Geometrical instruments – Miscellaneous – Light direction
Reexamination Certificate
1998-09-16
2001-01-23
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Miscellaneous
Light direction
C033S032300, C033S443000, C033S444000, C033S503000
Reexamination Certificate
active
06176018
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device for producing an essentially linear motion in a moveable part in a measuring machine where a transmission from a rotary motion to a linear motion takes place.
During the positioning of measuring robots there are very large requirements for low friction between a movable measuring carriage with a measuring bridge, a shaft and a measuring tip, and a fixed part.
Normally, a transmission to the carriage is used which gives a high rigidity in the positioning direction and a running action which is, relatively, as smooth as possible. This is done, for example through a plain shaft drive, e.g. such as is used in the CEJ-Cordimet marketed by C E Johansson, or by a belt drive (re-inforced toothed belt, e.g. CEJ-Saphir) or a cog against a fixed rack, or by a screw and nut.
Other variations of the type using a steel band have been produced, but this has led to very high parallel alignment requirements on the drive shaft and the moving part or carriage, with high manufacturing costs as a consequence.
Bands, belts, plain shafts, screw
uts and racks also easily lead to torques and forces which tend to deviate from the direction of movement being transmitted to the carriage, with subsequent scattering of the measurement result.
BRIEF SUMMARY OF THE INVENTION
One object of the invention is to produce a device for linear movement of a measuring carriage or the like, relative to a physical coordination axis, without the carriage being influenced materially by turning movements or forces in directions other than the direction of movement.
Yet one object of the invention is to minimize so-called random frictions in a measuring robot with a device for linear movement of a measuring carriage.
According to the invention a device for producing an essentially linear movement of a moving part in a measuring machine, where the power transmission takes place from one type of movement (e.g. rotary movement from a servo motor) to the linear movement, is characterized by a transmission element having a high coefficient of elasticity in a longitudinal direction and being flexible in the transverse direction of which one end is fastened to the same mechanical element as its other end, and that the transmission element is given a pre-stress which is greater than the maximum force encountered when accelerating during the transmission operation. The pre-stress can be applied by a force-providing element in the form of a pre-tensioning spring placed between one end of the transmission element and a fixed point, or by the elasticity of the transmission element itself, the force of which the strength is greater than half the maximum acceleration force. An alternative is that a controllable clamping arrangement is controlled during use to tension the force-providing element in the vicinity of one of its ends, whereby the pre-stress then is formed by the elasticity of the transmission element, and that the same end is fastened by means of a spring pre-tension to a fixed point, and that the clamping means is controlled to not clamp on the transmission element when the device is idle.
REFERENCES:
patent: 4651426 (1987-03-01), Band et al.
patent: 4928396 (1990-05-01), Raleigh
patent: 4964221 (1990-10-01), Breyer et al.
patent: 5072522 (1991-12-01), Stott et al.
patent: 5339531 (1994-08-01), Ogiwara
C. E. Johansson AB
Guadalupe Yaritza
Gutierrez Diego
Young & Thompson
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