| 摘要 |
<p>A preform (36) for a protective helmet is made from resin-impregnated blanks cut from a length of reinforcing fabric (10) along a zig-zag line (13) so that each part (14, 15) has a straight edge (11, 12) and a series of teeth (18, 19) defining the opposite edge. Lengths are cut off from each part (14, 15) to form the blanks and are wrapped in a plurality of layers around a cylindrical former, sized to correspond to the head size of the helmet, so that the teeth in successive layers are in staggered relationship. The layers are then compressed in a press (34, 35) to bend the teeth (18) over into mutual engagement and form a rigid domed preform (36).</p> |
