| 摘要 |
Method and apparatus for extruding burr holes in a metal sheet, in which a punch with a conical end portion and adjoining cylindrical portion of a diameter greater than the inner burr diameter is passed through the burr. The conical end portion has a half apex angle between 10 DEG and 20 DEG , and the axial length of the cylindrical portion and the coefficient of friction between the cylindrical portion and the burr wall are selected according to a specified relationship. |
