| 摘要 |
PURPOSE:To enable both a smaller diameter valve stem and a larger diameter umbrella-shaped head to be manufactured without difficulty by fabricating a poppet valve consisting of the umbrella-shaped head and the valve stem by means of butt-welding joint of the umbrella-shaped head to the valve stem formed in a separate body from the head. CONSTITUTION:In manufacturing a poppet valve, an umbrella-shaped head 9 having a neck 10, and a valve stem 13 with its stem end 14 being padded with stellite or high speed tool steel or being provided with an abrasion resistant surface treatment such as hard chrome plating are prepared, at first. Then, one end of the valve stem 13 is abutted on the abutting surface 12 of the neck 10 to joint them into one body by either friction welding or electric resistance welding. A flash 15 produced by this jointing is removed by machining to complete the manufacture of the poppet valve 16. This constitution enables a larger diameter umbrella-shaped head to be obtained and the neck surface of the umbrella-shaped head to have a larger inclination angle, thus securing a larger passage area. |
