Patent Document

FIELD OF THE INVENTION 
     The subject matter of the present application relates to fluted drills having replaceable cutting heads. 
     BACKGROUND OF THE INVENTION 
     Fluted drills having replaceable cutting heads are disclosed, for example in U.S. Pat. No. 5,957,631. Such replaceable cutting heads allow the cutting head to be replaced when it has become worn without having to replace the entire drill thereby reducing costs and waste of material. 
     SUMMARY OF THE INVENTION 
     In accordance with the subject matter of the present application there is provided a fluted drill cutting head comprising: two drilling portions facing axially opposite directions with respect to a head rotation axis, a plurality of cutting head coupling portions and a plurality of head flute portions; wherein, in an axial view, the cutting head has at least four see-through openings. The cutting head can have an axial head length L measured along the head rotation axis between axial extremities of the cutting head and a head diameter D measured radially in a direction perpendicular to the head rotation axis between radial extremities of the cutting head. The cutting head can fulfill the condition L&lt;2D. More precisely, the cutting head can fulfill the condition L&lt;D. The cutting head can be devoid of a radial through hole. The cutting head have a unitary, one-piece construction. The cutting head can be devoid of releasable or moving parts. The cutting head can be devoid of cutting inserts. The cutting head can be made of cemented carbide. The cutting head can be devoid of an elongated body section disposed between the two drilling portions. 
     Each head flute portion of one drilling portion can merge with an associated head flute portion of the other drilling portion to form a common head flute. The head flute portions can be non-flat. The head flute portions can be concavely curved in an axial view. 
     Each cutting head coupling portion can comprise a cutting portion and a non-cutting portion. The cutting portion and the non-cutting portion can be adjacent to each other. Each cutting head coupling portion can have an angular extension α&gt;10°. Each cutting head coupling portion can have at least one circumferentially facing driven surface and at least one axial abutment surface. Each cutting head coupling portion can comprise a clamping recess. 
     The clamping recess can comprise a driven surface and a head centering surface. The clamping recess can be located between the cutting portion and the non-cutting portion. Each clamping recess of one of the two drilling portions can merge with an associated clamping recess of the other drilling portion to form a common head clamping recess. 
     Each cutting portion can comprise a cutting edge formed at least partially by the intersection of an associated head flute portion and an associated relief surface. Each cutting portion of one drilling portion can merge with an associated non-cutting portion of the other drilling portion. 
     Each cutting portion of one of the two drilling portions can comprise a margin edge which connects with the cutting edge at a cutting corner. The margin edge can extend from the cutting corner to the associated non-cutting portion of the other drilling portion. A section of the margin edge adjacent the cutting corner can be a wiper. The margin edges can be alternately operative and non-operative margin edges. Each head flute portion can extend between an adjacent operative margin edge and an adjacent non-operative margin edge. 
     The non-cutting portion can be devoid of cutting edges. 
     A cutting head abutment surface can be located between angularly adjacent head flute portions. Each cutting head abutment surface can comprise leading and trailing abutment surface ends. The leading and trailing abutment surface ends can be located on respective adjacent cutting and non-cutting portions of the same drilling portion. 
     A head centering surface of the cutting head can be discontinuous. Each head centering surface can be axially located between associated opposite cutting head abutment surfaces of each drilling portion. 
     Each driven surface can extend from a leading abutment surface end of a cutting portion of one drilling portion, to an opposite trailing abutment surface end located on an associated non-cutting portion of the other drilling portion. 
     In accordance with another aspect of the subject matter of the present application, there is provided a fluted drill body having a body rotation axis, the fluted drill body comprising a clamping portion at a forward end, a shank portion extending axially rearwardly from the clamping portion and body flutes extending along the fluted drill body, the clamping portion comprising a plurality of drill body coupling portions, each drill body coupling portion comprising: 
     a cutting head support surface comprising leading and trailing support surface ends; and 
     an integrally formed clamping jaw extending forwardly from the respective cutting head support surface, each clamping jaw comprising: 
     opposite inner and outer side surfaces; 
     front and back side surfaces extending between the inner and outer side surfaces; 
     a drive surface located on the front side surface and facing generally in a rotation direction, 
     a body centering surface located on the inner side surface and facing inwards, towards the body rotation axis; and 
     a pullout prevention member located adjacent a clamping jaw upper surface; the clamping portion further comprising a drilling portion housing located rearwardly of the cutting head support surfaces; 
     wherein 
     the body centering surface is axially located between the pullout prevention members and the cutting head support surfaces. 
     Each body flute can comprise a gash located axially adjacent the drilling portion housing, formed to match a web thinning region of a reversible fluted drill cutting head. 
     The body centering surface can be discontinuous. 
     Optionally, the drilling portion housing does not engage any portion of a cutting head mounted therein. 
     Each leading support surface end can be located adjacent the back side surface of each respective clamping jaw. 
     Each trailing support surface end can be located adjacent the front side surface of each respective clamping jaw. 
     The pullout prevention members can be clamping screws. The pullout prevention members can be clamping jaw extensions, each of which extends transversely from the clamping jaw in the turning direction. 
     The body centering surface can project radially inward from the inner side surface. 
     In accordance still another aspect of the subject matter of the present application, there is provided a fluted drill comprising the fluted drill body and the cutting head securely clamped to the fluted drill body; wherein at least one head flute portion of the cutting head aligns with a respective body flute of the fluted drill body. 
     Optionally, a non-operative drilling portion is accommodated by, and does not contact, the drilling portion housing of the fluted drill body. 
     Each pullout prevention member of the fluted drill body can engage a respective cutting head screw support surface of the cutting head. 
     The head flute portions and the body flutes can be devoid of protrusions. 
     The fluted drill can be configured for drilling at a drilling depth which surpasses an axial length of the cutting head. 
     In accordance with another aspect of the subject matter of the present application, there is provided a fluted drill comprising the fluted drill body and the cutting head securely clamped in the clamping portion of the fluted drill body; wherein 
     each cutting head coupling portion comprises: 
     a cutting portion and a non-cutting portion, each cutting portion comprising a cutting edge formed at least partially by the intersection of an associated head flute portion and an associated relief surface, the non-cutting portion being devoid of cutting edges, each cutting portion of one drilling portion merging with an associated non-cutting portion of the other drilling portion; 
     a clamping recesses located between an adjacent cutting portion and an adjacent non-cutting portion; the clamping recess comprising a driven surface facing opposite a turning direction of the drill and a head centering surface facing away from the head rotation axis; and 
     a cutting head abutment surface located between angularly adjacent head flute portions; each cutting head abutment surface associated with an operative drilling portion engages a respective cutting head support surface of the clamping portion; 
     at least one operative driven surface engages a respective drive surface; and 
     at least one head centering surface engages a respective body centering surface. 
     In accordance with still another aspect of the subject matter of the present application, there is provided a double-ended fluted drill cutting head comprising: 
     two drilling portions facing axially opposite directions with respect to a head rotation axis; 
     a plurality of cutting head coupling portions, each coupling portion having at least one circumferentially facing driven surface and also at least one axial abutment surface; and 
     a plurality of common head flute portions. 
     Each coupling portion can comprise a common head clamping recess. In an end view of the cutting head, the common head clamping recesses can be circumferentially spaced apart from the common head flute portions. 
     Each common head flute portion can comprise: a first leading flute end and a first trailing flute end associated with a first cutting edge belonging to a first cutting end of the cutting head; and a second leading flute end and a second trailing flute end associated with a second cutting edge belonging to a second cutting end of the cutting head. 
     It is understood that the above-said is a summary, and that any of the aspects above can further comprise, or be further defined with, any of the features described in connection with any of the other aspects or described hereinbelow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the subject matter of the present application and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings, in which: 
         FIG. 1  is an isometric view of a fluted drill; 
         FIG. 2  is an isometric exploded view of a portion of the drill of  FIG. 1 ; 
         FIG. 3  an isometric view of a cutting head of the drill of  FIG. 1 ; 
         FIG. 4  is a side exploded view of the portion of the drill of  FIG. 2 ; 
         FIG. 5  is an end view of the drill of  FIG. 1 ; 
         FIG. 6  is an end view of the cutting head of  FIG. 3 ; 
         FIG. 7  is an isometric view of a portion of another drill; and 
         FIG. 8  is an isometric exploded view of the portion of the drill of  FIG. 7 . 
     
    
    
     Where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, various aspects of the subject matter of the present application will be described. For purposes of explanation, specific configurations and details are set forth in sufficient detail to provide a thorough understanding of the subject matter of the present application. However, it will also be apparent to one skilled in the art that the subject matter of the present application can be practiced without the specific configurations and details presented herein. 
     Reference is made to  FIGS. 1 to 6 . A fluted drill  10  includes a fluted drill body  12  and a fluted drill cutting head  14  mounted in a clamping portion  16  of the fluted drill body  12 . The cutting head  14  has a head rotation axis A and includes, in this non-limiting example, a pair of identical drilling portions  18  ( 18 A,  18 B) located at axially opposite ends of the cutting head  14 . The cutting head  14  therefore constitutes a reversible cutting head  14 . According to some embodiments, each drilling portion  18  comprises a pair of diametrically disposed cutting head coupling portions  19 . As will be explained below, each coupling portion  19  can have an angular extension α&gt;10°. An axial head length L of the cutting head  14  is measured along the head rotation axis A between two axially outermost tips  20  of each drilling portion  18 . A head diameter D is defined by radial extremities of the drilling portions  18 . The head length L of the cutting head  14  can be shorter than its head diameter D, i.e., L&lt;D. According to other embodiments, the axial length L can be longer than the head diameter D, i.e., the ratio L/D can be less than 2. The cutting head  14  therefore has a compact shape. As the cutting head  14  is reversible and has a compact shape, it can also be considered a so-called cutting insert. This relation between length and diameter of the cutting head  14  can provide radial stability for the fluted drill  10 . Furthermore, it may prevent an undesired bending moment from being developed in the clamping portion  16 . 
     When the cutting head  14  is mounted on the fluted drill body  12 , one drilling portion  18  constitutes an operative drilling portion  18 A, and the other drilling portion  18 , which faces the drill body  12 , constitutes a non-operative drilling portion  18 B. 
     Each drilling portion  18  can include two cutting head coupling portions  19  and two head flute portions  42 . 
     Each cutting head coupling portion  19  can include a cutting portion  22 , a non-cutting portion  24 , a cutting head abutment surface  28  and a clamping recess  26 . The non-cutting portion  24  is devoid of cutting edges. In an axial view of the cutting head  14  (as shown in  FIGS. 5 and 6 ), each non-cutting portion  24  can be angularly located between two cutting portions  22 . Furthermore, each clamping recess  26  can be angularly located between an adjacent cutting portion  22  and an adjacent non-cutting portion  24 . Stated differently, in an axial view of the cutting head  14 , each head flute portion  42  is separated from each clamping recess  26 . Each head flute portion  42  is separated from each clamping recess  26 , by either a cutting portion  22  or a non-cutting portion  24 . In an axial, or plan view, the cutting head  14  can be X-shaped. Stated differently, in a view along the head rotation axis A, the cutting head  14  can have four see-through openings which extend from one drilling portion to another. The see-through openings can be either open or closed in the radial direction. In other words, each opening opens out to both drilling portions and can open out in a general direction perpendicular to the head rotation axis A. In this non-limiting embodiment, one pair of openings is associated with the clamping recesses  26  and another pair of openings is associated with the head flute portions  42 . The clamping recesses  26  are therefore separated from the head flute portion  42 , in order to direct the chip flow only into the head flute portions  42 . This arrangement is advantageous because cut chips can flow free-of-obstruction in the head flute portions  42 , and any clamping means of the drill body is protected from the cut chips. 
     In an axial view of the cutting head  14 , each cutting portion  22  extends radially between the head rotation axis A and a cutting corner  34 . Each cutting portion  22  can include a cutting edge  36  and a margin edge  38  ( FIG. 3 ). A section of the margin edge  38  adjacent the cutting corner  34  can constitute a wiper  39 . Depending on the orientation of the cutting head  14 , the margin edge  38  can constitute an operative or a non-operative margin edge  38 A,  38 B. Each cutting portion  22  of one drilling portion  18  can extend in the direction of the rotation axis A. Each cutting portion  22  of one drilling portion merges with a non-cutting portion  24  of the other drilling portion  18  (as shown in  FIG. 4 ). In accordance with some embodiments, each cutting edge  36  extends from the head rotation axis A to the cutting corner  34  of the cutting portion  22 . 
     In an axial view of the cutting head  14 , the angular extension a of each cutting head coupling portion  19  is measured between two imaginary lines perpendicular to the head rotation axis A. The first line passes through a cutting corner  34  of a cutting portion  22  of one drilling portion  18 . The second line passes through a cutting corner  34  of a cutting portion  22  of the other drilling portion  18 . 
     Each drilling portion  18  can include two head flute portions  42  (as shown in  FIG. 4 ). According to this non-limiting example, the head flute portions  42  can have a concavely curved shape, as viewed from an axial view. The curved design can help form chips for efficiently evacuating them along the flute. Each head flute portion  42  of one drilling portion  18  merges with an associated head flute portion  42  of the other drilling portion  18  to form a common head flute  44 . Each head flute portion  42  extends between an adjacent operative margin edge  38 A and an adjacent non-operative margin edge  38 B. Each head flute portion  42  can include leading and trailing flute ends  46 ,  48 , with respect to a direction of rotation T of the fluted drill  10  (as shown in  FIGS. 2 and 5 ). For each drilling portion  18 , the leading flute end  46  can be located on a cutting portion  22 , and the trailing flute end  48  can be located on an angularly-adjacent non-cutting portion  24 . The leading flute end  46  can face the rotation direction T. Each leading flute end  46  of a cutting portion  22  of one drilling portion  18  can extend from an associated cutting edge  36  and merge with an associated trailing flute end  48  of an associated non-cutting portion  24  of the other drilling portion  18 . Each trailing flute end  48  can terminate at an associated trailing abutment surface end  32 . Each leading flute end  46  can merge with a trailing flute end  48  of an angularly-adjacent non-cutting portion  24 . In accordance with some embodiments, each head flute portion  42  is provided with a web thinning region  50 . In this non-limiting example, the web thinning region  50  includes two gashes, one in each flute portion  42  ( FIG. 3 ), adjacent each tip  20  of each drilling portion  18 . 
     Each cutting portion  22  further includes a relief surface  40  which extends from the cutting edge  36 , generally opposite to the rotation direction T. The relief surface  40  meets the head flute portion  42 , at least partially, at the cutting edge  36 . 
     When the cutting edges of the operative drilling portion  18  become worn, the cutting head  14  is reversed, and the non-operative drilling portions  18 B become operative drilling portions  18 A. 
     Each cutting head abutment surface  28  can be located between angularly adjacent head flute portions  42  of a given drilling portion  18 . The cutting head abutment surfaces  28  can be perpendicular to the head rotation axis A. Each cutting head abutment surface  28  can include leading and trailing abutment surface ends  30 ,  32 . For each drilling portion  18 , each trailing abutment surface end  32  can be located on a non-cutting portion  24 , and each leading abutment surface end  30  can be located on an angularly-adjacent cutting portion  22 . Each trailing abutment surface end  32  associated with the operative drilling portion  18 A can extend from a respective trailing flute end  48  in a direction opposite the rotation direction T, towards an associated clamping recess  26 . Each leading abutment surface end  30  associated with the operative drilling portion  18 A can extend from adjacent a respective relief surface  40 , in the rotation direction T, towards an associated clamping recess  26 . 
     The margin edge  38  (see  FIG. 3 ), meets the cutting edge  36  at the cutting corner  34 . The margin edge  38  is located generally along the periphery of the cutting head  14 . According to some embodiments, each margin edge  38  extends from the cutting corner  34  to the non-cutting portion  24  so that it terminates at a respective trailing abutment surface end  32 . According to some embodiments, each cutting portion  22  includes a single cutting edge  36 , a single cutting corner  34  and a single margin edge  38 . 
     In an axial view of the cutting head  14  along the head rotation axis A, it can be seen that by changing α, one can (depending on the application) determine, or control, an overall sector size of the common head flutes  44 , at the expense of a sector size of the clamping recesses  26 . 
     According to some embodiments, the clamping recesses  26  are common to both drilling portions  18 , i.e., a clamping recess  26  of one drilling portion  18  merges with an associated clamping recess  26  of the other drilling portion  18  to form a common head clamping recess  52 . Each clamping recess  26  can include a head centering surface  54  and two driven surfaces  56 . The head centering surface  54  can be arched. The head centering surface  54  can be discontinuous, in the sense that it can be separated into sections. The head centering surface  54  may be located radially inwards in the cutting head  14 , towards the head rotation axis A, and faces outwards therefrom. In accordance with some embodiments, the head centering surface  54  extends between each cutting and non-cutting portions  22 ,  24  on the same drilling portion  18 . Each head centering surface  54  is axially located between respective opposite head abutment surfaces  28  of each drilling portion  18 . According to some embodiments, the head centering surfaces  54  are axially located substantially midway between axial extremities of the cutting head  14 . When assembled, this can minimize bending moments and aid to the drill&#39;s overall stability. In other words, with respect to the axis of rotation A, lateral, or radial centering forces will be directed as close as possible to the cutting edges, where lateral machining forces are generated, thus minimizing bending moments. 
     The driven surfaces  56  are separated into opposite operative and non-operative driven surfaces  56 A,  56 B, which alternate, in accordance with the position of the cutting head  14  in the drill body  12 . In other words, each driven surface  56  becomes an operative driven surface  56 A when associated with an operative drilling portion  18 A, and after reversing the cutting head  14 , it becomes a non-operative driven surface  56 B. According to some embodiments, each operative driven surface  56 A extends from a leading abutment surface end  30  associated with a non-operative drilling portion  18 B, to an opposite trailing abutment surface end  32  associated with an operative drilling portion  18 A. The operative driven surfaces  56 A face generally opposite direction of the rotation direction T. 
     The drill body  12  has a body rotation axis B which defines a forward to rearward direction, and a shank portion  62  which extends rearwardly from the clamping portion  16 . The drill body  12  can have two chip evacuating body flutes  64  which extend along the drill body  12  and are formed to match, and continue the shape of, the common head flutes  44  of the cutting head  14 . According to some embodiments, each body flute  64  has a single gash  66  formed at a forward portion of the body flute  64 . The gash  66  is formed to match, and continue the shape of, the web thinning region  50  of the respective head flute portion  42 , thus allowing chips to flow freely from the head flute portion  42  to the body flute  64 . The clamping portion  16  includes, according to some embodiments, two cutting head support surfaces  68 . According to some embodiments, the cutting head support surfaces  68  are generally perpendicular to the body rotation axis B. 
     According to some embodiments the clamping portion  16  comprises two diametrically disposed drill body coupling portions  69  for coupling with the cutting head coupling portions  19  when securing the cutting head  14  to the drill body  12 . Each drill body coupling portion  69  includes an integrally formed clamping jaw  70 , which extends forwardly from a respective cutting head support surface  68 . Each clamping jaw  70  includes inner and outer side surfaces  72 ,  74  and front and back side surfaces  76 ,  78  which extend between the inner and outer side surfaces  72 ,  74  and between the respective cutting head support surface  68  and a clamping jaw upper surface  80 . Each cutting head support surface  68  includes leading and trailing support surface ends  82 ,  84 . According to some embodiments, the leading support surface end  82  extends, oppositely the rotation direction T, from the back side surface  78  towards the periphery of the drill body  12 . According to some embodiments, each trailing support surface end  84  extends in the rotation direction T, from an associated front side surface  76  to an associated body flute  64 . In terms of resistance to bending moment (when the cutting head is assembled), this separation into leading and trailing abutment surface ends  30 ,  32  improves overall drill stability, by providing a distribution of abutment forces. 
     Each clamping jaw  70  includes a drive surface  86  which is located on the front side surface  76  and faces generally in the rotation direction T. According to some embodiments, each clamping jaw  70  further includes a body centering surface  88  which is located on the inner side surface  72  and faces generally inwardly towards the body rotation axis B. According to some embodiments, the body centering surface  88  projects radially inwards from the inner side surface  72 . The body centering surface  88  can be arched. The body centering surface  88  can be discontinuous, in the sense that it can be separated into sections. 
     The clamping portion  16  includes pullout prevention members. In some embodiments (shown in  FIGS. 7 and 8 ), the pullout prevention members are clamping jaw extensions  90  which overhang the drive surface  86 . According to these embodiments, each clamping jaw  70  includes one clamping jaw extension  90  which projects transversely, in the rotation direction T, from a forward-most portion of the front side surface  76  of the clamping jaw  70 . The body centering surfaces  88  engage the head centering surfaces  54  with an interference fit in order to center the cutting head  14  with respect to the drill body  12 . A difference between the curvature radiuses of the head and body centering surfaces  54 ,  88  may enable a tight friction-fit between the clamping jaws  70  and the cutting head  14 . In some embodiments, after the cutting head  14  has been assembled on the drill body  12 , in addition to centering the cutting head  14 , the body centering surfaces  88  may have an additional role of preventing axial rotation (about axis B and against the rotation direction T) of the cutting head  14  with respect to the drill body  12 . 
     In some embodiments, the pullout prevention members are clamping screws  58 . In such embodiments, each clamping jaw  70  includes a screw bore  92  to threadingly receive the clamping screw  58 . The screw bore  92  extends in a general longitudinal direction of the clamping jaw  70 . Each clamping jaw  70  may further include a body screw support surface  94  for providing support for the clamping screw  58 . The body screw support surface  94  forms a ledge projecting from the back side surface  78  of a respective clamping jaw  70  at a location between the clamping jaw upper surface  80  and the leading support surface end  82  of the cutting head support surface  68  from which the respective clamping jaw  70  projects. 
     The clamping portion  16  further includes a drilling portion housing  96 , which is centered on the rotation axis B. According to some embodiments, the drilling portion housing  96  extends rearwardly from the cutting head support surfaces  68  and is formed to accommodate the non-operative drilling portion  18 B of the cutting head  14 . The drilling portion housing  96  does not include any surfaces formed to engage surfaces on the cutting head  14  and does not engage any portion of the cutting head  14 . 
     In the assembled position of the fluted drill  10 , the cutting head  14  is securely clamped in the clamping portion  16  of the drill body  12 . The fluted drill is configured to drill at a drilling depth which surpasses the axial length L of the cutting head  14 . In this position, each cutting head abutment surface  28  associated with the operative drilling portion  18 A abuts a respective cutting head support surface  68  of the drill body  12 . Each clamping recess  26  receives a respective clamping jaw  70 , i.e. each clamping jaw  70  is located between a pair of adjacent cutting and non-cutting portions  22 ,  24  of a given cutting head coupling portion  19  of the operative drilling portion  18 A. At least one operative driven surface  56 A of each clamping recess  26  abuts a respective drive surface  86  of a respective clamping jaw  70  of the drill body  12 , in order to transfer torque from the drill body  12  to the cutting head  14 . In accordance with embodiments in which the pullout prevention members are clamping screws  58 , each clamping screw  58  is screw threaded into a respective screw bore  92  and abuts both the cutting head screw support surface  60  of the cutting head  14 , and the body screw support surface  94  of the drill body  12 . 
     The cutting head  14  may be of the sort used in metal cutting operations and thus can be termed a metal cutting head meaning that the cutting head  14  may be used for cutting metal, not necessarily that the cutting head  14  is made of metal. In accordance with some embodiments, the cutting head  14  may be made of hard wear resistant material such as cemented carbide, and the drill body  12  may be made of steel or of another metal or metal compound. In accordance with some embodiments, the cutting head  14  may be made of a hard wear resistant material such as cemented carbide, and the drill body  12  may also be made of a hard wear resistant material such as cemented carbide. The cutting head  14  can have a unitary one-piece construction. Stated differently, the cutting head  14  can be devoid of mechanical parts such as inserts. The cutting head can be devoid of radial through holes, oriented generally perpendicularly to the head rotation axis A. The cutting head can be devoid of an elongated body section. In particular, the cutting head  14  can be devoid of an elongated body section disposed between the two drilling portions. The cutting head  14  can be made of a core material, and can be at least partially coated by at least another material. The core material can be cemented carbide or a like material. 
     As previously disclosed, the cutting head  14  is designed with head flute portions  42 . As a result, initially, cut chips only hit the head flute portions  42 . The cutting head  14  therefore protects the clamping portion  16  of the drill body  12  from being worn by cut chips. 
     The description above includes exemplary embodiments and details for enablement, if needed, of claimed subject matter, and does not exclude non-exemplified embodiments and details from the claim scope of the present application.

Technology Category: y