FI91368B - Drum Screen - Google Patents

Abstract

The subject of the invention is a drum screen for conditioning and classifying granular material with an input device at the one end of the drum which rotates about its lying longitudinal axis and an output device for the conditioned material at the other drum end. The output device connects to an annular space which is formed between the drum and annular screen sections which are located one after the other in the longitudinal direction of the drum and concentrically surround the drum. The mesh width of the annular screen sections changes in such a way that the section with the smallest mesh width is the annular screen section nearest to the output device and the section with the largest mesh width is the annular screen section at the greatest distance from the output device, preferably located in the region of the input device. Between every two successive annular screen sections (7a, 7b), a channel-shaped profile (29), with the open side directed outwards, concentrically surrounds the drum (2) at a distance of the width of the annular space. The profile engages with a number of hook- shaped mounting elements (28), distributed over the circumference, over the respective profile flange of the annular screen sections ending at it, the annular screen sections being located with initially still extended hook parts (28b) essentially free of play between two channel profiles spaced in the longitudinal direction of the drum and being held after installation in the installation position with the hooks bent about the free flange ends during installation. <IMAGE>

Description

91368

The invention relates to a drum screen according to the preamble of claim 1.

Such drum screens are used, for example, to make paving material using bitumen or asphalt and crushed stone with varying granularity. Coarse crushed stone is used for the backing layer and fine-grained crushed stone is used for the partial filling of the interstices of the backing layer, and the bitumen penetrating the remaining interstices acts as a binder for the other particles in the layer. Drum screens of the type 15 can then be used to bring the various components into the correct mixing ratio and in particular to prepare them by tempering in a heated drum screen when the individual pavement components have to be applied to the roadbed simultaneously.

20

The object of the invention is to provide a device according to the species so that separate ring screen compartments can be connected to the drum in a particularly expedient manner. By "in a particularly appropriate manner" is meant in particular that the ring screen compartments can be installed and dismantled as quickly as possible and with the least possible need for tools, and that the installed ring screens are reliably connected to the drum when they are installed.

The solution to this object is served in particular by the features of claim 1, wherein the features by which this solution is expediently applied are the subject of dependent claims.

In a further variant of the invention, it is necessary to improve the production of the mixing material, and as a solution to this sub-task, it is provided that the entire drum, including the screens, is provided with a longitudinal axis inclined with respect to the horizontal.

The invention will now be described in more detail with reference to the accompanying drawing, in which:

Fig. 1 is a schematic side view of a mixing drum into which used asphalt is fed in the manufacture of a road surface, which, however, is not necessary for the invention 10;

Figure 2 is a part of Figure 1 with more details; Fig. 3 is a section along the line III-III in Fig. 4; and

Figure 4 is a side view of the arrow C direction in Figure 3.

The fixed body 1 has a drum 2 rotatably mounted about its longitudinal axis 3. A drum 4 extends from the left end shown in the figure, the longitudinal axis of the flame of which coincides with the longitudinal axis 3 of the drum. The drum 2 is driven by a motor (not shown) via a gear comprising a running ring 5 permanently connected to the drum. At the lower end of the body 1 there are several so-called heating silos 6, arranged in the longitudinal direction of the drum in succession. These heating silos are funnel-shaped containers well insulated against heat radiation, which receive the crushed material screened from the drum 1 mixed with asphalt or bitumen mixed with it and which pass it on to a conveyor belt for further processing.

In order to sort the material, circular screens 35 91368 3 7 are arranged in succession on the drum in the longitudinal direction of the drum so that there is a ring space 8 between the sheath of the drum 2 and the circular screens 7. The round screens have different mesh sizes. 5 is a circular screen 7d of mesh size at the left end of the drum 2 shown in the drawing. The ring space 8 communicates through openings 9 in the interior of the drum 2, which openings are evenly distributed at the left drum end of the drawing on the circumference of the drum.

10

When operating the plant, different material is now fed from each end of the drum to the drum 2 by the respective feeders 10 and 11. Through the feeder 10, at the right end of the drum far from the burner, 15 new material is fed to the drum in the cold state, i.e. crushed stone with different roughness. whereupon it heats up to the desired temperature. The asphalt used is fed to the drum through the feeder 11 at the end of the drum burner 4. The mixture of used as-20 Falt and crushed stone enters through the openings 9 into the ring space 8 and from it, sorted into the respective crushed stone size, into heating silos 6, from where it can be taken for further processing.

25 Dust and moisture are removed via an exhaust flue 19 at the end of the drum feeder.

The attachment of the middle circular screens 7 to the drum 2 takes place according to the invention as shown in Figures 2 to 4.

30

The pairs of spacers 22, 23 are arranged in areas on either side of the plane 21, which mainly define the width of the gap between the drum 2 and the circular screens 7. The pairs of spacers 22, 23 are evenly distributed on the circumference of the drum 2 35 while maintaining long distances. Each spacer 22 or 23 is a longitudinally shaped profile of the drum having a U-shaped cross-section, with each spacer of a pair of 4 pairs of spacers, maintaining a relatively small distance in the circumferential direction of the drum, successively facing the backs 24 and secured radially inwardly. to the drum 5 2. The length of each distance piece (shape profile) 22 or 23 corresponds approximately to the length of one of the circular screens 7. Between the "one" spacer 22 of the pair of spacers and the "second" spacer 23 of the pair of spacers in the circumferential direction of the drum 2, a screen support 26 is provided, which is a flat and rectangular shaped profile running parallel to the circumference of the drum and following its contour and in particular, welded to the "one" of the above-mentioned paired spacer-15 pieces, and from one end to the "other", to a U-shaped spacer in cross section. Above these flat screen supports of rectangular cross-section and on top of the outer flanges 25a of the spacers 22, 23 are circular screens. The Py-20 rotary screens are held in this position at each end by a tensioning strap 27. Each clamping strap is a spring-loaded strip running parallel to the circumference of the drum 2, the length of which is adjustable by a tension lock between its ends so that the respective circular screen remains free of play between the screen support. At an initial position, angular stops 28 are evenly distributed over the length of each tensioning strap. The second rake 28b is directed radially outwards as a flange-like portion and can be functionally considered as part of the ring screen after the tensioning rim 27 has been inserted and tightened.

Between each of the two screen supports 26 arranged symmetrically with respect to the plane 21, a circumferentially shaped profile 29 is held, which likewise has a U-shaped cross-section. This profile 29 is fixedly connected to the screen supports on both sides, in particular welded.

To install the circular screen, spacer pieces 22, 23 are welded to the drum 2, screen supports 26 are welded to them, and shape profiles 29 are welded to them. The drum 2 made in this way is now placed on both sides of the shape profile 29, i.e. two shape profiles per-10 in the longitudinal direction of the drum. 29 between one of the py-sieves. The tensioning strap 27 is then placed on both ends of the respective screen with the holding means 28 and pulled tight. Thereafter, the radially inwardly directed brackets 28 are located as unobstructedly as possible against the shape profile 29. The material of the holders 28 now allows the radially projecting ends of the radially outwardly extending arms 28a (Fig. 3, left) over the flanges of the profile 29 to be bent over the upper edge 20 of the profile 29 flange (Fig. 3, right), reliably tightening the hoops and thus the screens. is fixed relative to the drum 2.

In the described embodiment according to the invention, it is possible to install and disassemble and replace the screens in a simple manner and still place the screens reliably in place without special aids.

Improving the use of the drum screen thus installed is now served by two other features with which the invention is provided.

On the other hand, the drum screen as a whole is inclined with respect to the horizontal 30 so that there is an angle α between it and the longitudinal axis 3 of the drum so that the discharge end 35 is higher than the feed end with the feeders 10. This procedure promotes mixing of materials 6. radial motion component.

On the other hand, a multi-threaded screw 31 is arranged in the ring space between the drum and the screen or successive screen compartments with different mesh sizes. For each outlet 9, a gutter is arranged between each of the two screw threads. This means or follows the leveling of the material in the ring space, which promotes sorting and the yield of sorted material in the heating silos 6. Preferably, four outlets 9 and four screws 4 are provided.

At the ends of the drum, either one flange of the U-shaped cross-sectional profile 29 is used as described, or instead of the arrangement shown in Fig. 3, only half moves to the right or left of the plane 21, depending on whether the drum in Fig. 1 is left or right.

Claims (11)

A drum screen for preparing and sorting granular material, comprising a feed device (10) at one end of a drum (2) rotating about its longitudinal axis (3) and a discharge device (9) for manufactured material at the other end of the drum, the discharge device communicating with the annular space (8). ) formed between the drum (2) and successive ring-screen compartments (7) surrounding the drum in the longitudinal direction of the drum, the mesh size of the ring-screen compartments 10 (7) changing so that the compartment (7d) with the smallest mesh size is closest to the discharge device ( 9) and the compartment (7a) with the largest mesh size is furthest from the discharge device (9), preferably in the region of the feed device (10), characterized in that the longitudinal axis (3) of the drum is slightly 15 inclined with respect to the horizontal (30), and a gap is placed concentrically between each of two successive annular screen sections (7a, 7b) surrounding the drum (2), in which a trough-shaped profile (29) is arranged a the side of the butter facing outwards, on the outer sides of which rests the retaining means (28) of the ring screen part 20-ton with a flanged outwardly pointing part (28b) which first extends over the profile in its elongate form after installation of the ring screen and then bends over one profile edge to the inside of the profile so that the ring screen compartment hooks over the profile. Drum screen according to claim 1, characterized in that each annular screen section (7a, 7b) rests on both sides of a chute-shaped profile (29) on a screen support (26) surrounding the drum (2) and located in the same circumferential plane as the profile profile partition. Drum screen according to claim 1, characterized in that each ring screen compartment (7a, 7b) is held in place by a tensioning rim (27) closed by its screen support (26). 8 Drum screen according to one of Claims 1 to 3, characterized in that the hook-like holding means (28) is fastened to a tensioning strap (27) which engages the profile (29). 5 Drum screen according to one of Claims 1 to 4, characterized in that the screen supports (26) are fixedly attached to each side of the respective profile (29) and rest on the wall of the drum 10 by means of spacers (22, 23). Drum screen according to Claim 5, characterized in that the spacers (22, 23) are trough-shaped profile sections in cross section, which are supported on their inner flange (25) on the drum (2) and are located in the gaps between the screen supports (26). Drum screen according to one of Claims 1 to 6, characterized in that a multi-threaded feed screw (31) is arranged in the annular space between the drum (2) and the ring screens (7) and is fixedly connected to the drum. 7 91368 Drum screen according to Claim 7, characterized in that the drum (2) has an outlet (9) for each turn of the feed screw. Drum screen according to Claims 7 and 8, characterized by four threads and four outlets (91). A drum screen according to claim 1, characterized in that the angle of inclination is in the range of about 10 degrees. Drum screen according to Claim 1 or 10, characterized in that the tip of the inclination angle (α) is located in the region of the feed end of the drum. 9 91368