GB2118718A

GB2118718A - Measuring devices

Info

Publication number: GB2118718A
Application number: GB08211651A
Authority: GB
Inventors: Stephen Royston Hurley; John Philip Hobson
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1982-04-22
Filing date: 1982-04-22
Publication date: 1983-11-02

Abstract

A measuring device for measuring the length of the perimeter of a profile of a component 10. The device comprises support 12 on which the component 10 is located, a plurality of plungers 16 which, in use, are urged by springs 20 into contact with the profile of the component 10. Each plunger 16 supports an elongate filament 24 which extends from a first location 26 which is fixed relative to the component 10, along the perimeter of the component to be measured, to a second location, where a tensioning means 30 is provided for applying a tensile force to the filament to urge it into contact with the component. A stop 36 is provided intermediate the first and second locations, and is secured to the filament. The position of the stop 36 relative to a datum is measured by a probe 34 and transducer 32 to provide an indication of the extent of the perimeter of the component that is contacted by the filament 24. <IMAGE>

Description

SPECIFICATION Measuring devices This invention relates to measuring devices and in particular to measuring devices for measuring the peripheral profile of a component.

There is a need for a simple measuring device for measuring the peripheral profile of large components. In particular where it is desired to match components of large diameter, for example, when welding two components together it is extremely difficult to measure across the diameter accurately with a simple cheap easy-touse device. Minor differences of the order of up to 0.5 mm in the diameter of a component which is, for example, of 1 or 2 metres nominal diameter, may have devastating results when one attempts to weld these components together.

An object of this invention is to provide a simple, cheap, easy to use, measuring device that is accurate and can be used to measure the peripheral profile of a component.

The invention as claimed enables one to measure the peripheral of the component and in this way measure other dimensions of the component.

An embodiment of the invention will now be described by way of an example with reference to the accompanying drawing.

Referring to the drawing the measuring device is provided for checking the outer circumference, and hence the diameter, of circular components 10. The device comprises a horizontal flat table 12 on which the component 10 is placed. Secured to the table at equal distance around the circumference of the component to be measured are a number of blocks 14.

Each block 14 is radially spaced outside the diameter of the component 10 to be removed and comprises a plunger 1 6 which projects radially inwards. The plunger 1 6 is urged inwards by a compression spring 20 acting between a ledge on the plunger 1 6 and each block 14.

Each plunger has a hemispherical end that contacts the outer circumference of the component 10 and a small hole 22 close to the hemispherical end.

A thin filament 24 such as a non-elastic or non-plastic metal wire or carbon fibre strands is passed through the holes 22 in the plungers 1 6 and encircles the outer circumference of the component 10. One end of the wire is securely anchored at a first location relative to the table 12 and component 10 by means of a block 26 so that the wire 24 is aligned tangentially to the outer circumference of the component 10. The other end of the wire passes through a guideway 28, aligned tangentially to the outer circumference of the component 10, to a tensioning device in the form of a toggle clamp 30. If desired the wire 24 could be tensioned by means of weights or springs attached to the wire.

The guideway 28 incorporates a linear measuring transducer 32 which produces an output signal indicative of the position of a probe 34 that engages a stop 36 secured to the wire 24.

In operation, a component 10 of known diameter is used as a reference, and located between the ends of the plungers 1 6 wire is located around the reference component 10 around the circumference to be measured and lightly tensioned to hold the wire tight.

The probe 34 locates the position of the stop 36 and the transducer 32 indicates the position of the stop 36. A display device 38, responsive to the output signal of the transducer 32, displays the measurement of the circumference, (or the diameter) of the component 10. The display device 38 is adjusted to display the exact dimension of the circumference of the reference component (as previously measured independently), taking account of the deviation of the wire 24 where it passes through the holes 22 in the plungers 16. Subsequent components 10 can then be checked with the device and their circumference (or diameter) displayed accordingly.

Periodically the accuracy of the device is checked by inserting the reference component in the loop of wire 24 and re-adjusting the display device 38.

The apparatus, although eminently suited for measuring circular components, could be used for other shapes of component such as rectangular, hexagonal or rhomboidal shapes depending upon the accuracy required.

Claims

1. A measuring device for measuring the length of the perimeter of a profile of a component comprising a support on which the component is located, a plurality of plungers which, in use, are urged into contact with the profile of the component, each plunger having means for supporting an elongate filament which extends from a first location which is fixed relative to the component, along the perimeter to be measured, to a second location, a tensioning means at the second location for applying a tensile force to the filament and thereby urge it into contact with the perimeter of the component to be measured, an indicator means located intermediate the first and second locations and secured to the filament, and means for measuring the position of the indicator means relative to a datum to provide an indication of the length of the filament over at least the extent of the perimeter of the component that is contacted by the filament.

2. A measuring device according to Claim 1 for measuring the circumference of a circular component wherein the plungers extend radially inwards and contact the component on a circumference tangentially to the first and second locations and extends around at least the complete circumference to be measured.

3. A measuring device according to Claim 1 or Claim 2 wherein the plungers are mounted to slide in blocks that are themselves mounted on a support and biassing means are provided to urge the plungers into contact with the component.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Measuring devices This invention relates to measuring devices and in particular to measuring devices for measuring the peripheral profile of a component. There is a need for a simple measuring device for measuring the peripheral profile of large components. In particular where it is desired to match components of large diameter, for example, when welding two components together it is extremely difficult to measure across the diameter accurately with a simple cheap easy-touse device. Minor differences of the order of up to 0.5 mm in the diameter of a component which is, for example, of 1 or 2 metres nominal diameter, may have devastating results when one attempts to weld these components together. An object of this invention is to provide a simple, cheap, easy to use, measuring device that is accurate and can be used to measure the peripheral profile of a component. The invention as claimed enables one to measure the peripheral of the component and in this way measure other dimensions of the component. An embodiment of the invention will now be described by way of an example with reference to the accompanying drawing. Referring to the drawing the measuring device is provided for checking the outer circumference, and hence the diameter, of circular components 10. The device comprises a horizontal flat table 12 on which the component 10 is placed. Secured to the table at equal distance around the circumference of the component to be measured are a number of blocks 14. Each block 14 is radially spaced outside the diameter of the component 10 to be removed and comprises a plunger 1 6 which projects radially inwards. The plunger 1 6 is urged inwards by a compression spring 20 acting between a ledge on the plunger 1 6 and each block 14. Each plunger has a hemispherical end that contacts the outer circumference of the component 10 and a small hole 22 close to the hemispherical end. A thin filament 24 such as a non-elastic or non-plastic metal wire or carbon fibre strands is passed through the holes 22 in the plungers 1 6 and encircles the outer circumference of the component 10. One end of the wire is securely anchored at a first location relative to the table 12 and component 10 by means of a block 26 so that the wire 24 is aligned tangentially to the outer circumference of the component 10. The other end of the wire passes through a guideway 28, aligned tangentially to the outer circumference of the component 10, to a tensioning device in the form of a toggle clamp 30. If desired the wire 24 could be tensioned by means of weights or springs attached to the wire. The guideway 28 incorporates a linear measuring transducer 32 which produces an output signal indicative of the position of a probe 34 that engages a stop 36 secured to the wire 24. In operation, a component 10 of known diameter is used as a reference, and located between the ends of the plungers 1 6 wire is located around the reference component 10 around the circumference to be measured and lightly tensioned to hold the wire tight. The probe 34 locates the position of the stop 36 and the transducer 32 indicates the position of the stop 36. A display device 38, responsive to the output signal of the transducer 32, displays the measurement of the circumference, (or the diameter) of the component 10. The display device 38 is adjusted to display the exact dimension of the circumference of the reference component (as previously measured independently), taking account of the deviation of the wire 24 where it passes through the holes 22 in the plungers 16. Subsequent components 10 can then be checked with the device and their circumference (or diameter) displayed accordingly. Periodically the accuracy of the device is checked by inserting the reference component in the loop of wire 24 and re-adjusting the display device 38. The apparatus, although eminently suited for measuring circular components, could be used for other shapes of component such as rectangular, hexagonal or rhomboidal shapes depending upon the accuracy required. Claims

4. A measuring device according to Claim 1 or Claim 2 wherein the means provided on each plunger for supporting the filament is a hold through which the filament passes.

5. A measuring device according to any one of the preceding claims wherein the filament is a wire.

6. A measuring device according to any one of the preceding claims wherein the tensioning means comprises a toggle clamp.