William C Mccabe

US Patent:

48152137, Mar 28, 1989

Filed:

Oct 9, 1987

Appl. No.:

7/107014

Inventors:

William J. McCabe - North Kingstown RI
Vitaly I. Pesikov - Providence RI

Assignee:

Brown & Sharpe Manufacturing Co. - No. Kingstown RI

International Classification:

G01C 1506

US Classification:

33125T

Abstract:

In a coordinate measuring machine, apparatus for compensating the sensing means for determining the position of a probe for changes in temperature, where the machine base and the support column for the probe have differing coefficients of thermal expansion. In a preferred embodiment, the apparatus of this invention is used to prevent "zero shift" in the Z-direction for a Z-rail. The compensating apparatus is associated either with the support column or Z-rail. The apparatus offsets the greater expansion of the machine component having the greater coefficient of thermal expansion. Typically, the position sensing means for the Z-rail includes an encoder and a scale. In one embodiment, either the encoder or the scale is secured to a mount which is affixed to the column. One element of the mount which extends upwardly from the support column has a coefficient of thermal expansion which is substantially less than that of the aluminum of which the column is composed. In another embodiment of this invention, the encoder the scale is secured to a lower end of a rod depending downwardly from the support column.

US Patent:

47634200, Aug 16, 1988

Filed:

Oct 6, 1987

Appl. No.:

7/106614

Inventors:

William J. McCabe - North Kingstown RI
Vitaly I. Pesikov - Providence RI

Assignee:

Brown & Sharpe Manufacturing Company - North Kingstown RI

International Classification:

G01B 503
B23B 3500

US Classification:

33503

Abstract:

A base assembly for a machine tool includes a support arrangement between a metal base and a granite worktable which eliminates distortion caused by differential thermal expansion and contraction and which isolates the base from deformation due to the weight of a workpiece. The support arrangement preferably includes three spaced-apart blocks, each with a V-groove track, attached to the bottom of the granite worktable. The axes of the V-groove tracks intersect at a common point. The metal base includes three spherical projections located for engagement in each of the V-groove tracks. The support arrangement permits the granite worktable and the base to expand, contract and distort separately, while providing vertical support and lateral and rotational restraint. Several configurations of tracks and projections are disclosed.