DE1271973B - Continuously working screw press for thermoplastics with extremely low bulk weight - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

B29f

German Kl .: 39 A4 3/00

Number: 1 271 973

File number: P 12 71 973.2-16 (B 70077)

Filing date: December 20, 1962

Open date: 4th July 1968

The invention relates to a continuous screw press for thermoplastic Plastics of extremely low bulk density, especially for waste products, consisting of a heated screw cylinder with. Feed opening for the goods to be processed as well as a circulating one Screw with different, strongly conically enlarged at the filling end and in the conveying direction decreasing land height, at which the outer diameter of the screw within the filling and feed zone is tapered to a fraction of its initial size and this reduced diameter size remains almost constant in the subsequent melting zone.

For the recovery of the starting materials of fiber, foil and similar waste is already it has been proposed to chemically restore this waste to the monomeric state or at least partially dismantle and then close again in the same operation condense to obtain the polymeric state of the starting material. The ones obtained in this way Polycondensates can be crushed and spun again or further processed as required. Such a transfer of the waste in the state that can be reprocessed or further processed Permitted on screw presses of the usual type, but it is very expensive.

The invention is therefore based on the object of such fiber waste, film scraps, rags, Packaging waste and the like from thermoplastic raw material and extremely low bulk weight by mechanical-thermal treatment in a screw press (extruder) continuously to form extruded products, but also, among other things, granules that are too small and have a significantly higher bulk density to reshape. However, this is not straightforward with the known type of screw presses possible.

As is known, when processing materials with a low bulk density in screw presses, it is important to increase the web height of the screw in the feed zone, the more the lower the bulk density is. The pitch also depends on the type and quality of the goods to be processed. For the processing of such materials, screw presses are already known whose revolving screw has a constant web height with a decreasing outer diameter in the conveying direction. Also known are screw arrangements in which the outer diameter and land height of the screw advance continuously in the conveying direction
for thermoplastics
of extremely low bulk weight

Applicant:

Barmag Barmer machine factory

Aktiengesellschaft, 5600 Wuppertal-Oberbarmen

Named as inventor:

Günter Augustin, 5829 Ennepetal-Rüggeberg;

Karl Causemann, 5678 Wermelskirchen;

Heinz Tebbe,

Heinz Vinkeloe, 5630 Remscheid-Lennep

tend or gradually decrease. In these cases

ao, the core of the screw always decreases to a corresponding extent and in the same direction. All measures taken when processing materials of ordinary type and shape, and also from such a low bulk density of the improvement of the intake ratios or the friction of the Feeding material after entering the extrusion cylinder, the build-up of a higher compression in the cylinder and a robust warehouse design, range from extreme when processing materials small bulk material but not sufficient, the required high compression ratio and a uniform To ensure filling of the pumping zone located at the end of the melting and compression zone and to make the conveying throughput economical for a certain screw diameter. Because the enlargement of the web heights cannot be increased at will, because with such an enlargement Because of the low internal friction of the product, its promotion especially in the layers that are in the The bottom of the worm gear is in the vicinity of the worm core, becomes increasingly smaller and finally stops completely.

So far known, strongly conically enlarged screws in conically enlarged housings all serve purposes other than processing unmelted thermoplastics extremely low bulk density.

In one known embodiment, for example, there is a screw press with a conically widened filling part and greatly increased screw flight height, the purpose of which is to facilitate batch delivery of thermoplastic mixed material in time-

809 568/524

3 4

At the same time intervals with such a feed quantity coming tape or strip shape of the waste allow the screw press to be more irregular or irregular for their material takes a longer time to work. The material constriction or clogging of the worm threads In this design, the feed takes place in a funnel and thus leads to the collapse of the feed, shaped reservoir on the filling part of the screw 5 The invention is based on the knowledge that kenpresse, in which the agitator blade with large it for processing of materials with extreme Lead angle trained screw end with low bulk density is necessary, the land height great resistance and at the same time much further due to the filling and intake zone provided return flow and flow around possible than previously usual, and that one speed for the filling material around the edges of the agitator io such measure is also possible if it is possible to wing around always only so much from the supply in this case in the filling material layers at the bottom of the the screw press conveys how they process screw thread near the screw core can. forcing a movement that is promoting and

The same applies to another known screw compression of the goods. To achieve this, press that is too ig for processing salt pastes is proposed according to the invention that the larger aisle, denser particles are used than they are at the height of the screw flights in the conical filling crystallization are achievable. The funnel-shaped and feed zone is the same as the pitch in the cylinder widened The area of the screw housing serves as a threshing melting zone and which is in the area of the Filling part in which the conically widened multi-feed zone surrounding the screw is provided with housing-common screw with such a clear spacing 20 inside wall with a longitudinal corrugation. Between the inner wall of the housing and the screw vane, longitudinal grooves are used as a means of increasing the height

edges so that at all times there is a return flow coefficient of friction between the inner wall of the housing and tion of the pasty material being fed too much to be extruded material is known per se, however around the hill edges is possible. The conical provide the features named in the claim Here, too, the route area has the task of the through-25, especially in this combination, the desired effect Mixing and stirring the abandoned ma - dry pre-compression greatly expanded terials. Material before it is melted, compressed,

Other known forms of training show only homogenization and extrusion. That’s once the one borrowed a funnel above the screw - strong and progressive reduction of the friction housing, in which a conically enlarged stirring force on the screw flanks in the strongly conical wing the screw the entered plastic dimensions kneading material (clay) before it is drawn into the screw by reducing the screw pitch angle processed. in this area by changing the screw pitch

All of these described embodiments of a (that is, the conical screw flight measured parallel to the axis extended screw can be found at a vertical distance of 35) in the conical part the same as in the cylindrical part Screw presses in which the conical part is held. This is the axial Feed part a material supply for the screw conveying of the filling material is favored significantly, Moving in ready and meanwhile as possible That is on the other hand the removal of the sticky goods should be mixed and kneaded. possibility of the material on the screw flanks

The object of the invention underlying the 40 in the conical area by the arrangement of dry compression of thermoplastic longitudinal corrugations in the unheated conical shell part Plastics of extremely low bulk density, instead of the known heating of the worm gear. H. the compression of the volume that is too large, so that the bulk material does not rotate without advancing Waste residues enter a compact volum- terials. As a result, those with less weight will gain weight dry form before it is melted, there is tangential friction forces arising from the pressure the embodiments mentioned are not based on. on the auger filling during the dry Such a task cannot be carried out with these be resolved. Because, on the one hand, the angle of inclination of the material is compensated to such an extent that it is flawless the agitator blade opposite to an axial transport of the still dry material to the screw axis vertical plane, which is decisive for the 50 cylindrical melting area. The size of the between the wing flank and the thermoplastic is also due to the tight fit of the outer cone Material occurring frictional forces, which with doors of the screw in the entire filling and ingrowth Angle of inclination to an increasing extent tension area on the inner wall of the screw endeavors to set the material in rotation housing essential for the prevention of the and thus not to convey axially, with the aforementioned 55 jamming and retention of tape or Embodiments so large that this is just the strip-shaped material, making the flowing The purpose of an intended stirring effect there, the conveying process could be severely disrupted, proves which in the processing of thermo- In this way it can be used despite the result of the non-plastic Waste materials which, in their strong, usually strong, reduction in external bulging State occupy a large volume, 60 knives of the auger in the feed and feed area is completely out of place. On the other hand, the loading with a constant screw core diameter is extreme heating of the screw jacket in the conical one-large web height actually a transverse movement of the part of the first-mentioned embodiment force a good to be processed closely. By the limited local thawing of the large-area movement of the screw or its web and through The consequence of falling residues, which when detached from the screw 65, is the greatly increased friction of the goods on the cylinder jacket stick to the unheated screw wing wall, a force component is exerted against the cylinder and then rotate together with the worm, without the wall generated due to the conicity deraxial to be promoted, which is usually the same over a large depth range and across the

5 6

Direction of conveyance has a retroactive effect, resulting in composite and heating friction despite lower reren sections of the filling material a movement of the same also baren cylinder in the area of the filling zone in the layers near the screw with 2, the feed zone with 3 and the melting and core lie, caused and the compression zone required for promotion is denoted by 4. In the area borrowed transverse movement is initiated. Thus, the cylinder has a feed 5 of the filling zone also the filling material parts of the lower lying layer opening 5 together with the filling funnel 6 for processing to the cylinder wall, which in turn results in the tendency of the good. To the screw 1, whose core is about the The force required for constant conveyance creates the same diameter over the entire length, has, the screw flight 7 is helically guided.

While the decrease in the outer screw diameter in the area of the melting and compression zone 4, knife or the diameter of the screw which, for example, a usual length from the surrounding min Casing surface area per screw at least 8 to 10 times the screw pitch in the feed zone at least equal to the seat, the screw points to the circumference of the screw half Length of the screw flight height, the web can have a normal outside diameter for screw presses Diameter decrease in the filling zone also 15 diameters with the usual web height and be less. In most cases it will be off-pitch. In contrast, in the area of the filling zone 2 are sufficient, the decrease in diameter in the feed-in the web or the web height is so greatly increased, zone per screw flight no larger than a whole that the outer diameter of the screw at To choose screw pitch. However, the beginning of the screw is at least 3 times the Cases conceivable where the exceeding of this dimension 20 outside diameter of the melting and compression too leads to favorable results. The optimal aisle zone 4 is brought and is in the filling zone 2 and according to this, the height can be set for each of the adjoining catchment zone 3 to be processed Material or for a group of such materials in starting size at the beginning of the screw under constant the usual way. Decrease in conveying direction until the end of the

In a further embodiment of the invention, the tension zone 3 can be adjusted to the extent of the outer diameter of the Part of the screw located in the filling zone as melting and compression zone 4, d. H. on ming separate Component, especially with its core at least one third of its original size verals tapered sleeve that can be attached to the screw shaft. These two zones 2 and 3 are purpose-built preferably a length of at least 6 to 8 times the length on the screw shaft mounted rotatably and with its own screw pitch. The cylinder wall, which drive is provided. Such a measure serves to surround the screw like a jacket, is in the area of then in addition, any larger pieces of waste, such as a lumbar conical intake zone 3 on the inner pen or packaging waste, when entering the cylinder side 8 of the jacket, fluted in the longitudinal direction to be comminuted to the width of the screw thread. In addition, the worm web is in the area and get carried away. Furthermore, the screw flight in the 35 of the filling zone 2 on a special, on the Area of the filling zone along the edge of its trei- screw shaft 9 attached sleeve 10 angeordbenden One flank opens into its circumferential edge and is designed in such a way that the outer edge is longitudinal the undercut and / or on its periphery of the edge 11 of its driving flank, as in FIG Have recesses or interruptions and FIG. 4 is shown, undercut and at his the inner wall of the screw cylinder has recesses 12 with a circumference of 40. The sleeve 10 preferably sawtooth-shaped cutting can sit firmly on the worm shaft 9, so that be provided with an edge that rotates with the screw at the same speed. as well running screw flight a device for Zer- the sleeve 10 can also be rotated on the smaller of the supplied material forms. Shaft 9 supported and independent of the worm,

The particular advantage of the invention is that 45, for example, via the spur gear 13 with a higher Gedaß In contrast to experiences with up to speed, be able to be driven. Closer known arrangements with extremely borrowed materials is the wall of the feed opening 5 of the cylinder lower Bulk weight, for example waste from the same, as in F i g. 2 and 3 shown, with a pre-thermoplastic Fibers, foils and the like, without preferably a sawtooth-like cutting edge special pretreatment on one according to the 50 14 provided, which is beaten with the screw flight and features described gestal- acts and a device for comminuting the zueten Forms screw press to extruded goods guided.

and also to granules of high bulk density. The combination of the measures described

can be shaped and that even large pieces ensure that the filler funnel 6 is

Good, like rags or packaging waste, economical thermoplastic goods of extremely low value

Hch can be processed. Bulk weight, be it for example rags,

In the drawing is an embodiment of the packaging waste, fiber or film residues, be it

Invention shown schematically. It shows other waste, in the filling zone 2 from the screw

F i g. 1 detected a longitudinal section through the filling side web 7, in cooperation of the same with the

the screw press, 60 cutting edge 14 cut or torn and of

Fig. 2 is a plan view of the feed hopper, the screw to the feed zone 3 and further into the

F i g. 3 a cross-section through the screw is conveyed in the melting and compression zone 4,

the filling zone, whereby the feed material due to the friction-increasing

F i g. 4 shows a partial cross-section through the screw configuration 8 of the inner wall of the shell of FIG

web. 65 catchment zone 3 despite the strong tapering of the

The screw press essentially consists of a screw with the same screw core diameter.

the screw rotating in the direction of the arrow 1 knife and correspondingly strong reduction

as well as the one surrounding it, usually from more than the screw flight height one to the bottom of the

Worm-rich rolling motion and the required high compression ratio and a uniform filling of those lying at the end of the melting and compression zone, not shown pumping zone is guaranteed. The conveying throughput of the screw press is therefore also economical designed. In this way, the abandoned goods can be converted into new extruded products processed, but also processed into granules immediately after leaving the screw press and thus formed into a material with a high bulk density for further uses will.

Claims (3)

Patent claims: 1. Continuously working screw press for thermoplastics of extremely low Bulk weight, especially for waste products, consisting of a heatable screw cylinder with a feed opening for the Good to be processed as well as from a revolving screw with different ones at the filling end strongly conically enlarged and decreasing web height in the conveying direction, at which the outer diameter of the screw within the feed and intake zone to a fraction its initial size is tapered and this reduced diameter size in the subsequent Melting zone maintains approximately constant, d a characterized in that the pitch the screw flights (7) in the conical filling and intake zone equal to the pitch in of the cylindrical melting zone and the one surrounding the screw (1) in the area of the feed zone Housing inner wall (8) is provided with a longitudinal corrugation. 2. Screw press according to claim 1, characterized in that the one located in the filling zone Part of the screw (1) as a separate component, in particular with its core as on the screw shaft (9) attachable sleeve (10) is formed, which on the screw shaft (9) is preferably rotatably mounted and provided with its own drive. 3. Screw press according to claim 1 or 2, characterized in that in the area of the filling zone the screw flight (7) along the edge (11) of its driving flank in its peripheral edge opening undercut and / or recesses (12) on its circumference and the inner wall of the screw cylinder is provided with a preferably sawtooth-like cutting edge (14) which together with the circumferential screw web (7) a device for comminuting the supplied Good educates. Considered publications: German Patent No. 402,879; Austrian Patent No. 156 009; French patents No. 1003 470,
654; U.S. Patents Nos. 2,011,055, 2,246,045,
398.2807 832; Textbook by Dr.-Ing. G. Schenkel, “Screw Presses für Kunststoffe ", Munich, 1959, p. 192, para. 2 and fig. 2 and 6. 1 sheet of drawings 809 568/524 6.68 © Bundesdruckerei Berlin