Abrasion apparatus with an abrading belt and product chambers

1. An apparatus for abrading the surface of objects comprising:

a chamber defined by a plurality of walls, an abrasive surface defining one of said plurality of walls of said chamber, and drive means for moving the abrasive surface relative to the other of said plurality of walls of said chamber, said chamber having a cross-section that is asymmetric about a central line intersecting said abrasive surface;

whereby in use, said relative movement promotes circulation of the objects within the chamber, the asymmetric shape of said chamber minimizing regions of flow stagnation of the objects within the chamber.

2. The apparatus for abrading the surface of objects according to claim 1 , wherein the other of said plurality of walls of said chamber include two perpendicular side walls and at least two angled walls joining the perpendicular side walls and shaped to approximate a peripheral flow path of the objects within the chamber.

3. An apparatus as claimed in claim 1 , wherein the chamber comprises a substantially rectangular cross-section with at least one chamfered corner.

4. An apparatus as claimed in claim 1 , wherein the chamber comprises first, second and third wall portions, the first and second wall portions extending toward the abrasive surface, the second wall portion being spaced from the first wall portion in the direction of movement of the abrasive surface, the third wall portion joining the first and second wall portions and being non-planar to at least partially approximate the peripheral flow path of the objects within the chamber.

5. An apparatus as claimed in claim 4 , further comprising a gap between the second wall portion and the abrasive surface, the gap being dimensioned to selectively allow the abraded surface material to exit there through.

6. An apparatus as claimed in claim 5 , wherein the chamber further comprises an extension wall for directing the abraded surface material to a secondary outlet.

7. An apparatus as claimed in claim 1 , further comprising a drum member, wherein the abrasive surface comprises a surface of the drum member and the drive means effects rotation of the drum member.

8. An apparatus as claimed in claim 1 , wherein the abrasive surface is substantially vertical.

9. An apparatus as claimed in claim 8 , wherein the depth of the chamber increases and/or decreases between the inlet and the primary outlet.

10. A method of abrading objects to abrade surface material therefrom, the method comprising the steps of introducing the objects into a chamber having a first wall defined by an abrasive surface and a second wall bounding said chamber and defining a cross-section that is non-symmetric about a central line intersecting said abrasive surface, and

moving the abrasive surface relative to the second wall and chamber to promote circulation of the objects within the chamber about a flow path, the chamber being shaped such that regions of flow stagnation within the chamber and outside said flow path are minimized.

11. A method as claimed in claim 10 , further comprising the step of selectively allowing abraded surface material from objects within the chamber to exit through a gap between a wall portion of the chamber and the abrasive surface.

12. A method as claimed in claim 11 , further comprising the step of drawing a vacuum outside the chamber to draw the abraded surface material from the gap.

13. A method as claimed in claim 10 , wherein the abrasive surface is substantially vertical, the method further comprising allowing abraded surface material from objects within the chamber to fall through the chamber under the force of gravity.

14. A method as claimed in claim 10 , further comprising passing the objects through the chamber more than once.

15. An apparatus for abrading the surface of objects comprising a chamber, an abrasive surface defining a wall of said chamber and drive means for moving the abrasive surface relative to the chamber, whereby, in use, said relative movement promotes circulation of the objects within the chamber, the chamber comprising an asymmetric cross-sectional shape to approximate the asymmetric peripheral flow path of the objects within the chamber.

16. An apparatus as claimed in claim 15 , wherein the cross-section of the chamber is asymmetric about a central horizontal plane that is substantially perpendicular to the abrasive surface.