METHOD FOR MANUFACTURING FIXING WASHERS FOR TWO-PIECE FLANGE NUT BY COLD FORGING USING MULTISTAGE FORMING MACHINE AND FORGING PRESS AND FIXING WASHERS FOR TWO-PIECE FLANGE NUT MANUFACTURED BY THE SAME

摘要

PURPOSE: To provide a method for forming fixing washers for two-piece flange nut by cold forging using multistage forming machine and forging press to reduce the number of manufacturing processes and enable mass-production and manufacturing cost reduction through production automation, and fixing washers for two-piece flange nut manufactured by the method. CONSTITUTION: The method for manufacturing fixing washers for two-piece flange nut comprises a step(S10) of cutting a metal work having plasticity to a disk shape suitable for forming; a step(S20) of performing first forging operation on the disk shaped cut work by multistage forming machine and forging press including a plurality of dies and punches; a step(S30) of annealing the first processed article to remove internal stress of first processed article generated by the first forging operation; a step(S40) of lubricating the annealed first processed article to prevent the first processed article from being stuck to the dies and clean the surface of the first processed article; a step(S50) of performing second forging operation on the lubricated first processed article by dies on which a finished product shape is formed; a step(S60) of performing QT treatment operation consisting of quenching and tempering on the second processed article to clear internal stress of second processed article generated by the second forging operation, and harden the surface of the second processed article and softening the inside of the second processed article, thereby improve mechanical properties of the second processed article; and a step(S70) of coating a film for preventing oxidation and corrosion on the second processed article.