Structural Composition of Shanghai Rotary Drilling Roller Cone Bit

　　Bit Leg

　　A cone on which teeth are mounted (or milled), divided into single cone and multiple cone. The single cone consists of main cone and back cone. The bit leg is the main part of the roller cone bit. A bit is assembled and welded together by three bit legs. The upper part has connecting threads to connect with the drilling tool, and the lower part is made into a journal with a certain inclination angle, forming a bearing pair with the inner hole of the cone. The bit leg has water hole channels, and an oil storage pressure compensation device can be installed. The journal bears the load and requires high wear resistance and hardness, while the matrix interior needs sufficient strength and impact toughness. II. Cutting Structure The cutting structure includes the cone and teeth. The cone is composed of... The single cone cone moves in pure rolling at the bottom of the well, suitable for drilling hard formations. The multiple cone consists of three parts: main cone, secondary cone and back cone. This kind of cone can not only roll but also slide when working at the bottom of the well, used for drilling softer formations. The teeth on the cone are divided into insert teeth and steel teeth. Insert teeth are made by drilling holes on the tooth ring of the outer cone surface of the cone and inserting hard alloy teeth of different sizes and shapes; steel teeth are directly milled from the cone body. The rows of teeth of the three cones on the bit mesh with each other, which can effectively and non-repetitively break the bottom hole rock and prevent tooth groove balling. The shape, size, number and length of teeth depend on the hardness of the formation being drilled. The softer the formation, the larger, sharper and fewer the teeth are arranged. Conversely, the harder the formation, the smaller, shorter and more numerous the teeth.