弧齿锥齿轮硬齿面刮削加工技术综述

为了降低弧齿锥齿轮传动噪声,改善齿轮副的啮合质量,修正轮齿热处理后产生的变形以提高齿轮的工作精度,硬齿面弧齿锥齿轮精加工技术是一广受行业关注的研究对象。根据弧齿锥齿轮切削加工近年来的研究成果,分析了硬齿面弧齿锥齿轮精加工方面已经取得的进展,对弧齿锥齿轮硬齿面精加工方法进行了综述,对我国弧齿锥齿轮硬齿面刮削加工中应注意的问题进行了阐述,结合运用刮削技术进行硬齿面加工的实例,对弧齿锥齿轮硬齿面刮削过程中加工工艺的制定、刮削余量的控制、机床的选定、基准的加工等方面进行了详细分析,并对今后刮削技术在刀具材料的优化、刀盘造型的设计、数控机床的应用等方面的研究进行了展望,展现了硬齿面刮削加工技术在弧齿锥齿轮精加工中应用的广阔前景,以便为后来的齿轮工作者进行弧齿锥齿轮硬齿面刮削技术的研究提供思路。     

电解磨削复合加工精密扩孔研究

研究电解磨削技术应用于9Cr18不锈钢微小孔扩孔工艺,重点分析了加工电压和进给速度对加工质量的影响.实验结果表明,采用电解磨削工艺,选择合适的加工参数可加工出高精度、低表面粗糙度的微小孔.     

木质砂轮的开发

普通砂轮是通过结合剂将无数细小的磨粒粘结在一起的，由于磨粒很硬，磨粒之问的粘结层十分微薄，导致磨粒间的接触几乎是刚性接触，砂轮具有较高的刚度。这种高刚度的砂轮具有高的磨削能力和磨削效率，缺点是被磨工件表面易产生划痕，难以获得高的表面加工质量。为了克服普通砂轮如SiC砂轮存在的高刚性，本文尝试在SiC磨料中加入少量的木质微粉，使其在磨粒之间起半弹性作用，从而改善被加工表面质量。这种半弹性的木质砂轮，是利用木质粉末经干馏、筛选后作为磨料，在砂轮制备过程中混入。本文应用这种砂轮对花岗岩进行了大量的磨削试验及加工比对试验。试验结果表明，木质砂轮不仅具有较高的磨削能力和效率，而且能获得纳米级加工表面(Ralonm／Ry112nm)。     

齿轮成形磨削能耗与表面粗糙度研究

齿轮成形磨削的能耗研究对于高精度齿轮的低碳制造具有重要意义.从数控成形磨齿机床的部件层面出发,分析齿轮成形磨削的能耗组成部分;基于磨削功率和材料切除率,建立齿轮成形磨削的净能耗密度模型;通过齿轮成形磨削试验发现,增加磨削能耗,会使表面粗糙度减小,但随着磨削能耗的持续增加,表面粗糙度减小幅度有限.研究结果为齿轮成形磨削的能耗与加工质量协同优化控制奠定了理论基础.     

A fundamental study on the mechanism of electrolytic in-process dressing (ELID) grinding

Demands for high quality surface finish, dimensional and form accuracy are required for optical surfaces and it is very difficult to achieve these using conventional grinding methods. Electrolytic in-process dressing (ELID) grinding is one new and efficient method that uses a metal-bonded diamond grinding wheel in order to achieve a mirror surface finish especially on hard and brittle materials. However, studies reported so for have not explained the fundamental mechanism of ELID grinding and so it has been studied here by conducting experiments to establish optimal grinding parameters to obtain better surface finish under various in-process dressing conditions. In this research the results show that the cutting forces are unstable throughout the grinding process due to the breakage of an insulating layer formed on the surface of the grinding wheel; however, a smoother surface can be obtained using a high dressing current duty ratio at the cost of high tool wear. ELID grinding is efficient for feed rates of less than 400 mm/min, and surface cracks are observed when it exceeds this limit.     

Surface finish on hardened bearing steel parts produced by superhard and abrasive tools

New technological process consisting of hard turning (HT) followed by abrasive machining, in place of the widely used method in industry, i.e., hard turning versus grinding, has lately been launched in the automotive industry. This is because, many transmissions parts, such as synchronizing gears, crankshafts and camshafts require superior surface finish along with appropriate fatigue performance. This paper provides a comprehensive characterization of part surface finish produced in dry turning of a hardened AISI 52100 bearing steel using mixed ceramic (MC) and PCBN tools, and also its modification after special abrasive finishing operations including superfinishing (SF) and belt grinding (BG). In this investigation, some important 2D and 3D surface roughness parameters, as well as profile and surface characteristics, such as the amplitude distribution functions, bearing area curves, surface topographies and contour maps obtained for the four surface types selected, were determined and analyzed. Experimental data gained during measurements indicate that each of the finishing abrasive processes provides a specific set of surface topologies. The transformation of bearing properties of surfaces, generated through two optional PCBN HT-BG and MC HT-SF machining sequences, are highlighted. As a result, the modifications of surface profiles achieved by means of special abrasive machining operations can distinctly improve the bearing properties of previously hard turned surfaces, and exemplarily, they shorten the running-in period.     

连续轴向进给时工程陶瓷的平面磨削

本文对工程陶瓷在连续轴向进给时的平面磨削进行了详细的研究，分析了磨削参数，尤其是轴向进给速度对平面磨削时磨削过程和磨削效果的影响，探讨了适合于陶瓷特点的高效磨削方法。     

Development of a Novel Modular and Agile Face Machining Technology

A novel face machining technology has been achieved by combining milling and grinding into one operation. The system's ability to control these distinct metal removal processes independently provides a high degree of process agility in terms of metal removal rate, surface finish and part flatness. A physics based model of the combined process has been developed to aid process development. It provides force and deflection values resulting from the unique excitation of milling and grinding together with the dynamics of the machine, fixture and part. The simulations are presently being validated using a prototype machine based on this machining technology.     

Fabrication of optical freeform molds using slow tool servo with wheel normal grinding

Precision molding is recognized as the most appropriate technology for the mass production of glass freeform optics. However, difficulty arises when fabricating freeform molds with sub-micron form accuracy and nanometre-scale surface finish. A novel wheel normal grinding approach with fillet-end grinding wheel based on slow tool servo is proposed to ensure that the wheel errors are not transferred to mold surface and, thus, that the required machining accuracy is achieved. The wheel path generation strategy and the corresponding wheel truing method are presented. A toric tungsten carbide mold is ground to experimentally verify the validity of the proposed method.     

Tribological behavior of micro structured surfaces for micro forming tools

Mechanical micro machining processes, like milling and grinding are appropriate technologies for the flexible production of precise molds with complex shapes for metal forming processes. In most cases machining strategies are orientated towards form accuracy of the desired forming tool only. Thus, the generation of tribologically advantageous surfaces is often carried out in subsequent machining steps like honing. In micro scale the subsequent treatment of complex surfaces is very difficult. For that reason it is desirable to create the shape and a suitable surface texture with one tool in one step.This paper is focusing on the comparison of the tribological behavior of polished surfaces with structured surfaces machined by micro milling and micro grinding processes. Micro milling tools and grinding pins with ballend shape are used to create micro structured surfaces. The machining strategy (tool path and line pitch) was varied for both tool types in the same manner. The experiments were carried out on hardened cold working steel using tungsten carbide micro cutters with TiAlN coating and micro grinding pins with an abrasive diamond layer. White light interferometry was used to characterize the machined surfaces and determine the surface parameters. Moreover, a strip drawing test was set up to investigate the tribological behavior of the system consisting of the machined surfaces and thin sheet metals. The results of the strip drawing test suggest a relationship between micro structure and tribological behavior. Finally, the dependencies between machining technology, surface parameters and tribological behavior will be discussed.     

基于轴承毛坯表面分析的磨削材料去除率模型与应用实验

目的 在轴承套圈磨削加工中,传统基于动力学模型建立的磨削材料去除率模型仅考虑了磨削工件-砂轮-机床三者的弹性变形,未考虑毛坯零件表面不规则变形对模型的影响,导致传统理论模型在实际磨削应用中的效果不佳。针对此问题,基于轴承套圈毛坯表面形状分析建立了新的磨削材料去除率模型,并进行了应用实验。方法 基于轴承套圈毛坯零件表面形状的工艺研究,针对粗磨阶段毛坯零件表面不规则形状和弹性变形对磨削加工及产品质量的影响,建立不同偏心圆数量的轴承套圈结构分析方法,并提出一种以分段函数形式的磨削材料去除率模型,该模型充分考虑了轴承套圈毛坯零件表面不规则变形和偏心圆形状对磨削材料去除的影响,可有效反映轴承套圈实际材料磨削去除过程。最后,通过大量实验对所建的分段函数形式的磨削材料去除率模型进行应用实验研究。结果 与传统磨削材料去除率模型GPSM相比,所建的以分段函数形式的磨削材料去除率模型MMRG的准确率提高了96%以上,该模型可有效在线量化分析毛坯表面不规则大小及偏心圆结构。结论 该模型对指导毛坯零件制造,保证磨削加工质量和磨削加工效率有着重要的理论指导意义。     

On ultrasonic assisted abrasive flow finishing of bevel gears

Finishing of bevel gears is an important requirement in many machining shop floors. Variants of abrasive flow machining (AFM) could be plausible solutions for finishing such parts with intricate geometries. In the present work, a relatively new variant of AFM called ultrasonically assisted abrasive flow machining (UAAFM) technique was employed to finish bevel gears made of EN8 steel. An analysis of the process has been presented with suitable illustrations. A finite element simulation of the behavior of the medium during finishing of bevel gears using the UAAFM process has been presented. A 3D model was constructed to simulate the flow of medium through the outer wall of the gear tooth surface using computational fluid dynamics (CFD) approach. The velocity, pressure and temperature values along the length of the workpiece were computed for both UAAFM and the conventional AFM processes. Further, the effectiveness of the process was investigated through experimental trials by conducting a comparison study between classical AFM and UAAFM. Ultrasonic frequency, extrusion pressure, processing time and the media flow rate were considered as the input variables while improvements in surface finish and material removal were considered as the monitored outputs. Results confirm that improvements in surface roughness and material removal are significantly higher than those obtained with conventional abrasive flow machining. The study further reveals that, the applied high frequency (ultrasonic) vibration to the workpiece has the maximum influence on the process responses among the variables considered.     

A hybrid process of raining co-deposition and rotary wire spark erosion in the development of a custom CBN tool for making a biochip injection mold

This study examines a hybrid process combining raining co-deposition and rotary wire spark erosion with one-off grinding to generate an array of microgrooves in the fabrication of biochip injection molds on NAK80 steel. A precision composite electroforming device that can create a rain like co-deposition effect to uniformly grow a Ni-based Cubic Boron Nitride (CBN) abrasive layer onto a wheel-blank substrate is proposed and employed. Slicing and dressing are conducted by using rotary wire spark erosion to make the co-deposited wheel-blank into a thin CBN wheel-tool with a grinding edge array that alternates between coarse and detailed. A multiple microgroove array on NAK80 steel is one-off generated by using the developed CBN wheel-tool array, swiftly creating a superior surface finish for biochip injection molding. A comprehensive examination of the quantitative and qualitative properties of the CBN wheel-tool was undertaken. Experimental results have been evaluated in terms of CBN grit content, accuracy of co-shaft machining, influence of grinding depth, shape of microgroove and tool wear as well as an estimation criterion for the CBN wheel-tool array.     

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。     

钛及钛合金平面磨削加工工艺研究

磁控溅射钛靶靶面加工精度要求很高，采用一般砂轮磨削，砂轮粘附现象严重，磨削精度达不到设计要求。为此，通过分析钛的物理力学性质，设计制备了专用砂轮。其砂轮的磨粒组成及精度、硬度和粘结剂均与钛的性质相匹配。通过试验筛选确定了一组合适的磨削参数。其磨削速度v0=35m／s，工件纵向进速度vw=12～15m／s，砂轮径向进给运动单行程量fr=0．005m/单行程。采用此参数进行磨削，钛靶靶面尺寸精度和粗糙度均可达到设计要求。     

调心轴承外圈立式车磨复合机床的设计

为在轴承外圈硬车立式数控车床基础上,增加调心轴承外圈滚道的磨削功能,设计调心轴承外圈立式车磨复合机床。分析轴承外圈在立式数控车床上的装夹方式,并对轴承外圈滚道范成法磨削原理进行研究。利用该机床经一次装夹,可实现调心轴承外圈一个端面、内外圆表面硬车及滚道面的精磨加工,可以满足调心轴承外圈加工精度要求,同时提高生产效率。     

Surface finish in robotic disk grinding

In spite of the various complexities, the ground surface during robotic grinding shows a definite and distinct surface texture. This paper presents a simple model for the surface finish produced during this process. The model is based on two simple assumptions. First is that though many grits remove material, the last grit that cuts largely in the ground surface determines the surface finish value. The second assumption is that the average shape of the active grit is spherical which generates a groove of parabolic cross section. The model is shown to be consistent with surface finish values measured experimentally during robotic rigid disk grinding and is able to predict the effect on surface finish to be expected when a given grinding variable is changed. It can be used for the purpose of process planning to improve the surface finish when desired.     

复合轮齿齿轮副同步互研法工艺研究

介绍一种采用高精度同步齿轮进行强制研磨对复合轮齿齿轮副进行精整加工的方法。     

数控车床高速车削滚珠丝杠的工艺方法

滚珠丝杠属典型的细长轴类零件,由于其长径比比较大,加工后很难获得满意的表面粗糙度和几何精度.传统的滚珠丝杠加工方法是“车-淬-粗磨-精磨”,采用磨削工序能提高滚珠丝杠的加工质量,但磨削设备造价较高,磨削工序耗时较长,能源消耗大.探讨滚珠丝杠加工的工艺方法,设计制造一种新型的丝杠加工专用数控车床,并采用“车-淬-精车-磨”的新工艺,提高了生产效率,降低了生产成本,解决了滚珠丝杠的加工难题.     

New tool concept for grinding a plateau-like surface for tribological applications

One of the most important factors for energy efficiency is the reduction of friction in machine elements. The grinding process is often the final machining process in machining hardened steel parts and the resulting surface finish influences the tribological behavior. The combination of grinding with a honing process can generate a plateau-like surface to reduce friction and create an oil reservoir to decrease abrasive wear and improve the fluid film stability. Additional processes like laser machining, micro milling or etching are able to generate micro dimples to improve the reduction of friction. Today, grinding processes are limited to machine plateau-like surfaces. Within this paper, a new tool concept will be presented, composed of a grinding tool with two different grain sizes and a metallic bonding. The use of small abrasive grains generates a smooth surface with low roughness values. A few additional larger grains induce stochastic scratches and create the plateau-like surface. Grinding experiments are conducted to analyze the effect of feed rate, feed angle and ratio between small and large grains on the resulting surface.