Sealing performance analysis and structure optimization of pressure-preserved controller for pressure-preserved coring in deep coal mine

As the pressure-preserved controller is a core component of the deep coal in-situ pressure-preserved coring device, its sealing design plays a decisive role in the effect of pressure-preserved coring. In order to obtain the optimal sealing structure, a two-dimensional axisymmetric nonlinear contact model was established for the sealing structure of the pressure-preserved controller. On this basis, the effects of different groove design, cone angle selection and friction coefficient on the sealing performance were analyzed by orthogonal test method. Meanwhile, the stress changes of the sealing ring under different closing stages and medium pressures were studied. The results show that: the pressure-preserved controller with 1.9 mm groove depth and 30° cone angle has the best sealing effect. The friction coefficient has little effect on the sealing performance, and it should be as small as possible according to the actual situation. The results of laboratory pressure test show that the pressure-preserved controller can form a seal under the action of a small preload, and its sealing performance remains stable with the increase of sealing pressure. The adaptive sealing characteristics ensure its sealing ability and working stability. The research results improve the sealing reliability of the pressure- and gas-preserved coring device in deep coal mines, which is of great engineering significance for the accurate determination of gas in deep coal mines.