DE102015102438B4 - Process for the production of fiber composite hollow bodies with flanges and winding core for carrying out the process - Google Patents

Abstract

Method for producing a hollow body having a flange structure made of fiber composite material using a cylindrical winding core (2) which determines the inner contour of the hollow body, comprising at least one winding pin which can be moved radially out of the winding core (2) kinematically on each circular arc in the end section ( 8.1, 8.2), wherein the longitudinal axis of the winding pins (8.1, 8.2) is tilted during removal in such a way that it is tangent to the respective arc, comprising the following steps: - winding fiber layers (11.1, 11.2) of reinforcing fibers on the winding core (2), wherein for each fiber layer (11.1, 11.2) a separate circumferential ring of extractable winding pins (8.1, 8.2) is used; - Fixing the wound fiber layers (11.1, 11.2) on the winding core (2) in the bending region of the flange with a holding tool (4), wherein the holding tool (4) annular over the entire circumference on the lateral surface of the winding core (2) radially from the outside in Direction of the central axis of the winding core (2) presses; - Leading out all winding pins (8.1, 8.2) of a ring on a separately for each winding pin (8.1, 8.2) fixed circular arc with a central angle of about 90 °, the circular arc in a through the central axis of the winding core (2) extending circular arc level which intersects the lateral surface at the position of the respective winding pin (8.1, 8.2), and the center of the circular arc lies on the lateral surface in the intersection of the circumferential circle contacted by the holding tool (4) with the circular arc plane, each winding pin (8.1, 8.2) is led away radially from the lateral surface of the winding core (2); - radially opening the holding tool (4) in such a way that the pressure exerted by the holding tool (4) on the wound fiber layers (11.1, 11.2) contact pressure drops to zero and between the holding tool (4) and the outermost fiber layer (11.2) around the Circumference of the fiber layer (11.2) circumferential gap of a thickness is formed, which corresponds to the thickness of a Flanschverstärkungselementes (10); ...

Description

The invention relates to a method and a winding core for the production of special, designed according to their function fiber composite hollow bodies with one or more flanges in fiber composite construction. The method is particularly suitable for the production of lightweight components that are exposed to high loads, such as a casing or a bypass for aircraft engines.

In aerospace, the production of housing structures in lightweight construction is becoming increasingly important. The production of individual components made of fiber composite materials, such as carbon fiber reinforced plastic (CFRP), is now part of the prior art.

Fiber composite components are manufactured according to various manufacturing processes of the winding or laminating technique. Known in the winding process fibers in the form of fiber bundles, usually deposited after impregnation with the matrix material under a defined thread prestressing on a rotating, component-adequate core in several layers, wherein circumferential windings or windings are created at a winding angle Ω in relation to the axis of rotation of the body ( DE 10 2010 005 987 B4 ).

The production of housing structures made of fiber composites, such. As CFK, glass fibers or other fibers, with outwardly shaped flanges is a major challenge. In the area of the flanges, both the wall thickness - due to the bending moments and the holes for attachment (usually gland) caused structural weakness - increased in an adapted manner will be ensured as well as an ordered fiber profile.

In a known manner structures or housing for aviation in the so-called prepreg technique are made of sheet goods. In prepreg technology, cut fiber webs, fleeces or mats are placed on a tool. Housing or hollow body, which are produced by means of prepreg technology, offer the possibility of designing and manufacturing the wall thickness of the body to be produced in accordance with the loads occurring, in particular in the region of a flange. For this purpose, flat prepreg fabric layers in individual segments, eg. B. six 60 ° segments, placed on the tool and bent in the region of the flange. The additional wall thickness required on the flange is achieved by applying additional layers of fabric.

However, this production technique has the disadvantage that a hollow body produced by this technique has at least one joint in each fabric layer of its layer structure at which the individual fibers are not connected to one another in a force-locking manner. Consequently, the body requires additional layers of fiber material to compensate for the disadvantage of non-existing adhesion in the individual layers. Accordingly, a plurality of individual layers is necessary, whereby both the effort to produce the body increases and the body increases in mass.

In addition, it is only partially possible with prepreg technology to ensure optimized fiber orientation for forces occurring, for example, at flanges. Available prepreg semi-finished materials have z. B. only tissue orientations of 0 ° or 90 °.

A method for producing a hollow shaft with an integral flange made of fiber composite is in DE 10 2008 028 337 B4 described. Here, a plurality of intersecting windings of fiber material is applied to a core wherein the core for each flange has a radial expansion ring with an axial abutment surface for specifying the shape of an end wall of a flange over an outer peripheral portion of the spreader set windings - after solving the fixation of the wound fiber material - drawn by a scraper from the outer peripheral portion of the spreader ring and pressed against the axial abutment surface thereof to form a portion of a flange. A similar method, in which, however, the expansion ring is pressed under expansion of the winding against the end face of a force applied to the winding core mold is in DE 4 005 771 C1 described.

It is also known to use tape-laying robots. These robots have pressure rollers with which individual tapes are placed and pressed at the desired position on the fiber composite semi-finished product. As a tape, for example, a unidirectional prepreg or tissue is referred to.

A disadvantage in the production of flanges with these placement robots is that the pressure rollers can not mold the individual tapes in the corners of the flange. Therefore, after being deposited as a cylindrical structure, a clinching operation is performed to form the flange. In addition, these robots require a high capital expenditure.

Another disadvantage of the known prior art method is that when bending the fiber composites to a flange usually wrinkling occurs. Since the scope of the Outside edge of the flange is greater than the circumference at the inner edge, the fabric pattern must be distorted and thus have different wall thicknesses. In addition, misregistration in terms of tissue orientation and overlap errors are possible especially at the prepreg joints.

The invention has for its object to avoid the disadvantages mentioned above, such as waviness, wrinkles or a disordered fiber flow, as far as possible so that fiber composite hollow body with a flange design reproducible and with adapted Wandstärkeverlauf with minimal structural weight and low production costs can be realized.

The solution of this object is achieved by a method according to the main claim 1 and a winding core according to claim 6. Expedient embodiments of the invention are in the subclaims.

According to the invention there is provided a method of manufacturing a hollow fiber composite body which, in a prior art fiber deposition process on the mandrel embodying the invention, including kinematics, enables the formation of the flange prior to the resin injection process, wherein for wall reinforcement in the Flange areas of the hollow body additional, preformed Flanschverstärkungselemente, preferably made of fiber composite material can be integrated.

The winding core according to the invention has a cylindrical shape, wherein in one or both end regions of the cylinder winding pins are arranged in a ring shape on the lateral surface around the entire circumference. Preferably, the winding core in the respective end region on a plurality of spaced apart in the axial direction of the winding core rings of winding pins.

The winding pins are connected to a kinematics, which makes it possible to lift the winding pins radially from the hub, the winding pins follow a circular arc and at the same time to the central angle of the circular arc, which can be up to 90 °, rotated. The rotation takes place around a rotation axis which is defined separately for each winding pin. This axis of rotation is arranged perpendicular to the central axis of the winding core and tangential to the lateral surface of the cylindrical winding core at a position which is displaced with respect to the position of the winding pin on the lateral surface in the axial direction towards the center of the cylinder.

The winding core can be hollow, at least in the respective end region in which the removable winding pins are arranged, in order to receive the kinematics for leading out the winding pins.

For example, such a kinematics by parallel to the central axis of the cylindrical winding core on the lateral surface (wherein the lever is advantageously embedded in the jacket) or arranged on a circle between the central axis and lateral surface lever be realized whose first end on the winding core with a on the Enclosed surface or the circle arranged axis is fixed, which is perpendicular to the longitudinal axis of the lever (or central axis of the cylindrical winding core) and tangential to the lateral surface or the circle at the position at which the lever is fixed by means of the axis of the winding core, wherein the second end region of each lever a winding pin whose longitudinal axis is perpendicular to the lateral surface of the cylindrical winding core (and thus also perpendicular to the longitudinal axis of the lever). By rotation of the lever about its axis, the winding pin disposed on the lever can be lifted radially from the cylindrical winding core, wherein the winding pin is simultaneously rotated about the lever axis.

The Ausführ- and rotating mechanism can be realized in other ways, for example, by radially emerging from the winding core, circular arc-shaped brackets of the winding pins.

The method according to the invention for producing a hollow body with a flange structure made of fiber composite material comprises the following method steps:
Winding of one or more, superposed fiber layers of reinforcing fibers - without prior impregnation with the matrix material - on the cylindrical winding core with kinematically herausführbaren winding pins. Preferably, at least two fiber layers are deposited one above the other on the winding core, wherein for each fiber layer a separate circumferential ring of removable winding pins is used on the winding core.

Fixing the wound fiber layers on the winding core in the bending region of the flange with a holding tool, wherein the holding tool annularly over the entire circumference on the lateral surface of the winding core presses radially from the outside towards the central axis of the winding core. The (preferably ring-shaped) holding tool presses on the fiber layers at the position of the (real or virtual) axes of rotation for the winding pins in such a way that the winding pins are still freely herausführ- and rotatable.

Subsequently, the kinematically herausführbaren winding pins of at least one ring are rotated by 90 ° (ie, a circular arc out of the winding core led out), wherein the local axis of rotation for each winding pin at the position on the Jacket surface is arranged, on which the holding tool presses against the fiber layers. In this case, the respective fiber layer wound around the lead-out winding pins maintains its bias.

Now, one or more Flanschverstärkungselemente, preferably made of fiber composite material, draped in the flange portion of the hollow body, wherein the Flanschverstärkungselement is draped over the entire circumference. Preferably, the flange reinforcement element is in one piece. Before draping, the holding tool is easily lifted off the fiber layer, i. H. the diameter of the ring formed by the holding tool is, for example, expanded by a few millimeters, so that the Flanschverstärkungselement can be pushed into the resulting gap. The flange reinforcement element may then be draped onto the outwardly facing surface of the fibrous layer between the holding tool and the fibrous layer. Alternatively, it can also be draped onto the inwardly facing surface of the fiber layer between the winding core and the winding body.

It is also possible to drape a plurality of flange reinforcement elements in a flange region of the hollow body, for example a first on the outwardly facing surface of the (outermost) fiber layer and a second between (innermost) fiber layer and winding core.

In the case of more than one deposited fiber layer or more than one ring of winding spins, the flange region of the outer fiber layer relative to the winding core can first be folded over and then a flange reinforcement element can be draped between the outer and the fiber layer arranged immediately below. Thereafter, the flange portion of the arranged immediately below the outer fiber layer of fiber layer is folded and possibly draped under this fiber layer, a Flanschverstärkungselement, wherein the holding tool is possibly opened a little further to obtain a sufficiently large gap for draping the Flanschverstärkungselementes. In this way, a flange reinforcing element can be draped between each two fiber layers.

After draping, the hollow body is consolidated with the flange-form, unthreaded flange reinforcement members by bonding or local bonding or sewing using a known special sewing technique for sewing.

Subsequently, the holding tool is removed and the consolidated, d. H. solidified, hollow body removed from the winding core. Now follows the Harzinjektionsprozess, wherein the hollow body, for example, placed in a mold and impregnated with synthetic resin.

Finally, any remaining winding pins in the flange area are removed, for example by cutting, and the final shape of the flange is finalized by a shaping manufacturing process. The term "forming manufacturing process" here implies, for example, cutting and removal technology. The finalizing can thus, for example, an introduction of the flange holes or a milling of the flange, so he z. B. has the form of a gear include.

The advantage of the method according to the invention is that the reinforcing fiber strands have an ordered orientation in the flange region, ie. H. They are aligned according to the loads occurring in the flange area. The draping of the flange reinforcement members is integrated into the fiber deposition process with the fiber composite flange reinforcement members dry (i.e., the plastic matrix not yet applied) draped. Thus, both the coiled fiber layers without wrinkling and / or distortions can be deformed into the flange shape as well as drape the flange reinforcement element well and adjust according to the desired shape, which also prevents a possible misfeed. In addition, a flange reinforcing member may be provided on the outer periphery (ie, on the outer side of the hollow body in the corresponding portion of the hollow body provided as a flange), the inner periphery (ie, on the inner side of the hollow body in the corresponding portion of the hollow body provided as a flange is) and / or arranged between two fiber layers.

The reinforcing fiber strands used for the production of the hollow body can be advantageously reduced, d. h., They are coated with a thermoplastic adhesive which is powdery at room temperature and at elevated temperatures, depending on the material between 150 ° C to 350 ° C, liquefied and fixed after cooling the reinforcing fiber strands in their position. As a result, after the draping of all flange reinforcement elements, the hollow body can be tempered, whereby it is consolidated in its shape.

An embodiment variant of the method according to the invention provides that the flange reinforcement elements are fixed in their position relative to the wound fiber layers with bolts which are inserted through positioning bores introduced into the flange reinforcement element. Preferably, the positioning holes are arranged in a region (the flange structure), the is removed by the final molding manufacturing process.

The process according to the invention and a fiber composite hollow body with flange produced by this process will be described in the following with reference to two figures in schematic representation. It shows in cross section:

1 the end region of a winding core with removable winding pins in the course of the method steps of the production method according to the invention;

2 : An engine-made bypass for an aircraft engine.

1 clarifies the procedure of the procedure. In the first method step A is applied to the winding core 2 which has two wreaths of winding pins 8.1 and 8.2 using the first ring of winding pins 8.1 the first layer 11.1 made of reinforcing fibers. In the subsequent process step B is on this first fiber layer 11.1 the second layer 11.2 wound from reinforcing fibers, wherein the winding pins 8.2 be used of the second wreath. After this step, therefore, two layers of reinforcing fibers are on the winding core 2 wrapped, with the first layer 11.1 under the second layer 11.2 ie between winding core 2 and second layer 11.2 , is arranged.

Now, in method step C, the holding tool 4 from the outside over the entire circumference on the outer wound layer 11.2 pressed, causing the two wound layers 11.1 and 11.2 be pressed on a circumferential line on the winding core. Then the winding pins 8.2 , which for the winding of the outer fiber layer 11.2 used with a kinematics in the manner of 90 ° around the holding tool 4 as a rotation axis of the lateral surface of the winding core 2 led away that outer layer 11.2 a radially from the lateral surface of the winding tool 2 protruding ring forms, the layer 11.2 from the holding tool 4 and the winding pins 8.2 is held under constant bias.

After this process step C, a flange reinforcing element 10 as in process step D1 on the left side of FIG 1 shown between the two layers 11.1 and 11.2 draped. This is the holding tool 4 opened by a few millimeters, ie from the central axis of the winding core 2 moved radially outward. After draping the flange reinforcement element 10 becomes the first fiber layer 11.1 in an analogous way, as before with the layer 11.2 done by means of kinematically moving winding pins 8.1 in the manner radially of the lateral surface of the winding core 2 led away that through the outer fiber layer 11.2 and the draped flange reinforcement 10 formed, radially projecting ring on the lateral surface of the winding core 2 by the position of the fiber layer 11.1 is reinforced, wherein the Flanschverstärkungselement 10 and the two fiber layers 11.1 and 11.2 form a sandwich structure (process step E1).

After method step C, the first fiber layer may also be first 11.1 in an analogous way, as before with the layer 11.2 done by means of kinematically moving winding pins 8.1 from the lateral surface of the winding core 2 be guided away, so that they are the already bent fiber layer 11.2 contacted (step D2). In the subsequent process step E2 then the Flanschverstärkungselement 10 outside on the lateral surface of the fiber layer 11.2 draped by placing it between the holding tool opened by a few millimeters 4 and the fiber layer 11.2 is pushed.

The reinforcing fiber strands of the two fiber layers 11.1 and 11.2 and the flange reinforcing member 10 are reduced. Heating the hub 2 with the fiber layers arranged thereon 11.1 and 11.2 leads to a consolidation of the fiber layers 11.1 and 11.2 so that the fiber composite hollow body in its fixed form from the winding core 2 can be taken down.

2 shows a cross section through the bypass 12 an aircraft engine, which was produced by the method according to the invention. On the left side of 2 is the flange reinforcement element 10 to see that between two fiber layers 11.1 and 11.2 of the bypass 12 was applied. But it can also be like on the right side of 2 shown, the flange reinforcement element 10 not just between two structural layers 11.1 and 11.2 of the bypass 12 , but also (another flange reinforcement element 10 ) on the outside of the bypass 12 be applied.

The flange holes 9 were after resin injection into the finished flanges of the bypass 12 brought in.

LIST OF REFERENCE NUMBERS

2

winding core

4

holding tool

8.1

Winding pin (first wreath on winding core)

8.2

Winding pin (second ring on winding core)

9

Flange

10

Flanschverstärkungselement

11.1

 Fiber layer (inside)

11.2

 Fiber layer (outside)

12

Housing / Bypass

A

step

B

step

C

step

D1

step

D2

step

E1

step

E2

step

Claims (7)

Process for the production of a hollow body with flange structure made of fiber composite material using a cylindrical winding core determining the inner contour of the hollow body (US Pat. 2 ), comprising at least one in the end portion on the circumferential surface encircling ring of kinematically on a respective arc radially from the winding core ( 2 ) removable winding pins ( 8.1 . 8.2 ), wherein the longitudinal axis of the winding pins ( 8.1 . 8.2 ) is tipped on removal in such a way that it is tangent to the respective circular arc, comprising the following steps: - winding fiber layers ( 11.1 . 11.2 ) of reinforcing fibers on the winding core ( 2 ), where for each fiber layer ( 11.1 . 11.2 ) a separate wraparound ring of removable winding pins ( 8.1 . 8.2 ) is used; Fixing the wound fiber layers ( 11.1 . 11.2 ) on the winding core ( 2 ) in the bending region of the flange with a holding tool ( 4 ), wherein the holding tool ( 4 ) annular over the entire circumference on the lateral surface of the winding core ( 2 ) radially from the outside in the direction of the central axis of the winding core ( 2 ) presses; - Leading out all winding pins ( 8.1 . 8.2 ) of a ring on a separately for each winding pin ( 8.1 . 8.2 ) fixed circular arc with a central angle of about 90 °, wherein the circular arc in a through the central axis of the winding core ( 2 ) extending arc of the arc lying, which the lateral surface at the position of the respective winding pins ( 8.1 . 8.2 ), and the center of the circular arc on the lateral surface in the intersection of the by the holding tool ( 4 ) contacted circumference circle lies with the circular arc plane, wherein each winding pin ( 8.1 . 8.2 ) from the lateral surface of the winding core ( 2 ) is led away radially; - radial opening of the holding tool ( 4 ) in the way that the holding tool ( 4 ) on the wound fiber layers ( 11.1 . 11.2 ) applied pressure drops to zero and between the holding tool ( 4 ) and the outermost fiber layer ( 11.2 ) around the circumference of the fibrous layer ( 11.2 ) circumferential gap of a thickness, the thickness of a Flanschverstärkungselementes ( 10 ) corresponds; Draping at least one flange reinforcement element ( 10 ) in the flange region of the hollow body ( 12 ), wherein the flange reinforcing element (s) (e) ( 10 ) over the entire circumference on the outwardly facing surface of the fiber layer ( 11.2 ) between holding tool ( 4 ) and fiber layer ( 11.2 ) and / or on the inwardly facing surface of the fibrous layer ( 11.1 ) between winding core ( 2 ) and fiber layer ( 11.1 ) and / or between two fiber layers ( 11.1 . 11.2 ) is / are draped; - consolidate the hollow body ( 12 ) with the fiber layers formed in the flange region ( 11.1 . 11.2 ) and the untrapped flange reinforcement elements ( 10 ) by bonding or local bonding or sewing; - removing the holding tool ( 4 ) and demolding the consolidated hollow body ( 12 ) from the winding core ( 2 ); - Performing a resin injection process; and finalizing the flanges in their final form by a forming manufacturing process. A method according to claim 1, characterized in that for the production of the hollow body ( 12 ) used reinforcing fiber strands are reduced. Method according to one of the preceding claims, characterized in that the flange reinforcement element ( 10 ) in position relative to the wound fiber layers ( 11.1 . 11.2 ) is fixed with bolts, which by in the flange reinforcement element ( 10 ) are placed in a region, which is removed by the final shaping manufacturing process, introduced positioning holes. Method according to one of the preceding claims, characterized in that a completely made of fiber composite flange reinforcement element ( 10 ) is used. Method according to one of the preceding claims, characterized in that a final machining process is used to finalize the flanges. Winding core for carrying out the method according to one of the preceding claims, characterized in that the winding core ( 2 ) at least one in the end portion on the lateral surface encircling ring of kinematically on a respective arc radially from the winding core ( 2 ) removable winding pins ( 8.1 . 8.2 ), each arc in each case in its own, by the central axis of the winding core ( 2 ) extending plane and the longitudinal axis of each winding pin ( 8.1 . 8.2 ) is arranged tangentially on the respective circular arc. Winding core according to claim 6, characterized in that the winding core ( 2 ) a hollow cylinder is in whose interior a kinematics for leading out the winding pins ( 8.1 . 8.2 ) is arranged.

Images