Lip skin sector and a method and apparatus for forming a lip skin sector

Abstract

An apparatus for forming a sector of an annular component having an arrangement for securely retaining at least a portion of a blank mountable thereon. The retaining arrangement is adapted for leaving a portion of the retainable blank accessible. A punch is provided having an external surface contour shaped to correspond to the shape of all or a part of the profile of the sector of the annular component from a trailing edge to a leading edge and/or from a leading edge to an inlet edge. The apparatus has a cooperating forming arrangement for forming the profile of the sector of the annular component from the leading edge to the inlet edge. The retaining arrangement is adapted for forming a clamping boundary enclosing the accessible part of the blank to be formed by the punch.

Claims

1. An apparatus for forming a sector of an annular component, comprising: means for securely retaining at least a portion of a blank mountable thereon; wherein the retaining means is adapted for leaving a portion of the retainable blank accessible; a punch having an external surface contour shaped to correspond to the shape of all or a part of the profile of the sector of the annular component from a trailing edge to a leading edge or from a leading edge to an inlet edge; wherein the punch or the retaining means is capable of radial movement so that the punch is capable of coming into contact with the accessible portion of the blank for forming the blank from the trailing edge to the leading edge; wherein the retaining means is adapted for allowing controlled flow of the blank material through the retaining means as the punch comes into contact with the blank for draw forming the blank across the punch; cooperating forming means for forming the profile of the sector of the annular component from the leading edge to the inlet edge; wherein the retaining means is adapted for forming a clamping boundary enclosing the accessible part of the blank to be formed by the punch; wherein the retaining means is adapted to define a gap for facilitating location of the punch; wherein the retaining means comprises a blank holder and a die; and wherein the die is a die plate which has a cut out and the blank holder has a cutout defining the gap and being formed for alignment with the cutout of the die plate in use.

2. The apparatus as claimed in claim 1, wherein the retaining means is adapted to create a continuous clamping boundary enclosing the accessible part of the blank to be formed by the punch.

3. The apparatus as claimed in claim 1, wherein the retaining means forms a frame enclosing the accessible part of the blank to be formed by the punch.

4. The apparatus as claimed in claim 1, wherein the cooperating forming means are adjustable in an axial direction.

5. The apparatus as claimed in claim 1, wherein at least part of the retaining means is capable of operating as at least part of the cooperating forming means for draw forming the sector of the annular component from the leading edge to the inlet edge.

6. The apparatus as claimed in claim 1, wherein the punch has an outer surface contour and a forming end shaped to correspond to the shape of the profile of the formed sector of the annular component from the trailing edge to the inlet edge.

7. The apparatus as claimed claim 1, wherein the external surface of the punch is optimized for springback or the external surface of the punch has a high surface finish for reducing friction during forming or the trailing edge of the punch has a radius.

8. The apparatus as claimed in claim 1, wherein the external surface contour of the blank holder and the internal surface contour of the die for engaging the blank correspond to the surface contour of a formed sector of an annular component.

9. The apparatus as claimed in claim 1, wherein the shape of the cut out is designed to match the shape of the punch with a small clearance for the blank material thickness.

10. The apparatus as claimed in claim 1, wherein the corners of the cut out of the die plate or blank holder are rounded or the boundary between the internal surface of the die plate and at least part of an internal peripheral surface of the cutout proximal to the blank is rounded by a radius for providing controlled material flow during the draw forming operation.

11. The apparatus as claimed in claim 1, wherein the die has a movable portion capable of being moved relative to the remainder of the die when the blank is clamped between the die and blank holder.

12. The apparatus as claimed in claim 1, wherein the die comprises a die plate and a support means around all or part of the perimeter of the die plate.

13. The apparatus as claimed in claim 1, wherein the punch comprises an internal grip, the internal grip having a profile for matching an internal profile of the forming punch.

14. The apparatus as claimed in claim 13, wherein the internal grip is movable in the axial direction with a resisting force provided by an integrated actuation system or biasing means.

15. The apparatus as claimed in claim 13, wherein the internal grip provides a second part of the cooperating forming means working together with the movable portion of the die.

16. The apparatus as claimed in claim 13, wherein the internal grip is alignable with the movable portion of the die as the punch forms the trailing edge to the leading edge of the lipskin sector.

17. The apparatus as claimed in claim 1, wherein the apparatus comprises two separate draw forming tools.

18. The apparatus as claimed in claim 17, wherein a first tool has a blank holder and die for retaining the blank there between with alignable cutouts formed for receiving a punch.

19. The apparatus as claimed in claim 18, wherein a second tool comprises: a sector of a punch formed for receiving the blank, the form of the punch sector corresponding closely to the form of the leading edge of the punch of the first tool or being that punch so as to neatly accommodate the blank and a clamping ring sector formed for nesting engagement with the punch with clearance for the thickness of the blank; and a cooperating forming arrangement in the form of a pair of cooperating gripping ring sectors provided for draw forming the blank from the leading edge to the inlet edge of the sector of the annular component.

20. The apparatus as claimed in claim 11, wherein actuation of the movable portions is provided by an actuation means, wherein the actuation means includes a hydraulic or electromechanical actuation system capable of causing radial motion of the punch or retaining means and is capable of causing axial motion of the cooperating forming means.

Description

(1) The invention will now be described with reference to the accompanying drawings, which show by way of example only three embodiments of an apparatus and method for forming a sector of an annular member such as a lip skin for a nacelle and the sector itself. In the drawings:

(2) Figure A is a sectional perspective view of an extended inlet cowl of a nacelle for an aircraft engine;

(3) FIG. 1 is an exploded perspective view of an apparatus for forming a sector of a lip skin;

(4) FIG. 2 is a sectional perspective view of a punch sub-assembly for forming a sector of a lip skin;

(5) FIG. 3 is an exploded sectional perspective view of an apparatus for forming a sector of a lip skin;

(6) FIG. 4 is a vertical section view of an apparatus for forming a sector of a lip skin;

(7) FIGS. 4A to 4E are vertical section views of the apparatus for forming a sector of a lip skin in first to fifth stages respectively of the forming process;

(8) FIG. 4F is a perspective view of the blank after the forming process and prior to trimming;

(9) FIGS. 5A to 5E are perspective views of a sector of a frusto-conical blank at first to fifth stages respectively of the forming process;

(10) FIG. 5F is a perspective view of a formed sector of inlet cowl after the forming process.

(11) FIG. 6 is an exploded perspective view of a second embodiment of apparatus of the present invention;

(12) FIG. 7 is a section of the perspective view of FIG. 6;

(13) FIG. 8 is a detail section view of the punch assembly of FIGS. 6 and 7;

(14) FIG. 9 is an exploded detail view of a second embodiment of die plate and cooperating forming arrangement;

(15) FIG. 10 is a sectional elevation view of the second embodiment of apparatus;

(16) FIGS. 11A to 11E are vertical section views of the apparatus for forming a sector of a lip skin in first to fifth stages respectively of the forming process;

(17) FIGS. 12A to 12E are perspective views of a sector of a frusto-conical blank at first to fifth stages respectively of the forming process;

(18) FIG. 12F is a perspective view of a formed sector of inlet cowl after the forming process.

(19) FIG. 13 is an exploded perspective view of a third embodiment showing a first tool of a two tool apparatus;

(20) FIG. 14 is a section of the perspective view of FIG. 13;

(21) FIG. 15 is an exploded perspective view of the third embodiment showing a second tool of the two tool apparatus;

(22) FIG. 16 is a section of the perspective view of FIG. 15;

(23) FIGS. 17A to 17C are vertical section views of the apparatus for forming a sector of a lip skin in first to third stages respectively carried out on the first tool of the two tool forming apparatus of the third embodiment; and

(24) FIGS. 17D to 17F are vertical section views of the apparatus for forming a sector of a lip skin in fourth to sixth stages respectively carried out on the second tool of the two tool forming apparatus of the third embodiment.

(25) Referring to the drawings and initially to FIGS. 1 to 4F, there is shown an apparatus indicated generally by the reference 31 for forming a sector of a lip skin of an aircraft nacelle. The apparatus 31 has a die plate 6 having a cast or machined surface supported by an additional cast or machined structure, not shown that transfers the force from the die plate 6 to a press system. The surface of the die plate 6 is made from a conic section with linear extensions on each side. The die plate surface is designed to ensure an even draw over the surface of a punch 12 while providing sufficient clearance to re-draw the internal surface using redraw ring sector 7. The shape of a cut out 16 in the centre of the die plate 6 is designed to match the shape of the punch 12 with a small clearance for the material blank thickness. The corners of the cut out 16 are rounded 17 to ensure sufficient material flow that also minimises wrinkling. The internal peripheral surface of the cutout 16 is rounded by a radius 14 to provide controlled material flow during the drawing operation.

(26) The re-draw ring sector 7 is movably mounted on the die plate 16 of the retaining arrangement 6, 8 facing a gap 51 for insertable movement into the gap 51. The redraw ring sector 7 is a semi arcuate member designed to draw the internal profile from the leading edge 3 to the inlet edge 2 while ensuring the blank 10 does not wrinkle or rip. The outer curved surface of the re-draw ring sector 7 is designed to match the internal profile of the punch 12 with clearance for the material thickness. The front of the re-draw ring sector 7 is rounded by radius 16 the size of which ensures that the blank 10 can re-draw around the ring sector 7 without ripping or wrinkling. The re-draw ring sector 7 can be driven by an integrated actuator system or by a series of cam dies from the main press.

(27) The blank holder 8 has a cast or machined surface to match the die plate 6. The blank holder 8 and die 6 are designed to match with clearance for the blank thickness. The main action of closing the blank holder 8 relative to the die 6 occurs in a vertical axis.

(28) The punch 12 comprises a punch sub-assembly having three main components, the internal support 11, punch 12 and internal grip 13. The internal support 11 supports the punch 12 and the internal grip 13. The external surface of the punch 12 is designed to match the internal surface of the inlet cowl up to 120 degree segments. The punch 12 is extended on each side beyond the 120 degree segment in order to minimise the distortion along the edges of the part. The punch axial length is extended beyond the trailing edge to minimise final part distortion. The internal grip 13 has an arcuate profile that matches the internal profile of the punch 12. The internal grip 13 can move in the axial direction 18 with a resisting force provided by an integrated actuation system or mechanical spring 71. The blank 10 is a profiled sheet material.

(29) The processing steps are shown in FIGS. 4A to 4F and the corresponding changes in the blank shape are shown in FIGS. 5A to 5F. The blank 10 is placed between the blank holder 8 and die 6 before closing see FIGS. 4A and 5A. The die 6 or blank holder 8 is then closed vertically. During this closing stage a force FBH-Clamp is applied to the blank holder 8 by a die cushion action from the die 6 or an additional actuation system in a preferably vertical direction 18. The blank 10 is then drawn over the punch sub-assembly 9 by a distance D Draw as shown in FIG. 4B while applying the force FBH-Draw. The blank 10 is free to draw in a controlled fashion from between the blank holder 8 and die 6 through the die cavity 16 as shown in FIGS. 4B and 5B.

(30) Upon reaching the draw depth D Draw the blank holder 8 load is increased to FBH-Stretch see FIG. 4C while the blank 10 is stretched from all sides over the punch sub-assembly 9 by a distance D Stretch. The blank 10 has minimal draw from between the blank holder 8 and die 6 during the stretching process see FIG. 4C. At this stage the inlet cowl profile from the leading edge 3 to the trailing edge 1 has been formed as shown in FIG. 5C.

(31) The blank 10 is then sheared along two axial lines see FIG. 5D either in the tooling system or by removing the part from the tooling system and using either a manual or CNC cutting process. If the material removal process occurs outside the tool system, the blank is then placed back into the tooling system see FIG. 5D and a load F BH rr Draw is applied. The blank holder 8 and die 6 remain in the D Fixed position while the load FBH-RR Draw is maintained see FIG. 4D while the re-draw ring sector 7 is forced into the punch sub-assembly 9 by a distance DRR-Draw under a spring force load of F RR-Draw see FIG. 4 D.

(32) Once the distance DRR-Draw has been reached the re-draw ring sector 7 contacts the internal grip 13 with a reaction load FRR-Stretch which then reduces or eliminates the draw of the blank 10 between the internal grip 13 and the re-draw ring sector 7. The blank 10 is then formed under tension for the remainder of the motion DRR-Stretch while the forces FBH RR draw and FRR-Stretch are maintained see FIG. 4E. The blank 10 shape is then that shown in see FIG. 5E. The blank 10 is then removed by removing all holding forces, retracting the re-draw ring sector 7 and lifting the die 6 clear as shown in see FIG. 5 F. The blank 10 is then trimmed using either a manual or CNC cutting process see FIG. 5 F.

(33) Referring to the drawings and now to FIGS. 6 to 12, there is shown a second embodiment of apparatus indicated generally by the reference numeral 21 for forming a sector of a standard lip skin and a sector 22 of an extended trailing edge lip skin. In the second embodiment, the retaining arrangement 23 has a blank holder 28 and a die 26. The die 26 has a movable portion 27 capable of being moved relative to the remainder of the die 26 when the blank 10 is clamped between the die 26 and blank holder 28. The movable portion 27 of the die 26 is located proximal to the leading edge of the die 26. By leading edge of the die 26 we mean the edge of the die 26 proximal to the leading edge of the punch 32 and the leading edge of the blank 10 to be formed into a sector 22 of an annular component such as a lipskin. The movable portion 27 of the die 26 is movable by powered actuation members 29, such as hydraulic rams. The powered actuation members 29 are operable between the movable portion 27 and another portion 30 of the die 26, mutually opposing the movable portion 27. The movable portion 27 of the die 26 provides one part of the cooperating forming arrangement indicated generally by reference numeral 33. The movable portion 27 of the die 26 is movable in a direction from the leading edge to the inlet edge of the sector 22 see FIG. 12F of the annular component for draw forming this part of the blank.

(34) The die 26 has a die plate 34, see FIG. 10 and a support member 35 see FIG. 9 around all or part of the perimeter of the die plate 34. In the embodiment shown in the drawings, the support member 35 is provided by a four walled open top box with reinforced corners and walls. Advantageously, the support member 35 provides structural support for the die plate 34 for transferring the clamping forces being applied through the die 26 to clamp the blank 10 between the die 26 and the blank holder 28 and for absorbing the actuation forces being applied by the actuation members 29 through the walls of the support member 35 to allow the movable portion 27 of the die 26 to be activated. The punch 32 has an internal grip 39. The internal grip 39 has an arcuate profile that matches the internal profile of the forming punch 32. The internal grip 39 can move in the axial direction with a resisting force provided by an integrated actuation system or biasing means such as one or more springs 36. The internal grip 39 provides the second part of the cooperating forming arrangement 33 working together with the movable portion 27 of the die 26. The internal grip 39 is alignable with the movable portion 27 of the die 26 as the punch 32 forms the trailing edge to the leading edge of the lipskin sector.

(35) The shape of a cut out 46 in the centre of the die plate 26 is designed to match the shape of the punch 32 with a small clearance for the material blank 10 thickness. The corners of the cut out 46 are rounded 47 to ensure sufficient material flow that also minimises wrinkling. The internal peripheral surface of the cutout 46 is rounded by a radius 44 to provide controlled material flow during the drawing operation. Both the upper and the lower edges of the leading edge of the movable portion 27 of the die 26 have a radius 44. In terms of the meaning of radial and axial direction, arrows Rd and Ad on FIG. 11E indicate the radial and axial directions respectively.

(36) The processing steps are shown in FIGS. 11A to 11F and the corresponding changes in the blank shape are shown in FIGS. 12A to 12F. The blank 10 is placed between the blank holder 28 and die 26 before closing see FIGS. 11A and 12A. The die 26 or blank holder 28 is then closed vertically. During this closing stage a force FBH-Clamp is applied to the blank holder 28 by a die cushion action from the die 26 or an additional actuation system in a preferably vertical direction 18. The blank 10 is then drawn over the punch 32 by a distance D Draw as shown in FIG. 11B while applying the force FBH-Draw. The blank 10 is free to draw in a controlled fashion from between the blank holder 28 and die 26 through the die cavity 46 as shown in FIGS. 11B and 12B.

(37) Upon reaching the draw depth D Draw the blank holder load is increased to FBH-Stretch see FIG. 11C while the blank 10 is stretched from all sides over the punch 32 by a distance D Stretch. The blank 10 has minimal draw from between the blank holder 28 and die 26 during the stretching process see FIG. 11C. At this stage the inlet cowl profile from the leading edge 3 to the trailing edge 1 has been formed as shown in FIG. 12C.

(38) The blank 10 is then sheared along two axial lines see FIG. 12D either in the tooling system or by removing the part from the tooling system and using either a manual or CNC cutting process. If the material removal process occurs outside the tool system, the blank is then placed back into the tooling system see FIG. 12D and a load F BH RR Draw is applied. The blank holder 28 and die 26 remain in the D Fixed position while the load FBH-RR Draw is maintained see FIG. 12D while the movable portion 27 of the die 26 is forced into the punch 32 by a distance DRR-Draw under a spring force load of F RR-Draw see FIG. 11D.

(39) Once the distance DRR-Draw has been reached the movable portion 27 of the die 26 contacts the internal grip 39 with a reaction load FRR-Stretch which then reduces or eliminates the draw of the blank 10 between the internal grip 39 and the movable portion 27 of the die 26. The blank 10 is then formed under tension for the remainder of the motion DRR-Stretch while the forces FBH RR draw and FRR-Stretch are maintained see FIG. 11E. The blank 10 shape is then that shown in see FIG. 12E. The blank 10 is then removed by removing all holding forces, retracting the movable portion 27 of the die 26 and lifting the die 26 clear as shown in see FIG. 12 F. The blank 10 is then trimmed using either a manual or CNC cutting process see FIG. 12 F.

(40) Referring to the drawings and now to FIGS. 13 to 17, there is shown a third embodiment of apparatus for forming lip skin sector. In the third embodiment, the apparatus has two separate draw forming tools, the first tool 51 having similar components to the components illustrated in FIGS. 6 to 12. The first tool 51 has blank holder 52 and die 53 for retaining a blank 54 there between with alignable cutouts 56, 57 respectively for receiving punch 55. The function of the tool is clearly illustrated in FIGS. 17A to 17C and will be described in greater detail below. In view of the fact that a second tool is used as illustrated in FIGS. 15 and 16 and in FIGS. 17D to 17 F, no cooperating forming arrangement is included in the first tool.

(41) The second tool illustrated in FIGS. 15 and 16 comprises a sector of a punch 65 formed for receiving the partially formed lip skin sector formed by the tool illustrated in FIGS. 13 and 14. The form of the arcuate leading edge of the punch 65 corresponds closely to the form of the leading edge of the punch 55 so as to neatly accommodate the partially formed lip skin sector. A clamping ring sector 66 has an interior curved surface formed for nesting engagement with the exterior curved surface of the punch 65 with clearance for the thickness of the blank 10. In use an operator removes the partially formed blank from the first tool and sets it onto the punch 65. The operator actuates a powered actuation system to move the clamping ring sector 66 and/or punch 65 so as to bring the blank 10 into engagement with the clamping ring sector 66. A cooperating forming arrangement in the form of a pair of cooperating gripping ring sectors 67, 68 are provided for draw forming the blank from the leading edge to the inlet edge of the lip skin sector. Gripping ring sector 68 is an internal gripping ring sector 68 having an external curved surface formed for engaging the internal surface of the blank 10. Gripping ring sector 67 is an external gripping ring sector 67 having an internal curved surface formed for engaging the external surface of the blank 10.

(42) Gripping ring sector 67 has an interior curved surface formed for nesting engagement with the exterior curved surface of the gripping ring sector 68 with clearance for the thickness of the blank 10. The operator actuates a powered actuation system to move the griping ring sector 68 into engagement with the blank 10 and then moves the gripping ring sector 67 into engagement with the blank. The leading edge of the gripping ring sector 67 is radiused to allow the blank 10 to flow through and around the leading edge during the redraw forming process.

(43) The processing steps are shown in FIGS. 17A to 17F. The blank 10 is placed between the blank holder 52 and die 53 before closing. The die 53 or blank holder 52 is then closed vertically. During this closing stage a force FBH-Clamp is applied to the blank holder 52 by a die cushion action from the die 53 or an additional actuation system in a preferably vertical direction 18. The blank 10 is then drawn over the punch 52 by a distance D Draw as shown in FIG. 17B while applying the force FBH-Draw. The blank 10 is free to draw in a controlled fashion from between the blank holder 52 and die 53 through the die cavity 57 as shown in FIG. 17B.

(44) Upon reaching the draw depth D Draw the blank holder load is increased to FBH-Stretch see FIG. 17C while the blank 10 is stretched from all sides over the punch 52 by a distance D Stretch. The blank 10 has minimal draw from between the blank holder 52 and die 53 during the stretching process see FIG. 17C. At this stage the inlet cowl profile from the leading edge 3 to the trailing edge 1 has been formed.

(45) The blank 10 is then sheared along two axial lines either in the tooling system or by removing the part from the tooling system and using either a manual or CNC cutting process. The blank is then placed into the second tooling system see FIG. 17D and a load F BH RR Draw is applied. The blank holder 52 and die 53 remain in the D Fixed position while the load FGrip-RR Draw is applied to the gripping ring sectors 67, 68 see FIG. 12D while the gripping ring sectors 67, 68 are forced into the punch 65 by a distance DRR-Draw under gripping force load of F Grip RR-Draw see FIG. 17E.

(46) Once the distance DRR-Draw has been reached a stretching load Fstretch RR draw is applied to the gripping ring sectors 67, 68 which then reduces or eliminates the draw of the blank 10 between the gripping ring sectors 67, 68. The blank 10 is then formed under tension for the remainder of the motion DRR-Stretch while the forces FBH RR stretch and F Grip RR-Stretch are maintained see FIG. 17F. The blank 10 is then removed by removing all holding forces, retracting the gripping ring sectors 67, 68 and lifting the clamping ring sector and the gripping ring sector clear. The blank 10 is then trimmed using either a manual or CNC cutting process.

(47) In relation to the detailed description of the different embodiments of the invention, it will be understood that one or more technical features of one embodiment can be used in combination with one or more technical features of any other embodiment where the transferred use of the one or more technical features would be immediately apparent to a person of ordinary skill in the art to carry out a similar function in a similar way on the other embodiment.

(48) In the preceding discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of the said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

(49) The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of a means for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or in any combination of such features be utilised for realising the invention in diverse forms thereof as defined in the appended claims.