Investigation into the rolling of profiled rings.
Three aspects of ring rolling are investigated in this thesis, single stage
closed-pass rolling, multi-stage rolling and radial-axial rolling.
In Chapter Two, which deals with single stage closed-pass rolling, the rolling of
a range of symmetrical and non-symmetrical profiles is investigated., The effects of
feed rate, lubrication, small variations in the geometry of the roll and blank shape
on profile filling are examined experimentally. The occurrence of defects and surface
cracking and the stability of rolling when producing non-symmetrical profiles are
examined. Rolling force and torque are predicted theoretically and comparisons with
experimental results are made.
In Chapter Three the production of a bicycle rim is investigated, following an
enquiry from a cycle manufacturer. A multi-stage ring rolling operation is employed.
The problems of profile filling, cracking and surface finish are solved. 'Means of
providing stability to the rolling process and diameter control are developed and
tested. The circumference is controlled to within 1 mm with radial thickness
variations within 1% of the specified thickness. Various aluminium alloys and a
magnesium alloy are used as test materiaLs. A theory for the dimensional limitations
in relation to profile folding in the final stage is given.
In Chapter Four a newly installed experimental axial rolling system is described.
The system was designed and manufactured in the Department and it was provided with
control and measuring equipment. Stability of the rolling process is examined
theoretically and experimentally for axial and radial-axial ring rolling operations
and the control system is examined. Rolling force and torque and power dissipation
are predicted theoretically and compared with experimental results.