METHOD OF NUT PRODUCTION Russian patent published in 2014 - IPC B21K1/68 

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and van be used for making hexagonal nuts of 8^th or 9^th strength class. Nut features hardness, at least, 170 HV and can be used at strains caused by stress higher than 800 N/mm². For making the nut billet steel rounds are used containing 0.15-0.35% of carbon and 0.5-1.6% of manganese, iron and unavoidable impurities making the rest. Carbon equivalent (C_eq) is defined by the formula: C_eq = C+Mn/20 where: C, Mn are weight ratio of carbon and manganese making at least 0.23 wt %. Rolled stock is subjected to abortive quenching with self-tempering at making at metallurgical conversion. Rolled stock features yield point is σ_y≥360 N/mm², point of maximum load σ_l≥480 N/mm², elongation δ₅≥28%, and contraction ψ≥60%. Rolled stock is subjected to cold plastic deformation at reduction of 5-20% to make wire to be cut to work pieces. Workpiece is successively deformed by cold die forging at six process passes at hexagon turret die with or with turnover through 180 degrees. Note here that outer hexagon and bore to be threaded are made at axial zone. Nut thread is either cut or rolled.

EFFECT: lower metal input and forging force, higher durability of tooling.

8 cl, 3 dwg, 1 tbl, 1 ex