() ne type of chicken thigh deboner utilizes an aperture diaphragm formed from a tough rubber material. The femur is forced through the aperture of the cliaplwagm so that only the femur bone emerges, with the meat being left hehind. A disadvantage of this apparatus is that it is not always effective in removing a) i of the meat from the bone.

Another form of deboning apparatus utilizes a pair of nylon worms that rotate towards one another, with the meat being entrapped in the nip between the worms and the rigid bone being discarded. A disadvantage of a deboning apparatus of this type, as well as the prior diaphragm-based apparatus, is that it is difficult to keep regularly clean in accordance with abattoir regulations.

All1\1MARY OF THE INVENTION According to a first aspect of the invention there is provided a deboning apparatus comprising clamping means for releasably clamping one end of a joint of meat in position. a pair of opposed stripping blades, first actuating means for reciprocally moving the stripping blades between a retracted position and an extended position in which they snugly encircle a bone in the joint adjacent the one end. and second actuating means for reciprocally moving the c tamping means and the extended and encircling stripping blades between a proximal position and a distal position so as to cause the meat to be stripped from the other end of the bone.

I n a preferred form of the invention, the first actuating means comprise a first pair of opposed actuators to which the stripping blades are connected and the second actuating means comprise a second pair of actuators, with the first pair of actuators being arranged to move transversely relative to the second pair of actuators.

Thé the first pair of actuators are mounted to a corresponding pair of reciprocating rams forming part of the second pair of actuators.

Conveniently, the clamping means comprises a clamping bracket terminating in rrup formation, a retaining plate pivotable between a raised releasing position and a lowered retaining position in which the retaining plate holds the hone captive within the stirrup formation, and a plate actuator for moving the retaining plate between the releasing and retaining positions.

Advantageously, the deboning apparatus includes a pneumatic controller comprising a plurality of pneumatic control valves and switches, with the actuating means being pneumatically operated by the pneumatic controller pneumatic logic.

Alternatively, the deboning apparatus includes a hydraulic controller, with the actuating means being hydraulically operated by the hydraulic controller using hydraulic logic.

I n v preferred form of the invention, the deboning apparatus includes a guillotine assembly for severing a joint or knuckle of non-clamped end of the bone for facilitating the stripping of meat from the bone. thé the guillotine assembly includes a guillotine plate, guide means for guiding the plate, guillotine actuating means for reciprocally moving the guillotine plate within the guide means, and triggering means for triggering the guillotine actuating means.

A triggering means is conveniently actuable by the joint or knuckle of the non- clamp end of the bone, with the triggering means being adjustable to enable the position at which the knuckle or joint is severed along the bone to be varied.

Typically, the guillotine is formed with a vee-shaped blade, and the guide plate is formed with an opposed vee-shaped blade arranged to overlap with the vee- shaped blade of the guide plate during the severing operation.

The invention extends to a method of automatically deboning a joint of meat comprising the steps of : b) clamping one end of the joint of meat in position; c) moving a pair of opposed stripping blades between a retracted position and an extended position in which they snugly encircle a bone in the joint adjacent the one end of the joint ; d) moving the clamping means and the extended and encircling stripping blades apart from one another so as to cause the meat to be stripped from the other end of the bone.

Preferably, the method includes the initial step of : a) using a guillotine assembly to sever a knuckle or joint from the other end of the bone to facilitate the stripping operation.

('onveniently. the method includes the subsequent steps of : e) moving the pair of opposed stripping blades between the extended position and the retracted position; and f) unclamping the stripped bone.

Advantageously, the method includes the step of repeating steps a) to f) in a subsequent stripping cycle.

IIIZIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a front view of a chicken thigh deboner of the invention; Figure 2 shows a detailed perspective view of the chicken thigh deboner of Figure 1; Figures 2A & 2B show more detailed perspective and exploded views of the chicken thigh deboner of Figure 1; Figures 3A to 3E show side and front views of the various steps involved in deboning a chicken thigh; Figure 4 shows a pneumatic circuit diagram illustrating the pneumatic circuitry forming part of the chicken thigh deboner of the invention; Figure 5 shows a partly cut-away top plan view of a second embodiment of a chicken thigh deboner of the invention incorporating a guillotine assembly; Figure 6 shows a more detailed underplan perspective view of the guillotine assembly of Figure 5 in the retracted position; Figure 7 shows a top perspective view of part of the guillotine of Figures 5 and 6 in the partly extended position; and Figure 8 shows an underplan perspective view of the guillotine of Figures 5 to 7 with the various components disassembled for cleaning.

I) ESCRIPTION OF EMBODIMENTS first first to Figures 1 and 2. a chicken thigh deboner 10 of the invention includes a stainless steel table 12 from which an upright back panel 14 projects.

Three pneumatic actuators 16,18 and 20 are mounted vertically via brackets 22 to the panel 14. Each of the pneumatic actuators are provided with a central reciprocating ram 24 and an outer pair of guide rods 26. Mounting platforms 28. 30 and 32 are carried on the ends of the rams and guide rods of the respective actuators 16,18 and 20. Upper and lower inner hydraulic actuators 4 and 36 are in turn mounted horizontally to the respective upper and lower Faces of the central mounting platform 30, and outer pneumatic actuators 38 and 40 are horizontally mounted to downwardly extending flanges 42 forming part of the outer platforms 28 and 32. The pneumatic actuator 36 includes a pneumatic ram 44 to the end of which is bolted a stripping plate 46 terminating in a notched blade 48.

As is clear from Figure 2B, the plate 46 travels within a guide track 49 defined I-) a guide bracket 50 which is screwed to the underside of the platform 30. the other pneumatic actuators 34,38 and 40 are provided with identical ram, blade and bracket arrangements. The pneumatic actuator 40 is arranged to reciprocate a stripping plate 52 similarly terminating in a notched blade 54.

Die reciprocating plate 52 moves in opposition to the reciprocating plate 46 between retracted and extended positions. A pair of clamping arms 56 and 58 extend from respective mounting brackets 60 and 62 and terminate in part circular bone-receiving stirrup recesses 64. A horizontal pivot rod 66 carries a Eair of overhead clamping or retaining plates 68 and 64. The pivot rod 66 is driven via a central pneumatic actuator 70 which is arranged to pivot the rod 66 so as to move the clamping plate 68 between upper released and lower c tamping positions.

The operation of the chicken thigh deboner of the invention will now be described with reference to Figures 3A to 3E. After a chicken thigh 72 has been prepared by removing the knee joint of the femur with secateurs, the hip joint 74 of the thigh is located within the stirrup recess 64. The retaining plate X is then pivoted downwards by the pneumatic actuator 70 from the Figure 3A to the Figure 3B position in which it effectively closes off the stirrup opening 64 to clamp the femur 94 in position. The pneumatic actuators 36 and 40 are then activated so that the opposed stripping plates or blades 46 and 52 are clriw : n towards one another to a position in which their respective notches encircle and clamp around the femur just below the stirrup aperture 64, as is clear from Figure 2. The pneumatic actuators 18 and 20 are then activated, causing the rams 24 to extend downwardly, driving the stripping blades along the femur and stripping the meat 78 away from the femur so that only the femur bone 80 is left clamped in position. The pneumatic actuators 36 and 40 are then activated to cause the stripping blades 46 and 52 to retract. The retaining plate 68 is then raised to the Figure 3E position, and the bone 80 is released and discarded. The stripped meat 78 falls through one of a pair of apertures 82 in the table top 83 and is collected in a dish 84 below. The thigh deboner is now ready for the next cycle.

Referring now to Figure 4, a pneumatic circuit diagram is shown illustrating the manner in which the deboner is operated. A pressurized air source 86 is filtered and regulated by means of a filter and regulator 88. A footswitch 89 is used to control the operation of the deboner. The footswitch controls the flow of air to three iive-way two-position valves 90,92 and 94 and three three-way two- position magnetic valves 96.98 and 100. The valve 90 controls the operation ol the pneumatic actuator 70. and the valve 92 in conjunction with the valve 96 controls the operation of the pneumatic actuators 34,36.38 and 40. The valve 4. together with the magnetic valves 98 and 100. control the operation of the three vertically mounted pneumatic actuators 16.18 and 20.

, entire deboning cycle takes less then one second to complete and is entirely controlled by the pneumatic logic embodied in the pneumatic circuit of Figure 4. A double thigh deboner of the type illustrated in the above embodiment can debone from 40 to 48 thighs per minute. Naturally, the number of deboning stations can be increased to four or more, with a concomitant increase in processing speed.

Referring now to Figures 5 and 6, a guillotine assembly 102 is shown mounted to the underside of the table top 83. Instead of manually having to prepare the thigh for deboning by removing the knee joint using a pair of secateurs, the knee joint is simply removed in a semi-automated operation by inserting it through a circular aperture 104 in the table top. A trigger mechanism 105 activates the pneumatically operated guillotine and causes the knee joint to be removed at the correct position, in the manner described below.

Figure 6 illustrates the guillotine assembly 102 in more detail. A two-way pneumatic actuator 106 includes a pneumatic ram 108 terminating in a clevis 1 10 to which a guillotine plate 112 is removably affixed by means of a clevis pin 1 1 1. As is clear from Figures 7 and 8, the guillotine plate 112 terminates in a vee-shaped blade 113, and is arranged to slide to and fro within side channels 1 14 del-iiied within a base plate 116. The side channels 114 are defined by a pair of re-entrant flanges 118, and a diamond-shaped aperture 120 is formed in the base of the base plate. Four threaded apertures 122 are similarly formed in the base of the base plate for bolting the base plate 116 beneath the table top 83 in a position in which the diamond-shaped aperture 120 is in alignment with the circular aperture 104.

The trigger mechanism 105 includes a stirrup-shaped lever 126 terminating in l-sllaped arms 128. the ends of which are mounted pivotably to trunnion blocks ) 30 which are in turn bolted onto the flanges 118. A trigger plate 131 extends from the centre of the stirrup-shaped lever 126 partly into the aperture 120. A sprung shaft assembly 132 is screwed into one of the trunnion blocks 130 and extends through an aperture defined in a platform portion 133 forming part of the stirrup lever 126. The sprung shaft captivates a coil spring 138 between a tteríly nut 139A and an annular plunger 139B which biases the stirrup lever ) 26 into into fully closed position illustrated illustrated Figure Figure l hc opposite side of the stirrup lever carries a microswitch 140 having a roller contact 141. The roller contact 141 is activated by abutting against the underside of a switch plate 142 which is carried on a shaft 144 having a threaded end which screws into a complementally threaded aperture 145 in the trunnion block 130. The guillotine assembly 102 is operated in the following manner. The operator holds the complete thigh 72 by gripping the hip joint side 72A. The exposed knee joint side 72B is passed through the circular aperture l () 4 in the table and into the diamond-shaped aperture 120, where it strikes the plate 131. The stirrup lever 124 is moved inwardly against the biasing action of the coil spring 138 to a point at which the roller contact 141 of the microswitch 140 contacts the underside of the switch plate 142, thereby commencing a forward stroke of the ram 108. The vee-shaped blade 113 of the guillotine plate advances rapidly to sever the knee joint from the thigh. The vce-shaped blade 113 and the opposed vee-shaped blade 146 defining part of the diamond-shaped aperture 120 in combination conduct a gripping. centering and severing operation in a fraction of a second, with the severed knee joint or I : nucl ; le falling into a receptacle (not shown). The operator does not alter his or her grip on the thigh. but merely inserts the hip joint 74 into the stirrup recess 64 in the manner previously described to commence the deboning operation.

The exact location at which the knee joint is severed from the femur can be ud ; usted by screwing the strike plate 142 up and down the shaft 144 to alter its heiglit.

Figure 8 illustrates the relatively simple manner in which the guillotine assembly 102 can be disassembled or stripped for cleaning purposes. The dcvis pin III is removed to release the guillotine plate 112. Thereafter, the strike plate 142 and the sprung shaft assembly 132 are unscrewed from the trunnion blocks, and the stirrup lever 126 is pivoted upwardly on the trunnion blocks to allow complete removal of the guillotine plate 112 for cleaning purposes.

Referring back to Figure 4, a pneumatic sub-circuit 148 for controlling the operation of the guillotine assembly 102 includes the roller contact 141 forming part of the microswitch 140, which, together with the magnetic switch 152, control the flow of air to a five-way two-position valve 154 which in turn controls the operation of the pneumatic actuator 106. The magnetic switch 152 is responsive to a signal from the microswitch 140.

A major avantage of the chicken thigh deboner of the invention is that it is entirely pneumatically operated, relying on pneumatic rather than electrical or clectl-ollic-based logic. As a result, the entire apparatus can be regularly washed and cleaned without danger of wetting electrical apparatus and causing electrical shorts and the like. The various stainless steel components of the apparatus, such as the stripping blades and the guides within which they are mounted, can easily be disassembled for further cleaning and maintenance, as is ctcur from Figure 2B.