大尺寸旋转模切刀具激光熔覆形性一体化控制方法研究

The performance of die-cutting equipment is directly determined by the die-cutting tool. Large-size rotary die-cutting tools with the diameter of over 200 mm is usually formed using milling or mounting, resulting in great material wastage, high defective rate, and low reliability. By analyzing the effect of substrate shape and process parameters on theshape-property of the cladding layer, the relationship between laser and powder on the substrate with curved surface and the mechanism of molten pool formation are explored. The predictive method of cross-section shape under single cladding track as well as the optimization method of lapping and laminating control under multiple cladding tracks are investigated. The method for controlling shape-property integrations of laser cladding in a curvilinear path on the substrate with curved surface is established, which will be of great significance for developing the fundamental theory of laser engineered net shaping. Combined with the analysis of the relationship among the material gradient, thermos-physical property, and tool property, the method for designing the two-dimensional gradient matrix of tool property as well as the material fabrication process are investigated. The control method established for shape-property integrations of the cutting edge made of functional gradient materials will provide guidance not only for the fabrication of large-size rotary die-cutting tool, but for the repair of the discarded tool. Such a method can promote the sustainable development of domestic die-cutting machine industry. Besides, the research achievements of this project will be of wide application value for the fabrication and repair of other complex surface parts such as large-size rotary tools, compound function material parts, and turbine blade.

模切刀具直接决定了模切装备的性能。直径大于200mm的大尺寸旋转模切刀，通常采用铣削或镶装方法成形，容易出现材料损耗大、废品率高、可靠性差等问题。本项目通过基体形状、工艺参数对熔覆层性能和形状的影响分析，探索曲面基体上“光-粉”作用和熔池形成机理，研究单道熔覆轨迹截面形状预测方法，以及多道轨迹搭接/层叠控制优化方法，建立曲面基体上曲线轨迹熔覆成形成性控制方法，对完善激光熔覆近净成形的基础理论有积极意义；通过对材料梯度、热物性和刀具性能间的关系分析，研究刀具二维梯度性能矩阵设计方法和材料制备工艺，建立梯度功能材料刀具刃口形性一体化控制方法，为大尺寸旋转模切刀制造以及废旧刀具修复再用提供新方法，推动国内模切机行业的可持续发展。同时，本项目研究成果对其他大尺寸回转类刀具、复合功能材料零件，以及发动机叶轮等复杂曲面零件的修复、制造也具有推广应用价值。

模切装备的性能取决于模切刀具。大尺寸的旋转模切刀通常采用铣削或镶装方法成形，容易出现材料损耗大、废品率高、可靠性差等问题。.项目通过关键工艺参数对单层单道熔覆层形貌、性能及组织的影响分析，厘清了曲面基体上“光-粉”作用与平面基体上的差异对熔覆层形成的影响规律，并建立了空间曲线轨迹截面形状的精确预测模型；推导了基于表面平整性的单层多道熔覆层最佳搭接理论公式，提出了基于多目标优化方法的单层多道熔覆层的表面质量保障方法；映射了刀具材料成分与性能要求，提出了二维梯度刀刃的设计方法与熔覆工艺，实现了三角截面近净成型。.研究表明：(1) 随着基体预热温度的升高，熔覆层稀释率逐渐递增；随着基体接触导热系数的增大，熔覆层稀释率逐渐下降。(2) 单道熔覆层宽度随激光功率的增大及扫描速度的减小迅速增大，随气流量的增加缓慢增大，随基体曲率半径的增大先减小后趋平。高度随激光功率增大而迅速增大，随扫描速度减小缓慢增加，随气流量增加先增后缓慢减小，随基体曲率半径增大先迅速减小后趋平缓。稀释率随激光功率增大而增大，随扫描速度增大而减小，随气流量增大而减小，随基体曲率半径增大而减小。(3) 搭接率对多道熔覆层表面平整度影响最为显著，平整度与搭接率呈反比；搭接区域未熔空隙随着激光功率增大、气流量减小、搭接率增大而减小；熔覆层气孔面积随激光功率增大、气流量减小、搭接率增大而减小。(4) 刀具材料组成成分与硬度的关系为二次抛物线模型。根据模切刀具硬度62HRC可设计硬度梯度分布的二维模切刀刃。模切刀刃近净成形时的最佳扫描方式为长边同向搭接并从中间到两边扫描，通过熔覆头偏移可以实现层叠形状的精确控制，Z轴高度方向的行程控制方法为0.5d2+d≤Z+ΔZ≤0.6d2+d。.研究成果为大尺寸旋转模切刀制造以及废旧刀具修复再用提供新方法，推动国内模切机行业的可持续发展。同时，研究成果对其他大尺寸回转类刀具、复合功能材料零件，以及发动机叶轮等复杂曲面零件的修复、制造及再制造也具有推广应用价值。