The punch pressure required to injection upset a cylindrical billet of an isotropic, non-work-hardening, rigid–plastic material is derived using an upper bound (velocity field) technique and by a ‘slab’ stress analysis. A method for applying the theory to the injection upsetting of work-hardening materials is evolved and the validity of this application is demonstrated by the results of experiments using pure aluminium, an aluminium alloy and copper.
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