DE29813559U1 - Roller screen - Google Patents

Description

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Description

Roller grate screen

The invention relates to a roller grate screen for the fine screening of classifiable goods. Non-vibrating classifying machines with a defined number of rollers arranged in a specific pitch (distance between the axes of two adjacent rollers) in a plane have been part of the state of the art for some time.

The individual rollers are made up of a large number of screen discs or disc packages. The screen discs or disc packages are usually pushed onto the shaft and secured in the usual way. The screen discs have various basic contours, e.g. three-arch, octagonal or star shapes for coarse gratings. Circular discs or special shapes are used for fine gratings.

There are gaps between the screen disks of each roller, the size of which has a decisive influence on the permeability of the screen. The bulk material with small grain sizes falls through the gaps between the screen disks when the roller rotates. The latter are arranged in series or offset from one another, sometimes interlocking.

The rollers, and thus the screen discs, rotate in the same direction as the conveying direction.

The screening material is thus transported from the feed point to the screening passage according to the set grain size and to the screening overflow for the oversized grain.

A distinction is made between coarse grates and fine grates. The former have a pitch of up to 150 mm and are used for coarse screening. Fine grates have a pitch of up to 150 mm. They are used for fine grain screening smaller than 30 mm.

On the drive side, the development status is characterized by the fact that roller grate screens are equipped with one drive motor per roller. A key advantage of this drive system is the optimal adaptation of the motors to different loads on the roller grate screen. Larger motors are installed on the feed side and smaller ones near the screen overflow. If one or two rollers fail, the screen can continue to operate temporarily. This results in simplified maintenance and servicing.

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In order to implement the drive system described for fine grates with small gap widths, it is absolutely necessary to use screen disks with a round outer contour in order to have the same gap widths. However, it has been shown that roller grate screens equipped with circular screen disks are only partially suitable for classifying goods that are difficult to screen, for example fine-grained hard coal with high surface moisture. The transport of the screened goods is difficult. The aim of the invention is to solve this problem.

Specifically, a roller grate screen for fine grain screening with one drive motor per roller is to be developed, which is particularly suitable for processing goods that are difficult to screen and which therefore does not have the trans-problem described above. The screen to be developed should also be inexpensive to manufacture and economical to operate.

The problem has been solved according to claim 1. Appropriate embodiments are specified in the subclaims.

The roller grate screen consists of a defined number of rollers arranged one behind the other in a plane, which are equipped with screen discs or disc packages. The combination of several features is considered relevant to the invention, which are explained in more detail below using drawings.

The individual figures show the following graphic representations:

Figure 1: Top view and side view of two adjacent rollers 1,

consisting of disc packs 2, with intermeshing sieve discs 3 and indicated comb scraper 4;

Figure 2: Figure 1 in enlarged view;

Figure 3: Section of a disc pack 2 with attached comb scraper 4;

Figure 4: Sieve disc 3 with recesses 5 on its circumference;

Figure 5: Recess 5 as detail A of the sieve disc 3.

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- According to Figures 1 and 2, the screen disks 3 of adjacent rollers 1 mesh with one another. This means that the distance between the screen disks 3 on a roller 1 can be chosen to be larger than is possible with opposing screen disks 3, which has manufacturing advantages. By meshing the screen disks 3, an improved screening result can be achieved.

Advantageously, disc packs 2 are used in welded construction to further reduce the manufacturing effort.

Due to the meshing arrangement of the screen disks 3 and the resulting increased distances between the screen disks 3 on a roller 1, it is possible to realize narrow gap widths 6 in the range between 10 and 30 mm, using the usual workshop technology.

- According to Figure 3, due to the increased disc spacing, as described above, a comb scraper 4 can be used with a gap width 6 of 10 mm or more. The large number of individual scrapers previously used can therefore be dispensed with.

- According to Figure 4, sieve discs 3 with a round outer contour are used, which are provided with a defined number of recesses 5 around the circumference. The distribution of the recesses 5 around the circumference of the sieve disc 3 can be regular or irregular.

In the example shown, 24 recesses 5 are evenly arranged on the circumference of the sieve disc 3.

The recesses 5 ultimately ensure the transport of the sieved material on the sieve bottom.

Particularly in the case of difficult-to-screen goods, a significant improvement in the transport of the screening material can be observed compared to the use of circular screening discs 3 without recesses 5.

Their number and the specific dimensions are crucial. Along with the other structural and process-related features, they influence the grain size of the material passing through.

- According to Figure 5, the recesses 5 have the shape of a circular section, which can be slightly recessed so that a distance L is established. A ratio of width B to depth T of 5:1 to 8:1 has proven to be advantageous.

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In the example shown in the drawing, a ratio of approximately 6.6:1 was chosen. The specific values should be designed in such a way that the specified maximum throughput grain is not exceeded, but the transport of the screening material must be guaranteed. Expressed in dimensional figures, the size ratio in the above 5 example is 4 mm:0.6 mm with a disk diameter D of 108.5 mm.

The reference symbols used mean:

1 Roller, 2 Disc package, 3 sieve disc, 4 comb scraper, 5 Deepening, 6 gap width, A detail, D Disc diameter, B Width, T Depth, L Distance measure.

Claims (8)

at · « · Protection claims 1. Roller grate screen, essentially consisting of screen rollers equipped with screen discs or disk packages arranged one behind the other in a plane, which rotate in the same direction in the conveying direction, whereby the screen discs have a circular basic circumferential shape, characterized by the combination of the following features: - The screen discs (3) of adjacent rollers (1) mesh with each other, whereby narrow gap widths (6) in the range between 10 and 30 mm are achieved. - Comb scrapers (4) are used to clean the rollers (1). - The sieve discs (3) are provided with recesses (5) around their circumference, which have the shape of a circular section with a width (B) to depth (T) ratio of 5:1 to 8:1. 2. Roller grate screen according to claim 1, characterized in that instead of individual screen discs (3), disc packages (2) in a welded construction are used. 3. Roller grate screen according to claim 1, characterized in that the depressions (5) are distributed regularly around the circumference of the screen discs (3). 4. Roller grate screen according to claim I, characterized in that the depressions (5) are distributed irregularly around the circumference of the screen discs (3). 5. Roller grate screen according to the above claims, characterized in that the screen discs (3) each have 24 recesses (5) which are evenly distributed around their circumference. 6. Roller grate screen according to claim 1, characterized in that the circular segment-shaped depressions (5) have a size ratio (B) to (T) of approximately 6.6:1. 401198gb 7. Roller grate screen according to claim 5, characterized in that the circular segment-shaped depressions (5) have a size ratio (B) to (T) of 4 mm : 0.6 mm with a disk diameter (D) of 108.5 mm. 5 8. Roller grate screen according to claim 1, characterized in that the circular segment-shaped recesses (5) are slightly sunk so that a distance dimension (L) is obtained. Here are four pages of drawings!