The opening and closing member of the plug valve is a perforated cylinder that rotates about an axis perpendicular to the passage to achieve the purpose of opening and closing the passage. Plug valves are primarily used to open and close pipes and equipment media. It is understood that the main advantages of the plug valve are: suitable for frequent operation, quick opening and closing, and light. The fluid resistance is small. The utility model has the advantages of simple structure, relatively small volume, light weight and convenient maintenance. The sealing performance is not limited by the installation direction, and the flow direction of the medium can be arbitrary. No vibration, low noise. However, the plug valves used in drilling often have problems that are not easy to open after closing. This paper has carried out a series of discussions and improvements on this issue.
1 Under the three kinds of given loads, the stress under the tensile load is the highest and the safety factor is the smallest. Therefore, the strength conditions under tensile load are the main contradiction.
2 Stretching is calculated by the commonly used plug valve material 40CrMnMo, and the safety factor is 1.71>1.5, which can meet the strength requirement.
3 Under the tensile load, the stress concentration at the orifice of the knob is large, and the yield limit of the material is reached at the stress concentration point. According to the new strength criterion, the maximum value of the stress concentration point is 935.75 MPa<2 MPa, which satisfies the stability condition.
4 The reference stress and stress in the inner groove during stretching are also large, but the strength requirement can be met. Care should be taken to reduce the stress concentration here.
5 Under the given torsion and internal pressure load, the safety factor of each dangerous section is very large, and the strength problem can be ignored.
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Label: Structural Improvement and Strength Calculation of Plug Valves
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