Implementation of a Robot System for Sculptured Surface Cutting. Part 1. Rough Machining

Rapid prototyping plays an important role in product development. There are two ways to realise rapid rototyping: one is to develop new prototyping equipment such as stereolithography apparatus (SLA), selective laser sintering (SLS), etc., and the other is to improve existing CNC techniques. In this work, a robot system for rapid prototyping, which is an enhancement of the CNC based method, is presented. A robot arm holding a milling tool is used to machine the prototype of a solid model drawn using a commercial CAD system. In this paper, Part 1, a strategy using the robot for rough machining is discussed and then an automatic tool-path generation method using a grid height array is presented. This method can generate tool paths for rough machining with different tolerances. As a verification of the proposed algorithm, a number of prototypes have been produced, which have demonstrated the feasibility and advantages of the algorithm. In a companion paper, Part 2, an approach to represent C-space by incorporating possible variations in tooling orientations is proposed. In order to reduce error on complex surfaces resulting from undercut or overcut operations, a curvature-matching algorithm is developed. Finally, experimental work using the collision-free planning strategy and simulation for the curvature matching algorithm is carried out.     

Rapid Sheet Metal Manufacturing. Part 2: Direct Rapid Tooling

The traditional methods adopted for tool design and production in the sheet metal forming industry usually carry a high cost and long lead time resulting in cost justification problems for short production runs. Rapid tooling (RT) technology is capable of justifying the cost of tooling suitable for short production runs or design evaluation purposes. In Part 1 of this work, a new process termed rapid sheet metal manufacturing (RSMM) for the production of soft tooling suitable for prototyping, tool development, and short production runs was introduced. In addition, an indirect RT method employing rapid prototyping (RP), rapid soft tooling, and casting for the fabrication of non-ferrous tools was presented. The current work, Part 2, presents an alternative technique for RSMM whereby metal forming tools are fabricated directly from the RP system via selective laser sintering (SLS).     

基于VC和OpenGL的STL文件的分层和显示

STL文件是快速成型系统的标准文件类型,广泛应用于数控加工、逆向工程和有限元分析等.详细介绍了STL文件的读取和分层算法,并利用VC＋＋6.0平台结合OpenGL编程技术,实现了STL文件格式的读取、分层算法以及STL模型的三维显示、视角变换、缩放、平移和分层显示等功能.为进一步实现数控系统直接使用STL文件进行加工奠定了基础.     

Planar segmentation of data from a laser profile scanner mounted on an industrial robot

In industrial applications like rapid prototyping, robot vision, and geometric reverse engineering, where speed and automatic operation are important, an industrial robot and a laser profile scanner can be used as a 3D measurement system. This paper is concerned with the problem of segmenting the data from such a system into regions that can be fitted with planar surfaces. We have developed a new algorithm for planar segmentation based on laser scan profiles and robot poses. Compared to a traditional algorithm that operates on a point cloud, the new algorithm is shown to be more effective and faster.     

基于CNC的自适应直接分层制造方法研究

将RP技术的增材制造理念与数控铣削加工技术相结合,提出了基于CNC机床的金属零件分层制造方法。为解决等厚分层方法存在的缺陷,提出了基于相邻层面积变化比率和轮廓法向矢量的自适应直接分层算法,并在Pro/E软件平台上,利用Pro/TOOLKIT进行了系统的开发。该方法采用定厚板材作为造型材料,在等厚分层的基础上对分层板进行自适应分层切削,有利于保证成型精度和提高成型效率,为复杂形面功能零件的快速成型制造提供了一种有效的方法。     

双机器人快速原型制造离线编程系统的研制

双机器人快速原型制造离线编程系统主要研究如何自动获取ＣＡＤ模型产生的零件图形的加要数据,并对其进行处理后按机器人的程序格式生成双机器人的加工程序。本文在分析双机器人快速原型加工硬件特点的基础上,建立了双机器人离线编程系统总体结构,研究了各功能模块的关键技术,并用ＩＤＥＦ方法对各功能模块进行了详细设计研制了一套离线编程软件,实现了双机器人加工程序的自动生成。     

基于PC总线的快速成形机高精度CNC系统

详细介绍了基于ＰＣ总线的高精度快速成形机ＣＮＡ系统。该系统结合世界先进的快速成形技术特点，根据开放性体系结构设计思想而完成，具有市场竞争力。系统的开发成功，为快速成形模型建立提供了先决条件。     

WEB-BASED VIRTUAL CNC MACHINE MODELING AND OPERATION

A CNC simulation system based on internet for operation training of manufacturing facility and manufacturing process simulation is proposed. Firstly, the system framework and a rapid modeling method of CNC machine tool are studied under the virtual environment based on PolyTrans and CAD software. Then, a new method is proposed to enhance and expand the interactive ability of virtual reality modeling language(VRML) by attaining communication among VRML, JavaApplet, JavaScript and Html so as to realize the virtual operation for CNC machine tool. Moreover, the algorithm of material removed simulation based on VRML Z-map is presented. The advantages of this algorithm include less memory requirement and much higher computation. Lastly, the CNC milling machine is taken as an illustrative example for the prototype development in order to validate the feasibility of the proposed approach.     

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.     

紫外光快速成形系统扫描策略研究

紫外光快速成形机是国内自主开发的经济型快速成形机，介绍了紫外光快速成形机的光路构成与扫描策略，分析了平面扫描时边界过固化问题的成因及危害，并针对此问题提出了改进的扫描策略。     

陶瓷零件快速成型机数控系统开发

在IPC+运动控制器的开放式数控平台上,结合陶瓷零件快速成型工艺加工过程,构建了硬件系统和软件系统,并进行功能模块的划分以及具体方法的实现,利用VC++语言,设计开发出针对陶瓷模具加工的开放式陶瓷快速成型数控系统.     

Metal Rapid Prototype Fabrication Using Selective Laser Cladding Technology

Non-metallic rapid prototyping has been successfully applied in several industries, but a metal rapid prototype is required for functional prototypes and tooling applications. A metal rapid prototype fabricated using selective laser cladding is presented in this paper. Laser cladding is one type of laser surface treatment process. During this process, an alloy is fused onto the surface of a substrate. Laser cladding devices, i.e. powder feeder, CNC workstation table, laser shutter, and shielding gas controller, were integrated to make automatically any cladding profile possible. The metal prototype was then fabricated layer by layer. This is called the selective laser cladding system (SLC). The fabrication of the metal rapid prototype using SLC technology is described and the detailed design and construction of the SLC is presented in this paper.     

Digital denture manufacturing-An integrated technologies of abrasive computer tomography, CNC machining and rapid prototyping

The orthodontic denture produced by the traditional method is heavily relied on the skill and experience of the technician. Its quality is depended on the accuracy of the technician’s subjective judgment. In addition, the manual process involves many steps that require a long time to complete. Most importantly, it does not preserve any quantitative information for future retrieval.In this paper, a novel device for scanning denture image and reconstructing 3D digital information of teeth models by abrasive computer tomography (ACT) is presented. The orthodontic denture is then to be produced by rapid prototyping (RP) or computer numerical control (CNC) machining methods based on the digital information. A force feedback sculptor (Freeform system, U.S.A.), using 3D touch technology, was applied to modify the teeth profile or features of the denture. It enables the dentist to perform digital manipulation of the denture profile with real-time and interactive operation. Due to its user-friendly human-computer interface, the dentist can directly access the 3-D model without relying on a CAD/CAM technician or denture technician. In this paper, the comparison between traditional manual operation and digital manufacture using RP and CNC machining technology for denture production is summarized.In this paper, a digital denture manufacturing protocol using an economic and harmless computer abrasive teeth profile scanning, computer-aided denture design, 3D touchable feature modification, and numerical denture manufacturing were proposed here. These proposed methods provide solid evidence that digital design and manufacturing technologies may become a new avenue for custom made denture design, analysis, and production in the 21th century.     

双机器人制造系统的网络协作离线编程研究

在分析双机器人快速原型加工硬件特点和基础上,建立了双机器人离线编程系统总体结构,研究了图形数据处理、加工路径规划与仿真和后置处理等关键技术,并用IDEF方法对各功能模块进行了详细设计,研制了一套离线编程软件,实现了双机器人加工程序的自动生成,最后详细论述了用NetMeeting进行双机器人异地协作编程的系统配置和工作过程。     

Inverse dynamics task control of flexible joint robots—I: Continuous-time approach

This paper focuses on the problem of application of inverse dynamics control methods to robots with flexible joints. In Part I of the paper, there are answers presented to a number of questions related to the analytical formulation of nonlinear decoupling control laws. After discussion, the dynamic model of a robot with flexible joints and electrochemical actuators is chosen. The application of the extended computed torque technique together with the methods from the theory of differential-algebraic equations (DAE) to the developed fifth-order robot model gives a number of decoupled linear subsystems, which take robot task space commands as inputs. Due to drawbacks of the continuous-time inverse dynamics, discussed in the paper, a new control strategy in discrete-time is developed in Part II of the paper. The proposed control method is computationally efficient and admits low sampling frequencies. The results of extensive numerical experiments confirm the advantages of the designed control algorithm.     

Data mining algorithm for manufacturing process control

In this paper, a new data mining algorithm based on the rough sets theory is presented for manufacturing process control. The algorithm extracts useful knowledge from large data sets obtained from manufacturing processes and represents this knowledge using “if/then” decision rules. Application of the data mining algorithm developed in this paper is illustrated with an industrial example of rapid tool making (RTM). RTM is a technology that adopts rapid prototyping (RP) techniques, such as spray forming, and applies them to tool and die making. A detailed discussion on how to control the output of the manufacturing process using the results obtained from the data mining algorithm is also presented. Compared to other data mining methods, such decision trees and neural networks, the advantage of the proposed approach is its accuracy, computational efficiency, and ease of use.     

Kinematic chains for robot hands—II. Kinematic constraints, classification, connectivity, and actuation

The work in this paper follows on from Part 1. We now consider the specific example of robot hands and identify several kinematic constraints of these devices. The method for number synthesis of kinematic chains in Part 1 is applied in several different ways in order to synthesise chains suitable for application as robot hands; several examples of the structures so found are presented. So as to identify those kinematic chains that are more promising than others, the new concept of minimal sets of kinematic chains is defined. Another new concept, the variety of a kinematic chain, is defined and used to make generalisations about relative connectivity within kinematic chains, which has application in the selection of actuated pairs. Fractionation of kinematic chains is reviewed in light of the concept of variety. The work presented here has application far beyond the number synthesis of alternative structures for robot hands.     

A new rapid manufacturing process for multi-face high-speed machining

High-speed machining is known as one of the most effective rapid prototyping and/or manufacturing (RPM) processes that provides the various machining materials with excellent quality and dimensional accuracy. However, the high-speed machining process is not suitable for the rapid realization of 3D-shaped product because a considerable amount of time is required for the work piece fixturing process. High-speed rapid prototyping (HisRP), a new type of RPM technology, will be presented in this paper. The proposed HisRP has been developed using a combination of a multi-face high-speed machining process and a flexible fixturing technique. Low melting point metal alloys are used to hold the work piece during multi-face machining. An automatic set-up device, mounted and fixed to the work table, has also been developed to guarantee positional accuracy during a series of multi-face machining operations. This set-up device is expected to be beneficial for successive multi-face high-speed machining of working materials, for example for two-face or four-face machining. The proposed HisRP process has been shown to be a useful method for manufacturing 3D metal products with reduced lead time.