Aiming at the disadvantages of normal four-winged on-off PDC drill bit,such as inflexible on-off movement of wing blade,low efficiency in seam-crossing drilling,and the yielding of drilling bit,a new three-winged on-off PDC bit was introduced.The fixing mode of center wing blade is changed from open type to semi-open type;the ball plunger is fixed in drill bit body rather than center wing blade;the bit structure is changed from four-wing to three-wing,and the tooth arrangement is optimized.Field test was carried out in Zhujidong Coal Mine of Huainan Ming Group,the average drilling footage was 590.7m,average life expectancy of the 3 drilling bits increased by 68.8%;the average drilling efficiency in sandstone section of seam-crossing drilling reached 16 m/h increased by 33%;and with flexible on-off movement of center wing,the success rate of casing job reached up to 100%.%为解决普通四翼可开闭式PDC钻头存在中心翼片开闭不灵活、钻进穿层孔效率低、钻头体易变形的问题,介绍了新型三翼可开闭式PDC钻头的设计.设计方案为:将中心翼片的定位方式由全开放式改为半开放式;将定位珠位置由中心翼片改为镶嵌于钻头体内;将钻头结构由四翼改为三翼,优化布齿.开发的新型三翼可开闭式PDC钻头,在淮南矿业集团朱集东煤矿进行试验,3只钻头平均寿命为590.7m,提高68.8%;钻进砂岩段效率为16m/h,提高33%;中心翼片开闭灵活,下管成功率达到100%.
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