Spindle protective structure in spindle-through coolant feeder

摘要

A spindle protective structure in a spindle-through coolant feeder capable of preventing coolant form invading a spindle and a spindle motor for an excessive overflow of coolant. Coolant is supplied into a through hole formed axially in the spindle or a shaft connected to the spindle through a stationary member and a rotary member of a rotary joint supported by a housing. A seal member having elasticity is provided on a circumferential surface of the spindle or the shaft. Coolant which leaks through the seal member is splashed by a fringer provided in the housing. When a large amount of coolant is overflowed in the housing, a pressure of the coolant in a first chamber of the housing increases to press a lip of the seal member towards the circumferential surface of the spindle or the shaft to prevent leakage of coolant into a second chamber of the housing. Thus, the excessive overflow of coolant is prevented from invading the spindle and the spindle motor for a long enough time for an operator to take countermeasure for the leakage of coolant.