DE20308984U1 - Mixer conveyor for cement mortar with washing device for the mixing container - Google Patents

Description

WEICKMANN &

Patent attorneys
European Patent Attorneys · European Trademark Attorneys

Our sign:

30804G DE/BR

DIPL.-ING. H. WEICKMANN (t»s3i.i.oi>

DIPL.-ING. FA WEICKMANN

DIPL.-CHEM. B. HUBER

DR-ING. H. LISKA

DIPL-PHYS DR. J. PRECHTEL

DIPL.-CHEM. DR. B. BÖHM

DIPL.-CHEM. DR. W. WEISS

DiPL.-PHYS. dr. J. TIESMEYER

DIPL-PHYS. DR. M. H ERZO G

DiPL-PHYs. B. RUTTENSPERGER

DIPL.-PHYS. DR.-ING. V.JORDAN

DIPL.-CHEM. DR. M. DEY

DIPL.-FORSTW. DR. J. LACHNIT

1 6 June 2003

Applicant:

AXECO S.p.A. Via Venezia 35

10088 VOLPIANO (Torino) Italy

Mixer conveyor for cement mortar
with washing device for the mixing container

P.O. Box 860 820, 81635 Munich, Germany, Tel. (089) 45563 0, Fax (089) 45563 999, email@weickmann.de

Mixer conveyor for cement mortar with washing device for the mixing container

Description

The invention relates to mixer-conveyors used in the construction industry for mixing and transporting over a certain distance limited quantities of cement mortar or light concrete mixtures, which can be used, for example, to produce cement bases for floors or paving or small concrete fills on site.

In particular, the invention relates to mixer conveyors containing:
a mixing tank consisting of a cylindrical body with a horizontal axis, provided at its ends with two concave bottom parts and mounted on a chassis equipped with wheels,

- a shaft mounted inside said container so as to rotate about said horizontal axis of the cylindrical body of the container and carrying a plurality of mixing blades,

- a gear motor for driving the rotary movement of said shaft,

- a loading opening arranged in the upper part of the cylindrical body part mentioned and which can be sealed by a cover hinged to this opening,

- this feed opening is provided with a connecting part in order to connect it to an air compressor via a pipe and thus to be able to pressurise the interior of the mixing container,

- a discharge opening located in the lower part of the above-mentioned cylindrical body part and provided with a connecting part to its

· · f

- 2-

connection to a feed pipe intended to convey the material mixed in the mixing tank to a place of use, this connection part being designed in such a way that it also allows its connection to an air injection pipe branched off from the pipeline which supplies compressed air into the interior of the mixing tank.

In the case of mixer-conveyors of the known type described above, it is necessary to wash or rinse the interior of the mixing tank after use in order to prevent the formation of deposits due to the solidification of the cement mortar residues which inevitably remain in the tank after the end of the work.

According to the state of the art, this washing or rinsing was carried out manually by introducing pressurised water into the interior of the container through the loading opening by means of a washing or rinsing lance connected to the water supply network or a washing gun connected at one end to the water supply network and at the other end to the aforementioned pipe for the compressed air supply.

This manual washing process required considerable time and did not allow complete cleaning, particularly as regards those parts of the internal surface of the mixing tank against which it was not possible to directly direct the water jet emitted by the lance or the washing gun.

In order to eliminate the aforementioned disadvantage, the invention relates to a mixer-conveyor of the type described above, the main feature of which lies in the fact that:

- the rotating shaft carrying the mixing blades is provided with a longitudinal bore at its centre forming a channel extending over the entire length of the shaft,

- 3-

- this hole is closed at one end of the shaft and is connected at the opposite end to a pipe leading to a pump capable of pumping high-pressure water into the said longitudinal channel of the shaft and

- the above-mentioned longitudinal channel of the shaft is connected near each of the two above-mentioned convex bottom parts of the mixing vessel to a nozzle which is inclined towards the concave inner surface of the corresponding bottom part 2 and is capable of directing a preferably fan-shaped diverging water jet towards said surface.

In particular, the longitudinally extending bore of the rotating shaft is closed at the end of the shaft which receives the movement from the above-mentioned gear motor and is connected at the opposite end, via a rotary coupling for high pressures, to a connector fixed to the housing to which the pipe leading to the pump capable of introducing high-pressure water into the above-mentioned channel is connected.

Due to the above-mentioned feature, the two water jets emitted by the two nozzles mentioned are deflected by the internal surfaces of the mixing tank against which they are directed, so as to effect, quickly and without the need for manual intervention, an effective washing or rinsing of the mixing tank.

According to a second preferred embodiment, in order to prevent the cement mortar or concrete mixtures from clogging the said nozzles and the channel of the shaft during mixing, conveying or introduction, a stream of compressed air is introduced into the latter during these phases, which prevents clogging by pressurizing the device.

In this case, the longitudinally extending channel of the shaft is connected to a nozzle inclined towards the concave inner surface of the corresponding bottom part, which is capable of directing a preferably fan-shaped jet of water onto said surface during the washing phase of the mixing tank, and to a second pipe connected to said air compressor in order to inject a stream of compressed air into the channel and nozzles during the mixing and feeding phases, when no high-pressure water is fed, in order to pressurise them in such a way as to counteract the clogging of these nozzles and the channel by the mixed material.

An embodiment of the invention will now be described with reference to the accompanying drawings.

Figure 1 shows a longitudinal section through the mixing and

Conveyor tank, and

Figure 2 is a side view in enlarged scale and partial

Sectional view of one of the two for washing out the

Nozzles used in the mixing tank.

Referring to Figure 1, 1 designates the mixing tank of a cement mortar mixer and conveyor, which is internally lined with wear-resistant sheets.

The container 1 is preferably intended to be mounted on a wheeled chassis in a manner known per se and comprises a cylindrical body part 2 with a horizontal axis and two convex bottom parts 3 at the ends.

-5 -

Reference numeral 4 designates a shaft which is supported by end bearings 5 and 5a inside the container 1 in such a way that it can rotate about the mentioned horizontal axis.

The shaft 4 has an outer surface of square cross-section to which are fixed in a known manner - by screw clamps - five blades with a curved profile, designated 7, 8, 9, 10, 11.

In the area of the bearing 5, the end of the shaft 4 is connected to a reduction gear 6, which in turn can be connected to a motor, schematically designated 12, whose task is to set the shaft 4 in rotation.

According to a first embodiment of the prior art, the motor 12 consists of a hydraulic motor driven - by means of an oil-hydraulic pump - by a diesel engine mounted on the same chassis that supports the container 1.

In a second embodiment, also belonging to the prior art, in which a motor-driven compressor is used, the above-mentioned motor 12 consists of an electric motor.

The container 1 has a loading opening 13 in its upper part for the introduction of the material to be mixed. The loading opening 13, which can be closed by a sealing cover 14, has a connecting piece 15 for its connection to an air compressor 16 by means of a pipe 15a.

In the above-mentioned first prior art embodiment, the air compressor 16 is driven directly by the diesel engine located on the chassis supporting the container.

- 6-

In the above-mentioned second prior art embodiment, the air compressor 16 is driven by the diesel engine mounted on a separate chassis.

The container 1 has in its lower part a discharge opening 17 which, in accordance with the prior art, is provided with a connecting part 18 for its connection to a feed pipe (not shown).

This feed pipe serves to supply the material mixed in the mixing container 1 by means of the rotary movement of the shaft 4 carrying the blades 7 to 11 to a place of use as a result of the excess air pressure generated in the container 1 by the compressed air fed in by the compressor 16.

Conveniently, the connection part 18 - according to the prior art - is designed in such a way that it can also be connected to an air injection pipe (not shown) which is branched off from the pipeline 1 5a, which conveys compressed air into the interior of the mixing container 1 and helps to press the material mixed in the container 1 into the mentioned feed pipe.

According to the invention, the shaft 4 carrying the mixing blades 7 to 10 is provided in the middle with a longitudinal bore 19 which forms a channel extending over the entire length of the shaft. This channel is closed at the end of the shaft 4 which receives the movement from the motor 12. At the opposite end of the shaft 4, the channel 19 is connected - via a rotatable coupling 20 known per se - to an angled connecting piece 21 carried by the container 1.

The connecting piece 21 is connected to a pipe 22 leading to a pump 23 which is able to supply water under high pressure to the aforementioned longitudinal channel 19.

In the case of the above-mentioned first embodiment according to the prior art, in which the motor 12 causing the rotary movement of the shaft 4 is a hydraulic motor, the water pump 23 is operated - via a hydraulic converter unit known per se - by the pressure oil of the hydraulic circuit driving the aforementioned hydraulic motor 12.

In the case of the above-mentioned second embodiment according to the prior art, in which the motor 12 is an electric motor, the pump 23 can be actuated by an electric motor, i.e. by the pressurized oil supplied from a separate hydraulic center driven by an electric motor.

The channel 19 of the shaft 4 is connected, near each of the two convex bottom parts 3 of the mixing container 1, to a device - designated overall by 24 - which contains a nozzle which can direct a preferably fan-shaped water jet onto the above-mentioned surface.

As shown in Figure 2, each device 24 comprises an angle piece 25 which is provided at one end with a threaded nipple 25a which can be screwed into a radially aligned threaded bore provided in the shaft 4 and communicating with the axial channel 19.

The angle piece 25 is connected at the other end to a nozzle 26 which is contained in a protective cap 27 which is screwed onto the angle piece 25 and has a bore 28 at its base. 29 designates a rubber disk which is mounted in an annular groove adjoining the base of the cap 27 and has a central bore 30.

- 8th-

which is opposite the bore of the nozzle 26 and has a smaller diameter than the bore 28 of the cap 27.

A pipe 31 connected to the air compressor 16 is expediently connected to the pipe 22 introducing the pressurized water, which pipe is capable of introducing a stream of compressed air 32 into the longitudinal channel 19 and into the nozzles 26 for pressurizing the air during the mixing and feeding phases of the machine's working cycle. At least one high-pressure non-return valve 33 and preferably a second valve, namely a safety low-pressure non-return valve 34, are expediently connected to the aforementioned pipe 31 before it is connected to the water-supplying pipe 22.

Preferably, the pipeline 31 is branched off from the pipeline 15a, which supplies compressed air into the interior of the mixing container.

The construction described above enables each of the two nozzles 26 - in the mixing phase - to direct a fan-shaped water jet with an opening angle A of the order of 25° against the concave inner surface of the base part 3 towards which the nozzle is directed.

This water jet is deflected by the concave inner surface against which it is directed so that it quickly and automatically carries out an effective internal washing or rinsing of the mixing container 1.

The washing phase referred to above takes place at the end of the normal working process carried out in accordance with the state of the art, i.e. after the cement mortar has been mixed and fed to the site by air pressure.

The water accumulated in the container after the end of the washing process can be drained together with the water

blasting, the mortar residues detached from the inner walls of the container can be discharged by gravity through the discharge opening 17, the feed pipe being removed, i.e. the compressed air can be used to carry out the discharge through the feed pipe connected to the aforementioned discharge opening, in such a way that the inner surface of this pipe is also washed.

During the mixing and transport phases of the cement mortar or concrete mixtures, when no high-pressure water is introduced for washing, the channel 19 is conveniently pressurized by introducing a flow of compressed air 32 through the pipe 31 and the check valves 33 and 34. In this way, the pressure in the channel 19 is kept in balance by the pressure of the internal chamber of the mixing tank 1. The air flow emerging from the nozzles 26 counteracts their clogging by preventing the ingress of part of the mixed material and keeps the device 24 constantly clean.

The working pressure of the washing water pumped through the feed pipe 22 is considerably higher than the working pressure of the air flow for pressurizing against the blockage, so that the introduction of compressed air into the channel is automatically interrupted as a result of this pressure difference when the water pump 23 is switched on in the washing phase. In this case, the check valves 33 and 34 prevent the flow of washing water to the compressor 16.

The supply of compressed air automatically resumes when the water pump 23 stops and the pressure in the channel 19 drops to such an extent that it becomes lower than the pressure of the air returned by the compressor.

Vi I 'III - ^: -V·:· i 5 :

- 10-

A cement mortar mixer-conveyor comprises a mixing vessel in which a shaft is pivotally mounted centrally, driven by a gear motor and carrying a plurality of curved blades. The centrally arranged shaft has a longitudinal channel in its centre, which extends along its entire length and can be connected to a source of pressurised water and a source of compressed air at the end of the shaft opposite the driving gear motor. The longitudinal channel of the shaft is connected at each of its ends to an inclined nozzle which serves to automatically wash the inner surface of the mixing vessel with a jet of pressurised water when the operation of mixing the cement mortar and conveying it to the place of use is completed. During the mixing and conveying phases, when no pressurised water is introduced, a stream of compressed air is introduced into the longitudinal channel of the shaft and into the nozzles to pressurise them, thus counteracting their clogging by the mixed material.

Claims (7)

1. Mixer-conveyor for cement mortar, containing: - a mixing vessel ( 1 ) consisting of a hydraulic body part ( 2 ) provided at the ends with two convex bottom parts ( 3 ), - a shaft ( 4 ) mounted inside the container ( 1 ) so as to rotate about the horizontal axis of the cylindrical body part ( 2 ) of the container and carrying a plurality of mixing blades ( 7 , 8 , 9 , 10 , 11 ), - drive devices ( 12 , 6 ) for driving the rotary movement of the shaft ( 4 ), - a feed opening ( 13 ) which can be sealed by a cover ( 14 ) and is connected via a pipe ( 15 a) to an air compressor ( 16 ) for the purpose of pressurizing the inner chamber of the mixing container ( 1 ), and - a discharge opening ( 17 ) which can be connected to a feed pipe, the task of which is to convey the material mixed in the mixing container ( 1 ) to a place of use, characterized in that - the rotating shaft ( 4 ) carrying the mixing blades ( 7 to 11 ) is provided in the middle with a longitudinal bore ( 19 ) which forms a channel extending over the entire length of the shaft, - this bore ( 19 ) is closed at one end of the shaft ( 4 ) and is connected at the opposite end to a pipe ( 22 ) leading to a pump ( 23 ) capable of pumping high-pressure water into the longitudinal channel of the shaft ( 4 ) and - the longitudinal channel ( 19 ) of the shaft ( 4 ) is connected near each of the two convex bottom parts ( 3 ) of the mixing container ( 1 ) to a nozzle ( 26 ) which is inclined towards the concave inner surface of the respective bottom part ( 3 ) and is capable of directing a preferably fan-shaped diverging water jet onto the aforementioned surface. 2. Mixer-conveyor according to claim 1, in which the nozzles ( 26 ) are able to direct a jet of water against the inner surface of the mixing container ( 1 ) during a washing phase of the mixing container (1), characterized in that the longitudinally extending bore ( 19 ) in the shaft ( 4 ) is also connected to a second pipe ( 31 ) connected to the air compressor ( 16 ) for introducing a flow of compressed air ( 32 ) for pressurizing the channel and the nozzles ( 26 ) during the mixing and conveying phases when no high-pressure water is fed in, so as to counteract the clogging of the nozzles ( 26 ) and the channel ( 19 ) by the mixed material. 3. Mixer conveyor according to claim 1 or 2, characterized in that the discharge opening ( 17 ) is provided with a connecting part ( 18 ) for its connection to the feed pipe, wherein the connecting part ( 18 ) is designed such that it can also be connected to an air injection pipe which is branched off from the pipeline ( 15a ) which injects compressed air into the interior of the mixing container ( 1 ). 4. Mixer-conveyor according to claim 1, 2 or 3, characterized in that each of the two nozzles ( 26 ) is carried by a device ( 24 ) which contains: - an angle piece ( 25 ) provided at one end with a threaded nipple ( 25 a) which is screwed into a radial threaded bore in the shaft ( 4 ) and communicates with the axial channel ( 19 ) of the shaft ( 4 ), - a nozzle ( 26 ) connected to the other end of the elbow ( 25 ), - a protective cap ( 27 ) which is screwed onto the angle piece ( 25 ) and surrounds the nozzle ( 26 ), the protective cap ( 27 ) being provided with a bore ( 28 ) at its bottom, and - a rubber disk ( 29 ) which is mounted in an annular groove adjoining the base of the cap ( 27 ) and has a central opening ( 30 ) which is opposite the bore of the nozzle ( 26 ) and has a smaller diameter than the bore ( 28 ) of the cap ( 27 ), the aforementioned components being dimensioned such that a water jet emerges from each of the two nozzles ( 26 ), which preferably has an opening angle (A) of the order of 25°. 5. Mixer conveyor according to claim 2, characterized in that the pipeline ( 31 ) for introducing the compressed air into the longitudinal channel ( 19 ) of the shaft ( 4 ) and into the nozzles ( 26 ) is branched off from the pipeline ( 15a ) which feeds the compressed air into the interior of the mixing container ( 1 ) and is connected to the pipeline ( 22 ) for introducing high-pressure water. 6. Mixer-conveyor according to claim 5, characterized in that the working pressure of the washing water pumped in via the feed pipe ( 22 ) is considerably higher than the working pressure of the air flow for pressurizing against the blockage ( 32 ), so that the introduction of compressed air into the channel is automatically interrupted as a result of this pressure difference when the water pump ( 23 ) is operating and restarts when the operation of the pump ( 23 ) is interrupted, and the pipe ( 31 ) for the introduction of compressed air contains at least one high-pressure check valve ( 33 ) and preferably a second valve, namely a low-pressure check valve ( 34 ), which are arranged upstream of the connection to the pipe ( 22 ) for the introduction of water as control devices capable of preventing the flow of water to the compressor. 7. Mixer-conveyor according to any one of the preceding claims, characterized in that the longitudinal channel ( 19 ) of the shaft ( 4 ) is connected to the pipe ( 22 ) for the introduction of the high-pressure water by a connecting part ( 21 ) carried by the mixing tank ( 1 ) via a rotatable high-pressure coupling ( 20 ).