Separator for a grinding machine

1. A grinding machine comprising:

a grinding head defining an opening;

a rotatable advancement member contained within the grinding head;

an orifice plate located within the opening of the grinding head, wherein the orifice plate defines an upstream surface and a downstream surface, and includes a plurality of outer grinding openings extending between the upstream surface and the downstream surface for discharging soft material through the orifice plate upon rotation of the rotatable advancement member, and one or more collection passages extending between the upstream surface and the downstream surface for discharging a mixture of soft material and hard material through the orifice plate upon rotation of the rotatable advancement member;

a separator assembly located downstream of the orifice plate, wherein the separator assembly includes an upstream inlet that receives the mixture of soft material and hard material from the one or more collection passages; a separator chamber having a wall that defines an axially extending tapered separator passage, wherein the separator passage receives the mixture of soft material and hard material from the upstream inlet, and wherein the wall of the separator chamber includes a plurality of perforations that communicate between the separator passage and an outer surface defined by the wall; and a separator screw disposed within the separator passage of the separator chamber, wherein the separator screw is interconnected with the rotatable advancement member and is rotatable within the separator passage in response to rotation of the rotatable advancement member, wherein rotation of the separator screw causes separation of soft material from the mixture of soft material and hard material and forces the soft material through the perforations in the wall of the separator chamber, wherein the separator chamber defines a downstream end that includes an outlet for discharging hard material; and

an open support extending outwardly from the grinding head, wherein the separator chamber is engaged with and supported by the support at a location downstream of the orifice plate.

2. The grinding machine of claim 1 , wherein the wall of the separator chamber has a generally conical configuration.

3. The grinding machine of claim 1 , wherein the separator chamber has a first tapered portion and a second tapered portion, and wherein the first tapered portion defines a collection cavity into which mixture of soft material and hard material is passed through the one or more collection passages of the orifice plate, and wherein the second tapered portion extends from the first tapered portion.

4. The grinding machine of claim 3 , wherein the perforations are formed in the second tapered portion of the separator chamber.

5. The grinding machine of claim 4 , wherein the downstream end of the separator chamber defines a constant diameter portion adjacent the outlet, wherein the perforations are located upstream of the constant diameter portion.

6. The grinding machine of claim 1 , further comprising a centering pin extending from the rotatable advancement member, wherein the centering pin rotates with the rotatable advancement member and is engaged within a center opening defined by the orifice plate, and wherein the separator screw is engaged with the centering pin so as to be rotatable with the rotatable advancement member via engagement with the centering pin.

7. The grinding machine of claim 6 , including engagement structure between the centering pin and the separator screw for non-rotatably securing the separator screw to the centering pin.

8. The grinding machine of claim 7 , further comprising an adjustment arrangement for adjusting the axial position of the separator screw within the separator passage, wherein the engagement structure between the separator screw and the centering pin accommodates axial movement of the separator screw relative to the centering pin by operation of the adjustment arrangement.

9. The grinding machine of claim 8 , wherein the engagement structure comprises a bore in the separator screw within which the centering pin is received; a transverse passage in the centering pin; a slot in the separator screw that overlaps the transverse passage; and a transverse engagement pin that extends through the slot and the transverse passage, wherein the slot accommodates axial movement of the separator screw relative to the centering pin.

10. A grinding machine comprising:

a grinding head defining an opening;

a rotatable advancement member contained within the grinding head;

an orifice plate located within the opening of the grinding head, wherein the orifice plate defines an upstream surface and a downstream surface, and includes a plurality of outer grinding openings extending between the upstream surface and the downstream surface for discharging soft material through the orifice plate upon rotation of the rotatable advancement member, and one or more collection passages extending between the upstream surface and the downstream surface for discharging a mixture of soft material and hard material through the orifice plate upon rotation of the rotatable advancement member;

a separator assembly located downstream of the orifice plate, wherein the separator assembly includes an upstream inlet that receives the mixture of soft material and hard material from the one or more collection passages; a separator chamber having a wall that defines an axially extending tapered separator passage, wherein the separator passage receives the mixture of soft material and hard material from the upstream inlet, and wherein the wall of the separator chamber includes a plurality of perforations that communicate between the separator passage and an outer surface defined by the wall; and a separator screw disposed within the separator passage of the separator chamber, wherein the separator screw is interconnected with the rotatable advancement member and is rotatable within the separator passage in response to rotation of the rotatable advancement member, wherein rotation of the separator screw causes separation of soft material from the mixture of soft material and hard material and forces the soft material through the perforations in the wall of the separator chamber, wherein the separator chamber defines a downstream end that includes an outlet for discharging hard material;

an adjustment arrangement for adjusting the axial position of the separator screw within the separator passage; and

an open support extending outwardly from the grinding head, wherein the separator chamber is engaged with and supported by the support at a location downstream of the orifice plate, wherein the support and the orifice plate are configured and arranged to prevent axial movement of the separator chamber, and wherein the adjustment arrangement is carried by the support and interconnected with the separator screw for providing axial movement of the separator screw within the separator passage.

11. The grinding machine of claim 10 , wherein the adjustment arrangement comprises an axially extending threaded adjustment member that extends through the support and into engagement with a threaded passage extending inwardly from a downstream end defined by the separator screw.

12. The grinding machine of claim 10 , wherein the wall of the separator chamber has a generally conical configuration.

13. The grinding machine of claim 10 , wherein the separator chamber has a first tapered portion and a second tapered portion, and wherein the first tapered portion defines a collection cavity into which mixture of soft material and hard material is passed through the one or more collection passages of the orifice plate, and wherein the second tapered portion extends from the first tapered portion.

14. The grinding machine of claim 13 , wherein the perforations are formed in the second tapered portion of the separator chamber.

15. The grinding machine of claim 14 , wherein the downstream end of the separator chamber defines a constant diameter portion adjacent the outlet, wherein the perforations are located upstream of the constant diameter portion.

16. The grinding machine of claim 10 , further comprising a centering pin extending from the rotatable advancement member, wherein the centering pin rotates with the rotatable advancement member and is engaged within a center opening defined by the orifice plate, and wherein the separator screw is engaged with the centering pin so as to be rotatable with the rotatable advancement member via engagement with the centering pin.

17. The grinding machine of claim 16 , including engagement structure between the centering pin and the separator screw for non-rotatably securing the separator screw to the centering pin.