B - Operations – Transporting – 29 – D
Patent
B - Operations, Transporting
29
D
18/660
B29D 27/00 (1980.01)
Patent
CA 1102066
ABSTRACT OF THE DISCLOSURE 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 mold, and a second cycle which includes the stages of transferring said shaped cellular preform at substant- ially ambient pressure, from the first mold to a second mold, by conveying said preform on said first mold member which retains said preform to said second mold, whereby the shaped preform is free to expand under the conditions of the stage of transferring, wherein said second mold is at a second substantially constant temperature throughout said two cycles, wherein said second substantially constant temperature is lower than said substant- ially constant elevated temperature and wherein the cavity of said second mold has the shape of the ultimate shaped article, cooling and compressing said shaped cellular preform in said second mold, and removing the finished article from said second mold. The method and apparatus are expecially adapted for high production rate of any thermoplastic material articles such as shock absorbing pads for packaging.
265052
Marks & Clerk
Selene Trust
LandOfFree
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