High speed drilling spindle with reciprocating ceramic shaft and double-gripping centrifugal chuck

摘要

A spindle (50) capable of operation at 200,000 revolutions per minute (RPM) with a reciprocating shaft design to minimize the moving mass. The spindle has a ceramic spindle shaft (62) to decrease the moving mass and increase the shaft stiffness for better dynamic stability. The spindle employs a built-in linear motor (110) to provide direct drilling motion to move the shaft along the axis, and a permanent magnet DC brushless motor (80) to rotate the spindle shaft. The linear motor is coupled to the shaft by a combination of an air bearing and a magnetic thrust bearing to reduce the size of the thrust area for better dynamic stability and reduction in stresses of material. A double gripping centrifugal chuck (150) is mounted in the hollow ceramic shaft, and reduces drill bit runout.