| CPC E21B 10/567 (2013.01) [E21B 7/15 (2013.01)] | 10 Claims |
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1. A combined drill bit, comprising:
a ground electrode, an insulating rod, an electrode spring, a connecting electrode, an insulating spline sleeve, an upper bearing, a conical connecting component, a polycrystalline diamond compact (PDC) bit, electrode screws, an electrode drill bit spring, a lower bearing, a cable connector, an insulating limit cover, and an end cover;
wherein the ground electrode is a cylindrical structure, a lower end of the ground electrode is provided with a centrally symmetrical petal-shaped structure, and a circumferential surface of an upper part of the ground electrode defines screw holes and a welding hole configured to weld an earth cable;
wherein an upper part of the insulating rod is provided with a spline, an upper end surface of the insulating rod defines drilling fluid flow channels and a cable hole configured to install the earth cable, a center axis of the insulating rod defines an electrode-installed hole, a middle-lower part of the insulating rod defines electrode screw holes, and a lower part of the insulating rod is provided with a conical structure;
wherein the connecting electrode is a rod-shaped structure, a lower end of the connecting electrode is provided with a conical structure, a middle-lower part of the connecting electrode is provided with a spring step installed with the electrode spring, and an upper part of the connecting electrode is provided with a connector step and a threaded structure which are connected to the cable connector;
wherein the insulating spline sleeve is a hollow structure, an upper part of the insulating spline sleeve is provided with an outer step and screw threads which are matched with the insulating limit cover, an inner part of the insulating spline sleeve is provided with a spline structure matched with the insulating rod, and a lower part of the insulating spline sleeve is provided with a lower bearing step matched with the lower bearing;
wherein the cable connector is a cylindrical structure, a center of an upper end surface of the cable connector defines a cable groove configured to weld cables, and a center axis of a lower part of the cable connector defines a threaded hole matched with the connecting electrode;
wherein a center of the insulating limit cover defines a limit cover through-hole, an inner part of the insulating limit cover is provided with a limit cover inner step and screw threads which are matched with the insulating spline sleeve, and an outer circumferential surface of the insulating limit cover is provided with an upper bearing step matched with the upper bearing;
wherein a center axis of the end cover defines a flow channel, an outer circumferential surface of the end cover is provided with screw threads matched with the PDC bit, and a lower part of the end cover defines an annular groove installed with the insulating limit cover, the lower part of the end cover is provided with a bearing step fixed with the upper bearing, and the lower part of the end cover is further provided with an inner step, and an upper surface of the end cover defines square grooves;
wherein the PDC bit is a hollow structure, the PDC bit is provided with an internal bearing step installed with the lower bearing, an inner cylindrical surface of a top of the PDC bit is provided with screw threads matched with the end cover, and the PDC bit defines drilling fluid holes; and
wherein the conical connecting component is a hollow structure and is fixedly connected with the PDC bit by welding.
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