Abstract:
A combination milling bit and cutter employed to machine a distal end of a workpiece is provided, in which the milling cutter includes a handle and a cutting portion formed on an end of the handle. The cutting portion includes two cutting edges; at least one of the two cutting edges comprises one cutting sub-edge for milling the distal end of the workpiece to form an end surface, and another cutting sub-edge for chamfering the distal end of the workpiece at both an annular outer chamfering surface and an annular inner chamfering surface on the distal end. The combination milling and cutting cutter device carries out both milling and cutting actions in a single operation.

Description:
BACKGROUND  
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to a cutter, and more particularly, to a milling cutter. 
         [0003]    2. Description of Related Art 
         [0004]    Referring to  FIG. 1 , a workpiece  100  produced by punching, which includes a base seat  10  and a rod portion  20  on the base seat  10 . The rod portion  20  includes a distal end  201  away from the base seat  10  and defines an axial hole  203  on the distal end  201  thereof. Burrs may be formed on the distal end  201  in the punching process. A conventional milling process is employed to machine the distal end  201  to remove the burrs, thereby forming an annular end surface  2044 , an annular outer chamfering surface  2013  and an annular inner chamfering surface  2015  on the distal end  201  of the rod portion  20 . The annular outer chamfering surface  2013  connects with the annular inner chamfering surface  2015  via the annular end surface  2044 . In detail, the milling steps of the conventional milling process are as follows: a flat-end milling cutter mills the distal end  201  to form the annular end surface  2044 ; an outer R cutter chamfers an outer periphery of the distal end  201  to form the annular outer chamfering surface  2013 ; and an inner R cutter chamfers an inner periphery of the distal end  201  to form the annular inner chamfering surface  2015 . However, the milling process is time-consuming. In addition, the annular inner chamfering surface  2015  and the annular outer chamfering surface  2013  are produced or formed independently, segmental differences between the annular inner chamfering surface  2015 , the annular end surface  2044 , and the annular outer chamfering surface  2013  are easily created or formed, and a quality thereof is thereby reduced. 
         [0005]    Therefore, there is room for improvement in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0006]    The components in the drawings are not necessarily drawn to scale, the emphasis instead placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0007]      FIG. 1  is an isometric view of a workpiece produced by a conventional milling process. 
           [0008]      FIG. 2  is an isometric view of an embodiment of a milling cutter. 
           [0009]      FIG. 3  is an enlarged view of a circled portion III of the milling cutter of  FIG. 2 . 
           [0010]      FIG. 4  is an isometric view of the milling cutter of  FIG. 2  shown in a state of use. 
       
    
    
     DETAILED DESCRIPTION  
       [0011]      FIGS. 2 through 4  show an embodiment of a milling cutter  200  for milling a workpiece  300 . The workpiece  300  produced includes a base seat  12  and a rod portion  22  on the base seat  12 . The rod portion  22  includes a distal end  221  away from the base seat  12  and defines an axial hole  223  on the distal end  221 . The milling cutter  200  mills the distal end  221  to remove the burrs, thereby forming an annular end surface  2244 , an annular outer chamfering surface  2213  and an annular inner chamfering surface  2215  on the distal end  221  of the rod portion  22  of the workpiece  300 . The annular outer chamfering surface  2213  connects with the annular inner chamfering surface  2215  via the annular end surface  2244 . 
         [0012]    The milling cutter  200  is substantially a rod shape, and includes a handle  40  and a cutting portion  60  on an end of the handle  40 . The handle  40  is substantially a cylindrical shape, and a cross-sectional view taken perpendicular to a central axis a thereof shows substantially a circular shape. The handle  40  is fixed to a driving mechanism (not shown), such as a CNC machine. In the illustrated embodiment, the handle  40  extends along the central axis a, and rotates around the central axis a, thereby driving the cutting portion  60  to mill the workpiece  300 . The cross-sectional view of the handle  40  taken perpendicular to the central axis may be a rectangular, triangular or other shape. 
         [0013]    The cutting portion  60  of the milling cutter  200  includes a pair of cutting edges  62  arranged along a radial direction of the cutting portion  60 . The two cutting edges  62  face each other and are offset from each other along the radial direction of the cutting portion  60 . Each cutting edge  62  includes a first cutting sub-edge  622 , a second cutting sub-edge  624 , a third cutting sub-edge  626 , connected in that order. The second cutting sub-edge  624  interconnects the first cutting sub-edge  622  and the third cutting sub-edge  626  and is depressed toward the handle  40 . The first cutting sub-edge  622  is located adjacent to a periphery of the cutting portion  60 , the third cutting sub-edge  626  is located adjacent to a center of the cutting portion  60 , and the second cutting sub-edge  624  is perpendicular to the central axis a of the handle  40 . The first cutting sub-edge  622  and the second cutting sub-edge  624  cooperatively define a first intersection angle α therebetween, and the third cutting sub-edge  626  and the second cutting sub-edge  624  cooperatively define a second intersection angle β therebetween. The first intersection angle α is an obtuse angle and is equal to the second intersection angle β. In other embodiments, the first intersection angle α may be not equal to the second intersection angle β. Each cutting edge  62  connects with the other cutting edge  62  via the third cutting edges  626 . Each cutting edge  62  further defines a rack surface  64  at a front side thereof facing the other one cutting edge  62 , a flank surface  66  away from the rack surface  64 , and a chip removal surface  68  at a side of the third cutting sub-edge  626  away from the first cutting sub-edge  622 . Front edges of the first cutting sub-edge  622 , the second cutting sub-edge  624  and the third cutting sub-edge  626  are coplanar with the rack surface  64 . The chip removal surface  68  is located at the front of the rack surface  64  of the other one cutting edge  62 . A distance between the chip removal surface  68  and the first cutting sub-edge  622  increases along the central axis a toward the handle  40 , and the chip removal surface  68  connects with a periphery of the handle  40 . In the embodiment, each cutting edge  62  further includes a connecting edge  627  connected to an end of the third cutting sub-edge  626  away form the second cutting sub-edge  626 . The two cutting edges  62  are connected to each other via the connected edges  627 , and the chip removal surface  68  is located at a side of the connecting edge  627  away from the third cutting sub-edge  626 . 
         [0014]    In the embodiment, the number of the cutting edges  62  is two and the two cutting edges  62  are aligned in a straight line. The first cutting sub-edge  622 , the second cutting sub-edge  624 , and the third cutting sub-edge  626  are integrally formed with the handle  40 , thereby obtaining a more compact structure. Thus, the milling cutter  200  is suitable for machining a small workpiece. The cutting portion  60  may include more (or extra) cutting edges  62  separately aligned along a radial direction of the cutting portion  60 . The milling cutter  100  is made of suitable materials. Normally, the milling cutter  100  is made of hard alloy or high-speed steel (HSS) which have a higher hardness and better heat-dissipating properties. The pair of first cutting sub-edges  622  may be coated with a hard film layer to enhance a performance of the milling cutter  200 . In view of the requirements of the milling cutter  200 , the hard film(s) layer may be made of titanium carbide (TiC), aluminum titanium nitride (AlTiN), titanium aluminum nitride (TiAlN), or titanium carbon nitride (TiCN). 
         [0015]    Also referring to  FIG. 4 , when in use, the milling cutter  200  is held by the driving mechanism of the CNC machine, the central axis a of the handle  40  is coaxial with an axial direction of the workpiece  300 . The second cutting sub-edge  624  resists the annular end surface  2244  of the workpiece  300 . The third cutting sub-edge  626  is partially received in the axial hole  223  and defines an angle with the inner surface of the workpiece  300 . The first cutting sub-edge  622  and the outer surface of the workpiece  300  define an angle. The milling cutter  200  rotates clockwise around the central axis a to machine the distal end  221  of the workpiece  300 , thereby forming the annular end surface  2244  (of finished shape and condition) by the second cutting sub-edge  626 , the annular outer chamfering surface  2213  by the first cutting sub-edge  622 , and the annular inner chamfering surface  2215  by the third cutting sub-edge  626 . When the annular outer chamfering surface  2213  is not needed, the first cutting sub-edge  622  may be omitted. When the annular inner chamfering surface  2215  is not needed, the third cutting sub-edge  626  may be omitted. 
         [0016]    The cutting edge  62  employs the first cutting sub-edge  622 , the second cutting sub-edge  624  and the third cutting sub-edge  626  in that order to machine the workpiece  300 , and forms the annular end surface  2244 , the outer chamfering surface  2213 , and the inner chamfering surface  2215  in one operation, which is a great time-saver. Segmental differences between the inner chamfering surface  2013 , the end surface  2044 , and the outer chamfering surface  2015  found in the workpiece  100  made by conventional milling process using various milling cutters are thereby sharply reduced as compared to the workpiece  300  of the embodiment. The milling cutter  200  may be employed to machine other portion of a workpiece, such as machining an end of a side wall of the workpiece. 
         [0017]    Finally, while various embodiments have been described and illustrated, the disclosure is not to be construed as being limited thereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the appended claims.