Key Points of the Operation of Rock Reamer

The main parameters of the operation control of rock reamer are the push-pull force applied to the reamer by the drilling rig (pull force in the case of reverse reaming, and thrust force in the case of forward reaming), which is also called drilling pressure, rotate speed, and the pump output of mud during the reaming.

Its control points are as follows:

(1) HDD rock reamers of different diameters and different forms have different requirements for drilling pressure. Most reaming accidents in rock layer are caused by excessive pursuit of reaming speed and excessive drilling pressure.

(2) Rotate speed is another important control parameter for rock reaming construction. The rotate speed referred to here is the speed at which the drill rod is driven by the drill to drive the reamer to rotate, and the adjustment of the rotate speed is mainly related to the hardness of the rock. When the diameter of the reamer is ≤70mm, the recommended speed should not exceed 60Rpm; when the diameter of the reamer is greater than 700mm, the recommended speed should not exceed 40Rpm. When drilling in hard rock, the speed should be reduced accordingly, generally 10 to 40Rpm. Too low speed will reduce the efficiency of reaming, which is not economical; too high speed will cause abnormal wear of the reamer, and even cause reaming accidents.

(3) An important principle that should be followed in the rock reaming operation is the harder the rock to be broken, the greater the required drilling pressure, and the lower the required drilling speed. At the same time, it should be noted that under the condition of the same drilling speed, the effects of reamers with different diameters are different. The larger the diameter of the reamer, the greater the linear velocity of the outer edge and the more serious the wear.

Professional rock drilling tools: roller bits, cone reamers, cone palms.

(4) When reaming the rock layer, it is also critical to ensure the pump output of the mud. At this time, the main function of the mud is to cool the reamer and carry drillings. The actual pump output of the mud should be determined after calculation according to the amount of drillings and the carrying capacity of the mud in each stage of reaming, which generally should not be less than 1m/min.

(5) The construction method of the reamer entering the rock layer: When the rock reamer enters the rock layer from the soft soil layer or enters the hard rock layer from the soft rock layer, the main point of operation is to first slow down the reaming speed, reduce the drilling pressure, and wait for expansion. After the device body has completely entered the rock layer or hard rock layer, increase the drilling pressure. If the drilling pressure applied during this process is too large, it is likely to cause jamming, thereby damaging the reamer, or at least shortening the service life of bearing of the reamer.

(6) When performing grading reaming, be careful not to choose rock reamers with diameters that are too close (the grade difference is less than 50mm) for grading reaming, otherwise the reaming effect of the reamer will not be exerted, and the reamers with similar diameter are prone to the danger of being stuck in the rock layer during operation.