High speed drilling spindle with reciprocating shaft and double-gripping centrifugal chuck
AssigneeElectro Scientific Industries, Inc.
InventorWojciech B. Kosmowski
Life of this patent
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Abstract
A spindle 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 to decrease the moving mass and increase the shaft stiffness for better dynamic stability. The spindle employs a built-in linear motor to provide direct drilling motion to move the shaft along the axis, and a permanent magnet DC brushless motor 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 is mounted in the hollow ceramic shaft, and reduces drill bit runout.
Claims25
A high speed drilling spindle for a drilling system, comprising:
- a spindle body;
- a rotatable rotor shaft supported within the spindle body for high speed rotation about a rotor axis;
- a rotary air bearing for supporting the rotor shaft for high speed rotation with low frictional drag within the spindle body, the rotary air bearing including an air bearing structure disposed about portions of the rotor shaft, wherein small bearing air gaps are defined between the air bearing and the rotor shaft;
- a rotary drive system for imparting rotational drive forces to the rotor shaft so as to rotate the shaft on the rotary bearing at high speeds of at least 200,000 revolutions per minute;
- and
- wherein said rotor shaft capable of withstanding centrifugal forces exerted during high rotation rates of 200,000 revolutions per minute without diametrical growth of the rotor shaft sufficient to close said air bearing gaps and cause seizure of the shaft in the rotary air bearing.
A high speed drilling spindle comprising:
- a spindle body;
- a rotatable rotor shaft supported within the spindle body for high speed rotation about a rotor axis;
- a rotary bearing for supporting the rotor shaft for high speed rotation with low frictional drag within the spindle body;
- a rotary drive system for imparting rotational drive forces to the rotor shaft so as to rotate the shaft on the rotary bearing at high speeds;
- a linear drive system for imparting axially directed drive forces to the rotor shaft to reciprocate the rotor shaft along a shaft axis, the linear drive system including a linear motor and a magnetically attracted and air-bearing-repelled thrust bearing for coupling the linear drive system to the rotor shaft, said thrust bearing including an air bearing;
- and
- a centrifugal chuck for holding a tool mounted in a distal end of the shaft.
A high speed drilling spindle for a drilling system, comprising:
- a spindle body;
- a rotatable rotor shaft supported within the spindle body for high speed rotation about a rotor axis;
- a rotary bearing for supporting the rotor shaft for high speed rotation with low frictional drag within the spindle body;
- and
- a rotary drive system for imparting rotational drive forces to the rotor shaft so as to rotate the shaft on the rotary bearing at high speeds, said rotary drive system includes a DC brushless permanent magnet motor, said motor comprising a stator assembly including a plurality of stator windings, said stator assembly mounted within said spindle body, and a permanent magnet mounted within an opening formed in said rotor shaft, the magnet acted upon by magnetic fields established as a result of excitation signals applied to the stator windings to impart rotational forces to the rotor shaft.
Dependencies are inferred from the claim text.