Plasticating apparatus screw having grooves of varying angles and depths

1. A screw for a plasticating apparatus, the screw comprising:

a longitudinal axis, the screw being rotatably supportable in a barrel for rotation about the longitudinal axis, the screw having a core and at least one helical flight extending along a length of the screw, the helical flight defining a helix angle relative to the longitudinal axis and defining a first helical path of a first helix angle less than ninety degrees; the helical flight defining a helical channel; and

a longitudinal portion of the screw having a plurality of advancing grooves with each advancing groove having at least one closed-end, the plurality of advancing grooves being arranged in a noncontinuous helix cut in the screw core in the helical channel of the screw, the plurality of advancing grooves being dimensioned to receive material therein as the material is conveyed through the helical channel;

the longitudinal portion further having a plurality of noncontinuous cross-cut grooves traversing several of the plurality of advancing grooves; and

at least one of:

at least one of the plurality of advancing grooves having an advancing groove depth taper; and

at least one of the plurality of cross-cut grooves having a cross-cut groove depth taper.

2. The screw of claim 1 , wherein the advancing groove depth taper of at least one of the plurality of advancing grooves is different from the advancing groove depth taper of another of the plurality of advancing grooves.

3. The screw of claim 1 , wherein the cross-cut groove depth taper of at least one of the plurality of cross-cut grooves is different from the cross-cut groove depth taper of another of the plurality of cross-cut grooves.

4. The screw of claim 1 , wherein the cross-cut groove depth taper of at least one of the plurality of cross-cut grooves is different from the advancing groove taper of at least one of the plurality of advancing grooves.

5. The screw of claim 1 , wherein at least one of the cross-cut grooves has an increasing depth taper along a longitudinal axis of the cross-cut groove in a direction of flow in the cross-cut groove.

6. The screw of claim 1 , wherein at least one of the cross-cut groove has a decreasing depth taper along a longitudinal axis of the cross-cut groove in a direction of flow in the cross-cut groove.

7. The screw of claim 1 , wherein at least one of the advancing groove has an increasing depth taper along a longitudinal axis of the cross-cut groove in a direction of flow in the advancing groove.

8. The screw of claim 1 , wherein at least one of the advancing groove has a decreasing depth taper along a longitudinal axis of the cross-cut groove in a direction of flow in the advancing groove.

9. A screw for a plasticating apparatus, the screw comprising:

a longitudinal axis, the screw being rotatably supportable in a barrel for rotation about the longitudinal axis, the screw having a core and at least one helical flight extending along a length of the screw, the helical flight defining a helix angle relative to the longitudinal axis and defining a first helical path of a first helix angle less than ninety degrees; the helical flight defining a helical channel; and

a longitudinal portion of the screw having a plurality of advancing grooves with each having at least one closed-end, the plurality of advancing grooves being arranged in a noncontinuous helix cut in the screw core in the helical channel of the screw, the plurality of advancing grooves being dimensioned to receive material therein as the material is conveyed through the helical channel;

the longitudinal portion further having a plurality of noncontinuous cross-cut grooves traversing at least one advancing groove; the plurality of cross-cut grooves comprising:

at least one first cross cut groove having a second helix angle;

at least one second cross-cut groove having a third helix angle; and

wherein the first helix angle, the second helix angle, and the third helix angle are different.

10. The screw of claim 9 further comprising at least one third cross-cut groove having a fourth helix angle that is different from the first helix angle, the second helix angle and the third helix angle.

11. The screw of claim 9 , wherein the at least one cross-cut groove is located at a axially downstream from the at least one second cross-cut groove.

12. A screw for a plasticating apparatus, the screw comprising:

a longitudinal axis, the screw being rotatably supportable in a barrel for rotation about the longitudinal axis, the screw having a core and at least one helical flight extending along a length of the screw, the helical flight having a radially outermost flight surface, the helical flight defining a helix angle relative to the longitudinal axis and defining a first helical path of a first helix angle less than ninety degrees; the helical flight defining a helical channel; and

a longitudinal portion of the screw having a plurality of advancing grooves with each advancing groove having at least one closed-end, the advancing grooves being arranged in a noncontinuous helix cut in the screw core in the helical channel of the screw, the plurality of advancing grooves being dimensioned to receive material therein as the material is conveyed through the helical channel;

the longitudinal portion further having at least one undercut surface located radially inwardly from the radially outermost flight surface and wherein the undercut surface has a depth that varies at least one of:

in a longitudinal direction parallel to the plurality of advancing grooves; and

in a direction traverse to the longitudinal direction.