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Apparatus for plasticating thermoplastics

Imported: 24 Feb '17 | Published: 06 Jan '04

Timothy W. Womer, Effinger J. Buck, Bernard J. Hudak, Jr.

USPTO - Utility Patents

Abstract

A plasticating screw having a feed section, barrier melting section, reorientation section and metering section disposed sequentially downstream wherein solid material is moved from a trail side of a main flight to a push side of the main flight in the reorientation section. The reorientation of solids is accomplished by discontinuing a barrier flight at a terminal end of said barrier melting section. The main flight decreases its pitch and continues into the reorientation section, which has a longitudinal length at least 360° about the screw axis. A melt channel and solids channel in said barrier melting section merge into a substantially uniform reorientation channel in the reorientation section so that solid plastic material conveyed along the reorientation section moves toward the push side of the main flight. A secondary flight is disposed in the metering section intermediate the main flight, whereby solids conveyed along the metering section are positioned primarily adjacent the push side of the main flight and melt is positioned primarily adjacent the trailing side.

Description

Many other objectives and features of the present invention will be obvious to those of skill in the art upon contemplation of the entire disclosure herein in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

It is to be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the instant invention, for which reference should be made to the claims appended hereto. Other features, objects and advantages of this invention will become clear from the following more detailed description made with reference to the drawings in which:

FIG. 1 shows a side elevational view of a plasticating apparatus with the barrel broken away to expose the screw according to the present invention;

FIG. 2 shows an enlarged view of the screw illustrated in FIG. 1;

FIG. 3 is an enlarged partial view showing the terminal end of the barrier melting section, reorientation section and beginning of the undulating metering section;

FIG. 4 is a side elevational view of FIG. 3 unwrapped in 360° increments placed adjacent to one another showing the termination of the barrier flight, merger of the solids and melt channels into the reorientation channel, decreased pitch of the main flight through the reorientation section, and the start of the secondary flight in the metering section;

FIG. 5 is an illustration of the same as shown in FIG. 4 but with alternative length of the reorientation section; and

FIG. 6 is an illustration of the reorientation of the melt material and solid material as they pass from the mixing section through the reorientation channel to the metering section.

Claims

1. A plasticating apparatus comprising:

2. The apparatus of claim 1, wherein said main flight has a substantially constant diameter throughout said metering section and said barrier flight has a substantially constant diameter throughout said barrier melting section.

3. The apparatus of claim 1, wherein said main flight has a thread width greater than said secondary flight in said metering section.

4. The apparatus of claim 1, wherein said barrier flight has a diameter substantially the same as said secondary flight.

5. The apparatus of claim 4, wherein said barrier flight has a width substantially the same as said secondary flight.

6. The apparatus of claim 5, wherein said metering section is a multi-channel undulating metering section.

7. A plasticating apparatus comprising:

8. The apparatus of claim 7, wherein said solids channel and said melt channel maintain substantially constant widths through said barrier melting section, said solids channel narrows at a position along said screw coinciding with said decreased pitch of the main flight.

9. The apparatus of claim 7, wherein the main helical flight passing into the reorientation section makes a rotation of at least 720° about said screw axis.

10. The apparatus of claim 7, wherein the main helical flight passing into the reorientation section makes a rotation at least 1440° about said screw axis.

11. The apparatus of claim 7, wherein the main helical flight of the reorientation section having a helix angle of approximately 19.5°.

12. The apparatus of claim 11, wherein the helix angle of the main helical flight of the reorientation section and the melting section are substantially equal.

13. A plasticating apparatus comprising:

14. The apparatus of claim 13, wherein the helix angle of the main helical flight of the reorientation section and the melting section are substantially equal.

15. The apparatus of claim 14, wherein said barrier flight has a diameter substantially the same as said secondary flight.

16. The apparatus of claim 15, wherein said barrier flight has a width substantially the same as said secondary flight.