Abstract:
The invention relates to a tuna skinning machine, in which at least one conveyor belt ( 3 ) is installed along a frame ( 1 ) in order to move tuna loins ( 4 ) which, as they move, are worked by vertical-axis brushes ( 7 ) moving horizontally, horizontal-axis brushes ( 16 ) moving vertically and vertical-axis cutters ( 24 ) moving both vertically and horizontally, the brushes being designed to skin the tuna and the cutters being designed to remove the dark meat. This structure can be repeated several times along the frame, with the aforementioned cutter ( 24 ) being replaced in the final structure by a brush ( 37 ) that completes removal of the dark meat. The conveyor belt ( 3 ) has an end gap ( 39 ) containing a lower brush ( 38 ) for cleaning the lower face of the loin.

Description:
OBJECT OF THE INVENTION  
       [0001]    The present invention relates to a machine specially intended for the automatic skinning of the tuna, particularly tuna, Skipjack tuna and other fish of considerable importance for the canning industry. 
         [0002]    The object of the invention is to get a machine with optimal results in what regards to the skinning of the tuna, with parallel removal of the dark meat of the same and with high production rate, derived from a “continuous” work of said machine. 
         [0003]    The invention therefore lies in the field of industrial machinery specifically intended for the canning industry. 
       BACKGROUND OF THE INVENTION  
       [0004]    As known, the tuna have high muscular activity as a result of which their flesh is compact and pink, being even red in some species, with the exception of certain parts close to their spine, commonly referred to as dark meat, which have to be disposed of both for its appearance and its taste, particularly when the fish are intended for the canning industry, in which case it is also necessary to remove their skin, for obvious reasons. 
         [0005]    Today the removal of both the skin and the dark meat is carried out manually, with the help of a knife, which involves the participation of a very important labor force in the processing of these fish, which comes to be approximately 40% of the labor force used in the canning factory, when it is the same that performs the skinning operations of the tuna concerned. 
         [0006]    In the case of the tuna loin manufacturers, where the cleaning must be especially careful, the percentage of labor force may amount to up to 80%. 
         [0007]    From this problem derives the strong interest that the canneries and other manipulative tuna industries have to achieve a solution that enables to automate the process, with the consequent lowering of costs by eliminating such an important amount of labor force. 
         [0008]    An attempt to solve this problem has resulted in the Spanish Invention Patent with publication number 2,166,291, consisting of a “method for skinning of tuna and other species, for the canning industry and device thereof”. 
         [0009]    This method consists in turning the fish on its own axis, hung by its tail, while a cutting blade attacking tangentially the fish, while sliding along its axis, such that fish and blade describe a movement of helical trajectory, which results in the skinning of the fish. 
         [0010]    Regardless of the fact that this method does not provide a solution for the removal of the dark meat, it requires for its implementation that the fish is frozen, so that it is completely rigid, which means a significant complication from the point of view of handling, since such a situation of freezing must be kept, besides at very low temperatures, from the freezer of the fishing refrigerator ship to the point where there skinning is carried out, with the consequent and negative impact at the level of costs, both of the installation and the energy consumed to keep such a low temperature. 
         [0011]    In addition the method translates into a discontinuous operation machine, since after skinning the fish replacement of such a fish by another one that is not yet skinned is required. While the machine provides two operating stations, one for skinning and another one for loading/unloading, such that while the skinning occurs in one of the stations, the unloading of the skinned fish and the loading of the not yet skinned fish occurs in the other one, there is downtime resulting from the fact that this loading/unloading operation must be performed manually, with fish weighing usually between 10 and 15 kg, which involves keeping an important manual participation, with a work that is in addition very hard for the operators. 
         [0012]    The cited problem is so acute that despite the time elapsed since the cited Patent application this still has not been put into practice. 
       DESCRIPTION OF THE INVENTION  
       [0013]    The machine that the invention proposes resolves in a fully satisfactory manner the problems previously exposed, based on a totally different operating concept, such that the skinning of the tuna is not carried out with the fish frozen, as it was mandatory in such a Patent, but once they have been cooked and are at room temperature, prior separation of the four loins that are obtained from the fish. 
         [0014]    The machine that is advocated, instead of skinning the tuna by cutting, as the aforementioned Patent, it does it by abrasion, with the exception of a milling operation for removal of the dark meat, which as previously mentioned the machine of the aforementioned Patent is not capable of carrying it out. 
         [0015]    More specifically, from a suitable frame, a conveyor belt of controlled movement is installed on the same, in order to adjust the speed of the same, with which collaborates an encoder that, faithful to the transmission of the conveyor belt, generates pulses which scaled to a PLC, are transformed in millimetres of advance for such a belt. 
         [0016]    A pair of laser generates an analog signal to the PLC according to the distance read up to the belt “height”, in order to draw two curves corresponding to the loin of the tuna, whose variable profile is thus perfectly defined for the control of a set of brushes substantially cylindrical that carries out the operation of brushing and subsequent detachment of the skin. 
         [0017]    Specifically there are motorized and moving brushes, one of vertical drive and another one of horizontal drive, whose movement is carried out by means of respective endless screws, controlled by a servo motor, as well as the conveyor belt. 
         [0018]    As a complement to the structure described above, the machine incorporates also a cutter or crown gear, also with movement control, for removal of the dark meat. 
         [0019]    Specifically the machine is provided to perform two successive operational phases, a first phase that could be called the skinning itself, which removes the skin, dark meat, bones and dark parts, waste disposable for lack of value, and a second phase, immediately subsequently, of a more thorough cleaning, rotating brushes being used in both phases, while the cutter for removal of the dark meat exists just in the first phase, being replaced in the second phase by a brush for disposal of the waste of the dark meat, and finally installing a lower brush for cleaning the lower face of the loin. 
         [0020]    In this second phase the final cleaning of the loins of tuna is achieved, generating some waste, such as “bits”, of less value than the loins but usable. 
         [0021]    Through proper programming of the PLC both the speed and the direction of rotation, pressure of brushes and cutters on the loin of the tuna, etc., can be modified, where the machine works continuously, i.e. in the absence of downtime. 
         [0022]    In addition in order to facilitate the skinning of the loins, it is intended that the flesh of the fish is cold and its skin warm, heating the latter by means of hot air steam applied to the same. 
         [0023]    In this manner a considerably high production is achieved, with a reduction in labor force required for the skinning in the order of 70% and with a minimum loss of material, both in the form of chunks as well as bits, since the loins cross the machine supported entirely by their two fleshy faces, without changes of position such as rotation or turning over being required. 
     
    
     
       DESCRIPTION OF DRAWINGS  
         [0024]    To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, in accordance with an exemplary preferred embodiment of the same, a set of drawings comes as an integral part of such a description, wherein illustratively and in a not limited manner, the following has been represented: 
           [0025]    FIG.  1 .—It shows a front perspective schematic representation of a tuna skinning machine made in accordance with the object of the present invention, in accordance with an embodiment for the same wherein two parallel skinning and cleaning lines are defined. 
           [0026]    FIG.  2 .—It shows a side view of the same machine. 
           [0027]    FIG.  3 .—It shows a plan view of said machine 
           [0028]    FIG.  4 .—It shows a perspective detail of a brush-motor assembly moving horizontally. 
           [0029]    FIG.  5 .—It shows a similar representation to  FIG. 4 , but corresponding to a vertical brush-motor assembly. 
           [0030]    FIG.  6 .—It shows, again according to a perspective view, the two cutters assembly actuating on the two skinning lines of the machine. 
       
    
    
     PREFERRED EMBODIMENT OF THE INVENTION  
       [0031]    In the light of the above figures it can be observed that the machine proposed by the invention is made from a frame ( 1 ), which integrates two working lines ( 2 ,  2 ′), longitudinal and parallel, of simultaneous action, in each of which a conveyor belt ( 3 ) for moving loins ( 4 ) of the tuna concerned, previously obtained from fragmentation of the fish, is installed. 
         [0032]    Conveyor belt ( 3 ) is driven by a geared motor ( 40 ) controlled from a speed regulator, to regulate the speed of it, at the expense of commands generated by a PLC, collaborating with such a geared motor an encoder ( 6 ) that relates the rotation of the motor with the advance of the conveyor belt. 
         [0033]    A single geared motor ( 40 ) supplies the movement to the conveyor belts ( 3 ) participating in the machine. 
         [0034]    On each belt ( 3 ) a brush ( 7 ) of vertical axis ( 8 ) is installed, represented in detail in  FIG. 4 , driven by the corresponding geared motor ( 9 ), the guide bearing of said the motor being mounted on a mobile cart ( 11 ), moving transversally on guides ( 12 ) and with the collaboration of an endless screw ( 13 ) in turn driven through a servo motor ( 14 ), mounted on a bearing ( 15 ) conveniently attached to the frame ( 1 ), such a that through said servo motor ( 14 ), brush ( 7 ) is capable of laterally distancing or approaching with respect to tuna loin ( 4 ). 
         [0035]    A second brush ( 16 ) actuates immediately subsequently on loins ( 4 ) of the fish, that second brush ( 16 ) having a tilted axis ( 17 ), relatively close to the horizontal, through which it receives movement from the corresponding motor ( 18 ), whose bearing ( 19 ) is mounted on guides ( 20 ), in this case vertical, as shown in  FIG. 5 , with the collaboration of an endless screw ( 21 ) also driven by a second servo motor ( 22 ). 
         [0036]    Servo motors ( 14  and  22 ) actuate for the respective brushes ( 7  and  16 ) to copy the profile of fish loin ( 4 ), through signals received by the PLC from a pair of laser ( 23 ,  23 ′) conveniently mounted on the frame ( 1 ), as shown particularly in  FIG. 2 . 
         [0037]    Immediately subsequently and for each working line, i.e. in correspondence with each of the conveyor belts of the machine, corresponding cutters ( 24 ,  24 ′) of vertical axis ( 25 ) are installed, driven by respective motors ( 26 ) mounted on bearings ( 27 ), each bearing ( 27 ) being integrally joined to a cart ( 28 ) moving vertically on guides ( 29 ) with the collaboration of a screw ( 30 ), also vertical, associated with a servo motor ( 31 ) mounted in turn on a bearing ( 32 ). 
         [0038]    Each bearing ( 32 ) and consequently each cutter is also capable of moving horizontally with the collaboration of another servo motor ( 33 ), in this case actuating through a horizontal screw ( 34 ) on the aforementioned bearing ( 32 ), integrally joined to a pair of horizontal guides ( 35 ), common to bearings ( 32 ,  32 ′) of both cutters ( 24 ,  24 ′) and implemented on a common intermediate bearing ( 36 ), to which not only guides ( 35 ) but the two servo motors ( 33 ,  33 ′) of horizontal drive are fitted. 
         [0039]    The described structure, in what refers to brushes and cutters, can be single or can be double, depending for the first skinning phase of the machine on the level of cleaning required in each case, as occurs in the machine of the drawings, or even n-fold, without it affecting the essence of the invention. 
         [0040]    In the second operational phase of the machine, where skinning has already been committed completely or mostly, the machine reproduces the above described structure, with the only exception that the cutters ( 24 - 24 ′) are replaced by respective brushes ( 37 ), being equally driven by motors ( 26 ), which brushes ( 37 ) ensure a total removal of the dark meat. 
         [0041]    Each working line of the machine concludes with a brush ( 38 ) for the lower cleaning of loins, intended to actuate on the lower face of the same, and consequently located in a gap ( 39 ) of the conveyor belt ( 3 ), the brushes being driven by a second geared motor ( 5 ).