Experimental Exploration of the Aluminum Tube Drawing Process for Producing Variable Wall Thickness Components used in Light Structural Applications
Experimental Exploration of the Aluminum Tube Drawing Process for Producing Variable Wall Thickness Components used in Light Structural Applications
复制标题
铝管拉拔工艺生产轻结构应用中变壁厚部件的实验探索
DOI：
10.4271/2010-01-0222
复制
发表时间：
2010
期刊：
影响因子：
6.4
通讯作者：
G. D'amours
中科院分区：
文献类型：
--
作者：
M. Guillot;M. Fafard;S. Girard;A. Rahem;G. D'amours
管材拉拔是一种众所周知的工艺，包括在室温下减小直径和壁厚以获得规定值。初始管被拉入具有较小开口的模具中，其厚度通过使用芯棒来实现。通常，芯棒有一个平台区域，该区域的直径通过调整最终管的内径来确定。汽车、飞机和其他车辆中的一些结构部件需要较轻的弯曲或液压成形管。具有不同轴向或周向厚度的管子是有意义的，这样可以减少低应力区域的超重，并在其他方面加固它。然而，由于变形区较高的金属流动应力以及在拉拔过程中需要精确控制芯棒位置，因此生产不同厚度的管材变得更加困难。轴向厚度变化是使用带有阶梯形凸缘或略微锥度的芯棒实现的，而圆周厚度变化是使用所需的内外形状(例如椭圆形)的芯棒实现的。本文介绍了两种轴向变壁厚技术和一种周向变壁厚技术，并进行了试验。首先，介绍了变厚度拉拔管的生产工艺。为了进行测试，使用了一台小型(335kN)仪表式拔管机。详细介绍了这台机器、工艺润滑、监测数据和所实施的工装。最初的管材主要是直径63.5 mm、厚度2.6 mm的AA6063挤压件，最终的外径即模具内径约为47.5 mm。还拉拔了AA6061管。从无芯棒拉拔试验开始，测量了管材的自然流量和牵引力。其次，用阶梯形芯棒生产了4种不同厚度的管材，研究了应变硬化对力学性能的影响。使用锥形芯棒，对连续变化壁厚的管子进行了测试。在某些情况下，模角半径内较高的局部压力限制了适当的润滑，但在大多数情况下结果是有希望的。我们还研究了沿管子的厚度变化率的影响。最后，用阶梯形椭圆形芯棒进行的试验提供了周向厚度变化的良好结果。用三坐标测量机测量尺寸质量，并从初始和拉拔的管材拉伸试验中获得机械性能。最后，尽管存在一些小问题，但所提出的技术可以有效地生产厚度变化的管子，并具有很强的工业应用潜力。
Tube drawing is a well known process involving at room temperature the reduction of diameter and wall thickness to obtain specified values. The initial tube is drawn into a die of a smaller opening and its thickness achieved by use of a mandrel. Usually, the mandrel has a land area which diameter defines by sizing the inside diameter of the final tube. Some structural components found in cars, aircrafts and other vehicles require bent or hydroformed tubes of lower weight. It is of interest to have tubes of varying axial or circumferential thickness so that to reduce overweight in low stressed areas and reinforce it otherwise. However, the production of tubes of varying thickness is more difficult in reason notably of higher metal flow stresses in the deformation zone and the need to control precisely the mandrel position during drawing. Axial thickness variation is obtained using a mandrel with stepped lands or with a slight taper while circumferential variation is achieved with a mandrel of desired internal or external shape (e.g. oval). In this paper, two techniques for axial tube wall thickness variation and one technique for circumferential variations are introduced and tested. First, the techniques to produce drawn tubes with thickness variations are presented. For testing, a small (335 kN) instrumented tube drawing machine is used. Details on this machine, process lubrication, monitored data and on the tooling implemented are also presented. Initial tubes are mainly AA6063 extrusions of 63.5mm O.D. and 2.6mm thick and the final outside diameter, i.e. the inside diameter of the die, is about 47.5 mm. AA6061 tubes are also drawn. Starting with drawing tests without mandrel, the natural flow of the tube and the drawing force involved are measured. Secondly, tubes of 4 different thicknesses are produced with a stepped mandrel and the strain hardening effect on mechanical properties established. Using a tapered mandrel, tubes of continuously varying wall thickness are tested. Higher local pressure in the die corner radius restricts proper lubrication in certain conditions but results are promising in most cases. We also study the effect of thickness rate of change along the tube. Finally, tests with a stepped oval mandrel provided good results for circumferential thickness variations. The dimensional quality is measured using a coordinate measuring machine and mechanical properties obtained from tensile tests in both initial and drawn tubes. Finally, despite some minor problems, the techniques proposed can efficiently produce tubes with thickness variations and have a very strong potential for industrial use.