Cock valve structure improvement and strength calculation

Cock valve is with hole plug body as open-close part, through the plug body and the valve rod rotation realize on-off movement. ball valve gate. Cock valve has simple structure, rapid opening and closing, the fluid resistance is small. We for the cock valve used in drilling problems made some improvement and strength calculation. Cock valve opening and closing is a perforated cylinder, perpendicular to the axis of rotation of the channel, so as to achieve the aim of opening and closing the channel. Cock valves are mainly used for opening and closing medium pipeline and equipment. Cock valve valve door main advantages are: apply to often operation, opening and closing fast, lightweight. Fluid resistance is small. Simple structure, relatively small volume, light weight, easy to maintenance. Sealed performance is not limited by the installation direction, the flow of medium can be arbitrary. No vibration, low noise. But cock valves are often used in the drilling turned off not easily open problems, this paper discussed a series of this issue and improve it. 1 under the effect of three kinds of given load, under the action of tensile load of the highest stress, minimum safety factor. Therefore, the strength condition under tensile load is the main contradiction. 2 stretch to cock valve materials commonly used 40 crmnmo calculation, safety coefficient is 1. 71 > 1. 5, can satisfy the strength requirement. Under tensile load knob orifice in the stress concentration is larger, the stress concentration at the material yield limit, according to a new strength criterion, the maximum stress concentration point 935. 75 mpa 4 inner grooved stretching in the benchmark stress and stress is bigger also, but can satisfy the strength requirement. When the design should pay attention to reduce the stress concentration. 5 in a given torque and under internal pressure loading and the safety factor of the dangerous section are very big, can not consider the strength problem.