EP1071521B1 - Method and device for smoothing a deposit of divided solid materials - Google Patents

Abstract

Powders or granules are deposited on a film (10) or on a band (100) by means of several rollers (1,2,3,4) which are driven at a constant speed by a conveyor (5). There are several vacuum tables (20,21,22) which are given an alternate oscillatory movement of low amplitude. The support is tensioned in its movement direction.

Description

Subject of the invention

The present invention relates to both a method and a device which make it possible to smooth, that is to say to level, products made from divided solid materials such as pulverulent products, powders or granules, and in the form of regular or irregular "heaps" deposited on a mobile support.

Technological background

Many industries are faced with the problem of smoothing powdered products deposited on a support which is mobile. In particular, we could cite the cement industry, the baking industry, etc.

More particularly in the field of floor covering, this type of problem appears during the deposition of a solid material divided as a powder on a support for the production of decorations.

More specifically, in this area of synthetic flooring, an important category is represented by coverings formed in the form of a relatively thick sheet made of a material synthetic, and whose decor is built in the mass. The main characteristic of this type of product must be the absence of variation of the decoration according to wear. These products are in practice intended to be used in premises with heavy traffic.

Several methods for producing such products have been proposed. Among these, there may be mentioned the technique of rolling or calendering solid or pasty materials in order to produce a solid decoration. However, according to this manufacturing method, it is observed that the decorations obtained by this technique have a preferred orientation in the direction of advance of the product on the production line.

In order to limit this orientation effect, it has been proposed to use a manufacturing process comprising several successive rolling mills and arranged perpendicularly to each other in order to reduce this problem of orientation preferred during the creation of the decoration.

Other work has been carried out on improved methods of inlaying granules or pieces of material between two rolling mills to obtain granite designs. Coating of grains has also been proposed, which makes it possible to obtain very fine and particularly well defined color transitions.

New techniques have also been proposed which aim to dispense with the use of a rolling mill. For this purpose, it has been proposed to use chips or particles embedded in a binder which is coated on a support. According to another method, a bed of chips is deposited and the binder is then deposited on the decoration consisting of the chips.

All of these techniques aim to form an attractive decor while limiting the orientation drawbacks due to the direction of manufacture.

The Applicant has in particular developed a process for producing a decoration using localized deposits of solid particles or powders carried out using rotary frames. This process is particularly well described in patent applications FR-A-2542260 and FR-A-2548093.

• granulométrie des particules
• dimension des mailles du cadre rotatif
• ouverture des lèvres du distributeur
• qualité d'écoulement du solide
• vitesse de rotation du cadre et d'avancement du produit

Within the framework of the process described above, it was possible to develop different ranges of products by playing on the quantities of powder deposited by gravity by acting on the following parameters:

• particle size
• mesh size of the rotating frame
• dispenser lips open
• solid flow quality
• frame rotation speed and product advancement

It was thus possible to obtain a decoration in the thickness of the product which may have a depth effect by modifying the translucency of the powders used. These methods are well suited for making imitations of natural stones, for example with a marbled effect. However, it has also been observed that problems can arise in obtaining a smooth surface from several successive powder deposits. Due to the inherent principle of the flow of powders, it is observed that they will deposit in the form of small heaps thus maintaining a certain relief in the decor.

It has been proposed inter alia to compress, in particular vertically, these deposits, but we observe in in this case vertical compaction and very low lateral creep.

The leveling of products of this type on a flexible movable support which in principle runs at constant speed is traditionally carried out by rolling, either at the outlet of a hopper maintained constantly in charge of products, or by a scraper blade or a rotating cylinder. . This technique does not make it possible to produce a regular layer without relief, the scraping of the grains of powder or of the granules creating zones not covered with product in the case of a thin layer or lineage phenomena in the case of a thick layer .

Aims of the invention

The present invention aims to avoid the drawbacks of conventional smoothing techniques when depositing products in the form of a divided solid. More particularly, the present invention aims to propose a process for smoothing the materials listed above deposited in the form of small regular or irregular heaps on a support moving in principle at constant speed in order to obtain a more uniform, smoother and upgraded.

The main aim sought is to obtain on the support a layer which can be both thin and thick but which must necessarily be regular, uniform and free of relief, starting from a homogeneous or heterogeneous mixture of products deposited in the form of regular or irregular heaps, these products being in a solid and divided state. These products may be of the same or different nature, texture and particle size.

In addition to regularity, uniformity and the absence of relief, it is also sought to reduce the drawbacks due to the phenomenon of preferred orientation, both in the direction of the advance of the product and perpendicular thereto.

An additional aim of the present invention is to propose a method and a device which make it possible to avoid excessive deformation of the final decoration obtained by the deposition of the materials in the form of a heap.

Description of the main characteristic elements of the invention

A first object of the present invention aims to propose a process for smoothing divided solid materials such as pulverulent products, powders or granules, deposited in the form of small regular or irregular heaps on an essentially horizontal support movable in the direction of the 'advance (and which corresponds to the direction of scrolling).

This horizontal support can be a film or directly the conveyor belt on which the deposition of the divided solid materials is carried out.

A first essential characteristic of this process lies in the fact that said essentially horizontal support on which the materials are deposited in the form of small heaps is driven by an alternating oscillatory movement, said movement being applied uniformly over the entire width of said support.

Preferably, according to a first embodiment, the direction of the alternating oscillatory movement is transverse with respect to the direction of advance, that is to say that the movement will take place perpendicularly to the movement of the support and this in the essentially horizontal plane of the support.

According to a second embodiment, this direction is parallel to the direction of advance, the alternating oscillatory movement being carried out longitudinally with respect to the movement of the support and this also in the essentially horizontal plane of the support.

According to a third embodiment, the direction is perpendicular to the plane of the support. This means that the movement will take place vertically with respect to the support, which is itself essentially horizontal.

According to other embodiments, it is also possible to envisage alternative oscillatory movements being a combination of the various embodiments mentioned above. For example, the movement can be performed obliquely or diagonally or even even in circular form.

According to a second important characteristic of the present invention, the support, that is to say the film or the conveyor belt, is tensioned or is prestressed in its elasticity zone. This tensioning or prestressing must above all be carried out in the direction of advance. This means that consideration is given to carrying out the tensioning or prestressing of the support longitudinally.

According to an advantageously complementary characteristic, and in particular according to the first and second embodiments, it is also proposed to prevent the support from undergoing a flapping outside the zone of implementation of the method, that is to say the upstream area and downstream of the area where smoothing is carried out using the device generating the alternating oscillatory movement. According to the first and second embodiments described above, and in which the oscillating reciprocating movement and the tensioning in the plane of the support are carried out, it is advisable to prevent the support from being subjected to a perpendicular movement. horizontally.

A second object of the present invention is to provide a device for smoothing divided solid materials such as pulverulent products, powders or granules, deposited in the form of regular or irregular heaps on an essentially horizontal support and moving in the direction of 'advanced. This device comprises a conveyor belt which can be directly the above-mentioned horizontal support or which can serve as a means of transport to said horizontal support constituted by a film on which the deposition is carried out.

According to a first important characteristic, the device is provided with means allowing an alternating oscillatory movement of the support. These means can for example comprise a table on which the conveyor belt or even the film moves and which performs the required oscillatory reciprocating movement controlled for example by a connecting rod - crank system. In addition, it should be noted that the means must be provided so that the movement is applied uniformly over the entire width of the support.

According to another important characteristic of the present invention, the device comprises the necessary means for tensioning or prestressing the horizontal support in its zone of elasticity preferably in the direction of travel. This means that the tensioning takes place essentially longitudinally. In this case, it suffices to propose a device for driving said support which makes it possible to drive the latter at a speed slightly lower upstream relative to the speed of travel downstream.

According to an advantageously complementary characteristic, the device also comprises means which make it possible to avoid any flapping of the support outside the implementation zone in order to prevent the transmission of the alternating oscillatory movement upstream and downstream.

"Reciprocating oscillatory movement" means a movement which takes place by returning to the starting point. It is not a vibratory movement which is a movement generated by a succession of shocks.

A final object of the present invention relates to the product obtained by the process or the device according to the invention, having a design, possibly geometric, almost identical to the initial design and obtained from divided solid materials, and having little or no relief.

Brief description of the figures

Figure 1

shows a perspective view of a device for implementing a smoothing process for powdery products according to the present invention in the case of deposition on a film.

Figure 2

shows a side sectional view of the device shown in Figure 1.

Figure 3

shows a sectional view from above of the device shown in Figure 1.

Figure 4

shows a view in longitudinal section along the axis III-III of the device shown in Figure 1.

Figure 5

shows a perspective view of the device for implementing a smoothing process for powdery products in the case of deposition directly on the conveyor belt.

Figure 6

shows a side sectional view of the device shown in Figure 5.

Description of several preferred embodiments of the invention

Figures 1, 2, 3 and 4 relate to a device for smoothing divided solid materials deposited on a film, while Figures 5 and 6 relate to a device for smoothing powdery materials directly deposited on the conveyor belt.

In the description which follows, the term "film" is used as opposed to the term "strip" to indicate that the support is a self-supporting film (10) on which the pulverulent materials are deposited while the strip (100) is directly the conveyor belt on which the powdery materials are deposited.

In either case, the film or the strip constitutes an essentially horizontal support integrated into the production line which circulates in the direction of advance necessarily at a speed in principle constant defined by the production speed of the line.

As shown in Figures 1 to 6, the divided solids are deposited using one or more distributor (s) (1, 2, 3 and 4) on a film (10) or on a strip (100 ) which are driven at a constant speed by a conveyor (5) in the running direction represented by the unidirectional arrow.

More specifically, in the embodiment shown in Figures 1 to 4, the device is equipped with several vacuum tables, and more specifically three vacuum tables (21, 22 and 23). According to the embodiment shown in Figures 5 and 6, a single vacuum table (22) is proposed. This table or the central table (22) is provided with a device (6) which makes it possible to perform an alternating oscillatory movement, preferably of small amplitude. The frequency of the oscillatory movement is preferably adjustable and can be between 5 and 500 Hz depending on the nature of the deposit, but also according to the direction in which this alternating oscillatory movement will take place.

The choice of the frequency and the amplitude, by the dynamic movements which they cause, allows the spreading out of the materials of the pile so that each particle or grain comes to be placed in relation to the others in the surface areas of the support. less abundance.

According to the two embodiments shown in Figures 1 to 6, this movement is carried out in the horizontal plane and transversely to the direction of travel of the support (10 or 100).

This oscillatory movement is carried out conventionally using a connecting rod - crank system shown in more detail in FIG. 4. An eccentric (60) transmits the movement to a connecting rod (61), itself connected to a shaft (62) via a socket (63). This shaft is fixed by two of its ends (64 and 65) directly to the central vacuum table (22). The eccentric (60) thus makes it possible to impart an alternating oscillatory movement to said table, which transmits it uniformly to the support (10 or 100).

It is understood that according to other embodiments, a movement in other directions can be printed on the support.

According to another important characteristic of the present invention, the horizontal support consisting either of the film (10) as shown in FIG. 1, or of the strip (100) as shown in FIG. 5, is kept under tension. Several possibilities for carrying out this tensioning of the support can be envisaged. According to a first preferred embodiment, it suffices to provide a rotation speed of the cylinder (51) located downstream of the conveyor belt (5) slightly greater than the production speed. According to another embodiment, it suffices to provide a speed of rotation of the cylinder (52) located upstream of the conveyor belt (5) slightly lower than the production speed. In these two cases, the support, which must be an elastic support, will be tensioned in its elasticity zone.

In addition, in order to avoid any vertical displacement of the movable horizontal support (10 or 100), it is necessary to provide means which hold the horizontal support. By way of example, and in particular as shown in the various figures, it has been proposed to use tables (31 and 32) fixed and adjustable in height in order to maintain the support. horizontal movable (10 or 100) in a relatively coplanar position.

Advantageously, under the effect of the alternating oscillatory movement of the central table (22), the various heaps of powder collapse and are leveled without significant modification of the decoration. The support then has a regular, uniform and uneven layer of powder. This layer is then agglomerated and fixed to the support by means known per se such as ovens or IR tunnels (70).

Then, the product obtained is cooled, signed and wound up according to the embodiment shown in Figures 1, 2, 3 and 4 while it can optionally be transmitted on another support according to the embodiment shown in Figures 5 and 6.

Claims (12)

1. Method for smoothing divided solid materials such as pulverulent products, powders or granules, deposited in the form of regular or irregular heaps on a support which is essentially horizontal and able to move in the feed direction, characterised in that :

   - said essentially horizontal support (10 or 100) is driven by an oscillatory reciprocating movement, said movement being applied uniformly to the entire width of said support, and in that

   - the support is tensioned or is prestressed essentially in the feed direction.
2. Method according to claim 1, characterised in that the support is tensioned or prestressed in its elastic range.
3. Method according to claim 1 or 2, characterised in that the oscillatory reciprocating movement is carried out in a transverse direction with respect to the feed direction.
4. Method according to claim 1 or 2, characterised in that the oscillatory reciprocating movement is carried out in a parallel direction with respect to the feed direction.
5. Method according to claim 1 or 2, characterised in that the oscillatory reciprocating movement is carried out in an orthogonal direction with respect to the horizontal support.
6. Method according to any one of the preceding claims, characterised in that the support is prevented from oscillating outside of the operating area.
7. Method according to any one of the preceding claims, characterised in that the essentially horizontal support is either a film on which the divided solid materials are deposited, either directly the conveyor belt on which the divided solid materials are deposited.
8. Device for smoothing divided solid materials such as pulverulent products, powders or granules, deposited in the form of regular or irregular heaps on an essentially horizontal support (10) moving in the feed direction, characterised in that said device comprises means (21, 22, 23) for imparting an oscillatory reciprocating movement of the support as well as means (51, 52) for tensioning or prestressing said support.
9. Device according to claim 8, characterised in that the means (21, 22, 23) for imparting an oscillatory reciprocating movement comprise a table on which the support (10) moves and which imparts the oscillatory reciprocating movement controlled by a slider crank mechanism (60, 61).
10. Device according to claim 8 or 9, characterised in that the means for tensioning or prestressing the support are carried out with a device for driving (52) said support, which allows said support to be driven at a speed which is slightly lower upstream than it is downstream.
11. Device according to any one of the claims 8 to 10, characterised in that it comprises means (31, 32) for preventing any vertical movement.
12. Product obtained by the method according to any one of the claims 1 to 7 or by the device according to any one of the claims 8 to 11, characterised in that it has a possibly geometric pattern which is nearly identical to the initial pattern and obtained from divided solid materials, and showing no or little relief.