US20230096027A1

US20230096027A1 - Abrasive Article and Method of Making such an Article

Info

Publication number: US20230096027A1
Application number: US17/909,402
Authority: US
Inventors: Sandro Giovanni Giuseppe Ferronato
Original assignee: KGS Diamond Group SA
Current assignee: KGS Diamond Group SA
Priority date: 2020-03-12
Filing date: 2020-03-12
Publication date: 2023-03-30
Also published as: WO2021180328A1; EP4117859A1

Abstract

A method for manufacturing an abrasive article (10), including:

- providing a sheet including a support layer (12) and members (20) of a quick release system, QRS (18, 19)
- applying a metal coating (36) onto the support layer and the QRS members;
- applying abrasive particles (38) onto at least part of the first surface of the support layer, so that the particles are thermally connected to the metal coating;

The support layer defines a plurality of openings (26) that extend from a first surface (14) of the layer, through the layer, to an opposite surface (16) of the layer, and which allow abrasion dust to pass through. The QRS members are fixed on or in the support layer and protrude from this opposite surface, and are configured to fix the article to a surface including complementary QRS members (19). The metal coating covers both the support layer and the QRS members, and forms thermally conductive paths from the abrasive particles on the first surface, via the openings, to the QRS members on the opposite surface.

Description

TECHNICAL FIELD

The invention relates to an abrasive article comprising for use in grinding or polishing treatment of objects. Furthermore, the invention relates to a method for manufacturing such an abrasive article.

BACKGROUND ART

Abrasive articles are generally known and can be used in various kinds of surface processing operations. Such operations may include grinding, smoothing, polishing, etc. of relatively hard materials like stone (e.g. granite, marble), glass, ceramics (tungsten carbide), concrete, solid metals (e.g. aluminium, titanium, steel), composites thereof (e.g. terrazzo), or glass fibre-reinforced plastics and hard coatings. Alternatively, such surface processing operation may be carried out on materials with lower hardness (abrasion resistance), such as on paint or lacquer, with the intention to polish or entirely remove a layer of this material. Depending on the product to be treated, the abrasive article may for instance be applied in the form of a belt, a disc, or a sheet.
Such an abrasive article may be used in combination with abrading tools that comprise a backup pad to which the abrasive article can be temporarily attached, using a quick release system (QRS) which may for instance be a touch fastener (e.g. a hook-and-loop attachment, also known as Velcro). The abrading tool can thus be used repeatedly, while only the abrasive article needs to be replaced, when the article is damaged or worn or when an abrasive article with a different processing effect is desired.
Patent document US2007/0028525A1 describes a known abrasive article, which includes a porous mesh support layer with holes to allow air and dust particles to pass through, and with hooks for attachment to a backup pad of an abrading tool equipped with loops. However, this known article is prone to overheating during use, which creates a high likelihood for causing burn marks on the surface of the processed object when the article is used for a prolonged continuous period.
It would be desirable to provide an abrasive article with QRS that is able to withstand higher mechanical and thermal loads.

SUMMARY OF INVENTION

Therefore, according to a first aspect of the invention, there is provided a method for manufacturing an abrasive article. The method includes:

- providing a base sheet that includes a support layer and fastening members of a QRS;
- applying an electrically and thermally conductive coating onto both the support layer and the fastening members, and
- applying abrasive particles onto at least part of the first surface of the support layer, so that the abrasive particles are thermally connected to the coating.
  In this method, the support layer defines a plurality of openings extending from a first surface of the support layer, through the support layer, to a second surface of the support layer opposite to the first surface. This support layer is configured to allow abrasion dust to pass through the support layer. The fastening members are fixed on or in the support layer and protrude from the second surface thereof, and are configured to temporarily fix the abrasive article to a surface including complementary fastening members of the QRS. The coating is applied so that it covers (when in solid phase) both the support layer and the fastening members, and forms thermally conductive paths from the abrasive particles on the first surface, via the openings, to the fastening members on the second surface of the support layer. The coating may be composed of any metal, metal alloy, or metal-resembling substance, which can be deposited from a suitable bath by electrodeposition techniques, so as to form a solid coating that fully covers the support layer and the fastening members, and which is abrasion-resistant, resistant to high operating temperatures, and is a good conductor of heat. This coating preferably has a melting temperature of at least 200° C. (at atmospheric pressure), a thermal conductivity of at least 40 Watt per meterKelvin, and a Vickers hardness of at least 350 megapascal or preferably above 500 MPa (in solid form and at operating temperatures).

The resulting abrasive article has improved heat dissipation properties. The coating is formed as a continuous body onto exposed outer surfaces of both the support layer and the fastening members, so as to form uninterrupted heat conducting paths that allow excess heat, which is generated in the deposits of abrasive particles on the first surface during abrasive action, to be quickly conducted via the coating, not only to the sides but also along and through the openings, and to the fastening members on the second surface of the support layer. Air or another fluid cooling medium may also be circulated through the openings, to allow heat stored in the coating to be absorbed and carried away from the abrasive article. For this purpose, an abrading tool carrying the article may be equipped with a circulation system and apertures for circulating cooling medium through the openings of the abrasive article. The effective heat dissipation area of the coating is considerable, because the coating extends across both the support layer and the fastening members. Improved heat dissipation via the coating (by conductive and convective heat transfer) causes the article to be less prone to overheating during use, thus lowering the likelihood of damaging the abrasive article or the processed object during abrasive action, and/or allowing the duration or frequency of cooldown intermissions to be reduced. In addition, the coating may improve the mechanical strength of the abrasive article, as the coating confers additional tear strength upon the support layer.
The term “quick release system” (QRS) is used herein to refer to a large number of cooperating fastening members, including first fastening members that are densely distributed across a surface of a first object and second fastening members that are densely distributed across a complementary surface of a second object. At least one of these objects is dimensionally flexible to allow out-of-plane bending or folding. Once engaged, the fastening members interlock to temporarily fix the objects to each other, while allowing the objects to be separated again by pulling force. The QRS may be a type of touch fastener, for instance a hook-and-loop fastener, with a first surface carrying a plurality of monofilament members shaped like hooks that project from this first surface, and with a complementary surface carrying a plurality of multi-filament members woven into loop-shaped projections. Alternatively, the QRS may be a mushroom-and-loop fastener, in which monofilament projections having mushroom-shaped heads are present instead of the hook-type fastening members. It will be understood that the selection of the type of first members on the abrasive article depends on the type of second members provided on the backing pad or mounting head of the abrading machine. As such backing pads and mounting heads are more likely to use hook- or mushroom-type fastening members, the abrasive article preferably has first members formed as loops. Alternatively, the backing pad or mounting head may be provided with loop-type fastening members, and the abrasive member may be provided with short strands that carry a hook or mushroom fastener on one distal end, and which are fixed with opposite distal ends to the support layer.
The openings in the support layer extend all the way through the support layer, and open up on both the first and second surfaces thereof. These openings are arranged in a surface (i.e. two-dimensional) array across the support layer. The openings are dimensioned so as to allow dust particles originating from the abraded surface or wear of the abrasive article to be transported from the first surface, through the support layer, and to the second surface. The openings may have various cross-sectional shapes, for instance quadrilaterals (e.g. rectangles, squares, diamonds, trapezoids), ellipses (e.g. circles), or different polygons (e.g. triangles, hexagons, etc.). In a support mesh made of woven fibre material, the openings may have regular quadrilateral cross-sectional shapes (e.g. regular diamonds, rectangles, but preferably squares). A characteristic cross-sectional size of the openings may be in a range of 0.1 millimetres to 4 millimetres. A pitch between centres of directly adjacent openings may be in a range of 0.77 millimetres to 2.25 millimetres.
In embodiments, the openings in the support layer have an open area (percentage) in a range of 20%-60% of the total surface area of the abrasive article. An open area percentage for the through openings in the indicated range yields a good balance between mechanical strength of the article on the one hand, and heat and dust discharge capability of the article on the other hand.
The openings in the support layer may be formed in a regular (i.e. symmetric) pattern along the surface. This pattern may exhibit two-dimensional periodicity, mirror symmetry, and/or discrete rotational symmetry. The term “discrete rotational symmetry” is used to indicate that the support layer exhibits symmetry when being rotated over a non-zero angle of 180° or less about an axis perpendicular to the plane of the layer. Examples are a honeycomb pattern, a wire mesh with diamond-shaped openings, or a mesh with square openings. The pattern may be a cellular pattern wherein a single cell shape is repeated along one or both surface dimensions, but it may also be a tessellation wherein rotation symmetry is only present for a group of multiple cells at once. Having a periodic surface pattern allows the abrasive article to be produced on a roll that can be cut into any desired shape afterwards. A woven square mesh is preferred, for it is cheap to manufacture and symmetric under 90° rotation.
In an embodiment, the fastening members are directly fixed onto or in the support layer before applying the coating. The method may then further comprise:

- applying the coating so as to cover and extend in a continuous manner across exposed outer surfaces of both the support layer and the fastening members.

The support layer and fastening members form an integrated (i.e. unitary) body, onto which the coating is subsequently and simultaneously applied. In this context, “integrated” refers to a rigid attachment of the fastening members to the support layer, so that their combined exposed surface area is smaller than the sum of the exposed surface areas of the separate support layer and fastening members before integration. Integrating the support layer and fastener members before applying the coating yields a significant reduction in the total outer surface of the support layer and members that need to be coated, in contrast to a support layer and fastening members (with its own backing layer e.g. a mesh or glue film) that are coated individually before being attached to each other. Simultaneous coating of the integrated layer with fastening members reduces the required time for coating and required amount of coating material, thus yielding a more efficient and/or economical manufacturing method.
The coating may also strengthen the mechanical connection between the fastening members and the support layer. Alternatively or in addition, for meshes with separate interwoven strands that are initially not mutually fixed, the coating may help to fix the mesh strands in place.
The support layer and fastening members may be integrally formed as a unitary body. The term “integrally formed” refers herein to the support layer and fastening members that are simultaneously manufactured as a single unit, and not as separate bodies that are subsequently mechanically attached, welded, adhered, or otherwise integrated. For example, a plastic wire mesh with integrated hooks or mushroom-shaped fastening members on a lower surface may be integrally formed using casting, 3D printing, or injection moulding techniques.
In embodiments, the coating forms a matrix layer. The method may then further include:

- applying the coating onto the support layer and the fastening members embedding the abrasive particles in a portion of the coating present at the first surface of the support layer, using electrolytic co-deposition.

Electroplating (also known as Galvanic deposition) is a process in which metal cations dissolved in a liquid medium are caused by an applied electric field to be deposited as a thin layer onto a surface of an object serving as an electrode. Electrolytic co-deposition is an electroplating method by which non-metallic particles (in this case, the abrasive particles) are embedded into a metallic coating that forms a matrix, and which is obtained from a solution in which the metal cations are dissolved and the particles are suspended.
Preferably, a thickness of the finalized electroplated coating including abrasive particles is in a range of 4 micrometres to 300 micrometres, depending on the grit size of the particles.
In embodiments, the method further includes:

- before applying the coating, applying an electrically conductive primer coating directly onto the support layer and the fastening members, and;
- applying the coating onto the primer coating, using electroplating or electrolytic co-deposition.
  The primer coating may for instance be a metal primer coating that is applied directly onto the support layer and the fastening members using chemical plating, to form a solid continuous metal layer that envelops the support layer.

“Chemical plating” (also known as “electro-less plating” or “auto-catalytic plating”) involves chemical reactions of metal cations in an aqueous solution without the use of an electric field. The resulting metal primer coating, which is thin relative to the electroplated metal coating, renders the coated outer surfaces of the support layer and fastening members electrically conductive, thus facilitating a subsequent step of coating the article with a (thicker) metal layer using electroplating techniques. Electrical conductivity of the applied solid primer coating is at least 10⁵Siemens per meter, and the primer coating preferably has a melting temperature of at least 150° C. (at atmospheric pressure). The primer coating may be any electrically conductive metal or metal alloy that can be applied to the support layer and fastening members by electro-less plating, for instance copper, gold, or silver (possibly alloyed with other minor components), but preferably nickel (alloy). A thickness of the primer coating formed by electro-less plating of nickel is preferably in a range of 0.05 micrometres to 8 micrometres. Alternatively, the primer coating may be a non-metallic material with an electrical conductivity of at least 10⁵S/m and melting temperature of at least 150° C.
In embodiments, the method may further include:

- providing the base sheet shaped as an elongated web that is stored on a roll or folded stack;
- continuously or intermittently unrolling or unfolding consecutive web portions of the base sheet from the roll or the folded stack;
- continuously or intermittently applying the coating onto both the support layer and the fastening members and applying abrasive particles onto the first surface of the support layer of respective consecutive web portions that have been unrolled or unfolded, thereby forming web portions of semi-finished abrasive sheet material, and
- cutting a predetermined shape form at least one of the web portions of semi-finished abrasive sheet material, to form the abrasive article.

The flexible semi-finished abrasive sheet material, including the base sheet with coated support layer and QRS fastening members, and bearing deposits with abrasive particles, may thus be conveniently produced in a roll-to-roll fashion, and subsequently cut (e.g. punched) into abrasive articles.
In embodiments, the abrasive article may be formed as a pad, disc, sheet, or belt configured to carry out a grinding and/or polishing process.
According to a second aspect of the invention, and in accordance with advantages and effect described herein above with reference to the first aspect, there is provided an abrasive article for processing a surface. The abrasive article includes a base sheet, a coating, and a deposit of abrasive particles. The base sheet includes a support layer and QRS fastening members. The support layer defines a plurality of openings, extending from a first surface of the support layer, through the support layer, to a second surface of the support layer opposite to the first surface. These openings are configured to allow abrasion dust to pass through the support layer. The fastening members are fixed on or in the support layer and protrude from the second surface thereof, and are configured to temporarily fix the abrasive article to a surface including complementary fastening members of the QRS. The abrasive particles cover at least part of the first surface of the support layer, and are thermally connected to the coating. The coating covers both the support layer and the fastening members, and forms thermally conductive paths from the abrasive particles on the first surface, via the openings, to the fastening members on the second surface of the support layer.
In an embodiment, the support layer is a mesh formed of multiple wires or strands that mutually cross or intersect, and which define the openings in between.
The term “mesh” is used herein to refer to a network of interconnected strands/wires, which—in mechanical rest state—forms a two-dimensional surface structure. These strands/wires may be formed by fibers (e.g. continuous monofilaments), by continuous yarns (i.e. intertwined fibers), or by continuous twines (i.e. intertwined yarns or bundles) made of such fibers. These strands/wires extend in a continuous manner predominantly along the mesh surface, and are arranged in a periodic and structured orientation relative to each other. In this context, the mesh forms an “open mesh” in which the strands/wires are patterned in a mutually interspaced arrangement, such that the strands/wires are at non-zero distances apart and enclose through holes in between them. The mesh surface structure has a thickness dimension being at least three orders of magnitude smaller than both of its in-plane dimensions. In particular, a characteristic cross-sectional size of the mesh fibres may be in a range of 0.05 millimetres to 1.5 millimetres, and a thickness of the mesh in an out-of-plane direction may be in a range of 0.1 to several millimetres.
The mesh wires or strands can be woven, welded, integrally formed, slit-and-expanded, etc. The mesh may for instance be a wire mesh formed by first strands that extend in a first in-plane direction and second strands that extend in a second in-plane direction, with the second strands crossing or intersecting the first strands. The mesh may for instance be a regular two-dimensional quadrilateral mesh of interwoven first and second strands or yarns.
In embodiments, the mesh is flexible in relation to out-of-the-plane folding/bending deformations. The term “flexible” refers herein to a mesh that is sufficiently ductile to allow out-of-plane flexing (e.g. bending or folding), such that the mesh can be flexed by manual force from a planar state of rest in to a temporary curved shape with a radius of curvature in the order of centimetres, or possibly even millimetres, without breaking. This flexibility simplifies the attachment and removal of the article from the base pad of an abrasive tool, and allows the article to be produced and stored on a roll or folded stack. The mesh may additionally have a low elasticity (i.e. low bending stiffness) so that the temporary curved/folded shape does not create substantial internal restoring forces that urge the layer back towards its planar state (compared to the manual force applied to fold/bend the mesh).
The mesh is preferably made of continuous filaments/twines/yarns of synthetic (e.g. polymer, mineral, glass, or ceramic) fibres, which have a high resistance to heat (a burning/melting/decomposition temperature of at least 160° C.) and are easily and reversibly flexible in relation to bending or folding out of the plane, yet have a high ultimate tensile strength (at least 100 MPa) along their length direction. Applying coating(s) onto such a mesh confers considerable heat dissipation capability upon the article but ensures sufficient flexibility. The mesh may for instance be composed of strands made of polyester fibre. Polyester is resistant against most chemicals, which allows the wire mesh to be placed in a chemical solution to apply the abovementioned electro-less plating or electroplating techniques without damaging the wire mesh. In addition, polyesters have typical melting temperatures of about 250° C., which is convenient during manufacturing as well as during use of the article.
In embodiments, the mesh is woven, braided, or knitted. The fastening members may thus be easily integrated into the wire mesh. A weaving, braiding or knitting pattern can be used, in which loops or hooks naturally protrude from the bottom surface of the wire mesh. Hooks may be formed by using split wires, or by cutting the loop in two parts. The coating fixes the position of all yarns in the wire mesh with respect to each other, and the position of the fastening members relative to the wire mesh. Woven, braided, or knitted mesh material can be supplied on a roll, which can be efficiently employed in a roll-to-roll manufacturing process of abrasive articles.
In embodiments, the mesh is an extruded mesh, a punched mesh, or a slit-and-expanded material mesh. The first surface (carrying the abrasive particles) of such mesh types may be made essentially flat, which helps to enlarge the contact area between the article and the surface to be polished, and thus leads to smoother polishing results and more homogeneous wear of the article during use.
In embodiments, the fastening members are integrated with the strands of the mesh, so that the fastening members and strands engage along contact surfaces, and so that the coating covers and extends in a continuous manner across both the mesh and the fastening members, without extending directly in-between the fastening members and the strands along the contact surfaces.
In embodiment, the fastening members are formed by filaments having base portions that are mechanically fixed to or incorporated into the support layer. The base portions may for instance be embedded in the strands of the mesh support layer, or may be intertwined with the mesh strands.
Relying on mechanical fixation of the fastening members to the support layer, avoids the need for an adhesive or other bonding agent to connect the fastening members to the support layer. When electroplating is used to apply the metal coating, or when electro-less plating is used to apply a metal primer coating, the mechanical bond is not affected by the chemical solution with metal cations (in contrast to an adhesive bond), and the chemical solution will not be contaminated by dissolving adhesive. Moreover, adhesives used in the field typically have high electrical resistivity, which obstructs the desired flow of charged particles and hence frustrates the deposition of metal during electroplating.
The phrase “intertwined with the mesh” refers herein to the result obtained by any technique known from textile crafting, such as weaving, knitting, spinning, braiding, interlacing, or otherwise intertwining the QRS filaments with the mesh strands.
The abrasive article may be formed as a rotationally symmetric pad, for instance a circular pad, and wherein the support layer and the openings both have discrete rotational symmetry.
Abrasive articles with a rotationally symmetric mesh are highly suited for application on abrading tools having an actuator head, which rotates about a nominal axis that is perpendicular to the surface normal of the article and on which the article is centred.
The coating may for instance be a metal coating that consists essentially of nickel or nickel-based alloy. Nickel can be deposited in a uniform manner, is corrosion resistant, and has a high hardness and abrasion resistance against mechanical wear resulting from friction along its surface.
The abrasive particles may consist essentially of diamond or cubic boron nitride (c-BN). Using diamond or c-BN as abrading particles renders the abrasive article suited for abrading surfaces with considerable hardness, for instance rock types. A grit size of the abrasive particles may vary from >0 to 250 μm.
The abrasive particles may be selectively deposited in a non-uniform manner across the first surface of the support layer (at a characteristic scale larger than the individual openings), so as to form a pattern of localized surface regions with particles that are confined and interspersed by surface regions that omit abrasive particles. The shape of and interspacing between such surface patterns may be varied, to adjust the flexibility and/or the abrasive aggressiveness of the article. The distribution of particle deposits may for example be attributed a (discrete or continuous) planar rotational symmetry in articles that are used in abrasive processes involving (continuous or oscillatory) rotational motion, or translational symmetry for articles that are used in processes involving (continuous or oscillatory) linear motion.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts. In the drawings, like numerals designate like elements. Multiple instances of an element may each include separate letters appended to the reference number. For example, two instances of a particular element 22 may be labelled as “22 a” and “22 b”. The reference number may be used without an appended letter (e.g. “22”) to generally refer to an unspecified instance or to all instances of that element, while the reference number will include an appended letter (e.g. “22 a”) to refer to a specific instance of the element.

FIG. 1 schematically shows a perspective view of an abrasive article according to an embodiment;

FIGS. 2 a-b show a top view and a cross-sectional side view of the article from FIG. 1 ;

FIG. 3 schematically illustrates system and process embodiments for manufacturing an abrasive article, and

FIGS. 4 a-c illustrate steps in a process for manufacturing an abrasive article, according to an embodiment.

The figures are meant for illustrative purposes only, and do not serve as restriction of the scope or the protection as laid down by the claims.

DESCRIPTION OF EMBODIMENTS

The following is a description of certain embodiments of the invention, given by way of example only and with reference to the figures.
FIG. 1 schematically shows a perspective view of the abrasive article 10, of which a part has been schematically cut out to show part of the article 10 in cross-section. The article 10 may be used to grind surfaces made of glass, metal, stone, ceramics, or composites.
The article 10 comprises a support layer 12 formed as a wire mesh, which defines an upper surface 14 and a lower surface 16 on opposite sides. The upper surface 14 carries a deposit with abrasive particles 38, and is adapted to face a surface of an object that is to be processed (e.g. grinded, polished, etc.).
The article 10 is configured to be attached to a disc-shaped base pad 42 of an abrading tool 40, by means of a hook-and- loop fastening system 18, 19. Such a base pad 42 may be rotatable about a nominal rotation axis A, relative to the remainder of the abrading tool 40 (not shown). On the lower surface 16 of the mesh 12, the article 10 is provided with first QRS-layer 18 formed by a dense distribution of fastening members 20 that protrude downwards from the lower surface 16. In this example, the fastening members 20 are loops configured to engage and interlock with hooks on the complementary QRS-layer 19 with hooks on the base pad 42. In attached state ready for operation, the disc-shaped article 10 is centred with respect to the nominal axis A.
FIG. 2 a shows a top view of a portion of the abrasive article 10 from FIG. 1 in more detail. The wire mesh 12 is coated with multiple layers 34, 36. The article and layers are shown in a partially stripped manner, only for illustrative purposes.
The wire mesh 12 is flexible, and formed by warp yarns 22 and weft yarns 24 that are woven together, so that the warp yarns 22 and weft yarns 24 cross each other in an alternatingly overlaying manner. In this example, the yarns 22 and 24 are made of polyester fibres that have initially been coated with a phenol formaldehyde resin (not shown). The yarns 22 and 24 each have a diameter of approximately 250 μm. It should be understood that different thread diameters may be used, depending on the desired mechanical characteristics of the resulting article.
As shown in FIG. 2 a , the weaving pattern creates through openings 26 in the mesh 12, which are enclosed between adjacent pairs of mesh strands 22, 24. The surface area of each of the openings 26 is approximately 0.5 mm². The open area (percentage) of the openings 26 relative to the total area of the bare mesh 12 is approximately 40%.
In this example, the fastening members 20 are also made of polyester filaments that are coated with a phenol formaldehyde resin. The resin-coated filaments have a diameter of approximately 60 μm, and are intertwined in the weaving pattern of the wire mesh 12 to form loops. The length of a loop is on average approximately 5.5 mm.
The wire mesh 12 and intertwined fastening members 20 are covered with a metal primer coating 34, with a metal main coating 36 that covers and fully envelops the primer coating 34, and with deposits of abrasive particles 38 that are embedded in the main coating 36 present on the upper surface 14 of the article 10. The main coating 36 fixes (immobilizes) the warp yarns 22, weft yarns 24, and fastening members 20 with respect to each other.
FIG. 2 b shows a cross-sectional side view of a portion of the abrasive article 10, which illustrates that the deposits with abrasive particles 38 are mainly positioned on the top surface 14 of the wire mesh 12. By contrast, the metal coating 36 is distributed in a continuous manner across the outer surfaces of the mesh 12 and the fastening members 20.
In this embodiment, the primer coating 34 has a thickness of approximately 0.2 μm and the main coating 36 has a thickness of approximately 100 μm. The main coating 36 and primer coating 34 are both made of nickel. It should be understood that a large variety of other metals, metal alloys, or metal-resembling materials with high thermal and electrical conductivities may be applied, and that the preferred thickness of the metal coating 36 relates to the desired thermal conductivity of the selected material. Preferably, a bulk thermal conductivity of coating 36 is at least 40 Watts per meter Kelvin.
The deposits with abrasive particles 38 are embedded in the main coating 36 on the upper surface 14 of the wire mesh 12. In this example, the matrix coating 36 is made of nickel, and the abrasive particles 38 are diamond particles with a median particle diameter of 40 μm. Nevertheless, it will be understood that in other embodiments, other matrix materials with high melting temperature and high heat conductivity, and abrasive particles of a different material and/or grit size may be used, dependent on the application purpose of the article.
The application of the coatings 34, 36 on the mesh 12 changes the openings 26 into openings 27 of reduced size. As a result, the surface area of each of the reduced openings 27 is approximately 0.3 mm², and the open area of the reduced openings 27 relative to the total area of the abrasive article 10 is approximately 30%. The size and amount of openings 27 are still sufficiently large to allow dust particles to pass through the article 10. Such dust particles may for instance originate from the processed surface of the object, or from wear of the article 10 itself. Besides removing dust, the openings 27 also allow ventilation through the abrasive article 10.
The coatings 34, 36 provide thermally conducting paths from the upper surface 14 of the article 10, through the openings 27, and to the fastening members 20 on the lower surface 16. During use of the article 10, heat produced by friction between the upper surface 14 with abrasive particles 38 and the surface of the treated object, can be conducted along these paths, through the wire mesh 12, and towards the fastening members 20. The abrading tool 40 may be equipped with a cooling device in the base 42, which extends along surface with QRS-layer 19 and allows heat accumulated in the QRS-layer 18 to be removed by conductive heat transfer.
Alternatively or in addition, heat accumulated in the layers 34, 36 may be absorbed and dissipated by convective heat transfer, for instance by air that is circulated through the openings 27 to absorb part of the heat in the coating 36, and to convey this heat away from the article 10. For this purpose, the abrading tool 40 may be equipped with an air suction system having suction apertures provided in the base 42 (FIG. 1 , not indicated), to promote flow of air through the openings 26.
FIG. 3 illustrates a method and a system 50 for manufacturing an abrasive article 10 according to embodiments. An elongated web of mesh precursor material is stored on supply roll 52, and continuously or intermittently unrolled into consecutive web portions 53 that are fed via guide rolls 56 towards a first bath 60 with an electro-less plating liquid 62. The resulting web portions with primer coating are continuously or intermittently moved by electrostatic roll 58 towards and into second bath 64, which is filled with a second liquid 66 with in which nickel ions and abrasive particles 38 are present. An electric field is applied between the coated web portion 53 and the source region of abrasive particles in the basin 64, so that the nickel ions are deposited as coating 36 onto both the support layer 12 and the fastening members 20 while the abrasive particles 38 are simultaneously embedded in the resulting coating 36 onto the first surface of the support layer of respective consecutive web portions 53. The resulting web portions 55 of semi-finished abrasive sheet material are moved out of the second bath 64, and are stored on a collector roll 54. These web portions 55 of subsequently be cut into separate abrasive articles 10.
FIGS. 4 a-4 c further illustrate method steps for manufacturing the abrasive article 10. FIG. 4 a shows an initial step, in which a base sheet with a mesh 12 and loop-shaped fastening members 20 is provided. Only three warp yarns 22 of the mesh 12 and a fastening loop 20 are shown in cross-section, whereas weft yarns 24 are omitted. The fastening members 20 are attached with base portions 28 wrapped around the mesh, so that the base portions 28 and strands 22 (and/or 24) engage along contact surfaces 30. The loop portions of members 20 protrude on a lower side 16 of the mesh 12.
FIG. 4 b illustrates that a metal primer coating 34 is applied onto the exposed outer surface regions 32 of the mesh 12 and fastening members 20, so that the mesh 12 and members 20 become essentially entirely embedded inside the primer coating 34. These exposed surface regions 32 do not coincide with contact surfaces 30, meaning that the primer coating 34 is not applied onto the surface regions 30 directly in between the mesh 12 and fastening members 20.
FIG. 4 c illustrates that a metal coating 36, is applied to the exposed surface of the primer coating 34, so that the mesh 12 and fastening members 20 with primer coating 24 become essentially entirely embedded inside coating 36. FIG. 4 c also illustrates that deposits with diamond grains 38 are embedded in portions of the metal coating 36 that are present on the upper surface side of the mesh 12. The resulting coating 36 fixes the members 20 and strands 22 (24) to each other, and simultaneously forms a metal matrix material for fixing in place the diamond grains 38 embedded therein.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. It will be apparent to the person skilled in the art that alternative and equivalent embodiments of the invention can be conceived and reduced to practice. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
Those skilled in the art and informed by the teachings herein will realize that the invention is applicable to any wire mesh or netting with integrated hook or loop surface that is or can be made thermally conductive. The wire mesh may also for instance be an extruded mesh, a slit-and-expanded material mesh, a knitted mesh, or a welded wire mesh. It will be clear to a person skilled in the art how to entangle or differently integrate the fastening members of the hook and loop system into the wire mesh. The selection for hooks or loops on the abrasive article will be determined by the type of fastening members provided on the base pad of the abrading tool.
This size and shape of various conceivable abrasive articles according to the present invention, may be adjusted to fit the dimensions of base pads or mounting members of various abrading tools. Exemplary alternatives are disc-shaped abrasive articles with a diameter in the order of 1 cm to several tens of cm. Other alternatives are closed-loop cylindrical sheets having a width comparable to their diameter, or elongated closed-loop belts having a length significantly larger than their width. Yet other embodiments include square or rectangular abrasive sheets with widths in a range of 10 mm to 60 cm and lengths in a range of 10 mm to 10 m. Abrasive pads with alternative shapes, like (rounded) triangle shapes, trapezoid shapes, or pentagonal shapes, are also conceivable.
In the above described embodiment, the abrasive particles 38 were densely but randomly distributed along an upper side of the article 10. In alternative embodiments, particles may be distributed in a non-uniform manner to form a plurality of localized deposits, these deposits being shaped into predetermined patterns on the upper surface of the article, for instance to optimize functionality of the abrasive article or to make the abrasive article aesthetically more attractive.
In the above embodiment, the mesh yarns and fastening members were formed of resin-coated polyester fibres. In alternative embodiments, the mesh may be formed of other types of (continuous) fibre material, provided the resulting filaments/twines/yarns are flexible, and have a high resistance to heat (melting/burning/thermal decomposition temperature of at least 160° C.) and a high ultimate tensile strength (of at least 100 MPa) along their length direction.
Also, the shape of openings in the wire mesh should not be considered limited to square openings. In alternative embodiments, the wire meshes may have openings with a regular cellular shape such as squares, honeycombs, triangles, or other polygons, or even a combination of different shapes.

LIST OF REFERENCE SYMBOLS

10 abrasive article
12 support layer (e.g. wire mesh)
14 first surface
16 second surface
18 QRS layer
19 QRS layer with complementary members
20 fastening member
22 warp yarn
24 weft yarn
26 through opening
27 reduced opening
28 base portion
30 contact surface
32 (initially) exposed surface
34 primer coating
36 deposit coating
38 abrasive particles
40 abrading tool
42 rotator base
50 manufacturing system
52 supply roll
53 web portion (of base sheet)
54 collector roll
55 web portion (of abrasive sheet)
56 guide roll
58 electrostatic roll
60 first bath
62 first liquid
64 second bath
66 second liquid
X longitudinal direction
Y transverse direction
Z normal direction
A rotation axis

Claims

1. A method for manufacturing an abrasive article, the method comprising:

providing a base sheet that includes a support layer and fastening members of a quick release system, QRS; wherein the support layer defines a plurality of openings, the openings extending from a first surface of the support layer, through the support layer, to a second surface of the support layer opposite to the first surface, and being configured to allow abrasion dust to pass through the support layer; and wherein the fastening members are fixed on or in the support layer and protrude from the second surface thereof, and are configured to temporarily fix the abrasive article to a surface including complementary fastening members of the QRS;

applying an electrically and thermally conductive coating onto the support layer and the fastening members;

applying abrasive particles onto at least part of the first surface of the support layer, so that the abrasive particles are thermally connected to the coating;

wherein the coating covers both the support layer and the fastening members, and forms thermally conductive paths from the abrasive particles on the first surface, via the openings, to the fastening members on the second surface of the support layer.

2. The method according to claim 1, wherein the fastening members are directly fixed onto or in the support layer before applying the coating, and wherein the method further comprises:

applying the coating so as to cover and extend in a continuous manner across exposed outer surfaces of both the support layer and the fastening members.

3. The method according to claim 1, wherein the coating forms a matrix layer, and wherein the method further comprises:

applying the coating onto the support layer and the fastening members and embedding the abrasive particles in a portion of the coating present at the first surface of the support layer, using electrolytic co-deposition.

4. The method according to claim 1, further comprising:

before applying the coating, applying a metal primer coating directly onto the support layer and the fastening members, using electro-less plating, and;

applying the coating onto the metal primer coating, using electroplating or electrolytic co-deposition.

5. The method according to claim 1, further comprising:

providing the base sheet shaped as an elongated web that is stored on a roll or folded stack;

continuously or intermittently unrolling or unfolding consecutive web portions of the base sheet from the roll or the folded stack;

continuously or intermittently applying the coating onto both the support layer and the fastening members and applying abrasive particles onto the first surface of the support layer of respective consecutive web portions that have been unrolled or unfolded, thereby forming web portions of semi-finished abrasive sheet material;

cutting a predetermined shape form at least one of the web portions of semi-finished abrasive sheet material, to form the abrasive article.

6. The method according to claim 1, forming the abrasive article as a pad, disc, sheet, or belt configured to carry out a grinding and/or polishing process.

7. An abrasive article for processing a surface, comprising:

a base sheet that includes a support layer and fastening members of a quick release system, QRS; wherein the support layer defines a plurality of openings, the openings extending from a first surface of the support layer, through the support layer, to a second surface of the support layer opposite to the first surface, and being configured to allow abrasion dust to pass through the support layer; and wherein the fastening members are fixed on or in the support layer and protrude from the second surface thereof, and are configured to temporarily fix the abrasive article to a surface including complementary fastening members of the QRS;

an electrically and thermally conductive coating covering both the support layer and the fastening members, and

a deposit with abrasive particles covering at least part of the first surface of the support layer, and being thermally connected to the coating;

wherein the coating forms thermally conductive paths from the abrasive particles on the first surface, via the openings, to the fastening members on the second surface of the support layer.

8. The abrasive article according to claim 7, wherein the support layer is an open mesh formed of multiple strands that mutually cross or intersect, and which define the openings in between.

9. The abrasive article according to claim 8, wherein the fastening members are integrated with the strands of the mesh so that the fastening members and strands engage along contact surfaces, and so that the coating covers and extends in a continuous manner across both the mesh and the fastening members, without extending directly in-between the fastening members and the strands along the contact surfaces.

10. The abrasive article according to claim 7, wherein the fastening members are formed by filaments having base portions that are mechanically fixed to or incorporated into the support layer, for instance embedded in or intertwined with strands of the mesh support layer according to claim 8 or 9.

11. The abrasive article according to claim 8, wherein the mesh is formed of woven, braided, or knitted strands.

12. The abrasive article according to claim 8, wherein the mesh is an extruded mesh, a punched mesh, or a slit-and-expanded material mesh.

13. The abrasive article according to claim 8, wherein the mesh is flexible.

14. The abrasive article according to claim 8, wherein the mesh is made of polyester fibres.

15. The abrasive article according to claim 7, wherein the openings in the support layer have an open area in a range of 20%-60% of the surface area of the abrasive article.

16. The abrasive article according to claim 7, wherein the openings in the mesh are provided in a regular pattern, the pattern having one or more of:

two-dimensional periodicity;

mirror symmetry;

discrete rotational symmetry.

17. The abrasive article according to claim 7, being a rotationally symmetric pad, for instance a circular pad, and wherein the support layer and openings have discrete rotational symmetry.

18. The abrasive article according to claim 7, wherein the coating is a metal coating consisting essentially of nickel or nickel-based alloy.

19. The abrasive article according to claim 7, wherein the abrasive particles consist essentially of diamond or cubic boron nitride.