Mould for the production of closures in compression moulding machines

A method for making a closure of plastic material with a tear-off membrane, by compression moulding, comprising the following steps:

• preparing a mould, having a male die element and a female die element, the female die element including:
• a first block, a second block and a third block, aligned with each other and movable along a moulding orientation;
• feeding a charge of material to the mould;
• closing the mould by moving the male die element and the female die element of the mould closer together along the moulding orientation;
• extruding the charge of material into an expansion chamber delimited by the walls of the male die element and of the female die element;
• opening the mould by moving the male die element and the female die element of the mould away from each other along the moulding orientation;
• withdrawing the closure from the mould,
• wherein a first spring, interposed between the first block and the second block, applies a first force along the moulding orientation, between the first block and the second block, and
• wherein a second spring, interposed between the second block and the third block, applies a second force along the moulding orientation, between the second block and the third block.

A method for making a closure of plastic material with a tear-off membrane, by compression moulding, comprising the following steps:

• preparing a mould, having a male die element and a female die element, the female die element including:
• a first block, a second block and a third block, aligned with each other and movable relative to each other along a moulding orientation;
• closing the mould by moving the male die element and the female die element closer together along the moulding orientation to compress a charge of material so as to form the closure;
• opening the mould by moving the male die element and the female die element away from each other along the moulding orientation to allow withdrawing the closure from the mould, and wherein, while the mould is being opened, the first block moves away from the second block and the second block moves away from the third block,
• wherein, when the mould is closed, the first block and the second block are in contact with each other,
• wherein, when the mould is closed, a first spring applies a closing force along the moulding orientation to keep the second block and the first block in contact with each other when no other forces are applied.

A method for making a closure of plastic material with a tear-off membrane, by compression moulding, comprising the following steps:

• preparing a mould, having a male die element and a female die element, the female die element including:
• a first block, a second block and a third block, aligned with each other and movable relative to each other along a moulding orientation;
• closing the mould by moving the male die element and the female die element closer together along the moulding orientation to compress a charge of material so as to form the closure;
• opening the mould by moving the male die element and the female die element away from each other along the moulding orientation to allow withdrawing the closure from the mould, and wherein, while the mould is being opened, the first block moves away from the second block and the second block moves away from the third block,
• wherein, when the mould is closed, the first block and the second block are in contact with each other,
• comprising a step of releasing the closure from the mould, the step of releasing including the following sub-steps:
• moving a central block of the male die element along the moulding orientation towards the female die element in a slide cavity formed in an annular body of the male die element;
• moving an outer bush of the male die element along the moulding orientation towards the female die element relative to the annular body.