WINDOWS环境下刀片断屑槽型参数化设计的研究

根据刀片断屑槽型CAD的需要，在Windows环境下对断屑槽型的参数化设计做了初步尝试。并介绍了利用AutoCAD在Windows环境下进行断屑槽型参数化设计的基本方法。本图形系统是在AutoCADR12forWindows环境下用ADS图形开发技术编写。     

Evaluation of turbulent forced convection of non-Newtonian aqueous solution of CMC/CuO nanofluid in a tube with twisted tape inserts

The present paper investigates the turbulent flow and heat transfer of non-Newtonian aqueous solution of Carboxymethyl cellulose (CMC) and CuO nanoparticles in a plain tube and also tube with twisted tape inserts. The aqueous solution of CMC and CuO/CMC nanofluid show a shear-thinning (pseudo-plastic) rheological behavior, resulting in a higher viscosity than that of water. The consistency index and the power law index are evaluated based on available experimental data. The single phase approach with temperature dependent thermo-physical properties is applied to simulate the nanofluid flow and heat transfer. Simulation results are presented at different nanoparticle concentrations and twisted tape ratios. Only an axial flow is identified in the plain tube whereas both axial and swirl flows are detected in the tube with twisted tape inserts. The turbulence kinetic energy in the tube with twisted tapes is significantly higher than that in the plain one, which is useful for non-Newtonian fluid with higher viscosity. Also, the temperature fields in the tube with twisted tapes are disturbed relative to those in the plain one, due to stronger turbulence intensity and better fluid mixing. Higher amounts of nanoparticles concentration and lower twist ratios, giving maximum values of total efficiency, display the advantage of using non-Newtonian nanofluid in the tube with twisted tape inserts rather than non-Newtonian base fluid in the plain one.     

An effective sensor for tool wear monitoring in face milling: Acoustic emission

Acoustic Emission (AE) has been widely used for monitoring manufacturing processes particularly those involving metal cutting. Monitoring the condition of the cutting tool in the machining process is very important since tool condition will affect the part size, quality and an unexpected tool failure may damage the tool, work-piece and sometimes the machine tool itself. AE can be effectively used for tool condition monitoring applications because the emissions from process changes like tool wear, chip formation i.e. plastic deformation, etc. can be directly related to the mechanics of the process. Also AE can very effectively respond to changes like tool fracture, tool chipping, etc. when compared to cutting force and since the frequency range is much higher than that of machine vibrations and environmental noises, a relatively uncontaminated signal can be obtained. AE signal analysis was applied for sensing tool wear in face milling operations. Cutting tests were carried out on a vertical milling machine. Tests were carried out for a given cutting condition, using single insert, two inserts (adjacent and opposite) and three inserts in the cutter. AE signal parameters like ring down count and rms voltage were measured and were correlated with flank wear values (VB max). The results of this investigation indicate that AE can be effectively used for monitoring tool wear in face milling operations.     

数控车削仿真中刀具库的设计与实现

在建立基于刀具数据库的数控车削加工仿真系统模型基础上,提出了一种面向该仿真系统的刀具库的设计方法。指出用数据库形式组织刀具数据可以为刀具库管理带来方便。同时,在ＷＩＮＤＯＷＳ９８平台下,以Ｖｉｓｕａｌ Ｃ＋＋５．０及Ｍｉｃｒｏｓｏｆｔ Ａｃｃｅｓｓ９７为开发工具完成了刀具库设计和数字仿真过程对刀具的调用。该软件的设计成功证实了本方法的可行性。     

预埋件对玻璃钢蜂窝夹层结构性能的影响

本文研究了几种不同材料制成的预埋件对某地面雷达天线罩的强度、刚度和电性能的影响,从而说明了天线罩支撑点材料选择的的重要性.     

玩具飞机型芯镶件的数控加工

本文主要介绍飞机玩具型芯镶件在数铣加工过程中,夹具的巧妙运用,详细地讲述了飞机橡胶模具结构,夹具和镶件的加工,镶件在夹具上的装夹。实践证明,通过这种加工方法取得了很好的经济效益,为零件的多面加工提供一个很好的加工思路。     

Hard machining performance of PVD AlCrN coated Al2O3/TiCN ceramic inserts as a function of thin film thickness

In the present work, AlCrN coating was deposited on Al₂O₃/TiCN ceramic inserts with varying thin film thickness using physical vapor deposition (PVD) technique. The thickness, surface morphology, chemical composition, hardness and adhesion strength of the coating to the substrate were characterized by field-emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), micro-indentations and scratch tests respectively. The machining performance of uncoated and coated tools was investigated in hard turning of AISI 52100 steel (62 HRC) under dry environment. The cutting behavior was analyzed in terms of machining forces, tool temperature, wear, friction and chip morphology. Further, a 3D finite element model with hybrid friction criterion has been adopted to support the experimental findings. The results revealed that coating/substrate adhesion and edge radius were the deciding criteria for the machining performance of coated tools with 3 µm coating thickness tool exhibiting best turning performance on Al₂O₃/TiCN mixed ceramic insert.