| 摘要 |
1,159,625. Shrink wrapping. E.I. DU PONT DE NEMOURS & CO. 9 Aug., 1967 [10 Aug., 1966], No. 36618/67. Heading B8C. [Also in Division F4] An apparatus for shrinking the protruding areas of a heat shrinkable film overwrap in the form of a sleeve comprises a tunnel that has at either end two discharge ports blowing hot air into the tunnel and directing the air on to the protruding areas. The whole overwrap may then be uniformly shrunk in a second tunnel. Air enters oven A by openings 32, passes through blower 68, over an electric resistor heater 34, via holes 36 into two pipes 20 and thence via ducts 22 to discharge ports 28, arranged in pairs at both ends of the tunnel. A probe 38 regulates the air temperature. Swivel elbow joints 26 permit the direction of the air stream to be varied. When no package is in the tunnel, ducts 22 are positioned so that the ports 28 blow air into openings 32 for recirculation. When a package enters the tunnel a sensing arrangement, e.g. a light 40 and photo-cell 42 arranged diagonally across the tunnel, actuate a cylinder 44 whose piston-rod 48 operates via rods 52, 54 to rotate pipes 20 about their axes and thus move ducts 22 into the operating position shown. After leaving oven A, the package may have its overwrap uniformly shrunk in a second oven (B) (Figs. 1 and 3, not shown), comprising a tunnel whose top, bottom and walls comprise an arrangement of diffuser plates (Fig. 9, not shown) through which heated air is passed and conveyer 14 may have a surface made up of idler rollers that in oven B may be caused to rotate by stationary friction members beneath them to cause the package to accelerate and thus assist uniform shrinkage. |
