Grinding wheel for roll grinding and method of roll grinding

1. A method of grinding a ferrous roll comprising:

rotating a grinding wheel on a machine spindle to form a rotating grinding wheel;

rotating a ferrous roll to form a rotating roll surface;

wherein the angle between the grinding wheel rotational axis and ferrous roll rotational axis is less than about 25 degrees;

bringing the rotating grinding wheel into contact with the rotating roll surface and

traversing the rotating grinding wheel across an axial roll length of the rotating roll surface, while maintaining a ratio of axial taper tolerance (TT) to radial wheel wear compensation (WWC) of greater than 10; and

grinding the roll surface while varying at least one or both of a grinding wheel rotational speed and a mill roll rotational speed at amplitude of +/−1 to 40% with a period of 1 to 30 seconds.

2. The method of claim 1 , wherein the wheel rotational speed is varied at an amplitude of +/−20% with a period of less than 5 seconds.

3. The method of claim 1 , wherein a ratio of the grinding wheel rotational speed to the mill roll rotational speed is not constant during the grinding.

4. The method of claim 1 , wherein:

the roll is ground to a surface roughness Ra of less than 3 micrometer;

the roll surface is substantially free of thermal degradation of the roll material; and

the grinding wheel includes a grinding wheel bond system comprising a superabrasive layer, wherein a superabrasive material of the superabrasive layer has a Knoop hardness greater than 3000 KHN.

5. The method of claim 4 , wherein the superabrasive material comprises one or more of natural diamond, synthetic diamond, or cubic boron nitride.

6. The method of claim 4 , wherein the superabrasive layer further comprises a secondary abrasive with a Knoop hardness less than 3000 KHN.

7. The method of claim 1 , wherein a ratio of TT to WWC is greater than 25.

8. The method of claim 1 , wherein the roll has a diameter of at least 18 inches and a length of at least 2 feet.

9. The method of claim 4 , wherein the superabrasive material comprises cubic boron nitride, and the amount of cubic boron nitride in said grinding wheel bond system is in the range of 10 to 60 volume %.

10. The method of claim 4 , wherein the grinding wheel bond system further comprises a vitrified bond comprising of at least one or more of clay, feldspar, lime, borax, soda, glass frit, or fritted materials.

11. The method of claim 4 , wherein the grinding wheel bond system further comprises a resin bond system comprising at least one or more of a phenolic resin, an epoxy resin, or a polyimide resin.

12. The method of claim 1 , wherein:

the grinding wheel is rotated from 3600 to 12000 fpm;

the grinding is carried out at a G ratio of at least 20;

the grinding wheel has an axis of rotation that is substantially parallel to the rotational axis of the roll; and

the grinding wheel removes a stock grind amount of less than about 0.2 mm from a minimum worn roll diameter.

13. The method of claim 1 , wherein a material from the ferrous roll is removed at a rate greater than 2 cc/min.

14. The method of claim 1 , wherein a material from the ferrous roll is removed at a rate greater than 20 cc/min.

15. The method of claim 1 , wherein a material from the ferrous roll is removed at a rate greater than 35 cc/min.

16. A method, comprising:

rotating a grinding wheel to form a rotating grinding wheel, wherein the rotating grinding wheel comprises cubic boron nitride in a vitrified bond system;

rotating a ferrous roll to form a rotating roll surface, wherein the angle between the grinding wheel rotational axis and ferrous roll rotational axis is less than about 25 degrees;

contacting the rotating grinding wheel with the rotating roll surface and traversing the rotating grinding wheel across an axial roll length of the rotating roll surface while

maintaining a ratio of axial taper tolerance (TT) to radial wheel wear compensation (WWC) of greater than 10; and

grinding the roll surface while varying at least one or both of a grinding wheel rotational speed and a mill roll rotational speed at amplitude of +/−1 to 40% with a period of 1 to 30 seconds.

17. The method of claim 16 , wherein the wheel rotational speed is varied at an amplitude of +/−20% with a period of less than 5 seconds.

18. The method of claim 16 , wherein the grinding wheel rotational speed is varied independently from the mill roll rotational speed.

19. The method of claim 16 , wherein the grinding wheel rotation speed is varied simultaneously with the mill rotational speed.

20. The method of claim 16 , wherein the vitrified bond system comprises at least one or more of clay, feldspar, lime, borax, soda, glass frit, or fritted materials.

21. A method to suppress chatter in a roll grinding process, comprising:

rotating a grinding wheel to form a rotating grinding wheel;

rotating a ferrous roll to form a rotating roll surface, wherein the angle between the grinding wheel rotational axis and ferrous roll rotational axis is less than about 25 degrees;

contacting the rotating grinding wheel with the rotating roll surface and traversing the rotating grinding wheel across an axial roll length of the rotating roll surface while

maintaining a ratio of axial taper tolerance (TT) to radial wheel wear compensation (WWC) of greater than 10; and

grinding the roll surface while varying at least one or both of a grinding wheel rotational speed and a mill roll rotational speed at amplitude of +/−1 to 40% with a period of 1 to 30 seconds.

22. The method of claim 21 , wherein the grinding wheel comprises at least one or more of an abrasive having a Knoop hardness less than about 3000 KHN or a superabrasive having a Knoop hardness greater than about 3000 KHN.

23. The method of claim 21 , wherein a ratio of the grinding wheel rotational speed to the mill roll rotational speed is not constant during the grinding.