Geometrical instruments – Miscellaneous – Light direction
Patent
1982-08-13
1984-11-20
Martin, Jr., William D.
Geometrical instruments
Miscellaneous
Light direction
33 1CC, 33 25R, G01B 503
Patent
active
044830742
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the field of mechanical engineering and, more particularly, it relates to methods for locating a point by its coordinates and to devices for accomplishing such methods.
This invention can be used most advantageously in instrument making, in printing and copying, in measuring equipment and robot making, in hoisting and transport equipment and the like for the orientation of objects on a plane and in space, for example, when making and measuring several holes in a part being machined, in automatic replacement of tools in machines and in transfer and removal of parts from equipment, as well as in automating assembly and auxiliary operations.
DESCRIPTION OF THE PRIOR ART
There are known in the art methods for locating points by coordinates thereof, employed in machine tool manufacture, measuring equipment, in mechanical engineering and instrument making, as well as for the reproduction of data from microfiche, wherein the location of preset points, i.e., the positioning of points on a plane, for example, upon machining or measuring parts, is effected by way of two rectilinear movements in preset orthogonal coordinates (cf., A. N. Rabinovich, Sistema upravleniya avtomaticheskikh mashin - System for Control over Automatic Machines, Tekhnika Publishers, Moscow, pp. 254-261).
Also known in the art is a method for locating a point by its coordinates in a plane and a device for accomplishing the method, wherein positioning is effected with the aid of a carriage driven by an individual drive to move in longitudinal guides of slide rails which, in turn, are movable in transverse guides of a base (cf., U.S. Pat. No. 3,765,755, granted in 1973).
In this latter prior art method and device, a preset point is located with the aid of two interperpendicular rectilinear movements which can only be effected if an intermediate link, such as slide rails, is used in the device. The accuracy of coordinate movements at the time of positioning depends upon the accuracy of the frame of reference used, as well as on the rectilinearity and interperpendicularity of the rectilinear displacement guides of the carriage and slide rails. The guides must provide for strict rectilinearity of movement of movable elements in horizontal and vertical planes. It is only on this condition that the values of coordinate movements at all points in the positioning plane, associated with the moving carriage, will be equal to the values of movements measured by the frames of reference of the device. For increasing the stiffness of the slide rails, their height is increased, this causing a simultaneous increase of error in the vertical plane.
The existing methods for locating a point by positioning are characterized by long drive chains, and by the presence of slack in the carriage movement chains. In order to eliminate the effect of long chains and slack on the accuracy of setting the carriage, the feed of the latter should always be effected in one and the same direction (always approaching the preset point from one side). With a view to saving the time required to move the carriage to extreme positions or to a more remote coordinate, high rates of the carriage movement in both directions have to be developed. It is impractical to maintain high rates of movement until the carriage arrives at the end position since the resulting forces of inertia cause an overtravel of the carriage far beyond the required limit or develop undesirable stresses in the table-and-part feed chain.
This necessitates a deceleration of the carriage travel prior to stopping. Therefore, provision is made for a stepped rate of carriage travel, namely , faster travel over most of the carriage path and slower (for accurate setting) travel over the remaining small portion, required for the carriage to reach the end position. The transition from higher to lower rate of travel is gradual rather than instantaneous, involving two-, three- and even a four-step variation of the travel rate. Different rates of travel upon accelerated
REFERENCES:
U.S.S.R. Academy of Sciences, Collection of papers on Mechanics of Machines, No. 33-36, Nauka Publishers, Moscow, 1972, A. G. Ovakimov, An Analytical Method for Determining the Values of Velocity and Acceleration of Space Mechanisms with Several Degrees of Freedom, (in Russian, pp. 45-62), (presented on May 6, 1968).
Rudzyanskaite Galina J.
Rudzyanskas Juozas P.
Adams Bruce L.
Burns Robert E.
Kaunassky Politekhnichesky Institut Imeni A. Snechkusa
Lobato Emmanuel J.
Martin, Jr. William D.
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