钻夹头夹紧力的分析与计算

分析了影响钻夹头夹紧力的因素。根据影响夹紧力的因素,提出了钻夹头夹爪螺纹修行的理论,改变钻夹头的参数,减小了钻夹头夹头螺纹的螺纹升角,进而提高了钻夹头的夹紧力。并通过实际例子的计算验证了理论的正确性。     

周向振动钻床钻夹头整体松脱解决方法研究

分析了周向振动钻床钻夹头整体从钻床主轴上松脱下来的原因，提出了极限摆振圆频率的概念，给出了极限摆振圆频率的计算公式．用事例验证了公式的正确性。找出了解决这一问题的办法，并提出了一些设想。实验表明，该方法简便、有效、切实可行。     

45钢深孔枪钻切削试验与切屑形态分析

切屑形态对枪钻深孔加工中孔成型精度影响极大,钻尖切屑易堵塞在V型排屑槽中或缠绕在钻头上,合理的断屑和排屑是保证加工顺利进行的前提。选用硬质合金枪钻对45钢进行深孔加工试验,采用单因素试验法研究切削速度和进给量对切屑形态的影响规律。试验表明:切削速度较低时,主要为带状切屑;切削速度较高时,主要为单元切屑;当切削速度保持不变时,随着进给量的增大,切屑的主要形状从长带状向单元切屑逐渐转变;当进给量保持不变时,随着切削速度的增大,切屑尺寸从大变小再变大。     

Simple mechanical device for orienting tissue blocks on the ultramicrotome

A simple and inexpensive modification of the specimen holder of the Porter-Blum model MT-1 has been devised, which allows fine adjustments of tissue block orientation in both horizontal and vertical planes. It consists of an additional ring mounted on the existing locking ring and fitted with four radial screws which push the shaft of the chuck.     

立式钻床的数控改装

将目前使用的普通立式钻床进行数控化改装 ,以适应壳体端盖等零部件加工 ,在生产线上取代了多轴专用钻床     

Study on the effect of various machining speeds on the wafer polishing process

Silicon wafer polishing has an important role in semiconductor manufacturing; the general purpose of the polishing process is to produce a mirror-like surface. The wafer surface roughness is affected by many variables such as the carrier head unit characteristics, operation, platen and chuck speeds, pad and slurry ratios, and temperature. The optimum process conditions for the experimental temperature, down-force, slurry ratio, and processing time were determined in previous studies and used as fixed factors in this experiment. The main purpose of the present study was to determine how the different platen and chuck machining speeds influence the wafer surface roughness via the polishing process to obtain the optimum machining speed. In the results, the machining temperature appeared to differ at different machining speeds, which is a vital element with regard to wafer polishing.     

An intelligent method for identifying otological drill slippage

An otological drill is a fundamental apparatus used for bone-milling in ear surgery. A common problem in bone-milling is that the drill bit slips on the bone surface. To improve the operational safety of such a surgery, this article presents a new apparatus combined with an intelligent method for identifying drill slippage. A two-axis force sensor is installed on a modified drill, and it detects the force of the bone's reaction to the drill bit. By integrating the unit reaction forces of the bone and the drill bit on the contact area, the functions of the force signals are deduced, which can reflect changes in the milling parameters. Based upon these functions, the slippage force, which is an important factor in drill slippage, is then extracted. An adaptive filter is specially designed to suppress interference in the slippage force. Drill slippage can be identified by calculating the variations in the filtering results. Five surgeons were invited to carry out an experiment in which they used this method on calvarian bones. Their average recognition rate of drill slippage was 86%, and only 1% of normal millings were identified as milling faults.     

快速夹具的关键部件性能分析与研究

由于夹头的形状特殊，建立夹头的力学模型是快速夹具性能分析的难点。对工件与夹头之间的接触方式提出了假设，依此建立夹头的力学模型，利用空间力系平衡解析条件，求解夹头受力，分析了夹头有限元模型中力的三要素，对夹头进行线性静力分析，并且以此判断夹头的力学性能，最后通过实例应用验证了该方法的可行性。     

高速精密动力卡盘分析与建模

高速精密动力卡盘设计要求载荷大、变形小、安全系数高,通过建立高速精密动力卡盘在切削力作用下的卡盘高爪受力模型,分析了带离心力补偿机构的卡盘结构,并针对刚度对称的卡盘提出了精密的夹紧力损失模型,为动力卡盘的优化设计提供了重要的理论参考.     

高速精密动力卡盘分析与建模

高速精密动力卡盘设计要求载荷大、变形小、安全系数高,通过建立高速精密动力卡盘在切削力作用下的卡盘高爪受力模型,分析了带离心力补偿机构的卡盘结构,并针对刚度对称的卡盘提出了精密的夹紧力损失模型,为动力卡盘的优化设计提供了重要的理论参考。     

Preparation of cryosections with a modified Sorvall MT2B ultramicrotome and cryoattachment

The Sorvall MT2B ultramicrotome and cryoattachment were modified to extend the duration of cutting and to overcome problems in tissue preparation. Microtome and cryochamber were encased and surrounded by an atmosphere of dry nitrogen gas at room temperature. A specially designed cold block sited within the box close to the microtome enabled tissues to be trimmed at low temperatures in the dry environment. Tissues could be readily visualized both on the trimming block and in the chamber with the existing microscope modified to improve its working distance and lighting system. During transfer from storage in liquid nitrogen, through the trimming procedure, to arrival in the cryochamber, the temperature of tissues as determined using thermocouples embedded in PVP on a stub, never exceeded 140 K. Although there was a considerable standing temperature gradient within the cryochamber, the cutting environment, specimen and edge of the knife were thermally stable. Sections could be routinely cut dry and freeze-dried within the chamber, if desired.     

偏心内圆类轴承零件磨削加工用夹具的设计

设计了一套专门用于磨削加工偏心内圆类工件的可调夹具,以在内圆磨床上磨削三叉式等速万向节钟形罩为例介绍了夹具的结构及工作原理。该夹具以端齿盘为精密分度装置,结合三爪自定心卡盘机构,可实现一次装夹、多工位加工,适合磨削分度精度高的中小型工件的偏心内圆。     

钻机卡盘夹紧机构的改进设计

主要研究了对钻机卡盘夹紧机构中卡圈、碟形弹簧及卡瓦座的结构参数的改进。在分析夹紧机构的构成及工作原理的基础上,给出了碟形弹簧工作时的压缩量、提供的弹力大小、卡圈倾斜角、卡圈位移和卡瓦位移等多个参数之间的数学关系,进而重新选取了卡圈的倾斜角,重新设计制作了新型的加厚碟形弹簧,并做了新、旧碟形弹簧的承载性能的对比实验,表明新的加厚碟形弹簧效果良好。     

车床卡盘扳手安全装置设计

根据普通卧式车床在实际操作过程中安全隐患最为突出的卡盘扳手而设计出一套车床卡盘安全保护系统。针对普通卧式车床在实际操作装卸工件时存在的安全隐患,提出安装车床卡盘安全保护系统的必要性,详细说明了所设计的安全保护系统的结构和工作原理,并对车床卡盘安全保护系统的安全保护性能进行了分析。     

浮动式六爪卡盘的改制与应用

针对三爪卡盘夹持薄壁工件时易变形的问题,介绍了一种在三爪卡盘基础上改制出原理可靠、结构简单的浮动式自定心六爪卡盘的方法,实现了改制后的卡盘在六爪联动同时能保证浮动接触、定心夹紧和稳定可靠,减少了薄壁工件夹紧变形。检测数据证明,浮动式自定心六爪卡盘能极大提高薄壁工件的加工精度。     

基于ANSYS的有机玻璃加工用钻头的优化设计

以Pro/E为平台建立了战斗机前挡玻璃加工用钻头的三维参数化模型;经过模型简化等前处理,把所建三维CAD模型转化为有限元模型,利用网格划分技术对钻头进行网格划分和单元属性定义,最后施加约束条件进行有限元分析求解。通过将该钻头与普通麻花钻进行分析比较,为钻头的优化设计提供了参考。     

双油缸四爪液压卡盘的研制

根据矩形工件、偏心工件和特殊形状工件等的结构特点，研制出一种双油缸四爪液压卡盘，解决了四爪液压卡盘的定心问题。实际使用表明，这种四爪液压卡盘具有结构紧凑、拆装方便、可夹持范围大、调整方便等优点，适合用来加工各种特殊形状的零件。     

有限元法在深孔钻头扭转计算中的应用

介绍了有限元法在深孔钻头扭转计算中的应用。用有限元法分析了钻头容屑槽单元的划分 ,列出了深孔钻头扭转时的应力、扭矩和刚度的计算公式 ,为应用计算机对钻头扭转的计算提供了理论依据。     

分体式三爪卡盘的设计

动力卡盘是机床夹具的重要附件，这里以Ф250卡盘为例在加工较大尺寸的工件时存在的问题，并对原有的常规结构提出了相应的改进措施，设计一种分体式动力卡盘，解决卡盘加工精度和磨损问题。     

Experimental study on nanofludic heat pipe hot chuck plate in semiconductor wafer baking process

The temperature uniformity on a heat pipe hot chuck (HPHC) during semiconductor wafer processing has been an important factor to critical dimension (300 mm) uniformity as the feature size of semiconductors decreases and productivity density increases due to the new process of nano size special manufacturing technology. To design the present heat pipe hot chuck system, which has enhanced temperature uniformity for the wafer process, the heat distribution of the system was analyzed experimentally with various working fluids such as water, TiO₂, ATO, ITO, Al₂O₃, and Ag-nanofluids and 8 cell structures. Unlike the conventional solid state chuck, the present heat pipe hot chuck system consists of a heat pipe containing specially charged working fluid. Various working fluids have been tested to find best temperature uniformity feature on the top surface of hot chuck. TiO₂-nanofluid was used and tested as the working fluid of the heat pipe hot chuck system in this paper. The temperature uniformity of upper surface was sustained in the range of ±1°C. A nano-porous layer was observed on the surface with the good result of surface temperature uniformity compared with distilled water.