During operation the wheels of railroad rolling stock (such as locomotives and railroad cars) become worn. This wear often increases the risk of train derailment and, additionally, may accelerate wheel wear or otherwise adversely affect the running characteristics of the wheels.
The wheels of railroad rolling stock may, with wear, develop flat areas on their circumferences. Such wear often causes a bumpy or vibratory rotation of the worn wheel against the rail. Additionally, worn wheels may cause derailment of the railway vehicle.
The contours of the wheel tires of railway wheelsets are the subject of international standardization. During operation, the peripheral surfaces of such wheel tires and/or wheel rims undergo severe wear, especially from the tips of the flanges to the outside wheel-tire surfaces or the wheel-rim surfaces. Thus, especially with high-speed trains, the wheel tires and wheel rims should be reshaped to reduce or minimize the bearing or bogie loads of the rail vehicles and the concomitant wear of rail surfaces.
Railway wheelsets may be trued with stock removal carried out, e.g., by a turning or milling process. Thus, e.g., peripheral milling machines, which are adapted to remove metal by feeding a workpiece through the periphery of a rotating circular cutter (such as a milling cutter), are often used.
Additionally, cutter heads, or shell end-milling cutters which duplicate the wheel shape desired in part or whole, are often used as tools for wheel shaping. By way of illustration, U.S. Pat. No. 3,540,103 of Oliver Saari (the disclosure of which is hereby incorporated by reference into this specification) discloses a milling cutter for truing wheels of railroad cars and locomotives. The milling cutter of this patent comprises a body of substantially circular cross-section and a plurality of center buttons rigidly associated with the surface of the body, the buttons being arranged in a plurality of spaced ranks to establish a helical array of buttons about the surface of the body, wherein the buttons are spaced within such ranks that buttons which are adjacent in the helical array lie in non-adjacent ranks. A similar cutter is disclosed in U.S. Pat. No. 2,645,003, the disclosure of which is also hereby incorporated by reference into this specification.
It is an object of this invention to provide a shaping tool which is adapted to duplicate at least a portion of a wheel shape.
It is another object of this invention to provide a process for shaping the contour of a wheel which provides good efficiency and optimum chip breaking capacity while simultaneously maximizing tool life.
It is yet another object of this invention to provide a process for shaping the contour of a wheel which provides high surface finish of the wheel with substantially no shape distortion.