the method proposed by the invention allows mechanical skinning , ie ; skinning that produces a similar product to that which is obtained by the traditional manual skinning process , but with minimum labour , and , as a consequence , production costs that are considerably lower and the implementation of which takes place in the canning factory , although , whenever considered necessary , may take place on the fishing boat itself . to this end and more specifically , this method is carried out in the following way : the frozen fish is taken by its head and tail and is placed preferably vertically laterally to the fish and approximately corresponding with its mid section , a knife is placed on the surface of the fish at a certain angle and with certain elastic tension . the knife is subjected to a tilting movement from one extremity of the fish to the other , with a parallel movement , in such a way that the knife is kept permanently on a level passing through the axis of the fish the breadth of movement of the knife corresponds with the length of the fish , referring to the area of the fish to be skinned , in such a way that the combined movement of the knife , on the one hand , and of the fish on the other , generates a spiral action of the knife on the periphery of the fish affecting the entire surface of the fish . when the skinning has been completed the movement of the fish is stopped , the knife is separated and the fish is taken from its fastening . given that , as mentioned previously , the skinning operation takes place when the fish is still frozen , there is the option of using hot water , steam , hot air or any other heat - producing method , that momentarily lessens the degree of freezing on the skin of the fish , in order to assist the knives &# 39 ; cutting action . the device planned for the implementation of the method is made up of a rotating turntable or is on a linear chain , on which one or more loading stations are set up , with their respective skinning stations , which in the first case , on the rotating turntable , will be diametrically opposite one another , and at each there will be two clamps to secure the fish , in vertical alignment , connected to a common rotating device and having the means to regulate the distance between them in order that this distance can be made to accommodate the different sizes of fish . said knife is placed laterally to the fish which will be in the shape of a glass , ie , cylindrical , hollow and open at its cutting edge , which will be placed to correspond with the imaginary opening of the glass , said edge or blade preferably having many internal facets or rabbets , half - moon shaped , equally distributed , very closely together , in order to achieve the best cutting conditions . the shaft of the knife will be assembled with freedom of rotation on a supporting arm and aided by a motor transmitting a rotating movement of said knife on its own geometrical axis , said arm assembled to tilt on a support allowing the knife to move from one extremity of the fish to the other as it turns , as a result covering the entire surface thereof in a spiral cutting strip . said arm will also be permanently pressed against the body of the fish , by means of a spring or similar , so that the knife incise the latter with a level of penetration determined by a shoe or press which moves equally over the surface of the fish as it rotates . as a complement to the described structure and given that the length of said supporting arm for the knife is invariable , in order for said knife to be effective at any point along the length of the body of the fish , the section and distance of which varies substantially in relation to the pivoting shaft of the arm , it is planned that the support of said arm should be assembled so that it can be moved transversally , activated , for example , using a cylinder or similar , so that the knife is nearer the fish corresponding with both extremities of same and is retracted as it reaches its mid section , specifically remaining on a plane passing through the axis of the fish , to which end , a sensor , also acting on the surface of the fish , continuously sends positional control signals from the knife to the cylinder causing the transversal movement of the support . both work stations set up on the rotating turntable can be identical , ie ; both being supplied with the aforementioned cutting unit , in such a way that said cutting unit be inoperative in the loading station and operative in the skinning station , or said cutting unit may be set up in the skinning station exclusively . in accordance with another preferred embodiment of the invention is the use of several skinning knives , working simultaneously , each one affecting a section of the body of the fish , so that , on the one hand , its mobility is considerably reduced and , on the other , the skinning speed is markedly increased . it is also planned that the knives , instead of the aforementioned glass shape , be in a circular , serrated disc framed by a pair of turntables of a lesser diameter and with a perfectly smooth edge , which , when rotating with the knife itself , act like fences to the penetration of the latter in the body of the fish , and consequently having the means to set the depth of skinning . here , it is also planned that the different knives be attached to respective tilting arms assembled co - axially on the frame of the machine and activated simultaneously by a single engine , which transmits the movement of the knives through the hollow interior of the arms themselves , each of which is assisted by a twin effect pneumatic cylinder , which , on the one hand adequately presses the respective knife on the body of the fish during the skinning phase , and on the other , tilts the respective arm into a situation where it is inoperative , leaving the area where the fish is processed perfectly free for removing the skinned fish and substituting it for another . it is also planned that each knife have a sluice - way , into which it throws the remains of skin taken from the fish , running into the different sluice - ways , at different heights , like the knives themselves , in a lateral , vertical and fixed collector which , in turn , runs into any suitable container underneath . for this vertical movement of the knives along the length of the body of the fish , a bridge is set up on the frame of the machine , which is vertically mobile using a system of spindles and the respective motor , on the bridge are assembled the support arms for the knives and all their accessories . finally and for the purpose of fastening and moving the fish , the frame should have a rotating support at a low level , mounted on vertical guides and operated using a cylinder , said support having a lower motor that activates a clamp or flange with a pointed and serrated opening to be used to hold the head of the fish , vertically and with its tail pointing upwards , which is simply fitted inside a yoke - shaped support , able to rotate freely over the frame , in such a way that , because the lower rotating support can be moved at a height , it is very easy to implant the fish and it can be secured whatever its size , by lifting said lower rotating support to a greater or lesser degree , the upper yoke being slightly movable at a height because of the pressure exerted by the frozen fish at the final phase of fastening , in order to act on a sensor that keeps the knives inoperative until the fish has been correctly and definitively implanted into the machine . for the rest , the machine will have electrical and pneumatic automated mechanisms so it may be operated correctly from a control panel . to complement this description and with the object of assisting better understanding of the features of the invention in accordance with a preferred example of the practical embodiment of same , a set of drawings , that are illustrative and not limiting in character , accompanies said description as an integral part thereof , where the following are shown : fig1 .— shows a schematic plan view of a device for the implementation of the method for the skinning of tuna and other species object of the present invention fig2 .— shows , also as a schematic representation , a side elevation view of the device from the previous figure fig3 .— shows a representation similar to that of fig2 but for the final phase of skinning fig4 .— shows a frontal perspective view of a machine for skinning tuna and similar shown in accordance with the aforementioned alternative practical embodiment of same fig5 .— shows , also as a perspective view , an enlarged detail of the machine from the previous figure at the level of the cutting area fig6 .— shows , finally , a rear - side perspective view of the same machine from fig4 and 5 . looking at these figures , specifically from fig1 to 3 , it can be seen how the device for implementing the method of the invention is structured from a horizontal turntable ( 1 ), able to turn intermittently on its axis ( 2 ), 180 ° rotations to be specific , there being on said turntable ( 1 ) at least two work stations ( 3 - 3 ′), diametrically opposite one another , one for loading and one for skinning , in such a way that whilst the fish is being fastened on to the first ( 4 ) to its appropriate support ( 5 ) at the other , the fish is being skinned . obviously and depending on the machine &# 39 ; s intended operative capacity , two or more loading stations may be set up on the rotating turntable , grouped on a half - turntable and several other skinning stations on another half - turntable , in such a way that several fish may be loaded simultaneously by the respective operatives , whilst at the other side of the turntable several others are being skinned automatically , the turn - table continuing to rotate intermittently at angles of 180 °. obviously , the different work stations ( 3 - 3 ′) can also be set up in line , in a chain type system . in any case , the support ( 5 ) for the fish ( 4 ) perpendicular to the turntable ( 1 ) will be adjustable in length to fit different sizes of fish and will have arms ( 6 - 6 ′) at both ends with their respective opening clamps ( 7 - 7 ′), the first for securing the fish ( 4 ) at the area next to its tail fin and the second at its head , both co - axially , so that the fish is in the vertical position shown in fig2 and 3 . in order to make the support ( 5 ) adjustable in length , a telescopic structure could be introduced so that both sections are connected via a hydraulic or pneumatic cylinder ( 8 ) that would set the distance between the clamps ( 7 - 7 ′) to suit the needs of each case . the clamps ( 7 - 7 ′) fixed to the support ( 5 ) must have movable collars inside so that the fish can be rotated ( 4 ), attached to one of which will be a means of transmission ( 9 ) which , using a motor ( 10 ) or any other suitable motorised part , will cause the fish to rotate in a suitable fashion . along with the described structure there will be a knife ( 11 ) preferably cylindrical , hollow and open at its cutting edge , attached axially at its closed base to an shaft ( 12 ) assembled with freedom of rotation inside a tubular arm ( 13 ), further on from which will be the respective motor ( 14 ) which will supply the knife with a rotating movement on its own shaft to permit cutting . each arm is ( 13 ) assembled to tilt on a support ( 15 ) and is aided by a lateral cylinder ( 16 ) or any other suitable driving means to allow the arm itself to tilt ( 13 ) and consequently the knife ( 11 ) from the upper extremity of the fish ( 4 ) as shown in fig2 to the lower extremity of the fish as shown , in turn , by fig3 the cylinder being able to act simultaneously ( 16 ) as a means of pressing the knife ( 11 ) against the body of the fish , or this objective being achieved by an auxiliary spring ( 17 ), in such a way that the level of the knife &# 39 ; s ( 11 ) penetration into the body of the fish is determined by a shoe or press ( 19 ) which , placed near the knife ( 11 ) is permanently supported on the body of the fish . as can be seen by looking at fig2 if the arm ( 13 ) were supplied the aforementioned tilting movement alone , the knife ( 11 ) would only work on the extremities of the fish ( 4 ), being substantially distanced from it at its mid section , hence , it is planned that the support ( 15 ) be mounted on a transversal guide and aided by a driving cylinder ( 19 ) receiving information at all times from a sensor ( 20 ) accompanying the knife ( 11 ) as it moves along the length of the fish and supplying information to the cylinder ( 19 ) so that it responds ensuring that the longitudinal movement of the knife ( 11 ) to the body of the fish is achieved on an imaginary plane ( 21 ) passing through the axis of the fish , ie ; the knife ( 11 ) keeping continuous contact with the body of the fish ( 4 ) and in the best cutting conditions . in order to facilitate cutting , the device may be supplied with a nozzle ( 22 ) to supply hot air or any other thermal means to cause a degree of surface defrosting to the body of the fish ( 4 ). in accordance with the described structure , operation of the device is as follows : at the loading station ( 3 ), the fish is secured ( 4 ) vertically and with the head facing downwards , by closing the clamps ( 7 ) on the extremities of same as shown in fig2 . after securing the fish ( 4 ) on the aforementioned loading station ( 3 ) the main turntable ( 1 ) turns 180 ° in such a way that said loading station ( 3 ) comes to take up the skinning position , while the operative group at the skinning station ( 3 ′) goes to take up that position where , at said skinning station ( 3 ′), the arm ( 13 ) supporting the cutting knife ( 11 ) starts to tilt until the latter is supported on the body of the fish at one of its extremities , for example in the upper extremity position shown in fig2 at which time the motorised part ( 10 ) rotates the fish ( 4 ) while the knife ( 11 ) rotates on itself as the arm ( 13 ) tilts downwards in such a way that said knife ( 11 ) follows a spiral path on the surface of the fish with a degree of penetration or cutting determined by the adjustable shoe ( 18 ) and with progressive retraction of the knife ( 11 ) via the cylinder ( 19 ) until said knife reaches the mid section of the fish , to then move in the opposite direction in order to maintain the aforementioned cutting plane ( 21 ), in accordance with the signals generated by the sensor ( 20 ). during the skinning operation at the appropriate station ( 3 ′), the skinned fish will have been removed from the clamps ( 7 - 7 ′) at the loading station ( 3 ), and it will have been replaced by another fish , which after the skinning operation has been completed at the other station , will be ready to go there via the aforementioned 180 ° rotation of the turntable ( 1 ). in accordance with the alternative practical embodiment shown in fig4 to 6 , where the machine has one single work station , this machine is supplied with a strong frame ( 101 ) vertically lengthened where at a lower front level a pair of vertical guides are set up ( 102 ) for a support ( 103 ) to be moved in this direction using a pneumatic cylinder ( 104 ), a support ( 103 ) having a casing at the front ( 105 ), inside which is accommodated the motorised part of a clamp or flange ( 106 ) which , in addition to securing the fish by its head supplies it with the necessary rotating movement for it to be skinned , to which end said clamp or flange ( 106 ) has a pointed opening ( 107 ) with serrated edges , ensuring both perfect insertion of the head of the fish and correct fastening of same by simple gravity . securing of the fish is completed using an upper support ( 108 ) ending in a yoke ( 109 ), with its opening facing downwards , designed to take the tail of the fish , this upper support ( 108 ) being assembled on an upper and fixed crossbeam ( 110 ) of the frame ( 101 ) through a collar ( 111 ) allowing some upward movement of the support ( 108 ), which is pressed by the body of the fish during the lifting of the lower support ( 105 ) in order to act on a position sensor ( 112 ) impeding activating the machine &# 39 ; s skinning device should the fish not be properly inserted therein . thus , due to the fact that the lower support may be adjusted at a height ( 105 ), said support ( 105 ) is distanced from the upper support ( 109 ) to a sufficient extent to allow the fish to be inserted easily , and later to bring these two supports together to any size required by the length or body size of the fish , rigid due to its frozen state . now , to move on to the means of skinning , on the upper area of the frame ( 101 ) it is planned that there should be a mobile transversal bridge ( 113 ) also movable on vertical guides ( 114 ), appropriately placed on the frame ( 101 ), specifically using at least one spindle activated by a power unit ( 115 ), there being another power unit ( 116 ) set up on said mobile bridge ( 113 ) transmitting movement simultaneously to a pair of knives ( 117 - 117 ′) through the hollow interior of the respective arms ( 118 - 118 ′), in such a way that these knives ( 117 ), moving continuously during the cutting phase , may be moved the length of the appropriate half of the fish , via the movement of the head itself ( 113 ) due to the effect of the motor ( 115 ), at the same time as they are kept in constant contact with the fish , irrespective of the anatomical variations thereof , in its rotating movement due to the effect of respective twin effect pneumatic cylinders ( 119 - 119 ′), which , during the cutting phase adequately press the respective arms ( 118 - 118 ′) against the fish , so that the knives act as a consequence ( 117 - 117 ′) and so that , in the phase of replacing the fish , they pull the arms ( 118 ) outwards , so that these , and , as a consequence , the knives , leave the handling area totally free . a sensor ( 120 ) placed at a lower level to the longest arm ( 118 ′), detects the end of the path over the body of the fish sending the appropriate control signal to the motor ( 115 ) so that it is stopped in the descent of the mobile bridge ( 113 ) and the knives are returned to their upper limit position . the knives ( 117 - 117 ′), as can be seen especially well in the enlarged detail of fig5 are made in a circular disc with a serrated edge that is framed by two plates ( 121 ), of a lesser diameter and smooth edge , acting as fences to the knives &# 39 ; penetration into the body of the fish . additionally , each knife ( 117 - 121 ) is assisted by a sluice - way ( 122 ) for waste , that goes with the knife as it moves and which runs into a vertical , fixed collector ( 123 ) which channels the waste into any receptacle or container , for which purpose said collector ( 123 ) has a longitudinal groove ( 124 ) in line with one of its generators , allowing free movement of the aforementioned sluice - ways ( 122 ) along the length thereof . the machine should be connected to a pressure source as can be seen from fig6 for activating the pneumatic mechanisms , while the electrical circuit governing the same is contained in a rear cabinet ( 125 ), receiving commands via a control panel ( 126 ) situated at its front face .
the method involves turning the fish around its own axis while a cutting blade is longitudinally displaced along the body of the fish and contacts the latter in such a way that the blade follows a helicoidal trajectory in relation to the skin of the fish thereby making it possible to fully skin the fish . to this end , the device has a pair of clamps to fix the fish in vertical position and preferably with the head facing downward . the clamps are aided by a rotational actuator delivering said movement to the fish while the blade is permanently pressed on the fish by a spring and is moved along the fish by a cylinder or any other appropriate means . the arm is rotated on a support located at mid - height and can be displaced transversally by a cylinder so that the blade can permanently work in an imaginary plane perpendicular to the axis of the fish .