Method and apparatus for molding expanded plastic material articles

Abstract From the Canadian patent

According to the invention a method for forming shaped articles from pre-expanded thermoplastic beads in, two cycles, comprises a first cycle which includes the stages of introducing said beads into a mold cavity of a first mold to fill said mold cavity, wherein said first mold comprises two members a male member and a female member, and wherein said first mold is maintained at a substantially constant elevated temperature throughout said two cycles, injecting steam into said first mold to cause the beads to expand, partially melt agglomerate and, form a shaped cellular preform disengaging said two members of, the first mold whereby said preform is retained by one mold member of said first …