The present invention relates to a machine for dusting a particulate matter on a profiled roofing sheet having raised patterns. It allows a homogeneous distribution, i.e. of constant thickness, of the particulate matter, herein solid particles, across the surface of the sheet despite the presence of raised elements thereon. It has industrial applications in the field of the manufacturing of cover elements, in particular corrugated sheets made of cellulosic fibres impregnated with bitumen.
To provide the corrugated roofing sheets with particular properties, it is sometimes necessary to deposit on the surface of these latter, in quantities identical in any point, solid particles such as flakes or granules, such matters being herein generically called “particulate matters”.
For evident reasons linked to the geometry, the film of solid particles obtained after conventional gravity coating through a dry process is not of constant thickness and depends directly on the geometric profile of the sheet. This gravity coating is conventionally performed with a hopper discharging the particulate matter as a linear curtain on the surface of the sheet.
In addition to the “Geometry” effect, another effect is added up, which is called herein the “Gravity” effect, linked to the sliding of the solid particles on the inclined plans, in particular the sides/sloping parts of the corrugations, where the coefficient of friction is lower than the force of gravity.
It is hence desirable to find a solution in order to make the distribution of the solid particles on the surface of the corrugated profile the most homogeneous possible, and that for any element of surface. Several means can be contemplated to achieve this objective. For example, the implementation of air blowing systems for displacing the excess of matter in the profile valleys towards the corrugation sloping parts/sides or the use of a profiled doctor blade in order to modify the concentration of the curtain of solid particles at the beginning of the application and corresponding to the needs.
However, in the particular case of a corrugated cover sheet, these two techniques, known from the one skilled in the art, generate cumbersome dysfunctions as for example a sliding of the particles, an air blowing difficult to adjust between an excess and a deficiency, a doctor blade that is badly adapted to lamellar particles.
It is hence proposed another solution, which is based on the use of deflectors disturbing the flow of solid particles falling in free fall on the sheet, also called a curtain of particles/particular matter, so as to better distribute these particles across the sheet surface taking into account the two above-mentioned effects, i.e. the “Geometry” effect and the “Gravity” effect.
Moreover, the document US-2002/0114871A1 is known, which relates to the dusting of food crisps by spices. Vibrating fingers forming vibrating chimneys distribute the spices on the crisps. However, the impact of the corrugations of the crisps on the final distribution across the surface of the crisps is not taken into account.
The document U.S. Pat. No. 3,184,324 discloses a device for spreading granules across a flat cover element. The granules fall in bands in particular areas and are guided in their fall by guides. The cover element is flat and the guides cause naturally an accumulation of granules at the limit of the bands of granules formed on the surface of the element.
The invention thus relates to a machine for dusting a shape with a particulate matter, said shape being a profiled roofing sheet having raised patterns extended in the direction of the length thereof, said raised patterns having elevated parts laterally separated from trough parts by inclined sloping parts, said sheet having a determined width, the machine including a dusting means forming a linear curtain of particulate matter falling transversally, across the width of the sheet, and driving means for a relative translational displacement of the sheet with respect to the curtain of particulate matter.
According to the invention, deflectors of the curtain of particulate matter are arranged above the bottom areas of the inclined sloping parts of the sheet so as to transversally divert the direction of the vertical flow of parts of the curtain of particulate matter above said bottom areas of the inclined sloping parts to redistribute the diverted particular matter towards an intermediate level of each corresponding inclined sloping part so that the quantity of particulate matter at the surface of said sheet is finally substantially homogeneous after sliding towards the bottom of said inclined sloping part of a part of the particulate matter that had been diverted.
Hence, the homogeneous final distribution of the particulate matter on the corrugated surface of the cover sheet is obtained by the principle that consists in intercepting the particulate matter that falls in a curtain towards the sheet, in the parts of the curtain opposite/above the bottom parts of sloping parts to laterally/transversally redistribute it at an intermediate height of the corresponding sloping part, a part of the redistributed particulate matter ending up sliding along the sloping part to equalize the distribution at the surface of the sheet.
In various embodiments of the invention, the following means, which can be used alone or in any technically possible combination, are used:
The invention also relates to the method that makes it possible to obtain a homogeneous distribution of particular matter across the surface of a roofing sheet having raised patterns by means of deflectors and according to all the implementation modes. In particular, the direction of the vertical flow of the parts of the curtain of particulate matter above the bottom areas of the inclined sloping parts is transversely diverted, by means of deflectors, to redistribute the diverted particulate matter towards an intermediate level of each corresponding inclined sloping part so that the quantity of particulate matter at the surface of said sheet is finally substantially homogeneous after sliding towards the bottom of said inclined sloping part of a part of the particular matter that had been diverted.
The present invention will now be exemplified, without being limited thereby, by the following description of embodiments and implementations in relation with:
The invention hence permits to make uniform the distribution of particulate matter, for example a fire-protection particulate coating, on the surface of a corrugated cover sheet 1, 1′, in particular a sheet of cellulose impregnated with bitumen, during an operation of dusting of the sheet with a linear particulate curtain 3 making it possible to linearly deposit the particulate matter on the sheet. During this operation, the sheet moves perpendicularly to the particulate curtain 3, this latter being preferably extended across the width of the sheet and the sheet moving according to its length under the curtain of particulate matter.
The sheet has raised patterns extended in the direction of the length thereof, said raised patterns having elevated parts separated laterally from trough parts by sloping parts inclined from the top to the bottom and laterally. Each elevated part hence forms a convex shape towards the top and the two lateral inclined sloping parts on each side of the elevated part are downwardly divergent.
To make the distribution of the particulate matter 2 on the sheet 1, 1′ uniform, a deflector 4, 4′ is installed above and opposite (in other word right above) the lower area or bottom part of each sheet sloping part. An example of implementation is illustrated by
We specify herein the double function “interception/deflection” because it is understood that the deflection occurs only because there is also interception of the flow of particulate matter of the curtain 3.
It will be seen that, for a sheet with corrugations alternated with a flats 1′, each deflector includes only an upper face of interception/deflection 5a′ or 5b′.
The equalization of the distribution of the particulate matter 2 on the sheet 1 can be optimized by acting on several parameters. Among these parameters, it can be mentioned:
The number of deflectors is linked to the geometrical profile of the corrugated sheet and, more specially, to the number of corrugations, and hence of sloping parts, given that there must be an upper face of interception/deflection opposite/above each bottom area of the sloping part if it is wanted to finally obtain a uniform distribution over the whole width of the sheet surface. This parameter is hence relatively constrained.
Hence, in
It is understood that the shape of the upper face(s) of interception/deflection 5a-5b, 5a′ or 5b′ may be optimized as a function of the needs, in particular taking into account an effect of this shape to send more or less laterally far from the deflector the particulate matter that has been intercepted.
By way of example, several general types of deflector shapes have been shown in
On the two bottom lines of
In
In the case of a regular-corrugation sheet, in the horizontal axis, the axis of symmetry of the deflector must be merged with the axis of symmetry of the repeated geometrical pattern of the sheet profile considered as located in the bottom part of the patterns. In the vertical axis, the positioning of the deflector in height h is adjusted experimentally, with the corrugation height H of the sheet profile.
The length of each deflector must be sufficient to intercept efficiently and to redistribute the particulate matter of the curtain of particulate matter.
The state of surface of the deflector must be chosen as a function of the particulate to be deposited so as to avoid the problems of electrostatic charges, the problems linked to the frictions (coefficient of friction), the problems of wearing. This list is not exhaustive.
In the case of a coating of flakes of graphite, a deflector made of aluminum seems particularly adapted.
Taking into account the four variables of adjustment described hereinabove, it has been shown, in a machine implementing deflectors according to the invention, that the homogeneity of the distribution of the solid particles applied by gravity on the surface of a corrugated sheet was greatly improved. In the machine in question, it has been implemented brushed-aluminum deflectors of geometrical shape of the angle type of 25 mm, positioned in the axis of symmetry of the corrugations at a height h=1.5*H.
It is to be noted that, except advanced optimization, for example with partial interception of the particulate matter, it is in practice impossible to totally compensate for the “Geometry” effect. However, in the common practice of a total-interception deflector, the profile corrected using a chosen deflector, adapted and regulated, makes it possible to get strongly closer to the ideal profile (iso-thickness).
Thanks to the invention, the coating of flake of graphite at the surface of the corrugated sheets to improve the fire resistance has permitted to pass with success all the tests of resistance to an external fire contrary to the corrugated sheets for which the coating had been made without implementation of the deflectors of the invention.
In
Number | Date | Country | Kind |
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13 60918 | Nov 2013 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2014/052845 | 11/6/2014 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2015/067905 | 5/14/2015 | WO | A |
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Number | Date | Country | |
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20160250659 A1 | Sep 2016 | US |