| 摘要 |
PURPOSE:To improve the creep resistance, abrasion resistance, chemical resistance and temperature resistance of a ball seat by forming the ball seat into a molded component of composite plastics which is a mixture of PFA and PTFE. CONSTITUTION:A ball seat 9 is formed as an annular-type substance incorporated into the stage section 8 of a valve body 1 which is located at an edge where one or both of the passage is opened into a valve chamber 2. When a valve ball 7 is in the position 'OPEN', the ball seat 9 connects the passage to a through hole 5 in the valve ball 7, and when the valve ball 7 is in the position 'CLOSED', the ball seat 9 lies between the valve body 1 and the valve ball 7 so as to seal the passage. Said ball seat 9 is formed by the use of a billet, which is previously prepared from a mixture of PTFE and PFA of not less than 10% and not more than 30% by weight ratio through a process where the billet is filled in a mold and then molded by heat and compression. |
