| 摘要 |
PURPOSE:To efficiently perform manufacture by simple plastic working, by using a punch guide, equipped with swivelable punches, and a press die or the like to perform the manufacture of a sleeve, which has in its internal surface axial directional grooves closing their both end parts in a lengthwise direction, that is, blind grooves, for a hydraulic rotary valve. CONSTITUTION:When a valve sleeve 12, in which plural blind grooves 13 are provided in the internal surface of a cylindrical material 1, is manufactured, an annular punch guide 5 inserts a punch guide rod 10, and the annular punch guide 5, which fits into its longitudinal grooves 6... punches 7, providing protrusive parts 7e of shape corresponding to the blind grooves 13, to be swivelably supported to the inner about supporting points 8, are prepared. And after the cylindrical material 1 is arranged between the punches 7 and a press die 2, upper and bottom molds 4, 3 are pressurized in a direction approaching each other to compress the material 1 and charge an air gap between the punch guide 5 and the material 1 so that the required blind grooves 13 are formed. Subsequently, the punch guide rod 10 is lowered, and the valve sleeve 12 is taken out by swiveling the punches 7 to the inner.
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