Abstract: An automatic pallet handling system for a machine tool is described in which the pallets are formed as lightweight cassettes (10) which can be mounted by means of shaped locating features on the external periphery of a receiving device (4) mounted, for example, for rotation with a horizontal indexing spindle (2) in a vertical spindle CNC machine. A portable cassette-loading system (15) which consists of a chain conveyor (17) having links (18) pivotably connected side-by-side and formed from lightweight extrusions is positionable adjacent the machine or removable to a loading station. The extruded links form features for engaging the same cassette-locating features on the cassettes and a transfer mechanism (50) slides the cassettes from the loading conveyor to the periphery of the receiving device.

Abstract: A measuring machine includes a table, a base and a metrology frame that supports carriages for moving a probe around the working volume of the machine. The metrology frame is fabricated into a lightweight but torsionally rigid structure. The base that supports the metrology frame on the table is rigidly connected to the metrology frame but is kinematically located on the table by supports. The table and the base can also be made as relatively lightweight structures but distortions of the table due to heavy workpieces are not transmitted to the metrology frame. The construction of the machine also enables it to be easily dismantled and packed for transportation.

Abstract: An analogue probe has a fixed structure and a stylus supporting member connected to the fixed structure by three serially mounted pairs of leaf springs interconnected by first and second intermediate members. The stylus supporting member supports an elongate stem upon which a cube, which supports three scales, is mounted. Readheads are mounted on the fixed structure, in register with the scales, to transduce movement of the stylus supporting member in three substantially orthogonal directions. The alignment of the scales about the yaw axis (extending in a direction perpendicular to the plane of the scale) determines the alignment of the measuring axes of the probe, while the straightness of the lines of the scales determines the straightness of the axes.

Abstract: A machine is disclosed having novel air bearings for supporting one machine part for translational movement on another part in a first direction X. Each bearing takes the form of a track (5A,14,16) on one of the parts providing concave part-cylindrical bearing surfaces (5A,14A,16A) and pads 25 on the other part providing confronting convex part-cylindrical bearing surfaces 25A. The arc lengths of the part-cylindrical bearing surfaces are such as to provide restraint against relative movements between the machine parts in at least one sense of both of the two directions (Y,Z) orthogonal to the direction (X) of the translational movement. The advantages are relative cheapness of manufacture compared to vee-bearings and a capability of the bearings to self-align under load.

Abstract: A measuring probe comprises a stylus-carrying member on which a stylus is magnetically retained. The carrying member is supported on a flat diaphragm spring for tilting movement relative to an intermediate member. The intermediate member is supported on two further diaphragms for linear movement relative to a housing. The spring rates of diaphragm and further diaphragms are chosen to give the probe the desired relative force/displacement characteristics in X,Y and Z.

Abstract: A touch trigger probe includes a hybrid integrated circuit (58). On this circuit are provided both kinematic support elements (28) for supporting a deflectable stylus (14) in a precise rest position, and sensing elements (40) for detecting contact between the stylus (14) and a workpiece. Embodiments are also disclosed in which the kinematic support elements are provided on a silicon chip, e.g. by micro-machining.

Abstract: 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.

Abstract: An optical inspection probe, used on a coordinate measuring machine, includes a sensing module having a CCD array and an imaging module releasably mountable thereon. The position of a feature on the surface is measured using the probe by calculating the instant of time at which an image of the feature will pass across a predesignated pixel Q.sub.c of the array. The calculation is performed on the basis of the relative velocity of the probe and the surface as determined from two consecutively scanned image frames of the CCD array. The probe may be used to determine, for example, the position of an edge of a surface by moving the probe laterally with respect to the surface or, may be used to measure the position of a predetermined height of a surface by projecting a light beam onto the surface at an angle to the optical axis and measuring the position of the resulting spot on the surface.

Abstract: A touch trigger probe for machine tools or coordinate measuring machines has three strain gauges SG1-3 which react to deflection of a stylus of the probe, causing a trigger signal to be generated in signal processing circuitry SP. To reduce power consumption, and thus to reduce thermal growth of the probe, the strain gauges are fed by constant current sources CS1-3. The sources CS1-3 are servo controlled from a reference resistance R.sub.ref and constant current source CS4, by an amplifier A4.

Abstract: A radio transmission system for a touch trigger probe for machine tools or coordinate measuring machines. In the transmitter shown in FIG. 1, a 1 kHz oscillator produces a signal which is phase modulated by an electronic switch and an inverter, when electrical contacts within the probe change state. This phase modulated signal is mixed in a mixer with an unmodulated 500 Hz reference signal, produced in a divider from the oscillator, so that there is a precise phase relationship between the two signals. The receiver shown in FIG. 2 has filters which separate out the 500 Hz reference signal and the phase modulated 1 kHz signal. A decoder phase demodulates the 1 kHz signal, using the 500 Hz signal as a reference in order to increase the reliability of the resulting signal.

Abstract: A touch trigger probe has electrical contacts. A comparator compares the resistance of the contacts with a threshold, in order to generate a repeatable trigger signal when the contacts open. To ensure that the trigger signal can be generated reliably even if the resistance of the contacts when closed should increase, the threshold set is variable. The threshold can, for example, be set by a sample and hold circuit which tracks the resistance of the contacts when closed.

Abstract: A core 4 is mounted on a machine tool for indexable rotation about an axis 2A, so as to bring respective cassettes 10 into position where they can be operated on by tools held in the machine tool spindle 6. The cassettes 10 may hold workpieces 14,14A for machining. After machining, the workpiece 14A is measured by a probe 20 held in the machine tool spindle 6. A pre-calibrated artifact 26 held on another cassette 10 is then indexed into the same position as previously occupied by the workpiece 14A, and comparative measurements are made of the artifact. The accuracy of these comparative measurements is increased because the artifact 26 resides on the machine tool in the same thermal environment as the workpiece during the machining, and because the measurements are made in the same position within the working volume of the machine tool, so that the same regions of the machine tool's measurement scales are utilized.

Abstract: A touch trigger probe for machine tools or coordinate measuring machines has three strain gauges 10A-C, which respond to deflection of a stylus of the probe when it contacts a workpiece. The signals from the strain gauges are each rectified by precision rectifiers 18A-C, and then combined at a summing junction 20. A first comparator 28 compares the combined signal with a threshold voltage V.sub.ref1, to produce a sensitive trigger signal. A second comparator 30 compares the combined signal with a higher threshold voltage V.sub.ref2, which produces a confirmation signal. This confirms that the trigger signal is caused by a genuine workpiece contact, and not caused falsely by vibration or acceleration.

Abstract: A stylus counterbalancing mechanism for a probe includes a stylus support member suspended on a resilient suspension system and connected to a spring which provides a force to counterbalance the weight of the stylus. The spring is connected to one end of a plate which is capable of sliding up and down a rod but is locked in position due to the clockwise moment produced by the spring force. The plate is unlocked from its position, when required, by movement of an actuating member. The actuating member is slidable up and down the rod and has bearing areas arranged to provide an anti-clockwise moment to the plate to unlock it and to move it along the rod to increase or decrease the spring force as required.In the probe, the actuating member includes a projection extending through the probe housing to be operable from the outside either manually or by the co-ordinate positioning machine, the machine being programmed to move the probe to engage the projection with a fixed ledge on the machine.

Abstract: 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).

Abstract: A probe head (10) includes a support (12) by which the probe head is retained on the quill of a coordinate positioning machine, and a rotor (14) which is magnetically retained on the support (12). The rotor (14) is rotatable between a plurality of indexed angular positions provided by a ring or balls (26) and three adjacently positioned pairs of rollers (24). A drive dog shaft (20) is linearly movable to disengage the balls (26) from the rollers (24), and rotatable to rotate the rotor (14) to a new indexed position, whereupon the drive dog shaft (20) is retracted to re-engage a set of three balls (26) with the rollers (24). Exchange of a measuring probe (16) is performed by removing the entire rotor (14), and exchanging it for a further rotor carrying a different measuring probe. The engagement elements provided by rollers (24) and balls (26) thus serve the functions of (a) indexing and (b) repeatably retaining a rotor (14) on the support (12).

Abstract: A probe head (10) includes a support (12) by which the probe head is retained on the quill of a coordinate positioning machine, and a rotor (14) which is magnetically retained on the support (12). The rotor (14) is rotatable between a plurality of indexed angular positions provided by a ring or balls (26) and three adjacently positioned pairs of rollers (24). A drive dog shaft (20) is linearly movable to disengage the balls (26) from the rollers (24), and rotatable to rotate the rotor (14) to a new indexed position, whereupon the drive dog shaft (20) is retracted to re-engage a set of three balls (26) with the rollers (24). Exchange of a measuring probe (16) is performed by removing the entire rotor (14), and exchanging it for a further rotor carrying a different measuring probe. The engagement elements provided by rollers (24) and balls (26) thus serve the functions of (a) indexing and (b) repeatably .[.retaining.]. .Iadd.positioning .Iaddend.a rotor (14) on the support (12).