Aggregate abrasive grains for abrading or cutting tools production

a technology of aggregate abrasives and cutting tools, which is applied in the direction of manufacturing tools, grinding devices, other chemical processes, etc., can solve the problems of segregation between metal powder and pellets, negative affecting the cutting or abrading performance of tools, and uneven formation of granules

Inactive Publication Date: 2014-02-27
SHERIDAN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This method enables the formation of aggregate abrasive grains with improved uniformity and retention, enhancing the cutting or abrading performance of tools by ensuring each grain has a single core particle and preventing direct contact between abrasive particles, thus improving tool efficiency and longevity.

Problems solved by technology

As a matter of fact, this negatively affects the cutting or abrading performance of the tool.
Those skilled in the art are aware that mixing the pellets with metal powder may cause the problem of segregation between the metal powder and the pellets.
As regards the “sausage” method, the granules that are formed are not uniform so that a step of selecting granules of substantially the same size is requires.
This method has the further drawbacks that each granule formed does not necessarily contain one (and only one) core particle and that the core particle is not necessarily positioned centrally within its shell.
Thus 2008 / 0017421 A1 does not enable the production of pellets having a single abrasive particle in the centre.
Nevertheless, one already encounters serious problems with the above methods as the ratio exceeds 1 / 11.
Another problem arises if the abrasive particles to be coated and the particles used as the surrounding material exhibit very different densities (e.g. diamond: 3.5 g / cm3, coarse WC: 15.8 g / cm3, fused WC: 16.4 g / cm3) because the particles tend to segregate.
The difficulties caused by density differences are particularly pronounced in the Fuji-Paudal method.

Method used

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  • Aggregate abrasive grains for abrading or cutting tools production
  • Aggregate abrasive grains for abrading or cutting tools production
  • Aggregate abrasive grains for abrading or cutting tools production

Examples

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example 1

[0051]Aggregate abrasive grains were formed according to the method described above using diamond particles (MBS 960, −20 / +25 mesh) as core particles and cast tungsten carbide particles with diameters from 75 to 150 μm as peripheral particles. The diamonds were spray-coated with an adhesive composed of polyvinyl butyral dissolved in methanol. The adhesive was obtained by using 425 ml of methanol per 100 g of polyvinyl butyral. After the diamonds had been dropped into a layer of cast tungsten carbide particles and covered with further such particles, they were dried during 20 minutes at 60° C. The consolidated aggregate particles were then separated from the excess tungsten carbide particles by sieving.

example 2

[0052]In this example, SDB 1100, −30 / +40 mesh diamonds were used as core particles and SDB 1100, −50 / +60 mesh diamonds as peripheral particles. The core particles were spray-coated with an adhesive composed of polyvinyl butyral dissolved in methanol. The adhesive was obtained by using 1100 ml of methanol per 57 g of polyvinyl butyral. The aggregate particles were consolidated in during 20 minutes at 60° C. and separated from the excess −50 / +60 mesh diamonds.

[0053]The consolidated aggregate particles were thereafter fed into a rotary mixing container, where the amount of aggregate particles and the rotational speed of the mixing container were chosen such that the aggregate particles rolled on themselves under the action of gravity. A mixture of a powder of carbonaceous material and a binding agent was then progressively sifted onto the aggregate particles, while a fine spray of solvent for the latter binding agent was directed thereto using a spray nozzle. The powder of carbonaceous...

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Abstract

Aggregate abrasive grains are formed for use in the production of abrading or cutting tools by providing abrasive core particles, coating these particles with adhesive, and separately dropping the adhesive coated core particles onto a layer of abrasive peripheral particles. The method further includes covering the dropped core particles with further peripheral particles, in a way to form aggregate particles, each of which includes a core particle having peripheral particles attached to it. The adhesive includes a binding agent and a solvent for the binding agent. Finally, the aggregate particles are consolidated by causing the solvent to evaporate, i.e. by letting the adhesive set.

Description

TECHNICAL FIELD[0001]The present invention generally relates to a method of formation an aggregate abrasive grain for use in the production of abrading or cutting tools. In the following, “aggregate abrasive grain” or “aggregate grain” designates an abrasive or superabrasive particle (“core particle”), which further abrasive or superabrasive particles (“peripheral particles”) are attached to by chemical bonds or mechanically. Such aggregate grains are useful, in particular, for facilitating the production of abrading or cutting tools, e.g. drill bits, inserts or cutting elements for drill bits, etc. as well as for improving the quality of such tools.BACKGROUND[0002]Tools for cutting and / or abrading are conventionally fabricated of a suitable matrix material with minute abrasive grains, such as diamonds, embedded within the matrix material. Basically, such tools are formed by conventional powder metallurgical techniques, wherein the abrasive grains are initially mixed with the matrix...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): B24D3/00C09K3/14
CPCC09K3/1436B24D3/008B24D18/00
InventorSHERIDAN
OwnerSHERIDAN