Patent Publication Number: US-2012027562-A1

Title: Machine system and method for transferring and grouping articles and packaging machine

Description:
This application claims priority to Italian Patent Application BO2010A000490 filed Jul. 30, 2010, the entirety of which is incorporated by reference herein. 
     This invention relates to a system and a method for transferring and grouping articles, in particular food articles which have a mainly flat extension. 
     The invention also relates to an automatic machine for packaging articles which comprises the same system for transferring articles. 
     In the food industry there are various prior art system for transferring and grouping articles for packaging purposes. 
     For example, patent EP0709289 in the name of Cavanna S.p.A. describes a system for transferring articles and forming stacks of articles in a plant for the automatic packaging of food products. 
     The device comprises a multi-way system for transferring articles, that is to say, using two or more transfer lines. 
     Associated with each transfer line there is a loading hopper in which the articles are positioned in stacks. 
     Moreover, each transfer line comprises a pusher designed to cyclically push a set of articles which are positioned at the bottom of the stack, and a conveyor unit comprising a plurality of contact elements, known to experts in the field as “flights”, which transfer the set of articles, fed by the pusher, along a substantially straight path. 
     In said transfer system the transfer lines release the articles to an outfeed conveyor extending at a right angle to the transfer lines. 
     Each transfer line releases the articles to an outfeed conveyor at its own release region and at a predetermined release height, both different to those of the other lines. That layout of the transfer lines and that height offset between the lines means that the various sets of articles released by the transfer lines are superposed in the outfeed conveyor, thus forming a stack of articles, made up of sets of articles from different transfer lines. 
     The stack of articles is designed to be inserted, downstream of the outfeed conveyor, in a corresponding package. 
     One disadvantage of that transfer and grouping system is that it cannot guarantee sufficient reliability. 
     If one of the pushers of the transfer lines feeds an incorrect number of articles (for example more or less than a predetermined number), the transfer and grouping system performs incorrect stacking of the articles at the outfeed conveyor which, in the most serious cases, causes the machine to stop and in any case produces, at outfeed, packages with an incorrect number of articles in them. 
     Moreover, the transfer device is quite complex, in particular requiring many adjustments for change-over, due to the presence of a plurality of transfer lines whose plan layout and height must be suitably adjusted. 
     Therefore, the aim of this invention is to propose a system and a method for transferring and grouping articles which are simple and reliable and which overcome the above-mentioned disadvantages. 
     Another aim of this invention is to propose a machine for packaging articles which is simple and highly reliable. 
     Accordingly, this invention achieves that aim with a system and a method for transferring and grouping comprising the technical features described in the appended claims. 
    
    
     
       The technical features of the invention, with reference to the above aims, are clearly described in the claims below and its advantages are more apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate a preferred embodiment of the invention provided merely by way of example without restricting the scope of the inventive concept, and in which: 
         FIG. 1  is a side view of a packaging machine comprising a system for transferring articles in accordance with this invention; 
         FIG. 2  is an enlarged side view of a detail H of the machine of  FIG. 1 ; 
         FIG. 3  is an enlarged side view of another detail K of the machine of  FIG. 1 ; 
         FIG. 4  is an enlarged side view of yet another detail J of the machine of  FIG. 1 ; 
         FIGS. 5 and 6  illustrate respective side views of a detail of the machine of  FIG. 1  in as many configurations; 
         FIG. 7  is an enlarged side view of a detail of the machine of  FIG. 1 . 
     
    
    
     With reference to the accompanying drawings, the numeral  100  denotes a machine for packaging articles A, in accordance with this invention, and the numeral  1  denotes a system for transferring and grouping articles A also in accordance with this invention. 
     In particular, the machine  100  is designed to package articles A which have a mainly flat extension, preferably food articles such as crackers. 
     The following is a description, by way of example only and without limiting the scope of the invention, of the packaging machine  100  in its entirety. The description also indicates the advantages and technical—functional features of the transferring and grouping system  1  integrated in it. 
     It should be noticed that the transferring and grouping system  1  advantageously can also be associated with, that is to say, can be integrated in, other types of machines. 
     Therefore, in light of this, again it should be noticed that the example described below is provided by way of example only, without in any way limiting the scope of the invention. 
     The machine  100  is described below relative to the flow of articles A through it, that is to say, from the infeed I to the outfeed U of the machine  100 . 
     The machine  100  comprises a frame  4 , designed to support the elements and parts of which the machine  1  consists, described in more detail below. 
     The frame  4  preferably comprises a plurality of tubular elements  5  which are interconnected in such a way as to create a supporting structure. 
     According to the invention, the machine comprises a vibrating channel  2  forming a channel LA for accumulation of articles A. 
     In particular and without limiting the scope of the invention, the vibrating channel  2  comprises a first stretch  2   a  and a second stretch  2   b.    
     The first stretch  2   a  is preferably substantially horizontal. 
     The first stretch  2   a  is designed to feed the articles A in a direction of feed labelled D 1 , whilst the second stretch  2   b  is set at an angle to the first stretch and is designed to feed the articles in a direction of feed labelled D 2 . 
     The vibrating channel  2  comprises respective actuator means  3  designed to make the channel  2  vibrate. The actuator means  3  are of the known type and therefore are not described in detail. 
     Preferably, as is clearly shown in  FIG. 1 , the articles A are fed along the vibrating channel  2  in contact with each other. 
     Said feed arrangement is also referred to in this description as “on edge”, this expression meaning that the articles A are arranged in such a way that the faces F of the articles A with the largest flat extension are in contact with each other and the articles are fed in a direction that is perpendicular to the plane in which said faces F extend. 
     According to the invention, the machine  100  comprises a wheel  6 , clearly visible in  FIG. 2 , designed to pick up articles A from the vibrating channel  2 . 
     In light of this, it should be noticed that, in the example illustrated, the wheel  6  is positioned at the end  29  of the second stretch  2   b  of the vibrating channel. 
     The wheel  6  comprises a plurality of recesses  8  extending radially which form corresponding cavities  7  designed to receive the articles A. 
     It should be noticed that each cavity  7  is shaped to hold one article A. 
     According to the invention, the wheel  6  is designed to pick up one article at a time from the vibrating channel  2 , at the region labelled R 1  in  FIG. 2 . 
     The wheel  6  is made to rotate, in the direction of rotation labelled W 1  in  FIG. 2 , by respective actuator means (not illustrated). 
     The cavities  7  are preferably spaced in such a way that they are separated from each other by an angle α. This allows the articles A to be spaced along the outside of the wheel  6  by a predetermined distance which depends, according to a known geometric relationship, on the diameter of the wheel  6  and the angle α. 
     The machine  100  also comprises a conveyor unit  9 . 
     The conveyor unit  9  is designed to receive the articles from the wheel  6 . 
     The conveyor unit  9  preferably comprises a first belt conveyor  9   a , positioned to receive articles from the wheel  6 , and a second belt conveyor  9   b  positioned to receive articles from the first belt conveyor  9   a.    
     The conveyor unit  9  in its entirety forms a feed line LB for a flow of articles A. 
     By way of example and without limiting the scope of the invention, the articles are conveyed along the feed line LB one after another, in such a way as to form a flow of articles A. 
     In particular, it should be noticed that the articles A are positioned with the face F having the largest flat extension in contact with the surface of the upper branches of the belts of the belt conveyors  9   a  and  9   b.    
     The first conveyor  9   a  of the conveyor unit  9  is designed to receive the articles A from the wheel  6 , as is clearly shown in  FIG. 2 . 
     The wheel  6  releases the articles A onto the upper branch of the belt  10  of the first conveyor  9   a , spacing them at a predetermined spacing P* (in a geometric relationship with the angle α and with the diameter of the wheel  6 ). 
     It should be noticed that, in accordance with the invention, the wheel  6  forms a device S which is operatively positioned between the accumulation channel LA and the feed line LB for picking up articles A one at a time from the accumulation channel LA and releasing them to the feed line LB according to a predetermined spacing P*. 
     The belt  10  of the first conveyor  9   a  is trained around a plurality of pulleys, labelled  11 . 
     One of the pulleys  11 , individually labelled  11   a , is connected to the actuator means  12  for the belt  10  so that it can be rotationally driven. The other pulleys  11  are preferably of the idle type. 
     The actuator means  12  for the pulley  11   a  preferably comprise a motor  13  and a belt  14  connecting the motor to the pulley  11   a.    
     As is clearly visible in  FIG. 3  the first conveyor  9   a  transfers the articles A in the direction labelled D 3 . 
     Preferably, according to the invention, the direction D 3  is parallel with the direction D 1 . 
     With reference to  FIG. 3 , R 2  denotes the transfer region where the first conveyor  9   a  releases the articles to the second conveyor  9   b.    
     The second conveyor  9   b  is preferably a belt conveyor, comprising an endless belt  47 . 
     The second conveyor  9   b  comprises, along the direction of feed for the articles A, a first portion  44  and a second portion  45  connected to each other by an articulated joint  41 , for allowing variation of the relative angular position of a first stretch T 1  and a second stretch T 2  of upper branch of the belt  40  associated with those portions  44 ,  45 . 
     In particular, it should be noticed that the first stretch T 1  is associated with the first portion  44  and the second stretch T 2  is associated with the second portion  45 . 
     Known means, not described in detail herein, keep constant the overall length of the upper branch of the belt  40  of the second conveyor  9   b , that is to say, the sum of the stretches T 1  and T 2 , lengthening or shortening one of the lower branches of the belt according to the relative angular position of the first stretch T 1  and the second stretch T 2  of the upper branch. That allows the tension on the belt  40  of the second conveyor  9   b  to be kept constant, avoiding excessive tensioning or loosening. 
     It should be noticed that the second conveyor  9   b  comprises a mobile pulley, individually labelled  42 , which is connected by a spring  43  to the first portion  44  which rotatably supports all of the other pulleys. 
     The pulley  42  and the spring  43  form means for maintaining a predetermined tension of the belt  40  of the second conveyor  9   b.    
     The first portion  44  of the second conveyor  9   b  is rotatably supported by the frame  4 . 
     In particular,  FIG. 3  shows how the first portion  44  is hinged to the frame  4  in such a way that the first stretch T 1  of the upper branch of the belt is free to rotate relative to the point labelled  30 . 
     In particular, the first stretch T 1  is designed to rotate between two limit positions, respectively a lowered position P 1  (illustrated in  FIG. 1 ) and a raised position P 2  (illustrated with a dashed line in  FIG. 1  and which, from the lowered position P 1  of  FIG. 1  and with reference to  FIG. 1 , is reached by means of a rotation in the direction labelled W 2 ). 
     The pivot point  30  is positioned at the end  16  of the second conveyor  9   b  close to the region R 2  where the articles A are transferred from the first conveyor  9   a  to the second conveyor  9   b.    
     It should be noticed that in the raised position P 2  (shown with a dashed line in  FIG. 1 ) the first stretch T 1  of the upper branch of the second conveyor  9   b  is inclined at an angle to a horizontal line. 
     As is clearly shown in  FIG. 4 , the second stretch T 2  of the second conveyor  9   b  is connected to a slider  18  which can move vertically (clearly visible in  FIG. 4 ) to allow movement of the second stretch T 2  between two limit positions, respectively lowered and raised. 
     The slider  18  is driven by actuator elements schematically illustrated and labelled  19  as a whole. 
     The slider  18  and actuator means  19  assembly forms means  17  for moving the first and second stretches (T 1 , T 2 ) of the upper branch of the belt  47  of the second conveyor  9   b  between the two limit positions P 1  and P 2 . 
     In particular, it should be noticed that the second conveyor  9   b  is designed in such a way that the slider  18  maintains unchanged the angle of the conveying direction D 5  of the second stretch T 2  relative to a horizontal plane. In other words, the angle of the second stretch T 2  relative to a horizontal plane is kept unchanged, irrespective of the position adopted by the slider  18 , whilst the angle of the first stretch T 1  relative to a horizontal plane depends on the position adopted by the slider  18 . 
     In other words, the conveying direction D 4  of the first stretch T 1  is modified, varying the angle relative to a horizontal plane, depending on the position of the slider  18 . 
     Therefore, the second conveyor  9   b  can release the articles A at a plurality of different heights for releasing the articles A. 
     Advantageously, the second conveyor  9   b  is able to convey the articles in such a way that on the second stretch T 2  they are positioned substantially with the face F having the largest flat extension lying in a horizontal plane. That advantageous technical feature is described in more detail below, with reference to machine  100  operation. 
     According to the invention, the machine  100  comprises a sensor  21  designed to detect the passage of the articles along the feed line LB. 
     The sensor preferably detects the passage of the articles A at a detection region R 5  positioned on the second stretch T 2  of the belt  47  of the conveyor  9   b.    
     The sensor  21  forms means  23  for counting the articles A along the feed line LB. 
     The machine  100  also comprises a station  20  for picking up and grouping the articles A, designed to pick up individual articles A from the feed line LB and to group them together. 
     The pickup and grouping station  20  is designed to pick up the articles A from the feed line LB and to group the articles A in such a way as to form groups G of articles A consisting of a predetermined number of articles A. 
     It should be noticed that, preferably, the groups G consist of the same number of articles A. 
     Hereinafter the groups G of articles A are also referred to using the term “groups”. 
     In particular, the station  20  for picking up and grouping the articles A is designed to stack the articles A. 
     As illustrated in  FIG. 5 , the articles A are positioned at the pickup and grouping station  20  in such a way as to form a vertical stack of articles A, that is to say, the articles are superposed one on top of another. 
     According to the invention, the machine  100  also comprises a unit  24  for transferring the groups G, set up to transfer the groups G from the pickup and grouping station  20  to a station  22  for releasing the groups G to an outfeed line LU, which is also part of the machine  100 . 
     It should be noticed that, in the embodiment illustrated, the pickup and grouping station  20  is formed at a region R 6  of the transfer unit  24 . 
     In particular, the transfer unit  24  forms the pickup and grouping station  20  at the region labelled R 6 . 
     According to the embodiment illustrated in the accompanying drawings, the transfer unit  24  is a conveyor unit  25  of the chain type. 
     The conveyor unit  25  comprises a pair of chains  26 , schematically illustrated in the accompanying drawings, trained around corresponding gear wheels ( 27   a ,  27   b ,  27   c ) and positioned side by side. 
     At least one  27   a  of the gear wheels ( 27   a ,  27   b ,  27   c ) is rotationally driven by actuator means  52 . 
     Each chain  26  is equipped with a plurality of contact and support elements  28  for the articles A, which are connected to the chain  26  and project towards the outside of the chain  26 . 
     According to the invention, the contact elements  28  more generally form first means  49  for picking up the groups G of articles. 
     Hereinafter the contact elements  28  are also referred to as contacts  28 . 
     It should be noticed that the contact elements  28  of the chains  26  form housings  34  for groups G of articles A. 
     In particular, the contact elements of the first chain  26  are labelled  28   a  and the contact elements of the second chain  26  are labelled  28   b.    
     In particular, by way of example and without limiting the scope of the invention, a group G is placed in a housing  34  formed by a contact element  28   a  of one of the two chains  26  and by a contact element  28   b  of the other of the two chains. 
     The fact that there are two chains  26  whose contact elements  28  operate in conjunction with each other to form the housings  34  for the groups G advantageously allows the transfer unit  24  to be rapidly and simply adapted for transferring groups G consisting of any number of articles A. The two chains  26  can be appropriately synchronised with each other in their direction of extension in such a way as to regulate, as required, the housing  34  space formed by the contact elements  28  of the two chains  26 . 
     The two chains  26  are preferably synchronised, that is to say, positioned relative to each other along their direction of extension, according to the methods described below:
         in accordance with a first synchronisation method, the contact elements  28   a  and  28   b  of the two chains  26  are aligned, along the direction of extension of the chains  26 , to form a housing  34  space with maximum amplitude for the groups G of articles A;   in accordance with a second synchronisation method (illustrated in  FIG. 4 ) the contact elements  28   a  and  28   b  are suitably offset along the direction of extension of the chains  26  in such a way as to form housings  34  with minimum amplitude which are identical, the minimum amplitude corresponding to around half of the maximum amplitude.       

     It should be noticed, with reference to the example in  FIG. 4 , that a stack of articles A forming a group G is supported by one of the contact elements  28   a  (positioned downstream relative to the direction of feed W 3  of the chains  26 ) of one of the two chains  26 , whilst a contact element  28   b  of the other chain  26  (positioned upstream relative to the direction of feed W 3  of the chains  26 ) acts as an element delimiting the housing  34  and is designed to support the next group G. 
     According to an alternative embodiment not illustrated in the accompanying drawings, the conveyor unit  25  comprises a single endless chain  26 , equipped with a plurality of contact and support elements  28  for the articles A which form the housings  34  for the groups G. 
     In accordance with said alternative embodiment, a group G of articles A is intended to occupy the housing  34  made available by a pair of adjacent contact elements  28  along the endless path on which the chain  26  extends, according to methods similar to those described above. 
     The conveyor unit  25  is set up to release the groups G of articles A at a releasing station, labelled  22  and more clearly visible in  FIG. 4 . 
     The conveyor unit  25  also comprises a guide  31 . 
     According to the example illustrated, the guide  31  is fixed to the frame  4 . 
     The guide  31  allows the groups G of articles A to be guided along a path for conveying the groups G formed by the conveyor unit  25  between the pickup and grouping station  20  and the releasing station  22 . Therefore, the guide  31  prevents the articles A from falling as the articles A are transferred from the pickup station  20  to the releasing station  22 . 
     Moreover, it should be noticed that the conveyor unit  25  transfers the groups G from the pickup and grouping station  20 , in which they are stacked vertically, and releases them at the releasing station  22  in an “on edge” arrangement. 
     In light of this, it should again be noticed that the conveyor unit  25  transfers the groups G according to a direction of feed on edge. 
     The machine  100  outfeed line LB comprises, by way of example and without limiting the scope of the invention, a conveyor  32  of the type with a chain  35 . 
     The chain  35  forms an endless path between a pair of gear wheels ( 54   a ,  54   b ), of which one gear wheel  54   b  is driven by respective actuator means  53 . 
     The conveyor unit  32  also comprises a guide  36 , associated with it, extending on the outside of the endless path formed by the chain  35 . 
     The guide  36  preferably extends in such a way as to form an endless path. 
     The top of the guide  36  comprises a first stretch TG 1 , a second stretch TG 2  and a third stretch TG 3  connecting the first stretch TG 1  and the second stretch TG 2 . 
     The stretches TG 1 , TG 2 , TG 3  are preferably straight. 
     Even more preferably, the third, connecting stretch TG 3  is a stretch inclined at an angle to a horizontal plane. 
     The conveyor unit  32  also comprises a plurality of contact elements  33  for the groups G of articles A. 
     According to the invention and more generally, the contact element  33  form second means  50  for picking up the groups G of articles. 
     The contact elements  33  form a space for housing a group G of articles. 
     In particular, the conveyor unit  32  alternatively comprises a front contact element  33   a , designed to make contact with the front of a group G of articles, that is to say, to delimit the front of the housing space, and a rear contact element  33   b , designed to make contact with the back of a group G of articles A, that is to say, to delimit the back of the housing space. 
     The following is a description of a preferred embodiment of the contact elements  33 . It should be noticed that said embodiment is shown purely by way of example and the contact elements  33  could have any structure/shape even different to that described, without departing from the protective scope of this description. 
     Each contact element  33  comprises a first portion  37 , fixed to the chain  35 , and a second portion  38  able to move relative to the first portion  37 . 
     According to the embodiment illustrated, the second, mobile portion  38  comprises means  39  for connecting to the guide  36 . 
     Therefore, more generally the second portion  38  is constrained to move along the path formed by the guide  36 . 
     Moreover, the second portion  38  comprises a projecting prong  40  designed to make contact with the group G of articles A. 
     It should be noticed that each group G of articles A, when it has been released by the conveyor unit  25 , is housed in a housing formed by a pair of contact elements ( 33   a ,  33   b ), respectively upstream and downstream with reference to the direction of feed of the groups Gin the outfeed line LU. 
     In this regard, it should be noticed that the outfeed line LU preferably transfers the groups G of articles on edge. 
     It should be noticed that the feed line LB, the pickup and grouping station  20 , the transfer unit  24 , the releasing station  22  and the outfeed line LU together form the system  1  for transferring and grouping articles A in accordance with this invention. 
     Preferably, downstream of the outfeed line LU, the machine  100  comprises a packaging station (schematically illustrated in  FIG. 1  and labelled  46 ) where the groups G of articles A are inserted in respective containers or sealed with flexible wrappers made of plastic material. 
     According to the invention, the machine  100  also comprises a control and actuator unit  51 , hereinafter referred to as the control unit  51 , which is connected to the conveyor unit  32  of the outfeed line LU and to the transfer unit  24 . 
     Moreover, preferably, the control unit  51  is also connected to the sensor  21  and to the feed line LB, in particular to the movement means  17  of the second conveyor  9   b.    
     Below is a description of packaging machine  100  operation with reference to the packaging of a group G of articles A. 
     The sequence of steps described below is illustrated in  FIGS. 5 and 6  which represent, by way of example, a preferred method of operation of the machine. 
     It shall be understood, from the following description, that the machine  100  and in particular the transfer system  1  may be operated, according to the invention, even in accordance with methods other than those described. 
     The wheel  6 , rotationally driven in the direction of rotation W 1 , cyclically picks up individual articles A and releases them to the first conveyor  9   a  which in turn releases them to the second conveyor  9   b.    
       FIGS. 2 and 3  show how the conveyors  9   a  and  9   b  convey an orderly flow of articles A (that is to say, a flow of articles A spaced at a constant spacing P*). However, that does not limit the scope of the invention, since according to the invention the articles could also be fed randomly or with variable spacing. 
     The sensor  21  counts the number of articles A passing along the feed line LB and sends a corresponding signal S 4  to the control unit  51 . 
     The control unit  51  drives, that is to say, activates, the actuator means  19  for the slider  18  of the second conveyor  9   b  by means of an output signal S 3  according to the methods described below. 
     In light of this, it should be noticed that, with each article A detected by the sensor  21  passing in the detection region R 5 , the second stretch T 2  of the second conveyor  9   b  is moved upwards by a distance corresponding at least to the thickness of one article A, in such a way as to allow the articles A to be stacked, forming the group G. 
     It should be noticed that from the signal S 4  the control unit  51  is able to count the number of articles A inserted in the housing  34 , that is to say, released from the feed line LB, and the number of articles A which still need to be inserted in order to complete the group G. 
       FIG. 5  shows a machine  100  configuration in which a group G has been completed in the housing  34  of the conveyor unit  25  at the pickup and grouping station  20 . 
     In  FIG. 5 , the control unit  51  has already activated movement of the conveyor unit  25  in such a way that it is suitably synchronised with the outfeed line LU. 
     It should be noticed how the control unit  51  has already sent an output signal S 2  to the actuator means  52  for the conveyor unit  25 . 
     The signal S 2  is a signal for activating the conveyor unit  25 . 
     It should be noticed how, in general, the control unit  51  activates the movement of the conveyor unit  25 —by means of the signal S 2 —subject to a signal S 1  input into the control unit  51  and arriving from the outfeed line LU. 
     The signal S 1  is a signal indicating a cyclical sequence of the positions for picking up the groups G of articles A which are gradually reached by the second pickup means  50  relative to the first pickup means  49 . 
     That idea is explained in more detail below. 
     In other words, it should be noticed that, during the movement of the conveyor unit  32 , the second pickup means  50  (that is to say, the contact elements  33   a  and  33   b ) move to a pickup position relative to the first pickup means  49 . 
     During a complete rotation of the conveyor unit  32 , each pair of contact elements, front  33   a  and rear  33   b , forming the second pickup means  50 , is located, relative to the first pickup means  49 , in a position for picking up the group G in which the control unit sends the signal S 3  for activating the actuators  52  for the conveyor unit  25 . 
     The fact that the conveyor unit  32  comprises a plurality of pairs of front and rear contact elements  33   a ,  33   b , each forming the second pickup means  50 , in general means that in a complete rotation of the chain  35  of the conveyor unit  32  there is a sequence of pickup positions which are gradually reached by each pair of contact elements  33   a ,  33   b —that is to say, second pickup means  50 —present on the conveyor  32 . 
     Therefore, preferably, the signal S 1  from the outfeed line is a signal of the ON/OFF type which adopts the ON value when one of the individual pickup devices  50  has reached a pickup position relative to the first pickup means  49 . 
     According to an alternative embodiment, the signal S 1  is a signal indicating the position of one of the two gear wheels  54   a ,  54   b , for example deriving from an encoder. 
     Preferably, if the conveyor unit  32  is operated at a constant speed, the signal S 1  is a cyclical signal. 
     To better illustrate that idea, it is assumed that the conveyor unit  25  is immobile, that is to say, not activated. 
     The passage of one of the front contact elements  33   a  at a predetermined position relative to the contact elements  28  which retain the group G 1  at the releasing station  22 , causes activation of the conveyor unit  25  which, from that moment, begins moving in such a way that it is suitably synchronised with the conveyor unit  32 . 
     In that sense, in light of the above, it is clear how the signal S 2  is subject to the signal S 1 . 
     From the moment it is activated, the conveyor unit  25  is controlled in such a way that it is in a phase relation with the conveyor  32 , that is to say, the speed of the conveyor unit  25 —or more generally the speed profile of the conveyor unit  25 —is a predetermined relation with the speed of the conveyor  32 —or more generally with the speed profile of the conveyor  32 . 
     This allows a group G of articles to be released by the first pickup means  49  to the second pickup means  50  according to a well-defined step. 
     In general the conveyor unit  25  is activated with constant steps, that is to say, at each activation cycle of the conveyor unit  25 , each contact element  28 , when the conveyor is stopped, occupies the position that was previously occupied, before the activation cycle, by the contact element  28  now located downstream relative to the direction of feed W 3  of the conveyor unit  25 . 
     With reference to the specific example illustrated in  FIGS. 5 and 6 , the control unit  51  activates the conveyor unit  25  when a front contact element  33   a  of the conveyor  32  is passing in the third, angled stretch TG 3  of the upper branch of the guide  36 . 
     It should be noticed that when the front contact element  33   a  of the conveyor  32  passes in the angled stretch TG 3  the projecting prong  40  is positioned at a height greater than that of the surface  48  on which the articles A rest. 
     Activation of the conveyor unit  25  therefore allows the group labelled G 1  to follow the front contact element  33   a  of the conveyor  32  in such a way that the first article A of the group G 1  is brought into contact with the front contact element  33   a  of the conveyor  32 . 
     It should be noticed that at the region labelled R 7  the front contact element  33   a  of the conveyor  32  makes contact with the first article of the group G 1  and the contact element  28   a  of the conveyor unit  25  abandons contact with the first article. In that region R 7  there is no interference between the front contact element  33   a  and the contact element  28   a , since the contact elements ( 33   a ,  28   a ) are suitably shaped relative to each other. 
     By way of example and without limiting the scope of the invention, according to a front view, the contact element  28   a ,  28   b  of the conveyor unit  25  has two prongs and has the shape of an inverted U. This allows the projecting prong  40  to be inserted in the recess formed by the inverted U, at the region R 7 , without any interference between the contact elements  33   a ,  28   a  and  28   b.    
     The conveyor unit  25  is suitably driven in such a way that it is synchronised with the outfeed line LU so that, at the angled stretch TG 3  of the guide  36 , the rear contact element  33   b  of the conveyor is inserted in the space between the two groups (see  FIG. 6 ) labelled G 1  and G 2 . In particular, it is inserted at the contact element  28  which for clarity is individually labelled  280 . 
     As a result of engagement of the rear contact element  33   b  of the conveyor  32  with the group G 1 , the conveyor  32  feeds the group G 1  forwards. 
     The operations described above by way of example form a step of releasing a group G from the first pickup means  49  to the second pickup means  50 . 
     It should be noticed that once the release operation is complete, the control unit  51  can disable the conveyor unit  25 . 
     The cycle for transferring a group G from the conveyor unit  25  to the conveyor  32  is repeated in the manner according to the methods described above, for the next group of articles (that is to say, for the group G 2  in  FIG. 5 ). 
     It should be noticed that the second stretch T 2  of the conveyor  9   b  is moved vertically according to detection of the passage of an article A in the detection zone R 5  and according to the movement of the conveyor unit  25 . 
     According to said aspect, when the conveyor unit  25  is moved to release the group G to the outfeed line LU, the second stretch T 2  is moved downwards to follow the movement of the housing  34  and so that the articles A arriving can be inserted in the housing in the correct position. 
     Moreover, the second stretch T 2  is moved vertically upwards according to the increase in the articles A detected by the sensor  21 , that is to say, arriving towards the pickup and grouping station  20 . 
     It should be noticed that the upward vertical movement of the second stretch T 2  is a motion for stacking the articles A, performed as an article A passes in the zone R 5  for detection of the passage of an article A by the sensor  21 . 
     Therefore, the second stretch T 2  is moved according to a law of motion comprising a downward vertical movement following the conveyor unit  25 —preferably continuous—and an upward vertical movement, that is to say, opposite to the previous movement,—which is usually intermittent. 
     More generally, the movement of the second stretch  9   b  resulting from overlapping the downward vertical following movement and the stacking vertical movement is preferably a movement of the continuous type with variable speed. 
     It should be noticed that the two vertical movements may or may not be combined (that is to say, one of the two movements may not be performed, for example because no articles A arrive along the feed line LB or because the conveyor unit  25  is not operated). 
     In general, the second stretch T 2  is moved according to the signal S 4 , that is to say, due to an increase in the count of articles A, and the signal S 2 , which indicates the movement of the conveyor unit  25 . 
     Therefore, more generally, the second stretch T 2  is moved according to the arrival of an article A in the pickup and grouping station  20  and according to the movement of the conveyor unit  25 . 
     The following are some general considerations regarding the machine  100  and the transfer system  1 . 
     It should be noticed that, in the absence of articles A, that is to say, groups G in the housings  34  of the conveyor unit  25 , the conveyor unit  25  preferably is not moved. 
     According to an operating method not illustrated, the conveyor  32  of the outfeed line LU may be operated according to any law of motion, that is to say, even at a speed that is not constant. In accordance with that embodiment, the conveyor unit  25  is activated and moved with a corresponding law of motion in such a way that it is possible to release at a predetermined step the groups G from the first pickup means  49  of the conveyor  25  to the second pickup means  50  of the outfeed line LU according to the methods described above. 
     The advantage of this invention is apparent from the above description. 
     According to the invention, the transfer system  1  allows the articles to be transferred from an infeed line LB to an outfeed line LU, simultaneously grouping the articles A. 
     Advantageously, the outfeed line may be operated using any law of motion (obviously, provided that the speeds of the outfeed line LU allow, depending on the release rate of articles A from the feed line LB to the conveyor unit  25 , the transfer of the groups of articles A between the line LB and the outfeed line LU). 
     Moreover, according to another advantageous aspect of the invention, the transfer system  1  allows a situation in which it can be guaranteed that each group G will consist of precisely the predetermined number of articles A. 
     According to an alternative embodiment, not illustrated in the accompanying drawings, the conveyor unit  25  is designed to transfer containers to the pickup and grouping station  20 . 
     In accordance with that alternative embodiment, the articles A are stacked directly in a container at the grouping and pickup station and are transferred to the releasing station  22  in the container. 
     The invention described above is susceptible of industrial application and may be modified and adapted in several ways without thereby departing from the scope of the inventive concept. Moreover, all details of the invention may be substituted by technically equivalent elements.