Patent ID: 8402656

Claim:
A method of producing a diaphragm damper having a high pressure chamber which includes two diaphragms welded together at their flanges and charged inside with a high pressure gas, the method comprising the steps of: forming the diaphragms from metal sheets and using a pair of jigs to face each other in a pressure vessel to hold the diaphragms; sealing and evacuating the pressure vessel, then charging and pressurizing a mixed gas including helium in the pressure vessel, then bringing the pair of jigs relatively near each other to bring the flanges of the pair of diaphragms into close contact; and welding outer peripheral edges of the flanges of the diaphragms along an entire circumference of the diaphragms in the pressure vessel, wherein each diaphragm comprises: a disk shaped flexible part; a positioning part formed in a continuous manner from an outer periphery of the disk shaped flexible part and bent to have an arc-shaped cross-section, wherein the positioning part is configured to form a half space for a high pressure chamber in combination with the disk shaped flexible part; forming the flange to be integral with an outer periphery of the positioning part to define a flat ring shape, the mixed gas includes 15 to 25 vol % of helium gas, and when welding the entire circumference of the flanges, inside the pressure vessel, the pressure of the mixed gas is, by gauge pressure, a pressure of 0.1 to 0.5 MPa, the jigs are simultaneously rotated in the pressure vessel to rotate the pair of diaphragms, and a laser beam is directed at the outer peripheral edges of the flanges of the diaphragms from a direction substantially perpendicular to a rotation axis of the diaphragms, wherein the flanges are welded along their entire circumferences in the pressure vessel, each jig is formed with a positioning recess for holding the diaphragm so as to be positioned by the positioning part and housing the disk shaped flexible part and the positioning part, the outer peripheral edges of the flanges of the diaphragms project out from outer peripheries of the jigs when the entire circumference of the flanges of the diaphragms are welded by the laser beam.