WO2001013732A2

WO2001013732A2 - Skinning apparatus

Info

Publication number: WO2001013732A2
Application number: PCT/US2000/023148
Authority: WO
Inventors: Somsak S. Rodboon; Kirk T. Selenberg; Eric W. Morales
Original assignee: The Laitram Corporation
Priority date: 1999-08-26
Filing date: 2000-08-23
Publication date: 2001-03-01
Also published as: WO2001013732A3; AU7066800A

Abstract

An apparatus for removing a surface layer from an animal includes a plurality of flexible paddles (130) rotatable about a rotational axis. The paddles (130) have radially outer ends arranged at a plurality of angles with respect to the rotational axis. When the paddles (130) are rotated about the axis, the radially outer ends of the paddles can contact a surface layer of an animal and remove it while removing a minimum of the underlying meat. The apparatus is particularly suitable for skinning of fish.

Description

SKINNING APPARATUS

Background of the Invention

1 Field of the Invention This invention relates to an apparatus and method for removing skm or other surface layer from the body of an animal Such an apparatus will be referred to as a skinning apparatus, although it is not restricted to use for the removal of skm The apparatus and method are particularly suitable for use in removing the skm from fish

2 Description of the Related Art Some varieties of food fish, such as tuna, marhn, shark, and swordfish, have a tough, inedible skin The meat of such fish can be sold with the skm attached, to be removed by the consumer, but it is frequently desirable to remove the skin before marketing the meat, smce the skinned meat is more appetizing and may bπng a higher price than meat with the skm attached

Summary of the Invention

The present mvention provides a skinning apparatus capable of automatically removing skm or other surface layer from an animal and particularly from fish

The present invention further provides a skinning apparatus which can remove skm or other surface layer from an animal while removing little or no edible meat with the skin The present mvention also provides a method of removing skm or other surface layer from an animal

Accordmg to one aspect of the present mvention, a skinning apparatus for removmg a surface layer from an animal includes a paddle wheel having a plurality of flexible paddles rotatable about a rotational axis Each paddle has a radially outer end for contacting a surface of an animal, with the outer ends of the paddles arranged at a plurality of angles with respect to the rotational axis The apparatus may also include a drive mechanism which can rotate the paddle wheel about the rotational axis

In preferred embodiments, each paddle extends over less than the entire length of the paddle wheel, and the paddles overlap each other in the axial direction of the paddle wheel The paddles may have a variety of shapes In preferred embodiments, each paddle includes a plurality of fingers which are capable of bending mdependently of each other when contactmg the surface of an animal Accordmg to another aspect of the present mvention, a paddle wheel for use m removmg a surface layer from an animal mcludes a hub havmg a rotational axis, and a plurality of flexible paddles extendmg outwards from the rotational axis of the hub, with each paddle havmg a radially outer end for contactmg a surface of an animal The outer ends of the paddles are preferably arranged at a plurality of angles with respect to the rotational axis Accordmg to yet another aspect of the present mvention, a method of removmg a surface layer from an animal mcludes contactmg an animal with a rotating paddle wheel including a plurality of flexible paddles havmg radially outer ends arranged in a plurality of angles with respect to a rotational axis of the paddle wheel In preferred embodiments, the animal is a fish, and relative movement of the fish and the paddle wheel in the lengthwise direction of the fish is produced while the fish contacts the paddle wheel The paddle wheel and the fish may be pressed agamst each other with a force which is controlled so as to be substantially uniform over the length of the fish

A skinning apparatus and method accordmg to the present mvention are particularly suited for use with fish havmg an inedible skm, but they can also be used with fish having an edible skm, which it may be desired to remove for cosmetic reasons or improved taste, for example The apparatus and method can also be used to remove skm or other surface layer from animals other than fish While the apparatus and method are mtended primarily for use m the removal of skm, dependmg on the type or condition of the animal, they may be effectively used to remove other portions of an animal's exterior, such as fish scales

Bnef Description of the Drawings Figure 1 is a side elevation of an embodiment of a fish skinning apparatus according to the present mvention

Figure 2 is another side elevation of the embodiment of Figure 1 with a portion of the frame removed for clarity

Figure 3 is a front elevation of the embodiment of Figure 1 as viewed from line 3-3 m Figure 1 Figure 4 is an enlarged side elevation of one of the paddle wheels of the embodiment of Figure 1

Figure 5 is a cross-sectional view taken along lme 5-5 of Figure 4 Figure 6 is a cross-sectional view taken along lme 6-6 of Figure 4

Figure 7 is an exploded isometric view of one of the paddles of the paddle wheel of Figure 4 Figure 8 is a plan view of one of the paddles of the paddle wheel of Figure 4 Figure 9 is a side view of a fish holder capable of being used m the embodiment of Figure 1

Figure 10 is a front view of the fish holder of Figure 9 Figure 11 is a cross-sectional view taken along line 11-11 of Figure 9 Figure 12 is a cross-sectional view taken along lme 12-12 of Figure 9 Figure 13 is a cross-sectional view taken along lme 13-13 of Figure 9 Figure 14 is a cross-sectional view taken along lme 14-14 of Figure 10

Figure 15 is a schematic view of a fish be g held by the fish holder of Figure 9 Figure 16 is a block diagram of a control system for the embodiment of Figure 1

Figures 17-20 are side elevations of a portion of the embodiment of Figure 1 at different stages during the skinning of a fish Figure 21 is a schematic side elevation of a portion of an embodiment of a fish skinning apparatus accordmg to the present mvention which can skm both sides of a fish m a smgle pass

Figure 22 is a schematic illustration showmg all the paddles of the paddle wheel of Figure 4 as they would appear if stacked atop each other m parallel planes

Figure 23 is a cross-sectional view of a portion of another embodiment of a paddle wheel which can be used m the present mvention

Description of Preferred Embodiments

Figures 1-3 are elevations of an embodiment of a skinning apparatus accordmg to the present mvention bemg used to process a fish 20 The illustrated fish 20 is a tuna, but as stated above, the present mvention can be used to process other varieties offish or other types of animals Of these figures, Figure 1 is side elevation of the skinning apparatus, Figure 2 is another side elevation with a portion of the structure removed for claπty, and Figure 3 is a front elevation as seen from the right m Figure 1 This embodiment mcludes one or more rotatable paddle wheels 100 each equipped with paddles 130 for removing skin from a fish 20 by contact with the surface of the fish 20 The apparatus may also mclude a frame 10 which can support the paddle wheels 100 and a fish 20 bemg processed In the present embodiment, the skmnmg apparatus mcludes two paddle wheels 100 disposed side by side at a smgle location so that two fish can be skinned simultaneously, but the number of paddle wheels 100 and their arrangement with respect to each other or with respect to other equipment is not restricted

The skinning apparatus may operate independently of other equipment, or it may be incorporated mto a lme along which fish are transported, either automatically or manually, from location to location for various processmg steps In the present embodiment, a fish 20 can be transported to the skmnmg apparatus along rails 30 which connect the skinning apparatus with other unillustrated equipment As shown in Figure 2, withm the skinning apparatus, there is a gap 31 between two rails 30, and in this gap 31, a movable support 43 for supporting a fish durmg skmnmg can be received The illustrated support 43 has a short rail on each of its widthwise sides which can be aligned with rails 30 so that a fish can be transported smoothly between the rails 30 and the support 43

A fish can be moved along the rails 30 by any convenient transport mechanism, such as by chains, belts, pistons which push the fish along the rails 30, gravity, or rollers, for example

Figure 4 is a side elevation of one of the paddle wheels 100 of Figure 3, and Figures 5 and 6 are cross- sectional views of the paddle wheel 100 taken along lmes 5-5 and 6-6, respectively, of Figure 4 The other paddle wheel 100 may have a similar structure

The illustrated paddle wheel 100 includes a rotatmg hub 110 which is supported for rotation about a longitudinal axis thereof, and a plurality of paddle holders 120 secured to the hub 110 for rotation therewith Each paddle holder 120 supports one or more paddles 130 for contacting the surface of a fish 20 to remove skm from the surface To give the paddle wheel 100 greater strength, it may include one or more annular runs 122 which are concentπc with the hub 110 and connect the paddle holders 120 with each other

The paddle wheel 100 may be rotated about its rotational axis by any desired mechanism The hub 110 of the illustrated paddle wheel 100 is mounted on a rotatmg shaft 111 m a manner such that the hub 110 rotates together with the shaft 111 but is capable of translating m the lengthwise direction of the shaft 111 while rotatmg to enable the paddle wheel 100 to automatically adjust its position with respect to a fish 20 bemg skinned For example, the hub 110 may be connected to the shaft 111 by a key and keyway which prevent relative rotation of the hub 110 and the shaft 111 while permitting translation of the hub 110 m a lengthwise direction of the shaft 111 Stoppers 112 m the form of collars or similar members may be mounted on the shaft 111 to limit the range of lengthwise movement of the hub 110 along the shaft 111 The shaft 111 is rotatably supported by bearings on opposite widthwise sides of the paddle wheel 100 and is rotated about its axis by a motor 143 through a drive belt 146 passmg around a pulley 144 mounted on the motor 143 and a pulley 145 mounted on the shaft 111 The shaft 111 may mstead be rotated by any other suitable mechanism, such as by a cham drive, a gear tram, rollers engagmg the shaft 111, or a direct connection between the motor 143 and the shaft 111 Instead of the hub 110 bemg rotated by the shaft 111, the shaft 111 may be stationary, the hub 110 may be freely rotatable on the shaft 111, and the hub 110 may be rotated on the shaft 111 by the motor 143 in a manner similar to that used m the present embodiment to rotate the shaft 111

The number of paddles 130 on each paddle wheel 100 is not restricted In the present embodiment, the paddles 130 are evenly spaced around the circumference of the paddle wheel 100 to reduce rotational vibrations and to provide greater uniformity of pressure of the paddle wheel 100 against the fish 20 being skinned, but the spacmg between the paddles 130 can be nonuniform The illustrated paddle wheel 100 has paddles 130 disposed at twelve locations around its circumference, but a different number of locations may be employed The circumferential spacmg between paddles 130 is preferably large enough that adjoining paddles 130 in the circumferential direction of the paddle wheel 100 do not contact each other when deformed during contact between the paddles 130 and a fish

Smce a fish has a curved transverse cross section, the angle of the surface of the fish with respect to the rotational axis of the paddle wheel 100 will vary around the girth of the fish Therefore, the paddles 130 are preferably arranged so that their radially outer edges which contact a fish are at a variety of angles to the axis of rotation of the paddle wheel 100 In the present embodiment, the radially outer edges of the paddles 130 are disposed at three different angles to the axis of rotation Paddles 130 in a first group (the center paddles extending vertically in Figure 5) each have a radially outer edge which is substantially parallel to the axis of rotation Paddles 130 in a second group (including the sloped paddles 130 in Figure 6) each have a radially outer edge which is at a first nonzero angle (such as approximately 25 degrees in the drawing) with respect to the axis of rotation Paddles 130 m a thud group (mcludmg the slopmg paddles 130 m Figure 5) each have a radially outer edge which is at a second nonzero angle (such as approximately 52 5 degrees m the drawing) with respect to the axis of rotation which is larger than the first angle The paddles 130 in the first group havmg a radially outer edge which is substantially parallel to the axis of rotation may be mounted on a paddle holder 120 by themselves, or they may be mounted on a paddle holder 120 together with other paddles 130, such as shown m Figure 5, m which one paddle 130 havmg a radial outer edge which is substantially parallel to the rotational axis is mounted on the same paddle holder 120 as two paddles 130 each havmg a radially outer edge which is sloped with respect to the rotational axis The paddles 130 havmg a radially outer edge which is sloped with respect to the rotational axis are preferably mounted on a paddle holder 120 m pans of two paddles 130 of equal and opposite slope so that lateral forces acting on the slopmg paddles 130 m a duection havmg a component parallel to the rotational axis will tend to center the paddle wheel 100 with respect to a fish bemg processed Furthermore, all of the slopmg paddles 130 are preferably symmetrically disposed with respect to a common centerlme plane 113 which is perpendicular to the rotational axis of the shaft 111 and which is at a fixed location with respect to the hub 110 but which moves with the hub 110 as the paddle wheel 100 translates in the axial dnection of the shaft 111 In Figure 5 , the two paddles 130 havmg radially outer edges parallel to the rotational axis of the shaft 111 are shown as being off-center with respect to the centerlme plane 113 so that each of these paddles 130 can overlap one of the slopmg paddles in the axial dnection of the shaft 111, but dependmg upon then: width measured m the axial direction of the shaft 111, one or both of these paddles 130 may mstead be centered with respect to the centerlme plane 113

In the present embodiment, each of the paddles 130 compπses one or more flexible fingers 133 each havmg a radially outer edge which is mtended to contact the skm of a fish 20 Each finger 133 may be individually mounted on one of the paddle holders 120 without bemg dnectly connected to any of the other fingers 133, but in the present embodiment, m order to reduce the number of components which need to be assembled to form the paddle wheel 100, each finger 133 is jomed to a plurality of the other fingers 133 to form a unit havmg three fingers 133 , for example, although a different number of fingers 133 may be j oined to each other As shown m Figures 7 and 8, which are respectively an exploded isometric view and a plan view of one of the paddles 130, each paddle 130 m the present embodiment compπses a thin plate 131 in which slits 132 have been cut over a portion of the length of the plate 131 to define the individual fingers 133 The plate 131 is not restricted to any particular mateπal For example, both plastics and metals can be employed, and different materials can be employed for different portions of the plate 131 For ease of manufacture, the illustrated plate 131 is flat m an unstressed state, but it may mstead have a curved or otherwise nonplanar unstressed shape In the present embodiment, the plate 131 is made of a plastic, such as nylon, with a thickness of 0 05 inches, while reinforcing members, such as stπps 134 made of a harder mateπal, such as metal or a harder plastic, are secured to the radially outer ends of the fingers 133 to protect them agamst abrasion, splitting, or other damage when they contact a fish 20 An example of a suitable material for the remforcmg strips 134 is a strip of stainless spring steel about 0 010 mches thick The edge of a thin remforcmg strip 134 which contacts the surface of a fish is able to pierce the skin and remammg subdermal connective tissue without damagmg the underlymg meat layer of the fish The remforcmg strips 134 may also be better able to penetrate the surface of a fish than the softer material of which the plates 131 are made The illustrated remforcmg strips 134 are secured to the plate 131 with rivets, but any other desired attachment method can be employed If desned, the remforcmg stπps 134 may extend beyond the radially outer ends of the plate 131, as shown m Figure 8, so that the plate 131 will not contact the surface of a fish The paddles 130 may be secured to the paddle holders 120 in any desired manner It may be advantageous for the paddles 130 to be detachably mounted on the paddle holders 120 to allow easy replacement In the present embodiment, each paddle 130 has a pair of holes 136 which can be aligned with either a first or a second pan of holes 121 m each paddle holder 120 to enable the position of the paddle 130 to be adjusted m the widthwise dnection of the paddle 130 so that different paddles 130, even though at the same angle with respect to the rotatmg shaft 111 , can contact different portions of a fish 20 However, instead of the position of a paddle 130 bemg adjustable, the paddle 130 can be made wide enough to cover the entire range in the widthwise direction of the paddle 130 over which it is desned for the paddles 130 to contact the body of a fish 20 In the present embodiment, each plate 131 is clamped between one of the paddle holders 120 and a securing plate 137 which is secured to the paddle holder 120 by nuts and bolts or m any other convenient manner In the present embodiment, because each paddle 130 comprises a rectangular plate 131 and the paddles

130 are at a vaπety of angles with respect to the rotational axis of the paddle wheel 100, each paddle 130 extends over a region measured parallel to the rotational axis which is less than the enure width of the paddle wheel 100 However, it is also possible for a smgle paddle havmg a radially outer end with a slope that varies over its width to extend over the entire width of the paddle wheel 100 The radially outer edges of the fingers 133 may have a variety of shapes In the present embodiment, to simplify manufacture, the radially outer edges of all of the fingers 133 of a paddle 130 are aligned with each other along a straight lme which is perpendicular to the lengthwise direction of the fingers 133 However, the radially outer edges may mstead be curved or otherwise nonperpendicular to the lengthwise duection of the fingers as viewed m plan Also to simplify manufacture, all of the fingers 133 on a single paddle 130 have the same rectangular shape and the same length, but different fingers 133 may differ m shape from one another and have different lengths

The surface of a paddle 130 which contacts the surface of a fish 20 may be smooth, or it may be serrated, roughened, or otherwise textured to enable the paddle 130 to more easily remove tough skm When the paddles 130 are used for skmnmg tuna, a smooth contact surface on the paddles 130 has been found to be suitable For example, m the present embodiment, each of the remforcmg stπps 134 has a smooth, i e , untextured surface which contacts a fish It may be desnable for one or both of the widthwise edges 134a of the remforcmg stπps 134 to be rounded to prevent them from diggmg too deeply mto the meat of a fish 20

The individual fingers 133 of the paddle 130 are not restricted to a particular width Fmgers havmg a narrow width can more easily follow a curved contour of the body of a fish, but if the fingers are too narrow, they may leave marks in the meat of the fish, and extremely narrow fingers may be difficult to manufacture, particularly when each finger is equipped with a reinforcing strip 134 on its radially outer end On the other hand, if a finger is extremely broad, it may have trouble conforming to a curved contour of a fish, with the result that some regions of the fish may be left unskinned The width of the fingers 133 may vary among the various paddles 130 or among the fingers 133 on a smgle paddle 130, but m the present embodiment, to simplify manufacture, all of the fingers 133 on all of the paddles 130 have the same width When the paddles 130 are used for skinning tuna, a typical range for the width of the fingers 133 can be from approximately 1/4 inch to approximately 2 mches, and preferably m the range of approximately 3/4 to approximately 1 25 inches

Each paddle 130 is preferably sufficiently flexible that it can bend from its initial shape upon contactmg the surface of a fish so as to enable the radially outer edge of the paddle 130 to follow the contour of the fish for some distance along the length of the fish If the paddles 130 are rigid so that then radially outer ends move along an arc of constant radius, they will tend to gouge meat from the fish, but if they are flexible so that their radially outer ends can follow the contour of the fish, the paddles 130 can perform a scrapmg, rubbing, or wiping action, for example, rather than a gougmg action to efficiently remove skin from the fish while removmg a minimum of the underlying meat

The meat of the fish m some regions is more susceptible to tearmg than in other regions For example, with tuna, the meat m the dorsal and ventral regions is more likely than the meat m the pectoral regions to be damaged as the skm is removed Therefore, in the present embodiment, the bendmg stiffness of the fingers 133 may vary among the paddles so that fingers which contact skm regions covermg meat that is more susceptible to damage are less stiff in bendmg than fingers which contact the regions with less sensitive meat The stiffness of a finger 133 depends upon its cross-sectional dimensions, its length, and the mateπal of which it is made Any of these parameters can be varied to adjust the stiffness In the present embodiment, m order to enable all of the paddles 130 to be formed from plates 131 havmg the same width and thickness so as to simplify manufacture, the stiffness of the fingers 133 is varied by varying their length The fingers 133 on the paddles 130 at the greatest angle to the rotational axis of the paddle wheel 100 (the slopmg paddles 130 in Figure 5) are the longest and most flexible, smce these fingers 133 contact the dorsal and ventral regions of a fish The fingers 133 on the paddles 130 at a smaller angle to the rotational axis of the paddle wheel 100 (the slopmg paddles 130 m Figure 6) are shorter and less flexible than the slopmg paddles 130 of Figure 5 The fingers 133 on the paddles 130 havmg a radially outer edge parallel to the rotational axis of the paddle wheel 100 are also shorter and less flexible, smce these fingers 133 contact the pectoral regions of a fish where the meat underlymg the skm is less susceptible to damage during skmnmg For example, in the present embodiment, the length L of the paddles 130 measured from where they protrude from one of the paddle holders 120 to the radially outer edges of the paddles 130 is 2 mches for the nonslopmg center paddles 130 of Figure 5, 2 5 inches for the slopmg paddles 130 of Figure 5, 2 25 ches for the slopmg paddles 130 in the upper half of Figure 6, and 2 mches for the sloping paddles 130 in the lower half of Figure 6 The shorter, less flexible fingers, because then outer edge is closer to the axis of rotation, move at a lower speed than the longer, more flexible fingers This tends to make for a more balanced distribution of force agamst the skm and more uniform skmnmg

The paddle holders 120 can have any structure which enables them to support one or more paddles 130 at desned angles with respect to the rotational axis of the paddle wheel 100 In the present embodiment, each paddle holder 120 is formed from a flat plate havmg a central portion 120a extendmg parallel to the rotational axis of the paddle wheel 100 and two arms 120b extending symmetrically from the central portion at an angle with respect to the rotational axis The central portion 120a can be attached to the hub 110 in any convenient manner, such as by weldmg, bonding, bolting, etc The plane of each of the illustrated paddle holders 120 is aligned with a radius of the hub 110, and the plane of each paddle 130 extends parallel to a radius of the hub 110, but the paddle holders 120 and the paddles 130 may be at any angle with respect to the hub 110

The paddle holders 120 are arranged such that a paddle holder 120 like one of those shown m Figure 5 supporting three paddles 130 alternates in the cncumferential direction of the paddle wheel 100 with a paddle holder 120 like one of those shown in Figure 6 supporting two paddles 130 Such an arrangement of the paddle holders 120 provides the paddle wheel 100 with a good rotational balance, but other aπangements of the paddle holders 120 may also be employed

Preferably each paddle 130 overlaps another of the paddles 130, whether on the same or a different paddle holder 120, m the axial dnection of the paddle wheel 100 so as not to leave unskmned portions offish m the regions lymg between where different paddles 130 contact the fish For example, m Figure 5, each of the slopmg paddles 130 on one of the arms 120b of a paddle holder 120 overlaps another of the slopmg paddles 130 and one or both of the middle nonslopmg paddles 130 on the central portion 120a of a paddle holder 120 in the axial dnection of the shaft 111, and each of the paddles 130 of Figure 6 overlaps another of the paddles 130 of Figure 6 and one or more of the paddles 130 of Figure 5 m the axial dnection of the shaft 111 The overlap is preferably such that different paddles 130 do not contact each other, m either a deformed or an undeformed state, so that each paddle 130 can deform when contactmg the surface of a fish without interference from another paddle 130 The overlap m the axial direction between different paddles 130 is best shown in Figure 22, which is a schematic illustration showmg all the paddles 130 as they would appear if stacked atop each other m parallel planes The outer surface of a body defined by the paths of movement of the radially outer ends of the paddles 130 as they rotate about the rotational axis of the paddle wheel 100 is generally hourglass shaped due to the radially outer ends of the paddles 130 bemg at vaπous angles with respect to the rotational axis and due to the distance of the radially outer ends from the rotational axis varying along the length of the paddle wheel 100 It has been found that such an hourglass shape is particularly effective for skmnmg a tuna because the shape is able to accommodate fish of different sizes and shapes When the paddles 130 contact the surface of a fish, the bendmg of the paddles 130 will mcrease the separation between a slopmg paddle on one arm 120b of a paddle holder 120 and the other sloping paddle on the other arm 120b of the same paddle holder 120 The amount of overlap between paddles 130 m the axial dnection of the shaft 111 is preferably selected so as to accommodate this mcrease in separation such that the overlap remains when the paddles 130 are contactmg a fish and are bent from then initial shapes shown m Figures 5 and 6 The paddles 130 on the illustrated paddle wheel 100 can contact up to roughly one-half the girth of a fish at a time over a region extendmg from the dorsal region to the ventral region Therefore, a fish can be skinned around substantially its entne girth by two passes of the fish past a smgle paddle wheel 100 However, the paddles 130 of a smgle paddle wheel 100 may contact a fish over a different percent of the girth In general, if the paddles 130 on a smgle paddle wheel 100 extend around 1/n of the girth of a fish, the fish may be skinned around its entne girth by n or more passes of the fish past the paddle wheel 100 As another alternative, the fish may be rotated about its longitudmal axis as it moves past the paddle wheel 100 so that the paddle wheel 100 can contact the entne girth of the fish m a smgle pass regardless of the percent of the girth of the fish over which the paddles 130 extend A fish is not restπcted to any particular orientation duπng skmnmg In the present embodiment, a fish is suspended from above and hangs substantially vertically during skinning, but the fish may be at any other angle with respect to the vertical For example, a fish may be oriented horizontally on a conveyor belt or other type of conveyor duπng skmnmg and move horizontally past a paddle wheel 100 disposed above, below, or beside the fish The speed of rotation of the paddle wheel 100 can be adjusted to obtain a circumferential speed of the radially outer ends of the paddles 130 so as to remove a desned amount of skin from a fish A suitable speed can depend on vaπous factors, such as the dimensions of the paddle wheel 100, the hardness of the remforcmg stπps 134, the bendmg stiffness of the paddles 130, the character and condition of the fish, the pressure of the paddles 130 agamst the fish, and the speed of movement of the fish past the paddle wheel 100 An example of a suitable rotatable speed when the paddles 130 have the above-descπbed dimensions and are made of the above-descπbed materials is one which produces a tip speed m the cncumferential direction of the paddle wheel m the range of approximately 5 5 to approximately 10 5 feet per second However, any speed which results m the removal of a desned amount of skm can be employed A fish may be supported m any manner duπng skmnmg, such as by a machme or by the hand of the user, if it is possible for the user to do so safely In the present embodiment, a fish 20 is supported by a holdmg device which will be referred to as a fish holder 50, an example of which is illustrated in Figures 9-15 A fish may be grasped by either its head or its tail, but with many fish, the head can be more easily and reliably grasped than the tail smce the head region is often sturdier than the tail region The illustrated fish holder 50 mcludes a frame 51 at its upper end (the πght end m Figure 9) on which are mounted rollers 52 which can roll along the rails 30 of Figure 1 A pan of opposmg arms 53 extend from the frame 51 and define a space between them mto which the head of a fish can be inserted At its end remote from the frame 51, each arm 53 mcludes one or more engaging members, such as projections 54 which can be inserted mto or otherwise engage the body of a fish The illustrated projections 54 comprise triangular prongs which are punched from a plate and bent inwards towards the opposmg arm 53, but the engaging members may have a variety of other shapes For example, they may be in the form of pms, hooks, teeth, clamps, etc Between the two arms 53 is disposed a cup 55 havmg a conical interior which can fit over the head of a fish The cup 55 is secured to a rod 56 which is shdably mounted on the frame 51 for movement m the lengthwise direction of the rod 56 The end of the rod 56 remote from the cup 55 is equipped with a flange 57 which prevents the rod 56 from becoming detached from the frame 51 The cup 55 is urged away from the frame 51 and towards the head of a fish by a biasmg member, such as a helical sprmg 58 surrounding the rod 56 between the cup 55 and the frame 51 The arms 53 are preferably capable of bemg urged away from each other to enable the fish holder 50 to accommodate fish of different sizes For example, m this embodiment, each arm 53 is rigidly secured to the frame 51 but is sufficiently flexible to be easily bent away from the opposmg arm 53, with the resilience of the arms 53 urgmg them towards each other Alternatively, the arms 53 may be pivotably connected to the frame 51

Figure 15 illustrates the fish holder 50 (shown m phantom) as it would typically appear when engagmg the head of a fish 20 The projections 54 on the arms 53 are made to pierce the surface of the fish 20 m a suitable location (such as through the gill plates) on the pectoral regions of the fish 20, and the cup 55 is pressed agamst the front of the head of the fish 20 by the compression sprmg 58 The cup 55 prevents the fish 20 from pivoting about the projections 54, and it also urges the head of the fish 20 m a direction tendmg to press the projections 54 deeper mto the fish 20

Some fish have a grain to then meat, and the skm of such fish can be removed more effectively if the paddles 130 move with the gram while contactmg the fish because movement with the gram will cause less meat to be removed along with the skm In the case of tuna, the grain typically runs from the head to the tail, so the paddle wheels 100 preferably rotate in a dnection such that the tips of the paddles 130 move in this direction when contactmg the fish

In order to remove skm from the entne length of a fish, it is generally desirable to produce relative movement of the fish with respect to the rotational axis of the paddle wheel 100 in a lengthwise direction of the fish while the paddle wheel 100 is contactmg the fish The relative movement can be produced by moving the fish and/or the paddle wheel 100 In the present embodiment, the relative movement is produced by raismg and lowermg the fish m its lengthwise direction while mamtammg the rotational axis of the paddle wheel 100 stationary with respect to the lengthwise dnection of the fish As shown m Figure 3, a fish can be suspended from a horizontal beam 42 which is secured to a carriage 40 associated with each paddle wheel 100 which is shdably mounted for vertical movement on a vertical column of the frame 10 Each carriage 40 can be raised and lowered by a suitable drive mechanism, which m the present embodiment comprises a pneumatic cylmder 41 secured to a side of the frame 10, but a variety of other types of drive mechanisms may be used, such as a hydraulic cylinder or an electric motor, mounted either on the frame 10 or the carnage 40

The speed with which the fish 20 is moved past a paddle wheel 100 while contactmg the paddle wheel 100 can be selected m accordance with factors such as the rotational speed of the paddle wheel 100, the force with which the paddle wheel 100 is pressed agamst the fish 20, the number of blades on the paddle wheel 100, and the amount of skm which it is desired to remove from the fish 20 m a smgle pass

A fish can be m various states when bemg skinned usmg the apparatus of the present mvention, ranging from a totally frozen state to a totally thawed state Many fish, such as tuna, are typically processed m an entnely or substantially frozen state, although durmg skmnmg the surface layer of the fish may be slightly thawed to make the skm easier to remove A skmnmg apparatus accordmg to the present mvention may be used on a fish which has not been otherwise processed, but it may perform skmnmg more effectively if certain portions of the fish, such as some or all of the scales and fins, have been previously removed

In the present embodiment, the fish and the paddle wheel 100 are movable relative to each other in a dnection transverse to the rotational axis of the paddle wheel 100, 1 e , m a dnection towards and away from each other, so that the paddles 130 can follow the contour of the fish as the fish is moved in its lengthwise dnection past the paddle wheel 100 Such relative movement can be produced by moving the fish and/or the paddle wheel 100 In the present embodiment, as shown m Figure 2, each paddle wheel 100 is mounted on a carnage 140 which is supported by the frame 10 for horizontal movement towards and away from a fish 20 bemg processed Each of the illustrated carriages 140 is shdably mounted on horizontal rails 141 and can be moved along the rails 141 by a pneumatic cylmder 142 or other dπve mechanism, such as a hydraulic cylmder or an electric motor The pressure supplied to the pneumatic cylmder 142 can be controlled by a pressure regulator, for example, so that each paddle wheel 100 is pressed agamst a fish with a controlled pressure, which may be held constant or may be vaπed over the length of the fish The pressure is preferably adjustable to enable the force pressmg the paddle wheel 100 agamst the fish to be set m accordance with the type or condition of the fish and the amount of skm which it is desired to remove

The pressure exerted by the paddles 130 agamst the surface of a fish is preferably such as to remove the desned amount of skin from the fish while removing a minimum of meat If the surface of a fish is m a thawed state m which the subdermal layer of connective tissue attaching the skin to the meat has been softened, the skin may be removed with the paddles 130 exerting very little pressure on the surface of the fish and performing essentially a wiping action along the surface of the fish When the subdermal layer is not so soft, the force exerted by the paddles 130 on the fish may be higher so that the paddles 130 exert a scraping or rubbing action on the surface of the fish so as to remove the desned amount of skm In the present embodiment, a fish 20 bemg skinned is held broadside to a paddle wheel 100, l e , with one of its pectoral regions facing the paddle wheel 100 and its ventral and dorsal regions facmg m a dnection parallel to the rotational axis of the paddle wheel 100 However, the orientation of the fish 20 may mstead be such that either the ventral or dorsal region faces the axis of the paddle wheel 100 Whatever the orientation of the fish 20, a smgle paddle wheel 100 will generally be able to contact only one side of the fish in a single pass of the fish past the paddle wheel 100, unless the fish is rotated about its lengthwise dnection as it moves past the paddle wheel 100 In order to enable the paddle wheel 100 to skm both sides of a fish, the skinning apparatus may be equipped with a mechanism for reversmg the oπentation of the fish at the end of a pass so that either side of the fish can be made to face the paddle wheel 100 In the present embodiment, an electric motor 44, shown m Figure 2, is supported by the outer end of each beam 42 and is connected to the correspondmg support 43 by a shaft 45 The motor 44 can rotate the support 43 through the shaft 45 about a vertical axis to adjust which side of the fish 20 faces the paddle wheel 100 Any other convenient mechanism may also be used for rotatmg the fish 20 about the vertical axis, such as a pneumatic cylmder which can rotate a lever connected to the shaft 45

The movement of the fish 20 within the skinning apparatus and the operation of the paddle wheels 100 may be coordmated manually by a human operator, or they may be coordinated by an automatic control system without the need for human intervention Figure 16 schematically illustrates an example of a control system which can be employed in the present mvention The control system mcludes an automatic control unit 60, such as a programmable controller or a microcomputer, which provides control signals to an elevating mechanism 61 (such as one of pneumatic cylmders 41) for raismg and lowermg one of the fish holders 50, a rotatmg mechanism 62 (such as one of the electπc motors 44) for rotatmg the fish 20 about a vertical axis, a translating mechamsm 63 (such as one of pneumatic cylmders 142) for moving one of the paddle wheels 100 towards and away from the fish 20, and a paddle wheel rotatmg mechanism 64 (such as one of the electric motors 143) for rotatmg the paddle wheel 100 about its rotational axis The control unit 60 may receive mput signals from various sensors or other mput devices, such as limit switches or proximity sensors, for sensmg the position of the fish 20 or the status of vaπous components of the skmnmg apparatus In the illustrated control system, the control unit 60 may receive an mput signal from a light sensmg device 71, to be descπbed below

An example of a method of processmg a tuna fish, mcludmg an example of skmnmg the fish usmg a skmnmg apparatus accordmg to the present mvention, is as follows The tail fin, thoracic fin, and pectoral fins of a fish m an entnely frozen state may first be removed by knives, saws, or other cutting instruments The dorsal and ventral fins of the fish may be removed at the same time as the other fins, but it is frequently easier to remove these fins after skmnmg has taken place The definned fish is then typically subjected to scaling usmg any suitable equipment, such as the scaling device described in WO 98/09530 The scaled fish may then be dipped in a hot water bath m order to soften the skm and to dissolve the subdermal layer of connective tissue that holds the skm to the underlying flesh of the fish The temperature of the hot water bath is preferably between about 160°F and about 180°F to dissolve the connective tissue The immersion time will depend primarily on where the fish was caught

Fish size and condition may have a secondary effect on immersion tune The fish is preferably immersed in the hot water bath long enough for the desned softenmg to occur but not long enough to thaw the inner portion of the fish The immersion tune may vary from around three mmutes to around eight mmutes dependmg mostly on where the fish was caught Except for the outer portion of the flesh adjacent the skin, the fish body is preferably mamtamed hard frozen

The fish can then be introduced mto a skmnmg apparatus accordmg to the present mvention For example, a fish holder 50 supporting the fish 20 to be skinned can be first transported along the rails 30 until it rests on one of the supports 43, as shown m Figure 1 The carnage 40 on which the horizontal beam 42 correspondmg to the support 43 is mounted is then lowered by the pneumatic cylinder 41 to a predetermined position, as shown m Figure 17 At this time, the correspondmg paddle wheel 100 may be mamtamed m a retracted position on the left m the figure so as not to mterfere with the lowermg of the fish 20 Then, as shown in Figure 18, the carnage 140 on which the paddle wheel 100 is mounted is moved towards the fish 20 (to the right m Figure 18), and the paddle wheel 100, if not already rotating, is rotated about its axis m the clockwise dnection m Figure 18 After the paddle wheel 100 has contacted the fish 20, the carnage 40 is raised, as shown in Figure 18, so that the region of the fish 20 bemg contacted by the paddle wheel 100 moves down the length of the fish 20 towards the tail The pneumatic cylmder 142 preferably urges the paddle wheel 100 against the fish 20 with a controlled force so that the paddle wheel 100 can remam m contact with the fish 20 as the profile of the fish 20 vanes As the paddles 130 of the rotatmg paddle wheel 100 move along the fish 20 m contact with it, they remove skm from the fish 20, the skm falling downwards to the bottom of the apparatus from where it can be removed When the fish 20 has been raised to a height sufficient that the entne length which it is desned to skm on one side of the fish 20 has been skinned, the paddle wheel 100 is moved away from the fish 20, e g , to the πght in Figure 19 The fish 20 is then rotated by 180° about a vertical axis so that the unskinned side of the fish 20 now faces the paddle wheel 100, and the fish 20 is lowered (either before or after being rotated) to the same predetermined height as in Figure 17 At this time, the fish 20 appears as shown in Figure 20 The above-descπbed process of movmg the paddle wheel 100 towards the fish 20 and raismg the fish 20 while contactmg the rotatmg paddle wheel 100 agamst the fish 20 is then repeated to skm the second side of the fish 20 When skmnmg of the second side has been completed, the fish 20 is raised back to the position shown m Figure 2 m which the movable support 43 is aligned with the rails 30 The fish 20 can then be transported along the rails 30 to a location for the next stage in processmg After the completion of skmnmg, the anterior and posterior dorsal fins and ventral fins of the skinned fish can be removed by pulling, scoopmg, cutting, or other convenient method The skinned fish is now ready to be subjected to subsequent processmg steps, such as removal of the head and entrails, cutting of the fish body into steaks or other shapes, and cookmg of various portions of the fish Examples of such subsequent processmg methods are described m WO 98/09530 The distance by which the fish 20 is raised from its lowest position shown m Figure 17 m which the paddle wheel 100 is moved towards the fish 20 and the position shown in Figure 19 in which the paddle wheel 100 is moved away from the fish 20 can be the same for each fish, regardless of the length of the fish Alternatively, to decrease the tune required to process each fish by decreasmg the amount of up and down movement of the fish, the distance can be vaπed based on the length of the fish being processed, with the distance bemg less for a short fish than for a long fish In the present embodiment, the control unit 60 can control the pneumatic cylmder 142 for movmg the paddle wheel 100 back and forth and the pneumatic cylinder 41 for raising and lowermg the carriage 40 based on the length of the fish bemg skinned As shown in Figure 3, a light emitting device 70 including one or more conventional light emitters (LED's, lasers, infrared devices, etc ) and a light sensmg device 71 including one or more light sensitive elements are mounted opposite and m alignment with each other in any suitable locations, such as on opposite sides of the frame 10, such that when a fish 20 is lowered towards one of the paddle wheels 100, the fish 20 will pass between the two devices 70 and 71 The illustrated light ermttmg device 70 emits a horizontally elongated light curtam, but the shape of the emitted light is not restπcted, and the light may have a different shape, such as that of a narrow beam The light emitting device 70 is preferably positioned such that when the fish holder 50 is in its highest position shown in Figure 3, the lower end of a fish 20 will be above the emitted light As the fish 20 is lowered from the position shown m Figure 3, the tail of the fish 20 will eventually cross the light curtain and partially block the light sensed by the light sensing device 71 The control unit 60 can determine when the fish 20 has crossed the light curtain by a variation m the output signal from the light sensmg device 71 The distance traveled by the fish 20 between the position shown in Figure 3 and the position of the fish 20 when its tail crosses the light curtam can be determined by actual measurement, such as by measuπng the position of the carnage 40 with respect to a reference position with an encoder or other suitable position measuring device, or the distance can be calculated based on the speed of travel of the carriage 40 and the time which has elapsed from the portion shown m Figure 3 until the tail of the fish 20 crosses the light curtain The distance by which the fish 20 is lowered until its tail crosses the light curtam is mdicative of the length of the fish 20, the distance bemg longer for a short fish than for a long fish Based on the determined distance, the amount by which the fish is raised between the positions shown m Figure 18 and Figure 19 can be vaπed m accordance with the length of the fish, with the amount bemg smaller for a short fish than for a long fish

Instead of the control unit 60 calculating a distance m the above manner and controlling the vertical movement of a fish based on the calculated distance, another possible control method is for the control unit 60 to sense, based on signals from the light sensmg device 71, when the fish 20 has been raised from the position shown in Figure 18 to a height at which the tail of the fish 20 is raised above the light curtam and then to retract the paddle wheel 100 at that pomt in tune

Figure 21 illustrates a variation of the embodiment of Figure 1 in which two paddle wheels 100 are disposed at different heights and face each other on opposite sides of the vertical path of movement of a fish 20 bemg skinned Each paddle wheel 100 may be identical m structure and operation to the paddle wheels 100 of the embodiment of Figure 1 As a fish 20 is passed vertically between the two paddle wheels 100, each paddle wheel 100 can remove skm from one side of the fish 20, so that both sides of the fish 20 can be skinned m a smgle pass rather than in two passes as m the embodiment of Figure 1 , thereby decreasmg the time requned for skmnmg The two paddle wheels 100 are disposed at different heights to prevent them from mterfermg with each other, but they may instead be disposed at the same height as each other if mterference will not occur The two paddle wheels 100 are shown as havmg then rotational axes parallel to each other, but the axes may be at a different angle to each other For example, the two axes may be at 90° to one another, and the fish 20 may be rotated by 90° after it has passed by the lower paddle wheel 100 and before it contacts the upper paddle wheel 100

In the embodiment of Figures 5 and 6, each finger 131 of a slopmg paddle 130 has a lengthwise dnection (defined by the dnection of the slits 132 between adjommg fingers 131) which is perpendicular to the radially outer end of the paddle However, the fingers of a paddle may extend in a different dnection Figure 23 is a cross- sectional view similar to Figure 6 of a portion of another embodiment of a paddle wheel employmg another example of a pan of slopmg paddles 150 which can be used in the present mvention Like the paddles 130 of Figure 6, each paddle 150 compπses a plurahty of fingers 151 separated by parallel slits 152 In contrast to the paddles 130 of Figure 6, the slopmg paddles 150 of Figure 23 have a lengthwise dnection (defined by the dnection of the slits 152) which is not perpendicular to the radially outer ends of the fingers 151 but extends at a different angle, such as perpendicular to the rotational axis of the shaft 111 of the paddle wheel, regardless of the angle of the radially outer ends of the fingers 151 Other slopmg paddles on the paddle wheel may have a similar structure These paddles 150 can function in substantially the same way as the slopmg paddles 130 of Figures 5 and 6, but they may be more expensive to manufacture, smce the overall shape of a given paddle 150 will depend upon the angle of the radially outer end of the paddle 150 with respect to the rotational axis, so paddles 150 at different angles to the rotational axis must be cut to different shapes In contrast, all of the paddles 130 of Figures 5 and 6, mcludmg the slopmg paddles and the nonslopmg paddles, can have the same overall rectangular shape and differ from each other only in then lengths

Claims

Claims What is claimed is-

1 An apparatus for removing a surface layer from an animal comprising a paddle wheel compπsmg a plurality of flexible paddles rotatable about a rotational axis, each paddle having a radially outer end for contactmg a surface of an animal, the outer ends of the paddles bemg arranged at a plurality of angles with respect to the rotational axis; and a first drive mechanism rotatmg the paddle wheel about the rotational axis

2 An apparatus as claimed in claim 1 wherein each paddle extends over a region measured parallel to the rotational axis which is smaller than a total region measured parallel to the rotational axis over which all of the paddles together extend.

3. An apparatus as claimed in claim 1 wherein a surface defined by paths of the radially outer ends of the paddles as the paddles rotate about the axis is generally hourglass shaped

4 An apparatus as claimed m claim 1 wherein each paddle compπses a plurality of flexible fingers 5 An apparatus as claimed in claim 1 wherein each finger can bend mdependently of other fingers on the same paddle.

6 An apparatus as claimed m claim 4 wherein each paddle is substantially flat

7 An apparatus as claimed m claim 4 wherein each paddle comprises a plate havmg one or more slits formed therein and dividing the plate mto a plurality of the fingers 8. An apparatus as claimed m claim 7 wherein each plate includes a plurality of parallel slits.

9. An apparatus as claimed m claim 4 wherein each paddle comprises a plastic plate divided mto a plurality of the fingers by slits and a metal remforcmg plate secured to a radially outer end of each finger

10. An apparatus as claimed in claim 4 wherein each of the fingers mcludes a remforcmg member mounted on an outer end of the finger. 11. An apparatus as claimed m claim 4 wherein each finger has a radially outer end aligned along a straight lme with the radially outer ends of the other fingers of the same paddle

12. An apparatus as claimed in claim 11 wherein each finger on a paddle has a length extendmg perpendicular to the straight lme

13. An apparatus as claimed m claim 1 wherem the paddles are disposed at equal intervals around the rotational axis

14. An apparatus as claimed m claim 1 wherem the paddles are mounted on a hub which is capable of translating parallel to the rotational axis while rotating about the axis

15 An apparatus as claimed in claim 1 wherein all of the paddles are rectangular and have the same width 16. An apparatus as claimed m claim 1 wherem a bendmg stiffness of the paddles varies among the paddles

17 An apparatus as claimed in claim 16 wherem a bendmg stiffness of the paddles mcreases towards a widthwise center of a region measured parallel to the rotational axis over which the paddles extend.

18. An apparatus as claimed in claim 1 mcludmg a second dnve mechanism arranged to translate the paddle wheel transversely with respect to the rotational axis towards and away from an animal bemg processed.

19. An apparatus as claimed m claim 18 wherein the second drive mechanism can exert a constant force on the paddle wheel towards an animal bemg processed

20. An apparatus as claimed in claim 19 wherem the second drive mechanism comprises a drive cylmder 21. An apparatus as claimed m claim 1 wherem a plurality of the paddles are arranged m pairs, each pan mcludmg two of the paddles having radially outer ends sloped m opposite directions from each other with respect to the rotational axis.

22. An apparatus as claimed m claim 21 wherem each paddle in each pair is coplanar with the other paddle in the same pair. 23. An apparatus as claimed m claim 21 wherem the two paddles of each pan are symmetrically aπanged with respect to a common centerlme plane.

24. An apparatus as claimed in claim 1 including a support arranged to support an animal opposite the paddle wheel

25. An apparatus as claimed in claim 24 wherem the support can raise and lower the animal with respect to the paddle wheel while the animal is in contact with the paddle wheel

26. An apparatus as claimed m claim 25 wherein the support can rotate the animal about an axis extendmg m a lengthwise direction of the animal.

27. An apparatus as claimed in claim 1 wherem each paddle overlaps another one of the paddles in a dnection parallel to the rotational axis. 28. An apparatus for removing a surface layer from an animal comprising- a paddle wheel compπsmg a plurality of flexible paddles rotatable about a rotational axis, each paddle havmg a radially outer end for contactmg a surface of an animal, a distance of the outer ends from the rotational axis varying among the paddles; and a drive mechanism rotatmg the paddle wheel about the rotational axis 29. A paddle wheel for use m removmg a surface layer from an animal comprising: a hub havmg a rotational axis; and a plurality of flexible paddles extendmg outwards from the rotational axis of the hub, each paddle havmg a radially outer end for contacting a surface of an animal, the outer ends of the paddles bemg arranged at a plurality of angles with respect to the rotational axis 30. A paddle wheel as claimed m claim 29 wherem the paddles are disposed at uniform intervals around the rotational axis.

31. A paddle wheel as claimed m claim 29 wherein each paddle extends substantially parallel to a plane contammg the rotational axis.

32. A paddle wheel as claimed m claim 31 wherem each paddle is offset with respect to a plane contammg the rotational axis of the hub.

33. A paddle wheel as claimed m claim 29 wherein a surface defined by paths of the radially outer ends of the paddles as the paddles rotate about the axis is generally hourglass shaped

34. A method of removmg a surface layer from an animal comprising contacting an animal with a rotatmg paddle wheel mcludmg a plurality of flexible paddles havmg radially outer ends arranged at a plurality of angles with respect to a rotational axis of the paddle wheel

35 A method as claimed m claim 34 wherem the animal is a fish, the method mcludmg producmg relative movement of the paddle wheel and the fish in a lengthwise dnection of the fish while contactmg the fish with the paddle wheel 36 A method as claimed m claim 35 wherein the fish has been scaled prior to contacting the paddle wheel

37 A method as claimed m claim 35 mcludmg rotatmg the paddle wheel m a direction such that the radially outer ends of the paddles move with a gram of meat of the fish while contacting the fish

38 A method as claimed m claim 35 wherem the radially outer ends of the paddles move in a direction from a head to a tail of the fish while contactmg the fish

39 A method as claimed in claim 35 mcludmg pressmg the paddle wheel agamst the fish with a constant force while producmg the relative movement

40 A method as claimed m claim 35 mcludmg disposmg a pectoral region of the fish facing the rotational axis while contactmg the fish with the paddle wheel 41 A method as claimed m claim 35 mcludmg passmg the fish past the paddle wheel a first time to remove skm from a first side of the fish, rotatmg the fish so that a second side of the fish faces the paddle wheel, and passmg the fish past the paddle wheel a second tune to remove skm from the second side of the fish

42 A method as claimed m claim 35 mcludmg allowing the paddle wheel to translate parallel to the rotational axis while contacting the fish 43 A method as claimed m claim 34 mcludmg softening subdermal tissue of the animal prior to contactmg the animal with the paddle wheel

44 A method as claimed m claim 43 wherem the animal is at least partially frozen, the method mcludmg immersing the animal m water to soften the subdermal tissue

45 A method as claimed in claun 44 wherem the temperature of the water is between about 160°F and about 180°F