The invention relates to a device and a method for producing preforms (14) with a special geometry, wherein the finished preforms have a neck region with a thread and a preform body, which adjoins the neck region and has an enlarged geometry in comparison with the cavity of the injection mould. The method is characterized in that preforms are produced by injecting a polymer melt into an injection mould, in which the geometry of the impressions forming the cavity in the mould is designed in such a way that the radial extent of the inner space in the preform body thereby produced is not greater than the radial extent of the inner space in the neck region, the preforms are removed from the open mould by a removal gripper, transfer pins of a transfer gripper are introduced into the associated inner space of a preform, the preforms are removed from the removal gripper by means of the transfer gripper and are transferred into a post-cooling device, and the preforms in the removal gripper and/or in the post-cooling device are inflated using positive pressure in such a way that the geometry of the inflated preform body is larger than the cavity in the injecti on mould.