Geometrical instruments – Gauge – Movable contact probe – per se
Patent
1996-05-23
1998-07-28
Bennett, G. Bradley
Geometrical instruments
Gauge
Movable contact probe, per se
G01B 503
Patent
active
057847959
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a touch probe, with a base unit comprising a casing, a movable arm-set assembly housed in the casing and provided with an arm protruding from the casing and a feeler fixed to the arm end external to the casing, and an adjustment and locking device for locking the base unit to a support and adjusting the position of the feeler by means of rotational displacements about a first geometrical axis, wherein the adjustment and locking device comprises a first and a second reference element with substantially spherical couplings between the base unit and the support for enabling rotational adjustment displacements of the base unit about the first geometrical axis, and two locking elements, coupled to the base unit and to the support, and adjustable along a longitudinal direction, perpendicular to the first geometrical axis.
BACKGROUND ART
Touch probes for checking dimensions of mechanical pieces, or tools, and for performing other similar checkings, comprise adjustment devices for adjusting the position of the probe feeler with respect to pre-set references. For example, in the case of applications on lathes, for checking tools, the references could consist in the longitudinal and transversal axes of the lathe and in the case of applications on machining centres, for checking machined, or to be machined, workpieces, the reference could be the axis of the spindle.
U.S. Pat. No. 4,510,693 discloses a probe, for use in machining centres, comprising an adjustment device with two annular washers having non-parallel surfaces, i.e. beveled shaped, that are mounted between the base unit of the probe and a mechanical adapter with a tapered shank that is clamped in the machine spindle. In order to bring the geometrical axis of the movable arm of the probe in alignment with the axis of the spindle, the two washers can simultaneously rotate with respect to the base unit of the probe and the mechanical adapter and, therefore, reciprocally rotate. Once the required alignment has been reached, the washers are clamped.
Another known adjustment and locking device comprises a central tapered seat formed in an adapter and a ball that is housed in the seat and enables the rotation of the base unit of the probe about the centre of the ball. In this way it is possible to obtain the desired location, and, hence, the base unit of the probe is clamped to the adapter by means of three or four screws.
A further known adjustment and locking device, enables rotational adjustment displacements of the base unit of the probe about a single geometrical axis passing through the centres of two balls placed between an adapter and the base unit. The base unit is locked in the desired location by means of two locking screws.
It is also known to provide a movable arm of a probe made of two portions, and to insert and clamp between the two portions a replaceable pin, with a preferential breakage section, that has the purpose of preventing any serious damage from occurring to the probe in the event of accidental impacts of the feeler. In the case of probes with a substantially cubic shaped feeler, intended for checking tools, it is possible, by unlocking an end of the pin, to perform a rotational adjustment displacement of the portion of the arm carrying the feeler about the geometrical axis of the arm.
The known adjustment devices are subject to some drawbacks, more specifically regarding their considerable layout dimensions, problems that may arise when performing the adjustment and locking operations, the presence of elements of the device in critical areas of the probe and, in the case of the lastly mentioned known adjustment device of the base unit, the possibility of adjusting the base unit about a single geometrical axis.
DISCLOSURE OF INVENTION
Object of the invention is to provide a probe with an adjustment device of the base unit that, in addition to enabling adjustment displacements about at least two perpendicular geometrical axes, has a structure that is favourably compatible with the o
REFERENCES:
patent: 4510693 (1985-04-01), Cusack
patent: 4547971 (1985-10-01), Imazeki
patent: 4763421 (1988-08-01), Feichtinger
patent: 4859817 (1989-08-01), Cassani
patent: 5024003 (1991-06-01), Breyer
patent: 5299361 (1994-04-01), Fiedler
patent: 5323540 (1994-06-01), McMurtry et al.
patent: 5435072 (1995-07-01), Lloyd et al.
Bennett G. Bradley
Marposs S.p.A.
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