A blowing head, a method for producing a blown film, and a blown film installation include the use of plate spiral distributors in blown film installations for distributing melt steams arriving from extruders and for combining the melt streams to form an annular gap stream in several layers in an annular gap leading to a tubular die. The melt streams in a plate spiral distributor are initially bundled and then forwarded in a bundled manner to a common co-extrusion flow. The distributer has a plurality of spirals in superimposed layers, and the spirals of two layers have a junction for pre-combining the melt streams of two layers, and in that starting from the junction, a common guide leading to the annular gap is provided for combining there the pre-combined melt streams with the annular gap stream.