| 摘要 |
1,148,243. Seaming non-metallic sheet material. FLUORODYNAMICS Inc. 22 July, 1966, No. 33206/66. Heading B5K. [Also in Division F2] Large diameter rolls, e.g. paper machine dryers, are provided with a covering of heatshrinkable thermoplastic material, e.g. heatsealable fluorinated ethylene polymers, by forming the covering material into a distended tube, positioning the tube about the roll to be covered, and applying heat to the tube to shrink it into a tight fit on the roll. The covering material may be distended prior to forming the tube. Forming the tube, Figs. 1, 3.-The sheet material 23, 24 is positioned on longitudinally extending flanges 11, 12, with its edges 21, 22 slightly spaced, and retained in this position by magnetic members 26. Thin foils 27, 28 are positioned respectively below and above the sheet. Members 29, 30 are adapted to be driven along the length of the seam, and comprise pressure plates 31, 32 with a small central electrically heating area, surrounded by water cooling tubes 39, 40 to limit the heating to the adjacent edge portions of the sheet. To join the two sheet sections, the members 29, 30 are brought up to the required heat, and are then driven by motor 49 along the length of the join, the sheet material first thermally expanding substantially into contacting relation and then flowing and fusing together to form a butt seam. On disconnecting members 29, 30 from their driving cables 41, 42, the formed tube may be removed from flanges 11, 12 by drawing a wall portion of the tube between rollers 15, 16. By appropriate loading of the rollers and by moving the tube, the seam may be calendered as the tube is removed. Distending the tube, Fig. 7 (not shown).-The tube is placed around two spaced rollers (50), (51) supported on arms (54), (55) expanded by an hydraulic piston-and-cylinder (56), (57). By driving the rollers in the same sense, the tube is uniformly distended. Alternatively, Fig. 8 (not shown), each end of the sheet, prior to being formed into a tube, is wound round a roller, each roller being driven in an opposite direction to distend the sheet, leaving unstretched end portions. The flanges 11, 12 and associated sealing means of the tube forming apparatus are then placed on the roller to be covered, and the distended sheet formed into a tube about the roller and flanges. Shrinking the tube, Fig. 10.-The tube is placed on the roll 74 with one end 70 extending. A source 71 of hot air is then rotated around the extended end 70 of the tube to shrink it, as shown, to fix that end. The other end is then resiliently held by springs (86), Fig. 11 (not shown), to apply axial tension to the tube and to maintain it in concentric relation to the roll. The source 71 is then moved axially along, and around the tube to shrink it into a tight fit on the roll. |
