Patent Application
20100297277
The instant application should be granted the priority dates of May 22, 2009, the filing date of the corresponding German patent application 10 2009 022 370.3.
The invention relates to an extrusion device.
An extrusion device with the aid of which threads are encased by rubber material and are extruded therewith has been known for a long time, for example from U.S. Pat. No. 2,760,230 or GB 950 741. With solutions of this kind, wires or threads are fed to a nozzle with the aid of a thread guide, and between the thread guide and the nozzle rubber material enters the region of the threads, thus encasing the threads. Solutions of this kind have been employed and are employed in various forms.
With the manufactured article it is important to have a sufficient anchorage or mounting of the threads in the extrusion material in order to achieve the desired effect. Indeed, the diameter of the threads could be reduced and thus the contact surface relating to the weight of the threads could be considerably increased. Very thin threads, however, may only be poorly guided through the extrusion nozzle and in some case are unsuitable, too, for example if a certain rigidity or stiffness of the manufactured article is to be achieved by means of the threads.
In order to increase the anchorage or mounting with given thread diameters it has been proposed to carry out a surface roughening of the threads. This is comparatively complex and costly and also only possible with some thread materials. Moreover, it would be desirable to be able to manufacture different products with the same extruder.
An improvement in this respect can be taken from DE-C2 28 13 217. This document represents a solution, with the aid of which the thread guide may be shifted or displaced relative to the nozzle such that an adaptation to the intended combination of rubber, thus substantially to the temperature and therewith to the viscosity thereof, and to the thread used, thus the thread material and the thread thickness, is possible.
This solution, however, is not entirely satisfactory if a quick refitting for different products to be extruded is to be provided.
A further problem is the fact that the threads often break. With twisted filaments, the breakage of a single filament is comparatively less critical if the filaments are well embedded in the rubber compound. In the case of a monofilament, however, or in the case of polyfilaments that are relatively poorly fixed to one another and that each are subject to separate tensile loads, this is critical and it must be ensured that the filaments of the thread meet the no-break criterion in the manufactured article.
An essential reason why a change and a new introduction of the product to be extruded is often not effected, although this would be displayed despite a breakage of the thread or filament, is the difficulty to newly load the thread guide, especially if many single filaments or threads are existent.
This, for example, may be carried out by having the extrusion head run empty and by pulling out from behind and reloading the thread guide after having loosened the respective screws.
In this respect, the invention is based on the object of producing an extrusion device of the aforementioned type which enables an improved handling even in the case of a breakage of the thread such that there is an enhanced possibility to carry out a refitting of a reinforcing material feeder in the case of a possible thread breakage.
This object is inventively solved by an extrusion device that comprises an extruder screw for conveying extruder material, in particular natural or synthetic rubber materials; a nozzle having two nozzle dyes that are displaceable relative to one another; and a reinforcing material feeder for conveying reinforcing material in the direction of the nozzle, via which nozzle reinforcing material and extrudable material are discharged together from the extrusion device, wherein the reinforcing material is guided in a horizontal plane of separation.
According to the invention it is particularly favorable to open the possibility of making the reinforcing material feeder accessible by separating the nozzle dies and for example of markedly easily replacing broken filaments. Surprisingly, a notedly high pressure for the extrusion head may be employed nevertheless, offering special advantages with respect to the adherence of the rubber compound to the surface of the filaments or to the reinforcing material, such as load-carrying cords. For this reason it is possible without further ado to provide a pressure of for example 400 bar within the feed or supply region for the extrusion compound, that is to say in the region between reinforcing material feeder and nozzle. Such a pressure allows to take advantage of the microroughness of the surface of the filaments and allows penetration of parts of the rubber compound at this location. The surface effects produced in this manner considerably increase the adherence such that a large contact surface of the reinforcing material may be exploited.
The extrusion device according to the invention allows with simple means to make adjustable the relative position of the reinforcing material feeder to the nozzle. In this way, the remaining free space may be adapted to the requirements, for example the nature and condition of the reinforcing material, to a large extent.
By moving apart the nozzle dies it is possible to mount the reinforcing material feeder in a freely accessible manner, whereas both simple repositioning and a machine process are possible.
It is preferred that the reinforcing material feeder is then held in position by the pressure of the nozzle dies on top of one another such that a manual adjustment device for the positioning of the reinforcing material feeder is not loaded or stressed by the extrusion pressure.
It is also possible in this connection to locate specific positions with the aid of a grid such as a corrugation or ribbing.
It is preferred that the flow to the reinforcing material feeder occurs laterally from the outlet of the extruder screw. Through this, the rubber or a different extrudable mass laterally impinges on the reinforcing material. With the aid of a horizontal variable position of the reinforcing material feeder, the different flow length or duration may be compensated so that despite a drop in pressure, a uniform exit speed with several products that are generated in parallel, is feasible.
According to the invention it is particularly favorable if cords are used as reinforcing material. If a cord breaks or ruptures during the production, the cords can be rapidly changed due to the fact that the reinforcing material feeder can be easily released according to the invention.
A further advantage of the inventive extrusion device is the ease of exchangeability of the nozzle inserts. Due to the dispartment or separateness and the relative movability of the nozzle dies relative to one another, the nozzle insert may be changed rapidly in the usual manner and may thus be adapted to the desired shape of the product to be extruded.
According to the invention it is also possible to arrange a plurality of nozzles and correspondingly associated nozzle dies next to one another. The upper nozzle dies as well as the lower nozzle dies may then preferably be connected to one another, respectively, whereas they may be realized in one upper nozzle carrier. The nozzle carriers may then be movable relative to one another whereas the direction of movement is preferably vertical so that all upper nozzle dies may together be separated from all lower nozzle dies.
According to the invention it is particularly favorable if the nozzle dies are substantially of semi-circular shape in order to receive or accommodate a nozzle insert. The nozzle insert is then changeable and provides the nozzle slot having the respective suitable shape. With the aid of a form-fit mounting known per se of the nozzle inserts in the nozzle dies, the high extrusion pressures may be absorbed without further ado.
The drive device according to the invention inventively keeps the nozzle dies tightly on top of one another during the extrusion process. In order to support the pressing or forming pressure of the drive device in the closed condition of the extrusion device, a strong electromagnet may be provided for example that is switched on during the extrusion and that is switched off during the movement of the nozzle dies, in particular for separating the nozzle dies from one another, or a combination of a stud and a nut.
It is to be understood that the drive device may be embodied in any suitable manner. Preferably, the drive device is embodied with a least one hydraulic cylinder that allows rapid opening and closing of the nozzle dies.
According to the invention it is provided that the discharge or exit direction of the reinforcing material feeder runs transversely to the axis of the extruder screw, in particular substantially at right angles thereto.
According to the invention it is provided that the discharge or exit direction of the reinforcing material feeder passes through the nozzle, in particular is arranged coaxially thereto.
According to the invention it is provided that the nozzle comprises a nozzle insert that is surrounded by the nozzle dies and that in particular forms a nozzle slot.
According to the invention it is provided that the nozzle dies in the closed condition of the extrusion head surround the nozzle insert in an annular manner.
According to the invention it is provided that two nozzles are arranged next to one another that comprise nozzle dies, whereas the upper nozzle dies are collectively displaceable relative to the lower nozzle dies.
According to the invention it is provided that a drive device is formed within an extrusion head of the extrusion device, via which an upper nozzle carrier may be separated from a lower nozzle carrier, whereas said drive device in particular operates in a hydraulic or pneumatic manner.
According to the invention it is provided that the reinforcing material feeder may be released or unblocked by separating the nozzle dies from one another.
According to the invention it is provided that the reinforcing material feeder is formed in two pieces and is comprised of a lower and an upper part, with said parts being able to be pressed on one another by bringing together the nozzle carriers via a drive device.
According to the invention it is provided that the separation or dispartment of the nozzle dies takes place in a horizontal direction, and the drive device for the nozzle carriers of the nozzle dies acts in a vertical direction.
According to the invention it is provided that the active surfaces of the nozzle carriers facing one another, thus in particular the exposed surfaces facing one another, are formed without protrusions or undercuts, and in particular no screws, bolts, etc. extend between the nozzle carriers apart from the drive device for the nozzle carriers.
According to the invention it is provided that a free space is formed between the reinforcing material feeder and a nozzle insert of the nozzle, said free space extending around the reinforcing material.
According to the invention it is provided that a free space that is formed between the nozzle insert and the reinforcing material feeder completely surrounds the reinforcing material and in particular, if represented in section, is formed such that it substantially runs towards a nozzle slot in a V-shape.
According to the invention it is provided that the decrease or drop in pressure with a lateral oncoming flow towards the nozzles through the extruder screw is compensated with the aid of fluidic means.
Further advantages, details and features emerge from the following description of an embodiment of the invention in connection with the drawings, in which:
The extrusion device 10 represented in
In the closed condition of the nozzle dies 14 and 16, the nozzle carriers 18 and 20 incidentally lie flat on top of one another. In the embodiment shown, additional studs or screw bolts 28, 30 with respective nuts 32 and 34 are provided for the safe closing of the nozzle carriers 18 and 20 relative to one another, with the aid of which studs and nuts a fixation of the nozzle carriers 18 and 20 to one another is realized. It is to be understood that instead of these means, any other fixing means may be provided and that it is also possible to ensure the closed condition of the nozzle 12 in any other manner.
As can be seen in
As is apparent from
In
Laterally adjacent to the reinforcing material feeder 60, the extruder screw 70 is formed that enables to evenly fill the free space 72 between the reinforcing material feeder and the nozzle insert 22 with natural or artificial rubber and hence to encase the reinforcing material.
In the closed condition of the nozzle carriers 18 and 20, the reinforcing material feeder 60 is pressed together at a given position so that the parts thereof firmly rest on one another.
It is obvious that the reinforcing material feeder 60 is freely removable and exchangeable in the represented condition according to
The specification incorporates by reference the disclosure of German priority document 10 2009 022 370.3 filed May 22, 2009.
The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 022 370.3 | May 2009 | DE | national |
