| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a burring method and a burring die for forming a burring part by which the more number of screw threads are formed by reducing the number of dies to be used and making the effective length of a hole for forming the screw threads longer. <P>SOLUTION: The burring method includes: an stage (a) where a planar workpiece W is held with a punching die and a dieing die, formed into thin thickness by sandwiching and pressurizing a portion where is sandwiched by a pressurizing projecting part 23 provided on the punching die and a pressurizing projecting part 35 provided on the dieing die opposing to the pressurizing/projecting part, and also by making the metal in the portion where is sandwiched and pressurized flow into an annular recessed part 19 where is formed around the pressurizing/projecting part provided on the punching die or the dieing die, a cylindrical projecting part BU is formed on one side face of the upper surface or the under surface of the workpiece W and also a recessed part is formed on the other side face of the workpiece W; and a stage (b) where the portion where is made into the thin thickness by the pressurizing projecting parts of the punching die and the dieing die is punched. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
