BACKGROUND 
     The invention relates to equipment for continuously feeding boxes or containers, which are initially stacked in a flattened tubular configuration in the form in which they are received from a paper products factory, to a packaging machine which is, for example, of the straight-line or other continuously operating type. The most similar prior art to the equipment described here is represented by the international patent application WO 1992/015450 entitled “Feeder mechanism for sleeve type cartons” and European patent EP 1 597 150 granted on May 14, 2008, entitled “Apparatus for forming containers”. The first of these patents describes equipment for feeding containers to the cellular conveyor of a packaging machine, in which the magazine holding the stacked containers is downwardly open and is located above the initial part of the cellular conveyor, with a carousel located between these two components and having a horizontal axis orthogonal to the direction of operation of the cellular conveyor, a plurality of suction cup pick-up units being mounted on the carousel in a radial arrangement with equal angular intervals between them, and being positioned in a way which is controlled by cams. The carousel rotates in phase with the conveyor of the packaging machine and moves each of its pick-up units in sequence in order to grip a container, draw it out of the base of the magazine, move it downwards, interact with an opening means, and, after a rotation of about 180°, insert the substantially open container at the correct time into a cell being formed in the initial part of the underlying conveyor, the container being supported by the wall opposite that with which the container touches the base of the cell. The equipment therefore requires extremely complicated, time-consuming, difficult and costly adjustments whenever the format of the containers is changed. It is also difficult to adjust the equipment in order to avoid damage to the container during its transfer to the conveyor of the packaging machine, each cell of which must always be positioned so that it is open at the rear and must then be closed on the container which has been fed into it. Furthermore, the height of this equipment is considerable, making it necessary to position the container magazine at a very high level, creating difficulties in the cyclic restocking and in the control of operation. However, the equipment is capable of operating continuously at high speed. 
     The equipment described in the second of the aforementioned patents partially overcomes the drawbacks of the first equipment, in that it enables the magazine to be positioned at a very low level and the containers are inserted into the cells of the packaging conveyor with their lower walls retained by the same means as those used to extract the containers from the feed magazine. The container feed means are therefore required to move between two “zero” reference positions, namely the base of the feed magazine and the base of the cells, which do not change when the format of the containers changes, and consequently the procedure for adapting the equipment to the changes in format is considerably simplified. In particular, the containers are drawn, one at a time, from the base of the magazine by a suction cup arm which initially swings downwards and then extends towards the initial part of the cellular conveyor of the packaging machine, where opening means operate at the correct time to open the container so that the latter can be inserted at the correct time into the cell which is open at the rear and which is being formed in the initial part of the conveyor. After the feed step, the suction cup arm releases the container, is lowered, is retracted under the magazine, and is then raised again to repeat the cycle which has been described. Clearly, equipment of this type has long periods of downtime and cannot operate at a speed as high as that of the carousel device described in the first of the cited patents. This equipment is subject to the same problems of adjustment as the first, for the purpose of avoiding damage to the container during its transfer to the conveyor of the packaging machine, each cell of which must always be positioned so that it is open at the rear and must then be closed on the container which has been fed into it. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention proposes equipment for feeding boxes or containers, initially stacked in a flattened configuration, to the conveyor of a packaging machine, this equipment having the advantages of the aforesaid known equipment, but being free of their drawbacks, in that it can operate continuously at high speed, requires no complicated adjustment when the format of the containers changes, can insert the containers into cells which are already substantially formed, and allows the magazine to be positioned at a low level where it can easily be restocked and inspected. The innovative characteristics of the equipment according to the invention will be apparent from the following description of a preferred embodiment of the invention, illustrated purely by way of non-limiting example in the figures on the three attached sheets of drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  show the equipment, respectively, in a schematic view and in lateral elevation with a degree of perspective, viewed in both cases from the same side of the container pick-up and feed members; and 
         FIG. 3  shows the equipment in a plan view from above, showing a single container pick-up and transfer unit, with parts in section. 
     
    
    
     DETAILED DESCRIPTION 
     In the drawings, the letter M indicates the magazine of a known type in which the containers A in a flattened tubular configuration are stacked, with one of the two open ends facing the viewer of  FIG. 1 , this magazine having its lower end facing downwards with an inclination of about 45° for example. The base of the magazine M is placed slightly upstream of, and at a slightly higher level than, the base of the active run of the cellular conveyor T of the packaging machine which operates continuously in the direction F. The letters PA and PP indicate, respectively, the front and rear walls delimiting the cells of the conveyor T, into each of which cells a container is to be fed in the open tubular configuration, to enable a product to be inserted into the container subsequently through one of its lateral openings. 
     The container feed equipment is located under the magazine M, upstream of the conveyor T and substantially at the same level as the conveyor, this feed equipment comprising a carousel  1  supported by one end of a horizontal main shaft  101  which is orthogonal to the direction F of advance of the conveyor T and which is supported rotatably by a support  2  fixed to the vertical plate  3  of a base structure of greater width (not shown). The end of the shaft  101  opposite that which supports the carousel  1  is connected to a motion transmission system  4 ,  104  of any type which can transmit to the carousel a rotation in the clockwise direction as it appears to the viewer of  FIGS. 1 and 2 , this rotation being continuous and in phase with the continuous movement of the chains of the conveyor T. Preferably, the transmission system  4  transmits the motion to the shaft  101  through an interposed safety joint  5 , and suitable sensors, which are not shown because they will be well-known to persons skilled in the art, are provided to transmit to the central processor of the machine electrical signals corresponding to the phase of the transmission system  4 ,  104  and to any difference between this and the phase of the shaft  101  when the safety joint  5  is required to operate. 
     A rotary distributor  6  connected to a pneumatic circuit  106 , described more fully below, is mounted on the end of the shaft  101  which is closer to the transmission system  4 . 
     The carousel  1 , which is fixed on the end of the shaft  101 , is star-shaped, having for example three identical spokes  201  spaced at equal angular intervals from each other, whose distal ends rotatably support corresponding pivot pins  7  which are parallel to the shaft  101 , and which project from both sides of the corresponding spokes  201 , a corresponding feed unit U 1 , U 2 , U 3  as described below being fixed on the end of each pivot pin. On the other end of each pin  7 , which projects towards the base side member  3 , there is fixed a right-angled lever  8  which has an arm of greater length  108  whose end carries, on the side facing the side member  3 , a roller  9  which follows the double-acting and closed annular profile  110  of a face cam  10  fixed to the base side member  3 . The profile  110 , as shown in  FIGS. 1 and 2 , is substantially elliptical in shape, is axially offset from the shaft  101 , and has an inner peak  110 ′ on the ascending branch for the purpose described below. On the end of the shorter arm of the right-angled lever  8  there is a laterally mounted roller  11  which can follow the curved profile  112 ,  112 ′ of two successive face cam sectors  12 ,  12 ′ which are fixed to the cam  10  and, partially, in the case of the sector  12 ′ only, to the base side member  3  also, with the interposition of spacers  13  ( FIG. 3 ). At least the entry ends of the profiles  112 ,  112 ′ and preferably also the exit end of the profile  112 ′ have flared shapes  14 ,  14 ′,  14 ″ to improve the interaction with the roller  11 . 
     An arm  15  is fixed perpendicularly to the other end of each pivot pin  7 , this arm being Z-shaped in plan view in order to keep its distal end  115  at a suitable distance from the adjacent carousel  1 , and this end  115  is designed in such a way that a plate  16  can be mounted on it in an adjustable and interchangeable way, the plate  16  having a shape related to that of the containers A and being provided with the correct number of suitably distributed suction cups  116 , which are connected at the correct time to suction means or to the atmosphere. For example, good results have been obtained by mounting in the lower part of each plate  16 , in communication with its inner cavities to which the suction cups  116  are connected, a small stationary Venturi vacuum pump  17 , which has a silenced outlet filter  117  and has its inlet  217  connected to a compressed air delivery tube  18 , which is supported in at least one intermediate part by a support  19  fixed to the arm  15 , and whose other end is connected to a connector  20  fixed on the end of the pivot pin  7  which supports the arm  15 . The connector  20  is connected to an axial cavity  21  of the pivot pin  7  which has a radial slot-like outlet  121  opening in a portion of the pin  7  on which is mounted, with the interposition of sealing means, a rotary collector  22  which is connected by means of a tube  23  with corresponding connectors  123 ,  223  to an axial cavity  24  of the shaft  101 , which is connected at the other end of this shaft to the circuit  6 ,  106  which in turn is connected to a compressed air supply. By means of the circuit which has been described, the compressed air is sent to each Venturi pump  17  which converts it to a suction force acting on the suction pumps  116 . The rotary collector  22  is internally shaped in such a way that, in its interaction by relative rotation with the radial slot-like outlet  121 , it forms an automatic distribution chamber which, in certain specific angular positions of the carousel  1  and of each arm  15 , causes the suction cups  116  of each arm to create suction or to be connected to the atmosphere (see below). In order to balance the weight of each arm  15  and the corresponding plate  16 , a suitable counterweight  25  for static and dynamic balancing is fixed to the end of the pivot pin  7  which also carries the arm. 
     It can be seen in  FIG. 1  that the equipment is designed in such a way that, while the plate  16  of one unit U 1  is interacting with the magazine M, the unit U 2  is interacting with the conveyor T and the unit U 3  is in an intermediate position between T and M, still with the plate  16  orientated upwards. The roller  11  of the unit U 3  has just ceased to interact with the profile  112 ′ of the fixed cam sector  12 ′, while the roller  9  is running along the lower portion of the profile  110  of the main fixed cam  10 . The suction cups of the unit U 3  are inactive. During the subsequent clockwise rotation of the carousel  1 , the roller  11  of the unit U 3  interacts with the profile  112  of the fixed cam sector  12 , causing the plate  16  of this unit to swing upwards and be positioned in the required way for correct interaction with the base of the magazine M. During the travel along the ascending portion of the profile  110 , before the roller  9  reaches the inner peak  110 ′ of this profile, the roller  11  leaves the profile  112  of the cam  12 , as a result of which, when the roller  9  follows the peak  110 ′, the plate  16  with the suction cups of the unit which bears on the magazine M, which in this example is the unit U 1 , approaches the base of the magazine in order to pick up the base container and draw it out with an upward translational movement, while known means which are provided in the magazine come into action to retain the other containers in the stack. In this step, the suction cups  116  of the plate  16  are providing suction in order to firmly retain the container to be drawn out, and then draw it out. In the movement from the magazine M to the conveyor T, the roller  11  of the feed unit starts to interact with the profile  112 ′ of the cam  12  and the plate  16  of this unit is inserted into the initial part of the upper run of the conveyor T, thus placing the container A in a horizontal position in the cell PA, PP which is substantially formed on this conveyor, while the suction cups of this unit are inactivated at the correct time to release the container. During the transfer from the magazine M to the conveyor T, at least one of the walls of the container held by the feed unit in transit interacts with any suitable opening means which open the container so that it can be inserted in the open state into the cell PA, PP of the conveyor T. In the present example, the front wall A 1  of the container which is about to be fed on to the conveyor T interacts with an adjustable fixed guide  26  which provides the desired degree of opening of the container. When the container has been inserted into the cell of the conveyor T, the distal end of the plate  16  of the unit U 2  swings downwards, thus assisting the progressive detachment of the container from the suction cups  116  which are disconnected from the vacuum at the correct time.
Equipment for feeding containers to a packaging machine comprising a magazine containing stacked containers. The equipment comprising a carousel device for collecting and inserting the containers into a conveyor. The magazine is positioned with its lower end slightly above that of the conveyor and suitably upstream thereof, in that a carousel device, rotating about a horizontal axis orthogonal to the direction of continuous advance of the upper run of the conveyor of the packaging machine, is located under the magazine and upstream of the conveyor, in that this carousel device comprises a plurality of suction cup units positioned in a way determined by interaction with cams, and in that the units are designed to grip the container and draw it from the base of the store by gripping the base wall by means of which these units subsequently deposit the container in a dynamic way on to the conveyor.