GB737165A - Apparatus for threshing and winnowing tobacco leaves - Google Patents

Abstract

737,165. Separating solid materials; centrifugal separators. AMERICAN MACHINE DEVELOPMENT CORPORATION. June 18, 1951, No. 14422/51. Addition to 722,183. Classes 23 and 117. [Also in Group VI] Tobacco passing from a ripper 24 enters an air stream moving upwards with such a velocity that clean stems fall through an opening 40 whilst stems with attached blade portions are carried upwardly towards a deflecting wall 44 which returns them to the ripper 24 for retreatment therein, blade portions without stems being carried by the air stream up a passage 54 into a separating chamber 58. In one form, the ripper comprises a revolving drum 26 having combs 24 coacting with rakes 28, 42, 48 and with a concave 30 having circumferential zig-zag slots through which the tobacco is forced either directly into the air stream or onto a moving belt 32 delivering it thereto. The tobacco is delivered to the ripper by hand or conveyer through a rotary gate valve 18 whose compartment walls 16 have flexible seals 17 which, with a flexible seal 52 acting on the belt 32, prevent undesired air entry. In another form, Fig. 4 (not shown), the concave 30 and rakes 28, 42 are replaced by a concave grid which curves in towards the drum surface spirally in the direction of motion so that as the drum rotates, the drum combs pass into the grid spaces and between diamond-shaped cutting members so spaced along the grid teeth that those on one tooth alternate circumferentially with those on the next. In the separating chamber 58, the blade portions fall and are discharged through a gate valve 60 similar to the valve 18, settled-out sand filters through a perforated wall 66 into a receptacle 70, and the air passes through a screen 72 which retains lint, string and feathers. The air then passes through an external conduit 78 on each side of the apparatus to a chamber 80, and thence via cyclone separators 82 to openings 102 leading by a duct 104 on each side of the apparatus to the suction entries of a blower 105 producing the air stream, dust from the separators 82 being discharged to a receptacle 92. The rate of air flow through the apparatus for any given tobacco type or humidity is determined conjointly by valves 106 in the ducts 104 and by a valve 108 manually adjustable through a worm drive to allow controlled leakage from the atmosphere into the chamber 80 at a rate which ensures a supply of air to the separators 82 sufficient to render them self-cleaning. An adjustable gate 57 allows additional air to enter the passage 54 in greater quantity at the centre thereof than at the sides. The valves 106 may be dispensed with if the blower 105 has a variable speed drive. Specification 737,223, [Group VI], is referred to.