Patent GB-1339823-A (GB)
Title: Apparatus for making flattening and hauling off blown tubular plastics film
IPC: B29C48/90
Filed: 1971-06-30
Abstract: 1339823 Tubular film apparatus WINDMOLLER & HOLSCHER 30 June 1971 [19 Aug 1970 16 Nov 1970] 30721/71 Heading B5B Apparatus for making blown tubular plastics film comprises an extruder 1, a vertically upwardly operative blowhead 2, stationary flattening plates 4 provided vertically above the blowhead downstream of a position at which the film has solidified, direction changing means including rolls 5, 7 for diverting the film through 180 degrees, said rolls having grooves 6, 8 permitting the passage of inflating air from the blowhead, to form bubble 311 and second flattening means for the film, including squeeze rolls 10, disposed at a spacing from and vertically below the downstream end of the direction changing means. In the apparatus of Fig. 2, the coiling means are stationary and use is made of a system of turning bars for leading the flattened film from the oscillatingly rotatable second flattening means to the stationary coiling means. The flat bubble 3<SP>1</SP> of film confined between the cylinders 9 between the direction changing rolls 5 and 7 is surrounded by a cooling jacket 28 through which cooling air is forced by a fan 30 preferably in the direction of arrows 29, namely in countercurrent to the feeding direction of the film. The bubble 311 of film is flattened by reversibly rotatable second flattening means comprising flattening plates 32 and squeeze rolls 31 and then passes over a system of turning bars 33 which swing out laterally like a fan. Reversible rotation through 360 degrees for the flattening plate 32 and squeeze rolls 31 is effected by motor 34 and takes place in the direction of the arrows 35, the individual direction changing shafts of the turning bar system about which the film is passed being oscillatingly rotated in unison with the flattening means but to an ever-decreasing extent as the film moves further away from the flattening means. The reversingly rotatable flattening plates, squeeze rolls and turning bar system are carried by frames 36 which is supported on coiling device 37 and which may also be used for accommodating a printing station 38 for the film and/or slitting means for slitting the flattened tubular film before winding it on a double winder. Positively driven haul-off rolls 41 are provided downstream of the turning bar system. One of these haul-off rolls is in contact with the film that is being coiled on reel 39 so that it is also effective to turn the reel and a separate drive for the reel can be dispensed with, provided the turning bar system does not cause the length of film between the blowhead and the reel to vary periodically. Bubble 3 is guided by calibrating means 18 disposed at the location where the plastics film solidifies and comprising supporting ring segments 19 provided with a readily rotatable covering and which are adjustable in diameter in the same way as the iris diaphragm of a camera. Bubble 3 is cooled by means not shown, before being flattened by plates 4. Auxiliary cylinders 9 limit the degree of inflation between the direction changing rolls 5, 7. The cylinders may be used as additional cooling means if water-cooled, or alternatively flat cooling plates or gratings may be used. The re-inflated film bubble 3<SP>11</SP> is guided by cooling means similar to the calibrating means but in which the supporting ring segments are replaced by water-cooled pipe segments 23 for cooling the film. The pipe segments 23 are disposed above the rotatable haul-off and coiling means 12 to 17 and coaxially therewith so that the flattened film will not be displaced laterally on the reel 13. The operation of the apparatus is simplified if the segments 19 and 23 of the calibrating and cooling means, respectively, are radially adjustable in unison to conform in diameter to a particular desired diameter of film. Such simultaneous adjustment is diagrammatically indicated by an adjusting shaft 26 connected at 27 to the calibrating and cooling means. The reinflated film now reaches reversibly rotatable haul-off means comprising hauloff rolls and further flattening plates 11, whereafter the film is passed over a contact roll 12 and coiled on a reel 13, both of which are reversibly rotatable together with the haul-off means by being mounted on a common frame 14 supported on the floor by bearings 15. The reversible rotation is indicated by the arrow 16. Contact roll 12 is effective to turn reel 13. Rotary movement on the bearings 15 is effected by a motor, not shown, of which the direction of rotation is reversed every 360 degrees. To simplify reel replacement, the full coil is preferably deposited on the floor or in a vehicle with the aid of hydraulically braked arms 17.