Magnetically levitated high-speed spindle for shaping irregular surfaces
First Claim
1. A magnetically levitated high-speed spindle assembly for forming a non-circular surface in a workpiece, said assembly comprising:
- an elongated spindle extending along an ax al axis between a rear end and a shaping end;
a shaping tool extending radially outwardly front said spindle adjacent said shaping end and terminating in a point-like cutting edge;
a first magnetic bearing cluster supporting said spindle proximate said shaping end for magnetically levitated rotation about said axial axis;
a second magnetic bearing cluster spaced from said first magnetic bearing cluster and supporting said spindle remote from said shaping end for magnetically levitated rotation about said axial axis;
a radial bearing controller for independently controlling said first and second magnetic bearing clusters to adjust the radial position of said axial axis during magnetically levitated rotation of said spindle and move said shaping end in a predetermined non-circular orbital path so that said cutting edge will form a correspondingly shaped non-circular hole in the workpiece; and
a cutting edge controller for maintaining a continuous tilt angle between said cutting edge and said orbital path so that said cutting edge remains in continued contact with the workpiece while said shaping end of said spindle traverses said orbital path, wherein said tilt angle comprises an optimal cutting angle defined by the angle between a radius extending from said axial axis to said cutting edge and a tangent line to any point along said orbital path whereby the non-circular hole can be shaped by said cutting edge with improved precision and said assembly can operate at higher rotational speeds and with greater spindle stability.
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Accused Products
Abstract
A magnetically levitated high-speed spindle assembly (20) is provided for forming non-circular holes (22) in workpieces (24) or non-circular surfaces on pins. The non-circular holes (22) can be formed with dimensionally varying axial trajectories at high speeds and with great accuracy. This is accomplished by supporting a rotating spindle (26) between first (58) and second (60) magnetic bearing clusters and independently controlling these bearing clusters (58, 60) to move a shaping tool (32) at the end of the spindle (26) in a predetermined orbital path (B). A multiple input-multiple output control strategy is used to control spindle (26) movements in the X and Y axes. The tilt angle between the cutting edge (34) of the shaping tool (32) and the orbital path (B) is maintained perpendicular under this multiple input-multiple output control of the magnetic bearing clusters (58, 60) to further improve shaping precision and spindle (26) stability during high-speed operations.
52 Citations
36 Claims
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1. A magnetically levitated high-speed spindle assembly for forming a non-circular surface in a workpiece, said assembly comprising:
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an elongated spindle extending along an ax al axis between a rear end and a shaping end;
a shaping tool extending radially outwardly front said spindle adjacent said shaping end and terminating in a point-like cutting edge;a first magnetic bearing cluster supporting said spindle proximate said shaping end for magnetically levitated rotation about said axial axis; a second magnetic bearing cluster spaced from said first magnetic bearing cluster and supporting said spindle remote from said shaping end for magnetically levitated rotation about said axial axis; a radial bearing controller for independently controlling said first and second magnetic bearing clusters to adjust the radial position of said axial axis during magnetically levitated rotation of said spindle and move said shaping end in a predetermined non-circular orbital path so that said cutting edge will form a correspondingly shaped non-circular hole in the workpiece; and
a cutting edge controller for maintaining a continuous tilt angle between said cutting edge and said orbital path so that said cutting edge remains in continued contact with the workpiece while said shaping end of said spindle traverses said orbital path, wherein said tilt angle comprises an optimal cutting angle defined by the angle between a radius extending from said axial axis to said cutting edge and a tangent line to any point along said orbital path whereby the non-circular hole can be shaped by said cutting edge with improved precision and said assembly can operate at higher rotational speeds and with greater spindle stability. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for magnetically levitating a high-speed spindle assembly for forming a non-circular hole in a work piece, said method comprising the steps of:
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forming a cutting edge on a shaping tool;
affixing the shaping tool to one end of a spindle having an axial axis such that the cutting edge is positioned radially outwardly from the axial axis;establishing a magnetic levitation field about a first region of the spindle proximate the shaping tool for rotation about the axial axis; establishing a magnetic levitation field about a second region of the spindle spaced from the first region and remote from the shaping tool; rotating the spindle within the first and second magnetic levitation fields about the axial axis; adjusting the radial position of the axial axis at the first and second regions during rotation of the spindle by varying the first and second magnetic levitation fields to thereby move the cutting edge in a predetermined non-circular orbital path to form the non-circular hole in the workpiece; and maintaining a continuous tilt angle between the cutting edge and the orbital path so that the cutting edge remains in continued contact with the workpiece while traversing the orbital path, wherein the tilt angle comprises an optimal cutting angle defined by the angle between a radius extending from the axial axis to the cutting edge and a tangent line to any point along the non-circular orbital path whereby the non-circular hole can be shaped by the cutting edge with improved precision and the spindle can operate at higher rotational speeds and with greater stability. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification