高精加工中的刀具夹持技术

本文综述了高精加工中用的刀具夹持技术,同时提出了在实际应用中如何正确选择刀具夹持系统的看法。     

Superhigh-speed extrusion of tungsten-free electrodes for electrospark alloying of steel 45

A production technology for tungsten-free electrodes with boron-bearing mineral additives has been developed; the electrodes are intended for use in electrospark alloying. The optimal electrospark alloying conditions and the composition of the alloy layers produced are determined.     

Optimal basing of high-precision parts in machining

Russian Engineering Research -     

淬硬钢的高速、高精度硬切削

聚晶立方氧化硼(PCBN)刀具代替磨削刀具使用于硬加工,但是由于加工过程中安全性的缺点到目前尚不能用于淬硬钢的高速和高精度加工。现在新开发的刀刃材料和变化的进给速度新工艺使这类刀具的应用成为可能。     

Multifunctional equipment for machining gas-turbine components

A multipurpose grinding and milling center for machining the blades of gas-turbine engines is described. The characteristics of a prototype Russian SXS735TC2 multifunctional system are presented. The individual components of the system are analyzed.     

Investigate the spindle errors motions from thermal change for high-precision CNC machining capability

As the demand for high speed and highly accurate machines has significantly increased, error motions from thermal change, which is up to 70 % of the total machining error, is found to be the main hurdles to overcome in improving the accuracy of CNC machine tools. In this research work, the authors installed four eddy current displacement sensors in the spindle structure near to the front bearing to monitor the spindle offset in the bearing level, which is mainly attributable to the thermal error motions of the spindle. In addition, another three capacitance sensors are mounted on the machine table level and aligned with the x-, y-, and z-axis of the machine to monitor the spindle shift in the table level to find out the correlation between temperature change and the thermal error motions of the spindle. To measure the temperature changes, we attached thermal sensors in the machine and cooling system. The estimation of the spindle thermal displacement based on temperature data from these thermal sensors can provide more information for the monitoring of thermal error motions of the spindle.     

Wear studies in precision machining of graphite

Tool wear in the precision machining of graphite is comparatively high. The purpose of the work described in this paper is to limit tool wear by controlling factors such as cutting speed, depth of cut, and workpiece temperature. The relative importance of these factors has been assessed in developing a generalised tool wear equation     

飞机结构零件数控加工技术研讨

随着我国航空制造技术的发展，对飞机结构零件的加工要求越来越高，尤其是对于零件的表面质量、深腔和薄壁形状以及零件的加工精度都提出了更高的要求。目前欧美许多发达国家按照高精度、高效率、高柔性的制造发展方向，已开始普遍使用高速铣削机床，并针对飞机结构零件的特点进行了大量的工艺技术研究。另外通过对难加工材料的加工工艺方法进行研究，大大提高了以钛合金为代表的难加工材料的加工效率，使飞机结构零件的数控加工不再成为制约整个飞机研制和生产的“瓶颈”。     

某塑料模具的石墨电极数控加工工艺

分析石墨电极数控加工的特点和难点,应用Mastercam数控加工技术,采取适当的工艺措施和合理的工艺路线,完成石墨电极的数控加工。     

Modelling and experimental investigation of spindle and cutter dynamics for a high-precision machining center

The geometric quality of high-precision parts is highly dependent on the dynamic performance of the entire machining system, which is determined by the interrelated dynamics of machine tool mechanical structure and cutting process. This performance is of great importance in advanced, high-precision manufacturing processes, including aerospace and biomedical applications. In this paper, the dynamics of the combined spindle/cutter system, a major component of any machine tool, is identified using impact testing techniques and is successfully approximated by a second-order linear model. Results of computer simulations of machining processes that include the identified spindle/cutter dynamics show a significant influence on the quality of the final product. From this, it is concluded that, for precision workpieces, the dynamics of the spindle and cutter system will have to be taken into account in order to improve future machining controls and processes.     

Implementation of the principal-axis method for machining of complex surfaces

In this paper a new strategy for 5-axis machining of complex surfaces is presented. The method uses curvature alignment and matching between the design surface and the cutting tool to improve surface finish and reduce machining time. The method is implemented on two configurations of 5-axis machines, and used to machine a test surface. The results of the tests show a considerable improvement over conventional 3-axis machining.     

Abrasive-jet machining of large hollow components

Analytical formulas are derived for the internal surface characteristics of a large cylindrical workpiece after treatment by an abrasive–air jet as a function of the machining conditions. A formula for the productivity is also presented.     

Manufacture of mandrels for the production of composite components by coiling

The manufacture of sand–polymer shaping mandrels for the production of composite components by coiling is considered.     

加工中心及数控铣床配套功能部件产品评述

在国家“十一五”规划的开局之年，上海新国际展览中心迎来了CCMT 2006中国数控机床展览会。本届展会是对我国“十五”机床工具工业成果的一次大展示。展会上展出了一大批高水平的数控机床的功能部件。     

An experimental investigation on micro machining of fine-grained graphite

Industrial applications of the micro milling process require sufficient experimental data from various micro tools. Research has been carried out on micro milling of various engineering materials in the past two decades. However, there is no report in the literature on micro milling of graphite. This paper presents an experimental investigation on micro machinability of micro milling of moulded fine-grained graphite. Full immersion slot milling was conducted using diamond-coated, TiAlN-coated and uncoated tungsten carbide micro end mills with a uniform tool diameter of 0.5 mm. The experiments were carried out on a standard industrial precision machining centre with a high-speed micro machining spindle. Design of experiments (DoE) techniques were applied to design and analysis of the machining process. Surface roughness, surface topography and burrs formation under varying machining conditions were characterized using white light interferometry, SEM and a precision surface profiler. Influence of variation of cutting parameters including cutting speeds, feedrate and axial depth of cut on surface roughness and surface damage was analysed using ANOVA method. The experimental results show that feedrate has the most significant influence on surface roughness for all types of tools, and diamond tools are not sensitive to cutting speed and depth of cut. Surface damage and burrs analysis show that the primary material removal mode is still brittle fracture or partial ductile in the experimental cutting conditions. 3D intricate micro EDM electrodes were fabricated with good dimensional accuracy and surface finishes using optimized machining conditions to demonstrate that micro milling is an ideal process for graphite machining.     

Focused ion beam-shaped microtools for ultra-precision machining of cylindrical components

Focused ion beam (FIB) sputtering is used to shape a variety of cutting tools with dimensions in the 15–100 μm range and cutting edge radii of curvature of 40 nm. The shape of each microtool is controlled to a pre-specified geometry that includes rake and relief features. We demonstrate tools having rectangular, triangular, and other complex-shaped face designs. A double-triangle tip on one tool is unique and demonstrates the versatility of the fabrication process. The FIB technique allows observation of the tool during fabrication, and, thus, reproducible features are generated with sub-micron precision. Tools are made from tungsten carbide, high-speed tool steel, and single crystal diamond. Application of FIB-shaped tools in ultra-precision microgrooving tests shows that the cross-section of a machined groove is an excellent replication of the microtool face. Microgrooves on 40–150 μm pitch are cut into 3 mm diameter polymer rods, for groove arc lengths greater than 12 cm. The surface finish of machined features is also reported; groove roughness (R_a) is typically less than 0.2 μm. Ultra-precision machining of cylindrical substrates is extended to make bound metal microcoils having feature sizes of 20–40 μm.     

Electrical discharge machining of submicron holes using ultrasmall-diameter electrodes

We have carried out the electrical discharge machining (EDM) of submicron holes using ultrasmall-diameter electrodes. Two types of electrode were used: tungsten electrodes fabricated by the combination of wire electrodischarge grinding and electrochemical machining, and silicon electrodes originally designed as probes for scanning probe microscopes. The diameters of the former and latter were 1 μm or less, and less than 0.15 μm, respectively. Holes were drilled using a relaxation-type pulse generator at an open-circuit voltage of less than or equal to 20 V with the machine's stray capacitance as the only capacitance. Using tungsten electrodes, holes of less than 1 μm in diameter and more than 1 μm in depth were successfully drilled. A 1.3-μm-wide slot was also fabricated by drilling many holes with a small pitch. It was possible to drill holes of approximately 0.5 μm diameter using silicon electrodes because the electrode diameter was less than those of the tungsten electrodes. These holes have the smallest reported diameter for holes drilled by EDM, indicating the possibility of submicron- and nanoscale machining by EDM.