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EP0240151A2
Expired / Lapsed
EP
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Metrological apparatus
Assignee: Rank Taylor Hobson Ltd
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Filing: 1987-02-26
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Granted: —
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Expires: 2007-02-26
Abstract
Abstract Metrological apparatus, particularly for measuring form, has a turntable 4 and a transducer 14 and associated stylus 12 mounted so that the tip 12a of the stylus is displaceable radially and vertically relative to the turntable 4. The problem of obtaining both high resolution and large range of operation is solved by using a transducer/stylus 12,14 having a resolution of 12 nanometres and a range of only 0.4 mm and mounting the transducer 14 on an arm 10 which is driven radially and/or vertically by a computer 30 in response to the output from the transducer 14 to cause the stylus 12 to follow the workpiece surface. High resolution data defining the rotary position of the turntable 4 and the radial and vertical position of the transducer 14 is provided by a photodetector/optical grating arrangement 23, 21, 31; 27, 19, 43 and associated interpolators 42, 44, 46. A novel computer architecture comprising a host 22, master 30 and slaves 33, 35, 37 provides an efficient system for controlling the apparatus and gathering data. Efficient gathering of data is further assisted by the provision of means to cause the stylus 12 to traverse the surface of the workpiece at a constant speed, particularly as a function of the radial position of the transducer.
Inventors
- 👤 Hugh Rogers Lane
- 👤 Peter Dean Onyon
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 11:29
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/28; G01B7/282; G01B7/004; G01B7/008; G01B7/34; G01B7/345
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
141 words
Metrological apparatus comprising a rotatable member (4) for receiving a workpiece, first drive means (33) for rotating said member, a sensor (12,14) for sensing the surface of a workpiece on the rotatable member (4) during rotation thereof, means (10) supporting said sensor (12,14) for movement relative to said workpiece receiving member (4), second drive means (35,37), for effecting said movement of said sensor (12,14), and digital computer means (22,30,40) arranged to receive signals derived from said sensor (12,14) for providing metrological data, characterised in that said digital computer means (22,30,40) is operable to control relative movement between said workpiece and said sensor (12, 14) in response to said signals derived from said sensor (12,14) such that said sensor follows said workpiece surface and to provide said metrological data in dependence both on said signals and on said movement of said sensor.
Claim 2
Dependent Claim
141 words
Metrological apparatus comprising a rotatable member (4) for receiving a workpiece, first drive means (33) for rotating said member, a sensor (12,14) for sensing the surface of a workpiece on the rotatable member (4) during rotation thereof, means (10) supporting said sensor (12,14) for movement relative to said workpiece receiving member (4), second drive means (35,37), for effecting said movement of said sensor (12,14), and digital computer means (22,30,40) arranged to receive signals derived from said sensor (12,14) for providing metrological data, characterised in that said digital computer means (22,30,40) is operable to control relative movement between said workpiece and said sensor (12, 14) in response to said signals derived from said sensor (12,14) such that said sensor follows said workpiece surface and to provide said metrological data in dependence both on said signals and on said movement of said sensor.
Claim 3
Dependent Claim
29 words
Apparatus according to claim 1, characterised in that said supporting means (10) supports said sensor (12,14) for movement in a substantially radial direction relative to said rotatable member (4).
Claim 4
Dependent Claim
29 words
Apparatus according to claim 1, characterised in that said supporting means (10) supports said sensor (12,14) for movement in a substantially axial direction relative to said rotatable member (4).
Claim 5
Dependent Claim
32 words
Apparatus according to claim 1, characterised in that said supporting means (10) supports said sensor (12,14) for movement in both substantially radial and substantially axial directions relative to said rotatable member (4).
Claim 6
Dependent Claim
72 words
Apparatus according to claim 2 or 4, characterised in that said sensor (12,14) is operable for sensing form of a workpiece in a radial plane relative to said rotatable member (4) and said computer means is operable in response to said signals derived from said sensor (12,14) to control said second drive means (35) to move said sensor in said substantially radial direction so that said sensor (12,14) follows said workpiece surface.
Claim 7
Dependent Claim
77 words
Apparatus according to claim 3 or 4, characterised in that said sensor (12,14) is operable for sensing form of a workpiece in a plane substantially parallel to the axis of said rotatable member (4) and said computer means (22,30,40) is operable to control said second drive means (27) in response to said signals derived from said sensor (12,14) to move said sensor (12,14) in said substantially axial direction to cause said sensor to follow said workpiece surface.
Claim 8
Dependent Claim
63 words
Apparatus according to claim 4, characterised in that said sensor (12,14) is operable selectively in a first condition to sense workpiece form in a radial plane or a second condition to sense workpiece form in an axial plane and said computer means (22,30,40) is correspondingly operable to control the movement of the sensor (12,14) either in the radial or in the axial direction.
Claim 9
Dependent Claim
40 words
Apparatus according to any preceding claim, characterised in that said digital computer means is operable to control said first drive means (33)in response to said signals derived from said sensor (12,14) such that said sensor (12,14) follows said workpiece surface.
Claim 10
Dependent Claim
62 words
Apparatus according to any preceding claim characterised in that said sensor (12,14) comprises a stylus (12) having a tip engageable with the workpiece surface and a transducer (14) responsive to deflection of said stylus (12) in a single plane to produce said signals, said transducer (14) and stylus (12) together being rotatable for changing from said first condition to said second condition.
Claim 11
Dependent Claim
24 words
Apparatus according to any preceding claim, characterised in that said sensor (12,14) provides an output signal substantially linearly related to surface variations sensed thereby.
Claim 12
Dependent Claim
33 words
Apparatus according to claim 10, characterised in that said computer means (22,30,40) controls said second drive means (35,37) to maintain said sensor (12,14) stationary until the output signal thereof exceeds a predetermined threshold.
Claim 13
Dependent Claim
39 words
Apparatus according to claim 10 or 11, characterised in that said computer means (22,30,40) is operable to provide said metrological data by storing signals representing the position of the sensor (12,14) when the output thereof has a predetermined value.
Claim 14
Dependent Claim
19 words
Apparatus according to any preceding claim, characterised in that said sensor (12,14) has a resolution better than 20 nanometres.
Claim 15
Dependent Claim
16 words
Apparatus according to claim 13, characterised in that said sensor (12,14) can resolve to 12 nanometres.
Claim 16
Dependent Claim
22 words
Apparatus according to claim 14, characterised in that said sensor (12,14) is adapted to sense form variations of up to 0.4 mm.
Claim 17
Dependent Claim
26 words
Apparatus according to any preceding claim, characterised in that the position of the sensor (12,14) is resolved in at least one direction to within 500 nanometres.
Claim 18
Dependent Claim
25 words
Apparatus according to claim 16, characterised in that the position of the sensor (12,14) in at least one direction is resolved to within 200 nanometres.
Claim 19
Dependent Claim
25 words
Apparatus according to any preceding claim, characterised in that the rotational position of the workpiece receiving member (4) is resolved to within 5 arc seconds.
Claim 20
Dependent Claim
55 words
Apparatus according to any preceding claim, characterised in that the sensor (12,14) is adapted to resolve to less than 20 nanometres, the position of the sensor is resolved in the radial and axial directions to within one micron and the rotary position of the workpiece receiving member (4) is resolved to within 100 arc seconds.
Claim 21
Dependent Claim
60 words
Apparatus according to any preceding claim, characterised in that the sensor is adapted to resolve to less than 20 nanometres, the position of the sensor is resolved in the radial direction to within 200 nanometres and in the axial direction to within 500 nanometres and the rotary position of the workpiece receiving member is resolved to within 5 arc seconds.
Claim 22
Dependent Claim
37 words
Apparatus according to any preceding claim, characterised in that said computer means (22,30,40) is operable to control said drive means (33,35,37) to maintain substantially constant the speed of traverse of the sensor (12,14) over the workpiece surface.
Claim 23
Dependent Claim
30 words
Apparatus according to claim 21, characterised in that said computer means (40) is operable during said substantially constant speed of traverse to record positional data at substantially fixed time intervals.
Claim 24
Dependent Claim
41 words
Apparatus according to any preceding claim, characterised by detector means (23,21,31) for detecting respectively the rotary position of the workpiece receiving member (4) and the position of the sensor (12,14), said computer means further being responsive to said detector means (23,21,31).
Claim 25
Dependent Claim
36 words
Apparatus according to claim 23, characterised by interpolator means (42,44,46) responsive to said detector means (23,21,31) for deriving from said detector means (23,21,31) positional data having a resolution higher than that provided by said detector means.
Claim 26
Dependent Claim
40 words
Apparatus according to any preceding claim characterised in that computer means comprises a plurality of slave computers (32,34,36) each for controlling a respective different said drive means, and a master computer (30) for supplying instructions to said slave computers (32,34,36).
Claim 27
Dependent Claim
28 words
Apparatus according to claim 25 characterised in that said computer means includes an additional computer (30a) through which said master computer (30) communicates with said slave computers (32,34,36).
Claim 28
Dependent Claim
52 words
Apparatus according to claim 25 or 26 characterised in that said computer means includes a host computer (22) including manually operable data input means (24) and operable for supplying to said master computer (30) instructions to perform specified measuring operations in response to data input by said manually operable input means (21).
Claim 29
Dependent Claim
25 words
Apparatus according to claim 25, 26 or 27, characterised in that said computer means comprises a further computer (40) operable for recording said metrological data.
Claim 30
Dependent Claim
35 words
Apparatus according to any preceding claim, characterised in that said computer means (22,30,40) is operable for performing a cylindricity measurement by causing the sensor (12,14) to traverse a helical path or paths over a workpiece.
Claim 31
Dependent Claim
34 words
Apparatus according to any preceding claim, characterised in that said computer means (22,30,40) is operable for performing a conicity measurement by causing said sensor (12,14) to traverse a spiral path over a workpiece surface.
Claim 32
Dependent Claim
34 words
Apparatus according to any preceding claim, characterised in that said computer means (22,30,40) is operable for performing a flatness measurement by causing said sensor (12,14) to traverse a spiral path over a workpiece surface.
Claim 33
Dependent Claim
179 words
Metrological apparatus comprising a workpiece support (4), a sensor (12,14) for sensing the surface of a workpiece on said support (4), a plurality of drive means (33,35,37) for effecting relative movement between a workpiece on said support (4) and said sensor (12,14) so that said sensor (12,14) traverses the surface of the workpiece, and computer means (22,30,32,34,36) for deriving metrological data during said measuring operation, characterised in that said computer means comprises a host computer (22) having data input means (24) for the input of instructions for performing a required measuring operation, and being arranged to perform calculations on data obtained with the aid of said sensor (12,14), a master computer (30) arranged for receiving from said host computer (22) instructions defining a metrological operation to be performed, and a plurality of slave computers (32,34,36) arranged for controlling respective different ones of said drive means (33,35,37) said master computer (30) being arranged for sending to said slave computers (32,34,36) instructions, dependent upon the metrological operation to be performed, to control said drive means for the performance of said operation.
Claim 34
Dependent Claim
179 words
Metrological apparatus comprising a workpiece support (4), a sensor (12,14) for sensing the surface of a workpiece on said support (4), a plurality of drive means (33,35,37) for effecting relative movement between a workpiece on said support (4) and said sensor (12,14) so that said sensor (12,14) traverses the surface of the workpiece, and computer means (22,30,32,34,36) for deriving metrological data during said measuring operation, characterised in that said computer means comprises a host computer (22) having data input means (24) for the input of instructions for performing a required measuring operation, and being arranged to perform calculations on data obtained with the aid of said sensor (12,14), a master computer (30) arranged for receiving from said host computer (22) instructions defining a metrological operation to be performed, and a plurality of slave computers (32,34,36) arranged for controlling respective different ones of said drive means (33,35,37) said master computer (30) being arranged for sending to said slave computers (32,34,36) instructions, dependent upon the metrological operation to be performed, to control said drive means for the performance of said operation.
Claim 35
Dependent Claim
30 words
Apparatus according to claim 32, characterised by an additional computer (40) for logging data obtained during said metrological operation and for transmitting said logged data to said host computer (22).
Claim 36
Dependent Claim
31 words
Apparatus according to claim 32 or 33, characterised in that said master computer (30) also receives information from the sensor (12, 14) and as to the position of the sensor (12,14).
Claim 37
Dependent Claim
123 words
Metrological apparatus comprising a rotatable member (4) for receiving a workpiece, first drive means (33) for rotating said member, a sensor (12,14) for sensing the surface of a workpiece on the rotatable member (4) during rotation thereof, means (10) supporting said sensor (12,14) for movement relative to said workpiece receiving member (4), second drive means (35,37), for effecting said movement of said sensor (12,14), and digital computer means (22,30,40) arranged to receive signals derived from said sensor (12,14) for providing metrological data characterised in that said computer means (22,30,40), is operable to control said drive means (33,35,37) in response to signals derived from said sensor (12,14) to cause said sensor (12,14) to traverse the surface of the workpiece at a substantially constant speed.
Claim 38
Dependent Claim
123 words
Metrological apparatus comprising a rotatable member (4) for receiving a workpiece, first drive means (33) for rotating said member, a sensor (12,14) for sensing the surface of a workpiece on the rotatable member (4) during rotation thereof, means (10) supporting said sensor (12,14) for movement relative to said workpiece receiving member (4), second drive means (35,37), for effecting said movement of said sensor (12,14), and digital computer means (22,30,40) arranged to receive signals derived from said sensor (12,14) for providing metrological data characterised in that said computer means (22,30,40), is operable to control said drive means (33,35,37) in response to signals derived from said sensor (12,14) to cause said sensor (12,14) to traverse the surface of the workpiece at a substantially constant speed.
References Cited (Backward Citations)
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