GB1327995A - Screw mixers - Google Patents

Abstract

1327995 Screw mixers; de-gassing P PONCET 26 July 1971 [7 Aug 1970] 34905/71 Headings B1C and B1M Mixing. A screw mixer has at least one pair (as shown, two pairs) of conical screws as 1, 2 and 3, 4, the screws of each pair intermeshing and rotating in the same sense, the cores of each screw being of the same conical as the thread, and the pairs rotating in opposed senses. The apparatus shown has an inlet 7, auxiliary inlets 8, 9 and an outlet 10, Fig. 2, shows the upper pair 1, 2 which has a feeding section 5, 6 with thin flat screw threads decreasing in pitch from left to right. Then follow a cylindrical mixing section, a conical section and a reverse pitch cylindrical section all with trapezoidal threads. Screws 1, 2 are co-rotated by a sprocket chain 15 and geared to the lower pair (which is of the same construction without the feeding section, see Fig. 3, not shown) at 16. The mixing sections may have narrow threads and wide grooves (see Figs. 8 and 9, not shown) permitting one of them to be given an additional motion of axial reciprocation (see Fig. 7, not shown) by an eccentric in order to wipe the bottoms of the grooves or the flanks of the threads; by suitable choice of the ratio of rotational speeds of the eccentric and screw wear can be spread round the screw. De-gassing: The screws may be enclosed in a housing under reduced pressure; if the second pair is rotated faster or is of larger diameter than the first, voids will be created in the material, promoting de-gassing.