Patent US4059660A successfully refreshed from Google Patents.
EP0243766A2
Expired / Lapsed
EP
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Probe for measuring workpieces
Assignee: Renishaw PLC
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Filing: 1987-04-11
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Granted: —
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Expires: 2007-04-11
Abstract
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 optimising the numbers, the 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 minimising the variation in pre-travel of the stylus.
Inventors
- 👤 Peter Hajdukiewicz
- 👤 Clifford William Archer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 17:33
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/002; G01B7/004; G01B7/008; G01B7/012
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
222 words
A contact-sensing probe for use in measuring the dimensions of workpieces on machines, said probe comprising; a fixed part intended to be mounted on the machine and having an axis, a moveable part intended to engage the workpiece during a measuring operation, support means for supporting the moveable part in a rest position on the fixed part, bias means arranged between the parts to urge the moveable part into the rest position, the moveable part being displaced from the rest position in opposition to the bias means which acts to return the moveable part to the rest position when the displacing force ceases, sensing means for sensing when the moveable part engages the workpiece and for providing an electrical signal indicative of such engagement, and an electric circuit for processing the signal, characterized by a fixed structure comprising two portions one portion being rigidly connected to the fixed part of the probe, the other portion supporting the moveable part of the probe, the two portions being interconnected at least at three locations by pillars equally spaced about the axis of the probe, the pillars having axes extending parallel to the axis of the probe, and further characterized by elongate strain sensitive devices one on each pillar, each of which has an axis inclined at an angle to the axis of the pillar.
Claim 2
Dependent Claim
222 words
A contact-sensing probe for use in measuring the dimensions of workpieces on machines, said probe comprising; a fixed part intended to be mounted on the machine and having an axis, a moveable part intended to engage the workpiece during a measuring operation, support means for supporting the moveable part in a rest position on the fixed part, bias means arranged between the parts to urge the moveable part into the rest position, the moveable part being displaced from the rest position in opposition to the bias means which acts to return the moveable part to the rest position when the displacing force ceases, sensing means for sensing when the moveable part engages the workpiece and for providing an electrical signal indicative of such engagement, and an electric circuit for processing the signal, characterized by a fixed structure comprising two portions one portion being rigidly connected to the fixed part of the probe, the other portion supporting the moveable part of the probe, the two portions being interconnected at least at three locations by pillars equally spaced about the axis of the probe, the pillars having axes extending parallel to the axis of the probe, and further characterized by elongate strain sensitive devices one on each pillar, each of which has an axis inclined at an angle to the axis of the pillar.
Claim 3
Dependent Claim
57 words
A contact sensing probe as claimed in claim 1 and characterised in that the support means comprises a pair of support elements on one of the movable part or the fixed part at each of three equally spaced apart locations and confronting support elements on the other one of said parts at each of the three locations.
Claim 4
Dependent Claim
81 words
A contact sensing probe as claimed in claim 2 characterised in that the movable member comprises a stylus holder and an intermediate member, the intermediate member is urged into said rest position'on the fixed part at said support means by said bias means, further support means are provided for supporting the stylus holder in a rest position on the intermediate member and further bias means are provided for urging the stylus holder into said rest position at said further support means.
Claim 5
Dependent Claim
64 words
A contact sensing probe as claimed in claimed in claim 3 characterised in that said further support means comprises a pair of support elements on one of the stylus holder and the intermediate member at each of three equally spaced apart locations and confronting support elements on the other one of the stylus holder and the intermediate member at each of the three locations.
Claim 6
Dependent Claim
67 words
A contact sensing probe as claimed in claim 4 characterised in that the intermediate member carries a pair of spherical seat elements at said three locations which are confronted by a pair of radially extending rollers on the fixed member to provide said support means, and are confronted by a single radially extending roller on the stylus holder at each location to provide said further support means.
Claim 7
Dependent Claim
74 words
A contact sensing probe as claimed in claim 1 characterised in that each of the strain sensitive devices are connected with an additional resistor in an electrical path between a DC voltage supply and a reference voltage to form a junction which is connected to a window comparator which produces a pulse signal when the variation in voltage at the. junction exceeds a predetermined level, which pulse signal constitutes the output of the probe.
Claim 8
Dependent Claim
44 words
A contact sensing probe as claimed in claim 6 characterised in that an auto-zeroing circuit is connected between each junction and the associated window comparator to bias the variation in voltage towards zero to compensate for drifting of the resistance of the strain gauge.
References Cited (Backward Citations)
No citation records indexed.
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