Apparatus and method for forming a concave object

An apparatus comprising:

• a feeding device for providing a pre-processed element made of at least one polymeric material, the pre-processed element being a dose of the polymeric material in a molten state;
• at least one mould comprising a female mould part and a male mould part, the female mould part and the male mould part being movable relative to one another in a moulding direction in order to form a concave object from the pre-processed element, the female mould part having a forming cavity;
• a transport device for transporting the pre-processed element towards the mould and releasing the pre-processed element into the forming cavity;
• wherein the forming cavity has a bottom and a lateral region, the lateral region having a transition zone defined by a funnel-shaped surface in which a transversal dimension of the forming cavity progressively passes from a larger value to a smaller value, the transition zone being at a distance from the bottom and being configured to restingly receive the pre-processed element when the pre-processed element is released in the forming cavity by the transport device,
• wherein the feeding device comprises a plasticizing device for plasticizing the least one polymeric material, the apparatus comprising at least one separating element for severing the dose of polymeric material in the molten state from the plasticizing device.

A method comprising the following steps:

• providing a pre-processed element made of at least one polymeric material,
• introducing the pre-processed element in a female mould part having a forming cavity,
• shaping the pre-processed element between the female mould part and a male mould part, the female mould part and the male mould part being movable relative to one another along a moulding direction so as to form a concave object from the pre-processed element,
• wherein the forming cavity has a transversal dimension measured transversely to the moulding direction, the forming cavity further having a transition zone defined by a funnel-shaped surface in which the transversal dimension progressively decreases from a larger value to a smaller value, the forming cavity further having a bottom,
• and wherein, during the introducing step, the pre-processed element is placed in the forming cavity on the transition zone, so that the pre-processed element rests on the funnel-shaped surface at a distance from the bottom of the forming cavity,
• and wherein the pre-processed element, after being located on the transition zone and before starting to interact with the male mould part, is deformed at least in a central zone thereof due to force of gravity, thereby taking a concave shape with a concavity facing upwards.