This invention relates to an apparatus and method for filling a canning container with a shaped foodstuff product, such as tuna fish.
1. Field of the Invention
Because of the known characteristics of tuna fish and the problems associated with the intrinsic nature of this foodstuff the subject invention is particularly suited for the canning of tuna fish. The invention provides a machine, device or apparatus which shears fillets of tuna fish according to a predetermined orientation of the tuna fish fibers into slices of tuna chunks, successively compacts the chunks into a mass and compresses the mass to a predetermined density for maintaining products of consistent size, weight and volume forms and cuts cylindrical shaped container charges of the tuna product from the compressed mass, and transfers the firm, compact, homogeneous and non-crumbly charges of the tuna product into the canning tins or containers.
2. Discussion
It is known that the automatic filling of relatively small cylindrical cans with the cylindrically shaped charges of tuna product presents various problems due to the irregular consistency of the fish fillets which makes it necessary to compact and compress the sliced tuna chunks so as to provide products of consistent weight, volume and density which are introduced into the canning containers.
One prior tuna fish canning apparatus is known from the U.S. Pat. No. 3,700,386, granted to Mencacci on Oct. 24, 1972. This prior can filling invention has an apparatus for filling only one can at a time with sliced tuna chunks which are compressed and shaped into a cylindrical pellet by a moveable shaping wall having an arcuate depression pushing on one side of the tuna chunks, while forceps-like knives having facing arcuate depressions are squeezing opposite sides of the tuna chunks. There is no way disclosed to control the weight, volume and density of the formed product prior to insertion in the can.
Another prior tuna fish canning apparatus, which is an improvement over the Mencacci device, is know from the U.S. Pat. No. 4,641,487 granted to Darecchio on Feb. 10, 1987. In this prior apparatus two charges of the cylindrically formed tuna product are ejected vertically into two canning containers. Chunks of the sliced tuna fillets are dropped by gravity, vertically into a horizontal shaping channel wherein a reciprocable extrusion plunger compacts the chunks and compresses them against a fixed lobed end of the channel. The fixed cusp between the lobes bifurcates the mass moving into the semi-cylindrical depressions forming the lobes in the fixed end wall. The semi-cylindrical surfaces also form vertical semi-cylindrical wall extensions for a pair of axially aligned upper and lower through bores, through which a pair of cylindrical hollow dies cut out a pair of cylindrical pellets from the bifurcated mass trapped in the lobes. A gate below the lower pair or through bores is opened and a pair of cylindrical pistons, concentric within the dies which have been introduced with the pellets therein into a pair of cans disposed under the lower pair of bores, are ejected from the dies into the cans, by the pistons, as the dies are retracted from the cans, without any loss of product. the Darecchio apparatus, even though it has solved various problems with prior fish can filling devices, it too has drawbacks, which have come to light during the course of its operation and use through the years.
One of the short comings is due to the high friction of the tuna chunks moving along the walls of the compression channel toward the fixed lobed end which causes an excessive compactness and therefore squeezing of the product against the container walls. The friction is further increased by the fixed position of the cusp or separating element which divides the mass into two streams entering the confines of the lobes.
Another short coming found in the known machines relates to the weight checking of the product for each tin. The only possibility of checking is often by means of adjusting the pneumatic pressure of the extrusion plunger or compression piston feeding the segments to the lobed end of the channel. This solution is not the ideal one for tuna processing machines because it may happen, during this processing, that the density of the formed cake changes considerably in consequence of quality changes of the fish or cooking conditions. If one tries to compensate for these changes by increasing or decreasing the pneumatic pressure to the compression piston, the product runs the risk to be damaged.