| 摘要 |
PURPOSE:To manufacture a drill-shaped printing working tool by rolling a printing part simultaneously with a screw thread part by one process, by a die which has formed many irregularities on a plane. CONSTITUTION:When a drill-shaped electrode 106 has been rotated and moved on a plane, many irregularities generated on its plane are formed on a slant face and the lower part 206 of a flat part of a die 201 which has been brought to electric discharge machining. In this state, by this die 201, a wire rod is rolled by the same method as a method for manufacturing a screw thread by a general rolling flat die. By this rolling, a self-drilling screw is obtained. A cutting part 1 of this screw has a groove 7 extending in the vertical direction, a land 9 and a margin 11. The groove 7, the land 9, ad the margin 11 are formed by a projecting part 208 of the die 201, a land forming surface 209 of a recessed part, and a margin forming surface 211 of the recessed part, respectively. Also, at the tip of the cutting part 1, a tip cutting edge 19 which has set the point angle to 110 deg. is formed in the edge of a tapered face 13, and this face 13 formed by a taper forming surface 213 of the die.
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