DE1252534B - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl.

B64c

B 29 j

German class: 62 b-24/04

Number: 1252 534

File number: B 72361 XI / 62 b

Filing date: June 21, 1963

Opened on: October 19, 1967

The invention relates to a method for producing self-supporting aircraft or missile components such as wings, fuselage pipes _j fins, control surfaces, fins u. The like., With a smooth outer skin and a wave-shaped with this bonded stiffening element of glass fiber reinforced synthetic resin.

As far as missile components or panels for aircraft components of the aforementioned construction are known are, they have a shell-shaped structure. The strength of a so-called shell is included mainly dependent on so-called support elements with regard to their resistance to bulging and grip and, in terms of its flexural strength and torsional strength, is essentially dependent on the rigidity of a die Shell-supporting frameworks of ribs and webs influenced.

Such a shell usually consists of two glass fiber reinforced, preferably multilayered Skins, an outer skin and an inner skin, which include support elements between them.

These support elements are honeycomb-shaped in sandwich or honeycomb constructions, made of aluminum, Paper, plastics or synthetic resins prefabricated and preferably using synthetic resin each glued to the outer skin and the inner skin.

It has been shown that created according to the conventional glass fiber reinforced synthetic resin lightweight construction Aircraft components meet today's requirements of aviation technology in terms of load capacity and Only partially correspond to its own weight. For example, there is sufficient strength of the bond between the support elements and the outer skin or the inner skin and between this and the Bars of the framework can only be achieved if there is a sufficient amount of adhesive for a kind of embedding forms the parts to be connected to the relatively small adhesive surfaces in these designs to enlarge. It also has a disadvantageous effect that for a proper transfer to the Longitudinal, transverse and torsional forces acting on the framework a variety of with the shell Shell glued ribs and webs is required.

The construction of the conventional shell components requires time-consuming and complex operations. So the support elements of the shell have so far been handcrafted in individual parts of the shape of the to be created component adapted and joined together in a so-called trough. These Work requires manual dexterity as well as the utmost precision and is therefore

Method of making self-supporting
Aircraft or missile components with a
Outer skin and one glued to it
wave-shaped stiffening element
glass fiber reinforced synthetic resin

Applicant:

Bölkow limited liability company,
Ottobrunn near Munich

Named as inventor:
Dipl.-Ing. Erich Ufer, Meindorf;
Karl Knieper, Ottobrunn near Munich;
Alfons Pützer, Bonn

makes it difficult that the usual honeycomb support elements have no elastic behavior. at the shell components created according to previously known manufacturing processes can therefore be a Increase in the permissible load values only indirectly via complex and weight-increasing constructive measures can be achieved.

The invention is based on the object of creating a method by means of which bypassing the disadvantages of the aforementioned construction self-supporting aircraft or missile components fiberglass-reinforced synthetic resin can be created in rib-free lightweight construction, whereby according to The components produced according to the invention compared to the known components due to a higher bending, Shear and torsional rigidity should be characterized.

The production of components of the type mentioned takes place according to the invention by that the glass fiber fabric for stiffening the component is applied to a core corresponding to the stiffening element to be created and by means of pressure and / or tension means under tension one after the other into wave-shaped recesses of the core drawn in, soaked with synthetic resin during or before or after this process, cured on the core and in a shape with

709 678/107

at least one fiberglass fabric layer impregnated with synthetic resin and forming the outer skin of the component is glued.

In lightweight aircraft and body construction, it is known to use support elements with a corrugated profile, z. B. corrugated sheets, each joined together with an outer skin and an inner skin to form a so-called sandwich component, for example glued are. Such sandwich components with large spacing of the support are only relative thick skins and are only suitable for production reasons for essentially flat Trash pieces.

In contrast, the stiffening element according to the invention can be used for lightweight components of any shape and sizes are used. Due to its special design, it gives the component or the supported outer skin has high strength and rigidity properties.

Furthermore, double-walled lightweight construction panels are also known in which trapezoidal corrugated profiles with corrugations running in the longitudinal direction of the component are arranged as support elements of the wall panels are. Such components cannot be produced by the method according to the invention, since as most components in which double wall panels of the aforementioned type are used, in the direction the corrugated profiles cannot be developed and thus with the known corrugated profiles no or only under difficult conditions in the longitudinal direction of the waves curved components can be produced. In addition, these components require shape retention and Dimensional rigidity additional ribs and ribs.

In contrast to the known components, the method according to the invention has the following advantages: Any components can be produced; Ribs and ribs are omitted because the transverse to the Longitudinal reinforcement of the component extending waves themselves represent a plurality of ribs and ribs; these cross shafts can be used cheaply in procedures are made; the weight-related strength is for hollow bodies with transverse corrugations (e.g. in aircraft fuselages, wings or the like) higher than in bodies with longitudinal waves.

For the stiffening element, glass fiber fabric can be used in various types of binding and manufacturing forms, e.g. B. mats, strips or ribbons, butted, overlapped or crossed as well as one or find use in multiple layers. Glass fiber fabrics with a elastic binding. Preferably, according to the invention, the glass fiber fabric is essentially with a fiber orientation of about 45 ° compared to the course of the wave-shaped recesses on the Core applied.

According to the invention, the pulling in of the fiberglass fabric in .die recesses of the core by means of fiberglass strands or fiberglass tapes as well as by means of rollers or stamps. To the Particularly suitable for pulling in are tubular woven glass fiber tapes, which are tightened in the recesses of the core under tensile stress lay the fiberglass fabric, forming beads on each of its long sides.

In this way, a stiffening element can be produced whose corrugated profile is extremely precise and whose wave troughs are reinforced at the same time. As a result of the bulge formation, they also increase

the surfaces involved in the bonding. If the stiffening element is to be particularly reinforced in the wave troughs, then glass fiber strands with a circular or lenticular cross-section are preferred.

According to a further method of the method according to the invention, the glass fiber strands are or the fiberglass tapes so impregnated with synthetic resin when applied to the core that the Resin escaping from them when resting on the core under tensile or compressive load is just sufficient to reach the area covered by them to soak dry fiberglass fabric with a predeterminable percentage of synthetic resin.

Appropriately, according to the invention, the applied to the core and into the recesses fiberglass fabric drawn in shortly before gluing to the outer skin with synthetic resin soaked and cured together with this. Such a process flow offers on the one hand the The advantage is that dry glass fiber fabric can be applied to the core more easily, quickly and with less effort can be applied as a pre-impregnated fiberglass fabric. On the other hand, using the So-called wet-on-wet gluing process, a lighter construction is achieved, and further operations are saved, since the additional application of No glue is required.

In a further embodiment of the method according to the invention, before or after gluing of the stiffening element with the outer skin webs made of corrugated profile, which are also produced by the method according to the invention and, as already described, are created, in the manner of a toothing, form-fitting with the stiffening element connected, e.g. B. be glued.

The stiffening element can also consist of several individual elements connected to one another put together that are easier to manufacture individually, e.g. B. wrap and their junctions for the finished component additionally as reinforcements, e.g. B / serve as a bending beam.

The advantageous design of the core required to manufacture the stiffening element allows the method according to the invention can be further simplified. According to the invention it is provided that the core has a corrugated profile on its surface with a substantially transverse to the direction of the greatest bending load and preferably parallel has mutually extending recesses, and that the wave crests of the profile in at least a plane tangential to the outer skin having the shape of the component are flattened. According to a further feature of the invention, the corrugated profile described can be incorporated into the surface of the core or it can be smooth formed and arranged on her an elastic corrugated profile.

The elastic corrugated profile of the core can also be compared to that coated with the outer skin Shape oversize, so that when the outer skin and stiffening element cure together, a press-fit bond is guaranteed without additional work.

According to the invention, the corrugated profile can also run helically and single or multi-thread be arranged.

According to a further feature of the invention, the cores can also be coated with fiberglass fabric

then done by winding, if a stiffening element for a flat or concave curved one Component is to be created. For this purpose, the core is designed so that the wave crests of its corrugated profile correspond to the shape of the component and are partially concavely curved, while its recesses have an at least slightly convexly curved course,

In the drawing are preferred exemplary embodiments and method steps and means for Implementation of the method according to the invention shown schematically. It shows

F i g. 1 in a perspective view and in section, a ribless wing part, consisting of a Reinforcement element made of fiberglass-reinforced corrugated profile, a similarly designed web as a bending beam and a smooth outer skin made of synthetic resin-soaked fiberglass fabric layers,

F i g. 2 shows an enlarged view of a section II-II through the wing part according to FIG. 1,

F i g. 3 shows a perspective partial view of one for producing the stiffening element according to FIG Fig. 1 required core during continuous coating with glass fiber fabric strips and glass fiber fabric tapes,

Fig. 4 in an enlarged perspective view and in section, a core piece during coating, with recesses and dowel pins worked into its surface for deflecting the glass fiber strands,

F i g. 5 in a view similar to FIG. 4 a core piece in coating, with helical running recesses, which are formed by an elastic corrugated profile placed on the surface of the core,

F i g. 6 in a view similar to FIG. 4 a key element in coating, its wave crests have a partially concavely curved course and its recesses are convexly curved get lost,

F i g. 7 in a view similar to FIG. 4 a core piece in coating, being glass fiber fabric is drawn or pressed into the recesses of the core by means of a roller-like punch,

F i g. 8 in an enlarged perspective partial view of the positive connection of the web with the Stiffening element according to FIG. 1,

F i g. 9 shows, in an enlarged view, the formation of the web at the connection point with the stiffening element according to FIGS. 1 and 8,

F i g. 10 in a perspective view and in section, a tubular body part with an in the Reinforcement element incorporated power transmission frame,

11 shows a perspective view of a wing part according to FIG. 1 with one as a connection with the power transmission frame according to FIG. 10 trained stub stubs,

FIG. 12 shows, in an enlarged partial perspective view and in section, a bending beam which is composed of two U-shaped webs made of corrugated profile and belts made of fiberglass-reinforced synthetic resin, which are incorporated into the stiffening element are,

F i g. 13 shows, in a partial view, the connection of the corrugation crests of the webs of the bending beam, which run with opposing slopes, through the openings of a light metal web according to FIG. 12 and

F i g. 14 in a perspective view and in section a wing part according to FIG. 1, whose stiffening element is composed of two individual elements, the abutting parts of which have a Light metal beams are connected to a bending beam, and coated in one with the outer skin Form is inserted.

The basic structure of a fiberglass-reinforced synthetic resin lightweight construction tool component is from the in F i g. 1 shown example of a wing part as well as from the in Fig. 2 shown, associated section II-II can be seen. It essentially consists of one tubular, self-contained, one-piece Verls steifungselementl and one glued to this Outer skin 2. The stiffening element, which, like the outer skin, consists of one or more synthetic resin-soaked fiberglass fabric layers is in the manner of a corrugated profile in a relatively steep trapezoid

ao form trained. This corrugated profile has waves 3 which are transverse to the direction of the greatest bending load of the component are arranged closely packed one after the other and run parallel to one another. Her Wave crests 4 are opposite the outer skin 2

as flattened and support each of these with their entire flattened surface. That of the outer skin facing edges 5 are rounded. In the wave troughs 6 of the corrugated profile there are glass fiber strands 7 (see also Fig. 4) or glass fiber tapes 8 (see.

Fig. 5) as a reinforcement of the stiffening element glued to this. As in the following in more detail is to be explained, are in FIG. 1 as additional reinforcement in the direction of the greatest bending load in Stiffening element 1, a web 9 made of corrugated profile and a belt-like reinforcement 10 on the outer skin 2 arranged. The fiber orientation of the fiberglass fabric of the outer skin and the stiffening elements is indicated by hatching 40 in each case. It is about 45 ° to the longitudinal direction of the component ^

Various possibilities for the production of the stiffening element 1 are shown in FIGS. 3 to 7.

For the purpose of a better overview, corresponding parts are provided with the same reference symbols in all figures.

A core 11 made of wood or plastic is provided for the production of a stiffening element, which has on its surface. 12 recesses 13, which are the counterpart to the described, trapezoidal corrugated profile of the stiffening element form. The recesses can be incorporated into the core (FIG. 4) or by placing one on top elastic, hollow corrugated profiles 14 made of plastic on the smooth surface of the core (Fig. 5). In the FIGS. 3 and 5 shown Embodiments run the wave-like Helical recesses. As cannot be seen from the drawing, the cores themselves are usually composed of several parts. Glass fiber fabrics are placed on the core strip 15 or glass fiber fabric 16 with one the hatching 40 indicated fiber orientation applied and by means of the glass fiber strands 7 or the Glass fiber tapes 8, which by one in F i g. 3 shown pulling device 18 under bias are held, drawn into the recesses 13 of the core. For the application of the glass fiber fabric strips 15 are usually guides 19 required, which is e.g. attached to a ring 17

are arranged (Fig. 3). The glass fiber strands 7 or glass fiber tapes 8 are effective as pulling means and as pressure means. Their cross-section is always like this dimensioned that the glass fiber fabric 16 or the glass fiber fabric strips 15 are forced to to adapt to the recesses 13 of the core (Fig. 3 to 6).

As in Fig. 3 indicated by arrows 20 and 21, this process can take place with relative movement between Core 11 and pulling device 18 and guide 19 run continuously so that the stiffening element is wound in one continuous operation can be. Depending on the shape and size of the component to be created, the core and guide can rotate around the Core axis 22 and the pulling device perform a longitudinal movement in the direction of the core axis or vice versa. Also a combined helical movement of the core or the guide or the Pulling device is possible.

Are - as in the example of a bending beam in FIGS. 12 and 13 - the recesses 13 of the core or the shafts of the stiffening element are arranged in multiple threads, the corresponding number of glass fiber strands 7 or glass fiber tapes 8 must be wound at the same time.

In the case of cores that are only to be partially coated, for example for the one shown in FIG. 10 body part shown, the glass fiber fabric 16 is passed through the glass fiber strands 7, which are each diverted at the ends of the recesses 13 via dowel pins 23 and back and are wound over the core part, drawn into or out of the recesses in the core. pressed in (Fig. 4).

The winding of a stiffening element with a partially concave course of the wave crests 4 is shown F i g. 6. The core 11 is designed so that the recesses 13 of its corrugated profile at least run slightly convex, while its wave crests 4 correspond to the shape of the outer skin to be supported and partially curved concavely are (see. Reference numeral 24). As already described, the glass fiber fabric 16 can therefore also in this case by means of the glass fiber strand 7 in the Recesses of the core are drawn in.

Another method for creating a stiffening element 1 is shown in FIG. 7. A stamp 25, consisting of at least two rollers 26 designed in trapezoidal profile takes on the task of pulling or pushing the glass fiber fabric 16 into the recesses 13 of the core 11. the Rollers are spring-loaded next to one another or one behind the other on a common holder 27 arranged increasing depth of engagement. The movement sequence of the stamp or the holder corresponds to that of the pulling device 18.

Depending on the shape and size of the stiffening element to be created, the glass fiber fabric processed dry or impregnated with synthetic resin, d. H. before, during or after application to the core Soaked in synthetic resin. Another possibility is shown in FIG. 3 shown. Dry fiberglass fabric will by means of synthetic resin-soaked fiberglass strands or fiberglass ribbons 8 in the recesses of the core 11 pulled into it. For this purpose, the fiberglass ribbons run through a synthetic resin bath, which is filled with a Tub 30 and a roller 31 is indicated. The pulling device 18 is designed as an adjustable scraper

direction trained. The fiberglass strands or the fiberglass tapes contain just enough synthetic resin that the synthetic resin emerging from them when resting on the core under tensile and compressive load is sufficient to cover the one covered by them Area of dry fiberglass fabric with a predeterminable percentage of synthetic resin soak.

Also according to the listed procedural features

painting in corrugated profiles can also be made from bending beams, web parts or other reinforcements for the stiffening element

Like F i g. 1 and in particular FIG. 8 shows, the web 9 is positively locked in the manner of a toothing glued to the stiffening element. In each case, those reinforced by glass fiber strands 7 are supported here Wave crests 6 of the web on corresponding wave crests 6 of the stiffening element 1 from. The wave crests 4 of these are also supported analogously

ao parts on top of each other. From Fig. 9 it can be seen that the ends of the corrugated profile of the web 9 at 45 ° are bevelled.

Another embodiment of a bending beam is shown in FIG. 12 can be seen. Here sits down

The bending beam consists of two U-shaped webs 33 and 34 formed in a corrugated profile and a top flange 35 and a lower chord 36 together, each form-fitting with the only partially shown Stiffening element 1 are glued. The straps consist of a variety of synthetic resin impregnations Glass fiber strands 39 and are in recesses 37 and 38 of the stiffening element transversely to the shafts inserted. The webs can by interposing a light metal web 41, the openings 42 on has to be additionally reinforced. Like in particular from 13, the shafts of the webs 33 and 34 are each multi-thread and with opposite directions Arranged gradients. As a result of this design, the webs can - as by hatching 43 marked - are glued together in a diamond shape.

As can be seen from FIG. 14, the stiffening element can also consist of two or more formed in corrugated profile individual elements 45 and 46, which are connected by means of a light metal bending beam 47. In the area of the bending beam, the outer skin 2 has a belt-like reinforcement 10 (see also FIGS. 1 and 8), which is shown in FIG Direction of force transfer is reinforced.

The outer skin is applied to the stiffening element in a divisible form, the lower part 50 or the upper part 51 of which are each coated individually. After applying a Separating layer 52 and application of identification 53 a lacquer layer 54 is sprayed on and onto this several synthetic resin-soaked fiberglass fabric layers 55 taking into account the on the thrust flow Matched fiber orientation applied together with the belt-like reinforcement 10.

The stiffening element, which is shown in FIG. 14 from the with the individual elements 45 and 46 connected to the light metal carrier 47 are inserted. Then the upper mold part 51 is placed and with the Braced lower part. The stiffening element is glued to the outer skin and in one cured subsequent drying process with or without supply of heat.

Claims (14)

Patent claims: 1. A method for producing self-supporting aircraft or missile components with an outer skin and a corrugated stiffening element made of glass fiber reinforced synthetic resin bonded to it, characterized in that the glass fiber fabric (16) for the stiffening of the component on a corresponding to the stiffening element (1) to be created The core (11) is applied and pulled one after the other into wave-shaped recesses (13) of the core by means of pre-tensioned compression and / or tension means, soaked with synthetic resin during or before or after this process, cured on the core and placed in a mold (50 and 51) is glued to at least one synthetic resin-impregnated glass fiber fabric layer (55) which forms the outer skin of the component. ao 2. The method according to claim 1, characterized in that the glass fiber fabric (16 ) is applied to the core (11) essentially with a fiber orientation (40) of about 45 ° with respect to the course of the recesses (13) , as 3. The method according to claim 1, characterized in that the glass fiber fabric (16) when applied to the core (11) by means of glass fiber strands (7) or glass fiber tapes (8) are drawn into the recesses (13) of the core. 4. The method according to claims 1 to 3, characterized in that the glass fiber strands (7) or the glass fiber tapes (8 ) remain as reinforcements in the corrugation troughs (6) corresponding to the recesses (13) of the core (11). 5. The method according to claim 1, characterized in that the glass fiber fabric (16) when applied to the core (11) by means of known stamps (26) or rollers (26) with increasing depth of engagement in the recesses (13) of the core or . is pressed in. 6. The method according to claim 3, characterized in that the glass fiber strands (7) or the glass fiber tapes (8) when applied to the core (11) are soaked with synthetic resin that the out of them when resting on the core under tension and Resin escaping pressure load is sufficient to impregnate the area of dry glass fiber fabric (15 or 16) covered by them with a predeterminable percentage of synthetic resin. 7. The method according to claims 1 to 6, characterized in that the on the core (11) applied and drawn into the recesses (13) glass fiber fabric (15 or 16) is impregnated with synthetic resin shortly before gluing to the outer skin (2) and cured together with this. 8. The method according to claims 1 to 7, characterized in that before or after gluing the stiffening element (1) to the outer skin (2) webs (9, 33 and 34) made of corrugated profile in the manner of a toothing positively connected to the stiffening element, z. B. be glued. 9. Core for carrying out the method according to claims 1 to 8, characterized in that the core (11) on its surface (12) has a corrugated profile with recesses (13) which are arranged essentially transversely to the direction of the greatest bending load and preferably run parallel to one another. and that the wave crests (4) of the profile are flattened in at least one plane tangentially with respect to the outer skin (2) having the shape of the component. 10. Core according to claim 9, characterized in that it corresponds to the shape of the component to be created by the thickness of the outer skin (2) and reduced by the height of the corrugated profile and that an elastic corrugated profile (14) is arranged on its smooth surface (12) is. 11. Core according to claims 9 and 10, characterized in that the waves of the corrugated profile (14) arranged on the smooth surface (12) of the core (11) are helical. 12. Core according to claim 11, characterized in that the waves of the corrugated profile (14) arranged on the smooth surface (12) of the core (11) are multi-threaded. 13. Core according to claim 10, characterized in that its elastic corrugated profile (14 ) is oversized with respect to the form (50 and 51) coated with the outer skin (2). 14. Core according to claims 9 to 13, characterized in that the corrugated crests (4) of its corrugated profile correspond to the shape of the component and are partially concavely curved, while its recesses (13) have an at least slightly convex curve. Considered publications:
H.Hertel, "Lightweight Construction", 1960, chap. Aircraft and other lightweight structures; »The Machine Market«, No. 98, December 6, 1957,
Pp. 22 to 26. 1 sheet of drawings 709 678/107 10.67 Q Bundesdruckerei Berlin