The main parameters of rock reamer operation control are the thrust force exerted by the drill on the reamer (force in reverse reaming and thrust in forward reaming) or the bit pressure, rotating speed and mud pumping volume during reaming.
Its control points are as follows:
(1) Different diameters and different forms of rock reamer have different requirements on bit pressure. Most rock layer reamer accidents are caused by excessive pursuit of pore broadening speed and excessive bit pressure applied.
(2) Speed is another important control parameter for rock reaming construction. The speed here refers to the speed driven by drill pipe and reamer, and the adjustment of speed is mainly related to the hardness of rock.
When the diameter of the reamer is more than 700mm, the recommended speed should not exceed 40Rpm. When drilling in hard rock, the speed should be reduced correspondingly, generally ranging from 10 to 40Rpm.
Too fast speed will cause abnormal wear of the reamer and even cause an accident of reaming.
(3) rock broaching operation should follow one of the most important principles:the harder the rock to be broken, the greater the need of wob and the lower the requirements of the drilling rate. At the same time, what should be paid attention to is that under the condition of the same rig drilling rate, the effect of the different diameter of reamer is not the same, the greater the outside edge of the linear velocity, the more serious the wear also.
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(4) It is also critical to ensure the amount of mud pumped during rock layer reaming, where the main role of the mud is to cool the reamer and carry cuttings. The actual pumping amount of mud should be calculated based on the amount of cuttings produced by each stage of reaming and the carrying capacity of the mud, generally no less than 1m/min.
(5) The reamer into rock construction methods: when the rock reamer into from soft soil layers or from soft rock into hard rock, the operating point is first expanding speed slow down, reducing wob, staying reamer ontology completely into the rock and hard rock strata and then increasing the wob. Exerting wob is too large, if the process is likely to cause sticking, so as to damage the reamer, or at least reduce the life span of the reamer bearing.
(6) In the process of graded reaming, pay attention not to choose rock reamer with too similar diameter (class difference less than 50mm) for graded reaming, otherwise, it will not give full play to the reamer's due reaming effect. On the other hand, a reamer with too similar diameter will easily be stuck by the rock layer during operation.