Patent ID: 8113810

Claim:
An extrusion die assembly comprising: a hollow extrusion head including a head inner surface, a central passage inlet opening, a forming section having a die opening, a first receiving space that extends from said central passage inlet opening to said forming section, a first lateral passage inlet opening, and a second receiving space having one end connected to said first lateral passage inlet opening and the other end connected fluidly to said first receiving space midway between said central passage inlet opening and said die opening; a first flow-dividing core disposed within said first receiving space, said first flow-dividing core being hollow and having a central passage connected to said central passage inlet opening and extending to said forming section, and a first grooved outer surface that is disposed upstream of said forming section and that has at least one groove which cooperates with said head inner surface to define at least one first accumulating passage; a first annular passage formed in said forming section and around said first flow-dividing core and said central passage, said first annular passage being connected to said first accumulating passage and merging with said central passage in said die opening; and a first flow-dividing block disposed within said second receiving space and dividing said second receiving space into two first lateral passages which are connected to said first lateral passage inlet opening, said first flow-dividing core and said head inner surface cooperatively defining a pair of said first accumulating passages which are respectively connected to said first lateral passages; wherein said second receiving space has a block-retaining section proximate to said first accumulating passages, and a tapered section proximate to said first lateral passage inlet opening, said first flow-dividing block including a first block base portion retained in said block-retaining section, and a main wedge-shaped portion received in said tapered section and tapered from said first block base portion toward said first lateral passage inlet opening; and wherein said first flow-dividing block further includes two auxiliary wedge-shaped portions projecting respectively from two opposite sides of said main wedge-shaped portion and tapering from said first block base portion toward said first lateral passage inlet opening.