| 摘要 |
A blowhead for making tubular plastics film comprising a housing having a central aperture for installing special equipment, a lateral supply passage in the housing for the entry of molten plastics material, branch passages which branch from the supply passage and extend, each in its own direction, through 90 DEG about an insert in the housing, are then shortly curved to divert the flow of plastics material axially of the blowhead against the direction in which film is blown, and then diverge constantly in the peripheral direction until they merge at positions at an end of the insert, recesses formed in the housing adjacent the end of the insert to direct the flow of plastics material over projecting surfaces provided on the end of the insert and into an annular passage leading to a nozzle orifice from which the plastics material is blown as a film, the projecting surfaces and recesses extending in the direction opposite to the film blowing direction such that, starting from the sharp curvatures, the flow path for the plastics material to the nozzle orifice has the same length in every angular direction of the diverging portions of the branch passages.
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