机床主轴/刀具连接系统离心力效应的分析及解决措施

文章通过弹性力学理论分析了高速状态下离心力对主轴／刀具连接系统特性的影响，提出了主轴装夹刀柄时的过盈量δ与脱松角速度ω^＊、主轴外径与刀柄内径之间的关系，以及主轴／刀具连接系统在离心力作用下膨胀后连接间隙△r与过盈量δ之间的关系。     

高速旋转刀具系统动平衡技术的研究

高速切削时，由于刀具系统的转速很高，刀具系统的不平衡会影响刀具寿命、加工精度和效率。论文从理论上分析了高速加工刀具系统产生动平衡的影响因素，运用ANSYS软件对其进行了静力学分析，并提出了改善刀具系统动平衡的技术方案。     

高速切削刀具系统动平衡研究与分析

分析了影响高速切削刀具系统动不平衡的因素，提出了减小不平衡因素影响的措施，重点论述了合理确定高速刀具系统动平衡精度的原则，     

CN1751848高效低廉的高精度金刚石刀具机械刃磨加工方法

高效低廉的高精度金刚石刀具机械刃磨加工方法，它属于超精密切削加工技术领域。为解决金刚石刀具的制备比较困难的问题，本发明按照下述步骤进行：调节金刚石刀具机械刃磨机床平衡；研磨盘工作表面经过精车成形后进行精细抛光，然后涂覆金刚石磨粒；对研磨机床主轴系统进行精细动平衡；装卡金刚石刀具，刀体卡具调水平；打开气源，开启金刚石刀具刃磨机床电源，调节机床主轴转速；调整前刀面刃磨方向为易磨方向，并调节刀具前角；在主轴工作转速为1800—2500r／min、研磨压力为金刚石刀具装卡系统自重的条件下刃磨刀具。本发明具有刃磨工艺简单、     

为什么转子静平衡后电机振动反而加剧

某厂购进一台单相电容式电机，通电运转后，发现振动、噪声都很大，经研究认为，可能是转子不平衡引起的，为此对电机转子重新校静平衡，但是转子校静平衡后，电机的振动反而加剧，这是什么原因呢？见图1，由于转子不平衡，则式中，F──不平衡重量产生的离心力（N）M──不平衡重量计（Kg）r──不平衡重量的旋转半径（m）ω──转子转动的角速度（raars）例如：r＝50rum，m＝log，n＝2800转／分，由此可见，10克的不平衡重量，转动时将产生较大的离心力42．9牛顿。电机在F的作用下，发生振动，引起机械噪声，加速轴承的磨损，缩短电机的…     

刀柄和刀具的平衡

机床用户经常听说,必须对自己使用的刀柄进行平衡,但他们不清楚这种说法是否正确。如果不对刀柄进行平衡,会损坏机床或工件吗？正确的问题不是“应该对刀具和刀柄进行平衡吗？”而是“何时应对刀具和刀柄进行平衡？”     

科氏力对硬涂层整体叶盘振动特性的影响分析

以某航空发动机整体叶盘简化模型为研究对象，对叶片表面涂覆NiCrAlY硬涂层，建立硬涂层整体叶盘有限元模型。针对不同工况下仅考虑离心力影响和同时考虑科氏力和离心力影响的2种情况，进行模态分析，研究离心力和科氏力对不同转速下硬涂层整体叶盘模态特性的影响，并讨论硬涂层对整体叶盘系统固有特性的影响；最后，根据计算得到的固有频率，得到2种不同载荷下的坎贝尔图，求得硬涂层整体叶盘发生共振时的危险转速。结果表明：转速越大，固有频率值升高，科氏力对频率特性影响越大；硬涂层对整体叶盘结构的频率影响较小，硬涂层削弱了科氏力的影响;对于高速旋转的整体叶盘系统，科氏力影响显著，工程计算时不可忽略。     

基于振动试验建模的不平衡状态预测研究

本文采用不同不平衡量的高速精加工铣削刀具开展铣削振动试验,研究在三种切削速度下,刀具的不平衡量与振动量的关系,利用统计学中回归方法建立相应的数学模型,并通过显著性分析和验证试验证明了三种数学模型的有效可行性。试验结果表明,在使用具有相同不平衡量的高速精加工铣削刀具情况下,切削速度越大,刀具振动量也相应变高;在相同切削参数情况下,刀具不平衡量越高,其振动量也相应变高。同时在不同切削条件下,通过数学模型可以有效对刀具动平衡状态进行预测,从而诊断出刀具的高速精密加工切削性能。     

离心力场电液伺服振动台的鲁棒H∞控制

近年来，离心和振动复合环境在航空航天、土木工程等领域受到越来越多的重视，国外对该环境进行了一些研究，国内的研究还刚起步，本文建立了离心力作用下电液伺服振动台的系统模型，并采用了鲁棒H∞控制方法，仿真表明，该方法对离心力场中的电液伺服振动台具有很好的效果。     

模具高速切削刀具技术研究概况

系统地介绍了模具高速切削刀具技术在各个领域的发展现状，包括：刀具材料、刀具磨损、刀具动平衡、刀具与机床的连接、刀具的可靠性、刀具的监测技术和刀具的几何参数。指出发展模具高速切削刀具技术，要从以下几个方面展开工作：研制和开发新的刀具材料，同时进行PCBN刀具切削性能的研究，推广其应用范围；进行模具高速切削刀具磨损机理的研究，进一步提高刀具寿命；做好刀具的动平衡，防止刀具的破损，保证工作人员的安全；进一步加强刀具监测技术的研究，以获得良好的加工质量；建立模具高速切削数据库，以便有效地利用刀具，提高刀具的寿命；大力推进有限元模拟技术在高速切削刀具技术中的应用。     

Development of a micro/meso-tool clamp using a shape memory alloy for applications in micro-spindle units

In developing micro-spindle units, a critical problem is miniaturization of the tool clamp. Approaches for scaling down conventional tool clamps, such as the collet-chuck, hydraulic chuck, and shrink-fit methods may be limited by their inherently complicated mechanisms. This study developed a novel tool clamp based on shape memory alloy (SMA), which allows further miniaturization. The tool clamp can be simplified by using an SMA ring, which is all that is needed for clamping. The SMA-based tool clamp does not require any collet, and its structural configuration is axisymmetric. Furthermore, the SMA makes it possible to switch between the clamped and unclamped states by using a simple device to regulate small changes in temperature. This paper first describes the operating principle of the SMA-based tool clamp. Second, it presents the finite element method (FEM) analyses that were conducted to investigate the characteristics of the clamping/unclamping operations and the effect of centrifugal force. Third, it describes a prototype of the SMA-based tool clamp, which was designed and built for applications in micro-spindle units. Fourth, it presents an evaluation of the time needed for the clamping/unclamping operations and the tool-clamping force, which were both evaluated experimentally. Finally, it describes a mill-machining test conducted with the prototype, which confirmed that the tool clamp is little affected by centrifugal force at high rotational speeds. The experimental results confirm that the proposed SMA-based tool clamp can be successfully applied to micro-machining.     

Methodology for evaluation of centrifugal force resistance of HSC-tools by analyzing tool body deformation and cutting edge offset

For high speed milling operations the most critical load is caused by centrifugal force. The maximum operational speed has to be determined to ensure centrifugal force resistance without over-dimensioning HSC-tools. Hence, resource intensive burst tests have to be executed. This paper demonstrates a non-destructive methodology to qualify tools for high speed milling. As our research shows, it is possible to estimate the maximum operational speed by analyzing the characteristics of elastic and plastic tool body enlargement and cutting edge displacement. In addition, it will be discussed how work piece quality can be improved by considering the cutting edge offset.     

Development of automatic variable preload device for spindle bearing by using centrifugal force

Machine tool spindles of late require high stiffness and fast rotation characteristics all at once for high-speed, high-efficient processing, as well as for a wide range of use rotation. As such, many studies are being carried out on automatic variable preload control methods that apply a preload to a spindle rolling bearing as an alternative to the existing fixed position preload and constant pressure preload methods. This paper introduces a newly structured automatic variable preload device that can automatically adjust the preload applied to spindles employing a rolling bearing. It proposes an automatic variable preload device with a completely new composition comprising of a main bearing to which the preload is applied, an auxiliary bearing that conveys the force and a centrifugal element that converts the centrifugal force into a force in the axial direction, and a constant pressure preload spring that applies the initial preload to the main bearing. Other changes in the centrifugal force are also presented. The proposed composition was validated through a contact nonlinear analysis, and the design data necessary to create a prototype were obtained. A prototype for the automatic variable preload device using centrifugal force was then created and tested to confirm that the preload device of the proposed structure runs properly and smoothly.     

一种考虑机器人转向离心力的动态窗口算法

在移动机器人的相关技术中,局部路径规划技术是一项关键技术。对于自主配送机器人在配送某些易碎物品或是对运动较为敏感的物品时,为了保证被运输物品的安全性,在路径规划中还要考虑到机器人车体的离心力大小。动态窗口算法是局部路径规划的一种常用算法,针对经典动态窗口算法不能兼顾到机器人在运动过程中的离心力大小,提出了改进的动态窗口算法。在经典动态窗口算法的目标函数中加入离心力的评价项,防止机器人在转向过程中离心力过大导致车体运行不稳定。实验表明:当目标函数中离心力评价项占比更重时,机器人运行的转向半径更大,多数情况下沿直线运行,且在整个导航过程中离心力的最大值更小。     

电磁离心凝固过程中宏观偏析的数值模拟

基于连续模型建立了非惯性坐标系下电磁离心凝固过程流动、传热、传质耦合数学模型．依此模型对Al-5％Cu合金进行了模拟计算．结果表明，电磁离心凝固过程中，电磁力使熔体的平均径向运动速度下降．熔体流动状态的改变使凝固合金外层的逆偏析减轻，凝固过程中两相区的负偏析也减轻．与普通离心铸造相比，电磁离心凝固可减轻铸件宏观偏析．模拟结果与实测铸件成分分布基本吻合，表明本数学模型较好地描述了电磁离心凝固过程．     

不同加载作用下砂轮片破裂失效的有限元分析

针对实际磨削加工中砂轮片的破裂失效机理进行研究,通过ANSYS有限元分析软件对不同加载状态下的砂轮片进行应力分布分析,揭示失效的原因。建立砂轮片有限元模型,对砂轮模型分别施加离心力、磨削力、端面力,模拟砂轮片实际作业中的不同受力情况,分析和比较砂轮工作过程中不同受力状态下的应力、应变和位移变化。结果表明:对砂轮应力影响程度由大至小依次是离心力、端面力和磨削力;对砂轮应变影响程度由大至小依次则为端面力、离心力和磨削力;过大角速度带来的大离心力和端面磨削带来的端面力是造成砂轮破裂的主要因素。     

陶瓷内衬复合铜管的自蔓延高温合成

研究了离心自蔓延高温合成陶瓷内衬复合铜管工艺中离心力和添加剂对复合铜管性能的影响。结果表明：随着离心力增大，陶瓷层的孔隙度降低，压溃强度和压剪强度明显提高，离心力超过200G后，压剪强度反应降低。铝热剂中加入SiO2也可降低孔隙度，提高压剪强度。提高铝热剂预热温度，可加快铝热反应速度，改善复合铜管质量。     

细长轴双刀车削加工让刀量误差优化的研究与应用

通过建立细长轴对称式双刀车削模型,推导出刀具加工点理论让刀量公式。对细长轴双刀车削进行静力学仿真分析,得到刀具在加工点让刀量数据。考虑到刀具径向力与背吃刀量的关系,以及引起刀具让刀量误差的其他因素,在刀具加工点理论让刀量公式中引入修正系数k,对仿真曲线和预测理论曲线进行对比分析,确定修正系数k的大小。最后进行数控车削试验,结果表明:将优化后的理论让刀量公式作为补偿函数车削细长轴能显著提高其加工精度。     

振动台在离心环境中的离心力自恰克服方法研究

根据离心环境下振动台的工作特点，在分析振动离心复合环境下克服振动台离心力的可能条件与具体要求基础上，提出了一种配重克服方法，这种方法所提供的离心力平衡力随离心机的转动角速度同时改变，实现自恰克服。选择合适的克服力作用点可在克服离心力的同时也消除离心力矩的影响，文中也计算和分析了离心力克服装置对振动台工作的影响。     

Simulation of mold filling and solidification during centrifugal precision casting of Ti−6Al−4V alloy

A two-dimensional simulation model for melt flow and solidification in centrifugal precision casting has been developed based on experimental results on melt flow in a precision casting tree for Ti-6A1-4V alloy castparts. The amount of liquid alloy is intentionally adjusted to be less than that required for complete filling and is poured under a centrifugal force. The melt flows into mold cavities keeping contact with the vertical inside walls of the cavity in the anti-rotation side, and solidifies directionally by accumulating a solidified layer from the far end of the cavity to the gate according to the gradient of centrifugal force. The model reproduces melt flow observed in casting trials and directional solidification during centrifugal casting. In addition, it has been confirmed that the centrifugal force imposed on the melt enhances removal of defects caused by entrapment of gas bubbles or by solidification shrinkage and improves mechanical properties of the castparts. Formerly Graduate School of Iron and Steel Technology Pohang University of Science and Technology San 31 Hyoja-dong, Namku, Pohang 790-784, Korea