面向钛及钛合金的复合模态超声波振动拉丝技术及机理研究

It is of great strategic significance to consolidate the national defense and the economics for developing the titanium and titanium alloy wire industry. However, titanium and titanium alloy wires are of the difficult-to-draw materials. At present, the conventional wire drawing process has some defects, such as needing to deal with the xidation annealing, coating and drying, easily broken wires, short life of drawing dies and rough surfaces. Accordingly, this project treats the interaction between the wire and the drawing die as the contact mechanics and tribology problems, and presents that the configuration planning of the ultrasonic vibration system with composite modes will be performed by coupling the longitudinal, bending, radial and torsional ultrasonic vibration modes. The effects of the composite ultrasonic field on the stress distribution and the trajectories of crystal grains will be studied. By taking the contact boundary conditions of the nonlocal friction effect in an elliptical region into account, various kinds of mathematical models on the wire drawing process with composite ultrasound modes will be established. 3-D models with rough surface contact will be developed. And their elastic-plastic contact analysis will be carried out. Characteristics and laws with respect to contact loads, contact stress and strain distributions, friction stress distributions, the dislocation, the slip, the distortion and the twin of lattices in titanium and titanium alloy wires will be studied. It will reveal the mechanism on the plastic deformation occurred in titanium and titanium alloy wires under the effects of the ultrasonic field with composite modes. It will provide feasible theory and techniques for the industrialized drawing production of the titanium and titanium alloy wire with low-cost and high-efficiency. The achievements of this project have broad prospects in application, and will bring huge economic and social benefits.

发展钛及钛合金丝工业对巩固国防和国民经济具有重要的战略意义。然而钛及钛合金丝属于难拉拔材料，当前其常规拉拔工艺存在需氧化退火、涂层和烘干处理、易断丝、拉丝模寿命短以及产品表面粗糙等缺陷。本项目将丝材与拉丝模间的相互作用视为接触力学与摩擦学问题进行研究，提出采用超声波的纵向振动、弯曲振动、径向振动以及扭转振动模态进行复合超声波振子构型规划，研究复合超声场对丝材的应力分布和晶粒运动轨迹的影响。以椭圆域的非局部摩擦效应为边界条件，建立接触体内部的应力场和复合模态超声拉丝过程的数学模型；构建3D粗糙表面接触模型并进行弹-塑性接触分析；探索钛及钛合金丝的接触载荷、接触应力与应变分布、摩擦应力分布、晶格位错、滑移、畸变以及孪生的特点和规律；揭示钛及钛合金丝在复合超声场作用下塑性成形的机理；为低成本、高效率、产业化拉拔生产钛及钛合金丝提供可行的理论和技术。本项目的成果应用前景广、经济效益和社会效益大。

发展钛及钛合金工业对巩固国防和国民经济具有重要的战略意义。针对市场中钛及钛合金丝材冷拉拔生产中存在易断丝，拉丝模具寿命短以及表面粗糙等问题。本项目提出使用超声振动辅助拉拔的方法，使丝材在加工过程中的摩擦降低、拉拔力减小、综合性能有所改善。提出了纵向振动、正交复合振动、纵扭复合振动、聚焦式振子等多模态的超声换能器构型规划；建立了各种复合模态超声波振动拉丝过程的数学模型；对难拉拔材料，如钛及钛合金丝、超细盘条钢丝、异形丝等都进行了超声振动拉拔研究。结果表明：设计多模态复合超声振子测试性能良好，满足超声振动拉拔的要求；超声振动对丝材拉拔过程的减摩有较明显的效果，能够显著降低拉拔力、改善丝材表面质量；且随着超声振幅的增大，性能提升效果越显著；获得了超声波振动场作用下难拉拔材料的塑性变形机理。通过本项目与南方一些拉丝生产企业形成了合作关系，对超声振动拉丝的产业化进行了探索，进行了换能器与生产用拉丝机的适配和拉拔实验，实验结果证明超声振动能够降低拉拔力、提升丝材圈径、延长连续拉拔时间，为超声振动拉丝的产业化和市场化奠定了基础。本项目发表SCI论文6篇，EI及会议论文3篇；培养博士生1名、硕士生3名；获得授权专利3项；与江苏省邳州市经济开发区合作注册了江苏锐翔超声科技有限公司，注册资本1000万元，主要生产金刚切割线母线，用于硅晶体、蓝宝石等原材料的切割，大力推进超声拉拔技术的产业化。

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