Renishaw Plc

Renishaw Metrology Limited

Peter Hajdukiewicz

David R McMurtry

Peter Kenneth Hellier

Geoffrey McFarland

David Wilson

David Sven Wallace

Graham A Hellen

Clifford W Archer

John C Dabbs

Geoffrey Mcfarland

An apparatus for measuring a surface of a workpiece is described. The apparatus comprises a support, attachable to the moveable arm of a machine, such as a coordinate positioning machine, and rotatable about first and second axes of rotation, the axes driven by first and second motors respectively. The apparatus additionally comprises a surface sensing device for sensing the surface of a workpiece, rotatable about a third axis of rotation. This third axis of rotation is alignable with the first axis of rotation, and when aligned, rotation of the support relative to the surface sensing device is actuatable by the first motor. A method for using an apparatus for measuring a surface of a workpiece is also described.

Surface sensing device

A probecomprises a housingand a membermovable with respect to the housing onto which a stylusmay be mounted such that movement of the stylus results in movement of the member and a primary transducerfor measuring movement of the member relative to the housing. The member may be located in a precisely defined rest positionwith respect to the housing, putting the probe in a mechanical datum position. For a combined transducer probe, this enables the primary transducerto be locked while enabling use of a secondary transducer. The primary transducer outputs can be datumed while in this mechanical datum position. Driveor biasmeans in one axis secure the member in its rest position in all axes.

Analogue probe

A method of calibrating an analogue probe () having a stylus () with a workpiece-contacting tip () or a non-contact probe (). A calibration artefact such as a calibration sphere () is mounted on a coordinate measuring machine (CMM) (). The probe () is mounted on an arm () of the CMM and the probe is moved along a path whilst continually scanning the surface of the calibration artefact such that the probe is exercised throughout its working range. For an analogue probe () having a workpiece-contacting stylus (), the path is such that the deflection of the stylus varies along the path. For a non-contact probe () the path is such that there is variation of the radial distance between the path and the calibration artefact. The probe path may comprise a path parallel to a chord of the calibration sphere or a curved, e.g. a sinusoidal, path.

Calibration of a probe

Apparatus for releasably connecting together two members () comprises two members (), each provided with co-operating elements (A) to define the location of one member with respect to the other member. A damper () is provided on at least one of the members to reduce the impact when the two members are joined together. The two members may comprise two modules of a modular surface sensing probe. The damper may include guide means to assist in guiding the members together.

Kinematic coupling with damper

A system is disclosed enabling the automated exchange of touch probes (34,38) on an articulating probe head 40. The touch probes are mounted to adaptors 32, and are housed in storage ports 20 of a magazine. An adaptor 32 is repeatably located upon the retaining module by the mutual engagement of kinematic support elements 50,52 on the probe head 40 and adaptor 32 respectively. The support elements 50,52 are urged into mutual engagement by a locking mechanism having a spigot 60 on the probe head 40 which engages a cam 62 on the adaptor 32; rotation of the cam 62 locks/unlocks the support elements into mutual engagement. During an exchange operation the cam 62 is rotated by a screwdriver 80 in the storage port. Rotation of the screwdriver 80 is caused by relative movement of the storage port and the support plate 14, which is part of the support structure of the magazine. This relative movement is powered by the motion of the arm of the machine (to which the probe head 40 is mounted) along a path B,C,D,E, during an exchange operation.

Method and apparatus for changing operating modules on a coordinate

A touch probe includes a stylus module (54) and a sensing module (52) to which the stylus module is releasably securable by a magnetic coupling. The sensing module comprises a strain sensitive load cell on which the stylus module is supported, and which senses strain in the stylus on contact with a surface. The stylus module provides for overtravel of the probe; a stylus-supporting member being biased into a kinematic rest position with respect to the casing of the stylus module. The biasing force in the stylus module is chosen with regard to the length and configuration of stylus. This modular system enables automated stylus changing without the need to adjust the biasing force on the stylus-supporting member when different lengths of styli are employed.

Touch probe

A magazine has a plurality of storage ports 400 each of which retains a stylus module 314 for use in measuring workpiece dimensions on a coordinate measuring machine. Each storage port 400 is configured as a pair of jaws provided by docking inserts 414. A permanent magnet 418 is mounted on each docking insert 414. The lower casing of the stylus module 314 is urged against the inwardly facing edges 416 of the docking inserts 414 by the magnetic attraction force due the magnets 418. The stylus module 314 is engaged with a retaining module (on the quill of the machine) by moving the retaining module in a downward sense to engage the stylus module 314; further downward movement disengages the stylus module 314 from the storage port 400, thus enabling engagement of such a stylus module and removal of the module from the storage port in a single continuous movement.

A touch probe for use on a coordinate positioning machine includes a stylus module and a sensing module securable to a movable arm of the positioning machine for releasably supporting the stylus module. The sensing module can include a sensor for detecting contact between the stylus and a surface and/or for detecting displacement of the stylus module relative to the movable arm. The stylus includes a support structure, releasably supported by the stylus module, and a stylus-supporting member for supporting the stylus, with the stylus-supporting member being biased into a rest position with respect to the support structure. The stylus-supporting member is displaceable from the rest position and relative to the support structure when a deflection force acts on the stylus, and returns to the rest position when the deflecting force is removed.

A contact-sensing probe for measuring workpieces includes a body (16) for attachment to a machine and a workpiece contacting stylus (22) carried by a stylus holder (24) which is mounted within the body for movmeent relative thereto from a rest position to a displaced position when the stylus contacts the workpiece. Sensors are provided for sensing workpiece contact by the stylus. The sensors comprise a plurality of strain gauges (46) mounted on pillars (44) connecting two parts (36A,36B) of a support structure which supports the stylus holder on the body. The strain gauges are mounted with their principal axes lying at an angle to the axes of the pillars, and by optimizing the numbers, positions and dimensions of the pillars together with the angles of the strain gauges, high sensitivity can be achieved with minimum risk of false signals due to probe vibration, while at the same time minimizing the variation in pre-travel of the stylus.

Probe for measuring workpieces

A contact-sensing probe for measuring workpieces includes a body (16) for attachment to a machine and a workpiece contacting stylus (22) carried by a stylus holder (24) which is mounted within the body for movement relative thereto from a rest position to a displaced position when the stylus contacts the workpiece. Sensing means are provided for sensing workpiece contact by the stylus. The sensing means comprise a plurality of strain gauges (46) mounted on pillars (44) connecting two parts (36A,36B) of a support structure which supports the stylus holder on the body. The strain gauges are mounted with their principal axes lying at an angle to the axes of the pillars, and by optimizing the numbers, positions and dimensions of the pillars together with the angles of the strain gauges, high sensitivity can be achieved with minimum risk of false signals due to probe vibration, while at the same time minimizing the variation in pre-travel of the stylus.

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Wotton-under-Edge, United Kingdom

Peter Hajdukiewicz