PRS-XY型混联数控机床系统软件开发

结合PRS-XY型混联机床结构特点,采用以"PC Turbo PMAC"为硬件平台,以Windows XP操作系统为软件平台,构建了开放式混联数控系统的总体方案;并介绍了数控系统控制结构和系统软件各模块的设计.通过本软件成功构建了一种混联数控机床的控制体系,可以实现与普通数控机床相同的加工功能及机床控制功能,且控制可靠,运行良好.     

BF-850B立式高速数控机床精度检测及误差补偿研究

机床在加工的过程中会因为物理变形和热变形,使得加工零件的精度难以保证,因此必须对运动中的影响机床精度的误差源进行误差分析及实时补偿。利用激光干涉仪和球杆仪对数控机床定位精度进行检测,并建立了关于机床变形的检测数据的数学模型,确定了定位误差补偿方法,同时以具体的数控机床为例进行了定位精度检测与误差补偿,最后对补偿效果进行了分析。结果表明：该定位误差检测及补偿方法具有可行性与实用性,使数控机床的定位精度得到了显著的提高。     

PRS-XY型混联机构运动学分析和运动控制

在研究PRS-XY型混联平台结构的基础上,建立了该机构的运动学模型,通过逆运动学解析,给出PRS-XY型混联平台的运动控制算法,导出了计算实轴位置的运动学公式.阐述了PRS-XY型混联加工平台的控制过程,提出了在基于Turbo PMAC平台的数控系统中将粗插补和运动学算法下载到Turbo PMAC卡中运行的方法,可以提高机构运动的在线实时控制能力,该方法也可用于其它类型并联机构或机床的控制.     

基于球杆仪的数控机床误差识别与补偿

论述了数控机床几何误差的球杆仪识别及软件补偿技术。提出了从Renishaw球杆仪测量数控机床的联动误差数据中识别反向间隙、直线度、垂直度、定位误差的一种方法;建立了机床结构的每个误差元和切削刀具相对工件位置误差相联系的通用数学模型;用球杆仪在数控机床上进行补偿前后加工轨迹的测量实验表明该方法效率高、效果显著。     

三自由度混联机床的机构误差分析与仿真

文章提出了一种新的三自由度混联机床构型,基于Solidworks建立其三维实体模型.利用误差独立作用原理,建立了误差分析数学模型.通过矩阵分析方法结合运动学徽分方程,分析了并联机床静态误差,得到固定平台校链点位里误差、驱动杆长度误差与运动平台位里误差的映射关系,并对机构误差在工作空间内的分布规律进行了仿真,为混联机床的误差补偿提供了理论基础.     

混联码垛机器人误差分析

论文以所研制的串并联混合的MJR混联码垛机器人为研究对象,介绍了四自由度垂直移动关节与回转关节组合式串并联的混联机器人机构特点,并进行了运动学分析,提出了这种机器人的误差分析方法,利用摄动法建立了广义坐标偏差和结构偏差对机器人末端位姿影响的误差模型,并通过数值仿真分析了广义坐标偏差和结构偏差对机器人末端位置误差的影响程度,计算结果证实了位姿误差模型的正确性,为机器人的位置误差补偿及精度优化设计提供了依据.     

3PRS-XY混联型并联运动机床数控系统研究

设计了基于“Pc＋Turbo PMAC”开放模式的数控系统,实现3PRS-XY混联型并联运动机床的运动控制。利用Turbo PMAC开放的运动学计算功能,将运动学变换计算嵌入到Turbo PMAC中,在Turbo PMAC中完成轨迹粗插补,提高了控制系统的实时性和可靠性,降低了系统的开发周期。     

基于FANUC的进给运动误差补偿方法

运动误差是数控机床最常见的一种误差形式，通过日本FANUC数控系统的例子，说明不但可以调整机床硬件结构消除该误差，还可以通过设置机床参数来补偿。     

提高轮廓加工误差联机检测精度的研究

在数控机床或加工中心上采用联机检测轮廓加工误差的方法，不用价格昂贵的坐标测量机，具有简单、省时、经济的特点。文章分析了数控机床或加工中心的直线运动误差对联机检测轮廓加工误差精度的影响，并测量出了加工中心的几何运动误差，提出了消除机床几何运动误差影响，提高轮廓加工误差联机检测精度的方法。实验结果表明，所采用的方法可以明显提高轮廓加工误差联机检测精度。     

基于球杆仪的VMCL600型立式加工中心精度检测与分析

基于球杆仪的误差检测原理,通过球杆仪检测VMCL600型三轴立式机床5个不同位置的误差,找出影响该型号加工中心几何精度的主要因素是垂直度误差、y轴和x轴的反向间隙、比例不匹配误差等。分析了这些误差产生的原因、对加工精度的影响并提出相应的解决措施。     

Geometric error measurement and identification for rotary table of multi-axis machine tool using double ballbar

In this paper, comprehensive geometric errors, including linkage errors and volumetric errors, of a rotary table are measured totally by employing a double ballbar and obtained by a two-step identification procedure. The derivations of the center of the ball installed on the table are measured in the error sensitive directions with newly developed serial of two axes controlled circular paths. Hence, there are nine results measured from three mounting positions of the ball at the same rotation angle. These results are used to form the identification model based on the homogeneous transformation. Moreover, a sensitivity analysis method is applied to select the optimum installation parameters of the ballbar to diminish the influence of the inaccuracy of the measurement parameters. As the mounting position errors of the socket on the table are inevitable during the installation of the balls, a new correction procedure is developed as well. Finally, an experiment is conducted on the four-axis machining center. The comparison results between the predicted errors and the measured results are shown to verify the proposed method.     

基于SAPSO-GA算法的高速曲轴随动数控磨床几何误差辨识方法

以某型数控曲轴磨床作为研究对象,对其结构和运动进行分析,推导出曲轴磨削时理想的砂轮轨迹方程。根据多体系统理论建立含有误差参数的模型,并推导出机床-工件和机床-刀具的运动链位置矩阵,得出机床精密加工的约束方程。对磨床的几何误差进行研究,建立几何误差模型。为快速、准确辨识出各项几何误差,提出一种混合SAPSO-GA算法。通过对比球杆仪测量补偿前后的运动轨迹,分析补偿效果。结果表明:所提方法提高了辨识准确性,通过补偿大大提高了曲轴随动磨床的加工精度。     

基于空间样条曲线的数控五轴机床误差辨识研究

在划分球杆仪空间误差辨识区域的基础上,基于NUBRS空间样条曲线生成辨识轨迹。分析球杆仪空间辨识原理,并依据此原理建立适用于NUBRS空间曲线的误差辨识模型,该模型包含18个误差因素。依据五轴机床多体运动学的分析结果,提出了一种空间误差辨识方法。通过激光干涉仪的测量及误差补偿,在消除9项空间位移误差的基础上,使用生成的NURBS曲线对剩余9项角度误差因素进行辨识。经实验验证,在进行NUBRS曲线修正后,该方法可有效辨识出3个坐标系中的18项误差因素。     

Total ballbar dynamic tests for five-axis CNC machine tools

The linear and rotary axes of a five-axis machine tool are driven simultaneously to generate a specified tool position and orientation in workpiece coordinates. It is crucial that these servo-controlled axes are of balanced dynamics to achieve high tracking accuracy. In this paper, ballbar circular tests for all possible combinations of linear and rotary axes of a five-axis machine tool are investigated and total ballbar dynamic tests are proposed. Through the relational arrangement of the test sequence, the total ballbar dynamic tests can be employed to identify dynamic differences between linear and rotary axes. More importantly, the velocity gains of the position control loops of all servo-controlled linear and rotary axes can be tuned synchronously to eliminate gain mismatch errors. Experimental results have proved the effectiveness of the new methods.     

Double ballbar test for the rotary axes of five-axis CNC machine tools

In this paper a new method that uses the double ballbar to inspect motion errors of the rotary axes of five-axis CNC machine tools is presented. The new method uses a particular circular test path that only causes the two rotary axes to move simultaneously and keeps the other three linear axes stationary. Therefore, only motion errors of the two rotary axes will be measured during the ballbar test. The theoretical trace patterns of various error origins, including servo mismatch and backlash, are established. Consequently, the error origins in the rotary block can be diagnosed by examining whether similar patterns appear in the motion error trace. The method developed was verified by practical tests, and the servo mismatch of the rotary axes was successfully detected.     

Microcladding of hypereutectic Al–Si alloys: technological aspects and structure features

Abstract

This study aims to investigate the technological possibility to generate high precision microrange structure from aluminium alloys using laser microcladding. Clad tracks of Al–Si alloys with different silicon contents with lateral resolution of ～200 μm were produced using co-axial laser microcladding. Particle size distribution with surface morphology and microstructure of the initial powders were investigated. Mechanisms of structure formation in Al–Si alloys during laser microcladding were studied. It was revealed that the chemical composition of the powder material influences the structure formation process and microhardness of hypereutectic Al–Si alloys produced by microcladding. In addition, the effect of processing parameters on the microstructure and geometry of the resulted tracks is discovered. The conclusions on technological possibility of manufacturing the single tracks with width of <500 μm from hypereutectic Al–Si alloys were made.     

轧制吹扫喷嘴结构仿真优化

为优化吹扫用喷嘴内部结构,改善吹扫效果,运用CFD软件对几种典型结构的喷嘴的内部流动进行了有限元仿真,得到了相应的流动特性参数等结果。对比分析了仿真结果,结合各种结构的加工工艺性,提出了渐进抛物线型截面的喷嘴结构方案。最后通过试验数据,证明了采用该结构的喷嘴具有一定的优越性。     

The foundations of a new approach to additive manufacturing: Characteristics of free space metal deposition

In this paper, we report on the realisation of a free space deposition process (FSD). For the first time the use of a moving support structure to deposit tracks of metal starting from a substrate and extending into free space is characterised. The ability to write metal shapes in free space has wide ranging applications in additive manufacturing and rapid prototyping where the tracks can be layered to build overhanging features without the use of fixed support structures (such as is used in selective laser melting (SLM) and stereo lithography (SLA)). We demonstrate and perform a preliminary characterisation of the process in which a soldering iron was used to deposit lead free solder tracks. The factors affecting the stability of tracks and the effect of operating parameters, temperature, velocity, initial track starting diameter and starting volume were measured. A series of 10 tracks at each setting were compared with a control group of tracks; the track width, taper and variation between tracks were compared. Notable results in free space track deposition were that the initial track diameter and volume affected the repeatability and quality of tracks. The standard deviation of mean track width of tracks from the constrained initial diameter group were half that of the unconstrained group. The amount of material fed to the soldering iron before commencing deposition affected the taper of tracks. At an initial volume of 7 mm³ and an initial track diameter of 0.8 mm, none of the ten tracks deposited broke or showed taper > ∼1°. The maximum deposition velocity for free space track deposition using lead-free solder was limited to 1.5 mm s⁻¹.     

液滴在双轨亲水轨道上的运动特性研究

目的 探究重力驱动液滴在双轨亲水轨道上的运动特性,揭示其力学机理。方法 采用喷涂法制备不锈钢超疏水表面,然后采用激光刻蚀法在超疏水表面上加工出不同类型的亲水轨道。研究液滴在不同轨道上的运动行为,讨论液滴运动状态与轨道参数之间的关系,并对液滴运动的力学特性进行分析。结果 液滴在平行双轨轨道上的运动阻力约为在单轨轨道上的1.6~2.4倍,其与轨道宽度呈正相关,与轨道间距呈负相关,且液滴运动终止时呈现出轨道中途停滞、轨道末端停滞、脱离轨道末端三种状态;液滴在非平行双轨轨道上的运动阻力与运动方向有关,由宽端至窄端的运动阻力较由窄端至宽端更小,前者约为后者的90.7%。结论 液滴在轨道上的运动阻力主要受液滴与亲水轨道的接触面积影响。当平行双轨轨道的间距增大时,液滴在垂直轨道的方向上拉伸效果增强,液滴将沿平行轨道的方向收缩,铺展长度减小,由此液滴与亲水轨道的接触面积减小,从而降低了液滴运动阻力;而液滴在非平行轨道不同运动方向上的阻力差异与液滴的表面张力有关。     

生物质压缩成型工艺参数

以玉米秸秆、锯末、棉杆为原料,进行改进后热压缩成型工艺试验,通过松弛密度这一指标得到最佳工艺参数范围;并利用OLYMPUS BX51-金相显微镜观察玉米秸秆成型后颗粒的微观形貌,从微观角度研究成型工艺参数与成型块微观结构之间的关系。试验结果表明,最佳参数范围是,粒度0～2mm、含水率15%～23%、温度130℃～150℃、长径比5.28;以玉米秸秆为例,微观形貌分析得出的最佳工艺参数范围与试验得出的基本一致。