Abstract:
Apparatus for extracting pomegranate seeds from pomegranates including a pomegranate breaker operative for breaking open pomegranates generally without cutting pomegranate seeds at the interior of the pomegranates and a pomegranate seed extractor operative to engage broken open pomegranates for separating the pomegranate seeds from other parts of the pomegranates.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the processing of fresh pomegranates generally and more particularly to the extraction of the seeds of pomegranates for fresh consumption. 
     BACKGROUND OF THE INVENTION 
     The following U.S. Patents are believed to represent the current state of the art: 
     U.S. Pat. Nos. 5,508,052; 5,000,967; 4,284,651; 4,530,278; 5,178,057; 5,088,393; 5,286,508; 5,817,360; 6,220,153 and 6,371,014. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to provide apparatus and methodology for the efficient extraction of the seeds of pomegranates. 
     There is thus provided in accordance with a preferred embodiment of the present invention apparatus for extracting pomegranate seeds from pomegranates including a pomegranate breaker operative for breaking open pomegranates generally without cutting pomegranate seeds at the interior of the pomegranates and a pomegranate seed extractor operative to engage broken open pomegranates for separating the pomegranate seeds from other parts of the pomegranates. 
     In accordance with a preferred embodiment of the present invention the pomegranate breaker includes a pomegranate periphery scorer for scoring an outside rind of the pomegranates. Additionally or alternatively, the pomegranate breaker includes a pomegranate crown remover. Additionally, the crown remover includes a rotating knife having a curved cutting edge configured to enable removal of the crown generally without cutting pomegranate seeds. In accordance with another preferred embodiment of the present invention the pomegranate breaker includes a plurality of hooks which engage segments of the pomegranates following partial separation of the segments from each other by scoring. 
     In accordance with yet another preferred embodiment of the present invention the pomegranate breaker includes an equatorial scorer for performing equatorial scoring of the pomegranate. In accordance with still another preferred embodiment of the present invention the pomegranate breaker includes a pomegranate engager for oppositely rotating portions of the pomegranate, thereby to break open the pomegranate. In accordance with a further preferred embodiment of the present invention the pomegranate breaker includes an automatic pomegranate positioning assembly operative automatically to position the pomegranate at multiple operative positions during pomegranate breaking. Additionally or alternatively, the pomegranate breaker includes a scoring knife having a cutting depth limiter associated therewith. 
     In accordance with still another preferred embodiment of the present invention the pomegranate seed extractor includes a plurality of fluid jets. Additionally, the fluid jets impinge upon the broken-open pomegranates while the broken-open pomegranates are in motion. In accordance with another preferred embodiment of the present invention the pomegranate seed extractor includes a pomegranate seed/pomegranate membrane separator. 
     There is also provided in accordance with another preferred embodiment of the present invention a method for extracting pomegranate seeds from pomegranates including automatically breaking open pomegranates generally without cutting pomegranate seeds at the interior of the pomegranates and engaging broken-open pomegranates for separating the pomegranate seeds from other parts of the pomegranates. 
     In accordance with another preferred embodiment of the present invention the breaking includes scoring an outside rind of the pomegranates. Additionally or alternatively, the breaking includes pomegranate crown removal. In accordance with yet another preferred embodiment of the present invention the breaking includes automatically causing a plurality of hooks to engage segments of the pomegranates following partial separation of the segments from each other by scoring. In accordance with still another preferred embodiment of the present invention the breaking includes performing equatorial scoring of the pomegranate. In accordance with yet another preferred embodiment of the present invention the breaking includes oppositely rotating portions of the pomegranate, thereby to break open the pomegranate. Additionally or alternatively, the breaking includes automatically positioning the pomegranate at multiple operative positions during pomegranate breaking. 
     In accordance with another preferred embodiment of the present invention the breaking employs a scoring knife having a cutting depth limiter associated therewith. 
     In accordance with yet another preferred embodiment of the present invention the engaging employs a plurality of fluid jets. Additionally, the engaging comprises moving the broken-open pomegranates while the fluid jets impinge upon the broken-open pomegranates. In accordance with still another preferred embodiment of the present invention the engaging comprises separating the pomegranate seeds from pomegranate membranes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
         FIG. 1  is a simplified pictorial illustration of apparatus for extraction of seeds of pomegranates, constructed and operative in accordance with a preferred embodiment of the present invention; 
         FIGS. 2A &amp; 2B  are simplified pictorial illustrations of a pomegranate holder forming part of the apparatus of  FIG. 1 , both empty and holding a pomegranate in an orientation suitable for operation of the apparatus of  FIG. 1 ; 
         FIG. 3  is a partially cut away side view illustration of pomegranate crown removal apparatus, forming part of the apparatus of  FIG. 1 ; 
         FIGS. 4A ,  4 B,  4 C and  4 D are simplified side view illustrations of four steps in the operation of the apparatus of  FIG. 3 ; 
         FIG. 5  is a simplified pictorial illustration of part of a pomegranate break-open assembly constructed and operative in accordance with a preferred embodiment of the present invention; 
         FIGS. 6A ,  6 B,  6 C,  6 D,  6 E,  6 F,  6 G,  6 H and  6 I are simplified top view illustrations of steps in the operation of the pomegranate break-open assembly of  FIGS. 1 and 5 ; 
         FIGS. 7A ,  7 B,  7 C,  7 D,  7 E,  7 F,  7 G,  7 H and  7 I are simplified side view illustrations of steps in the operation of the pomegranate break-open assembly of  FIGS. 1 and 5 ; 
         FIGS. 8A and 8B  illustrate extraction of seeds from broken-open pomegranates using air jets in accordance with one embodiment of the present invention; 
         FIGS. 9A and 9B  illustrate extraction of seeds from broken-open pomegranates using air jets in accordance with another embodiment of the present invention; 
         FIG. 10  is a pictorial illustration of transport and separation of individual pomegranate seeds in accordance with a preferred embodiment of the present invention; 
         FIG. 11  is a sectional illustration taken along lines XI-XI in  FIG. 10 ; 
         FIG. 12  is a simplified pictorial illustrations of apparatus for extraction of seeds of pomegranates, constructed and operative in accordance with another preferred embodiment of the present invention; and 
         FIGS. 13A-13F  are simplified pictorial illustrations which illustrate breaking open a pomegranate using the apparatus of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference is now made to  FIG. 1 , which is a simplified pictorial illustration of apparatus for extraction of seeds of pomegranates, constructed and operative in accordance with a preferred embodiment of the present invention. For the purposes of the specification and claims, the term “seed” is employed to refer to the individual seed enveloped by its aril. 
     The apparatus of  FIG. 1  comprises an endless conveyor  100 , driven by a motor (not shown) preferably in a stepwise manner, which is operative to receive and supply pomegranates to crown removal assemblies  102  and thereafter to pomegranate break-open assemblies  104 , which break open the pomegranates to expose their seeds for extraction thereof, generally without cutting the seeds. Broken-open pomegranates are transported on conveyors  106 , preferably rod, mesh or screen conveyors, into operative engagement with fluid jets, preferably air jets  108 , which dislodge the seeds  110  from the remainder of the broken-open pomegranate. Preferably a retaining conveyor belt  111 , which is preferably vibrating, engages the broken-open pomegranates from above, while they are engaged by the air jets  108  from below. The dislodged seeds  110  are preferably engaged by a flow of water and caused thereby to fall along an inclined surface  112  into a water flow trough  114  at which pomegranate membranes  116  are separated therefrom, by floating. The membranes  116  are deflected to a waste receptacle  118 , some of the membranes being deflected by a rotating membrane deflector  120 . The seeds  110  are preferably conveyed by an additional conveyor  124 , preferably a screen conveyor, which permits water to drip therethrough, to a collection location (not shown). 
     Conveyor  100  preferably comprises pairs of pomegranate support sockets  128 , which are mounted in pairs onto socket support surfaces  130 . Socket support surfaces  130  are preferably interconnected by chains  132 , as shown. 
     Reference is made to  FIGS. 2A and 2B , which illustrate a pomegranate support socket  128 , both empty and holding a pomegranate in an orientation suitable for operation of the apparatus of  FIG. 1 . As seen in  FIGS. 2A and 2B , pomegranate support socket  128  preferably defines a generally conical circumferential pomegranate support surface  134  which is rotationally symmetric about a generally vertical axis, designated by reference numeral  136 . An aperture  138  is defined at the center of pomegranate support surface  134  through which the lower part of the pomegranate, including the crown, extends. 
     Preferably, the pomegranate support surface  134  is arranged at an angle of approximately 33 degrees with respect to a horizontal plane orthogonal to vertical axis  136  and the aperture  138  has a radius of 30 mm. Preferably, as seen in  FIG. 2B , each pomegranate  140  is arranged in a pomegranate support socket  128 , such that its crown  142  is centered along axis  136 . 
     Reference is now made additionally to  FIG. 3 , which, together with  FIG. 1 , illustrates one embodiment of a crown removal assembly  102 . Each crown removal assembly  102 , of which preferably two are provided, preferably includes a pneumatically operated piston assembly  150 , including a cylinder  152  ( FIG. 1 ) and a rod  154 , which terminates in a pomegranate retaining head  156 . Assembly  150  provides vertical motion of retaining head  156  along a preferably vertical axis  158 . Preferably pomegranate support sockets  128  are each aligned relative to a crown removal assembly  102 , such that vertical axis  136  and vertical axis  158  are coaxial. 
     Disposed along axis  158  is a rotatable crown removing knife  184 , which is arranged to be displaced vertically upward along axis  158  into operative engagement with the crown  142  of the pomegranate  140 , which crown is preferably aligned with axis  136  and thus with axis  158 . Knife  184  is driven in rotary motion by a motor (not shown) and is selectably displaced along axis  158  by a linear actuator  186 , such as a pneumatic piston. A knife depth limiting ring  188  preferably surrounds knife  184 , but does not rotate therewith. It is a particular feature of the present invention that knife  184  has a curved blade configuration which is adapted to the configuration of the crown  142  and to the configuration of a portion  190  ( FIG. 4B ) of the pomegranate rind which separates the crown  142  from the seeds  110 , so as to leave portion  190  ( FIG. 4B ) intact. 
     Reference is now made to  FIGS. 4A ,  4 B,  4 C and  4 D, which are simplified side view illustrations of four steps in the operation of the apparatus of  FIG. 3 . As seen in  FIG. 4A , retaining head  156  is lowered into operative engagement with a top surface of pomegranate  140 , which is in turn supported on pomegranate support socket  128 . If the pomegranate  140  is properly positioned in support socket  128 , rotating knife  184  is aligned with the pomegranate crown  142 . 
     Turning to  FIG. 4B , it is seen that knife  184  is moved upward along axis  158  into cutting engagement with crown  142 , limited by engagement of ring  188  with the pomegranate  140 , thus removing the crown but preferably not engaging or damaging the pomegranate seeds  110 . It is appreciated that due to variations in the configuration of the fruit, in some cases, engagement of the knife  184  with the pomegranate seeds  110  will occur, although this is sought to be minimized or eliminated. 
     It is a particular feature of the present invention that knife  184  has a curved blade configuration which is adapted to the configuration of the crown  142  and to the configuration of a portion  190  of the pomegranate rind which separates the crown  142  from the seeds  110 , so as to leave portion  190  intact. 
       FIG. 4C  illustrates pomegranate  140  followed preferred crown removal. 
       FIG. 4D  illustrates disengagement of retaining head  156  from pomegranate  140 , following removal of the crown  142 . 
     At this stage, as shown in  FIG. 1 , endless conveyor  100  moves the pomegranates in a stepwise manner from the crown removal assemblies  102  to the break-open assemblies  104 . 
     Reference is now made additionally to  FIG. 5 , which is a simplified illustration of a portion of pomegranate break-open assembly constructed and operative in accordance with a preferred embodiment of the present invention, and to  FIGS. 6A ,  6 B,  6 C,  6 D,  6 E,  6 F,  6 G,  6 H &amp;  6 I and  FIGS. 7A ,  7 B,  7 C,  7 D,  7 E,  7 F,  7 G,  7 H &amp;  7 I, which are simplified respective top view and side view illustrations of steps in the operation of the pomegranate break-open apparatus of  FIG. 5 . Pomegranate break-open assembly  104 , of which preferably two are provided, preferably includes a pneumatically operated piston assembly  230 , including a cylinder  232  ( FIG. 1 ) and a rod  234 , which terminates in a pomegranate positioning head  236 . Assembly  230  provides vertical motion of positioning head  236  along a preferably vertical axis  238 . 
     Pomegranate positioning head  236  preferably includes a plurality of barbed pomegranate engagement shafts  239  which extend parallel to axis  238  downwardly from a bottom surface  240  of head  236  and is provided with a plurality of evenly spaced vertically aligned slits  241  along an outer cylindrical surface  242  thereof. 
     Preferably disposed at bottom surface  240  of head  236  is a pusher assembly  243 , which preferably is pneumatically operated for selectively disengaging the head  236  from the pomegranate  140 . Pusher assembly  243  preferably comprises a pusher element  244 , which is connected by a rod  245  to a piston  246 . The piston  246  is biased forwardly by a spring  247  and is positioned along axis  238  relative to a surrounding cylinder  248  preferably by the relative pneumatic pressure supplied to conduits  249 , communicating with respective interior volumes of the cylinder  248  lying on respective opposite sides of piston  246 . 
     Alternatively, pusher assembly  243  may be replaced by a vacuum cup (not shown), which communicates with conduits  249 . 
     Preferably, a pomegranate support socket  128  is aligned along axis  238  for initial pickup of the pomegranate  140  from the socket  128 , as seen in  FIGS. 6A and 7A , wherein barbed pomegranate engagement shafts  239  engage and retain the pomegranate  140 . Following pomegranate pick-up, the conveyor  100  ( FIG. 1 ) shifts socket  128  in a stepwise manner so that the pomegranate can be lowered into operative engagement with a scoring and pulling assembly  250 , as shown in  FIGS. 6B and 7B  and described further hereinbelow. 
     Scoring and pulling assembly  250  preferably comprises a ring-shaped base element  252 , which is fixedly mounted onto the chassis of the apparatus. Pivotably mounted onto base element  252  there are provided a plurality of scoring knife assemblies  254 , preferably six in number, which are spring loaded by a corresponding plurality of springs (not shown), which are mounted onto base element  252 . 
     Also pivotably mounted onto base element  252  are a plurality of segment pulling assemblies  258 , preferably six in number, interdigitated with scoring knife assemblies  254 . Segment pulling assemblies  258  are actuated, as described hereinbelow, by a corresponding plurality of commonly controlled segment pulling assembly pneumatic actuators  260 , which are fixedly mounted onto base element  252 . 
     Scoring knife assemblies  254  preferably each include an integrally formed arm element  262  having a pivot end  264  at the top thereof and a knife clamping portion  265  at the bottom thereof. A knife  266  is clamped between the knife clamping portion  265  and a clamping element  268 , so as to extend outwardly from the knife clamping portion  265  by a predetermined distance, equal to a maximum desired scoring depth at which scoring of a pomegranate is to be effected. 
     Segment pulling assemblies  258  preferably each include an integrally formed arm element  272  having a pivot end  274  at the top thereof, a bend  276  nearer to the top thereof than to the bottom thereof and an inwardly facing pointed hook  278  at the bottom thereof. 
       FIGS. 6A and 7A  illustrate pomegranates  140  being held by pomegranate positioning heads  236  above respective scoring and pulling assemblies  250 . At this stage, sockets  128  (not shown in  FIG. 7A  for the sake of clarity) are positioned intermediate the pomegranates  140  and the respective scoring and pulling assemblies  250 . After the stage shown in  FIGS. 6A and 7A , conveyor  100  ( FIG. 1 ) is operated, preferably in a stepwise manner, to shift sockets  128  in a direction indicated by arrows  280  to positions illustrated in  FIG. 6B . The steps which occur while, pomegranate support sockets  128  are in the positions shown in  FIG. 6B  are now described with reference to  FIGS. 6B-6I  and  7 B- 7 I. 
       FIGS. 6B and 7B  illustrate initial engagement of pomegranates  140  with respective scoring and pulling assemblies  250 , produced by downward movement of pomegranate positioning heads  236  resulting from actuation of piston assembly  230 . 
       FIGS. 6C and 7C  illustrate further downward movement of pomegranate positioning heads  236  relative to respective scoring and pulling assemblies  250 , resulting in scoring engagement of knives  266  with the pomegranates  140 . The scoring engagement preferably begins from the bottom of the pomegranate  140  at an edge  282  at which the crown was removed and proceeds upward along multiple, mutually and evenly spaced paths along the outer skin of the pomegranate  140 . The depth of scoring is carefully limited by the extent by which each knife  266  protrudes from knife clamping portion  265 , in order to prevent, in most cases, cutting of the pomegranate seeds  110 . 
       FIGS. 6D and 7D  illustrate still further downward movement of pomegranate positioning heads  236  relative to respective scoring and pulling assemblies  250 , resulting in continued scoring engagement of knives  266  with the pomegranate  140 . The scoring engagement continues to a location near the top of the pomegranate  140  at which location the pomegranate is engaged by head  236  and the knives  266  engage respective slits  241  in head  236 . 
       FIGS. 6E and 7E  show additional downward movement of pomegranate positioning heads  236  relative to respective scoring and pulling assemblies  250 , resulting in knives  266  moving along slits  241  in heads  236  and resulting in initial pulling apart of segments  284  of the pomegranates  140 . Pulling apart is realized by engagement of hooks  278  with respective segments  284  of the pomegranate  140  at edge  282  thereof and by pivotal motion of arm elements  272  resulting from the downward movement of pomegranate positioning heads  236 . 
       FIGS. 6F and 7F  show still further downward movement of pomegranate positioning heads  236  relative to respective scoring and pulling assemblies  250 , resulting in knives  266  moving further upward along slits  241  in heads  236  and resulting in further pulling apart of segments  284  of the pomegranates  140 , producing breaking of membranes  116  ( FIG. 1 ). This continued pulling apart is realized by pivotal motion of arm elements  272  resulting from the downward movement of pomegranate positioning heads  236  while hooks  278  are in engagement with respective segments  284  of the pomegranates  140  at edges  282  thereof. 
       FIGS. 6G and 7G  show still further downward movement of pomegranate positioning heads  236  relative to respective scoring and pulling assemblies  250 , resulting in full breaking open of segments  284  of the pomegranates  140 , producing further breaking of membranes  116  ( FIG. 1 ) and very fully exposing the seeds  110 .  FIGS. 6G and 7G  also illustrate disengagement of hooks  278  from respective segments  284  of the pomegranates  140 , produced by the operation of actuators  260  ( FIG. 5 ). 
       FIGS. 6H and 7H  show initial operation of pusher assembly  243  ( FIG. 5 ) which causes disengagement of the pomegranates  140  from the barbed pomegranate engagement shafts  239 . Full disengagement is shown in  FIGS. 6I and 7I . 
     Reference is now made to  FIGS. 8A and 8B , which illustrate extraction of seeds  110  from broken-open pomegranates  300  using air jets  108  in accordance with one embodiment of the present invention. In the illustrated embodiment of  FIGS. 8A and 8B , air jets  108  each provide a jet of air which impinges on each broken-open pomegranate  300  preferably in a raster pattern, as illustrated in  FIG. 8B . 
       FIGS. 9A and 9B  illustrate extraction of seeds  110  from broken-open pomegranates using air jets  108  in accordance with another embodiment of the present invention wherein air jets  108  each provide a jet of air which impinges on each broken-open pomegranate  300  in an overlapping spiral pattern, produced by combined rotational motion of the air jets  108  and perpendicular linear motion of the broken-open pomegranates  300  on conveyors  106 . 
     Reference is now additionally made to  FIG. 10 , which is a pictorial illustration of transport and separation of individual pomegranate seeds in accordance with a preferred embodiment of the present invention and to  FIG. 11 , which is a sectional illustration taken along lines XI-XI in  FIG. 10 . As seen in  FIG. 10 , air jets  108 , arranged for operation in accordance with the embodiment of  FIGS. 8A &amp; 8B  cause extraction of seeds  110  from broken-open pomegranates  300  on conveyors  106 . As noted above with reference to  FIG. 1 , and shown in  FIG. 11 , the dislodged seeds  110  and broken pieces of membranes  116  are preferably engaged by a flow of water  302  and caused thereby to fall along an inclined surface  112  into a water flow trough  114  at which membranes  116  are separated from the seeds  110  by differences in their specific gravity, resulting in floating of the membranes  116 , while the seeds  110  tend to sink in the trough  114 . 
     Reference is now made to  FIG. 12 , which is a simplified pictorial illustration of apparatus for extraction of seeds of pomegranates, constructed and operative in accordance with another preferred embodiment of the present invention. 
     The apparatus of  FIG. 12  comprises an endless conveyor  400 , driven by a motor (not shown) preferably in a stepwise manner, which is operative to receive and supply pomegranates  402  to pomegranate break-open assemblies  404 , which break open the pomegranates  402  to expose their seeds  405  for extraction thereof, generally without cutting the seeds  405 . Broken-open pomegranates are transported on a conveyor  406 , preferably a rod, mesh or screen conveyor, into operative engagement with fluid jets, preferably air jets  408 , which dislodge the seeds  405  from the remainder of the broken-open pomegranate  410 . Preferably a retaining conveyor belt  411 , which is preferably vibrating, engages the broken-open pomegranates from above, while they are engaged by the air jets  408  from below. The dislodged seeds  405  are preferably engaged by a flow of water and caused thereby to fall along an inclined surface  412  into a water flow trough  414  at which pomegranate membranes  416  are separated therefrom, by floating. The membranes  416  are deflected to a waste receptacle  418 , some of the membranes being deflected by a rotating membrane deflector  420 . The seeds  405  are preferably conveyed by an additional conveyor  424 , preferably a screen conveyor, which permits water to drip therethrough, to a collection location (not shown). 
     Conveyor  400  preferably comprises pomegranate support sockets  428 , which are mounted onto socket support surfaces  430 . Socket support surfaces  430  are preferably interconnected by at least one conveyor belt  432 , as shown. Pomegranates  402  are preferably positioned sidewise in sockets  428 . 
     Pomegranate break-open assembly  404  provides for initially equatorially scoring the pomegranates  402  and then breaking apart the pomegranates by rotating the top and bottom of the pomegranates in opposite directions, thus breaking the membranes  416  and exposing the seeds  405 . As seen in  FIG. 12 , the pomegranate break-open assembly  404  comprises a plurality of pomegranate engagement subassemblies  436 , which are preferably mounted on a rotating support  438 . 
     Each of the pomegranate engagement subassemblies  436  includes a pair of motor driven pomegranate rotators  440 , which are mounted for linear motion on linear actuators  442 , which are in turn rotatably mounted onto a base  444 . Base  444  is in turn mounted, typically via a shaft  446  onto rotating support  438 . Each of the pomegranate rotators  440  includes a drive shaft  448  to which is coupled a vacuum cup  450  or other engagement assembly for tightly engaging either the top or the bottom of a pomegranate  402 . 
     Reference is now additionally made to  FIGS. 13A-13F , which illustrate operation of a pomegranate engagement subassembly  436  of the break-open assembly  404 .  FIG. 13A  shows the subassembly  436  prior to engagement with a pomegranate  402 , with linear actuators  442  being operative to bring vacuum cups  450  into tight engagement with the pomegranate  402 . Following rotation of rotating support  438 , as indicated by arrows  460  in  FIG. 12 , the subassembly  436  in engagement with a pomegranate  402  is positioned for scoring. 
       FIGS. 13B and 13C  shows rotators  440  both operating in the same direction prior to and during scoring engagement of the pomegranate  402  with a knife  452 , preferably mounted onto a linear actuator  454 . As described hereinabove, care is taken such that scoring causes minimal or no cutting damage to the pomegranate seeds  405 .  FIG. 13D  shows breaking open of the pomegranate  402  by rotating its equatorially scored portions in opposite directions by action of pomegranate rotators  440  and linear motion of linear actuators  442  in mutually opposite directions as indicated by arrows  456 . 
       FIG. 13E  shows a typical broken-open pomegranate  410 , its equatorially scored portions being separated and each still being engaged by a vacuum cup  450 . It is seen that membranes  416  are broken and seeds  405  are exposed. At this stage, linear actuators  442  are preferably rotated with respect to base  444 , as indicated by arrows  458 . This, combined with rotation of rotating support  438  as indicated by arrows  460  in  FIG. 12 , positions the broken open portions of the pomegranate face down onto conveyor  406 , as shown in  FIG. 13F , at which position they are released by vacuum cups  450 . 
     It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of the various embodiments described hereinabove as well as modifications thereto which would occur to a person skilled in the art reading the foregoing description and which are not in the prior art.