FR2485659A1 - COMPOSITE METAL SHAFT AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

SHAFT IN COMPOSITE METAL WITH A SPECIFIC HIGH MODULE, AND PROCESS FOR ITS MANUFACTURING. AN EXTERIOR METAL TUBE 2 TRANSMITS TORQUE AND A COMPOSITE SLEEVE 3 IN METAL AND HIGH MODULAR FILAMENTS IS BOUNDED TO THE INTERIOR SURFACE OF THE TUBE. THE COMPOSITE SLEEVE IS MANUFACTURED AND BONDED TO THE TUBE BY WINDING A COMPOSITE TAPE ON A CHUCK WITH THE FILAMENTS BEING AXIALLY ALIGNED. THE CHUCK IS THEN INSERTED INTO THE TUBE. THE ASSEMBLY IS CLOSED AND VACUUMED, THEN THE CHUCK IS AT A PRESSURE AND A SUFFICIENT TEMPERATURE TO OBTAIN THE BINDING BY DIFFUSION AND THE CONSOLIDATION OF THE COMPOSITE SHEET PROPERLY, AS WELL AS THIS SHEET TO THE INTERIOR SURFACE OF THE TREE. THE INVENTION APPLIES PARTICULARLY TO THE MAIN SHAFTS OF A GAS TURBINE.

Description

The present invention relates to a composite metal shaft and to a

  process for its manufacture; it aims, more particularly, a tree of this type for

gas turbine.

  There is a consistent trend in gAaz turbine technology for the production of larger motors.

  small and of best performance, with a special power

  increased. These changes inevitably lead to higher speeds and fatigue levels for the main engine components. An output tree of

  engine power is an important example of this

  The combination of greater rotor speed and smaller shaft diameter results in critical speed difficulties. One solution is to reduce the effective length of the tree, by adding

  additional bearings. This results in complexities

  increased caniques, to realize and assemble a smaller engine. A simpler and more practical solution to this problem is to produce trees with a higher ratio of the modulus to the specific weight, which gives a specific rigidity and speed.

higher criticism.

  The subject of the invention is a composite composite tree

  which is capable of withstanding the torsional and bending stresses that occur in a small diameter drive shaft for a gas turbine engine.

  The composite shaft, according to the invention, of mo-.

  high specific dule, is characterized in that it com--

  takes a tubular sheath made of machinable material, with high

  resistance to torsion, in which is inserted axially

  a metal matrix containing filaments, aligned with

  xially, of a high-modulus material. The sheet is completely integrated and bonded to the inner surface of

the tubular sheath.

  The process according to the invention for the manufacture

  cation of such a composite shaft is to manufacture an outer tubular sheath, machinable material with high torsion strength, having an axial inner passage; fabricating a matrix of metal strip in which filaments of high modulus material arranged longitudinally are embedded; rolling this matrix on a mandrel, the high modulus filaments being oriented in the axial direction; insert the die and mandrel into the axial passage, in close contact with the surface

  inside the tubular sheath; and submit this set

  ble at a sufficient temperature and pressure to achieve consolidation and diffusion bonding of the filament-reinforced

outer tubular sheath.

  In a preferred embodiment, but not

  In the first place, an outer tubular shaft is

  steel. Then boron filaments are carefully

  placed between two thin aluminum foils to form an aluminum foil containing internally

  longitudinally oriented boron filaments. The sheet

  the boron-aluminum is rolled on a mild steel mandrel and inserted into the tubular steel shaft, the filaments

  being aligned axially. The whole is placed in a

  toclave which is first brought to a pressure of 0.5 to 0.7 kg / cm 2, heated to 515 C and then subjected to a higher pressure of 14 kg / cm 2, for 30 minutes.Ce method allows to obtain a perfectly consolidated composite shaft comprising a steel outer shell and an inner sleeve of aluminum reinforced with boron filaments axially aligned so as to improve the bending rigidity. The invention will be better understood in the light of

  the description of its nonlimiting embodiment,

  shown in the accompanying drawings.

  Fig. 1 is a perspective view of an extreme

  a tree according to the invention, and

  Fig. 2 is a section along a longitudinal plane

passing through the axis of the tree.

  A finished shaft 1, made in accordance with the present invention, is shown in FIGS. 1 and 20. It comprises an outer tubular casing 2 of hardened steel having treated ribs 6, to which is

  linked, on its inner periphery, a high layer 3 -

  specific module. Layer 3, as we see, on the

  FIG. 2, consists of an aluminum matrix,

  consolidated, in which drowned

  4 layers of boron, substantially aligned with the axis 5. The layer 3 is formed of an aluminum ribbon matrix 0.18 mm thick inside which are interposed 0 boron filaments, 16 mm. It is also possible to use a titanium ribbon but, in this case, it is necessary to use carbide-coated boron filaments.

  silicon or boron carbide to avoid interac-

between titanium and boron.

  The layer 3 is rolled on a steel mandrel

  soft and it is inserted into the tubular shaft 2 in

  cer. This set is then placed in an autoclave,

  in which the pressure is then

  their intermediate of 5 to 7 kg / cm2. We then raise the temperature

  at 515 C, which increases the ductility of the

  che 3 and its mandrel and facilitates the initial phases of the link. The next step is to increase the pressure to 14 kg / cm and maintain this value for about half an hour to allow complete consolidation. The mandrel is then removed by a process

chemical removal.

  The turbine shaft 2 can be constructed of steel or titanium, to obtain the torsional strength of the composite shaft. Typically, the shaft 1 may comprise an outer sheath of steel or titanium

  having an outer diameter of 25.4 mm and a diameter of

  15.9 mm thick, with a 1.8 mm thick boron-aluminum layer 3 bonded to the inner surface of the sheath

in steel.

  In this way, a composite tree with a high specific modulus is obtained which makes it possible to achieve a

  higher critical speed. Since external surf-ace

  re is steel, it can be machined or welded, following

needs.

  To avoid the use of an autoclave, the entire shaft and mandrel can be sealed and evacuated. Pressure can then be exerted by an internal axial passage inside the mandrel. By

  put under pressure at high temperature, we obtain the

  solidification and diffusion bonding of the matrix ribbon

  himself, as well as ribbon to the tree.

  It is understood that modifications of detail may be made in the form and construction of the device according to the invention, without departing from the scope thereof.

Claims (12)

claims   1. Composite shaft for gas turbine engine, having   a specific high module, characterized in that it com-   takes: an outer tubular sheath (2) of usie material   nable, with high torsion resistance, having a   wise axial interior; and an inner sheet (3) consisting of a metal matrix containing axially aligned filaments (4) of a high modulus material,   this sheet being completely integrated and linked to the over-   inner face of the tubular sheath.   2. Shaft according to claim 1, characterized in that   that the tubular sheath is steel.   3. Shaft according to claim 1, characterized in   the tubular sheath is made of titanium.   4. Shaft according to one of claims 1 to 3, characterized   characterized in that the metal matrix is aluminum.   5. Shaft according to any one of the claims   1 to 3, characterized in that the metal matrix is titanium.   6. Shaft according to any one of the claims   1 to 5, characterized in that the high modulus material is boron.   7. A method of manufacturing a composite shaft for gas turbine engine, having a high specific module, characterized in that it consists in: manufacturing a sheath   outer tubular, machinable material with high resistance   torsion resistance, having an axial inner passage; manufacturing a metal strip matrix in which are embedded high modulus material filaments arranged longitudinally; roll this matrix on a mandrel,   the high modulus filaments being oriented in the direction   axial; insert the die and the mandrel into the pas-   axial wise, in close contact with the inner surface of the tubular sheath; and subject this set to a temperature and pressure sufficient to obtain the   consolidation and the diffusion link of the   in the tufted sheath, reinforced by the filaments outer bungee.   8. Process according to claim 7, characterized in that the consolidation is obtained by: introducing the assembly into an autoclave; raising the pressure in the autoclave to an intermediate value; increase   from the temperature in the autoclave to a value that increases   the ductility of the mandrel and the sheet and   get the link; and further pressure rise in the autoclave to promote bonding and consolidation,   this pressure being maintained until these processes sus are completed.   9. A process according to claim 7 or 8, characterized   in that the outer tubular sheath is made of steel.   10. A process according to claim 7 or 8,   characterized in that the outer tubular sheath is made of titanium.   11. Process according to any one of the claims   7 to 10, characterized in that the metal strip of the matrix is obtained by interposition of longitudinally aligned filaments between two thin metal films.   Process according to any one of the claims   7 to 11, characterized in that the metal matrix is aluminum.   13. The method of claim 12, characterized   in that the high modulus filaments are boron. *30