| 摘要 |
The screw nail is used for fastening or fixing soft materials such as metals, wood, plastic or fibroid material or low-density material without fracture. The screw nail is rolled by stationary dies (40) with a plurality of slots (40') and engaged with reciprocating dies (41) with a plurality of slots (41'). The stationary dies (40) forming the slots (40') has core zone (z) for forming core (42) with reverse-involute curve, which is formed on slot (10) in the order odd numbers (1,3,5,-17) in the slot (40'). The reciprocating dies (41) forming the slots (41') has core zone (z') for forming core (42') with reverse-involute curve, which is formed on slot (11') in the order even numbers (2,4,6,-18) in the slot (41').
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