| 摘要 |
PURPOSE:To form a rack having both a shaft of necessary width and a tooth of necessary accuracy, by plastically deforming a pipe having necessary thickness which is made to conform with a tooth to be formed, which is obtained by working a blank material, to a flat shape, and thereafter, executing press-working. CONSTITUTION:By use of a hollow blank material having surplus thickness from standardized goods on the market, a pipe 11 having necessary thickness which is made to conform with a tooth to be formed is obtained by machine work, etc. Into a hole 12 of this pipe 11, a filling material 13 consisting of a regular shape substance such as a hollow or full copper rod, a plastic blank material, etc., or an amorphous substance such as sand or others is charged, and subsequently, a rack tooth forming area of the pipe 11 is plastically deformed to a flat shape by press working. Thereafter, in the direction crossing at right angles to the direction of said plastic deformation, a rack tooth 4 is formed on the upper side part of the pipe 11 by press-working, also is formed to a necessary shape, and a rack shaft 15 is constituted. Also, it is desirable to perform annealing treatment to the blank material or the pipe before forming said rack tooth, because the quality of material becomes uniform, and its mechanical aptitude is elevated. |
