发明名称 |
Fluid operated drill apparatus |
摘要 |
Down-the-hole drill comprising a housing (1), a hammer piston (6) movable to-and-fro in the housing and intended for impacting a drill bit (5). A back piece (3) provided with an extension (12) with a valve part (17) cooperates with a part (8) of a central channel in the hammer piston. This part of the central channel comprises a zone (16) with larger diameter than adjacent parts at an intermediate part of this part. This results in that pressure medium can pass the valve part when it is situated at the zone and that the valve part and the hammer piston sealingly cooperate when the valve part is on either side of the zone.
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申请公布号 |
US5318140(A) |
申请公布日期 |
1994.06.07 |
申请号 |
US19920992247 |
申请日期 |
1992.12.14 |
申请人 |
UNIROC AB |
发明人 |
EKWALL, BERNDT;JAKOBSSON, TORBJOERN;PETERSON, MARTIN |
分类号 |
E21B4/14;(IPC1-7):E21B4/14 |
主分类号 |
E21B4/14 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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