Knowledge-Based System For Computer-Aided Process Planning With Finite Element Predictions
The knowledge-based system COFEX (Cold Forging Expert) has been developed to assist in the planning of the cold forging of a wide variety of tubular steel components. Following user-input of the required shape and dimensions of the finished forging, together with as many different sequences as desired, each operation is examined by the system by consulting the knowledge-base process rules and data. Messages give the reason if any of the operations is unacceptable. If manufacture by cold forging is feasible, the dimensioned drawings of the finished and semi-finished forgings, together with the process parameters are displayed. Subsequently the suitability of existing presses are checked or new ones specified, the cost of the forging is computed and the sensitivity of the costs to various factors assesses. If heading is included in the sequence it can be checked by the finite element analysis whether or not plastic buckling and subsequent folding defect is likely to occur, and forging loads, stresses and strains predicted.
Cold Extrusion of Flanges on Cylindrical Hollows
Flanges on hollow cylindrical engineering components are often made by free upsetting when under certain conditions a bulge is formed in the unsupported portion, which on further deformation appears as a fold in the finished flange.
THE INHOMOGENEOUS DEFORMATION OF HOLLOW CYLINDERS SUBJECTED TO STATIC AND DYNAMIC AXIAL COMPRESSION
Abstract Experiments are described in which hollow cylinders of mild steel were subjected to stalic compression, both where the operation was stopped freqnenily to effect re-lubrication, and where the operation was continuous. Previous observations relating to the rolling of material from the walls of the specimen onto the compression plaiens are illustrated and discussed. The effects of specimen/platen friction on the interpenetration of the “dead meta zones“ or “pressure cones“ and the resultant effects upon force-displacement characleristics and axially inhomogeneous deformation of the specimen are demonstrated. Further tests carried out dynamically at both room and elevated temperature are described. The mechanism whereby a sharp “tongue“ of material is caused to project from the inner wall at high fractional reductions —also observed in ihe use of Plasticenef specimens—is illustrated.