| US 7,476,096 B2 | ||
| Screw extruder | ||
| Takuzo Iwata, Kobe (Japan); and Isao Ohiwa, Kobe (Japan) | ||
| Assigned to Sumitomo Rubber Industries Ltd., Kobe-shi (Japan) | ||
| Filed on Feb. 28, 2006, as Appl. No. 11/362,707. | ||
| Claims priority of application No. 2005-108917 (JP), filed on Apr. 05, 2005. | ||
| Prior Publication US 2006/0222727 A1, Oct. 05, 2006 | ||
| Int. Cl. B29C 47/62 (2006.01); B29C 47/64 (2006.01) | ||
| U.S. Cl. 425—204 [366/80; 366/81; 366/90; 425/208] | 5 Claims |
| 1. A screw extruder comprising an extruder body (4) with a bore (4H), and a screw (5) rotatably disposed in the bore (4H),
the screw (5) comprising a screw shaft (7), and two screw flights (8 and 9) disposed in the form of a double helix, wherein
one of said two screw flights (9) forms a main passage (G) between the helical portions of the one screw flight (9), the main passage (G) extending helically around the screw shaft (7),
the other of said two screw flights (8) is provided with large interruptions (11), whereby the other screw flight (8) is divided by the interruptions (11) and screw flight pieces (12) are formed between the interruptions (11),
when the helical main passage (G) is unrolled into a straight form, the one screw flight (9) extends in a straight line, and the screw flight pieces (12) of the other screw flight (8) are arranged in a straight line,
within each of the interruptions (11), two additional flight pieces (13A and 13B) which are substantially parallel with each other are disposed, and
each of the two additional flight pieces (13A and 13B) is spaced apart from each of the two adjacent screw flight pieces (12) by a positive distance (WJ1, WJ2, WJ3, WJ4) in the longitudinal direction of the main passage (G), wherein
the distance (WJ1) between one additional flight piece (13A) and one of the two adjacent flight pieces (12) is smaller than the distance (WJ2) between the other additional flight piece (13B) and the same flight piece (12); and
the distance (WJ3) between the additional one flight piece (13A) and the other of the two adjacent flight pieces (12) is larger than the distance (WJ4) between the other additional flight piece (13B) and the same flight piece (12), and
said extruder body (4) is provided with mixing/kneading pins (15) protruding into the bore (4H), wherein
paths (17) for the mixing/kneading pins (15) are provided between the additional flight pieces (13A and 13B) and the screw flight pieces (12) so that each of the interruptions (11) forms two of the paths (17) on the upstream side and downstream side of the additional flight pieces (13A and 13B); and
the one screw flight (9)is provided with clearances (16) to form the paths (17) for the mixing/kneading pins (15), wherein the clearances (16) have a shape slightly larger than that of the respective pins (15) enabling the passing of the mixing/kneading pins (15) so that each of the clearances (16) forms one of the paths (17), and the one screw flight (9) has no interruption except for the clearances (16).
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