Drawing: Flat strip, round bar and tube

Abstract

Drawing: definition, purposes, demerits and fields of application. Drawing stress with friction for work-hardening and non-strain-hardening strip drawn through wedge-shaped dies. Frictionless ideal drawing stress. Maximum reduction of area in a single pass with and without friction. Drawing stress with friction for strip drawn through cylindrical dies. Treatments of work metal prior to drawing, such as heat treatment (recrystallization annealing, patenting), surface preparation (pickling, surface conditioning or coating), and pointing or chamfering. Drawing equipments, such as draw bench, multiple-die continuous and single-die block drawing machines, stepped-cone multiple-die drawing machine. Conical converging drawing die, describing internal profile geometry and functions of different zones of die nib. Drawing of rod and wire: dry drawing and wet drawing. Drawing load and power with friction, and with and without back tension, with and without consideration for work hardening. Frictionless ideal drawing stress without back tension. Maximum reduction of area in a single drawing pass: for non-strain-hardening rod or wire with and without friction and back tension, and for strain-hardening rod or wire with friction and back tension. Redundant deformation, redundant work factor and its effect on drawing stress. Variation of drawing stress with die-cone angle, describing optimum cone angle, dead-zone formation and shaving mode of flow. Tube drawing using fixed plug, floating plug or mobile mandrel. Stress and maximum reduction of area in a single pass for plug drawing and mandrel drawing. Tube sinking and stress for sinking. Stability condition of a floating plug. Application of slip-line field to frictionless plane-strain strip drawing through wedge-shaped dies. Upper-bound solution for frictionless plane-strain strip drawing through wedge-shaped dies, with an example. Problems and solutions.