Spindle assembly of machine tool, and machine tool

A machine tool comprising:

• a machining head comprising:
• a rotating body;
• a plurality of bearings including a first bearing;
• a housing that supports the rotating body to be rotatable about a first axis via the plurality of bearings;
• and
• a first rotational driver configured to rotate the rotating body about the first axis;
• a lubricator configured to supply the first bearing with a mixed fluid containing oil and air through a supply flow channel;
• a collector configured to collect, via a collecting flow channel, at least part of the oil that has passed through the first bearing;
• a workpiece holder configured to hold the workpiece;
• a mover configured to move the machining head relative to the workpiece holder;
• and
• control circuitry configured to control at least the first rotational driver and the mover,
• wherein the first bearing comprises
• an inner ring,
• an outer ring surrounding the inner ring, and
• rolling elements provided between the inner ring and the outer ring, the inner ring and the outer ring being relatively rotatable around the first axis via the rolling elements,
• wherein the rotating body comprises
• a tip end portion to hold a tool,
• a rear end portion opposite to the tip end portion along the first axis,
• a first portion that supports the inner ring of the first bearing, the first portion having a first outer circumferential surface,
• a second portion having a second outer circumferential surface with a diameter smaller than a diameter of the first outer circumferential surface, the second portion being disposed further in the first direction than the first portion, the first direction being a direction from the rear end portion toward the tip end portion, and
• a stepped surface that connects the first outer circumferential surface with the second outer circumferential surface,
• wherein the housing comprises
• a third portion that supports the outer ring of the first bearing, and
• a fourth portion that defines an annular receiving space configured to receive the oil from a first gap between the first portion and the third portion, and
• wherein the fourth portion comprises
• an opening portion via which the oil flows from the annular receiving space to the collecting flow channel, and
• an annular projection that faces both the stepped surface and the annular receiving space and that projects in a direction away from the first axis.