| 摘要 |
The present invention relates to a hammer device, preferably a down-the-hole hammer, including a drill bit (11) and a piston (10) reciprocating therebehind to periodically strike the drill bit. The drill bit (11) includes front (11a) and rear (11b) portions of different impedance, and the piston (10) includes front (10b) and rear (10a) portions of different impedance. In the drill bit, the front portion (11a) has a larger impedance than the rear portion (11b). In the piston, the rear portion (10a) has a larger impedance than the front portion (10b). The length of the drill bit front portion (11a) is about twice the length of the drill bit rear portion (11b). The length of the piston rear portion (10a) is about twice the length of the piston front portion (10b). The invention further relates to a drill bit (11) and a piston (10), per se.
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