Bearings – Linear bearing – Plain bearings
Reexamination Certificate
1999-10-13
2001-09-18
Hannon, Thomas R. (Department: 3682)
Bearings
Linear bearing
Plain bearings
C384S037000, C384S042000
Reexamination Certificate
active
06290395
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to linear slide mechanisms, and relates more particularly to a linear slide assembly having a carriage with a laterally-compliant way mounting that incorporates flexures and lateral stops.
2. Description of the Relevant Art
Linear positioners are used to move and position objects along a linear path. Typically, a linear positioner has (1) a linear slide mechanism that guides a carriage along the linear path and (2) a source of motive power, such as a lead screw mechanism, to move the carriage. A linear slide mechanism typically has a stationary base, the moveable carriage, and slides or guide rails or ways to guide the carriage.
Design considerations for a linear slide mechanism may include factors such as positioning accuracy, load carrying capacity, and wear. It is desirable for a slide mechanism to require a low but consistent force for moving the carriage along the linear path, yet be relatively stiff or resistant to forces in any direction other than along the linear path.
One type of linear slide mechanism has two parallel, stationary ways mounted on a base, and two corresponding parallel ways mounted on a carriage. The contacting surfaces of the mating ways may be coated with a low-friction bearing strip material made from a polymer such as Turcite, which may be impregnated with bronze or brass particles. Turcite-lined ways are available from SKF Gmbh of Schweinfurt, Germany. A problem with using a solid material as a linear bearing is that some means must be provided to preload the ways to minimize lateral compliance and to compensate for wear. Also, some means must be provided to compensate for ways being not quite precisely parallel so that the carriage can run freely and precisely despite minor misalignments.
SUMMARY OF THE INVENTION
In accordance with the illustrated preferred embodiment, the present invention is a linear slide assembly having a carriage with a laterally-compliant way mounting. The linear slide assembly comprises a pair of parallel stationary ways and a carriage. A pair of parallel traveling ways are mounted to the carriage. One traveling way is mounted to the carriage by a fixed mounting and the other is mounted to the carriage by a laterally-compliant mounting. The laterally-compliant mounting includes a compliant mounting bar and flexures that permit movement in a direction transverse (lateral) to the direction of carriage movement. The compliant mounting further includes a stop that limits the transverse movement of the compliant traveling way. Preferably, the ways have a low friction bearing material, such as Turcite B or Delrin AF, between the stationary and traveling portions.
The linear slide assembly of the present invention is used in a linear positioning system having a motor-driven helical lead screw that engages a nut mounted to the carriage. Rotation of the lead screw moves the carriage linearly along the stationary ways. The linear positioner may be used in applications such as, for example, positioning test heads for testing or certifying disk drive media. More generally, the linear slide assembly of the present invention may be used in a wide variety of positioning systems, including open loop and closed loop, and may be operated in dirty environments, or while submerged in oil. The linear slide assembly may be used in linear motors and may be powered by various motors, such as stepper motors or servo motors.
The laterally-compliant way mounting on the carriage accommodates slight misalignment of the ways, yet provides a very stable and stiff platform for coupling the carriage to the ways. The laterally-compliant way mounting acts like a spring up to the point where the stop is engaged, and then acts like a solid mounting with no lateral compliance.
The features and advantages described in the specification are not all inclusive, and particularly, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification and claims hereof. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. For example, it is assumed that the direction of carriage movement is horizontal and that an upper mounting surface of the carriage is also horizontal, and references below to “vertical” or “horizontal” are based on that assumed orientation. However, the present invention need not be oriented horizontally; the assumed orientation is adopted solely for ease of description and is not intended to be limiting. As another example, the terms “way” and “ways” are used herein to describe the structures used to guide the linear movement of the positioner. Other, comparable terms for the guiding structures are: guide, rail, slide, guide rail, slide rail, and rail guide, and the like. The terms “way” and “ways” are intended to encompass all of the other comparable terms without limitation. Accordingly, resort to the claims is necessary to determine the inventive subject matter.
REFERENCES:
patent: 4390216 (1983-06-01), Mueller et al.
patent: 4637738 (1987-01-01), Barkley
patent: 4773769 (1988-09-01), Church
patent: 4941758 (1990-07-01), Osawa
patent: 5064318 (1991-11-01), Cirillo
patent: 5176454 (1993-01-01), Schlereth
patent: 5247891 (1993-09-01), Morita
patent: 6019514 (2000-02-01), Feinstein
Gray Cary Ware & Freidenrich L.L.P.
Hannon Thomas R.
Techmetric Inc.
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