EP1803496B1 - Mixer with automatic cleaning - Google Patents

Abstract

The mixer, comprising a bowl (12) and a mixing tool (3) that performs a double rotary motion inside it, includes an automatic system for separate cleaning of the mixing tool and bowl. The bowl is mounted on a mobile frame (10) allowing it to adopt three different positions: an upper operating position where it is sealed by a cover (4) on the fixed frame (1) carrying the mixing tool, a lower inverted position for emptying, and a third position facing the cleaning implements, where it is sealed by a second cover (20). Both bowl and mixing tool are cleaned by brushes (27, 30) designed to remove traces of mixed materials.

Description

The present invention relates to an automatic cleaning mixer.

New fast setting binder products such as gypsum, high performance fine concrete, resins, have recently appeared on the market and seem to have a very promising future.

• aucune trace de germe ne doit subsister ni dans la cuve de malaxage ni sur l'outil de malaxage parce que ces traces vont agir comme des accélérateurs de prise et modifier les performances du produit.

However, they present very difficult implementation difficulties for their industrial manufacture:

• no trace of germ must remain in either the mixing tank or the mixing tool because these traces will act as setting accelerators and change the performance of the product.

The fouling of the tools reduces their efficiency and disturbs the quality of the mixtures in case of detachment of elements.

It has been attempted to achieve the desired mixing with kneaders used in bakery that is to say consist of a tank whose internal volume is stirred by a mixing tool or blade driven by a double rotational movement, the first around the axis of the tank, the second on itself.

In known devices, the rotational movement on itself of the mixing tool is obtained by a planetary gear. Mixers of this type are exposed in FR-A-2 402 471 and in FR-A-2,849,788 .

Such kneaders have good kneading performance, but it has proved impossible to automatically remove absolutely any trace of mixing after a kneading operation; a manual cleaning operation proving essential.

Other cleaning devices consist in projecting a liquid by means of nozzles into the chamber formed by the tank and the kneading mechanism. This presents, in practice, poorly cleaned areas and sometimes requires drying after cleaning.

The present invention therefore has for its first object to provide a mixer equipped with automatic cleaning means leaving no trace of produced neither on the walls of the tank nor on the mixing tool after a kneading operation.

On the other hand, the present invention comprises means of independent adjustment of the two speeds of rotation of the tool to optimize each step of mixing and to avoid wear phenomena in preferred places of the tank.

In addition, the present invention is characterized by the fact that the cleaning is confined, and therefore without pollution, by sealing and suction.

Figure 1

une vue schématique en coupe latérale d'un exemple de réalisation de l'invention en position de malaxage

Figure 2

une vue de l'appareil de la figure 1 en position de vidange de la cuve

Figure 3

une vue de l'appareil des figures 1 et 2 en position de nettoyage automatique

Figure 4

une vue schématique en plan illustrant les deux positions de l'outil de malaxage pendant son nettoyage

Figure 5

une vue de détail en coupe longitudinale illustrant le mécanisme de double rotation de l'outil de malaxage.

By way of non-limiting example, and to facilitate the understanding of the invention, there is shown in the accompanying drawings:

Figure 1

a schematic side sectional view of an exemplary embodiment of the invention in the mixing position

Figure 2

a view of the device from the figure 1 in the emptying position of the tank

Figure 3

a view of the camera figures 1 and 2 in automatic cleaning position

Figure 4

a schematic plan view illustrating the two positions of the mixing tool during its cleaning

Figure 5

a detail view in longitudinal section illustrating the double rotation mechanism of the kneading tool.

Referring to these figures, it can be seen that the apparatus according to the present invention comprises a stationary carrier chassis 1 and a movable carrier chassis 10.

The fixed frame 1 has the form of a bracket and carries at its end a mechanism 2 for driving a mixing tool 3.

Mechanism 2 will be described in detail in relation to the figure 5 . With this mechanism, the kneading tool 3 is rotated both around the X axis and on itself around the Y axis.

The mobile frame 10 is carried by the fixed frame 1 and actuated by means that allow it to go up and down.

The frame 10 carries a support 11, on which a tank 12 is pivotally mounted.

When the frame 10 is in the up position, as shown in FIG. figure 1 , the upper rim of the tank 4, which is conical, is engaged in the lower conical flange of a fixed cover 4 carried by the frame 1.

In a design variant, the fixed tool frame becomes mobile. The tank carrier frame being stationary or movable.

In this position the tank 12 is closed hermetically, so that no dust can escape during mixing.

Although this is not shown to simplify the drawing, the lid 4 has closable orifices for introducing into the tank 12 the various products to be mixed by mixing, such as sand, gypsum, admixtures, water or other.

When the mixing is completed, the frame 10 is brought into the lower position and the tank 12 is rotated by 180 °, as shown in FIG. figure 2 . the kneaded product then falls into a hopper or conveyor which are not shown because they do not form part of the invention.

When the tank is empty, there remains a significant amount of products glued against its walls. Likewise, a certain amount of kneaded product remains stuck to the branches of the kneading tool 3.

It is imperative before proceeding to a new kneading operation to clean the tank 12 and the tool 3 so that it does not remain the smallest plot of product.

It has indeed been found, in tests with known kneaders, that the slightest trace of product constitutes a setting accelerator germ such that if the tank 12 is filled again, there will be a start of setting during kneading. which will make impossible a homogeneous mixing and will make unusable the products put in the tank.

The apparatus according to the present invention therefore comprises two cleaning assemblies: a first for the interior of the tank 12, a second for cleaning the branches of the mixing tool 3.

After being turned 180 ° to be emptied, the tank 12 is rotated 90 ° to occupy a horizontal position, its orifice being turned towards the apparatus, as shown in FIG. figure 3 .

A movable cover 20, similar to the fixed cover 4, carried by a carriage 22 rolling between rollers 23 and moved by a lever 24 moved by a jack 25 closes the tank 12 hermetically.

This lid carries at its center, rotatably mounted, a tube 26 which may be a hollow tube, said tube 26 carrying a set of brushes 27 conforming to the shape of the inner wall of the tank 12.

The lid 20 comprises at its upper part an air inlet orifice 28 and at its lower part an air outlet orifice 29, connected to a duct for exhausting air + dust 41, this duct being telescopic to follow the movements of the lid 20 and connected to a suction and filtration device 40.

The tube 26 is rotated by any suitable motor, so that the set of brushes 27 strongly rubs against the inner wall of the tank 12. The products and dust detached by the brushes 27 are sucked into the pipe 41.

The tank 12 is then cleared of any trace of product.

The tube 26 being hollow can be used to spray a little water or solvent to complete the brushing work.

The second cleaning assembly has the function of cleaning the mixing tool 3.

It consists of brushes 30 disposed at the opening of a box 31 carried by a carriage 32. The enclosure of the box 31 is connected by a telescopic pipe 42 to the suction device 40.

In the example shown, when the carriage 32 is moving forward, the kneading tool 3 passes between two parallel cylindrical brushes 30 and penetrates inside the box 31. The particles of kneaded product which had remained stuck to the branches of said tool 3 are detached and aspirated in the device 40.

Preferably, the longitudinal opening 33 of the box 31, between the two brushes 30, is masked by brushes son to prevent product particles may fall outside the box 31.

In kneading machines known, such as for example those used in bakery, the kneading tool is driven both by a circular movement and a rotational movement on itself, this double movement being obtained by a planetary type gear of the kneading tool on a central gear. These two movements are therefore mechanically linked.

According to another aspect of the present invention, these two rotational movements must be independent for two reasons.

The first to adapt the speeds relating to the compositions and the successive stages of the mixture and to avoid the creation of wear areas of the tank. The second to put it in position relative to the brushing tool, as shown in FIG. figure 4 .

To obtain a good brushing of the tool 3, it must be in the opening 33 being parallel to the plane Z separating the two brushes 30; for this it must be rotatable about its axis Y, regardless of any rotation around the X axis.

As shown in figure 4 firstly, the tool 3 is presented so as to be parallel to the plane Z but slightly offset on the side, as shown in solid lines, then in a second step it is shifted so as to occupy a symmetrical position of the first, but on the other side of the Z plane, as shown in dotted lines.

Thus, each side of the branch of the tool 3 is rubbed by the brushes 30 in two ways: once by being driven into the mass of the brush and a second time by the end of the bristles of the brush, this which gives an excellent cleaning.
In general, to optimize its cleaning, the tool must be moved during this operation.

Moving parallel to itself can only be achieved by rotating a certain angle around X in conjunction with a rotation in the opposite direction around Y.

Of course, this can not be achieved with planetary gear drive means, or any other synchronized mechanical link.

Referring to the figure 5 it can be seen that the drive mechanism of the tool 3 consists of two coaxial tubes 50 and 51; the tube 50 rotates about the X axis being driven by a pulley 52, while the tube 51 rotates around the shaft 50 being driven by a pulley 53.

The tube 51 carries a pinion 54 which meshes with a pinion 55 which rotates about the axis Y and carries the shaft 56 of the tool 3.

The fact that the rotational speeds of the tool on itself and along the axis of the tank are independently and continuously adjustable during the mixing cycle makes it possible to adjust different mixing steps, especially in the case of adding fiber.

Claims (9)

1. A mixer of the type comprising a vat (12) in which is displaced a mixing implement (3) which is moved in a double movement, one being a circular movement about the axis (X) of the vat (12), and the other being a rotational movement on itself about its axis (Y), characterised by the fact that it comprises means effecting automatically, and separately after each mixing operation, cleaning of the vat (12) and of the mixing implement (3).
2. A device [sic] according to Claim 1, in which the two rotational movements of the implement are independent.
3. A mixer according to Claims 1 and 2, characterised by the fact that it comprises a first, fixed, frame (1) bearing the mixing implement (3) and its drive mechanism (2); a second, mobile, frame (10), pivotally bearing a vat (12) such that said vat (12) can occupy three positions relative to the mixing implement: an upper, working, position in which it is sealed hermetically by a cover (4) borne by the first frame (1); a second, lower, position in which it is separated from the implement and pivoted for emptying; and a third position in which it is pivoted facing automatic cleaning means and sealed.
4. A mixer according to Claims 1, 2 and 3, characterised by the fact that the implement-bearing frame (1) is mobile.
5. A mixer according to Claims 1, 2, 3 and 4, in which the automatic cleaning means comprise: a cover (20), borne by a carriage (22) such that it is able to hermetically seal the vat (12), said cover bearing in its centre a rotary spindle (26) which in turn bears a set of brushes (27) which conform to the shape of the inner wall of the vat (12), said cover (20) being provided with dust extraction means (29).
6. A device according to Claims 1 to 5, in which the device for cleaning the branches of the mixing implement (3) is formed by a mobile box structure (31) in which brushes (30) are placed, this box structure being mounted on a mobile carriage (32) so as to cause the mixing element to pass between the brushes (30).
7. A device according to Claims 1 to 6, in which the mixing implement (3) is moved within its cleaning box structure to facilitate the brushing operation.
8. A device according to any one of Claims 1 to 7, in which the speeds of rotation of the implement on itself and about the axis of the vat are adjustable independently and continuously during the mixing cycle according to the blending stages in particular in the event of fibres being added.
9. A device according to any one of Claims 1 to 7, in which the mechanism (2) for driving the mixing implement (3) is formed of two coaxial shafts (50, 51), one rotating about the axis (X) of the vat (12), the other rotating about the spindle (50) comprising a pinion (54) engaging on another pinion (55) rotating about the axis (Y) and bearing the shaft (56) of the mixing implement (3).

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