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

Abstract

A method of forming a sector of an annular component such as an inlet cowl/lip skin of a nacelle for an aircraft engine. The method comprising the steps of clamping at least part of a blank along a clamping boundary in a retaining arrangement so as to leave a portion of the blank exposed within the clamping boundary. Moving a punch and/or retaining arrangement radially so that the punch comes in to contact with the exposed portion of the blank and through the main body of the exposed blank thereby drawing the blank onto an external surface of the punch forming the sector from the leading edge to the trailing edge. Activating cooperating forming arrangement for engaging the blank and drawing the blank over the punch forming the sector of the inlet cowl from the leading edge to the inlet edge, the method comprising using a second draw forming tooling arrangement for the cooperating forming arrangement.

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, the retaining means being adapted to leave a portion of the blank accessible, and a punch having an external surface contour shaped to correspond to the shape of all or a part of a profile of the sector of the annular component from a trailing edge to a leading edge and/or from the leading edge to an inlet edge, wherein the punch and/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, the retaining means is adapted to allow controlled flow of the blank through the retaining means as the punch comes into contact with the blank for draw forming the blank across the punch, and the retaining means is adapted to form a clamping boundary enclosing the accessible portion of the blank to be formed by the punch; the apparatus further comprises an arrangement of two separate draw forming tools, comprising: a separate aft re-draw forming tool comprising a first arcuate gripping plate and a second arcuate gripping plate formed for gripping a bent section of the trailing edge of the blank there between; and a leading edge re-draw tool.

2. The apparatus as claimed in claim 1, wherein the retaining means comprises a blank holder and a die for retaining the blank there between with alignable cutouts respectively for receiving the punch.

3. The apparatus as claimed in claim 1, wherein the leading edge re draw tool has a blank holder and a die for retaining the blank there between.

4. The apparatus as claimed in claim 1, wherein a gap is provided between the aft re-draw forming tool and leading edge re-draw tool for receiving a second punch.

5. The apparatus as claimed in claim 1, wherein the punch comes into contact with the blank for draw forming the blank across the punch to form a partially formed lip skin sector from the blank; and an interior gripping face of at least one of the first arcuate gripping plate and the second arcuate gripping plate comprises an arcuate groove formed therein and the arcuate groove is formed for receiving the bent section of a trimmed portion of the partially formed lip skin sector.

6. The apparatus as claimed in claim 1, wherein the punch comes into contact with the blank for draw forming the blank across the punch to form a partially formed lip skin sector from the blank; and the leading edge re-draw tool comprises a pair of cooperating gripping ring sectors provided for draw forming the partially formed lip skin sector from the leading edge to the inlet edge of the lip skin sector.

7. The apparatus as claimed claim 6, wherein one gripping ring sector of the pair of cooperating gripping ring sectors is an internal gripping ring sector having an external curved surface formed for engaging an internal surface of the partially formed lip skin sector.

8. The apparatus as claimed in claim 7, wherein the other gripping ring sector of the pair of cooperating gripping ring sectors is an external gripping ring sector having an internal curved surface formed for engaging an external surface of the partially formed lip skin sector.

9. The apparatus as claimed in claim 8, wherein the internal curved surface is formed for nesting engagement with an exterior curved surface of the internal gripping ring sector with clearance for the thickness of the partially formed lip skin sector.

10. The apparatus as claimed in claim 8, wherein the leading edge of the external gripping ring sector is radiused to allow the partially formed lip skin sector to flow through and around the leading edge during a redraw forming process.

11. The apparatus as claimed in claim 1, wherein the first arcuate gripping plate and the second arcuate gripping plate are configured to move in an axial direction for gripping the bent section of the trailing edge of the blank.

12. The apparatus as claimed in claim 1, wherein a gripping face of the first arcuate gripping plate and a gripping face of the second arcuate gripping plate face in an axial direction.

13. A method of forming a sector of an annular component, the method comprising the steps of: clamping at least part of a blank along a clamping boundary in a retaining means so as to leave a portion of the blank exposed within the clamping boundary; moving a punch and/or the retaining means radially so that the punch comes in to contact with the exposed portion of the blank and through a main body of the exposed portion of the blank thereby drawing the blank onto an external surface of the punch forming the sector from a leading edge of the sector to a trailing edge of the sector, thereby forming a partially formed lip skin sector; trimming a trailing portion of the partially formed lip skin sector, leaving a bent section at the trailing edge; placing the trimmed partially formed lip skin sector into a second draw forming tooling arrangement, the second draw forming tooling arrangement comprising a separate aft re-draw forming tool and a leading edge re-draw tool; clamping the bent section of the trimmed partially formed lip skin sector between a first arcuate gripping plate of the separate aft re-draw forming tool and a second arcuate gripping plate of the separate aft re-draw forming tool; and activating the second draw forming tooling arrangement for engaging the trimmed partially formed sector and drawing the trimmed partially formed sector over a second punch forming the sector from the leading edge to an inlet edge.

14. The method as claimed in claim 13, wherein the method further comprises applying a draw load between a blank holder and a die of the leading edge re-draw tool.

15. The method as claimed in claim 14, wherein the method further comprises: placing a draw load on the aft re-draw forming tool; and fixing a position of the two arcuate plates of the aft re-draw forming tool while applying the draw load to the blank holder and the die of the leading edge re-draw tool while the blank holder and the die of the leading edge re-draw tool are forced into the second punch by a predetermined draw distance under a predetermined gripping force load.

16. The method as claimed in claim 15, wherein the method further comprises applying a predetermined stretch load to the blank holder and the die of the leading edge re-draw tool once the predetermined draw distance has been reached for reducing or eliminating the draw of the trimmed partially formed lip skin sector between the blank holder and the die of the leading edge re-draw tool.

17. The method as claimed in claim 15, wherein the method further comprising placing a predetermined stretch load on the aft re-draw forming tool.

18. The method as claimed in claim 15, wherein the method further comprising: applying a predetermined stretch load to the blank holder and the die of the leading edge re-draw tool once the predetermined draw distance has been reached for reducing or eliminating the draw of the trimmed partially formed lip skin sector between the blank holder and the die of the leading edge re-draw tool; placing a predetermined stretch load on the aft re-draw forming tool; and simultaneously moving the two arcuate plates of the aft re-draw forming tool a predetermined stretch distance while the stretch load is applied to the blank holder and the die of the leading edge re-draw tool.

19. The method as claimed in claim 18, wherein the method comprising forming the blank under tension for a remainder of the stretch motion while the predetermined stretch load of the leading edge re-draw tool and the predetermined stretch load of the aft re-draw forming tool are maintained.

20. The method as claimed in claim 15, wherein the method further comprising: applying a predetermined stretch load to the blank holder and the die of the leading edge re-draw tool once the predetermined draw distance has been reached for reducing or eliminating the draw of the trimmed partially formed lip skin sector between the blank holder and the die of the leading edge re-draw tool; placing a predetermined stretch load on the aft re-draw forming tool; simultaneously moving the two arcuate plates of the aft re-draw forming tool a predetermined stretch distance while the stretch load is applied to the blank holder and the die of the leading edge re-draw tool; and removing the blank by retracting the die of the leading edge re-draw tool, and lifting an arcuate plat: of the two arcuate plates clear of the other arcuate plate of the two arcuate plates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures.

(2) FIG. 1 is a sectional perspective view of an extended inlet cowl of a nacelle for an aircraft engine;

(3) FIG. 2 is an exploded perspective view of an apparatus for forming a sector of a lip skin;

(4) FIG. 3 is a sectional perspective view of a punch sub-assembly for forming a sector of a lip skin;

(5) FIG. 4 is an exploded sectional perspective view of an apparatus for forming a sector of a lip skin;

(6) FIG. 5 is a vertical section view of an apparatus for forming a sector of a lip skin; FIGS. 5A to 5E 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;

(7) FIG. 5F is a perspective view of the blank after the forming process and prior to trimming;

(8) FIGS. 6A to 6E are perspective views of a sector of a frusto-conical blank at first to fifth stages respectively of the forming process;

(9) FIG. 6F is a perspective view of a formed sector of inlet cowl after the forming process;

(10) FIG. 7 is an exploded perspective view of a second embodiment of apparatus of the present disclosure;

(11) FIG. 8 is a section of the perspective view of FIG. 7;

(12) FIG. 9 is a detail section view of the punch assembly of FIGS. 7 and 8;

(13) FIG. 10 is an exploded detail view of a second embodiment of die plate and cooperating forming arrangement;

(14) FIG. 11 is a sectional elevation view of the second embodiment of apparatus;

(15) FIGS. 12A to 12E 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;

(16) FIGS. 13A to 13E are perspective views of a sector of a frusto-conical blank at first to fifth stages respectively of the forming process;

(17) FIG. 13F is a perspective view of a formed sector of inlet cowl after the forming process;

(18) FIG. 14 is an exploded perspective view of a third embodiment showing a first tool of a two tool apparatus;

(19) FIG. 15 is a section of the perspective view of FIG. 14;

(20) FIG. 16 is an exploded perspective view of the third embodiment showing a second tool of the two tool apparatus;

(21) FIG. 17 is a section of the perspective view of FIG. 16;

(22) FIGS. 18A to 18C 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;

(23) FIGS. 18D to 18F 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;

(24) FIG. 19 is an exploded perspective view of the fourth embodiment showing a second tool of the second arrangement of two tool apparatus;

(25) FIG. 20 is a section of the perspective view of FIG. 19;

(26) FIGS. 20A to 20C 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 second arrangement of two tool forming apparatus of the fourth embodiment; and

(27) FIGS. 20D to 20G 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 second arrangement of two tool forming apparatus of the fourth embodiment.

DETAILED DESCRIPTION

(28) Referring to the drawings and initially to FIGS. 1 to 5F, 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 center 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 minimizes wrinkling. The internal peripheral surface of the cutout 16 is rounded by a radius 14 to provide controlled material flow during the drawing operation.

(29) The re-draw ring sector 7 is movably mounted on the die plate 6 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 15 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.

(30) 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.

(31) 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 minimize the distortion along the edges of the part. The punch axial length is extended beyond the trailing edge to minimize 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 61. The blank 10 is a profiled sheet material.

(32) The processing steps are shown in FIGS. 5A to 5F and the corresponding changes in the blank shape are shown in FIGS. 6A to 6F. The blank 10 is placed between the blank holder 8 and die 6 before closing see FIGS. 5A and 6A. 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. 5B 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. 5B and 6B.

(33) Upon reaching the draw depth D Draw the blank holder 8 load is increased to FBH-Stretch see FIG. 5C 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. 5C. At this stage the inlet cowl profile from the leading edge 3 to the trailing edge 1 has been formed as shown in FIG. 6C.

(34) The blank 10 is then sheared along two axial lines see FIG. 6D 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. 6D 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. 5D) while the re-draw ring sector 7 is forced into the punch sub-assembly 9 by a distance ORR-Draw under a spring force load of F RR-Draw see FIG. 5D.

(35) 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. 5E, The blank 10 shape is then that shown in see FIG. 6E. 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. 6F. The blank 10 is then trimmed using either a manual or CNC cutting process see FIG. 6F.

(36) Referring to the drawings and now to FIGS. 7 to 13, 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 21 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. 13F of the annular component for draw forming this part of the blank.

(37) The die 26 has a die plate 34, see FIG. 11 and a support member 35 see FIG. 10 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 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.

(38) The shape of a cut out 46 in the center 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 minimizes 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. 12E indicate the radial and axial directions respectively.

(39) The processing steps are shown in FIGS. 12A to 12E and the corresponding changes in the blank shape are shown in FIGS. 13A to 13F. The blank 10 is placed between the blank holder 28 and die 26 before closing see FIGS. 12A and 13A. 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. 12B 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. 12B and 13B.

(40) Upon reaching the draw depth D Draw the blank holder load is increased to FBH-Stretch see FIG. 12C 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. 12C. At this stage the inlet cowl profile from the leading edge 3 to the trailing edge 1 has been formed as shown in FIG. 13C.

(41) The blank 10 is then sheared along two axial lines see FIG. 13D 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. 13D 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. 13D while the movable portion 27 of the die 26 is forced into the punch 32 by a distance ORR-Draw under a spring force load of F RR-Draw (see FIG. 12D).

(42) Once the distance ORR-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 ORR-Stretch while the forces FBH RR draw and FRR-Stretch are maintained see FIG. 12E. The blank 10 shape is then that shown in see FIG. 13E. 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. 13F. The blank 10 is then trimmed using either a manual or CNC cutting process see FIG. 13F.

(43) Referring to the drawings and now to FIGS. 14 to 18, 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. 7 to 13. 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. 18A to 18C and will be described in greater detail below. In view of the fact that a second tool is used as illustrated in FIGS. 16 and 17 and in FIGS. 18D to 18F, no cooperating forming arrangement is included in the first tool.

(44) The second tool illustrated in FIGS. 16 and 17 comprises a sector of a punch 65 formed for receiving the partially formed lip skin sector formed by the tool illustrated in FIGS. 14 and 15. 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.

(45) 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.

(46) The processing steps are shown in FIGS. 18A to 18F. 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. 18B 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. 18B.

(47) Upon reaching the draw depth D Draw the blank holder load is increased to FBH-Stretch see FIG. 18C 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. 18C. At this stage the inlet cowl profile from the leading edge 3 to the trailing edge 1 has been formed.

(48) 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. 18D 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. 13D while the gripping ring sectors 67, 68 are forced into the punch 65 by a distance ORR-Draw under gripping force load of F Grip RR-Draw see FIG. 18E.

(49) Once the distance ORR-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 ORR-Stretch while the forces FBH RR stretch and F Grip RR-Stretch are maintained see FIG. 18F. 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.

(50) Referring to the drawings and now to FIGS. 19 to 20:G, there is shown a fourth embodiment of apparatus for forming a lip skin sector. In the fourth embodiment, the apparatus has a separate aft re-draw forming tool 70, 73 and a leading edge re-draw tool 71, 72 having similar components to the components 67, 68 illustrated in FIGS. 16 and 17. The leading edge re-draw tool 71, 72 has blank holder 72 and die 71 for retaining a blank 94 there between. The aft re-draw forming tool 70, 73 has two arcuate plates 70, 73 formed for gripping the blank there between. A gap is provided between re-draw forming tool 70, 73 and leading edge re-draw tool 71, 72 for receiving punch 69. The function of the tool is clearly illustrated in FIGS. 20:C to 20:G and will be described in greater detail below. In view of the fact that a second tool is used as illustrated in FIGS. 19 and 20 and in FIGS. 20:D to 20:F, no additional cooperating forming arrangement is included.

(51) The fourth embodiment of apparatus illustrated in FIGS. 19 and 20 comprises a sector of a punch 69 formed for receiving the partially formed lip skin sector formed by the tool illustrated in FIGS. 14 and 15. The form of the arcuate leading edge of the punch 69 corresponds closely to the form of the leading edge of the punch 55 so as to neatly accommodate the partially formed lip skin sector. In use an operator removes the partially formed blank from the first tool after the blank has been formed as illustrated in FIGS. 20:A to 20:C. The trailing edge of this partially formed blank is trimmed leaving a first bent section bent at approximately 90 degrees relative to the trailing end of the partially formed annular sector A second shorter bent section is bent from the end of the first bent section of the trimmed portion, the second short bent section being bent back towards the leading edge of the partially formed lip skin sector. This trimmed partially formed lip skin sector is set onto the punch 69. The operator actuates a powered actuation system to bring the aft re-draw forming tool 70, 73 and the blank 94 into engagement with each other. The first and second bent sections of the trailing edge of the partially formed lip skin sector is located between the two arcuate plates 70, 73 and as the plates 70, 73 are closed together by a powered actuator the bent sections are clamped and gripped there between. An arcuate groove 95 is formed in one of the interior gripping faces of the arcuate gripping plates and this groove is formed for receiving the short bent section of the trimmed portion of the partially formed lip skin sector. This provides a secondary locking function between the bent sections of the tailing edge of the partially formed lipskin sector and the gripping plates 70, 73 to further enhance the gripping action of the arcuate gripping plates 70, 73.

(52) A leading edge re-draw tool 71, 72 in the form of a pair of cooperating gripping ring sectors 71, 72 are provided for draw forming the partially formed lip skin sector from the leading edge to the inlet edge of the lip skin sector. Gripping ring sector 72 is an internal gripping ring sector 72 having an external curved surface formed for engaging the internal surface of the partially formed lip skin sector 94. Gripping ring sector 71 is an external gripping ring sector 71 having an internal curved surface formed for engaging the external surface of the partially formed lip skin sector 94.

(53) Gripping ring sector 71 has an interior curved surface formed for nesting engagement with the exterior curved surface of the gripping ring sector 72 with clearance for the thickness of the partially formed lip skin sector 94. The operator actuates a powered actuation system to move the griping ring sector 72 into engagement with the partially formed lip skin sector 94 and then moves the gripping ring sector 71 into engagement with the partially formed lip skin sector 94. The leading edge of the gripping ring sector 71 is radiused to allow the partially formed lip skin sector 94 to flow through and around the leading edge during the redraw forming process.

(54) The processing steps are shown in FIGS. 20:A to 20F. The blank 94 is placed between the blank holder 52 and die 53 before closing, see FIGS. 14 and 15. 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 94 is then drawn over the punch 52 by a distance D Draw as shown in FIG. 20B while applying the force FBH-Draw. The blank 94 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. 20B.

(55) Upon reaching the draw depth D Draw the blank holder load is increased to FBH-Stretch see FIG. 20C while the blank 94 is stretched from all sides over the punch 52 by a distance D Stretch. The blank 94 has minimal draw from between the blank holder 52 and die 53 during the stretching process see FIG. 20C. At this stage the inlet cowl profile from the leading edge 3 to the trailing edge 1 has been formed.

(56) 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. 20:D and a load F Grip RR Draw is applied between blank holder 72 and die 71 of the leading edge re-draw tool 71, 72. A load F aftgrip-RR-Draw is placed on the aft re-draw forming tool 70, 73. The two arcuate plates 70, 73 of aft re-draw forming tool 70, 73 remain in the fixed position while the load FGrip-RR Draw is applied to the blank holder 72 and die 71 of the leading edge re-draw tool 71, 72 see FIG. 20:D while the blank holder 72 and die 71 of the leading edge re-draw tool 71, 72 are forced into the punch 69 by a distance ORR-Draw under gripping force load of F Grip RR-Draw see FIG. 20:E.

(57) Once the distance ORR-Draw has been reached a stretching load F Grip RR stretch is applied to the blank holder 72 and die 71 of the leading edge re-draw tool 71, 72 which then reduces or eliminates the draw of the blank 10 between blank holder 72 and die 71 of the leading edge re-draw tool 71, 72. A load F aftgrip-RR-stretch is placed on the aft re-draw forming tool 70, 73. The two arcuate plates 70, 73 of aft re-draw forming tool 70, 73 are simultaneously moved a distance D RR-Stretch while the load FGrip-RR Stretch is applied to the blank holder 72 and die 71 of the leading edge re-draw tool 71, 72 see FIG. 20:F. The blank 94 is then formed under tension for the remainder of the motion ORR-Stretch while the forces are maintained. The blank 10 is then removed by removing all holding forces, retracting the die 71 of the leading edge re-draw tool 71 and lifting the arcuate plate 70 clear of the arcuate plate 73. The blank 10 is then trimmed using either a manual or CNC cutting process.

(58) 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.

(59) 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.

(60) 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 utilized for realizing the invention in diverse forms thereof as defined in the appended claims.