Winding shaft for a winder

Abstract

The invention relates to a winding shaft for winding a continuous flexible material web into a roll. The winding shaft has means in order to adjust the diameter of the winding shaft surface to be wound between a reduced-diameter unused position and an expanded operating position, and the winding surface in the expanded position is formed jointlessly with a uniform curvature and is supported inward against the operational pressure around said winding surface in a dimensionally stable manner that is substantially uniform. A roll can thereby be wound without disruptions and then stored without a casing until the roll “dies”, said roll remaining stable during storage and not forming any disrupted zones on the inner face of the roll.

1 . A winding shaft for a winder for the winding of a continuous, flexible plastic film to form a roll, which comprises a surface to be wound on, characterised in that it comprises means for adjusting the diameter of its surface to be wound on between a diameter-reduced rest state and an expanded operating state, wherein the surface to be wound on in the expanded state is constituted gapless with a uniform curvature and is supported inwardly all round against the operating pressure in a dimensionally stable manner that is essentially uniform. 
     
     
         2 . The winding shaft according to  claim 1 , with radially movable segments for the adjustment between the rest state and the operating state, wherein the means comprise a winding shaft core elastically expandable in the circumference, the outer surface whereof forms the surface to be wound of the winding core, and into which supporting elements running over at least the length of the surface to be wound are moulded, said supporting elements in the expanded operating state lying with a predetermined spacing from one another. 
     
     
         3 . The winding shaft according to  claim 2 , wherein the supporting elements are constituted as supporting shells, which in the interior of the winding shaft core run on a common diameter between the surface to be wound and the inner surface and lie side by side with a spacing from one another in the expanded state of the winding shaft, and wherein the supporting shells are disposed with respect to radially extendable segments in such a way that each intermediate space between radially extendable segments is overlapped by an associated supporting shell. 
     
     
         4 . The winding shaft according to  claim 2 , wherein the supporting elements are constituted as supporting shells, the inner surfaces whereof form sections of the inner surface of the winding shaft core. 
     
     
         5 . The winding shaft according to  claim 3  or  4 , wherein the supporting shells run in the form of a helical line along the length of the winding shaft core and the helical line extends over the length of the windable surface less than a half, preferably less than a third, particularly preferably less than a quarter of a full revolution. 
     
     
         6 . The winding shaft according to any one of  claims 2  to  5 , wherein the winding shaft core comprises an elastically expandable material, preferably a plastic such as polyurethane with an admixture of rubber, the expandability whereof permits the change in the circumferential length between the rest state and the operating state. 
     
     
         7 . The winding shaft according to any one of  claims 2  to  6 , wherein the supporting elements comprise a material which is harder than the expandable material of the winding shaft core, and are preferably made of a sheet metal or glass fibre-reinforced or carbon fibre-reinforced plastic. 
     
     
         8 . The winding shaft according to  claim 3  or  4 , wherein the supporting shells taper from a central region between the longitudinal edges towards the latter. 
     
     
         9 . The winding shaft according to any one of the preceding claims, with radially movable segments for the adjustment between the rest state and the operating state, wherein the segments are disposed over the length of the windable surface in the form of a helical line on the winding shaft and the helical line is preferably less than a half, preferably less than a third, particularly preferably less than a quarter of a full revolution. 
     
     
         10 . The winding shaft according to any one of the preceding claims, wherein its mass in the expanded state is counterbalanced dynamically towards its axis of rotation. 
     
     
         11 . A method for producing a winding shaft according to  claim 2 , wherein, in the retracted state of the radially movable segments, an elastic material is cast over the length on the rotating winding shaft until the latter is covered with a layer of the material all round at least over the length of the surface to be wound on, after which the supporting elements are brought onto this layer and a further layer of the material is cast onto the rotating winding shaft until the intended thickness of the winding shaft core has been reached, and wherein the winding shaft core expands after the hardening of the cast elastic material and is worked in the expanded state into a round shape with respect to the axis of rotation of the winding shaft, until the surface to be wound on is constituted cylindrical and coaxial with respect to the axis of rotation. 
     
     
         12 . The method according to  claim 5 , wherein the surface to be wound, after being worked into a round shape, is subsequently ground, up to quality N6, preferably N7. 
     
     
         13 . A winding shaft core for a winding shaft constituted so as to be diameter-adjustable between the rest state and the operating state, for the winding of a continuous, flexible plastic film to form a roll, wherein the winding shaft core comprises a surface to be wound, characterised in that the winding shaft core also comprises means for adjusting the diameter of its surface to be wound between a diameter-reduced rest state and an expanded operating state, wherein the surface to be wound in the expanded state is constituted gapless with a uniform curvature and is supported inwardly all round against the operating pressure in a dimensionally stable manner that is essentially uniform. 
     
     
         14 . The winding shaft core according to  claim 13 , wherein the means comprise a winding shaft core elastically expandable in the circumference, the outer surface whereof forms the surface to be wound of winding shaft, and into which supporting elements running over at least the length of the surface to be wound are moulded, said supporting elements in the expanded operating state lying with a predetermined spacing from one another. 
     
     
         15 . The winding shaft core according to  claim 14 , wherein the supporting elements are constituted as supporting shells, which in the interior of the winding shaft core run on a common diameter between the surface to be wound and its inner surface and lie side by side with a spacing from one another in the expanded state of the winding shaft core. 
     
     
         16 . The winding shaft core according to  claim 14 , wherein the supporting elements are constituted as supporting shells, the inner surfaces whereof form sections of the inner surface of the winding shaft core. 
     
     
         17 . The winding shaft core according to  claim 14  or  15 , wherein the supporting shells run in the form of a helical line along the length of the winding shaft core and the helical line extends over the length of the windable surface less than a half, preferably less than a third, particularly preferably less than a quarter of a full revolution. 
     
     
         18 . The winding shaft core according to any one of  claims 14  to  16 , wherein the winding shaft core comprises an elastically expandable material, preferably a plastic such as polyurethane with an admixture of rubber, the expandability whereof permits the change in the circumferential length between the rest state and the operating state. 
     
     
         19 . The winding shaft core according to any one of  claims 14  to  17 , wherein the supporting elements comprise a material which is harder than the expandable material of the winding shaft core, and are preferably made of a sheet metal or glass fibre-reinforced or carbon fibre-reinforced plastic. 
     
     
         20 . The winding shaft core according to  claims 14  to  19 , wherein the supporting shells taper from a central region between the longitudinal edges towards the latter.