Abstract: The apparatus comprises a turntable plate arranged on a platform (1), there being tube means (6) mounted on the plate such as to form a conical shape with the aid of a bolted joint (7). To one side of the turntable plate (3) there are arranged on the platform three rollers (12,13,14) and on another part thereof there is arranged a feed roller (29) and guide rolls (31,32). The roller (29) and guide rolls (31,32) are adjustable in two planes in relation to the platform (1). For winding up a boom it is taken between the rolls (31,32) over the feed roller (29) and over the rollers (12,13,14), where the expansion means are flattened so that the boom is wound up in a flattened condition on the tube means (6) forming the conically shaped winding bobin.