US 6,775,013 B2 · Method and apparatus for measuring displacement or motion error

Abstract

The degree to which a rotating object like a machine tool spindle undesirably wobbles in directions both transverse and parallel to its axis of rotation is measured preferably by providing a laser beam or other beam energy source which directs the beam toward a beam reflecting surface, most advantageously a curved surface, like a spherical or cylindrical surface. The reflecting surface is most advantageously formed by a spherical body mounted for adjustment in a plane perpendicular to the rotating axis involved, so that the center of the curved surface can be positioned as close as possible to the axis involved before error measurements are taken. In such case, the distance the beam traverses between the beam source and the point on the curved surface struck by the beam is a measure of the degree to which the spindle undesirably wobbles in directions both transverse to and parallel to the spindle axis. The beam source and the beam traverse distance measuring means can be a commercially available laser head which by use of focussing means, if needed, returns the reflected beam to the laser head which is designed to produce beam traverse distance measurement data.

Claims25

Dependent claims

Motion error testing apparatus useable for testing the error motion of the inner end of a spindle rotated about a first longitudinally extending axis or the outer end of a spindle rotatable about a different axis while the inner end remains in a fixed orientation, said apparatus including:

a frame having a mounting portion attachable to the outer end of said spindle and an opposite portion having a recess opening onto the end of said opposite portion at the frame;
an energy beam-reflecting unit having an inner mounting portion adjustably mounted within said recess and an outer portion located outside of said recess, said outer portion having a curved beam-reflecting surface presenting beam-reflecting points to be spaced varying distances from a source of beam energy to be directed initially to the nearest point on said curved surface, the beam striking other points of said surface if the spindle should wobble in directions transverse to the beam direction, the beam traverse distance to and from the beam source thus being a measure of the spindle error motion;
and said frame having thereon means for adjusting the position of said beam reflecting unit in said recess so that a point on said beam-reflecting unit can be adjusted.

Apparatus for measuring the motion error of a rotating spindle having an inner end which has a first possible axis of rotation, said apparatus including:

a first energy beam distance traverse measuring system including a first source of beam energy to be directed at a beam-reflecting surface to be attached to the outer end of said spindle and an associated beam traverse distance measuring means for measuring the distance the beam directed by said first source traverses as it goes from the beam directing point to said reflecting surface and then is reflected back to a reflected beam-receiving point which can be the same or different point than said beam directing point;
a frame attachable to the outer end of said spindle and an energy beam-reflecting surface mounted on said frame so that it can receive and reflect beam energy directed thereto from a given beam directing point, said surface having at least one beam receiving area with points spaced varying distances from said beam directing point so that if the beam is directed toward the nearest point of said surface assuming said spindle ideally does not wobble in any direction transverse to said possible axis of rotation of said spindle said beam will strike the nearest point thereof and if said spindle wobbles in said transverse direction the distances between the beam source and the beam reflecting point on said surface will increase in proportion to the amount the spindle has moved transversely from the ideal axis position, said measuring means providing a measure of the varying distance said beam traverses as said spindle carrying the reflecting surface rotates about said axis.

A method of measuring the error motion of a rotating spindle comprising the steps of:

attaching to the outer end of a spindle having at least one axis of rotation an energy beam-reflecting surface having a first surface area facing in a first direction transverse to said axis of rotation and which has points located progressively varying distances from a source of beam energy to be directed thereat in said first direction;
directing a first source of said beam energy in said first direction;
and
imparting rotation to said spindle and providing a measure of the variation of the distance between said first beam source and said reflecting surface area over at least one rotation of said spindle, any wobbling of said spindle in a direction transverse to said first direction causing said beam to strike points of said reflecting area of varying distance from said first source in proportion to the degree to which the spindle wobbles in said transverse direction.

1 more element

Dependencies are inferred from the claim text.

Method and apparatus for measuring displacement or motion error

Life of this patent

Method and apparatus for measuring displacement or motion error

Life of this patent

Abstract

Claims25