Abstract: A rotary drive mechanism is disclosed comprising a housing (10), a first motor (12) having a first rotor (38) and a first stator (32) connected to the housing and a second motor (50) having a second rotor (52) and a second stator (54) connected to the housing characterised in that the second motor is mechanically independent of the first motor whereby acceleration torques of the first motor are at least partially inertia balanced by the second motor. The balancing may be effected by equal and opposite rotation of the second motor. Control means may be provided to provide the second motor with a current which is proportional to that supplied to the first motor. Also disclosed is a positioning device and a probe having the rotary drive mechanism.

Abstract: A probe for position determining apparatus has a probe body (18) and a workpiece-contacting stylus (14). A strain sensitive structure connects the probe body and the stylus, and includes bendable members (32). The bendable members have an asymmetric cross-section, e.g. “T” shaped. A strain gauge (33) 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.

Abstract: A machine tool control method is disclosed employing a machine tool for carrying out a work producing process having a cutting implement for machining a workpiece according to the process, the cutting implement comprising a first part having a shank and a second part having a cutting surface and, optionally a tool holder, a sensor device provided on the second part of the cutting implement for sensing at least one condition of the process, and a machine controller, the method comprising: operating the machine under the control of the machine controller to cause a process to commence, sensing at least one condition of the process, and adapting controller or sensor based cutting parameters during the process in accordance with the sensed condition. The cutting implement may be changeable during the process. The process can be a single cutting operation. Sensor based parameters can be adapted independently of the machine controller.

Abstract: A rotary ring for use in scale reading apparatus, comprises a flexible ring (10) which has scale markings (14) provided on a surface thereof. The rotary ring is mounted onto a machine part (22) by providing the machine part with a region of increased diameter (26) and stretching or shrinking the flexible rotary scale (10) over said region of increased diameter. The manufacturing tolerance of the rotary scale or differential e.g. thermal expansion is thus taken up by stretching or shrinking it into place. The region of increased diameter may comprise an annular protrusion or an O-ring, for example.

Abstract: A method of measuring an object with a coordinate positioning apparatus, comprises the following steps: placing the object within the working volume of the coordinate positioning apparatus; measuring the object with a workpiece contacting probe to create measurement data of the object, the measurement data being collected at multiple probe forces; for at least one location on the surface of the object, determining a function or look up table relating the measurement error data to the probe force; for said at least one location on the surface of the object, using the function or look up table to determine the measurement data corresponding to zero probe force; and outputting the measurement data corresponding to zero probe force as the measurement of the object.

Abstract: The invention relates to a device and method for analysis of a tool (50) e.g. used on a machine tool. A tool detector (5) includes a light emitter (12) and a light receiver (34). Tool (50) when progressed into a beam (20) of light emitted from the emitter (12) will cause a signal from the receiver to change. Circuitry (32) includes a digital signal processor which processes the signal from the receiver and produces an output only if the signal conforms to a predetermined condition. Preferably this predetermined condition could be e.g. a characteristic shape of the signal from the receiver, a change in a value derived from a succession of such signals or a change in the minimum or maximum values of a succession of signals from the receiver.

Abstract: Re-orientation of a stylus 30 or measurement probe 12 can be accomplished by engaging a part of the stylus or probe with a fixed part 50 and moving the probe in a spherical path centred at the engagement. The engagement 50 is spaced from the stylus tip 34 and avoids bending of the stylus during re-orientation. The re-orientation can take place into a plurality of e.g. repeatable rest positions by virtue of a kinematic array (e.g. balls 122 and rollers 120 FIG. 2).

Abstract: A touch probe (10,50) is disclosed comprising a probe body (12,52) housing first locating elements (23,58), a stylus holder (16,54) having second locating elements (24,57) which co-operate with the first locating elements to locate the stylus holder within the probe body, and a bias (36,68,86) to urge the first and second locating elements into contact, wherein an element (35,50,76,90) is provided to damp motion between the probe body and the stylus holder. The element may slow a relative movement between the locating elements perhaps by resisting the urging of the bias or absorb energy produced by a relative movement between the probe body and stylus holder. The element may be slidably or rotatably mounted with respect to one of the probe head and stylus holder.

Abstract: A method of measuring an object on a coordinate positioning apparatus. A first object is placed on a coordinate positioning apparatus and measured with a workpiece contacting probe to create measurement data. The measurement data is collected at multiple stylus deflections or probe forces. For a plurality of points on the surface of the first object, the measurement data is extrapolated to that corresponding to zero stylus deflection or zero probe force. An error function or map is created from the measurement data and the extrapolated data. Subsequent objects are then measured using a known stylus deflection or known probe force and the error function or map is used to apply an error correction to these measurements.

Abstract: A pivot joint has a first structure comprising a ball mounted in a receptacle, wherein the location of the ball is held with respect to the receptacle, and a second structure mounted on and movable with respect to the ball, wherein the second structure has at least one bearing surface which defines its position with respect to the ball. The ball may be held in location by contact with the receptacle at at least two positions. At least one of the positions of contact may be adjustable.

Abstract: A bearing arrangement for an articulatable support includes bearing assemblies. In one embodiment, the assemblies have a ball and aperture having sliding contact at discrete areas during relative rotation. In another embodiment, the sliding contact may be formed at a ball and a plastics (e.g. P.T.F.E. support). Resilient displacement of the bearing contact along a rotational axis is provided by planar spring supports and a rigid support is provided by supports.

Abstract: A device for the axial and rotational movement of a sample is disclosed comprising a mount member for mounting the sample, which is rotatable about and movable along an axis, characterised in that the mount member has a helical screw thread which produces the movement along said axis simultaneously with the rotation. A sample may be scanned or machined whilst being axially and rotationally moved. The screw thread may be disengageable perphaps by relative movement of co-operating screw threads into and out of engagement with each other by a lever to allow movement of the mount member along the axis without rotation when desired. The screw thread on one of the members may be formed from a piece or layer of a deformable material, which deforms to form a mating screw thread upon being brought into engagement with the screw thread on the other member. Also desclosed is a method of scanning a sample.

Abstract: A method of scanning an object is disclosed comprising the steps of providing a scanning device having a probe and a sample holder whereby the sample holder is rotatable relative to the probe, providing a first feature for indicating the start and/or end of a scan, and recognising the first feature whereby when the first feature is recognised the scanning device is ready to start or end a scan. The scanning device may have a fixed stop which comprises the first feature alternatively, the first feature is provided on the scanning device or on the object. A second feature, located on the scanning device or object for example, may be provided wherein the first feature indicates the start of a scan and the second feature indicates the end of the scan. Also disclosed is an apparatus for scanning an object.

Abstract: A measurement probe (10) has a stylus part (12) connected to it by means of a ball and cup universal joint (24/25 FIGS. 2 and 3). The stylus part (12) is reorientable relative to the probe and during reorientation is held by means of magnetism or suction to an at tractor (50) whilst the probe (10) is moved. The stylus part (12) is held in static relation to the probe during measurement by means of magnetism or vacuum. The stylus part (12) may be exchanged for another, e.g. 12a or 12b? at rack (100). During exchange the magnetism or vacuum holding (15) the probe and stylus part in static relation is reduced.

Abstract: A measurement probe (5) which comprises a housing (16) for mounting on an arm (6) of a coordinate positioning apparatus (2) and a stylus (10) mounted on a stylus support member (28). The stylus (10) and the stylus support member (28) are deflectable with respect to the housing (16). A first transducer system (40–48) measures movement of the stylus support member (28) relative to the arm (6) of the coordinate positioning apparatus (2). A second transducer system (38) measures movement of the stylus tip (12) relative to the stylus supporting member (28). A measurement of total stylus deflection is achieved by combining data from the first and second transducer systems.

Abstract: Re-orientation of a stylus (30) or measurement probe (12) can be accomplished by engaging a part of the stylus or probe with a fixed part (50) and moving the probe in a spherical path centred at the engagement. The engagement (50) is spaced from the stylus tip (34) and avoids bending of the stylus during re-orientation. The re-orientation can take place into a plurality of e.g. repeatable rest positions by virtue of a kinematic array (e.g. balls (122) and rollers (120) FIG. 2).

Abstract: A storage port (20) for separating a magnetically coupled task module (18) from a modular probe (16) mounted on a machine comprises a housing (22) and arm (24) receivable by the task module (18). A mechanism is provided for separating the task module from the probe body using a mechanical advantage, such that physical movement of the machine actuates the mechanism thereby separating the task module (18) from the modular probe (16). The arm (24) may be rotatable about a pivot (26) such that on moving the probe upwards, the task module (18) is also pulled upwards, causing the arm (24) and hence the task module (18) to rotate about the pivot (26) and thus breaking contact between the task module (18) and the probe (16) with a tilting action. Damping means (38, 48, 60, 62) are provided to ensure smooth and controlled movement of the arm (24).

Abstract: Apparatus for aligning an optical measuring system to a desired direction comprises two housings (42,48) attachable to two relatively movable parts of a machine. The housings (42,48) have engagement means (53) such that when they are engaged together the optics inside (44,50) are aligned. The first housing (42) may be provided with attachment means, such as a ball (46), which may be located in a mount (54) on the machine table (56). The position of this ball (46) is determined and the machine spindle housing (48) to be attached to the spindle (60) when the two housings (42,48) are joined and such that the apparatus is aligned with the desired direction. The engagement means (53) between the two housings (42,48) may be compliant along an axis of the apparatus.

Abstract: A bearing arrangement for an articulatable support (6) comprises bearing assemblies (20/28, 22/29, 24/30 and 26/32). In one embodiment the assemblies comprise a ball (20, 22, 24, 26) and aperture (40 FIG. 2) having sliding contact at discrete areas (36) during relative rotation. In another embodiment the sliding contact may be formed at a ball (20,22,24,26) and a plastics e.g. P.T.F.E. support (84, 85 FIGS. 10 and 11). Resilient displacement of the bearing contact along a rotational axis (A and B) is provided by planar spring supports (28, 32) and rigid support is provided by supports (29 and 30).

Abstract: A storage port (20) for separating a magnetically coupled task module (18) from a modular probe (16) mounted on a machine comprises a housing (22) and arm (24) receivable by the task module (18). A mechanism is provided for separating the task module from the probe body using a mechanical advantage, such that physical movement of the machine actuates the mechanism thereby separating the task module (18) from the modular probe (16). The arm (24) may be rotatable about a pivot (26) such that on moving the probe upwards, the task module (18) is also pulled upwards, causing the arm (24) and hence the task module (18) to rotate about the pivot (26) and thus breaking contact between the task module (18) and the probe (16) with a tilting action. Damping means (38, 48, 60, 62) are provided to ensure smooth and controlled movement of the arm (24).