CALCULATING PARAMETERS OF HEMISPHERE PART DRAWING IN THE DIE WITH AN ELASTIC ELEMENT

The paper provides a method to obtain hemisphere part in a die where the part surface is formed by the counter die. This is due to the tool design with a steel elastic element placed around the punch. Such process scheme allows for two different processes combined in one tool: drawing and calibration. Drawing sphere-like parts requires calibration since the part has a large area that is not in contact with the punch and die where the part looses stability and starts to buckle. The elastic element made of spring steel and placed around the hard punch calibrates part at the final drawing stage. The paper provides a forming scheme to obtain hemisphere parts with a relative thickness S′ = S/D0·100 % = 1,5÷0,15. Process parameters are evaluated using the engineering method. Geometrical parameters are calculated for the Steel 1060 elastic element for hemisphere part drawing of aluminum alloy 5056 with a thickness of 0,5 to 10 mm. The size of a gap between the punch and elastic element is determined. Maximum stresses occurring in the elastic element when forming are calculated. It is found that the elastic element has no plastic deformation. It is proposed to use the elastic element to produce parts with accurate geometrical dimensions and compensate elastic restitution.

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