Brake drum for wet-type band brake drum and method for manufacturing the same

摘要

A brake drum for a wet-type band brake has a large number of grooves substantially along the circumferential direction on a slide contact surface with the brake band. Each adjacent grooves are smoothly linked to each other through a substantially convex arcuate cross sectional-portion. A method for manufacturing the brake drum comprises the steps of forming the grooves by cutting work, and forming a border portion between each adjacent grooves in a substantially convex arcuate cross section by plastic working using a forming roller.