DE1529774B2 - DEVICE FOR REGULATING THE BACK PRESSURE BETWEEN TWO TWIN-SPINDLE EXTRUDERS LOCATED BEHIND EACH OTHER - Google Patents

Description

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The invention relates to a device for changing the reflux cross-section between the collar and the annular groove

control of the back pressure between two in a row (German Auslegeschrift 1 201 041).

arranged multi-spindle extruders with a simple flow rate regulation with one

Throttle block on the deflection head housing the first wall-free kneading effect can also be achieved thereby Extruders. 5 that between the high pressure zone after the

The types of screw presses or extrusion filling opening and the low pressure zone after discharge

dera, whose essential work tools are used to attach a throttle point to extruders

Hch single or multi-spindle, in engagement with one another, which has an annular passage space for the

Standing screws are the masses released in a cylinder that is opposite to one another

close axially more or less tightly and equally conical surfaces on the screw and a cylinder

Rotating sensibly or in the opposite direction are quite less limited. The cross section of the annular

manifold. This work-through space is also used in this case

machines mainly in the chemical tech- axial displacement of the screw changeable (German

Technology to an increasing extent for a variety of see interpretation 1099 996).

Purposes, e.g. B. for the constant processing of highly viscous 15 for difficult to process plastic masses

However, the well-known throttle options are sufficient for separating liquids or gases

moderate media made of plastic material or for kneading are not sufficient to produce a product of perfect quality

and / or mixing viscous, powdery to achieve. That's why you already have a second one

or granular plastics. Throttle point in the conveying path of the plastic mass

For the quality of the extruded intermediate products 20 seen, so that the mass pressure in a further is a good kneading and mixing of the plastic area on the particular plastic to be processed mass can be tuned in addition to uniform heating through; Both throttle points sii \ d External heat is sucked in from the outside and one centrally from the end of the snail through the bed Friction in the plastic generated heat service man adjustable and decisive at all passage. The inevitable promotion of the artificial constrictions is the connection of a pressure measuring device mixture conditionally a regular expulsion lines provided with a drive device and the joint kneading work of the screws must be of some kind in such a way that in deliver good plasticizing performance. The tightness depends on the pressure readings the Drosseides The drawn plastic strand will thereby be controllable.

aims that the material inside the extruder 30. There are also extruders known that in stages pressures as high as possible are sufficiently offset in the cross section of the screw tip will. have adjustable annular gap, so that by axial

Depending on the type of mass to be processed, a displacement of the screws must reduce the throttling effect

more or less strong kneading effect can be achieved, achieving the required melt pressure set

to achieve perfect homogenization. 35 can be. In the case of difficult-to-process art

A change in the kneading and / or mixing effect allows substances to be sufficient, however, these known Drosselmög-

It is well known that replacing the snails does not result in a flawless product

or snail sleeves against those with one to achieve.

Achieve different delivery volumes of their gears with the same Despite precise control of the pressure conditions at the speed of the worm shaft. In addition, 4 ° of the processing of the common plastics are made, a high kneading and mixing action can be achieved in the common extruder for a perfect homoderm way that the mass to be processed is generated from materials with strong scattering and when passing through the extruder brake-changing influencing variables, such as B. bulk weight, send threaded parts pressed in the conveying direction. The threaded parts, as throttle elements 45, increase the dwell time of the mass in the extruder as throttle elements 45 and stabilizer additions, along with other two, which means that they are not universally usable. Thereto an improvement en% kneading and mixing effect changes nothing which, using several Extrueinhergeht. The intensity of this effect on the one behind the other or at an angle to one another, pressed material increases with increasing back pressure and are arranged separately or by a * the mouthpiece. Be driven together by a single point in front of the input 5 °. Opening of the mouthpiece arranged pressure flow- In such duplex machines usually pushes the regulating valve, one has already tried to ensure a machine its working mass over a connection predetermined mass back pressure after overcoming connection nozzle in the downstream machine equal to a certain delivery pressure. Art. This connecting channel between two aggregates - The evenly high back pressure in front of the mouth - 55 is already part of the general conveyor technology, a flawless product should be used for a long time for special purposes. So stigen. does he z. B. to accelerate separation

Another suggestion for achieving a connection was to a vacuum or cone gradual compression aims at that capacitor line or is itself as a vacuum container Screws or rotor bodies formed one or more 60 th. In the relevant technology of the stowage sections show, which from one the snowworking of plastic masses one already has in the kanggang interrupting ring-shaped collar and transition between two successive extruders in the area of this federal ring provided a controlled passage device, namely exist in the cylinder. As a result of the transverse valve provided by a rotary valve through which a precut constriction Caused congestion is the 65 rush of mixture components from the first Ma plastic mass condensed. In the case of a single-screw extruder, this should be prevented so that this can be achieved by additional axial displacement of the mixture only in the bound state into the second Rotor body reaches the cylinder of the through machine. By depending on the

Claims (5)

Filling volume of the second machine-controlled rotary valve, the processing stage in this machine is fed in such a way that the continuity of the mass flow to the rotor bodies of the second machine is guaranteed. Long-term observations, extensive experiments and investigations have shown that the back pressure in the working cylinder largely influences the plasticization and homogenization of the plastic compound, but counteracts the ejection of the screw. Finally, it is known to provide a throttle block in a plane to the discharge nozzle of an extruder (British patent specification 978 331). With this equipment of the extruder, however, is associated with the serious disadvantage that the throttle mandrel is in the high pressure zone. At the high pressure build-up, e.g. B. up to 500 atmospheres, which can result from a narrow gap position of the throttle cone, the plasticized plastic compound can penetrate into the fit of the throttle pin and in this way practically switch off any elastic control option. The fixation of the plastic in the standard gap, however, easily leads to deterioration and to the decomposition of the plastic. The invention is based on the object, when using two multiple extruders with a throttle block on the circulating head housing, to regulate the back pressure in such a way that the above-mentioned disadvantages no longer occur. This object is achieved according to the invention in such a way that the throttle block with its axially adjustable throttle mandrel is in the same plane as the plasticizing screws of the first extruder and protrudes into the discharge channel of the same extruder with the cone of the throttle mandrel to form the regulating gap. In the case of an additional arrangement of a screw nut for changing the width of the regulating gap, the throttle mandrel is expediently guided in a longitudinally movable manner in a sleeve designed in the form of a blade. The screw nut is advantageously supported against disc springs. A load cell is provided to display the spring deflection and a scale is provided to display the width of the regulating gap. In the subject matter of the invention, the sensitive and plasticized plastic strand is continuously widened in a flow-like manner from the tip to the ring in the hollow cone in a flow-like manner. The mass to be processed is ejected into the screw conveyor of the following extruder without dead corners. Finally, the viscosity and the coefficient of friction between steel and plastic should be given special consideration in the case of channel constrictions and strong diversions. The homogeneity of the plastic mass is better guaranteed with the subject of the invention than with the known extruder types, the back pressure in the working cylinder of the first extruder, which has to plasticize the mass, is regulated, so that the second extruder only has the task of removing sensitive plasticized material for a short time Ways to expel. The variables affecting the back pressure are essentially composed of the discharge quantity, the viscosity and the coefficient of friction of the mass. By mechanically regulating the back pressure with the aid of the throttle block and its throttle mandrel arranged according to the invention, the technical advantage is achieved that the regulation of the back pressure within the first extruder A at the same time optimally influences its plasticizing performance. When processing z. Experience has shown that, for example, polyvinyl chloride is very sensitive to the melt after it leaves the extruder. Any excessively strong throttling would lead to excretions or burns in this state of aggregation. Furthermore, the back pressure can easily be measured at any stage of the kneading or mixing process and can be regulated automatically as a result of the disc spring arrangement. The possibility of reading off the gap setting makes the operation of the entire machine much easier. The influencing variables of the batches of material can now be largely eliminated by the easy mechanical operation of the throttle mandrel arranged according to the invention, which is accompanied by greater work performance and the achievement of a flawless plasticized material. In the drawing, an embodiment of the throttle mandrel is shown in section. The two multi-spindle extruders can be seen, namely extruder A for plasticizing the plastic compound and extruder B for ejecting the plasticized material to be pressed. The two extruders are arranged one behind the other in such a way that the rear part of the working cylinder of the extruder A is located above the front part of the working cylinder of the second extruder B. Both working cylinders are firmly connected to a distribution gear of known type (not shown). The two pairs of worms are - as usual - coupled directly to the gearbox and are preferably speed-dependent from one another. Between the two extruders is the deflection head housing 1 with the discharge channel 1 α. The throttle block is attached to the deflection head housing by a flange 8. The throttle block is divided essentially into a blade-shaped sleeve 3 in which the throttle mandrel 2 is guided, the tip of which blocks the discharge channel 1 α depending on the prevailing operating conditions. The adjustability of the throttle mandrel 2 takes place by means of the screw nut 4, which rests against the plate springs 5. The load cell 6 shows the existing pressure on the throttle mandrel, while the scale 7 shows the size of the gap width. A vacuum connection is provided in the area of the conveying channel 9. Paterite claims: 1. A device for regulating the back pressure between two multi-spindle extruders arranged one behind the other with a throttle block on the deflection head housing of the first extruder, characterized in that the throttle block with its axially adjustable throttle mandrel (2) lies in the same plane as the plasticizing screws of the first extruder (A) and to Standard gap formation with the cone of the throttle mandrel (2) protrudes into the discharge channel (la) of the same extruder (A) . 2. Apparatus according to claim 1 with a nut for changing the width of the Control gap, characterized in that the throttle mandrel (2) is designed in the form of a blade Sleeve (3) is guided longitudinally. 3. Device according to claims 1 and 2, characterized in that the screw nut (4) is supported against disc springs (5). 4. Apparatus according to claim 3, characterized in that indicates that a load cell (6) is provided to display the spring travel. 5. Device according to claims 1 to 4, characterized in that a scale (7) for Display of the width of the conical standard gap is provided. 1 sheet of drawings