Device For Heat-Welding Superposed Flaps Of A Wrapping Enveloping A Set Of Articles

Abstract

The device ( 1 ) is associated, in line, to an outlet of a packing machine and is designed to seal superposed flaps (Ls, Li) of packs (C), at longitudinal vertical sides (V) thereof. The device includes apparatus ( 2 ) for receiving and moving the packs (C) and includes two batteries ( 3, 4 ) of heat-welding rollers ( 30, 40 ), having a vertical axis, for acting on respective longitudinal vertical sides (V) in order to heat the flaps (Ls, Li) up to a temperature which is sufficient to cause joining by aggregation of the packing material. Cooling is provided downstream of the batteries ( 3, 4 ) for acting on the flaps (Ls, Li) in order to lower the temperature thereof and thus stabilize the joint.

1 . A device for heat-welding superposed flaps of a wrapping enveloping a pack of articles, for associating downstream of a packing machine in which the pack (C) of articles is formed, the flaps being arranged at longitudinal vertical sides (V) thereof, and folded in a predetermined order such that an upper flap (Ls) is external of and superposed on a lower flap (Li) and a superposing strip (S) develops horizontally, the device comprising:
 two batteries ( 3 ,  4 ) of heat-welding rollers ( 30 ,  40 ) symmetrically opposite one another, the rollers ( 30 ,  40 ) of each battery ( 3 ,  4 ) being arranged with relative axes thereof disposed vertically, the two batteries ( 3 ,  4 ) being mutually flanked and destined to intercept in succession a corresponding longitudinal vertical side (V) of the pack (C), also including the strip (S) for superposing on the flaps (Ls, Li) in order to heat the flaps (Ls, Li) up to a temperature which is sufficient to cause joining thereof by aggregation of a material of which the flaps (Ls, Li) and the strip (S) are made;   tilting support means ( 31 ,  41 ) associated to each of the rollers ( 30 ,  40 ) and enabling each of the rollers ( 30 ,  40 ) to press elastically on the flaps (Ls, Li) in a transversal direction to the pack (C), consequently to intercepting of the longitudinal vertical side (V) and independently of the other rollers ( 30 ,  40 );   cooling means ( 5 ) arranged downstream of the batteries ( 3 ,  4 ) of rollers for acting on the flaps (Ls, Li) which have been superposed and heat- welded by the batteries ( 3 ,  4 ) of rollers, which cooling means ( 5 ) lower a temperature of the flaps ( 3 ,  4 ) and stabilize the joining thereof; means ( 2 ) for receiving the packs (C), at an end of a conveyor line (T) comprised in the packing machine, the means ( 2 ) for receiving also moving the packs (C) downstream of the packing machine, in a same direction, same orientation and with a velocity which is at least equal to a velocity of the conveyor line (T), for a tract of a length which enables the packs (C) to transit first to the batteries ( 3 ,  4 ) of heat-welding rollers and then to the cooling means ( 5 ).   
     
     
         2 . The device of  claim 1 , wherein the heat-welding rollers ( 30 ,  40 ) are borne idle on the respective tilting support means ( 31 ,  41 ). 
     
     
         3 . The device of  claim 1 , wherein the heat-welding rollers ( 30 ,  40 ) exhibit a lateral surface having a high degree of roughness. 
     
     
         4 . The device of  claim 1 , wherein the tilting support means ( 31 ,  41 ) are constituted by a right-angled lever, centrally articulated at a vertex thereof, with an arm thereof bearing the relative roller ( 30 ,  40 ) and with a remaining arm thereof subjected to an action of elastic means ( 32 ,  42 ) included for enabling the roller ( 30 ,  40 ) to press elastically on the flaps (Ls, Li), in a transversal direction to the pack (C), consequently to the intercepting of the longitudinal vertical side (V). 
     
     
         5 . The device of  claim 1 , further comprising heating means ( 130 ,  140 ,  230 ,  240 ) provided for the heat-welding rollers ( 30 ,  40 ) and for maintaining the heat-welding rollers ( 30 ,  40 ) at a predetermined temperature. 
     
     
         6 . The device of  claim 5 , wherein the heating means ( 130 ,  140 ) operate with hot air and comprise a semicircular casing ( 131 ,  141 ), designed to partially circumscribe the relative roller ( 30 ,  40 ) and at least an input conduit ( 132 ,  142 ) of hot air, opening into a space existing between the casing ( 131 ,  141 ) and the lateral surface of the roller ( 30 ,  40 ), the hot air being destined to strike and heat the roller ( 30 ,  40 ), as well as exiting from a zone in which the roller ( 30 ,  40 ) enters into contact with the corresponding vertical side (V) of the pack (C), and thus further heating the plastic material of the wrapping. 
     
     
         7 . The device of  claim 5 , wherein the heating means ( 230 ,  240 ) exhibit an electrical resistance and operate with hot air and comprise: a semicircular casing ( 231 ,  241 ) designed to partially circumscribe the relative roller ( 30 ,  40 ), the roller ( 30 ,  40 ) being constituted by a fixed shaft ( 30 A,  40 A) on which an external surface ( 30 C,  40 C) is rotatably borne, the external surface ( 30 C,  40 C) being provided with a plurality of radial holes ( 30 D,  40 D); at least an electrical resistance ( 232 ,  242 ) housed internally of an axial hole provided in the fixed shaft ( 30 A,  40 A); an input conduit ( 233 ,  243 ) destined to enable air to flow internally of the axial hole of the fixed shaft ( 30 A,  40 A), which air is destined to be heated by the electrical resistance ( 232 ,  242 ); radial holes ( 30 F,  40 F), provided in the central portion of the fixed shaft ( 30 A,  40 A), which radial holes ( 30 F,  40 F) place the axial hole of the fixed shaft ( 30 A,  40 A) in communication with an annular chamber ( 30 G,  40 G) identified between the fixed shaft ( 30 A,  40 A) and the external surface ( 30 C,  40 C), the hot air together with the heat radiated by the electrical resistance ( 232 ,  242 ) heating the external surface ( 30 C,  40 C) as well as to exit through the radial holes ( 30 D,  40 D) present therein, in order to further heat the plastic material of the wrapping. 
     
     
         8 . The device of  claim 7 , wherein a longitudinal flat portion ( 30 F,  40 F) is located in a central portion of the fixed shaft ( 30 A,  40 A), at the position of the radial holes ( 30 F,  40 F). 
     
     
         9 . The device of  claim 1 , wherein the means ( 2 ) for receiving and moving the packs (C) comprise:
 an inlet group ( 10 ) for intercepting the longitudinal vertical sides (V) of the packs (C), in outlet from the conveyor line (T) upstream of the batteries ( 3 ,  4 ) of rollers; clutch means, associated to the inlet group ( 10 ), destined to aid a transitory increase in velocity of the packs (C) on outlet from the conveyor line (T);   connecting planes ( 13 ,  14 ) respectively situated upstream and downstream of the inlet group ( 10 ), destined to facilitate entry and exit of the pack (C) into and out of the inlet group ( 10 );   upper conveyor straps ( 21 ) and lower conveyor straps ( 22 ), respectively included for contactingly receiving the horizontal upper side (Os) and the horizontal lower side (Oi) of the pack (C), extending downstream of the inlet group ( 10 ) and being destined to cooperate with the inlet group ( 10 ) for advancing the pack (C).   
     
     
         10 . The device of  claim 1 , wherein the means ( 2 ) for receiving and moving the packs (C) comprise:
 an inlet group ( 10 ), destined to intercept the longitudinal vertical sides (V) of the packs (C) in outlet from the conveyor line (T), and located before the batteries ( 3 ,  4 ) of rollers; clutch means, associated to the inlet group ( 10 ), destined to aid transitory increases in velocity of the packs (C) on outlet from the conveyor line (T);   connecting planes ( 13 ,  14 ), respectively situated upstream and downstream of the inlet group ( 10 ), destined to facilitate entry and exit of the packs (C) into and out of the inlet group ( 10 );   powered heat-welding rollers ( 30 M,  40 M) included in the batteries ( 3 ,  4 ) destined to cooperate with the inlet group ( 10 ) for advancing the pack (C);   a sliding plane for horizontally supporting the pack (C).   
     
     
         11 . The device of  claim 9 , wherein the inlet group ( 10 ) is constituted by a pair of conveyor belts ( 11 ,  12 ) arranged symmetrically, each of which is ring-wound and stretched about corresponding pairs of pulleys, respectively a drive pulley ( 110 ,  120 ) and a driven pulley ( 111 ,  121 ) having relative vertical axes, the clutch means having freewheel mechanisms, interposed between the drive pulleys ( 110 ,  120 ) and the respective shafts, for enabling free rotation of the drive pulleys ( 110 ,  120 ) with respect to the shafts in the advancement direction, while maintaining the constraint in the opposite direction. 
     
     
         12 . The device of  claim 11 , wherein operative branches ( 11 A,  12 A) of the belts ( 11 ,  12 ) are subjected to action of the respective stretcher rollers ( 112 ,  122 ) which ensure contact with the vertical sides (V) of the pack (C). 
     
     
         13 . The device of  claim 10 , wherein the inlet group ( 10 ) is constituted by two series of drive rollers, arranged symmetrically, with the rollers borne with a vertical axis by relative tilting support means, and in that the clutch means have freewheel mechanisms, interposed between each of the drive rollers and the relative drawing gear, for enabling free rotation of the drive roller with respect thereto in the advancement direction, while maintaining the constraint in the opposite direction. 
     
     
         14 . The device of  claim 10  wherein the inlet group ( 10 ) is constituted by a pair of conveyor belts ( 11 ,  12 ) arranged symmetrically, each of which is ring-wound and stretched about corresponding pairs of pulleys, respectively a drive pulley ( 110 ,  120 ) and a driven pulley ( 111 ,  121 ) having relative vertical axes, the clutch means having freewheel mechanisms, interposed between the drive pulleys ( 110 ,  120 ) and the respective shafts, for enabling free rotation of the drive pulleys ( 110 ,  120 ) with respect to the shafts in the advancement direction, while maintaining the constraint in the opposite direction. 
     
     
         15 . The device of  claim 14 , wherein operative branches ( 11 A,  12 A) of the belts ( 11 ,  12 ) are subjected to action of the respective stretcher rollers ( 112 ,  122 ) which ensure contact with the vertical sides (V) of the pack (C).