Processes for stuffing meat products have been continually improved over the years.
U.S. Pat. No. 4,155,212, for example, relates to a mechanism for wrapping a netting around a meat piece, provided with a cylinder around which is placed the netting in which the meat piece supplied from a table is introduced manually and pushed manually or by a piston. The meat is pushed through the inside of the cylinder and leaves out of its discharge opening wrapped in the netting.
U.S. Pat. No. 4,621,482 considers the additional application of a collagen film that, together with the netting, wraps the meat in a stuffing apparatus.
An evolution of these systems is found in U.S. Pat. Nos. 4,910,034 and 4,958,477, which respectively show a process and an apparatus for production of meat products. The process for obtaining the final product consists mainly of simultaneously wrapping the meat products with a collagen film and an elastic netting supplied from tubes concentric to the central tube in which the meat pieces travel. Both the meat feeding and impulsion through the tube are manual in these systems.
The manual stuffing process generally requires one person to feed the meat pieces to the machine and another person to receive the stuffed product from the applicator tube, conform and clip it and deliver it to a third person who clips it. The working speed of this system is not greater than 5 pieces per minute. Applicators exist that are connected to a stuffing machine that feeds the meat, but their speed is the same, although they work with one less person.
The TCM machine of Tipper Tie incorporates a pneumatic piston for pushing the meat and an automatic clipping system at the applicator outlet that allows a rate of 7-8 pieces per minute. However, it has limitations regarding the dimensions of the clipping system, its slowness and the need to feed the machine manually interrupting the process during loading.
Patent application WO 03/066440 describes a method and apparatus for automatic stuffing of meat pieces in a double casing of film and netting, in which participate a synchronised stuffing machine and fast clipper and where the meat piece is made to pass through a tube with a small diameter independent of but smaller that the size of the finished product. The rates reached depend on the flow of meat that the stuffing machine can impel and the time taken by the clipper to clip, reaching a production on the order of 30 pieces per minute.
The machine that constitutes the object of the aforementioned patent application WO 03/066440 is conceived to stuff only meat made of small pieces that can be fed by pumping by a stuffing machine.
There are, however, a number of products that must be manufactured without pumping. These are those made of entire muscles. These are top-end products that require the integral maintenance of the muscle structure and those in which it is desired to have the product wrapped with its skin visible on the surface. These products cannot be stuffed by a pumping means nor through small diameter tubes, as they would lose their structure and order.
If the apparatus described in the aforementioned U.S. Pat. No. 4,958,477 is provided with a mechanical impulsion means, such as a pneumatic piston, and combined with an “iris” type clamp clipper such as that described in U.S. Pat. No. 6,705,063, which allows passage of pieces with a diameter of up to 180 mm and a high-rate clipping, this may provide a first step towards mechanisation of the stuffing process of said products that cannot be pumped. However, to improve the results obtained by the aforementioned TCM machine of Tipper Tie, this system would require an automatic stuffing system that reduces to a minimum the loading time of the entire muscles.
In manual loading systems the meat pieces are loaded in a chamber of the applicator after the cylinder has retracted from its pushing stroke. To do so, the chamber lid must be opened and the meat piece must be placed in it orderly and with a specific orientation, taking care that the skin, if it must be visible from the outside in the stuffed product, is properly extended in the surface. The preparation time involved in positioning the meat piece and the subsequent closing of the lid, whether manually or mechanically, until the meat is finally impelled by the piston, implies lost time for the system that will remain unproductive.
The automation of the feeding and its operative optimisation therefore constitute the objectives of the invention described below.