| 摘要 |
A cold forged valve stem for a three-way valve includes a conical valving portion provided by a conical skirt of work hardened material. The skirt is radially deflectable to insure proper seating and hardened to reduce wear. An oppositely facing conical valve seat is also work hardened. The valve stem is cold formed from cylindrical stock without scrap. The skirt is formed by first upsetting an intermediate head and subsequently further upsetting such head while backward extruding a tubular skirt. Subsequently the tubular skirt is deformed by a conical tool to a conical shape. The opposite end of the valve stem is forward extruded to a polygonal shape to provide a wrenching portion.
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