Machining method, application tool, and machining arrangement for modifying or repairing a surface spot of a workpiece surface of a fiber composite workpiece

Abstract

To reduce the processing time in the case of repairing of excessively countersunk bolt openings or surface damage in fiber composite workpieces, it is proposed to countersink the corresponding surface spot to produce a contact surface and a depression for a fiber composite insert body. The fiber composite insert body is placed onto the contact surface and is fixed on the fiber composite workpiece in the depression. In the case of an excessively countersunk bolt opening, a new bolt opening is drilled into the fiber composite insert body, which new bolt opening is subsequently countersunk to the correct countersunk bore depth. In the case of the method, a three-legged application tool can be used which positions and orients the fiber composite insert body correctly and presses it onto the fiber composite workpiece during the curing of the adhesive.

Claims

1. A machining method for modifying or repairing a surface spot of a workpiece surface of a fiber composite workpiece, the surface spot, first of all, not corresponding to a design specification, and corresponding to the design specification after the modifying or repairing, wherein the surface spot is a countersunk bolt opening, comprising the steps: 1.1 further countersinking the countersunk bolt opening to produce a contact surface and a depression; 1.2 placing a fiber composite insert body onto the contact surface, and fixing the fiber composite insert body on the fiber composite workpiece in the depression; and 1.3 producing an end bolt opening in the fiber composite insert body in accordance with the design specification.

2. The machining method as claimed in claim 1, wherein, in step 1.2, the fiber composite insert body is positioned concentrically with respect to the depression during the placing of the fiber composite insert body onto the contact surface.

3. The machining method as claimed in claim 1, wherein step 1.2 comprises at least one of: pressing the fiber composite insert body onto the fiber composite workpiece; or adhesively bonding the fiber composite insert body to the fiber composite workpiece.

4. The machining method as claimed in claim 1, wherein, in step 1.2, the fiber composite insert body protrudes beyond the workpiece surface in an axial direction of the depression, and step 1.2 comprises a removal of the fiber composite insert body until it is at least one of flat or flush with the workpiece surface.

5. The machining method as claimed in claim 4, wherein the removal takes place in such a way that, although any coatings of the workpiece surface are gripped, they are not removed.

6. The machining method as claimed in claim 5, wherein the coatings of the workpiece surface are roughened, but not removed, as they are gripped.

7. The machining method as claimed in claim 4, wherein, in step 1.2, the removal takes place by means of grinding.

8. The machining method as claimed in claim 1, wherein, after step 1.2 a functional coating, formed as lightning protection materials, is re-established.

9. The machining method as claimed in claim 1, distinguished by the step: providing of the fiber composite insert body by cutting out or by drilling out the fiber composite insert body from a fiber composite body.

10. The machining method as claimed in claim 1, wherein, in step 1.2, at least one of: the fiber composite insert body is positioned concentrically with respect to the countersunk bolt opening during placing of the fiber composite insert body onto the contact surface; the fiber composite insert body has a pilot opening for at least one of positioning or orienting the fiber composite insert body during at least one of placing or fixing, the pilot opening at least one of being positioned concentrically with respect to the countersunk bolt opening or being oriented parallel to the countersunk bolt opening due to the placing of the fiber composite insert body onto the contact surface; or the fiber composite insert body protrudes beyond the workpiece surface in an axial direction of the countersunk bolt opening, step 1.2 comprising a removal of the fiber composite insert body until it is flush with the workpiece surface.

11. The machining method as claimed in claim 10, wherein, in step 1.3, at least one of: the end bolt opening is produced by way of enlarging of the pilot opening; or the production takes place by means of drilling.

12. The machining method as claimed in claim 11, wherein the production takes place by way of drilling, and the drilling comprises reaming.

13. The machining method as claimed in claim 1, wherein the countersunk bolt opening has a countersunk bore depth, and the end bolt opening has an end countersunk bore depth, the countersunk bore depth and the end countersunk bore depth being defined in each case relative to the workpiece surface of the fiber composite workpiece, the machining method modifying the countersunk bore depth to the end countersunk bore depth, and comprising a step 1.4 which comprises countersinking of the end bolt opening to the end countersunk bore depth.

14. The machining method as claimed in claim 13, wherein the modifying of the countersunk bore depth comprises a reducing of the countersunk bore depth.

15. The machining method as claimed in claim 13, wherein, in step 1.4, the end countersunk bore depth is selected such that a bolt which is configured for the countersunk bolt opening and was not flush with the workpiece surface when the bolt was inserted into the countersunk bolt opening, is then flush with the workpiece surface when the bolt is inserted into the end bolt opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments will be described in greater detail on the basis of the appended diagrammatic drawings, in which:

(2) FIG. 1 shows a cross-sectional view of a countersunk bolt opening,

(3) FIG. 2 shows a perspective view of the countersunk bolt opening,

(4) FIG. 3 shows a cross-sectional view of a countersunk bolt opening which has been countersunk further,

(5) FIG. 4 shows a perspective view of the countersunk bolt opening which has been countersunk further,

(6) FIG. 5 shows a cross-sectional view of the countersunk bolt opening with a fiber composite insert body,

(7) FIG. 6 shows one exemplary embodiment of an application tool,

(8) FIG. 7 shows a detailed view of the fiber composite insert body from FIG. 6,

(9) FIG. 8 shows a further detailed view of the fiber composite insert body from FIG. 6,

(10) FIG. 9 shows a view of the fiber composite insert body from FIG. 6 from below,

(11) FIG. 10 shows a cross-sectional view with a fiber composite insert body which has had material removed,

(12) FIG. 11 shows a perspective view of a fiber composite workpiece,

(13) FIG. 12 shows a perspective view of a further fiber composite workpiece,

(14) FIG. 13 shows a cross-sectional view with an inserted bolt,

(15) FIG. 14 shows a perspective view of a fiber composite workpiece,

(16) FIG. 15 shows a perspective view of a fiber composite workpiece from FIG. 14,

(17) FIG. 16 shows a view relating to the cutting out of the fiber composite insert body,

(18) FIG. 17 shows a view of the fiber composite insert body which is extracted in FIG. 16, and

(19) FIG. 18 shows an enlarged view of the cut surface of the extracted fiber composite insert body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(20) Reference is made, first of all, to FIG. 1 and FIG. 2 which show a fiber composite workpiece 10. The fiber composite workpiece 10 can be, for example, part of an aircraft component, for instance a fuselage panel or a trim element.

(21) The fiber composite workpiece 10 has a surface spot 11 to be machined. The surface spot 11 can be, for example, a countersunk bolt opening 12. The surface spot 11 can also be damage of the fiber composite workpiece 10, which damage has been produced by way of impact. In the following text, the examples will be described on the basis of the countersunk bolt opening 12. It can be seen, however, that the measures which are described herein are also suitable for damaged surface spots 11.

(22) The fiber composite workpiece 10 has the countersunk bolt opening 12 for a bolt 14. The bolt 14 is, for example, a round bolt and can have a thread.

(23) The countersunk bolt opening 12 has a countersunk bore 16, for example in a cylindrical form. The countersunk bore 16 has a countersunk bore depth 18. The countersunk bore depth 18 is measured from a workpiece surface 20 of the fiber composite workpiece 10. The countersunk bolt opening 12 is shown here as a blind bore, but can also be a through hole or another type of hole.

(24) Furthermore, the countersunk bolt opening 12 has a shank region 22 for receiving a bolt shank 24 of the bolt 14. Furthermore, the bolt 14 comprises a bolt head 26 which can be arranged in the countersunk bore 16.

(25) As can be seen from FIG. 1, in particular, the bolt head 26 is arranged at a greater depth than the workpiece surface 20, with the result that the bolt 14 is not flush with the workpiece surface 20. The spacing between the bolt 14 and the workpiece surface 20 is as a rule less than 1 mm, but is more than the allowed tolerance permits. Therefore, the bolt 14 does not correspond to a design specification.

(26) In order then to modify the countersunk bore depth 18 in such a way that the bolt 14 is flush with the workpiece surface 20, the fiber composite workpiece 10 is machined as described in the following text.

(27) As shown in FIG. 3 and FIG. 4, the countersunk bolt opening 12 is countersunk further by means of a conical countersink tool, in order to obtain a conical countersunk bore 28. Here, the countersunk bore 16 (or damage) can be removed completely. The cone angle is preferably between 90° and 130°. In particular, the cone angle is 100°. Other angles are not ruled out, depending on the application.

(28) In addition, the conical countersunk bore provides a contact surface 30 for a fiber composite insert body 32 which is preferably of conical or frustoconical configuration. The contact surface 30 is preferably cleaned, in order to obtain an adhesive surface 34.

(29) Furthermore, the countersunk bore provides a depression 33 for the fiber composite insert body 32.

(30) Resin material is then applied as adhesive 35 to the adhesive surface 34 and a circumferential surface 36 of the fiber composite insert body 32. The quantity of adhesive 35 is preferably overdimensioned, in order to close any pores on the adhesive surface 34 and/or the circumferential surface 36. Furthermore, air bubbles which are enclosed by way of the adhesive can be moved out of the adhesive region.

(31) As shown in greater detail in FIG. 5 to FIG. 7, the fiber composite insert body 32 is inserted into the countersunk bolt opening 12 and is placed onto the contact surface 30, in particular the adhesive surface 34. The fiber composite insert body 32 can have a pilot opening 38 for positioning and orienting. For this purpose, an application tool 40 can be used.

(32) The application tool 40 has a supporting frame 42. The supporting frame 42 is preferably configured as a tripod 44, and can be fastened releasably to the fiber composite workpiece 10, for example by means of releasable adhesive connections 46. Vacuum suction cups or magnets can also be used for the releasable fastening.

(33) Furthermore, the application tool 40 comprises a guide bolt 48 which is supported on the supporting frame 40 such that it can be displaced vertically. The guide bolt 48 can grip the fiber composite insert body 32 and, in particular, can engage into the pilot opening 38, in order to position the fiber composite insert body 32 concentrically with respect to the countersunk bolt opening 12 and/or to orient it parallel to the countersunk bolt opening 12.

(34) In addition, the application tool 40 can have a pressing device 50, by means of which a force can be exerted on the fiber composite workpiece 10 in the axial direction of the fiber composite insert body 32 in the direction of the fiber composite workpiece 10. In the present case, the pressing device 50 comprises an elastic element 52, for example a helical spring 54, the exerted force of which can be set by way of a setting element 56, for example a nut 58.

(35) The fiber composite insert body 32 can be positioned or oriented concentrically with respect to and/or parallel to the countersunk bolt opening 12, in particular, on account of the interaction of the fiber composite insert body 32 with the contact surface 30, optionally with the aid of the application tool 40.

(36) The result of the step can be seen, in particular, in FIG. 8 and FIG. 9. The fiber composite insert body 32 is preferably configured in such a way that it protrudes beyond the workpiece surface 20 in the axial direction of the countersunk bolt opening 12. Furthermore, the excessive quantity of adhesive 35 can be seen.

(37) As shown in FIG. 10 to FIG. 12, the fiber composite insert body 32 is removed, in particular is ground off, until the fiber composite insert body 32 is flush with the workpiece surface 20. It is ensured here that any functional coating 60 is not removed during the removal. The fiber composite insert bodies 32 are optionally provided with the functional coating 60 and are therefore integrated. One example for a functional coating 60 is, for instance, lightning protection material.

(38) As shown in FIG. 13 to FIG. 15, the pilot opening 38 is widened, in particular is drilled out, in order to provide an end bolt opening 62. On account of the previously performed positioning and orientation, the end bolt opening 62 is also concentric and parallel with respect to the countersunk bolt opening 12. It should be noted that this is fundamentally also possible without the pilot opening 38, but can require more skill, for instance.

(39) The end bolt opening 62 is then countersunk, in order to obtain an end countersunk bore 64. The end countersunk bore 64 has an end countersunk bore depth 66 which is configured in such a way that, when it is inserted into the end bolt opening, the bolt 14 is flush with the workpiece surface 20.

(40) It will be explained in greater detail in the following text on the basis of FIG. 16 to FIG. 18 how the fiber composite insert body 32 can be manufactured.

(41) First of all, a fiber composite body 68 can be provided which is preferably manufactured from the same material as the fiber composite workpiece 10.

(42) A fiber composite cutting tool 70 is used, in order to cut out the fiber composite insert body 32 from the fiber composite body 68. The fiber composite cutting tool 70 preferably has a central drill section 72 and a cutting head 74. During the cutting out, the drill section 72 forms the pilot opening 38, whereas the cutting head 74 forms the circumferential surface 36 of the fiber composite insert body 32.

(43) The fiber composite insert body 32 can be cleaned by means of an ultrasonic bath, and can subsequently be used.

(44) FIG. 18 shows the cut surface or circumferential surface 36 in greater detail. As can be seen, no fibers protrude from the cut surface, and merely relatively small machining marks can be seen.

(45) It is therefore proposed, in order to reduce the processing time in the case of the repair of excessively countersunk bolt openings in fiber composite workpieces, to insert a fiber composite insert body made from fiber composite material into the excessively countersunk bolt opening. The insert body is adhesively bonded to the fiber composite workpiece. A new bolt opening is drilled into the insert, which bolt opening is subsequently countersunk to the correct countersunk bore depth. In the case of the method, a three-legged application tool can be used which positions and orients the fiber composite insert body correctly and presses it onto the fiber composite workpiece during the curing of the adhesive.

(46) By way of the measures which are described herein, the processing time for machining and/or repairing excessively countersunk bolt openings in fiber composite workpieces can be reduced considerably, by almost up to seven hours per bolt opening. Furthermore, the method can be taught simply, and can therefore be carried out reliably by more workers than has been the case up to now.

(47) While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

LIST OF DESIGNATIONS

(48) 10 Fiber composite workpiece

(49) 11 Surface spot

(50) 12 Countersunk bolt opening

(51) 14 Bolt

(52) 16 Countersunk bore

(53) 18 Countersunk bore depth

(54) 20 Workpiece surface

(55) 22 Shank region

(56) 24 Bolt shank

(57) 26 Bolt head

(58) 28 Conical countersunk bore

(59) 30 Contact surface

(60) 32 Fiber composite insert body

(61) 33 Depression

(62) 34 Adhesive surface

(63) 35 Adhesive

(64) 36 Circumferential surface

(65) 38 Pilot opening

(66) 40 Application tool

(67) 42 Supporting frame

(68) 44 Tripod

(69) 46 Adhesive connection

(70) 48 Guide bolt

(71) 50 Pressing device

(72) 52 Elastic element

(73) 54 Helical spring

(74) 56 Setting element

(75) 58 Nut

(76) 60 Functional coating

(77) 62 End bolt opening

(78) 64 End countersunk bore

(79) 66 End countersunk bore depth

(80) 68 Fiber composite body

(81) 70 Fiber composite cutting tool

(82) 72 Drill section

(83) 74 Cutting head