Abrasive tools having a permeable structure

• US 20070074456A1
• Filed: 09/30/2005
• Published: 04/05/2007
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Saint-Gobain Abrasives Incorporated (Compagnie De Saint-Gobain)
• Original Assignee: Saint-Gobain Abrasives Incorporated (Compagnie De Saint-Gobain)
• Inventors: Jeevanantham, Muthu, Orlhac, Xavier, Krause, Russell, Wu, Mianxue
• Granted Patent: US 7,722,691 B2
• Time in Patent Office: Days
• US Class Current: 51/307
• CPC Class Codes: B24D 18/0009 using moulds or presses
• CPC Class Codes: B24D 3/00 Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide

Abstract

A bonded abrasive tool comprises a blend of abrasive grains and a bond component. The blend of abrasive grains comprises a filamentary sol-gel alumina abrasive grain and agglomerated abrasive grain granules. A bonded abrasive tool comprising an agglomerate of filamentary sol-gel alumina abrasive and non-filamentary abrasive grains, and a bond component is also disclosed. The filamentary sol-gel alumina abrasive grain has a length-to-cross-sectional-width aspect ratio of greater than 1.0. The agglomerated abrasive grain granules comprise a plurality of abrasive grains held in a three-dimensional shape by a binding material. A method of making such a bonded abrasive tool as described above is also disclosed.

Claims

1. A bonded abrasive tool comprising:

a) a blend of abrasive grains including;

i) a filamentary sol-gel alumina abrasive grain having a length-to-cross-sectional-width aspect ratio of greater than about 1.0, or an agglomerate thereof; and

ii) agglomerated abrasive grain granules including a plurality of abrasive grains held in a three-dimensional shape by a binding material;

b) a bond; and

c) at least about 35 volume percent porosity.

2. The bonded abrasive tool of claim 1, wherein the bonded abrasive tool has a structure permeable to fluid flow.

3. The bonded abrasive tool of claim 2, wherein the blend includes about 5-90 percent of the filamentary sol-gel alumina abrasive grain by weight with respect to the total weight of the blend.

4. The bonded abrasive tool of claim 3, wherein the filamentary sol-gel alumina abrasive grain has an aspect ratio of at least about 4:

1 and comprises predominantly alpha alumina crystals having a size of less than about 2 microns.

5. The bonded abrasive tool of claim 3, comprising about 35-80 volume percent total porosity.

6. The bonded abrasive tool of claim 5, wherein at least about 30 volume percent of the total porosity is interconnected porosity.

7. The bonded abrasive tool of claim 1, wherein the agglomerated abrasive grain granules comprise at least one abrasive grain type selected from the group consisting of fused alumina, non-filamentary sintered sol-gel alumina, sintered bauxite, cofused alumina-zirconia, sintered alumina-zirconia, silicon carbide, cubic boron nitride, diamond, flint, garnet, boron suboxide, aluminum oxynitride, and combinations thereof.

8. The bonded abrasive tool of claim 7, wherein the agglomerated abrasive grain granules comprise fused alumina.

9. The bonded abrasive tool of claim 1, wherein the bond component and binding material each independently comprise an inorganic material selected from the group consisting of ceramic materials, vitrified materials, vitrified bond compositions and combinations thereof.

10. The bonded abrasive tool of claim 9, wherein the binding material is a vitrified bond composition comprising a fired oxide composition of SiO₂, B₂O₃, Al₂O₃, alkaline earth oxides and alkali oxides.

11. The bonded abrasive tool of claim 1, wherein the agglomerated abrasive grain granules have a size dimension in a range of between about two and twenty times larger than the average grit size of the abrasive grains.

12. The bonded abrasive tool of claim 11, wherein the agglomerated abrasive grain granules have a diameter in a range of between about 200 and about 3,000 micrometers.

13. The bonded abrasive tool of claim 1, wherein the bond component is a resin bond.

14. The bonded abrasive tool of claim 3, wherein the blend of abrasive grains comprises an agglomerate of the filamentary sol-gel alumina abrasive grain where the agglomerate comprises a plurality of grains of the filamentary sol-gel alumina abrasive grain and a second binding material, and where the plurality of filamentary sol-gel alumina abrasive grains are held in a three-dimensional shape by the second binding material.

15. The bonded abrasive tool of claim 14, wherein the agglomerate of the filamentary sol-gel alumina abrasive grain further comprises a secondary non-filamentary abrasive grain, where the secondary non-filamentary abrasive grain and filamentary sol-gel alumina abrasive grain are held in a three-dimensional shape by the second binding material.

16. The bonded abrasive tool of claim 15, wherein the agglomerate of filamentary sol-gel alumina abrasive grain includes about 5-95 percent by weight of the filamentary sol-gel alumina abrasive grain with respect to the total weight of the agglomerate.

17. A bonded abrasive tool comprising:

a) an agglomerate comprising;

i) a filamentary sol-gel alumina abrasive grain having a length-to-cross-sectional-width aspect ratio of greater than about 1.0;

ii) a non-filamentary abrasive grain; and

iii) a binding material, wherein the non-filamentary abrasive grain and filamentary sol-gel alumina abrasive grain are held in a three-dimensional shape by the binding material;

b) a bond; and

c) at least about 35 volume percent porosity.

18. The bonded abrasive tool of claim 17, wherein the bonded abrasive tool has a structure permeable to fluid flow.

19. The bonded abrasive tool of claim 18, wherein the non-filamentary abrasive grain comprises at least one abrasive grain type selected from the group consisting of fused alumina, non-filamentary sintered sol-gel alumina, sintered bauxite, cofused alumina-zirconia, sintered alumina-zirconia, silicon carbide, cubic boron nitride, diamond, flint, garnet, boron suboxide, aluminum oxynitride, and combinations thereof.

20. The bonded abrasive tool of claim 18, wherein the agglomerate includes about 5-90 percent of the filamentary sol-gel alumina abrasive grain by weight with respect to the total weight of the agglomerate.

21. The bonded abrasive tool of claim 20, comprising about 35-80 volume percent total porosity.

22. The bonded abrasive tool of claim 21, wherein at least about 30 volume percent of the total porosity is interconnected porosity.

23. A method of making a bonded abrasive tool, comprising:

a) forming a blend of abrasives, the blend comprising;

i) a filamentary sol-gel alumina abrasive grain having a length-to-cross-sectional-width aspect ratio of greater than about 1.0 or an agglomerate thereof; and

ii) agglomerated abrasive grain granules comprising a plurality of abrasive grains held in a three-dimensional shape by a binding material;

b) combining the blend of abrasives and a bond component;

c) molding the combined blend of abrasives and bond component into a shaped composite comprising at least about 35 volume percent porosity; and

d) heating the shaped composite to form the bonded abrasive tool.

24. The method of claim 23, wherein the bonded abrasive tool comprises about 35-80 volume percent total porosity.

25. The method of claim 24, wherein the bonded abrasive tool comprises at least about 30 volume percent of the total porosity is interconnected porosity.

26. The method of claim 23, wherein the melting temperature of the binding material is in a range of between about 800°

C. and about 1300°

C.

27. The method of claim 23, wherein the agglomerated abrasive grain granules are sintered agglomerated granules.

28. The method of claim 27, further comprising the steps of making the sintered agglomerated granules:

feeding the abrasive grains and binding material into a rotary calcination kiln at a controlled feed rate;

rotating the kiln at a controlled speed;

heating the mixture at a heating rate determined by the feed rate and the speed of the kiln to a temperature in a range of between about 80°

C. and about 1,300°

C.;

tumbling the grain and the binding material in the kiln until the binding material adheres to the grains and a plurality of grains adhere together to create the sintered agglomerated granules; and

recovering the sintered agglomerated granules from the kiln.

29. The method of claim 28, wherein the step of feeding the abrasive grains and binding material into a rotary calcination kiln includes the steps of making a substantially uniform mixture of the abrasive grains and the binding material and then feeding the mixture into the rotary calcination kiln.