在拉延过程中,金属材料与模具的表面直接接触,而且相互间作用的压力很大。使材料在凹模表面滑动时,产生很大的摩擦。摩擦力增加了拉延所需的力和制件侧壁内的拉应力,因而对拉延过程不利,易使制件破裂,造成废品。另外,材料与凹模表面的摩擦还降低了模具的寿命和容易划伤制件表 In the drawing process, the metal material is in direct contact with the surface of the mold, and the pressure exerted by each other is great. When the material slides on the surface of the die, great friction occurs. Friction increases the force required for drawing and the tensile stress in the sidewall of the part, which adversely affects the drawing process and can easily rupture the part resulting in waste. In addition, the friction between the material and the die surface also reduces the life of the die and easily scratches the part list