Abstract:
A method and apparatus for cutting a puff extrudate utilizing a blade that passes through the extrudate while the extrudate is in a viscous melt stage. The present invention utilizes a tube to facilitate production of a curly puff extrudate. A gap is provided in between the tube and the extruder die to allow a blade to access the extrudate as it exits an orifice in the die. The blade accesses the extrudate at the viscous melt stage, before the extrudate has cooled and hardened. The blade nicks the extrudate, as opposed to completely cutting it, which allows the extrudate to remain connected throughout processing such as curling in the containment tube. The gap also allows steam to be vented form the extrudate as it exits the orifice in the die. The nicked extrudate separates when fried or baked.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Technical Field  
           [0002]    The present invention relates generally to the production of a puff extrudate and, specifically, to an improved process of producing a plurality of similarly shaped curly puff extrudate pieces from a single curly puff extrudate.  
           [0003]    2. Description of Related Art  
           [0004]    The production in the prior art of a puff extruded product, such as snacks produced and marketed under the Cheetos™ brand label, typically involves extruding a corn meal or other dough through a die having a small orifice at extremely high pressure. The dough flashes or puffs as it exits the small orifice, thereby forming a puff extrudate. The typical ingredients for the starting dough may be, for example, corn meal of 41 pounds per cubic foot bulk density and 12 to 13.5% water content by weight. However, the starting dough can be based primarily on wheat. flour, rice flour, soy isolate, soy concentrates, any other cereal flours, protein flour, or fortified flour, along with additives that might include lecithin, oil, salt, sugar, vitamin mix, soluble fibers, and insoluble fibers. The mix typically comprises a particle size of 100 to 1200 microns.  
           [0005]    The puff extrusion process is illustrated in FIG. 1, which is a schematic cross-section of a die  12  having a small diameter exit orifice  14 . In manufacturing a corn-based puff product, corn meal is added to, typically, a single (i.e., American Extrusion, Wenger, Maddox) or twin (i.e., Wenger, Clextral, Buhler) screw-type extruder such as a model X 25 manufactured by Wenger or BC45 manufactured by Clextral of the United States and France, respectively. Using a Cheetos like example, water is added to the corn meal while in the extruder, which is operated at a screw speed of 100 to 1000 RPM, in order to bring the overall water content of the meal up to 15% to 18%. The meal becomes a viscous melt  10  as it approaches the die  12  and is then forced through a very small opening or orifice  14  in the die  12 . The diameter of the orifice  14  typically ranges between 2.0 mm and 12.0 mm for a corn meal formulation at conventional moisture content, throughput rate, and desired extrudate rod diameter or shape. However, the orifice diameter might be substantially smaller or larger for other types of extrudate materials.  
           [0006]    While inside this orifice  14 , the viscous melt  10  is subjected to high pressure and temperature, such as 600 to 3000 psi and approximately 400° F. Consequently, while inside the orifice  14 , the viscous melt  10  exhibits a plastic melt phenomenon wherein the fluidity of the melt  10  increases as it flows through the die  12 .  
           [0007]    It can be seen that as the extrudate  16  exits the orifice  14 , it rapidly expands, cools, and very quickly goes from the plastic melt stage to a glass transition stage, becoming a relatively rigid structure, referred to as a “rod” shape if cylindrical, puff extrudate. This rigid rod structure can then be cut into small pieces, further cooked by, for example, frying, and seasoned as required.  
           [0008]    Any number of individual dies  12  can be combined on an extruder face in order to maximize the total throughput on any one extruder. For example, when using the twin screw extruder and corn meal formulation described above, a typical throughput for a twin extruder having multiple dies is 2,200 lbs., a relatively high volume production of extrudate per hour, although higher throughput rates can be achieved by both single and twin screw extruders. At this throughput rate, the velocity of the extrudate as it exits the die  12  is typically in the range of 1000 to 4000 feet per minute, but is dependent on the extruder throughput, screw speed, orifice diameter, number of orifices and pressure profile.  
           [0009]    As can be seen from FIG. 1, the snack food product produced by such process is necessarily a linear extrusion which, even when cut, results in a linear product. Consumer studies have indicated that a product having a similar texture and flavor presented in a “curl,” “spiral,” or “coil spring” shape (all of which terms are used synonymously by Applicant herein) would be desirable. An example of such spiral shape of such extrudate is illustrated in FIG. 2, which is a perspective view of one embodiment of a spiral or curl shaped puff extrudate  20 . The apparatus for making curly puff extrudate is the subject matter of U.S. patent application Ser. No. 09/952,574 entitled “Apparatus and Method for Producing a Curly Puff Extrudate” and is incorporated herein by reference.  
           [0010]    Curly puff extrudate  20  has proven difficult to cut into smaller, more manageable extrudate pieces. Some type of containment vessel such as a pipe or tube (terms used synonymously by the Applicant herein) is used for the curly puff extrudate production and a cutting device at the end of the tube results in surging and plugging within the tube, particularly during start-up and shutdown of the extruder. FIG. 3 illustrates a perspective view of a device involving a number of tubes  30  attached to a die face  18 . The exit end of each tube  30  is attached to an extruder face  23 . This arrangement then permits the attachment to the extruder face  23  of a circular cutting apparatus  24  having a number of individual cutting blades  26 . Such an arrangement is shown with ten tubes  30  connected to a die face  18 . Although not shown in FIG. 3, the tube  30  and extruder face  23  configuration can be designed such that the dies  12  are allowed to vent until specific conditions are met (such as extrudate bulk density, specific mechanical energy, moisture content, screw speed, and die pressure), then the tube  30  can be rotated over the dies  12  by device of an additional rotatable plate (not shown) between the tubes  30  and the dies  12 .  
           [0011]    However, cutting the curly puff extrudate  20  at the end of the tube  30  in a multiple tube  30  assembly is not preferable because the cutting blades  26  drag the curly puff extrudate  20  from one tube  30  to another which results in jagged and non-uniform ends of individual curly puff extrudate  20  pieces. FIG. 4 is an example of a piece of curly puff extrudate  20  cut with a device similar to the one in FIG. 3. Additionally, when the curly puff extrudate  20  is produced in a multiple tube assembly, the tubes may not produce extrudate at the same rate, so a single cutter cutting multiple tubes will produce curly puff extrudate pieces of differing lengths.  
           [0012]    This problem can be overcome by completely severing the extrudate at the die face when it is in the plastic melt state rather than the glass transition state. However, severing the extrudate at the die face disconnects the individual extrudate pieces and it is sometimes preferable to keep the extrudate connected for processing before separating the extrudate into individual extrudate pieces. Examples of processing include: conveying, seasoning, stretching, separating, or confining the extrudate in a containment vessel. Therefore, a need exists for an effective method of cutting the extrudate in the plastic melt state without completely separating the extrudate  
           [0013]    Another problem with the apparatus in FIG. 3 is that it does not allow for the release of steam and other hot gasses released from the expanding extrudate. The steam and other gasses promote surging and plugging within the tube. Therefore, a need also exists for an apparatus and method for venting steam and other hot gasses so they cannot enter the containment device.  
           [0014]    It should be understood that while a need exist for an apparatus capable of cutting a curly puff extrudate without plugging a containment tube, the need is not limited to curly puff extrudate. A need also exists for an apparatus for cutting a sinusoidal puff extrudate as well as other types of linear and non-linear puffed extrudates.  
           [0015]    Consequently, a need exists for an apparatus and method of cutting the puff extrudate into smaller puff extrudate pieces that will create smooth cuts at each end of the individual pieces. A need also exists for an apparatus and method that will prevent plugging of the tube during start-up, operation, and shutdown of the extruder. A need further exists for a method of releasing steam from the expanding extrudate. Moreover, a need exists for an apparatus and method of controlling the length of the individually cut puff extrudate pieces in a configuration with multiple orifices for each die.  
         SUMMARY OF THE INVENTION  
         [0016]    The present invention comprises a nicking blade apparatus that nicks the curly puff extrudate rather than cutting it. The nicks create a series of weak points in the curly puff extrudate. The weak points are strong enough to keep the curly puff extrudate connected during the conveying process. However, when the curly puff extrudate is further processed in an oven or fryer, the curly puff extrudate breaks at the nicks, separating the curly puff extrudate into individual pieces.  
           [0017]    In order to properly facilitate the nicking process while the extrudate is in the plastic melt state, the nicking should occur as close to the diehead as possible. The tube is separated from the diehead so that a blade may access the diehead orifice. The resulting separation also allows steam from the expanding extrudate to vent instead of proceeding through the tube. The release of steam allows the curly puff extrudate to flow more smoothly through the tube and helps prevent plugging and surging.  
           [0018]    The proposed invention also comprises a tube positioning device that positions the tube over the diehead orifice during operation, but removes the tube away from the diehead orifice during start-up and shutdown. Removal of the tube from over the orifice is desired during start-up and shutdown because the extrudate tends to surge during these periods and plugs the tube. In order to facilitate nicks of different depths, a blade positioning device is also disclosed.  
           [0019]    The preferred embodiment of the present invention utilizes a nicking blade for every orifice. However, as some die configurations will not allow a nicking blade for every orifice, a central blade apparatus for nicking multiple orifices is also disclosed.  
           [0020]    The preferred embodiment of the present invention also utilizes an oven or fryer to separate the nicked curly puff extrudate. However, under certain circumstances, an oven or fryer is not preferable, so alternate separation devices are also disclosed. Alternative separation devices include a paddle wheel, a vibrating conveyer, and a tumbler.  
           [0021]    The above as well as additional features and advantages of the present invention will become apparent in the following written detailed description.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein:  
         [0023]    [0023]FIG. 1 is a schematic cross-section of a prior art puff extrudate die;  
         [0024]    [0024]FIG. 2 is a perspective view of a length of curly puff extrudate product;  
         [0025]    [0025]FIG. 3 is a perspective view of a puff extrudate face cutter applied to the curly puff extrudate production apparatus as disclosed in U.S. patent application Ser. No. 09/952,574;  
         [0026]    [0026]FIG. 4 is a perspective view of a piece of curly puff extrudate cut using a puff extrudate face cutter;  
         [0027]    [0027]FIG. 5 is a side view in elevation of one embodiment of the present invention;  
         [0028]    FIGS.  6 A- 6 C are side views in elevation of the positioning of the tube from start-up through operation for one embodiment of the present invention;  
         [0029]    [0029]FIG. 7 is a plan view of one embodiment of the present invention incorporating a configuration utilizing a single blade for each orifice;  
         [0030]    FIGS.  8 A- 8 C are side views of one embodiment of the present invention utilizing a single nicking blade for multiple orifices;  
         [0031]    [0031]FIG. 9 is a perspective view of piece of curly puff extrudate cut with the present invention; and  
         [0032]    FIGS.  10 A- 10 B are front views in elevation of the paddle wheel separator of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0033]    [0033]FIG. 5 is an elevation view of one embodiment of the present invention. Identical reference numerals will be used to identify identical elements throughout all of the drawings, unless otherwise indicated. As with the prior art, the extrudate  16  exits an orifice  14  in the die  12 . The cross-sectional diameter of the orifice  14  is dependent on the specific dough formulation, throughput rate, and desired rod (or other shape) diameter, but is preferred in the range of 1 mm to 14 mm. (The orifice  14  diameter is also dependent on the mean particle size of the corn meal or formula mix being extruded.)  
         [0034]    If a curly puff extrudate  20  is desired, a tube  30  with a flapper  32  can be used. A flapper  32  puts pressure on the extrudate  16  exiting the orifice  14  so that curls will form in the extrudate  16 . A tube positioning device  34  is used to position the tube  30  in front of or away from the orifice  14 . The tube positioning device  34  is capable of moving the tube  30  in any direction relative to the die  12 . Examples of tube positioning devices are electrical servo motors, pneumatic actuators, hydraulic actuators, and mechanical screws. A tube blade  36  is also affixed to the end of the tube  30  closest to the die  12 .  
         [0035]    A nicking blade  40  is positioned flush with the die face  18  and either rotates or oscillates about a shaft  44 . The nicking blade  40  and the shaft  44  are powered by a motor  42 , which is connected to a blade positioning device  46 . The blade positioning device  46  is capable of moving the motor  42 , the shaft  44 , and the nicking blade  40  in any direction relative to the die  12 . Examples of blade positioning devices  46  are electrical servo motors, pneumatic actuators, hydraulic actuators, and mechanical screws. In order to effectively nick the extrudate  16  exiting the orifice  14 , the nicking blade  40  is positioned such that the end of the nicking blade  40  only partially covers the orifice  14  when passing in front of the orifice  14 . Allowing the nicking blade  40  to completely cover the orifice  14  would completely sever the extrudate  16 , which would not allow the extrudate  16  to remain connected for additional processing. It should be understood that the extent to which the nicking blade  40  covers the orifice  14  determines the depth of the nick in the extrudate  16 . Deeper nicks will allow the extrudate  16  to break more easily, a property referred to here as breakability. Shallower nicks will allow the extrudate  16  to stay connected more easily, a property referred to here as connectivity. The amount of coverage over the orifice  14  is expressed as a coverage percentage that is equal to the length of the nicking blade  40  covering the orifice  14  divided by the orifice  14  cross-sectional diameter. The coverage percentage desired will depend on the type of viscous melt  10  and orifice  14  size. Coverage percentages of eighty to ninety percent have generally been found to be an acceptable balance between breakability and connectivity for the melt  10  and orifice  14  size described herein. If desired, the rate at which the nicking blade  40  nicks the extrudate  16  can be increased such that the nicking blade  40  nicks the extrudate  16  faster than the extrudate  16  curls. When this is done and the nicked extrudate  16  is separated, smaller “C” shaped pieces of extrudate are formed.  
         [0036]    Another factor affecting the nick size is the nicking blade  40  tip shape. While pointed nicking blades  40  are capable of nicking the extrudate  16 , square edged nicking blades  40  (i.e. where the edge of the nicking blade  40  contains two ninety degree angles) have proven more effective at creating uniform nicks in the curly puff extrudate  20 .  
         [0037]    During start up, the tube  30  is positioned away from the orifice  14  with the tube blade  36  placed firmly against the die face  18 . As the extruder starts and approaches operating parameters, it will extrude undesirable extrudate  16 . The extruder also extrudes an excess amount of hot gasses, such as steam, from the orifice  14  during start up. Steam and other hot gasses tend to cause plugging in the tube  30 . Positioning the tube  30  away from the orifice  14  allows the undesired extrudate  16  to bypass the tube  30  and prevents the undesired extrudate  16 , steam, and other hot gases from plugging the tube  30 . The motor  42  is generally not run during start up so that the start up extrudate  16  is not nicked. Alternatively, if the motor  42  is running, the blade positioning device  46  can position the moving nicking blade  40  such that the blade cutting radius  22  does not cover the orifice  14 , and the nicking blade  40  will not nick the extrudate  16  nor interfere with the positioning of the tube  30 . In this manner, the motor  42  and the nicking blade  40  can be brought up to operating speed without nicking the extrudate  16  or interfering with the positioning of the tube  30 . If desired, the nicking blade  40  can be positioned by the blade positioning device  46  such that it completely cuts the extrudate  16  exiting the orifice  14 . This method cuts the extrudate  16  into smaller pieces and eliminates the need for a separating device.  
         [0038]    FIGS.  6 A- 6 C illustrate the process of starting up and operating one embodiment of the present invention. When the extruder reaches its operational parameters, the tube positioning device  34  positions the tube  30  so that the tube blade  36  is flush with the die face  18  (See FIG. 6A). The tube positioning device  34  then quickly slides the tube  30  across the die face  18  until the orifice  14  is within the inside diameter of the tube  30  (See FIG. 6B). When the tube blade  36  passes over the orifice  14 , the tube blade  36  slices off the old extrudate  16  and allows the orifice  14  to extrude a new extrudate  16  into the tube  30 , where the flapper  32  will contact the extrudate  16  and cause it to curl and form the curly puff extrudate  20 .  
         [0039]    After the tube positioning device  34  positions the tube  30  over the orifice  14 , the tube positioning device  34  moves the tube  30  away from the die  12  (See FIG. 6C). Separating the tube  30  from the die face  18  creates a gap  38 . The gap  38  allows gasses such as steam to escape from the expanding extrudate  16  and allows the nicking blade  40  to access the extrudate  16  as it exits the orifice  14 . Gap distances of 4-8 millimeters have been found to be a good balance between containing the curling extrudate inside the tube  30 , allowing the nicking blade  40  access to the extrudate  16 , and allowing sufficient release of steam. It should be understood that the gap  38  may vary depending on the pressure and temperature of the extrudate  16 , the back pressure created by flapper  32 , and the thickness of the nicking blade  40 .  
         [0040]    It should also be understood that multiple embodiments of the orifice  14 , the nicking blade  40 , and the tube  30  can be implemented on a single die  12 . FIG. 7 is an illustration of a die  12  with four such embodiments. The blade cutting radius  22  is defined by the outer reach of the nicking blade  40  and is shown only partially covering the orifice  14 . The position of the nicking blade  40  shown in FIG. 7 is preferable to other configurations, such as one in which the shaft  44  is closer to the edge of the die face  18 , because the blade cutting radius  22  does not extend beyond the perimeter of the die face  18 . Keeping the blade cutting radius  22  within the perimeter of the die face  18  helps prevent injury to people working in close proximity to the extruder and the die  12 . During operation of a die  12  with multiple orifices  14 , the extrudate  16  discharge rate may vary from one orifice  14  to another. The embodiment utilizing one nicking blade  40  for every orifice  14  is preferred because it allows an operator or automated controller to adjust the nicking blade  40  speed based on the extrudate  16  output rate and curling rate. By adjusting the speed of the nicking blade  40  to the output rate of the extrudate  16  of an individual orifice  14 , the distance between the nicks on the extrudate  16  from each individual orifice  14  can be precisely controlled and thus yield curly puff extrudate  20  pieces of uniform length.  
         [0041]    In certain situations, an embodiment utilizing a nicking blade  40  for every orifice  14  may not be necessary or preferable. In these cases, a central nicking apparatus  62 , as shown in FIGS. 8A, 8B, and  8 C, utilizing a central nicking apparatus positioning device (not shown), a blade positioning device  64 , and at least one blade  60  can be utilized. The central nicking apparatus positioning device can move the central nicking apparatus  62  in any direction relative to the die  12 . Examples of central nicking apparatus positioning devices  62  are electrical servo motors, pneumatic actuators, hydraulic actuators, and mechanical screws. A central nicking apparatus  62  like the one utilized in FIGS.  8 A- 8 C can be used to cut or nick a plurality of orifices  14 . FIGS.  8 A- 8 C are illustrations of the process of positioning the central nicking apparatus  62  into the center of the die face  18  such that the blades  60  of the central nicking apparatus  62  are able to nick multiple orifices  14 . In FIG. 8A, the central nicking apparatus  62  is positioned close to the die face  18 . A motor (not shown) powers the central nicking apparatus  62 . As the central nicking device  62  begins to rotate, the centrifugal force, caused by the rotation of the central nicking apparatus  62 , forces opens the blades  60 . The blade positioning device  64  guides the blades  60  into position such that they will be parallel with the die face  18  when completely opened. Alternatively, the blade positioning device  64  can be actuated or otherwise controlled to force the blades  60  into position. In FIG. 8B, the centrifugal force continues to expand the blades  60  and positions them adjacent to the die face  18 . The nicking apparatus  62  continues to rotate so that the blades  60  are moved into position and nick the extrudates  16  exiting the orifices  14  (See FIG. 8C). The blades  60  can also be extended far enough to completely sever the extrudates  16  exiting the orifices  14 .  
         [0042]    Referring back to FIG. 5, after exiting the tube  30 , the curly puff extrudate  20  is generally transported to an oven for baking or a fryer for frying. The nicks in curly puff extrudate  20  are weaker than the rest of the curly puff extrudate  20  and, consequently, the curly puff extrudate  20  breaks into individual curly puff extrudate  20  pieces with little or no mechanical manipulation upon baking or frying. FIG. 9 is an example of a nicked curly puff extrudate  20  piece that has separated in a fryer.  
         [0043]    In some applications, it may be desirable to separate the individual curly puff extrudate  20  pieces prior to baking, frying, or some other processing. In that case, there are a variety of devices that can be used to separate the nicked curly puff extrudate  20 . One type of separation device is a paddle wheel. FIGS. 10A and 10B are illustrations of a paddle wheel. In the embodiment disclosed in FIGS. 10A and 10B, the curly puff extrudate  20  exits the tube  30  and travels along a conveyer belt, which is parallel to the shaft  70  of the paddle wheel. The view in FIGS. 10A and 10B is that of the curly puff extrudate  20  being conveyed out of the page towards the viewer. Each paddle wheel comprises a shaft  70  connected to a motor (not shown). A plurality of paddles  72  are connected to the shaft  70 . When the shaft  70  rotates, the paddles  72  come into contact the nicked curly puff extrudate  20  (FIG. 10A). By this point, the curly puff extrudate  20  has cooled sufficiently to harden. When the paddles  72  come into contact with the curly puff extrudate  20 , the nicked curly puff extrudate  20  breaks at its weakest point, namely the nick. The individual curly puff extrudate  20  pieces then fall into a capture bin underneath the paddle wheel (FIG. 10B). A guide  74  keeps the curly puff extrudate  20  from repositioning itself out of the reach of the paddles  72 .  
         [0044]    It should be realized that a paddle wheel is not the only device for separating the individual curly puff extrudate  20  pieces. A tumbler could be employed to tumble the unseparated curly puff extrudate  20  until the curly puff extrudate  20  pieces break off. The curly puff extrudate  20  pieces could then be removed from the tumbler. The curly puff extrudate  20  can also be separated on a vibrating conveyer or a conveyer having steps or direction changes that facilitate product separation. Persons skilled in the art will also be aware of various other devices for separating nicked curly puff extrudate  20 .  
         [0045]    While the present invention is disclosed in reference to curly puff extrudate  20 , it should be understood that the present invention could be employed with cylindrical, uniquely shaped, or any other type of extrudate  16 . Additionally, the present invention can be utilized any time there is an need for cutting or nicking of a quasi-solid effluent from any type of process.  
         [0046]    It should further be understood that more than one die  12  could be routed into a single tube  30 . For example, a tube  30  can receive the extrudate  16  from two nearby orifices  14 . Further, dies  12  producing any number of shapes, such as a star or square cross section or more complex shapes, such as a cactus or pepper shape, can be used with the invention.  
         [0047]    Any number of various types of extruders can be used with the invention, including twin screw and single screw extruders of any length and operating at a wide range of rotational speeds. Further, while the process has been described with regard to a corn-based product, it should be understood that the invention can be used with any puff extrudate, including products based primarily on wheat, rice, or other typical protein sources or mixes thereof. In fact, the invention could have applications in any field involving extrusion of a material that quickly goes through a glass transition stage after being extruded through a die orifice.  
         [0048]    While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the