Multi-cavity mold with a knife pressure-box for a thermoforming machine used in the process of high-volume, continuous thermoforming of thin-gauge plastic products

A multi-cavity mould (1) for a thermoforming machine used in the process of high-volume, continuous thermoforming of a plurality of thin-gauge plastic products (2) from a preheated thin-gauge thermoplastic sheet (3) comprising:

• an upper tool (11) and a lower tool (12) arranged in a cooperating manner;
• the lower tool (12) comprising:
• a plurality of cavities (8) for receiving cavity moulds (8′) and
• a plurality of base plates (91) from which a plurality of supporting blocks (92) extend perpendicularly over a predetermined total height (a), situated between adjacent cavities (8) and
• the upper tool (11) comprising:
• a top base plate (4) and
• a plurality of plug moulds (5) arranged in an x-z array and connected in a translational manner to said top base plate (4) by means of driving rods (6) such that said plug moulds (5) are movable in a direction (y) perpendicular to a transport direction (x) of said preheated thin-gauge thermoplastic sheet (3)
• characterized in that
• said upper tool (11) further comprises a knife pressure box (13) comprising:
• a horizontal top plate (131) connected to said top base plate (4);
• first and second vertical end plates (132) extending orthogonally downwardly from a lower surface of said horizontal top plate (131),
• first and second vertical side plates (133) extending orthogonally downwardly from said lower surface of said horizontal top plate (131) wherein
• the first and second end plates (132) and the first and second side plates (133) are connected such that the horizontal top plate (131), the first and second end plates (132) and the first and second side plates (133) form a downwardly open rectangular parallelepiped enclosure;
• the first and second end plates (132) and the first and second side plates (133) are made from tool steel with a thickness (t) measured from 6.35 mm to 10 mm and have a cutting surface (130) defined along an orthogonally downwardly projecting end of said end and side plates (132, 133) wherein
• said cutting surface (130) has a substantially V-shaped profile comprising a micro flat face (M) with a width from 0.02 mm to 0.1 mm and is positioned such that when said knife pressure box (13) is pressed against the preheated thin-gauge thermoplastic sheet (3), the cutting surface (130) partially penetrates the preheated thin-gauge thermoplastic sheet (3) in order to form a seal around the knife pressure box (13) by pressing a zone of said thermoplastic sheet (3) which was partially trimmed and which is situated inside the rectangular parallelepiped enclosure against the cutting surface (130).