| 摘要 |
<p>668,876. Flexible conduit cores. DUCTUBE CO., Ltd. Aug. 16, 1949, No. 21323/49. Class 99 (ii). [Also in Group V] A cord sheath 3 is braided over an uncured or tacky rubber layer.2 applied on a mandrel 1 of selected size, and the sheath is wetted by a layer of rubber cement over which is applied an outer rubber sheath 4 that may be in the form of a helically-wound strip. The core, which may have a removable wrapping of canvas or the like, is steam cured and removed from the mandrel, and a closure is secured at one end and a valve at the other end of the core The sheath strands may be at an angle of at least 42 degrees to the axis of the core when inflated, the angle changing upon deflation so that the core in twisting is freed from a surrounding mass of concrete.</p> |
