| 摘要 |
<p>752,568. Heating by electric resistances. CELANESE CORPORATION OF AMERICA. Jan. 27, 1954 [Jan. 28, 1953], No. 2503/54. Class 39(3). [Also in Groups VIII and XVII] In apparatus for seaming the wrapping film 58 of a package 56 (see Group VIII), a narrow belt 11 passes over a driving pulley 12, a tension roller 27, a hollow heating pulley 16, and a heating shoe 39. Pulley 16 is heated by a stationary electric heater 37 extending into the interior of the pulley, and shoe 39 is heated by an electric heater 43 with a thermostat 44. Pulley 16- and shoe 39 contact only the central portions of belt II through a peripheral rib 33 on the pulley and an upstanding rib 45 on the shoe. Pulley 16 and shoe 39 are provided with thermal insulation. In operation, a package 56 is fed by belt 11 beneath pressure rollers 68 with the overlap 59 of the thermoplastic wrapping film 58 resting on belt 11 and the edge of the package bearing against a combined support and edge guide 61. - The temperature of the central portion of belt 11 is sufficient to form a seam in the overlap 59. The belt may be made of corrosion-resistant metal such as phosphor bronze or stainless steel ; adhesion between the package and the belt is then reduced by a thin film of a substance, such as silicone oil, to which the heated film material will not adhere, applied by a roller 55 to the outer surface of the belt. Alternatively, the belt may be made of a silicone rubber, or of woven glass fibres impregnated with a heat and adhesion-resistant substance such as polytetrafluoroethylene.</p> |
