Stamping Forming and Die Design （冲压成型与模具设计）
1.2.3
The quality of the blanking workpiece mainly to the qualities of the cutting cross-section and workpiecesurface,shape tolerance and dimensional accuracy.(冲裁件质量主要是指切削截面和工件表面质量、形状公差和尺寸精度。)The cutting cross-section quality of the workpiece is an important factor to determine whether the blanking process is succeeded or not.(工件的切削截面质量是确定冲裁工艺能否成功的重要因素。)
As shown in Fig.1-4,the cutting cross-section can be divided into four regions:the smooth sheared zone,fracturezone,rollover zone and burr zone.(如图，切割断面可分为四个特征区域：光亮带，断裂带，圆角带和毛刺。)
Fig.1-4 Characteristic of the cutting cross-section of blanking workpieces(图1-4，冲
裁工具的切削截面特征）
When the punch edge cuts into the blank,the plastic deformation occurs due to extrusion between the material and the side of the cutting edge,resulting in the forming of the smooth sheared zone.（凸
凹模刃口对板料进行塑性剪切而形成光亮带）Due to the characteristic of extrusion,the surface of the smooth sheared zone is smooth and perpendicular,and is the region with highest accuracy quality within the cutting cross-section of the blanking workpiece,The thickness ratio of the smooth sheared zone to the cutting cross-section is about 1/2~1/3.(由于同时受到模具侧面的挤压力该区域不仅光亮且与板平面垂直，是断面上质量最好的区域，当间隙合适时，光亮带约占板料厚度的1/2~1/3。)
The fracture zone is formed in the final stage of blanking,it‘s the area where blank is cut off,and the fracture surface is formed with the cracks expanding continuously under tensile stress.The surface of the fracture zone is rough and inclined,and is not perpendicular to the blank.(在落料的最后阶段形成了断裂带，在拉应力作用下，断裂面形成有裂纹的区域，断裂带的表面粗糙、倾斜，且不垂直于坯料。) The rollover zone is formed when the die presses into the blank.The material near cutting edge is embroiled and deformed.The better the plasticity of the material,the larger would be the rollover zone.(圆角带是由于刃口附近的材料产生拉伸弯曲的结果。材料的塑性越好，就会有越大的圆角带。)
The burr of the cutting cross-section is formed when micro-cracks occur during blanking,The formed burr is then elongated and remains on the workpiece.(毛刺形成于断裂分离阶段，形成的毛刺是细长的且
附在工件上。)
There are many factors affecting the quality of the cutting cross-section.The proportion of the thickness of the four zones varies with blanking conditions,such as workpiecematerial,punch and die,equipment,etc.(有许多因素影响切削截面的质量，四个区域的厚度的比例随冲裁条件的变化而变化,如工件材料、冲床和模具、设备等。
Fig.1-5 shows the main factors that affect the quality of the cutting cross-section of blanking workpeice.（图1-5表明影响冲裁工件切割断面质量的主要因素）Fig.1-6 shows those factors affecting the dimensional accuracy of blanking workpiece.（图1-6说明影响冲裁件尺寸精度的因素）The research and analysis show that the clearance between the punch and die is the most important factor affecting the surface quality and the dimensional accuracy of the blanking workpiece.（研究与分析表明，凸模和凹模之间的间隙是影响表面质量和冲裁工件尺寸精度的重要因素。）To increase the surface quality of the blanking workpiece,it is important to study the clearance influence mechanism,so as to find a method for calculating the optimal clearance between the punch and die.（提高冲裁工件的表面质量，是研究间隙对机制的影响具有重要的意义，从而找到计算凸模和凹模之间间隙的最佳的方法。）