Apparatus for forming seal liners of thermoplastic material within closure cap shells

An apparatus for forming seal liners of thermoplastic foaming material within closure cap shells comprising:

• a plurality of movable dies each having an inner die and an annular outer die,
• each of said inner and outer dies being movable up and down,
• said inner die having a cylindrical lower end portion which is slidably disposed within said annular outer die and has a lower end wall for radially spreading a measured amount of fused thermoplastic foaming material placed on a horizontal wall of an interior surface of a cap shell, as said inner die takes its lowermost position,
• said annular outer die having a cylindrical lower end portion whose external diameter is substantially equal to an internal diameter of said cap shell, so that a cylindrical external circumferential wall of said cylindrical lower end portion is in contact with a substantially upwardly extending wall of said interior surface of the cap shell when said outer die is in its lowermost position,
• said inner die being so arranged as to still continue its downward movement to its lowermost position after said outer die has taken its lowermost position,
• means for restricting downward movement of said outer die so as to prevent its lower end wall from contacting said horizontal wall of said cap shell thereby to provide a certain constant clearance between said lower end wall of the outere die and said horizontal wall of said cap shell,
• an annular recess formed in a lower end circumference of said inner die,
• said annular recess being communicated with said clearance so that an annular foaming chamber of a constant capacity, for forming a thick annular pad portion of said seal liner, is formed beneath said lower end wall of the outer die when both of said outer and inner dies are in their lowermost positions,
• means for restricting upward movement of said outer die when said thermoplastic foaming material is forcibly pushed into said foaming chamber,
• a plurality of gas discharging grooves formed in a relatively slidable area existing between a cylindrical external surface of said cylindrical lower end portion of said inner die and a cylindrical internal surface of said cylindrical lower end portion of said outer die, said area being located above said annular foaming chamber and inwardly spaced apart from said upwardly extending wall of said interior surface of said cap shell, and
• said foaming chamber being communicated with the atmosphere through said gas discharging grooves.