COMPOSITE DISK FOR SUPPORTING FAN BLADES

Abstract: The composite support disc or ring (10) for a row of fan blades (62) in a bypass turbine engine is made up of plies of high strength fibers so oriented as to carry the loading developed on the ring (10) by the fan blades (62) and with the fan blades (62) mounted to minimize the loading on the composite disc (10). The orientation of the fibers are different in selected areas of the disc to provide a high strength disc (10) with a minimum weight.

Description: This invention relates to a composite disk or ring assembly for supporting the fan blades on a high bypass turbine engine particularly where the fan is mounted outside and surrounding the engine core. The invention also concerns a method of making the composite disk or ring assembly. These disks or rings have been made generally of a metal which is machined to provide the circumferentially spaced bearing mountings in which the individual fan blade roots are supported for turning movement in adjusting the pitch of the blades. These metallic rings as disclosed e. g. in US-A-4,021,142 are necessarily heavy in order to carry the loading thereon during the operation of the fan. It is well known that weight reduction is desirable wherever possible in a aircraft engine and if a composite support ring can be made strong enough to carry the loading on the blades a substantial weight reduction will result with an inevitable significant reduction in the total weight of the engine. Thus, there is provided in accordance with the invention a ring assembly for the support of a row of fan blades for a bypass turbine engine, the blades being turnable on a radial axis for pitch changing, characterized in that said ring assembly comprises a composite ring of layers or plies of fibers, substantially the outer half of the ring having the fibers of the plies thereof generally arranged at 0° to the circumferential direction of the ring, substantially the inner half of the ring having the fibers of a portion of the plies arranged at 0°, said portion of the plies alternating with the remaining plies, said remaining plies comprising in part plies having the fibers thereof at 45° and plies having the fibers thereof at 90 degrees with respect to the circumferential direction of the ring, with additional plies of fibers arranged generally on the side surfaces of the ring and on the inner and outer surfaces and extending beyond the ring to form mounting flanges for the ring, said additional plies having the fibers thereof generally at substantially 45° to the circumferential direction of the ring, said composite ring having radial holes formed therein for the fan blades, and mounting bosses positioned in said holes to receive the blade roots. The method of making the ring assembly is characterized by wrapping the plies making up the inner and outer half of the ring about a support drum, curing the wrapped plies making up the inner and outer half of the ring under heat and pressure, machining the radial openings and the annular groove in the cured ring, applying the additional plies to the side surface and to the inner and outer surfaces of the ring and thereafter curing the additional plies. Advantageous features of the ring assembly are recited in the dependent claims 2 through 7. The foregoing and other features and advantages of the present invention will become more apparent from the following description of preferred embodiments and accompanying drawings, wherein: Fig. 1 is a sectional view of a completed ring assembly showing the blade root positioned therein and the mounting of the ring within the engine. Fig. 2 is a transverse sectional view of the portion of the ring. Fig. 3 is a view looking in the direction of the arrow 3 of Fig. 2 to show the position of the flanges on the support bosses. Fig. 4 is a sectional view of the ring structure before being machined. Fig. 5 is a sectional view of the ring after being machined. Fig. 6 is a sectional view of the ring after the additional plies have been added to the surfaces of the basic ring. As shown in Fig. 1, the ring 10, made of composite material, as will be described later, has the additional plies of fibers 12 on the inner surface 14 and other plies of fibers 16 on the portion of the outer surface 18 to the left of the groove 19 and on one side surface 20. The fibers 16 overlap with the plies of fibers 12 to form a flange 24 having an outwardly turned edge to form a radial flange 26 for attachment to a driving ring 27. At the other end of the ring there are additional plies 28 extending generally radially on the other side surface 30 of the basic ring and projecting radially inward of the ring to overlap with the mating portion 32 of the plies 12 to form the flange 34 for attachment to a support structure 36. Additional plies of fibers 38 on the portion of the outer surface 18 to the right of the groove 19 and extending radially inward therefrom abut against the radial plies 28. At their inner portion these plies form a part of the flange 34. From this set of plies of fibers 38 annular flanges 40 and 42 are formed to serve as sealing flanges cooperating with fixed seals 44 and 46. The ring 10 has radial holes or openings 48 formed therein to receive mounting bosses 50 each of which has a groove 51 in its inner surface to receive a row of ball bearings. Each boss has a flange 54 at its inner end and this flange is generally square to provide corners to receive bolts 56 therethrough which extend into the composite ring and hold the bosses in position thereon. Suitable spacers 58 are provided to fill the space between the flat flange and the cooperating curved inner surface of the ring to distribute the load on the boss over an extended portion of the ring. The ring also has the annular groove 19, above referred to, in its outer surface 18. This groove intersects the holes 48 and exposes the outer ends of the bosses 50. The surface 18 is in fact two spaced apart distinct surfaces on opposite sides of the annular groove as mentioned earlier. The fan blade 62 has a root 64 with an annular groove 66 thereon positioned in the supporting boss with the bearings 52 engaging said groove 66 as shown. The balls are trapped in position by a split clamping ring 68 engaging the outer end of the boss and shoulder 70 on the fan blade root 64 and this arrangement serves to hold the blade root securely in position. The ring assembly as above described is supported for rotation in surrounding relation to the engine structure by the support structure 36 extending generally inwardly from the attachment flange 34 and attached thereto. The end 73 of the support structure 36 opposite the flange 34 is mounted in a bearing 74 carried by a fixed support structure 76 integral with the surrounding engine casing. The blade root has an eccentrically projecting arm 78 at its inner end to provide for the attachment of a pitch control mechanism. In making the ring 10 the composite structure is built up of layers of plies of high strength fiber generally wrapped around a support drum. Substantially the inner half 10a of the composite ring is made up of about 40% of plies of fibers of graphite filaments arranged at 0° alternating with about 30% of 45° of fiberglass fibers arranged in plies and 30% of 90° fiberglass fibers also arranged in plies. The 0° means parallel to the circumferential direction and obviously 90° means the plies are parallel to the longitudinal axis of the ring. Similarly 45° fibers means at an angle midway between 0° and 90°. When this portion of the ring is completed the remaining outer half 10b of the ring is built up of wrapped layers of plies of graphite fibers all generally at 0° for circumferential strength and stiffness in the completed ring. This particular percentage of fibers is characteristic of one specific ring and variations may be utilized depending on the strength desired in certain different portions of the ring. However this particular arrangement has been found to be effective for one particular installation. After the plies of the ring have all been assembled the complete assemblage is cured by the usual curing procedures utilizing heat and pressure. The plies may have been pre-pregnated with a matrix material or the matrix material may be added at the start of the curing process. Either of these procedures is well known in the art and the techniques for completing the curing process in either event is also well known. The curing of this basic ring having been completed the several radial openings 48 are machined and the annular groove 19 is also machined to provide the partially completed structure of Fig. 5. It will be noted that the base of the groove 19 is close to the division between the outer 0° plies and the inner composite of different plies. After the ring has been machined the surrounding plies 12 on the inner surface and the plies 16 on the outer surface are positioned. The surface 18 is now two spaced surfaces 18 by reason of the intervening groove 19 and the plies do not extend over this groove. These plies are generally fiberglass and at 45° so that they may be shaped to conform to the outer surface 18 and the side surface 20 of the ring and also to form the flange 26. Also the plies 28 are mounted at the other side surface 30 of the ring and these plies are also generally fiberglass and with a 45° arrangement of the fibers. The other plies 38 are also added and shaped as above described to form the necessary flanges as shown in Fig. 1. After these plies have all been added and in the shape shown in the finished product the ring is again subjected to a curing to harden these additional plies and to form a completed ring or disk construction in which these added plies will be integral with and therefore essentially a part of the basic ring. It is understood that the manner and sequence of assembling the plies may be altered to satisfy individual manufacturing and production capabilities. Thereafter the bosses are mounted with the spacers 58 and the assemblage is then ready for the attachment of the fan blades. Since the assembly of these fan blades is not an essential part of the present invention it will not be described.

Claims: Ring assembly for the support of a row of fan blades for a bypass turbine engine, the blades being turnable on a radial axis for pitch changing, characterized in that said ring assembly comprises a composite ring of layers or plies of fibers, substantially the outer half (10b) of the ring (10) having the fibers of the plies thereof generally arranged at 0° to the circumferential direction of the ring (10), substantially the inner half (10a) of the ring (10) having the fibers of a portion of the plies arranged at 0°, said portion of the plies alternating with the remaining plies, said remaining plies comprising in part plies having the fibers thereof at 45° and plies having the fibers thereof at 90 degrees with respect to the circumferential direction of the ring (10), with additional plies of fibers (12,16,28,38) arranged generally on the side surfaces (20,30) of the ring (10) and on the inner and outer surfaces (14,18) and extending beyond the ring (10) to form mounting flanges (26, 34) for the ring (10), said additional plies (12,16,28,38) having the fibers thereof generally at substantially 45° to the circumferential direction of the ring (10), said composite ring (10) having radial holes (48) formed therein for the fan blades (62), and mounting bosses (50) positioned in said holes (48) to receive the blade roots (64). Ring assembly according to claim 1, characterized in that the fibers in the outer half (10b) are generally of graphite and a substantial part of the fibers in the inner half (10a) of the ring (10) are fiberglass. Ring assembly according to claim 2, characterized in that the fibers of the additional plies (12,16,28,38) are generally fiberglass. Ring assembly according to claim 1, characterized in that the mounting bosses (50) are flanged and with the flanges (54) at the inner side of the ring (10) and with bolts (56) securing the bosses (50) to the ring (10). Ring assembly according to claim 1, characterized in that a portion of the additional plies (38) are shaped to form seal flanges (40, 42) on the ring (10). Ring assembly according to claim 1, characterized in that the radial holes (48) in the ring (10) extend through the inner half (10a) of the ring (10) and intersect with an annular groove (19) extending radially inward from the outer surface (18) of the ring (10) to intersect said radial holes (48). Ring assembly according to claim 1, characterized in that the inner half (10a) of the ring (10) has the fibers of about 40 % of the plies arranged at 0°, the fibers of about 30% of the plies at 45° and the fibers of the remaining 30 % of the plies at 90 degrees with respect to the circumferential direction of the ring (10). Method of making the ring assembly of claim 1, characterized by: wrapping the plies making up the inner and outer half (10a,10b) of the ring (10) about a support drum, curing the wrapped plies making up the inner and outer half (10a,10b) of the ring (10) under heat and pressure, machining the radial openings (48) and the annular groove (19) in the cured ring, applying the additional plies (12,16,28,38) to the side surface (20,30) and to the inner and outer surfaces (14,18) of the ring (10) and thereafter curing the additional plies (12,16,28,38).

Inventors: DENNISON, WILLIAM T.
Applicants: UNITED TECHNOLOGIES CORPORATION
Application year: 1988
Main classification: F01D5
IPC codes: F02C7, F16C35, F01D5, F01D7, B32B5