Abstract:
A machine for forming a stream of articles (A) into spaced groups of articles, which machine has a working reach and a metering element ( 10 ) for being brought into contact with an article (A) passing, in a stream, into the working reach, which metering element ( 10 ) is driven by a drive means ( 18 ), wherein a speed at which the metering element ( 10 ) is driven is retarded as the metering element ( 10 ) enters the working reach without retarding the drive means ( 18 ).

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to apparatus for metering articles into spaced groups. More specifically, though not exclusively, the present invention relates to apparatus that brings a metering element into contact with articles in a stream and accelerates those articles relative to the stream, so as to form a spaced group. Yet more specifically, though not exclusively, the present invention relates to apparatus that retards the speed of the metering element, as it is brought into contact with those articles, so as to limit the forces to which the articles are exposed, before accelerating the metering element to form the spaced group. 
       BACKGROUND OF THE INVENTION 
       [0002]    A common requirement of the packaging industry is the requirement to meter streams of articles into smaller groups of articles, which group may preferably be spaced from one another by desired distances. This metering can, for example, be highly advantageous when each group is to be loaded into a separate container. 
         [0003]    A well known method for creating and spacing group of articles is to use a metering apparatus, which apparatus comprises a metering element that is brought into contact with one or more articles in the stream and then accelerates some portion of the articles in the stream to form a group. However, the relative difference in motion between the metering element and the articles in the stream leads to a high impact force being imparted onto the articles at the moment of contact, which may cause damage to the apparatus or the articles themselves. 
         [0004]    WO 02/064464 to Davaillon provides a grouping device for articles to be loaded into a carton having spacer elements to engage articles in a stream of articles for separating the stream of articles into discrete groups having two modes of operation. 
         [0005]    There is, therefore a requirement for an apparatus that can control the speed of the metering element, relative to that of the articles with which it is to come into contact, so as to reduce the impact forces imparted to those articles. The fact that the packaging industry requires very high rates of throughput and minimal down time further introduces a requirement for the apparatus to be extremely robust and capable of metering articles at high speed. 
         [0006]    The present invention seeks to over come or at least mitigate the disadvantages of the prior art, in providing an apparatus directed to the above requirements. 
       SUMMARY OF THE INVENTION 
       [0007]    A first aspect of the present invention provides machine for forming a stream of articles into spaced groups of articles, which machine has a working reach comprises a metering element for being brought into contact with an article passing, in that stream, into the working reach, and further comprises a drive means for driving the metering element, wherein a speed at which the metering element is driven is retarded as the metering element enters the working reach without retarding the drive means. 
         [0008]    Preferably, the machine comprises a metering element slidably disposed upon a conveyor means and comprises a portion for making contact with one or more of the articles of the stream, which conveyor means propels the metering element in a first direction at a first speed, and wherein the portion is displaceable relative to the conveyor means such that the contact is made, the displacement of the portion being angled with respect to the first direction such that the portion is caused to have a second speed in the first direction during that displacement, substantially equal to a third speed, which third speed is that possessed by the articles of the stream, when the contact is made, and wherein the first and third speeds are different. 
         [0009]    Preferably, the displacement of the portion ceases once the contact is made, at which point the portion returns to the first speed, thereby accelerating the one or more articles from the third speed to the first speed. 
         [0010]    Optionally, the machine comprises a shaped cam path that is followed by the portion, and which shaped cam path therefore controls the displacement of that portion. 
         [0011]    Preferably, a section of the shaped cam path is angled relative to the direction of the first speed, which angle alters the difference between first speed and the second speed. 
         [0012]    Optionally, the displacement takes place in a direction that is at an angle to the direction of the first speed, which angle alters the difference between first and second speeds. 
         [0013]    Optionally, each metering element comprises a cam follower element that follows the shaped cam path. 
         [0014]    Optionally, the machine comprises more than one metering element. 
         [0015]    Optionally, each metering element comprises a comb connected to a carriage. 
         [0016]    Optionally, a spacing between any two articles of the stream may be altered as a result of altering the difference between the first and the third speeds. 
         [0017]    Optionally, the one or more articles for groups of articles, the sizes of which are alterable by altering the position in which the contact is made, further upstream of the motion of the stream of articles. 
         [0018]    A second aspect of the present invention provides a method for forming a stream of articles into spaced groups of articles, which method comprises providing a machine that has a working reach and that comprises a metering element for being brought into contact with an article passing, in the stream, into that working reach, driving that metering element using a drive means, and retarding a speed at which the metering element is driven, without retarding the drive means, at the point in which the metering element enters the working reach. 
         [0019]    Preferably, the metering element is slidably disposed upon a conveyor means and comprises a portion for making contact with one or more of the articles of the stream, which conveyor means propels the metering element in a first direction at a first speed, and wherein the said portion is displaceable relative to the conveyor means such that the contact is made, the displacement of the portion being angled with respect to the first direction such that the portion is caused to have a second speed in the first direction during that displacement, substantially equal to a third speed, which third speed is that possessed by the articles of the stream, when the contact is made, and wherein the first and third speeds are different. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0020]    Exemplary embodiments of the present invention will now be described by way of example only, with reference to the following figures, in which: 
           [0021]      FIG. 1  illustrates a machine for metering articles, according to one aspect of the present invention; 
           [0022]      FIG. 2  illustrates a portion of the machine of  FIG. 1 , in plan view; 
           [0023]      FIGS. 3 to 6  sequentially illustrate the operation of an exemplary embodiment of a machine for metering articles, according to one aspect of the present invention; and 
           [0024]      FIGS. 7 to 10  sequentially illustrate the operation of another exemplary embodiment of a machine for metering articles, according to another aspect of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    The present invention provides a system for grouping and spacing articles A that are conveyed through the working reach of the system in a stream from an in-feed end, as best illustrated in  FIG. 1 . The stream of articles A pass parallel to a conveyor means of the machine, upon which are mounted metering elements, which metering elements are displaced toward and brought into contact with one or more of the articles A in the stream, thereby to select those articles A. The selected articles are then accelerated relative to the remainder of the stream of articles A so as to form a spaced group. 
         [0026]    The system  2  of  FIGS. 1 and 2  comprises a plurality of metering elements in the exemplary form of combs  10 , connected to respective carriages  8 , via connecting portions  12 . Each carriage  8  is disposed upon a conveyor means  18 , adjacent and parallel to which passes a stream of articles A travelling at a velocity of V 1 . In the illustrated embodiment, the conveyor means  18  is a conveyor belt, and is driven by some mechanical provision, such as a motor, as is well known in the art. This exemplary conveyor means  18  rotates to propel the carriages  8  along its longitudinal axis, at a velocity V 2  that is greater than, and substantially parallel to, the velocity V 1  of the articles A. 
         [0027]    Each carriage  8  is mounted upon the conveyor means  18  in a slidable manner, such that it may be reciprocally displaced along a line of displacement  16 , relative to the conveyor means  18 , whilst maintaining a mechanical connection thereto. The specific embodiment of the slidable connection is not essential to the present invention and it is contemplated that one skilled in the art would readily apply one of numerous techniques known in the art to accomplish such functionality. However, in the example shown, the carriage  8  slides between a pair of guide rails (not illustrated). The line of displacement  16  and arrangement of the carriages  8 , connection portions  12 , and combs  10  is such that the carriage  8  may slide along that line of displacement  16  so as to bring a corresponding comb  10  into, and out of, contact with one or more articles A in the stream. 
         [0028]    The system  2  further comprises a cam arrangement that comprises a shaped cam path  14 , which cam arrangement is fixed in position and does not move with the rotation of the conveyor means  18 . Each carriage  8  comprises some form of cam follower means  20 , various implementations of which are readily understood by those skilled in the art. Through interaction between the cam follower  20  and the shaped cam path  14 , displacement of the carriage  8  along the line of displacement  16  is effected. The exact embodiments of the shaped cam path  14  and the cam follower  20  are not essential features of the present invention and it is contemplated that one skilled in the art would readily employ one of numerous solutions known in the art to provide such functionality. 
         [0029]    Preferably, the line of displacement  16  is angled with respect to a longitudinal axis of the conveyor means  18 . In the exemplary embodiment of  FIG. 2 , this angle is denoted by a (a best shown in  FIG. 2 ) and is greater than 90°. 
         [0030]    The displacement of the carriage  8  along the line of displacement  16  can be thought of as comprising two components: a first component lying in the direction of velocity V 2  of the carriage; and a second component lying in a direction 90° thereto, transverse to the conveyor means  18 , serving to bring the carriage  8  closer to the stream of articles A. The significance of these two components of the displacement is discussed in detail below. 
         [0031]    In the exemplary embodiment, the profile of the shaped cam path  14  extends along the length of the conveyor means  18  substantially parallel to the longitudinal axis thereof; a first portion  30  being offset further from the stream of articles, and a second portion  34  being offset closer to the stream of articles. The junction between the first and the second portions of the shaped cam path  14  follows an ‘S-bend’ in transition region  32  that extends from a terminus of the first portion  30  to a terminus of the second portion  34 . A substantial portion of the ‘S-bend’ in transition region  32  is substantially straight and inclined between the two aforementioned termini. As the carriage  8  is propelled at velocity V 2 , by the conveyor means  18 , so the cam follower  20  of that carriage  8  follows the profile of the shaped cam path  14 . As that shaped cam path  14  causes the cam follower  20  to move toward to stream of articles A, so the carriage  8  is caused to slide along the line of displacement  16 . 
         [0032]    If the line of displacement  16  were to lay parallel to a transverse axis  17  of the conveyor means  18 , then the displacement of the carriages  8  would serve only to bring the carriage  8 , and therefore the comb  10 , closer to the stream of articles A. However, the angle between the line of displacement  16  and the transverse axis  17  of the conveyor means  18  causes a component of that displacement to lay in the direction of motion of the conveyor means  18 . That component of the displacement relates to an additional velocity component V 3 ′ of the carriage  8  that is additive to V 2 . 
         [0033]    The additional velocity component V 3 ′ thus serves to speed up or slow down the motion of the carriage  8  relative to that of the conveyor means  18  and, more importantly, relative to the velocity V 1  of the stream of articles A. 
         [0034]    The angle α between the line of displacement  16  and the direction of the velocity V 2  of the conveying means  18  dictates the nature of the additional velocity component V 3 :
       If the angle is less than 90° , then the additional velocity component V 3 ′ will be positive with respect to V 2 .   If the angle is exactly 90° , then the additional velocity component V 3 ′ will be zero.   If the angle is greater than 90° , then the additional velocity component V 3 ′ will be negative with respect to V 2 .       
 
         [0038]    The present invention takes advantage of this relationship to decrease the difference between the velocity V 4  of the combs  10  and velocity V 1  of the stream of articles A, at a point at which they are brought into contact. The fact that the difference in these two velocities is minimized means that the forces to which the articles A are subjected at that point of contact are also minimised. Thus the articles A are less likely to become damaged and the overall process can be run at a higher throughput rates. This invention is particularly advantageous in that this result is achieved without any requirement for controllably slowing the conveyor means  18 , and thus provides a mechanically simple and robust system. 
         [0039]    In contrast, metering systems of the prior art often subject the articles A to high impulse forces as metering elements are brought into contact with them, and therefore suffer from frequent breakages of both the articles A and the metering elements themselves. 
         [0040]    The profile of the shaped cam path  14  is specifically adapted such that, at the point that the combs  10  are brought into contact with the articles A that form the next group, the corresponding cam follower  20  reaches the end of the ‘S-bend’ portion  32  of the shaped cam path  14  and begins to follow the second portion  34  thereof. Thus the carriage  8  ceases to move along the line of displacement  16 , and thereby ceases to exhibit any additional velocity component V 3 . Both the comb  10  and the carriage  8 , therefore, are caused to return to a velocity V 2  equal to that of the conveyor means  18 , which velocity is greater than velocity V 1  of the stream of articles A, and therefore results in an acceleration of the selected articles A to form a spaced group. 
       EXAMPLE 1 
       [0041]      FIGS. 3 to 6  illustrate one embodiment of the present invention, whereby the ‘S-bend’ in transition region  32 , of the shaped cam path  14 , follows a relatively straight line that is at an angle to the direction of motion of the conveyor means  18 . The figures sequentially illustrate the carriage  8 , initially moving with a first velocity V 4  equal to the velocity V 2  of the conveyor means  18 . As the ‘S-bend’ portion  32  of the shaped cam path  14  exerts a normal reaction force on the cam follower  20 , the carriage  8  is forced along the line of displacement  16 , thereby giving the comb  10  a total velocity that is equal to the sum of V 2  and V 3 , as is best illustrated in  FIGS. 4 and 5 . Also illustrated in those figures is velocity component V 3 ′, which corresponds to the component of velocity V 3  that lays in the same direction as V 2 . Velocity V 4  is the component of the total velocity of the comb  10  that lies in the same direction as velocity V 1  of the articles A and is equal to the sum of V 3 ′ and V 2 , wherein V 3 ′ is relatively small compared to V 2  and is negative. At the point at which the comb  10  is brought into contact with articles A, the velocity V 4  of the tools  10  is substantially equal to the velocity V 1  of the articles A. In this embodiment, the system  2  is adapted such that each comb  10  is brought into contact with four articles A, and accelerates them as the cam follower  20  moves along the second portion  34  of the shaped cam path  14  at velocity V 2 , to create a spacing between those articles A and the following group. 
       EXAMPLE 2 
       [0042]      FIGS. 7 to 10  illustrate another embodiment of the present invention, wherein the ‘S-bend’ portion in transition region  32  of the shaped cam path  14  is inclined at a greater angle to velocity V 2  than is the case in the embodiment described in the previous Example 1, and as a result, brings the combs  10  into contact with articles A in a shorter space of time.  FIG. 7  illustrates the carriage  8  moving at a velocity of V 2 , which velocity is greater than that V 1  of the stream of articles A. As the cam follower  20  of the carriage  8  reaches the inclined portion of the ‘S-bend’  32  of the shaped cam path  14 ,  FIG. 8  shows the carriage  8  beginning to slide along the line of displacement  16 . By the point illustrated in  FIG. 9  the carriage  8  and therefore comb  10  are moving with a speed in the direction of V 2  that is little greater than V 1 . This is because, in contrast to the embodiment of the previous Example 1, the shaped cam path  14  and line of displacement  16  in  FIG. 5  cause a velocity component V 3 ′ that is a substantial fraction of V 2 , and therefore reduces the velocity V 4  of the comb  10  by a greater amount. Thus, The comb  10  is brought into contact with articles A of the stream of articles A, with a velocity V 4  substantially equal to V 1 , and at this point the cam follower  20  begins to move along the second portion  34  of the shaped cam path  14 , thus reducing V 3 ′ to zero, and accelerating the comb  10 , and the selected articles A, to velocity V 2 . 
         [0043]    Once the desired grouping and spacing has been desired, one skilled in the art would readily understand that the comb  10  may be disengaged from the articles A by displacement, along the line of displacement  16 , away from those articles A. It will further be appreciated that the carriages  8  may follow some form of return path, such as the underside of the conveyor belt used as the conveyor means  18  in the Figures, or some other means known in the art, so as to be used for further grouping operations. 
         [0044]    Furthermore it will be appreciated that the shaped cam path  14  in Example 2 comprises round corners between the included portion of the ‘S bend’  32  and the shaped cam path in  14  regions  30  and  34  respectively. The rounded corners provide a smooth transition for the cam follower  20  to follow as it changes direction. This is especially important in the region where the cam follower  20  moves though the transition between the ‘S bend’  32  and second portion  34 , thereby smoothing effects of the greater velocity change experienced by the tools  10  in Example 2. 
         [0045]    The change of velocity experienced by the carriage  8  in Example 2 is significantly greater than that of Example 1 due to the reduction of the angle between the line of displacement  16  and the inclined portion of ‘S bend’  32 . The combs  10  therefore experience greater deceleration and acceleration in Example 2 than in Example 1. The provision of the rounded corners provides a smoothing of the transition by gradually reducing or increasing the velocity of the combs  10 . 
         [0046]    The embodiments of the system  2  that have been described above are exemplary in nature, and it is contemplated that the implementation of the various features described above may be altered within the scope of the invention as set out in the attached claims. As noted above, the conveyor means  18 , which is illustrated as a conveyor belt, may be any other sort of conveyor means capable of driving the carriages  8  along a path suitable for achieving the grouping operations described above. Additionally, the mechanical implementation of the connection between the carriages  8  and the conveyor means may also be adapted to include any slideable fixing known in the art. The metering elements  10  of the present invention are not limited to combs, and may use any form of metering element that is suitable for selecting and accelerating groups of articles A, such as lugs or overhead plungers. The exemplary embodiments have been illustrated in a horizontal plane, though it is contemplated that the same technique could be used to bring metering elements  10  into contact with the articles A in some other orientation. The two exemplary embodiments typified in  FIGS. 3 and 7  show two different shaped cam paths  14  and one angle for the line of displacement, relative to velocity V 2 , either of which may be altered so as to effect differing relative movement between the conveyor means  18 , carriages  8  and articles A.