The present invention concerns an abrasive element for use in rotating abrading or polishing tools for use in grinding or polishing surfaces, and of the type including an abrading fabric and support brushes, and where the abrading fabric is mounted such that the abrading fabric at its passive side is supported by the support brushes, where the abrading fabric is terminated by an outer free edge area which in use constitutes an active area of the active side of the abrading fabric. The invention further includes an abrading fabric for an abrasive element for use in rotating abrading or polishing tools for grinding or polishing surfaces, the abrading fabric being supported by support brushes at a passive side, where the abrading fabric is terminated by an outer free edge area which in use constitutes an active area of the active side of the abrading fabric. Background of the Invention

Abrasive elements for use in grinding or polishing machines constructed around e.g. drum grinders or grinding wheels are prior art. These will typically consist of abrading fabric and support brushes in combination. The abrading fabric and the support brushes are mounted in an elongated support rail where the abrading fabric and the support brushes protrude from the profiled rail. The rail is typically intended for retaining the abrasive element in an undercut groove in a tool on grinding or polishing machines.

The abrading fabric is terminated at a free outer edge area extending beyond the top of the brushes and along the upper end parts of the support brushes, and which in use constitutes the actively abrading area of the abrading fabric. However, the abrading area only constitutes part of the entire abrading fabric which is mounted in the profiled rail.

Moreover, the prior art abrasive elements are limited in their effect in that the flexibility, pliability, perpendicularly to the longitudinal direction is determined by the flexibility, pliability, of the sandpaper, and that the flexibility, pliability, is an important parameter by abrading or polishing the surfaces of various items.

Finally, it is well-known that abrading fabric in the shape of sandpaper is relatively cheap and has a limited service life. It is, however, not a problem as the abrasive elements may be replaced rapidly and simply without substantial time consumption.

However, there are known abrading fabrics where the price of material is considerable as well as it is known with machines where it is important with a long service life for the abrasive elements in the machines.

However, it is desirable to reduce costs, including providing abrasive elements where it is possible to reduce consumption of material. This is particularly pronounced in case of expensive abrading fabrics.

From US 4,969,299 is known a rotating abrading tool with abrasive elements containing flaps consisting of fabric with abrasive grains bonded thereon. In this document there is no indication of use of support brushes. An area of the fabric for supporting the flaps is kept clear of abrasive grains. Object of the Invention

By the present invention, it is therefore intended to reduce consumption of material, not only of expensive abrasive materials and abrading fabrics, but generally to reduce material consumption and thereby reduce operating costs. It is furthermore desired particularly also to indicate abrasive elements with possibility of long service life.

Description of the Invention

In the present description of the invention which is intended for use in abrading or polishing tools, the terms "abrade" and "polish" are arbitrarily interchanged. For example, an abrading fabric also means a polishing fabric, and so on. The primary object of the present invention is achieved by an abrasive element of the type mentioned in the introduction which is peculiar in that the abrading fabric is only coated with an abrading material in the active area. The abrading fabric according to the invention is peculiar in that the abrading fabric is only coated with abrading material in the active area.

By only having abrading materials in the active area of the abrading fabric, a saving of abrasive materials is achieved. This is particularly of significance when the abrasive materials are expensive, such as in the case of super-abrasive materials, e.g. in the form of diamonds.

In a preferred embodiment, the abrasive element is peculiar in that both the abrading fabric and the support brushes are mounted in an elongated profiled rail where the support brushes and the abrading fabric have different heights, support brush height and abrading fabric height, respectively, extending from the profiled rail such that the outer free edge area of the abrading fabric extends beyond the top of the support brushes and a short distance down along the outer free end parts of the support brushes.

Alternatively, the abrading fabric and support brushes can be mounted in separate, elongated profiled rails, or directly in the head of the abrading or polishing tool for individual replacement of brushes and abrading fabric. By using the abrasive element, the active area of the abrasive element may hereby enclose or roughly enclose the point or the top of the support brushes, and the active area with the abrading material may thereby act on a surface to be worked with an active area which is as large as possible for efficient abrading as the support brushes in a work stroke are substantially at right angles to the surface.

In an embodiment, the abrasive element is made such that the abrading fabric has an abrading fabric height and the support brushes have a support brush height. By this is meant an embodiment where the heights are constant along the profiled rail. In an alternative embodiment, the said heights along the profiled rail have varying height profiles such that the abrading fabric along the profiled rail has an abrading fabric height profile where the distance from the outer free edge area of the abrading fabric to the profiled rail varies. And also such that the support brushes along the profiled rail have a support brush height profile where the distance from the outer free end parts of the support brushes to the profiled rail varies. In this embodiment, the invention may hereby grind or polish surfaces with varying projections and/or holes.

According to a further embodiment, the abrasive element according to the invention is peculiar in that the active area constitutes between 1/4 and ½, typically about 1/3 of the abrading fabric height of the abrading fabric.

For typical combinations of abrading fabrics and abrading materials is hereby achieved in practice an appropriately active area which has the desired abrading effect and a material-saving effect as well compared with abrading fabrics also having abrading material in the inactive areas of the abrading fabric.

In an alternative embodiment, the abrasive element is peculiar in that the active area has an abrasive profile in the height direction of the abrading fabric. -Hereby is meant e.g. an abrasive profile with varying abrading material or e.g. abrasive profile with on/off abrading material.

In an alternative embodiment, the abrasive element is peculiar in that from the active area with abrasive material to the end of the outer free edge area there is a lesser area of the abrading fabric which is not coated with abrading material, the lesser area constituting between 0 and 1/8 of the abrading fabric height.

According to a further embodiment, the abrasive element according to the invention is peculiar in that the abrading fabric height of the abrading fabric is between 20 mm and 80 mm, typically about 40 mm.

Hereby is achieved by the abrasive element a suitable abrading effect by practical applications of the abrasive element in tools and machines which can be manually operated by one person, and in tools and machines applied in a typical production of elements in the industry.

It is obvious to the skilled in the art to extend the abrading fabric height for use in abrasive elements for application by larger or special grinding or polishing tasks.

It is also obvious to the skilled in the art to reduce the abrading fabric height for use in abrasive elements for application by smaller or special grinding or polishing tasks.

According to a further embodiment, the abrasive element according to the invention is peculiar in that the abrading material is a super-abrasive material consisting of particles or powder of e.g. diamonds or corresponding materials..

According to the invention is hereby achieved that the active area of the abrading fabric has a particularly efficient abrading ability that increases the service life compared with traditional abrading fabrics.

In a preferred embodiment, the abrading material is diamond particles.

In an alternative embodiment of the abrasive element the abrading material consists of material units having a unit size between 0.1 μηι and 1000 μηι. By this is meant that the abrading material can be a powder in the sense that the unit size is at the smaller end of the range and that the abrading material can be particles in the sense that the unit size is at the larger end of the range. The said range is typical for the abrading and polishing tasks typical for the invention.

By special and typically finer grinding and polishing tasks, it is obvious to the skilled in the art to go beyond the range and e.g. use abrading materials with unit size in the nano-range.

In that the abrading material is a super-abrasive material it is essentially understood that the units of the abrading material have a certain strength, e.g. a crystal strength or a breaking strength, and that this strength is about the strength of diamonds. Also, the units of the abrading material are variable in shape and structure. The units may thus be edged or round, or the units of the abrading material may be a combination thereof. The units may furthermore be crystalline or non-crystalline. An example of an alternative embodiment is the super-abrasive material boron nitride with a cubic unit shape (cBN), which material has a hardness close to that of diamonds and at the same time a thermal conductivity comparable to traditional abrading materials. In a further alternative embodiment, the super-abrasive material is coated with a coating which may be a metal coating, which metal coating e.g. may be based on nickel, copper or similar coating materials.

In an alternative embodiment, the nature of the abrading material in the form of particles is produced by the abrading fabric itself having local projections giving rise to an actual active contact with the surface to be abraded.

The area between the local projections provides channels that may conduct grinding dust or particles away from the abraded surface.

Furthermore, these projections and channels provide increased heat conduction.

According to a further embodiment, the abrasive element according to the invention is peculiar in that the abrading material is attached to the abrading fabric in the active area by a binder binding the said particles or powder to the abrading fabric.

Hereby is achieved by the abrasive element that the active area is directly embedded in the abrading fabric, and by wear the abrading fabric may readily be replaced in the profiled rail.

The abrading fabric may then be reused as new abrading material can be applied to the active area. In an embodiment, the binder is a resin-based binder. In alternative embodiments, other binders like varnish, glue or the like may be used.

The binder may furthermore be a polyimide or a phenolate.

According to a further embodiment, the abrasive element according to the invention is peculiar in that abrading material is provided on another fabric which is mounted on the active area of the abrading fabric. By this is meant that the abrading material is applied to a separate base, the other fabric, and that the other fabric and the active area of the abrading fabric are provided for mounting.

The form of mounting can be by gluing, welding, a Velcro-lock or a rail arrangement.

According to a further embodiment, the abrasive element according to the invention is peculiar in that flexibility of the abrading fabric in an area between the active area and the profiled rail is greater than the flexibility of the abrading fabric in the active area. By flexibility is meant pliability, and substantially in the direction perpendicular to the longitudinal direction of the profiled rail.

The flexibility is the active area of the abrading fabric is essentially associated with the abrading material layer in the active area of the abrading fabric.

The flexibility of the abrading fabric in an area between the active area and the profiled rail is essentially associated with the flexibility of the support layer of the abrading fabric which lies between the active area and the profiled rail. According to an alternative embodiment of the abrading fabric, the inner area is provided with at least one area with enhanced flexibility. In an embodiment, this area is provided in that the abrading fabric in a narrow area is thinner than the rest of the area. Hereby is further achieved that the active area can act against the surface, approximately in parallel with the surface, as the active area comes between the surface and the edges of the support brushes. According to a further embodiment, the abrasive element according to the invention is peculiar in that the abrading fabric is cut up from the outer free area for forming lamellae.

In an embodiment, the abrading fabric is cut up from the outer free edge area to the profiled rail for forming long lamellae.

In an embodiment, the abrading fabric is cut up at right angles to the profiled rail from the free edge to a position between the active area and the profiled rail of short lamellae.

In an embodiment, the cutting up of the abrading fabric is periodical in longitudinal direction for forming lamellae with uniform lamella length.

In an embodiment, the cutting up of the abrading fabric is varying in longitudinal direction for forming lamellae with varying lamella length.

According to a further embodiment, the abrasive element according to the invention is peculiar in that the abrading fabric is made of a plastic material as e.g. polyethylene (PE), polypropylene (PP) or polyvinyl chloride (PVC), that the abrading fabric is made of a rubber material or that the abrading fabric is made of a bio-material.

The abrading fabric may hereby be used in the abrasive element for a longer period of time, and thereby with longer service life than traditional fabrics.

Description of the Drawing

In the following, an embodiment of the invention will be explained in more detail with reference to the accompanying Figures, in which: Fig. 1 shows the abrasive element from a side where the support brushes and the passive side of the abrading fabric are seen;

Fig. 2 shows the abrasive element from a side where the active side of the abrading fabric is seen;

Fig. 3 shows an isometric view of the abrasive element with the support brushes and the active side of the abrading fabric; and

Fig. 4 shows an isometric view which is preferably a cross-section perpendicular to the longitudinal direction of the abrasive element in use against a surface where the support brushes press the active area of the abrading fabric against the surface.

Detailed Description of Embodiments of the Invention

Fig. 1 shows an abrasive element 1 fastened in a profiled rail 2 which is intended for use in an abrading or polishing tool or machine. The profiled rail 2 is elongated, and thereby the abrasive element 1 has a natural longitudinal direction 3.

In the profiled rail 2 is mounted an abrading fabric 4 and support brushes 5. The abrading fabric 4 is made with lamellae 6.

In the specific embodiment, the profiled rail 2 delimits extraction of the abrading fabric 4 and the support brushes 5. From the mounting area of profiled rail 2 and in a height direction 7, the abrading fabric 4 and the support brushes 5 radiate or are raised substantially in the same height direction 7 within a narrow angle.

Opposite the profiled rail 2, the abrading fabric 4 ends in a fabric edge 8, and the distance from the fabric edge 8 to the profiled strip 2 defines a fabric height 9.

Opposite the profiled rail 2, the support brushes 5 end in a support brush end 10, and the distance from the support brush end 10 to the profiled strip 2 defines a support brush height 11. Similarly, an abrading fabric length 12 is defined as the extension of the abrading fabric 4 in longitudinal direction 3 and a support brush length 13 as the extension of the support brushes 5 in longitudinal direction 3. In the shown embodiment, the abrading fabric 4 is made with a plurality of lamellae 6 which in the specific embodiment approximately have the same lamella length 14. However, nothing prevents the lamella length 14 from varying.

In the shown embodiment, the brush length 13 is longer than the fabric length 12, and a plurality of brush hairs are provided per lamella length 14.

In the shown embodiment, the fabric height 9 is greater than the support brush height 11.

The passive side 15 of the abrading fabric 4 is, as shown, facing the support brushes 5.

Fig. 2 shows the same abrasive element 1 as in Fig. 1 from a different side, where particularly the active side 16 of the abrading fabric 4 appears.

The active side 16 of the abrading fabric 4 has an active area 17 (marked as— ) coated with an abrading material 18. The active area 17 is an area at an outer free edge area 19 (marked as ...) of the abrading fabric 4 from the abrading fabric edge 8 against the profiled rail 2. It is unimportant if the outer free edge area 19 has a height which is greater than the height of the active area 17. The essential feature is that the two mentioned areas 17, 19 have a certain overlap.

In the shown embodiment and illustrated in the detail in the Figure, the abrading material 18 is provided as a super-abrasive material 20 consisting of diamonds 21 in the form of particles 22 and a powder 23. The abrasive material 18 is here provided on another fabric 24, which in turn is mounted in the active area 17 of the abrading fabric 4. In the specific embodiment, the other fabric 24 is glued on the abrading fabric 4.

In the shown embodiment, the abrading material 18 on the other fabric 24 is cut up corresponding to the lamellae 6. Fig. 3 shows an isometric view of the abrasive element 1 with the support brushes 5 and the active side 16 of the abrading fabric 4.

The support brush end 10 rests or acts on a surface 25, the surface 25 also interacting with the passive side 15 of the abrading fabric 4.

The abrading fabric 4 is substantially with an inner flexibility 26 and an outer flexibility 27, where the outer flexibility 27 is associated with the active area 17 of the abrading fabric 4 and the inner flexibility 26 with the area between the active area 17 and the profiled rail 2.

Fig. 4 shows an isometric view of the abrasive element 1, which preferably is a cross- section perpendicular to the longitudinal direction 3 of the abrasive element 1 in use, or acting with the active side 16 of the abrading fabric 4 facing the surface 25, where the support brushes 5 are pressing on the passive side 15 of the abrading fabric 4 such that the active area 17 of the abrading fabric 4 acts on or works on the surface 25.