EP0019288A1 - Method and apparatus for continuously mixing of dry and wet products, especially of dry mortar ready for use - Google Patents

Abstract

A device for mixing mortar with a liquid or foaming material includes a reservoir for the dry mortar, a housing containing a portion of a driven shaft with the housing terminating at one end in a mixing chamber; the mixing chamber contains a disc attached to the shaft and rotatable therewith; on one side of the disc, there is located radially extending mixing paddles or blades, the outer edges of the blades and the discs being spaced a predetermined distance to define a gap between the inner surface of the wall of the mixing chamber and the outer edge of the blades and disc; at one end of the mixing chamber an outlet is provided which is connected to a suction device and a baffle ring is situated about the outlet to divert material away from the suction inlet.

Description

The invention relates on the one hand to a process for the continuous mixing of a coarse-grained to powdery dry mortar, e.g. a plaster and masonry mortar with a liquid and / or a foam material in a mixing chamber, which is connected upstream of a storage container for the dry material and a suction device for the mixed material. Furthermore, the invention also relates to an apparatus for performing this method.

From DE-GM 7 046 623 a device for performing this method is known. The dry material pressed out of a storage container by means of a screw conveyor falls into a vertical mixing tube in which a dry material scraper circles and which is followed by a feed pump. Since the conveying device for the dry material and the mixing device are driven by two separate motors, the mixing device can be completely emptied independently of the dry material to be conveyed. The mixture leaving the mixing device contains only a relatively small proportion of air pores, which leads to the disadvantages listed below. Lime cement After application, plasters and cement plasters tend to form drying cracks on the surface to be plastered, which can occur after minutes or hours. In addition, there is a risk of stress cracks after a longer period of time. With conventional plasters, these dangers have been reduced by applying the plaster mortar in several layers. It has also been shown that coarser sands reduce the tendency to crack in the plaster. However, the conventional cleaning process was very time-consuming and labor-intensive.

So-called single-layer plasters have therefore been developed, which can also be processed with continuous mixing pumps. In order to guarantee perfect machine operation, the grain size of these materials had to be reduced to 1 - 1.5 mm.

In order for single-layer processing to be possible with these plasters, chemicals had to be added for the formation of air voids and water retention. Good results were also achieved with batch-type compulsory mixers, but the material was mixed too short for the continuous mixing pumps customary on the market (e.g. DE-GM 70 46 623). As a result, only a few air pores were introduced and the tendency of the plasters to crack again increased considerably.

The invention has for its object to provide a method and an apparatus with which it is possible to prepare plasters or mortar that are particularly rich in air voids.

The object is achieved with a method of the type mentioned above in that, according to the invention, the mixing chamber is blocked by a mechanical device in cooperation with the dry material against air leakage through the supply of dry material, and further that the mixing chamber partly with the dry material penetrated by a slight excess pressure and partly kept filled with the mix and that the dry material feed remains at least as large as the removal of the mix by the suction device.

Whilst the air content in the plaster is even reduced when using screw conveyors or similar forced conveyors, the devices according to DE-OS 21 17 nn ⁿ or 24 37 231 have not led to any tangible successes, because on the one hand the supply of water to the area of the worm drive and, on the other hand, the stirring device downstream of the feed pump could not prevent the dry material from being fed to the mixing device in an air-pore form. An air pore-enriched building material cannot therefore be obtained with this device either. According to the invention it is therefore also proposed to introduce the liquid and / or the foam material into the interior of the mixing chamber finely distributed under pressure over the entire mixing chamber. Since in the method according to the invention no forced conveyors are to be used, but the starting traction materials are supplied already enriched in air in the dry state of the mixing chamber, the finely distributed sprinkling or spraying of the dry matter provides a further possibility of increasing the pore content of the end product or at least not reducing it.

According to a particularly preferred measure, the dry material and / or mixed material is processed in a plurality of rooms in the mixing chamber which are separated by partitions and which are connected to one another via calibrated slots, gaps, bores or the like, only such an amount of dry material and / or mixed material is passed through the latter, as is removed from the suction device. The step-by-step treatment of the dry material while largely preventing its degassing leads to end products with a high pore content.

While in the known processes the mix remains in the mixing tube for about 5 to 6 seconds, the dry or mix in the mixing chamber is to be processed according to the invention for at least 10 seconds. This also increases the pore content of the end product.

Finally, the procedure according to the invention ren achieved that the mix receives a relative air pore content increase of more than 8%, preferably more than 20% by mixing.

By using the method according to the invention and increasing the air pore content, the bulk density of the end product or plaster is reduced and the thermal insulation is thus improved; the water vapor diffusibility is greatly increased; the wall surface dries out faster; any condensation water in the wall can also evaporate more easily. In the case of wet plastering mortar, the water retention capacity is improved because the air pores interrupt the pore channels; This means that drying cracks do not occur so quickly and the binders have the water required for setting longer available. The plaster is easier to work with because the air pores create a "creamier consistency"; the plaster becomes "smoother". The machinability, ie the pumpability of the end material improves, since the small pores like "ball bearings" on the wall reduce the friction; this makes it possible to either continue to convey the end product with a pump or to reduce the wear of the pump by reducing the pressure. The increased air porosity introduced improves the yield per unit weight of the end product, ie you can clean more square meters with the same amount of material. In this context, it should be noted that although the batch-wise machines mentioned above strive for an air pore content of 20-25% in the lime-cement plasters currently on the market, they are rarely achieved precisely and evenly, since the mixing times naturally fluctuate greatly at the construction site. With continuously operating plastering machines that work using mono screws, an air pore introduction, for example in the case of a lime-cement plaster, is only achieved by 7-10%, while an air pore content of approximately 25% and more can be achieved with the device according to the invention . _ y
The device proposed for performing the method according to the invention is essentially characterized in that, according to the invention, at least one storage space filled with dry goods and air cushions is provided between the storage container and the "ischkammer", which on the one hand with calibrated slots, bores or the like with the storage container and on the other hand with the mixing chamber is connected.

The slots, bores or the like can have a size which just exceeds the coarse grain of the dry material.

If the device according to the invention has the basic structure of a corresponding device according to DE-GM 70 46 623, i.e. If the mixing chamber, which is provided with an approximately vertical drive shaft and has a cylindrical feed space, is connected to an end face of the essentially horizontal storage container, the mixing chamber is expanded in the radial direction with respect to the cylindrical feed space and is essentially airtight.

With this construction of the device according to the invention, a space-saving mixing chamber is created with the possibility of connection to known similar mixing tubes, with which the air pore content of the end product can be decisively increased.

A feed line for the liquid and / or the foam material can be provided in the interior of the mixing chamber, the outlet openings of which are distributed over the entire mixing chamber. Instead of the liquid mentioned, steam, for example a gaseous medium, can also be introduced into the dry material.

According to a preferred embodiment of the device according to the invention, the feed line is ring-shaped and consists of a tube provided with bores, slots or the like. The intensive processing of the material and the ring-shaped feed line also reduce wear in the mixing chamber.

The ring-shaped feed line for the liquid and / or the foam material in the mixing chamber can be separated from the dry material feed by a stationary cylindrical deflecting wall or the like.

It is also possible that the agitator of the mixing chamber is attached to a stub shaft which is connected to the coaxial drive shaft e.g. is detachably connected via a plug-in coupling. The cylindrical feed space provided above the storage space is expediently provided with blades and / or knives attached to the drive shaft at least at its end facing the storage space; the blades and / or knives can be provided at least directly above the calibrated slots, gaps, bores or the like which lead to the storage space.

An annular slot surrounding a jacket of the drive shaft is preferably provided for the passage of the dry material into the storage space; For the passage of the dry material from the storage space into the mixing space, an annular slot or the like is expediently provided between a stationary housing wall surrounding the drive shaft at a distance and a turntable or the like which is optionally provided with blades.

The storage space just mentioned between the storage container and the mixing space is formed by the fact that e.g. only due to gravity through the small calibrated openings or slots falling dry material above the slots through the dry material conveyed from the storage container forms a barrier, so that the dry air that passes through in free fall and essentially contains air cannot vent. Air cushions or air bubbles under low pressure are formed in the storage space, which cannot escape upwards and are therefore entrained by the other dry goods falling at the edge of the turntable and fed to the mixing room.

The agitator provided in the mixing chamber can have blades or the like which are arranged across one another the mixing chamber extending turntable or the like are attached, which is separated from the wall of the mixing chamber parallel to the axis of rotation by an annular slot. At the edge of the turntable carrying the agitator or the like, pins, plates or the like are preferably mounted parallel to the wall of the mixing chamber. By means of these pins, plates or the like, the pasty wet mix is conveyed to the ring slot just mentioned and transported along the mixing chamber wall in the direction of the suction opening. Furthermore, it is possible that the turntable or the like carrying the agitator is provided with small bores, holes or the like for sucking out air at a distance of approximately one third of the blade length from the wall of the mixing chamber housing.

On the lower side of the turntable carrying the agitator, plates, mandrels, knives or the like can be provided parallel to the axis of rotation. The bottom wall adjoining the mixing chamber wall can also be designed in the shape of a truncated cone and the central section of the bottom wall can run perpendicular to the axis of rotation; the section of the base wall running perpendicular to the axis of rotation can carry a ring or the like designed as a chicane for the mixed material, the upper edge of which protrudes beyond the lower edge of the plates, mandrels, knives or the like. The chicane just mentioned brings about a further mixing effect with the plates, thorns, knives or the like; due to the swirling or swirling effect achieved at the outlet due to the suction device, the air sucked in via the small bores or holes is also incorporated into the mixture, so that the air pore content is also increased at this point.

The stub shaft supporting the agitator can be provided at its lower end with an adapter for a coupling of the suction device and between the coupling and the straight section of the bottom wall there can be an annular slot or the like for suctioning off the mixed material be provided.

It is also possible that the upper wall of the mixing chamber is fastened to the housing wall surrounding the cylindrical feed space and either has a hinge or the like for folding down the mixing chamber, or the mixing chamber is detachably attached to the upper wall.

Finally, the blades attached to the turntable or the like can be attached with their inner edges to a cylinder which surrounds the stub shaft at a distance and which carries the turntable or the like closing off the storage space.

• Fig. 1 einen Längsschnitt durch die Ausführungsform,
• Fig. 2 ein Detail dieser Ausführungsform und
• Fig. 3 eine Ansicht gemäß Linie 3-3 in Fig. 2.

In the drawing, an example embodiment of the device according to the invention is shown; it shows:

• 1 shows a longitudinal section through the embodiment,
• Fig. 2 shows a detail of this embodiment and
• 3 is a view along line 3-3 in FIG. 2nd

A shaft 1 of an electric motor-driven agitator is provided with a jacket 2 and accommodated in the center of a cylindrical housing 3. The cylindrical housing 3 extends to the electric motor, not shown, and has a lateral opening 4. The lateral opening 4 is provided with a throttle valve 6 which can be rotated in the direction of the arrow 5 and leads to a storage container 7, the worm drive of which is not shown in detail; the storage container 7 can be provided with a lid 8.

Through the opening 4, dry material is conveyed into the housing 3.

Knife-shaped wings 9 are attached to the casing 2 of the shaft 1 and cover the space in the housing 3 at the upper edge 10 of breakthrough 4 "complete". The space 11, which is almost completely filled with the dry material, is connected on its lower side by a wall 12, which can also be interchangeable if necessary. The wings or blades 13 cause a "stowage" of the dry material in the direction of the lower end of the shaft 1. Around the jacket 2 is at the level of. Wall 12, an annular gap or _R provided ingschlitz 14 is performed by which the dosage of the dry material in the mixing device. Immediately or half of the annular gap 2 blades 15 are attached to the jacket, which can also be set so that they constantly cause a supply of dry material downwards. Knife-like blades 16 can be provided above the blades 15, which can also be attached in an inclined position, such as the blades 13 on the casing 2, and stow the dry material in the direction of the mixing device. As can be seen in FIG. 2, the jacket 2 closes off at the level of the lower edge 17 of the wall 12 and can be connected to a stub shaft 20 in a rotationally fixed manner, for example by means of a plug connection 19.

The cylindrical housing wall 3 has a radially extending upper wall 22 above its lower edge 21, which e.g. welded to the wall 3 or otherwise firmly connected.

Beneath the wall 12 there is a storage space 23, the lower end of which is formed by a disk or a plate 24, on which wings 25 are fastened, which can be set so that they press the dry material towards the wings 15. The disc 24 releases an annular gap 26 which is provided between the housing wall 3 and the disc just mentioned.

Due to the fact that the dry matter in the space 11 is deposited to such an extent that the space above the wall 12 or also above the blades 15 and the knife-like wings 16 is completely filled with dry matter, only a desired metered amount is obtained through the annular slot 14 of dry goods due to a Rotation of the agitator shaft 1 promoted.

Since the ring slot 26 has a larger diameter than the ring slot 14, the dry material can fall through the ring slot 26 faster and better than through the ring slot 14. However, on the other hand, the blades 25 can also be set so that the dry material into the Storage space 23 is pressed, air cushions or air bubbles arise above the dry goods in space 23, which are under a slight excess pressure; These air bubbles or air cushions ensure, due to the drainage of the dry material in the direction of the mixing chamber 30, that particularly strong aeration of the dry material can be carried out in the mixing chamber. The disc 24 is fastened on a cylindrical tube piece 31, on the lower edge 32 of which a further disc 33 is fastened. On the disc 33, as can be seen from Fig. 5, 'five blades 34 are attached, with which the mixture of the dropping dry material with a liquid, e.g. Water 28 is made. The liquid is supplied via a pipe ring 29, to which the liquid is supplied under pressure via an inlet connection 30. In order to prevent the liquid from entering the dry material in the vicinity of the annular gap 26, a shielding ring 35 is provided in the mixing chamber, which is welded to the tubular ring 29. In this way it is achieved that the dry material falls into the mixing space provided with blades 34 while still dry. The blades 34 can be set to cause the material to be conveyed radially outwards and at the same time upwards.

As can be seen from FIG. 3, wipers 36 are attached to the end of two blades 34, which expose the annular gap 37 to the cylindrical outer wall 38 of the mixing device. These wipers can also have the shape shown in FIG. 3, that is to say they can be bent so that they again turn the mixture - in this case it is already completely wetted - in the direction of press the paddles 34.

When the agitators 1 and thus the casing 2 and the stub shaft 20 are rotated, the agitator blades 34, like the blades 25, are set in rotation. The tubular shield 35 is stationary and prevents the soaked mixture from being pressed up. The mix pressed down laterally in the ring slot 37 runs on a conical wall 40 in the direction of the agitator shaft 1 or the shaft stub 20. The section 41 of the wall 40 which runs at right angles to the agitator shaft axis is provided with an annular slot 42 through which the ready-mixed material is fed into a Suction device 43 or is sucked off by this with a pipeline provided with a feed pump.

At the transition point between the straight section 41 and the conical section 40 of the bottom wall, a cylindrical shielding wall 45 is provided; at a distance from this cylindrical wall, mandrels, plates 46 or the like rotate during operation of the agitator, so that a further mixing effect is achieved even in this area.

3, bores 50 are provided in the disk 33, through which air present in the agitator area can be sucked off in the direction of the suction device 43. Since in the area of the ring slot 42 due to the rotation of the agitator and the movement with the feed pump or from the mixing device, whirls or swirls arise, the air sucked out through the bores 50 is brought into the mixture, so that its pore content is increased still further becomes.

The residence time of the dry material passing through the slot 14 in the mixing device until it leaves the mixed material through the annular slot 42 is e.g. in about 20 to 30 seconds, which not only significantly increases the mixing effect, but also the pore content, which e.g. can be increased to 25%:

Due to the fact that the stirring blades 34 Conveying mixed material primarily through its setting upwards and that the mixed material can only flow out "in a mushy state" via the annular channel 37, not only in the mixing space but also above the annular gap 26, especially in the storage space 23 stagnations of the dry material. Accordingly, in the storage space 23 there are, in addition to the dry goods, also air bubbles or air cushions which, as already noted, are under a low air pressure of a few tenths of a bar. This air is then fed to the dry material in the mixing room and mixed into the mixed material.

Increasing the air pore content in fine-grained or fine types of plaster, such as lime-cement plaster, which can be machine-applied in one layer in the interior or exterior, has also proven particularly useful.

While the top wall 22 is attached to the housing 3. a hinge 51 is provided to secure the mixing device, e.g. to be able to fold down for cleaning purposes.

With the mixing method according to the invention or with the mixing device according to the invention, the air pore content can be increased in all ready-to-dry mortars whose air pore content can also be increased with batch mixers with a correspondingly long residence time. Compared to the use of mixing tubes, i.e. continuous mixing devices, decisive improvements can be achieved. For example, in the case of lime-gypsum plaster with an ordinary mixing pipe, an air pore content of only 7-10% compared to 15-20% can be achieved with the device according to the invention; the corresponding values for a lime-cement plaster are 7 - 12% compared to 20 - 25%. In the case of a known thermal insulation plaster, the values are 25-30% compared to 45-50%.

The frost resistance of the plaster is also improved by the increased air pore content. The longer mixing time also means that all of the dry mortar additives have a longer dissolving time and are therefore more effective.

Claims (26)

1. A method for continuously mixing a coarse-grained to powdery dry mortar with a liquid and / or a foam material in a mixing chamber, which is connected upstream of a storage container for the dry material and a suction device for the mixed material, characterized in that the mixing chamber by a mechanical device in cooperation with the dry material against air leakage through the dry material supply is blocked, that further the mixing chamber part is kept filled with the dry material penetrated by air cushions under slight overpressure and partly filled with the mixed material, and that the dry material supply remains at least as large as the removal of the mixed material by the suction device. 2. The method according to claim 1, characterized in that the liquid and / or the foam material is introduced into the interior of the mixing chamber over the entire mixing chamber finely distributed under pressure. 3. The method according to claim 1 or 2, characterized in that the dry material and / or mixed material is processed in several rooms divided by partitions in the mixing chamber, each of which is connected to one another via calibrated slots, columns, bores or the like, only one such an amount of dry material and / or mixed material is passed through the latter, as is removed by the suction device. 4. The method according to claim 1 or the following, characterized in that the dry or mixed material is processed in the mixing chamber at least 10 sec. 5. The method according to claim 1 or the following, characterized in that the material to be mixed receives a relative air pore content increase of more than 8%, preferably more than 20%. 6. Device for performing the method according to claim 1 or following, characterized in that between the storage container and the mixing chamber at least one filled with dry goods and air cushions Storage space is provided, which is connected via calibrated slots, bores or the like on the one hand to the storage container and on the other hand to the mixing chamber. 7. The device according to claim 6, characterized in that the slots, bores or the like have a size just exceeding the coarse grain of the dry material. 8.The device according to claim 6 or 7, wherein the mixing chamber provided with an approximately vertical drive shaft and having a cylindrical feed space is connected to an end face of the substantially horizontal storage container, characterized in that the mixing chamber extends in the radial direction with respect to the cylindrical feed space and is essentially airtight. 9. Apparatus according to claim 6 or following, characterized in that a feed line for the liquid and / or the foam material is provided in the interior of the mixing chamber, the outlet openings of which are distributed over the entire mixing chamber. 10. The device according to claim 9, characterized in that the feed line is annular and consists of a tube provided with holes, slots or the like. 11. The device according to claim 9 or lo, characterized in that the annular feed line for the liquid and / or the foam material in the mixing chamber is separated from the dry material supply by a stationary cylindrical baffle or the like. 12. The apparatus according to claim 6 or following, characterized in that the agitator of the mixing chamber is attached to a stub shaft which is connected to the coaxial drive shaft e.g. is detachably connected via a plug-in coupling. 13. The apparatus of claim 6 or following with a dry material supply essentially by gravity, characterized in that the above the Storage space provided cylindrical feed space is provided at least at its end facing the storage space with blades and / or knives attached to the drive shaft. 14. The apparatus according to claim 6 or following, characterized in that the blades and / or knives are provided at least immediately above the calibrated slots, columns, bores or the like, which lead to the storage space. 15. The apparatus according to claim 6 or the following, characterized in that a ring slot surrounding a jacket of the drive shaft is provided for the passage of the dry material into the storage space. 16. The apparatus according to claim 6 or the following, characterized in that an annular slot or the like is provided for the passage of the dry material from the storage space into the mixing space between a stationary housing wall surrounding the drive shaft at a distance and an optionally provided with a turntable or the like. 17. The apparatus according to claim 6 or the following, characterized in that the stirrer provided in the mixing chamber has blades or the like which are attached to a turntable or the like extending transversely across the mixing chamber and which is separated from the wall of the mixing chamber parallel to the axis of rotation by an annular slot . 18. The apparatus according to claim 17, characterized in that at the edge of the turntable carrying the agitator or the like, pins, plates or the like are arranged running parallel to the wall of the mixing chamber. 19. The apparatus according to claim 17 or 18, characterized in that the turntable carrying the agitator or the like is provided with small bores, holes or the like for extracting air approximately at a distance of a third of the blade length from the wall of the mixing chamber housing. _20th Apparatus according to claim 17 or the following, characterized in that plates, mandrels, knives or the like are provided on the underside of the turntable carrying the agitator parallel to the axis of rotation. 21. The apparatus according to claim 6 or the following, characterized in that the bottom wall adjoining the mixing chamber wall is frustoconical and the central section of the bottom wall is perpendicular to the axis of rotation. 22. The apparatus according to claim 6 or the following, characterized in that the section of the bottom wall running perpendicular to the axis of rotation carries a ring or the like designed as a chicane for the mixed material, the upper edge of which projects beyond the lower edge of the plates, mandrels, knives or the like. 23. The device according to claim 6 or following, characterized in that the stub shaft supporting the agitator is provided at its lower end with an adapter for a coupling of the suction device and that between the coupling and the rectilinear portion of the bottom wall an annular slot or the like for suctioning the Mixed material is provided. 24. The device according to claim 6 or the following, characterized in that the upper wall of the mixing chamber is fixed to the housing wall surrounding the cylindrical feed space and has a hinge or the like for folding down the mixing chamber. 25. Device according to one of claims 6 to 23, characterized in that the upper wall of the mixing chamber is attached to the housing wall surrounding the cylindrical feed space and the mixing chamber is detachably attached to the upper wall. 26. The apparatus of claim 6 or the following, characterized in that the blades attached to the turntable or the like are attached with their inner edges to a cylinder surrounding the stub shaft at a distance, which is the turntable closing the storage space or the like. wearing.

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