Abstract:
A handling apparatus for groups of thermoformed object constantly held in a correct axial alignment. The apparatus include at least one picking up and release head having as many receiving seats extending parallel to one another from the head as are the stacks to be handled, and a drive apparatus arranged to move a respective pick up and release head between a stack pick up station and a stack release station of one or more stacks of thermoformed objects and to position it correctly both at the stack pick up station and at the stack release station. At least one mobile pusher member is arranged to engage the stacks of thermoformed objects located in each receiving sear, and control drive apparatus for each mobile pusher member to follow and hold down each stack while each stack is being released from its respective receiving seat.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a handling apparatus for groups of thermoformed objects constantly held in a correct axial trim. 
   In the industrial production of thermoformed objects, i.e. containers and lids, by means of a modern thermoforming press, once the moldings of objects have been stacked at a stacking station, the serious problem exists of moving away the already formed stacks with the required rapidity, but without modifying the trim or the axial alignement thereof, within the cycle times of the thermoforming press in order to avoid dead times and to keep a constantly high productivity of the press. 
   As is shown in  FIGS. 1 and 2  in the accompanying drawings that illustrate one release or laying phase of a group of stacks  4  of thermoformed objects  5  drawn from a stacking device and located in cages of hooking rods  3  provided with supporting retractable hooks or spikes  6 , laying of the stacks can occur either onto a plane (fixed or movable) p (See  FIG. 1 ) or onto a plate p having a series of vertical guides g for locating stacks as shown in FIG.  2 . As a matter of fact, breaking down of the stacks occurs rather frequently since some thermoformed objects  5  can become arranged in an untidy way between the hooking rods  3  during release thereof, which can result in uncomplete release of the stacks or in release and laying of untidy stacks that would create quite serious problems) as will be easily understood, in successive handling operations of the stacks. 
   SUMMARY OF THE INVENTION 
   The main object of the present invention of the present invention is to provide a handling apparatus for groups of stacks which can assure keeping of the correct axial alignment of the single stacks as well as their mutual spacing while being transferred from a stacking or stack storing station to a stack receiving or release station. 
   Another object of the present invention is to provide a handling apparatus for stacks of thermoformed objects that is of high efficiency and practical use so as to be suitable to operate in synchronization and within cycle times of a thermoforming machine. 
   These and other objects which will be better apparent hereinafter are attained by a handling apparatus for groups of thermoformed objects constantly held in a correct axial alignement according to the present invention, which apparatus includes at least one pick up release head having as many receiving seats extending parallel to one another from said head as are the stacks to be handled, and a drive apparatus arranged to move a respective pick up and release head between a stack drawing station and a stack release station of one or more stacks of thermoformed objects and to position it correctly both at the said stack drawing station and at the said release station, and is characterized in that it comprises at least one mobile pusher member arranged to be moved between, and parallel to, the said receiving seats in order to engage at the top thereof the stacks of thermoformed objects located in each receiving seat, and control drive means for each mobile pusher member, thereby following and hold down each stack while the same is being released from its respective receiving seat. 
   Advantageously, an equipped receiving member is provided at the said release station for receiving the stacks released from the picking up head. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further aspects and advantages of the present invention will better appear from the following detailed description of some presently preferred embodiments thereof, given with reference to the accompanying drawings, in which: 
       FIGS. 1 and 2  each show a detail on enlarged scale of a pick up or drawing and transfer head in accordance with the prior art and some typical breakdowns in stacks while being released from the hooking rods; 
       FIG. 3  illustrates a first embodiment of a handling apparatus for groups of stacks of thermoformed objects according to the present invention having rotatable picking up and release head, the stacks being loaded onto a resting surface; 
       FIG. 4  shows a diagrammatic perspective view of a second currently preferred embodiment of a handling apparatus for groups of stacks according to the present invention having a picking up and transfer head for stacks of thermoformed objects, which can move on a straight path for releasing stacks on an equipped plate; 
       FIG. 5  is a diagrammatic perspective view of a detail on an enlarged scale of a pick up head of a stack handling apparatus according to  FIGS. 3 and 4 ; 
       FIGS. 6  to  9  show the sequence of laying or releasing a plurality of stacks of thermoformed objects onto a receiving surface by means of a pick up and release head according to  FIG. 3 ; 
       FIGS. 10  to  16  are each a diagrammatic perspective view of a pick up head of an apparatus according to FIG.  4  and show the operating sequence of a release and laying of a plurality of stacks of thermoformed objects onto an equipped plate; and 
       FIGS. 17  to  19  illustrate a third embodiment of a handling apparatus for stacks of thermoformed objects, in which the pick up head releases groups of stacks in a substantially horizontal, rather than vertical, direction onto a carry away conveyer for the stacks. 
   

   In the accompanying drawings the same or similar parts or components have been indicated by the same reference numerals. 
   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference first to  FIGS. 3  to  5 , it will be noted that a handling apparatus for stacks  1  of thermoformed objects according to the present invention comprises a moving pick up-release head  2  having a plate  2   a  equipped with six groups of four hooking rods extending downwardly parallel to one another from the plate  2   a . Each group of hooking rods  3  delimits a receiving seat arranged to locate and support a respective stack  4  of thermoformed objects, e.g. lids  5 , as is shown in the drawings. Each hooking rod  3  is provided at its lower free end with a retractable hook  6 , which may be pneumatically remotely controlled to come out from, and retract into, its respective rod, as is well known in the art. 
   In  FIG. 3  the plate  2   a  is upwardly secured, e.g. bolted, to the free and of a overhanging support arm  7 , which in turn is supported on the top, e.g. keyed, of a vertical output shaft  8  mounted for rotation in a support case  9 , which preferably also locates a reversible motor-reduction gear group (not shown in the drawings, but of any suitable type). The support case also locates a vertically raising-lowering device (not shown in the drawings, e. g. a double acting jack) arranged to cause the overhanging arm  7 , and thus the pick up-release head  2 , to raise and lower vertically. The prearranged and combined motion of rotation and the raising-lowering motion results in the support arm  7  causing, in use, the pick up-release head  2  to move between a picking up station, e.g. at a stacking device  10  (see  FIG. 4 ) for picking up a plurality of stacks  4  of thermoformed objects  5  and a release station where the stacks  4  of thermoformed objects are laid, such as onto a flat tape  12  of a tape conveyer  13  shown in FIG.  3 . 
   In the embodiment illustrated in  FIG. 4  the plate  2   a  of the pick up and release head  2  is secured underneath a support frame  14  which is supported, e.g. in an overhanging fashion, by a pair of sliding guides  15 , that in turn are carried by a fixed U-shaped crosspiece  16 . The frame  14  can be driven to effect to and from movements or strokes between a stack pick up station  10  and a stack release station  17  by means of a linear actuator, e. g. of the type comprising a screw  18  driven by a reversible motor-reduction gear group  19  and nut screw  19   a  formed or secured to the frame  14 . 
   Moreover, the plate  2   a  can effect straight vertical movements owing to the action of a linear actuator, e. g. comprising a pneumatic double acting cylinder and piston group  20 , which is arranged to lower and lift the plate  2   a  at the pick up station  10  and the release station  17 . 
   Both in FIG.  3  and  FIG. 4  among the hooking rods  3  there is provided one or more moving pushers  21 , e.g. in the form of a grid or frame mounted or supported in such a way as it can move parallel to the hooking rods  3  in order to engage the top of the stacks  4  of thermoformed objects  5  being located within each group of booking rods  3 . To this end, a suitable drive means is provided, e.g. a pair of double acting pneumatic jacks  23 , arranged to transmit to the pushers a controlled movement to pursue the stacks  4  of thermoformed objects  5  while the same are being released at the stations  12  or  17 . 
     FIGS. 6  to  9  show the operational sequence followed by the pick up and release head  2  illustrated in  FIG. 3  while releasing or unloading stacks  4  of thermoformed objects  5  carried by it. Once the head  2  has been transferred (or while being transferred) onto the receiving surface  12 , the pushing frame  21  is moved to rest on top of the stacks  4  of thermoformed objects  5  located in the head  2 , then the plate  2   a  is lowered through the arm  7  by the raising-lowering device seated in the case  9  until the tips of the hooking rods  3  are resting on, or very near to, the receiving surface (see FIG.  7 ). At this point, the plate  2   a  with its respective hooking rods  3 , owing to the returning action of the raising-lowering device in the case  9 , begins to raise, whereas at the same time the hooks  6  are controlled to retract into their respective hooking rods  3  and the pair of jacks  23  pushes the frame  21  to pursue the stacks  4  and hold them suitably pressed downwards, while the stacks slip off the hooking rods lowing to the raising movement of the plate  2   a  to come to rest on the receiving surface  12  and to keep each stack packed until the hooking rods are fully pulled off (see FIG.  8 ); after which the frame  21  is lifted by the jacks  23  (see  FIG. 9 ) and the head  2  is moved away from the release station  12  to return to station  10  to be loaded with another group of stacks  4  and to restart the operation cycle. 
   In the embodiment of  FIG. 4  the pick up station  10  is constituted by a stacker of any suitable type, e. g. comprising a plate p, vertical guides g extending therefrom and holes  24  formed close to the guides g for temporary receiving and engaging with the tips of the hooking rods  3  of the picking up-release head  2 . Among the guides g stacks  4  of thermoformed objects  5  are obtained in any suitable manner, e.g. owing to the action of a linear actuator  26 , as is well known to a skilled person in the art. 
   The receiving plane at the release or unloading station  17  instead comprises an equipped plate  30 , which can have vertical guides g as plate g at the pick up station  10  and has a vertically movable bearing frame or grid  31  and a linear actuator for the frame  31 , e. g. comprising a pair of pneumatic jacks  32  whose piston rod is secured to the frame  31  so as to cause the same to effect controlled lifting-lowering strokes. 
   The operation sequence of the handling apparatus according to the present invention, framed as shown in  FIG. 4 , is illustrated in  FIGS. 10  to  16  according to distinct operational ways, will explained hereinbelow. The head  2  is vertically transferred above the equipped plate  30  located at the release or unloading station  17 . The frame  31 , while the head  2  is being transferred or immediately after the same has arrived above the plate  30 , is lifted towards the head  2 , as is shown in FIG.  10 . 
   According to a first way of unloading (see  FIGS. 10  to  13 ) the head  2  carries lengths  4   a  of stacks to be unloaded onto the plate  30 , and thus the frame  31  is moved to a lifted position to receive the lengths  4   a , whereas the head  2 , within which in the mean time the frame  21  has moved to a rest position onto the stacks lengths  4   a , is lowered by the jack  20  until the lengths  4   a  rest onto the frame  31  underneath (see FIG.  11 ). At this point the frame  31  is lowered towards an intermediate position, whereas the jacks  23  push the frame  21  downwards so as to hold down the stack lengths  4   a  well packed (FIG.  12 ), after which the head  2  is raised and can return to the pick up station  10  to be loaded with a second group of stack lengths  4   b  and to be then transferred, owing to the drive action of the motor  19 , above the plate  30  (FIG.  13 ), where in the mean times the frame  31  is in a standby condition in its intermediate position corresponding to the height of the coming lengths  4   b  which are then unloaded with the above described procedure onto the lengths  4   a  under the pushing action of the frame  21  so as to complete the stacks  4  (FIG.  14 ). 
   According to a further way of carrying out unloading or release operations, the head  2  is loaded with complete stacks  4  and unloads them in a single operation, as shown in  FIG. 14 , always with the pushing action of the upper frame  21  in the head  2  and the frame  31  onto the receiving plate  30 , which in each case is lifted from the plate  30 , as shown in  FIG. 10 , to receive the coming stacks  4  and lower them onto the plate  30 . 
   Once the complete stacks  4  are unloaded onto the frame  31  by being pushed by the upper frame  21 , the head  2  is lifted, whereas the frame  21  holds down the stacks while being further lowered together with the lower frame  31 , that in the mean time comes to rest onto the plate  30  while the hooking rods  3  slip off the stacks (FIG.  15 ). Finally, the frame  21  is lifted and leaves the stacks  4  and the head  2  can move away from the release station  17 , thus leaving on the plate  30  stacks perfectly axially aligned and ready for subsequent handling operations (FIG.  16 ). 
   It will be noted that owing to the presence of the frame or grid  21 , even in the case in which gravity does not suffice to ensure unloading by fall of all the thermoformed objects in a stack  4 , all the thermoformed objects  5  are unloaded from the head  2  in any circumstance and, since they are permanently held down well packed together during the unloading operation, the stacks  4  cannot split up or become otherwise misaligned. 
     FIGS. 17  to  19  show a handling apparatus according to the present invention having a pick up-release head  2  with a plate  2   a  laying in a transverse (vertical) plane rather than a horizontal one, as in the above described embodiments, in order to carry out loading and unloading of groups of stacks of thermoformed objects in a direction which differs from the vertical one, and thus even without taking advantage of the gravity for unloading the stacks. 
   More particularly, the plate  2   a  is equipped with a multiplicity of pairs of guides  40  delimiting a sliding receiving seat for the stacks  4  and are equal in number to the stacks to be received therein. The guides  40  extend perpendicularly from a face of the plate  2   a  and a pusher, formed by a cross bar  21  driven by a pair of double acting jacks  23 , is arranged to move parallel to them. 
   The unloading or release station is constituted e. g. by a tape conveyer  13  having a tape  12  provided with parallel partition sectors  12   a  delimiting (horizontal) cradles for the stacks  4 . A resting and guide element, e. g. constituted by a bar  31  extending parallel to the bar  21  (when the latter is in its unloading position) is mounted on the conveyer  13 . The bar  31  is supported by a pair of sliding (horizontal) guides  41  and is secured to the piston rod end of a double acting jack  42 . 
   During the unloading operation, the head  2  is moved with its receiving seats in alignement with an equal number of cradles on the conveyer  13 , the pushing bar is brought to rest against the stacks  4  loaded in the head  2 , after which the pusher  21  and the bar  31  are moved in unison so as to keep the stacks  4  well packed and transfer them onto the conveyer  13 . The latter has downstream thereof a pair of fixed sliding guides  42  and  43  extending in the feeding direction of the tape  12  so as constantly to keep the stacks  4  well packed and axially aligned. During unloading in fact the pusher  21  moves forwards until its front is coplanar with the inner face of the guide  42 , whereas at the same time the bar  31  moves backwards until its front face is coplanar with the inner face of the guide  43 . The bars  21  and  31  remain in this aligned position with their respective fixed guide  42 ,  43  until the tape  12  has moved forward to such an extent that al the stacks  4  unloaded thereon are abutting against the guides  42  and  43 , after which the pusher  21  moves back and the head  2  can return to be loaded with stacks  4  to start a new operating cycle. 
   The disclosure in Italian patent application no. VR2001A000017 filed on Feb. 15, 2001 from which priority is claimed is incorporated herein by reference.