| 摘要 |
933,171. Heating thermoplastic sheets by electric resistances. E. VOGT, [trading as VOGT & HARTMANN]. June 2, 1960 [June 4, 1959], No. 19597/60. Class 39 (3). [Also in Group V] Apparatus for heating sheets of thermoplastic synthetic material to be shaped, comprises a conveying carriage 40 for supporting a sheet 35 in a predetermined plane, heating elements 52 arranged on one side of the said plane, and a reflection surface arranged on the other side thereof, said reflection surface being secured on the conveying carriage 40 or constructed as the conveying carriage, so that a sheet of said material may rest directly on the said surface during the heating operation. The tunnel oven 46 shown is located between and serves two moulding stations of a vacuum moulding machine (see Group V) and is provided with a bank of infra-red heating elements 52. The carriage 40 has wheels which run on tracks 36 and 37 and its face 41 is made of polished aluminium or aluminium alloy. Infra-red radiation not absorbed on its first passage through the sheet 35 is thus reflected to pass through the sheet a second time. Resistance heating elements 56 (Fig. 4) mounted in recesses in the carriage 40 may serve to supply additional heat to the sheet 35 by conduction while the sheet is in the oven, but serve chiefly to prevent the sheet from freezing to the carriage 40 on emerging from the oven. Recesses 57 communicate with compressed air lines 60 to assist in speedy removal of the heated sheet 35 from the carriage 40. An additional bank of removable infra-red elements (not shown) may be mounted below the carriage 40.
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