Geometrical instruments – Gauge – Movable contact probe – per se
Patent
1990-02-13
1991-07-09
Cuchlinski, Jr., William A.
Geometrical instruments
Gauge
Movable contact probe, per se
33556, 33558, 33561, G01B 728
Patent
active
050293990
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to probes for use in measuring apparatus and in particular relates to dynamic probes for use with measuring machines and machine tools.
It is known from U.S. Pat. No. 4,535,543 for such a probe to take the form of a stack of plates with defined tilting axes in x and y co-ordinate directions. The plate at one end of the stack is connected to the body of the probe, and a probe feeler or stylus is connected to the plate at the opposite end of the stack with its longitudinal axis orthogonal to the plane of the plate to which it is connected. The plates are interconnected in pairs along the tilting axes by leaf springs, and are supported one upon another. Additional springs are provided between the plates of each pair to provide a force in the direction of the longitudinal axis of the stylus to urge the plates into a rest position. The plates may be displaced from the rest position by a tilting or lifting action by a force applied to the free end of the stylus when the stylus contacts a workpiece.
Such probes are inherently liable to potential inaccuracy. For example, if the leaf springs are made too resilient they may bend or twist under the force applied to the stylus in the sense of allowing movement of the stylus transverse to the axis. However, if they are made stiff enough to prevent such bending or twisting they will provide resistance to the force provided by the additional springs, and may under some circumstances prevent the rest position being attained.
The present invention provides an improved probe for use with measuring apparatus. According to the present invention there is provided a probe for use with measuring apparatus, the probe having an axis and comprising:
a plurality of members spaced apart in the direction of said probe axis and including a fixed member, a movable member to which a stylus is connectable and at least one further member,
hinge means connecting the members together in pairs and constraining the members of each pair for relative pivoting movement about a pivot axis which extends in a plane at right angles to said probe axis, the pivot axis of each pair being laterally offset from said probe axis.
support means for each pair of members disposed in the plane of the pivot axis of the pair on the opposite side of said probe axis to the pivot axis, said support means co-operating with the respective hinge means to define an axial rest position for one member of the pair on the other when no external force acts on the probe stylus,
resilient means for urging said one member of the pair into said rest position on the other member,
constraining means for preventing relative transverse movements between the two members of a pair.
The fixed member may be, or may be connected to, a fixed part of the probe e.g. a probe housing.
There may be a plurality of said further members each of which, along with the movable member, is pivotable relative to another of the members. In this way a stylus connected to the movable member may be made both tiltable about a plurality of pivot axes extending in two mutually orthogonal directions at right angles to the probe axis in the same or different planes, and movable in at least one direction along the axis of the probe, when an external force is applied to it, for example when it contacts a workpiece during a measuring operation.
In a preferred form of the invention there are provided a plurality of members in the form of flat plates each supported one upon another and each having at least one side edge, the plates being interconnected in pairs with said side edges in mutually parallel relationship, and each pair being capable of relative pivoting movement about a pivot axis adjacent to said side edges of the pair and perpendicular to the probe axis. The number and arrangement of the plates is such that four pivot axes are provided, two of which extend parallel to a first direction and two of which extend in a second direction perpendicular to the first direction.
Preferably signalling means are provided on the probe, o
REFERENCES:
patent: 4535543 (1985-08-01), Linder
patent: 4553332 (1985-11-01), Golinelli et al.
patent: 4562646 (1986-01-01), Dall'Aglio
patent: 4734994 (1988-04-01), Cusack
patent: 4916825 (1990-04-01), Breyer
patent: 4934065 (1990-06-01), Hajdukiewicz et al.
patent: 4964223 (1990-10-01), Linder et al.
Dynamic Acquisition and Automatic Reduction of Data, p. 288, 6/1978.
Cuchlinski Jr. William A.
Dowling William C.
Renishaw plc
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