Internal pressure forming method for forming a hollow cylinder, in particular for producing a drum casing for a washing drum of a laundry treatment appliance, which method comprises the following method steps: - positioning the hollow cylinder relative to an outer die and an inner die; - sealing an interior space delimited by the hollow cylinder and the inner die at the first free end (6.1) of the hollow cylinder and at a second free end (6.2) of the hollow cylinder that is opposite the first free end (6.1), the interior space being completely circumferentially sealed off from the free environment by means of a first sealing means and by means of a second sealing means; - introducing a pressure medium into the interior space formed by the seals at the first and the second free end (6.1, 6.2) of the hollow cylinder by means of the first and the second sealing means (12, 16), the hollow cylinder and the inner die; - expanding the hollow cylinder in the interior space by means of an internal pressure generated by the pressure medium located in the interior space, characterized by - fixing the hollow cylinder between the outer die and the inner die at the first free end (6.1) of the hollow cylinder, the hollow cylinder being fixed, at its first free end (6.1), relative to the outer die in the axial direction of the hollow cylinder by means of a fixing device, the hollow cylinder being movably guided, at its second free end (6.2), relative to the outer die in the axial direction of the hollow cylinder by means of the second sealing means arranged on the inner die, a substantially free continual flow of the hollow cylinder being made possible at the second free end (6.2) of the hollow cylinder until a predetermined final pressure of the pressure medium in the interior space has been reached and the second sealing means being moved in the axial direction of the hollow cylinder in such a way that a relative movement between the hollow cylinder and the second sealing means is substantially prevented. - positioning the hollow cylinder relative to an outer die and an inner die; - sealing an interior space delimited by the hollow cylinder and the inner die at the first free end (6.1) of the hollow cylinder and at a second free end (6.2) of the hollow cylinder that is opposite the first free end (6.1), the interior space being completely circumferentially sealed off from the free environment by means of a first sealing means and by means of a second sealing means; - introducing a pressure medium into the interior space formed by the seals at the first and the second free end (6.1, 6.2) of the hollow cylinder by means of the first and the second sealing means (12, 16), the hollow cylinder and the inner die; - expanding the hollow cylinder in the interior space by means of an internal pressure generated by the pressure medium located in the interior space, characterized by - fixing the hollow cylinder between the outer die and the inner die at the first free end (6.1) of the hollow cylinder, the hollow cylinder being fixed, at its first free end (6.1), relative to the outer die in the axial direction of the hollow cylinder by means of a fixing device, the hollow cylinder being movably guided, at its second free end (6.2), relative to the outer die in the axial direction of the hollow cylinder by means of the second sealing means arranged on the inner die, a substantially free continual flow of the hollow cylinder being made possible at the second free end (6.2) of the hollow cylinder until a predetermined final pressure of the pressure medium in the interior space has been reached and the second sealing means being moved in the axial direction of the hollow cylinder in such a way that a relative movement between the hollow cylinder and the second sealing means is substantially prevented.