304不锈钢板冷冲及其冲裁质量研究

Investigation on cold-blanking and blanked edge quality of 304 stainless steel sheet

为提高冲裁件质量,降低废品率,研究不锈钢板冷冲过程及冲裁间隙对冲裁件质量的影响规律.本文采用板料冲孔试验:以2 mm厚的同一规格304不锈钢板为试验材料,以凸模直径为冲孔公称尺寸,通过更换不同直径的凹模改变冲裁间隙,完成在不同冲裁间隙下的冲裁试验.试验采集了冲裁力随冲裁行程的变化曲线,分析了冲孔件断面形貌,测量了断面光亮带的孔径和高度、毛刺高度以及断裂带的孔径,并拟合各参数与冲裁间隙之间的关系曲线,研究不锈钢板冷冲过程中冲裁力的变化及冲裁间隙对尺寸精度、断面质量的影响.试验结果表明:不同冲裁间隙下冲裁力-冲裁行程曲线变化趋势基本一致,与冲裁3个变形阶段互相对应,冲裁力达到最大值时光亮带结束;冲裁间隙对冲孔件质量影响显著,冲裁间隙较小时,断裂带形貌呈韧窝状,而较大时断裂带形貌呈台阶状.研究表明:在试验给定大冲裁间隙条件下,当冲裁间隙为15%t左右时,冲孔件尺寸精度最高且断面质量最好,即冲孔件质量最好.

In order to improve the blanked edge quality and reduce the rejection,the cold blanking process and the effect of blanking clearance on the quality of blanking parts were studied. 304 stainless steel sheets with 2 mm thickness were used as the test material in punching test with different blanking clearance. The punch diameter was used as nominal dimension of punching,the blanking clearance was changed by changing the diameter of the die. The blanking force with the stroke was obtained,the section morphology was analyzed,the aperture and height of the burnish,the height of burr and the aperture of the fracture were measured,and the relationships between these parameters and blanking clearance were fitted. The major study context in this paper includes the change of blanking force in blanking process and the effect of blanking clearance on dimensional accuracy and section quality. The experimental results show that the trend of blanking force-stroke curve with different blanking clearance is basically similar,and they are corresponded to the three deformation stages. The burnish stops producing when the blanking force reaches the maximum value. The blanking clearance has a significant effect on the blanking quality. The fracture surface has many dimples when the blanking clearance is smaller,while the fracture appears step shape when it is larger. The investigation shows that under the test conditions given large blanking clearance,when clearance is about 15% t,the highest dimensional accuracy is achieved and the best section quality and blanking quality is obtained.