Geometrical instruments – Gauge – Coordinate movable probe or machine
Patent
1989-01-04
1990-08-14
Cuchlinski, Jr., William A.
Geometrical instruments
Gauge
Coordinate movable probe or machine
33 1M, G01B 703
Patent
active
049475576
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to means for angular and linear measurements, and more specifically is concerned with coordinate measuring machines.
STATE OF THE ART
Known in the art are coordinate measuring machines, comprising a base, a portal which is free to displace relative to the base, and a carriage mounted on the portal with the possibility of moving along the latter. The carriage encloses a spindle, which is free to move in a vertical plane, and the spindle carries a system of feeler gauges to feel the item being measured in the process of measurement of its geometric parameters. The portal is driven by a relevant actuating mechanism. The machine also includes a portal displacement measuring system located outside the portal on a side surface of the base. The portal actuating mechanism is arranged close to the measuring system, also outside the portal (cf., prospectus Ferranti, "The Name that Ensures Success", Methodology Systems, SC, 0657/027/3M).
Also known is a coordinate measuring machine, comprising a base with guides for a portal to move along, the portal embracing a measurement zone in which the item is placed for its geometric parameters to be measured. The portal carries a carriage which is free to move along the latter, and the carriage is provided with a spindle fitted with a system of feeler gauges and displacing in a vertical plane. The portal actuating mechanism, e.g. in the form of a lead screw and a nut, interacts with a rigid cross member connecting the lower parts of the portal posts. The machine has a portal displacement measuring system, comprising a measurement scale secured on the base and a measuring head, e.g. in the form of a set photosensors, mounted on the rigid cross member (cf., SU, A, 621,955).
The rigid cross member and the portal form a closed system.
Both prior art coordinate measuring machines do not assure the requisite accuracy and effectiveness of measurements, as the portal displacement measuring system is located at a considerable distance from the measurement zone and its tentative geometric center, and the portal actuating mechanism is comparatively far from the center of gravity of the portal proper. The foregoing factors cause additional measurement errors due to irregular angular oscillations of the portal arising during its motion, and also angular deviation of the portal. Therefore, the latter is displaced at a low rate which, in addition, must be kept constant, particularly when the feeler gauges approach the surface being measured and when the coordinates are read at the measurement points. The above circumstances result in a lower measuring capacity.
SUMMARY OF THE INVENTION
The invention essentially aims at providing a coordinate measuring machine, wherein the measurement error due to angular oscillations and angular deviation of the portal during its displacement would be reduced by altering the location of the portal displacement measuring system.
This object is accomplished by a coordinate measuring machine, comprising a base, a portal displacing along guides located on the base, and embracing the measurement zone, a rigid cross member associated with the portal posts, a portal actuating mechanism interacting with a rigid cross member, and a portal dispacement measuring system having a measurement scale connected with the base, and a measuring head associated with the rigid cross member, according to the invention which, has a post to arrange the portal displacement measuring system, which is mounted on the base equidistant from the portal posts and which carries the measurement scale of the portal displacement measuring system in a manner that the straight line, which is the extension of the longitudinal axis of the measurement scale, crosses the measurement zone.
It is expedient that the rigid cross member be secured in brackets attached to the posts of the portal above the post for arrangement of the portal displacement measuring system.
It is practicable that the portal actuating mechanism be located on the post for arra
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Stenzel Apollo Prospectus, Warner & Swasey/A. Cross & Trecker Co., Sheffi Measurement Division.
Article Ferrant, Metrology Systems (3 pages).
Dzidolikas Kyastutis P.
Gapshis Vladas-Algis A.
Kasparaitis Albinas J.
Kumetaitis Juozas-Stasis
Cuchlinski Jr. William A.
Fulton Christopher W.
Vilnussky Filial Experimentalnogo Nauchno-Issledovatelskogo Inst
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