FR1464849A

FR1464849A - Pneumatic roller compactor

Info

Publication number: FR1464849A
Application number: FR39718A
Authority: FR
Original assignee: ENTPR GAETAN BRUN
Current assignee: ENTPR GAETAN BRUN
Priority date: 1965-11-25
Filing date: 1965-11-25
Publication date: 1967-01-06

Description

Rouleau compacteur pneumatique.
Depuis l'introduction en France de la technique de fabrication et mise en oeuvre d'enrobés à chaud, l'engin de compactage des revêtements utilisant cette technique a été le rouleau compacteur à cylindre métallique lisse.
Or, à l'exception de leur aptitude à lisser les surfaces de tels revêtements, les rouleaux à jantes lisses manquent, pratiquement, de toutes les qualités requises pour assurer un bon compactage.
En effet, pour obtenir une bonne mise en place des matériaux enrobés, il est indispensable que les agrégats de toute la surface du revêtement se déplacent les uns par rapport aux autres; or le cylindre métallique lisse s'appuie uniquement sur les points hauts, ce qui entraîne obligatoirement un écrasement de matériaux sur ces points hauts et, par contre, un manque de compactage dans les points bas.
Par ailleurs, le cylindrage à l'aide de jantes lisses nécessite la mise en place d'une quantité importante d'eau sur la surface des jantes, pour éviter le collage des matériaux enrobés au cylindre.
Ce processus introduit de l'eau dans le matériau enrobé, lors de sa mise en u̇vre, alors que cette dernière a été éliminée à grand frais lors de la fabrication dans un four sécheur; cette présence d'eau est un facteur de désenrobage et de mauvaise tenue du revêtement; par ailleurs, le refroidissement obtenu 'artificiellement s'oppose à l'obtention d'une forte densité du matériau.
Pour être exécuté de façon rationnelle, le compactage nécessite un engin assurant une pression égale sur toute la surface, et capable à cet effet d'épouser les déformations des matériaux compactés. Le cylindre à jantes lisses ne permet évidemment pas d'obtenir ce résultat, les pressions qu'il détermine étant très variables d'un point à un autre.
Tout au contraire, le rouleau compacteur à cylindre pneumatique permet une variation contrôlée de charge et de pression, et il assure une action constante et uniforme; c'est donc un engin beaucoup mieux adapté à la mise en u̇vre des matériaux enrobés.
La plus importante difficulté rencontrée à ce jour pour obtenir un compactage satisfaisant avec un cylindre pneumatique était le collage des matériaux enrobés aux pneus du compacteur; pour éviter ce grave inconvénient, il fallait cylindrer l'enrobé quand il était suffisamment refroidi, ce qui conduisait à une médiocre compacité.
C'est ainsi que, sur de nombreux chantiers d'application d'enrobés, l'atelier de compactage doit comprendre des cylindres métalliques lisses et tandem, suivant le matériel de répandage, puis des cylindres à pneus compactant les enrobés à température basse.
Cette utilisation de matériel à jantes lisses et pneumatique ne résoud pas les impératifs de la technique qui recherchent une compacité élevée des matériaux enrobés.
Le cylindre à pneus intervient en effet trop tard pour avoir une action efficace, car son passage ne peut s'effectuer qu'après un délai assez long, pour permettre le refroidissement des enrobés, jusqu'ici seul capable d'éviter leur collage aux pneumatiques.
Or on a trouvé, suivant la présente invention, qu'il était possible d'éviter ces inconvénients en utilisant un rouleau compacteur pneumatique caractérisé en ce qu'il comporte des moyens de chauffage des pneus permettant de porter leur température à un degré tel que les enrobés ne collentPneumatic roller compactor.
Since the introduction in France of the technique of manufacturing and implementing hot mixes, the coating compacting machine using this technique has been the compactor roller with a smooth metal cylinder.
However, with the exception of their ability to smooth the surfaces of such coatings, rollers with smooth rims lack practically all the qualities required to ensure good compaction.
In fact, in order to obtain good placement of the coated materials, it is essential that the aggregates of the entire surface of the coating move with respect to each other; however, the smooth metal cylinder is based only on the high points, which necessarily leads to a crushing of materials on these high points and, on the other hand, a lack of compaction in the low points.
Furthermore, rolling using smooth rims requires placing a large quantity of water on the surface of the rims, to prevent sticking of the coated materials to the cylinder.
This process introduces water into the coated material, during its implementation, while the latter was removed at great expense during manufacture in a drying oven; this presence of water is a factor in the stripping and poor performance of the coating; moreover, the cooling obtained artificially opposes obtaining a high density of the material.
To be carried out rationally, compaction requires a machine ensuring equal pressure over the entire surface, and capable for this purpose of conforming to the deformations of the compacted materials. The smooth rim cylinder obviously does not make it possible to obtain this result, the pressures that it determines being very variable from one point to another.
On the contrary, the roller compactor with pneumatic cylinder allows a controlled variation of load and pressure, and it ensures a constant and uniform action; it is therefore a machine much better suited to the implementation of coated materials.
The most important difficulty encountered to date in obtaining satisfactory compaction with a pneumatic cylinder was the sticking of the coated materials to the tires of the compactor; to avoid this serious drawback, it was necessary to roll the asphalt when it was sufficiently cooled, which led to poor compactness.
Thus, on many asphalt application sites, the compaction workshop must include smooth and tandem metal cylinders, depending on the spreading equipment, then pneumatic cylinders compacting the asphalt at low temperature.
This use of material with smooth and pneumatic rims does not solve the technical requirements which seek high compactness of coated materials.
The tire cylinder intervenes too late to have an effective action, because its passage can only take place after a long enough time, to allow the cooling of the asphalt, until now the only one capable of preventing them from sticking to the tires. .
However, it has been found, according to the present invention, that it was possible to avoid these drawbacks by using a pneumatic compactor roller characterized in that it comprises means for heating the tires making it possible to bring their temperature to a degree such that the tires asphalt do not stick

Claims

not on them without however that this temperature evening prejudicial to their good behavior. It has in fact been observed that by limiting the temperature difference between the materials and the surface of the tires, the adhesion of the asphalt to the tires is avoided. Thus, in particular, it is possible to produce pneumatic compactors whose tires are heated by heat diffusing panels; pneumatic cylinders thus equipped, which prevent the asphalt from sticking without having to be sprayed with water, have given excellent results. The accompanying drawing shows by way of example an embodiment of the present invention. Figure 1 is a general schematic view; Figure 2 is a rear view, on a larger scale, of a set of tires; Figure 3 is a side view of one of the tires with its heater. The pneumatic compactor shown schematically in FIG. 1 comprises a train of four tires 1 and a train of three tires 2, the tracks of which overlap; a source of pressurized gas 3 supplied by a pressure reducing valve 4 and the pipes 5 of the burners 6 which heat the heat diffuser panels 7 arranged opposite each of the tires of the two trains 1 and 2. Each diffuser panel is mounted in a housing 8, inside which is arranged the corresponding burner connected to the rail 9 of the general gas supply pipe 5 by a flexible pipe 10 with the interposition of a control valve 11; the orientation of the diffuser can be adjusted by rotating the housing 8 around the axis 12, for this purpose using the control arm 13, after loosening a nut; its distance from the tire can also be adjusted by sliding the piston 14, integral with the frame 15, in the cylinder 16. It was assumed that all the diffusers of the set of tires were mounted on a common frame 15, but it could well be intended to provide a special frame for each diffuser; one could also provide a single diffuser for all the tires of the same train; the radiant panel (s) 8 are protected by a casing

17 whose function is to avoid significant heat loss by radiation and by the action of the wind. The temperature of the tires depends on the one hand on the distance of the tires from the panels, and on the other hand, on the amount of energy used in the panels. There are therefore two adjustment possibilities:

1. Distance and orientation of the panel from the tires;

2. Adjustment of the energy flow by a servo control placed in the driver's cab, or near the heating panel. In addition, a control system slaved to the gearbox-clutch assembly automatically stops heating the panels when the roller remains stationary beyond a determined time. The panels are re-ignited automatically when restarting by means of a pilot light or electrical contact system. Tire temperature monitoring and control can be obtained: a. By thermometric probe measuring the temperature under the radiant panel; b. By measuring tire pressure; vs. By the two systems used simultaneously. The starting and stopping of these systems can be slaved to the previous physical data measuring devices. This control can also be a function of the temperature of the mixes during the implementation, of the ambient temperature, and adjusted accordingly by special device. It is understood that the embodiment of the invention which has been described above with reference to the appended drawing has been given purely as an indication and in no way limiting and that numerous modifications can be made without deviating from for this within the scope of the present invention; it is thus in particular that the heating of the tires can be obtained by an electric resistance embedded in the tread of the tire itself and the commissioning of which is ensured by rotating joints, mounted on the rims supporting the tires. ; it is also possible to use induction heating, the tire in this case having a metal carcass; these two devices can be adjusted and controlled under the same conditions as the devices described above. ABSTRACT

1. This pneumatic roller compactor is characterized in that it comprises means for heating the tires making it possible to bring their temperature to a degree such that the coated materials do not stick to them without however this temperature being detrimental to their good performance;

2. The heating of the tires is obtained by radiant panels;

3. These panels are heated by burners;

4. The distance between these panels and the tires as well as their orientation are adjustable;

5. The panels are protected by housings;

6. Control systems maintain the temperature of the tires at the desired degree;

7. The switching on and off of the heating is automatically controlled by switching on and off the compactor roller;

3. The tires are heated by resistors embedded in the mass;

9. They are heated by induced currents.