Milling cone: It is a tool for milling the casing to open the window. The main working surface is the side carbide cutting knife. Commonly used milling cones for sidetracking include single and double milling cones.
The basic requirements for the milling cone are: quick window opening, good wear resistance, geometric shape for cutting, small cutting load, difficult to drill, and easy to discharge. The maximum diameter of the milling cone is as large as possible to the diameter of the open hole drill so that it does not ream after opening the window. The compound milling cone consists of four cones of different taper. The lowermost stage is the cone head, and the taper is 2°~3°. It has a bottom cutting edge, which is used to guide the milling cone to prevent slipping out of the casing in advance; the second section taper is 6°~10°, and the length of the cutting edge is the most. The length is the main section of the downward grinding casing; the third section cone slope is basically the same as the orientation of the orienter, and its function is to stabilize the milling cone to enlarge the window; the uppermost section has a taper of zero, and the main function is to trim the window.
After the double-milling cone opens the window, the single-milling cone is a tool for continuing to lengthen the window. The main working surface is the bottom cutting edge, and the side cutting edge with the side slope and the inclined surface of the orienter expands, which can be used to lengthen the bevel along the orienter. Window to the maximum position.