Patent ID: 7396221

Claim:
A mould for forming the top of deformable tubular plastic containers comprising a tubular body ( 51 ) and a headpiece ( 52 ) of plastic material bonded to one end of the tubular body ( 51 ), the mould comprising: a punch ( 10 ) having an outer surface ( 11 ′) arranged to engage the container tubular body ( 51 ) as an exact fit, and an end portion ( 13 ) projecting axially from the lower end of the cylindrical outer surface 8 ( 11 ′) and a die ( 30 ) arranged to form, in combination with the lower surface ( 13 ′) of the punch, a cavity (F) for forming the headpiece ( 52 ) of the container, said die ( 30 ) having a concave surface ( 32 ′) arranged to receive as an exact fit, by axial penetration, the lower end of the cylindrical outer surface ( 11 ′) of the punch together with the lower end of the tubular body ( 51 ) of the container, the headpiece ( 52 ) being formed within the forming cavity (F) and being pressure-bonded therein to the lower end of the tubular body ( 51 ), the punch ( 10 )/die ( 30 ) comprising a radial deformation means ( 22 , 20 25 , 62 , 65 ), positioned on its outer surface ( 11 ′)/concave surface ( 32 ′), which extends annularly along the entire circumference of this surface to act on the tubular body ( 51 ) of the container, and is arranged to assume a normal position in which its outer surface does not project radially from the cylindrical outer surface ( 11 ′) of the punch/from the concave surface ( 32 ′) of the die ( 30 ), and an active position in which it is urged in a radial direction in such a manner as to press the tubular body ( 51 ) against the opposing surface of the die/punch, characterised in that said radial deformation means are positioned within an annular chamber ( 21 , 61 ) which is provided in the punch ( 10 )/die ( 30 ), is open towards the cylindrical outer surface ( 11 ′) of the punch/the concave inner surface ( 32 ′) of the die, and is in the form of a flexible annular element ( 22 , 62 ) positioned to close the annular chamber ( 21 , 61 ) but with its outer surface not normally projecting from the annular chamber ( 21 , 61 ), said annular element ( 22 , 62 ) being arranged to deform radially until it presses the tubular body ( 51 ) against the opposing surface ( 32 ′) of the die ( 30 )/against the opposing surface ( 11 ′) of the punch, as the result of feeding pressurised fluid into the chamber ( 21 , 61 ).