| 摘要 |
933,933. Grommets. HEYMAN MANUFACTURING CO. Nov. 8, 1960 [Nov. 13, 1959], No. 38350/60. Class 89 (1). A self-locking bushing or grommet of the type installed by applying thereto a force directed substantially along the longitudinal axis comprises a flexible body portion 10 with a non-split wall 10a with means for retaining the bushing in an apertured panel, the portion 10 having a flexible head 11, the flexible flanged portion 12 of which constitutes part of the bushing-retaining means, having an outside edge 14 positioned as shown in Fig. 2 to provide a first locking surface, the portion 10 having locking steps 21, 22 and 23 (Figs. 1 and 2) providing second locking surfaces as another part of the retaining means, the first locking surface extending radially outwardly beyond these surfaces, the body portion 10 being readily distortable cross-sectionally for installation. The cross-section of the head 11 of the bushing is arcuate, extending outwardly as shown through substantially 180 degrees, the radius of curvature of about 90 degrees of the cross-section from the edge 14 being greater than that of the cross-section immediately adjacent to it. The head 11 has at least two notches, e.g. three- 18, 19, 20, radially disposed and extending to the first locking surface, being longitudinally aligned with the steps 21, 22 and 23 and circumferentially spaced at an angle of 120 degrees. With sufficient flexing of the arcuate head 11 of the bushing (Fig. 8b), having the surface 14 of the flanges 12 a distance d radially outward from the body portion 10 and the inside surface of the head 11 a maximum height H from the plane of the surface 14, to make the distance d increase to a distance D and the height H decrease to a height h, the ratio of D to d becomes at least 4 to 3 and H to h at least 7 to 4. The material of the bushing has preferably a high value of electrical resistance and a flexural modulus of the order of 175,000 Ib/square inch. |
