Geometrical instruments – Distance measuring – Opposed contacts
Reexamination Certificate
1999-07-14
2001-06-19
Ackun, Jr., Jacob K. (Department: 2859)
Geometrical instruments
Distance measuring
Opposed contacts
C033S784000
Reexamination Certificate
active
06247244
ABSTRACT:
This invention concerns a device for longitudinal measurement, for example a micrometer, and more particularly a micrometer comprising a threaded screw engaged in a fixed sleeve and having means of adjustment of the play between the sleeve and the screw. The present invention also relates to an electronic micrometer comprising a fixed transducer facing the scale.
U.S. Pat. No. 5,433,016 describes a conventional electronic micrometer. This micrometer comprises a micrometric screw engaged in a threaded sleeve integral with the anvil of the micrometer. By turning the micrometric screw by means of the thimble of the micrometer, the screw is thus displaced longitudinally with respect to the anvil. A system of capacitive measurement measures the number of rotations made by the micrometric screw and thus allows the distance between the free end of the latter and the anvil to be determined.
In order to measure distances with optimal precision and resolution, on the order of one micron, it is necessary to reduce as much as possible the mechanical play between the micrometric screw and the fixed sleeve. With this aim, a portion of the sleeve is tapered and is provided with a plurality of longitudinal slits. In order to adjust the play, a nut is screwed onto this portion of the sleeve. By tightening the nut more, its point of contact with the tapered portion of the sleeve is changed, which causes a deformation of the latter at the level of the slits and a reduction in the diameter of the sleeve, in such a way as to compensate the play with the screw.
By tightening the external nut, however, the inner threading of the sleeve the level of the slits is also deformed. Moreover, the deformations of the sleeve are concentrated in the region of the slits so that the compressed sleeve is no longer perfectly circular and a smooth displacement of the micrometric screw is not guaranteed. It is therefore necessary to bore and tap the sleeve simultaneously with the external nut slightly with restraint. This adjustment operation must be done manually, during assembly of the micrometer, by means of a specially manufactured boring and tapping tool. The result is not always guaranteed, and it is sometimes necessary to repeat the operation several time Furthermore the machining of the slits and the tapping produce burrs which are difficult to eliminate completely and which are liable to disturb the functioning of the micrometer.
The U.S. Pat. No. 3,877,149 describes a micrometer in which the play between the sleeve and the micrometric screw is adjusted by means of a pin pressed at a point on the periphery of the sleeve. The pressure between the sleeve and the micrometric screw is adjusted only locally at the point of contact between the pin and the sleeve so that the deformation of the sleeve is very great in this device.
The British patent GB 1 361 991 describes a micrometer employing a threaded piece of synthetic material deformable by compression to compensate the play with the micrometric screw. A threaded piece of synthetic material, however, is difficult to machine with great precision and moreover liable to wear out quickly. This construction is thus unsuitable for micrometers of high range.
One object of the invention is thus to propose a device for longitudinal measurement, for example a micrometer, which enables the drawbacks of the prior art devices to be overcome or reduced. In particular, an object of the present invention is to propose a micrometer in which no machining of material is necessary to adjust the play between the sleeve and the micrometric screw during assembly.
These objects are achieved, according to the invention, by means of a device for longitudinal measurement, comprising
a sleeve having an at least partially threaded inner surface and an at least partially threaded outer surface, said outer surface comprising at least one deformable tapered portion,
a screw engaged in said sleeve and able to be set in rotation with respect to said sleeve in such a way as to displace itself along the longitudinal measuring axis (x) of the device,
a nut engaged on the threaded portion of said sleeve and able to be put in contact with said tapered portion in such a way as to deform it in order to adjust the play between said screw and said sleeve, wherein said tapered portion is devoid of longitudinal slits and its deformability is provided by an outer diameter variable along its periphery.
In particular these objects are achieved by means of a device for longitudinal measurement in which the sleeve is devoid of longitudinal slits, in particular in its tapered portion. The deformability of the sleeve results from an external diameter variable along its periphery, preferably by means of a plurality of flat parts around its periphery.
This construction brings with it the unexpected advantage of permitting modifications in the diameter of the sleeve without damaging the inner threading and without changing the circular form of the sleeve. The invention thus makes it possible to compensate for the play in the micrometer without detracting from precise functioning of the micrometric screw as in the devices of prior art.
REFERENCES:
patent: 1098694 (1914-02-01), Starrett
patent: 2212910 (1940-08-01), Witchger
patent: 2325351 (1943-01-01), Willis
patent: 2467499 (1949-04-01), Sachtleber
patent: 2555243 (1951-05-01), Parker
patent: 2563061 (1951-08-01), Parker
patent: 2871571 (1959-02-01), Metevia
patent: 3131482 (1964-05-01), Watelet et al.
patent: 3667127 (1972-06-01), Tsugami
patent: 3686766 (1972-08-01), Matumoto
patent: 3758956 (1973-09-01), Nakata
patent: 3835544 (1974-09-01), Schneider
patent: 3877149 (1975-04-01), Masuda
patent: 4255861 (1981-03-01), Nakata et al.
patent: 4268969 (1981-05-01), Koenuma
patent: 4561185 (1985-12-01), Sakata et al.
patent: 5433016 (1995-07-01), Tachikake et al.
patent: 5495677 (1996-03-01), Tachikake et al.
patent: 5829155 (1998-11-01), Takahashi et al.
patent: 2657651 (1977-06-01), None
patent: 0791801 (1997-08-01), None
patent: 2356120 (1978-01-01), None
patent: 0538184 (1993-04-01), None
patent: 1230417 (1971-05-01), None
patent: 1361991 (1974-07-01), None
Patent Abstracts of Japan, vol. 14, No. 430, Sep. 14, 1990 and JP 02 167425A (Mutoh Ind Ltd), Jun. 27, 1990.
Bovey Arthur
Paudex Michel
Zanier Adriano
Ackun Jr. Jacob K.
Brown & Sharpe Tesa SA
Francis F.
Jacobson & Holman PLLC
LandOfFree
Device for longitudinal measurement does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for longitudinal measurement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for longitudinal measurement will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2485194