Before various articles can be made from tobacco leaves, it is necessary to clean the leaves to remove dust and other contaminants from them. Prior to final processing tobacco leaves are subjected to wide variety of contamination from insects, dust, sand, and the like. In addition, the leaves of flue-cured tobacco are tied together and looped onto tobacco sticks with cotton string, which supports the leaves in the curing barns during the curing process. Frequently these cotton strings or portions of the strings become mixed in with the leaves during the processing operations.
Tobacco scraps and some tobacco leaves also are packed in burlap sacks for delivery from the growers to the processing plants; and when tobacco scraps and leaves are emptied from such burlap bags, burlap fibers become mixed in with the leaves and scraps of tobacco. A variety of other foreign matter also frequently is present.
Because of the presence of foreign matter in the tobacco leaves and tobacco scraps, the tobacco in a processing plant is placed on tables and moved on conveyors past operators who manually pick out the largest and most obvious contaminants, such as string segments, feathers, straw, and the like. It is difficult, however, if not impossible for such operating personnel to remove fine particles such as burlap bag fibers and cotton string fibers and similar contaminants from the tobacco; so that these smaller contaminants are overlooked.
To remove contaminants such as dust and insect eggs from the tobacco, tobacco cleaning machines have been developed using rotating brushes for engaging the tobacco leaves as they moves beneath the brushes on a conveyor belt. Two such tobacco cleaning machines are disclosed in the Patents to Spierer U.S. Pat. No. 973,228 and Fonseca U.S. Pat. No. 1,831,953. The devices of both of these patents are similar to one another; and both of them employ rotating brushes to engage the surfaces of the leaves to remove dust, insects, larva, eggs and other surface impurities from the tobacco. Rotating brush cleaners in conjunction with shakers, air blowers and other apparatus continue to be used to prepare tobacco leaves for processing.
A rotating brush machine for cleaning tobacco scrap to separate the tobacco scrap from dirt and larger contaminants is disclosed in the Patent to Skinner U.S. Pat. No. 2,942,607. The machine of the Skinner Patent employs a plurality of rotating brushes for moving the tobacco from a hopper up a series of inclined planes to separate the desired tobacco scraps from different sizes of contaminants in various stages of operation.
It has been found, however, that even when rotating brush cleaning machines are used to remove foreign matter from tobacco leaves, as the leaves move from conveyor to conveyor throughout the processing plant, the cleaned tobacco still includes fine particles of lint, string and the like, which ultimately become incorporated into the products made from the tobacco.
Accordingly, it is desirable to provide a device which can be used to more effectivly remove particles of lint, burlap bag fibers, string and other contaminants from tobacco leaves prior to the processing of such leaves into various products. It further is desirable for such a device to be efficient in operation and inexpensive to manufacture, install and operate.