Renishaw Plc

David Kenneth Thomas

Tim Prestidge

Graham Richard Ferguson

Timothy Donald Hayter

David R McMurtry

David Collingwood

Clive Esmond Harwood Renton

Edward Stott

Andrew J Harding

Geoffrey McFarland

John Charles Ould

Andrew Loach

David C Bound

Neil A Maddock

Andrew James Harding

An apparatus for digitizing an impedance is provided that comprises a first impedance element having a first impedance that varies with a property to be measured and a second impedance element having a second impedance. The apparatus also includes a drive signal generator for applying a first alternating drive signal to the first impedance element and a second alternating drive signal to the second impedance element. An analog-to-digital converter, ADC, receives a resultant signal comprising the combination of the signals produced by the application of the first and second alternating drive signals to the first and second impedance elements. The first alternating drive signal is phase shifted relative to the second alternating drive signal such that the resultant signal received and sampled by the ADC sequentially relates to the sum of, and the difference between, the first and second impedances. The apparatus also comprises a signal separator that receives sample values from the ADC and generates a sum channel and a difference channel therefrom.

Apparatus and method for digitising impedance

The invention relates to the transmission of power and/or data from/to a stationary part of a machine toolto/from an accessorymounted in the spindleof the machine tool. A first electrical link or interfaceprovides electrical communication between the stationary partand the spindle, and a second electrical link or interfaceis provided electrically connected to the first electrical link at the accessory mounting area. The second linkis in the form of electrical contacts. The invention extends to an accessory shankfor mounting to the spindleof the machine tool, and also to an accessorye.g. in the form of a measurement probe, connected to the said shank

Machine adaptation

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

The transmission of power and/or data from/to a stationary part of a machine tool to/from an accessory mounted in the spindle of the machine tool. A first electrical link or interface provides electrical communication between the stationary part and the spindle, and a second electrical link or interface is provided electrically connected to the first electrical link at the accessory mounting area. The second link is in the form of electrical contacts. An accessory shank for mounting to the spindle of the machine tool, and also to an accessory e.g. in the form of a measurement probe, connected to the said shank.

A tool shank () is described that comprises a spindle attachment portion () that is removably attachable to the rotatable spindle () of a machine tool (), a shank body portion () which extends beyond the end of the spindle when the tool shank () is attached to the spindle () of a machine tool () and the first part () of a separable electrical coupling (). The shank body portion comprises a feature () suitable for engagement with a tool change device () and the first part () of the separable electrical coupling () is located on the shank body portion () between the feature () and the spindle attachment portion (). A machine tool (), and a kit for retrofitting a machine tool (), that comprise the second part () of the separable electrical coupling () are also described.

Power and/or signal paths for a machine tool accessory

The invention relates to the transmission of power and/or data from/to a stationary part of a machine toolto/from an accessorymounted in the spindleof the machine tool. A first electrical link or interfaceprovides electrical communication between the stationary partand the spindleand a second electrical link or interfaceis provided electrically connected to the first electrical link at the accessory mounting areaThe second linkis in the form of electrical contacts. The invention extends to an accessory shankfor mounting to the spindleof the machine tool, and also to an accessorye.g. in the form of a measurement probe, connected to the said shank

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.

A displacement responsive device e.g. a measurement probe ( ) is disclosed. Displacement of a stylus ( ) causes resilient movement of a carriage ( ) supported by planar springs ( ) and ( ). This movement is detected by a capacitance sensor ( ), formed from two cylinders ( ) and ( ). The cylinders move in at least three degrees of freedom and changes in their capacitance during the said movement can be determined by a circuit (e.g. FIG. ). Movement in x, y and z directions can be sensed.

Capacitive displacement sensor

A capacitance probe is used by a coordinate measuring machine or machine tool to determine distances from the probe to the workpiece surface at various points over the surface. The probe is calibrated by moving it along a line, which is skewed to the surface. During this movement, a plurality of values of the capacitance and the corresponding values of the actual distance moved along the line are recorded. A datum value for the movement along the skewed line is also determined, which corresponds to a position at which the probe would touch the surface. The probe is calibrated without needing separate independent measurements of the distance from the probe to the surface. The workpiece surface is scanned using the thus-calibrate probe, in which different calibration values are used at different points on the surface, in order to account for the local shape of the surface.

Calibration of capacitance probe

Probe for measuring surface roughness by sensing fringe field

Probes (18A, 18B, 18C) can be interchangeably mounted in the spindle (12) of a machine tool. Each probe has an optical signal transmission system, in which an optical signal from a light emitting diode (24) is transmitted to a receiving photodiode (26). To prevent interference between the different probe signals, each probe modulates the emitted light at a different carrier frequency. The receiver (28) contains electronic bandpass filters to separate out the different carrier frequencies. The signal information is encoded onto the optical signal by phase modulation of the carrier frequency.

Signal transmission system for machine tools, inspection machines, and

Capacitive transducers

A stylus (15) for contacting a workpiece (13) to sense its position is suspended on a movable member (16) within a fixed housing (10). The suspension is by means of three connecting units (20, 30, 40). Taking the connecting unit (20)as an example, the movable member (16) is connected to an intermediate member (22) by a first pair of links (21), while the intermediate member (22) is connected to the fixed housing by a second pair of links (23). The pairs of links are rigid in tension and compression so as to prevent rotation of the stylus about a respective one of the three orthogonal axes X, Y, Z. Nevertheless, the links permit translational movement along all three axes. The similar connecting units (30, 40) likewise permit translation on all three axes, while preventing rotation about a respective one of the axes. The use of two pairs of links (21, 23) with a rigid intermediate member (22) is equivalent to the use of a much longer single pair of links without such an intermediate member, and therefore facilitates a more compact construction of the probe for a given range of translational displacement of the stylus (15).

Growing community of inventors

Bristol, United Kingdom

David Kenneth Thomas