Device for tightening and sealing plastic packaging straps

Abstract

The device according to the invention for tensioning and sealing plastic strapping bands for packages has a housing ( 11 ), a band channel ( 14 ) extending in the longitudinal direction of the strapping band ( 12 ), which is open on one side and which receives the band ends ( 19,20 ), which channel is limited on one of its side by a tensioning plate ( 16 ) and on its other side by a tensioning wheel ( 18 ) provided with a profiling, whereby the tensioning wheel and the tensioning plate can be abutted relatively to one another. So as to be able to exert a large tensioning force on the band ends even with a small abutment force between the tensioning wheel and the tensioning plate, without damaging the band by rotating the tensioning wheel, it is suggested by the invention that the profiling consists of first transverse profile grooves ( 27 ) running approximately in the axial direction of the tensioning wheel and of second circumferential profile grooves ( 29 ) running in the circumferential direction, whereby the transverse profile grooves comprise a smaller slot depth than the circumferential profile grooves. Tensioning teeth ( 30 ) are formed at the circumference of the tensioning wheel by this arrangement, which teeth penetrate up to the depth of the transverse profile grooves into the band even with a small abutment force between tensioning plate and tensioning wheel, and ensure a transfer of high tensioning forces.

1 . Device for tightening and closing plastic strapping bands for packages or the like, having a housing, a band channel extending in the longitudinal direction of the strapping band in the housing, which is open on one side and which receives the opposed band ends of the strapping band which are to be tensioned mutually, which channel is limited on one side by a tensioning plate and on the other side by a tensioning wheel provided with a profiling, whereby the tensioning wheel and the tensioning plate can be abutted relatively to one another, characterised in that the profiling ( 25 ) consists of first transverse profile grooves ( 27 ) running approximately in the axial direction ( 26 ) of the tensioning wheel ( 18 ) and of second circumferential profile grooves ( 29 ) running in the circumferential direction, whereby the transverse profile grooves ( 27 ) comprise a smaller slot depth (t) than the circumferential profile grooves ( 29 ).  
     
     
         2 . Device according to  claim 1 , characterised in that the circumferential profile grooves ( 29 ) and/or the transverse profile grooves ( 27 ) have an approximately V-shaped or trapezoidal cross section which tapers towards the groove base lying radially inwards.  
     
     
         3 . Device according to  claim 1  or  2 , characterised in that the circumferential profile grooves ( 29 ) have a V-shaped cross section, and the transverse profile grooves ( 27 ) have a trapezoidal cross section which tapers towards the groove base ( 37 ) lying radially inwards.  
     
     
         4 . Device according to one of  claims 1  to  3 , characterised in that the circumferential and/or transverse profile grooves ( 29  or  27 ) form approximately pyramidal pointed tensioning teeth ( 30 ) between each other.  
     
     
         5 . Device according to one of  claims 1  to  4 , characterised in that the transverse profile grooves ( 27 ) have a slot depth which is smaller than the thickness (D) of the thinnest strapping band ( 12 ) to be processed.  
     
     
         6 . Device according to one of  claims 1  to  5 , characterised in that the tip angle (α) of the tensioning teeth which is enclosed by the groove walls ( 31 ) of the profile grooves ( 27 , 29 ) of the tensioning teeth ( 30 ) is smaller than 60°.  
     
     
         7 . Device according to  claim 6 , characterised in that the tip angle (α) is between 35° and 45°.  
     
     
         8 . Device according to one of  claims 1  to  7 , characterised in that the slot depth (T) of the circumferential profile grooves ( 29 ) is about 1.5 to 3 times of the slot depth (t) of the transverse profile grooves ( 27 ).  
     
     
         9 . Device according to one of  claims 1  to  8 , characterised in that the slot depth (t) of the transverse profile grooves ( 27 ) is between 0.2 and 0.4 mm and the slot depth (T) of the circumferential profile grooves ( 29 ) is between 0.6 and 1 mm.  
     
     
         10 . Device according to one of  claims 1  to  9 , characterised in that the tensioning plate ( 16 ) is provided with holding teeth ( 32 ) running in the longitudinal direction of the band channel ( 14 ) which engage the into the circumferential profile grooves ( 29 ) in the tensioning position of the tensioning plate ( 16 ) and the tensioning wheel ( 18 ) a bit.  
     
     
         11 . Device according to one of  claims 1  to  10 , characterised by a sealing mechanism ( 42 ) guiding the tensioning wheel ( 18 ) in the tensioning position relative to the tensioning plate ( 16 ) in the axial direction ( 26 ) of the tensioning wheel.  
     
     
         12 . Device according to  claim 11 , characterised in that the sealing mechanism ( 42 ) essentially consists of a guide finger ( 43 ) projecting from the tensioning plate ( 16 ), engaging a circulating guide groove ( 44 ) in the tensioning wheel ( 18 ) in the circumferential direction ( 28 ).  
     
     
         13 . Device according to  claim 12 , characterised in that the guide finger ( 43 ) abuts the guide groove base ( 46 ) of the guide groove ( 44 ) with its free end ( 45 ) in the tensioning position when the band is not inserted.  
     
     
         14 . Device according to one of  claims 1  to  13 , characterised in that the guide groove ( 44 ) forms a centring guide ( 47 ) for the guide finger ( 43 ) in its radial outward region.  
     
     
         15 . Device according to one of  claims 1  to  14 , characterised by a cleansing device ( 34 ) assigned to the tensioning wheel ( 18 ) for the profile grooves ( 27 , 29 ).  
     
     
         16 . Device according to one of  claims 1  to  15 , characterised in that the cleansing device ( 34 ) essentially consists of a cleansing block ( 35 ) having cleansing teeth ( 37 ) which engage the circumferential profile grooves ( 29 ).  
     
     
         17 . Device according to one of  claims 1  to  16 , characterised in that the cleansing teeth ( 37 ) reach the bottom of the groove ( 39 ) of the circumferential profile grooves ( 29 ).  
     
     
         18 . Device according to one of  claims 1  to  17 , characterised in that the cleansing device ( 34 ) abuts the tensioning wheel ( 18 ) under the action of a pressure spring ( 41 ).  
     
     
         19 . Device according to one of  claims 1  to  18 , characterized in that the cleansing block ( 35 ) is approximately wedge-shaped and abuts the tensioning wheel ( 18 ) with its free wedge edge ( 36 ).  
     
     
         20 . Device according to one of  claims 1  to  19 , characterised in that the cleansing block ( 35 ) consists of a soft material, in particular of brass alloy.