DE3012707A1 - MIXER FOR TROGIMIC - Google Patents

Description

Patent attorneys - 4 -

ing. E. ^Eder
K. Sohl · «** ·

BHS-Bayerische Berg-, Hütten- und Salzwerke Aktiengesellschaft

Munich

Mixing mechanism for trough mixers

The invention relates to a mixer for trough mixers, with at least two horizontal, counter-rotating Mixing shafts for mixing powdery, granular or plastic mix, in particular building material mixes, whereby on each mixing shaft two helical screw flights running in opposite directions are arranged.

In order to achieve a good mixing effect with a fast mixing effect, i.e. with a short mixing time, the following must be used by the mixer Requirements are met: Intensive and counteracting mix movements at maximum transport speed in a revolving, repetitive movement cycle in the mixing trough.

These mixing requirements are met by trough mixers, that work with slowly rotating mixers, best achieved by helical mixers, normal peripheral speeds measured on the outer mixer diameter, are in the range from 1.4 to 2.0 m / s.

A mixer for concrete mixers is already state of the art known, wherein on each of the two mixer shafts two oppositely coiled screw belts are arranged

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are (DE-OS 24 40 461).

The length ratio of the two counter-rotating screw belts is here 1: 1. The screw belts thus each have the same length and are also the same Run angles.

In practice it has now been shown that no good mixing results can be achieved with this known mixer. This The main disadvantage is the insufficient cyclical movement of the mix in the trough. There is no circular motion within the trough in the desired sense.

The state of the art also includes a mixer for single-shaft mixers (DE-OS 2 311 579). Here, too, the length ratio of the two provided with opposite inclines is Auger belts 1: 1. This mixer is. only suitable for single-shaft but not for double-shaft mixers.

Based on the aforementioned embodiment of a Double-shaft trough mixer, the object of the present invention is to create an improved mixer, which enables quick mixing with a good mixing effect.

This object is achieved in that the Helical screw flights of each mixing shaft have different system lengths have and form an asymmetrical spiral screw mixer. So there is a longer and on each mixing shaft a shorter, but counter-rotating helical worm. The long helix is used to transport the mix in the longitudinal direction of the Mixing trough and the short helix for transporting the mix in the transverse direction of the mixing trough, so that a cyclical movement of the mix arises. This results in very good mixing effects with rapid mixing of the mix, especially of building material mixtures, achieved.

1300 * 1/0 * 11

In a further embodiment of the invention, there is in each case a spiral worm gear greater system length of one mixing shaft to a spiral worm gear of lesser system length of the other mixing shaft arranged opposite. This advantageously results a good circular movement within the trough, which results in a very good mixing effect.

According to another feature of the invention, the helical worm flights of different system lengths can either have the same helix angle or different helix angles. The pitch angle (X- of the shorter helix can be within the limits of 40 to 90 ° and the helix angle ß? Of the long helix in the limits of 25 to 40 °. Very good mixing results are obtained according to a further feature of the invention if the system> length ratio X: Y for the helical screw flights lies within the limits of 1: 2 to 1: 7.

Another embodiment of the invention is possible in that the helical worm flights are designed to be interrupted individual, attached to the arms of the respective mixed shaft, Helical blades arranged one behind the other in a helical line. The helix angle in the different helical screw flights of the asymmetrical spiral screw mixer here equal to, smaller or larger than the slope angle of the be helical connecting line between the individual blades.

In a further embodiment of the invention, the helical screw flights be multi-threaded.

With regard to the center distance A of the mixing shafts in relation to the outer diameter D of the mixing mechanism, in a further embodiment According to the invention, the center distance A must be smaller than the outer diameter D. Here, the ratio of center distance A to Outside diameter of the mixer D within the limits of 1: 1.1 up to 1: 1.4.

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The invention is described in more detail below with reference to an exemplary embodiment shown in the drawing. In the Drawing show:

Fig. 1 is a cross section through the trough of a

Twin-shaft trough mixer with top view on the two asymmetrical spiral screw mixers arranged horizontally in the trough;

Fig. 2 is a longitudinal section of an asymmetrical

Helical screw mixer in the twin-shaft trough mixer according to the invention.

According to Fig. 1, two parallel and horizontally mounted, counter-rotating mixing shafts 1 and I ¹ are arranged within a mixing trough 6. Each mixing shaft 1 or I ¹ has two asymmetrical helical screw mixing flights 4 and 5 or 4 'and 5' with an incline in opposite directions. The individual helical worm flights have different system lengths X and Y, the length ratio X: Y advantageously being in the limits of 1: 2 to 1: 7.

The helix angles, which are defined as the angle between the helix of the helical screw and the direction of movement Z, are indicated by OC and β. Here there is the possibility that the pitch angles (P and yogieich or can be configured differently. If the pitch angles are configured differently, advantageous values result when CO is in the range from 40 to 90 ° and β> in the range from 25 to 40 ° .

The two asymmetrical helical worm flights 4 and 5 or 4 ¹ and 5 ¹ are each attached ^{to the mixing shaft 1 and I 1} via arms 2 and 2 ', respectively.

From Fig. 1 it can be seen that the helical worm gear 5 with the system length Y of the mixing shaft 1 with the helical worm gear 4 '

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the system length X of the other mixing shaft 1 'is opposite. Correspondingly, the shorter helical worm gear 4 of the mixing ^{shaft 1 is} assigned to the mixing shaft I ^{1 compared to the longer helical worm gear 5 1.}

Here, the helical screw flights 5 and 5 ¹ carry out the transport of the material to be mixed in the longitudinal direction, while the shorter helical screw flights 4 and 4 ¹ carry out the transport in the transverse direction. This results in a very favorable cyclical movement of the mix in the trough, so that practically a kind of circular movement takes place in it.

The mixer diameter is denoted by D in FIGS. From Fig. 1 it can be seen here that the mixer diameter D of the two helical screw flights 4 and 5 or 4 ¹ and 5 ¹ overlap; the center distance A between the mixer shafts 1 and I ¹ is therefore smaller than the mixer diameter D. Favorable ratios A to D are between 1: 1.1 to 1: 1.4 and depend on the mixer size and the mixer speed.

Another embodiment, not shown in detail to the invention can consist in that the helical screw flights 4 and 5 or 4 'and 5 interrupted ¹ are executed. This results in individual, helically arranged, helical blades attached to the arms 2 and 2 ¹ , with the pitch angles OU and β in the areas of the system lengths X and Y being equal to, smaller or larger than the pitch angle of the helical connecting line between the individual blades.

Overall, it should be noted that the asymmetrical training the helical screw flights in a twin-shaft trough mixer, rapid mixing takes place with a good mixing effect.

DIpI.-Ing. E. Ed & r Dlpl.-Ing. K. Schieschke β Munich 40, Elisabeihstra0e34

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Claims (1)

Patenfenwltt Dipl.-ing. E. Eder DJpI.-Ing. K. Schleschk «» Munich 49, Hlisabethstra3e34 BHS-Bayerische Berg-, Hütten- und Salzwerke Aktiengesellschaft Munich Mixing mechanism for trough mixers Claims Mixing mechanism for trough mixers, with at least two horizontal, counter-rotating mixing shafts for mixing powdery, granular, or plastic mixes, in particular building material mixtures, with two helical screw flights in opposite directions being arranged on each mixing shaft, characterized in that the helical screw flights (4, 5; 4 ¹ , 5 ') of each mixing shaft (1, I ¹ ) have different system lengths (X, Y) and form an asymmetrical spiral screw mixer. Mixing mechanism according to claim 1, characterized in that in each case a spiral screw flight (5, 5 ') of greater system length (Y) of one mixing shaft (1, 1') has a spiral screw flight (4, 4 ¹ ) of shorter system length (X) of the other mixing shaft (1 , I ¹ ) is opposite 130041/0412 3. Mixing mechanism according to claim 1 and 2, characterized in that the helical screw flights (4, 4 ¹ ; 5, 5 ¹ ) of different system lengths have the same pitch angle. 4. Mixing mechanism according to claim 1 and 2, characterized in that the helical screw flights (4, 4 ¹ ; 5, 5 ^{1 of} different system lengths have different pitch angles (CX-, β) . 5. Mixing mechanism according to one of the preceding claims, characterized in that the system length ratio (X: Y) for the helical worm flights is within the limits of 1: 2 to 1: 7. 6. Mixer according to claim 4, characterized in that the one pitch angle (OC) within the limits of 40 to 90 ° and the other pitch angle (/ 2) within the limits of 25 to 40 °. 7. Mixing mechanism according to claim 1, characterized in that the helical screw flights are designed to be interrupted with individual helical blades which are attached to the arms (2, 2 ') of the respective ^{mixing shaft (1, I 1} ) and are located one behind the other in helical lines. 8. Mixing mechanism according to claim 7, characterized in that the pitch angle ((X, ß) in the different system lengths (X, Y) of the asymmetrical helical screw mixer are equal to »smaller or greater than the pitch angle of the helical connecting line between the individual blades. 9. Mixing mechanism according to one of the preceding claims, characterized in that the helical worm flights are multi-thread are. 130041/0412 10. Mixing mechanism according to one of the preceding claims, "characterized characterized in that the center distance (A) of the mixing shafts is klei ner than the outside diameter (D) of the mixer. 11. Mixing mechanism according to claim 10, characterized in that the ratio of the center distance (A) to the outer diameter of the Mixing mechanism (D) is within the limits of 1: 1.1 to 1: 1.4. g L, _{t (} K. Sch! «» «» 130041/0412