【作者】 王凯庆；

【导师】 徐戊矫；

【作者基本信息】 重庆大学 ， 材料加工工程， 2012， 硕士

【摘要】 高精度铝合金矩形管作为微波信号传导的关键媒介被广泛的应用到航空、航天、雷达等国防高尖端领域。由于其使用环境的特殊性，不仅对矩形管的几何形状及尺寸精度要求很高，而且对其内表面粗糙度有着更加严苛的限定，制备难度相当大。我国该类型矩形管的研制工作起步晚，受技术条件等因素的制约，还不能生产出完全符合使用要求的成品矩形管，从而造成了长期依赖进口的尴尬局面，这种形势也将随着我国军事工业的发展而变得日益严峻。因此，掌握该类型铝合金矩形管的自主开发技术变得势在必行，同时也可以打破欧美国家的技术垄断，具有较强的国防军事意义。本文的研究对象为尺寸规格91.62×48.26×2.05mm的铝合金矩形管，其尺寸偏差为±0.12mm，内表面粗糙度要求达到Ra=1.0um，这正是其制备的重点与难点所在。目前，由于受到工艺、设备等诸多因素的影响，矩形管生产存在较多问题，如成品管壁内凹、翘曲、壁厚分布不均，尤其是内表面侧壁中部手感毛糙，出现明显的橘皮现象，这些大大的制约了矩形管的使用性能。基于此，本文开展了对该规格铝合金矩形管的成形工艺研究，其主要内容如下：①对矩形管成形特点进行分析，确定了三道次的拉拔成形方案，即第一道次空拉拔获得过渡近似矩形截面；中间道次带芯棒拉拔对前道次管材进行矩形矫正，使其更加接近成品管；末道次带芯棒拉拔保证最终的尺寸形状及表面精度。三个阶段管材截面变化尺寸参数为： φ92.8×2.15mm—96.38×57.26×2.15mm—92.8×50.0×2.1mm—91.62×48.26×2.05mm。②建立了矩形管多道次冷拉拔成形过程的有限元分析模型，阐述了金属流动特点及变形规律，解释了成形过程中出现的管壁内凹、翘曲、壁厚不均等缺陷的成因，并提出了恰当的解决措施，有效地保证了矩形管的形状精度。③为了提高拉拔过程材料变形的均匀性，结合数值模拟与数学正交试验设计方法对五个主要拉拔参数（拉拔速度v、摩擦系数、成品模定径带长度L、模具入模角、定径区过渡圆弧半径R）进行优化分析，确定了应变均匀性指数和成品管尾部‘凸耳’高度H两个评价指标，并通过对结果的直观分析，得到了保证成形稳定性的最佳参数组合：v=12.5mm/s，L=9mm，=0.05，R=5mm，=9°④针对铝合金矩形管成形表面质量较差的现象，对传统的拉拔模具及芯棒结构进行了优化再设计，提出了新型的‘凸包型’模具及‘台阶型’芯棒，通过开展对优化前后方案的模拟分析，系统的比较了管材等效塑性应变应力场的分布情况、管材内表面与芯棒的接触状态、矩形管的成形尺寸精度以及拉拔载荷等参量，分析结果显著地证明了新型模具及芯棒设计对于提高矩形管变形稳定性及改善成形精度方面的有效性与可行性。⑤对优化后方案开展铝合金矩形管实际工艺试制。经测量，成品管形状尺寸精度达标，并且内表面粗糙度均在产品的设计范围之内，满足了该铝合金矩形管的严苛使用要求。通过本文开展的系列研究，实现了对该规格铝合金矩形管的工艺开发，并有效地丰富了异型截面管材拉拔成形理论，对今后类似规格管材的研制具有较强的借鉴作用与指导意义。更多还原

【Abstract】 The aluminum rectangular tube with high accuracy is a widely used component inthe aviation, radar, and aircraft for microwave transmission. Due to particular conditionof usage, not only the requirement for dimensional accuracy is high, but also for theinternal surface finish is stricter. Therefore, it is difficult to obtain the accurate tubeforming. The research for the high accuracy rectangular tube in our country has a veryshort history, so the forming process has not been developed to manufacture the eligibletube for lacking of technology and experience. The situation leads to the long-term tubeimportation from abroad which greatly restricts the development of our military industry.Therefore, it is necessary to obtain our own production process for this type ofaluminum rectangular, which can break out the technique monopolization of developedcountries and has a strong contribution to our national defense industry construction.The research object in the paper is the aluminum rectangular tube with dimensionsof91.62×48.26×2.05mm, the dimensional deviation±0.12mm and internal surfacefinish Ra=1.0um. Nowadays, the production of rectangular tube has some formingproblems for the influences of process, machine and so on, such as tube wall concave,wrinkle, uneven wall thickness distribution, especially the rough internal surface andevident ‘orange texture’ phenomenon in tube inner surface. All of these are greatlyaffecting the particular usage of the rectangular tube. Based on the analysis, theinvestigation of forming process for manufacturing this rectangular tube has beencarried out in this paper and the main content are as follows:①The three passes drawing scheme is determined after the analysis of therectangular rube forming feature, that is, the first pass is tube sinking drawing withoutplug for proper transition section; The middle pass plays a role of rectangular correctionfor the first pass tube; and the last one is the significant drawing pass with plug forassuring the finial dimension, geometry and surface accuracy. The section dimension forthe three passes is:φ92.8×2.15mm—96.38×57.26×2.15mm—92.8×50.0×2.1mm—91.62×48.26×2.05mm②The finite element model of aluminum rectangular tube multi-pass cold drawingprocess has been established in the paper. Through series of FEM analysis, the tubemetal flow and deformation feature is summarized. Meanwhile, the reason for maindrawing defects such as tube wall concave, wrinkle and uneven wall thickness is also explanted in our study. And the proper measurements are proposed to solve this problemwhich guarantees the eligible tube geometry accuracy.③To improve the uniformity of tube metal deformation in drawing process, thestudy is carried out to optimize the five significant drawing factors (drawing velocity v,friction coefficient, drawn tube sizing zone length L, die semi-angle, transitionarc radius R). Two evaluate index (deformation uniformity criteria θ and tube ear height H)are determined to analysis the simulation results. And the optimal parameterscombination for assuring the tube drawing stability is obtained after results institutiveanalysis, that is, v=12.5mm/s， L=9mm，=0.05， R=5mm，=9°④Aiming to solve the unqualified accuracy of rectangular tube inner surface, thenew type of “convex hull” shape die configuration and plug with “tinny boss club” areproposed to replace the traditional ones. The contact status between the tube innersurface and plug, the plastic strain-stress distribution, the dimensional accuracy of theformed part, and the forming load have been compared between the conditions that thetraditional die and this new type one have been used respectively. The results showclearly that the new type drawing die and plug design are beneficial to increase thedeformation uniformity and improve the tube forming accuracy.⑤The experiment on the cold drawing process of the aluminum rectangular tubehas been performed. The comparisons of the drawn tube dimensions, e.g. height/widthand wall thickness, have been made between simulation results and practical production.Meanwhile, the surface finish has also been measured. The experimental result exhibitsthat the drawn tube can better fulfill the requirements of the design and usage when theoptimized forming scheme is adopted.The investigation in the paper achieves the development of this high qualifiedaluminum rectangular tube, enriches the drawing deformation theory of special-sectiontubes and can also provide an effective guideline and reference to the research of thiskind of tube.更多还原