Manufacturing method of vehicle wheel and vehicle wheel

A method for manufacturing a vehicle wheel having a cylindrical rim portion for mounting a tire and a disc portion provided with pluralities of spokes and decorative holes, and both the cylindrical rim portion and the disc portion are manufactured by casting or forging, the method comprising

• performing lathe processing of the disc portion, an edge treatment step including removal of burrs at a spoke edge generated by the lathe processing, and a coating step wherein
• the pluralities of spokes comprise a front surface of a spoke that is an outer surface side of the vehicle wheel when the vehicle wheel is mounted on a vehicle, a back surface of the spoke that is an inner surface side of the vehicle wheel when the vehicle wheel is mounted on a vehicle, and a side surface of the spoke that is an opposing surface of the adjacent spokes forming the decorative hole,
• the spoke edge is a corner portion of a boundary between the back surface and the side surface of the spoke, and a ridgeline of the corner portion has a three-dimensional linear shape according to a shape of the spoke,
• during the edge treatment step, with the vehicle wheel on a fixed side, a cutting tool is disposed on a front surface side of the disc portion that does not interfere with the cylindrical rim portion, with a tip end of the cutting tool is inserted into a decorative hole, of the decorative holes, from a side of the front surface of the disc portion, and cutting the spoke edge on the back side of the spoke having the three-dimensional linear shape with a processing blade formed at the tip end of the cutting tool,
• the edge treatment step comprises using the cutting tool as hale type tool for non-rotational processing having the processing blade with an R-shaped or a polygonal C-shaped recessed blade edge protruding from an outer peripheral surface on a side of the tip end of the cutting tool connected to a rod-shaped shank portion of the cutting tool, with a processing machine equipped with four or more moving axes that move each axis by computerized numerical control (CNC) based on three-dimensional shape data along the ridgeline of a three-dimensional shape of the spoke edge, the cutting tool is standing upright against a disc surface while holding a tool rotation direction angle within a range that allows transferring of a shape of the R-shaped or the polygonal C-shaped recessed blade edge of the cutting tool, the blade edge of the processing blade is applied to the spoke edge and continuously moved relative to the spoke edge along the ridgeline of the spoke edge for scraping so that burrs are removed from the spoke edge, and at the same time, a processed surface having a uniform R shape or a polygonal C shape that matches the shape of the blade edge of the cutting tool is continuously formed, and
• the coating step comprises forming a coating film having a film thickness of at least 7 μm or more on the spoke edge after the edge treatment step over an entire length of the spoke edge.