The invention relates to a long-fiber-reinforced polymer material, in particular for processing in the injection moulding method or extrusion method, consisting of granular materials with integrated long-fiber reinforcement, according to the preamble of claim 1, as well as to a method and to an installation for manufacturing this long-fiber-reinforced polymer material. Materials known for application in injection moulding methods and extrusion methods are short-fiber-reinforced polymer material in the form of granular materials with 0.1 to 5 mm fiber length and long-fiber-reinforced polymer material in the form of rod-like granular materials with fiber lengths of 5 mm to 50 mm, wherein rod-like granular materials more than 25 mm long can only be processed with modified, large, special plasticisation assemblies. One usually obtains lengths of 10 mm, 12 mm or 25 mm. Non-continuous winding methods, e.g. for manufacturing containers and pipes with continuous fiber rovings, are known as methods for manufacturing components with very long fibers. A special injection moulding installation is known e.g. from WO 00/37233, with which a continuous fiber strand is mixed into the compounder and is injected in a directly discontinuous manner (in-line compounding). This method however basically necessitates special complicated, expensive injection moulding installations.
Long fibers in the resulting injection moulded components can only be achieved to a very limited extent with the known polymer materials. When processing known rod-like granular materials with screw plasticisation assemblies, the relatively long fibers are subjected to high shear loads which lead to most of the long fibers being broken and massively shortened. Moreover, the maximal fiber length is also limited by the length of the rod-like granular material. This problem of the shortening of the fibers, above all on feeding and in the solid-matter conveyor region of screw machines, has not been solved to this date. The problem becomes more acute, the smaller are the applied screw diameters. In particular, the processing of LFT rod-like granular materials with screw diameters below 60 mm is not possible today without changes with regard to the machine.
It is therefore the object of the present invention, to overcome the disadvantages and limitations of the known long-fiber-reinforced polymer materials and to provide a continuously manufacturable, long-fiber-reinforced polymer material which after the processing, in particular permits much longer fibers in the component and thus much better mechanical properties than was previously the case. This above all should also permit the processing on existing, smaller injection moulding installations and extrusion installations with smaller screw diameters, even of less than 45 mm.
According to the invention, this object is achieved by a long-fiber-reinforced polymer material according to claim 1, by a method according to claim 11, and by an installation according to claim 18 for the continuous manufacture of the long-fiber-reinforced polymer material as well as by a component and a method for manufacturing a component with wound elements. With the shaping and construction of the wound elements according to the invention, much greater fiber lengths and a much greater share of long fibers are achieved in the components manufactured with these, and thus the mechanical properties of these components such as strength, stiffness and impact strength are greatly improved. The shaping of the wound elements on the one hand results in large fiber lengths in the compact round granular material and on the other hand permits a gentle processing with less fiber breakages and thus greater fiber lengths in the component.
The dependent patent claims relate to advantageous further formations of the invention with particular advantages with respect to the rational manufacture, processing and optimal characteristics or properties of the long-fiber-reinforced polymer material in the form of wound elements, and significantly better mechanical properties of the components manufactured with this.
The invention is hereinafter explained further by way of embodiment examples and figures, and thereby there are shown in:
a, b an example of a wound element with three turns lying over one another,
a a manufacture of wound elements by way of forming windings on a winding core,
b a wound element with turns partly lying over one another,
a,b a manufacture of wound elements with turns lying over one another,
a, b a manufacture of wound elements with turns lying next to one another,
c a manufacture of wound elements in mixed form,
a, b a manufacture of wound elements with turns lying over one another and next to one another,
a, b a manufacture of wound elements with an additional displacement of the running-in, impregnated continuous fiber strand,
a-d different examples of winding cores,
a-manufactured from known rod-like granular materials,
b-manufactured from wound elements according to the invention, as a granular material,
a, b a multiple winding installation with many winding locations,
The wound elements 5 according to the invention can comprise turns 6 lying over one another=curled 51 (according to
On advancing and melting the wound elements 5 in a compounder of a shaping process (e.g. injection moulding), curled wound elements 51 with turns lying over one another maintain their shape longer, the turns are broken up less rapidly and are mixed through less rapidly than with spiral-shaped wound elements 52 with turns lying next to one another. The curled wound elements 51 therefore tend to have particularly less fiber breakages with accordingly longer fibers in the components and are intermixed to a lesser extent, whilst the spiral-shaped wound elements 52 tend to break up more rapidly, to have a greater intermixing, but less long fibers in the component—not as long as with curled wound elements—but much longer that with granular materials until now.
With mixed forms 53 of the wound elements, with turns lying to some extent over one another and to some extent next to one another, as well as by way of the number and size of the turns in the wound elements, one can influence and optimise the desired characteristics in the component manufactured therefrom (fiber length, distribution, degree of mixing).
Curled wound elements 51 are particularly suitable for achieving as large as possible fiber lengths in a component.
a, b in two views show a wound element 5 with three turns 6.1, 6.2, 6.3 lying over one another, with the linear dimensions L=length, B=width, H=height. The wound elements 5 have an as compact as possible, round shape, in the broadest sense approximated to a ball shape or square cylinder shape. With this, relatively very large fiber lengths f which amount to a multiple of the fiber lengths of known long-fiber granular materials can be produced in a relatively small volume of the granular material.
The wound elements 5 can preferably have a ratio of maximum/minimum of the linear dimensions (L, B, H): max (L, B, H)/min (L, B, H) of at the most 2-3. These linear dimensions L, B, H of the wound elements can be 5-20 mm for most applications, wherein larger dimensions are also possible.
The wound elements according to the invention can basically comprise polymer material 2 of all types. The wound elements can advantageously be applied in thermoplastic manufacturing methods and accordingly comprise thermoplastic polymer material 2 of the known type, e.g. with thermoplasts such as polypropylene PP, polyamides PA, technical and high-performance polymers, new e.g. PCTG=polycyclohexandimethylenterphthalate etc. However, duromers such as epoxides EP, polyester UP etc. can also be applied as a polymer material 2 for the wound elements 5, depending on the application. Elastomers such as polyurethane, EPDM etc. can also be applied as polymer material 2.
One can achieve good mechanical characteristics with a fiber share of 10-70%, preferably 20-60% by weight and with fiber lengths f of more than 25 mm of the impregnated continuous fiber stands 3 in the wound elements 5, wherein fiber lengths of 200 mm and more are also possible depending on the application. As is known, glass fibers, carbon fibers, aramide fibers etc. can be applied as reinforcement fibers. The wound elements 5 apart from the impregnated continuous fiber strands 3 can also yet contain additional polymer material 2. Pure polymer material 2 can also be admixed to the wound elements as a granular material (with high fiber content) and thus the end fiber content in the component manufactured with this can be set.
a shows a part of an installation, analogously to
b shows an example of wound elements 5 in mixed form 53 with turns 6.1-6.4 which lie partly over one another and which can be manufactured with an installation according to
The general method for the continuous manufacture of granular materials from long-fiber-reinforced polymer material in the form of wound elements 5 comprises the following method steps:
(41) winding off a roving of continuous reinforcement fibers 1 and impregnating with molten or liquid polymer material 2 for forming an impregnated continuous fiber strand 3,
(42) winding the impregnated continuous fiber strand 3 in turns 6 lying over one another and/or next to one another, about a winding axis 23 for forming windings 6a,
(43) and thereby displacing the formed windings in the axial direction +x,
(45) solidifying the windings 6a during the further displacement in the axial direction +x,
(46) subsequent cutting through the solidified windings 6a at defined distances L and the formation of individual wound elements 5 by way of this.
Thereby, a rotating winding core 22 can be applied as a winding axis 23.
A particularly advantageous further formation of the method comprises a periodic forwards and backward movement of the winding core 22, as is represented in the
The method additionally comprises a movement (−x1, +x1) of the winding core 22, which oscillates in the axial direction, with the following steps:
(42) winding the impregnated continuous fiber strand 3 for forming a wound element 5.1 in a winding position 8.1 on the winding core, subsequently
(43) retracting −x1 the winding core 22 and, by way of this, advancing the already formed wound elements 5 on the winding core and subsequently
(44) advancing +x1 the winding core and, by way of this, releasing a new winding position 8.2 for the production of a next wound element 5.2
(45) solidifying the wound elements 5 with the further advance (+x) on the winding core
(46) cutting through the impregnated continuous fiber strand 3 and with this, the separation of the individual wound elements 5 from one another.
The method according to the invention is in particular suitable for the manufacture of thermoplastic, long-fiber-reinforced polymer material. Thereby, in the method step (41), the continuous reinforcement fibers 1 are impregnated with heated, molten thermoplastic polymer material 2 and in method step (45) the wound elements 5 are cooled on the winding core 22 and solidified by way of this. This is carried out in an installation according to
Instead of a metallic winding core 22 as part of the production installation, in a further method variant, one can also use a winding core 22a as a material to be consumed, which consists of the same thermoplastic polymer material 2 as the wound elements 5. Thereby, firstly a rod of non-reinforced or preferably reinforced polymer material 2 is formed or premanufactured, and subsequently in the cold, solid condition is used as a rotating winding core 22a for winding the molten, impregnated continuous fiber strand 3 and then in method step (46) is cut through together with the impregnated continuous fiber strand by the separating device 27. A piece of the polymer winding core 22a then together with the turns 6 form a wound element 5.
With the use of duromers or elastomers as a polymer material 2, cold-impregnated continuous fiber strands 3 are formed in the method step (41), and in method step (45) the wound elements 5 on the winding core 22 are solidified by way of heating and polymerisation.
a winding-off unit 11 for a roving of continuous reinforcement fibers 1, a subsequent melt (molten mass) feed 13 of thermoplastic polymer material 2 and a melt and impregnation device 12 for forming a molten, impregnated continuous fiber strand 3,
a winding device 18 with a winding core 22 for winding up, cooling and solidifying the impregnated continuous fiber strand 3 and for forming wound elements 5 with more than one turn 6 and turns 6 lying over one another and/or next to one another,
with a rotation motor 20 for the drive of the winding core 22 with a cooling device 19 (e.g. a water cooling)
and with a linear drive 30, with which the winding core 22 can be moved in the axial direction in an oscillating manner (−x1, +x1)
for retracting −x1 the winding core 22 and by way of this, for advancing the formed wound elements 5 on the winding core
and for the subsequent advance +x1 of the winding core, and by way of this release of a next winding position 8.2 for winding a next wound element 5.2,
with a cooling device 17 for cooling and solidifying the wound elements 5 on the winding core
and with a separating device 27 for separating the individual solidified wound elements 5 as well as with a control 35 of the installation.
The installation of
a, b in a part of the installation according to
a, b schematically illustrate a manufacture of wound elements with (spiral-shaped 52) turns 6.1-6.3 which lie next to one another, in an installation according to
c schematically illustrates a wound element 5 in mixed form 53 manufactured in an installation according to
a, b shows the manufacture of wound elements with turns 6.1-6.4 which in a combined manner lie over one another and next to one another. According to the course of s22(t), after the retraction (43), a first advance (44) and winding (42) of the turn 6.1 is effected, thereupon then the winding of the turn 6.2, then a second advance (44) and winding of the turn 6.3 (next to the turn 6.1), then winding the turn 6.4 onto the turn 6.3, then refraction again (43) etc.
a, b show a manufacture of wound elements (53), with turns 6.1-6.6 lying over one another and next to one another. Here, the position of the running-in, impregnated continuous fiber strand 3 within the released winding position 8 can be additionally displaced by way of guide plates 24, 24.2 adjustable in the x-direction, as this is shown in
a-d show examples of winding cores 22 in cross section. The winding must be effected in the plastic (molten) condition. A high friction value in the radial direction is desired for transmitting the necessary tension force for winding from the winding core 22 onto the impregnated continuous fiber strand 3, and an as low as possible friction value is desired in the axial direction for advancing the wound elements. For this, the winding core 22 can have a suitable shaping, e.g. with grooves 32 according to
The surface can comprise a smooth, wear-resistant, hard coating, e.g. of titanium carbide, for improving the friction values and for minimising wear. The winding cores for the purpose of a good cooling consist of metal with a good thermal conduction, e.g. of brass. A particularly good cooling effect can be achieved with hollow winding cores according to
a, b illustrate the resulting much greater fiber lengths f in an injection moulded part which is manufactured with wound elements according to the invention, in comparison to granular material until now. Both samples are manufactured with a small injection moulding installation with only 35 mm screw diameter:
a with 10 mm LFT-rod granular material with 30% fiber share,
The figures show the large difference in the fiber lengths:
a, 20b show a multiple-installation for the series manufacture of the wound elements 5 with a high production performance and productivity with a reduced spatial requirement and energy consumption. Thereby, simultaneously, several (e.g. 50) continuous fiber strands 3i are separately fed, wound off, impregnated (28i), in each case wound onto a rotating winding core (22i), advanced thereon, solidified and separated into individual wound elements 5i. This is analogous to the installation of
The winding cores 22i are additionally refracted (−x1) in step 43 and advanced (+x1) in step 44 with a multi-installation according to
This method for the simultaneous manufacture of wound elements 5 of several impregnated continuous fiber strands 3i runs as follows:
(41) -separately winding-off several continuous fiber rovings 1i from winding-off units 11i and their impregnation with molten polymer material 2 in an impregnation tool 28 with several impregnation locations 28i,
(42) -winding up the impregnated continuous fiber strands 3i in each case about a rotating winding core 22i,
(43) -retracting −x1 and
(44) -advancing +x1 of the several winding cores 22i by way of a linear drive 30,
(45) -cooling and solidifying the windings and separating by way of a multiple separating device 27i, into individual wound elements 5i.
With this, one can process very many fiber strands 3i (e.g. 50) into wound elements 5i in a simultaneously rational manner with only one extruder 13, a melt device 12, a multiple impregnation tool 28i, a linear drive 30, a multiple cooling device 17i and a multiple cutting device 27i.
A component and a method for manufacturing a component of fiber-reinforced polymer material can be manufactured in a shaping process with wound elements 5 according to the invention. Such shaping processes, e.g. are formed by injection moulding, extruding, pressure extrusion, etc. Thereby, the wound elements with regard to shape, type and size can be mutually matched and optimised to the shaping processes and the shaping installation.
Essential advantages which are achieved with the continuously manufactured wound elements according to the invention as granular material by way of their construction and shaping are e.g.:
With this, significantly better mechanical characteristics of the manufactured components, particularly injection moulded parts, with regard to strength, stiffness and impact strength can be achieved. In particular, with existing shaping installations, e.g. with smaller injection moulding machines with small screw diameters
1. much greater fiber lengths of the wound elements can be processed and
2. with this, much greater fiber lengths in the component can be achieved.
The following reference numerals have been used in the framework of the description:
Number | Date | Country | Kind |
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1306/09 | Aug 2009 | CH | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CH10/00204 | 8/23/2010 | WO | 00 | 2/17/2012 |