DE2240245B2 - MIXING DEVICE, IN PARTICULAR FOR GRAINY GOODS - Google Patents

Description

In most known mixing devices, the contour of the blades is not critical, since only one

with high turbulence occurring forward movement of the material to be mixed along the mixing trough is to be achieved.

From GB-PS 10 51 651 a mixing device of the type described above has become known, in which the airfoils are H-shaped, the airfoils of the one shaft have an opposite pitch angle as the blades on the other shaft. Respectively an airfoil of one shaft is to an airfoil of the other shaft in the axial direction arranged offset This known mixing device leads to a known mixing process, which is unsatisfactory in terms of its intensity or the homogeneity of the mixed goods

From DT-PS 86 806 a mixing device with a shaft is known, the blades of which are elliptical. This mixing device, which differs from the type in question here, also has however, only one wave leads to unsatisfactory mixing results.

The invention has for its object to provide a mixing device with which a counter over the known mixing process new mixing process is to be practiced, whereby by means of a separation or Cutting process as well as a displacement process in each case mix quantities alternately from Area of one shaft should reach the area of the other shaft and each with such a mix quantity engaging shovel blade the mixed material portion again divided into two subsets and an adjacent airfoil the other Shaft feeds, which proceeds in the same way etc, us.i on this Way to ensure or a particularly thorough and intimate mixing of the good components to obtain largely homogeneous mixed goods.

As a solution to this problem, according to the invention in a mixing device of the type described at the outset it is provided that the blades have the shape of circular secto-like cut-out ellipses, which are attached with their main and minor axes intersecting the respective shaft axis that the Pitch angles of the blades formed by the main axis of the ellipse and the shaft axis the same size on the shafts driven in opposite directions at the same speed, from shaft to shaft however, it is provided in the opposite direction, and that in each case an airfoil of the one shaft is an airfoil the other shaft forming an airfoil pair, is arranged opposite one another without an axial offset.

As can already be seen from the above, the mixing device according to the invention works according to a new mixing process in which, due to the inside of the mixing trough rotating two mutually parallel shafts with those arranged on them, designed in a special way Shovel blades result in a mixing process in which mixed material partial quantities due to a cutting process and a displacement process are alternately moved from one shaft to the other shaft and each with one of these mixed material quantities engaging blade of a shaft turn the amount in question into two Divided subsets and thereby one of the subsets to a display sheet that is in turn adjacent to it another wave feeds, which in turn repeats this process, etc. The sequence of operations takes place continuously, so that the mix before exiting the mixing trough one of the number of number of existing blades corresponding to the number of existing blades has been subjected to subdivision operations.

The mixing principle according to the invention is therefore based on the fact that partial amounts of mixed material are separated from one another treated individually after they have been brought into a position in front of any blade have been. This mixing process, which brings about a very thorough and intimate mixing, is of so complicated in nature that it can only be seen as a repetitive subdivision of the A further description of the The mixing process on which the invention is based is carried out below on the basis of an exemplary embodiment.

Preferred embodiments of the invention emerge from the subclaims.

The invention is further based on an exemplary embodiment with reference to a drawing explained. It shows

F i g. 1 shows a partially sectioned side view of a mixing device,

F i g. 2 shows an end view of the mixing device according to FIG. 1.

F i g. 3 shows an enlarged partial section of the mixing device according to FIGS. 1 and 2 in the direction the section line 3-3 in F i g. 2 seen

4 is a plan view of the mixing device of F i g. 1 to 3,

F i g. 5 shows an enlarged sectional illustration in the direction of the section line 5-5 in FIG. 4 seen

6 is an exploded representation of a view similar to FIG. 5, in which the mixing trough for cleaning in one of the rest of the mixing device released position is shown.

F i g. 7 shows an enlarged partial section through the device according to FIG. 1 towards the Section line 7-7 in FIG. 1 seen

F i g. 8 is a side view of a blade consisting of an airfoil and a hub;

F i g. 9 is a front view of the blade according to FIG. 8th,

Fig. Iü a schematic representation of time successive positions of two juxtaposed and interacting with each other Blades of a pair of blades,

F i g. 11 is a schematic representation of the between two blades according to FIG. 10, overlapping positions present during a short time interval of a revolution; and

Fig. 12 is a schematic representation of successive Positions of two mutually cooperating blades of a blade pair a variant.

The drawing shows a generally designated 10 mixing device on a top End of a support frame 12 is arranged on bearings 15 supported turntable 14.

Pumps PX and Pl are supported on the support frame 12 and serve to convey liquid substances, for example a catalyst and a binding agent, which are to be added in doses to a granular material to be mixed in the mixing device 10.

The mixing device 10 has a mixing trough 20 which receives the material to be mixed. By doing Mixing trough 20 are two mutually parallel, bladed blade shafts 21 at a mutual distance

and 22 , which cooperate in the mixing process. The blade shafts 21, 22 are horizontal and rotate in opposite directions. The on the blade shafts 21,

22 arranged blades or blades on which will be discussed in more detail below, cause a continuous subdivision of the in the mixing trough 20 located good, in which they penetrate or cut into the good to be mixed and at the same time the Promote mixed material in the longitudinal direction of the mixing device to an outlet.

The mixing trough 20 is attached to a frame so that it can be removed. The frame consists of a square base plate arranged on the turntable 14

23 and a laterally projecting frame part 24, arranged on the base plate 23, on which in turn four upwardly extending columns 26 are arranged, which serve to support an upper frame part 28.

On the upper frame part 28, a vertically extending supply pipe 30 is arranged, which with a The storage container 32 containing the material to be mixed is connected to the upper frame part 28 Pressure medium-actuated closure means 34 with a slide plate 36 and one with the slide plate 36 cooperating, manually operable control plate 38 arranged

Attached to the four columns 26 at a distance from one another are two support bars 40 protruding laterally beyond the turntable 14, at the outer ends of which a front end wall 42 of the mixing trough 20 is arranged. A rear end wall 44 is attached to the inner ends of the support bars 40 and is supported on the frame part 24, which forms a type of base plate (FIG. 1)

On the support bars 40 , angle irons 46 are also attached at various points, which serve to support locking devices 48 which hold the mixing trough 20 releasably on the support bars 40.

As shown in FIGS. 5 and 6, the mixing trough 20 has two side walls 50 and a bottom 52 which is divided into two flat, semi-cylindrical channels 52a and 52 ^. The grooves 52a, 526 are separated from one another in the longitudinal direction by an upstanding rib 56

Angle profile strips 58 are welded to the upper edge regions of the side walls 50, the horizontal legs of which lie somewhat below the upper edges of the side walls 50.

The locking devices 48 are used to set the mixing trough 20 to the Abstützholmen 40. Each locking device 48 comprises a lever 60, whose one end is pivotally mounted on a associated with an angle iron 46 bracket 62 on each arm 60 is a bell crank 64 pivoted, further is rotatably connected to a clamp arm 66 hinged to the ss bracket 62. Ke position of the toggle link 64 and its articulation points on the lever 60 and on the clamp arm 66 and selected so that the toggle lever 64 pivots the clamp arm 66 from the mixing trough 20 when the lever 60 is in its in Fig. 6 position shown is pivoted outward.

When the lever 60 is pivoted to the position shown in Figure 5 Steflung inwardly, the clamp arm 66 anderWmk ^ ^ rofiTleiste58zurAnla unddrücktdiese arrives at the associated AbstOtzhofan 49th The toggle lever member 64 moves up slightly beyond its dead center and locks the mixing device in a position in which it holds the mixing trough 20 in place

At the free end of the clamping arm 66 an adjusting screw 67 is provided, by means of which the clamping pressure exerted on the angled profile strip 58 can be adjusted.

As shown in FIGS. 1 and 4, an outlet opening 68 for the mixed material is provided at the front end of the mixing trough 20.

The two vane shafts 21 and 22 described in more detail below are similar to one another, so that it is sufficient if only one of the two blade shafts is described below.

The blade shaft 21 consists of an actual shaft 70 and a number of blades 72 (FIGS. 5, 6, 8 and 9) which are arranged in the longitudinal direction on the shaft 70.

Each blade 72 has a hub part 74 to which a blade 76 is welded, which consists of a flat disk in the form of an ellipse cut away in the manner of a circular sector (FIG. 9).

The blade plane and thus the major and minor axes of the relevant ellipse intersects the respective shaft axis at an acute angle of about 45 °.

The blades 72 are pushed onto the shaft 70 with their hub parts 74 lying end to end, in such a way that all the blades 72 are parallel to one another and are inclined relative to the shaft 70 so that they have a slope directed to the left. Because of this slope, when the shaft rotates clockwise, the blades 72 act on the material to be mixed in such a way that they convey the material in the direction of the outlet opening 68. The blades 72 are connected to the shaft 70 by means of suitable fastening elements such as wedges 78 or screws 80.

The vane shaft 22 is designed similarly to the vane shaft 21. The same reference numerals are therefore used for them, but preceded by the number “1”.

It should be pointed out that, in contrast to the blade blades 76 attached to their hub parts 74 with a pitch angle pointing to the left, the blade blades 176 of the blades 172 arranged on the shaft 170 are each attached to their hub part 174 at a pitch angle pointing to the right.

For the purpose of counter-rotating rotation of the vane shafts 21 and 22, the front ends of the shafts are mounted 70 and 170 in bearings 79, while the rear ends of the shafts extend 70,170 through openings provided in the rear end wall 44 openings in a gear housing 81 in bearings in which it 82 are stored. Gear wheels 86 and 88 (FIG. 7) seated on the shafts 70 and 170 and engaged with one another cause the shafts 70, 170 to rotate in opposite directions when the wire 70 is driven by a motor Afl which is coupled to the shaft 70 via a coupling 89 is connected

If the mixing device 10 is used, for example, for processing foundry sand, the. Sand is supplied to the mixing trough 20 from the storage container 32 via the supply pipe 30, while the pumps P1 and 3Ϊ convey a catalyst and a liquid binder into the mixing trough 20. The pump Pl driven by a motor A / 2 is at its Sangsehe πώΐ a storage container for the Raftj ^ satoruiri to flwerDrticäcsefte via a fl ^ t

connected to a nozzle 92, which is close to that a ~. "

ΔΔ 4U

Area of the mixing trough 20 is arranged in which the sand passes from the feed pipe 30 into the mixing trough 20. The pump P2 driven by a motor M 3 is similarly via a flexible line 94 with a liquid binder in the mixing trough 20 ■; introducing nozzle% connected. Arranged on a control panel 102, manually operable control means 98 and ICLO are located in the lines 90 and 94th

The impeller blades 76, 176 are designed in such a way that when the two shafts 70 and 170 move at the same time during a full revolution, the impeller blades 76 of one shaft 70 do not engage with the impeller blades 176 of the other shaft 170 . This non-interlocking or non-overlapping of the blade blades 76, 176 , shown schematically in FIG. 10, together with the other features of the inventive teaching, leads to a novel mixing process.

With regard to the arrangement of the blades 76 and 176 along the shafts 70 and 170, it should be noted that the blades 72 and 172 or their hub parts 74 and 174 are arranged side by side on the shafts 70 and 170 , so that each blade 76 an airfoil 176 , which is positioned exactly to the side of it, is assigned in each case with the formation of an airfoil pair. Although the blades 76 and / or «>. 176 rotate in opposite directions, the movement of the respective airfoil of an airfoil pair assigned to an airfoil is not hindered on the other shaft.

In Fig. 10 eight positions are shown, which are assumed by a pair of adjacent blades 76 and 176 as the movement progresses, initially in an initial 0 ° position in which both blades 76, 176 are on the same side of their shaft 70 and 170 take a similar position. This is followed by the positions below at 45 ° intervals up to a 315 "position, which is then again followed by the 0 ° position ^{after another 45 = clearly.}

When considering these positions, it must generally be taken into account that the blades 76, 176 are flat and that their contour is semi-elliptical, although the blades 76, 176 are shown semicircular in the drawing because they are seen at a viewing angle of 45 ° .

In the 0 ° position located at the top in FIG. 10, that is to say the 45 "position of the two blades 76, 176, one tip of the blade 76 appears to be in contact with the tip of the blade 176. In fact, however, the tips are at a considerable mutual distance from one another.

Similarly, in the 225 ° position of the two blades 76, 176 the tip of the blade 76 is at a considerable distance behind the tip of the blade 176.

•. For this reason there is always a spacing between adjacent blades 76, 176 present while in none of the positions shown there is a significant overlap between the blades 76, 176

The vane sizes, vane blade contours and vane clearances shown actually exist between the 45 ° position and the 90 ° position. ne very slight overlap of the blade tips has no effect on the mixing process. You fet in Fi g. 11, in which the movement of the shovel

Sheets 76, 176 are shown at 10 ° intervals between the 50 ° position and the 90 ° position.

A second area with a slight overlap lies immediately behind the 270 ° position, where the one tip of the airfoil 76, due to its faster circular movement, sweeps over the inner area of the adjacent edge of the opposite airfoil 176 . This small overlap, however, very quickly becomes zero, since this edge falls back, with no overlap whatsoever between the two blade blades 7fi 176 in the 315 ° position.

During operation, the mix is continuously separated or divided by the blades 76, 176 , displacement taking place in which steadily decreasing material masses are thrown from one side of the mixing trough to the other or from one channel 52a into the other channel 52Z> and the material is divided into smaller portions as it moves along the mixing trough 20 and is thoroughly and intimately mixed in the process.

In order to achieve the greatest possible efficiency, the control plate 38 is set so that the material level in the mixing trough 20 does not exceed the maximum height of the paddle blades 76, 176. In this way, a surprisingly thorough mixing is brought about by a geometric progression of dividing processes.

In practice, it has been found that equal amounts of black and white sand separately introduced at the inlet end of the mixing trough 20 are mixed to form a sand of a uniform gray color before reaching the fourth pair of opposing blades 76 and 176, respectively.

It can thus be seen that any material which has been subjected to the severing and impacting action of all of the paddle blades 76, 176 located in the mixing trough 20 emerges from the outlet opening 68 in a thoroughly mixed state.

Under certain conditions, for example in the aforementioned processing of foundry sand, the sand may be mixed with a catalyst and a binding agent! be desired by a kneading process in which the individual grains are inevitably brought into close contact with one another in order to provide all grains of the material with a uniform coating of binding agent. In such a case, the required turbulence of the sand can be achieved by using shallow, semi-elliptical blades with surfaces that push back the sand, because not all areas of the blades which normally cause the sand to move back are cut away. Such an airfoil shape is shown schematically in FIG. It can be seen that the cut-away areas of the shovel blade 276 and 376 extend only approximately over 90 °.

In this embodiment according to the invention, the scoop blade egg occurs during one full revolution 276, 376 - apart from the blade controls exactly corresponding to the 0 ° position and the 180 ° position - always overlaps, the largest being There are overlaps in the 90 ° position and the 270 ° position, in which the overlap is somewhat 25% reached Direction of rotation, inclination and incline of the blades 276,376 are the same as for the dei Blade 76 and 176.

In Fi g. 12 the overlapping areas are hatched

009530 / 4S

drawn. In this case, an area of the airfoil 276 that overlaps a part of the airfoil 376 represents an area which exerts a backward pressure on the sand. This area is opposite an area of the airfoil 376 which exerts forward pressure on the sand. This results in a compaction and scrubbing effect that is aimed at in commercially available sand processing plants. Since the axial pressure exerted by all of the impeller blades 276, 376 is predominantly directed forwards, the constant forward movement remains

of the sand along the mixing trough 20 received.

In the two embodiments of the invention described above, certain principles of the mixing process are the same. In general it can be said that the degree of mixing is a function of the length of the mixing trough 20 and the shape of the blades 76, 176, 276, 376, while the throughput of material through the outlet opening 68 is a function of the rotational speeds of the shafts 70 and 170 and the pitch angle of the blades 76, 176, 276, 376.

For this purpose 3 sheets of drawings

3

Claims (7)

Patent claims: ! Mixing device, especially for granular material. with an elongated, horizontally arranged mixing trough, which at one end has an inlet for the material to be mixed and at its other end an outlet for the mixed material, and with two spaced parallel to each other in the mixing trough, extending in its longitudinal direction extending driven shafts, on each of which a row of axially spaced and parallel rows of blade-shaped blades are attached to the respective shaft at an angle of inclination, the largest radial extension of which from the shaft in question is somewhat smaller than the clear distance between the two shafts , characterized in that the blades (76, 176) have the shape of ellipses cut out in the manner of a sector of a circle. which are attached with their main and minor axes intersecting the respective shaft axis; that each of the major axis of the ellipse and ^Wei:; however nachse formed pitch angle of the blades (76, 176) to the driven in opposite directions at the same speed shafts (70, 170) of equal size, of shaft (70) to shaft (170) is provided opposite; and that in each case an airfoil (76) of the one shaft (70) corresponds to an airfoil (176) of the other shaft (170); Forming an airfoil pair, is arranged opposite one another without an axial offset. 2. Mixing device according to claim 1, characterized in that the bottom (52) of the mixing trough (20) is divided in the longitudinal direction into two grooves (52a, 526), the walls of which are surfaces of revolution which are generated by the rotational movement of the airfoils (76, 176). 3. Mixing device according to one or both of the preceding claims, characterized in that that the channels (52a, 526) of the mixing trough (20) by a straight, upright rib (56) are separated from each other. 4. Mixing device according to one or more of the preceding claims, characterized in that that the pitch angle of the blades (76,176) is 45 ° 5. Mixing device according to one or more of the preceding claims, characterized in that that the blades (76,176) have the shape of a semi-ellipse divided along their main axis to have. 6. Mixing device according to claim 5, characterized in that the paddle blades (76, 176) a pair of airfoils are mounted on the shafts (70, 170) in such a way that an airfoil (76) above and the other blade (176) below the through the two shaft axes laid plane is ^ 270 ° position in Fig. 10 or 90 ° position in Fig. 11). 7. Mixing device according to one or more of the preceding claims, characterized in that that the blades (76, 176) attached to sleeve-shaped hub parts (74, 174) are pushed onto the shafts in adjacent positions and against longitudinal displacement and rotation are removable. The invention relates to a mixing device, in particular for granular material, with an elongated, horizontally arranged mixing trough, which at one end has an inlet for the material to be mixed and on its other end has an outlet for the mixed material, and with two parallel at a distance each other arranged in the mixing trough, extending in the longitudinal direction of the driven Shafts on each of which a row of axially spaced and parallel rows, attached to the respective shaft at an angle of inclination, disk-shaped blades are, the largest radial extent of the shaft in question is slightly smaller than the clear Distance between the two waves. Mixing devices of this type can be used, for example, for the preparation of foundry or molding sand, whereby for this area of application a substitutability is sought not only for the case in which an exclusively granular material is present, but also when, for example, the molding sand has a liquid binder or a liquid catalyst is added with which the hardening of the sand during the molding process is to be facilitated. The use of such mixing devices is not limited to the foundry area, however, but it is also used, for example, for mixing granular materials for making concrete or plaster of paris or, for example, when iodising salt. In addition, there is an area of application, for example, in the use of such Mixing devices for mixing plastic or semi-solid mix or for mixing fibrous solids with liquids. The mixing processes that occur when known mixing devices are used are very different. Mostly the aim is to create an uncontrolled, so to speak, turbulence in the mixing trough as much as possible cause random and random or random mixing process. In other mixing devices, the paddle blades act of the two shafts in opposite directions onto the mix. Mixing devices are also known in which a helical blading for the Waves is used, which generates parallel streams of mix, with subsets of the two Mixture flows are transferred from one mix flow to the other by the formation of eddies. Mixing devices with alternating blades are also known, which the mixed material Issue movements of different types, the mixed effect by changing from one type of movement to the other. While in some of the known mixing devices the paddle blades when rotating the two mutually parallel shafts intermesh in order to generate a high level of turbulence for the mixing process, in other mixing devices, the shafts are again so far apart that the The blades of the two shafts cannot interlock, so that the mixing process takes place on a Lateral tossing of mix from the area of one shaft to the area of the other Wave restricted.