Renishaw Plc

Renishaw Metrology Limited

Peter Kenneth Hellier

David R McMurtry

Peter Hajdukiewicz

David Wilson

Michael John Wooldridge

Jonathan Paul Fuge

Peter G Lloyd

Graham A Hellen

Jamie John Buckingham

Christopher J Daniel

Robert Charles D'Olier Umfreville

John C Dabbs

Tim Prestidge

Graham Richard Ferguson

Andrew J Harding

John Anthony Styles

David Roberts Mcmurtry

Robert B Morrison

Jamie Buckingham

Christopher James Daniel

David Roberts Mcmurty

A measurement probe, for a co-ordinate positioning apparatus such as a machine tool, is described that includes a stylus holder that is deflectably mounted to a probe housing. One or more sensors are provided for sensing deflection of the stylus holder relative to the probe housing. A processor is included for producing a trigger signal when the deflection sensed by the one or more sensors meets a trigger condition, such as a deflection threshold. The probe also includes an accelerometer for measuring acceleration of the measurement probe. The trigger condition applied by the processor is alterable, during use, in response to the acceleration measured by the accelerometer. In this manner, false triggering can be suppressed.

Touch trigger measurement probe

A measurement probe, such as a touch trigger measurement probe, is described that comprises a measurement portion for measuring an object and a data transfer portion for receiving data from and/or transmitting data to an associated unit. The measurement device also comprises an authentication module for verifying the authenticity of the associated unit. The authentication module may include a processor for running a one-way hash algorithm. Authenticity may be established using a challenge and response authentication process.

Measurement probe systems for co-ordinate positioning apparatus

A 'go, no-go' method is described for determining whether the dimensions of an object, such as a workpiece, conform to tolerance. The method uses a measurement probe, such as a touch trigger, analogue, or non-contact probe, mounted on a measuring apparatus such as a coordinate measuring machine, machine tool, or a lathe. The method comprises the step of driving the measurement probe around a path relative to the object, said path being based on a tolerance of the object. The path relative to the object may include at least a first path based on the maximum tolerance of the object and a second path based on the minimum tolerance of the object. The method additionally comprises the steps of monitoring any probe measurement data acquired by the measurement probe as the probe is driven around the path, and indicating if the dimensions of the object do not conform to tolerance only if there is a change in state of the probe measurement data that is acquired as the measurement probe is driven around the path.

Method for measuring an object

A dimensional measurement probe () is mounted in a machine tool (), which reorientates the probe about at least one axis A. Strain gauges () sense when a stylus () of the probe contacts a workpiece (), to produce a trigger signal. False trigger signals may be produced when the probe is reorientated. To overcome this, the reorientation is detected by monitoring changes in the fluctuations of the strain gauge outputs, caused by vibrations of the stylus.

Method of determining measurement probe orientation

A probe for position determining apparatus has a probe body () and a workpiece-contacting stylus (). A strain sensitive structure connects the probe body and the stylus, and includes bendable members (). The bendable members have an asymmetric cross-section, e.g. 'T' shaped. A strain gauge () is mounted to the stem of the 'T' to detect the bending caused when the stylus contacts a workpiece. This enables the strain sensitive structure to be both robust and sensitive to the bending.

Measurement probe

A measurement probe for a machine tool has a housing incorporating a window that allows the optical transmission or receipt of signals from/to infrared transmitters or receivers. To obviate the need to mount the transmitter and receiver components on an external surface of the housing, they are surface mounted to a circuit board.

Probe signalling

A measurement probe for a machine tool has a housing incorporating a window which allows the optical transmission or receipt of signals from/to infrared transmitters or receivers . To obviate the need to mount the transmitter and receiver components on an external surface of the housing, they are surface mounted to a circuit board

Vibrations of the stylus ( ) of a measuring probe ( ) mounted on a machine, and which are transmitted to the probe stylus via the machine quill and probe body, are reduced or eliminated by a vibration damping means positioned within a cavity of the stylus. FIG. 2 illustrates a first embodiment in which the vibration damping means is a unconstrained rubber cylinder ( ), in a hollow cartridge ( ) connected to the stylus at its tip. Alternatively a dynamic vibration absorber can be used.

Probe with vibration damped stylus

A touch probe has a stylus holder,which is supported on a radially extending flange,in a kinematic seat comprising pairs of balls,supporting rollers,. To avoid the use of glue to fix the balls in position, the balls are located and clamped in recesses,on flange,. Clamping pressure is provided by a plug,which is forced towards the flange by rolling a lip,over the protruding end of the plug. Other alternative constructions for providing the clamping force are described. An electrical circuit through the balls for producing a trigger signal includes a flexible member,on which electrical conducting elements,are formed. The member is positioned on the flange to overlie the recesses so that it is deformed into the recesses when the clamping force is applied. By making use of the clamping force in this way good electrical connections between the balls and the conducting elements is ensured and the need to connect wires to the balls is avoided.

Touch probe

A touch trigger probe incorporates piezoelectric sensors , whose outputs are processed by an interface circuit. The interface circuit discriminates between signals generated from the piezoelectric sensors as a result of machine vibration and those generated as a result of a genuine measurement event, by the use of a timing circuit . The timing circuit compares the time intervals (t -t );(t -t ) between attainment of first and second , and second and third output signal levels from the sensor , and upon the basis of this comparison validates (or rejects) measurements made with the probe. Additionally, the interface determines whether measurements made with the probe are taken upon the basis of outputs generated by the sensors due to a shock wave in the stylus of the probe, or as a result of strain in the stylus ; as an alternative, measurements may be made only on the basis of strain.

Touch probe and signal processing circuit therefor

Measuring probe

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.

A touch trigger probe incorporates piezoelectric sensors 50, whose outputs are processed by an interface circuit. The interface circuit discriminates between signals generated from the piezoelectric sensors 50 as a result of machine vibration and those generated as a result of a genuine measurement event, by the use of a timing circuit 90. The timing circuit 90 compares the time intervals (t.sub.1 -t.sub.2);(t.sub.2 -t.sub.3) between attainment of first 1.sub.1 and second 1.sub.2, and second 1.sub.2 and third 1.sub.3 output signal levels from the sensor 50, and upon the basis of this comparison validates (or rejects) measurements made with the probe. Additionally, the interface determines whether measurements made with the probe are taken upon the basis of outputs generated by the sensors 50 due to a shock wave in the stylus 24 of the probe, or as a result of strain in the stylus 24; as an alternative, measurements may be made only on the basis of strain.

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.

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North Nibley, United Kingdom

Peter Kenneth Hellier