Abstract:
A system for transporting containers, which is especially suitable for use in a plant for the production of paints, varnishes and the like, includes a longitudinally extending bearing structure for containers. The structure in turn includes a first, fixed, portion defining one or more fixed bearing surfaces, and a second, movable, portion defining one or more movable bearing surfaces. Handling devices are coupled operatively to the movable portion in order, in use, to bring about coordinated movements of lifting/lowering and longitudinal advance/return of the movable portion relative to the fixed portion.

Description:
This is a National stage entry under 35 U.S.C. §371 of Application No. PCT/IT01/00066 filed Feb. 14, 2001; the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
    
    
     The present invention relates to the field of industrial plants for the production of paints, varnishes, enamels, inks and the like, and in particular to a system for handling containers in those plants. 
     Known types of industrial plant for the production of paints and varnishes usually comprise lines for handling the paint containers which are carried in sequence to processing stations including, for example, stations for filling, for metering and delivering dyes, for mixing, for weighing and checking, and also for packing, storing and/or despatching. 
     An example of an industrial plant of the type indicated above is described in the document EP-A-0 427 497 which illustrates a conventional container-handling system which comprises tracks having idle and/or motor-driven rollers which transport the containers along predetermined paths. Other transport and handling systems normally used also in other technological fields involve the use of endless and motor-driven conveyor belts, the upper face of which supports the containers which are to be transported from one station of the plant to another. 
     Another example of a transport system is disclosed in document U.S. Pat. No. 4,151,907 which shows a walking beam conveyor having a cam ( 32 ) at only one of its end driving a longitudinally extending beam ( 26 ). First and second linkage means ( 48 ,  54 ) move the beam transversely, e.g. vertically, and longitudinally, e.g. horizontally, of the conveyor. 
     The prior art transport systems have a number of disadvantages, above all the low degree of precision in reaching accurate positions along the production line, which means that it is necessary to adopt often expensive arrangements for ensuring the correct placement of the containers, for example, beneath the delivery nozzles of the dye-dispensing machines. It should be borne in mind that containers for paints and varnishes often have a very small opening on the upper face which is closed with a cap once the container has been filled. The small dimensions of that opening, together with the necessity to deliver correctly often very small amounts of dye to the inside of the container, make it necessary to provide means suitable for ensuring the exact centring of the hole below the delivery nozzle. Given the poor positioning precision of the transport systems of known type, in conventional plants it is necessary to provide a series of additional means at the individual work stations, such as guides, stops, mechanical manipulators, robots, and the like. This naturally involves a complication of the plant both in mechanical terms and in control terms, with a consequent reduction in the reliability, repeatability and quality of production during the prolonged and intensive use for which such plants are intended. 
     A further disadvantage of the known systems is the inability to manage multi-form production, that is to say, in which the containers have different shapes and dimensions. 
     Another disadvantage of the transport systems of the prior art, especially for use in plants for the production of paints and varnishes, is the difficulty of keeping such systems clean, above all if a dye product, a varnish or a paint is spilt or upset on them, which could spoil the containers themselves and therefore impair the quality and appearance of the final packaging of the product. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to overcome the disadvantages of the prior art by providing a system for transporting and handling containers which is precise and reliable and which is at the same time economical and simple to produce. 
     In order to achieve that object, the present invention relates to a system for transporting containers, which is especially suitable for use in a plant for the production of paints, varnishes and the like, characterised in that it comprises a longitudinally extending bearing structure for containers, comprising a first, fixed, portion defining one or more fixed coplanar bearing surfaces, and a second, movable, portion defining one or more movable coplanar bearing surfaces, handling means being connected operatively to the movable portion in order, in use, to bring about coordinated movements of lifting/lowering and longitudinal advance/return of the movable portion relative to the fixed portion. 
     A particular advantage of the present invention is afforded by the fact that the handling system can be provided in modular form, with segments of predetermined length which can be readily assembled to form portions of transporter of the desired length. 
     A further advantage of the present invention is provided by the fact that it is readily possible to clean the transport system owing to the substantially planar form of the transport surfaces. 
     Another advantage of the present invention is that it is possible to predetermine with precision not only the positioning of each individual container along the production line but also the relative distance between one container and another, so as to ensure a correct time sequence in the operation of the individual machines in each work station without having to resort to the extensive and generalised use of presence-sensing means at each work station, which clearly has favourable results as regards the overall economy of the plant, its reliability, and the simplicity of managing the complete production process, especially with the large production volumes for which the plants of the type indicated above are intended. 
     Yet another advantage of the present invention is provided by the quiet operation of the transport system compared with the prior art systems, owing to the fact that the impacts between the containers and the bearing surfaces are substantially reduced and the risk of contact between the various containers, which remain spaced from one another by a predetermined distance over the entire handling path, are also completely eliminated, thus also reducing the risk of the containers being damaged, in particular dented. 
     A further advantage of the present invention is provided by the fact that it is also possible to transport and handle simultaneously containers having widely varying dimensions, without having to make any modification to the structure or to the components of the transport system, and while still ensuring optimum precision of advance and positioning along the path of the plant. 
     A further advantage resides in the fact that it is also possible to produce long transport path segments operated by a single motor, simply by combining and connecting small modular portions which can be readily stored and transported. 
     Naturally, although the invention has been developed with particular regard to a plant for the production of paints, varnishes and the like, the transport and handling system to which the invention relates could also be used in other technological fields which require just as accurate a system for positioning parts or members within the framework of a production line. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further characteristics and advantages will emerge from the following detailed description of a preferred embodiment, with reference to the appended drawings which are given purely by way of non-limiting example and in which: 
     FIG. 1 is a partially sectioned plan view of a modular portion of the transport system according to the present invention, comprising a power unit; 
     FIG. 2 is a sectioned side view taken on the line II—II in FIG. 1, 
     FIG. 3 is a cross-section taken on the line III—III in FIG. 2, 
     FIG. 4 is a plan view, similar to FIG. 1, of a modular portion of the transport system without a power unit; 
     FIG. 5 is a plan view, similar to FIG. 1, of a modular portion with a power unit and a device for rotating the containers; 
     FIG. 6 is a sectioned side view taken on the line VI—VI in FIG. 5, and 
     FIG. 7 is a schematic perspective view of a group of containers at the location of a device for rotating the containers. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, a system for transporting containers along a production line comprises a succession of modular portions  10 ,  12 ,  14  of similar type which, as a whole, determine the path along which a group of containers are transported in succession. In particular, the motor-driven modular portion  10 , illustrated in FIGS. 1 to  3 , comprises a principal frame structure  16  including longitudinal support bars  18  resting on the ground by way of a plurality of legs  20  having end feet  21  which are adjustable in height. Secured to the principal frame structure  16  are two longitudinal lateral shoulders  22  which define two corresponding outer bearing surfaces  23 . Also secured to the principal frame structure are two inner bearing girders  24  which define two corresponding inner bearing surfaces  25  arranged symmetrically relative to the plane of the longitudinal centre line of the modular portion  10 . 
     A handling beam  26  which is slidable both longitudinally and vertically relative to the principal frame structure  16  is arranged along the centre line of the modular portion  10 . The beam  26  is supported by a plurality of lifting devices, for example, although this is not to constitute a limitation, by the pneumatic jacks or cylinders  28  illustrated in the drawings, which are secured firmly to the frame structure  16 . A sliding system is interposed between the lifting devices  28  and the beam  26  and is, for example, constituted by bearings  30  which enable the beam  26  to slide longitudinally, irrespective of the vertical position it assumes as a result of the cylinders  28  being operated. At one of its ends the beam  26  is coupled to a motor  32 , preferably an electrical motor, with the interposition, in addition to an optional reduction gear  33 , of a connecting rod and crank mechanism  34  having an eccentric, or of any other type of mechanism normally known by a person skilled in the art which is suitable for transmitting the movement to the beam  26  with conversion thereof from a rotary movement to a linear movement. 
     Secured along the beam  26  are cross-members  36  on which are mounted intermediate bearing girders  38  which define two corresponding intermediate bearing surfaces  39  which are arranged symmetrically relative to the plane of the longitudinal centre line of the modular portion  10  and which are interposed with play between the lateral surfaces  23  and the inner surfaces  25 . The play between the surfaces  23  and  25  is such as to ensure free relative movement between them but it is nevertheless sufficiently small to offer adequate protection against accident to the operators. A longitudinal support structure  40  is also secured to the beam  26  and defines a corresponding median bearing surface  41  having a median duct  41   a  for collecting any drops of product which might escape from the containers. The intermediate bearing surfaces  39  and the median bearing surface  41  lie substantially in the same horizontal plane which, when the beam  26  has been lowered to the maximum extent, is lower than the horizontal plane in which the lateral bearing surfaces  23  and the inner bearing surfaces  25  lie. The stroke of the lifting means  28  is such that, when the beam  26  has been raised to the maximum extent, the horizontal plane in which the intermediate surfaces  39  and the median surface  41  lie is raised above the horizontal plane in which the lateral bearing surfaces  23  and the inner bearing surfaces  25  lie. 
     Referring now to FIG. 4, the simple modular portion  12 , without any independent motorisation in the horizontal direction, but likewise provided with means  28  for lifting the central beam, comprises a structure substantially similar to that of the motor-driven modular portion  10 , with the exclusion of the motor  32  and the handling devices connected thereto. Instead, the ends of the modular portion  12  are provided with connecting means  42  which enable the modular portion  12  to be connected to adjacent portions in order to derive from a remote motor-driven modular portion  10  the movement of the central beam and of the structures connected thereto. 
     Referring to FIGS. 5 and 6, the motor-driven modular portion  14  also comprises a device  44  for rotating the containers, which comprises a pair of bearing tracks  46  supported by a platform  48  which is rotatable by means of a mechanism  50 , which preferably, although this does not constitute a limitation, includes a pneumatic linear actuator and a bevel gear. Substantially, the tracks  46  lie on the extension of the girders  25 . 
     The modular portions  10 ,  12 ,  14  described above can be coupled one behind the other. Preferably, a single motor-driven modular portion  10  or  14  controls a plurality of simple modular portions  12  connected thereto in succession. The lifting means  28  of the various modular portions are generally served by the same power supply, in particular by the same source of compressed air, in order to bring about the simultaneous lifting and lowering of all of the beams  26  of modular portions that are adjacent to one another, and therefore the simultaneous lifting and lowering of all of the intermediate  39  and median  41  bearing surfaces relative to the parallel lateral  23  and intermediate  25  longitudinal bearing surfaces. 
     The lifting and lowering movement of the beams  26  is coordinated by an external control system (not illustrated in the drawings) with the horizontal sliding movement of the beams  26  and, consequently, of the intermediate  39  and median  41  longitudinal bearing surfaces. 
     When a series of containers is placed on the transport and handling system formed by the series of modular portions  10 ,  12 ,  14  connected adjacent to one another, in an initial stage the bases of the containers rest only on the lateral bearing surfaces  23  and/or on the inner bearing surfaces  25 , depending on the transverse dimensions of the containers. The system for controlling the transporter then activates the lifting means  28 , in particular, although this is not to constitute a limitation, by bringing about the delivery of compressed air to the pneumatic cylinders  28 . The various beams  26  of the modular portions  10 ,  12 ,  14  are raised in a manner such that the various intermediate  39  and/or median  41  longitudinal bearing surfaces push simultaneously on the bases of the various containers, lifting them and removing them from the lateral  23  and inner  25  bearing surfaces. 
     The control system then sends an activating signal to the motor  32  which brings about the longitudinal advance of the beams  26 . When the beams have reached the longitudinally advanced position, the control system brings about the deactivation of the lifting means  28  and the consequent lowering of the various intermediate  39  and/or median  41  longitudinal bearing surfaces. Thus, the series of containers is set down gently again on the lateral  23  and/or inner  25  fixed support surfaces, but in a position advanced by a specific amount relative to the starting situation. 
     When the movable bearing surfaces  39  and  41  have been lowered to such an extent that they no longer support the containers, the control system activates the motor  32  so that it returns the beams  26  into the withdrawn position, in order for the operating cycle to be resumed again from the beginning. 
     Although the operation of the transport system has been described above with reference to activation and deactivation commands imparted by an external control system, it is nevertheless possible to provide an operating procedure which does not require a complex control logic. It is sufficient to synchronise a continuous alternating movement of lifting and lowering the beams  26 , which is brought about by the lifting means  28 , with a continuous longitudinal alternating movement of the beams  26  which is brought about, for example, by the connecting rod and crank mechanism connected to the motor  32 . The result is a circular or elliptical movement in the vertical plane, in which the horizontal velocity component of the guides  26  is zero at the front and rear dead centres, which coincide with the moment at which all of the fixed  23 ,  25  and movable  39 ,  41  bearing surfaces are aligned in a horizontal plane common to the base plane of the various containers. 
     The rotation device  44 , which can be either integrated in the modular portion  14  of FIGS. 5 and 6 or provided as a separate accessory which can be integrated in a transport system constituted by the modular portions  10  and  12 , is advantageously used in cases where it is necessary to rotate the containers at a work station, for example so that they can be picked up by a manipulator before a set of mixers. In fact, in many cases it is necessary to orient the containers C, C′ in a specific manner so that, for example, although this is not to constitute a limitation, the handles  50 ,  50 ′ are oriented in predefined directions. In such cases, when the movable surfaces  39 ,  41  are in the lower position of their movement, the tracks  46  can be rotated about a vertical axis in order to present the containers C, C′ in the required position for the subsequent production stages. 
     In the above description, the unit for operating the handling means in the longitudinal direction of the transport system, comprising the motor  32 , the optional reduction gear  33  and the mechanism  34  for converting the movement from rotary to linear, has been described by way of example as forming an integral part of the motor-driven modular portion  10 . It will be appreciated that it is possible to provide as mentioned above with regard to the rotation device  44  an independent motor-driven operating unit which can be integrated in a transport system comprising only simple modular portions  12 . In that case, the placing of such a motor-driven operating unit close to a simple modular portion  12  would basically assume a configuration analogous to that of the motor-driven modular portion  10  illustrated in FIG. 1, in which the broken line J is intended to indicate the line of the plane joining the motor-driven operating unit (on the right in the Figure) and the simple modular portion connected thereto (on the left in the Figure). 
     Naturally, the principle of the invention remaining the same, the details of construction and forms of embodiment may be varied widely with respect to those described and illustrated, without thereby departing from the scope of the invention.