Introduction to Deformation Processes R Wertheim Technion

Introduction to Deformation Processes R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Shaping and Forming - Rough Shapes Rolling Extrusion F Die N Die Angle Vo hf h o Vf Dead Metal Zone Forging F Drawing R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

• Tooling: • Design and geometry • Surface Finish • Mechanical hardness Workpiece Interface Conditions Coulomb’s law Material Flow • Equipment • Accuracy and rigidity • Rate of production Final product • Mechanics of Deformation • Constitutive equation • Thermal condition • Rate R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Material is incompressible, volume is constant e 1+e 2+e 3=0 R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Yielding Criteria: when does material start to plastically deform? Tresca R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Plane -Strain Compression R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

R. Wertheim Technion עירגול Rolling Technion – Israel IWU. Fraunhofer - Germany

R. Wertheim Technion Rolling ערגול Technion – Israel Iscar 2001 IWU. Fraunhofer - Germany

The model reproduces one of Leonardo' s drawings. The two cylinders, by revolving, can level out a sheet of tin about 30 cm wide. R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Hot Rolling and Microstructure Development R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

L w sy sz R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

w Vr V 0 Vf R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

a R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Hot Rolling • Advantages – Stresses lower – Forces smaller – Power requirements less – No work hardening – Large deformations possible – Breaks up the cast structure into preferable forms – Closes porosity • Disadvantages – Higher friction – Rolls need to be cooled – Material handling difficult R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Cold Rolling • Advantages – Deformations of ~ 50 to 80% – Work hardening increases strength – Excellent surface finish – Excellent tolerance on thickness and shape • Disadvantages – High forces – Small reductions give rise to surface stresses and nonuniform stress distributions R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Effect of Roll Forces • The forces result from the resistance of the material to deformation and cause • Roll bending – Non flat material • Cambered sheet • Buckling • Roll flattening – Poor tolerances – Increased forces (larger contact area) R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Roll Force Compensation – Can decrease Roll Forces by: • Reducing friction - Lubricants • Using smaller diameter rolls • Smaller reductions per pass (Residual stresses) • Increasing temperature • front or back tension • camber rolls to compensate • bend rolls back R. Wertheim Technion – Israel IWU. Fraunhofer - Germany

Control of Overall Properties • Tolerance – Thickness • Operator skill/automation – Gauges measure thickness of input and output – Computers control roll gap – Camber • Roll bending/automation – Special segmented tension meters measure "shape" – Computers bend the rolls • Surface finish – Roll finish Bearing reaction forces Applied forces R. Wertheim Technion – Israel IWU. Fraunhofer - Germany