| 摘要 |
A method and an apparatus for plastic working of a hollow rack, and a hollow rack formed by the same are provided to effectively use thickness of the workpiece along the entire length of a workpiece, obtain a desired performance as a rack bar, and maximize a weight reduction, a cost performance, a resource saving and a vehicle performance. A method for processing a hollow rack by plastic working using a cylindrical workpiece, the method comprises: reducing the weight of the workpiece by subjecting the cylindrical workpiece to plastic working for adjusting thickness of the work piece to desired values at respective positions in the length direction of the workpiece in order to obtain cross-sectional areas of the workpiece corresponding to required functions as the hollow rack at the respective positions in the length direction of the workpiece before forming toothed portions on the workpiece. As a hollow rack formed by performing plastic working of a pipe workpiece used as a steering part of a vehicle, the hollow rack includes a first portion of which a thickness is substantially the same as or slightly increased from a thickness of the pipe workpiece, and a second portion of which a thickness is highly reduced from the thickness of the pipe workpiece and of which a length is elongated, wherein a rack gear is formed on the first portion.
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