Mold having vent passageways to obviate trimming of flash

Abstract

A mold for producing foamed articles includes an upper mold and a lower mold which define a mold cavity. A vent is provided in communication with the mold cavity and has a vent passageway with an entrance and an exit. Structure is also provided for sealingly engaging the upper mold with the lower mold to cause, in cooperation with the predetermined size and shape of the vent passageway, liquid foam polymeric composition expanding inside the mold cavity to enter the vent entrance but to not exit from the vent exit to cause at least partial curing of the foam composition within the vent passageway. Preferably, the vent may be ribbon-shaped so that a ribbon of foamed composition adheres to the foamed article and may be folded flat against the article thus avoiding the labor step of trimming the flash from the product. Additionally, .[.or alternatively,.]. the vent may include a vent passageway with an obstruction disposed therein to provide one or more openings between the outer surface of the obstruction and the inner surface of the vent passageway. The foam composition in these openings may be expelled by driving the obstruction axially within the passageway. Again, the labor step of hand trimming the flash is avoided.

What is claimed is: 
     
       1. A mold for producing foamed articles, comprising: an upper mold and a lower mold which define a mold cavity;   at least one vent disposed in said upper mold and in communication with the mold cavity, said vent having a vent passageway with an entrance and an exit;   an obstruction disposed in said vent passageway, said obstruction and said vent passageway combining to form at least one opening having an elongated shape which allows movement of a liquid foam polymeric composition to pass from the mold cavity into the vent passageway entrance but prevents the liquid foam polymeric composition from exiting the vent passageway exit to cause at least partial curing of the liquid foam polymeric composition in the at least one opening between the vent passageway and the obstruction; .[.and.].   driving means for driving the obstruction axially within said vent passageway to expel the at least partially cured liquid foam polymeric composition from said at least one opening .Iadd.said lower mold having a first plurality of vents disposed along one side of the lower mold at a part line between the upper and lower molds;   said lower mold having a second plurality of vents disposed on a second side of the lower mold which is adjacent the first side, said second plurality of vents being disposed on the part line between the upper and lower mold; and   each of said first and second pluralities of vents having a vent passageway with an entrance and an exit, each said vent passageway being sized and dimensioned to cause liquid foam polymeric composition expanding inside the mold cavity to enter into each said vent passageway entrance but to not exit from each said vent passageway exit so that at least partial curing of the liquid foam polymeric composition occurs within each said vent passageway so that the at least partially cured liquid foam polymeric composition in each said vent passageway does not separate from the mold foam article when the upper mold and lower mold are separated so as to produce the plurality of appendages on the sides of the foamed article. .Iaddend.   
     
     
       2. A mold according to claim 1, wherein said obstruction has an octagonal cross-section so that eight openings are disposed between said obstruction and said vent passageway. 
     
     
       3. A mold according to claim 1, wherein said driving means comprises a pneumatic piston. 
     
     
       4. A mold according to claim 1, wherein said vent passageway comprises a plastic material. 
     
     
       5. A mold according to claim 4, wherein said plastic material comprises an acetal resin guide bushing. 
     
     
       6. A mold according to claim 1, further comprising means, coupled to said obstruction, for sweeping an interior of said vent passageway to expel liquid foam polymeric composition adhering to the interior of said vent passageway when said driving means drives said obstruction. 
     
     
       7. A mold according to claim 1, further comprising a plurality of corresponding vents, obstructions, and driving means. 
     
     
       8. A mold for producing foamed articles, comprising: an upper mold and a lower mold which define a mold cavity;   at least one first vent disposed in said upper mold and in communication with the mold cavity, said first vent having a vent passageway with an entrance and an exit;   an obstruction disposed in said first vent passageway, said obstruction and said first vent passageway combining to form at least one opening having an elongated shape which allows movement of a liquid foam polymeric composition expanding in the mold cavity to pass from the mold cavity into the first vent passageway entrance but prevents the liquid foam polymeric composition from exiting the first vent passageway exit to cause at least partial curing of the liquid foam polymeric composition in the at least one opening between the first vent passageway and the obstruction;   driving means for driving the obstruction axially within said first vent passageway to expel the at least partially cured liquid foamed polymeric composition from said at least one opening; .Iadd.and .Iaddend.   at least one second vent disposed on a part line between said upper mold and said lower mold and in communication with the mold cavity, the second vent having a second vent passageway with an entrance and an exit, the second vent passageway being elongated with a width substantially greater than a thickness orthogonal to the width to cause the liquid foam polymeric composition expanding inside the mold cavity to enter the second vent passageway entrance but to not exit from the second vent passageway exit to cause at least partial curing of the liquid foam polymeric composition within the second vent passageway.   
     
     
       9. A mold according to claim 8, wherein said second vent passageway has a thickness orthogonal to the part line of from about 0.002 inches to about 0.030 inches. 
     
     
       10. A mold according to claim 8, wherein the second vent passageway has a thickness orthogonal to the part line of from about 0.005 inches to about 0.020 inches. 
     
     
       11. A mold according to claim 8, wherein said second vent passageway has a substantially rectangular cross-section with a width parallel to the part line of substantially 6.0 inches and a thickness orthogonal to the part line of from about 0.005 inches to about 0.020 inches. 
     
     
       12. A mold according to claim 8, wherein said driving means comprises a pneumatic piston. 
     
     
       13. A mold according to claim 8, wherein said first vent passageway comprises a plastic material. 
     
     
       14. A mold according to claim 13, wherein said plastic material comprises an acetal resin guide bushing. 
     
     
       15. A mold according to claim 8, further comprising means, coupled to said obstruction, for sweeping an interior of said first vent passageway to expel liquid foam polymeric composition adhering to the interior of the second vent passageway when said driving means drives said obstruction. 
     
     
       16. A mold according to claim 8, further comprising a plurality of second vents disposed on the part line between said upper mold and said lower mold, and a plurality of first vents disposed in said upper mold.