DE4004473A1 - Composite component prodn. with braided and unidirectional fibres - Google Patents

Abstract

In the prodn. of composite components one or more layers of unidirectional fibres are combined with a braided fibre structure on a shaped core. Both sets of fibres are drawn through an eye and the outer braiding fibres press the inner unidirectional fibres onto the core. The unidirectional fibres may be located between the core and the braiding fibres or are interwoven between the contra-rotating braiding fibres

Description

The invention relates to a method of manufacture of components with at least one layer along the construction part directional unidirectional fibers, in which a Support core is produced, which then together with at least partially surrounding the component, under tension held unidirectonal fibers by a device is performed such that the unidirectional fibers on the component is placed and glued with resin.

A method of this type is known from DE 34 13 601 A1, in which a prefabricated for the production of composite profiles ter support core together with surrounding reinforcing fibers in introduced a mold channel, impregnated with liquid synthetic resin and then subjected to a curing process. This allows components to be aligned along the component ten, so-called unidirectional fibers manufacturing technology just be surrounded. However, the procedure is only for Suitable components that have a constant cross section.

This shortcoming is allegedly proposed according to the DE 39 19 508 resolved that instead of the rigid form a membrane is used, the opening of which is automatic adapts to the contour of the component to be carried out.  

When using this method, however, Pro arise with curved components. The core surrounding, kept under tension fibers Curvatures of the support core take the shorter path want, causing the fiber to slip to the concave Side of the component and the lifting of the fibers at con kaven sides is possible.

The invention has for its object a method of to improve the type mentioned in such a way that Components of any configuration while maintaining the ferti engineering simplicity with unidirectional fibers can be covered.

The object is achieved with the features of Claim 1 solved.

The fibers of the wickerwork automatically wind around the Core around and press between the core and braided fibers located unidirectional fibers to the core. Here The braided fibers do not only replace the known ones Process used rigid form or membrane, but they at the same time form a torsion box for the component, which absorbs the radial forces occurring under load.

The procedure also leads unidirek tional fibers caused by these or parts thereof Need to be braided at the same time. In this way is at the same time slipping in the circumferential direction of the unidirectional fibers prevented.  

According to one embodiment of the invention, the unidirek tional fibers between the support core and the braided fibers leads. This configuration has the advantage that the uni directional fibers for optimal use of fiber strength be introduced into the component in a tensioned form, while the wattle around the unidirectional fiber location.

According to a further embodiment of the invention, at least part of the unidirectional fibers in that Wickerwork can be included, thereby guiding it along the surface line of the component is given. This shape device is particularly suitable for strongly curved components, where the most accurate guidance of the unidirectional Fibers along the surface lines is desired.

In this case, the chosen unidirectional fibers underlaid with braided fibers, so that these fibers in their Loss of strength. Anyone can compensate dings can be achieved by increasing the number of fiber layers. But it is also possible to choose very thin braiding fibers to reduce the loss of strength.

Of course, any combination is possible in which more or less unidirectional fibers between the Core and the braided fibers or within the braid be performed.  

A resin is introduced according to conventional methods Methods, e.g. B. by soaking the fibers before or after their application to the support core. That after the above Component manufactured described is to closing or while pulling through the thread eye subjected to heat treatment to cure the resin.

The invention extends to the application of the Process according to the invention for the production of bones implants, in particular for the manufacture of the shaft for a hip joint endoprosthesis. A pre-made core will preferably completely with taut unidirectional len fibers, the braided fibers the unidirectional len fibers surround.

Because of the curvature that an implant shaft has, can um at least part of the unidirectional fibers be braided to match this in the curvature to be able to lead. The ends of the shaft can exclude consist of unidirectional and braided fibers, the support core only as a displacement body Formation of the area with a thicker cross section is used becomes.

One can use the method according to the invention commercially available braiding machine can be used, the expanded with fiber guides for the unidirectional fibers becomes.

The invention is illustrated schematically in the drawing illustrated embodiments described in more detail. Show it:

Fig. 1 and 2, a plant for carrying out the method in section and in plan view,

Fig. 3 shows the fiber course on a component and

FIGS. 4 and 5 each shows a cross section of a finished component.

In Fig. 1, the manufacture of a prosthesis socket is shown, which initially consists of a prefabricated support core 10 . The support core 10 is pulled through a thread eye 11 of a braiding machine 12 by means of a gripper 13 . The braiding machine 12 consists of a guide ring 14 on which two sinusoidal guide rails 15 and 16 ( FIG. 2) are provided. In one rail 15 , a certain number of clappers 17 of a first group are guided in one direction 18 , while a second group of clappers 19 are guided on the second rail 16 in the opposite direction 20 .

During the movement of the clappers 17 and 19 described in this way , each individual fiber 21 is placed once under another fiber and once over another fiber. In addition to the braiding fibers 21 , 22 of the two bobbin groups 17 , 19 , uni-directional fibers 25 are provided via an inner ring 50 ( FIG. 2), which are drawn between the core 10 and the braiding fibers 21 , 22 through the thread eye 11 . All fiber ends are connected to the gripper 13 , which at the same time carries the support core 10 and moves it away from the thread eye 11 at a predetermined speed. For curved or irregular components, as is the case with the prosthetic socket, the gripper 13 is equipped with joints 30 , telescopic device 31 or the like in order to be able to carry out swiveling movements in addition to the feed movement 32 . In this way, the component can be aligned in such a way that the axis of the component area that is currently on the thread eye plane is on the braiding machine axis. In this way, the unidirectional fibers 25 kept under tension will always follow the surface lines 35 ( FIG. 3) of the component.

The individual braiding fibers 21 and 22 describe a helix in the course of the braiding process, as is shown in FIG. 3 with the thick-drawn fiber 21 . In this course, the braiding fiber 21 presses the unidirectional fibers, which follow the surface line 35 of the support core 10 ', to the support core 10 or 10 '. The gradient of the wrapped braiding fibers or their orientation on the finished component is determined by the geometric conditions of the braiding machine 12 , the cross section of the component or support core 10 and the speed at which the component 10 is moved. By automating and programming the gripper movement mechanism, the feed speed can be changed in accordance with the geometry or the cross section of the construction part 10 in order to obtain the desired orientation of the braided fibers 21 , 22 over the entire component.

Both the braided fibers 21 and the unidirectional fibers 25 can be impregnated with impregnation devices with a matrix beforehand. The curing of the resin is effected by means of the Heizeinrich device 37 provided above the thread eye 11 . The introduction of the matrix material and its hardening can also be carried out in any other known way.

In the steps described so far, the uni-directional fibers 25 form an inner fiber layer which is surrounded by the wattle 55 . In a longitudinal section through the finished component 40 , as shown in FIG. 4, a longitudinal fiber 25 can be seen on the surface 41 of the support core 10 , on which the braided fibers 21 and 22 are located. In this case, the unidirectional fiber 25 lies exactly parallel to the surface line 35 of the support core 10 . It is stretched, which means that the component has the optimum strength for compressive / tensile loads.

If a component has strong curvatures, such as. May be for example in the prosthesis shaft the case would be in addition to the radial guide of the unidirectional fibers 25, a tangential guide expedient to slippage of the fibers under tensile stress areas 25 in the curve 38 of the support core 10 to be avoided. In this case, a part of the unidirectional fibers 25 is not within, but led through the braid ring 14 . This is shown in more detail in FIG. 2, in which the inner ring 50 does not guide all, as described above, but rather only a large part of the unidirectional fibers 25 , while thread eyes 51 for unidirectional fibers 25 are provided in the ring 14 . These fibers 25 'are alternately passed under by one bobbin group 17 and passed over by the other bobbin group 19 , so that these unidirectional fibers 25 ' in addition to the radial guidance through the braided fibers 21 , 22 also a tangential guidance, as in Fig. 3 with the arrows 52 indicated, experienced. So who the they held in their position, ie along the corresponding surface line 35 of the support core 10 '.

In this case, as shown in Fig. 5, the corresponding de unidirectional fiber 25 'underlaid in places by braiding fibers 21 and wrapped in between with braiding fibers 22 , so that the unidirectional fiber 25 ' loses its optimal tensioned position. With very thin braiding fibers 21 and 22 , this disadvantage can be minimized when it matters. The ratio of the unidirectional fibers 25 and 25 'guided by the inner ring 50 and the braid ring 14 ' can be chosen as desired. It will usually depend on the respective application and its requirements.

For the manufacture of a shaft for a hip joint implant with unidirectional fibers, the ratio between the inner ring 50 and the braid ring 14 guided unidirectional fibers 25 and 25 'should be chosen as large as possible.

Claims (5)

1. A method for producing components with at least one layer of uni-directional fibers directed along the component, in which a prefabricated support core is passed through a device together with the component, at least partially surrounding, held under tension, unidirectional fibers, the unidirectional fibers placed on the component and glued by means of resin, characterized in that in addition to the unidirectional fibers ( 25 ) from a braiding machine ( 14 , 17 ) guided braiding fibers ( 21 , 22 ) with the support core ( 10 , 10 ') through a braiding eye ( 11 ) are guided, at least some of the braiding fibers forming a wickerwork ( 55 ) which surrounds the unidirectional fiber layer ( 25 ). 2. The method according to claim 1, characterized in that the unidirectional fibers ( 25 ) between the support core ( 10 , 10 ') and the braided fibers ( 21 , 22 ) are guided. 3. The method according to claim 1 or 2, characterized in that the unidirectional fibers ( 25 ) at least partially on the level of the braided fibers ( 21 , 22 ) are guided such that they are braided. 4. The method according to claim 3, characterized in that very thin braiding fibers ( 21 , 22 ) are used. 5. The method according to any one of the preceding claims, characterized by using the method for Manufacture of bone implants.