汽车覆盖件模具因硬度较高、精加工余量较小,导致模具精加工中经常出现由于余量选择不当而造成刀具与工件之间产生滑擦,使得模具精加工后出现多处区域加工不到的现象,此现象在凸曲面加工中尤为常见,严重影响汽车覆盖件模具的合模精度,增加了后期人工修磨时间。针对汽车模具凸曲面精加工中刀具与工件之间的滑擦现象,提供一种确定工件材料最小切削厚度的试验方法,确定淬硬钢Cr12MoV材料不同切削速度下最小切削厚度值,在此基础上,通过理论分析,建立考虑刀具变形因素的模具钢凸曲面加工极限切削深度预测模型,并通过模具钢凸曲面铣削试验验证所建立模型的准确性。该模型的建立为模具精加工余量的选取提供一个最小值,精加工余量的选取应大于该最小值,以确保刀具与工件之间能够正常切削,提高模具的加工质量及合模精度,最终为汽车覆盖件模具高品质加工工艺参数的选取提供理论依据及技术指导。
As high hardness and small finish machining allowance of automobile panel dies, sliding-friction phenomenon between tool and workpiece often occurs in dies finishing machining, especially in convex surface machining, which is due to unreasonable machining allowance, resulting in multiple region cannot be machined, seriously affecting assembly precision of automobile panel dies and increasing artificial grinding time. Aiming at the sliding-friction phenomenon between tool and workpiece in convex surface finishing machining, a test method is provided for determining the minimum cutting thickness of workpiece material, and the minimum cutting thickness values of hardened steel Cr12MoV under different cutting speeds are obtained. Based on the research above and through theoretical analysis, the limit cutting depth prediction model for automobile dies finishing machining of convex surface is established considering cutter deflection, and the accuracy of the model is verified by experiment. The model provides a minimum value for the selection of dies finishing machining allowance, in order to ensure the normal cutting and also for improving the quality and assembly precision of dies allowance should be selected greater than the limit cutting depth predictive value, which ultimately provides theoretical basis and technical guidance for parameters selecting in high quality automobile panel dies machining.