METHOD OF RESTORING SPRINGS Russian patent published in 2012 - IPC B21F35/00 

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and may be used for spring reconditioning at automotive machinery repair fabrics. Proposed method comprises stretching, heating and holding the spring as-stretched unless cooling-down. The spring is stretched on mandrel with coil pitch exceeding that of finished spring, heated to tempering temperature of 400-420°C and tempered as-stretched. Then, shot-blast cold-hardening is carried out for re-tempering at 230-250°C and pressing by axial load making (10÷300)F₃, where F₃ is spring force at maximum strain.

EFFECT: longer life, expanded performances.