Abstract:
An apparatus for laying fiber tapes includes a deflection guide for the fiber tapes consisting of pressure plates which are arranged adjacent to one another transversely to the deflection axis and a frame which is displaceable in the laying direction for accommodating the pressure plates. At least a part of the pressure plates respectively form a sliding shoe which is resilient in the pressing direction for the deflection of the tape.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Applicant claims priority under 35 U.S.C. §119 of Austrian Application No. A50829/2013 filed Dec. 16, 2013, the disclosure of which is incorporated by reference. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to an apparatus for laying fiber tapes, comprising a deflection guide for the fiber tapes consisting of pressure plates which are arranged adjacent to one another transversely to the deflection axis, and comprising a frame, which is displaceable in the laying direction, for accommodating the pressure plates. 
       DESCRIPTION OF THE PRIOR ART 
       [0003]    Laying heads with a deflection guide for the fiber tapes are usually used for producing fiber structures, which laying heads are pressed against the already laid fiber layers by means of the adjacently arranged pressure plates which form the deflection guide. The fiber tapes, which comprise an adhesive tape carrying a fiber layer, are drawn off from a supply roll to the extent of the forward feed movement of the laying head and supplied to the deflection guide in order to press the fiber layer to the already laid fiber layers on the one hand and to remove the adhesive tape from the fiber layer on the other hand, which requires a comparatively small deflection radius. Since the individual fiber layers of the fiber structure are to be placed tightly on each other with no trapped air in between, a respective pressurization of the fiber tapes by the deflection guide must be ensured. It is known for this purpose (EP 0 371 289 B1) to mount the pressure plates arranged in an assembly next to one another in a displaceable manner independently of each other in the pressing direction in a frame and to apply pressure to the same by a pressure means via a membrane, so that the individual pressure plates are also able to follow an uneven progression of the already laid fiber layers as a result of the flexibility of the membrane. There are limits to the mutually independent pressurization of the individual pressure plates as a result of the local deformation properties of the membrane which are not independent from each other, so that it does not make sense to provide the pressure plates for a finely graduated adjustment to the surface contour of the already laid fiber layers with a thinner configuration than a measure which is predetermined by the deformation properties of the membrane for the mutually independent pressurization of the pressure plates. 
         [0004]    In order to reduce the friction between the pressure plates and the fiber tapes, it is further known in apparatuses for laying fiber tapes (U.S. Pat. No. 5,352,306 A) to allow the pressure plates not to act directly on the fiber tapes but via a flexible slider which is fixed to a frame accommodating the pressure plates on the side of the pressure plates which is at the front in the laying direction. Such a slider extending over all pressure plates impairs a finely graduated adjustment of the deflection guide to the surface of the already laid fiber layers. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention is thus based on the object of providing a deflection guide for an apparatus for laying fiber tapes in such a way that the fiber tapes can be pressed by the pressure plates with a respective pressure in a comparatively finely graduated adjustment to the respective surface contour of the already laid fiber layers. 
         [0006]    On the basis of an apparatus of the kind mentioned above, this object is achieved in accordance with the invention in such a way that at least a part of the pressure plates respectively form a sliding shoe which is resilient in the pressing direction for the deflection of the tape. 
         [0007]    As a result of the arrangement of the pressure plates with sliding shoes which are resilient in the pressing direction, a respective pressing pressure can be exerted via the sliding shoes within the scope of their resilient pretensioning independent of the adjacent sliding shoes on the fiber tapes which are deflected about the sliding shoes, so that the thickness of the pressure plates or sliding shoes can be selected in a sufficiently thin way for the respectively required graduated adjustment to the surface contour of the already laid fiber layers, irrespective of whether the individual pressure plates are pressurized jointly or independently from each other by a pressing pressure. It merely needs to be ensured that the forces exerted on the pressure plates ensure a respective resilient pretensioning of the sliding shoes and thus a pressing of the fiber tapes on the already laid fiber layers in a manner that is substantially constant over the width of the tape. 
         [0008]    Especially simple constructional conditions are obtained for the formation of the sliding shoes in such a way that the pressure plates are provided with recesses which separate the sliding shoes from the remaining plate body. The connecting webs produced by the recesses between the plate bodies and the sliding shoes can be used advantageously in this case within the scope of their elastic bending behavior as spring elements. 
         [0009]    Since sufficient pretensioning of the sliding shoes must be ensured as a result of the sliding shoes which are resilient with respect to the plate bodies via the pressure means pressurizing the membrane, it is possible to subdivide the sliding shoes of the pressure plates into resilient sliding segments which are parallel to the plane of the plate and which are independent from each other, which allows an especially finely graduated adjustment of the pressure plates to the surface contour of the fiber structure, because the individual sliding segments of the sliding shoes can be displaced in a resilient fashion to the extent of the pretensioning independently from each other in the pressing direction. 
         [0010]    The friction between the deflection guide and the fiber tapes should be as low as possible. For this purpose, the sliding surfaces of the pressure plates can be coated accordingly. Especially advantageous constructional conditions are obtained however when the pressure plates are provided with compressed-air channels which open into the sliding surface for the deflection of the tape, so that the compressed air exiting from said compressed-air channels reduces the friction between the sliding surfaces and the adhesive tape of the respective fiber tape without impairing the pressing pressure of the fiber tape on the already laid fiber layers. On the contrary, the pressing of the fibers of the fiber tape on the already laid fiber layers can be supported advantageously by the pressure of the compressed air. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The subject matter of the invention is shown in the drawings by way of example, wherein: 
           [0012]      FIG. 1  shows an apparatus for laying fiber tapes in the region of the deflection guide for the fiber tapes in a schematic longitudinal sectional view; 
           [0013]      FIG. 2  shows this apparatus in a sectional view along the line II-II of  FIG. 1 ; 
           [0014]      FIG. 3  shows an illustration according to  FIG. 1  of a constructional variant of an apparatus in accordance with the invention; 
           [0015]      FIG. 4  shows a constructional variant of a pressure plate in the region of the sliding shoe in a sectional view along the line II-II in  FIG. 1  on an enlarged scale; and 
           [0016]      FIG. 5  shows a further embodiment of a pressure plate in accordance with the invention in a simplified side view. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    In accordance with the embodiment according to  FIGS. 1 and 2 , the apparatus for laying fiber tapes comprises a deflection guide  1  for the fiber tapes  2  which comprise an adhesive tape  4  carrying a fiber layer  3 . Said fiber tapes  2  are drawn off a supply roll in adjustment to the forward feed of the laying and pressed by means of the deflection guide  1  against the already laid fiber layers  5  of a fiber structure to be formed, wherein the adhesive tape  4  is removed from the fiber layer  3  of the fiber tape  2 , which occurs at a comparatively small deflection radius. The deflection guide  1  is composed of a plurality of pressure plates  6  which are arranged next to one of other perpendicularly to the deflection axis and which are displaceably guided in the pressing direction in a frame  7  and are pressurized jointly by a pressing means by means of a membrane  8 . In order to achieve simple constructional conditions, the membrane  8  is formed by a pressure hose in the embodiment, which rests on a frame wall  9  as an abutment on the side opposite of the pressure plates  6 . The pressure plates  6  are pressed against the already laid fiber layers  5  by pressurization of the membrane  8 , wherein the actuating path of the individual pressure plates  6  depends on the surface contour of the already laid fiber layers  5  as a result of the flexibility of the membrane  8 . 
         [0018]    As is indicated in  FIG. 2 , a step  10  in the fiber structure cannot be taken into account easily by the membrane deformation because said membrane deformation extends over several pressure plates  6 . In order to still enable a finely graduated adjustment of the deflection guide  1  to the surface contour of the fiber structure, despite the limitation caused by the membrane  8 , the pressure plates  6  form resilient sliding shoes  11  in the pressing direction, which sliding shoes are separated from the remaining plate body by a recess  12 . The remaining connecting webs  13  ensure the resilient properties of the sliding shoes  11  in the pressing direction, so that the sliding shoes  11 , as a result of their resilient pretensioning by the pressurization of the plates  6  via the membrane  8 , press the fiber tape  2  against the fiber layers  5 . This means that the sliding shoes  11  are pressed in a resilient manner against the fiber structure in the region of the fiber structure step  10  in addition to the pressurization of the membrane  8  with the effect that the fiber tape  2  rests with its entire surface on the step  10  of the fiber structure, which would not be ensured by pressurizing the membrane alone. This resilient displacement of the sliding shoes  11  is indicated in  FIG. 1  by the dot-dash line. 
         [0019]    As a result of the sliding shoes  11  which are resilient in the pressing direction, no separate pressurization of the individual pressure plates  6  is required especially in the case of lower thicknesses. As is shown in  FIG. 3 , the frame  7  can accommodate the pressure plates  6  in a mutually non-displaceable manner with respect to each other, so that in the case of a loading of the frame  7  with a respective pressing force the sliding shoes  11  of the individual pressure plates  6  are pressurized with a pretension which allows individual pressing of the sliding shoes  11  against the already laid fiber layers  5 . In this case, the individual pressure plates  6  can also be integrally connected to each other on the side of the recess  12  which is opposite of the sliding shoes  11 . 
         [0020]    The provision of sliding shoes  11  which are resilient in the pressing direction further allows an additional graduation in the pressurization of the fiber tape  2  over the width of the tape when the sliding shoes  11  are subdivided into sliding segments  15  by slots  14  which are parallel to the plane of the plate, as is indicated in  FIG. 4 . As a result of their pretensioning via the membrane  8 , the sliding segments  15  of the sliding shoes  11  are capable of pressing the fiber tape  2  independently from each other against the surface of the already laid fiber layers  5 . 
         [0021]    In order to ensure the reduction in the friction between the sliding surface of the sliding shoes  11  and the adhesive tape  4  of the fiber tapes  2 , said sliding surfaces can be provided with a sliding coating. Especially effective measures are obtained if the pressure plates  6  are provided according to  FIG. 5  with compressed-air channels  16  which open into the sliding surface of the sliding shoes  11 , so that the compressed air is injected between the sliding surface of the sliding shoes  11  and the fiber tape  2 . For the purpose of the supply with compressed air, the compressed-air channels  16  can originate from a common borehole  17  which extends through the assembly of the pressure plates  6 .