US 5,189,806 AGranted

Method of and apparatus for scanning the surface of a workpiece

AssigneeRenishaw PLC

InventorsDavid R. McMurtry, Brian C. R. Henning

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Abstract

A method of scanning a workpiece surface is disclosed in which a machine carrying a scanning head is moved along a path, preferably at constant velocity, while a surface contacting device is moved by the scanning head to oscillate transversely to the instantaneous path direction to scan an area of the surface. Transducers on the machine, the head, and where necessary the surface contacting device provide data relating to the positions of the surface contacting device to data gathering device under the control of a computer. Apparatus for carrying out the method is also disclosed and includes a scanning head for moving the surface detecting device which may be a stylus or a probe relative to one axis, and preferably orthogonal axes. The head can include a set-up for inertia balancing the head and mass balancing the surface detection device. Also the head may include air bearings on which the stylus or probe are supported for oscillation. Surfaces to be scanned may be flat plates, cones, bores or other surfaces with compound angles.

Claims36

Dependent claims

Apparatus for gathering data relating to a surface of a workpiece, the apparatus including a part of a coordinate positioning machine, and comprising:

a surface detecting device;
support means for mounting the surface detecting device for movement within a three-dimensional reference framework, the support means being supported on the part of the coordinate positioning machine;
means for producing relative movement between the surface detecting device and the surface to bring the surface detecting device into a predetermined spatial relationship with the surface;
means for producing relative movement between the surface detecting device and the surface along a path at constant speed within the reference framework, whereby the surface detecting device passes over the surface;
means for simultaneously producing relative oscillatory movement between the surface detecting device and the surface in a direction transverse to said path such that said surface detecting device moves through a plurality of locations;
and
means for determining at said plurality of locations relative to a datum position;
(a) an instantaneous position of the surface detecting device relative to the support means;
and
(b) an instantaneous position of the part of the coordinate positioning machine, whereby data in respect to the positions of a plurality of points of the work surface relative to said reference framework may be gathered.

7 more elements

A method of gathering data relating to a surface of a workpiece with a surface detecting device, the device being supported on a part of a coordinate positioning machine in a three-dimensional reference framework by a scanning head providing movement of said surface detecting device with 2 degrees of freedom relative to said machine part, the workpiece being support on a table of the machine relative to which said part is movable, the method comprising the steps of:

bringing the surface detecting device into a surface detecting relationship with the surface;
operating the machine to produce relative movement between the scanning head and the workpiece surface at constant speed along a path adjacent the workpiece surface whereby the surface detecting device passes over the workpiece surface;
simultaneously operating the scanning head to produce relative oscillatory movements between the surface detecting device and the workpiece surface in a direction transverse to the instantaneous path and substantially parallel to the local plane of the workpiece surface;
maintaining the surface detecting relationship between the surface detecting device and the workpiece surface at a plurality of locations as the surface detecting device passes over the surface;
and
determining at said locations relative to a datum position:
(a) the instantaneous position of the surface detecting device relative to the machine part, and
(b) the instantaneous position of the machine part relative to the table, and
using the results of said determination to determine the positions relative to said reference framework of a plurality of points on the workpiece surface.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/928,667Filed 17 Aug 1992 · continuation
Priority: WO PCT/GB88/0113519 Dec 1988
Granted: 2 Mar 1993
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01B 21/04
For measuring length, width, or thickness: by measuring coordinates of points
G05B 19/4015
Characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes: going to a…
G05B 2219/37207
Measurements: verify, probe, workpiece
G01B
Measuring length, thickness or similar linear dimensions