Cooling apparatus and method for cooling a continuous strip

Abstract

The invention relates to a cooling apparatus and a method for cooling a continuous strip, wherein the cooling apparatus comprises a cooling drum and a guiding device for guiding the strip in a plurality of windings around the cooling drum, wherein the guiding device comprises first and second guiding elements, wherein each one of the first guiding elements forms a set with one of the second guiding elements, wherein the first guiding element of the set receives the strip from a first winding in a first winding direction and directs the strip in a first transition direction towards the second guiding element which receives the strip in a second transition direction and directs the strip into a consecutive winding in a second winding direction, wherein the first transition direction is different from the first winding direction and the second transition direction is different from the second winding direction.

1 . A cooling apparatus for cooling a continuous strip, wherein the cooling apparatus comprises a cooling drum with a cylindrical cooling surface that extends in a circumferential direction and has a rotation axis concentric to the cooling surface and extending in an axial direction, wherein the cooling drum is arranged for receiving the continuous strip in a plurality of windings around the cooling surface, wherein the plurality of windings comprises an outfeed winding where the continuous strip ultimately leaves the cooling drum, wherein the cooling apparatus further comprises an outfeed pulling member for feeding the continuous strip out of the outfeed winding away from the cooling drum, wherein the cooling apparatus further comprises a control unit that is operationally connected to the cooling drum to control the rotational speed of said cooling drum, wherein the control unit is operationally connected to the outfeed pulling member and configured to control the outfeed pulling member such that it pulls on the continuous strip at an outfeed rate that is higher than the rotational speed of the cooling drum. 
     
     
         2 . The cooling apparatus according to  claim 1 , wherein the outfeed speed is at least five percent or at least ten percent higher than the rotational speed of the cooling drum. 
     
     
         3 . The cooling apparatus according to  claim 1 , wherein the cooling apparatus further comprises a guiding device with a plurality of guiding elements for guiding the continuous strip in the plurality of windings around the cooling surface. 
     
     
         4 . The cooling apparatus according to  claim 3 , wherein the outfeed winding extends over at least a quarter up to at least three quarters of the circumference of the cooling surface in the circumferential direction after the continuous strip has left the last of the guiding elements. 
     
     
         5 . The cooling apparatus according to  claim 1 , wherein the plurality of windings comprises an infeed winding where the continuous strip is first applied to the cooling drum, wherein the cooling apparatus comprises an infeed pulling member for feeding the continuous strip into the infeed winding at an infeed speed, wherein the control unit is operationally connected to the infeed pulling member and configured to control the infeed pulling member such that the infeed speed is lower than the rotational speed of the cooling drum. 
     
     
         6 . A production line for producing a continuous strip, wherein the production line comprises an extruder for extruding the continuous strip at a variable extrusion speed, a cooling apparatus according to  claim 1  for cooling the continuous strip and a buffer member between the extruder and the cooling apparatus to absorb variations in the extrusion speed, wherein the production line further comprises a control unit that is operationally connected to the cooling drum to control the rotational speed of said cooling drum, wherein the control unit is operationally connected to the outfeed pulling member and configured to control the outfeed pulling member such that it pulls on the continuous strip at an outfeed speed that is higher than the rotational speed of the cooling drum. 
     
     
         7 . The production line according to  claim 6 , wherein the plurality of windings comprises an infeed winding where the continuous strip is first applied to the cooling drum, wherein the cooling apparatus comprises an infeed pulling member that is located between the buffer member and the cooling drum for feeding the continuous strip into the infeed winding at an infeed speed, wherein the control unit is operationally connected to the infeed pulling member and configured to control the infeed pulling member such that the infeed speed is lower than the rotational speed of the cooling drum. 
     
     
         8 . A method for cooling a continuous strip using the cooling apparatus according to  claim 1 , wherein the method comprises receiving the continuous strip in a plurality of windings around the cooling surface, wherein the plurality of windings comprises an outfeed winding where the continuous strip ultimately leaves the cooling drum, wherein the method further comprises the step of pulling on the continuous strip that leaves the outfeed winding at an outfeed speed that is higher than the rotational speed of the cooling drum. 
     
     
         9 . The method according to  claim 8 , wherein the plurality of windings comprises an infeed winding where the continuous strip is first applied to the cooling drum, wherein the method comprises the step of feeding the continuous strip into the infeed winding at an infeed speed that is lower than the rotational speed of the cooling drum. 
     
     
         10 . The method according to  claim 9 , wherein the method further comprises the step of winding the outfeed winding over at least a quarter up to at least three quarters of the circumference of the cooling surface in the circumferential direction after the continuous strip has left the last of the guiding elements. 
     
     
         11 . A cooling apparatus for cooling a continuous strip, wherein the cooling apparatus comprises a cooling drum with a cylindrical cooling surface that extends in a circumferential direction and has a rotation axis concentric to the cooling surface and extending in an axial direction, wherein the cooling drum is arranged for receiving the continuous strip in a plurality of windings around the cooling surface, wherein the plurality of windings comprises an infeed winding where the continuous strip is first applied to the cooling drum, wherein the cooling apparatus comprises an infeed pulling member for feeding the continuous strip into the infeed winding at an infeed speed, wherein the cooling apparatus further comprises a control unit that is operationally connected to the cooling drum to control the rotational speed of said cooling drum, wherein the control unit is operationally connected to the infeed pulling member and configured to control the infeed pulling member such that the infeed speed is lower than the rotational speed of the cooling drum. 
     
     
         12 . The cooling apparatus according to  claim 11 , wherein the infeed speed is at least five percent or at least ten percent lower than the rotation speed. 
     
     
         13 . The cooling apparatus according to  claim 11 , wherein the cooling apparatus further comprises a guiding device with a plurality of guiding elements for guiding the continuous strip in the plurality of windings around the cooling surface. 
     
     
         14 . The cooling apparatus according to  claim 13 , wherein the infeed winding extends over at least a quarter up to at least three quarters of the circumference of the cooling surface in the circumferential direction prior to receiving the continuous strip at the first of the guiding elements. 
     
     
         15 . The cooling apparatus according to  claim 11 , wherein the continuous strip is fed to the cooling apparatus from below. 
     
     
         16 . The cooling apparatus according to  claim 11 , wherein the continuous strip is fed to the cooling apparatus from above. 
     
     
         17 . A production line for producing a continuous strip, wherein the production line comprises an extruder for extruding the continuous strip at a variable extrusion speed, a cooling apparatus according to  claim 11  for cooling the continuous strip and a buffer member between the extruder and the cooling apparatus to absorb variations in the extrusion speed, wherein the production line further comprises a control unit that is operationally connected to the cooling drum to control the rotational speed of said cooling drum, wherein the control unit is operationally connected to the infeed pulling member and configured to control the infeed pulling member such that the infeed speed is lower than the rotational speed of the cooling drum. 
     
     
         18 . A method for cooling a continuous strip using the cooling apparatus according to  claim 11 , wherein the method comprises receiving the continuous strip in a plurality of windings around the cooling surface, the plurality of windings comprises an infeed winding where the continuous strip is first applied to the cooling drum, wherein the method comprises the step of feeding the continuous strip into the infeed winding at an infeed speed that is lower than the rotational speed of the cooling drum. 
     
     
         19 . Method according to  claim 16 , wherein the method further comprises the step of winding the infeed winding over at least a quarter up to at least three quarters of the circumference of the cooling surface in the circumferential direction prior to receiving the continuous strip at the first of the guiding elements.