工艺试验,检测分析不同抛光参数下单沟槽底面形貌、材料去除率以及表面粗糙度的变化规律;根据单沟槽底面几何精度和表面粗糙...     

螺旋槽砂轮磨削非光滑表面形貌特征仿真

非光滑表面在机械摩擦磨损的过程中具有减少摩擦和降低能耗的作用。为获得平面工件的非光滑表面,采用磨削加工方式。将砂轮表面修整成螺旋槽形状,并建立螺旋槽砂轮表面的数学模型,根据磨削运动学建立磨粒运动轨迹方程,通过MATLAB仿真研究不同加工参数下磨削表面的形貌特征。     

基于钛合金磨钻过程中不同槽型磨具的仿真研究

介绍了CBN超硬磨具磨钻小孔的成形机理,分析了磨钻过程中出现的问题,在已有实验的基础上对磨具结构进一步优化设计,针对不同深度直槽型的刀具进行仿真实验,得出最适槽深,并且与螺旋槽刀具进行比较,进而探索出一种更适合在高速磨钻下应用的磨具。     

Electrorheological fluid-assisted ultra-precision polishing for small three-dimensional parts

This paper deals with a new machining method (electrorheological fluid-assisted polishing) for small three-dimensional parts such as micro-aspherical lens, die and mirror. The behavior of electrorheological particles and abrasive particles in the vicinity of the tip of the tool was observed by CCD microscope, and the electric field strength, electrode shape, and type of abrasive particles were investigated. It was clear that the electrorheological effect facilitates collection of the abrasive particles at the tool tip, even while the tool is rotating. Then, electrorheological fluid-assisted micro-aspherical generator system was developed, which is capable of micro-grinding and micro-polishing on the same machine. The system demonstrated the excellent polishing performance of small area after grinding process.     

斜圆柱结构的新型微细球端铣刀的设计与制造

针对微细切削刀具的特点与应用需求,设计一种斜圆柱结构的新型微细球端铣刀,将铣刀球端刀刃复杂的空间曲线转化为易加工的平面曲线。根据所设计铣刀的几何结构特征,从制造工艺方面进行刀具结构的调整,分析刀具的刃磨成形原理,并在微细刀具数控刃磨机上完成该刀具的制作。通过与传统螺旋槽球端铣刀和椭圆柱刃型球端铣刀的切削性能对比试验,研究所设计刀具的切削性能。试验结果表明,所设计的微细球端立铣刀在显著降低刀具制备难度的同时,具有较高的切削刃强度,能够满足硬脆性材料的微细切削要求。     

Design and NC Machining of Concave-Arc Ball-End Milling Cutters

The paper presents a geometric modelling approach for the precision design and NC machining of a concave-arc ball-end milling (CABEM) cutter which is an important tool for mould-making industries. This paper presents systematic models of the cutting edge, helical groove, and grinding wheel design for the NC machining of a CABEM cutter. Both the normal to the revolving axis and the tangent to the groove, are used to derive the required precision sectional profiles of the grinding wheel. In compliance with the maximal sectional radius of the cutter, the profile of the groove section and both the radial and axial cutting speeds of the grinding wheel are computed in sequence. Using the computer simulation results of the groove actually obtained, this paper proposes a method to resolve the problems of the residual revolving surface and the narrow cutting edge strip. This paper is intended to serve as a reference for the design and NC machining of cutters of this type .     

A manufacturing model of helical groove on rotary burr and a universal post processing method

A systematic machining theory and precision method to determine cutter location in a grinding system is presented for rotary burr. First, the helical cutting edge on various kinds of revolving surfaces is built. Then, based on the geometry model of the helical cutting edge, the smooth spiral rake surface with constant normal rake angle and flank surface can been formed during the one-pass grinding process by this method. No interference between the grinding wheel and workpiece happens by the wheel special rotation. The method has the characteristic of detaching the grinding wheel path solution from specified machining conditions. The grinding wheel path is suitable for different NC machine tools through post processing. Meanwhile, a mechanism kinematic model of the NC machine tool is built, and a generalized algorithm for post-processing of multi-axis NC machine tools is presented. This model is applied to arbitrary configuration of NC machine tool, and the motion value for each axis will be generated by the inputting structure and motion parameters of the machine tool. The model, together with the machining method mentioned in this paper, make the calculation and generation of the grinding wheel path simpler and universal. At last, the validity of the method given in the paper is identified by an example of grinding.     

Simulation-based approach to modeling the chip formation energy of polishing process

Polishing is one typical material removal process, which is widely used for surface processing of porcelain tiles. Due to complex polishing head structure and kinematics features of polishing machine, polishing for porcelain tile is a high energy intensity process. To improve the energy efficiency by optimizing operation, it is essential to establish an energy consumption model for polishing process. This article divides the total energy of polishing process into constant energy and chip formation energy. Furthermore, this article focuses on modeling the chip formation energy for optimizing operation. Based on the energy conversion mechanism and energy flow characteristics, the chip formation energy of polishing process is further divided into three motion energies that govern the abrasive trajectory over the tile surface. A conceptual framework of simulation-based approach is then proposed for modeling chip formation energy of polishing process by integrating the above calculation algorithm of motion energy. Finally, a case study is implemented to illustrate the validation of the proposed approach, and the results show that it is a feasible tool to model the chip formation energy of polishing process and reveal the influence of different process operational parameters.     

用于模具自由曲面的新型气囊抛光中磨粒场的分析

为提高模具自由曲面抛光的效率和品质,提出一种基于柔性抛光理念的新型气囊抛光技术。研究了气囊抛光接触区内磨粒的运动轨迹、压力分布和抛光力的分布情况,建立了气囊抛光接触区内磨粒的运动模型、压力模型,揭示了气囊抛光接触区内磨粒直径对抛光力和被加工工件内部剪切应力的影响规律,研究了抛光过程中工件内部的剪切应力分布,明确了材料疲劳去除机理。为气囊抛光的应用奠定了理论基础。     

薄壁回转体表面岛屿状高凸台结构旋印电解加工成形过程研究

以航空发动机机匣为代表的薄壁回转体表面分布有大量岛屿状的高凸台结构，此类零件普遍存在加工变形大、刀具损耗严重等制造难题。旋印电解加工采用回转体工具电极，通过工件与工具的同步对转实现阳极材料的逐层均匀溶解，对于机匣等薄壁回转体零件加工具有独特优势。开展了旋印电解凸台成形过程的仿真研究，建立了电极等效运动分析模型和阳极溶解数学模型，掌握岛屿状高凸台结构旋印电解加工成形规律。仿真结果表明，阴极进给深度和窗口宽度对凸台轮廓形状有着很大的影响。随着阴极工具的不断进给，阴极窗口运动轨迹的包络线逐渐由尖锥形变为纺锤形，凸台侧壁锥度不断减小，呈现从正锥形→垂直→倒锥的变化趋势。阴极窗口宽度的增加会导致窗口运动轨迹倾斜角度增大，有利于获得锥度较小的凸台侧壁轮廓。对于任意阴极窗口宽度的凸台侧壁轮廓均可以通过某一宽度的轮廓通过角度旋转偏置获得。此外，旋印电解加工间隙呈现出非平衡态变化趋势。在仿真分析的基础上，进一步开展了旋印电解加工试验研究，在镍基合金GH4169薄壁回转体表面加工出岛屿状高凸台结构。试验结果表明旋印电解加工技术对于具有较大高度复杂异形岛屿状凸台结构的薄壁回转体零件具有较好的加工能力。     

滚珠型弧面凸轮分度机构的运动分析和仿真

滚珠型弧面凸轮分度机构中滚珠的运动影响到机构的润滑、失效形式和传动效率。滚珠中心、滚珠与凸轮滚道接触点及滚珠与分度盘球窝接触点相对于凸轮旋转轴线运动轨迹为螺旋曲线,计算表明3条曲线的螺旋升角大小不同。利用螺旋传动理论,分析滚珠的运动形式,计算滚珠的侧滑速度。应用RecurDyn软件对机构进行运动学仿真,验证了滚珠侧滑和锲紧的存在及负载转动惯量对分度盘运动规律的影响。     

钢球全表面展开原理及方法

针对轴承用钢球表面缺陷检测的生产需求,以实现球面全展开为目标,提出球面螺旋线运动展开原理。首先,设计实现钢球全表面展开的倾斜轴锥面驱动体,并建立其锥面模型;分析展开过程中球面上一点的运动参数,建立钢球和驱动体的接触约束模型,采用迭代法求解拟合出驱动体锥面上接触点的运动轨迹模型;为保证钢球全表面展开,进一步分析球面上接触轨迹,利用弧长积分得到展开过程中球面上的接触轨迹曲线模型;最后通过仿真技术和物理样机试验对钢球展开过程进行分析测试,验证了理论分析结果的正确性。提出的球面展开理论及方法可以应用到高精密轴承球类滚动体的表面缺陷检测设备,也可对其他球类物体的检测提供理论参考。     

Efficient automatic polishing process with a new compliant abrasive tool

In this paper, an efficient polishing process is proposed for precision polishing tasks using a new compliant abrasive tool. The polishing process is conducted by a force-controllable five-axes robot. The polishing process comprises many steps using different abrasive grain sizes. For each process step, an optimal set of polishing parameters that can efficiently reduce surface roughness is determined by the Taguchi method. The relation between the surface roughness and the polishing efficiency for each set of optimal parameters can be fitted as an R–E curve. The efficiency of a polishing step decreases with the number of polishing cycles and the surface roughness reduces to an asymptote value. The automatic polishing scheduling is fulfilled by switching to a more efficient choice among these R–E curves until the desired surface roughness is reached.     

气囊抛光技术及其研究现状

气囊抛光能够获得稳定的材料去除特性和高质量的抛光表面。回顾了气囊抛光的工作原理、特点和发展现状,对气囊抛光的关键技术进行了比较分析,包括抛光工具,进动抛光,脉动抛光,磁流体抛光,驻留时间,边缘控制和过程控制,抛光轨迹规划,磨粒场及气囊抛光应用等。研究结果表明,气囊抛光是一种值得关注的自由曲面高效精密抛光方法。     

Finishing of structured surfaces by abrasive polishing

A new polishing process for the finishing of structured optical elements was introduced by the authors. Abrasive polishing using pin type and wheel type polishing tools made of polyamide was applied to improve the surface roughness of structured molds exhibiting fly-cut and precision ground V-grooves. Surface roughness of abrasive polished sides of V-grooves was found to be about 5 nm Ra. Furthermore, material removal rates were determined according to Preston's equation resulting in increasing removal rates with increasing polishing pressure and relative velocity. Material removal in abrasive polishing of structured surfaces was observed to be caused mainly by two-body abrasion but also by three-body abrasion, depending on relative velocity and polishing pressure. Tribological investigations showed that in abrasive polishing of structures mainly micro-ploughing and less micro-cutting occurs.     

化学机械抛光垫沟槽形状的研究及展望

在化学机械抛光过程中,沟槽形状是抛光垫性能的重要影响因素之一,它会直接影响抛光效果。本文介绍了化学机械抛光垫上沟槽的基本形状及其对抛光效果的影响,以及不同复合形状的抛光垫沟槽及其对抛光效果的影响,并就研究中现存的主要问题提出展望。