【作者】 夏登玉；

【导师】 王永智； 李学京；

【作者基本信息】 合肥工业大学 ， 机械制造及其自动化， 2004， 硕士

【摘要】 冷挤压直齿圆柱齿轮精密成形技术因其具有节省材料、生产效率高、能保证零件尺寸精度、轮齿表面质量好、承载能力强和产品综合质量高等优点，成为直齿圆柱齿轮成形的一种发展趋势。但因直齿圆柱齿轮不允许有拔模斜度，使其挤压成形在模具设计上有一定的难度。流曲线曲面外形能极大地减小运动物体前进过程中流体对物体的阻力，是曲面造型一个新的发展方向。本论文基于这种理论，把流函数引入CAD设计中，设计一个符合金属流变特性的挤压过渡腔，对保证金属流动均匀性提高、改善金属流动性能、减少产品的扭拧和弯曲、降低成形压力和齿轮成形的精度提高有着积极的意义。 本论文主要研究了挤压型腔的数学建模、几何建模、图形交互数控自动编程以及数控加工仿真等方面内容。首先，我们运用流体力学的原理，分析推导出流曲线曲面的参数方程，实现了挤压型腔的数学建模。在数学建模中，利用Bezier曲线拟合、逼近流曲线。并根据齿轮轮廓线的实际情况把其分成五段：齿根圆段、过渡曲线段、渐开线段、齿顶过渡圆角段和齿顶圆段，把整个的挤压腔分成五个曲面片进行拟合，用五组参数方程来描述；其次是几何建模，我们利用所建立的数学模型，借助Pro／ENGINNEER软件先建立曲线网格，然后建立各曲面片，最后进行曲面拼接，建立挤压腔的几何模型；最后利用所建立的几何模型，在Pro／MANUFACTURE模块下，实现图形交互数控自动编程和数控加工仿真。 本课题的研究方向是按照制造业现代化CAD／CAM的发展趋势，开展对直齿圆柱齿轮精密成形的研究，该研究内容将为推广应用先进的成形工艺、生产高精度的齿轮发挥积极作用，为发展我国的精密成形理论和技术做出一定贡献。更多还原

【Abstract】 The extrusion technique become a trend towards spurs gears for it has many advantages, saving material, high productivity, high precision of parts dimensions, good parts surface and high product quality . But spurs gears have some difficulties in extrusion for they have no drawing slope. Stream surface outline can reduce the resistance pressure that produced by the objects going forward, so stream surface modeling become a new trend of modeling theory. This article leads stream function into computer aided design based on the theory, and to design an extrusion transition cavity to conform to the rule of metal flowing deformation, which can ensure the homogeneity of metal flowing, improve metal flowing properties, reduce product bending deflection and lower the extrusion pressure. It has a wide significance in gears extrusion.In this article, I do some work of mathematic model, geometric model, automatic NC programmed by figures interactive processing and NC process simulation. First, we realize the mathematic model through getting the parameterized equation by analyzing the fluid mechanics and make use of Bezier curve to approximate stream curve. In order to get the mathematic mode easily, we divide gear profile curve into five parts: the root of gear curve, the transition curve, the involutes curve, the transition round curve and the top of gear curve, which break the cavity into five surface parts. So we can describe the cavity by five groups parameterize equations. Second is geometric modeling, which can be established by the mathematic model with the help of Pro/ENGINEER. Last we realize the automatic NC programmed by figures interactive processing and NC process emulation by using the same software.This research job is the direction of modern CAD/CAM, and it plays a positive role in accurate spurs gears extrusion.更多还原