CS197890B1 - Binder for the active grinding layer of the grinding instruments - Google Patents

Description

The invention relates to a binder for an active abrasive layer of abrasive tools for grinding sintered carbides with diamond or hardened steel with cubic boron nitride produced by conventional powder metallurgy processes.

The existing binders for the active abrasive layer of the abrasive tools for grinding the abovementioned materials are mainly made of Cu-Sn based metal alloys with the addition of various alloying elements and non-metallic additives as fillers. These binders are characterized by high durability, but with different mechanical-physical properties depending on the type of alloying elements and fillers used. These are mainly the hardness, strength, abrasion resistance and thermal conductivity of the alloy, diamond wettability and shrinkage coefficient, which besides the grinding performance influence the use of diamond or cubic boron nitride, durability and self-sharpening properties of the abrasive tool. The abrasive tools are manufactured by conventional powder metallurgy processes, most often by pressing in heat-alloy alloys, sintering and hot pressing, while simultaneously sintering the active abrasive layer of the abrasive tool either directly to the support body or to a Cu-Sn based interlayer pre-sintered. to create the perfect connection.

Abrasives with existing bonding agents for the active abrasive layer exhibit poor properties, in particular self-sharpening, in the vast majority of cases. This means that the surface is active

The 197,890 abrasive layer of the abrasive tool is gradually clogged with its own metal components of the active abrasive layer along with the grinding products during the grinding process. The binder holds the grains of diamond or cubic boron nitride unsatisfactorily, which means that it does not appropriately release the blunted grains of the abrasive used and does not allow exposing new sharp grains. The grinding tool loses its grinding ability, decreases performance, increases cutting resistance and cutting temperature, which is the immediate cause of interruption of the grinding tool. The working ability of such an abrasive tool and diamond or cubic boron nitride needs to be restored, and this is most often done by cleaning or dressing free or bonded abrasive silicon carbide. Damage to defective products, eg due to overheating and cracking of components, is accompanied by diamond or cubic boron nitride losses during dressing. These losses are generally higher than the consumption of diamond or cubic boron nitride during the working process. In the manufacture of abrasive tools with an abrasive layer on the periphery, due to the considerable difference between the shrinkage coefficient of the existing binders for the active abrasive layer and the interlayer alloys, an imperfect bond between the abrasive layer and the interlayer is formed; such products, of which there is a certain proportion, shall be rejected as defective.

These disadvantages are overcome by a binder for the active abrasive return of abrasive tools, for grinding sintered carbides with diamond or hardened steel with cubic boron nitride, produced by conventional powder metallurgy processes according to the present invention, wherein the binder comprises 65 to 80 wt. % copper, 8 to 18 wt. % tin, 1 to 11 wt. % tungsten carbide, 2 to 8 wt. % amorphous coal and 3 to 10 wt. silicon dioxide.

The main advantages of the binder of the composition according to the invention are the high lifetime of the wheels, achieved by considerably less wear of the active abrasive layer, good grinding properties and high grinding performance. The binder composition according to the invention ensures that the abrasive tool has good eamo-abrasive properties during the working process. The grinding ability of the grinding tool does not decrease over time and its working ability does not have to be restored by dressing or cleaning. The abrasive tools whose active abrasive layer is made of the binder according to the invention operate at a constant high productivity and their use is very efficient and economical. Tests performed with grinding wheels manufactured using the binder of the present invention have shown a longer service life of 75-150% over grinding wheels commercially manufactured. Last but not least, the binder according to the invention, thanks to its considerably lower shrinkage coefficient against the existing binders, makes it possible, without technological problems, to produce large-diameter abrasive tools and an abrasive layer on the periphery with guaranteed quality of the active abrasive bond.

Grinding tools for grinding cemented carbides with diamond and quenched steel with cubic boron nitride binder bonded to the active abrasive layer of the present invention are manufactured by known powder metallurgy processes, in particular cold pressing, sintering in refractory alloy molds and subsequent hot-dipping. The bonding of the binder with diamond or cubic boron nitride results in an active abrasive layer which contains, in 100 parts by volume, 10 to 40 parts by volume of diamond or cubic boron nitride.

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Example 1

An example of a binder composition for the active abrasive layer of the abrasive tools of the invention: The binder comprises: 76 wt. % copper wt. % tin % tungsten carbide % amorphous coal wt. silicon dioxide

Said binder is produced by the described metallurgy processes. The binder according to the invention forms with the grains of diamond or cubic boron nitride an active abrasive layer which contains 25 parts by volume of diamond or cubic boron nitride in 100 volumes.

Example 2

Example of binder composition for the active abrasive layer of the abrasive tools according to the invention: The binder contains: 73 wt. % copper wt. tin 6 wt. % tungsten carbide 3 wt. % amorphous coal 6 wt. silicon dioxide

Said binder is produced by the powder metallurgy processes described above. The binder according to the invention forms with the grains of diamond or cubic boron nitride an active abrasion layer which contains, in 100 parts by volume, 30 parts by volume of diamond or cubic boron nitride.

Claims (1)

SUBJECT OF THE INVENTION Binder for an active abrasive layer of abrasive tools for grinding sintered carbides with diamond or hardened steel with cubic boron nitride, produced by conventional powder metallurgy processes, characterized in that it contains 65 to 80 wt. % copper, 8 to 18 wt. % tin, 1 to 11 wt. % tungsten carbide, 2 to 8 wt. % amorphous coal and 3 to 10 wt. silicon dioxide.