Abstract:
A product-spreading hood assembly ( 10 ) for use with a die unit ( 128 ) includes a deflector ( 14 ) having wall structure defining a product inlet opening ( 90 ) and a product outlet opening ( 92 ); the deflector ( 14 ) is preferably generally frustoconical in shape and is supported by a housing ( 12 ). An optional air delivery assembly ( 16 ) allows air currents to be directed from the area of the inlet ( 90 ) towards outlet ( 92 ) to facilitate separation of discrete products. Advantageously, the air currents are delivered in a circumferential fashion about the die unit ( 128 ). Use of the hood assembly ( 10 ) serves to separate high moisture or “sticky” extrudates, thereby preventing agglomeration thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a division of identically titled application Ser. No. 13/626,683, filed Sep. 25, 2012, is now issued as U.S. Pat No. 9,221,627, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is broadly concerned with a product-spreading hood assembly operable for use with an outlet die unit in order to separate discrete products issuing from the die to prevent agglomeration of the products. More particularly, the invention is concerned with such apparatus, and corresponding methods, wherein a substantially frustoconical deflector is disposed about the die unit to deliver the extrudate to a downstream dryer or other processing device in a separated condition. The invention is particularly useful in the production of high moisture or otherwise “sticky” extrudates normally having a tendency to agglomerate. 
     2. Description of the Prior Art 
     Extrusion cooking systems have long been used for the preparation of human foods and animal feed products. Broadly speaking, such extrusion systems include an elongated extruder barrel with one or more elongated, axially rotatable, helically flighted extruder screws within the barrel, together with a downstream restricted orifice extrusion die. In typical processing, the feed ingredients are fed into and through the extruder barrel where they are subjected to increasing levels of heat, pressure and shear in order to at least partially cook the ingredients and form an extrudate. This extrudate may be cut or otherwise subdivided at or downstream of the die. Thereafter, the subdivided extrudate is often subjected to post-extrusion treatments such as surface application of fats and drying. 
     For many types of conventional extrudates, these extrusion systems operate smoothly. However, in certain cases, the food or feed formulas have a tendency to produce very sticky products. In such instances, the extrudates may tend to agglomerate adjacent the die or as the extrudates fall onto a conveyor or other take-away equipment. For example, the high moisture products described in co-pending application Ser. No. 13/626,644 now is abandoned entitled “Production of Engineered Feed or Food Ingredients by Extrusion,” may tend to excessively agglomerate. 
     There is accordingly a need in the art for improved apparatus associated with a die unit in order to maintain the cut extrudate issuing from the die unit in a separated condition until such time as the extrudates are sufficiently dried or otherwise processed to over come the tendency to agglomerate. 
     SUMMARY OF THE INVENTION 
     The problems outlined above are largely, if not entirely, ameliorated by provision of a specialized product-spreading hood assembly operable to be placed adjacent an outlet die unit in order to separate discrete products issuing from the die unit. The hood assembly comprises a deflector having wall structure defining a product inlet opening and a product outlet opening, with a product-receiving area between the inlet and outlet openings. Preferably, the deflector wall structure is generally frustoconical in shape with a relatively small product inlet opening located in generally circumscribing relationship about the die unit, and a relatively large product outlet opening spaced from the inlet opening. In addition, a housing disposed about and supporting the deflector and extending along the length of the deflector and beyond the product outlet opening to present a product confinement zone, the zone having an open bottom so that products from the outlet opening will gravitate from the housing in a substantially separated condition. 
     In certain instances, operation of the hood assembly is facilitated by means of an air delivery assembly operable to direct air currents from a point proximal to the product inlet opening and into the product-receiving area in a direction towards the outlet opening, with the air currents operable to substantially maintain the discrete products in a separated condition as the products pass through the outlet opening and into the area. Preferably, the air delivery assembly comprises a plenum extending at least partially about the portion of the deflector wall structure defining the product inlet opening, with an airway communicating the plenum so that the air currents are directed into the plenum and pass through the airway into the product-receiving area. 
     An external housing is provided to support the deflector, with the housing extending along the length of the deflector and beyond to define an open-bottom product confinement zone downstream of the outlet end of the deflector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of a preferred product delivery hood assembly in accordance with the invention; 
         FIG. 2  is a side elevational view of the hood assembly; 
         FIG. 3  is a perspective view of the hood assembly, viewing the rear end thereof opposite that illustrated in  FIG. 1 ; 
         FIG. 4  is a front perspective view similar to that of  FIG. 1 , but illustrating the hood in its opened position permitting access to the extruder die and knife assembly; 
         FIG. 5  is a side vertical sectional view of the hood assembly, illustrating the internal components of the assembly; 
         FIG. 5A  is an enlarged, fragmentary view illustrating the airflow path within the hood assembly; 
         FIG. 6  is a vertical sectional view taken along line  6 - 6  of  FIG. 2 ; and 
         FIG. 7  is an enlarged, fragmentary view partially taken along line  6 - 6  of  FIG. 2 , and further illustrating the details of construction of the hood assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, a product-spreading dispersal hood assembly  10  is illustrated in  FIGS. 1-6 , and broadly includes an outer housing  12  supporting inner, generally frustoconical deflector  14 , and an air delivery assembly  16 . The hood assembly  10  is designed for use with devices such as extruders or pellet mills, which are equipped with a die unit to create discrete products; in the exemplary embodiment, the hood assembly  10  is used in conjunction with a conventional extruder  18 . The purpose of hood assembly  10  is to maintain the discrete products in a separated condition for delivery onto a take-away device, such as an inlet belt  20  of a product dryer (see  FIG. 2 ). In this way, the discrete products are substantially prevented from agglomerating after extrusion and during downstream drying and/or other processing. 
     The housing  12  is generally semicircular in overall configuration and includes a pair of shiftable housing halves  22  and  24 . The halves  22 ,  24  are largely mirror images of each other, except for the differences described below. Thus, each housing half includes a rear end wall  26 ,  28 , an elongated arcuate sidewall  30 ,  32 , and a forward end wall  34 ,  36 . The sidewalls  30 ,  32  have detachable, somewhat U-shaped forward panels  38 ,  40  secured to the sidewalls  30  and  32  by latches  42 ,  44 . Each such panel has an inwardly extending wall segment  38   a ,  40   a , each having an arcuate inner margin which abuts the adjacent sidewall  30  or  32 . The halves  22 ,  24  cooperatively define the complete overall housing  12  when the walls are placed in adjacency, as illustrated in  FIG. 1 . In order to ensure proper attachment between the halves  22 ,  24 , the pair of alignment tabs  46  are provided on the butt edges of the front end walls  34 ,  36 , and a fore and aft latches  48  and  49  are provided to interconnect the halves. As depicted in  FIG. 1 , the front end walls  34 ,  36  are cooperatively designed to provide a knife drive opening  50 , which is important for purposes to be described, and are also equipped with observation ports  52 ,  54 . A bracket  56 ,  58  is secured to the outer surface of each sidewall  30 ,  32  and supports a spherical mount  60 ,  62 . 
     The deflector  14  is made up of two largely mirror image, half-frustoconical walls  64 ,  66 , with each wall being secured to and extending along the length of a corresponding housing half  22 ,  24  so that, when the halves  22  and  24  are closed together, the walls  64 ,  66  cooperatively define the substantially frustoconical deflector  14 . As illustrated in  FIGS. 4 and 5 , the wall  64  is welded or otherwise affixed to the inner surface of sidewall  30 , and is further supported by means of tabs  68  secured to rear end wall  26 . As such, it will be observed that a semicircular, generally triangular in cross-section, open-ended airway  70  is defined between the outer surface of wall  64 , the inner surface of sidewall  30 , and the inner surface of end wall  26 . A semicircular air outlet  72  is in communication with airway  70  and is defined between the inboard margin  74  of wall  64  and a semicircular collar  76 , the latter being secured to and extending forwardly from rear end wall  26 . 
     The frustoconical wall  66  is likewise secured to the inner surface of housing sidewall  32 , thereby also defining a semicircular, generally triangular in cross-section airway  78  between the outer surface of wall  66 , the inner surface of sidewall  32 , and the inner surface of end wall  28 . A lower tab  80  provides further support for the wall  66 . However, at the upper end of the airway  78 , a somewhat triangular panel  82  is provided which closes the upper end of airway  78 . A semicircular air outlet  84  in communication with airway  78  is defined between the inner margin  86  of wall  66  and a semicircular collar  88  affixed to end wall  28 . 
     It will be appreciated that when the halves  22 ,  24  are closed against each other and latched together, the abutting walls  64 ,  66  define the substantially frustoconical deflector  14  having a relatively small product inlet opening  90  defined by the abutting collars  76  and  88 ; a relatively large deflector product outlet opening  92  in spaced and opposed relationship to the opening  90  and defined by the outer margins  94 ,  96  of the walls  64 ,  66 ; an essentially full-circle airway  98  defined by the aligned airways  70  and  78 ; a circular air outlet  100  defined by the now-aligned outlets  72  and  84  in communication with airway  98 ; and that the sidewalls  64  and  66  forward of the outer margins  94 ,  96 , the front walls  34 ,  36 , and the panels  38 ,  40  cooperatively provide a an elongated, laterally extending, open-bottom product confinement zone  102 . 
     The air delivery assembly  16  is designed to supply airway  98  with pressurized air, and to direct such air through the outlet  100  in a direction towards the outlet opening  92  of deflector  14 . 
     To this end, an air inlet pipe  104  is secured to sidewall  32  and is designed to receive an air conduit (not shown), supplying pressurized air for passage through airway  98  and outlet  100 . 
     The extruder  18  in the illustrated embodiment has an elongated, tubular, multiple-head barrel including a terminal head  106 , with a pair of elongated, helically flighted, axially rotatable extrusion screws  108  within the barrel. The outlet end of head  106  is equipped with a transition  110  which is secured to the inlet  112  of a back pressure valve assembly  114 . The assembly  114  is itself conventional, and is designed to provide a selective degree of restriction to flow of material from the extruder barrel. The valve assembly is illustrated and described in detail in U.S. Pat. No. 6,773,739, wherein the portions thereof directed to the back pressure valve assembly  114  are incorporated by reference herein in their entireties. The outlet  116  of the assembly  114  is equipped with a transition  118 , the latter supporting a circular spacer  120 . A die plate support  121  is mounted on spacer  120 , and in turn supports a restricted orifice die plate  122  having a plurality of die openings therethrough. 
     A multiple-blade rotary cutoff knife  124  is positioned against the outer face of die plate  122 , and is secured to a knife shaft  126 . The shaft  126  extends through the shaft opening  50  and is coupled with a conventional motor drive (not shown). It will thus be appreciated that the die plate  122  and knife  124  provide a die unit  128 , which, with the overall extruder  18 , provides discrete cut extrudate products. 
     In order to further support the housing halves  22 ,  24  during swinging movement thereof, a pair of hinged support arms  130 ,  132  are operatively connected between the back pressure valve assembly  114  and the respective spherical mounts  60 ,  62 . In this manner, the halves  22 ,  24  may be easily swung between the closed position of  FIG. 1  and the open, access position of  FIG. 4 . 
     In the operation of hood assembly  10 , the use of air delivery assembly  16  is optional, i.e., with some products, it is unnecessary to provide air currents surrounding the die unit  128 . 
     In other instances, the air delivery assembly  16  facilitates separation of the cut extrudate. When used, the assembly  16  may be operated at a velocity of up to about 6,000 cubic feet/minute (cfm), more usually from about 2,000-4,000 cfm, and most typically about 3,000 cfm. The air may be ambient temperature air or heated to a temperature of up to about 80° C. Ambient air is preferred for reasons of cost, and also because ambient air helps to “set” the surface of the extrudates to reduce stickiness. In any case, use of the assembly  16  also helps deflect the extrudates so that they strike the deflector  14  at a lower angle, thereby reducing the probability of agglomeration on the side of the deflector. 
     While the invention has been described in the context of the twin screw extruder  18 , the invention is not so limited. That is, a single screw extruder could also be used or, for that matter, any other processing device, such as a pellet mill which will generate cut extrudate products. Moreover, while the support arms  130 ,  132  have been shown as mounted on the back pressure valve  114  assembly, this is a matter of convenience only, and such support arms, where used, may be supported on any other convenient portion of the overall apparatus.