板料成形中考虑油膜厚度和滑动速度的摩擦模型

A friction model considering lubricant film thickness and sliding speed in sheets metal forming

板料成形过程中,摩擦特性直接影响成形件的质量。通过分析边界润滑状态和流体润滑状态的金属镀层板料受力情况,建立了一个混合润滑状态下关于润滑油膜厚度和滑动速度的摩擦模型。采用平板滑动摩擦实验研究了润滑油膜厚度和滑动速度对镀锌钢板摩擦系数的影响,确定了实验条件下CR4镀锌板的摩擦模型参数,并验证了其准确性。研究表明:摩擦系数随着油膜厚度增加而减小并最终趋于稳定;随着滑动速度增加,摩擦系数减小。油膜厚度和滑动速度的增加都使得模具和板料镀层直接接触的面积在实际接触面积中的百分比降低,从而摩擦力下降。

The friction characteristics directly affect the quality of stamping parts. By analyzing the forces acting on the coated metal sheet under the boundary lubrication and the fluid lubrication respectively, a friction model was proposed considering both lubricant film thickness and sliding speed under the mixed lubrication state. The influences of lubricant film thickness and sliding speed on the friction coefficient of galvanized steel sheets were studied by planar sliding test, and the friction model parameters of galvanized CR4 steel sheet were obtained under the experimental conditions and then were verified. It is concluded that the friction coefficient decreases with the increase of lubricant film thickness, and eventually tends to be stable ; and it also decreases with the increase of sliding speed. With the increase of lubricant film thickness and sliding speed, the percentage of the contact area between the die and the sheet coating in the actual contact area decreases, and the friction force decreases theoretically.