EP0241723A2 - Mixer - Google Patents

Abstract

In the case of a tile lining for the cylindrical mixing trough of a mixer, it is proposed to offset the individual tiles (22) of adjacent rows of tiles (22B, 22C, 22D) running in the surface line direction in this surface line direction (M).

Description

The invention relates to a mixer with at least one mixing shaft comprising a mixing trough with an approximately cylindrical inner trough surface occupied by wear protection tiles and at least one mixing element lying adjacent to the trough inner surface and rotating around the mixing trough axis with one of the lining organ surfaces approximately formed by the wear protection tiles and following an angle of attack against has a surface line of the lining inner surface which is parallel to the mixer axis and intersects the edge of the mixer organ, the wear protection tiles being arranged in rows which are approximately parallel to the surface line approximately mutually parallel line separating joints between adjacent rows and with individual tile separating joints extending at an angle to the row separating joints are arranged between the individual tiles of each row.

Such a mixer is known for example from DE-PS 12 37 936. The wear protection tiles are generally interchangeable and can be replaced as intended after wear, so that the mixing trough construction is retained. Such trough linings are used in particular in compulsory mixers for mixing powdery, granular and plastic materials, for. B. in mixers for processing building material mixtures.

In the known embodiment according to DE-PS 12 37 936, the wear protection tiles are designed with a rectangular outline, the individual tile separating joints of adjacent rows lying in circumferential alignment with one another.

It has now been found that, in the known embodiment, wear occurs more rapidly on the individual tile separating joints than on the row separating joints lying in the direction of the surface line and on the inner surfaces of the tiles forming the lining inner surface.

The invention has for its object to design a mixer of the type mentioned in such a way that the premature wear of the individual tile separating joints running transverse to the longitudinal direction of the tile lining is largely avoided.

To solve this problem it is proposed that the individual tile joints of individual rows against the individual Tile dividing joints of other rows in the row longitudinal direction, ie are offset in the surface line direction.

It was found that this measure can significantly reduce the wear on the tiles in the area of the individual tile joints. The cause of this beneficial effect is not fully understood. It could be that this advantageous effect is due to the fact that the line transport of mixed material along the individual tile separating joints is interrupted by their offset in the area of successive row separating joints and thus the abrasive effect of the mixed material on the areas of the tiles forming the individual tile separating joints is reduced. In any case, it has been shown that the staggered arrangement of the individual tile separating joints of individual rows compared to the individual tile separating joints of other rows approximates the service life of all tile areas and thus extends the service life of the wear protection tiles as a whole.

Particularly favorable results with regard to the extension of the service life are achieved if the individual tile separating joints of each row are offset in the direction of the generatrix in relation to the individual tile separating joints of the rows immediately adjacent to this row. This result supports the theory given above that the interruption of the line flow of the mixed material along the individual tile separating joints could be responsible for the reduction in the wear on the tiles in the area of the individual tile separating joints.

The execution of the inventive idea was opposed to the consideration that when transferring the individual tile separating joints in the row longitudinal direction against each other at the ends of the respective rows would receive defects in which the lining is interrupted and that one would have to take care of a different form of the lining there. However, it has now been shown that this problem can also be solved in a relatively simple manner by providing compensating tiles at the ends of at least part of the rows.

According to one embodiment of the invention, the individual tile joints are perpendicular to the row joints. If you then additionally ensure that the individual tile separating joints of adjacent rows are offset by half the individual tile dimensions in the row longitudinal direction, you can get by with a single type of compensation pieces, namely compensation pieces whose length in the row longitudinal direction is equal to half the tile length in the row longitudinal direction .

Surprisingly, it has also been found that a significant reduction in wear of the wear protection tiles on the individual tile joints can also be achieved in that the individual tile joints are arranged inclined against a circumferential line of the trough, in the sense of a reduction in the angle between the speed vector of the resulting mixture movement in the Area of the mixing organ edge and a normal line following the inner lining surface onto the respective individual tile joint. This phenomenon is also not fully explained. It could be due to the fact that the angular approximation of the speed vector of the resulting mixture movement in the area of the mixer organ edge to a normal line following the inner surface of the trough to the respective one Single tile joint the line movement of the mix along the respective single tile joint is largely suppressed.

The idea of inclining the individual tile separating joints against the circumferential line of the inner trough surface should be protected against the individual tile separating joints of other rows in the direction of the generatrix, irrespective of the displacement of the individual tile separating joints. H. in particular, the possibility is to be covered by the protection in which the individual tile separating joints inclined against the circumferential line of successive rows are all in alignment with one another.

In the embodiment in which the individual tile separating joints are inclined against a circumferential line, it is advisable to offset the individual tile separating joints from one another in the longitudinal direction of the row by the length of their projection onto the longitudinal longitudinal joints. Thus, on the one hand, an interruption of the line flow along the individual tile separating joints is achieved and, on the other hand, this measure ensures that an inner trough surface can be lined with a single compensating tile in addition to the normal tiles. The leveling tile then differs from the normal tiles only in that one of its end edges running transverse to the longitudinal direction of the row runs parallel to the associated circumferential line.

When equipping the mixer with mixing elements with different angles of attack, appropriate tile arrangements in the area of each mixing element can on the one hand ensure the displacement of the individual tile separating joints of individual rows against the individual tile separating joints of adjacent rows and, on the other hand, meet the requirement that the individual tile separating joints are inclined in the sense of a circumferential line Angle approximation of the speed vector of the resulting mixture movement in the area of the respective mixer organ edge to a normal line following the inner lining surface onto the respective individual tile joint. This would lead to an optimal service life of the entire lining. However, one can also compromise with a solution to the fact that when the mixer is equipped with mixing elements with different angles of attack, the inclination of the individual tile separating joints against the circumferential line is the same for all tiles and is matched to the angle of attack of the large number of mixing elements with the same angle of attack. This solution can be chosen, for example, if material transfer devices for transferring the mix from the area of one shaft to the area of the other shaft are provided at the two ends of each shaft in a double-shaft compulsory mixer and these transfer devices have a pitch angle opposite to that of the normal mixing devices. In any case, even if the mixer is equipped with mixing or transfer elements of different angles of attack, the advantage can be exploited that results from the displacement of the individual tile separating joints of successive rows in the longitudinal direction of the row.

The wear protection tiles can rest against the inner surface of the trough in an abutment area surrounding an approximately central fastening point and can have a short, approximately constant distance from the inner surface of the trough outside this abutment area. This embodiment ensures that when the wear protection tile is fastened, for example by means of a clamping screw, no bending stresses can be introduced into the tile. however, it is possible to support the tiles on the inner surface of the trough.

It is recommended that the tiles along the row joints on the lining inner surface meet approximately with their edge surfaces and form widening gaps towards the inner surface of the trough. In this way, the tiles are left with a certain degree of tumbling and the risk of destruction due to mutual imprinting of internal tensions is avoided.

For easier design and to avoid internal stresses, the tiles on their outer surfaces, i. H. those areas that lie against the inner surface of the trough be provided with recesses.

• Fig. 1 eine perspektivische Ansicht eines Doppelwellen­zwangsmischers mit erfindungsgemäßer Gestaltung der Kachelauskleidung;
• Fig. 2 ein Mischorgan im Bereich einer Einzelkacheltrenn­fuge;
• Fig. 2a eine Abwicklung zu Fig. 1 mit einem Mischorgan und einer Kachelauskleidung entsprechend dem Stand der Technik;
• Fig. 3 eine erste Ausführungsform einer erfindungsgemäß gestalteten Kachelauskleidung in Abwicklung;
• Fig. 4 ein Schema entsprechend demjenigen der Fig. 2a bei der Kachelauskleidung gemäß Fig. 3;
• Fig. 5 eine weitere Ausführungsform einer erfindungs­gemäßen Kachelauskleindung bei einem Doppelwellen­zwangsmischer mit zwei Mischorganen unterschied­lichen Anstellwinkels;
• Fig. 6 ein Schema gemäß Fig. 2a zu dem linken Misch­organ in Fig. 5;
• Fig. 7 eine Rückansicht einer Verschleißschutzkachel zu der Auskleidung gemäß Fig. 5;
• Fig. 8 einen Schnitt nach Linie VIII-VIII der Fig. 7 und
• Fig. 9 eine Rückansicht auf eine Ausgleichskachel zu der Auskleidung gemäß Fig. 5.

The accompanying figures explain the invention using exemplary embodiments. They represent:

• Figure 1 is a perspective view of a double shaft positive mixer with inventive design of the tile lining.
• 2 shows a mixing element in the area of a single tile separating joint;
• 2a shows a development of FIG. 1 with a mixing element and a tile lining according to the prior art;
• 3 shows a first embodiment of a tile lining designed according to the invention in development;
• Fig. 4 is a diagram corresponding to that of Fig. 2a in the tile lining according to FIG. 3;
• 5 shows a further embodiment of a tile lining according to the invention in a double-shaft compulsory mixer with two mixing elements of different angles of attack;
• FIG. 6 shows a diagram according to FIG. 2a for the left mixing element in FIG. 5;
• FIG. 7 shows a rear view of a wear protection tile for the lining according to FIG. 5;
• Fig. 8 is a section along line VIII-VIII of Fig. 7 and
• 9 is a rear view of a compensation tile for the lining according to FIG. 5.

The double-shaft compulsory mixer shown by way of example in FIG. 1 comprises a double-chamber mixing trough which is composed of two mixing troughs 10. A mixing shaft 12 is arranged in each of the two mixing troughs 10. The mixing shafts 12 carry in their central axial section mixing elements 14 in the form of mixing blades, which are arranged in such a way that they convey the mix in the two mixing troughs 10 in opposite directions and at the same time move from mixing trough to mixing trough, while at the ends of the two mixing shafts 12 transfer elements 16 are arranged, which ensure that at the ends of the two mixing troughs 10, the mix is transferred from one mixing trough to the other mixing trough. It is only of interest for the present consideration that the transfer organs 16 have a different angle of attack with respect to the mixing elements 14.

A mixing trough 10 has a cylindrical inner trough surface 18, which has a circumferential line U and a surface line M. The surface line M is parallel to the axis A of the mixing shaft 12. The inner trough surface 18 is covered with a tile lining 20. The tile lining 20 is formed by wear protection tiles 22. The wear protection tiles 22 are arranged in rows of tiles 22A, 22B etc. It can be seen that the wear protection tiles 22 of the rows 22A and 22B are offset from one another, with row butt joints 24 being formed parallel to the surface line M between the rows 22A, 22B etc. and between the individual wear protection tiles 22 of each row of individual tile separating joints 26. The single tile parting lines 26 are in the longitudinal direction, i. H. offset from each other in the generatrix line direction M and measured by half the length of a wear protection tile in the generatrix line direction M.

In the embodiment belonging to the prior art, which is shown in development in FIG. 2a, the wear protection tiles 22 were arranged such that the individual tile separating joints 26 were aligned with one another, in contrast to the offset arrangement according to FIG. 1.

According to FIG. 2a, the mixing elements 14 are arranged with their mixing element edges 28 at an angle α against the surface line M. The peripheral speed of the edge of the mixer organ is designated v _u . As a result of the angle of attack α, there is a sliding movement of the material to be mixed along the edge of the mixing element 28, with a sliding action speed v _g . The resulting speed of the mixed material at the location X of the mixing organ edge 28 is denoted by v _r . This resulting speed v _r results from vectorial superimposition of the peripheral speed v _u and the sliding speed v _g , the size of which in turn is dependent on the angle of attack α and on the coefficient of friction of the material to be mixed along the edge of the mixing element 28. 2a also shows the normal line N to the single tile separating joint 26. The angle enclosed between the normal line N and the speed _vector v _{r of} the resulting speed is denoted by γ. It can be seen that, assuming an angle of attack α of approximately 45 ° and given the circumferential speed v _u and the sliding speed v _g, the angle γ between the normal line N and the resulting speed _vector v _{r is} considerably greater than 45 °. This means that there is a significant component of the resulting speed v _r in the direction of the single tile separating joint 26. This component parallel to the individual tile separation joint 26 of the resulting speed _vector v _r leads to a pronounced linear movement of the mixed material taking place along the individual tile separation joints 26, which leads to premature wear of the wear protection tiles 22 along the individual tile separation joints 26. This linear movement of the mixed material along the individual tile separating joints 26 is all the more pronounced in the known embodiment according to FIG. 2a, since the individual tile separating joints 26 are aligned with one another parallel to the circumferential line U. According to FIG. 2, this leads to wear of the wear protection tiles 22 along the individual tile separating joint 26 between the mutually facing edge surfaces 30 of the wear protection tiles. This wear leads to excavations in which the mixed material particles 32 become stuck can set so that they are transported from the Mischorgankante 28 along the decolored individual tile joints 26. This can lead to further damage to the mixing organ edge 28, as shown in broken lines in FIG. 2. In this way, there is a loss of service life due to premature wear of the wear protection tiles 22 and - which is even more serious - premature wear of the expensive mixing elements 14.

It can be seen from Fig. 2a that the row butt joints 24 are less at risk than the individual tile butt joints 26 because the speed component of the resulting speed v _r in the direction of the row butt joints 24 (this speed component is not shown) is significantly lower than the speed component in the direction of the single tile butt joints 26. This fact must be taken for granted due to the values of the angle of attack α, which are usually around 45 °, and the usual coefficients of friction between the material to be mixed and the edges of the mixer organ. This means that primarily the individual tile separating joints 26 are susceptible to premature wear, and that attempts to increase the service life of the tile lining are particularly concerned with achieving an improvement in the area of the individual tile separating joints 26. 2a and in the following FIGS. 3, 4, 5 and 6, the angle between the individual tile separating joints 26 and the row separating joints 24 is denoted in each case by ε.

In the embodiment according to FIGS. 3 and 4, the wear protection tiles 22 are again arranged in rows 22A, 22B, etc., the row separating joints 24 again running parallel to the surface line M. However, the tiles 22 within the individual rows 22A, 22B etc. are now offset by half their length in the direction of the surface line, so that the individual tile parting lines 26 in the direction of the surface line M are mutually offset are offset, as also indicated in Fig. 4. In the embodiment according to FIG. 4, the inclination γ of the resulting speed v _r compared to the normal N on the single tile butt joint 26 has now remained the same as in the known embodiment according to FIG. 2a. However, since the individual tile separating joints 26 are offset from one another, the pronounced line movement occurring in the embodiment according to FIG. 2a can no longer take place over several individual tile separating joints aligned with one another, and the excavation to be expected according to FIG. 2 is therefore significantly reduced and thus the risk of damage the mixing organ edge 28.

5 and 6, the individual tile separating joints 26 are inclined at an angle β with respect to the circumferential line U, as shown in FIG. 6. This means that the speed _vector v _r is approximated to the normal line N to the single tile separating joint 26; the angle γ has become smaller. This leads to the fact that the speed component of the resulting speed _vector v _r parallel to the single tile separating joint 26 has become significantly smaller. In other words: the pronounced line movement takes place along the individual tile separating joints 26 and the material is pushed essentially vertically over the individual tile separating joint 26 through the mixing organ edge 28. It has been shown that in this way the leveling out along the individual tile separating joint 26 which occurred in the prior art according to FIG. 2 and the resulting damage to the mixing organ edge 28 is further reduced.

5 and 6 that the offset of the individual tiles 22 in the longitudinal direction of the row, ie in the direction of Surface line M is equal to the projection p of a single tile separating joint 26 onto a row separating joint 24. At the ends of the rows 22A, 22B etc. compensation tiles 34 are provided, the end edges 36 of which extend transversely to the surface line M and form a 90 ° angle with the surface line. It can also be seen from FIG. 5 that a single type of compensating tile 34 can be used at both ends of the rows 22A, 22B etc.

5, namely in its right half, also the transfer member 16 from FIG. 1, the angle of attack of which is denoted by δ. Because of the other angle of attack δ (this is also assumed, for example, to be approximately 45 °), the conditions at the edge of the transfer member 16 are considerably less favorable than shown in FIG. 6 for the mixing member edge 28 of the mixing member 14. This means that the individual tile separating joints 26 provided in the area of the transfer members 16 are subject to increased wear and tear unless other measures are taken to prevent wear and tear. One could of course change the slope of the individual tile separating joints 26 to the circumferential line U in the area of the transfer members 16 in order to achieve the advantageous results according to FIG. 6 here as well. However, one can also accept that in the area of the transfer members 16 the improvement is achieved only by the offset of the individual tile separating joints by the dimension p in the surface line direction M, which is also present here. You then have the advantage that you can get by with a single normal tile and with a single compensation tile. If the individual tile separating joints located in the area of the transfer members 16 are worn out prematurely and thus a loss of service life occurs, the advantage still remains that one can in the larger area of the mixing members 14 (see Fig. 1) the wear protection tiles 22 are maintained longer and thus the extent of the necessary replacement repair remains reduced.

7 and 8, a normal tile 22 for the embodiment of FIGS. 5 and 6 is shown. The angle of the individual tile separating joint 26 against the circumferential line direction U is drawn in with β and is assumed to be approximately 9 °. It can be seen from FIG. 8 that the normal tile 22 has a projecting central contact surface 38 in the area of a central fastening opening 40 on its rear side. It can also be seen that the normal tile 22 is designed with recesses 42 on the back.

The compensation tile 34 shown in FIG. 9 is designed accordingly.

According to FIG. 8, the row parting line 24 is designed as a parallel gap which extends from the inner surface of the tile lining to the inner surface of the cylindrical trough.

5, the mounting holes 40 are arranged in the corner points of a rectangular grid.

For the embodiment according to FIGS. 3 and 4, it must also be added that the compensation tiles are designated by 23 there. These compensation tiles 23 have in the row longitudinal direction, i. H. in the surface line direction M half the length as the normal tiles 22.

Claims (12)

1. Mixer with at least one mixing shaft, comprising a mixing trough with an approximately cylindrical inner trough surface (18) covered by wear protection tiles and at least one mixing element (14) adjacent to the inner trough surface (18) and rotating around the mixing trough axis (A) with one of the wear protection tiles (22) formed lining inner surface approximately following the mixing organ edge (28), wel che has an angle of attack (α) against a surface line (M) of the mixing trough (10) which is parallel to the mixer axis (A) and intersects the wear protection tiles (22) in rows (22A, 22B etc.) which are approximately parallel to the surface lines and with row separating joints which are approximately 24) are arranged between adjacent rows (22A, 22B etc.) and with individual tile separating joints (26) running at an angle (ε) to the row separating joints (24) between the individual tiles (22) of each row (22A, 22B etc.), thereby characterized in that the individual tile separating joints (26) of individual rows (22A, 22C etc.) are offset in relation to the individual tile separating joints (26) of other rows (22B, 22D etc.) in the surface line direction (M). 2. Mixer according to claim 1, characterized in that the individual tile separating joints (26) of each row (22B) are offset in relation to the individual tile separating joints (26) of the immediately adjacent rows (22A, 22C) in the surface line direction (M). 3. Mixer according to claim 1 or 2, characterized in that compensating tiles (23) are provided at the ends of at least part of the rows (22A, 22B, etc.). 4. Mixer according to one of claims 1 to 3, characterized in that the individual tile separating joints (26) run perpendicular to the row separating joints (24) (ε = 90 °). 5. Mixer according to claim 4, characterized in that the individual tile separating joints (26) of adjacent rows (22A, 22B etc.) are each offset by half the individual tile dimension in the longitudinal direction (M). 6. Mixer, in particular according to one of claims 1 to 3, characterized in that the individual tile joints (26) are inclined against a circumferential line (U) (β) in the sense of a reduction in the angle (γ) between the speed _vector (v _r ) resulting movement of the mix in the area of the mixer organ edge (28) and a normal line (N) following the inner surface of the trough (18) onto the respective individual tile joint (26). 7. Mixer according to claim 6, characterized in that the individual tile joints (26) are each offset by the length (p) of their projection onto the row joints (24) in the longitudinal direction (M). 8. Mixer according to claim 7, characterized in that the fastening points (40) of the wear protection tiles on the inner surface of the trough (18) are arranged in the corner points of a rectangle grid with sides parallel to the circumferential direction (U) and to the surface line direction (M). 9. Mixer according to one of claims 6 to 8, characterized in that when the mixer is equipped with mixing elements (14, 16) different angles of attack (α, δ) the inclination (β) of the individual tile joints (26) against the circumferential line (U) for all tiles (22) are the same and are matched to the angle of attack (α) of the larger number of mixing elements (14) of the same angle of attack (α). 10. Mixer according to one of claims 1 to 9, characterized in that the wear protection tiles (22) on the inner trough surface (18) in an approximately central fastening point (40) surrounding Anlagebe abut (38) on the inner surface of the trough (18) and have a short, approximately constant distance from the inner surface of the trough (18) outside this contact area (38). 11. Mixer according to one of claims 1 to 10, characterized in that the tiles (22) along the row joints (24) on the lining inner surface approximately meet with their edge surfaces and form parallel gaps towards the inner trough surface (18). 12. Mixer according to one of claims 1 to 11, characterized in that the wear protection tiles on their outer surfaces, ie towards the inner trough surface (18), are provided with recesses (42).

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