the prior art as shown in fig1 this interior shaping unit provides an additional pressure area 8 against the interior of the workpiece 9 by the contact pressure of the inner reshaping rollers said area 8 extending radially outward from the interior of the workpiece 9 this is shown in fig4 two pressure areas 7 8 that overlap each other are formed by the shaping units on both sides thus significantly increasing the available reduction potential of the wall thickness 10 or permitting a higher degree of stiffness of the material to be reshaped with a constant reduction in wall thickness in the illustrated example this interior shaping unit based on the invention includes a number of conic rollers tangential to the workpiece 9 that may be mounted as reshaping rollers 11 particularly in a cage 12 13 that may be repositioned tangentially and axially with respect to the workpiece 9 the cage is held together using threaded fasteners 14 and may be adjusted axially the reshaping rollers 11 rest against an inner mandrel 16 that is particularly conic and that is secured to an extension section 17 whose diameter is smaller than the shaped inner workpiece diameter 18 or smaller than the inner workpiece diameter 18 to be shaped the reshaping rollers 11 are thus particularly held in position tangentially and axially by the cage 12 13 and radially by the inner mandrel 16 this arrangement ensures that the reshaping rollers do not fall out of the interior shaping unit when the interior shaping unit is located outside of the workpiece 9 because of design and configuration of these reshaping rollers 11 a maximum number of reshaping rollers is possible that exert the maximum possible reshaping force on the inner walls of the workpiece.