EP0759486A1 - Kneader-mixer, in particular for mastic asphalt - Google Patents

Abstract

The mixer comprises a stationary housing which has a cylindrical or semi-cylindrical wall (4) and flat ends (2,3) and which encloses a straight fixed blade (12) extending lengthwise about one third radially outwards from the housing axis (5) and two generally helical blades (13,14) rotating close to the cylindrical wall. Bearings on the housing ends hold blade (12) stationary and allow blades (13,14) to be rotated by an external drive. Each blade (13,14) is supported by radial arms (16,17) at its two ends, the arms (16,17) subtending 120 degrees between them. The helical blades (13,14) are located symmetrically about an axis (5) and about the mid-point (15) of the housing.

Description

The present invention relates to a kneading kneader, in particular for poured asphalts, that is to say hot mixes, between 200 ° C. and 250 ° C. approximately, of filler, of sand, of gravel, of ground natural asphaltic limestone. powder and refinery bitumen.

Such mixtures, made homogeneous by kneading, can then be poured hot to seal buildings, parking terraces and engineering structures, or to create traffic layers for road works such as sidewalks, pavements, etc ...

In the field of kneading mixers for mastic asphalts, kneaders with a generally horizontal axis are known at the present time, the tank comprises an axial shaft driven by an external motor and carrying a series of radial arms at the end of each of which is fixed. a pallet which can be slightly curved and more or less parallel to the shaft.

With such known kneaders, the mixing operation is slow: 2 to 3 hours for 500 kg and 5 to 8 hours for 10 t. In addition, when successively introducing the products to be mixed into the tank, in particular the natural asphalt powder, one notes the existence of beige streaks in the black mass, which remain visible for a very long time, thus showing that the mixture does not becomes homogeneous and presents the required quality only after a very long period of time. This obviously results in a very high energy consumption. In addition, in this type of kneader known, we often see forming a more or less large roll which wraps around the tree and which therefore has a negative impact on the homogeneity and the quality of the mixture and on the kneader's yield. .

The research which led to the invention has surprisingly shown that the abovementioned drawbacks can be remedied by means of a new design of the mixing tools, which at the same time makes it possible to reduce the mixing time by at least 20% at 30% and very quickly remove all the beige streaks, which is the sign of an excellent dispersion of the fine elements, and the rapid obtaining of a homogeneous mixture of the required quality. In addition, the new shape of the mixing tools allows energy savings of up to 50%, which is another completely unexpected result, while the phenomenon of sausage no longer appears, which is also surprising. and implies that the mixing efficiency is obtained from the start of the tank filling phase, which is obviously very important for the quality of the mixture. Finally, this new form of the tools makes it possible to increase the mixing speed in significant proportions without any risk of deformation or rupture of the tools, the tank or the rotary drive mechanism.

According to the invention, the kneading kneader, in particular for mastic asphalts, is of the type comprising a fixed heated tank, comprising two transverse plane or curved but preferably planar end walls connected by a fully or semi-cylindrical wall having an axis of longitudinal symmetry, and containing at least one fixed tool and an eccentric rotary tool respectively supported by the fixed and rotating parts of axial bearings associated with the end walls, one of said rotating parts being integral with a rotation drive means external to tank.

According to an essential characteristic of the invention, the fixed tool consists of a generally straight bar arranged in the vicinity of one third of the radius of the tank and the rotating tool consists of two generally helical bars, arranged symmetrically with respect to the center of the tank and near the cylindrical wall of the latter, each bar being mounted between two radial arms respectively close to the end walls and forming between them an angle of about 120 °.

• la barre constituant l'outil fixe est disposée dans un plan radial, présente une pente de 5° à 15° par rapport à l'axe de symétrie longitudinal et est reliée à l'un des paliers par un tronçon incliné à environ 45° et à l'autre palier par un tronçon en arc de cercle et un tronçon coudé ;
• la barre constituant l'outil fixe est conformée en U dont les deux branches rectilignes sont généralement parallèles à l'axe de symétrie longitudinal, le fond du U étant relié à l'un des paliers par une chaise de support et les extrémités respectives des deux branches rectilignes du U étant inclinées et fixées de part et d'autre d'une pièce de support axiale associée à l'autre palier ;
• la barre constituant l'outil fixe est creuse et les extrémités respectives des deux branches tubulaires du U sont raccordées à des conduits délimités par une cloison centrale de la pièce de support axiale et débouchant dans des gaines extérieures d'entrée et de sortie.

According to other characteristics of the invention:

• the bar constituting the stationary tool is arranged in a radial plane, has a slope of 5 ° to 15 ° relative to the longitudinal axis of symmetry and is connected to one of the bearings by a section inclined at approximately 45 ° and at the other bearing by a section in an arc of a circle and a bent section;
• the bar constituting the fixed tool is U-shaped, the two straight branches of which are generally parallel to the longitudinal axis of symmetry, the bottom of the U being connected to one of the bearings by a support chair and the respective ends of the two rectilinear branches of the U being inclined and fixed on either side of an axial support piece associated with the other bearing;
• the bar constituting the fixed tool is hollow and the respective ends of the two tubular branches of the U are connected to conduits delimited by a central partition of the axial support piece and opening into external inlet and outlet sheaths.

According to yet another characteristic of the invention, each helical bar carries a series of small equidistant longitudinal scrapers alternately interposed on the two bars, constituted by removable plates adjustable on scraper carriers integral with said bars, each radial arm carrying a large terminal scraper constituted by a long removable plate adjustable on a scraper holder integral with said arm.

According to another essential characteristic of the invention, the kneader is double and contains two sets of fixed and rotating tools mounted in series, the tank being entirely cylindrical and comprising a single external device for driving in rotation.

• un palier intermédiaire disposé à mi-longueur de la cuve et comportant une bague extérieure supportée par au moins trois bras radiaux dont les extrémités libres sont respectivement logées de façon réglable dans des pots solidaires de la paroi intérieure de la cuve,
• un dispositif d'accouplement disposé à mi-longueur de la cuve et comportant deux pièces qui sont respectivement solidaires des outils tournants, solidaires l'une de l'autre et logées dans un coussinet autolubrifiant en "Metafram" par exemple supporté par le palier intermédiaire, lesdites pièces entourant un coussinet autolubrifiant intérieur supportant les outils fixes.

According to still other characteristics of the invention, the double kneader comprises:

• an intermediate bearing disposed at mid-length of the tank and comprising an outer ring supported by at least three radial arms, the free ends of which are respectively housed in an adjustable manner in pots integral with the interior wall of the tank,
• a coupling device arranged at mid-length of the tank and comprising two parts which are respectively secured to the rotary tools, secured to each other and housed in a self-lubricating "Metafram" bearing, for example supported by the intermediate bearing, said parts surrounding an internal self-lubricating bearing supporting the stationary tools.

• la figure 1 représente une vue schématique partielle de dessus d'une première forme de réalisation du pétrin de malaxage selon l'invention ;
• la figure 2 représente une vue en coupe schématique partielle suivant la ligne axiale II-II de la figure 1 ;
• la figure 3 représente une vue en coupe brisée schématique partielle suivant la ligne III-III de la figure 1 ;
• la figure 4 représente une vue schématique partielle de dessus d'une deuxième forme de réalisation du pétrin de malaxage selon l'invention ;
• la figure 5 représente une vue en coupe schématique partielle suivant la ligne axiale V-V de la figure 4 ;
• la figure 6 représente un vue schématique avec coupes latérales partielles d'un pétrin double à deux ensembles d'outils en série ; et
• la figure 7 représente une vue schématique transversale partielle du palier intermédiaire pour pétrin double.

Other characteristics and advantages of the invention will emerge more clearly from the description which follows of several possible embodiments, made with reference to the appended drawings in which:

• FIG. 1 represents a partial schematic view from above of a first embodiment of the kneading kneader according to the invention;
• 2 shows a partial schematic sectional view along the axial line II-II of Figure 1;
• Figure 3 shows a partial schematic broken sectional view along line III-III of Figure 1;
• FIG. 4 represents a partial schematic view from above of a second embodiment of the kneading kneader according to the invention;
• 5 shows a partial schematic sectional view along the axial line VV of Figure 4;
• Figure 6 shows a schematic view with partial side sections of a double kneader with two sets of tools in series; and
• FIG. 7 represents a partial transverse schematic view of the intermediate bearing for double kneader.

In these drawings, the same references designate the same elements.

Referring to Figures 1 to 3, these illustrate a first embodiment of the invention applied to a small kneading kneader for mastic asphalts having a capacity of the order of 500 kg for example.

Such a kneading machine preferably comprises a heated tank 1 comprising two transverse end walls, preferably planar 2 and 3 connected at their lower part by a semi-cylindrical wall 4 having a longitudinal axis of symmetry 5 and at their upper part by two longitudinal walls forming with the terminal walls a rectangular upper assembly.

The tank is arranged at a fixed position on the ground or on a truck and contains at least one stationary tool and one rotary tool which are offset relative to the axis of symmetry 5 and which are respectively supported by the fixed walls 6, 7 and rotary 8, 9 of axial bearings 10, 11 associated with the end walls 2, 3. The rotary part 8 is made integral with a drive means in rotation not shown and external to the tank.

According to an essential feature of the invention, the stationary tool consists of a generally straight bar 12, which is arranged in the vicinity of one third of the radius of the semi-cylindrical tank 1, and the rotary tool consists of two bars generally helical 13, 14 which are arranged symmetrically with respect to a point 15 located on the axis of symmetry 5, approximately at the center of the tank, each helical bar being deduced from the other by a rotation of 180 ° around said central point 15 The two symmetrical bars 13, 14 are also arranged near the cylindrical wall 4 of the tank and are each mounted between two radial arms 16, 17 which are respectively close to the end walls 2, 3 and form an angle α between them. having for example a value of approximately 120 °.

More specifically, the bar 12 forming the stationary tool is arranged in a radial plane, for example the vertical radial plane passing through the axis of symmetry 5 of the tank, and has a slope of the order of 5 ° to 15 ° with respect to said axis 5. To be removable, the bar can comprise two elements 12a, 12b connected in a known manner by associated flanges 18 and 19, the element 12a being connected to the fixed part 6 of one of the bearings 10 by a section 20 inclined at about 45 ° for example, while the element 12b is connected to the fixed part 7 of the other bearing 11 by a section in an arc of a circle 21 and a bent section 22.

As a variant and with reference to FIGS. 4 and 5, the stationary tool can be in the form of a bar in U 23 generally parallel to the axis of symmetry 5 and preferably arranged in the vicinity of a third of the radius of the tank 1. The bottom 24 of the U is connected to the fixed part 6 of one of the bearings 10 via of a chair 25 or any other support means and the respective ends 26a, 26b of the two arms 27a, 27b of the U are inclined, for example at approximately 45 °, and rounded in an arc so that they can be fixed on either side of an axial support piece 28 associated with the fixed part 7 of the other bearing 11.

The straight bar 12 shown in Figures 1 and 2 and the U-shaped bar 23 shown in Figures 4 and 5 are intended to break the flow of material during mixing. The straight bar 12 like the U-shaped bar 23 can be solid or hollow. When these bars are hollow or tubular, they can be used to house the wires of temperature sensors, for example thermocouples, and carry several judiciously distributed temperature probes, thus making it possible to know the temperature at several points of the mixture and no longer only in facade as is currently the case.

In the particular case where the U-shaped bar 23 is hollow, it can also allow the circulation of a heat-transfer fluid contributing to the heating of the mixture to be kneaded in order to increase the efficiency of the heat exchange as will be explained in more detail below. -after.

Referring to Figures 4 and 5, the tubular ends 26a and 26b of the hollow U-shaped bar 23 are connected to the orifices 29a, 29b of the axial support piece 28, which is hollow and has a central partition 30 delimiting two conduits 31a and 31b opening respectively into external inlet and outlet sheaths, 32a and 32b. In addition, at least the rectilinear parts 27a and 27b of the U-shaped tube 23 can carry fins 33 for thermal diffusion, the general outline of which is shown very schematically.

During operation, the heat transfer fluid arrives through the inlet sheath 32a, enters the first compartment or conduit 31a of the axial support piece 28, then circulates successively in the inlet branch 27a, the bottom 24 and the outlet branch 27b of the U-shaped tube 23, to then pass into the second compartment or duct 31b of the piece 28, then in the outlet sheath 32b. When the kneading kneader is conventionally heated by burners whose burnt gases circulate in the double jacket of the tank, these burnt gases can advantageously be recycled in the circuit described above by entering through the inlet sheath 32a and by exiting through the outlet sheath 32b to be released to the atmosphere. This obviously results in a significant improvement in energy efficiency due to the fact that the mixture is also heated in its bulk and no longer only by heat exchange with the wall of the mixing tank.

Referring essentially to Figures 1 to 3, each generally helical bar 13, 14 preferably comprises a purely helical section 13a, 14a extended by a straight section 13b, 14b parallel to the cylindrical wall 4 of the tank. These two sections 13a, 13b and 14a, 14b of each bar 13, 14 together carry a series of small scrapers intended to act on the cylindrical wall 4 of the tank 1. All the small scrapers are preferably equidistant and inserted alternately on the two bars 13 and 14 so as to cover the entire cylindrical surface of the wall 4. These scrapers can be constituted by removable plates 34 mounted in an adjustable manner, for example by means of oblong holes, on scraper holders 35 which are made integral with said sections, for example by welding, so as to make a certain angle with the associated director of the cylindrical wall 4. The research which led to the invention has shown that an angle of approximately 35 ° is perfectly suitable for allow the scraped material to escape and return to the mass during mixing without requiring excessive force on the helical structure and / or the mechanism rotational drive, whose direction of work is obviously a function of the direction of gyration of the two constituent propellers.

As indicated above, the two generally helical bars 13 and 14 or the two assemblies comprising a purely helical section 13a or 14a extended by a straight section 13b or 14b are each mounted between two radial arms 16 and 17 which are respectively close to the end walls 2 and 3. These radial arms are respectively mounted on the rotating parts 8 and 9 of the axial bearings 10 and 11 and can have a generally cylindrical or slightly conical shape. However, they must each have a generator parallel to the end walls and arranged so as to be able to receive a large scraper intended to act on the associated end wall 2 or 3 of the tank 1. These large scrapers may each consist of a long removable plate 36 mounted in an adjustable manner, for example by means of oblong holes, on a scraper holder 37 made integral with the support arm 16 or 17, for example by welding. As before, each large scraper holder preferably makes a certain angle with the surface of the associated end wall 2 or 3. The research which led to the invention has shown that an angle of approximately 65 ° is perfectly acceptable for bringing the scraped material to be returned to the mass during kneading.

The removable plates 34 and 36 can be constituted by metal, by a ceramic, by polytetrafluoroethylene or even by metal brushes which, when the equipment must be explosion-proof, are advantageously made of brass.

Furthermore, each of the two bars 13, 14 and, more precisely, each of the two helical sections 13a and 14a may include a bar 38, which serves to stiffen the assembly and particularly improves the stirring effect and which is fixed on the bar or the associated section by means of at least two spacers 39 and, optionally, a bent end of the bar 40.

The two helical bars 13 and 14 can be constituted by a solid profile or a hollow tube having a circular, elliptical or oblong cross section, for example with two plane and parallel walls connected by semicircular end walls.

Referring to Figures 6 and 7, these illustrate an embodiment of the invention applied to a large kneading kneader for poured asphalts having a capacity of the order of 10 tonnes, for example.

In this case, the torsional forces in the tools become too great. The solution consisting in increasing their section leads to heavy, bulky tools which are difficult to install without enlarging the loading doors and to be driven in rotation due to their inertia. The only acceptable solution therefore consists in making a double kneader in which the two sets of tools are mounted in series, which makes it possible to use tools of reasonable size and relatively standard, without any particular assembly difficulty.

Of course, the realization of this assembly in series with a single external drive device in rotation implies the existence of an intermediate bearing 41 and a coupling device 42 arranged at mid-length of the tank.

The intermediate bearing 41 essentially comprises an outer ring 43 supported by three or four radial arms 44, the free ends of which are respectively housed in an adjustable manner in pots 45 integral with the entirely cylindrical inner wall 4 of the tank 1. The arms 44 are arranged so as to leave entirely free not only the spaces located directly above the loading doors (not shown) and also the bottom of the tank 1 in order to allow scraping of the latter from the drain valve (not shown) after the end of a mixing operation.

The inner face of the outer ring 43 has a concave rounded shape allowing it to cooperate in a movement of the ball joint with the convex rounded external face of an inner ring 46 in order to absorb the misalignments of the two sets of tools.

The parts 47 and 48 respectively support the two sets of rotary tools 13 and 14, are integral with one another to form the coupling device 42 and are themselves supported by a bearing 49 mounted inside of the inner ring 46. Another self-lubricating bearing 50 is mounted between the rotating external parts 47, 48 and the fixed internal parts 51 which are integral with the two fixed tools 12.

The outer ring 43 is preferably surrounded by a sheet metal joint cover in order to avoid filling the interstices between the parts 43, 47 and 48.

At the base of the rotary tools, it is also possible to fix other scraping devices by means of flanges 52 on which are fixed bent flat irons forming support arms 53 for scraping rollers 54. These rollers can be fitted either with brushes 55 arranged on the generators of the rollers, or with brushes arranged around the rollers in a helical path. These brushes can be substituted or added to the scraping devices previously described for a small kneading machine.

The present invention has been described with reference to a kneading kneader, in particular for mastic asphalts, but it is also applicable to any other bituminous mixture, to any non-bituminous mixture comprising a certain proportion of mineral aggregates, such as resin concretes by example, or to any mixture of the chemical or food industry comprising a certain proportion of granular ingredients as well as one or more ingredients acting as a binder so that after kneading, the mixture is present under the shape of a homogeneous dough, the kneader being heated or not and being able even to be cooled according to needs.

It is understood that the present invention has been described and shown for explanatory purposes but in no way limitative and that any useful modification may be made to it, in particular in the field of technical equivalences, without going beyond its ambit.

Claims (10)

Mixing kneader, in particular for poured asphalt, of the type comprising a fixed heated tank (1), comprising two preferably flat transverse end walls (2,3) connected by a fully or semi-cylindrical wall (4) having an axis of symmetry longitudinal (5), and containing at least one fixed tool and an eccentric rotating tool respectively supported by the fixed (6, 7) and rotating (8, 9) parts of axial bearings (10, 11) associated with the end walls, the one of said rotating parts being integral with a drive means in rotation external to the tank, characterized in that the fixed tool is constituted by a generally straight bar (12) disposed in the vicinity of one third of the radius of the tank ( 1) and that the rotating tool is constituted by two bars (13, 14) generally helical, arranged symmetrically with respect to the center (15) of the tank and near the cylindrical wall (4) of the latter, each ba rre being mounted between two radial arms (16, 17) respectively close to the end walls (2, 3) and forming between them an angle (α) of approximately 120 °. Mixing kneader according to claim 1, characterized in that the bar (12) constituting the fixed tool is arranged in a radial plane, has a slope of 5 ° to 15 ° relative to the longitudinal axis of symmetry (5 ) and is connected to one of the bearings (10) by a section (20) inclined at approximately 45 ° and to the other bearing (11) by a section (21) in an arc and a bent section (22) . Mixing kneader according to claim 1, characterized in that the bar (23) constituting the fixed tool is U-shaped, the two rectilinear branches (27a, 27b) are generally parallel to the longitudinal axis of symmetry (5) , the bottom (24) of the U being connected to one of the bearings (10) by a support chair (25) and the respective ends (26a, 26b) of the two rectilinear branches (27a, 27b) of the U being inclined and fixed on either side of an axial support piece (28) associated with the other bearing (11). Mixing kneader according to one of claims 2 or 3, characterized in that the bar (12, 23) constituting the fixed tool is hollow. Mixing kneader according to claim 4, characterized in that the respective ends (26a, 26b) of the two tubular branches (27a, 27b) of the U are connected to conduits (31a, 31b), delimited by a central partition (30 ) of the axial support piece (28) and opening into external inlet and outlet sheaths (32a, 32b). Mixing kneader according to any one of Claims 1 to 5, characterized in that each helical bar (13, 14) carries a series of small equidistant longitudinal scrapers inserted alternately on the two bars, constituted by removable plates (34 ) adjustable on scraper carriers (35) integral with said bars, each radial arm (16, 17) carrying a large terminal scraper constituted by a long removable plate (36) adjustable on a scraper carrier (37) integral with said arm. Mixing kneader according to any one of Claims 1 to 6, characterized in that each helical bar (13, 14) comprises a counterbar (38) fixed by at least two spacers (39). Mixing kneader according to any one of Claims 1 to 7, characterized in that it is double and contains two sets of fixed (12) and rotary (13, 14) tools mounted in series, the tank (1) being entirely cylindrical and comprising a single external rotary drive device. Mixing kneader according to claim 8, characterized in that it comprises an intermediate bearing (41) disposed mid-length of the tank (1) and comprising an outer ring (43) supported by at least three radial arms (44 ) whose free ends are respectively housed in an adjustable manner in pots (45) integral with the inner wall (4) of the tank. Mixing kneader according to one of claims 8 or 9, characterized in that it comprises a coupling device (42) disposed at mid-length of the tank (1) and comprising two parts (47, 48) which are respectively secured to the rotating tools (13, 14), secured to each other and housed in a bearing (49) supported by the intermediate bearing (41), said parts surrounding an inner bearing (50) supporting the stationary tools (12).

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