A new manufacturing process has been developed for reducing the diameter
of one end of a tinplate can by over 30%. Conventional processes are limited
to a maximum of 10% reduction and typically operate at less than 5%. The
improvement was achieved by using special tooling and ultrasonic excitation
of the die to reduce the forming force.
Ultrasonics have been used in this way before but without a full
understanding of the numerous modes of vibration of the die, and how they
interact, the efficiency of earlier systems was low. Finite element analysis has
been used to characterize the natural modes and frequencies of radial-mode
ultrasonic dies and this has led to the development of highly efficient
systems. In special cases a non-round die has been required to overcome
undesirable modal characteristics; optimum shapes have been developed. A
completely new method of mounting the ultrasonic dies was designed and its
geometry optimized (again using finite element analysis) to further improve
the efficiency of the system.
The new system operates at an amplitude under load approximately three
times greater than the earlier equipment. The reduction in forming force
(between 30 and 60%) makes the difference between success and failure for
the manufacturing process.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.