MANUFACTURE OF ROTARY SHAFT FOR TURBINE TYPE FLOWMETER

PURPOSE:To make it possible to stably measure a minute flow rate, by a method wherein recessed parts are formed to both end parts of the rotary shaft of a blade wheel and balls in contact with the bearing part provided in opposed relation to the blade wheel are inserted in the recessed parts and subsequently pressed to the axial direction to fix the rotary shaft. CONSTITUTION:A metal round rod 7 made of brass or stainless steel is cut into a predetermined length and recessed parts 3, 4 having a predetermined depth are formed to both end surfaces 7a, 7b of the round shaft 7 in the axial direction by cutting processing. The peripheral edge parts 3a, 4a of the recessed parts 3, 4 are made thin by applying chamfering processing to the outer peripheries of both end parts and balls 5, 6 each formed of a hard alloy or ceramics so as to have an outer shape dimension slightly smaller than the inner diameter dimension of each of the recessed parts 3, 4 are inserted in the recessed parts 3, 4 so as to partially protrude to be pressed to the axial direction and the peripheral edge parts 3a, 4a are deformed to the inner peripheral direction to fix the round rod 7 to form a rotary shaft 2. This shaft is inserted through the central hole 1b of the hub 1a of a blade wheel 1 to be fixed to said wheel 1. This blade wheel 1 is pivotally supported by the bearings 17a, 17b of the cones 16, 16b, which are fixed to the shafts 15a, 15b in a flow passage 14, through the shaft 2.