Coolant nozzle

1. An apparatus comprising:

a machine tool;

an elongate abrasive bit carried by the machine tool; and

a nozzle, the nozzle comprising a sintered body having:

at least one coolant inlet;

a plurality of coolant outlets, no gap in either circumferential direction between sequentially adjacent ones of the outlets being more than 72°;

internal surface portions defining one or more passageways between the at least one coolant inlet the and at least one coolant outlet; and

an aperture accommodating the bit.

2. The apparatus of claim 1 wherein the sintered body is a single unitary piece.

3. The apparatus of claim 1 wherein the one or more passageways includes a plenum surrounding the aperture.

4. The apparatus of claim 1 wherein the plurality of coolant outlets are symmetric around an axis.

5. The apparatus of claim 1 wherein the plurality of coolant outlets are positioned to direct associated coolant outlet streams toward an axis of the bit when said bit is in an installed position.

6. The apparatus of claim 5 wherein the plurality of coolant outlets are elongate.

7. The apparatus of claim 5 wherein the plurality of coolant outlets comprises at least five outlets and the at least one coolant inlet is a single coolant inlet.

8. The apparatus of claim 1 wherein the aperture has a diameter of less than 3 cm.

9. The apparatus of claim 1 wherein the plurality of coolant outlets are angled to provide essentially total coverage along a length of an abrasive portion of the bit.

10. The apparatus of claim 1 wherein the plurality of coolant outlets provide a redundant coverage around the entire circumference of the bit so that, during a machining operation, the effects of a workpiece blocking one or more sprays of the coolant are limited.

11. The apparatus of claim 1 wherein the coolant is water based or comprises oil.

12. The apparatus of claim 1 wherein the one or more passageways include:

a feed trunk; and

a plenum between the feed trunk and the outlets.

13. An apparatus comprising:

a machine tool;

a rotating abrasive quill carried by the machine tool; and

a nozzle, the nozzle comprising a sintered body and having:

at least one coolant inlet;

at least one coolant outlet discharging a plurality of liquid coolant outlet streams impacting obliquely toward a tip of the quill along a side of the quill;

internal surface portions defining one or more passageways along essentially an entire circumference of the quill between the at least one coolant inlet and the at least one coolant outlet; and

an aperture accommodating the quill.

14. The apparatus of claim 13 formed of a sintered ceramic.

15. The apparatus of claim 13 wherein the at least one coolant outlet comprises at least five outlets and the at least one coolant inlet is a single coolant inlet.

16. The apparatus of claim 13 wherein the liquid coolant outlet streams have centerlines meeting the bit at an acute angle to a rotational axis of the bit.

17. An apparatus comprising:

a machine tool;

a rotating abrasive bit carried by the machine tool; and

a nozzle, the nozzle comprising a sintered body and having:

a through-aperture accommodating the bit;

a coolant inlet;

a plurality of coolant outlets at more than one angular position about the through-aperture and oriented to discharge associated coolant outlet streams and having circumferential spacing between each of the outlets and an associated first and second adjacent ones of the outlets on respective first and second sides of said outlet of no more than 72°; and

internal surface portions defining one or more passageways between the coolant inlet and the plurality of coolant outlets.

18. The apparatus of claim 17 wherein the bit is an elongate superabrasive quill.

19. The apparatus of claim 17 wherein the bit has a doubly convex head portion and a distal shaft portion which have an abrasive coating or embedded abrasive particles.

20. The apparatus of claim 17 having a sintered nozzle body.