GB777015A - Improved method of forming hollow articles from sheet metal blanks - Google Patents

Abstract

777,015. Making hollow ware, wheel discs; spinning; altering physical structure. LODGE & SHIPLEY CO. Aug. 31, 1955 [Sept. 9, 1954], No. 25067/55. Classes 83 (2) and 83 (4). A method of forming hollow articles which have sides of tapering thickness by displacing metal of a blank comprises supporting a blank on a spindle defined by a curved surface of revolution and while the spindle and the blank are rotating, making a roller having a working tip in contact with the blank to displace metal of the blank and making said working tip follow a path having the same curvature as the curve defining said surface, the path being non- parallel to said surface and displaced therefrom in a direction parallel to the axis of the spindle by a distance substantially equal to the original thickness of the blank to axially displace metal of the blank and thereby form a hollow horn or bow-shaped article whose side is of tapering thickness. In an embodiment for making automobile wheel discs a flat or cupped metal blank 1208 is held against the flat portion 1207 of a dome-shaped spindle 1204 by a tail stock 1209. The blank is rotated and a roller 1220 starting from a point 1221 follows a working curve 1222 which is identical to the surface curve 1206 of the spindle and axially displaces the metal of the blank to conform with the spindle and reorientates the grain structure. Thus the thickness of the formed sides measured parallel to the axis of rotation remains equal to the original thickness of the blank while the thickness measured normal to the spindle surface gradually decreases. The surface cuve of the spindle may be tangential to the flattened end portion (Fig. 3) or intersecting (Figs. 4 and 6) or the curve may be such that a uniformly decreasing taper is imparted to the side of the formed hollow member (Fig. 5). In another embodiment the spindle is provided with a curve 1247 having a radius of curvature which decreases as the curve goes away from the axis 1250 of the spindle (Fig. 7) so that the side thickness of the formed hollow article has a taper gradually increasing towards its mouth. A plurality of rollers may be used and the head of the spindle may be pointed. The thickness of the blank may be non- uniform, e.g. the portion clamped between the spindle head and tail stock may be thicker than the remainder of the blank.