Development of a process for the two-stage production of gears

齿轮两阶段生产工艺的开发

• 批准号: 443284947
• 负责人: Professor Dr.-Ing. Mathias Liewald
• 金额: --
• 依托单位: Institut für Umformtechnik (IFU)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/443284947?language=en
• 关键词: Development; process; two; stage; production

Cold forging has been applied since numerous years in industrial gear production. To produce straight and helical spur gears, lateral extrusion is a commonly used cold forging manufacturing process. Usually lateral extrusion processes require high process forces to fill a toothed die contour. These results in a high elastic deformation of the active die surface and a huge elastic springback in the workpiece after the ejection from the die. Therefore, lateral extrusion with without corrected die profile does not achieve the required accuracy of gears. An improvement of mould filling and gearing precision as well as a reduction of process forces can be achieved by multi-stage forming or the utilization of incremental forming processes. Another method to improve mould filling while simultaneously reducing process forces and tool loading can be achieved by the established principle of the divided flow method. The newly discovered effect of lateral cavity filling is based on the same principle as the divided flow method, and has been demonstrated experimentally and numerically as part of the preliminary studies for the proposed research project. Simulations have been performed to illustrate the positive effect of lateral cavity filling with the example of a two-staged lateral extrusion process to manufacture an external gearing. By applying this innovative method, a considerable reduction of punch forces of over 40 % was achieved as a result of the targeted material flow along the freestanding workpiece surfaces in the tooth flanks.In the applied research project an innovative technological approach for manufacturing gears using lateral extrusion by means of numerical and experimental investigations will be examined. The forming process of the teeth occurs in the second forming stage using the above-mentioned effect of lateral cavity filling in order to achieve a reduced forming force and correspondingly tool load. By systematic material pre-distribution in the first forming stage and a specific asymmetrical positioning of the preform in the second forming stage, the tooth profile is formed with a minimised die surface contact. This innovative forming process results in a significantly reduced pressing force and tool load during mould filling and, consequently, improves tooth accuracy compared with conventional, single-stage toothing presses using lateral extrusion.

冷锻在工业齿轮生产中的应用已有多年。为了生产直齿和斜齿正齿轮，横向挤压是常用的冷锻制造工艺。通常横向挤压工艺需要高工艺力来填充齿形模具轮廓。这会导致有效模具表面的高弹性变形以及工件从模具顶出后的巨大弹性回弹。因此，在没有修正模具轮廓的情况下进行横向挤压无法达到齿轮所需的精度。通过多阶段成形或渐进成形工艺，可以提高模具填充和传动精度，并减少工艺力。另一种改进模具填充同时减少工艺力和工具负载的方法可以通过分流法的既定原理来实现。新发现的侧向空腔填充效应基于与分流法相同的原理，并且作为拟议研究项目初步研究的一部分，已通过实验和数值论证。已经进行了模拟，以制造外齿轮的两阶段横向挤压工艺为例，说明了横向空腔填充的积极效果。通过应用这种创新方法，由于目标材料沿着齿面中的独立工件表面流动，冲切力显着降低了 40% 以上。在应用研究项目中，将通过数值和实验研究研究一种利用横向挤压制造齿轮的创新技术方法。齿的成形过程发生在第二成形阶段，利用上述横向空腔填充的效果，以实现减小的成形力和相应的工具负载。通过在第一成型阶段中系统性的材料预分配以及在第二成型阶段中预成型件的特定不对称定位，以最小化的模具表面接触形成齿形。与使用横向挤压的传统单级齿压机相比，这种创新的成型工艺可显着降低模具填充过程中的压力和工具负载，从而提高齿形精度。