Abstract:
A milling cutter  1  with a directed coolant delivery system is disclosed. The milling cutter  1  may have a plurality of coolant ducts  40  which span from a centrally located reservoir  42  or distribution point within the body  20  of the milling cutter  1  to a series of recesses  10  on the exterior of the body  20.  Coolant nozzles  50  are inserted into a countersunk portion  51  between the coolant duct  40  and the recesses  10.  The countersunk portions  51  provide protection for the coolant nozzles  50.  Each coolant nozzle  50  has a bore  58  which may be narrower than the coolant duct  40  or alternatively may have a bore  58  and a restriction  60.  Nozzles of the present invention provide consistent streams of coolant to the to the tool-workpiece interface to enable precise adjustment of the streams of a coolant from a position close to the tool-workpiece interface.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to coolant nozzles for milling cutters for machining and metalworking, and in particular to coolant nozzles of a fluid cooling system for multi-pocket milling cutters. 
       BACKGROUND INFORMATION 
       [0002]    Cooling fluid, e.g., light cutting oil, is often used in metalworking operations. The cooling fluid is often delivered through a passage to a discharge point near an interface between a cutting tool and a work piece. The cooling fluid serves to prolong the life of the cutting tool or insert, and also enables faster cutting or machining of the work piece, by reducing friction and assisting in heat transfer from the work piece to the cutting tool at the interface between the two. 
         [0003]    Many coolant delivery systems clamp an exterior tube onto the cutting tool holder to deliver cooling fluid to the cutting tool. These systems are inexpensive and easy to assemble but are often flimsy, easily damaged and incapable of discharging cooling fluid near the cutting tool-workpiece interface. Other cooling fluid delivery systems provide a duct through the tool holder which discharges in an area near the insert. However, correct sizing of the ducts presents manufacturing challenges. Drilling a long duct with a small drill bit is difficult. The small bit often breaks and causes significant downtime and cost. Small ducts also take a long time to make due to longer cycle times. As a result, larger bits are used to bore larger ducts, but coolant system pressure losses due to the larger ducts cause poor coolant delivery and ineffective cooling. The present invention has been developed in view of the foregoing. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention provides a milling cutter with a directed coolant delivery system. The milling cutter may have a plurality of coolant ducts which span from a centrally located reservoir or distribution point within the body of the milling cutter to a series of recesses within pockets on the exterior of the body. Coolant nozzles are inserted into a countersunk portion between the coolant duct and the recesses. The countersunk portions provide protection for the coolant nozzles. Each coolant nozzle has a bore narrower than the coolant duct or alternatively may have a bore and a restriction. Nozzles of the present invention provide a precise stream of coolant to the tool-workpiece interface from a position close to the tool-workpiece interface and in a manner that equally distributes coolant to all pockets. 
         [0005]    An aspect of the present invention provides a milling cutter comprising a cutter body including a plurality of recessed cutting portions, a coolant reservoir within the cutter body, a plurality of coolant ducts extending from the reservoir to the recessed cutting portions each having a reservoir end and a discharge end and at least one coolant nozzle inserted into the discharge end of the coolant duct having a restriction having an internal diameter less than an internal diameter of the discharge end of the coolant duct. 
         [0006]    Another aspect of the present invention provides a milling cutter comprising a cutter body including a plurality of recessed cutting portions a coolant reservoir within the cutter body, a plurality of coolant ducts extending from the reservoir to the recessed cutting portions each having a reservoir end, discharge end and a countersunk portion and a coolant nozzle having a head and a threaded portion. 
         [0007]    Yet another aspect of the current invention provides a coolant nozzle for use in a milling cutter comprising an inlet end, a discharge end, a bore between inlet end and the discharge end and having an inside diameter and providing fluid communication between the inlet end and discharge end, a driver indentation in fluid communication with the inlet end and discharge end located between the discharge end and the bore having an inside diameter or width greater than the inside diameter of the bore structured and arranged to receive a driving device, wherein the bore and driver indentation are centered about a longitudinal axis of the nozzle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Further features of the present invention, as well as the advantages derived therefrom, will become clear from the following detailed description made with reference to the drawings in which: 
           [0009]      FIG. 1  is an oblique view of a milling cutter with replaceable inserts and coolant nozzles according to one embodiment of the present invention. 
           [0010]      FIG. 2  is a section view of the milling cutter shown in  FIG. 1  along section line  22  of  FIG. 1  according to one embodiment of the present invention. 
           [0011]      FIG. 3  is an enlarged oblique view of a recess in the body of a milling cutter for the cutting insert and coolant nozzle according to one embodiment of the present invention. 
           [0012]      FIG. 4  is a side view of a coolant nozzle according to one embodiment of the present invention. 
           [0013]      FIG. 5  is a front view of the head of a coolant nozzle according to one embodiment of the present invention. 
           [0014]      FIG. 6  is a side cross-section of a coolant nozzle showing the bore and restriction according to one embodiment of the present invention. 
           [0015]      FIG. 7  is a section view of a milling cutter along a coolant duct with a plug type of coolant nozzle according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    A milling cutter  1  with replaceable cutting inserts  2  is shown in  FIG. 1  according to one embodiment of the present invention. The milling cutter  1  has a plurality of recesses  10  within the body  20  of the milling cutter  1 . The recesses  10  provide clearance for installation of cutting inserts  2  which are the cutting portion of the milling cutter  1 . The cutting inserts  2  are often indexable, replaceable inserts made in whole or in part from, for example, carbides, including tungsten carbide, titanium carbide and tantalum carbide, aluminum oxide, titanium nitride, cobalt, cubic boron nitride, including ceramics, and alloys and cermets of these materials. Recesses  10  include seating surfaces  11  for seating of the cutting inserts  2 . The cutting inserts  2  are held against the seating surfaces  11  by way of retention screw  3  which is threadedly engaged with an aperture  5  within the seating surface  11  of the body  20 . Projecting from the body  20  is the mounting member  30 . The shank  30  is the portion of the milling cutter  1  which attaches to a rotating drive apparatus (not shown). The milling cutter and drive apparatus share a common axis of rotation illustrated by the dashed line in  FIG. 1 . The shank  30  also provides a path for delivering coolant to the milling cutter  1 . 
         [0017]    Referring now to  FIG. 2 , a sectional view of the milling cutter  1  of  FIG. 1  is shown along section line  2 - 2 . Section  2 - 2  is taken along a center line of a coolant duct  40  which provides passage of coolant from a centrally located reservoir  42  within the milling cutter  1  to the recess  10 . At the recess  10  end of the duct  40  is a coolant nozzle  50  which provides a restriction at the recess  10  end of the coolant duct  40 . The coolant nozzle  50  has an inlet end  57  for receiving coolant that is proximally positioned in coolant duct  40  and a discharge end  59  that is distally located near the recess  10 . As seen in  FIG. 2  the coolant duct  40  has a reservoir end  43  and a discharge end  44 . The discharge end  44  may be fitted with internal threads for receiving an externally threaded coolant nozzle  50 . The coolant nozzle  50  has a reduced diameter bore which restricts the relatively large diameter coolant duct  40  to ensure fluid pressure is not lost and coolant is propelled to the cutting edge  4  of the cutting insert  2 . As seen in  FIG. 3 , a countersunk portion  51  transitions between the recess  10  and duct  40  to allow clearance for the head  50  of the nozzle  40 . Countersunk portion  51  has an inside diameter greater than an inside diameter of the coolant duct  40  and at least as large as nozzle head  50 . In this manner, the head  50  can be securely fastened against the countersunk portion  51 . Additionally, countersunk portion  51  provides protection for the coolant nozzle  40  preventing it from plugging or being damaged, for example, by metal chips or other debris. As used herein, the term “countersunk portion” refers to a hole with the top part enlarged so that a screw or bolt will fit into it and lie below the surface. A countersunk portion would include by way of example cylindrical and non-cylindrical counter bores and countersinks. 
         [0018]    Referring to  FIGS. 2 and 3 , it is to be noted that the bore  58  of the coolant nozzle  50  is aligned with and in close proximity to the cutting edge  4  of the insert  2 . In the preferred embodiment, the bore  58  and restriction  60  are aligned with the corner of the insert cutting edge  4  as illustrated in  FIGS. 1-3 . Additionally, the coolant nozzle  50  is integrated into the coolant duct  40  and countersunk portion  51  of the body  10  of milling cutter  1 . In this manner, a narrow stream of coolant can precisely be delivered to the interface of the tool and workpiece being cut. 
         [0019]      FIG. 4  shows an isolated side view of a nozzle  50  according to one embodiment of the present invention. As shown, nozzle  50  has a threaded portion  54  that is inserted in duct  40  to hold the nozzle  50  in place. Threaded portion  54  has an outside diameter which corresponds to the inside diameter of the coolant duct  40  to enable threaded engagement of the two components. Coolant nozzle  50  may also have an expanded head portion  52  for the nozzle which seats in the countersunk portion  51  between the duct  40  and the recess  10 . Nozzle  50  is configured about a central longitudinal axis shown as the centerline in  FIG. 4 . 
         [0020]    Referring now to  FIG. 5 , a front view of the nozzle&#39;s head  52  with a driver indentation  56  is shown according to one embodiment of the present invention. The driver indentation  56  is shown here as having an internally dimensioned, generally hexagonal shape but may be many different configurations, for instance, a star-shaped pattern, an X-shaped pattern, or square. In another embodiment of the present invention, the head may have a bolt head type of configuration whereby a socket is used to tighten and loosen the coolant nozzle within the coolant duct. The discharge end of restriction  60  can also be seen in this view. Driver portion  56  has a width shown as W in  FIG. 5  which is greater than or equal to the restriction  60 . W may be about 1 mm to about 3 mm, for example 2 mm. The driver indentation  56  is configured to provide removal and installation of nozzles  50  with standard tools and also provides protection for the discharge end of restriction  60  while not interfering with the streaming discharge of liquid coolant from the nozzle  50 . 
         [0021]    Referring now to  FIG. 6 , a cross section of the nozzle  50  shown in  FIGS. 4 and 5  is illustrated. The cross section is taken along section lines  6 - 6  of  FIG. 5 . As can be seen in  FIG. 6 , the nozzle  50  has a bore  58  near inlet end  57  of the coolant nozzle  50 . The bore  58  may have a diameter, D b , less than the inside diameter of a coolant duct  40  for which it is sized. Positioned between the bore  58  and the driver indentation  56  is a restriction  60 . The restriction  60  may have a diameter of about 0.5 mm to about 2.5 mm, for example 1.5 mm. In a preferred embodiment, the restriction  60  also has a length L n , of no less than 1 mm. Restriction  60  and/or bore  58  is sized to enable a more consistent flow through ducts to the cutting edge of the cutting inserts and focus the coolant into a narrower stream. The width or diameter of the driver indentation should be dimensioned at least as wide as restriction so clearance is providing for the exiting coolant stream. 
         [0022]    Another embodiment of the present invention having a plug type of coolant nozzle is shown in  FIG. 7 . A cross-section view along the center line of the coolant duct  140  of the milling cutter  101 . The milling cutter  101  has a body  120  with a plurality of recessed cutting portions  110 . Each recess  110  has a seating surface  111  for mounting a cutting insert  102 . At an end of the coolant duct  140  is a discharge end  144 . Between the discharge end  144  and the recess  1   10  is an internally threaded countersunk portion  151 . A step  132  radially extends from the coolant duct  140  to the countersunk portion  151 . In this embodiment, the coolant nozzle  150  has a threaded portion  154  and a head  152 . The threaded portion  154  and the head  152  are both externally threaded and both have the same external diameter. This structure enables the entire coolant nozzle  150  to be threaded into the countersunk portion  151  until the threaded portion abuts the step  132  between the coolant duct  140  and the countersunk portion  151 . The bore  158  may be a first tapered portion  153  which provides a smooth transition between the coolant duct  140  and the bore  158  of the coolant nozzle  150 . A second tapered portion  155  provides a smooth transition between the bore  158  and the restriction  160 . The head  152  of the coolant nozzle  150  has a driver indentation  156  at the discharge end  159 . The bore  158  and restriction  160  are dimensioned as described in earlier embodiments. 
         [0023]    Coolant nozzles  50 ,  150  are typically threaded into the coolant ducts  40 ,  140 . Liquid thread locking compound may be applied to the coolant nozzles  50 ,  150  to ensure the coolant nozzles  50 ,  150  are securely held in the coolant ducts  40 ,  140 . This facilitates easy installation and removal of the coolant nozzles  50 ,  150 . In this manner, coolant nozzle restriction diameters can be changed on a given milling cutter  1 ,  101  or the replacement nozzles may be installed. While a threaded connection is preferred, it has been contemplated that a press fit, adhesive or welded connection could be used to retain the coolant nozzles within the coolant ducts. 
         [0024]      FIGS. 8 and 9  depict embodiments of the present invention having alternate location of the restriction within the coolant nozzle.  FIG. 8  shows a coolant nozzle  250  with the restriction  260  at the discharge end of the coolant nozzle  250  and the bore  258  at the inlet end or the coolant nozzle  250 .  FIG. 9  shows a coolant nozzle  350  with the restriction  360  at the inlet end of the coolant nozzle  350  and the bore  358  at the discharge end or the coolant nozzle  350 . 
         [0025]    Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.