Abstract:
A coolant nozzle is used in a machine tool having a rotating bit. The nozzle includes a through-aperture for accommodating the bit. The nozzle has a coolant inlet and a number of coolant outlets at more than one angular position about the through-aperture. Internal surface portions define one or more passageways between the inlet and the outlets.

Description:
U.S. GOVERNMENT RIGHTS 
   The invention was made with U.S. Government support under contract no. N0001902C3003 awarded by the U.S. Navy. The U.S. Government has certain rights in the invention. 

   BACKGROUND OF THE INVENTION 
   (1) Field of the Invention 
   The invention relates to machining. More particularly, the invention relates to superabrasive machining of metal alloy articles. 
   (2) Description of the Related Art 
   Apparatus for point and flank superabrasive machining (SAM) of turbomachine components are respectively shown in U.S. patent applications Ser. Nos. 10/289,493 and 10/400,937, respectively filed Nov. 6, 2002 and Mar. 27, 2003. The disclosures of the &#39;493 and &#39;937 applications are incorporated by reference herein as if set forth at length. It is important to provide fluid coolant/lubricant (e.g., oil or water-based materials) to maintain machining effectiveness. 
   SUMMARY OF THE INVENTION 
   One aspect of the invention involves a coolant nozzle for use on a machine tool having a rotating bit. The nozzle comprises at least one coolant inlet and at least one coolant outlet. Internal surface portions define one or more passageways between the inlet and the outlet. An aperture accommodates the bit. 
   In various implementations, the internal surface portions may be formed in a laser sintered ceramic body. The passageways may include a plenum surrounding the aperture. There may be a number of outlets symmetric around an axis. There may be a number of outlets positioned to direct associated coolant outlet streams toward an axis of the bit when the bit is in an installed position. The outlets may be elongate. There may be at least five outlets and a single inlet. The aperture may have a diameter of less than three centimeters. The nozzle may be in combination with the machine tool and bit and a number of coolant outlet streams may exit the outlets and impact obliquely along a side of the bit. 
   Another aspect of the invention involves a coolant nozzle for use in a machine tool having a rotating bit. The nozzle includes a through-aperture for accommodating the bit. The nozzle has a coolant inlet and a number of coolant outlets at more than one angular position about the through-aperture. Internal surface portions define one or more passageways between the coolant inlet and the coolant outlets. 
   In various implementations, the coolant outlets may each be at a common radial position relative to an axis and at a unique angular position about the axis. There may be no other coolant outlets in addition to the coolant outlets. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view of a nozzle according to principles of the invention. 
       FIG. 2  is a vertical sectional view of the nozzle of  FIG. 1  taken along line  1 - 1 . 
       FIG. 3  is a front x-ray view of the nozzle of  FIG. 1 . 
       FIG. 4  is a view of a front nozzle boss of the nozzle of  FIG. 1 . 
       FIG. 5  an enlarged view of the nozzle taken along line  5 - 5  of  FIG. 2 . 
       FIG. 6  is a rear perspective view of the nozzle of  FIG. 1 . 
   

   Like reference numbers and designations in the various drawings indicate like elements. 
   DETAILED DESCRIPTION 
     FIG. 1  shows a nozzle  20  for lubricating/cooling a bit  22  held by a spindle  24  of a machine tool  25  ( FIG. 2 ). An exemplary bit is a superabrasive quill. The bit has a shaft with a distal doubly convex (e.g., hemispherical) head  26  and distal shaft portion  28  which have an abrasive coating or embedded abrasive particles (e.g., plated cubic boron nitride or diamond grit). The bit has an intermediate enlarged portion  30  having flats (not shown) for gripping by a tool and a proximal portion (not shown) for mounting the bit to the spindle. The nozzle has a front surface  40  ( FIG. 2 ) and a back surface  42 . The back surface may include features (e.g., a channel  44 ) for mating to complementary features of the machine tool front to register the nozzle in an operative position in precise alignment with the machine tool. Securing means may be provided such as mounting apertures  46  ( FIG. 1 ) for receiving studs protruding from the machine tool or fasteners extending into the machine tool to removably secure the nozzle registered in the operative position. Alternatively, a clamping mechanism may be used in conjunction with an automated tool changer. In the operative position the nozzle has an aperture  50  encircling a central longitudinal axis  500  of the spindle and bit. The aperture is, in principal part, defined by an internal surface  52  in close spaced part relation to the bit intermediate portion  30  (e.g., with a radial clearance of up to about 1 cm, more narrowly 5 mm). In the exemplary embodiment, a forward portion  56  of the spindle is received within a recess  58  in the nozzle aft surface. In the exemplary embodiment, the recess  58  surrounds the spindle forward portion with an appropriate radial clearance and is connected via passageways  60  ( FIG. 1 ) to the nozzle lateral periphery. The passageways  60  permit passage of cooling air to reach the spindle. 
   A principal function of the nozzle is to introduce a cooling and/or lubricating fluid to the bit. At its lower end, the nozzle has with a fluid inlet  62  which feeds fluid to a trunk  64  of a fluid passageway network the respective portions of which are defined by associated internal surface portions of the nozzle. The trunk  64  feeds an exemplary three branches  66 ,  68 , and  70  ( FIG. 3 ). The branches feed a plenum  72  encircling the axis  500 . The branch outlets to the plenum are spaced at approximately even 120° intervals so as to provide even introduction of fluid to the plenum. A circular array of outlet passageways  74  ( FIG. 2 ) extend from the plenum to a nozzle boss  76  on the front surface  40  encircling the aperture  50  ( FIG. 4 ). In the illustrated embodiment, each outlet passageway extends to an outlet  80  on an outlet boss  82  protruding from a slightly inwardly-facing frustoconical rim surface  84  of the nozzle boss  76 . The outlet and a surrounding rim  86  are oriented facing forward and inward toward the axis  500 . A terminal portion  90  of each outlet passageway is downstream divergent and elongate along a plane along the axis  500  so as to have a length L in such plane and a width W transverse thereto. Such a configuration produces a spray  100  that fans out at an approximate angle θ 1  in such plane to impact the bit along the intermediate portion  30  with a centerline  101  at an acute angle θ 2  to the axis  500 . The angles θ 1  and θ 2  are chosen so that the sprays provide essentially total coverage along the length of the abrasive portion of the quill. The large number of outlets provides a highly redundant coverage around the circumference of the quill so that, during the machining operation, the effects of the workpiece blocking one or more of the sprays are minimized. 
     FIG. 6  shows further details of the exemplary nozzle. Along the bottom of the aperture  50 , a depression  102  is formed in the surface  52  to serve as a drain. This depression extends downward along the stepped forward surface portions  104  and  106  of the recess  58  to permit drainage around the spindle. Similarly, the surface  106  is provided with open channel recesses  108  formed as continuations of the cooling passageways  60 . These recesses help permit the outward ventilation of coolant mist. 
   In an exemplary method of manufacture, the nozzle is formed as a single unitary piece by selective laser sintering (SLS) of a ceramic. This can provide for quick and cost-effective manufacture, especially of small quantities. For ease of manufacture, strength, and distribution of the outlets, advantageously the nozzle circumscribes a full 360° around the aperture. This structure, for example, allows the plenum to similarly extend. However, there may be particular circumstances where this structure might not be utilized. 
   In the exemplary embodiment, the outlets are all of a given size and shape, and at a given radius from the axis  500  and are equally spaced about such axis. The illustrated nozzle includes twenty outlets. An exemplary broad range is two to forty outlets. Narrower ranges are five to thirty and ten to twenty-five. 
   One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, various details of the nozzle may be configured for use with particular machine tools, bits, and applications. In flank SAM applications, the outlets may be distributed so that their streams advantageously clear the workpiece being machined. This may involve uneven outlet distribution and/or greater overlap/redundancy in streams. Accordingly, other embodiments are within the scope of the following claims.