Abstract:
According to the invention, the handling robot includes a vertical telescopic mast ( 11 ) that comprises: a vertically fixed base ( 20 ); and a plurality of sections ( 21 - 23 ) with synchronised movements, said movements being speed- and acceleration-controlled and including a gravity extension movement and a powered retraction movement, the last section ( 23 ) bearing a head ( 13 ) for gripping the products ( 3 ) to be palletised. The robot includes a common driving shaft ( 30 ) for moving the different sections ( 21, 22, 23 ), wherein said shaft ( 30 ) includes wheels ( 31, 32, 33 ) having a diameter adapted to the travel of the section ( 21 - 23′ ) they operate, respectively, via transmission members. For the last section ( 23 ) bearing the gripping head, the movement transmission is carried out by chains and for the other sections the transmission members between the wheels ( 31, 32 ) and the sections thereof ( 21, 22 ) consist of belts that wind up on the corresponding wheel. A housing ( 46 ) receives and stores the free end of each movement transmission chain, and is made in the form of a block with notches each defining a curved helical path.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a National Stage of International Application No. PCT/FR2008/051714 filed Sep. 25, 2008, claiming priority based on French Patent Application No. 0706788, filed Sep. 28, 2007, the contents of all of which are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The invention relates to palletization facilities, and in particular to an improvement to the handling robot which grasps the products supplied by a conveying device and arranges them on a pallet. 
       DESCRIPTION OF THE PRIOR ART  
       [0003]    This type of palletization facility, or palletizer, comprises a structure which serves as a framework for supporting the handling robot. This robot is a three- or four-axis robot and is composed of:—a platform which moves on rails arranged on the upper part of said framework, —a vertical mast which is supported and guided by said platform, and, at the extremity of said mast,—a gripping head appropriately equipped to take hold of the products to be palletized. 
         [0004]    The gripping head can be pivoting, on the fourth axis, and have suction cups for grasping products on the supply conveyor and then arranging them in the proper orientation on the pallet. 
         [0005]    This type of facility is subject to multiple constraints, including the primary constraints related to operator safety and comfort, but also constraints related to product throughput and type, e.g. weight, size, and those related to problems with installing this type of equipment which must be able to fit into existing buildings that may have a very low ceiling. 
         [0006]    Robot palletizers have been in existence for a long time, and this problem of space for housing the robot has already been mentioned and resolved as described, for example, in document FR2642059. 
       SUMMARY OF THE INVENTION  
       [0007]    The present invention proposes a handling robot for a palletizer which provides a response to this type of installation and spacing constraint. 
         [0008]    It also provides a response to the other constraints related to the environment, with a decrease in noise, and related to operating safety with, in particular, an original control of the movements of the gripping head which protects against dropping hazards. 
         [0009]    The handling robot of the invention also proposes, as described in the document cited above, the use of a telescoping mast for handling crates for palletization. This type of telescoping mast is also described in other documents concerning the art such as, for example, documents JP03241121 and U.S. Pat. No. 5,465,854; these two documents respectively show a manipulating telescoping mast of a back-hoe and a telescoping mast for manipulating an instrument for testing and inspecting various objects. 
         [0010]    The handling robot of the invention, which is a three- or four-axis robot for a palletizer, comprises:—a platform which is guided, transversely to the direction in which the products arrive, on beams situated in the upper part of the framework of said palletizer, and—a telescoping vertical mast consisting of: a vertically fixed base which allows limiting the height requirements of said palletizer, said fixed base supported and longitudinally guided on said platform, and several sections of which the last, or central, section supports the head for gripping said products to be palletized, these sections being manipulated by wheels of diameters appropriate for the travel distance of the section to which they are attached, and by means of independent connecting members, said wheels being mounted onto the same common shaft which provides gravitational extension movement and powered retraction movement, said connecting members between said sections and said wheels consisting of at least one transmission chain for said last section and belts for the other sections, said belts winding around their respective wheel. 
         [0011]    This arrangement, with a chain which establishes a strong connection between the load and the drive shaft and with belts which accompany the movement of the other sections, allows flexible operation and, above all, a particularly quiet operation of the robot. 
         [0012]    Still according to the invention, the last section of the mast is associated with two transmission chains each cooperating with a sprocket wheel, said wheels being placed side by side on the drive shaft, and one of the chains acting as the primary chain for ensuring normal movement of the last section while tension is maintained in the other chain which serves as a retaining and safety device in case of breakage of said primary chain. 
         [0013]    In another arrangement of the invention, the tensioning means of the second chain comprises an elastic member placed between a support located on the upper part of the last section and a stop, said stop being arranged at the lower extremity of a rod that extends the chain and passes through an opening in said support which serves as a guide for it. 
         [0014]    Still according to the invention, the chains for maneuvering the last section extend from their sprocket wheel between the upper part of said last section and a housing which accepts and stores their free end, said housing being in the form of a block equipped on each face with a curved helical groove which accepts said corresponding free end, these grooves being cut into the lateral faces of said block. 
         [0015]    In another arrangement of the invention, the block serving as the housing for the free ends of the two chains is made of thermoplastic material and is in the form of a rotated L, said block partially covering the upper part of each sprocket wheel, acting as a guide for said chains, for about half of the circumference of said sprocket wheels. 
         [0016]    Still according to the invention, the robot comprises, in association with one of the sprocket wheels, a safety device comprising a latch which is maneuvered by means of an actuator supplied with compressed air to maintain said hook in the inactive position and with a spring which places this hook in the active position, if needed, during operator intervention on the machine for example. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0017]    The invention will be further detailed in the following description and the attached drawings, provided as examples, and in which: 
           [0018]      FIG. 1  is a schematic elevated view of a palletization facility comprising a robot of the invention with its mast represented in two positions: it is represented with bold lines in the retracted position and represented with thin dotted lines in the completely extended position 
           [0019]      FIG. 2  is an enlarged schematic horizontal cross section from  2 - 2  of the mast which appears in bold lines in  FIG. 1   
           [0020]      FIG. 3  is an enlarged partial schematic vertical cross section viewed from  3 - 3  of the mast which appears in bold lines in  FIG. 1   
           [0021]      FIG. 4  is a partial schematic vertical cross section viewed from  4 - 4  in  FIG. 3   
           [0022]      FIG. 5  is an enlarged cross section from  5 - 5  in  FIG. 4 , showing the housing in the form of a block, which guides the free ends of the two transmission chains associated with the last section of the mast, 
           [0023]      FIG. 6  is a more detailed schematic view of the safety system for locking the notched and sprocketed wheels which maneuver the sections. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    The palletization facility represented in  FIG. 1  comprises a structure in parallelepiped form which constitutes the framework  1  of what is more simply called a palletizer. 
         [0025]    This framework  1  forms a sort of gantry which is arranged to accept a handling robot  2  with three or four axes, said robot  2  picking up the products  3  supplied by a conveyor  4  and arranging them on a pallet  5  which is positioned within a frame of reference  6  of the facility. 
         [0026]    The robot  2  is composed of—an overhead traveling platform  8  which moves along the upper beams  9  of the framework  1  under the effect of appropriate motorized means, guided by means of guide rails  10 , and—a vertical mast  11  which is supported and guided by said platform  8  as it moves under the effect of appropriate means such as a motorized belt  12 . 
         [0027]    The platform  8  moves in a direction which is transverse to the direction in which the products  3  arrive; the mast  11  moves longitudinally, in a direction which is parallel to that of the arrival of said products. 
         [0028]    The mast  11  comprises the head  13  which is arranged to allow it to grip products  3 . This head may be pivoting, around a vertical axis, in order to align said products in the appropriate position for their placement on the pallet  5 , said pivoting axis constituting the fourth axis of the robot  2 . 
         [0029]    The head  13  is, for example, equipped with a gripping device which is constituted of several suction cups  14 . 
         [0030]    The movements of the head  13  in the transverse direction and in the longitudinal direction result respectively from movements of the platform  8  relative to the framework  1  and of the mast  11  relative to said platform  8 . 
         [0031]    The vertical movement of the head  13  is ensured by the mast  11  which, in the context of the invention, is telescoping. This mast  11  is in fact composed of—a base  20  whose vertical position is fixed, and as represented by the thin dotted lines in FIG.  1 ,—several sections  21  to  23  which extend downwards, under said base. 
         [0032]    The base  20  projects slightly above the framework  1  and, considering the fact that it is vertically immobile, it is this that defines the maximum height requirement of the facility, said height requirement practically limited to the height of the framework  1 ; this allows easy installation of the palletizer in existing buildings. 
         [0033]    This base  20  is longitudinally guided on the platform  8  by means of guide rails  24 , shown in  FIG. 3 . 
         [0034]    In the embodiment detailed in the drawings, the telescoping mast  11  comprises the base  20  into which a first section  21  is guided; this section  21  guides a second section  22  and that section  22  guides the last section  23  which is in the center and which supports the head  13  for gripping the products  3  mentioned above. The sections  21  and  22  act as the connection between the base  20  and the last section  23 ; this assembly allows having an advantageous vertical travel distance for the gripping head  13 . 
         [0035]    All these sections  21  to  23  move vertically, beneath the base  20 , within the enclosure of the palletizer; their downward movement is due to simple gravity but is controlled, and the upward movement is caused by motorized means. 
         [0036]    These upward and downward movements of each section are synchronized and their speed and acceleration are motor-controlled, as detailed below. 
         [0037]      FIG. 2  schematically shows a horizontal cross section of the different elements of the mast  11 . Starting from the base  20 , they are successively: 
         [0038]    the first intermediate section  21 , which is vertically guided relative to said base by means of a set of guide rails  25  arranged in a longitudinal vertical plane, 
         [0039]    the second intermediate section  22 , which is guided in the same manner by means of a set of guide rails  26  arranged in the same vertical plane, 
         [0040]    the last section  23 , which is also guided by a set of guide rails  27  arranged in said vertical plane. 
         [0041]    These different sections  21  to  23  all move vertically together and their movements are synchronized by means detailed below. In fact, unlike the common practice, the sections do not move each other by means of travel limit stops. 
         [0042]    One will also note that the gripping head  13  is located in the same vertical plane as the guide rails  25 ,  26 , and  27  for the respective sections  21 ,  22  and  23 . This arrangement allows concentrating the lifting force on the central axis of the mast and avoids friction and sticking issues due to overhang of the load which is at the end of the central last section  23 . 
         [0043]    The synchronized movements of the sections  21  to  23  allow smooth displacement of the head  13 , without shocks and abrupt movements, which also eliminate the excessive noise from this type of equipment. 
         [0044]    Each section  21  to  23  is connected to a driving member  29  which is common to all said sections. This connection is made by means of wheels which are supported by a single shaft  30  which is the shaft of said driving member  29  and by transmission members such as chains and belts, as represented in  FIG. 3 . 
         [0045]    In this  FIG. 3 , one can see the base  20  which is supported and guided by the platform  8  by means of guide rails  24 , and this base  20  is traversed by the shaft  30  of the driving member  29 . 
         [0046]    This shaft  30  is arranged transverse to the platform  8  and comprises several wheels: 
         [0047]    a first wheel  31  which is connected to the first intermediate section  21  by a belt  41 , 
         [0048]    a second wheel  32  which is connected to the second intermediate section  22 , also by a belt  42 , 
         [0049]    a third and a fourth wheel  33 ,  33 ′, which are identical and connected to the last section  23  by respective transmission chains  43  and  43 ′. 
         [0050]    The diameters of the different wheels  31  to  33  and  33 ′ are adapted to the vertical travel distance of their respective sections. The diameter of the wheels  33 ,  33 ′ is roughly three times that of the first wheel  31 , and that of the second wheel  32  is roughly twice that of said first wheel  31 . 
         [0051]    The belts  41  and  42  are cogged belts whose extremities are respectively anchored on the wheels  31  and  32  and on the sections  21  and  22 . They are stored on their respective wheels, meaning that they wind or unwind on the wheel in question according to the movement of said sections. 
         [0052]    These belts  41  and  42  are anchored at the sections  21  and  22  by means of respective tabs  51 ,  52 . Said attaching tabs are slightly offset from each other, as represented in  FIG. 2 . 
         [0053]    The wheels  33  and  33 ′ are sprocket wheels which mesh with the respective transmission chains  43 ,  43 ′. 
         [0054]    The chain  43  is fixed to the upper part of the section  23  at the tab  53 , said tab situated in a median transverse plane which is perpendicular to the plane of the guide rails  25  to  27 . 
         [0055]    The wheel  33  and its chain  43  are primarily responsible for the motion of the last section  23 . 
         [0056]    The wheel  33 ′ and its corresponding chain  43 ′ constitute a safety device to prevent a risk of breakage in the other chain  43 . Tension is simply maintained in the chain  43 ′, by means of an elastic member  44  as represented separately in more detail; it does not continuously and directly participate in the maneuvering of the last section  23 . 
         [0057]    The elastic member  44  is placed between a support situated on the upper part of the last section  23  and a stop  45 , said stop  45  being situated at the lower extremity of a rod positioned at the extremity of the chain  43 ′ and which extends said chain by traversing an opening in said support, said support serving as a guide for it. 
         [0058]    Purely mechanical stops  54 , situated in the upper part of each mobile section, establish a limit to the movement of these different mobile sections in case of necessity. 
         [0059]    The chains  43  and  43 ′ extend from their respective wheels  33  and  33 ′, on one side down to the section  23  and on the other they are free and the corresponding end is stored in a housing  46 . 
         [0060]    This housing  46  is in the form of a block of thermoplastic material. It comprises a groove  47 ,  47 ′ in each lateral face, which accepts the free ends of the respective chains  43  and  43 ′, defining a curving helical path for each one. 
         [0061]    These grooves  47  and  47 ′ are cut into the block constituting the housing  46  and are in the form of a T, as represented in  FIG. 5 . This T shape allows each chain  43 ,  43 ′ to slide on its proper wheel and remain centered along the length of its respective groove  47 ,  47 ′. 
         [0062]    In addition, the nature of the material used a thermoplastic material such as polyethylene, facilitates sliding and avoids the improper meshing as it feeds onto the sprocket wheels  33  and  33 ′ which can result from sticking phenomena in the links of the chains  43 ,  43 ′. 
         [0063]    The block that constitutes the housing  46  is arranged perpendicularly to the shaft  29  between the wheels  33  and  33 ′. This housing  46  is in the form of a rotated L covering the wheels  33  and  33 ′ and it envelops part of their circumference. 
         [0064]    The two chains  43  and  43 ′ wind around the upper part of the circumference of the respective wheels  33  and  33 ′; they are covered and guided by means of the housing  46 . 
         [0065]    As the corresponding chain  43 ,  43 ′ leaves its sprocket wheel  33  and  33 ′, it is directed towards the entry into the respective groove  47 ,  47 ′ in the housing  46  by means of a guide  48 . Only one guide  48  appears on the drawings and in particular in  FIG. 4 . 
         [0066]    This guide  48  helps the corresponding chain to leave the sprocket wheel; it accompanies and directs the outside edge of the chain  43  towards the housing  46  entrance when the section  23  is lifting and guides it to mesh with the wheel during the inverse movement. 
         [0067]    Each chain  43 ,  43 ′ follows a curving helical path which first loops on one side of the block, said loop followed by a rectilinear path which passes above the corresponding wheel  33 ,  33 ′, before forming, on the other side of said block, a large vertical loop whose height is about a fourth of the travel distance of the outside section. 
         [0068]      FIG. 6  shows the details of a safety device which operates in case of emergency to lock the different sections of the mast  11  almost instantaneously, and especially the head  13  for gripping the products  3 . 
         [0069]    This safety device comprises a latch  55  which cooperates with one of the wheels to stop the shaft  30  and all the other wheels. In the embodiment presented, the latch  55  is in the form of a hook  56  and cooperates with notches  57  in the sprocket wheel  33 , said notches  57  being in the form of openings regularly distributed along a circumference situated under the teeth of said wheel, as shown in  FIG. 4 . 
         [0070]    The hook  56  is set in motion automatically by an actuator  58 . This actuator, which is pneumatic, maintains the hook  56  in the inactive position when pneumatic pressure is applied, for example, and automatically assumes the active position when there is no pressure, under the effect of an elastic member such as an integrated spring. 
         [0071]    The hook  56  can be activated directly by the operator, for example when he needs to perform an intervention on the machine. It can also be activated automatically, in case of an incident at the gripping head  13  such as, for example, an incident in the air supply to the suction cups  14  that carry the product  3 .