| 摘要 |
PURPOSE:To suppress the release of a ceramic member or generation of gap between metal members by forming the wedge-shaped projection part formed onto the both sides of a ceramic piston-head member into the reverse tapered form spreading outwardly towards the end. CONSTITUTION:A piston head member 23 made of sintered ceramics is fitted from the above onto a recessed part 22 formed from an reverse tapered part 22A in which the top part edge surface of a piston body 21 is outwardly spread towards the end and a cylindrical part 22B parallel to the piston center shaft. Then, a pressing ring 24 is screwed into the screw part 26 at the top recessed part 25 of the piston body 21, and pressed and integrally formed through fitting with the peripheral-edge cut part 23A of the piston head member 23 made of ceramics. Therefore, slide is generated between the standard surface 23B and the reverse tapered surface 23C, for the expansion in the circumferential direction of the piston, and no gap is generated on the standard surface 23B, and only the slide in the direction of the reverse tapered surface 23C is generated, and the pressing force of the pressing ring 24 is made constant.
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