Uticaj kontaktnih uslova kod klasičnog i suprotnosmernog izvlačenja

Abstract

In production of big parts of complex geometry out of sheet, such as parts of car-bodies for example, the operation of deep drawing is usualy performed on the first machine (of double action), in one stage. Other machines in line perform additional forming. However, in multi-phase deep drawing, each forming stage has extreme significance from the aspect of realization of limiting relations of forming. In course of that the drawing ratio (basic geometry) and tribological conditions (blank holder pressure, speed, lubrication) have the greatest influence. The second operation of deep drawing can be realized in two basic ways: by classic drawing (round and conical die) and by reversing drawing. The descriptions of these procedures are well-known in theory of forming of thin sheets; because of different forming schemes, the corresponding tribo-models are also different /1/. In reverse drawing die (holder) has bigger surface of contact with piece, during which the tension stress field in piece is widenes. Low carbon thin sheet È0148P5, 0.8 mm thick, has been used in investigation, the drawing ratio in first phase was 1.6, in the second it was 1.66 for axis-symmetrical drawing with flat piece bottom. In course of forming the conditions of proportionality have been satisfied; strain fields have been determined in indentical sections by graphometrical method. In reversing drawing the measurement greed pattern has been deposited on both sides of sheet.