Patent Publication Number: US-2020290771-A1

Title: Method for applying liners inside containers

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method for applying liners inside containers. 
     The invention was developed in particular with a view to its application in the industry for preparing and dosing paints and related products. In the following description, reference will be made to this specific application field without, however, losing generality. 
     DESCRIPTION OF THE PRIOR ART 
     Paints are usually prepared or simply dosed inside cylindrical containers with an open upper edge, in which ready paints are dosed or quantities of paints, dyes and diluting products are dosed and subsequently mixed. 
     Paint containers are usually made of plastic or sheet metal. After filling, the containers are closed by a lid which closes the open upper edge of the container. 
     The document DE4126964-A1 describes a container for paints and the like, inside which a recyclable liner resistant to the product contained therein is applied and which, after use, can be removed from the container leaving the container clean. After use by the end user, the containers can be returned empty to the manufacturer or distributor and can be reused an indefinite number of times, reducing the environmental impact. 
     The use of a liner inside paint containers allows:
         reducing the quantity of materials to be disposed of as waste after use;   reducing the production of plastic or metal containers; and   reducing the production costs of the containers while providing environmental advantages.       

     However, in the state of the art there are no methods or apparatuses that can be used on an industrial scale to quickly and efficiently apply removable liners inside paint containers. 
     OBJECT AND SUMMARY OF THE INVENTION 
     The present invention aims to provide a method and an apparatus for automatically applying liners inside containers intended, for example, to be filled with paints. 
     According to the present invention, this object is achieved by a method and by an apparatus having the characteristics forming the subject of claims  1  and  6 . 
     The claims form an integral part of the disclosure provided here in relation to the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described in detail with reference to the attached drawings, given purely by way of non-limiting example, wherein: 
         FIG. 1  is a perspective view of an automatic apparatus for applying liners inside containers, 
         FIGS. 2 and 3  are, respectively, a side view and a plan view according to the arrows II and III of  FIG. 1 , 
         FIGS. 4 and 5  are a side view and a plan view of a liner, 
         FIG. 6  is a schematic side view illustrating the operation of the de-stacking device of the liners indicated by the arrow  6  in  FIG. 2 , and 
         FIG. 7  is a side view of a tool for gripping the liners indicated by the arrow VII in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIGS. 1-3 , numeral  10  indicates an apparatus for applying liners  12  inside containers  14 . In the illustrated example, the containers  14  are containers for paints made of plastic material or sheet metal. The containers  14  have a cylindrical shape with a closed bottom and an open upper edge, and can be provided with a handle hinged to the side wall. 
     As shown in  FIGS. 4 and 5 , each liner  12  has a closed bottom wall  16 , a side wall  18  and an upper opening  20  opposite the bottom wall  16 . The side wall  18  at its upper end forms a fold  22 , which extends along the edge of the upper opening  20 . The liners  12  can be formed of a film of plastic material, for example, PET, with a thickness of the order of 0.2-0.5 mm. 
     The apparatus  10  comprises a stock  24  in which a plurality of liners  12  are arranged in at least one vertical stack  26 . In the illustrated example, the stock  24  comprises a plurality of positions  28  carried by a circular table  30  rotatable around a central vertical axis. Each of the positions  28  is configured to receive a respective stack  26 . Each stack  26  is formed by a plurality of liners  12  turned upside down and one inside the other. In each stack  26 , the liners  12  are arranged with the upper opening  20  oriented downwards and the bottom wall  16  oriented upwards. 
     The apparatus  10  comprises a de-stacking device  32  including a stationary upright  34  and a pick-up element  36 , movable with respect to the stationary upright  34  along an inverted U-shaped path. The pick-up element  36  has, substantially, the shape of a pallet and is provided with gripping elements configured for gripping the bottom wall  16  of the liner  12  located at the top of the stack  26  located in front of the de-stacking device  32 . The pick-up element  36  can, for example, be provided with suctions cups configured for gripping the bottom wall  16  of a liner  12  by suction. 
     As illustrated in  FIG. 6 , during operation, the pick-up element  36  of the de-stacking device  32  comes into contact with the bottom wall  16  of the liner  12  located at the top of the stack  26  and grips the bottom wall  16 , for example, by means of vacuum gripping elements. After gripping the bottom wall  16  of a liner  12 , the pick-up element  36  moves upwards for a stroke with a length equal to or greater than the height of the liner  12 , so as to disengage the liner  12  from the stack  26 . After the stroke in the vertical direction, the pick-up element  36  rotates by 180° about a horizontal axis, so as to overturn the liner  12  by 180°, so that following the overturning the liner  12  is oriented with the bottom wall  16  facing downwards and the upper opening  20  facing upwards. 
     The de-stacking device  32  may comprise a retaining element  38  configured to retain the second liner  12  of the stack  26 , i.e. the liner  12  located immediately below the liner  12  located at the top of the stack  26 . The retaining element  38  may serve to prevent two or more liners  12  from being removed simultaneously from the stack  26 . 
     The de-stacking device  32  may also comprise a lifting device  40  which raises the stack  26  as liners  12  are removed from the top of the stack  26 , so that removing the liners  12  by the pick-up element  36  can always be carried out at the same height. 
     The apparatus  10  comprises a manipulator  42  which can, for example, be an anthropomorphic robot. The manipulator  42  carries a gripping tool  44  configured for gripping the liners  12  after they have been de-stacked and oriented with the upper opening facing upwards by the de-stacking device  32 . With reference to  FIG. 7 , the gripping tool  44  comprises a central vertical stem  46 , a lower plate  48  and an upper gripper  50 . The upper gripper  50  may comprise an expandable annular membrane  52  connected to a source of compressed air. The expandable annular membrane  52  may be located between two rigid plates  54  fixed to the upper end of the central stem  46 . The gripping tool  44  may further comprise a pressing element  56  having the shape of an annular crown, movable in a vertical direction between a raised position and a lowered position. The gripping tool  44  may comprise proximity sensors  58  arranged on the lower surface of the lower plate  48 . 
     The apparatus  10  can further comprise a conveyor  60 , for example, a roller conveyor, arranged to advance containers  14  in the direction A. 
     During operation, the empty containers  14  advancing on the conveyor  60  are stopped in a liner application station. The de-stacking device  32  picks up a liner  12  from the top of a stack  26  of the stock  24 , and overturns it as illustrated in  FIGS. 1, 2 and 3 . The liner  12  oriented with the upper opening  20  facing upwards is held by the pick-up element  36  above the conveyor  60 . The manipulator  42  inserts the gripping member  44  inside the liner  12  held in an upright position by the pick-up member  36 . The dimensions of the gripping tool  44  correspond to the dimensions of the liner  12 . The gripping tool  44  is inserted inside the liner  12  until the sensors  58  come into contact with the bottom wall  16  of the liner  12 . In this condition, the expandable gripper  50  of the gripping tool  44  is positioned inside the open upper edge  20  of the gripping element  12 . At this point, the expandable membrane  52  is inflated, which increases its diameter and grips the inside of the open upper edge  20  of the gripping element  12 . At this point, the manipulator  42  moves the gripping tool  44  with the corresponding liner  12  above a container  14  and inserts the gripping tool  44  and the liner  12  held thereby inside the container  14 . During this step, the pick-up element  36  of the de-stacking device  32  is positioned above the stack  26  to pick up a new liner  12 . 
     The liner  12  held by the gripping tool  44  is inserted inside the container  14  and is arranged with the fold  22  outside the open upper edge of the container  14 . After having positioned the liner  12  inside the container  14 , the pressing element  56  of the gripping tool  44  is lowered so as to press the fold  22  against the upper edge of the container  14 . At this point, the expandable membrane  52  is deflated so as to reduce its diameter and to disengage the gripping tool  44  of the liner  12 . Then, the gripping tool  44  is extracted from the container  14  leaving the liner  12  inside the container  14 . At this point, the container  14  in which a liner  12  has been positioned advances on the conveyor  60  in the direction A towards a filling station and the cycle is repeated for a new container. 
     Of course, the details of construction and the embodiments can be widely varied with respect to those described and illustrated, without thereby departing from the scope of the invention as defined by the claims that follow. 
     For example, the elements for gripping the liners  12  may be different from those described and illustrated. In alternative embodiments, the elements for gripping the liners  12  from the top of the stack  26  could be magnetic or mechanical gripping elements (pincers or the like). In the same way, other types of elements could be used by the gripping tool  44  for gripping the liners  12 , for example, suction, magnetic or mechanical means, etc.