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The invention relates to the field of composite materials with abrasive function with overlapping layers.

Said abrasive composite materials are generally used together with honing and/or polishing machines for working and finishing any kind of surface.

Said honing machines generally comprise one or more heads, both fixed and movable, the tools thereof comprising portions, suitably shaped, of said abrasive composite material.

Honing machines often comprise also a sucking system for the powders produced during the honing, essentially made by ducts connected to a pump arranged for creating a suction pressure near said abrasive composite material for removing said powders.

The abrasive composite material normally used together with said honing machines comprises two layers of material coupled with one another and suitable anchoring means for obtaining a reversible fixing system to said machines' heads.

The first layer, i.e. the layer serving as a tool, is made of a paper or fabric sheet provided with an abrasive surface with grain specific for the use, and the second layer is made of resilient material, i.e. elastically yielding, arranged for absorbing the pressures that the honing machine exerts on the surface to be treated.

According to prior art, said resilient material is a closed cell foam, or a natural or artificial latex.

The anchoring means are generally made of a light wool layer applied to said second layer by glue, arranged for cooperating with a corresponding layer provided with hooks, arranged on said heads of said honing machines, in order to make a reversible Velcro ^® type fixing system that allows rapid substitution of said abrasive composite material in case of working change or substitution due to wear.

In particular the abrasive composite material in layers thus obtained is subsiquently cut into different shapes and dimensions for adapting to the use and to the machines and/or surfaces to be treated.

Said material is mainly cut into a circular shape for creating an abrasive disk for honing machines' rotating pads, but it can also have the shape of a strip, triangle, etc...

In a particularly useful embodiment, said abrasive disks can also be provided with a central hole for the centering onto the honing machine's heads and with a plurality of holes, arranged homogeneously, for allowing better suction of the powders produced during working.

Said abrasive composite material with overlapping layers, within the implementation to said honing and polishing machines, has some limits or drawbacks.

The main deficiency is in that, to be usable, said abrasive composite material must be coupled, by means of resins or glues, with a light wool layer, arranged for cooperating with a correspondent layer provided with hooks arranged on the working tools for making a reversible fixing: this disadvantageously implies the use of additional components, at high costs and long production times.

Besides, due to it being hardly permeable to air and solid particles, the resilient layer does not allow correct suction of the powders produced during the honing, therefore making it always necessary to provide suction holes, with additional costs, structure weakening and reduction of the abrasive surface.

DE 94 19 573 U1 discloses an abrasive composite material comprising a base made of non-woven fabric, an abrasive material in grain being applied on at least one of the faces thereof. Said composite material is not very tearing resistant, besides it needs the application of a light wool layer or of a roughening treatment of one face in order to be anchored to a working head provided with hooks, by means of a velcro type connection.

EP 07 38 562 A2 discloses an abrasive composite material comprising a base layer made of a velcrable fabric or non-woven fabric, the abrasive grain being directly applied on one of the faces thereof, thus serving at the same time as support layer and as light wool layer for a velcro type connection. Said material is particularly weak and scarcely tearing resistant, due to the fact that it comprises only one layer of non-woven fabric.

EP 1 666 204 A1 discloses an abrasive composite material comprising a base layer made of a needled fabric, one face thereof being covered with a binding layer that incorporates the abrasive grain. The rear face of the fabric can adhere to hooks arranged on a grinding wheel to make a velcro type connection. Said material needs elaborate and expensive treatments for applying the abrasive grain to the fabric, besides it tends to be rapidly obstructed by the powder particles sucked during working, loosing its porosity property.

Aim of the invention is to overcome said limits, producing an abrasive composite material with overlapping layers easily and rapidly produced and used, which does not need the application of any further layers serving as anchoring means for a reversible fixing system, cheap and provided with a good mechanical resistance and permeability for the air and the powders produced by the honing machines on which it is used.

These aims are achieved by means of an abrasive composite material with overlapping layers, comprising:

a first layer of paper or fabric provided with an abrasive surface; - a second layer of resilient material coupled to said first layer;

anchoring means arranged for cooperating with corresponding hooking means provided on a working head for making a reversible fixing system,

characterized in that said layer of resilient material is made of non- woven fabric based on artificial and/or natural fibers and also constitutes said anchoring means of said reversible fixing system.

According to a preferred embodiment of the invention said non-woven fabric comprises fibers bonded to one another in an open weft structure.

According to a further preferred embodiment of the invention said second layer of resilient material incorporates internally, or on the surface, a weft and warp fabric.

The abrasive composite material thus obtained has numerous advantages:

- the layer of paper or fabric gives the composite material special mechanical resistance and strenght and represents an excellent base for the application of the abrasive material according to prior art;

the layer made of non-woven fabric based on artificial and/or natural fibers serves at the same time the resilient purpose of absorbing the pressures that the honing machine exerts on the surface to be treated, and the purpose of fixing onto working tools through direct coupling of its fibers with suitable means correspondent to hooks provided on said working tools;

since the abrasive composite material itself serves the purpose of hooking, further applications of glue or resin are not necessary to couple a further layer comprising the anchoring means for the reversible fixing system, thus allowing production money saving; the weft and warp fabric associated with the layer of resilient material gives the abrasive composite material more consistence; the open weft of said resilient layer made of fibers bond to each other in an open weft structure allows passage of air and powders produced during working granting a good permeability without opening additional holes or with a lower density thereof and a smaller area occupied by said holes, which can also be opened in the abrasive layer only.

The advantages of the invention shall appear more clearly from the following description of a preferred embodiment, made by way of an indicative and non-limiting example, with reference to the drawings wherein:

Fig. 1 represents, in cross section and with proportions intentionally distorted, an abrasive composite material according to the present invention;

Fig. 2 represents, in a perspective view, the abrasive composite material of Fig. 1 partially rolled on itself;

Fig. 3 represents, in plan view, one face of an abrasive disk made of the abrasive composite material according to the present invention;

Fig. 4 represents, in cross section, one portion of an abrasive disk fixed onto the head of a honing machine.

Figures 1 and 2 show an abrasive composite material 1 with overlapping layers, Tollable in rolls 4, comprising a first layer provided with an abrasive surface 2, and a second layer of resilient material elastically yielding 3.

Said abrasive layer 2, made of abrasive paper or fabric, can have a surface with different grain according to the different implementations.

Said layer of resilient material 3 is made of non-woven fabric based on artificial and/or natural fibers and is also an anchoring means 6, of the light wool type, arranged for cooperating with corresponding hooking means 5, of the hooks type, provided on a general working head 9, for making a reversible fixing system.

The thickness of said second resilient layer 3 is advantageously comprised between 2 mm and 15 mm, and is made in particular of nylon and/or polyester fibers.

The length of said fibers can vary between 20 mm and 100 mm, and they are bond and treated by means of resins chosen among acrylic, phenylacrylic, polyurethane, phenolic resins and/or thermofusible materials.

Said first layer 2 is coupled with said second layer 3 made of fibers by means of a glue or resin film 8, or other equivalent fixing means of known type.

Figures 3 and 4 show an abrasive disk 10 for honing machines, provided with working heads 9 provided with a fixing system with hooks 5 for making a Velcro ^® type hook and loop reversible coupling with said disk 10, thanks to anchoring means 6.

Said disk 10, made of said abrasive composite material 1 according to the present invention, essentially comprises a first layer 2 provided with an external abrasive surface for the honing, and a second resilient layer 3. In the embodiment shown, said second layer 3 made of fibers internally incorporates a weft and warp fabric 7.

Said weft and warp fabric 7 is made of fabrics, also ladder-proof, made out of known materials, also of the plastic type, and gives higher stiffness to said second layer 3 of fibers and as a consequence to the whole disk 10.

The fibers of said second layer 3 that cross said weft and warp fabric 7 make all the same a light wool layer 6, arranged for coupling in a reversible way with said layer provided with hooks 5 provided on the working head 9.

In embodiments not shown, said second layer 3 of fibers incorporates said weft and warp fabric 7 only superficially in order for the fibers' tufts to stick out the mesh of said fabric, creating all the same the anchoring means 6.

Said abrasive disk 10 comprises a central hole 11 useful for the centering thereof on the moving heads of the honing machines.

In case the abrasive disk 10 is used in processings particularly meant for producing high quantities of powders, the presence of holes opened at least into the abrasive layer 2 can be considered, in order to facilitate the suction of the air containing said powders.

The use of said composite abrasive material with overlapping layers is as follows.

The roll 4 of material is unwound and cut into suitable shapes for adapting to the working heads 9. In case the honing machines are provided with sucking system, the air and the powders can pass through the resilient and transpirant layer 3 entering from the lateral surface. If necessary, the material can also be perforated for increasing the surface for the passage of air and powders.

The present invention, as described and illustrated, allows to reach the objectives and the aims preset.

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