Abstract: Optical apparatus for use with a machine having parts movable along three mutually orthogonal axes. The apparatus uses a single laser to direct a main beam along a first one of the axes and a square deflector mounted on a movable part of the machine to direct the beam orthogonally into a second direction without any angular errors due to pitch or yaw of the square deflector. Thus only roll of the square deflector need be measured. Further square deflectors are used to deflect the beam around other axes of the machine whereby the co-ordinates of a measuring probe can be accurately checked against the machine scale readings. Various methods of measuring roll are described including generating side beams from the main beam and directing them in anti-parallel direction to the main beam onto detectors which detect the deviation of the anti-parallel beams due to roll of the square deflector.

Abstract: For setting the cutting tip (30) of a cutting tool (32) of a lathe, a tool-setting probe (10) has a stylus tip (18) for contacting the tool tip (30). The stylus tip (18) is generally cube-shaped. In addition to a conventional vertical datum surface (36) for setting the tool in the horizontal direction (arrow A), it has a 45.degree. sloping datum surface (38). The tool is touched in the direction of arrow A against both surfaces (36,38). The horizontal difference between the two contact positions is a measure of the height of the tool tip (30), enabling it to be set in the vertical direction.

Abstract: The invention provides an opto-electronic scale reading apparatus wherein a read head comprises a lens adapted to project a beam of collimated light through a spatial filter on to a scale having lines. Light reflected from the scale passes back through the filter and through the lens to a phase discrimination circuit. The filter comprises two gratings co-operating to produce light modulations corresponding to the scale lines. Since the light passes twice through the filter the latter has improved ability to exclude scale lines not having the periodicity demanded by the filter.

Abstract: An optical analogue probe (9) is used on a co-ordinate measuring machine (1). Prior to use, it is datumed to compensate for any misalignment of the angle (.theta.) of its measurement axis (12A) from each of the machine's axes (X,Y,Z). Trigger points (D2,D3) are defined near opposite ends of the probe's measurement range (MR). A first set of machine X,Y,Z co-ordinates of at least four points (40) on a test sphere (38) are taken at one probe trigger point (D2). A corresponding set of co-ordinates for another four points (44) are taken at the other trigger point (D3). For each set of co-ordinates, a calculation is made of the center of the sphere, giving respective center points (42,46). The vector between these center points (42,46) is parallel to the measurement axis (12A) of the probe (9). From this vector, direction cosines are calculated for correcting the probe output to give X,Y and Z values.

Abstract: Quadrature input signals from an opto-electronic or magnetic readhead which is movable relative to a periodically marked scale, are respectively multiplied by quadrature reference signals from a reference oscillator in multipliers. The resulting signals are added together in a mixer to give a signal (S) having a frequency which is the reference frequency shifted by the frequency of the input signals. This signal (S) is then compared with the reference signal. The reference signals are generated from a high frequency clock which is subsequently used to compare the period of the reference signal with that of the signal (S), giving outputs which interpolate the position of the readhead within the pitch of the marks on the scale.

Abstract: A contact sensing probe is disclosed for use with a measuring machine or machine tool for measuring the dimensions of a workpiece. The probe comprises a housing within which a stylus holder is mounted on a kinematic support. A spring urges the stylus holder into a rest position on the support and yieldingly resists tilting or lifting of the stylus holder from the support when the stylus engages a workpiece. A sensing device in the form of an accelerometer is supported within the housing on the stylus holder to sense one of the effects of stylus engagement with the workpiece, and to produce a signal which is used to stop the machine and read the signal and read the coordinates of the instantaneous stylus position. The effects sensed in different embodiments of the invention are, sudden lifting of the stylus holder due to physical displacement of the stylus, or the shockwave produced in the stylus on contact with the workpiece.

Abstract: Apparatus including an analogue-to-digital converter 26 having a given number of digits, includes a variable gain amplifier (23) for the input (VA) to the converter (26). If any one instantaneous value (21A) of the input (VA) is less than is necessary to saturate the converter (26), i.e. to use all the digits of the converter (26), the gain of the amplifier (23) is automatically set to amplify the instantaneous input (21A) to the extent necessary to saturate the converter (26). By such selective amplication of different outputs (VA), each instantaneous value (21A) is digitized by the full number of digits of the converter (26) and the resolution of the apparatus is the same for all inputs (VA) regardless of their magnitude. On the other hand the converter is not over-saturated such as could be the case if the different inputs (VA) were amplified by a common gain.

Abstract: The apparatus disclosed is a co-ordinate measuring machine having a column (33) movable relative to an object (11) for determining the contour (12) thereof. A tube (15) movable relative to the column (33) has a lens (18) focussing light to a sensing point (19) intended to lie at the contour (12). When, on moving the column (33) across the contour (12), the contour (12) rises relative to the column (33) and the lens (18), the change is at first detected by an optical position sensor (23) which produces an error signal (26A) to a motor (27) causing the latter to move the tube (15) in the sense restoring the sensing point (19) to the new position of the contour (12). The movement of the tube (15) is sensed by a further position sensor (30) which outputs a signal (30Z) connected to move the column (33) in the sense of restoring its previous position relative to the tube (15).

Abstract: The invention enables two-way communication to be established between a measuring probe on a machine spindle and the machine using only two wires between the probe and the machine. Communication from the probe to the machine is achieved by causing current changes in an electrical circuit within the probe (due to the probe circuit changing state when a workpiece is detected) to be sensed by a current sensing circuit on the machine to produce an output in the machine circuit indicative of workpiece detection. Communication from the machine to the probe is achieved by varying the voltage supplied to the probe circuit under the control of the machine controller, the change in voltage being sensed by components of the probe circuit to initiate different functions of the probe circuit e.g. re-setting the probe or changing the gain of a component.

Abstract: A contact-sensing probe for measuring workpieces includes a body (16) for attachment to a machine and a workpiece contacting stylus (22) carried by a stylus holder (24) which is mounted within the body for movement relative thereto from a rest position to a displaced position when the stylus contacts the workpiece. Sensing means are provided for sensing workpiece contact by the stylus. The sensing means comprise a plurality of strain gauges (46) mounted on pillars (44) connecting two parts (36A,36B) of a support structure which supports the stylus holder on the body. The strain gauges are mounted with their principal axes lying at an angle to the axes of the pillars, and by optimizing the numbers, positions and dimensions of the pillars together with the angles of the strain gauges, high sensitivity can be achieved with minimum risk of false signals due to probe vibration, while at the same time minimizing the variation in pre-travel of the stylus.

Abstract: A contact sensing probe is disclosed for use with a measuring machine or machine tool for measuring the dimensions of a workpiece. The probe comprises a housing within which a stylus holder is mounted on a kinematic support. A spring urges the stylus holder into a rest position on the support and yieldingly resists tilting or lifting of the stylus holder from the support when the stylus engages a workpiece. A sensing device in the form of an accelerometer is supported within the housing on the stylus holder to sense one of the effects of stylus engagement with the workpiece, and to produce a signal which is used to stop the machine and read the signal and read the coordinates of the instantaneous stylus position. The effects sensed in different embodiments of the invention are, sudden lifting of the stylus holder due to physical displacement of the stylus, or the shockwave produced in the stylus on contact with the workpiece.

Abstract: A device for checking the accuracy of coordinate positioning apparatus which includes a support, a head and components for measuring the coordinate position of the head relative to the support. The device comprises a bar, a connecting member movably securable to the support, a first universal pivot for supporting the bar at one end on the connecting member, a second universal pivot adapted for establishing a universal pivotable connection between the other end of the bar and the head, and a switch for producing a signal responsive to the head attaining a predetermined location in a coordinate field of the apparatus.

Abstract: The probe has a piezo-electric sensor (22A) for determining initial contact of a stylus (16) with a workpiece (4). It also has a kinematic support (18) made up of confronting electrical contacts (19, 20) which are connected to indicate displacement of the stylus from a rest position and correct reseating on the kinematic support. The sensor (22A) and the electrical contacts (19, 20) are connected to an electrical circuit (24) within the probe. The circuit (24) has only two terminals connecting it to an external interface (9), which both receives the signals from and supplies power to the sensor (22A) and the contacts (19, 20). This enables the receipt of a signal from the contacts (19, 20) to provide a fail-safe backup to the signal from the sensor (22A) and to indicate correct reseating of the probe, while maintaining the interface (9) compatible with prior art probes having only one workpiece-engagement sensing arrangement with two terminals.

Abstract: A frequency-to-voltage converter, as applied to controlling the speed of a motor, comprises: a motor speed encoder (1) producing first and second alternating signals (3a,3b) each at the same, first frequency which frequency is dependent on the said speed, the first and second signals being in quadrature with each other; a reference oscillator (4), for producing third and fourth alternating signals (5a,5b) each at the same, reference frequency, which frequency is higher than said first frequency, the third and fourth signals being in quadrature with each other; and single sideband modulating means (6,7,8) connected to receive the first, second, third and fourth signals and to produce a fifth alternating signal (8a) which is a frequency-shifted version of one of the first and second signals.

Abstract: The method for measuring dimensions of a workpiece (15) in a coordinate measuring machine having an optical probe (14) arranged to output radiation in a direction (21A) at an angle to a surface (15A) to be measured. The probe has a housing (17) which is arranged to lie clear of a projection formed by the surface (15A) to be measured and another, adjacent, surface (15B) so that the housing can pass clear of the projection and the measurement can be made without halting the machine at the surface to be measured.The probe (14) is adapted for the radiation to be in the form of a cone (21) symmetric about an axis (Z1) transverse to the direction of movement of the probe so that the probe can sense all around the axis and therefore can sense any surface parallel or inclined to the axis regardless of the direction in which the surface faces.

Abstract: A machine has a movable member capable of releasably supporting a tool for performing an operation on a workpiece, and a supply of pressurized fluid. The tool includes an electric circuit which is provided with power from an electrically generator drivingly connected to a turbine driven by the machine's supply of pressurized fluid. The turbine may be in the form of a Pelton Wheel, the buckets of which are rotated by directing the pressurized fluid at them in a jet. The pressurized fluid may be a liquid or a gas. The tool may take one of several alternative forms, such as a boring bar or measuring probe.

Abstract: 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.

Abstract: A machine tool having a table movable relative to a head for machining a workpiece mounted on the head by a tool mounted on the table. The table also supports a magazine for blank workpieces, and the table is movable between a first position in which the head and the tool are in machining proximity and a second position in which the head and the magazine are proximate. The head has a work holder adapted to grip a blank workpiece at said second position for transfer, by movement of the table, to said first position. After machining, the workpiece is correspondingly returnable to the magazine. The work holder is mounted on a spindle supported on the head and rotatable for machining purposes. In a modification the spindle supports a tool, and the head has a gripper which is separate from the spindle and is used for the transfer of workpieces between the magazine and a work holder mounted on the table.

Abstract: A contact sensing probe is disclosed for use with a measuring machine or machine tool for measuring the dimensions of a workpiece. The probe comprises a housing within which a stylus holder is mounted on a kinematic support. A spring urges the stylus holder into a rest position on the support and yieldingly resists tilting or lifting of the stylus holder from the support when the stylus engages a workpiece. A sensing device in the form of an accelerometer is supported within the housing on the stylus holder to sense one of the effects of stylus engagement with the workpiece, and to produce a signal which is used to stop the machine and read the signal and read the coordinates of the instantaneous stylus position. The effects sensed in different embodiments of the invention are, sudden lifting of the stylus holder due to physical displacement of the stylus, or the shock-wave produced in the stylus on contact with the workpiece.

Abstract: An apparatus for measuring displacement between two members subject to movement relative to one another. The apparatus includes a scale defined by spaced marks provided on one of the members. A light source is arranged to illuminate the marks, wherein light reflected from the marks constitutes light signals. A light-receiving device is provided on the other of the members for receiving at least two light signals reflected from the marks in predetermined phase relationship. A determining circuit is coupled for receiving the light signals and for determining the sense of direction of the relative movement of one of the members based upon the phase relationship of the two light signals. A single optical fiber is provided for transmitting the light signals between the light-receiving device and the determining circuit. Additionally, color-encoding means are located for color-encoding the respective light signals.