Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
  • B24D3/001—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as supporting member
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/922—Static electricity metal bleed-off metallic stock
  • Y10S428/9265—Special properties
  • Y10S428/932—Abrasive or cutting feature
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S76/00—Metal tools and implements, making
  • Y10S76/12—Diamond tools
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T407/00—Cutters, for shaping
  • Y10T407/27—Cutters, for shaping comprising tool of specific chemical composition
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
  • Y10T428/12576—Boride, carbide or nitride component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/30—Self-sustaining carbon mass or layer with impregnant or other layer

Definitions

• the present invention relates to a composite diamond abrasive product, its preparation process and the drilling or machining tools which are equipped with it.
• the present invention relates more particularly to abrasive composite products of the type having a part consisting of a "compact" containing diamond grains representing more than 80% by volume of the compact, each grain being bonded directly to its neighbors to present a rendered polycrystalline structure.
• integral with a hard and refractory support consisting essentially of a refractory carbide such as tungsten carbide.
• compact designates a sintered product consisting of grains linked together by bridges created by diffusion of material in the plastic state also called bridging. This plastic phase sintering is obtained at pressures and temperatures of the order of magnitude of the pressures and temperatures used for the synthesis of diamond grains.
• compact does not cover abrasive products comprising a support made of silicon carbide and of polycrystalline diamond, unsintered since not subjected, during manufacture, to temperatures and pressures sufficient to allow inter-growth of the diamond grains between them; in these products, the voids between grains of the composite are occupied by a compound of silicon and a metal such as nickel (US-A-4,241,135). These products exhibit poor abrasion resistance due to the absence of sintering.
• composite abrasive products (US-A-4 124 401) comprising a mass of polycrystalline diamond cemented by a binder containing silicon associated with a carbide support whose cohesion is ensured by cobalt.
• the absence of catalyst and sintering during the manufacture of the diamond mass prevents the formation of direct bridges between the diamond grains.
• FR-A-2 089 415 describes such a composite product consisting of a diamond compact on a tungsten carbide support; the compact and the carbide contain the same additive which can be cobalt, nickel or iron, this additive playing on the one hand the role of diamond catalyst solvent and on the other hand the role of carbide sintering binder.
• the object of the invention is to propose a diamond abrasive product on a brazable support which better meets those previously known than the requirements of the practice, in particular in that it comprises a compact in which the diamond grains are directly linked together by bridging, with increased thermostability.
• the Applicant has been able to determine that the use as a sintering binder of the tungsten carbide support of a nickel-chromium binder made it possible to obtain a composite diamond abrasive product having, compared to a similar product with tungsten carbide support with cobalt binder, equivalent abrasion resistance, increased thermostability and better resistance to corrosion of the carbide support; the product is, moreover, endowed with non-magnetic properties.
• the composite diamond abrasive product according to the invention is characterized in that the tungsten carbide support comprises a nickel-chromium binding phase.
• the active part contains at least 80% by volume of diamond.
• the diamond catalyst binder is a nickel-chromium binder originating from the binder phase of the support.
• the bonding phase of the support represents from 6 to 15% and preferably 10% by volume of the carbide.
• the relative proportions by weight of nickel and chromium of the binding phase vary in the range from 60 to 90% for nickel and from 40 to 10% for chromium.
• the new binding phase of the tungsten carbide support has the advantage of avoiding the oxidation problems which may arise at the support / active part interface during the diffusion of the binder in the diamond.
• the powder intended to constitute the active layer of the product is placed; it is a mixture of diamond grains with a grain size is chosen according to the application envisaged, this particle size being generally higher for drilling products than for machining products.
• diamond powder for products intended for machining, diamond powder can be used, the average grain size of which is between 0.5 and 30 microns; for products intended for drilling, an average grain size of 20 to 150 microns is preferred.
• This piece is generally cylindrical in shape. Its face in contact with the diamond mixture can be flat, hemispherical or grooved. The shape of this interface depends on the use of the composite.
• the cup is crimped onto the carbide pin so as to ensure a good seal and to avoid any pollution of the active part.
• the powdery components of the support are placed on the diamond powder layer, ie a tungsten carbide powder added with 6 to 15% of a nickel-chromium mixture, the relative proportions of nickel. and chromium which can vary in a range of 60 to 90% and 40 to 10%.
• a pressure transmitting material which can be chosen from sodium chloride, hexagonal boron nitride, talc or any other suitable material.
• the whole is placed in a metal or graphite resistor.
• the whole is surrounded by a material that transmits pressure and can form seals like pyrophyllite.
• This "cell” is then introduced into a press which can develop ultra-high pressures as well as high temperatures.
• the pressure is first applied in order to place itself in the thermodynamic stability zone of the diamond, then the heating (by resistance).
• the operating conditions are between 40 and 60 Kbars and 1,250 ° to 1,550 ° C for two to fifteen minutes; we prefer to work at 55 Kbars and 1400 ° C for three minutes.
• the diamond grains bond together and form a network of intergranular bridges, the voids between grains being filled by the binding phase.
• the compact After sintering under high pressure and temperature, the heating is stopped; allowed to cool to about 100 ° C and then the pressure is canceled.
• the compact is recovered after removing the various materials surrounding it.
• the metal cup is sandblasted or chemically etched with acid.
• the compact is then ground and rectified. It can be cut into precise shapes by EDM or laser.
• nickel-chromium mixture is added to the diamond grains of the active part.
• a layer of nickel-chromium alloy is placed in contact with the diamond grains; this layer can be placed between the diamond powder and the support or on the upper part of the active part.
• an intermediate layer (diffusion barrier) is placed between the active part and the support, consisting exclusively of diamond, tungsten carbide and / or nickel and chromium.
• the characteristics of the product thus obtained were determined compared to the standard product only available on the market, in which the binder of the tungsten carbide support is a cobalt binder.
• the first zone (100 to 200 m / min) represents the wear of the tool mainly due to degradation by abrasion. Diamond grains are torn from the tool one after the other. Wear measures this tendency to "loosen”, therefore the quality of the bridging of the diamond grains in the active part of the tool.
• the energy required for cutting is mainly used to remove material and to wear out the tool.
• the standard product and the product according to the invention have an equivalent low speed abrasion resistance (equivalent wear); - the second zone (200 to 250 m / min) is an intermediate zone between the first and the last zone described below; - the third zone (greater than 250 m / min) represents the wear of the tool mainly due to thermal degradation.
• the energy required for cutting which is used to remove material and to wear the tool (as in the first zone) also serves to heat the tool.
• the tool heats up a lot during work at these high speeds and the stresses due to this increase in temperature are preponderant: if the tool is not thermostable, thermochemical degradation is added to wear by abrasion: the expansion of the binder of the diamond part tends to weaken the intergranular bridging of the diamond and thus promote wear.
• the product according to the invention has a significantly lower wear than the standard product and this indicates better temperature resistance of the product of the invention (increased thermostability). In fact, thermochemical degradation is nonexistent. All of the cutting energy is transformed into material removal and heat which reduces the amount of abrasive degradation.
• the product according to the invention can therefore be used for dry machining.
• This characteristic is also very useful in the case of drilling tools: poor cooling of the drilling head is no longer a problem with the product according to the invention. This characteristic also allows the brazing of the tools according to a less restrictive operating process.
• the product according to the invention has the following characteristics: - equivalent abrasion resistance, - improved impact resistance, - increased thermostability, - non-magnetic qualities, - increased resistance to corrosion of the support.
• the corrosion resistance as well as the non-magnetic characteristics of nickel-chromium allow applications (press anvils) using an induction heating for example that the standard product does not offer.
• the invention also relates to tools equipped with the composite diamond abrasive product described above and, more specifically, tools intended for machining as well as drilling.
• a mixture constituting the active layer comprising 87% by weight of diamond grains having a semi-logarithmic distribution of maximum particle size 20 microns and 13% by weight of solvent-catalyst consisting of nickel and chromium powder with a particle size equivalent to that of diamond in a mass ratio of 80/20;
• a mixture constituting the diffusion barrier comprising 50% by volume of sintered tungsten carbide powder at 8% by weight of nickel with a particle size of 200/325 mesh (45 to 80 microns) and 50% by volume of diamond grains with a particle size 20 microns mixed with 13% by weight of nickel and chromium in a mass ratio of 40/60;
• the quantities of powder used are such that the thicknesses in the final sintered product are 0.7 mm for the active layer and 0.2 mm for the diffusion barrier.
• the tungsten carbide support is 0.9 mm thick.
• the cup is crimped onto the carbide pin, then the assembly is placed in a cell. This is subjected to a pressure of 60 kbar approximately and a temperature of 1500 ° C for three minutes. After cooling, the pressure is removed.
• the composite product recovered is then freed from its cup by chemical attack and then lapped on both sides. Shapes were then cut by electroerosion in this part and then mounted by brazing on a cutting tool support. After sharpening and polishing, the tools thus obtained were used for dry machining of tungsten deposition on cathodes for X-ray tubes. The results concerning the service life were two to three times greater than those obtained with conventional tools with cobalt bond.
• PVD Physical Vapor Deposition
• the thicknesses of the various layers are identical to those of Example 1.
• the cup is crimped on the pin, then the whole is placed in a cell. This is subjected to a pressure of approximately 60 kbar and a temperature of 1500 ° C. for three minutes. After cooling, the pressure is removed.
• the composite product is treated in an identical manner to that of Example 1.
• the cutting tools manufactured were used for the machining of agglomerated wood panels. The performance obtained was 10% higher than that of a part with a cobalt binder.
• the powder constituting the active layer comprising 100% of diamond grains with a particle size between 20 and 60 microns; - the mixture constituting the diffusion barrier comprising 50% by volume of powdered tungsten carbide powder 325 mesh (80 microns) and 50% by volume of diamond powder with particle size 60 microns; - a cylinder of tungsten carbide sintered to 11% by weight of binder phase consisting of nickel and chromium in a mass ratio of 85/15.
• the quantities of powder used are such that the thicknesses in the final sintered product are 0.7 mm for the active layer and 0.15 mm for the diffusion barrier.
• the tungsten carbide support is 7.4 mm thick.
• the assembly After crimping the cup onto the carbide pin, the assembly is placed in a subjected cell, after reaching a pressure of 55 kbar, at a temperature of 1400 ° C. for 3.5 minutes. After cooling, the pressure is removed.
• the composite product (picot) is then rid of its cup by sandblasting. It is then prowled on both sides and then ground to the standard diameter. It was then brazed on a drilling tool head.
• the powder constituting the active layer comprising 100% of diamond grains with a particle size between 20 and 60 microns in sufficient quantity to form a sintered layer of 0.7 mm; - a cylinder of tunsgtene carbide sintered to 11% by weight of binder phase consisting of nickel and chromium in a mass ratio of 85/15.
• This support is 3.2 mm.
• the manufacturing cycle was identical to that of the previous example.
• the manufactured pins made it possible to carry out comparative tests with the standard product with cobalt binder.
• a layer constituting the active part comprising 87% by weight of diamond grains with a particle size of 0.5 - 8 microns and 13% by weight of solvent-catalyst consisting of nickel and chromium powder with a particle size equivalent to that of diamond in a mass ratio of 85/15;
• a cylindrical pin terminated on one side by a half-sphere made of sintered tungsten carbide with 6% of Ni / Cr binding phase in a mass ratio of 85/15.
• the quantities of powder used are such that the respective thicknesses of the layers in the final sintered product are 0.3 mm, 0.4 mm and 0.5 mm on the support with a total height of 16 mm.
• the assembly After crimping the cup onto the carbide pin, the assembly is placed in a subjected cell, after reaching a pressure of 55 kbar, at a temperature of 1450 ° C. for four minutes. After cooling, the pressure is removed.
• the composite product thus produced (dome) is then freed from its cup by sandblasting. It is then rectified to the nominal diameter and then bevelled into a cone on the rear face.
• This product by its shape and its intermediate layers which act as a shock absorber, is particularly well suited to work involving shocks. It was mounted on a percussion tool. The results were 1.2 times better than the performance usually achieved with products having a cobalt binder.
• Example 5 The product identical to that obtained under the conditions of Example 5 was used at the periphery of the cones on the drill heads in tricones. The results were equivalent to those of the product of the prior art with a cobalt binder.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Polishing Bodies And Polishing Tools (AREA)
• Powder Metallurgy (AREA)

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• 1987
  • 1987-11-17 FR FR8716140A patent/FR2623201B1/fr not_active Expired - Fee Related
• 1988
  • 1988-11-16 US US07/272,163 patent/US5002828A/en not_active Expired - Fee Related
  • 1988-11-16 DE DE8888420383T patent/DE3864240D1/de not_active Expired - Fee Related
  • 1988-11-16 EP EP88420383A patent/EP0317452B1/de not_active Expired - Lifetime

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