Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
  • G01B7/002—Constructional details of contacts for gauges actuating one or more contacts
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
  • G01B7/004—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring coordinates of points
  • G01B7/008—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring coordinates of points using coordinate measuring machines
  • G01B7/012—Contact-making feeler heads therefor

Definitions

• PROBE This invention relates to a probe for use, for example, in conjunction with a co-ordinate measuring machine for determining the dimensions of an object and to co-ordinate measuring machines incorporating such a probe. It is an object of the present invention to provide an improved probe of the type referred to.
• a probe for use in a co-ordinate measuring machine comprising a probe stylus ovably mounted in a housing so as to project beyond said housing, a switch activating member for activating switch means, and transmission means for transmitting movement of the probe stylus into movement, preferably . linear movement, of the switch activating member.
• the probe stylus is mounted for multidirectional movement relative to the housing.
• the transmission means comprises a first transmission member attached to the end of the probe stylus remote from the end thereof projecting from the housing and a second transmission member attached to one end of the switch activating member, said first and second transmission members being in contact with each other by virtue of the switch activating member being biassed towards the probe stylus by biassing means such as spring means.
• a first of the two transmission members includes a seat, which is most preferably substantially conical in shape, and a second of the two transmission members includes a ball bearing which is capable of riding on the inclined surfaces of the conical seat.
• the arrangement of transmission members is usually such that, when the probe stylus is not in use, the biassing means serves to bias the transmission member attached to the switch activating members so that the ball bearing seats in the apex region of the conical seat which corresponds to a reference position in which the probe stylus is centralised.
• the first transmission member is attached to the probe stylus and the second -2- transmission member is attached to the switch activating member.
• the internal apex angle subtended by the inclined surfaces of the conically shaped seat should not be so large that the
• the • angle subtended to the horizontal by the line along the inclined internal surface thereof which extends from the apex of the conical seat to the edge of the conical seat is preferably up to 45 , more preferably 15 to 30 and most
• the probe is intended for use with a co-ordinate measuring machine which may be driven manually or under computer control.
• the position of the probe stylus may be determined by a readout/counter which provides a visual display, and also may
• the measuring operation can be capable of having data accessed from itself and through an interface presented to a computer. This facility enables the computer to drive the system to any given position and monitor its progress on the way. Once the probe has arrived at a preset reference position, the measuring operation can be
• the co-ordinate measuring machine may then be driven either manually or under computer control, until the probe stylus comes into contact with the part to be measured. At this instant the probe generates a signal via the switch which
• the main drive system of the measuring machine causes the relative data of the measuring machine's position to be presented to the computer, and the main drive system of the measuring machine to stop, reverse direction, and back the probe stylus away from the part, to the preset position, before the next operation is commanded from the computer.
• the switch means can be an infra-red type switch means with which different amounts of movement of the switch activating member cause different amounts of interference in the infra-red field of the switch.
• the amount of interference caused in such an arrangement can be interpreted by the computer to give a read out showing the movement of the actual probe stylus itself. Contours may, for example, be measured in this way.
• Figure 1 is a side view, partially in cross-section of one form of the probe according to the invention.
• Figure 2 is a schematic illustration showing how the probe may be mounted in a machine
• Figure 3 is a circuit diagram illustrating one way of using the probe
• Figure 4 is a circuit diagram illustrating another way of using the probe.
• the probe 1 has a two part housing 2, 3, ' the first part 2 and the second part 3 being secured together by means of a screw thread 4.
• the first part 2 includes an internal annular ring 5, for example of a plastics material, which receives a substantially spherical portion 6 integral with the probe stylus 7.
• the probe stylus 7 projects through the end wall 8 of the part 2 which is so shaped to allow a angular movement of the stylus 7 in any radial direction.
• a conical seat 10 is provided at the end of the probe stylus 7 remote from the tip 9 so that movement of the tip 9 causes the seat 10 to move in the opposite direction as the probe stylus 7 pivots about the ball 6.
• a ball 11 disposed in the conical seat 10 constitutes the transmission means.
• the angle subtended to the horizontal by the line along the inclined internal surface thereof which extends -from the apex of the conical seat to the edge of the conical seat is preferably up to 45°, and is most preferably 22.1/2°.
• the ball 11 mounted in a bearing 12 which carries an
• the bearing 12 is mounted on a shaft 13 which has an axially extending projection 13a_ which serves as the switch actuating member.
• This shaft 13 is slidably mounted in a linear bearing 15 within the housing part 3, the bearing 15 including ball bearings 14.
• the shaft 13 is biassed towards the seat 10 by means of a coil spring 16, the opposite ends of which abut the flange 12a_ and the bottom of the casing 15. Biassing of the shaft 13 in this way causes the ball 11 to be biassed towards the apex of the conical seat 10.
• the probe 1 is mounted on a lower body 20 which is connected to an upper body 21 by means of an insulating gasket 22.
• the upper body 21 is carried by a shank 23 which is received in the measuring machine.
• the electronic control circuitry may be located in the lower body 20.
• FIG. 3 of the drawings One form of electronic circuit is shown in Figure 3 of the drawings. This is an opto-electronic device with associated control circuitry. .
• the opto-electronic device is located relative to the switch actuating member 13a_ so that the switch actuating member enters a light field between an anode and a cathode thereby causes a change in the electronic state of the device.
• FIG. 4 of the accompanying drawings An alternative electronic circuit for use with the probe is shown in Figure 4 of the accompanying drawings.
• the work piece is held at one potential, such as earth potential, and the probe is maintained at a different potential for example 5 volts DC.
• this voltage is applied to the stylus by means of an internal connection within the probe body.
• the input signal condition of TR1 is changed and this is converted into an output pulse.
• the output electronic pulse can have many uses, depending upon the application of the probe. It may, for example, be used for gaining a data transfer from a suitable digital readout.
• tips other than the sphere 9 shown in the drawings may be used.
• the tip conveniently comprises a disc, the centre of which is attached to the shaft of the probe stylus," and a ball bearing is set near the periphery of the disc.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Length Measuring Devices With Unspecified Measuring Means (AREA)
• A Measuring Device Byusing Mechanical Method (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10525008

Family Applications (1)

Country Status (5)

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Family Cites Families (4)

• 1982
  • 1982-10-04 WO PCT/GB1982/000284 patent/WO1983001301A1/en not_active Application Discontinuation
  • 1982-10-04 GB GB08313369A patent/GB2116719B/en not_active Expired
  • 1982-10-04 EP EP82902908A patent/EP0090818A1/de not_active Withdrawn
  • 1982-10-04 JP JP57502879A patent/JPS58501690A/ja active Pending
  • 1982-10-06 IT IT23627/82A patent/IT1152698B/it active

Non-Patent Citations (1)

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