摘要 |
<p>The teeth are formed by extruding a plastic tape having edge ribs on one face and a pair of longitudinally spaced ridges on the opposite face, and cutting slots in the tape to define between the slots transverse strips having enlarged central regions. The tape is then folded over along the longitudinal axis with the edge ribs outermost so that the ridges abut and define a recess in which the edge of a backing tape is secured (e.g. by stitching) and so that the folded over strips define teeth. The enlarged central regions of the strips may also be thickened. The teeth are cheap to produce and easily secured to the backing tape.</p> |