| 摘要 |
A retreading envelope is produced by extruding an elastomeric material in substantially tubular form, with portions of the wall thickness of the circumference of the extruded tubing being of a thickness substantially greater than the wall thickness of the remainder of the tubing, cutting a length of the extruded tubing from the tubing as extruded, and butt-seaming the free ends of the cut length to form an annular tube substantially of circular cross-section, with the thickened wall portions of the extruded length in the area of its outer periphery. The elastomeric material in the thickened wall portions of the annular tube is then caused, e.g. by air under pressure, to flow to give the annular tube a substantially flattened outer periphery, and partially flattened side portions joining the flattened periphery with the curved body of the annular tube, so that the side portions have less curvature than said body, while curing the elastomeric material, and the inner surface of the cured annular tube is then slit.
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