EP0305576A1 - Stirrer for an industriel mixing machine - Google Patents

Abstract

A stirrer for an industrial mixing machine or stirring machine has impellers (100) which consist of at least two parts (10), (20) which are freely twistable relative to each other and relative to a drive shaft (0) and can be locked in any selected position. As a result, the stirrer can be ideally adapted to the current requirements. <IMAGE>

Description

The invention relates to a stirring tool for an industrial mixing or stirring machine, comprising a shaft which can be rotated by a motor and at least two stirring blades attached to it. Such a stirring tool is generally known.

Stirring tools of this type are used for mixing and stirring in pourable, in particular liquid and pasty media, as well as for emulsifying and dispersing.

In practice, a distinction is made between "laminar" and "turbulent" stirring and mixing systems. Stirring tools for laminar stirring and mixing systems include frame stirrers, anchor, grid and finger stirrers. Stirring tools for turbulent stirring and mixing systems include propeller, turbine, disc, basket (or cyclone), bar and / or cross bar stirrers. The type of mixing tool used depends on the objective of the mixing or mixing process. For example, a gentle or intensive mixing, or rapid heat transfer or sedimentation-preventing stirring action and the aforementioned dispersion or the homogenization of solid or liquid aggregates in a carrier fluid may be required.

These different objectives and material conditions require appropriately dimensioned agitators, which in practice requires an extensive inventory of agitators if different objectives and operating conditions are to be taken into account, also taking into account the specified engine power and speeds for driving the agitator shaft.

The selection of a suitable stirring tool is often made empirically when producing a new product. This sometimes makes a large number of attempts with frequent replacement of the stirring tools necessary and is therefore time-consuming.

The invention has for its object to provide a stirring tool of the type mentioned that can be quickly and easily adapted to a variety of different uses and conditions.

This object is achieved by the characterizing features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

The invention provides an agitating tool that can be easily adapted to the requirements by adjusting its impeller parts or by exchanging them with other impeller parts. It is thus possible to achieve a wide range of adaptation to the respective task with one and the same stirring blades, so that the necessary storage of stirring tools can be reduced accordingly. The invention makes use of the knowledge that the displacement capacity and thus the process-related effect of each stirring element is due to the stirring tool projecting into the stirring product area is determined. When using a planar stirring tool, it is thus possible to change this projected stirring blade surface by changing the angle of attack. This results not only in a change in the power consumption on the stirring tool shaft, but also in a change in the flow effects caused by the rotation of the stirring tool in the material to be stirred. This adjustment of the agitator blades can be done in a much shorter time than a complete exchange of agitators. It is thus possible to adapt the shape of the stirring tool to the respective needs to a much finer extent than can be achieved by exchanging stirring tools if a reasonable effort is adhered to.

Preferably, impeller parts are designed so that the blade width decreases in the radial direction from the inside to the outside, so that on the one hand such a blade can be optimally dimensioned from the point of view of strength, and on the other hand the different linear speeds of rotation depending on the radius are taken into account. The lower orbital velocity in the vicinity of the orbital axis requires a larger effective projected area in order to achieve the same flow effect in the material to be stirred than a larger orbiting radius. The stirring tool therefore offers a larger area near the axis of rotation than far from the axis of rotation.

The variable angle adjustment of the impeller parts makes it easy to change the power consumption and displacement efficiency in fluid media. The flatter the angle of attack, the lower the power consumption of the impeller depending on the peripheral speed and the surface projection.

The multi-part design of each agitator blade also allows the flow conditions in the radially outer area to be set independently of those in the radially inner area, since according to the invention the individual parts of an agitator blade can be rotated independently of one another and can be fixed in the selected positions. Usually, the impellers are essentially flat structures with essentially flat surfaces, but the invention also provides special impeller parts which are provided, for example, with a Venturi nozzle or with ribs running obliquely parallel to one another. With such agitator blade parts, special flow effects can be caused in the material to be stirred, for example local compression depending on the peripheral speed, and these effects can also be changed by changing the inclination position of the agitator blade part in relation to the plane in which the agitator blade part rotates. The homogenization of liquid media is improved in particular by means of such Venturi nozzles.

Intensive radial flow components and shear forces in the agitated material can be achieved by means of inclined ribs, which are attached to the wings, these ribs running obliquely to a circumferential radius, with the flow radially outwards, radially inwards, angled upwards or downwards depending on the angular position can be performed, again depending on the inclination of the agitator blade part carrying these ribs against the circumferential plane.

If agitator blades are arranged one above the other in several stages, the flow effects in a container equipped with the agitator tool can be influenced in a special way by suitable selection of the settings of the agitator blade parts.

Flow patterns of various types can be set therein, in particular also countercurrents, which lead to particularly intensive mixing. For example, a radially inwardly directed flow component can be imparted to the material to be stirred in one stage, while a radially outwardly directed flow component is generated in the adjacent stage. Likewise, flow components can also be generated parallel to the axis of the shaft of the stirring tool, which run opposite to the axis near the axis near the axis.

In operation, the invention enables the mixing tool to be optimally adapted to a given motor power or rated speed of the drive motor, i.e. adjust the stirrer if necessary, taking into account a possibly not reached optimum of the stirring action, so that just the nominal power or the nominal speed of the drive motor for the stirrer is achieved. The invention makes it possible, if necessary, to approach this position of the agitator blade parts of the agitating tool, which can achieve such conditions on the drive shaft, by experiment.

When using sheet-like, blade-shaped impeller parts, in the processing of fluid media which contain constituents that tend to sediment, suitable adjustment of the angle of attack of the impeller parts against the circumferential plane can result in such sedimentation being hindered. This is achieved by means of settings which, in areas where sedimentation tends to occur, for example under the stirring tool shaft or in the center of a stirring container with a centrally positioned stirring tool, cause or promote the formation of intensive currents.

Alternatively, where sedimentation or separations are to be carried out under centrifugal forces, the formation of currents in the stirred material which favor the processes mentioned can be brought about by suitable selection of the setting angle of the impeller parts or replacement thereof.

It is also possible to use those impeller parts which have knife edges in order to comminute the material to be stirred. In connection with impeller parts which have a mixing-promoting effect, a stirrer can thus be designed into a comminutor with which a comminution result with a relatively uniform particle size distribution can be achieved in a short time.

In summary, it can be said that with a minimum set of different impeller parts, a suitable combination and choice of settings can be used to perform a multitude of tasks, so that the risk of a bad investment for the user is small.

• Fig. 1 eine Teildarstellung eines Rührwerkzeugs mit einer vollständigen Darstellung eines Rühr­flügels mit den Merkmalen der Erfindung von der Seite,
• Fig. 2 eine Einzelheit aus Fig. 1, das radial innen liegende Rührflügelteil zeigend, sowie Schnitte durch dieses Flügelteil, aus denen unterschied­liche mögliche Anstellwinkel erkennbar sind,
• Fig. 3 eine weitere Einzelheit aus Fig. 1, das mitt­lere Rührflügelteil in Draufsicht zeigend,
• Fig. 4 eine weitere Einzelheit aus Fig. 1, das radial außen liegende Rührflügelteil zei­gend, und zwar (a) in Draufsicht und (b) in seitlichem Schnitt.
• Fig. 5 eine Venturidüse als ein wahlweise verwend­bares radial außen liegendes Rührflügelteil,
• Fig. 6 zwei zu beiden Seiten einer Achse gelegene äußere Rührflügelteile, bei denen jeweils Verturidüse mit einem blattförmigen Rührflü­gelteil integral vereinigt ist, und zwar (a) von der Seite und (b) in Richtung der Umlaufachse gesehen,
• Fig. 7 eine vergrößerte perspektivische Teildar­stellung eines integral mit einer Venturidüse vereinigten Rührflügelteils, und
• Fig. 8 eine andere Ausführungsform eines radial außen zu montierenden Rührflügelteils, das im Endbereich geteilt und in entgegengesetzte Richtungen verschränkt ist, und zwar (a) in Seitenansicht und (b) in stirnseitiger Ansicht vom freien Ende aus, wobei die Figur eine zur Umlaufachse symmetrische Anordnung zeigt.

The invention will be explained in more detail below with reference to the drawings. It shows:

• 1 is a partial view of a stirring tool with a complete representation of a stirring blade with the features of the invention from the side,
• 2 shows a detail from FIG. 1, showing the impeller part located radially on the inside, and sections through this part of the impeller, from which different possible angles of attack can be seen,
• 3 shows a further detail from FIG. 1, showing the middle impeller part in a top view,
• Fig. 4 shows a further detail from Fig. 1, the radially outer impeller part, namely (a) in plan view and (b) in side section.
• 5 shows a Venturi nozzle as an optionally usable radially outer impeller part,
• 6 two outer impeller parts located on both sides of an axis, in each of which Verturi nozzle is integrally combined with a leaf-shaped impeller part, namely (a) seen from the side and (b) in the direction of the circumferential axis,
• 7 is an enlarged partial perspective view of an impeller part integrally combined with a venturi nozzle, and
• Fig. 8 shows another embodiment of an impeller part to be mounted radially on the outside, which is divided in the end region and folded in opposite directions, namely (a) in a side view and (b) in an end view from the free end, the figure being symmetrical with respect to the circumferential axis Arrangement shows.

Fig. 1 shows a partial representation of an agitator tool and can thereby fully recognize the inventive design of an impeller. In the figure, only one impeller 100 is shown attached to a drive shaft 0 in a rotationally fixed manner, while a second impeller, which is rotationally symmetrical to the first impeller 100 and is at the same axial height, is only indicated. The impeller 100 consists in the present case of three parts 10, 20 and 30, which in seen in the radial direction are arranged one behind the other.

The first, radially inner impeller part 10 is connected in a rotationally fixed manner to the drive shaft 0 by means of a bush 40. We will have to go into details later. The second, middle impeller part 20 is attached to the radially outer end of the first impeller part 10. Finally, the third, radially outer impeller part 30 is attached to the radially outer end of the second impeller part 20.

In the present example, the three agitator blade parts 10, 20, 30 are designed as flat, blade-like plates which extend essentially in the radial direction. All connections of the impeller parts with the socket 40 or with one another are designed such that the impeller parts are freely rotatable, each with a radius to the drive shaft 0 as the axis of rotation, and can be fixed in their rotational positions. Details of this will be discussed later. In Fig. 1 it can be seen from an upper edge visible on the impeller part 10 and a lower edge visible on the impeller parts 20 that these impeller parts are inclined in opposite directions to a plane in which the impeller 100 rotates, while the outer impeller part 30 transversely to the direction of the Orbital movement around the axis of the drive shaft 0.

As can be seen from Fig. 2, a radially extending with respect to the circumferential axis of the drive shaft 0 sleeve 11 is welded to the radially inner end of the first impeller part 10, which is inserted into a corresponding recess formed longitudinally in the impeller part 10 and ver at the edges thereof is welded. At the inner end of the sleeve 11 facing the impeller part 10, the impeller part 10 is provided with an approximately circular opening 12. The inner end of the sleeve 11 protrudes into this opening 12.

In the area of its radially outer end, the first agitator blade part 10 is provided with two bores 13 one behind the other in the radial direction with respect to the axis of the drive shaft 0, which serve to fasten a connecting element 50.

The bush 40 is mounted on the drive shaft 0 in a rotationally fixed manner by means of a wedge 41. Other anti-rotation devices, such as slot wedge connections, clamping screws screwed through the bushing 40 and the like, can also be used. The bushing 40 carries a plurality of radially extending connecting pins 42 which are evenly distributed in the circumferential direction, one of which is shown in FIG. 2. The connecting pin 42 has a collar 43 which is integrally connected to it and by means of which the connecting pin 42 is fastened to the socket 40 by welding.

The sleeve 11 of the first impeller part 10 is pushed onto the pin 42. Your free, i.e. end pointing away from the impeller part 10 is supported on the collar 43. The pin 42 carries at its free end a threaded portion 44 onto which a nut 45 is screwed, with the aid of which the impeller part 10 is thus fastened to the bush 40. The nut 45 is accessible for a suitable tool due to the opening 12 in the impeller part 10.

After loosening the nut 45, the impeller part 10 twisted on the pin 42 and fixed by tightening the nut 45 in any selected position.

On the right of the representation of the impeller part 10, three possible inclination positions of the impeller part 10 are shown as cuts in FIG. 2 as a selection.

2, the width of the impeller part 10 decreases from the inside to the outside. This takes into account the various speeds at which the impeller part 10 strikes the material to be treated.

FIG. 3 shows the middle impeller part 20 from FIG. 1 in a side view. This is designed essentially in the same way as the first impeller part 10, but its dimensions may be smaller, as shown in FIG. 1. The details of the second impeller part 20, which correspond to those of the impeller part 10 of FIG. 1, are provided with reference numerals increased by 10 and need not be explained again.

FIG. 3 also shows the connecting element 50, with which the first and second impeller parts 10 and 20 are connected to one another. The connecting element 50 has a forked shaft 51 and a connecting pin 52. At the transition between the forked shaft 51 and the pin 52, the connecting element 50 carries a collar 53 formed integrally with it. At the free end of the pin 52, a threaded section 54 is formed. The sleeve 21 of the second impeller part 20 is pushed onto the pin 52 and secured there in a rotationally fixed manner by means of a nut 55 screwed onto the threaded section 54. By loosening the mother 55, the second impeller part 20 can be rotated on the pin 52 and fixed by tightening the nut 55 in any selected position.

At the other, outer end, the impeller part 20 has two bores 23, which are used to attach a connecting element 60 for connecting the third, outer impeller part 30.

FIG. 4 shows the third, outer impeller part 30 in a top view (FIG. 4a) and in a lateral section (FIG. 4b). FIG. 4b also shows the type of attachment to the middle impeller part 20, which corresponds entirely to the type of attachment of the middle impeller part 20 to the first impeller part 10.

In the present example, the third, outer impeller part 30 is relatively short in the radial direction compared to the other impeller parts 10 and 20, but is relatively wide for this. It carries on both sides approximately perpendicular to the surface extension of this impeller part 30, blades 34 extending parallel to one another, which begin at the radially outer edge and extend obliquely over about a third of the radial extent of the impeller part 30. These blades 34 are intended to produce a special shearing action in the material to be treated and to promote emulsification processes. The angle that the blades form with the drive shaft radius is 30 to 60 °. The third impeller part 30 is fastened to the second impeller part 20 by means of the connecting element 60 already mentioned, which is completely the same as the connecting element 50 and, like that, allows the rotary positions of the third impeller part 30 to be freely selected with respect to the second impeller part 20. The details of the connector 60, those of the connector 50 correspond to reference numerals increased by 10, which therefore speak for themselves, so that a repetition of the explanation can be omitted.

4b shows, the forked shaft 61 sandwiches the second impeller part 20 between them. The shaft 61 is provided with two bores 66 which are aligned with the bores in the second impeller part 20. Screw bolts 67 are screwed through these holes. Regarding the attachment of the second impeller part 20 to the first impeller part 10, reference is made to the preceding explanation.

FIG. 5 shows an alternative embodiment of an impeller part 70 which can be used as a radially external part and which is essentially characterized by a Venturi nozzle 74. This impeller part consists of a plate 70 'which, in the manner of the impeller parts described above, carries a sleeve 71 for attachment to a connecting element 60 in the manner already explained, which ends in an opening 72. The aforementioned Venturi nozzle 74 is welded to this plate 70 at the end facing away from the sleeve 71. The Venturi nozzle 74 consists of two trapezoidal side plates 75, one of which is welded to the plate 70 ', and two cover plates 76 connecting the two side plates 75 to one another, which converge and form a funnel-shaped inlet, as in Fig. 5 in the two Sectional views to the right of the side view is shown. The direction of flow of the material into the Venturi nozzle 74 when the stirring tool rotates is indicated in the sectional views in FIG. 5 by arrows.

As in the examples described above, the impeller part 70 can be rotated on the connecting element 60 and fixed in any rotational position. The right sectional view in FIG. 5 shows a position in which the Venturi nozzle 74 is rotated by an angle α with respect to the sectional view shown to the left thereof.

When circulating in fluid media, this Venturi nozzle causes it to compress as it passes through the nozzle, depending on the speed of movement of the Venturi nozzle in the medium. Depending on the angular position, the achievable stirring intensities can be set. This affects not only the compression within the nozzle but also the flow around the nozzle. The ram jet effect of the Venturi nozzle causes compression of the stirred medium and thus a high flow velocity of the same in the nozzle, in contrast to the areas of the medium to be stirred which are not covered by the Venturi nozzle, as a result of which homogenization processes can be accelerated.

Fig. 6 shows a side view and a top view of two rotationally symmetrical outer agitator blade parts 80, in which agitator blades 80 'approximately trapezoidal shape with Venturi nozzles 84 are integrally combined. As can be seen from both representations of FIG. 6, the Venturi nozzles 84 are arranged in a rotationally symmetrical manner with respect to the axis, which is only shown schematically here, so that they each have the same effects when circulating through the material to be stirred. It is understood that in this case, too, the impeller parts 80 can be brought into arbitrary angular positions and can be fixed in them. The facilities required for this need not be explained again.

Fig. 7 shows a perspective view as a detail of the end of an impeller part 80 from Fig. 6. It can be seen that in the region of the free end of the plate 80 'a breakthrough is formed in which a Venturi nozzle 84 is used, the structure of which 5 is completely the same, which is why a more detailed explanation can be dispensed with here. The Venturi nozzle 84 is preferably fixed in the cutout in the plate 80 'by welding.

Fig. 8 shows in a rotationally symmetrical arrangement with respect to the axis of the drive shaft 0 shown only schematically, two outer impeller parts 90, which are designed as flat, to the free end narrowing plates 90 '. These plates 90 'are each provided at the radially outer end with a central incision S, which extends in the example shown over about 25% of the length of each plate 90'. The flags 94 and 95 lying on both sides of this incision S are crossed in opposite directions, i.e. bent out of the plane in which the remaining portion of the plate 90 'extends. FIG. 8a shows the representation from the side, while FIG. 8b shows an end view from which the different directions of entanglement of the flags 94 and 95 can be clearly seen. FIG. 8b also shows that one impeller part 90 has an opposite position to the other impeller part with respect to an orbital plane around the axis of the drive shaft 0.

Due to the different entanglement of the ends of the impeller parts 90, movement components can be produced in the medium to be stirred which are directed radially and in opposite directions to one another Directions. This achieves homogenization in the medium to be stirred.

It can be seen from the preceding illustration that it is possible to combine different parts of the impeller depending on the intended use, which of course requires standardization of the connecting elements. The stirring tool is extremely versatile and can be largely adapted to the respective needs. The amount of stirring tools or stirring tool parts to be kept can be considerably reduced.

Claims (10)

1. Mixing tool for an industrial mixing or stirring machine, comprising a shaft (0) which can be rotated by a motor and at least two stirring blades (100) attached thereto, characterized in that each stirring blade (100) consists of at least two parts (10, 20 , 30,70,80,90), of which the one (inner) impeller part (10) is detachably and adjustably attached to the shaft (0) at one (inner) end, and that at the other (outer) end of the inner Impeller part (10) the other (outer) impeller part (20) is detachably and adjustably attached. 2. Stirring tool according to claim 1, characterized in that the inner impeller parts (10) are each attached to pins (42) which extend in the radial direction from a sleeve (40) carrying them, which is attached to the shaft (0) and is non-rotatably connected to this. 3. Mixing tool according to claim 2, characterized in that each outer impeller part (20,30,70,80, 90) is attached to a pin (52, 62) which is attached to the outer end of the respective inner impeller part and from there extends substantially radially outward. 4. Stirring tool according to claims 2 or 3, characterized in that the impeller parts each have a sleeve (11, 21, 31, 71) for receiving the pins (42, 52, 62) and an opening (12, 22 in the end region of the sleeves) , 32, 72), and that the pins have at least at their free end an external thread (44, 54, 64) onto which a nut (45, 55, 65) braced on the associated sleeve is screwed. 5. Stirring tool according to claim 3 or 4, characterized in that the pins carrying the outer impeller parts are forked on their end facing the inner impeller part (51, 61) and the fork legs rest on both sides of the inner impeller part and thereon by means of screw bolts (67) are attached. 6. Stirring tool according to one of the preceding claims, characterized in that one of the impeller parts (70, 80) carries a Venturi nozzle (74, 84), the opening of which is arranged transversely to the direction of movement of the impeller part when the shaft (0) rotates. 7. Mixing tool according to one of the preceding claims, characterized in that one of the impeller parts (30) carries a plurality of ribs (34) which run parallel to one another and which are at an angle between 30 ° and 60 ° with respect to a radius through the shaft (0) run. 8. Stirring tool according to one of the preceding claims, characterized in that the impeller parts (10, 20, 30, 80, 90) are formed at least in a partial area, tapering in the radial direction from the inside to the outside. 9. Stirring tool according to one of the preceding claims, characterized in that the outer impeller part (90) of each impeller (100) is flat and cut in its end region in the radial direction (S), and that of the cut (S) from each other divided flags (94.95) of the impeller part (90) are crossed in opposite directions. 10. Stirring tool according to one of claims 2 to 8, characterized in that on the socket (40) more than two pins (42) are attached in a uniform angular distribution.

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