一种自由曲面抛光机器人轨迹规划方法

针对机器人抛光自由曲面轨迹规划困难,抛光精度不高等问题,提出了一种机器人抛光轨迹规划方法。该方法在UG软件环境下完成对自由曲面的建模,借鉴铣削加工中刀轨生成方法并结合抛光工艺特点,利用等残余高度算法生成抛光轨迹,在此基础上,提出了改进的Douglas-Peucker算法,该算法用于对抛光刀触点的提取,能够将弓高误差控制在给定的范围内,提高抛光精度,最后根据连续抛光刀位点数据求解出机器人各关节转角。实例表明,该抛光轨迹规划方法精度高,可解决自由曲面抛光轨迹规划问题。     

曲面磁力抛光刀具路径规划与驻留时间算法研究

复杂曲面的自动抛光加工方法与效率一直是困扰模具曲面加工的难题,将磁力抛光与数字化测量、控制技术相结合,可以较好地解决曲面抛光加工的效率与自动化问题。参考数控加工理论,对自由曲面加工的刀具轨迹以及轨迹生成算法进行了分析,重点探讨了抛光刀具的驻留时间控制算法。     

自由曲面数控加工刀具轨迹映射算法

对自由曲面的数控加工,寻求最优的刀具轨迹生成方法至关重要。本文基于开源3D库Open CASCADE(OCC)和编程开发环境Microsoft Visual Studio 2010(VS2010),应用B样条表达的自由曲面,采用“投影法”思想,研究“重用已有相似刀具路径”方法,提出了处理自由曲面的NC刀具轨迹映射算法。为了验证算法的有效性和可行性,实验建立5类自由曲面,启动设计的轨迹映射算法,输出曲面的NC加工轨迹质量可以满足设计要求,实现了刀具轨迹的重用。     

数控加工刀位轨迹生成的算法分析

自由曲面数控加工刀位轨迹的自动生成,是CAM技术的关键问题。针对自由曲面零件刀具口路径生成的几种算法,进行了较为详细的分析,并指出了这几种算法各自的加工特点。     

机器人光学自由曲面气囊抛光工具的位姿研究

为了更好实现光学自由曲面的有效加工,根据计算机控制光学表面成型技术原理,将工业机器人与气囊抛光技术相结合,提出一种光学自由曲面加工的新方法。本文首先建立了机器人抛光系统,分析了气囊抛光工具与工件表面的抛光位姿关系,然后根据气囊抛光工具与工件表面的数学关系,提出一种气囊抛光工具的位姿求取算法。在此基础上,以六轴工业机器人为实验平台,对确定的自由曲面进行计算验证,规划出抛光路径,推导了气囊抛光工具姿态控制算法。结果表明,该位姿求取算法满足机器人气囊抛光技术的要求,能够实现理想的抛光工具姿态控制。     

自由曲面数控加工刀具轨迹曲线的一种生成算法

提出一种自由曲面数控加工轨迹曲线计算方法。根据这一方法,可由自由曲面上一定数量的任意分布型值点来 计算曲面加工时的刀具曲线。算法的基本思想是,型值点影响并决定着其控制区域内的曲面形状,这种影响的大小与到 型值点的距离及权指数相关。分别给出了沿X向进给及Y向进给时刀具轨迹曲线的生成算法。讨论了算法中参数选取 对加工曲面形状及拟合精度的影响。     

带倒角平底刀曲面加工无干涉刀具轨迹生成

对自由曲面ＮＣ加工中刀具轨迹生成技术和干涉处理方法进行了分析,以曲面模型→刀具接触点数据→无干涉刀位数据为基本求解策略,研究开发出适用于带倒角平底刀无干涉刀具轨迹生成的新算法。该算法具有干涉检测彻底、处理效率高、稳定性好等优点。     

带倒角平底刀曲面加工干涉刀具轨迹生成

对自由曲面ＮＣ加工中刀具轨迹生成技术和干涉处理方法进行了分析,以同面模型→刀具接触点数据→无干涉刀位数据为基本求解策略,研究开发出适用于带倒角平底刀无干涉刀具轨迹生成的新算法。该算法具有干涉检测彻底、处理效率高、稳定性好等优点。     

基于等照度线的自由曲面轨迹生成法

目前关于自由曲面轨迹生成的算法有很多,但加工效率受所生成轨迹的长度影响,提出一种基于等照度线的自由曲面轨迹生成法,在整体生成轨迹的基础上,考虑局部路径间的残留高度,在根据需要进一步细化,使整体残留高度在误差范围内,减少了总体刀具轨迹的长度,提高了加工效率,通过实例相比较,证明可以获得更高的表面质量。     

面向数控加工的自由曲面区域分割技术

自由曲面主要是通过数控加工实现,数控加工刀具轨迹规划对自由曲面加工的效率和质量有重要的影响。基于区域的刀具轨迹生成策略是通过识别自由曲面上有意义的特征,将具有相似的加工属性的局部曲面分割成相应的区域,这个过程称为区域分割,再以区域为单位自动生成数控加工刀具轨迹。该加工策略的关键技术是区域分割,针对面向数控加工的自由曲面区域分割技术的进行归纳综述,主要分三个部分:面向数控加工的自由曲面区域的概念和分类、区域分割算法、区域分割技术在自由曲面数控加工中的应用。对以上每个方面中涉及的概念和方法进行简短介绍,就学者们所提出的方法的主要优点和缺点进行讨论。在文章的最后,提出了目前该研究领域仍存在的问题,并对发展方向进行了展望。     

Magnetic polishing of three dimensional die and mold surfaces

A new magnetic polishing technology applicable to die and mold manufacturing has been studied using the magnetic polishing tool. The key idea is that magnetic force is used to produce the polishing pressure so that polishing of curved surfaces can be possible without exact control of tool path. This makes the polishing automation of dimensional dies and molds very easy. In this study, experiments have been executed using the magnetic polishing tool and mini CNC milling machine without tool path control. Some mirror-like surfaces have been acquired by two stages of polishing: firstly, wheel type magnetic polishing and, secondly, magnetic abrasive polishing.     

基于游离磨料的机器人抛光工艺实验研究

建立了基于游离磨料和软质抛光工具的工业机器人抛光系统,研究了机器人抛光轨迹的生成方法,并研究了主要工艺参数如主轴转速、轨迹间距和机器人行走速度对表面抛光质量的影响,为确定合理的机器人抛光工艺参数提供了依据。在此基础上对等离子熔射快速制造的金属模具型腔进行了表面抛光实验验证。     

应用于模具自由曲面的新型气囊抛光技术

为提高模具自由曲面抛光的效率和品质,提出一种基于柔性抛光理念的新型气囊抛光技术。建立相应的机器人抛光系统,研究旋转型膨胀气囊抛光工具及抛光过程中各因素对抛光表面粗糙度的影响。对气囊抛光工具的位置和姿态控制问题以及抛光工具,以一定下陷深度和倾斜角度与被抛工件接触时的接触区域的相关特性进行分析。在机器人抛光系统上进行抛光正交试验和试验数据分析,获取表面粗糙度的不同影响因数的最优参数组合,试验中被抛光曲面平均表面粗糙度达到了0.007 μm。研究结果表明,气囊抛光技术可实现抛光工具与被抛光工件的大面积柔性接触,通过气囊内部气压的调节和机器人抛光系统对抛光工具的运动轨迹和姿态的精确控制,可有效地提升自由曲面抛光的品质和效率。     

Development of a robot system for complex surfaces polishing based on CL data

In most cases, polishing work is done by manual labour. It is an extremely laborious operation that demands a lot of time, so it is very expensive. In this paper, instead of manual polishing work, a robotic polishing system is introduced. A trajectory generator needed for generating the robot polishing path is taken from the cutter location data generated from the postprocessor of a CAD system. Using the trajectory generator, the present polishing robot doesn’t need the conventional complicated teaching process. In order to improve the quality of a workpiece surface, a quaternion interpolation algorithm (QI algorithm) between two CL data is also proposed, which can realize the smooth interpolation of robot end-effector positions and orientation. The effectiveness of the proposed polishing method is proven through polishing experiments using an industrial robot, Motoman sv3, and a Motoman XRC Industrial controller.     

Cycloids for polishing along double-spiral toolpaths in configuration space

An automated polishing process of free-form surfaces requires a tool path that covers the entire surface equally and forms an overlapping pattern without visible artifacts. The recently presented double-spiral tool paths assure a coverage of the entire surface with a continuous, non-overlapping path and low variation in distance between adjacent traces of the path. We build upon this approach by constructing cycloids of flexible radii that fill the space between adjacent traces. The use of cycloids mimics the cyclic movement when polishing by hand. The approach operates in a precomputed configuration space (c-space) given in form of an adaptive quadrilateral heightfield mesh. Operating in c-space avoids having to deal with the issues of patch-boundary oscillations or long, stretched triangles in non-uniform rational b-spline surface or triangular mesh representations, respectively. Our algorithm computes appropriate spheroids that are intersected with the c-space to compute the cycloids. We derive a smooth representation of the cycloids using arcs in a rational Bézier formulation. We apply our approach to real-world examples to demonstrate its effectiveness in covering the entire surface with the desired polishing movements.     

Surface quality in milling of hardened H13 steel

In the final milling process of free-form surfaces, commonly employed in the production of molds and dies, knowledge of the cutting conditions and a strategy for choosing adequate processing routes can provide a significant reduction in the manufacturing times. The objective of this work is to evaluate quantitatively and qualitatively the surface quality behavior of a steel used in the production of dies and molds. The analysis was carried out for hardened AISI H13 tool steel inclined at an angle of 60° and for different cutting path orientations. The roughness of milled surfaces was measured and verified by scanning electron microscopy in order to compare the strategies and the surface textures obtained. Four different cutting path strategies were employed in these experiments, with horizontal and vertical single-direction rastering, both upward and downward. The conclusion is that, in the vertical upward strategy, the surface displays greater roughness and an irregularity with regard to plastic deformation. The other strategies showed lower roughness and similar regularity. Magnetic Barkhausen noise, used for sub-surface characterization, was found to be largest when measured along the cutting direction of the inserts. These directions coincided with the directions of greatest plastic deformation in the sub-surface region.     

模具型面快速数控抛光研究

针对模具型面的特点,提出一种快速数控抛光工艺方法.通过对抛光轮和抛光装置的柔性设计,使得与普通数控机床相联的抛光工具能够随着模具表面形貌的变化,作出一定范围内的姿态调节,从而保持了抛光过程的一致性,能够获得均匀的抛光效果.通过抛光实验,初步验证了抛光工具对曲面的加工能力,并从实验数据中总结出抛光加工的去除模型.     

小口径非球面斜轴磨削及磁流变抛光组合加工工艺及装备技术研究

为提高小口径非球面模具加工效率和加工精度,提出一种结合斜轴超精密磨削和斜轴磁流变抛光的组合加工方法,将两种超精密加工方法集成在一台机床上,以缩短装夹时间以及降低装夹误差。研制新型的小口径非球面超精密复合加工机床,对直径Ф6.6 mm的非球面碳化钨模具进行了加工试验。斜轴磨削后加工表面粗糙度达到R_a 6.8 nm,斜轴磁流变抛光后表面粗糙度达到R_a 0.7 nm,面型精度可以达到PV 221 nm。结果表明,所开发的小口径非球面超精密复合加工装备能达到加工要求,可有效提高加工精度和加工效率。     

模具高速加工技术与策略

综述了高速加工技术在模具制造中的应用 ,介绍了模具高速加工对机床、数控系统和刀具的要求 ,重点分析了模具的高速加工工艺和走刀策略     

Modelling of the Polished Profile in Computer-Controlled Polishing by a Sub-Aperture Pad

High-quality part surfaces with high surface finish and form accuracy are increasingly in demand in the mold/die and optics industries. The computer-controlled polishing (CCP) is commonly used as the final procedure to improve the surface quality. This paper presents a theoretical and experimental study on the polished profile of CCP with sub-aperture pad. A material removal model is proposed based on the evaluation of the amount of material removed from the surface along a direction orthogonal to the tool path. The model assumes that the material removal rate follows the Peterson equation. The distribution of the sliding velocity at the contact region is presented. On the basis above, the approaches to calculate the polished profiles are developed for the sub-aperture pad polishing along a straight path and a curved path. The model is validated by a series of designed polishing experiments, which reveals that polishing normal force, angular spindle velocity, feed rate and polishing path all have effects on the polished profile. The result of experiments demonstrates the capability of the model-based simulation in predicting the polished profile.