Development Of Expandable Reaming Bit Used In Gravel Stratum

With pipe drilling in gravel stratum, the lower part of casing which frequentlyoccur in boulder with tube difficult problem. This article develop a new drillingtechnology and drilling tools, it’s telescopic reaming drill bore hole drillingtechnology. The article introduce design, processing and application of the scalablereaming drill bit, mainly introduced the application of technology in hydropowerinvestigation and its advantages and disadvantages.This drill is equipped with two adjustable blade, under the action of mud pumppressure rinses can be stretched to outside the bit body. Scaling degree can be adjustedas the pressure size, at the same time two telescopic blades in the stretch and borehole drilling can be performed. In lower boulder the bit enlarge the annular gap isgreater than the casing pipe diameter, the casing continue to follow up to reach thetarget depth.In order to drill in gravel layer better, the cutting-edge shape has been improved. Inaddition, the paper are fully described drilling process parameters using telescopicreaming drill, equipment requirements, operating precautions. Especially itseffectiveness in the application of prospecting of hydropower engineering wereanalyzed and compared. Although the technology is low efficiency in drillingpenetration rate compared to small-caliber diamond,this method can avoid thetraditional fried hole blasting dangerous and cumbersome process of crushed andsolitary stone. It also can overcome the problem of torque resulting casing wear, easyto break, high costs result of using rotary casing bit up the casing pipe. The processmethod is easy to master without hole depth limit and has a good effect. It can also beused in reaming drilling with pipe, dealing with incidents, so it can be promotion andapplication.