【作者】 王宇；

【导师】 罗远新；

【作者基本信息】 重庆大学 ， 机械工程， 2018， 硕士

【摘要】 齿轮轴向滚轧作为一种新型齿轮成形方法,既能克服切削加工存在的材料利用率低、轮齿疲劳寿命低等缺陷,又能避免挤压、锻造存在的脱模困难、模具寿命低等问题,能够满足齿轮高效、精密的生产要求。但国内外针对齿轮轴向滚轧的研究较少,材料流动机理尚不清楚,工艺参数选取缺乏科学依据,离工业化应用差距较大。为解决上述问题,本文基于滑移线场理论,对滚轧过程中塑变区材料流动规律进行了研究。利用有限元法深入探究工艺参数对材料流动的影响,并通过齿轮轴向滚轧实验对模拟结果进行验证。主要内容包括:(1)对成形过程中齿坯受力进行分析,用图解法建立塑性变形区的滑移线场。并根据滑移线场的速度场理论,对齿坯不同部位材料的流动趋势进行预测,得到不同成形阶段下齿坯塑变区内的材料流动状态。(2)基于有限元对齿坯材料流动过程进行数值模拟,针对有限元软件难以定义工件旋转的问题,提出了以轧轮公转代替齿坯自转的运动学等效模型,并通过坐标变换法验证其正确性。(3)通过分析各阶段中齿坯应变、节点流速等参数变化规律,得到成形轮齿特点。以齿坯应变、材料流速、有效齿高、突耳体积等指标为参照,基于控制变量法分析轴向进给速度、轧轮转速、轧轮与坯料间的摩擦系数对材料流动的影响规律。(4)利用自行搭建的齿轮滚轧实验平台对材料流动规律进行验证。为了清晰地展现材料流动过程,采用“网格法”追踪齿坯材料运动轨迹,并将变形后网格与有限元结果进行对比。更多还原

【Abstract】 As a new gear forming method,the gear roll-forming process with axial infeed can overcome the defects of cutting machining such as low material utilization rate and low fatigue life of teeth.It can also avoid the problems of extrusion,forging such as demoulding difficulty and low service life of die.It can satisfy the production requirement of high efficiency and precision.However,there is less research of domestic and international on gear rolling process with axial infeed.The mechanism of material flow is not clear and there is no scientific basis for the selection of process parameters.This process is far from industrial application.To solve these problems,this paper studies the flow of materials in plastic zone during roll-forming process based on the theory of slip line field,The influence of process parameters on the flow of materials was investigated by finite element analysis.The simulation results are verified by the gear roll-forming experiment.The following contents are studied:(1)The force of workpiece in roll-forming process with axial infeed was analyzed.The slip-line field of the plastic deformation zone was established by the graphical method.The material flow trend of different parts of workpiece is predicted by the theory of velocity field.The material flow state in the plastic deformation zone of the workpiece under different forming stages was analyzed.(2)Based on finite element method,simulation of the workpiece material flow process is carried out.Rotational motion of the workpiece is hard to be defined in software,thus a kinematic model,the workpiece rotation is replaced by the rolling tool revolution,is deduced.The correctness of the kinematic model is verified by the coordinate transformation theory.(3)The characteristics of the forming gear teeth were obtained by analyzing the change rule of tooth strain and node velocity in each stage.Based on the parameters of tooth strain,material flow velocity,effective tooth height and rabbit ear volume,The influence law of the feed speed,the roller rotate speed,the friction coefficient between roller and workpiece on the material flow is analyzed based on the control variable method.(4)The material flow rule is verified on the gear roll-forming experiment platform.To demonstrate the flow of materials clearly.The motion track of workpiece material was tracked by "grid method",and the deformation of the mesh is compared with the finite element results.更多还原