EP0794850B1 - Abrasive tool, cutting tool or the like, and method for making same - Google Patents

Abstract

An abrasive tool and a method for its manufacture is provided in which the structural body of the tool, including both the central core and the outer, abrasive-containing portion, is fabricated of a homogeneous material, with abrasive particles dispersed throughout the consumable abrasive-containing portion to grindingly remove workpiece material during rotation of the structural body. A porous lattice of diamond grains encased in a cladding material is first formed by sintering as a continuous annulus or as arcuate segments. The skeletal lattice is then placed in a mold and a homogeneous material in liquid state is introduced into the mold to simultaneously form the central core and to flow into at least a portion of the porous lattice of clad diamond grains to provide an integrally molded, unity tool when the core material solidifies.

Description

The present invention relates to a abrasive tool, for cutting, drilling or grinding construction materials including a support associated with or provided with a structure, positioning grains of diamond. The invention also relates to a method for manufacture of an abrasive tool. A process according to the preamble is known, for example, from WO-A-9009620.

The known abrasive or cutting tool of the type above, when it is a cutting disc, is consists of a circular sheet steel support and a metallic structure formed by a succession of segments, teeth or rim or continuous diamond crown fixed, for example, by soldering, welding or by sintering on the periphery of this sheet.

In these known cases, the structure metallic consists of a body sintered by the powder metallurgy incorporating diamond grains. In construction applications covered by the present invention, these grains generally have a size ranging from 20 to 80 US-MESH (ISO 6106 / FEPA or ANSI B74-16 standard).

The cost price of such a known tool is relatively high as well due to the cost of products used only specialized labor required for fixing the aforementioned diamond part on the sheet or that of the large number of manufacturing stages necessary for its manufacture.

From this follows that the costs investment in a tool like this is justified only for professionals who make it relatively intense use.

For occasional use, it there are very inexpensive abrasive tools. In the case discs, abrasive particles, generally formed of silicon carbide, extend over the entire surface of the disc and are incorporated into a phenolic resin reinforced with synthetic fibers. However, these disks have the disadvantage that the abrasive part is very weak and wears out quickly. So the diameter of such a disc rapidly decreases during use and therefore requires replacement frequent during relatively intensive use.

Furthermore, as a result of these discs are not very resistant, a significant risk exists that they will crack and burst, thereby injuring possibly the user.

Another disadvantage, not negligible in some cases is that the user never has a constant and optimal depth of cut for a same disc as a result of this rapid wear. Thereby, the replacement frequency is all the higher.

In addition, there are also sawing or grinding tools in which the structure bearing diamond grains at the periphery of the tool is made of a lattice fixed in a resin. Such tools especially have the disadvantages of having no only a relatively short lifespan but also the limitation of being used exclusively with a refrigerant to avoid degradation of said resin, the latter generally being of low resistance thermal. Dry use is therefore not possible with this type of tool.

In still other known tools the structure bearing the grains only exists virtually. The grains diamonds have been previously coated with a layer microscopic nickel of maximum 20 microns having the particularity of better adhering to said resin. From this done, a lattice-like structure does not turn out necessary. This design remains limited to tools exclusively for grinding or grinding, where friction forces transmitted in diamond remain well in below the forces generally encountered during sawing. In these tools the grain size is less than 200 microns and is commonly between 100 and 400 US-MESH.

One of the essential purposes of this invention is to remedy the disadvantages of these types known abrasive tools and to present an abrasive tool, cutting or the like which may be suitable for both intensive use only for relatively few uses frequent, especially thanks to its manufacturing price relatively reduced compared to its lifespan, and which, more, assures the user performance and safety, especially when this tool is used dry. In addition, the invention allows the user to have a tool abrasive with continuous depth of cut substantially constant.

To this end, according to the invention, the support consists essentially of a molded body, cast, injected or pressed into a material having a point higher than the operating temperature and below 1000 ° C and incorporating a structure device itself carrying and positioning the grains diamond abrasives. These are at least distributed following the direction in which the tool should be applied to the material to be worked, the structure with open spaces, recesses or pores and being at least partially embedded in the aforementioned material, which at least partially penetrates these interstices of so as to secure the structure to the support and to transmit a torque from a motorized axis. The diamond grains advantageously have a size between 20 and 80 US-MESH and preferably between 30 and 60 US-MESH.

Advantageously, the aforementioned structure includes an assembly of particles each formed diamond grains coated with a binding envelope, these particles being fixed, directly or not, one to others in such a way as to let subsist between them interstices into which matter enters above to form an anchor with the aforementioned support.

La figure 1 est une vue latérale d'un disque diamanté connu.

La figure 2 est, à plus grande échelle, une vue latérale analogue d'une partie de la périphérie du disque montré à la figure 1.

La figure 3 est une vue latérale d'un disque abrasif suivant une première forme de réalisation de l'invention.

La figure 4 est, à plus grande échelle, une vue analogue d'une partie du bord périphérique de cette première forme de réalisation dans laquelle la matière constituant le support du disque a été omise.

La figure 5 est une vue en perspective d'un foret suivant l'invention.

La figure 6 est une vue en perspective d'une meule de ponçage suivant l'invention.

La figure 7 est une vue en coupe et perspective partielle d'une forme de réalisation particulière supplémentaire d'outils diamantés suivant l'invention.

Other details and particularities of the invention will emerge from the description given below, by way of nonlimiting example, of some particular embodiments of the invention with reference to the appended drawings.

Figure 1 is a side view of a known diamond disc.

FIG. 2 is, on a larger scale, a similar side view of part of the periphery of the disc shown in FIG. 1.

Figure 3 is a side view of an abrasive disc according to a first embodiment of the invention.

Figure 4 is, on a larger scale, a similar view of a portion of the peripheral edge of this first embodiment in which the material constituting the support of the disc has been omitted.

Figure 5 is a perspective view of a drill according to the invention.

Figure 6 is a perspective view of a sanding wheel according to the invention.

Figure 7 is a partial sectional and perspective view of an additional particular embodiment of diamond tools according to the invention.

In these different figures, the same reference figures relate to similar elements or identical.

Figure 1 shows a first type known from abrasive, cutting or cutting discs comprising a circular support 1, formed of a sheet of steel, and a metallic structure 2, formed by a succession of diamond segments fixed by brazing, welding or sintering on the periphery of this sheet. Such a disc is generally called "diamond disc".

As is more evident from the Figure 2, in these segments 2, diamond grains 3 are held in a metal matrix 4 formed by sintering of metallic powders. Such a matrix including the diamond grains 3 rigidly positioned one by compared to others in it, of which the segments 2, is generally called "concretion" and is attached to the periphery of the circular support 1. This fixation can be achieved by various methods assembly.

Thus, the aforementioned concretions, forming segments 2, can either be formed in situ by sintering on the periphery of the support 1, either to be preformed sintered and fixed on the periphery of the support 1 by soldering or welding, or again by means mechanical. The junction between support 1 and the various segments 2 is indicated by the reference 6 'in the figure 2. The circular support 1 has a central bore 5 for driving the disc around of its axis.

The height or thickness of the segments 2 in radial direction of support 1 is traditionally less than 10 mm. These segments 2 are caused to wear out sawing by slow abrasion of the metal matrix 4, while their cutting power is constantly regenerating by successive appearance of layers of diamond grains 3. This type of disc is renowned for its performance cut, wet or dry, in virtually all building materials, and generally in use on portable or table-top machines. The diameters generally range from 100 to 500 mm.

It should also be noted that in the embodiment shown in Figure 1, notches 11 are provided between two consecutive segments 2.

However, instead of a succession of diamond segments, it is possible to plan at the periphery of this sheet a diamond rim or crown keep on going.

Figure 3 is a representation schematic of a cutting disc according to the invention. The essential characteristic of the invention resides in the design and construction of structure 2 where the 3 diamond grains will have the best possible adhesion to take up the constraints induced by the work of chopped off. According to the invention, the structure 2 can be obtained prior to the molding of the support 1 by agglomeration of abrasive particles 8 containing the diamond grains 3.

The dimensions and number of these interstices, recesses or pores 9 are in particular function of the nature, more particularly of the viscosity, of the material 6 of which the support 1 is made up. according to the invention, the support 1 consists of a material 6 molded, cast, injected or pressed having a melting point higher than the tool temperature during of its use and less than 1000 ° C. So the abrasive particles 8 are embedded in the material of the support 1 for example by overmolding in such a way that this material 6, in the liquid or pasty state, can penetrate sufficiently into these interstices, recesses or pores 9 to obtain a rigid and reliable fixing between the support and structure 2 formed essentially by these abrasive particles 8 and especially to allow transmit a sufficiently large torque from the support 1 with diamond grains 3 when using this tool.

For example, the volume part occupied by structure 2 on the periphery amounts to 60% while material 6 has a higher penetration rate 90% in the recesses, pores or interstices 9. These diamond grains can be agglomerated on a trellis or on an openwork plate by brazing, sintering or depositing electrolytic.

Advantageously, for a question of cost and performance at work, the structure 2 can be obtained directly by coating each diamond grain 3 (as shown in Figure 5), or a whole of such grains by a layer or envelope coating and bonding 7. These coating methods are known so there is no need to describe them here. The particles 8 obtained by coating grains of diamonds 3 are bonded together by brazing, bonding or sintering in shape and size structure 2, that is, making sure that recesses, pores or interstices 9 remain between the agglomerated particles 8.

Another embodiment of the structure 2 is obtained by agglomeration by the same diamond wire means assembled in the directions desired, so as to form for example a trellis at network in two or more layers of such wires. These sons can be obtained by extruding metallic powders or other premixes with diamond grains and a plasticizer allowing passage through dies adequate.

Any other technique related to injection molding is also applicable to obtain derived forms, the particle size 8 obtained must be at least 300 microns. In addition, the average diameter of the diamond grains itself is preferably greater than 200 µm. So the thickness of the layer of coating 7 is at least 50 μm.

Yet another form of the invention, structure 2 can be produced in situ by at the same time as the operation of molding, casting, injection or pressing of the support 1 of the tool, at the provided that the materials selected from layers 7 for coating or for the formation of grain agglomerates diamond 3 are compatible to react chemically with the material 6 of the support 1. Reaction is understood to mean chemical, the formation of a 7 'interface between two parts which is likely to create sufficient adhesion of one in relation to the other. So if for example the layer 7 is formed of a metal, such as nickel, and that the material 6 of the support 1 is formed of another metal, such than aluminum, the 7 'interface is made of an alloy of these two metals.

Given the high concentration of particles 8 at the periphery of the tool, the in-situ chemical reaction forms a continuous network joining the particles together, thereby forming said structure 2.

It is understood that the characteristics thermo-mechanical materials used for training of layer 7 of the agglomerated particles 8 must be superior to the thermomechanical characteristics of materials 6 used for the production of support 1.

To do this, the present invention provides for the coating layer 7 of the diamond grains 3 is advantageously metallic of the iron, nickel type, cobalt, copper, zinc or their derived alloys if the material 6 of support 1 is a metal with a low melting point, such as aluminum, copper, zinc or their alloys respective, such as alpax, bronze, brass or zamak, or possibly a high performance polymer of the type polyimide, polysulfone or PEEK (polyetheresterketone). This layer 7 will either be metallic of the same type as above, either based on polymers or liquid crystals of high thermo-mechanical performance, such as polyimides, polysulfones, PEEK, when support 1 will consist of a less sophisticated polymer, such as polyesters, epoxy possibly reinforced with glass fibers, aramid or carbon.

Figure 4 refers to a disc diamond whose rigid structure formed of said particles 8 extends in a crown around the periphery of the support 1. In addition, this structure has a wavy shape in a direction tangential to this periphery, that is to say in the direction of the couple applied to the disc when in use.

However, as shown in detail in the FIG. 5, the material 6, from which the support 1 is formed, does not not only penetrates into the recesses 9 between the particles 8 but also completely fills the hollows 10 created laterally in the rigid structure 2 by this wavy shape. This further improves the fixation from the latter to support 1.

The width of the structure 2 carrying the diamond grains 3 can be variable and be basically a function of the desired service life of the tool and depth of cut required. The invention allows a large choice of this width, for example from 1 to 25 mm.

Furthermore, instead of providing for a continuous diamond crown, as in the shape of realization shown in figure 4, it is possible to form successive diamond segments 2 separated by notches 11 possibly penetrating into the support 1, as in the case of the known diamond disc, shown in figure 1.

In general, to fix the support 1 to the diamond structure 2 thus obtained, the latter is placed motionless in a suitable mold, not shown in the figures, and we inject, pour or press the material 6 from which the support is formed in this mold of in such a way that this material envelops at least partially structure 2 and enters the interstices 9 of this structure 2 thus making it possible to make the two parties intimately united.

Molding techniques are known in industrial practices. When the support 1 of the tool is metallic, preferably use the methods of casting molten metal, sand, shell or pressure in permanent mold. When the tool support is made of synthetic materials thermosetting or thermoplastic, we will use preferably injection or molding methods adequate.

In order to increase the rigidity of the support 1, thus obtained, a steel frame 17 or a material synthetic can be placed beforehand in the mold used for support formation.

The fact that the support 1 is molded, cast or injected around this structure 2 allows for a large number of support types, both in terms of concerns the geometry of the support surfaces that the composition of it. Therefore, if the tool constitutes a cutting disc, it is possible to reduce the surface lateral contact of the latter with the material to be cut by providing for example an embossing on the lateral faces of the concretion. Likewise, fins 12 can be shaped in the lateral faces of the support 1, as shown in Figure 6, to provide ventilation for this last when using the disc, especially when dry.

It is also possible to train the tool body directly into the desired bore 5 of the support 1. It is still possible to make a support 1 whose bore 5 is located outside the plane thereof, so as to obtain thus a disc says: "with hub deported. "To achieve all these different forms of support 1, simply adapt the construction of the mold, in which the latter is formed by processes forming classics already cited above.

In addition, it is possible to mold a marking, references, the arrow of rotation etc ... in the mass of the support 1.

As shown in Figure 3, in which structure 2 is formed of a lattice, a certain quantity of carbide grains 13 or of another material hard can be mixed with the resin at the trellis 2 in the shape of a crown. These carbide grains 13 or this other hard material can be located in the mesh of the mesh 2. The quantity of carbide grains or of this other hard material represents at most ten times the volume of the quantity of diamond grains 3.

The addition of these grains in carbide or another hard material 13 can also take place during the constitution of the trellis 2 by brazing, sintering or collage to the latter. So these 13 grains could be diamond grain premixes 3 to be fixed on the trellis 2 and therefore be on the trellis 2 as well as in the meshes of it and even be spread across the support 1 in order to improve the longevity of the latter.

Regarding the composition of the support 1, also thanks to the very classic technique simple that can be applied for its training, it is possible to incorporate charges of an extremely varied and even very complex shaped inserts. So, it is possible to incorporate into it particles to high thermal conductivity so as to facilitate the evacuation of calories, generated during the effort of cutting when the tool is used dry, from the periphery towards the axis of the machine driving the tool.

Figure 7 is a schematic view in perspective of a drill with a metallic structure 2 containing 3 diamond grains, corresponding to the shape as shown in Figure 5. The material 6, of which the cylindrical support 1 of this drill is formed, is advantageously metal cast in a mold, not shown, in which the structure was already placed 2 positioning the diamond grains 3. This structure consists of a succession of platelets distributed to equal distances along the free circular edge of the support 1 and cast therein. In addition, this support 1 is provided, on the side opposite its free circular edge, an axial rod 14 for mounting the drill on a drive machine, not shown. This rod 14 is advantageously formed by an insert which, during the formation of the support 1, is molded by the material 6 of which the latter is constituted.

Figure 8 is a perspective view of a grinding wheel, according to the invention, which is manufactured from the same way as the disc according to figure 4 and the drill according to Figure 7 and whose fasteners 15 are also formed by inserts molded into the support 1.

Figure 9 concerns a form of special production of diamond tools, according to the invention, for milling or surfacing objects 16 made of stony or vitreous materials. As shown by this represents the working face, i.e. the structure 2 positioning the diamond grains, can be very shaped varied. Indeed, it can be not only flat, as in a cup wheel, or cylindrical as in a polishing roller but it can also have a concave or convex profile, such as for grinding wheels molding or polishing shoes.

Claims (20)

1. Abrasive, cutting or analogous tool comprising a body (1) associated with a structure (2) that positions grains of diamond (3), and designed to be applied according to a particular direction to a material to be worked (16), characterised in that said body (1) is essentially comprised of a material (6) which is moulded, cast, injected or pressed, having a melting point higher than the temperature of use of the tool and lower than 1000°C, said diamond grains (3) being distributed at least in the above-mentioned particular direction with reference to the structure (2), said structure presenting open interstices or pores and being at least partially submerged in said material (6), the latter penetrating at least partially into said interstices or pores, so as to form a solid bond with said structure (2) of the body (1) and to transmit a torque from the latter to the diamond grains (3).
2. Tool according to claim 1, characterised in that the above-mentioned structure (2) comprises a perforated plate or a lattice onto which said diamond grains (3) are rigidly fixed in a three-dimensional manner.
3. Tool according to claim 2, characterised in that said diamond grains (3) are fixed to said lattice or perforated plate (2) by brazing, adhesive-bonding, sintering or electrochemical deposition.
4. Tool according to claim 1, characterised in that said structure (2) comprises an assembly of particles (8) each formed of diamond grains (3) coated by a binding envelope (7), said particles (8) being attached to one another in such a way as to leave pores or interstices (9) between them, thus forming a structure (2) in the form of a skeleton incorporating the diamond grains (3).
5. Tool according to claim 4, characterised in that the above-mentioned envelope (7) is formed of or covered by a substance with a melting point higher than that of the material (6), such as a high-performance thermoplastic material of the type polyimide, polysulfone or polyetheresterketone (PEEK), or by a mixture of a metallic powder and an adhesive, said envelope having been submitted to sintering or polymerisation so as to immobilise the coated diamond grains (3) with respect to each other.
6. Tool according to one or other of claims 4 and 5, characterised in that the envelope (7) contains brazing material, with the coated diamond grains (3) being welded to each other by said brazing material.
7. Tool according to any of claims 4 to 6, characterised in that the above-mentioned structure (2) comprises an assembly of agglomerates of diamond grains (3).
8. Tool according to claim 1, characterised in that the above-mentioned structure (2) comprises threads that have been extruded or formed by injection from a mixture of diamond grains (3) and a substance with a melting point higher than that of the material (6) of the body (1).
9. Tool according to claim 8, characterised in that the above-mentioned structure (2) comprises a lattice (1) formed from threads that have been extruded or formed by injection.
10. Tool according to any of claims 1 to 9, characterised in that it comprises grains of carbide, in particular silicon carbide (13), representing not more than ten times the volume of the quantity of diamond grains (3).
11. Tool according to any of claims 1 to 10, characterised in that the above-mentioned material (6) of the body (1) is formed of a metal, such as aluminum, or an aluminum alloy, or bronze, or brass or an alloy of zinc.
12. Tool according to any of claims 1 to 10, characterised in that the above-mentioned material (6) of the body (1) is formed of a synthetic material, such as a thermoplastic or thermo-hardening material or a composite material, which may possibly be reinforced, for example by fibres.
13. Tool according to any of claims 1 to 12, characterised in that the body (1) contains an armature, such as a lattice of steel or synthetic fibres.
14. Tool according to any of claims 1 to 13, characterised in that the above-mentioned structure (2) projects with reference to the body (1).
15. Tool according to any of claims 1 to 14, characterised in that when the above-mentioned material (6) of the body (1) is formed of a resin, the latter is charged with abrasive grains (13), in particular silicon carbide.
16. Tool according to any of claims 1 to 15, characterised in that it is formed of an abrasive disk, a grinding wheel or a drill bit.
17. Tool according to any of claims 1 to 16, characterised in that the above-mentioned structure (2) positioning the diamond grains (3) presents a succession of projecting parts with respect to the direction of the torque applied during use of the tool.
18. Tool according to claim 17, characterised in that the structure (2) presents an essentially undulating form in the direction of the above-mentioned torque.
19. Process for the manufacture of an abrasive tool, in which a rigid structure (2) is first formed with open interstices or pores positioning the diamond grains (3) at least in the direction according to which said structure is designed to be applied to a material to be worked, characterised in that for the manufacture of an abrasive tool according to any of claims 1 to 18, a material (6) with a melting point higher than the temperature of the tool during use and lower than 1000°C is moulded, in particular by casting, pressing or injection, in such a manner that said material penetrates into said interstices or pores, thus forming a body (1) rigidly attached to said structure (2).
20. Process according to claim 19, characterised in that the above-mentioned structure (2) is fixed to an armature for the body (1), and that the material (6) destined to make up the body (1) is then formed around the structure (2) of said armature.

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