| 摘要 |
<p>Easy production of a two-piece wheel is made possible by plastically forming the opposite ends of a cylindrical member of metal into radially double-bend curls of regular shape having a rectangular cross section, thereby directly creating a rim from the cylindrical member. After a drop center section has been formed in the barrel of the cylindrical member (2) of metal , the opposite ends (3) of the cylindrical member (2) are expanded by plastic forming, and the expanded opposite ends (3) are formed into curls (4) of regular shape having a rectangular cross section by regular curl forming (method 1). Alternatively, the expanded end (3) is formed into a curl (4) of circular cross section by curl forming and then the curl (4) is finished into a regular shape having a rectangular cross section by shaping and accuracy promoting (method 2). For the thus-obtained rim (8) having the curls (4) of rectangular cross section at the opposite ends, bead sheet sections (6) are formed with humps (7), each curl (4) is formed with a water drain hole (9), one drop inclined section (10) is formed with a bulb hole (11) for sealing air in the tire, and a disk is attached to the inside of the rim (8), whereupon a two-piece wheel is obtained.</p> |
