WO2021052548A1

WO2021052548A1 - Grinding element for use in rotary grinding or polishing tools

Info

Publication number: WO2021052548A1
Application number: PCT/DK2020/050258
Authority: WO
Inventors: Karsten Larsen; Claus Groth HEDE
Original assignee: Flex Trim A/S
Priority date: 2019-09-18
Filing date: 2020-09-18
Publication date: 2021-03-25
Also published as: US20220402099A1; DK201970574A1; BR112022004866A2; DK180350B1; EP4031327A1; CN114728402A

Abstract

Described is a grinding element (1) for use in rotary grinding or polishing tools used for grinding or polishing surfaces, and of the type comprising an elongate profile rail (2), including an abrasive cloth (4) and support brushes (5). The abrasive cloth (4) and the support brushes (5) are mounted in or on the profile rail (2), such that the abrasive cloth (4) is supported by the support brushes (15) on its inactive side (15). The abrasive cloth outside the profile rail (2) has a height (9) in the vertical direction (7) and a length (12) in the longitudinal direction (3). The support brushes (5) and the abrasive cloth (4) have different heights, a support brush height (11) and an abrasive cloth height (9), respectively, from the profile rail (2), such that the abrasive cloth (4) is terminated by an outer exposed edge area (19) extending beyond the top of the support brushes (5) and a short distance down along the outer exposed end portions (10) of the support brushes (5). The outer exposed edge area (19), when used, constitutes an active area (17) of the active side (16) of the abrasive cloth (4). The abrasive cloth (4) is coated only with abrasive material (18) in the active area (17). The abrasive material consists of particles (22) of, for example, diamonds (21) or similar materials. The abrasive cloth (4) is cut from an outer exposed canvas edge (8) toward the profile rail in a direction parallel to the vertical direction (7) in order to form slats (6). The particles are placed in adjacent rows (26), such that the particles (22) of the abrasive material in a row7 (26) are arranged with the particles offset relative to the particles (22) in the adjacent rows (26). The particles in the rows (26) are arranged spaced apart (29), such that an overlap of the abrasive particles occurs in the longitudinal direction (3) of the abrasive canvas.

Description

GRINDING ELEMENT FOR USE IN ROTARY GRINDING

OR POLISHING TOOLS

Field of the invention

The present invention relates to a grinding element as described in the preamble of claim 1 of the present patent application.

Background of the invention

In the present description of the invention, which is intended for use in grinding or polishing tools, the terms "abrasive" and "polishing" are mutually interchangeable. For example, an abrasive cloth also refers to a polishing cloth, etc.

Grinding elements for use in grinding or polishing machines designed, e.g., as drum grinders or grinding wheels are known. These typically consist of a combination of an abrasive cloth and support brushes. The abrasive cloth and the support brushes are typically mounted in an elongate support profile rail, in which the abrasive cloth and the support brushes protrude from the profile rail. Alternatively, the support brushes may be mounted in an elongate support profile rail, and the abrasive cloth may be placed outside the profile rail or directly on the brushes. The profile rail is typically meant to secure the grinding element in an undercut groove on a tool on grinding or polishing machines.

The abrasive cloth is terminated in an exposed outer edge area extending beyond the top of the brushes and along the upper end portions of the support brushes, which forms the active abrasive area of the abrasive cloth, when in use. However, this abrasive area is only a part of the whole abrasive cloth, which is mounted in the profile rail.

Furthermore, known grinding elements are limited in their effect, in that their flexibility, pliability, perpendicular to the longitudinal direction, are determined by the flexibility and pliability of the sandpaper, and in that their flexibility, pliability, is an important parameter in treating surfaces, when grinding or polishing various workpieces.

Finally, it is well known that sandpaper in the form of sandpaper is relatively inexpensive and has a limited service life. However, this is not a problem, in that the grinding elements can be replaced swiftly and easily without substantial downtime.

However, grinding cloths with a substantial material price are also known, as are machines, for which a long service life of the grinding elements is important.

However, it is desirable to reduce costs, and also provide grinding elements, which allow for reducing the consumption of materials. This is particularly the case, when dealing with expensive abrasive cloths.

US 4,969,299 discloses a rotary grinding tool with grinding elements, which contains flaps consisting of cloth with glued-on abrasive grains. Said citation contains no instructions as to the use of support brushes. An area of the cloth for supporting the flaps is kept free of abrasive grains.

Furthermore, WO 2011/110176 discloses a grinding element of the type described in the preamble of claim 1 of the present patent application. For many years, this grinding element has worked acceptably in many applications, in that it has a history of reduced consumption of expensive abrasive materials and a long service life. However, disadvantages were encountered in the form of abraded grooves in surfaces treated with tools using these grinding elements.

Even when using fine-grained abrasive materials, problems were encountered in several applications, when finishing the treated surface. The treated surface will typically be finished with some form of coating or paint.

Thus, problems were encountered with a coating adhering to the treated surface. To remediate this, experiments were conducted with various basic treatments and binders as a foundation for surface varnishing or surface coating. The use of several finishing layers is undesirable both as concerns the incurred costs and the weight. Likewise, surface-gloss problems have occurred. In many products, this will create problems with unwanted glare and reflections. Even when using a coating for finishing purposes, this can create problems in the finished surfaces. This is due to treated surfaces having an irregular surface due to abraded grooves with areas, where glare and reflection occur. This problem is particularly exacerbated for fiber surfaces in public spaces, e.g., wind-turbine blades, safety helmets and photovoltaic systems. To alleviate this problem, experiments with special varnishes have been conducted. However, it is desirable to keep the weight within limits, especially with products, such as wind-turbine blades and safety helmets, i.e., reduce the use of paints and coatings as much as possible.

Thus, several experiments have been done with different types of finishing, including the use of binders and special varnishes. The application of binders, primers, special varnishes, possibly in several layers, will increase costs and, moreover, causes the weight to increase, which for several products is undesirable.

It is therefore desirable to improve grinding/polishing in order to achieve a surface, which will provide a better foundation in the form of the treated surface, and thereby minimize the need for finishing and eliminate problems with glare and adhesion.

Object of the invention

The object of the present invention is being able to use prior-art grinding elements, which reduces the consumption of expensive grinding materials, and which have a long service life, and also achieve uniform surface grinding, thereby minimizing problems with adhesion and glare.

Description of the invention

This object is achieved by the present invention by a grinding element of the type mentioned in the introduction, which is characterized in that the arrayed particles of the abrasive material are arranged with the particles offset relative to the particles in adjacent rows, and that the arrayed particles are spaced apart, such that the abrasive particles overlap in the longitudinal direction of the abrasive cloth. The commercially available abrasive cloths are machine-manufactured with the particles of the abrasive material placed in adjacent rows. The particle rows are placed such that the particles in every other row are offset from one another, when viewed transversely to the length of the rows.

When using these commercially available abrasive cloths, the normal procedure for forming slats in grinding elements has been to cut in a direction parallel to the rows and in a space between adjacent rows. This has made it possible to create a clean cut without interfering with the particles of the abrasive material, which typically consists of a diamonds or similar hard materials, which act as a super-abrasive material.

With such cutting, the slats of the grinding element are provided with rows of particles, which are oriented parallel to the vertical direction. This has caused abraded grooves with areas, in which a surface is being ground in areas adjacent to the rows, and minor or no abrasion in areas between these rows. In other words, areas will appear in the longitudinal direction of the abrasive cloth, in which there are no abrasive particles that can be used to form the surface being machined.

This problem is obviated with the present invention, in that the abrasive particles overlap in the longitudinal direction of the abrasive cloth. Thus, particles will be provided in the longitudinal direction of the abrasive cloth. The particles are appropriately arranged in rows. As the particles of the abrasive material are arranged in rows, generally commercially available abrasive cloths may be used. By changing the orientation of the rows, such that they are no longer parallel to the vertical direction of the abrasive cloth, it is possible to create overlapping of the abrasive particles in the longitudinal direction of the abrasive cloth.

Despite the fact that for many years it has been possible to "reverse" the orientation of the rows in commercially available abrasive cloths, the desire to perform cutting parallel to the rows has thus far required an expert’s solution to the formation of slats.

Thus, the invention in a surprisingly simple way allows for creating an abrasive cloth, in which the arrangement of the particles of the abrasive material makes it possible to grind the whole surface which is being covered by the abrasive cloth. Consequently, no specific abraded grooves occur with areas, where no grinding was performed.

Such areas of the surface, where no abrasion occurs, are undesirable, in that they appear with a smooth surface. This smooth surface may partly result in poor adhesion, but may also cause reflection and glare emanating from the top of the surface.

Thus, with a grinding element according to the present invention, a surface will be created, which is rougher and without smooth areas, which cause glare. This greater surface roughness will also create a larger area, which makes for a larger surface for the adhesion of coating or varnish. Thus, adhesion will be increased.

Due to the surface appearing rough and without smooth areas, the reflection will become far more diffuse. This makes it possible to control the surface and determine the chance of glare and gloss based only on the coating or varnish used. This varnish may be applied in a thinner layer than is traditionally the case, given the larger surface, wherein adhesion occurs, and given the diminished need for more layers in order to reduce glare from the abraded and coated surface.

Particularly with regard to wind turbine blades, it is desirable to control the glare from the turbine blade. A similar challenge occurs in photovoltaic systems, where glare from the often very large surfaces of such a photovoltaic system is undesirable.

In safety helmets, a similar reduction in the glare is also desirable for road safety reasons.

The specific arrangement of the particles being offset from the particles in the adjacent rows, along with the angular arrangement of the rows relative to the extension of the slats, results in improved grinding/polishing in a simple way, allowing for obtaining a surface, which creates a better foundation, whereby the need for post-treatment is minimized, while avoiding problems with glare, and optimizing adhesion. The abrasive material consists of particles placed in the active area of the abrasive cloth. Hence, this area has a particularly effective abrasive capability, which increases the service life in relation to traditional abrasive cloths. In a preferred embodiment, the abrasive material consists of diamond particles.

The abrasive material may comprise units of material, whose unit size is between 0.1 and 1,000 micrometers. This means that the abrasive material may have the consistency of a powder, in that the unit size is at the lower end of the range, and that the abrasive material may consist of particles, in that their unit size is at the upper end of the range.

The said range is typical of the grinding and polishing jobs that are characteristic of the invention.

It is obvious to a person skilled in the art when performing special and, in this case, typically more precise grinding and polishing jobs, to go outside the range, and, e.g., use grinding materials with a unit size in the nano range.

The units of the abrasive material may vary in terms of shape and structure. Hence, the units may be angular or round, or the abrasive material units may be a combination thereof. Moreover, the units may be crystalline or non-crystalline.

In an alternative embodiment, the abrasive material in the form of particles is characterized by the abrasive cloth itself having local projections, which create the actual effective contact with the surface to be abraded.

The area between the local projections give rise to channels, which can divert abrasive dust away from the surface, which is being abraded.

Moreover, these projections and channels provide increased heat conduction.

The abrasive cloth is cut out from the outer exposed edge area in order to form slats. The abrasive cloth is typically cut out perpendicular to the profile rail from the outer exposed edge of the cloth. In one embodiment, the abrasive cloth may be cut out from the outer exposed edge of the cloth to the profile rail in order to form long slats. Alternatively, the abrasive cloth may be cut out from the outer exposed edge of the cloth to a position between the active area and the profile rail in order to form short slats. The abrasive cloth may be cut out in order to form slats with identical slat lengths or to form slats with varying slat lengths.

According to a further embodiment, the grinding element according to the invention is characterized in that the adjacent rows are arranged at an angle different from 0° with respect to the vertical direction.

When using abrasive cloths, wherein the particles are arranged in rows, varying the orientation of the rows slightly relative to the vertical direction of the abrasive cloth can make the particles overlap in the longitudinal direction of the abrasive cloth.

Depending on the distance between the adjacent rows, the angle may be varied from 1° to 179°.

The abrasive cloth is preferably arranged, such that the adjacent rows are arranged at an angle of 90° relative to the vertical direction of the abrasive cloth.

According to a further embodiment, the grinding element according to the invention is characterized in that the orientation of the adjacent rows is in the longitudinal direction.

Thus, when the rows are aligned is in the longitudinal direction, their orientation will be below 90° relative to the vertical direction. This represents a particularly simple design. By arranging the particles in rows, it becomes possible to vary in a relatively simple way the particle size and shape, as well as the spacing between the particles in the rows, and thus ensure overlapping in the longitudinal direction of the abrasive cloth.

According to a further embodiment, the grinding element according to the invention is characterized in that the extension of the particles in the direction of the row is greater than the spacing between the particles in adjacent rows. By using particles, whose extent in the longitudinal direction of the row is greater than the distance between successive particles in an adjacent row, overlapping in the longitudinal direction of the abrasive cloth will be obtained in a particularly simple way. This is particularly advantageous, when using an abrasive cloth, wherein the rows are aligned in the longitudinal direction of the abrasive cloth.

According to a further embodiment, the grinding element according to the invention is characterized in that the abrasive material is a super-abrasive material, which consists of particles, as well as of powder of, e.g., diamonds or similar materials.

The abrasive material is a super-abrasive material, which in essence means that the units of the abrasive material have a certain strength, such as crystal strength or tensile strength, and that this strength is roughly similar to the strength of diamonds.

An example of an alternative embodiment is the super-abrasive material Boron Nitride with a cubic unit shape (cBN), which has a hardness roughly the same of as diamonds and, at the same time, thermal conductivity comparable to traditional abrasive materials.

In a further alternative embodiment, the super-abrasive material is provided with a coating, which may be a metal coating and which may be based on, e.g., nickel, copper or similar coating materials.

According to a further embodiment, the grinding element according to the invention is characterized in that the active area constitutes between ¼ and ½ and typically about a third of the abrasive cloth height.

Thus, for typical combinations of abrasive cloths and abrasive materials, an active area is obtained in practice, which has the desired abrasive effect, as well as a material-saving effect over abrasive cloths, which also have abrasive material in nonactive areas of the abrasive cloth.

According to an alternative embodiment, the grinding element is characterized in that the active area has an abrasive profile in the vertical direction of the abrasive cloth. By this is meant, e.g., an abrasive profile with varying abrasive material or, e.g., an abrasive profile with an on/off abrasive material.

According to an alternative embodiment, the grinding element is characterized in that the active area of the abrasive material and up to the end of the outer exposed edge area includes a smaller area of the abrasive cloth, which is not coated with an abrasive material, and which constitutes between zero and an eighth of the abrasive height of the cloth.

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

Thus, the grinding element provides a suitable abrasive effect for practical applications in manually controlled machines and tools, and in machines and tools typically used in the production of elements in the industry.

It is obvious to a person skilled in the art to extend the height of the abrasive cloth for use in grinding elements for larger or special grinding or polishing purposes.

Likewise, it is obvious to a person skilled in the art to reduce the height of the abrasive cloth for use in grinding elements for smaller or special grinding or polishing purposes.

According to a further embodiment, the grinding element according to the invention is characterized in that the abrasive material is made to adhere to the abrasive cloth in the active area using a binder, which bonds the said particles to the abrasive cloth. If also using a powder, such a powder will also be bonded to the abrasive cloth by the binder.

As a result, the grinding element has the active area directly embedded in the abrasive cloth, and the abrasive cloth can easily be replaced in the profile rail, when worn. The abrasive cloth can then be recycled, in that a new abrasive material may be applied in the active area.

In one embodiment, the binder is a resin-based binder. In alternative embodiments, other binders such as varnish, adhesive, or the like, can be used.

Furthermore, the binder may be a polyamide or a phenolate.

According to a further embodiment, the grinding element according to the invention is characterized in that the abrasive material is provided on a second cloth, which is mounted in the active area of the abrasive cloth.

The idea is that the abrasive material is applied to a separate substrate, i.e., the second cloth, and that the second substrate and the active area of the abrasive cloth are set up for mounting.

Mounting may be done by adhesive bonding, welding, Velcro-locking, or a rail arrangement.

According to a further embodiment, the grinding element according to the invention is characterized in that the flexibility of the abrasive cloth in an area between the active area and the profile rail is greater than the flexibility of the abrasive cloth in the active area.

Flexibility refers to pliability and substantially in a direction perpendicular to the longitudinal direction of the profile rail.

Flexibility in the active area of the abrasive cloth is substantially related to the layer of abrasive material in the active area of the abrasive cloth.

The flexibility of the abrasive cloth in an area between the active area and the profile rail is substantially related to the flexibility of the support layer of the abrasive cloth, which is situated between the active area and the profile rail. According to an alternative embodiment of the abrasive cloth, the inner area comes with at least one area of increased flexibility. In one embodiment, the said area is brought about, in that the abrasive cloth in a narrow area is thinner than the rest of the area.

Furthermore, this allows for the active area to act upon the surface, approximately parallel to the surface, in that the active area appears between the surface and the tips of the support brushes.

According to a further embodiment, the grinding element according to the invention is characterized in that the abrasive cloth is made of a plastic material, such as Polyethylene (PE), Polypropylene (PP), or Polyvinyl chloride (PVC), and in that the abrasive cloth is made of a rubber material, or that the abrasive cloth is realized as a biomaterial.

This allows for the abrasive cloth to be used in the grinding element over an extensive period or time, and thus increases its service life over traditional cloths.

Description of the drawings

The invention will now be explained in more detail with reference to the accompanying drawings, in which

Fig. 1 is a sideview of a known grinding element showing the support brushes and the inactive side of the abrasive cloth,

Fig. 2 is a sideview of the grinding element in Fig. 1 showing the active side of the abrasive cloth,

Fig. 3 is an isometric view of the grinding element shown in Fig. 1 showing the support brushes and the active side of the abrasive cloth,

Fig. 4 is an isometric view of the device shown in Fig. 1, which is preferably a cross-section perpendicular to the longitudinal direction of the grinding element being used against a surface, wherein the support brushes push the active area of the abrasive cloth against the surface, Fig. 5 is an image corresponding to the section in Fig. 2 of an abrasive cloth for a grinding element according to the present invention,

Fig. 6 is a schematic diagram of an enlarged view of the abrasive cloth shown in Fig. 5,

Fig. 7 is a schematic diagram illustrating a surface machined with a grinding element according to prior art, and

Fig. 8 is an illustration corresponding to Fig. 7, wherein a surface is machined with a grinding element according to the present invention.

Detailed description of the invention

Figs. 1-4 show the basic design of a prior-art grinding element 1, as disclosed in WO 2011/110176. This design shares the design of a grinding element 1 according to the present invention. The difference lies in the way, in which the abrasive particles are arranged on the abrasive cloth. Thus, the grinding element 1 according to the invention will be explained with reference to the explanation of the known grinding element. The novel features of the invention will be explained in more detail with reference to Figs. 5-8.

Fig. 1 shows a grinding element 1 secured in a profile rail 2, which is intended for use in a grinding or polishing tool or machine. The profile rail 2 is elongate, and thus the grinding element 1 has a natural longitudinal direction 3.

An abrasive cloth 4 is mounted in the profile rail 2, as are support brushes 5. The abrasive cloth 4 is provided with slats 6.

In this specific embodiment, the profile rail 2 limits the risk of the abrasive cloth 4 and the support brushes 5 being extracted from the profile rail. The abrasive cloth 4 and the support brushes 5 ascend or radiate substantially in the same vertical direction 7 within a narrow angle from the mounting area of the profile rail 2 and in a vertical direction 7. Opposite the profile rail 2, the abrasive cloth 4 terminates at an edge of the cloth 8, and the distance between the edge of the cloth 8 and the profile strip 2 defines the height of the cloth 9.

Opposite the profile strip 2, the support brushes 5 are terminated in a support brush extremity 10, and the distance between the support brush extremity 10 and the profile strip 2 defines the height 11 of the support brush.

Similarly, the abrasive cloth length 12 is defined as the extension of the abrasive cloth 4 in the longitudinal direction 3, and the support brush length 13 is defined as the extension of the support brushes 5 in the longitudinal direction 3.

In the embodiment shown, the abrasive cloth 4 is realized with a plurality of slats 6, which in the specific embodiment have roughly the same length 14. However, nothing stands in the way of varying the slat length 14.

In the embodiment shown, the brush length 13 exceeds the canvas length 12, and there is a plurality of bristles per slat length 14.

In the embodiment shown, the height 9 of the cloth exceeds the height 11 of the support brush.

As shown, the inactive side 15 of the abrasive cloth 4 faces the support brushes 5.

Fig. 2 shows the same grinding element 1 as in Fig. 1, but from a different side, wherein, in particular, the active side 16 of the abrasive cloth 4 appears.

The active side 16 of the abrasive cloth 4 has an active area 17 (marked as --- ), which is coated with an abrasive material 18. The active area 17 is an area at an outer exposed edge area 19 (marked as ...) of the abrasive cloth 4 from the edge of the abrasive cloth 8 toward the profile rail 2. It is immaterial whether the outer exposed edge area 19 has a height, which is greater than the height of the active area 17. The important thing is that the two said areas 17, 19 have a certain overlap. In the embodiment shown and illustrated in the section of the figure, the abrasive material 18 is provided as a super-abrasive material 20, which consists of diamonds 21 in the form of particles 22. Also illustrated here is a powder 23, which may optionally be used with the particles 22.Here, the abrasive material 18 is provided on a second cloth 24, which furthermore is mounted in the active area 17 of the abrasive cloth 4.

In the specific embodiment, the second cloth 24 is glued to the abrasive cloth 4.

In the embodiment shown, the abrasive material 18 on the second cloth 24 is cut similarly to the slats 6.

It can be seen here that the particles 22 are placed in rows 26. It is quite customary in commercially available abrasive canvases of this type for the particles to be placed in adjacent rows on a canvas. The particles 22 in every other row 26 are placed next to one another, as seen in the longitudinal direction 3. The particles 22 in the intermediate rows 26 are located offset next to the spaces. Thus, the rows 26 of particles 22 are oriented parallel to the vertical direction 7. It can also be seen that the cut-out is done parallel to the vertical direction 7 in the spaces 30 between the rows 26. In these spaces 30, the particles 22 do not overlap, such that the spaces 30 in the longitudinal direction 3 of the abrasive cloth have no abrasive material. This gives rise to abraded grooves, in that areas on the surface 25 (see Figs. 3 and 4), which are abraded with the grinding element 1, will not be coated by the particles 22.

Fig. 3 is an isometric view of the grinding element 1 showing the support brushes 5 and the active side 16 of the abrasive cloth 4.

The extremity of the support brush 10 rests or acts on a surface 25, which surface 25 also interacts here with the inactive side 15 of the abrasive cloth 4.

The abrasive cloth 4 substantially has inner and outer flexibility, wherein the outer flexibility is associated with the active area 17 of the abrasive cloth 4, and the inner flexibility is associated with the area between the active area 17 and the profile rail 2. Fig. 4 is an isometric view of the grinding element 1, which is preferably a cross- section perpendicular to the longitudinal direction 3 of the grinding element 1, in use, or acting with the active side 16 of the abrasive cloth 4 facing the surface 25, wherein the support brushes 5 push on the inactive side 15 of the abrasive cloth 4, such that the active area 17 of the abrasive cloth 4 acts or works on the surface 25.

Fig. 5 shows a section of an abrasive cloth 4 for a grinding element 9 according to the present invention. The device shown in Fig. 5 corresponds to the section in Fig. 2 and thus illustrates the abrasive cloth 16, upon which a second canvas 24 is arranged, and in which the abrasive material 18 is provided.

The abrasive material 18 is provided in the form of particles 22, which are arranged in rows 26. The rows 26 are arranged parallel to the longitudinal direction 3 of the abrasive cloth, and thus perpendicular to the vertical direction 7 of the abrasive cloth. The abrasive rows have a direction 28 at an angle 27 with respect to the vertical direction 7

The extension 30 of the particles 22 is in the direction of the row 28, and is greater than the spacing 29 between the particles 22 in the adjacent rows 26. Furthermore, the particles are arranged offset relative to one another in the rows 26. In this way, an overlap of abrasive particles over the whole longitudinal direction 3 of the abrasive cloth is obtained, such that any area of a surface 25 being machined will be coated with particles 22 from one or the other row 26.

Fig. 6 has an enlarged section showing the abrasive particles 22 arranged in rows 26. It also illustrates more clearly that the extent 30 of the particles is greater than the distance 29 between the particles 22.

In Fig. 6, the particles are shown with a substantially circular shape. Alternatively, however, the particles 22 may have a different shape.

Fig. 7 illustrates a surface 25 abraded with a conventional grinding element of the type shown in Fig. 1. It can be seen that the surface 25 is provided with abraded grooves or depressions 32. These are created in areas next to each row 26 of particles 22, which in the known design are oriented in the vertical direction 7 of the abrasive cloth.

Between the depressions 32, there are areas with a flat surface 31. This flat surface 31 is an untreated flat surface, which appears without roughness. It may be smooth, which makes it difficult for varnish or other coating to adhere to the plane 31 of the flat surface 25. These flat surfaces 31 will also give rise to undesired reflections and glare from incident light, in that no diffusion occurs from the flat surfaces 31.

Fig. 8 illustrates a surface 25 machined with a grinding element according to the present invention. It can be seen here that the whole top surface of the plane 25 is machined by grinding elements, such that a series of adjacent abrasive grooves or depressions 32 are formed.

Between the adjacent abrasive grooves or depressions 32, peaks 33 are provided, which are approximately sharp.

With this abrasion, roughness is obtained over the whole top surface of the plane 25, which increases the chance that varnish or other coating will adhere. Furthermore, the rough surface will diffusely reflect incident light. Thus, glare and reflection will largely be avoided with a plane 25, as illustrated in Fig. 8.

Experiments have been conducted with grinding elements of the known type, as illustrated in Fig. 1, and with grinding elements of the novel type, as illustrated in Fig. 5. In this case, experiments were conducted with gel coat and carbon.

With a grain size of 200, it was found with gelcoat, that a grinding element according to the invention yields a roughness parameter (Ra) of 2.7, and with the known system, an RA of 2.5. Similarly, with carbon and a grain size of 200, an RA of 2.8 with a grinding element according to the invention, and an RA of 2.4 with the known grinding element were measured.

In addition, tests with a grain size of 120 have revealed an RA value of 4.4 and 3.6, respectively, for the grinding element according to the invention, over the previous one on gelcoat. Similarly, with a grain size of 120, an RA of 3.4 and 2.9, respectively, was measured in a carbon for a grinding element according to the invention as compared with the previous one.

In other words, there is evidence of improved roughness with both grain size 120 and grain size 200. For a grain size of 120, the roughness value thus increased by 22 percent.

For customers, this could mean a significant improvement in the adhesion and reduced reflection, as well as in the grinding rate and the service life of the grinding elements.

Claims

1. Grinding element (1) for use in rotary grinding or polishing tools used for grinding or polishing surfaces and of a type comprising an elongate profile rail (2) and an abrasive cloth (4) and support brushes (5), and wherein the abrasive cloth (4) and the support brushes (5) are mounted in or on the profile rail (2), such that the abrasive cloth (4) on its inactive side (15) is supported by the support brushes (15), wherein the abrasive cloth outside the profile rail (2) has a height (9) of the abrasive cloth in the vertical direction (7) and a cloth length (12) in the longitudinal direction (3), wherein the support brushes (5) and the abrasive cloth (4) have different heights, a support brush height (11) and an abrasive cloth height (9), respectively, from the profile rail (2), such that the abrasive cloth (4) is terminated by an outer exposed edge area (19) extending beyond the top of the support brushes (5) and a short distance down along the outer exposed end portions (10) of the support brushes (5), which outer exposed edge area (19) ), when in use, forms an active area (17) of the active side (16) of the abrasive cloth (4), which abrasive cloth (4) is coated only with abrasive material (18) in the active area (17), which abrasive material consists of particles (22) of, for example, diamonds (21) or similar materials, which abrasive cloth (4) is cut from an outer exposed edge of the cloth (8) against the profile rail in a direction parallel to the vertical direction (7) in order to form slats (6), and which particles are arranged in adjacent rows (26), characterized in that the particles (22) of the abrasive material in a row (26) are arranged with the particles offset relative to the particles (22) in adjacent rows (26), and in that the particles in the rows (26) are spaced apart (29), such that the abrasive particles overlap in the longitudinal direction (3) of the abrasive cloth.

2. Grinding element (1) according to claim 1, characterized in that the adjacent rows (26) are arranged (28) at an angle (27) different from 0° with respect to the vertical direction (7).

3. Grinding element (1) according to any claims 1 to 2, characterized in that the adjacent rows (26) are arranged with their orientation (28) in the longitudinal direction

(3).

4. Grinding element (1) according to any of the preceding claims, characterized in that the particles (22) have an extension (30) in the orientation (28) of the row, which is greater than the spacing (29) between the particles (22) in the adjacent rows (26).

5. Grinding element (1) according to any of the preceding claims, characterized in that the abrasive material (18) is a super-abrasive material (20), which consists of the particles (22) and a powder (23) of, for example, diamonds (21), or similar materials.

6. Grinding element (1) according to any of the preceding claims, characterized in that the active area (17) constitutes between ¼ and ½ and typically about a third of the height (9) of the abrasive cloth (4).

7. Abrasive element (1) according to any of the preceding claims, characterized in that the abrasive canvas height (9) of the abrasive canvas (4) is between 20 mm and 80 mm and typically about 40 mm

8. Grinding element (1) according to any of the preceding claims, characterized in that the abrasive material (18) is made to adhere to the abrasive canvas (4) in the active area (17) with a binder, which bonds said particles (22) to the abrasive cloth

(4)·

9. Grinding element (1) according to any of claims 1 to 7, characterized in that the abrasive material (18) is provided on a second cloth (24), which second cloth (24) is mounted in the active area (17) of the abrasive cloth (4).

10. Grinding element (1) according to any of the preceding claims, characterized in that the flexibility of the abrasive cloth (4) in an area between the active area and the profile rail is greater than the flexibility of the abrasive cloth (4) in the active area.