Extruder injection apparatus and method

DETAILED DESCRIPTION This invention relates to a plasticating apparatus including a rotating screw having a helical flight disposed within and cooperating with the inner wall of a heated barrel provided with inlet and outlet openings.
Particles of resinous material are introduced through said inlet opening to a helical valley extending along said flight and said particles are plasticated by said screw and advanced towards said outward opening.
A barrier extends along the helical valley between facing portions of said helical flight to divide said helical valley into coextensive helical valley sections.
The barrier extends in a non-parallel path having an alternating direction with respect to the helical flight so that the pitch of the barrier is alternately greater than and less than the pitch of the helical flight, without the barrier intersecting the helical flight.
The height of the barrier is less than the height of the flight so that the resinous material being worked overflows the barrier due to changes in width of the helical valley sections.
Successive sections of the barrier can be straight with a bending angle being defined between the successive sections to provide a zigzag path.
If desired, the path of the barrier can be wavy or serpentine.
The wavy path can be essentially sinusoidal, if desired.
No matter what specific path is defined by the barrier, the alternating path of the barrier causes the barrier to successively approach and withdraw from the flight in the direction of resin flow without intersecting the flight.
Coextensive helical valley sections are defined between the central barrier and the facing portions of the helical flight on opposite sides of the barrier.
Because the direction or path of the barrier is non-uniform with respect to the direction or path of the helical flight, the widths of the side by side helical valley sections continuously change in a manner such that as the helical path on one side of the barrier narrows the helical path on the other side of the barrier widens by a corresponding amount, and vice versa