Abstract:
A feed device for a linear airflow separator that eliminates the use of a winnower in the separation of tobacco products. The feed device includes an adjustable angle baffle deflector in combination with an air knife. The air-fed adjustable angle baffle deflector feeds with non-product contact and as a result does not lead to mechanical degradation of the treated material. The air knife is fed with air from a high pressure blower having a variable frequency drive. The feed device treats the product with air only, thereby eliminating mechanical contact with the product and resulting in higher separation yields and higher operating efficiency than conventional recirculating pneumatic separators.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to the separation of materials of different characteristics from an airstream of conveyed material, and specifically to a feed device for a linear airflow separator including an air nozzle and an adjustable angle baffle deflector that in tandem may be adjusted in angle to improve the quality and method of feeding materials to a linear airflow separator. 
       BACKGROUND OF THE INVENTION 
       [0002]    Recirculating pneumatic separators are commonly used in the separation of tobacco products, such as the separation of threshed tobacco leaves from the heavier tobacco parts such as stems. Conventional recirculating pneumatic separators typically include a winnower as a feed device that imparts a substantial velocity to the particles of material to be fed to the separator. The winnower consists of a rotary impeller with a plurality of vanes rotating at extremely high speeds, typically 500 to 800 rpms. The rapidly rotating vanes physically contact the particles of material to be separated and thereby impart a substantial velocity to the material. 
         [0003]    Unfortunately, several negative consequences result from operating a winnower at these high rates of rotation. The direct physical contact of the high speed vanes with the product leads to substantial degradation of the product. The yield of a conventional recirculating pneumatic separator is thus negatively affected by the product degradation. Furthermore, in the processing of tobacco, it is absolutely critical to avoid introducing any foreign matter into the tobacco. Winnowers, running at a high revolution rate, break down frequently and lose portions of their vanes into the tobacco product. Introducing the broken portions of the winnower into the tobacco processing stream is a critical and unacceptable problem in the processing of tobacco. 
         [0004]    What is needed is an improved method of separating threshed tobacco leaves from the heavier tobacco parts. The improved separation device and method should preferably reduce the amount of product degradation thereby having a positive effect on separator yield. The method should also eliminate the possibility of contaminating the tobacco product with broken portions of the separator machinery. These improvements are realized by the feed device of the present invention, which eliminates the winnower as a piece of machinery in the separation of tobacco products. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The invention is a feed device for a linear airflow separator that eliminates the use of a winnower in the separation of tobacco products. The feed device includes an adjustable angle baffle deflector in combination with an air knife. The air-fed adjustable angle baffle deflector is designed to feed with non-product contact and therefore does not degrade the treated material. Air is fed to the air knife by a high pressure blower controlled by a variable frequency drive. As compared to conventional separators, the feed device of the present invention eliminates mechanical contact with the product being fed and as a result leads to longer operational life and less frequent breakdowns of equipment. The air feed reduces or actually eliminates the frequent maintenance that is required by conventional feed devices using a winnower to mechanically feed a product. 
       OBJECTS AND ADVANTAGES OF THE INVENTION 
       [0006]    The feed device of the present invention exhibits several advantages over conventional feed devices for recirculating pneumatic separators, including:
       1) The feed device eliminates the use of a winnower for imparting velocity to the particles of material to be separated, which eliminates product damage caused by the physical contact of the rapidly rotating vanes of the winnower with the product.   2) As a result of causing less damage to the product, the feed device has a direct positive effect on yields.   3) The feed device is designed to feed with non-product contact, which leads to substantially less degradation of product.       
 
         [0010]    These and other objects and advantages of the present invention will be better understood by reading the following description along with reference to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0011]    Reference is made herein to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
           [0012]      FIG. 1  is a schematic diagram of the preferred embodiment of a feed device for a linear airflow separator, in accordance with embodiments of the invention. 
           [0013]      FIG. 2  is a side view of an air-fed adjustable angle baffle deflector that forms a portion of the feed device of  FIG. 1 . 
           [0014]      FIG. 3  is a sectional view of the air-fed adjustable angle baffle deflector including the air knife gap. 
           [0015]      FIG. 4  is a schematic diagram illustrating the degrees of rotation of the air-fed adjustable angle baffle deflector. 
           [0016]      FIG. 5  is a top isometric view of the air-fed adjustable angle baffle deflector. 
           [0017]      FIG. 6  is a top view of the air-fed adjustable angle baffle deflector. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    With reference to  FIG. 1 , there is shown a preferred embodiment of a feed device  20  for a linear airflow separator in accordance with the present invention, of which a portion of the linear airflow separator  21  is shown in dashed lines in the figure. The a feed device  20  includes an air-fed adjustable angle baffle deflector  22  that includes an air knife  24  and a deflector baffle  26  fixed in relation to one another. The air knife  24  and deflector baffle  26  rotate in tandem around a pivot  28 . A blower  30  supplies pressurized air to the air knife  24  through flexible hose  32 . A transport mechanism in the form of a conveyor  34  with a driven belt  36  delivers clumped tobacco  38  around roll  40 , which product falls toward deflector baffle  26 . The clumped tobacco product includes tobacco materials of various densities, such as stems and threshed leaves. A fixed baffle  42  extends substantially from the air knife  24  to the lower surface of belt  36  and prevents tobacco from adhering to and the underside of belt  36  as it travels around roll  40 . Air is supplied in the direction of arrow  44  to the air knife  24 . Tobacco travels along conveyor  34  and is dropped or free falls into the air-fed adjustable angle baffle deflector  22 . The air-fed adjustable angle baffle deflector  22  then thrusts the tobacco (or other product) in the direction of arrow  46 . The trajectory of the product/airflow is adjustable via rotation of the air-fed adjustable angle baffle deflector  22  around pivot  28 . The air knife  24  and the deflector baffle  26  rotate as a unit around pivot  28 , that is to say the angle between the two is fixed. 
         [0019]    Although a conveyor is shown as the transport mechanism in  FIG. 1 , other transport mechanisms could also be used to deliver tobacco to the air-fed adjustable angle baffle deflector  22 , such as a vibrating conveyor, gravity-fed chute, vibrating chute, separate belt conveyor, screw drive, or a hopper and valve arrangement. It should also be understood that the feed device  20  can be used for separation of products other than tobacco. The purpose of the feed device is to improve the method of feeding tobacco into a classifier, especially in reducing the mechanical damage to the tobacco and in improving the yield of the separation process. Since the feed device feeds product with air, there is no mechanical contact with the tobacco, and this leads to less degradation of material and higher separation efficiencies and yields. 
         [0020]    Referring to  FIGS. 2 and 3 , according to the preferred embodiment, an air knife  24  and a deflector baffle  26  are fixed in relation to one another to form an air-fed adjustable angle baffle deflector  22 . The air knife  24  includes a nozzle  48  that has two tips  50  of hardened metal. As shown in  FIG. 3 , the tips  50  form an air knife gap  52  that is set to obtain a preferred air stream exiting the gap. The air knife gap  52 , denoted by distance D1 in  FIG. 3 , is preferably set at 0.040 to 0.045 inch. The tips  50  enable adjustment of the air knife gap  52 . 
         [0021]    As shown in  FIG. 3 , the air knife gap  52  is aligned along the centerline  54  of the air knife gap  52  and the ramp portion  56  of deflector baffle  26  is aligned along plane  58 . The air knife  24  and the deflector baffle  26  are maintained in a fixed relationship to one another and rotate as a unit, or in tandem, to form the air-fed adjustable angle baffle deflector  22 . The air knife  24  and the deflector baffle  26  are rotated as a unit around pivot  28  in order to obtain the desired trajectory and distance of the thrust tobacco. The air knife  24  is preferably positioned at a distance above and at an angle with respect to the ramp portion  56  of the deflector baffle  26 . The distance above the ramp portion  56  of the deflector baffle  26 , as measured from the centerline  54  of the air knife gap  52  to the ramp portion  56  of the deflector baffle  26  as denoted by distance D2 in  FIG. 3 , is preferably from 0.06 to 0.08 inch. The angle between the air knife  24  and the deflector baffle  26 , denoted by θ in  FIG. 3 , is preferably between 3 and 7 degrees. Most preferably the angle is 5 degrees. The angle between the air knife  24  and the deflector baffle  26  is critical to keep the deflector baffle  26  clear and to properly disperse and thrust the tobacco in order to properly feed the material to a classifier or similar piece of equipment for further processing of the tobacco. Preferably, the air knife is positioned 0.06-0.08 inch above the surface of the deflector and at an angle of 5 degrees with respect to the surface of the deflector baffle  26 . In operation, air is provided to the air knife  24  from the blower  30  thereby causing the air to impinge at an oblique angle (see angle θ in  FIG. 3 ) on the ramp portion  56  of the deflector baffle  26 . 
         [0022]    With reference to  FIG. 2 , fixed baffle  42  includes a brush  59  extending upward therefrom and a lower leg  60  extending toward the air knife  24 . The brush  59  clears driven belt  36  of any tobacco material adhered to the belt, and sends it back toward the air-fed adjustable angle baffle deflector  22 . Lower leg  60  of fixed baffle  42  is positioned close to the air knife  24  and prevents tobacco material from traveling toward the air knife. 
         [0023]    Referring to  FIG. 4 , the air-fed adjustable angle baffle deflector  22  is rotated to a desired position in order to obtain the proper trajectory of the tobacco entering the classifier. This angle is adjusted to compensate for various factors, such as the rate of tobacco being processed and the fraction of high and low density portions. Pivot lever  62 , which is attached to pivot  28 , and turnbuckle  64  provides a means of rotating the air-fed adjustable angle baffle deflector  22 . Rotation of the air-fed adjustable angle baffle deflector  22  is effected by adjusting the turnbuckle  64  manually, which moves pivot lever  62  and in turn rotates the air-fed adjustable angle baffle deflector  22  around pivot  28 . The air-fed adjustable angle baffle deflector  22  is normally aligned along neutral plane  66 . Most preferably, the air-fed adjustable angle baffle deflector  22  is adapted to rotate up to 30 degrees (+30°) above or up to 15 degrees below (−15°) the neutral plane  66 , or a total of 45 degrees of rotation. The extent of rotation is shown by plane  68  for the upper extent and plane  70  for the lower extent of rotation. 
         [0024]    With reference to  FIGS. 5 and 6 , the air-fed adjustable angle baffle deflector  22  portion of the feed device is constructed in various machine widths, denoted by dimension W1 in  FIG. 5 , in order to size the separator for the volume and rate of tobacco that will be treated. The separator  20  and air-fed adjustable angle baffle deflector  22  can be constructed in various lengths, ranging from 36 to 144 inches, in order to accommodate all widths of tobacco separators. 
         [0025]    As shown in  FIG. 6 , the length of the ramp portion  56  of the baffle deflector  26  is critical to the operation of the feed device in order to achieve proper separation of the tobacco. Most preferably, the length of the ramp portion  56  is from 15.15 to 16.5 inches. The blower  30  (see  FIG. 1 ) preferably provides a pressure of 17 psia at a frequency of 60 Hz. The rotational speed of the blower is preferably from 3,600 to 22,000 rpm. Most preferably, the rotational speed of the blower is 3,600 rpm. 
         [0026]    Having thus described the invention with reference to a preferred embodiment, it is to be understood that the invention is not so limited by the description herein but is defined as follows by the appended claims. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments herein were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention.