Extending the range of die-less sheet forming processes

: (Alternative Format Thesis)

Abstract

To remain competitive, manufacturers now require agile, flexible processes that are capable of creating a diversified portfolio of parts in a sustainable and cost effective manner. This demand is prevalent in the manufacture of sheet metal parts. However most industrialised sheet forming processes are optimised for mass production and are inflexible, owing to the dependence on rigid, part-specific tooling. This has resulted in the development of new, flexible forming processes that are characterised by an ability to form a wide range of parts without the need for bespoke tooling.

In pursuit of new flexible forming processes, a useful starting point for process designers is to look back at the versatile tools and techniques used by the traditional metal Smith. In a comprehensive review, a number of tools and techniques used by the Smith to form parts are identified and a taxonomy of manual processes assembled. Automated adaptations of these processes are reviewed with the methods used to automate both the physical actions and decision making elements (control) compared. With automated adaptations not yet as effective as their manual counterpart, a number of methods are identified that can be used to improve the efficiency of automated processes by learning from the Smith.

The focus of this thesis surrounds the English wheel, a tool found in most Smith's workshop, but has received little attention from the flexible forming community. A finite element (FE) model of the process is developed with particular care taken to define sheet properties and boundary conditions that replicate the physical process. The model provides insight on the mechanics of the process, showing how the sheet stretches in the region where the tools make contact with the sheet and bend just beyond this region in the transverse to wheeling direction. Physical trials are carried out using a novel 8-axis CNC machine. Formed parts are doubly curved with greater profile variations observed along the transverse to wheeling direction. Greater curvatures are observed at regions transitioning between less and more densely wheeled areas. The effects of sheet trajectories and machine configurations are explored using both the FE model and physical trials.

Date of Award	29 Mar 2023
Original language	English
Awarding Institution	University of Bath
Supervisor	Evros Loukaides (Supervisor), Andrew Plummer (Supervisor) & Alborz Shokrani Chaharsooghi (Supervisor)