EP0188674B1 - Transportable mixer, preferably having a reversed-running emptying facility for building materials, especially concrete - Google Patents

Abstract

In a mobile mixer, preferably having counterrotational emptying, for building materials, in particular concrete, in a mixing drum (1) which, on its inner wall (9), has one or more flat elevators (11, 12) following a helix and extending from the closed drum base (2) to the drum opening (3), which elevators (11, 12) are driven about the drum axis during rotation of the mixing drum and push the building material to the front of the closed base (2) during transport and during mixing, with one or more flat sections (26, 27) which are helically curved about the mixing drum axis (4) being fixed for driving during the mixing drum rotation (5) in the mixing drum space enclosed by the elevators acting as mixing spirals (11, 12), which flat sections (26, 27) are arranged counterrotationally to the mixing spirals (11, 12) in such a way that, during the transport and during the mixing of the buiding material (13), they produce a counterflow in the building material filling core surrounded by the mixing spirals (11, 12). It is provided according to the invention that the flat sections (26, 27) start at the mixing drum base (2) and end in front of the mixing spirals (11, 12) and the mixing drum opening (3), and that the flat sections (26, 27) of the counterflow spirals (26, 27) are fixed to the elevators of the mixing spirals (11, 12) and via the mixing drum base (2) to the mixing drum wall (9).

Description

3. The invention relates to a truck mixer, preferably with opposite emptying for building materials, in particular concrete.

The truck mixer according to the invention transports a batch of building material in the mixing drum and mixes it on the transport by the rotation of the mixing drum. In addition to concrete, the building material can also consist of mortar, whereby in addition to masonry mortar and plastering mortar, lime, cement and fireclay mortar can also be considered. Generally speaking, these building materials consist of a special dry mix, which in addition to the aggregates or sand and the additives usually contains hydraulic, but occasionally also non-hydraulic cements, and water. As soon as the water comes into contact with the cement, a chemical process begins in most types of cement, the faster the higher the ambient temperature, the faster the ambient temperature one must take into account the heat of hydration released as an additional heat source. The truck mixer according to the invention enables the addition of the mixing water at a time which is more or less shortly before the use of the building material at the construction site during the journey or at the place of use of the building material, because of the deliberately mixing effect which circulates the building material batch, so that the truck mixer is transporting the dry mixture and can mix them with the mixing water.

The design of the mixing drum, in which the truck mixer according to the invention transports the building material, ensures, because of the firmly arranged, spiral-shaped elevations on the inner wall of the mixing drum, a simple structure of this device which, depending on the direction of rotation of the mixing tower, pulls the building material around its central axis or through it closed mixing drum bottom opposite mixing drum opening to the outside.

The invention relates, inter alia, to mixing drums which are constructed so inclined on mostly road-going vehicles designed as trucks or as truck trailers that their opening through which the building material is given or given is above and its closed bottom is below. According to the invention, if the building material has to be transported through narrow cross sections, such as occur, for example, in tunnel construction, the mixing drum also installed with a horizontal arrangement, for example on a rail chassis of the mixing drum axis. In this case, the jacket of the mixing drum between the mixing drum base closed with a removable cover and the mixing drum opening can have a number of side-by-side manholes depending on the length and the mixing drum diameter, through which the batch of building material is filled, which emerges through the base with the lid open; With these truck mixers, the opening of the mixing drum is often used to pick up the building material from an upstream mixing drum and to pass it through a downstream mixing drum.

In known truck mixers of the type described, a helical elevation mostly consisting of flat steel is provided above the drum base. It exerts a driving effect on the building material, which leads to strong compaction in the core of the building material batch surrounded by the elevations, which core has been filled into the mixing drum for transport.

The mixing effect is prevented, particularly in the case of earth-moist concrete, which leads to considerable deterioration of the building material.

It is also known for this reason (DE-A-29 49 026) to mount a tube rotating with it in the middle of the drum, in which a spiral is fastened with rotation opposite to the outer mixing spiral. The pipe ends above the drum base and under the drum opening. However, the intended creation of a countercurrent in the core of the drum filling, which dissolves the building material accumulation on the drum bottom and is intended to start the mixing action again, does not occur. Rather, the tube prevents the mix carried upward in the course of a drum rotation from the outer spiral in free fall from falling far enough down. For this reason, the intended free-fall mixture does not come about or only insufficiently. In addition, the narrow passage cross section of the tube limits the amount of mix to such an extent that such mixers are practically uninteresting.

If one then goes on to add a majority or all of the mixing water to the building material mixture before filling the batch to be transported in order to improve the miscibility in relation to the dry mixture, no significant improvement is achieved. The transport of such a largely finished building material has the further disadvantage that it threatens to freeze at low ambient temperatures and, at high ambient temperatures, will prematurely harden during transport and if there are any waiting times at the construction site, unless appropriate countermeasures are taken to avoid this mitigate or avoid any deterioration of the building material.

Since, due to the described effects of the spiral elevations and the short counter-rotating spiral pieces in the space between the elevations, the movements of the building material batch in the mixing drum are inadequate, despite the rotating mixer drum, the above-mentioned deterioration of building materials occurs even with favorable outside temperatures during longer transport and waiting times. In many types of truck mixers, especially in the truck mixer types described above, which are intended for tunnel construction, the turning of the mixing drum already makes considerable difficulties. Compressed air drives are used for safety reasons, for example in truck mixers for tunnel construction.

It is also known in truck mixers with the inclined inclined arrangement of the mixing drum, such as are provided in most road transport vehicles, to provide a forced mixing device to avoid the above-mentioned difficulties, which has a drive that is separate from the mixing drum drive and is installed outside in front of the mixing drum base is provided. The compulsory mixing device itself consists of a short shaft arranged in the mixing drum axis, on which several mixing blades are attached. These act below the filling line of the mixing drum, which runs from the lower edge of the outlet opening at an incline of approximately 25 degrees to the upper inner wall for reasons of economy in order to utilize the capacity of the mixing drum, on the lower part of the batch, which fills the mixing drum tightly above the bottom of the mixing drum. These mixing blades are intended to generate a radial and axial flow of the building material in the compacted building material core described. Such a device actually improves the mixing effect and thereby also enables the dry transport of building materials and the addition of the mixing water outside the mixing systems from which the building material is fed to the truck mixers.

On the other hand, truck mixers designed in this way have proven to be extraordinarily complex constructions, either because of that to certain ones Truck mixers, such as the truck mixers described, cannot be used for tunnel construction at all or, because of their complicated structure, create numerous sources of interference and are accordingly difficult to maintain. In addition, the mixing effect is also unsatisfactory. Because the building material, especially if it is realized with concrete, contains coarse aggregates to a greater or lesser extent, the tools of the compulsory mixer must be protected from being damaged by jammed components of the building material mixture. This can only be achieved if a correspondingly large space is maintained between the compulsory mixing device and the elevations of the drum shell, in which the coarse components can escape, but in which, on the other hand, no compulsory mixing effect is achieved.

The invention is based on the object, for a truck mixer of the type known from the document mentioned in a simple manner a general, i.e. to create a structure applicable to the different types of truck mixer described, which ensures complete mixing and movement of the batch of building material through the mixing drum, even in the case of earth-moist concrete, and thereby ensures sufficient mixing.

The invention solves this problem with the characterizing feature of claim 1. Appropriate embodiments of the invention are the subject of the dependent claims.

In the invention, when the mixing drum is rotated for transport, a stream of the building material mixture directed towards the closed mixing drum base is actually generated in an outer jacket area of the building material batch, which stream reverses inward over the mixing drum base and in the core of the building material mixture enclosed by the elevations of the mixing drum jacket Direction towards the mixing drum opening. This counter-current movement of the part of the building material batch described by the mixing drum receives its energy from the flat profiles of the concentrically inner counter-current spirals due to their opposite slope to the mixing spirals which are attached to the drum shell. However, since these flat profiles do not reach the ends of the mixing spirals forming the elevations of the mixing drum shell, but rather end in front of them and the mixing drum opening, the countercurrent transport effect ceases in good time, so that the building material cannot escape through the mixing drum opening, but instead is picked up again by the elevations of the mixing drum shell and is diverted in the direction of transport. In the case of the invention, the known free-fall mixture is superimposed on this effect because the attachment of the inner countercurrent spiral offers no or only negligible resistance, which also advantageously depends on the amount required in the countercurrent. The overall structure of the new truck mixer is also no longer complicated, but on the other hand also offers the possibility of using this truck mixer structure on flat-lying mixing drums, as is the case with the truck mixers described for tunnel construction must be used. The countercurrent spiral produces not only an axial, but also a radial movement component, because this movement is practically not hindered by the built-in parts. These are nevertheless sufficient to fix the countercurrent spiral in the mixing drum so that it is carried along by it against the resistance of the building material mass and is not deformed in the process.

In the case of simultaneous emptying through the mixing drum bottom opening or counterflow emptying through the constantly free mixing drum opening opposite the mixing drum bottom, a complete emptying of the mixing drum is ensured despite the reversal of the flow direction in the core of the building material batch as a result of the countercurrent mixing spirals, because the countercurrent spirals also generate and move the building material mixture radially therefore in this direction of rotation convey the building material mixture to the outside into the mixing spirals, which then transport it along the mixing drum wall through the mixing drum opening to the outside.

The design of their mixer drum ensures that the truck mixers according to the invention have a mixing effect which was previously only achievable with stationary mixing machines, although one does not need to realize their large dimensions in relation to the contents, nor additional drives, as are the rule with compulsory mixers. For this reason, the filling quantity of the truck mixers according to the invention essentially corresponds to the filling quantity of conventional truck mixers of the same dimensions. Nevertheless, according to the invention it is prevented that the building material mass in the area of the mixing drum casing only moves around the axis of the mixing drum when the mixing drum is running. The invention has the advantage, even when the mixing drum is full, that the truck mixer can be used as a mixing machine; That is why truck mixers according to the invention eliminate the adverse effects of extreme outside temperatures on the quality of the building material in that only the dry mixture of the building material can be transported, which is then mixed and mixed with the mixing water shortly before use.

The conveying capacity of the counterflow spirals is preferably set up in such a way that an axial speed results in the core of the building material mass, which corresponds approximately to the speed which the mixing spirals in the jacket of the building material mass produce in the opposite direction.

It is known from US Pat. No. 1,866,688 a truck mixer with counterflow emptying for building materials, in which the flat profiles start from the mixing drum base and end in front of the mixing spirals and the mixing drum opening and the flat profiles of the counterflow spirals at the elevations of the mixing spirals and above the mixing drum base at Mixing drum wall are attached. In such a truck mixer, however, there is often the problem that, on the one hand, the vehicle is used to transport dry mixtures of the building material, which are only mixed and mixed with the mixing water before use, that on the one hand the mixing water is not or not quickly enough with the other components mixed, but also the resistance is too great, which the stationary parts oppose the intended movement of the building material. Therefore, according to the invention, nozzles for dispensing mixing water are arranged inside the mixing drum, which are connected via pipes to one another and to a pump arranged outside the drum, the nozzles being directed so that their openings lie in the mixed flow shadow during the mixing process of the drum. This ensures good mixing of the building material batch on the one hand and, on the other hand, a uniform distribution and mixing of the building material batch with the mixing water.

In a preferred embodiment of the invention it is provided that the pipelines follow the course of the flat profiles and each end in a straight pipe section running in a plane perpendicular to the longitudinal axis of the drum, one of the pipe sections being connected to a supply line connected via a Rotary lead-through in one of the drum ends leads to the pump.

To protect the nozzles from the abrasive building material and as a further additional measure to prevent the nozzles from becoming blocked, they are covered with hollow-shaped caps made of elastic or elastomeric material, in which slit-shaped openings are provided, and which are wear-resistant due to their material.

A modified embodiment of the invention provides that nozzles for the mixing water are provided on the end faces of the mixing spirals facing the center of the drum. The countercurrent spirals have been dispensed with in this embodiment.

Although the combination of mixing spirals, counter-current spirals and water discharge nozzles inside the drum, preferably on the counter-current spirals, results in optimal mixing, since the counter-current spirals ensure true free-fall mixing and the product is not pressed against the bottom of the drum alone, but this solution already offers significant progress. Due to the evenly distributed nozzles on the mixing spirals and the thus enabled defined and concentrated application of the mixing water inside the drum, a loosening of the filling material pressed by the mixing spirals to the bottom is achieved, so that a good mixing of the filling material and the filling material with the mixing water is still achieved is achieved.

A further modification of the invention provides that the rotating union has several channels, each channel being supplied with mixing water by a pump and behind the rotating union the channels are connected via individual lines to certain discharge nozzles. Depending on the shape, size and construction of the mixing drum, this makes it possible to add water in a targeted or forced manner.

The truck mixer can be designed so that the mixing drum is shifted obliquely rising with the bottom and opening above on the chassis of a transport vehicle, but it is also provided that the mixing drum is moved horizontally on the chassis of a vehicle and the mixing drum bottom and the Mixing drum opening can be closed with lids.

Truck mixers of this type are used in particular when concreting tunnels. For this purpose, the truck mixers are coupled either long or short.

The long coupling creates a distance between the end faces of the mixing drums mounted on the vehicles, which ensures that the train can negotiate curves. In the short coupling, the feed and discharge openings, which are aligned with one another in the longitudinal direction of the train, mesh with one another, so that the concrete can be discharged from one mixing drum into the other on site if the mixing drums rotate in the appropriate direction. In this way, the train is emptied in a continuous manner by the elevations arranged on the inside of the drum driving the building material through the discharge openings. The building material is filled in outside the tunnel. For this purpose, a further feature of the invention provides that the filling opening is arranged in the end wall of the drum opposite the discharge-side drum end wall, to which a filling funnel can be fastened which extends into the filling opening with a chute. So far, the building material has been filled into the drum by the premixed building material has been introduced into the mixing drum via a plurality of manhole openings arranged one behind the other on the mixing drum. However, this results in considerable disadvantages, which relate to an unfavorable degree of filling of the drum and an unfavorable quality of the building material. The unfavorable degree of filling results from the fact that approximately conical heaps form under the manhole openings. When the piles reach the manhole openings, they first have to be closed, then the mixing drum has to be rotated so that there is a uniform, low filling level. The mixer vehicle must be maneuvered under the mixing system so that every manhole opening can be used to fill the building material. All of this results in a considerable amount of time and poor building material quality when filling the mixing drum.

In order to shorten the filling process even further, which is particularly important for the quality of the building material, a further feature of the invention provides that the filling funnel with cone-shaped lugs arranged on it can be locked in two or more cone-shaped sleeves, which are on the chassis of the vehicle are arranged. For example, the hopper only needs to be inserted into the sleeve and can be easily removed after the filling process. Lengthy assembly is not necessary. Nevertheless, the hopper is safely moved.

Fig. 1

in Seitenansicht eine Mischtrommel gemäß der Erfindung, wie sie in dem straßengängigen Fahrmischer Verwendung findet, wobei die Mischtrommel selbst zur Verdeutlichung der Verhältnisse während des Mischens durchsichtig gezeichnet ist,

Fig. 2

einen straßengängigen Fahrmischer, auf dem eine Mischtrommel nach Fig. 1 aufgebaut ist in Seitenansicht und

Fig. 3

einen schienengängigen Fahrmischer gemäß der Erfindung, wie er u.a. im Tunnelbau verwendet wird,

Fig. 4

eine Mischtrommel gemäß Fig. 1 mit einer Vorrichtung zur Einbringung von Anmachwasser (Drehdurchführung im Trommelboden),

Fig. 5

Mischtrommel gemäß Fig. 4 mit Wasserzuführung durch die Trommelöffnung,

Fig. 6

einen schienengängigen Fahrmischer gemäß Fig. 3 mit seitlicher Einfüllöffnung,

Fig. 7

einen straßengängigen Fahrmischer mit durchsichtig gezeichneter Trommel gem. Fig. 4 (ohne Gegenstromspiralen).

The details, further features and other advantages of the invention result from the following description of embodiments according to the invention, which are shown in the figures of the drawing. Show it

Fig. 1

a side view of a mixing drum according to the invention, as is used in road-going truck mixers, the mixing drum itself being drawn transparently to illustrate the conditions during mixing,

Fig. 2

a road mixer, on which a mixing drum according to FIG. 1 is built in side view and

Fig. 3

a rail-type truck mixer according to the invention, such as is used in tunnel construction,

Fig. 4

1 with a device for introducing mixing water (rotary feedthrough in the drum base),

Fig. 5

4 with water supply through the drum opening,

Fig. 6

3 with a side filler opening,

Fig. 7

a road-going mixer truck with a transparent drum acc. Fig. 4 (without counterflow spirals).

In the illustration in FIG. 1, 1 denotes a pear-shaped mixing drum, which has a closed bottom and an opening 3 opposite the bottom 2, which has no cover and is therefore kept open at all times. The axis of symmetry 4 of the mixing drum shows that it is installed at an incline, the direction of rotation of the mixing drum being indicated by arrow 5.

The shape of the mixing drum sees you lower conical section 6, a subsequent cylindrical section 7 and a conical neck 8, which leads to the opening 3. On the inside 9 of the drum casing, generally designated 10, two mixing spirals 11 and 12 are attached. The attachment of the mixing spirals is designed so that the mixing spirals are taken along when the drum rotates in the direction of arrow 5 against the resistance of a building material mass 13. The two mixing spirals 11, 12, which are offset by a semicircle, have the same pitch and, generally speaking, represent elevations on the drum shell 9, which protrude into the interior 14 of the drum. If such a mixing drum is constructed on a truck chassis 14 'as shown in FIG. 2, it generally has a capacity of between 2.5 and 10 m 3. It can be rotated in two directions by means of a hydraulic drive motor 15, which is fed by a built-in pressure generator 16, via a gear 17. The gear 17 acts on the drum base 2 via a flange 18. The rest of the mixing drum rests with a race 19 fastened on the outside of its casing in the region of the neck 8 in a bearing 20 which is arranged so as to be fixed to the structure. In front of the mixing drum opening there is a filling funnel 21 through which a building material mixture can be filled into the drum 1. When the mixing drum 1 is driven counter to the direction of the arrow 5 in FIG. 1, the building material is discharged and reaches the prefill container 23 via a chute 22, for example.

The two mixing spirals 11, 12 fastened on the inside 9 of the drum casing 10 are designed as solid wall spirals. If the building material mixture is poured into the drum via the filling funnel 21, it must be rotated in the direction of arrow 5 so that the mixing spirals 11, 12 can move the building material mixture into the interior 14 of the drum. In the embodiment according to FIG. 1, this process is favored by the inclined mounting of the mixing drum. For reasons of economy, the volume of the drum is always fully utilized. The filling line 24 of the drum then runs from the lower edge 25 of the outlet opening at an incline of approximately 25 degrees to the upper inside of the mixing drum. Behind or below this filling line 24 is the drum bin to the head end, i.e. bulging in the direction of the drum testicles 2. Depending on the duration of the transport or the distance traveled, it is necessary to keep the contents of the mixing drum in motion so that the setting process does not start, provided the building material has been filled in with the mixing water. For this purpose, the motor 15 rotates the mixing drum in the direction of the arrow while the vehicle 14 'is traveling at low speed.

In the mixing drum space enclosed by the mixing spirals 11, 12, two flat profiles which are curved according to helical lines about the mixing drum axis 4 are fastened for entrainment when the mixing drum rotates, as shown in FIGS. 1 to 5. These flat profiles start from the mixing drum base 2 and end in front of the mixing spirals 11, 12 and the mixing drum opening 3. They are designed in the opposite direction to the mixing spirals 11, 12 and are arranged offset by a semicircle such that they act as counter-current spirals 26, 27. This means that when the building material is mixed when the mixing drum rotates in the direction of arrow 5 in the core 28 of the building material filling 13 surrounded by the mixing spirals 11, 12, a countercurrent originating from the drum base is generated, which is schematically indicated by the inner arrow pairs 29, 30 in Fig. 1 is indicated. The countercurrent is directed towards the mixing drum opening 3, but ends below the ends of the mixing spirals 11, 12 shown at 31 and 32. This is due to the fact that the two countercurrent spirals 26, 27 are approximately at the filling line 25 mentioned and thus below the ends 31, 32 are over, as a result of which the ends 31, 32 can reverse the direction of the flow of the building material and the jacket of the building material filling is able to follow the arrows 33, 34 which run along the drum wall in the direction of the floor. As soon as the building material particles following this external stream have reached the bottom 2, their direction reverses again according to the arrows 35, 36.

These opposing flows in the mixing drum prevent a compact building material mass from forming, particularly in the lower part of the mixing drum, which is formed by the cone 6. Rather, the counterflow spirals 26, 27 cause an intensive circulation of the building material mass and thus immediately a better distribution of the binder contained in the building material mixture, the fine sand and the different grain sizes of the additives. This also happens when the building material is dry. When water is added, even watering is accelerated and intensified.

In the aforementioned reversal of the direction of rotation of the mixing drum 1, the solid wall spirals 11, 12 take the building material mixture against the direction of the arrows 33, 34 and convey it through the opening 3 to the outside. With increasing emptying of the mixing drum, the material to be mixed slides off the counter-current spirals 26, 27 until the building material core is dissolved, the mass of which is also grasped by the solid-walled spirals 11, 12 and transported to the outlet opening 3.

1 also shows that the countercurrent spirals 26, 27 have the same slope as the mixing spirals 11, 12. Furthermore, the width of the flat profiles forming the counterflow spirals 26, 27 is less than the width of the elevations on the mixing drum wall 9 formed by the mixing spirals 11, 12.

The flat profiles of the counterflow spirals 26, 27 are fastened to the spirals 11, 12 at several points with the aid of rod-like supports 40, 41. In addition, the lower region of the drum, the counterflow spirals 26, 27 are attached directly to the bottom 2 of the drum or to the adjoining drum wall.

3 is intended for tunnel construction. On rail-type bogies 42, 43, the chassis 44 of a low-build wagon runs, which have on its front and rear couplings 45 and 46 for subsequent or advancing transport wagons, which correspond in design and dimensions to the truck mixer 47, which in Fig. 3 is shown.

The truck mixer is essentially constructed from a mixing drum 48, which has a cylindrical jacket 49 over the greater part of its length and is supported with races in stationary bearings 50 and 51. The bottom 5, the mixing drum is provided with a cover 53. The opening 54 of the mixing drum opposite the bottom is in turn closed by a cover 55. A conical section 56 "of the mixing drum forms an elongated transition from the cylindrical part 49 to the opening 54.

Such mixing drums are usually about 3 to 7 m long. They can be driven with a motor, which is indicated at 56 ', but in many cases must be designed as a compressed air drive because of the special tunnel conditions.

The building material is introduced into the drum 47 under a mixing station in front of the tunnel through manhole openings shown at 56 to 58. in the generally, such drums have one to three manholes, depending on their length, which are placed one after the other under a downpipe, in order to subsequently close the manhole with a lid. Furthermore, truck mixers 47 of the type shown in FIG. 3 are usually coupled in pairs and form a train which transports a larger amount of building material via tracks to the installation site in the tunnel. Depending on the length of the route, the building material must be circulated for the purpose of keeping it fresh. Unless a separate power source is carried on the train, the train must stop on the way to start the compressed air motors for the drum rotation at an infeed point.

In turn, the two mixing spirals 11, 12 are formed in the drum 47, which are attached to the inside 9 of the mixing drum 47. They extend from the drum base 2 to the opening 54. In addition, the two counterflow spirals 26, 27 are provided, which in turn end below the ends 31, 32 of the mixing spirals 11, 12 and thus also break off in front of the opening 54.

During the transport of the building material filled through the three manholes 56 to 58, the mixing spirals 11, 12 push the building material inside the drum against the end of the drum identified by the bottom 2, which is closed with the cover 53 as well as the drum opening 54 through the cover 55. The build-up of the building material on the floor 52 is caused by the action of the counter-current spirals 26, 27 prevented, which is described in connection with the embodiment of Figures 1 and 2.

What is new is the mixing effect that occurs in the described embodiment of the truck mixer 27, which corresponds to that of a free-fall mixer. If the counter-current spirals 26, 27 convey the building material in the opposite direction, they lead to a brightening and recycling of the building material in the core, which is enclosed by the mixing spirals 11, 12. This creates free spaces that allow the building material to mix in free fall.

4 and 5 the same parts as in Figures 1 to 3 are provided with the same reference numerals. The countercurrent spirals 26, 27 are provided on their contour facing the drum wall with tubes 101, 102 which follow the course of the countercurrent spirals 26, 27. In the bottom 2 of the drum 1, a rotating union 103 is provided, through which a pipe 104 leads from a pump 105 to two pipe sections 106 and 107 radially emerging from the rotating union. The pipe sections 106 and 107 open into the pipes 101 and 102 at their ends facing away from the rotary feedthrough. The pipe lines 101 and 102 are connected to one another at their end on the drum opening side by means of a further pipe section 108. Nozzle-shaped outlet openings 109 are distributed uniformly over the length of the pipelines 101 and 102. The nozzles 109 are like this arranged that they lie in the mixed flow shadow during the mixing process, so that the free discharge of the mixing water is guaranteed. Reference number 110 denotes the drum drive, which is only shown schematically.

FIG. 5 shows a mixing drum according to FIG. 4, in which the mixing water is supplied from the pump 105 via the line 104 through the drum opening 3 to the pipe sections 106, 107 to the nozzles 109. The line 104 is connected to the rotating union 103 with the aid of a sleeve 111, which consists of elastic material. The sleeve is held and sealed with the help of clamp bands 112 and 113.

FIG. 6 shows a building material train composed of several truck mixers. Each truck mixer consists of a mixing drum 1, 1 ', 1''which is rotatably mounted on bearings 207 and 208 on a chassis 44. In the bearings 207 and 208, the drive for the rotary movement of the drums 1 to 1 ″ is accommodated at the same time. The drums 1 to 1 "are guided into the drums 1 to 1" surrounding guides 210 and 211. As can be seen from the drawing, the drum 1 to 1 "is arranged horizontally on the chassis. The left end face 212 of the drum 1 to 1 ″ in the drawing is frustoconical. A hollow cylindrical end 213 adjoins the truncated cone 212. The hollow cylindrical end 213 of the end wall 212 is during the filling process, as in FIG The middle of the picture is shown, closed. The opposite end wall 214 also has an opening 54, which, however, is not closed. The chute 216 of a filling funnel 217 extends into the opening 54, the upper opening 218 of which extends below the discharge opening 219 of a stationary mixing device or a concrete silo 220. Conical noses 221 are arranged on the hopper 217 in its lower region, only one of which is shown in the drawing. The filling funnel is supported and locked in corresponding conical sleeves 222 with these lugs 221. Inside the mixing drums 1 to 1 ″, helical elevations 11, 12 are attached to the drum casing. They range from one end wall to the opposite. In the region of the central axis of the drum 1 to 1 ″, helical flat profiles 26 and 27 are arranged, which extend from one end face 212 of the drum 1 to 1 ″ to the opposite end face 214. The flat profiles 26, 27 are wound in opposite directions to the elevations 11, 12 and connected to them by struts 227. The spiral formed by the flat profiles 26, 27 has a diameter which is approximately 1 1/2 to 1/3 of the diameter of the drum 1 to 1 ″. The truck mixers are coupled to one another with couplings 45, 46 and can be moved on rails 229.

The mixing drum 1 'is filled with building material from the silo 220 via the filling funnel 217 and the lateral opening 54. The drum 1 'rotates. The helical elevations 11, 12 drive the introduced building material to the opposite end face 212 of the drum 1 '. There the building material from the Flat profiles 26, 27 detected and conveyed back in the opposite direction due to their opposing spiral. At the end of the flat profiles, the building material falls down and is again picked up by the elevations 11, 12 and so on. If the drum 1 'is filled, the filling funnel 217 is removed and the following truck mixer is moved towards the drum 1' in such a way that the hollow cylindrical end 213 of the drum 1 '' extends into the filling opening 54 of the drum 1 'and closes it. The train is then moved until the conical sleeve 222 comes to rest on the chassis 44 of the truck mixer under the silo 220. Then the hopper 217 is inserted and the drum 1 '' can be filled. When all the truck mixers belonging to the train are loaded, the train goes to the place of use, eg in the tunnel, with the mixing drums rotating. There, the lids in the hollow cylindrical ends 213 of the drum 1 to 1 "are removed and the building material is applied as a result of the rotary movement of the drums 1 to 1" with the aid of the elevations 11, 12, the drums 1 to 1 "from empty continuously right to left.

FIG. 7 shows a modified embodiment of the invention. In the drum 1, only the mixing spirals 11, 12 are attached to the drum wall 9. Pipes 101, 102 which follow the course of the end faces of the mixing spirals 11, 12 facing the center of the drum connect nozzles 109 to one another, which are arranged distributed uniformly over the length of the mixing spirals 11, 12. The nozzles 109 are aligned so that their openings are in the mixed flow shadow during the mixing process and thus an undisturbed escape of the mixing water is guaranteed. The tubes 101, 102 are connected on the one hand via the tube 108 and on the other hand via the tubes 106 and 107, the tubes 106 and 107 starting radially from a rotary feedthrough 103 located in the drum 1, into which the feed line 104, which opens the nozzles 109 connects to a pump 105 outside the drum 1. Although the counter-current spirals 26, 27 are missing, this arrangement already results in a considerably improved mixing of the building material batch.

Claims (9)

1. A transportable mixer, preferably having a reverse-running emptying facility, for building materials, particularly concrete in a mixing drum (1), which facility has on its inner wall (9) one or more flat projections (11, 12) following a helical path and extending from the closed drum base (2) to the drum aperture (3), which projections are moved around the drum axis during rotation of the mixing drum (1) and drive the building material above the closed drum base (2) during transportation and during mixing, wherein in the mixing drum chamber encircled by the projections acting as mixing helices (11, 12) one or more flat profiles (26, 27) curved about the mixing drum axis (4) along helical paths are fixed to synchronise with the mixing drum rotation (5) and are arranged to run counter to the mixing helices (11, 12) such that they produce a counterflow during transportation and during mixing of the building material (13) in the middle of the building material charge surrounded by the mixing helices (11, 12), characterised in that the flat profiles (26, 27) project from the mixing drum base (2) and end before the mixing helices (11, 12) and the mixing drum aperture (3), and that the flat profiles (26, 27) of the counterflow helices are fixed to the projections of the mixing helices (11, 12) and by way of the mixing drum base (2) to the mixing drum wall (9) and that in the inside of the mixing drum (1) there are arranged nozzles (109) for the recovery of mixing water which are connected to one another by means of pipes (101, 102; 106, 107; 108) and to a pump (105) arranged outside the drum (1), wherein the nozzles (109) are so directed that their apertures lie underneath the mixing flow during the mixing process of the drum (1).
2. A transportable mixer according to claim 1, characterised in that the nozzles (109) are arranged on the flat profiles (26, 27) in the area of their forward sides directed towards the drum wall (9) and the pipes (101, 102) follow the course of the flat profiles (26e, 27) and at their ends terminate in a respective pipe piece (106, 107, 108) running in a plane radial to the longitudinal axis of the drum, wherein one of the pipe pieces is connected to a feed pipe (104) which leads to the pump (105) via a rotary duct (103) in one of the front sides of the drum (2, 3).
3. A transportable mixer, preferably having a reverse-running emptying facility, for building materials, particularly concrete in a mixing drum (1) which facility has on its inner wall (9) one or more flat projections (11, 12) following a helical path and extending from the closed drum base (2) to the drum aperture (3), which projections are moved around the drum axis during rotation of the mixing drum (1) and drive the building material above the closed drum base (2) during transportation and during mixing, wherein in the mixing drum chamber encircled by the projections acting as mixing helices (11, 12) one or are flat profiles (26, 27) curved about the mixing drum axis (4) along helical paths are fixed to synchronise with the mixing drum rotation (5) and are arranged to run counter to the mixing helices (11, 12) such that they produce a counterflow during transportation and during mixing of the building material (13) in the middle of the building material charge surrounded by the mixing helices (11, 12), characterised in that, on the front sided of the mixing helices (11, 12) facing the middle of the drum which are formed as flat raised areas, nozzles (109) are arranged which are connected to one another by means of pipes (101, 102, 108), which follow the course of the mixing helices (11, 12) and, by way of pipes (106, 107) and a rotary duct (103) which is arranged on one of the front sides (2, 3) of the drum (1), are connected by a feed pipe (104) to a pump (105), wherein the nozzles (109) are so directed that their apertures lie underneath the mixing flow during the mixing process of the drum (1).
4. A transportable mixer according to one of claims 1 to 3, characterised in that the nozzles (109) are covered with hollow-formed wear-resistant caps made of elastic or elastomeric material in which slit-shaped apertures are provided.
5. A transportable mixer according to one of claims 1 to 4, characterised in that the rotary duct (103) has several channels wherein each channel is fed respectively by a bump (105) and the channels are connected behind the rotary duct (103) via individual conduits to specified discharge nozzles (109).
6. A transportable mixer according to one of claims 1 to 5, characterised in that the mixing drum (1) is moved with an inclined orientation with the base (2) at the bottom and the aperture (3) at the top on the chassis of a transport vehicle (14).
7. A transportable mixer according to one of claims 1 to 5, characterised in that the mixing drum (47) is moved horizontally on the chassis (44) of a vehicle, and the mixing drum base (2) and the mixing drum aperture (54) are closable by covers (53, 55).
8. A transportable mixer according to claim 7, characterised in that the feed aperture (54) is arranged in the end wall of the drum (1, 1', 1'') opposite the drug end wall on the output side, and a feed hopper (217) can be fixed to extend with a chute (216) into the feed aperture (54).
9. A transportable mixer according to claim 8, characterised in that the feed hopper (217) has conical ends (221) which can be secured in two or more corresponding conical sockets (222)arranged on the chassis (44) of the vehicle.

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