Abrasive grain and grindstone
An abrasive grain 1 includes a crystal defect CD in its crystal structure CS. The crystal defect CD is formed by a laser irradiation.
1. A grindstone comprising diamond or CBN abrasive grains:
each of the abrasive grains includes one or more crystal defect or microscopic gap formed by a laser irradiation, the crystal defect or microscopic gap having a size of at least one micrometer and being capable of playing a role in self dressing of the grain, wherein the one or more crystal defect or microscopic gap exists at a transparent or translucent location inside a crystal structure.
2. A grindstone according to claim 1 , wherein:
the abrasive grains are mixed with laser non-irradiated abrasive grains.
3. A grindstone according to claim 1 , wherein:
layers with the abrasive grains and layers with laser non-irradiated abrasive grains are disposed on a surface of the grindstone.
4. A grindstone according to claim 2 , wherein:
the layers irradiated by the laser are disposed on a lateral surface of the grindstone.
5. A grindstone according to claim 4 , wherein:
the lateral surface is back-tapered.
6. A grindstone according to claim 3 , wherein:
the both type of layers are alternately disposed on a circumferential surface of the grindstone.
7. A grindstone according to claim 3 , wherein:
the both type of layers are alternately disposed on a lateral surface of the grindstone.
8. The grindstone according to claim 1 , wherein the laser is a Yb femto second fiber laser providing radiation with a pulse width of 500×10 −15 seconds, a central wavelength of 1040 nm and an energy of 1.5 micro Joules.
9. A grindstone comprising CBN abrasive grains:
each of the abrasive grains includes one or more crystal defect or microscopic gap formed by a laser irradiation, the crystal defect or microscopic gap having a size of at least a few hundred nanometers and being capable of playing a role in self dressing of the grain, wherein the one or more crystal defect or microscopic gap exists at a transparent or translucent location inside a crystal structure.
10. A grindstone according to claim 9 , wherein:
the abrasive grains are mixed with laser non-irradiated abrasive grains.
11. A grindstone according to claim 9 , wherein:
layers with the abrasive grains and layers with laser non-irradiated abrasive grains are disposed on a surface of the grindstone.
12. A grindstone according to claim 10 , wherein:
the layers irradiated by the laser are disposed on a lateral surface of the grindstone.
13. A grindstone according to claim 12 , wherein:
the lateral surface is back-tapered.
14. A grindstone according to claim 13 , wherein:
the both type of layers are alternately disposed on a circumferential surface of the grindstone.
15. A grindstone according to claim 11 , wherein:
the both type of layers are alternately disposed on a lateral surface of the grindstone.
16. The grindstone according to claim 9 , wherein the laser is a Yb femto second fiber laser providing radiation with a pulse width of 500×10 −15 seconds, a central wavelength of 1040 nm and an energy of 1.5 micro Joules.