Abstract:
A lug chain apparatus having lugs ( 22 ), an endless chain ( 30 ) and a positioning mechanism ( 20 ). The lugs ( 22 ) are releasably engageable with the chain ( 30 ). The positioning wheel ( 20 ) engages the lugs ( 22 ) and moves them along the chain ( 30 ), to predetermined locations along the chain respectively. Each lug ( 22 ) includes locking mechanism ( 24, 26, 31 ) that holds that lug ( 22 ) in a predetermined location along the chain ( 30 ) when in a locking state, and allows movement of that lug ( 22 ) along said chain ( 30 ) when in a releasing state, such that repositioning of the lugs ( 22 ) along the chain ( 30 ) is effected without removal of the lugs ( 22 ) from the chain ( 30 ).

Description:
FIELD OF INVENTION 
     The present invention relates generally to a lug chain apparatus with chain driven lugs, that are used widely in the packaging industry for tasks such as grouping or metering articles, and more specifically though not exclusively, to chain driven lugs that may be spaced with varying pitch along the length of a chain. Yet more specifically though not exclusively, the present invention relates to chain driven lugs adapted such that the aforementioned varying pitch may be achieved without altering the rotational speed of the chain. 
     BACKGROUND OF INVENTION 
     It is well known in the art that lugs, driven by chains, may be used for many purposes in industry such as, for example, grouping or metering articles as a part of a packaging process. Such articles may take differing sizes and may need to be grouped differently, depending on the requirement of the type of packaging used Therefore it is necessary to alter the spacing between successive lugs on the chain. 
     The prior art of such lug chains teaches lugs that are mounted upon a chain using some form of relatively easily releasable mechanism, which allows each lug to be removed, by hand, from the chain before being secured again to the chain at some other position. However, the prior art does not disclose a system whereby lugs may be releasably engaged with a chain, at desired points, whilst the system is in continuous operation. 
     Should the system require deactivation in order to reposition the lugs, it will necessarily lead to reduced efficiency of the system through increased ‘down time’. It is therefore advantageous that the system be capable of altering the positions of the lugs whilst remaining operational. 
     The present invention therefore seeks to overcome or at lease minimize the disadvantages of the prior art by providing a system whereby the spacing between successive lugs on a chain may be altered without deactivating the system. 
     SUMMARY OF INVENTION 
     A first aspect of the present inventions provides a lug chain apparatus comprising lugs, chain and positioning means, wherein the lugs are positioned at predetermined locations along the chain, and wherein the positioning means engages the lugs and moves them along the chain, to said predetermined locations, and wherein each lug comprises locking means to hold that lug in one of said predetermined locations along the chain when that locking means is in a locked state, and to allow movement of that lug along said chain when the locking means is in a releasing state, such that repositioning of the lugs along the chain is effected without removal of the lugs from the chain. 
     Preferably the positioning means is operable to automate the movement of the lugs along the chain. 
     Preferably, the lug chain further comprises an engagement assembly that puts the locking means into said locking state. 
     Preferably, the lugs maintain a friction fit with the chain so that the lugs are driven by the chain when the locking means is in said releasing state, and wherein the friction fit is overcome if the lugs become impeded, so that the chain may slip beneath the lugs. 
     Preferably, the locking means is maintained in said locking state by the presence of an engaging assembly. 
     Preferably, the lug comprises a body, and wherein the locking means comprises a latch that is hinged to that body, which latch is releasably engageable with the chain. 
     Preferably, the lug chain comprises a reservoir of lugs, the locking means of each of those lugs being maintained in said releasing state, and wherein those lugs are held within a working reach of the positioning means such that each may be engaged, in turn, by the positioning means. 
     A second aspect of the present inventions provides a method of altering the spacing between lugs on a lug chain which method comprises the step of: providing multiple lugs upon a chain, which lugs are movable along the chain to predetermined locations, without requiring removal of the lugs from the chain; and providing positioning means to engage the lugs and move them along the chain to respective ones of said predetermined locations: and providing locking means to hold each lug in said respective ones of said predetermined locations when in a locking state, and to allow movement of that lug along the chain when in a releasing state; putting the locking means into said locking state when a lug reaches said respective one of said predetermined locations: and unlocking the locking means before returning the lugs to the positioning means. 
     Preferably, the method further comprises the step of maintaining a reservoir of lugs, the locking means of each of those lugs being maintained in said unlocking state, within a working reach of the positioning means such that each may be engaged, in turn, by the positioning means. 
     Preferably, the method further comprises the step of providing an engagement assembly that puts the locking means of each lug into said locking state. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       The drawings referred to throughout the description illustrate only one preferred embodiment of the invention; one skilled in the art will readily appreciate that other specific embodiments of a lug or lug chain apparatus may be used whilst still benefiting from the invention disclosed herein. In which drawings: 
         FIG. 1  is fragmentary perspective view of a lug chain assembly according to a preferred embodiment of the present invention, showing some lugs in engagement with and moved by a positioning wheel; 
         FIG. 2  is a fragmentary perspective view of the lug chain assembly of  FIG. 1 , showing one of the lugs moved apart from the positioning wheel; 
         FIG. 3A  is an enlarged fragmentary plan view of the lug chain apparatus of  FIG. 1 ; 
         FIG. 3B  is a view taken along the line  3 B- 3 B in  FIG. 3A ; 
         FIG. 4A  is an enlarged fragmentary plan view of the lug chain apparatus of  FIG. 2 ; 
         FIG. 4B  is a view taken along the line  4 B- 4 B in  FIG. 4A ; 
         FIG. 5  is an enlarged cross sectional view of the lug of  FIG. 3A  and its surrounding portions. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates to a lug chain apparatus and a lug that is useful in the lug chain apparatus.  FIG. 1  shows an exemplary embodiment of the lug chain apparatus using a plurality of lugs  22  such as those used in the grouping or metering of articles A. The lugs  22  are releasably engageable with an endless chain  30  that is driven by a suitable chain-driving means  21  including, for example, sprocket wheels and a driving motor for the sprocket wheels. 
     Each lug  22  rests upon one side of the chain  30 , and protruding portions of the lug  22  extend parallel to portions of the chain  30  adjacent said side, as illustrated in  FIGS. 3B and 4B , thus defining a channel in which the chain  30  may be accommodated. The lug  22  does not form a tight fit with the chain  30 , but rather permits the chain  30  to slide through a channel in the lug  22 . A friction block  34 , is disposed within each lug  22 , as shown in  FIG. 5 . The friction block  34  is urged against a surface of the chain  30  and is formed from a high friction material. The friction block  34  is pivoted to the body of the lug  22 , about a pivot point  27 . Some form of resilient biasing means, such as a compression spring  29  held in a recess  23 , urges the friction block  34  to pivot about pivot  27  thereby bringing a free end portion of the friction block  34  into contact with some portion of the chain  30 . Preferably the pivot  27  is positioned sway from the centre of the friction block  34  and toward the side of the friction block  34  upstream of the motion of the chain  30 . Thus, should the lug  22  encounter an encumbrance to its motion along the chain, the friction block  34  may more easily pivoted away from the chain  30  so as to allow the chain  30  to slide beneath it. 
     Clearly, other means of inducing a friction fit between the lug  22  and the chain are possible, the use of a pivoted friction block  34  being only one implementation, which other means of achieving such an affect are well known in the art. 
     A locking means or mechanism is provided for each lug  22 . The locking means includes a latch  24  hinged at one of its ends to one end of the lug  22 , about pivot  26 . The opposing end of the latch  24  comprises a shaped portion  25  that protrudes toward the lug  22 , and which is shaped so as to allow engagement with apertures occurring between links in the chain  30 , as shown in  FIG. 5 . Thus, engaging the shaped portion  25  of the latch  24  with chain  30  secures the lug  22  in fixed relation to the chain  30 . 
     In the lug chain apparatus of  FIG. 1 , a number of lugs  22  of the type described above, are located around a chain  30 , which chain  30  is guided around a path a portion of which passes around the exterior of a star wheel  20  that provides a part of a positioning means or mechanism for positioning the lugs  22  at predetermined locations along the chain  30  respectively. The star wheel is not in contact with the chain  30 , but is rather vertically offset from the surface of the chain  30 , and the rotation of the chain is independent of the rotation of the star wheel  20 . 
     The star wheel  20  comprises a number of indents around its perimeter, each indent being sized and shaped to be complementary to a portion of the lugs  22  protruding interior of the path of the chain  30 . Thus it is possible for a lug  22  to sit upon the chain  30 , whilst located in one of the indents in the perimeter of the star wheel  20 . An outer guide  28  follows a path of constant offset from the exterior surface of the chain  30  and abuts a part of the aforementioned protruding portions of the lugs  22 , so as to restrain the lug  22  from separating from the indent in the star wheel  20 . 
     The indents in the star wheel  20  serve to trap the lugs  22  when the star wheel  20  is not rotating. When this happens, the chain  30 , if rotating, slides through the aforementioned channel in the lugs  22  by overcoming the friction between the lug  22  and the chain  30 . As the star wheel  20  turns, the combination of the rotational force of the star wheel  20  and that of the chain  30  serves to drives any lugs located in the aforementioned indents around the path of the guide  28 . 
     The indents in the perimeter of the star wheel  20  are shaped such so as not to foul the path of the lugs  22  as the chain diverges away from the star wheel  20 . The guide  28  continues to follow the chain  30  at a fixed offset, and therefore it too diverges from the perimeter of the star wheel  20 , thus freeing the lug  22  to separate from the indent. 
       FIGS. 1 ,  3 A and  3 B specifically illustrate the point in the process before the aforementioned separation begins to occur. The latch  24  is preferably hinged to the body of the lug  22  toward its leading edge.  FIGS. 2 ,  3 A and  3 B show how an activating assembly in the form of a runner  32  having a tapered end may be arranged so as to come into contact with the latch  24  before the lug becomes separated from the star wheel  20 . As the latch  24  comes into slicing contact with the tapered edge of the runner  32 , the latch  24  is activated or pivoted up into engagement with the chain  30 , thus securing the lug  22  onto the chain  30 . 
     The latch  24  is preferably resiliency biased away from the chain  30  by means, for example, of a spiral spring  31  disposed around the pivot  26 , so as to resist the hinging of the latch  24  into a position of engagement with the chain  30  For this reason, if is necessary that the latch  24  be brought into a position of engagement before separation of the lug  22  from the star wheel  20  is complete, so that sufficient driving force from the star wheel remains acting upon the lug to overcome the resistance of the resilient bias. 
     Once the latch  24  has bean entered into a position of engagement with the chain  30 , the force of the resilient bias encourages the latch  24  to hinge away from the chain  30  and therefore disengage the lug  22  from the chain  30 , as shown in  FIGS. 2 ,  4 A and  4 B. This disengagement is prevented by the fixed offset between the runner  32  and the guide  28 . The guide  23  maintains a sliding contact with parts of the protruding portions of the lug  22  whilst the runner  32  maintains a sliding contact with parts of the latch  24 , thus combining to prevent the latch  24  from hinging away from the lug  22 . The lug is consequentially sandwiched between the runner  32  and the guide  28 , and is driven along the length of the two by the chain  30  to which it is secured. 
     Thus, the lugs  22 , once secured, are ready to perform operations well known in the art such as grouping articles. Most chain driven systems employ art endless chain, and therefore at some point the lugs  22  will return to the star wheel  20 . Before this occurs, the runner  32  terminates so as to allow the lugs  22  to disengage from the chain  30 . Friction between the friction block  25  and the chain  30  suffices to drive the lugs  22  around the remainder of the path of the chain, and back to the star wheel  20 . 
     Once the disengaged lugs  22  reach the start wheel  20 , they will be impeded by either the surface of the star wheel  20  or another lug  22 , at this point the chain  30  will overcome the friction of the friction block  25  and the lug  22  and will begin to slip beneath the lug  22 . Therefore it is possible for the lugs  22  to queue, with the chain  30  passing beneath them, until such time as the star wheel  20  is positioned so as to align an indent in its perimeter with a lug  22  at the head of the queue. Friction between the lug  22  and the chain  30  exerts sufficient force on the lug  22  to locate it in the indent, and thereafter above process begins again. 
     Beside the star wheel  20 , the positioning means further includes a wheel-driving means  36  (e.g., a servomotor) and an electronic control means  33  (see  FIG. 1 ). The star wheel  20  is rotated by the wheel-driving means  38  independently of the rotation of the chain  30 . The wheel-driving means  36  is controlled by the control means  38  to adjust the rotational speed of the star wheel  20  relative to the rotational speed of the chain  30 . The control means  38  monitors the rotational speed of the chain  30  through the chain-driving means  21  and use the monitored rotational speed of the chain  30  to adjust the rotational speed of the star wheel  20  and/or to control the chain-driving means  21  itself to adjust the rotational speed of the chain  30 . By this means, the positioning means is capable of controlling at exactly which point along the chain  30  the lug  22  is secured, and thus allowing varying separation distances (i.e., the pitch) between successive lugs. The rotational speed of the star wheel  20  relative to that of the chain  30  dictates the change in pitch between the lugs  22 . If the star wheel  20  is controlled to rotate faster than the chain  30 , the pitch will reduce, whilst if the star wheel is controlled to rotate slower than the chain  30 , the pitch will increase. During the normal operation of the lug chain apparatus, the control means  38  also controls the rotation of the star wheel  20  so as to ensure that the protruding portion  25  of the latch  24  is always located into a link in the chain  30 . 
     As the desired spacing between the lugs  22  on the chain  30  increases, the total number of lugs  22  which may be located on the chain  30  at any one time will decrease. The aforementioned queuing of lugs  22  enables surplus lugs  22  to wait until they are required, without any need for user intervention or for deactivation of the chain in order to remove them. 
     The above description relates to a preferred embodiment of a lug  22  and a lug chain apparatus into which it is incorporated. It is, however, contemplated that other embodiments of the lug or the lug chain apparatus may be employed without departing from the scope of the present invention, in particular, the way in which a friction fit is achieved between the lugs  22  and the chain  30  may be achieved in any way known in the art. Moreover, the present invention is not limited to strictly chain driven systems, and may well be employed on belt driven systems also. The particularities of the latch herein described may also be altered so as to suit the chain or belt being used.