| 摘要 |
1418659 Forming ball ends on metal strings C B S INC 29 Dec 1972 59987/72 Heading D1T A metal string end is balled by placing it in a metal element, compressing the element laterally to introduce at least one fold into at least one wall of the element, and compressing the element longitudinally until the metal on opposing sides of the or each fold plane is compacted together to form a ball end. A musical instrument string 41, Fig. 3, is provided with a ball end by placing it within metal ferrule 23 within split-die cavity 26, and deforming the ferrule with plungers 14, 17 to bend the string end into an S-shape. The ferrule is then compressed by ram 31, Fig. 4, the ferrule teeth 48 (Fig. 3) being turned by cavity surface 29 to grip and centralise the string, the metal then cold flowing about the string and while it retains its S-shape. Fold surfaces 45, 46 become radial abutments 51, 52 in the resulting ball end, Fig. 5a. Due to the cavity and ram shape, the ball has a convex free end, a cylindrical surface coaxial with string portion P, and a hemispherical surface leading to neck 49. String portion P lies between parallel planes L 1 , L 2 tangential to the string bends. The string may comprise a core wire wrapped with a wire of less tensile strength. The plungers and ram are moved hydraulically. |
