CIMT’97主要展品的技术特点综述

两年一度的中国国际机床展览会是国际机床界和我国机械制造业的一件盛事。第五届中国国际机床展览会(CIMT’97)又一次荟萃了国内、外各机床厂及相关配套件厂和工具厂的精华,既可看到一些名牌企业享有盛名的产品,也会发现一些脱颖而出的新秀企业所展示的精品。从展览会上我们能深刻地领会到机床工具行业的发展动向,也能生动地观察到琳琅满目的新产品和新结构。从中既反映了丰富多采的世界先进实用制造技术和最新制造技术,也展示了中国机床工具行业通过“三大战役”在增强开发能力和竞争实力方面所取得的可喜的巨大进步。     

Error budget and uncertainty analysis of portable machines by mixed experimental and virtual techniques

This paper analyzes the error sources of portable machines, which can move along large parts to perform machining operations and defines a mixed virtual-experimental model to quantify such errors. The method combines three different aspects of particular relevance in portable machines: a process force and machine stiffness model, a geometric error model and a machine and work piece inter-referencing error model. The combination of these models helps to control and define the effects of different errors in the virtual mobile machine, before a real prototype is built. An application to a particular portable machine is presented where error values are either simulated or experimentally obtained from a conventional three-axis milling machine where typical strategies of mobile machines are implemented and tested. The research shows that portable machines can be a solution for automatic and unattended machining operations with accuracy requirements below 0.1 mm.     

New tool-workpiece setting up technology for micro-milling

A major issue in micromilling is the setting up with the necessary accuracy the work coordinate system on the machine. The spindle thermal stability during the setting up procedure make this a very difficult task. Thus, it is essential to develop new tool setting up technology to increase the process productivity, reduce machine setting up times and errors, and at the same time improve the precision and quality of machined components. The paper presents a cost-effective and reliable method for setting up the work coordinate system for micro-milling operations employing an on-line tool–workpiece voltage monitoring system. The viability of the proposed method was verified in a series of experiments conducted on an ultra-precision micromilling machine centre. The experimental trials involved the machining of test parts in brass with cutters 100 and 200 µm in diameter. The results of these experiments were analysed and compared with the capabilities of currently available methods and technologies on micro milling machine tools for condition monitoring and setting up the working coordinate systems. Finally, conclusions are made about the effectiveness of the proposed new tool-workpiece setting up technology for micro milling.     

Monitoring and control of tools in multifunctional machine tools

Machining centers and multifunctional machine tools are used in computerized integrated production. They are equipped with a large number of cutting tools for production of a specific batch of parts. In such automatic systems, monitoring and control systems replace the human operator. Monitoring of the state of machining systems is essential today in monitoring and control of the machining operations [1, 2]. It is important to create monitoring systems to support reliable tool operation in multifunctional machine tools. The goals of such systems are to minimize the damage from serious disruption of tool operation and to ensure timely tool replacement. To that end the multifunctional machine tools and/or the numerical control system must be equipped with sensors and various monitoring devices. A strategy must be developed for the prevention of disruption of the machining process and tool failure.     

A method for thermal characterization and modeling of large gantry-type machine tools

In this paper, a method specially designed for the assessment of repeatability and accuracy of large machine tools is proposed, along with results for a large gantry-type milling machine, recorded in a medium-term period. For this purpose, temperatures were recorded and a metrological frame was used along with inductive sensors in the tool tip, performing repetitive measurements. As initial results, origin, weight and influence of every heat source on this kind of machines were found. Afterwards, high precision measurements of thermal deformations were obtained. Mechanism of errors was found, discerning between main thermal error in the vertical Z-axis and secondary error in longitudinal X-axis towards out of the plane of the gantry bridge. Finally, a finite element model was developed which showed main thermal behavior identified experimentally. This will permit to make simulations of the thermal response of the machine and to choose machining strategies for future parts. Proposed methodology was therefore proved satisfactory for thermal characterization of this kind of big machine tools. This knowledge will make possible to improve thermal design of machines and to develop error compensation procedures. This method can also be applied on workshop conditions for recalibration purposes.     

Experimental analysis of change detection algorithms for multitooth machine tool fault detection

This paper describes an industrial application of fault diagnosis method for a multitooth machine tool. Different statistical approaches have been used to detect and diagnose insert breakage in multitooth tools based on the analysis of electrical power consumption of the tool drives. Great effort has been made to obtain a robust method, able to avoid any needed re-calibration process, after, for example, a maintenance operation. From the point of view of maintenance costs, these multitooth tools are the most critical part of the machine tools used for mass production in the car industry. These tools integrate different kinds of machining operations and cutting conditions.     

并联机床高速加工性能分析

论述了并联机床在高速加工中的特点 ,分析了以串联式进给运动为特点的普通机床在高速加工中的局限性 ;提出了高速机床实现的设计要求 ,包括直接驱动技术、轻型复合结构和新机床运动学。对滑块式并联机构作了运动学、动力学和加工精度分析 ,给出了位移、速度和加速度及驱动力曲线 ;最后分析了并联机构在高速机床上的应用需解决的诸如串动和奇异空间问题     

A smart machine supervisory system framework

Machine tools and machining systems have gone through significant improvements in the past several decades. Recent advance in information technology made it possible to collect and analyze a large amount of data in real time. This brings about the concept of a smart machine tool, enabled by process monitoring and control technologies, to produce the first and all subsequent parts correctly. This paper presents a system framework for a smart machine supervisory system. The supervisory system integrates individual technologies and makes overall intelligent decisions to improve machining performance. The communication mechanism of the supervisory system is discussed in detail. Its decision-making mechanism is illustrated through an example that integrates process planning, health maintenance, and tool condition monitoring.     

高速切削刀具材料及其应用

高速切削能加工出精度较高的零件,还能降低加工成本。高速切削技术已经成为最有前途的先进制造技术之一,其应用领域正在持续扩展。高速切削技术是随着刀具技术如刀具材料等的发展而发展起来的。介绍了高速切削中所使用的金刚石、立方氮化硼、陶瓷、金属陶瓷和涂层刀具等的性能、适用范围和发展方向,并介绍涂层刀具、超细晶粒硬质合金和高速钢刀具的制备技术,以促进高速切削技术的推广应用。     

5-axis micro milling machine for machining micro parts

This paper presents a PC-based 5-axis micro milling machine, which can be used for machining micro-sized parts, and be easily constructed a low cost. Micro cutting is a method for manufacturing three-dimensional micro parts; however, machine tools for micro machining are expensive. The micro milling machine presented in this paper is mainly composed of commercially available micro stages, and an air spindle and PC-based control board. An effective method for initializing the spindle position is proposed. Test results of the micro milling machine are presented, which include machining of micro walls, micro columns and micro blades.     

制造技术与装备领域30年来的4大质变

回顾了机床的发展历史,归纳了智能型机床、快速成型加工、并联机床、新型工具等加工方式、设备和工具领域的革命性变化。总结了机床工具领域内国内外发展的最新动态,指出了该领域的发展方向。     

Smart Cutting Tools and Smart Machining: Development Approaches,and Their Implementation and Application Perspectives

Smart machining has tremendous potential and is becoming one of new generation high value precision manufacturing technologies in line with the advance of Industry 4.0 concepts. This paper presents some innovative design concepts and, in particular, the development of four types of smart cutting tools, including a force-based smart cutting tool, a temperature-based internally-cooled cutting tool, a fast tool servo (FTS) and smart collets for ultraprecision and micro manufacturing purposes. Implementation and application perspectives of these smart cutting tools are explored and discussed particularly for smart machining against a number of industrial application requirements. They are contamination-free machining, machining of tool-wear-prone Si-based infra-red devices and medical applications, high speed micro milling and micro drilling, etc. Furthermore, implementation techniques are presented focusing on: (a) plug-and-produce design principle and the associated smart control algorithms, (b) piezoelectric film and surface acoustic wave transducers to measure cutting forces in process, (c) critical cutting temperature control in real-time machining, (d) in-process calibration through machining trials, (e) FE-based design and analysis of smart cutting tools, and (f) application exemplars on adaptive smart machining.     

COMPARISON OF MACHINED SURFACE QUALITY OBTAINED BY HIGH-SPEED MACHINING AND CONVENTIONAL TURNING

The aim of this article is to present some results of investigations on machined surface quality produced by high-speed cutting technologies and conventional turning. Machined surface quality demands significantly affect cost of production and increase the price of a product. Hence, obtaining a good quality of surface while lowering production costs has been metalworkers' preoccupation since beginning their jobs. One possible approach for solving that problem is introducing high-speed machining facilities into production. High-speed machining allows higher productivity, excellent surface finish and good dimensional accuracy in the manufacturing process. Therefore these technologies have considerable advantages over traditional machining technologies. In this article some high-speed machining tests on different materials with different hardness, different machinability index, and by using different experimental approaches have been illustrated. Hard turning and high-speed turn milling, in particular, have been analyzed from the aspect of applicability of these technologies on conventional machines, since these machines still can be found in many manufacturing facilities. Results obtained through these experiments confirmed advantages of high-speed technologies over conventional machining. It has been shown that common production machines, e.g., a universal lathe, in combination with new cutting tools, might be use effectively in some high-speed applications also.     

COMPARISON OF MACHINED SURFACE QUALITY OBTAINED BY HIGH-SPEED MACHINING AND CONVENTIONAL TURNING

The aim of this article is to present some results of investigations on machined surface quality produced by high-speed cutting technologies and conventional turning. Machined surface quality demands significantly affect cost of production and increase the price of a product. Hence, obtaining a good quality of surface while lowering production costs has been metalworkers' preoccupation since beginning their jobs. One possible approach for solving that problem is introducing high-speed machining facilities into production. High-speed machining allows higher productivity, excellent surface finish and good dimensional accuracy in the manufacturing process. Therefore these technologies have considerable advantages over traditional machining technologies. In this article some high-speed machining tests on different materials with different hardness, different machinability index, and by using different experimental approaches have been illustrated. Hard turning and high-speed turn milling, in particular, have been analyzed from the aspect of applicability of these technologies on conventional machines, since these machines still can be found in many manufacturing facilities. Results obtained through these experiments confirmed advantages of high-speed technologies over conventional machining. It has been shown that common production machines, e.g., a universal lathe, in combination with new cutting tools, might be use effectively in some high-speed applications also.     

A heuristic algorithm for the loading problem in flexible manufacturing systems

The paper considers the loading problem in flexible manufacturing systems (FMSs). This problem involves the assignment to the machine tools of all operations and associated cutting tools required for part types that have been selected to be produced simultaneously. The loading problem is first formulated as a linear mixed 0–1 program with the objective to minimize the greatest workload assigned to each machine. A heuristic procedure is presented in which an assignment of operations to machine tools is obtained by solving a parameterized generalized assignment problem with an objective function that approximates the use of tool slots required by the operations assigned to the machines. The algorithm is coded in FORTRAN and tested on an IBM-compatible personal computer. Computational results are presented for different test problems to demonstrate the efficiency and effectiveness of the suggested procedure.     

提高触发式测头在机检测精度

在机检测是保证数控机床加工精度的有效手段。文章系统介绍了触发式测头测量系统的特点及其误差组成，阐述了对在机检测系统及其测量误差修正的技术，最后以实例说明了尺寸误差的反馈补偿的效果。     

一次走刀立铣加工优化与CAM软件开发

研究了数控机床一次走刀立铣加工的计算机辅助优化与CAM软件的开发。基于最大生产率原则建立了数控机床一次走刀立铣加工的优化数学模型,采用数学分析与图形表达结合的方法开发了一种全局优化策略与CAM软件。这种优化策略不仅能够获得全局最优解,缩短优化时间,而且也适用于以最低成本为目标的优化过程。试验验证了该优化策略不仅具有比手册数据更好的经济性,还可以评估及改善机床性能。     

微切削加工技术

在探讨切削技术发展动力的基础上给出了机械加工的尺度划分方法。通过综述微制造技术,介绍了微切削加工装备和微切削刀具,提出了利用应变梯度塑性理论进行微切削机理研究的设想,从分子动力学模拟仿真、最小切削厚度、切屑形态、微切削力、切削温度、工件材料的微量加工性、刀具变形、表面粗糙度与切削稳定性、毛刺、积屑瘤、刀具磨损等不同方面分析了微切削机理的研究现状和存在问题。最后介绍了微铣削CAD/CAM技术,并指出了微切削加工技术的发展趋势。     

Design principles of reconfigurable machines

Reconfigurable machines form a new class of machines that are designed around a specific part family of products and allow rapid change in their structure. They are designed to allow changes in machine configuration according to changes in production requirements. The reconfiguration may be related to changes in machine functionality or its scalability, i.e., the change in production volumes or speed of operation. Reconfigurable machines represent a new class of machines that bridges the gap between the high flexibility and high cost of totally flexible machines and the low flexibility and low cost of fully dedicated machines. The design principles of reconfigurable machines follow a similar philosophy, which was derived for reconfigurable manufacturing systems, and present an approach for the design of machines to be used mainly in high-volume production lines. This paper introduces design principles for reconfigurable machines, which may be applied in different fields of manufacturing. Based on these design principles, three types of reconfigurable machines were designed for various types of production operations such as: machining, inspection and assembly. This paper shows how the suggested design principles were utilized in the design of several full-scale machine prototypes and tested experimentally.     

Scope of in-process measurement, monitoring and control techniques in machining processes—Part 3: In-process techniques for cutting processes and machine tools

In-process techniques for cutting processes and machine tools are surveyed through representative examples. Detection of cutting force and chatter vibration are especially important in cutting processes. As for machine tools, four measuring items will be important which include the driving system, the bearing and rotating systems, the temperature control system, and the monitoring system. They are the primary factors to be taken into consideration for achieving high machining accuracy.