Apparatus for manufacturing screw closures by pressure molding

In an apparatus for manufacturing screw closures having tamper-proof rings provided with retention elements adapted-to engage below a collar of a container to be closed and including a carousel supporting structure that is rotatable about a vertical rotation axis thereof,

• a plurality of pressure molding units including each an upper male half-mold and a lower female half-mold, said male and female half-molds being aligned along a vertical alignment axis that is parallel to said rotation axis of the carousel to form a molding chamber and to further provide a molding pressure in said molding chamber by lifting and respectively forcing the lower female half-mold against the upper male half-mold which is maintained in a stationary position, and wherein each said molding unit further comprises:
• a bowl provided at said female half-mold and forming a cavity which has an annular shoulder;
• a cylindrical jacket provided at said male half-mold, said jacket being fixedly supported at the carousel structure coaxially to said vertical alignment axis;
• a sleeve, which is guided on said jacket and has a lower annular segment that is adapted to engage said bowl;
• a plunger, which is guided in said jacket;
• return elastic means for urging said plunger in a raised molding position;
• hydraulic actuation means for actuating said female half-mold from a lowered position for receiving a dose of plastic material that is sufficient to form a closure, to a raised molding position in which said annular segment of said sleeve enters said bowl to abut against said annular shoulder and to form, together with the plunger, the closure molding chamber in which said closure is molded on said plunger, and again to said lowered position so as to allow removal of said molded closure from said plunger;
• mutually opposite surfaces provided at said plunger and respectively at said jacket to form, in said molding position of the female half-mold, a male half-mold cavity in which the retention element of said tamper-proof ring is molded;
• sleeve actuation means for actuating said sleeve in a downward motion so as to act axially on the molded closure and drag downwards the plunger by a short extent for causing a spacing of said opposite surfaces enough for freeing the molded retention element and remove the molded closure.

In an apparatus for manufacturing screw closures having tamper-proof rings provided with retention elements adapted to engage below a collar of a container to be closed and including a carousel supporting structure that is rotatable about a vertical rotation axis thereof,

• a plurality of pressure molding units including each an upper male half-mold and a lower female half-mold, said male and female half-molds being aligned along a vertical alignment axis that is parallel to said rotation axis of the carousel to form a molding chamber and to further provide a molding pressure in said molding chamber by lifting and respectively forcing the lower female half-mold against the upper male half-mold which is maintained in a stationary position, and wherein each said molding unit further comprises:
• a bowl provided at said female half-mold and forming a cavity which has an annular shoulder;
• a cylindrical jacket provided at said male half-mold, said jacket being fixedly supported at the carousel structure coaxially to said vertical alignment axis;
• a sleeve, which is guided on said jacket and has a lower annular segment that is adapted to engage said bowl;
• a plunger, which is guided in said jacket;
• return elastic means for urging said plunger in a raised molding position;
• hydraulic actuation means for actuating said female half-mold from a lowered position for receiving a dose of plastic material that is sufficient to form a closure, to a raised molding position in which said annular segment of said sleeve enters said bowl to abut against said annular shoulder and to form, together with the plunger, the closure molding chamber in which said closure is molded on said plunger, and again to said lowered position so as to allow removal of said molded closure from said plunger;
• mutually opposite surfaces provided at said plunger and respectively at said jacket to form, in said molding position of the female half-mold, a male half-mold cavity in which the retention element of said tamper-proof ring is molded;
• a spacer provided between a portion of said plunger and a shoulder of said jacket so as to form with said opposite surface, during molding, said male half-mold cavity and to allow the molding pressure to be discharged through said plunger and said jacket onto said carousel structure;
• sleeve actuation means for actuating said sleeve in a downward motion so as to act axially on the molded closure and drag downwards the plunger by a short extent for causing a spacing of said opposite surfaces enough for freeing the molded retention element and remove the molded closure.