PLANETARY MIXER FOR THE PRODUCTION OF CONCRETE

Description

[0001] The present invention relates to a planetary mixer for the production of concrete at construction sites or similar and at the sites of the manufacturers of prefabricated elements, in accordance with the preamble of claim 1.

[0002] In particular the present invention relates to a family of planetary mixers in which the part comprising the mixing tank is constructed from modular elements connected to each other by bolted joints, which facilitate the easy and rapid configuration of the position' and number of unloading doors with which the mixer is to be fitted. The upper part comprises a fixed reduction gear body which can be fitted with inspection doors or aggregate feed doors also in a modular fashion, and a corresponding rotary body which via an epicyclic gear mechanism transmits motion to the mixer and scraper paddles.

[0003] The drive unit rather than being concentrated in a single large gear motor is decentralised to one or more gear motors which transmit motion to a ring gear with the advantage of distributing the load to the teeth of the gearing at multiple points and thereby enabling an improved distribution of power.

[0004] This leaves the centre of the mixer free and available for housing a radial distribution system for distributing the ingredients needed to make the concrete. This system is the most important feature of the innovation and enables greater uniformity in the distribution of the ingredients.

[0005] The present invention applies to the industrial sector for the production of concrete using both fixed and mobile plant for the production of concrete.

BACKGROUND ART

[0006] It is well known that the equipment for the production of concrete comprises an aggregate storage unit, a mixing unit for receiving, measuring and dosing the aggregates, the water and the cement, a loading system for transferring the aggregates from the storage unit to the mixing unit and silos containing the cement; the silos are usually fitted with feed screws for conveying the cement to the mixing unit.

[0007] At the present time according to known technology, mixing is undoubtedly the most critical step in the concrete making process, so much so that the quality of concrete depends largely on the type of mixer used.

[0008] Vertical axis mixers are available in a variety of constructional variants. The most widely used have a central drive unit with the aggregate, cement and water feeds being mounted on the sides; this limits the space available for maintenance and cleaning.

[0009] The upper part has a substantially conical shape whereas the mixing tank is cylindrical and has one or more unloading doors. There are versions with twin drive units where the feed system is also centrally located.

[0010] There are mixers where the upper part is not conical but consists of a vertical extension of the cylindrical tank. In this case the covers do not open at the top but open at the sides; this feature makes efficient washing and cleaning more difficult.

[0011] Usually these mixers comprise a one-piece mixing tank with one or more unloading doors and with the epicyclic reduction unit mounted on top.

[0012] On many models the drive transmission system consists of gearing or a toothed crown wheel driven by a gear motor which has a drive pinion meshing with the transmission gearing.

[0013] On other models the drive is transmitted to the lower part of the reduction unit by a rack or a toothed bearing.

[0014] On some models where the drive transmission is a ring gear, the free central space is used for loading aggregates but the infeeds for cement, water and additives remain at the side.

[0015] The known method for water distribution usually consists of piping feeding water into the mixer on one side of the mixer rather than radially; this means that the water is not distributed uniformly to the mix.

[0016] In other applications the water is distributed by nozzles mounted on uprights on the upper part of the mixer, that is, on the arms supporting the main reduction gear and the drive motor; here there are only three or four water distribution points depending on the size of the mixer.

[0017] All these systems have the drawback that the water is not distributed uniformly with they result that the product obtained is of a low quality; this lack of uniformity can derive from the side mounting of the water distribution components.

[0018] Document WO 95/11120 A1 discloses a planetary mixer in acccordance with the preamble of claim 1 and more specifically comprising a stirring unit and a mixing vessel having a closable discharge opening. The mixer moreover comprises a scraper mechanism which is caused to describe an orbital movement about a central axis in the vessel by the stirring unit in operation. This scraper mechanism serves to raise a scraper blade (29) above the material during mixing and down into it during discharge.

[0019] U.S. Patent No. 2,174,089 discloses a mixer embodying a container adapted to receive and retain a quantity of material while mixing the same. This patent teaches the use of a suction and filtering device that withdraws air out of a feed system which is displaced by the fed cement. Furthermore, this document discloses the feeding of water in a mixing tank.

[0020] Document SU 1258467 A discloses the feeding of a powder and a liquid via concentric pipes. The water is sprayed as an umbrella-like shower on the sidewall of the mixing tank. The powder to be mixed with the water is projected by a flow divider onto the liquid film formed on the inside of the mixing tank.

DESCRIPTION OF THE INVENTION

[0021] The present invention provides a modular planetary mixer for the production of concrete which eliminates or at least reduces the shortcomings described above.

[0022] This is achieved by a concrete mixing system which can be transported on trucks or similar vehicles and whose characteristics are described in the main claim.

[0023] The dependent claims describe advantageous embodiments of the present invention.

[0024] In order to solve the drawbacks described above, the present invention uses the central part for feeding the concrete components such as water, cement and additives and at the same time provides a concentric feed system which optimises component distribution and reduces the effects of a lack of uniformity deriving from the side feeding of these components.

[0025] The present invention provides a concrete mixing system comprising modular tank elements where the mixing tank comprises sectors which can be fastened to each other in the configuration required and with the possibility of choosing, even at a later date, the position of the concrete unloading doors and the number of doors installed.

[0026] The modular construction can also be applied to the upper part of the mixer and to the installation of the inspection doors and the aggregate feeding door. The concentric design of the central system for distributing cement, water and additives enables the distribution and uniform mixing of the components on the entire mix being mixed.

[0027] In one embodiment of the invention, the outermost concentric pipe is connected at the bottom to a cone which forms an umbrella-like shower of water distributing the water radially over the entire surface.

[0028] This pipe has rectangular slits to prevent the formation of deposits in cases where dirty water is used.

[0029] The embodiment also comprises a sliding ring which partially covers the slits thereby regulating the flow of water.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further features and advantages of the invention will become apparent from the description of an example embodiment which follows with reference to the annexed drawings, given purely by way of a non-limiting example, in which:

• Figure 1 shows an overview of the entire plant which includes the planetary mixer for the production of concrete at construction sites or similar and at the sites of the manufacturers of prefabricated elements.
• Figure 2 is a front, partially cut-away view of the plant.
• Figure 3 is a view of the plant seen from above.
• Figure 4 shows a cross-section, side view of the plant.
• Figures 5 to 9 show various views of the plant according to the present invention; some of the figures show the plant partially exploded.
• Figure 10 shows diagrammatic views of the material and water feeding units and the dust extraction unit.
• Figure 11 shows a perspective view of the feed and extraction unit according to the present invention.

DESCRIPTION OF AN EXAMPLE EMBODIMENT

[0031] With reference to the annexed drawings, the plant substantially comprises a body 20 with a rounded shape which at the bottom has a tank 21, defined by sector modules and which at the top has a fixed body 22 or mixer carrying vertical-axis ring gear motors 23.

[0032] The fixed reduction gear body 22 in turn comprises a series of mixer elements operating inside the tank 21 while the central upper part of the fixed body is fitted with a feeder unit 24 used to feed water, cement and additives into the tank 21.

[0033] The mixer elements located inside the tank comprise a plurality of mixer paddles 25 and scraper paddles 26 actuated by a transmission system where generously overdimensioned planetary gear motors 23, flanged to the upper part of the mixer reduction gear body 22, transmit drive power to a strong ring gear 27 which powers the lower part 39 of the reduction gear body which acts as a planet carrier in such a way that the rotary body of the reduction gear box transmits drive power to the scraper paddles 26.

[0034] The mixer paddles 25 are driven by a sun gear 28 which meshes with a fixed, toothed crown wheel 29.

[0035] The coupling between the mixer planet, which drives the two or three mixer paddles, and the transmission shaft (38) driving the sun gear consists of splining; splines make timing easier and, above all, exclude the stress concentration factors otherwise found in keyed applications. This has the effect of making the transmission stronger and more resistant to the fatigue stresses to which mixers are subject.

[0036] The lower part 39 of the reduction gear body 22 houses a rotary seal 30 which has a twin purpose: to stop dust and contaminants entering into the reduction gear box 22 and to stop the leakage of lubricant from the reduction gear. The seal is mounted in a open groove to facilitate maintenance and is protected by containing sectors.

[0037] The inside parts of the mixing tank 21 in contact with the material are completely lined with interchangeable anti-wear panels 31 made from high abrasion resistant steel; for special applications a lining made from wearproof rubber can also be used.

[0038] The mixer paddles 25 are made from cast iron castings; variants made from high abrasion resistant steel or coated with wearproof rubber could also be used.

[0039] All the paddles are shaped to optimise the flow of material during mixing and to minimise friction and therefore the abrasion wear caused by aggregates.

[0040] Special hydrodynamic profiles were designed for the central paddles, for the peripheral scraper paddles and for the paddle support arms.

[0041] The tank 21 is constructed using sector modules 41, 42, fixed to each other with bolts and designed to facilitate variations in the position and number of the unloading doors 32. In cases where it necessary to add unloading doors it is sufficient to substitute a fixed sector with a sector fitted with a door. This is made possible by the design of the bolted joints on the mixer.

[0042] The main innovative feature of the present invention is the water, cement and additive distribution system, indicated in its entirety by the numeral 24. This is fixed to the fixed part of the reduction gear body 22 and comprises a series of concentric pipes visible in Figure 10.

[0043] The first, innermost pipe 33 is designed for the passage of cement given that the central distribution of cement together with the centrifuging of the aggregates in the tank is the ideal way of obtaining uniform distribution, reducing mixing times and improving the mechanical performance of concrete.

[0044] The outer concentric pipe 34 is designed to extract dust and being concentric with the cement pipe limits the deposits of unused cement dust on the inside walls of the mixer; this pipe forms an annular screen which extracts dust radially from the entire volume of the tank.

[0045] The last, outermost concentric pipe 35 is used for feeding in water and, thanks to a sector 36 with a cone-shaped lower edge, distributes an umbrella-like shower of water and additives radially over the entire surface of the tank through the openings 37 located at regular intervals. This radially distributed shower of water forms a barrier which also damps down the dust caused by the entry of the cement being fed in through a pipe which is concentric to the dust extraction pipe and the water pipe.

[0046] The additives enter the water pipe through the connectors (17).

[0047] Thanks to the efficiency of the forced mixing method used, the mixer in the present invention meets the technical requirements of a wide range of production processes and applications including the following: plant for loading truck-mounted concrete mixers; prefabricated concrete production facilities; mobile plant; construction site applications; special mixing process (for dusts, binders, industrial waste treatment and treatment of chemical materials).

[0048] The mixing flow is highly efficient thanks to centrifugal effect of the orbiting central planets (one or more depending on the capacity of the mixer model) combined with the centripetal effect of the perimeter scraper paddles.

[0049] The advantage of using multiple gear motors (23)(the number depends on the size of the mixer) is an improved distribution of torque to the ring gear 27 so that the toothing of the rack is less stressed in comparison with a rack driven by a single gear motor and therefore has greater fatigue resistance and a longer life.

[0050] The entire perimeter of the mixing tanks is fitted with steel panels 40, which can be opened a section at a time and which facilitate easy access to the mixing components. The mixer is fitted with inspection hatches and safety limit switches in compliance with the most stringent accident prevention regulations.

Claims

1. A planetary mixer for the production of concrete at construction sites or similar and at the sites of the manufacturers of prefabricated elements, where the mixer comprises a tank (21) fitted with a fixed reduction gear body (22) carrying mixing means and their actuating components and where the upper central part of the fixed reduction gear body (22) has a feeder unit (24), characterised in that the system for distributing water, cement and additives (24) is fixed to the fixed reduction gear body (22) and comprises a series of concentric pipes where the first, innermost pipe (33) is for the passage of cement, the outer concentric pipe (34) is for dust extraction and which, being concentric with the cement pipe, limits the formation of cement dusts, and the last, outermost concentric pipe (35) which is used for feeding in water and which thanks to a sector (36) with a cone-shaped lower edge, distributes an umbrella-like shower of water and additives radially over the entire surface of the tank through the openings (37) located at regular intervals; additives enter the water pipe through the connectors (17).

2. The planetary mixer for the production of concrete according to the foregoing claim, characterised in that the tank (21) is constructed from sector modules (41, 42), fixed to each other with bolts and designed to facilitate variations in the position and number of the unloading doors (32) being bolted to each other or to support columns.

3. The planetary mixer for the production of concrete according to the foregoing claim, characterised in that the mixing means inside the tank comprise a plurality of mixer paddles (25) and scraper paddles (26) actuated by a transmission system where planetary gear motors (23), flanged to the upper part of the fixer reduction gear body (22), transmit drive power to a ring gear (27) which powers the lower part (39) of the reduction gear body which acts as a planet carrier, in such a way that the rotary body of the reduction gear box transmits drive power to the scraper paddles (26).

4. The planetary mixer for the production of concrete according to claim 3, characterised in that the mixer paddles (25) are driven by a sun gear (28) which meshes with a fixed, toothed crown wheel (29).

5. The planetary mixer for the production of concrete according to claims 4, characterised in that the coupling between the mixer planet and the sun gear shaft comprises splining designed to make timing easier and to exclude the stress concentration factors otherwise found in keyed applications.

6. The planetary mixer for the production of concrete according to one of the foregoing claims, characterised in that the lower part (39) of the fixed reduction gear body (22) houses a rotary seal (30) mounted in a open groove, to facilitate maintenance, protected by containing sectors.

7. The planetary mixer for the production of concrete according to one of the foregoing claims, characterised in that the inside parts of the tank (21) in contact with the material are completely lined with interchangeable anti-wear panels (31) made from high-abrasion resistant steel.

8. The planetary mixer for the production of concrete according to one of claims 4-7, characterised in that the mixer paddles (25) are made from cast iron castings or made from high abrasion resistant steel or coated with wearproof rubber and also characterised in that all the paddles are shaped to optimise the flow of material during mixing and to minimise friction and therefore abrasion wear caused by the aggregates.

Ansprüche

1. Planetenmischer zur Herstellung von Beton auf Baustellen oder dergleichen und auf dem Gelände von Herstellern vorgefertigter Elemente, wobei der Mischer aus einem Tank (21) besteht, der mit einem Reduktionsgetriebekörper (22) zur Aufnahme einer Mischeinrichtung und ihrer Antriebsteile ausgerüstet ist, wobei der obere zentrale Teil des festen Reduktionsgetriebekörpers (22) eine Beschickereinheit (24) aufweist,
dadurch gekennzeichnet, dass
das für die Verteilung von Wasser, Zement und Additiven dienende System (24) am festen Reduktionsgetriebekörper (22) befestigt ist und dass es eine Reihe von konzentrischen Rohren aufweist, wobei das erste innerste Rohr (33) dem Durchlauf von Zement dient, das äußere konzentrische Rohr (34) der Entstaubung gilt und konzentrisch mit dem Zementrohr die Zementstaubbildung verhindert, und das letzte äußerste konzentrische Rohr (35) der Wasserzufuhr dient und mittels einem eine kegelförmige Unterkante aufweisenden Abschnitt (36) eine schirmartige Brause aus Wasser und Additiven durch die in regelmäßigen Abständen angebrachten Öffnungen (37) radial über die gesamte Oberfläche des Tanks verteilt; und dass Additive durch die Anschlüsse (17) in das Wasserrohr gelangen.

2. Planetenmischer zur Herstellung von Beton gemäß Anspruch 1,
dadurch gekennzeichnet, dass der Tank (2) aus Abschnittmodulen (41, 42) gebaut ist, die mit Bolzen aneinander befestigt und so konstruiert sind, dass sie verschiedene Positionen und eine verschiedene Anzahl an Entleerungstüren (32) ermöglichen können, die mit Bolzen aneinander oder an Stützsäulen befestigt sind.

3. Planetenmischer zur Herstellung von Beton gemäß Anspruch 1, 2
dadurch gekennzeichnet, dass die Mischeinrichtung im Tank mehrere Mischpaddel (25) und Schaberpaddel (26) aufweist, die von einem Getriebesystem betätigt werden, wobei am oberen Teil des festen Reduktionsgetriebekörpers (22) angeflanschte Planetengetriebemotoren (23) Kraft auf ein Hohlrad (27) übertragen, das den unteren Teil (39) des Reduktionsgetriebekörpers antreibt, welcher als Planetenträger so funktioniert, dass der Rotationskörper des Reduktionsgetriebegehäuses Antriebskraft auf die Schaberpaddel (26) überträgt.

4. Planetenmischer zur Herstellung von Beton gemäß Anspruch 3,
dadurch gekennzeichnet, dass die Mischpaddel (25) von einem Sonnenrad (28) angetrieben werden, das in ein festes gezähntes Kronrad (29) eingreift.

5. Planetenmischer zur Herstellung von Beton gemäß Anspruch 4,
dadurch gekennzeichnet, dass die Kupplung zwischen dem Mischerplaneten und der Sonnenradwelle eine Verzahnung aufweist, um das Timing zu erleichtern und die Spannungskonzentrationsfaktoren auszugrenzen, die sonst bei gezahnten Anwendungen auftreten.

6. Planetenmischer zur Herstellung von Beton gemäß einem der vorhergehenden Ansprüche,
dadurch gekennzeichnet, dass der untere Teil (39) des festen Reduktionsgetriebekörpers (22) einen Drehverschluss (30) aufweist, der in einer offenen Rille befestigt ist, um die Wartung zu erleichtern, und der durch Haltebereiche geschützt ist.

7. Planetenmischer zur Herstellung von Beton gemäß einem der vorhergehenden Ansprüche,
dadurch gekennzeichnet, dass die mit dem Material in Berührung kommenden inneren Teile des Tanks (21) vollständig mit austauschbaren Platten (31) aus hochabriebfestem Stahl verkleidet sind.

8. Planetenmischer zur Herstellung von Beton gemäß einem der Ansprüche 4 bis 7,
dadurch gekennzeichnet, dass die Mischpaddel (25) aus Gusseisen oder hochabriebfestem Eisenguss bestehen oder mit verschleißfestem Gummi beschichtet sind und dass alle Paddel so geformt sind, dass der Materialfluss beim Mischen optimiert wird und die von den Aggregaten verursachte Reibung und damit der Abrieb minimalisiert wird.

Revendications

1. Mélangeur planétaire pour la production de béton à des sites de construction ou similaire et aux sites des fabricants d'éléments préfabriqués, où le mélangeur comprend un réservoir (21) équipé d'un corps d'engrenage réducteur (22) fixe, supportant des moyens mélangeurs et leurs composants d'actionnement et où la partie centrale supérieure du corps d'engrenage réducteur (22) comporte une unité d'alimentation (24), caractérisé en ce que le système pour distribuer l'eau, le ciment et des additifs (24) est fixé au corps d'engrenage réducteur (22), et comprend une série de tuyaux concentriques dont le premier tuyau le plus intérieur (33) sert au passage de ciment, le tuyau concentrique extérieur (34) sert à l'extraction de poussière et, étant concentrique au tuyau de ciment, limite la formation de poussières de ciment, et le dernier tuyau concentrique le plus extérieur (35) est utilisé pour l'alimentation en eau et, grâce à un secteur (36) avec un bord inférieur de forme conique, distribue une pluie d'eau semblable à un parapluie et des additifs radialement au-dessus de la surface entière du réservoir par les ouvertures (37) situées à intervalles réguliers ; les additifs entrent dans le tuyau d'eau par les connecteurs (17).

2. Mélangeur planétaire pour la production de béton selon la revendication précédente, caractérisé en ce que le réservoir (21) est construit à partir de modules en secteurs (41, 42) fixés les uns aux autres avec des boulons et conçus pour faciliter les variations dans la position et le nombre de trappes de déchargement (32) boulonnées les unes aux autres ou à des colonnes de support.

3. Mélangeur planétaire pour la production de béton selon la revendication précédente, caractérisé en ce que les moyens de mélange à l'intérieur du réservoir comprennent une pluralité de pales de mélangeur (25) et de pales de racloir (26) actionnées par un système de transmission dans lequel des moteurs d'engrenages planétaires (23), bord à bord avec la partie supérieure du corps d'engrenage réducteur (22), transmettent une puissance motrice à un engrenage annulaire (27) qui entraine la partie inférieure (39) du corps d'engrenage réducteur qui agit comme un support planétaire, de manière à ce que le corps rotatif de la boite d'engrenages de réduction transmette une puissance motrice aux pales de racloir (26).

4. Mélangeur planétaire pour la production de béton selon la revendication 3, caractérisé en ce que les pales de mélangeur (25) sont entrainées par un pignon d'engrenage (28) en prise avec une roue en couronne dentée (29) fixée.

5. Mélangeur planétaire pour la production de béton selon la revendication 4, caractérisé en ce que le couplage entre le mélangeur planétaire et l'arbre du pignon d'engrenage comprend des cannelures conçues pour rendre la temporisation plus aisée et pour exclure les facteurs de concentration de contraintes trouvés autrement dans les applications à clavettes.

6. Mélangeur planétaire pour la production de béton selon l'une des revendications précédentes, caractérisé en ce que la partie inférieure (39) du corps d'engrenage de réduction (22) renferme un joint rotatif (30) monté dans une rainure ouverte, pour faciliter la maintenance, protégé par des secteurs qui le contiennent.

7. Mélangeur planétaire pour la production de béton selon l'une des revendications précédentes, caractérisé en ce que les parties intérieures du réservoir (21) au contact du matériau, sont entièrement doublées avec des panneaux anti-usure (31) interchangeables, réalisés à partir d'un acier résistant anti-abrasion.

8. Mélangeur planétaire pour la production de béton selon l'une des revendications 4 à 7, caractérisé en ce que les pales de mélangeur (25) sont faites de fonte de fer coulé, ou d'acier à haute résistance à l'abrasion ou sont revêtues d'un caoutchouc résistant à l'usure et également caractérisé en ce que toutes les pales sont conformées pour optimiser l'écoulement de matériau durant le mélange et minimiser la friction et donc l'usure par abrasion occasionnée par les agrégats.

Drawing