Coiler for very thin metal strip

Abstract

To enable safe coiling of very thin metals at high speed, the invention discloses a coiler comprising a mandrel of considerably smaller diameter then prior art mandrels, enabling said mandrel to be directly driven by an electric motor without using reduction gears. The coil outer diameter is also reduced, the result being a coiler having far lower polar moment of inertia than prior art coilers, therefore greatly reducing the incidence of tension errors and strip breaks. The mandrel is constructed specifically for operation with a spool upon which the coil is wound, and incorporates the novel feature of concentric expansion using a plurality of circumferentially oriented wedges, which ensures uniform support and grip of the spool bore, holding said spool and coil concentric with the axis of the mandrel.

What is claimed is: 
     
         1 . A coiler for coiling a thin metal strip on a rolling mill, wherein said metal strip is coiled on a hollow cylindrical spool mounted on a collapsible mandrel, said mandrel being expanded to grip the inside diameter of said spool, and, in order to minimize the polar moment of inertia of the rotary parts, said mandrel is directly coupled to an electric motor, without intermediate gears or pulleys, and said mandrel expansion is achieved by synchronized radial movement of a plurality of at least eight support members, said support members consisting of metal rectangular staves slideably mounted in a hollow cylindrical cage having a plurality of axial slots equally spaced around the circumference of said cage, and within each of said axial slots one of said staves slides in a radial direction, each of said staves being held by return springs  15  in contact with one wedge of a set of identical wedges formed equally spaced on the outside of an inner sleeve, said wedges being oriented in a circumferential direction, said inner sleeve being mounted on and keyed to a cylindrical shaft, and, in order to expand the mandrel, said inner sleeve and said shaft are rotated in one of a clockwise or a counter-clockwise direction around the axis of the mandrel relative to said cage and said staves in order to cause each of said staves to ride up a wedge, the motion of all said staves being synchronized by said equal spacing of said wedges and said staves, such that the outer ends of all of said staves always lie on a true circle concentric with the mandrel axis, the diameter of said circle increasing, and thus said mandrel expanding as the staves ride up the wedges, and, in order to collapse said mandrel, said inner sleeve and said shaft are rotated in the other of said clockwise or counter-clockwise directions around the axis of the mandrel relative to said cage and said staves in order to cause each of said staves to down a wedge, the motion of all said staves being synchronized by said equal spacing of said wedges and said staves, such that the outer ends of all of said staves always lie on a true circle concentric with the mandrel axis, the diameter decreasing and thus the mandrel collapsing, as the staves ride down the wedges. 
     
     
         2 . A coiler mandrel according to  claim 1  wherein each wedge of said set of wedges is provided with a convex cylindrical surface, and each of said staves is provided with a matching concave cylindrical surface, whereby substantially full area contact is achieved between each of said wedges and its mating stave throughout the expansion stroke of said mandrel. 
     
     
         3 . A coiler mandrel according to  claim 1  whereby the orientation of said wedges and said staves relative to the direction of the strip tension torque is such that said tension torque urges the staves and cage to rotate in a direction relative to said inner sleeve and said shaft causing the staves to ride up the wedges and thus self tighten the wedges against the inside diameter of the spool. 
     
     
         4 . A coiler mandrel according to  claim 1  wherein the inner sleeve and cage are axially located upon said cylindrical shaft by a front end plate, attached to the front end of said cage and a back end plate, attached to the back end of said cage, said end plates being mounted on and keyed to said cylindrical shaft and wherein the keyways  35  in said end plates are much wider than the mating keys  16 , 17  in said cylindrical shaft, the sides of the keyways functioning as stops to limit the rotation of said end plates and cage relative to said cylindrical shaft. 
     
     
         5 . A coiler mandrel according to  claim 4  wherein said end plates each incorporate at least two hydraulic expand cylinders  22 , and said inner sleeves incorporate at least two lugs  20  at each end, the piston  21  of each of said hydraulic expand cylinders bearing against the side of a lug, so that pressurizing said hydraulic expand cylinders causes rotation of said inner sleeve and cylindrical shaft relative to said end plate said cage and said staves, causing said staves to ride up said wedges thus expanding the mandrel. 
     
     
         6 . A coiler mandrel according to  claim 5  wherein return springs  29  and plungers  39  are incorporated in said end plates to retract the pistons of said hydraulic expand cylinders, when pressure is released from said hydraulic expand cylinders in order to force said staves to ride down the wedges and thus collapse the mandrel. 
     
     
         7 . A coiler mandrel according to  claim 4  where an axial retention ring  34  is provided at the back end of the mandrel, said axial retention ring engaging with a shoulder on said cylindrical shaft, and being attached to the back end plate  18   a  by cap screws  31 , retains the mandrel assembly on said cylindrical shaft, such that removal of said cap screws enables said mandrel assembly less said axial retention ring and said cap screws to be removed from said cylindrical shaft, by sliding said mandrel assembly forward off the front end of said cylindrical shaft. 
     
     
         8 . A coiler mandrel according to  claim 4  where an oil feed ring is provided at the front end of the mandrel, said oil feed ring being bolted to the front end plate and said oil feed ring incorporating holes and seals enabling hydraulic oil to flow from a central axial hole in said cylindrical shaft to said hydraulic expand cylinders in said front end of plate. 
     
     
         9 . A coiler mandrel according to  claim 4  where oil holes are provided in said cylindrical shaft and said front and back end plates enabling hydraulic oil to be delivered to all of said hydraulic expand cylinders from a single port on the axis of said cylindrical shaft, this port being located either at the front end or the back end of said cylindrical shaft. 
     
     
         10 . A coiler mandrel according to  claim 5  where hydraulic collapse cylinders are incorporated in said end plates whose pistons each bear against the opposite side of each lug  20  from the side bearing against each hydraulic expand cylinder piston  21 , whereby releasing the pressure from said hydraulic expand cylinders and applying pressure to said hydraulic collapse cylinders causes rotation of said end plates and said cage and stave assembly relative to inner ring and cylindrical shaft, causing said staves to ride down said wedges, thus collapsing the mandrel, and, at the same time, forcing the pistons in said hydraulic expand cylinders to retract, it being clear that, to enable the mandrels subsequently to be expanded by applying pressure to said hydraulic expand cylinders, the pressure in the hydraulic collapse cylinders must first be released.