GB2542613A

GB2542613A - Measurement of features in a workpiece

Info

Publication number: GB2542613A
Application number: GB1517029.3A
Authority: GB
Inventors: Davies Matthew; White Matthew
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2015-09-25
Filing date: 2015-09-25
Publication date: 2017-03-29
Also published as: GB201517029D0

Abstract

A method of measuring one or more dimensions of a feature in a workpiece, the feature having an opening at a surface of the workpiece. A jig (figure 6, 65) is attached to the workpiece and forms an aperture around the feature. The method includes providing a depth gauge 1 having a probe 4 and a body 2, inserting the depth gauge 1 through the jig (figure 6, 65) until the body contacts the surface of the workpiece adjacent the opening, and contacting the feature with the probe 4. One or more dimensions of the feature is thus measured using the depth gauge 1. The dimension measured may be the depth of a counter-sink. Also provided is a depth gauge 1 having a probe 4 and a body 2, the body having a cylindrical portion (figure 5, 48) extending around the probe and a distal end 55 for contacting a surface of a workpiece, the probe having a check part 6 for engaging a feature of the workpiece, wherein the depth gauge is adapted to measure an offset between the surface of the workpiece and the check part when engaged with the feature.

Description

MEASUREMENT OF FEATURES IN A WORKPIECE

FIELD OF THE INVENTION

[0001] The present invention relates to a method of measuring the dimensions of one or more features in a workpiece, particularly but not exclusively countersunk holes, where a jig is attached to the workpiece in the area of the feature. The present invention also relates to an apparatus for carrying out the measurement.

BACKGROUND OF THE INVENTION

[0002] In a manufacturing environment, jigs are used to provide speed and accuracy when performing various operations, for example when drilling multiple holes at predetermined locations in a workpiece or component. During or after each drilling sequence, a sample of holes is inspected for accuracy on a pass or fail basis using a gauge. This ensures the hole measurements are to tolerance, enabling early detection of hole dimensions moving out of tolerance as well as non-conformance.

[0003] When producing holes in the wing structure of an aircraft automated drilling units are used in conjunction with jigs. The holes produced are then checked manually at intervals, for example every 1 in 10 holes may be checked. The inspection process may measure one or more dimensions, the countersink depth in particular being relevant to how flush a countersunk bolt head will sit in the surface of an aircraft wing.

[0004] When a jig is located on the surface of the aircraft wing, workpiece or component to be drilled, the jig obstructs the surface of the workpiece where the depth gauge would ordinarily be referenced from.

[0005] The operator therefore has to either remove the jig each time an inspection is required, or complete the drilling of all the holes on the drill jig with the inherent risk that the automated drilling unit (or drill operator if an automated drill is not used) is producing out of tolerance holes. Removing the drill jig at every interval that inspection is required takes time and is hence an expensive operation. Alternatively, drilling all holes and inspecting once the drilling sequence is complete means that any potential non-conformances are not identified until all the holes on that jig are drilled. This could lead to expensive rework or even the drilled component needing to be scrapped.

SUMMARY OF THE INVENTION

[0006] A first aspect of the invention provides a method of measuring one or more dimensions of a feature in a workpiece, the feature having an opening at a surface of the workpiece, with a jig attached to the workpiece and forming an aperture around the feature, the method comprising providing a depth gauge having a probe and a body, inserting the depth gauge through the jig until the body contacts the surface of the workpiece adjacent the opening, contacting the feature with the probe, and measuring one or more dimensions of the feature using the depth gauge.

[0007] A further aspect of the invention provides apparatus for measuring one or more dimensions of a workpiece feature, the apparatus comprising a depth gauge having a probe and a body, the body having a cylindrical portion extending around the probe and a distal end for contacting a surface of a workpiece, and the probe having a check part for engaging a feature of the workpiece, wherein the depth gauge is adapted to measure an offset between the surface of the workpiece and the check part when engaged with the feature.

[0008] The probe may be, for example, a dial gauge, digital indicator, clock, probe indicator, pointer, test indicator, dial test indicator etc. The feature may be any feature having an opening in the surface of the workpiece, for example, a hole drilled in the surface of a workpiece or component, however the feature could be a formed, milled or otherwise produced feature.

[0009] The invention overcomes the problem outlined above by providing a body forming part of a depth gauge, and a measurement method such that an accurate inspection can take place with the jig in situ, i.e. without removing the jig from the workpiece. The depth gauge including the body is inserted into the jig aperture located in the area around the feature, until one end of the body contacts the surface of the workpiece adjacent the opening. The depth of the feature to be measured relative to a calibration depth can then be ascertained using the probe.

[0010] Various optional but preferred features of the present invention are presented in the dependent claims.

[0011] The feature to be measured may be a hole or a countersunk hole in the workpiece. The jig located over the hole may be a drill jig. The method may further comprise using a drill engaged with the drill jig to form the hole and subsequently measuring the one or more dimensions of the hole using the depth gauge without removing the drill jig from the workpiece.

[0012] The depth gauge probe may include a check part. The dimensions of the check part may match those of the bolt, pin or other part that will be assembled into the workpiece in use, and may be a countersunk check bolt or countersunk check pin.

[0013] Depending on the dimensions of the jig, the probe may include an extension member in order that the depth gauge can measure the depth of the feature when located on or in the jig. The depth gauge may have an indicator, and the body may be detachable from the indicator.

[0014] The measurement process may include calibrating the depth gauge prior to the measurement step. The measurement may also include measuring an offset, the offset being the dimension between the surface of the workpiece and the feature.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Embodiments of the invention will now be described with reference to the accompanying drawings, in which: [0016] Figure 1 is a perspective view of the depth gauge according to an embodiment of the invention, [0017] Figures 2a and 2b are schematic views of a probe forming part of the depth gauge according to Figure 1, [0018] Figure 3 is a side view of an exemplary check part forming part of the depth gauge according to Figure 1, [0019] Figure 4 is a side view of an exemplary extension member, [0020] Figure 5 is perspective view of a body forming part of the depth gauge according to Figure 1; and [0021] Figure 6 shows the depth gauge located through an exemplary drill jig in order to measure the dimensions of a hole. DETAILED DESCRIPTION OF EMBODIMENT(S) [0022] In an embodiment, the depth gauge 1 has a body 2, and a probe 4, as shown in Figure 1. The probe 4 passes through the body 2. The probe 4 comprises an indicator 5 and a check bolt 6. The indicator 5 provides a measurement reading, and the check bolt 6 is engaged with the indicator 5. The depth gauge 1 is configured to measure whether the countersink depth of one or a series of drilled holes meets the required dimensional tolerance range. The hole forms a feature in a workpiece. The hole has an opening at a surface of the workpiece. This is an important dimension since a countersunk bolt assembled into the hole is required to be flush with the surface of the workpiece into which it assembles. In this embodiment, the workpiece forms part of an aircraft wing cover.

[0023] Figures 2 to 5 show the different components of the depth gauge 1. Figure 2a and 2b show two different indicators 5 suitable for use in the embodiment. Indicator 5a has a digital readout display 7, whereas indicator 5b has a dial indicator 8. Otherwise the indicators carry out the same function. Various forms of indicator are commonly available (for example dial gauge, digital indicator, clock, probe indicator, pointer, test indicator, or dial test indicator) and may be suitable for use as part of the depth gauge. One exemplary indication set up utilises a Mitutoyo digital indicator (DTI).

[0024] In operation, the indicator tip 10 makes contact with a surface of a component to be measured. There are various shapes and sizes of tip 10 available to suit the application. In this embodiment, the tip 10 of the indicator 5 has an external thread (not shown) in order that it can be assembled with the check bolt 6. The tip 10 is movable in an axial direction along the length of the tip 10 as shown by arrow 12, and this movement is converted into a measurement on the display 6 or dial 8. By first calibrating the gauge to read zero at a particular nominal dimension, any variation to this dimension when the tip 10 contacts a surface to be measured provides a reading of whether the dimension is above or below the nominal reading and therefore in or out of an acceptable tolerance range.

[0025] In this embodiment the indicator 5 is used in conjunction with the check bolt 6. Alternatively, the check bolt 6 may be omitted. The check bolt 6 acts as a check point. The check bolt 6 dimensions match those of the bolt which will be assembled into the aircraft wing. In alternative embodiments, the check part may be a simple pin of the correct length or diameter, or be of any nominal dimension according to the application it will serve. Figure 3 shows a check bolt 20 having a countersunk head 22. The check bolt 20 has a threaded hole 24 in the countersunk head 22, in order that the tip 10 of the indicator 5 can be threaded into the hole 24 of the check bolt 20.

[0026] Depending on the thickness of the drill jig (the thickness of the jig being the dimension extending perpendicularly away from the surface of the workpiece), an extension member or bar 30 as shown in Figure 4 may be needed. The extension bar 30 has externally threaded ends 32, 34 and connects between the indicator 5 and the check bolt 20 in order to accommodate greater distances between the check bolt 20 when in the hole and the indicator tip 10. In an embodiment where the extension bar 30 is required, the tip 10 of the indicator 5 has an internally threaded end section (not shown), in order to assemble onto an externally threaded end 32, 34 of the extension bar 30. In alternative embodiments, the extension bar may have any combination of internally or externally threaded end sections, or any other connection means to the indicator 10, or checkbolt 6. Equally then, the end sections of the indicator tip 10 and the head of the check bolt 20 may have a variety of corresponding connection means to the extension bar 30.

[0027] The body 2 is mountable to the indicator 5. The body 2 may form one of a selection of interchangeable bodies, acting as a body kit. Each body 2 may have different shapes and dimensions dependent on the desired dimensions of the hole being drilled. In an embodiment with multiple bodies 2, the operator selects one of the bodies 2, the shape and dimensions of the body 2 being based on the dimensions of the hole being drilled, as well as the access to the hole via the jig. The indicator 5 attaches to the body 2. One body 2 shown in Figure 5 comprises first and second portions 42, 43. The first portion 42 is in the form of a substantially L-shaped plate. The first portion has an elongate back 44 substantially perpendicular to a base 45. The elongate back 44 forms a rectangular plate with a substantially U-shaped cut out 46 at a distal end opposing the base 45, as shown in Figure 5. A protrusion 9 (shown in Figure 1) on the indicator 5 slots into the substantially U-shape cut-out 46 of the body 2, thereby helping locate the indicator 5 to the body 2. It is to be understood that the shape of the body 2 may take any form suitable for the indicator being used and the jig being fitted into, and is not limited to the shape described herein.

[0028] As shown in Figure 5, the second portion 43 extends from the first portion 42. The second portion 43 is a hollow tube 48 extending from the base 45. The tip 10 of the indication 5 and the check bolt 20 fit through a bore 47 of the second portion 48. The outer diameter of the tube 48 is configured to fit into the aperture in the drill jig located around the hole to be measured. A free end of the second portion has three lobes 54. Other embodiments may have more or fewer lobes, differing lobe profiles or no lobes at all. The ends of the lobes 54 define a seat 55 of the depth gauge 1 on the surface of the workpiece.

[0029] In the current embodiment, the indicator 5, check bolt 20, together with the optional extension bar 30 are assembled to the body 2 in any order, i.e. the check bolt 20 and/or extension bar 30 can be assembled on to the indicator 5 before or after assembling the indicator 5 to the body 2.

[0030] Once assembled, the depth gauge 1 may take the required measurement directly or may first be inserted into a calibration plate (not shown) to zero the indicator 5 ready for measurement. The calibration plate will include at least a surface representative of the surface of the workpiece, and a hole of nominal and known dimensions in accordance with the hole to be measured. Preferably a representative jig aperture also locates the body 2 correctly. The seat 55 of the depth gauge 1 is seated against the surface of the calibration plate, and the probe 4 is located in the calibration hole at a required point. The current embodiment measures the countersink depth, however the overall depth of the hole or any other required measurement may be taken. The operator turns the dial 7 or digital readout 8 on the indicator 5 to zero, and is then ready to measure the drilled hole. The digital readout 7 or the dial gauge 8 will provide a measurement of the deviation from the calibrated nominal dimension.

[0031] Figure 6 shows the depth gauge 1 in situ against a cover 60 of the aircraft wing through a drill jig 65. With the indicator 5 calibrated as required, the operator then inserts the depth gauge 1 including the check bolt 20 through the relevant jig position 70 into the drilled hole. Once the seat 55 of the body 2 is stable and seated firmly against the workpiece surface surrounding the hole 70, the check bolt 20 is seated in the hole, and a reading will be displayed on the indications. This reading can be referenced against the relevant flushness standard to provide a clear indication of pass or fail, i.e. whether the hole is in or out of tolerance. Alternatively, the indicator 5 can be set up to show directly the pass or fail result, for example by red or green sections on the dial gauge 5b either side of a zero reading.

[0032] The body 2 of the depth gauge 1 may be made of any material able to provide the function of supporting the probe 4 and locating the depth gauge through the jig on a repeated basis. The body 2 is required to substantially maintain the required dimensions in the conditions under which measurement is taken, for example the material used should be stable under the required temperature and pressure conditions in the manufacturing environment.

[0033] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

CLAIMS 1. A method of measuring one or more dimensions of a feature in a workpiece, the feature having an opening at a surface of the workpiece, with a jig attached to the workpiece and forming an aperture around the feature, the method comprising: providing a depth gauge having a probe and a body, inserting the depth gauge through the jig until the body contacts the surface of the workpiece adjacent the opening, contacting the feature with the probe, and measuring one or more dimensions of the feature using the depth gauge. 2. A method according to claim 1, wherein the jig is a drill jig and the feature is a hole in the workpiece, and the method further comprises using a drill engaged with the drill jig to form the hole and subsequently measuring the one or more dimensions of the hole using the depth gauge without removing the drill jig from the workpiece. 3. A method according to claim 1 or claim 2, wherein the feature is a countersunk hole. 4. A method according to any preceding claim, wherein the probe includes a check part. 5. A method according to claim 4, wherein the check part is a countersunk check bolt or countersunk check pin. 6. A method according to any preceding claim, wherein the probe further comprises an extension member. 7. A method according to any preceding claim, wherein the measurement step includes measuring an offset between the surface of the workpiece and the feature. 8. A method according to claim 7 when dependent on claim 4, wherein measuring the offset between the surface of the workpiece and the feature includes measuring the offset between the surface of the workpiece and the check part when engaged with the feature. 9. A method according to any preceding claim, further comprising calibrating the depth gauge prior to the measurement step. 10. A method according to any preceding claim wherein the probe extends through the body. 11. A method according to any preceding claim wherein the body is one of a plurality of bodies and the method further comprises interchanging the body of the depth gauge. 12. Apparatus for measuring one or more dimensions of a workpiece feature, the apparatus comprising a depth gauge having a probe and a body, the body having a cylindrical portion extending around the probe and a distal end for contacting a surface of a workpiece, and the probe having a check part for engaging a feature of the workpiece, wherein the depth gauge is adapted to measure an offset between the surface of the workpiece and the check part when engaged with the feature. 13. Apparatus according to claim 12, wherein the check part is a countersunk check bolt or a countersunk check pin. 14. Apparatus according to claim 12 or claim 13, wherein the probe further comprises an extension member. >. Apparatus according to any of claims 12 to 14, wherein the depth gauge further comprises an indicator, and the body is detachable from the indicator. >. Apparatus according to any of claims 12 to 15, wherein the probe extends through the body. CLAIMS

1. A method of measuring one or more dimensions of a feature in a workpiece, the feature having an opening at a surface of the workpiece, with a jig attached to the workpiece and forming an aperture around the feature, the method comprising: providing a depth gauge having a probe and a body, the probe including a countersunk check part, the check part having dimensions which substantially match a countersunk part to be assembled in the workpiece, inserting the depth gauge through the jig until the body contacts the surface of the workpiece adjacent the opening, engaging the feature with the countersunk check part of the probe, and measuring one or more dimensions of the feature using the depth gauge.

2. A method according to claim 1, wherein the jig is a drill jig and the feature is a hole in the workpiece, and the method further comprises using a drill engaged with the drill jig to form the hole and subsequently measuring the one or more dimensions of the hole using the depth gauge without removing the drill jig from the workpiece.

3. A method according to claim 1 or claim 2, wherein the feature is a countersunk hole.

4. A method according to claim 4, wherein the check part is a countersunk check bolt or countersunk check pin.

5. A method according to any preceding claim, wherein the probe further comprises an extension member.

6. A method according to any preceding claim, wherein the measurement step includes measuring an offset between the surface of the workpiece and the feature.

7. A method according to claim 7 when dependent on claim 4, wherein measuring the offset between the surface of the workpiece and the feature includes measuring the offset between the surface of the workpiece and the check part when engaged with the feature.

8. A method according to any preceding claim, further comprising calibrating the depth gauge prior to the measurement step.

9. A method according to any preceding claim wherein the probe extends through the body.

10. A method according to any preceding claim wherein the body is one of a plurality of bodies and the method further comprises interchanging the body of the depth gauge.

11. Apparatus for measuring one or more dimensions of a feature in a workpiece, the feature having an opening at a surface of the workpiece, with a jig attached to the workpiece and forming an aperture around the feature, the apparatus comprising: a depth gauge having a probe and a body, the body having a cylindrical portion extending around the probe and a distal end for contacting a surface of a workpiece, and the probe having a countersunk check part for engaging a feature of the workpiece, wherein the check part has dimensions which substantially match a countersunk part to be assembled in the workpiece, and wherein the depth gauge is adapted to be inserted through the jig until the body contacts the surface of the workpiece adjacent the opening and the countersunk check part engages the feature to thereby measure an offset between the surface of the workpiece and the check part.

12. Apparatus according to claim 12, wherein the check part is a countersunk check bolt or a countersunk check pin.

13. Apparatus according to claim 12 or claim 13, wherein the probe further comprises an extension member.

14. Apparatus according to any of claims 12 to 14, wherein the depth gauge further comprises an indicator, and the body is detachable from the indicator.

15. Apparatus according to any of claims 12 to 15, wherein the probe extends through the body.