Improvement of machining quality of copper-plated roll mold by controlling temperature variation

Micro prism film used in LCD industry can be manufactured by roll to roll method with copper-plated roll mold. As copper-plated roll mold is getting larger, pitch error is getting severer. The pitch error drops the quality of micro prism film. The main cause of the pitch error was investigated during machining large roll mold whose machined length was 1 200 mm. The temperature of machining system was elevated during machining roll mold, and this elevation induced thermal expansion of the system. The temperature variation around the roll mold also made thermal expansion of the roll mold. The amount of thermal expansion had strong relationship to the amount of pitch error. Therefore, the roll mold was machined after warming-up of machining system and precise temperature controller around copper-plated roll mold was installed, which minimized the temperature variation. Finally, precise micro prism patterns without pitch error were machined on the large roll mold.     

Derivation of machine tool error models and error compensation procedure for three axes vertical machining center using rigid body kinematics

Volumetric positional accuracy constitutes a large portion of the total machine tool error during machining. In order to improve machine tool accuracy cost-effectively, machine tool geometric errors as well as thermally induced errors have to be characterized and predicted for error compensation. This paper presents the development of kinematic error models accounting for geometric and thermal errors in the Vertical Machining Center (VMC). The machine tool investigated is a Cincinnati Milacron Sabre 750 3 axes CNC Vertical Machining Center with open architecture controller. Using Rigid Body Kinematics and small angle approximation of the errors, each slide of the three axes vertical machining center is modeled using homogeneous coordinate transformation. By synthesizing the machine's parametric errors such as linear positioning errors, roll, pitch and yaw etc., an expression for the volumetric errors in the multi-axis machine tool is developed. The developed mathematical model is used to calculate and predict the resultant error vector at the tool–workpiece interface for error compensation.     

数控车削多面体的误差分析及其补偿

在数控车床上利用旋转的车刀车削多面体时,存在着一定的加工误差,并且,其加工误差的大小与刀具长度成反比,与工件直径成正比.文章提出通过实时改变刀具与工件间中心距的方法来进行误差补偿,并给出了具体的误差补偿公式,而且可以直接应用于数控插补计算.采用这种误差补偿方法可以大大地提高车削多面体的精度,扩大车削多面体的尺寸范围.     

XK714/1数控铣床螺距误差补偿

数控机床的定位精度是影响其高精度性能的一个重要方面,因而也是数控机床验收和检测的重要指标之一。螺距误差是影响定位精度的重要因素,通过螺距误差补偿能够有效改善机床的定位精度和加工精度,对数控机床的使用和维护具有重要意义。对数控机床反向间隙补偿和螺距误差补偿的原理及测量方法进行深入研究,并针对XK714/1数控铣床FANUC 0M系统的螺距误差进行补偿,取得了良好的补偿效果,说明对滚珠丝杆传动机构的反向偏差与螺距误差进行补偿是恢复和提高机床精度的一种重要手段。     

基于FANUC系统的螺纹误差测量与补偿

螺距误差是影响数控机床加工精度的重要因素.根据误差产生原因,介绍数控机床螺距误差补偿的依据和原理;以某一型号数控车床为例,详细说明了利用激光干涉仪实现误差测量及补偿的具体方法.结果表明,该补偿方法能较大程度提高数控机床的加工精度.     

数控车削多面体机床原型系统设计

在分析车削多面体机床对数控系统要求的基础上,对CA6140型车床进行改装,设计了一个原型系统.利用电子齿轮的优势,设计了简单而又满足要求的控制系统,并进行了加工试验,验证了数控车削多面体机床原理的正确性.     

基于跨齿分度法的大型齿轮齿距误差分析及补偿研究

针对成形法加工大型圆柱齿轮中的齿距误差，根据大型齿轮齿距精度的评定方法，分析机床热变形误差、刀具磨损误差及回转台分度误差对齿轮齿距误差的影响，研究齿距分度、连续分度对齿轮齿距误差的影响规律。基于跨齿分度，优化齿轮精加工工序，以降低齿距误差，并对优化效果进行试验验证。结果表明：跨齿分度法可有效降低因机床热变形、刀具磨损、回转工作台分度分辨率导致的齿轮齿距误差，较大幅度提高大型圆柱齿轮齿距的加工精度。     

Simulation of low carbon steel solidification and mold flux crystallization in continuous casting using a multi-mold simulator

An inverted water-cooled multi-mold continuous casting simulator was used to investigate initial solidification of low-carbon steels and crystallization of mold flux. Embedded mold thermocouples showed characteristic temperature profiles dependent on parameters including casting speed, oscillation frequency, and stroke. Higher maximum temperatures for thermocouples at higher casting speeds, higher frequencies, and lower stroke lengths were observed. The surface of the as-cast steel strips showed oscillation marks similar to those of industrially cast slabs and higher casting speeds resulted in shallower oscillation marks. The measured pitch agreed well with the theoretical pitch suggesting the multi-mold simulator to be a cost-effective alternative to pursue fundamental studies on initial solidification in the mold. Analysis of the mold flux taken between the copper mold and solidified steel shell showed highly dendritic uni-directional crystallization occurring within the flux film suggesting that the heat transfer direction is dominantly horizontal towards the water-cooled copper mold. In addition, the solidified flux located at the upper to lower part of the mold suggested morphological differences in the size and shape of the crystalline phases indicating that crystallization ratio can increase depending upon the retention in the mold and subsequently decrease radiative heat transfer as the flux traverses down the mold.     

Optical Film for LED with Triangular-Pyramidal Array Using Size-Reducible Embossing Method

This study presents a modified hot-embossing process to fabricate micro-triangular-pyramidal array (MTPA). First, a tungsten (W) steel mold (as the first mold) is manufactured by precision machining including optical projection grinding, lapping, and polishing processes. The dimension of a triangular pyramid with acute angle of 85° on the W-steel mold is about 300 μm in width and 139 μm in height. The pitch between two triangular-pyramidal tips is about 170 μm. Then, only the portion of the tip area of the triangular-pyramidal patterns is transferred on bulk metallic glass (BMG, Mg₅₈Cu₃₁Y₁₁) using this modified multi-step hot-embossing method to reduce the pattern size. With a position-adjustable mechanism, size-reduced concaved-shaped MTPA can be selectively formed, used as the secondary mold. In this way, not only can the size of triangular-pyramidal patterns on W-steel mold be reduced down on BMG, but also the tool arc between each triangular-pyramid on W-steel mold caused by machine tool can be eliminated. This is based on the fact that amorphous glass alloys contain no dislocation that can be responsible for yielding in crystalline materials. Thus, BMG is expected to be strong and hard enough to be used as a mold material. Then the secondary mold is used to emboss convex-shaped MTPA on PolymethylMethacrylate (PMMA) optical film. Experiments with different embossing times and embossing pressures are conducted and discussed. Large-sized triangular-pyramidal array on the W-steel mold has been successfully and selectively miniaturized on BMG, and then transferred on PMMA. Finally, this optical film of PMMA with MTPA is packaged on light-emitting diode (LED) to improve its lighting uniformity and luminance. In comparison with commercial 3M^™ optical film (3M^™ Vikuiti^™ TBEF2-T-65i), the film with MTPA shows a good optical performance.     

五轴并联机床刀具末端运动位姿自适应控制技术

高精尖领域对精密小零件的加工精度要求越来越高，五轴并联机床作为主要机械加工设备，严格控制机床刀具的运动位姿对于保证成品零件的加工精度具有极其重要的作用。在此背景下，研究一种五轴并联机床刀具末端运动位姿自适应控制技术。在五轴并联机床前方布置两个CCD 摄像头作为视觉系统，拍摄关于刀具末端的左右两张图像；在图像预处理、特征点提取与匹配等环节的基础上，求解位姿参数，包括位置三维坐标以及3个姿态数据。以刀具末端运动实际位姿为输入，利用神经网络获取与刀具末端紧密相连的五轴关节角度补偿量。利用PID控制器，通过补偿量计算位姿控制量不断纠正位姿误差，靠近理想位姿。结果表明：应用所提控制方法，与理想位姿之间的平均误差均更小，且平均误差的波动最小，三维位置坐标波动仅在-0.02~0.015、-0.01~0.02、-0.02~0.02 mm之间；横滚角、俯仰角以及方位角波动仅在-0.02°~0.03°、-0.01°~0.04°、-0.02°~0.01°之间，由此说明所提控制方法的精度更高，控制稳定性更高。     

Injection molding of micro patterned PMMA plate

A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications, was selected as a model pattern. The prism pattern is 50 μm in pitch and 108° in the vertical angle. The overall size of the plate was 335 mm×213 mm and the thickness of the plate varied linearly from 2.6 mm to 0.7 mm. The prism pattern was firstly machined on the nickel plated core block using micro diamond tool and this machined pattern core was installed in a mold for injection molding of prism patterned plate. Polymethyl methacrylate (PMMA) was used as a molding material. The pressure and temperature of the melt in the cavity were measured at different positions in the cavity and the replication of the pattern was also measured at the same positions. The results show that the pressure or temperature profile through the process depends on the shape and the size of the plate. The replication is affected by the temperature and pressure profiles at the early stage of filling, which is right after the melt reaches the position to be measured.     

面向高速钢轧辊材质磨削的磨床电解磨削装置控制系统研发

针对高速钢轧辊材质的修复问题,展开高速钢轧辊材质电解磨削装置控制系统研发工作。基于普通外圆磨床的机床,以S7 200 SMART系列PLC为控制器对阴极进给系统、电解液供液系统和加工系统进行控制。其次,展开高速钢轧辊材质电解磨削装置控制系统的硬件、软件以及人机交互设计,该控制系统具有自动对刀、故障检测等模块化功能。再者,对加工间隙控制提出了一种带修正因子的模糊控制器-PI双模控制方法,建立MATLAB/Simulink仿真模型,其结果表明该控制方法效果理想,鲁棒性强,可整定控制器增益参数,并将该算法编程于PLC中,最终可实现加工间隙控制过程稳态误差小、超调小、响应快、稳定性好。最后,展开预实验,探究了加工间隙以及温度对加工电流的关系,结果表明加工电流随加工间隙的增加而减小,随温度的升高而增加。     

工作辊擦辊器的机械加工

工作辊擦辊器的上、下擦辊梁在加工中存在工件易变形、堆焊合金层厚度均匀性要求高、槽加工难度大等问题。对工件的工艺流程和机械加工工艺进行了合理的安排,优化生产工序,使加工工艺满足了设计要求,保证了产品质量和生产进度。     

基于Sinumerik 802D s1系统的模具型腔数控加工研究

Sinumerik 802D s1系统是目前广泛应用于模具数控加工领域的数控系统之一,本文以该系统为基础对手机模具型腔数控加工程序工艺编制、机床后处理文件编写和零件加工表面质量控制方面进行研究,可为同类型零件的数控加工提供参考。     

降低精密数控车床进给轴热误差对切削精度影响的方法

精密数控车床批量加工零件的精度稳定性是衡量机床性能的重要指标,其中加工过程中的进给轴受热伸长是影响加工精度的重要因素之一。对数控车床进给轴热变形方向及伸长量进行研究,对比丝杠预拉伸及数控系统热误差补偿功能,指出这两种降低进给轴热误差方法局限性,提出一种使用中空油冷循环系统降低进给轴热误差的方法。该中空油冷循环系统,一方面通过中空丝杠内循环的冷却油带走丝杠螺母的发热量,另一方面通过轴承室内循环冷却油带走轴承的发热量。进行了系统结构设计与实验验证,结果表明该系统可以使进给系统在加工时保持温度稳定,降低热误差,进而提升批量加工的精度稳定性。     

基于UG连接杆模具型腔电极设计与数控加工

为提高型腔模具电极设计与数控加工的效率和质量,提出了一种优化的设计方法。以型腔模具高效率、高质量电极设计与数控加工为目标,结合企业生产实际,采用单一使用UG建模命令的万能方法进行电极设计,采用优化的数控,h~．．Y--．Y--艺进行电极数控加工编程,并采用自定义的后处理文件生成了相应数控系统的数控代码。     

模具曲面光整加工中数字化磁力研磨技术

本文针对模具制造过程中模具表面的自动化研磨光整加工的问题，介绍了一种数字化磁力研磨技术。简述了其原理，详细论述了数字化研磨三维加工模型的获得、工艺参数的选择、数字化研磨轨迹的生成方法以及专用和改装的数字化磁力研磨设备等关键技术，证实利用数字化磁力研磨可以对模具曲面进行有效地自动化光整加工。     

结晶器固态渣膜形成过程及传热研究

通过自制的模拟铜结晶器实验装置,模拟结晶器固态渣膜的形成过程,研究无氟渣膜形成过程中渣膜状态及热流密度的变化,并利用扫描电镜、X射线衍射仪研究了渣膜的微观结构及结晶矿物。结果表明,随着模拟铜结晶器实验装置浸入渣液时间的延长,结晶器壁渣膜呈逐渐增厚的趋势,晶体质渣膜的成长速度比玻璃质渣膜要快得多,且固态渣膜形成过程中结晶矿物种类不变;穿过固态渣膜的热流密度呈下降趋势,尤其在浸入渣液25 s内,热流密度的下降趋势更为显著;渣膜传热是固态渣膜中的气孔、结晶率和渣膜厚度三方面因素综合作用的结果。     

数控机床中螺距误差补偿原理及测量方法研究

文章对数控机床反向间隙补偿和螺距误差软件补偿原理及测量方法进行深入的研究,提出一种高效、快速螺距误差测量和补偿值设定方法,并进行了具体实例应用。实践证明该检测方法操作简单方便,测量结果正确可靠,特别适合我国国情,可以满足生产企业数控机床定期螺距误差检测、及时校正反向间隙和机电联调的需要,能有效改善机床定位精度和加工精度,对数控机床的合理使用和维护具有重要的实用参考意义。     

再制造双圆弧齿轮单齿切削机床设计

目前抽油机减速器双圆弧齿轮使用一段时间后会出现单个齿破损或多个齿间隔破损的情况,现有的修复方法效率低。针对这种情况,提出设计一种对修复后的再制造双圆弧齿轮进行再加工的切削机床,验证再制造双圆弧齿轮单齿加工的可行性。结合再制造双圆弧齿轮单齿展成加工理论,对单齿加工机床的刀具运动部件、齿向螺旋进给部件、齿形展成进给部件以及工件运动部件进行设计,最终得到满足加工要求的再制造双圆弧齿轮单齿切削机床。分析再制造双圆弧齿轮单齿加工的误差后,提出一种减小再制造双圆弧齿轮轴向齿距误差的方法。