Abstract:
The cutting fluid distribution system disclosed is one in which the cutting fluid passages which carry the cutting fluid from a pressurized source to the cutting bits of a rotary milling cutter are incorporated into the cutter in a way to be formed in large part by the mere assembly of the constituent elements of the cutter.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to milling cutters, and particularly to a system for delivering cutting fluid from a pressurized source in a machine spindle to the multiple cutting edges of a rotary milling cutter such as, but not necessarily limited to, a face mill.  
           [0002]    In the past, it has been common to carry cutting fluid to the multiple cutting sites of the rotary tool through conduits drilled in the body of the cutter. Apart from difficulty of manufacture, such systems are subject to clogging of the drilled passages as well as to differential distribution of the cutting fluid if the conduits are not carefully designed and made, and maintained.  
           [0003]    These problems are addressed in the cutter of the invention by incorporating the cutting fluid distribution system into the design of the cutter in a way such that it is formed merely by the assembly of the constituent elements of the cutter body and is completely opened for inspection and maintenance as an incident to the disassembly of the cutter body.  
         SUMMARY OF THE INVENTION  
         [0004]    In the cutter of the invention, the distribution paths which carry the cutting fluid to the multiple cutting sites of the tool are formed by the central bore of the cutter head, the central pilot boss of the adapter received in the inner end of the cutter head bore, and a cap received in the outer end of that bore and spaced from the flat cutting face to permit the radial escape of the cutting fluid across the face of the cutter head to grooves in the peripheral rim of the cutter head leading to the rake face of each cutting bit of the cutter.  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0005]    The invention is described in connection with the accompanying drawings, in which:  
         [0006]    [0006]FIG. 1 is an oblique isometric drawing of a face mill cutter head embodying the invention, seen there from the front as a partial exploded assembly view;  
         [0007]    [0007]FIG. 2 is a similar exploded oblique isometric view of the same seen from the rear;  
         [0008]    [0008]FIG. 3 is an elevational view of the underside of the well cap seen with the cutter head in FIGS. 1 and 2;  
         [0009]    [0009]FIG. 4 is a side view of the well cap of FIG. 3;  
         [0010]    [0010]FIG. 5 is an isometric view of the well cap shown in FIGS. 3 and 4;  
         [0011]    [0011]FIG. 6 is a cross-sectional view of the cutter head, well cap, adapter plate, and spindle face in assembled relation, taken as though along the angled broken line  6 - 6  of FIG. 3;  
         [0012]    [0012]FIG. 7 is a fragmentary enlargement of the right half of FIG. 6, made to show by exaggeration the flow path of the cutting fluid in the clearance space between the well cap and the face of the cutter head;  
         [0013]    [0013]FIG. 8 is an exploded isometric assembly drawing of another embodiment of the invention applied to cutters of smaller diameter;  
         [0014]    [0014]FIG. 9 is an enlarged side elevation view of the cap screw alone, of FIG. 8; and  
         [0015]    [0015]FIG. 10 is a centerline cross section of the assembly of FIG. 8, illustrating the path of cutting fluid from the central bore of the pilot boss of the adapter plate to the face of the cutter head and thence to the rake face of each cutting insert.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    The invention is here illustrated in one preferred embodiment, namely the cutter head  20  of a face mill  10 , the exterior of which is seen from front, side, and back in FIGS. 1 and 2, and the internal construction of which will be evident from the cross-sectional view of FIG. 6, which shows the cutter head  20  in assembly with an intermediate adapter plate  22  secured by conventional means to the face  24  of the spindle of the milling head (not shown), which drives and wields the cutter.  
         [0017]    Aligned axial passages  26  and  28  in the spindle face  24  and adapter plate  22 , respectively, supply cutting fluid under pressure to a central bore  30  in the cutter head  20 .  
         [0018]    Secured by screws  32  to the top of the cutter head  20  in FIGS. 6 and 7 is a closure  34  for the well  30 . The closure  34  comprises a circular cap  36  having on its underside an integral center plug  38  which is received into the central bore  30  of the cutter head  20  in the assembly.  
         [0019]    About its periphery, the center plug  30  is indented radially by four equispaced cut-outs  40  which reduce the central plug  38  essentially to a four-armed spider which remains clear of the pilot boss  42  of the adapter plate  22  to form therewith a manifold chamber communicating with the four cut-outs  40 .  
         [0020]    The circular cap  36  of the well closure  34  has on its underside, aligned with the residual arms of the center plug  38 , four integral pads  44  of small dimension axially of the cutter body. Countersunk screw holes in the cap  36  in the center of each pad  44  receive the screws  32  which secure the closure  34  to the cutter head  20 , with the underside of the cap  36  spaced from the flat face of the cutter head  20  by the thickness of the pads  44 , leaving a clearance space beneath the cap  36  which serves as a channel of increasing dimension radially of the cutter head.  
         [0021]    The cutter head  20  is held in assembled relation with the adapter plate  22  by four cap screws  46  seated in counterbored through holes  48  in the cutter head and received in aligned threaded holes in the adapter plate (FIG. 6). To provide access to the screw holes  48  from the face of the cutter head  20 , the cap  36  of the well closure  34  is notched in its periphery at  49  in alignment with the screw holes  48 , avoiding the necessity of removing the well closure  34  in order to disassemble the cutter head  20  from the adapter plate  22  for routine service, i.e., the indexing and/or replacement of the cutting inserts which are served by the cutting fluid, and to which attention will now be turned.  
         [0022]    The cutter head  20 , as shown in FIGS. 1 and 2, is essentially a disc having a substantial peripheral rim  50  on the side of the cutter head which addresses the workpiece, which may be referred to as the cutter face  52 , and which has a flat central area within the rim  50 .  
         [0023]    The periphery of the cutter head is milled to provide multiple tool bit emplacements, each comprising a recess or pocket  54  of generally rectangular configuration having its long axis aligned approximately parallel to the rotational axis of the cutter head, but leaning slightly away from the cutting direction of rotation to provide clearance for the axially facing cutting edges of the cutting inserts  56  therein. The inserts are normally supported axially of the cutter head within the pockets  54  by insert seats (not shown in FIGS.  1  to  7 ) in turn supported by the bottom wall of the pocket  54 , as the insert  56  and its supporting seat are backed by the rear wall of the pocket, which is open to its front side, i.e., in the cutting direction of rotation, to a more deeply milled chip gullet  58  to receive the chips taken from the workpiece by the end and side cutting edges of the insert.  
         [0024]    The insert seat, in its form and its relation to the cutter head  20  and the insert  56 , although illustrated in FIGS. 8 and 10 hereof, is shown only incidentally, as it is the subject of my co-pending patent application Ser. No. ______ filed contemporaneously herewith, and forms no part of the invention of this application.  
         [0025]    Returning to the cutting fluid distribution system, the upstanding rim  50  about the face  52  of the cutter head, is milled to provide upwardly-inclined radial slots  60  extending from the face  52  to each of the chip gullets  58  at their upper ends (FIGS. 1 and 6). Thus, as the cutter head  20  is rotated by the machine spindle, and cutting fluid is supplied to central bore  30  of the cutter body under pressure through the conduits  26  and  28 , it is manifolded by the central bore to the cut-outs  40  of the central plug of the well closure  34 , and then escapes radially outwardly through the clearance space between the cap  36  and the face  52  of the cutter body, proceeding as a sheet or film of fluid until it reaches the rim  50 .  
         [0026]    Portions of the cutting fluid, under centrifugal force, are forced up the sloping channels  60  to bathe and cool the cutting inserts  56 , lubricate the cut of the inserts engaged against the workpiece, and flush the chips accumulating in the chip gullets  58  to facilitate their departure from the chip gullets by centrifugal force as the inserts clear the cut.  
         [0027]    A portion of the cutting fluid also escapes over the top of the rim  50 , as two distinct spray cones have been seen to occur at operating speeds, which, in the case of milling aluminum, may run to 4,000 surface feet per minute.  
         [0028]    As earlier noted, the enlargement of a portion of FIG. 6 as FIG. 7 purposely exaggerates the clearance space between the cap  36  and the face  52  of the cutter head for the sake of illustrating the fluid flow path clearly. In an actual case of an eight-inch diameter face mill, that clearance space was held to a maximum of 0.018″, determined by the thickness of the pads  44  on the underside of the cap  36 . That clearance space, related to the pressure of the entering fluid, is intended to produce a throttling effect sufficient to assure reasonably uniform distribution from the central well manifold to each chamber formed between the cut-outs  40  and the wall of the central bore  30  of the cutter head, to assure reasonably uniform flow across the cutting face of the cutter head to the multiple cutting inserts.  
         [0029]    The embodiment of FIGS. 8, 9, and  10 , as earlier noted, is an adaptation of the fluid distribution system of the larger face mill of FIGS.  1  to  7  to milling cutters of smaller diameter, e.g., four inches. In the smaller diameter version the well closure  34 , its attaching screws  32 , and the cap screws  46  for securing the cutter head  20  to the adapter plate  22 , are combined in a specially adapted cap screw  70 , which, when assembled with the cutter head  20 ′ and the adapter plate  22 ′, provides the cutter fluid distribution system, delivering to the face  52 ′ of the cutter head  20 ′ a film of cutting fluid which proceeds by centrifugal force to the rim  50 ′ and through the slots  60 ′ to bathe the cutting inserts  56 ′ and the chip gullets  58 ′ about the periphery of the cutter head  20 ′.  
         [0030]    The special cap-screw closure  70  (FIGS. 8 and 9) incorporates a large flat cap or head  72 , larger in diameter than the central bore  30 ′ of the cutter head  20 ′ and overlying the radially inner half of the face  52 ′ of the cutter head (FIG. 10). The underside of the screw head  72  is undercut axially at  74  in opposition to a counterbore  76  of comparable radial extent in the central bore  30 ′ of the cutter head. Together, the undercut  74  of the screw head  72  and the counterbore  76  form an annular reservoir chamber  78  (FIG. 10). Radially outwardly of the peripheral ring  80  formed by the undercut  74 , the underside of the head  72  is milled to the lesser axial depth of some twenty thousandths inches (0.020″) to provide shallow radial channels  82  between stand off pads  84  (FIGS. 8 and 9) when the latter meet the face  52 ′ of the cutter head as the screw closure  70  is tightened into holding contact with the cutter head, using an Allen wrench in the central hexagonal socket  86  of the screw head.  
         [0031]    Adjacent to the enlarged head  72 , the screw is undercut radially in a shallow ring  88  to define a plug  90  which substantially closes the central bore  30 ′ of the cutter head  20 ′, while the necked down ring  88  serves to increase the radial dimension of the annular reservoir chamber  78  (FIG. 10).  
         [0032]    The cap screw  70  is drilled on its axis through an integral threaded shank  92  extending from the plug  90  to form a blind central conduit  94  which is penetrated by multiple holes  96  drilled radially into the screw in the undercut  98 . The holes  96  communicate with the annular chamber  78 .  
         [0033]    In the case of the smaller diameter cutter, the central hole  28 ′ of the adapter plate  22 ′ is counterbored and threaded within the pilot boss  42 ′ to receive the threaded shank  92  of the cap screw  70 . When the three parts, i.e., adapter plate  22 ′, cutter head  20 ′, and cap-screw  70 , are assembled (FIG. 10), the cutting fluid path, depicted by the arrow  98 , is upward in FIG. 10 through the aligned central bores  28 ′ and  94  of the adapter plate  22 ′ and cap screw  70 , respectively, then radially outwardly through the holes  96  to the annular chamber  78  surrounding the cap screw  70  on the underside of its head  72 .  
         [0034]    The chamber  78  manifolds the several holes  96 , serving as a collector ring and as a spinning reservoir from which the cutting fluid, emanating under pressure from the spindle, is further pressurized by centrifugal force to escape through the radial channels  82  on the underside of the cap screw head  72  to flow across the face  52 ′ of the cutter on its way to bathe, cool, and lubricate the peripheral cutting inserts  56 ′.  
         [0035]    As with the escape channels formed on the underside of the cap  36  of the well closure  34  of the first-described embodiment, the flow path of the cutting fluid of the smaller cutter of FIGS.  8  to  10  is made and unmade with each assembly and disassembly of the cutter head with the adapter plate for routine maintenance, i.e., the indexing and replacement of the cutting inserts, resulting in the automatic and incidental maintenance of the cutting fluid channels from the pressurized source in the spindle to the face of the cutter head.  
         [0036]    The features of the invention believed new and patentable are set forth in the following claims.