AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT TAPERED MEAT MINCER The following statement is a full description of the invention, including the best method of performing it known to me: 1 TAPERED MEAT MINCER In the food industry for instance, in the preparation of foodstuffs and related material, meat is required to be minced. The meat so minced is required to be of varying grades, depending upon the required end use of the minced product. The best type of minced meat is of the form where it has not been worked as a part of 5 the mincing process and thus maintains the required constituent substance. The required product consistency may be fine or course, but either way, high quality output requires that the product has a defined particulate form. By the nature of how the meat is transported within the standard mincing machine, and thus taken to the cutting head, it is worked by the internal mechanism such that, typically, 0 particulate form is lost. The conventional meat grinder or mincer consists of a method to feed the meat to be minced into or onto a transport system that typically consists of a screw drive mechanism. The feed screw rotation transports the meat along the length of the feed screw until it impinges upon a fine orifice mincing end plate with adjacent 5 rotating cutters. As the meat is pushed against the plate it is extruded through the small orifices within the plate and cut off by the rotating cutters. The extruded and cut meat, which is the desired end product, is then collected after it has passed through the end plate. The feed screw mechanism of a typical or conventional meat mincer extends from 0 the point where the meat enters the transport system through to the end plate, is comprised of one or two segments and is of a consistent diameter throughout the length of the feed screw. Typically, the feed screw fits within an outer housing and thus the meat is channelled and forced along and through the length of the feed screw and housing by rotation of the feed screw until the meat impinges on the end 25 plate. The meat is forced to move through the length of the feed screw and housing because of the rotation of the feed screw and the generally incompressible nature of the meat, and in doing so is squashed, sheared, shredded and heavily worked between the various moving surfaces, thus damaging the meat structure. The excessive working of the meat with subsequent loss of meat fibre definition 30 and structure and, most specifically, the lack of definition of the particulate nature of the end product is the worst possible outcome for minced meat required for a large variety of meat products. It is therefore the primary and preferred object of the invention to provide a meat mincing system that enables the mincing of meat on a large scale without working 2 the meat such that particulate definition of the minced meat is always provided to the required size and consistent with the defined minced meat output requirements. The use of a parallel screw feed and the equivalent parallel housing in typical meat mincing mechanisms also imposes excessively high mechanical loads on the 5 mechanism. These loads become excessive the larger the machines used and the greater the mince output flow rates sought. It is therefore another preferred objective of the invention to provide a high rate of minced meat output that requires a comparatively low power input to produce and conveys low mechanical stress on the working parts of the mechanism. Such an 0 invention, embodying these capabilities will have a high output yield and is able to use standard industrial motors to drive the mechanism without loss or degradation of functionality. As the meat in a typical mincer movers towards the orifice end and reaches the end of the drive screw mechanism it leaves the feed screw and enters the cutting zone 5 and is pushed by compression through the cutting zone towards the mincing end plate. As the transported meat is leaving the end of the screw it is critical for the meat flow not to be disturbed by the passage of the proximal cutter assembly until the meat reaches the mincing end plate and is cut to the correct longitudinal size by the cutter blades. Incorrect positioning of the cutter mechanism can imping on the 0 flow of the transported meat further working the meat or reducing or impeding the flow of meat to the mining end plate. It is therefore another preferred objective of the invention to have the cutting assembly in a fixed and defined position relative to the outlet segment through which the transported meat leaves the feed screw and passages to the mincing end '5 plate. The particulate size of the minced meat end product will vary depending upon the demands of the consumer. The particulate size is determined by the size of the multitude of orifice holes in the end plate, the pressure upon the meat product as it is extruded through the orifice end plate holes and the flow rate of the meat, thus 30 determining the length of the extruded meat when the cutter crosses the face of the end plate and cuts the meat to length. In a typical mincer the only variable in this entire process it the size of the orifice end plate used. It is therefore very difficult to alter the particulate size produced to meet the demands of the consumer.
3 It is therefore another preferred objective of the invention to be able to vary the orifice end plate size, the geometry of the feed screw and feed screw assembly, the delivery and flow rate of the meat, and the pressure and extrusion rate of the minced meat so produced such that the particulate size is able to be adjusted to 5 meet the requirements of the consumer. Broadly the invention comprises a device with a feed screw mechanism fitted within a housing such that unprocessed meat that is placed into the mechanism at one end is transported along the feed screw and within the housing until it reaches an end plate and cutting mechanism where the meat is cut by the cutting blades 0 attached to the end of the feed screw and the meat is then forced and extruded through a large number of relatively small orifices in the end plate. The feed screw and housing may typically comprise two joined segments, the first being cylindrical and constructed parallel to the axis of rotation of the feed screw and of consistent screw pitch and diameter, and the second segment which is clearly 5 frusto-conical or outwardly flared at a constant angle of the internal walls of the housing with a tapered feed screw segment that fits snugly within the housing and is of varied pitch, diameter and depth such that the volume within each tapered feed screw flute is essentially constant. The frusto-conical section provides for a larger total volume of the meat to be transported at a lower longitudinal rate, 0 without the meat being worked, overheated or separated, such that the end product remains particulate in nature and ensures particulate definition of the required end product size. The frusto-conical section can be stand alone, with a very short feed segment, be a part of a manufactured two section mechanism as outlined herein, or be attached to or replace an existing cylindrical feeder screw such that the frusto 25 conical section becomes the final segment that undertakes the mincing process. The invention may be better understood with reference to the accompanying drawings, which show one example of the invention. The drawings depict the application from a holistic context. In order that the invention may be readily understood and put into practical effect, preferred 30 embodiments are described by way of example with reference to accompanying drawings as stated. Figure 1 is a sectional view of the entire feed screw, housing and end plate assembly. This figure depicts the invention for clarity, without specifying 4 preferred embodiments. Meat is fed into or onto one end or portion of the cylindrical feed screw (1) to begin the meat transport process. Said cylindrical feed screw typically has a constant diameter, constant pitch and constant depth, with the pitch being typically greater than that of the tapered feed screw (2) within 5 the frusto-conical housing (3). The length of said cylindrical feed screw is minimised to reduce possible working of the meat and the geometry of said cylindrical feed screw is designed such that the amount of meat able to be fed into the meat mincing assembly is controlled and matched to all segments involved. Figure 2 is a plan view of the entire feed screw depicting the geometry of the 0 tapered arrangements. Both the cylindrical feed screw section (1) and tapered feed screw section (2) are depicted. The length of said cylindrical feed screw is minimised such that the volume of meat transported by this section exactly matches the required meat transport volume of said tapered feed screw (2). The pitch (4) of said tapered feed screw (2) varies along the length of the taper (5). 5 This pitch is also able to be varied across the entire tapered feed screw to provide the exact feed rate required for the desired end product. Similarly, the diameter (6) of said tapered feed screw and the depth from the outer edge of said tapered feed screw to the inner core (7) vary constantly along the length of said tapered feed screw such that the total volume within each flute (8) of said tapered feed screw is '0 constant throughout the length of said tapered screw feed. The entire geometry of said tapered feed screw assembly is able to be varied to meet the mass, flow rate, pressure and volume of transported meat required to match the orifice end plate and cutting blade size and geometry and thus ensure the desired particulate size for the required end product without compromising the quality of the minced meat 25 through overworking of the product. Figure 3 is a sectional view of the frusto-conical housing (3) showing the machined inner section (9) that allows the tapered feed screw to fit within and rotate with close tolerances to the inner face of said frusto-conical housing ensuring optimal transportation of the meat product without working said meat as it is transported 30 through the housing section. Figure 4 is another sectional view of the entire feed screw, housing and end plate assembly. Meat travels along the tapered feed screw (2) and within the frusto conical housing (3) until it is compressed against the orifice end plate (10) and 5 cutting blades (11). Said cutting blades then cleanly slice the meat as the meat is extruded under pressure through the numerous small holes in said orifice end plate. Figure 5 is a lateral view of the orifice end plate (10). The view demonstrates the numerous small holes within said orifice end plate through which the meat product 5 is extruded under pressure. The cuttings blades (11) are depicted on the obverse side of said orifice end plate and can be seen in a four-blade arrangement. The actual number of blades and their geometry are determined and provided so as to ensure the correct size of the meat particulate that is cut off by said cutting blades as the meat is extruded through said orifice end plate. The cutting blade assembly 0 is attached to the end of the tapered feed screw (2) in a fixed position such that the meat flowing from the end of said tapered feed screw is not impeded by said cutting blade assembly. It is readily apparent to the skilled addressee that the present invention provides a tapered meat mincer assembly therefore, which has many advantages over the prior 5 arrangements. Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention defined in the appended claims.