Linear-motor-driven simultaneous stretching installation

Method for operating a linear-motor-driven simultaneous stretching apparatus, in particular plastics film simultaneous stretching apparatus, having the following features:

• transport units equipped with transport parts and clips retained thereby are moved along a guide track and/or a transport rail by means of a linear motor drive,
• the edge of a material web is grasped and retained by means of the clips,
• during normal operation, the linear-motor-driven transport units in the simultaneous stretching zone are subjected to an acceleration phase having a normal operation acceleration profile, as the spacing from a following transport unit driven by the linear motor drive becomes increasingly large,
• characterised by the following further features:
• when the material web enters the stretching zone, at least two successive leading clips that are driven by the linear motor are accelerated in the stretching zone in a manner differing from the acceleration profile during normal operation such that the spacing formed between the at least two successive linear-motor-driven clips is less than 80% or less than 75% of the spacing produced during normal operation.