METHOD FOR MANUFACTURING HYDRAULIC DEVICE, AND HYDRAULIC DEVICE MANUFACTURED USING THIS MANUFACTURING METHOD

摘要

A hydraulic pump 1 equipped with: a pair of helical gears 20, 25 each of which has rotary shafts, and the tooth sections of which mesh with each other; an aluminum alloy main body 3 having a hydraulic chamber 4 housing the gears 20, 25 in the meshed state; shaft bearing members 30, 35 rotatably supporting the rotary shafts 21, 22, 26, and 27 of the gears 20, 25; and cover bodies 7, 8 sealing the main body 3 in a liquid-tight manner. The tooth sections of the gears 20, 25 are configured from carbon steel, and have a tooth profile such that an arc section is included in the tooth tip and in the tooth bottom, with a contact line being formed continuously at the meshing part, from one end part to the other end part in the tooth width direction. With this hydraulic pump 1, after the main body 3, the gears 20, 25, the shaft bearing members 30, 35, and the cover bodies 7, 8 are assembled, the inner circumferential surface 3a of the hydraulic chamber 4 of the main body 3 is machined and removed by the gears 20, 25 by means of a running-in operation, and during this running-in operation the machining and removing is carried out by the gears 20, 25, the surfaces of which have been modified such that the surface roughness Rz of the tooth tip is within a range of 5-20 μm.