GB1239840A - Apparatus for stretching and smoothing a natural tobacco leaf - Google Patents

Abstract

1,239,840. Smoothing, stretching and stripping tobacco leaves. ARENCO A.B. 28 Aug., 1969 [9 Sept., 1968; 4 Nov., 1968], No. 42871/69. Heading A2C. [Also in Division B8] An apparatus for stretching and smoothing a natural tobacco leaf 3, e.g. prior to stripping, comprises an air permeable leaf supporting conveyer belt 1 and retaining members 8, 32 co-operating therewith to keep a narrow zone 35 of the leaf 3 fixed relative to the belt 1, air flow members 17, 18, 19, 33 disposed above the belt 1 to direct an air stream from the central vein of the leaf 3 towards its edges, and a suction device 7 disposed below the top run of the belt 1 to retain the leaf 3 on the belt 1, the air stream being applied first to smooth and stretch the leaf 3 and then, at a moment preceding or immediately following termination of the air supply, suction is applied by the device 7 to retain the smoothed leaf 3. The apparatus, Fig. 1, comprises three stations A, B, C, the belt 1 being advanced intermittently to transfer the leaf 3 from one station to the next. Within the stations A, C, vacuum boxes 5, 11 underlie the upper run of the belt 1 to provide leaf-retaining suction. The belt 1 is formed from at least transversely stretchable material, such as perforated rubber or woven material, and includes edge holding means 13 to which guide pins 14 are secured, and pins 14 running in grooves 15 of two guide rails 16. The grooves 15 run parallel to each other at a first distance apart through stations A, B, whereas at station C this distance is increased causing stretching of the belt 1 and hence further stretching of the stretched and smoothed leaf 3. Section B, Fig. 4, includes a suction box 17 which carries suction tubes 18, 19, a rubber pressure rail acting as the uppermost retaining member 32, and is mounted to a tie rod 22 for a reciprocation in a vertical direction by a cam driven lever mechanism, the box 17 being raised when conveying the leaf 3 into or out of the station B and lowered to clamp the central vein 35 of the leaf 3 during the smoothing operation. Throttle valves 10, 20, 21 are provided in pipe 9 and tubes 18, 19 to control the suction applied. Openings 33, provided in the top of the box 17, permit ingress of air, flowing in the directions shown by the arrows, when the throttles 20, 21 are opened. Where the central vein 35 is to be cut out, the station C may be dispensed with and a non-stretchable airpermeable belt 1 may be employed, e.g. a perforated steel band. In another embodiment, Figs. 7, 8, the leaf 3 is deposited with its central vein 35 over a line of suction holes 38 formed in a table 37 and is then conveyed on to a narrow conveyer belt 46 overlaid by two narrow pressure belts 47, 48 that clamp the central vein 35. Compressed air is then directed through openings 55 in tables 46, 51 to smooth and stretch the leaf 3. The leaf 3 is then transported on two suction-backed air-permeable conveyers 56, 57 past circular knives 61, 62 and a co-operating feeder wheel 63 to cut out the central vein 35.