| 摘要 |
The construction of the device includes an inner tube (1), a tubular outer case (2) and a connection device (3) for connection to an associated blowing head (Blk) of the film-blowing system. The outer case (2) surrounds the inner tube (1) with an annular gap. The thermoplastic tube (Ks) emerging from a die gap of the blowing head forms, together with the outer case (2), an annular flow channel (5) surrounding said outer case (2). The outer case (2) is provided at its bottom and top with outlet openings (6,7) for the introduction of blowing air into the flow channel (5) or into the film bubble (Fb). Distributed over the length of the assembly comprising inner tube (1) and outer case (2) there is arranged, towards the bottom side, at least one blowing-air suction device ( ), by means of which blowing air can be sucked out of the flow channel (5) and be introduced into the inner tube (1). At least one further blowing-air outlet (9) is arranged towards the top side at a distance from the top outlet opening (7) and is intended for introducing blowing air into the flow channel (5). The blowing-air suction device (8) and the additional blowing-air outlet (9) are aerodynamically matched to one another for the purpose of stabilising the plastic tube and/or the film bubble. <IMAGE> |
