影响板料镦压力大小的因素及板料镦压力的计算

Analysis of Influencing Factors of the Forming Force and Calculation of Forming Force for Sheet Upsetting

目的获取板料镦压成形力影响因素的规律以及合适板料镦压的成形力公式。方法分析板料镦压的类型和特点,选取圆形板料,通过deform进行模拟,得到材料、工件直径、工件厚度、摩擦润滑条件等因素对板料镦压成形力的影响情况,对镦压工况下的断面缩减率进行求解,综合棒料镦粗和棒料挤压提出板料镦压力计算的数学模型。结果板料镦压比棒料镦压的阻力大很多,并且存在厚度变小时"压力骤增效应";实心板料镦压状态下,按径向挤压过程理解,其断面缩减率R值为d/(d+4t);基于提出的板料镦压力计算模型,当宽厚比分别为2,4,6,8,10时,m值分别选取为2,0.5,0.25,0.1。结论材料的屈服极限和硬化指数较小,增加坯料厚度,减小坯料直径,减小摩擦因数,在一定范围内可以降低成形力;随着宽厚比增大,镦压力增大。

In order to obtain the influence laws of the forming force of sheet upsetting and the suitable forming force for- mula of sheet upsetting. The types and characteristics of sheet upsetting are summarized, the influence of the material, the di- ameter of the workpiece, the thickness of the workpiece and the friction and lubrication conditions on the forming force of the sheet upsetting are analyzed; by selecting a round sheet and a series of simulations, the reduction in area under the sheet upset- ting condition is solved, the formula of forming force of rod bar upsetting and extrusion are summarized, the mathematic model of the forming force of the sheet upsetting is put forward. The upsetting of the sheet is much greater than that of the rod bar up- setting, and there is a ＂thickness reducing and pressure dropping effect＂; In the state of solid sheet upsetting, the R value is d/（d＋4t） based on radial extrusion, when the width-thickness ratio is 2, 4, 6, 8, 10, the m values are selected as 2, 0.5, 0.25, 0.1 based on the new mathematic model of forming force respectively.The yield limit and hardening exponent of the material are small, increasing the thickness of the workpiece, reducing the diameter of the workpiece, reducing the friction factor, the form- ing force reduced in a certain range; the forming force increases with the width-thickness ratio increasing.