Abstract:
A device for splitting the ends of strands of laminar bonded fiber material, preferably carbon fiber-reinforced lamellae, into two or more end piles with a cutter, accurately to the measurements. The device includes a positioning device which enables the cutter to be aligned exactly in relation to the end of the fiber strand. In one embodiment, the carbon fiber lamella is fixed on a bearing table in a cutting position and a cutter that is pivotally mounted on the table is manually pivoted through the lamella end. In another embodiment, the cutter is held in a cutter slide and can be linearly displaced together with the same along a slide guide. Yet another embodiment includes a planing device in which the cutter is fixed and placed on the lamella end, the lamella end being guided through a linear guide and onto the cutter directly at the front in a manner which is accurate to the measurements and split into the desired number of end piles.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a device for splitting the ends of a lamella of fibre composite material, especially a carbon-fibre-reinforced plastics material lamella for reinforcing load-bearing structures, the device comprising a cutter.  
           [0002]    Fibre composite materials have proved themselves for increasing the load-bearing capability of load-bearing structures at existing buildings, which materials, for example in the form of lamellae of carbon-fibre-reinforced plastics material, so-called CFRP lamellae, are glued under bias over an area on the tension side of the load-bearing structure. Of particular significance in that case is the introduction of the biasing force by way of closure elements to the CFRP lamella. The ends of the CFRP lamella are split into at least two end plies along the fibre direction and connected in force-locking manner with the closure element, preferably glued, as is illustrated in Swiss Patent Application No. 1997 1987/97, which is not prior disclosed. Due to the splitting, an advantageous increase in the gluing area is achieved without the strength properties of the CFRP lamella in tension direction being impaired.  
           [0003]    Due to the small cross-sectional thickness of the lamella, what matters is maintaining the desired end ply thickness and avoiding separation through of the lamella. If in that case an end ply turns out to be too thin, then there is a great risk that the brittle fibres are bent over by the spreading apart of the end plies during mounting or during fixing in the connecting element at the structure and are no longer available for introduction of the biasing force by way of the connecting element into the lamella.  
           [0004]    The invention present therefore has the object of indicating a device which enables a separating of the lamella ends in simple manner.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention concerns a positioning device for the lamella, at which device the cutter is fixed, serves for this purpose. In that case cutter and positioning device are fixed in their position relative to one another, so that the fibre strand is aligned or positioned in desired manner in its position relative to the cutter. The cutter can be placed precisely at the fibre strand end and thereby split up end plies with desired layer thickness in intended and reproducible manner. Due to the laminar structure the cutter penetrates through the cross-sectional width in fibre longitudinal direction into the fibre composite material and splits a layer of the fibres, which have tensile strength in the fibre direction but which are brittle, fixed in the matrix. The cut sharpness is therefore so selected that it penetrates only into the matrix of the lamella and does not cut through the individual fibres. In order to avoid, during the cutting process, a breaking off possibly of thin end plies, it is best to use a cutting blade with a thin back of a few millimeters.  
           [0006]    According to a preferred embodiment of the invention the positioning device is formed as a support table with a flat support surface. In the region of the support surface a two-dimensional guide ensures that the lamella ends to be split are aligned in a desired cutting position relative to the cutter. The lamella brought into the cutting position is fixed in its position on the support table by means of a holding-down device. The cutter is, in common with a paring knife supporting it, connected with the support table to be pivotable about a pivot axis provided vertically relative to the support surface. In that case the paring knife bears by its planar underside on the support surface, whereby the cutter on pivotation of the paring knife in direction towards the lamella undergoes an exact guidance.  
           [0007]    The guide ensures that on one hand the lamella is supported in the cutting/pivoting direction of the paring knife and on the other hand that end plies are split off or separated off with desired thickness. The latter is preferably settable by way of the support position of the lamella on the support surface. Thus, in one embodiment templates are used which for setting the end ply thickness predetermine the support level of the lamella on the support surface and, through these, place the cutter at the desired position at the lamella cross-section.  
           [0008]    According to another embodiment it is advantageous with respect to a precise cut guidance if the cutter does not lie at the same time over the entire width at the end face of the lamella, but the position of the pivot axis in relation to the cut application is selected in such a manner that the cut is applied at one edge. The cut in that case penetrates effortlessly to the desired level and experiences a cut guidance during the further cut movement through the laminar structure of the lamella. According to another preferred embodiment of the invention the positioning device is in turn constructed as a support table for the lamella end to be split. As in the previously described embodiment, a lateral guide and a template for bedding the lamella serve the purpose of bringing the lamella into the desired cut position in which it is finally fixed by means of the pressing-down device.  
           [0009]    However, the cutter is to be moved in translational manner onto the positioned lamella end. Here, too, the cutter bears on the support surface, but is held in a knife carriage and displaceable together with this along a carriage guide relative to the support table. The carriage guide comprises two guide rods, which are arranged parallel to the translational movement preferably laterally at the support table and at which the knife carriage is fixed to be axially displaceable. Due to this parallel guidance the cutter experiences a particularly precise guidance, for which reason this embodiment is suitable to a high degree for splitting off or separating off a greater number of and thinner end plies.  
           [0010]    Knife carriage and carriage guide are constructed to be strong and rigid. Moreover, the cutter is arranged close to the support table and not laterally thereabove, whereby the risk of injury for the user as well as the risk of damage to the cutter are small. For the stated reasons this embodiment offers advantages in the mounting of the lamella at a building site.  
           [0011]    In a further particularly preferred embodiment of the invention, a positioning device and cutter are fixedly interconnected to form a planing tool. The positioning device forms a guide for the lamella, by virtue of which this can be inserted exclusively in longitudinal direction onto the free end of the lamella and be displaced. In that case the guide is oriented in such a manner that the lamella end at the end face runs directly onto the cutter and is split up into end plies. This embodiment has a particularly simple and robust construction; it enables a splitting of the lamella end without previous clamping or fixing of the lamella to the positioning device and is thereby particularly simple in handling. Moreover, the cutter is embedded in the positioning device and accordingly protected against damage and does not represent a risk of injury for the user. By virtue of its compact construction the planing tool embodiment is particularly well suited for use at a building site, where each reinforcing lamella can thus be adapted to the respectively required dimensions and the connecting elements can be mounted.  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0012]    The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:  
         [0013]    [0013]FIG. 1 shows a paring knife as a first embodiment of the invention, in plan view;  
         [0014]    [0014]FIG. 2 shows a schematic cross-sectional view of the paring knife along the section line II-II in FIG. 1;  
         [0015]    [0015]FIG. 3 shows a schematic detail view III of FIG. 2;  
         [0016]    [0016]FIG. 4 shows, schematically, a second embodiment of the invention with a cutter movable translationally;  
         [0017]    [0017]FIG. 5 shows, schematically, a third embodiment of the invention;  
         [0018]    [0018]FIG. 6 shows a half sectioned view of the embodiment illustrated in FIG. 5, along the section line VI-VI; and  
         [0019]    [0019]FIG. 7 shows a cross-section through a reinforced concrete beam with a CFRP lamella mounted on the underside, with a schematic cross-section through a locking element of a CFRP lamella. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    [0020]FIG. 1 shows a first embodiment of the device  1  according to the invention. The device  1  comprises, as essential subassemblies, a support table  2 , a pressing-down device  3  and a paring knife  4  pivotably connected with the support table  2 .  
         [0021]    The support table  2  has a rectangular outline and a flat support surface  5 . Machined over the entire length of the support table  2  on one half of the support surface  5  is a positioning groove  6 , the U-shaped cross-section of which, as illustrated in FIG. 2, is bounded by a flat groove base  7 , a first flank  8  and a second flank  9 , which extends parallel thereto, of an abutment strip  10 .  
         [0022]    The groove depth  11  is oriented to the thickness of the lamella  12  to be split and the desired thickness  13  of the end plies to be split off or pared off. The groove depth  111  is usually selected in such a manner that the CFRP lamella  12  laid into the positioning groove  6  protrudes by the desired dimension of the end ply thickness  13  above the positioning groove  6 . In order to be able to also set the thickness  13  of the end plies, which are to be split off, independently of the lamella thickness, a template  14  is additionally laid into the positioning groove  6  in the case of the embodiment illustrated in FIGS.  1  to  3 . The CFRP lamella which bears on this template  14 , can be bedded down above the thickness  15  thereof until the desired layer or end ply thickness  13  projects above the positioning groove  6 , which can be clearly recognized in FIG. 3.  
         [0023]    The width  16  of the positioning groove  6  is here selected to be slightly greater than the width of about 80 millimeters of a CFRP lamella  12 , the end-face end  17  of which is to be split into end plies. Basically the positioning groove  6  is provided to be equal in width to or wider than the CFRP lamella  12 , so that it is ensured in every case that the CFRP lamella  12  finds sufficient space in the positioning groove  6  and lies flatly on the groove base  7  or the template  14 . Independently of the actual lamella width, the lamella  12  bears laterally against the abutment strip and is clamped down by means of a holding-down device  3  described further below and fixed in its position.  
         [0024]    A scale calibration  19  is formed along the abutment edge  18  of the abutment strip  10  starting from the holding-down device  3 . It serves the purpose of aligning the free end  17  of the CFRP lamella in the position groove  6  to the desired length of the end plies.  
         [0025]    The holding-down device  3  bears by a flat pressing surface  20 , which faces the support surface  5 , on the CFRP lamella  12  and is screw-connected by four tightening screws  21  relative to the support surface  5 . The screw bolts  22  are anchored in the support table  2  and project through the holding-down device  3  by way of four correspondingly arranged bores  23 . A respective wing nut  24 , which is supported on the holding-down device  3  and presses this down, is screwed onto the free end, which protrudes above the holding-down device  3 , of each of the screw bolts  22 . Other quick-action fastening means or devices are also possible instead of the tightening screws  21  with wing nuts  24 .  
         [0026]    Thus, the holding-down device  3  can be connected, for example, at one side by way of a hinge or the like with the support table  2  and the opposite side can be pressed down onto the CFRP lamella  12  by way of a quick-action closure or a quick-action clamping screw. A holding-down device which is foldable in this manner is particularly simple in use.  
         [0027]    One end of a paring knife  4  is connected with the support table  2 , on the side opposite the abutment strip  10 , to be pivotable about a pivot axis  25  provided vertically relative to the support surface  5 . The length of the paring knife  4  is so dimensioned that it protrudes by its other end, which is constructed as a handle  26 , beyond the support table  2 . With the exception of the handle  26 , the side of the paring knife  4  facing the positioning groove  6  is obliquely sharpened and forms the cutter  28  by the underside  27  along the common edge. The underside  27  of the paring knife  4  is illustrated flat and bears on the support surface  5 , whereby the cutter  28  then experiences a precise guidance on pivotation of the paring knife  4  about the pivot axis  25 . The position of the pivot axis  25  and in addition the position of the cutter  28  relative to the positionally fixed CFRP lamella  12  is so selected that the cutter  28  pivoted by hand into the setting illustrated in chain-dotted lines in FIG. 1 hits at the corner edge  29  against the CFRP lamella  12  and can there apply the cut precisely at the level of the support surface  5 . As soon as the cutter  28  has penetrated into the fibre strand laminate of the CFRP lamella  12  and the cut is placed, the paring knife  4  can be pivoted by hand until in its end position parallel to the holding-down device  3 . In FIG. 4 there is illustrated a second embodiment of the invention in which in addition a support table  30  is provided, in which a lateral guide  31  and template  32  for bedding the CFRP lamella  33  serve the purpose of bringing the lamella  33  into a desired cut position in which it is finally fixed by means of the holding-down device  34 . By contrast to the previous example the cutter  35  is here to be moved translationally onto the positioned lamella end  36 .  
         [0028]    The cutter  35  is held in a knife carriage  37  and displaceable together with this along a carriage guide  38  relative to the support table  30  on the support surface  39 . The carriage guide  38  comprises two guide rods which are arranged parallelly to the translational direction  40  laterally at the support table  30  and are screw-connected at both ends by way of a screw connection  42  to two beams  43 ,  44 . One beam  43  is fastened at the front side  45  and the beam  44  at the rear side  46  of the support table  30  by means of screw connections  47 . The knife carriage  37  is fixed to this carriage guide  38 , which is fixedly connected with the support table  30 , to be axially displaceable.  
         [0029]    The knife carriage  37  comprises two guide sleeves  48  which are plugged onto the guide rods  41  and surround these. The guide sleeves  48  are fixedly connected together by way of a cutter carrier  49 . Arranged in notional prolongation of the cutter carrier  49  and at both sides are freely protruding rod-shaped handles  50  by which the inherently stiff knife carriage can be displaced by hand.  
         [0030]    Instead of the handles  50  it is also possible to displace the knife carriage  37  by means of a lever or screw mechanism, which is not illustrated here in more detail. A lever mechanism can be pivotably connected to the guide sleeves  48 , the tension force of which is introduced into the support table  30  by way of a correspondingly suitable kinematic system.  
         [0031]    A blade  51  with a straight or, as illustrated here, obliquely extending cutting edge  35  is fixedly connected with the cutter carrier  49 . Due to the oblique course of the cutting edge the cutter  35  initially hits against a corner edge  52  of the end-face lamella end  36 . There the cutter  38  penetrates in punctiform manner into the fibre laminate and thus applies the cut. On further displacement of the knife carriage  37  the cutter  38  then splits or pares off the respectively desired laminate layer.  
         [0032]    The knife carriage  37  and the blade  51  fastened thereto exhibit a cross-sectional profile which is wedge-shaped in cutting direction and which on penetration of the cutter  35  and progressing splitting of the lamella end serves as a guide step for the split-off laminate layer.  
         [0033]    An embodiment of the device according to the invention in the form of a planing tool  52  is illustrated in FIGS. 5 and 6. The planing tool  52  differs from the previously described embodiments of the invention by cutters  54  fixedly anchored in a positioning device  53 . With respect to the manner of function, the CFRP lamella  55  is not, in the case of this embodiment as a planing tool  52 , fixed in cutting position on the positioning device  53 , but cutters  54  and guide of the CFRP lamella  55  are fixed in their position relative to one another in constructionally defined manner and are displaced as a unitary device in common relative to the CFRP lamella  55 . On displacement, the free lamella end  56  is split up in one working process into the desired number of end plies.  
         [0034]    The planing tool  52  forms a first lateral part  57  and a second lateral part  58 , between which a first guide block  59  and a second guide block  60  are fixedly clamped in place by means of four clamping screws  61 . Lateral parts  57 ,  58  and guide blocks  59 ,  60  are preferably made of a metal material, such as aluminum; they can, however, also be made of plastic material or wood.  
         [0035]    The first guide block  59  and the second guide block  60  bound therebetween in longitudinal direction of the planing tool a guide slot  62 , which diverges in wedge shape towards the rear side  63 . The guide slot  62  has a rectangular cross-section over a length  64  from the front side  65  up to the transition  66  to the wedge-shaped funnel  67 , wherein the clear spacing  68  between the first guide block  59  and the second guide block  60  can be matched to the respective thickness of the lamella end  56 , which is to be split, with the aid of elongate holes  69  formed in the two guide blocks  59 ,  60 .  
         [0036]    The width dimension of the guide slot  62  is constructionally fixed to one size; expediently, it is selected in every case to be larger than the lamella width. Two knife blades  70 , which are axially aligned with the guide slot  62 , project from the rear side  63  so far into the wedge-shaped funnel  67  that their cutting edges  62  reach up to the rectangular guide slot  62 . The knife blades  70  extend over the entire width of the planing tool  52  and are combined in a knife insert  71  into a subassembly, which is fixedly mounted by means of socket pins  72  in the complementary recesses  73 ,  74  in the lateral parts  57 ,  58 . The knife insert  71  comprises, apart from the two knife blades  70 , on each side three spacers  75 , by which the mutual spacing  76  of the knife blades  70  and thus the layer thickness of the end plies can be fixed. At the same time, by appropriate adaptation in thickness the position of each individual knife blade  70  and/or knife insert  71  can be aligned and set in relation to the guide slot  62 .  
         [0037]    For anchoring of the knife insert  71  two bores are provided on each side in the spacers  75  and knife blades  70  perpendicularly to the blade plane and one behind the other. The position of the bores corresponds with bores  77  in the lateral parts  57 ,  58 , through which in the mounted state there is inserted the socket bolt  72  which fixes the knife insert  71 .  
         [0038]    [0038]FIG. 7 shows a cross-section through a reinforced concrete beam  78  with a CFRP lamella  79 , which is glued on at the underside (tension side) and at the ends of which closure elements  80  and  81  are mounted. Three retaining slots  82 ,  83 ,  84  are formed in the closure elements  80  and  81  to lie one above the other and to be spread apart in wedge shape, in each of which slots there is glued a respective one of three end plies  85 , into which the end of the CFRP lamella  79  is split. The introduction of tension forces by way of the closure elements  80 ,  81  into the CFRP lamella  79  is thus improved.  
         [0039]    In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.