US 6,546,781 B1 · Method of verifying spindle bearing functionality prior to service

Abstract

A method of verifying spindle bearing functionality prior to service, comprising: assembling a machine-tool spindle having an outer housing rotatably supporting an inner spindle shaft about a spindle axis by use of roller bearing sets, at least one set being compressed along the spindle axis to promote a resilient bearing preload force between the housing and shaft; suspending the housing of said assembly on a non-resonating flexible support, the spindle shaft being essentially isolated from the housing except for the preloaded rolling bearing set; sharply striking the inner spindle shaft along said spindle axis to induce an axially oscillating frequency; measuring the oscillating frequency in the shaft as it is affected by the degree of bearing preload of such at least one bearing set; and comparing the measured induced frequency to a known frequency analysis for the type of spindle assembly which is correlated to varying bearing preloads, the comparison indicating the spindle bearing functionality prior to service.

Claims8

Dependent claims

A method of verifying spindle bearing functionality prior to service, said spindle having been assembled with a housing about a shaft carrying one or more bearing sets axially compressed to exert a preload force between the housing and shaft, comprising:

(a) suspending the housing of said assembly on an essentially non-resonating support allowing said shaft and said housing the freedom to oscillate except as modified by the preloaded bearing force there-between;
(b) sharply striking the end of the shaft to induce its natural vibration frequency as modified by the degree of axial bearing preload stiffness between said housing and shaft;
and
(c) measuring said induced frequency and comparing it to known frequency data for said type of spindle assembly correlated to varying bearing preload stiffnesses, where said known frequency data is gathered by use of a computer implemented analytical dynamic model wherein axial spindle frequency is calculated for varying bearing preloads by the relationship Fa=½πka/Mm/M+m, with M being the outer mass, m being the inner mass, and ka being axial stiffness calculated as a function of bearing preload force and bearing axial deflection.

1 more element

A method of verifying spindle bearing functionality prior to service, comprising:

(a) assembling a machine-tool spindle having an outer housing rotatably supporting an inner spindle shaft about a spindle axis by use of a front bearing set located on said shaft and adjacent to the working end of said shaft, and a rear bearing set located remote from said working end of the shaft, whereby the front bearing set is provided with a bearing preload while the rear bearing set is free to slide within the housing absent any preload there-between;
(b) suspending the housing of said assembly on a non-resonating flexible support set;
(c) striking the inner spindle shaft along said spindle axis to induce an axially oscillating frequency;
(d) measuring said oscillating frequency in said shaft or housing as it is affected by the degree of bearing preload of said at least one bearing set;
and
(e) comparing said measured induced frequency to a known frequency analysis for said type of spindle assembly which is correlated to varying bearing preloads, said comparis on indicating the spindle bearing functionality prior to service.

3 more elements

Dependencies are inferred from the claim text.

Method of verifying spindle bearing functionality prior to service

Life of this patent

Method of verifying spindle bearing functionality prior to service

Life of this patent

Abstract

Claims8