High speed drilling spindle with reciprocating ceramic shaft and edoubl-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.
Claims34
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, said rotor shaft fabricated of a ceramic material capable of withstanding centrifugal forces exerted during high rotation rates without significant diametrical growth of the rotor shaft;
- 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.
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, said rotor shaft fabricated of a ceramic material capable of withstanding centrifugal forces exerted during high rotation rates without significant diametrical growth of the rotor shaft;
- 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 ceramic shaft.
A centrifugal chuck for use in a spindle, holding a tool having a tool shank in place during high speed rotation to perform tool operations, the chuck adapted to grip the drill shank during rotation at first and second separated points along the shank to guarantee parallelism of the shank to the axis of rotation, the chuck comprising a uni-body flexure which has two gripping segments, the first gripping segment at a front end of the chuck and the second gripping segment at a back end of the chuck, each gripping segment including a plurality of weights distributed about the chuck axis and which are joined by flexures to form a uni-body construction.
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, said rotor shaft fabricated of a ceramic material capable of withstanding centrifugal forces exerted during high rotation rates without significant diametrical growth of the rotor shaft;
- 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 an axially directed drive force to the rotor shaft to perform drilling movements;
- and
- a thrust bearing for coupling the linear drive system to the rotor shaft, said thrust bearing including an air bearing and magnetically-attracted thrust surfaces.
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, said rotor shaft fabricated of a ceramic material capable of withstanding centrifugal forces exerted during high rotation rates without significant diametrical growth of the rotor shaft;
- 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 chuck for holding a tool mounted in a distal end of said ceramic shaft;
- and
- wherein said shaft comprises a hollow ceramic tube structure, and said chuck is disposed within a sleeve member inserted into said distal end of said ceramic shaft, said sleeve member fabricated of a metal material to relieve localized stresses exerted by the chuck on the ceramic 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, said rotor shaft a hollow tube having a central opening formed therethrough and fabricated of a ceramic material capable of withstanding centrifugal forces exerted during high rotation rates without significant diametrical growth of the rotor shaft;
- 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 including 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 said tube central opening, the magnet having axially extending north and south magnetic poles which are 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.
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, said rotor shaft fabricated of a ceramic material capable of withstanding centrifugal forces exerted during high rotation rates without significant diametrical growth of the rotor shaft;
- 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;
- and
- a linear drive system for imparting an axially directed drive force to the rotor shaft to perform drilling movements, said linear drive system including a linear drive motor, a thrust bearing slider structure and a thrust bearing for coupling the thrust bearing slider structure to the rotor shaft, said linear motor drive comprising an axially movable coil structure having coil windings disposed about the coil structure, a linear motor magnet assembly having core elements fabricated of a magnetic material and one or more permanent magnets, said magnet assembly being stationary with respect to the spindle housing, said coil structure moving axially in response to linear motor drive signals applied to the coil windings.
Dependencies are inferred from the claim text.