Fundamental Characteristics of a Wedge-Shaped Metal Seal

The fundamental characteristics of a static metal seal made between an annular wedge-shaped asperity of copper and a smooth seal surface of steel were investigated by varing the surface roughness (R_y≒0.1～100 μm) and the semi-angle of wedge (α=15～60°). The following results were obtained from gas leak tests and calculations of contact pressure on the wedge-shaped asperity. (1) The P_c/l(=p_mw_c)-values of the compressive force per unit length for sealing decreased with a decrease in the R_y-and α-values. The recommended values of R_y and α were in the range of R_y <__= 20 μm and α=30° respectively, and it was possible to forecast the P_c/l-values corresponding to that range. (2) The p_c-values of the contact pressure for sealing approximately agreed with the calculated values, p_m obtained from theory of slip-line field of wedge. (3) The w_c-values of the contact width for sealing decreased with a decrease in R_y-and α-values, and were about 50～100 μm in the range R_y