DE20308817U1 - Screw compressor for hollow, waste plastic packaging, comprises trough containing rotor formed by tapered screw and blunt cone carrying friction strips - Google Patents

Abstract

In the part of the trough which is upwardly-open, the screw shaft is a closed blunt cone (7). This includes angled friction strips (8), preferably steel profiles of triangular cross section about 20 mm high, with mean circumferential spacing of 50 mm. They are connected to the blunt cone following the same tapering inclination as the screw spiral (10), but at a smaller pitch (15). In the part of the trough which is upwardly-open, the screw shaft is a closed blunt cone (7). This includes angled friction strips (8), preferably steel profiles of triangular cross section about 20 mm high, with mean circumferential spacing of 50 mm. They are connected to the blunt cone following the same tapering inclination as the screw spiral (10), but at a smaller pitch (15). Low in the trough stripping edges of square- or rectangular steel bars, are oppositely-pitched to the friction strips, and have minimum spacing from them, enclosing them closely. In contrast to the generally conical form of the entire unit, a variant of the design is generally-cylindrical. Other sections than triangular may be substituted for the friction strips.

Description

Applicant: Kampwerth Umwelttechnik GmbH & Co. KG

OntheWittenburg80
49196 Bad Laer

Designation: Screw compactor for used hollow body packaging made of
plastic

The invention relates to a screw compactor for compacting hollow packaging,
e.g. disposable beverage bottles made of PET plastic.

Such bottles are almost always returned with the cap on and, if not compressed, take up a lot of transport volume. By using a suitable compression process
Approximately 90% of transport volume can be saved. However, the bottles must be opened before compaction, e.g. by punching or squeezing them, to allow the trapped air or residual liquid to escape. As is well known, so-called perforators are used for this. These are usually spiked rollers driven by an electric motor which, running in pairs against each other or rotating individually at a short distance from a sheet metal wall, draw in the hollow bodies, destroy their walls and release them downwards into the compaction device, e.g. a screw compactor or a reciprocating piston press with an attached press container. To accomplish the task, two different machines are therefore required, with two drives and the need to combine and coordinate them structurally. In addition, due to the material flow, both machines have to be arranged one above the other, which inevitably increases the filling height and may require additional conveyor technology.

The innovation described below avoids the aforementioned disadvantages and reduces the technical effort considerably. Destruction and subsequent compaction of the hollow bodies are carried out by only one rotating component.
It is a screw compressor, the screw shaft of which rotates on one side in a partially open trough on the drive side. The part of the screw shaft in the open area is a truncated cone-shaped body, which is fitted with friction strips on its closed surface, which are arranged at a circumferential distance of approx. 50 mm, preferably at an angle of approx. 80° to the left (when the shaft is rotating clockwise, viewing direction = conveying direction). The friction strip cross-section can be

-2- (Screw compressor for...)

square, rectangular or triangular. Perpendicular to the surface, the friction bars have a height of approx. 20 mm. The part of the screw shaft located in the closed part of the trough is designed as a normal conveying/compression screw and protrudes with its end and the surrounding trough that merges into a pipe into the adjoining compression chamber. In the area that is open at the top, the trough encloses the screw shaft at the bottom in an area of approx. 120° and has one or more scraper edges that are approx. 20 mm high, the side of which facing the screw axis has a constant distance of approx. 5 mm from the friction bars passing by. In addition, the scraper edge is arranged at an angle of approx. 45° to the right in order to achieve a squeezing effect as well as a conveying effect in conjunction with the left-hand oriented friction bars.

The invention is explained in more detail below with reference to 4 drawings.

Fig. 1 in side view a sectional view of the machine housing with -not cut-
Worm shaft

Fig. 2 a view against the conveying direction

Fig. 3 a top view

Fig. 4 a top view without worm shaft

In Fig. 1 you can see the machine housing 1, which consists essentially of front and side walls, and which also has the trough 2 and separating plates 3 inserted transversely to the screw axis, each of which has corresponding cutouts for the contact-free passage of the screw shaft. In addition, you can see the roller bearing 4 on the right, on which the drive wheel 5 with the screw shaft 6 attached to it is mounted. The screw shaft is divided into two sections: the first section 7 is a truncated cone with friction strips 8 attached to the outer surface, which are arranged at a pitch angle 9 (approx. 80°). The second section 10 is designed as a conveyor/compressor screw and is in the

-3- (Screw compressor for...)

Outlet area surrounded by a pipe 11, which projects into the adjacent compression chamber, not shown here.

Fig. 2 shows a view against the conveying/pressing direction. The position of the drive motor 12 used here with traction drive connection 13 to the drive wheel of the screw shaft can be seen, as well as the course of the trough 2. In this view, the direction of rotation is to the left, anti-clockwise. Also shown in the inlet gusset are a few bottles 14 which are gripped by the friction bars, pressed against the trough extension running tangentially to the top left and thereby drawn in. The compression of the hollow bodies leads to an increase in pressure inside them, which, together with the sharp edges of the friction bars and the scraper edge in the trough, leads to destruction of the hollow body wall. At the same time, the gradient arrangement of the friction bars and scraper edges causes the destroyed hollow bodies to be conveyed in the direction of the second section of the screw shaft. As soon as they have reached this, they are conveyed further and then compacted in the coupled press container. This is where the particularly advantageous operation of a screw compactor compared to a reciprocating piston press becomes apparent: plastics show such a strong re-expansion during compaction that reciprocating piston presses are unable to accept newly filled material at an early stage, which is not the case with the screw compactor due to its principle.

Fig. 3 shows a top view.

Fig. 4 shows a plan view without a worm shaft, so that the scraper edge 15 arranged in the trough is visible.

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Claims (4)

1. Screw compressor for hollow plastic packaging, consisting of a screw shaft ( 6 ) arranged preferably horizontally in a housing ( 1 ) with a one-sided bearing ( 4 ) and a drive ( 12 , 13 , 5 ), surrounded in the lower peripheral area by a trough ( 2 ) open at the top and a pipe socket ( 11 ) connected to it and 2 separating plates arranged transversely to the screw shaft axis in the trough area with cutouts for the screw shaft ( 3 ), characterized in that the screw shaft in the upwardly open area of the trough consists of a closed truncated cone ( 7 ) which is provided on its outer surface with friction strips ( 8 ) arranged at an angle ( 9 ), consisting preferably of steel profiles with a triangular cross section with a height of approx. 20 mm and a mean distance in the peripheral direction of 50 mm, and adjoining the truncated cone is a friction strip arranged in the same direction of inclination as the friction strips. further screw flight ( 10 ) but with a much smaller pitch angle ( 15 ). 2. Screw compressor according to claim 1, characterized in that in the lower trough area at least one scraper edge ( 15 ) consisting of a steel profile with a square or rectangular cross-section, with a pitch direction opposite to the pitch direction of the friction bars and with the smallest possible distance to the envelope of the friction bar outer edges, is arranged. 3. Screw compressor according to claim 1 or 2, characterized in that instead of the frustoconical design of the outer contour of the screw shaft and the enclosing trough part, a cylindrical design is selected. 4. Screw compressor according to one of claims 1-3, -2-(protection claims for screw compressors for . .), characterized in that instead of the triangular friction bar cross-section, another cross-section is used.