| 摘要 |
Extruded thermoplastic tubing, e.g. polyethylene tubing, is passed through a pleating die G and blown into shaping contact with the walls of the die by internal air pressure to form continuous longitudinal tucks or pleats in the tube, the pleated tube being finally flattened by pulling rolls and wound on a reel. The die G <PICT:0670707/IV (a)/1> comprises a top plate 31, which may be transparent, a bottom plate 30 and two pairs of tapering side members 32, 33, the members 32, 33 at each side having a blade 35 between them. The blades 35 form the tucks in the tubing. The assembly is secured together by bolts 34 and the members 32, 33 and 35 are laterally adjustable to the positions for obtaining regular tucking and flattening of the tube to the desired final form. The adjustment of members 32, 33 is facilitated by yokes 37 which are clamped to the die G and carry bolts 39a, 39b, for pushing the members 32, 33 inwardly. Means for pulling them out may also be provided. Two yokes, one at each end, may be provided at each side, or one only which is moved as necessary. Similar means may be provided for adjusting the pleating blades 35 within the limits provided by slots 36 through which the bolts 34 pass. As described, the tubing before entering the die G is expanded, cooled, sized, and partly flattened in the manner described in Specifications 664,412 and 670,708. |
