| 摘要 |
PURPOSE:To form a wheel rim for vehicles having unequal wall thicknesses with less number of working steps by interposing a thick-walled annular blank material between a freely rotatable die and a freely rotatable and movable rolling reduction roll, and subjecting the same to intermediate forming then pressing the same between a die of a finish forming die and a rolling reduction roll which are respectively of the same construction. CONSTITUTION:A thich-walled annular blank material W1 which is an expanded material of Al or the like and is of a diameter smaller than that of the final product is interposed between a freely rotatable die and a freely rotatable and movable rolling reduction roll, and is pressed by these, whereby an intermediate formed material W2 which is smaller in diameter than that of the product and of which both end parts in the axial direction are thicker than the central part is preformed. Next, the material W2 is interposed between a die 1 of which the inside circumferential size and shape conform to the outside diameter and shape of the final product rim and which is supported freely rotatably and a rolling reduction roll which is smaller in diameter than that of the material W2, of which the outside diameter shape conforms to the inside shape of the final product rim and which is supported rotatably and freely movably in the radial direction. Next, the material W3 is pressed by said die 1 and roll 2, whereby it is rolled to the size and shape of the final product rim and the unequally walled wheel rim W3 which is thick walled in respective corner parts A,B,C,D, is formed. |
