| 摘要 |
The sleeve (4) with head and screwthread is particularly for securing a plate preventing drilling of a lock. The sleeve head (5) contains a drilling (7) extending for part of the length of the shank. This is filled with powder containing cemented carbide, which is sintered to form a core (9). There can be a recess (8) in the head, from the bottom of which the drilling extends, both being filled with the sintered powder. The drilling can widen in the direction away from the head. ADVANTAGE - Cannot be sawn or drilled through
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