The invention relates to a method for the extrusion of preforms, which emerge vertically from the underside of an extrusion die (1) from an annular die gap (5) of the extrusion die and are expanded by blow molding into hollow plastic bodies. The geometry of the die gap (5) is changed during the extrusion of the preforms, wherein for changing the die gap geometry at least one elastically deformable sleeve (7) is used, which is arranged horizontally adjustable within the extrusion die (1). For horizontal adjustment and elastic deformation of the sleeve (7), at least two program-controlled actuators (8, 8 ') are provided, which at force application points (9, 9'), which are offset by 180 °, on the circumference of the elastic sleeve (7 ) Act. The travel paths of the actuators (8, 8 ') are controlled according to the invention using a synchronously with the extrusion of the preforms running program control (13), which determines the movements of the force application points (9, 9') by superposition of two movement components (14, 15) , The first movement component (14) allows a symmetrical deformation of the sleeve (7) and consists of opposing and amount equal to the same positioning paths of the force application points (9, 9 '). The second movement component (15) allows a horizontal positional displacement of the sleeve (7) and consists of rectified and the amount equal to the same positioning paths of the force application points (9, 9 '). For the first movement component (14), a limit value (GW14) for the maximum permissible travel is specified.
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