METHOD TO STRENGTHEN CYLINDRICAL HELICAL COMPRESSION SPRINGS Russian patent published in 2016 - IPC B21F35/00 C21D7/06 

FIELD: machine building.

SUBSTANCE: invention can be used in production of springs of steel. Method includes operations of winding, hardening, tempering, grit blasting and pre-stressing of spring that is followed by cold-hardening of inner surface of springs using hardening device. Latter comprises three deforming rollers arranged relative to each other at an angle of 120°. Force-hardening of spring inner surface is created due to turn of each of deforming rollers on angle, the value of which depends on the preset radial force. Cold-hardening is performed at rotation of the spring at the rate of not more than 10 rpm.

EFFECT: higher fatigue strength and durability of helical springs is taking effect, reduced noise, vibration and drawing force in machining, higher period of resistance of the hardening device is taking effect too.

1 cl, 2 dwg