ROTARY FLOW-THROUGH JOINT AND GRINDING APPARATUS

摘要

To provide a rotary flow-through joint that can be equipped with plural flow-through paths without having to increase a shaft diameter and enables high-speed rotation. A rotary flow-through joint is equipped with a shaft 111 that is supported by bearings 113a and 113b such that it may freely rotate and a fixed shaft 112 that is fixed with respect to rotation of this shaft 111, with a coolant flow-through path 131 that enables circulation of a grinding fluid, a drain passage 132 that recovers the grinding fluid and an air-use passage 133 to which air is pressure-fed and supplied from the outside being formed in the fixed shaft 112 in the axial direction thereof 120 degrees apart from each other in the circumferential direction and taking as their axial center a position off-centered from the axial center of the fixed shaft 112, and with a connection insertion portion 134 that is a portion that connects to the shaft 111 being capped by an insertion connection portion formation-use cylindrical body 136, and with part of radial direction cross sections of the coolant flow-through path 131, the drain passage 132 and the air-use passage 133 going over an inner diameter circle of the insertion connection portion formation-use cylindrical body 136 being clipped.