Renishaw Plc

Renishaw Metrology Limited

Andrew J Harding

David R McMurtry

David Kenneth Thomas

Martin P Spivey

Peter Kenneth Hellier

John Charles Ould

Tim Prestidge

Stephen E Lummes

Timothy Donald Hayter

Jonathan S Sullivan

James Zannis

David Ian Pilborough

David R Whittle

A workpiece inspection system is disclosed for determining measurements of a workpiece on a machine tool. The system utilizes a measurement device which outputs data relating to the workpiece (e.g. in place of a conventional cutter). The problem of obtaining real time data relating to the position of the machine tool is overcome by recording a machine tool position data set and a measurement device data set at selected instants which are defined by a synchronization signal. The data sets are combined later in the correct relative position because the synchronization signal was used. The synchronization signal can issue from the machine tool controller, an interface, measurement device or another part of the system.

Machine tool workpiece inspection system

Transmission of power and/or signal across a machine tool spindle shank is disclosed. Contacts () on the shank are connectable to tracks () on the spindle (). A circuit (e.g. FIG.) is used to determine the orientation of the contacts relative to the tracks when the shank is inserted in an unknown orientation into the spindle.

Machine adaptation

An interface circuit for processing signals from a touch trigger probe is adapted to prevent the generation of false trigger signals during an inspection cycle. The probe incorporates a plurality of strain gauges, the voltage across which rises above a predetermined threshold when a stylus supported by the probe contacts a surface. When the probe is moved away from the surface and the stylus loses contact, the outputs across the gauges drop below the trigger threshold. The interface prevents false triggers When, while the stylus is in contact with a surface, a machine vibration occurs which causes an oscillation in the voltage across the gauges; the voltage dropping below the threshold level (causing the interface to reset), and then immediately passing back up through the threshold, causing the interface to emit a trigger signal. The interface of the present invention prevents such an occurrence by returning to its seated level only if, at a predetermined time interval after the sensor signal has passed below the predetermined threshold, the signal level from the or each sensor has not once again exceeded the predetermined threshold value.

Signal processing circuit for trigger probe

An arm 12 for holding a tool-setting probe 14 in a machine tool is rotatable between an operative position and an inoperative position. The operative position is defined by elements 48,52 which form a stop against further rotary motion beyond the operative position. These elements 48,52 are arranged as a kinematic support, so that the operative position is defined in a precisely repeatable manner. Springs 40 urge the elements 48,52 together. When the arm is in the operative position, these springs are stretched by a repeatable amount, so that they provide a repeatable force, in order to increase the precision of the operative position.

Probe arm for machine tool

Measuring probe

A touch probe (10) has a housing (12) and stylus-supporting member (14) biased into a kinematic rest position relative to the housing (12) by a biasing mechanism. The biasing mechanism includes a first helical spring (40) which acts between a movable shuttle (44) and an intermediate member (48). The shuttle (44) is movable within a bore (46) and the position of the shuttle within the bore may be adjusted by the action of an adjusting screw (74). A second helical spring (42) acts between intermediate member (48) and the supporting member (14). The first spring (40) has a low spring rate and is pre-loaded such that the second spring (42), which has a high spring rate, will deflect first upon movement of the shuttle (44) or supporting member (14). Once the pre-load of spring (40) has been overcome the two springs (40,42) co-operate to act as a single spring whose spring rate is the sum of the reciprocals of the spring rates of springs (40,42). This provides adjustment of the biasing force with only a small movement of the shuttle (44) while simultaneously providing large deflections of the stylus-supporting member (14) opposed with a low rate of increase of biasing force.

Touch probe

Growing community of inventors

Bristol, United Kingdom

Andrew J Harding