Assembled double wall preform, and process for the making thereof

Assembled preform (1) according to any of the preceding claims, wherein said internal preform (11) further comprises:

• said protruding contacting region (13) at the outer surface of the neck region (12) consists of a substantially smooth annular region,
• said protruding contacting region (14) at the outer surface of the neck region (12) consists of a protruding annular edge, which has a series of vertical grooves (110);
• a series of ports (15) each shaped like a rectangular slot, and being perimetrically formed at the neck region (12), each port (15) communicating said outer surface of the neck region (12) with the inner surface of the latter, and wherein each port (15) communicates with a longitudinal and vertically shaped groove (150) arranged and formed at said inner surface of said neck region (12);
• and
• at a region below said protruding contacting region (14), a series of protruding elements (111) are integrally formed onto the surface of the internal preform (11), said elements (111) having a longitudinal shape and being arranged in an inclined manner with respect to the longitudinal axis of said internal preform (11).

Assembled preform (1) according to any of the preceding claims, wherein said internal preform (11) further comprises:

• said contacting surface at said outer surface of said neck region (12) of said internal preform (11) consists of a continuous substantially smooth annular surface (16);
• said contacting surface (16) having a plurality of longitudinal grooves (110) each of which communicating with a respective groove (150) formed onto said inner surface of said neck region (12) and each communicating with the other through a respective opening (15);
• and
• at a region below said contacting surface (16), a series of protruding elements (111) are integrally formed onto the surface of said internal preform (11), the elements (111) having a longitudinal shape and being arranged in an inclined manner with respect to the longitudinal axis of the preform (11).

Process for the manufacturing of an assembled preform (1) for the making of a double-walled blown container, the preform (1) comprising a first external preform (10) which comprises a neck part (2) having an outer region (4) which includes a threaded region (5), and an inner region (3), and a second internal preform (11) arranged inside said first external preform (10), said internal preform (11) having a neck region (12) configured to cooperate in a locked manner with said neck region (3) of said external preform (10), and wherein an inner volume (6) is defined between said first external preform (10) and said second internal preform (11), said volume (6) being adapted to contain a gas, and wherein said neck region (12) of said internal preform (11) comprises locking means (13, 14, 16) configured for cooperating by a locking interference with said inner region (3) of said neck part (2) of said external preform (10) when said internal preform (11) is inserted in said first preform (10),

• characterized in that it comprises the following steps:
• Separate forming of said external preform (10) and said internal preform (11) by an injection moulding process for each preform (10,11);
• Inserting of said internal preform (11) inside said external preform (10) until the neck part (12) of the internal preform (11) abuts on the neck part (3) of the external preform (10);
• Exerting a thrust force onto the internal preform (11) towards the inside of the external preform (10) by forcing the coupling by interference through said locking means (13,14, 16) onto the surfaces (12) and (3) of the respective neck regions of said preforms (10,11);
• Obtaining an assembled preform (1) in an assembled and irreversibly locked arrangement;
• and
• Sending said assembled preform (1) to the subsequent production steps to obtain a double-walled blown container.