Method for manufacturing moulded parts

A method for manufacturing moulded parts, in comprising the following steps:

• a) providing a device comprising:
• a first pressing tool,
• a second pressing tool,
• at least one membrane, and
• at least one seal,
• wherein the first pressing tool and the second pressing tool can be moved relative to one another between an open position and a closed position,
• wherein a working space for a workpiece is formed between the first pressing tool and the second pressing tool,
• wherein the membrane is arranged at least in sections between the first pressing tool and the second pressing tool,
• wherein the membrane is arranged at least in sections in the working space,
• wherein at least one cavity for a working medium is formed between the membrane and the first pressing tool and/or the second pressing tool at least in the closed position,
• wherein the cavity can be sealed by the seal at least in sections at least in the closed position,
• wherein, in order to seal the cavity, a sealing force (FD) can be applied to the membrane by means of the seal, and
• wherein the membrane and the first pressing tool and/or the second pressing tool have different thermal expansion coefficients,
• b) applying a sealing force (FD) by means of the seal to the membrane,
• wherein the cavity is sealed at least in sections by applying the sealing force (FD) to the membrane, and
• wherein a frictional force;
• (FR) is applied between the membrane and the seal by the sealing force (FD),
• c) applying pressure and/or temperature to the membrane,
• wherein the membrane extends at least in sections at least in the working space,
• wherein pressure is applied to the membrane,
• wherein the pressure counteracts an expansion of the membrane into the cavity and thereby effects an expansion force (FA) along the membrane surface, and
• wherein the expansion force (FA) counteracts the frictional force (FR) between the membrane and the seal at least adjoining the seal,
• wherein
• the membrane can be passed by the seal and in that in step c), the membrane is passed by the seal at least in sections due to the expansion force (FA).