Patent Application
20200086591
The present invention relates to an injection box for a pultrusion system, wherein the injection box comprises:
The invention further relates to a pultrusion system with such an injection box and a fibre-reinforced plastic profile, in particular plastic rod, which is produced by means of such a pultrusion system.
Fibre-reinforced profiles in the form of elongated rods are used as reinforcement during construction. Here, for example, glass fibres are used, which are bonded with a vinyl ester resin. Compared to conventional reinforcement rods made of steel, they offer not only the advantage of a distinctly lower weight, but—in contrast to steel—they are also corrosion-resistant and can therefore be used in chemically aggressive environments. In addition, glass fibres—unlike steel—are not electrically conductive and a non-magnetic, so that corresponding reinforcement rods are suitable for the construction of housings and bases of high energy systems, e.g. switching systems, steelworks, aluminium smelters, electrical substations etc.
Such fibre-reinforced plastic rods can be produced in different lengths, also endlessly, by pultrusion.
Pultrusion or continuous drawing is a method known for several decades for the continuous production of endless, fibre-reinforced plastic profiles with a uniform cross-section. Here, fibres, which are combined into bundles, so-called rovings, are impregnated with a thermosetting or thermoplastic matrix material, for example polyurethane or epoxy resin, and are subsequently cured in a curing tool to form a fibre-reinforced plastic profile, mostly through a heat treatment. The fibres can be, in particular, glass, carbon, basalt or aramid fibres.
In the most prevalent pultrusion systems, the rovings are drawn by means of a drawing unit, a so-called puller, over deflection rollers through an open impregnating bath, which is filled with liquid matrix material. Following the open impregnating bath, the impregnated rovings enter into the curing tool, which usually comprises one or more heat chambers. Such pultrusion systems with an impregnating bath are used for the production of fibre-reinforced plastic profiles with different cross-sections and in particular also for the production of the mentioned elongated reinforcement rods.
To achieve a greater throughput, basically also pultrusion systems have been known for a few years in which the rovings are drawn without deflection through an injection box. The latter conventionally comprises a housing with at least one slit-shaped fibre supply opening for supplying the fibres at a front end of the housing in the direction of movement of the fibres, and an injection connection, provided on the housing, for injecting a liquid matrix material into the interior of the injection box. While the fibres are drawn by the drawing unit through the injection box, they are impregnated there with the pressurized liquid matrix material. The impregnated fibre portions leave the injection box through a slit-shaped delivery opening at a rear end of the housing in the direction of movement of the fibres, in order to subsequently enter into the curing tool.
Pultrusion systems with an injection box are used hitherto substantially for the production of fibre-reinforced plastic profiles which are composed from one or more plate-shaped sections. This is due to the hitherto available geometries of the injection boxes, in particular their slit-shaped supply- and delivery openings. A production of rod-shaped plastic profiles is hitherto not possible with such pultrusion systems.
It is therefore the object of the present invention to propose an injection box for a pultrusion system which also enables the production of rods.
According to the invention, this problem is solved in a generic injection box for a pultrusion system in that the delivery opening has a substantially circular cross-section. The impregnated fibre sections then leave the injection box in the form of an endless string with a circular cross-section, which can be cured in the subsequent curing tool to form an endless rod. The latter can then be cut into rods with the desired length by a conventional saw, in particular a so-called flying saw.
The delivery opening can be provided directly on the housing or on a calibration attachment which is able to be connected to the housing. In the first-mentioned case, the delivery opening is, as it were, a circular hole at the downstream rear end of the injection box in relation to the direction of movement of the fibres. In the last-mentioned case, a special calibration attachment is connected, for example by screwing, to the housing of the injection box at the downstream end. The fibres which are impregnated with matrix material then leave the housing of the injection box in the region of the connection site, enter there into the screwed-on calibration attachment as the rearmost part of the injection box, and leave the latter through a circular delivery opening. The particular advantage of this configuration lies in that by means of a set of several calibration attachments with delivery openings of different sizes, which for example can all be screwed into the same thread at the downstream end of the housing of the injection box, different diameters of the rods which are to be produced can be realized.
Preferably, in the injection box according to the invention provision is made that also the fibre supply opening has a substantially circular cross-section. This facilitates the uniform guidance of the fibres in the cavity within the injection box in the direction of the substantially circular delivery opening.
If here, in addition, the diameter of the fibre supply opening is greater than the diameter of the delivery opening, it is ensured that the fibres are compressed simultaneously in radial direction during the impregnating with matrix material in the cavity, which improves the stability of the rod which is to be produced.
In such an injection box according to the invention, provision can be made that a cross-section of a cavity in the housing of the injection box decreases substantially continuously from the fibre supply opening to the delivery opening. This leads to a further improvement and facilitation of the uniform guidance of the fibres in the cavity.
Alternatively, however, it is also conceivable that a cross-section of a cavity in the housing of the injection box increases from the fibre supply opening up to an intermediate position in the in the housing, and decreases from the intermediate position to the delivery opening, wherein then advantageously the intermediate position is to correspond to the position of the injection connection. Such a configuration improves the supply of the cavity in the interior of the injection box with matrix material, in particular at high throughputs.
In simple embodiments, the injection box according to the invention comprises a single cavity, however it is also possible according to the invention that a first plurality of cavities is provided in the housing of the injection box, substantially orthogonally to the direction of movement of the fibres. This increases the throughput of the entire pultrusion system in which such an injection box according to the invention is installed, because several endless strings of impregnated fibres can be produced simultaneously, over one another or adjacent to one another depending on the arrangement of the several cavities, and which are subsequently cured to form rods in a shared curing tool or in several curing tools, which are likewise arranged over one another or adjacent to one another.
In such an injection box according to the invention, the several cavities can be supplied with matrix material via a single injection connection. For this, the several cavities must be connected to one another, so that the liquid matrix material can flow from the single injection connection into all the cavities. Preferably, however, provision is made that a second plurality of injection connections is provided on the housing, wherein then expediently the first plurality is identical to the second plurality, so that an injection connection is assigned to each cavity. Hereby, a uniform supply of all cavities with matrix material is guaranteed, wherein all the injection connections can be supplied from a shared matrix material tank.
The invention further relates to a pultrusion system for the production of fibre-reinforced plastic rods which comprises an injection box as described above.
In a particularly expedient embodiment for the production of reinforcement rods, such a pultrusion system further comprises a winding device, which is designed to wind winding fibres and/or a winding band onto the fibres, which are impregnated with the matrix material, after their exit from the delivery opening of the injection box. In this way, an additional structure is applied onto the outer surface of the fibre-reinforced plastic rods, which enlarges the surface of the rods. Therefore, a larger contact surface is created for connection with the concrete which is to be reinforced, in order to increase the tear-out torques from the concrete.
In such a pultrusion system according to the invention, the winding device is expediently arranged before the curing tool in the direction of movement of the fibres. Therefore, the winding fibres and/or the winding band are wound onto the still damp fibres which are impregnated with matrix material, so that they can also become saturated with matrix material and, in the subsequent curing tool, enter into a secure connection with the fibre-reinforced plastic profile onto which they were wound.
In an advantageous configuration, the winding device is designed to receive at least one spool with winding fibres, wherein the winding fibres are preferably provided as a twisted roving. By the winding of the plastic rods with a twisted roving, it is ensured that the enlarged contact surface to which the concrete which is to be reinforced is to engage, has a particularly high stability, in order to permanently increase the tear-out torques from the concrete.
In order to keep the number of required starting materials as small as possible, the winding fibres and the fibres impregnated with the matrix material are expediently made from the same fibre material.
In a further development of the pultrusion system according to the invention, the winding device is designed to wind various types of winding fibres adjacent to one another onto the fibres, which are impregnated with the matrix material, after their exit from the delivery opening of the injection box. The various types can differ from one another according to the precise purpose of use of the reinforcement rod which is to be produced and of the concrete which is to be reinforced with regard to its material and/or with regard to the diameter of the respective rovings and/or with regard to further characteristics.
Basically, the winding device can comprise at least one rotary arm, which is able to be driven for rotation about a rotation axis which runs through the delivery opening of the injection box and substantially parallel to the direction of movement of the fibres which are impregnated with the matrix material. In particular in embodiments which are designed for the winding of various types of winding fibres adjacent to one another or respectively for the winding of winding fibres and of winding band adjacently or onto the winding fibres, the winding device can comprise several rotary arms.
In a further development, the pultrusion system according to the invention can comprise, furthermore, a pre-forming unit arranged before the fibre supply opening in the direction of movement of the fibres, which is designed to apply liquid matrix material onto the fibres before their entry into the injection box. Hereby, a particularly uniform wetting of the fibre rovings can be achieved, which are still spaced apart from one another in the region of the pre-forming unit and can therefore be reached by matrix material from all radial directions before they are compressed after entry into the injection box.
Here, the pre-forming unit can be designed to apply the liquid matrix material in a pressureless or pressurized manner onto the fibres. With a pressureless application, the matrix material can, for example, be dripped onto the fibre rovings. A pressure application requires a pre-forming unit which is substantially closed except for the openings for the entry and exit of the fibre rovings.
The invention further relates to a fibre-reinforced plastic profile, in particular a plastic rod, which is produced by pultrusion using a pultrusion system as described above.
Embodiments of the invention will be explained below as non-restrictive examples with the aid of the figures. There are shown herein:
The drawing function is exerted by a drawing unit, a so-called puller, which is likewise not illustrated on the right in the figure. The direction of movement of the fibre rovings 14 is from left to right in
On one side of the housing 18, an injection connection 20 is provided for injecting a liquid matrix material 22. In the interior of the housing 18 of the injection box 10, the rovings 14 are therefore acted upon pressure with the liquid matrix material 22 and are impregnated. The impregnated rovings 14 are drawn out from the injection box 10 through a delivery opening 18B on the right-hand side of the housing 18 in
The fibre supply opening 18A and the delivery opening 18B are configured so as to be slit-shaped in such conventional injection boxes 10, as vertical slits in the case shown in the side view of
In the embodiment of
In the embodiment of
In the embodiment of
In the embodiment of
In the embodiment shown in
From the same tank, not illustrated in the figure, matrix material 22 can also be directed via a pre-forming unit supply line 28 to the four pre-forming units 16, in order to drip down there onto the fibre rovings 14, before they are drawn into the injection box 10. In this way, the rovings 14 can be acted upon all around with liquid matrix material 22, before they are compressed in the respective cavity 18C of the injection box 10. Therefore, it is ensured that the rovings 14 are not only wetted by matrix material 22 on their exposed outer side, but over their entire circumference, which improves the complete as possible impregnating of the rovings 14 with matrix material 22.
In the embodiment shown in
In this pultrusion system 12 according to the invention, a winding device 30 is arranged between the delivery opening 18B, provided directly on the housing 18, of the injection box 10 and the curing tool 24. The winding device 30 is illustrated isolated in perspective in
While the fibres 14, impregnated with matrix material 22, are drawn by the puller out from the delivery opening 18B of the injection box 10 and through an opening in the rotary arm 34 in the region of its rotation axis, they are immediately subsequently wound by the winding device 30 with the twisted roving 38. In the diagrammatic illustration of
As shown in
By providing a further spool 36 on the rotary arm 34, for example at the other end of the rotary arm 34, two twisted rovings 38, for example of different materials, can be wound adjacent to one another onto the fibres 14 which are impregnated with matrix material 22. If applicable, the winding device can also have several rotary arms 34, in order to carry further spools 36 with twisted rovings 38 and/or with a winding band, which are to be wound adjacent to one another or on one another onto the fibres 14 which are impregnated with matrix material 22. In particular a continuous winding with a winding band which is electrically insulating or is shielding electromagnetic waves can be of importance when the produced fibre-reinforced plastic profile is provided with electrically conductive fibres 14 in its interior and/or with electrically conductive rovings 14 on its outer surface for signal transmission or current conduction.
Such possibilities for use of a fibre-reinforced plastic profile 40 according to the invention will be described below with the aid of
The fibre-reinforced plastic profile 40 in the form of a rod comprises a cured plastic matrix of matrix material 22, into which a roving, i.e. a bundle of glass fibres 14 is embedded. In the embodiment which is shown, the glass fibres 14 run substantially centrally along a longitudinal centre axis of the plastic matrix. Such a central arrangement of the fibres 14 can be achieved without difficulty during production by pultrusion. A decentralized embedding of the glass fibres 14 into the plastic matrix parallel to the longitudinal centre axis of the plastic profile is, however, likewise possible, for example by displacement of the pre-forming unit 16 which is used. The illustrated fibre-reinforced plastic rod 40 can be used as a reinforcement rod in the erecting of buildings and, owing to the light-conducting characteristics of the glass fibres 14, permits at the same time a use as a data line for optical communication. In the case of incomplete curing in the curing tool 24, the fibre-reinforced plastic profile 40 illustrated in
Finally,
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 106 940.2 | Mar 2017 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/056983 | 3/20/2018 | WO | 00 |
