Friction in aluminium extrusion—Part 1: A review of friction testing techniques for aluminium extrusion

In the aluminium extrusion process, the friction at the workpiece/tooling interface is a highly complex phenomenon, affected by local temperature, relative velocity, contact pressure, geometry and tooling surface roughness, etc. Despite of this understanding, general rules for the selection of friction testing techniques have not been established yet. This paper summarises the recent development of the friction testing techniques for aluminium extrusion processes and detailed comparisons of these techniques are presented. Of the existing friction testing techniques, the combination of extrusion friction tests and short sliding distance ball-on-disc tests is recommended.     

A Mixed Lubrication Model for Computer Simulation of Extrusion Processes

A mixed lubrication/friction model for extrusion process is developed in the present research. The model combines a rigid-plasticity finite element code to simulate the interface condition between the tooling and workpiece in the extrusion operation. The influence of surface roughness on lubricant flow is treated by using the average Reynolds equation. The active lubrication regime and appropriate friction factor were determined from the current local values of interface variables such as mean lubricant film thickness and workpiece and tooling roughness, in addition to the more traditional external variables such as interface pressure, node sliding velocity and strain rate of the workpiece. Numerical results using the coupled code include friction stress and normal pressure under different lubrication conditions are compared with experimental investigation. The discrepancy is very small and the proposed model proved to be very efficient in predicting interface friction condition in the extrusion processes.     

链条压出力研究

压出力是表征链条综合制造质量的重要指标,如何合理确定压出力的大小一直是困扰链条行业的难题之一.将链条压出力与链条额定功率曲线、链条疲劳极限结合起来,提出了链条压出力的确定方法,并据此得到了在疲劳极限载荷作用下不同可靠度的链条最小压出力限值.     

一模多孔铝合金型材牵引技术的应用

采用Solidworks对一模多孔铝型材挤压技术进行了模拟,模拟结果表明:在一模多孔挤压过程中,不同孔的料受力不均匀,左上方受力最大,右下方受力最小;对恒定牵引力7 kN下一模多孔挤压过程进行模拟发现,在牵引力的作用下,各孔料受力变得均匀。基于模拟结果,提出了双头单轨牵引技术的工艺路线,并在14 MN挤压生产线上进行试验,在牵引机作用下,一模多孔铝型材平直,表面质量良好。     

塑料挤出模制造业CIMS

介绍塑料挤出模制造业ＣＩＭＳ的研究背景和基础,结合塑料挤出模制造亚的特点讨论了塑料挤出膜ＣＩＭＳ的关键技术,总体框架设计 和数据流设计,阐述了ＣＩＭＳ实施中应该注意的技术和管理问题。Ｃ     

基于实验Inconel718正交切削有限元仿真分析

为研究犁削效应和前刀面粘压对Inconel718切削过程的影响.基于正交切削实验建立Inconel718有限元切削模型,模型结果同实验值对比以验证模型可靠性.通过改变刀具圆角半径和负前角参数,提取并比较不同的切削力时域曲线和刀具温度,分析犁削效应和前刀面粘压.研究表明犁削效应提高进给力数值,刀具圆角半径由0变为5μm,Inconel718切削进给力均值提高7％：前刀面粘压提高刀具和切屑温度,有利于切屑分离.但刀具负前角为-20＆#176;,切削加工不稳定.     

FEA-aided design of multi-stage drawing process and tooling for production of a miniature sheet metal component

This paper presents the design of multi-stage drawing process and tooling aided by finite element analysis (FEA) for fabrication of a miniature sheet metal component, made of a cold-reduced carbon steel material (SPCC). To design such a tooling, it is essential to figure out how many intermediate drawing steps are needed to produce the final part without deformation defect. First of all, a four-stage drawing process and a set of four-station tooling are designed. This pre-designed process is then analyzed by simulation, and the deformation behavior and formability in each stage is revealed. Based on the revealed deformation behavior and formability, the design of the process and tooling is confirmed. The reasonable drawing ratio and drawing depth in each drawing operation are determined. The size, clearance, and the corner radii of punch and die in each stage are also identified. The designed process and tooling are finally implemented. Through experiment, the “right design in the first time” is realized, and the simulation and experiment are found to have a good agreement. The research further demonstrates that the FEA simulation can be used as an effective tool to aid the design of metal-formed component, tooling, and process in upfront design process.     

新型高速加工工具系统研究进展

综述了新型高速加工工具系统的发展过程、特点及应用情况,着重分析了NC5工具系统的刚度和承载能力、夹紧力、抗颤振能力及刀柄清洁等关键问题,展望了高速加工工具系统的发展趋势。     

精密数控机床铣刀故障监测方法的研究

刀具在加工过程中不可避免的存在着磨损和破损现象,刀具的消耗直接导致工件精度下降和生产成本增加。开展了一系列实验,深入研究刀具状态监测方法,构建了新型铣削过程刀具磨损监测试验系统。通过振动传感器和声发射传感器对铣削过程中不同磨损程度刀具的信号进行检测、采集、分析。选择对刀具磨损状态反映敏感的特征量。采用BP神经网络,建立刀具磨损特征向量与刀具磨损状态之间的非线性映射关系。     

HSK主轴/刀柄接口扭转刚度特性

主轴/刀柄接口性能直接影响零件的加工质量,HSK主轴/刀柄接口克服了传统7/24锥度工具接口在高速切削加工中存在的弊端。HSK工具系统接口的扭转刚度高于同规格的BT工具系统,而高速刀柄和主轴接口在工作中的扭转变形直接影响工具系统的使用性能。运用有限元方法分析了锥面接触和端面接触对接口扭转刚度以及过盈量、夹紧力、转速对扭转刚度的影响。研究结果为高速加工工具系统的设计与合理使用提供了依据。     

花键管挤压成形研究

分析了冷挤压成形花键管的可行性，包括挤压成形的力学计算、摩擦力分析和模具的初步设计。应用模拟分析软件，根据初步的设计结果，模拟花键管冷挤压成形的挤压变形过程，受力状况及应力分布。并根据模拟结果适当改进模具结构。最终进行模具的设计加工和表面磷化皂化处理，有效减小挤压加工过程中的摩擦，在压力机上完成花键管的挤压成形。     

连续变断面挤压工艺的开发

开发出了一种集挤压工艺与电、液、计算机控制技术融为一体的连续变断面挤压新工艺,并以工业纯铝为研究对象,对外形连续变断面挤压工艺进行了试验研究。研究结果表明：根据连续变断面工件的特征参数,通过调节主液压缸和侧向液压伺服系统的参数,无须更换模具,可以成形断面由大到小、由小到大、往复循环的全纤维连续变断面挤压型材或零件。     

Rapid Sheet Metal Manufacturing. Part 1: Indirect Rapid Tooling

Rapid sheet metal manufacturing (RSMM) is a closed loop process for making sheet metal products which uses advanced computer-aided techniques and computer-controlled machines to produce non-ferrous tooling directly or indirectly. The tooling would be suitable for short-run production or design evaluation of sheet metal products for which prototyping cost and lead time are greatly reduced. The key aspect of this closed-loop process is the method used to fabricate and modify the sheet metal forming tool. Various approaches are adopted in the preparation of the tooling for onward embossing on a sheet metal. The three indirect approaches use selective laser sintering (SLS), stereolithography (SLA), and high-speed computer numerical controlled (CNC) milling to build the masters from computer data models. The masters are used in the vacuum casting process to generate the non-ferrous tooling. Comparisons on quality, lead time and cost are presented.     

Big-Plus主轴/刀柄接口径向刚度分析

Big-Plus工具系统不仅与BT工具系统兼容,而且锥面和端面同时定位和夹紧,为高速数控机床重要通用部件之一。Big-Plus主轴/刀柄接口的精度、刚度、可靠性等直接影响被加工零件的质量和加工效率,主轴/刀柄在工况下的径向变形是影响整个工具系统刚度及其性能的重要指标。基于UG/Nastran软件,采用有限元分析方法分别分析了过盈量、夹紧力和转速对接口径向刚度的影响。     

3D printed tooling for vacuum-assisted resin transfer moulding

Three-dimensional printing (3DP) is widely considered to be one of the low-cost additive manufacturing (AM) processes. In this paper, the suitability of 3DP for making tooling for the vacuum-assisted resin transfer moulding (VARTM) process is considered. This combination has potential advantages, since VARTM has significant prototyping benefits if it can be combined with a fast and low cost tooling option. This paper presents a new process chain for the manufacture of closed mould composite parts using the VARTM process. It will be shown that 3DP tooling is significantly less accurate than CNC machined tooling, but there is a cost and time advantage to making tooling with 3DP. The mould life is also limited to typically 15 to 30 parts since significant wear occurs in the manufacturing process. Quantitative data are presented to show the effect of treating the mould surface to improve the surface roughness and to determine the mould life. An aspect often lacking in AM research is cost estimation. Here, the first cost model for rapid tooling for VARTM using 3DP moulds is presented and compared to actual results. It is shown that the model is suitable for design for manufacture analysis.     

Optimal Shape Design of an Extrusion Die Using Polynomial Networks and Genetic Algorithms

Designing the optimal shape for an extrusion die to produce a high-quality extrusion product is often required by industry. Design from experience is unsatisfactory for achieving the flexibility and precision requirements in die design. In this paper, a design method has been developed for the optimum shape design of extrusion die. The extrusion process was modelled and analysed by using the finite-element method to obtain the extrusion force and effective strain for different die shapes. A polynomial network was applied to identify the force and strain models in terms of the geometric parameters of the extrusion die. An improved genetic algorithm was used to optimise the identified model for optimal shape with minimum force and strain. It has been verified that the modelling error is extremely small. The designer can quickly and accurately access the optimal shape of an extrusion die through this new approach. RID=" ID=" <E5>Correspondence and offprint requests to</E5>: Dr Y.-C. Hsu, Department of Mechanical Manufacturing Engineering, National Huwei Institute of Technology, 64 Wun-Hua Road, Huwei, Yunlin, Taiwan. E-mail: jasonych&commat;sunws.nhit.edt.tw     

基于Solid Edge的塑料管材挤出机头零件参数化设计

采用VisualBasic编程语言工具,对三维造型软件SolidEdge进行二次开发,实现了对塑料管材挤出机头的主要零件参数化设计。按照用户选择或输入的不同参数,得到不同尺寸零件的三维实体和相应的变量表,扩展了SolidEdge的功能。     

新型减速齿轮塑性成形工艺研究

针对大模数拖拉机减速齿轮冷挤压时存在变形抗力大、齿腔充填困难、模具寿命低等技术难题,提出了在凹模齿腔深处设置分流型腔法,并结合浮动凹模技术,制订了挤压新工艺,试验结果显示,该工艺不仅能很好地提高充填性能,而且能降低载荷50%,提高了模具寿命。     

发动机壳体热挤压成形模拟及模具设计

针对发动机壳体零件的特点,分析了其热挤压成形工艺,确定了挤压成形工艺参数,并利用数值模拟软件,分析了发动机壳体挤压成形时金属的流动规律和压力行程曲线,从而保证了挤压件的质量,为实际生产提供了理论基础,并以此为依据设计了一套热挤压模具。     

Original models for the prediction of angular error in wire-EDM taper-cutting

Taper-cutting is a common application of the wire electrical discharge machining (WEDM) process used for the production of parts with complex geometry such as extrusion dies in wear-resistant materials, cutting dies, etc. During cutting, the wire is subject to deformation, resulting in deviations in the inclination angle of machined parts. This fact causes dimensional errors and loss of tolerances that can lead to the rejection of high added-value tooling. Currently, WEDM machine manufacturers propose time-consuming experimental trial-and-error methodologies for the correction of the errors. To reduce the experimental load and to contribute a more general approach to the problem, two original models for the prediction of angular error in WEDM taper-cutting are presented here. Results show that part thickness and taper angle are the most influencing variables in the problem. Experimental validation of the proposed models shows that angular error can be reduced below 3′45′′ in 75% of cases.