一种等离子切割机切割机构的设计

针对等离子切割在不锈钢板材下料方面的应用讨论,通过对目前下料方式的优缺点分析,阐述了等离子切割在该领域应用的重大意义,设计出了一种等离子切割机的整体结构方案,详细说明了切割工艺过程。同时,对机器切割机构部分进行了深入的探讨,通过对该机构的功能和运动分析、对各种实现方案的比较以及对关键部件的设计计算,提出了一种经济适用的结构方案。该切割机构结构简单,调整方便,能较好地满足切割生产要求。     

五轴并联机床正解研究

并联机床运动学正解问题由于涉及到求解非线性方程组问题而不易解决。首先对五轴并联机床进行运动学建模,获得了其运动学方程;然后使用连续同伦方法,对上述方程组进行求解,并获得并联机床正解。     

五轴数控机床旋转轴几何误差测量与建模

利用球杆仪对五轴数控机床旋转轴的几何误差进行了测量及建模。在测试中,五轴数控机床采用两个平动轴和一个旋转轴同步运动,球杆仪采用径向、切向和轴向三种测试路径,并在此基础上对其进行几何误差建模。     

双轴转台精度检测与研究

双轴转台为加工中心和数控铣床提供了回转坐标,通过双轴数控转台的等分回转、不等分回转、连续的回转,实现了数控机床复杂曲面精密加工,扩大了数控机床的加工范围。针对双轴转台应用于五轴数控加工中心目前ISO认证中没有规定其几何精度和运行精度检验方法。通过变换矩阵建立双轴转台误差模型,分离出双轴转台运动误差,采用实验方法,改变双轴转台试验装置运动参数,对分离出的双轴转台进行精度检测。针对五轴数控加工中心用双轴转台几何精度和运行精度检验,提出了一种有效的双轴转台误差测量与分析方法。     

Dynamic modeling and validation of a tripod-based machine tool

In this paper, a reconfigurable tripod machine tool system is introduced, with a focus on dynamic modeling. The Newton-Euler approach is applied and a new modeling procedure is proposed. In the procedure of the dynamic modeling, the reference coordinate system for the forces/torques calculation and that for the equilibrium equations derivation are dealt with respectively. As a result, specific structural features of the tripod system are utilized to simplify the dynamic model and, thus, reduce the calculation complexity. The prototype tripod system is developed and the presented method is implemented for its configuration design. An experiment is conducted to validate the dynamic model.     

转台-摆头式五轴机床几何误差测量及辨识

为降低转动轴几何误差对转台-摆头式五轴机床精度的影响,提出了基于球杆仪的位置无关几何误差测量和辨识方法。基于多体系统理论及齐次坐标变换方法建立了转台-摆头式五轴机床位置无关几何误差模型,依据旋转轴不同运动状态下的几何误差影响因素建立基于圆轨迹的四种测量模式,并实现10项位置无关几何误差的辨识。利用所建立的几何误差模型进行数值模拟,确定转动轴的10项位置无关几何误差对测量轨迹的影响。最后,采用误差补偿的形式实验验证所提出的测量及辨识方法的有效性,将位置无关几何误差补偿前后的测量轨迹进行比较。误差补偿后10项位置无关几何误差的平均补偿率为70.4%,最大补偿率达到88.4%,实验结果表明所提出的建模和辨识方法可用于转台-摆头式五轴机床转动轴精度检测,同时可为机床精度评价及几何精度提升提供依据。     

小功率CO2激光切割机控制部分设计

针对广告市场非金属加工设备的需要,分析了激光切割机床的机械结构,根据功能要求详细地介绍了主要控制部件的选配以及各控制部件的连接并得以实现,为研制同类激光加工机床提供了依据.     

车方机床行星轮系机构的设计计算

车方机床用曲率半径很大的椭圆短半轴曲线代替直线切削方形工件。生产率高 ,刀具成本低。选取适当的车头行星轮的分度圆直径 ,可以有效地控制车方原理的直线度误差。对实际工件进行了原理误差的分析计算和行星轮系的设计计算     

可转位刀片刃口钝化与机床应用

主要针对可转位刀片刃口钝化形式及作用进行介绍,结合实际生产中所使用的机床,给出两种重型切削刀片刃口在钝化过程中合理参数的确定及相应问题的处理.     

The influence of friction on contouring accuracy of a Cartesian guided tripod machine tool

This paper is focused on the friction-induced contouring errors of a three-axis parallel kinematic machine (PKM) called a Cartesian-guided tripod (CGT). A dynamic model of the CGT including the nonlinear dynamic, mechanical compliance and mechanical friction has been formulated. Servo control characteristics of the formulated CGT dynamic model are analyzed based on the conventional P-PI controller and feedforward friction compensation implemented in the joint level control scheme. Quantitative analysis and comparison of the various friction sources from the actuated joints (ballscrew/nut) and passive joints (balljoint and guideway) have been conducted. Analysis results show that the ballscrew/nut friction produces the most significant friction-induced contouring errors. The ball-joint friction and linear-guide friction induced contouring errors are two-order and one-order, respectively, lower than the errors by the ballscrew friction. The main reason is that the equivalent friction torques of these two friction sources coupled into the servo drive loop are reduced by the leverage effect of the driving leg length. It was also found that the conventional feedforward friction compensation can effectively reduce the ballscrew-friction-induced contouring errors. However, if not properly compensated, ballscrew friction could excite significant platform-leg structural vibration because the tripod-based PKM usually has a high compliance vibration mode in the horizontal platform-leg direction. The friction-excited structural vibration can be reduced by putting vibration absorbers on the guideways of the passive leg to damp out the platform-leg vibration. From the primary analysis results, it can be seen that the proposed tripod based PKM has high potential for high-speed 5-axis machining applications.     

数控机床固定结合面的建模与特征参数识别

结合面的建模是结合面特征参数识别的关键问题.结合面建模时,分别用传统方法(基于弹簧-阻尼单元)和改进方法(基于接触单元和弹簧-阳尼单元)进行建模.根据两种等效模型,分别建立CK1632数控机床床身与底座固定结合面的有限元模型,用有限元分析软件ANSYS10.0进行模态分析,同时进行结合面参数的优化设计,先优化出刚度,再优化出阻尼值.模态振型分析的结果表明,基于接触单元及弹簧-阻尼单元的结合面模型比较合理.利用ANSYS的命令流输入方法计算出结合面的参数识别结果.这对机床整机动态特性的分析和优化设计具有重要意义.     

Speed-varying cutting force coefficient identification in milling

Accurate simulation of the machining process is crucial to improve milling performance, especially in High-Speed Milling, where cutting parameters are pushed to the limit.Various milling critical issues can be analyzed based on accurate prediction of cutting forces, such as chatter stability, dimensional error and surface finish. Cutting force models are based on coefficients that could change with spindle speed. The evaluation of these specific coefficients at higher speed is challenging due to the frequency bandwidth of commercial force sensors. On account of this, coefficients are generally evaluated at low speed and then employed in models for different spindle speeds, possibly reducing accuracy of results.In this paper a deep investigation of cutting force coefficient at different spindle speeds has been carried out, analyzing a wide range of spindle speeds: to overcome transducer dynamics issues, dynamometer signals have been compensated thanks to an improved technique based on Kalman filter estimator. Two different coefficients identification methods have been implemented: the traditional average force method and a proposed instantaneous method based on genetic algorithm and capable of estimating cutting coefficients and tool run-out at the same time.Results show that instantaneous method is more accurate and efficient compared to the average one. On the other hand, the average method does not require compensation since it is based on average signals. Furthermore a significant change of coefficients over spindle speed is highlighted, suggesting that speed-varying coefficient should be useful to improve reliability of simulated forces.     

一种可调式二轴铣刀头架的设计与实现

为降低手术刀柄专用机床的改造成本,设计了一种新型可调式二轴铣刀头架。由于采用了斜齿轮消除间隙机构,有效补偿了调节过程中产生的齿侧间隙。介绍了该装置的结构和工作原理及实现方法,并推导了薄片斜齿轮间加工垫片厚度的计算公式。经实践表明:该装置结构简单、运行平稳,很好地满足了生产要求。     

微型机床的结构动态特性分析

利用有限元和实验的方法,对微型机床试验台进行了结构动态特性分析。通过实验测试数据与理论计算结果对比分析,验证了有限元模型的合理性,并对测试及计算中造成误差的因素进行了讨论,为后续的微小型化机床系统动力学研究奠定基础。     

机器人柔性抛光机床的力控制系统的建模与辨识

机器人柔性抛光系统中,力控制系统是重要的组成部分.力控制系统对抛光加工性能有重要的影响,直接关系着抛光质量.该力控制系统实际上是一个闭环的交流伺服系统,对力控制系统的建模为抛光系统的动态和静态性能分析提供了理论基础.     

Axis geometrical errors analysis through a performance test to evaluate kinematic error in a five axis tilting-rotary table machine tool

Geometrical work piece errors in milling process are commonly generated by different error sources. Axis geometrical errors, such as the straightness error for linear axis and the offset location error of the origin of rotary axis, introduce kinematic error in the tool path. Direct measurement of kinematic error requires special devices such as laser interferometers, grid plate encoders or double ball bars, which impose production stop and specialized staff. These problems could be analyzed using indirect measurements obtained by means of a cutting performance test that is already a standard for three axis machine tools. Because of the different architectures of five-axis milling machines these tests are hardly standardizable, therefore this paper proposes a devised easy-to-use and time efficient cutting performance test to identify and quantify axis geometrical errors for a five axis tilting-rotary table machine tool. This test can be performed as a periodical checkup or, in case of production, as a re-start test. The main goal of this study is to develop a kinematic analytical model capable of correlating the work-piece geometrical errors to the axis geometrical errors of the machine tool. The model has been implemented on a multi-body software in order to simulate the axes motion sequence of the performance test and validated to decouple the kinematic error into the geometrical axis errors. The developed models have demonstrated to be capable of correcting a generic five axis tool path by predicting the tool-path error displacement. The overall validation of this approach has been carried out by comparing the simulated and experimentally measured profile of the NAS 979 standard five axis contouring cone frustum profile.     

机床的进给驱动(下)

提出了设计高端机床进给驱动的若干原则.分析了滑动和滚动导轨的结构形式及其优缺点.讨论了不同直线进给和圆周进给的结构形式及其发展趋势.最后对保证进给运动精度的测量传感系统作了全面的介绍.     

双摆头自动交换技术研究

具有自动换头功能的五轴联动加工中心为近年来重要的发展趋势,其应用可满足复杂曲面、复杂型腔及特殊工序的加工,使工件在一次装卡后,可完成全部工序或大部分工序从粗到精加工,提高了加工效率和精度。本文针对双摆头自动交换中的机电液耦合、铣头夹紧自锁保护及交换状态监测等关键技术提出了采用电气液快插快换结构、液压夹紧自锁机构、液压流量监测等解决方案,实现铣头自动交换安全可靠,并在实际应用中获得了良好的效果。     

钢轨砂磨及刷光机床的研制

针对某焊轨厂加工处理钢轨的落后现状,提出并设计了一个自动化程度、生产效率、可靠性、可操作性都非常高的除锈机床,并对该机床机械机构部分、液压系统和电气控制部分进行了设计.在对机床的电气控制部分,设计采用了三菱公司的FX2N系列PLC,使得控制稳定可靠,操作简单方便,功能强大.     

带有加工工具的超声复合变幅杆的优化设计

鉴于传统的带有加工工具的超声复合变幅杆求解方法的不准确性,运用有限元法,设计带有加工工具的复合变幅杆,并对其进行动力学分析,包括模态分析、谐振分析;并在此基础上进行优化设计。在保证其突变处工作应力在其材料许用应力范围的前提下,得到其固有频率等于工作频率时复合变幅杆的最佳放大倍数及谐振长度;运用有限元法,分析了工具头的长度,直径对于整个变幅杆谐振长度、放大倍数的影响,为设计更多的复杂形变幅杆提出了一种新的思路。