Cutting head having resilient male coupling member for cutting tool and method of assembly thereof

[0001] The subject matter of the present application relates to cutting tools of the type in which a cutting head is releasably retained in a tool holder by means of a resilient coupling mechanism.

[0002] Cutting heads can be provided with a resilient coupling mechanism for securely fastening the cutting head in a tool holder.

[0003] Such resilient coupling mechanisms usually consist of a male coupling member on the cutting head and a female coupling member on a tool holder. There can be a resilience slit on the male coupling member that creates an interference fit when the male coupling member is forced into the female coupling member, forming a locked position.

[0004] Various cutting heads and cutting tools are disclosed in U.S. Pat. No. 5,228,812, US 2010/143059 and U.S. Pat. No. 7,048,480.

[0005] In accordance with a first aspect of the subject matter of the present application there is provided a cutting head, having a head longitudinal axis extending in a forward to rearward direction, comprising:

[0006] a forward portion forming a cutting portion and a rearward portion forming a mounting portion;

[0007] the mounting portion having two opposing major surfaces and a base surface extending therebetween;

[0008] a male coupling member protruding from the base surface, the male coupling member comprising a coupling member rear surface spaced apart from the base surface and a coupling member peripheral surface extending therebetween;

[0009] a central resilience slit extending between the two major surfaces and opening out to the male coupling member;

[0010] at least one lateral resilience slit extending between the two major surfaces and opening out to the base surface; wherein

[0011] the central resilience slit and the at least one lateral resilience slit have forwardmost central and lateral resilience slit points, respectively, located forward of the base surface.

[0012] In accordance with a further aspect of the subject matter of the present application, there is also provided a cutting tool comprising:

[0013] a cutting head; and

[0014] a tool holder, having a holder longitudinal axis extending in a forward to rearward direction, comprising an insert pocket forming a forward portion, the insert pocket comprising two pocket abutment surfaces facing in generally opposite directions and a forward facing holder base abutment surface extending therebetween, the holder base abutment surface comprising a female coupling member; wherein

[0015] each of the two major surfaces includes a cutting head abutment surface;

[0016] in a major side view, a base plane defined by the base surface intersects the coupling member peripheral surface at two lateralmost points thereof, defining a coupling member width; and

[0017] the cutting tool is adjustable between a released position and a locked position, wherein:

[0018] in the locked position:

[0019] the male coupling member is resiliently retained in the female coupling member; and

[0020] at least one of the pocket abutment surfaces abuts a corresponding cutting head abutment surface; wherein

[0021] the coupling member width is smaller in the locked position than in the released position.

[0022] In accordance with a still further aspect of the subject matter of the present application, there is provided a method of assembling a cutting tool comprising the steps of:

[0023] a) positioning the cutting head forward of the tool holder with the cutting portion facing in the forward direction and the head longitudinal axis approximately coaxial with the holder longitudinal axis;

[0024] b) slidingly inserting the male coupling member into the female coupling member; and

[0025] rotating the cutting head less than 90° in one direction about its head longitudinal axis from the released position to the locked position.

[0026] In accordance with a still further aspect of the subject matter of the present application, there is provided a cutting head, having a head longitudinal axis extending in a forward to rearward direction, comprising:

[0027] a forward portion forming a cutting portion; and

[0028] a rearward portion forming a mounting portion having:

• • [0029] a base surface facing in the rearward direction and defining a base plane, and
  • [0030] a pair of resilient male fixation legs extending in a forward-to-rearward direction on both sides of the base plane, the male fixation legs being separated from one another by a central resilience slit which extends forward of the base plane; wherein:
  • [0031] at least one of the male fixation legs is defined:
  • [0032] on an inner side thereof by the central resilience slit; and
  • [0033] on an outer side thereof by an inner wall of a lateral resilience slit which extends forward of the base plane, and a peripheral surface which extends rearward of the base plane and forms a continuous surface with the inner wall of the lateral resilience slit.

[0043] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity, or several physical components may be included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[0044] 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.

[0045] Attention is first drawn to FIGS. 1 and 2 showing a cutting tool 20 of the type used for drilling operations, in accordance with embodiments of the subject matter of the present application. The cutting tool 20 has a cutting head 22, 122, 222 that has a head longitudinal axis A that extends in a forward D_F to rearward direction D_R and a tool holder 24 that has a holder longitudinal axis C. The cutting head 22, 122, 222 can be secured in the tool holder 24 by means of a coupling mechanism.

[0046] It should be appreciated that use of the terms “forward” and “rearward” throughout the description and claims refer to a relative position in a direction of the head longitudinal axis A towards the top and bottom, respectively, in FIGS. 3, 6 to 8.

[0047] Reference is now made to FIGS. 3 to 6. The cutting head 22, 122, 222 has a forward portion that forms a cutting portion 28 and a rearward portion that forms a mounting portion 30. The mounting portion 30 has two opposing major surfaces 32 and a base surface 36 that extends therebetween.

[0048] In accordance with some embodiments of the subject matter of the present application the base surface 36 can be planar and perpendicular to the head longitudinal axis A. Whether or not the base surface 36 itself is planar, the innermost portion(s) of the base surface 36 define a base plane P2 which is perpendicular to the head longitudinal axis A.

[0049] A male coupling member 26 protrudes from the base surface 36 in the rearward direction beyond the base plane P2. The male coupling member 26 has a coupling member rear surface 42 spaced apart in the rearward direction D_R from the base surface 36 and a coupling member peripheral surface 44 that extends therebetween. In accordance with some embodiments of the subject matter of the present application the male coupling member 26 can extend along a coupling member longitudinal axis B in the rearward direction D_R. The coupling member rear surface 42 can face in the rearward direction D_R. The coupling member rear surface 42 can be planar and perpendicular to the coupling member longitudinal axis B. The head longitudinal axis A and the coupling member longitudinal axis B can be co-axial. The coupling member rear surface 42 can define a rear plane P3 which is rearward of, and parallel to, the base plane P2.

[0050] A central resilience slit 50 extends between the two major surfaces 32 and opens out to the male coupling member 26. In accordance with some embodiments of the subject matter of the present application the central resilience slit 50 can open out to the coupling member rear surface 42. In a major side view, the central resilience slit 50 can have a generally constant central resilience slit width W1, where the central resilience slit width W1 is measured perpendicular to the head longitudinal axis A. The coupling member longitudinal axis B can be contained in a first plane P1 that longitudinally bisects the central resilience slit 50. In accordance with some embodiments of the subject matter of the present application, the central resilience slit 50 can bisect the male coupling member 26.

[0051] Referring to FIG. 5, in accordance with a first embodiment of the subject matter of the present application, the central resilience slit 50 can open out to a portion the base surface 36.

[0052] It should be appreciated that use of the term “major side view” throughout the description and claims refer to a view of the cutting head 22, 122, 222 from a direction generally perpendicular to the two major surfaces 32, such as seen in FIGS. 3, 7 and 8.

[0053] At least one lateral resilience slit 52 extends between the two major surfaces 32 and opens out to the base surface 36. In accordance with some embodiments of the subject matter of the present application each of the at least one lateral resilience slit 52 can open out to the base surface 36 adjacent the male coupling member 26. A radially inner wall 53 of the lateral resilience slit 52 which extends forward of the base plane P2 forms a continuous surface with the male coupling member's peripheral surface 44 which extends rearward of the base plane P2. In a major side view, the rear portion of the at least one lateral resilience slit 52 can have a generally constant lateral resilience slit width W2. In a bottom view, as shown in FIG. 5, the central resilience slit 50 and the at least one lateral resilience slit 52 can be parallel. Each of the at least one lateral resilience slit 52 can diverge away from the central resilience slit 50 in the forward direction D_F.

[0054] Referring now to FIG. 8, in accordance with a third embodiment of the subject matter of the present application, in a major side view, the rear portion of the at least one lateral resilience slit 52 can be parallel to the head longitudinal axis A.

[0055] The central resilience slit 50 and the at least one lateral resilience slit 52 have forwardmost central and lateral resilience slit points P_CS, P_LS, respectively, which are located forward of the base surface 36 and/or the base plane P2. That is to say, the central resilience slit 50 has a central resilience slit point P_CS located forward of the base surface 36 and/or the base plane P2, and the at least one lateral resilience slit 52 has a lateral resilience slit point P_LS located forward of the base surface 36 and/or the base plane P2. In accordance with some embodiments of the subject matter of the present application each of the at least one lateral resilience slit points P_LS can be located a lateral resilience slit distance D_LS from the base surface 36. A rearmost coupling member point P_CM on the male coupling member 26 can be located a male coupling member distance D_CM from the base surface 36 and/or the base plane P2. Each lateral resilience slit distance D_LS can be greater than the male coupling member distance D_CM. The forwardmost central resilience slit point P_CS can be located a central resilience slit distance D_CS from the base surface 36 and/or the base plane P2. The central resilience slit distance D_CS can be greater than each lateral resilience slit distance D_LS. In some embodiments, the central resilience slit distance D_CS and the lateral resilience slit distance D_LS are typically within 50% of each other. A forwardmost cutting head point P_CH on the cutting head 22, 122, 222 can be located a cutting head distance D_CH from the base surface 36 and/or the base plane P2. The male coupling member distance D_CM can be less than a third of the cutting head distance D_CH.

[0056] In accordance with first and second embodiments of the subject matter of the present application, as shown in FIGS. 3 and 7, the forward portion of the at least one lateral resilience slit 52 can have a generally circular shape that has a radius of curvature R. The radius of curvature R can be generally equal to the lateral resilience slit width W2.

[0057] Referring now just to FIG. 7, in accordance with a second embodiment of the subject matter of the present application the forward end portion of the at least one lateral resilience slit 52 can have a straight portion generally perpendicular to the head longitudinal axis A that has a straight portion width W3 generally equal to twice the radius of curvature R. The purpose of having such a configuration is to provide a space for the insertion of a locking projection (not shown) located on the tool holder 24.

[0058] In accordance with some embodiments of the subject matter of the present application there can be exactly two lateral resilience slits 52. The exactly two lateral resilience slits 52 can be disposed either side of the male coupling member 26.

[0059] By virtue of the central resilience slit 50 and the at least one lateral resilience slit 52 with the geometry and structural properties defined hereinabove, the male coupling member 26 has greater resilience compared to other prior art male coupling members.

[0060] Further in accordance with some embodiments of the subject matter of the present application the cutting head 22, 122, 222 can exhibit two-fold rotational symmetry about the head longitudinal axis A.

[0061] Another aspect of the subject matter of the present application includes the cutting tool 20. The cutting tool 20 includes the cutting head 22, 122, 222 and the tool holder 24. The tool holder 24 has the holder longitudinal axis C that extends in the forward D_F to rearward direction D_R. The tool holder 24 has an insert pocket 54 that forms a forward portion. The insert pocket 54 includes two pocket abutment surfaces 56 facing in generally opposite directions and a forward facing holder base abutment surface 58 that extends therebetween. The holder base abutment surface 58 includes a female coupling member 60. In accordance with some embodiments of the subject matter of the present application, the two pocket abutment surfaces 56 can be parallel to the holder longitudinal axis C.

[0062] Each of the two major surfaces 32 on the cutting head 22, 122, 222 includes a cutting head abutment surface 38. In accordance with some embodiments of the subject matter of the present application the mounting portion 30 can include two opposing minor surfaces 34 that extend between the two major surfaces 32.

[0063] In a major side view, the base plane P2, and an imaginary line L that extends along the periphery of the base surface 36, intersect the coupling member peripheral surface 44 at two lateralmost points P_L thereof to define a coupling member width W_CM. In accordance with some embodiments of the subject matter of the present application the imaginary line L can intersect the two minor surfaces 34 at two outermost points Po thereof, to define a mounting portion width W_MP.

[0064] In accordance with some embodiments of the subject matter of the present application the female coupling member 60 can be in the form of a coupling bore 66. The coupling bore 66 extends along the holder longitudinal axis C and can only open out to the holder base abutment surface 58. In the other words, the tool holder 24 is devoid of radially extending slits and passageways which connect to the coupling bore 66. The coupling bore 66 can be non-cylindrical.

[0065] The cutting tool 20 is adjustable between a released position and a locked position. In a released position the cutting head 22, 122, 222 is unattached to the tool holder 24. In the locked position, the male coupling member 26 is resiliently retained in the female coupling member 60. At least one of the pocket abutment surfaces 56 abuts a corresponding cutting head abutment surface 38 and functions as a driving surface to transmit torque from the tool holder 24 to the cutting head. In accordance with some embodiments of the subject matter of the present application the holder base abutment surface 58 can abut the base surface 36.

[0066] The coupling member width W_CM is smaller in the locked position than in the released position. That is to say all points on the male coupling member 26 are under deflection. Moreover, the mounting portion width W_MP is the same in the locked position as in the released position. That is to say no points on the mounting portion 30 are under deflection.

[0067] Another aspect of the subject matter of the present application includes a method of assembling the cutting tool 20. The cutting head 22, 122, 222 is positioned forward of the tool holder 24 with the cutting portion 28 facing in the forward direction D_F and the head longitudinal axis A approximately coaxial with the holder longitudinal axis C. The male coupling member 26 is slidingly inserted into the female coupling member 60. The cutting head 22, 122, 222 is rotated less than 90° in one direction about its head longitudinal axis A from the released position to the locked position.

[0068] The male and female coupling members 26, 60 are designed to provide an interference fit in the locked position. To attach the cutting head 22, 122, 222 to the tool holder 24 the male coupling member 26 can be freely placed in the female coupling member 60 by virtue of a clearance fit. The cutting head 22, 122, 222 is then rotated about the head longitudinal axis A until an interference fit is achieved. The central resilience slit 50 and the at least one lateral resilience slit 52 provide flexibility to the male coupling member 26 which enable the width of the male coupling member 26 to be made smaller by applying a force perpendicular to the central resilience slit 50.

[0069] The male coupling member 26 has two spaced apart male fixation legs 62. On applying such a force, the two male fixation legs 62 are moved closer to each other and a resilience force is set up in the male coupling member 26 which urges the male fixation legs 62 apart to their original position. It should be appreciated that the term “male coupling member” in the present application refers to the portions of the male fixation legs 62 that protrude from the base surface 36. In other words, any point on the male fixation legs 62 that, in a major side view, is located on, or rearward of, the imaginary line L and/or base plane P2.

[0070] It can be seen from the foregoing that the male fixation legs 62 and the central resilience slit 50 both extend in a forward-to-rearward direction on both sides of the base plane P2. At least one of the male fixation legs 62 is defined on an inner side thereof (the side closest to the head longitudinal axis A) by the central resilience slit 50. At least one of the male fixation legs 62 is further defined on an outer side thereof by the inner wall 53 of the lateral resilience slit 52 which extends forward of the base plane P2, and the peripheral surface 44 which extends rearward of the base plane P2 and forms a continuous surface with the inner wall 53 of the lateral resilience slit 52. Both male fixation legs 62 can be configured as above, where the peripheral surface 44 forms a continuous surface with the inner wall 53 of the lateral resilience slit 52.

[0071] It should be noted that an advantageous feature of subject matter of the present application is that the distance between the rearmost coupling member point P_CM on the male coupling member 26 and the base surface 36, i.e. the male coupling member distance D_CM, can be reduced, since the combination of the central resilience slit 50 and the at least one lateral resilience slit 52 that all extend forwardly in relation to the base surface 36 make the male coupling member 26 highly resilient. Having a shorter male coupling member 26 provides it with improved strength.

[0072] Another advantageous feature of subject matter of the present application is that the male coupling member 26 can be manufactured with a reduced engineering tolerance. This is by virtue of the fact that the entire male coupling member 26 is resilient and can be put under deflection.

[0073] Still another advantageous feature of subject matter of the present application is the cutting portion 28 is devoid of elastic deformation when the cutting head 22, 122, 222 is secured in the tool holder 24. This provides a cutting portion 28 with a precisely located cutting edge 64.

[0074] Still yet another advantageous feature of subject matter of the present application is the female coupling member 60 being in the form of a coupling bore 66 which only opens out to the holder base abutment surface 58. The coupling bore 66 beneficially provides a rigid and fixed boundary against which the two male fixation legs 62 can undergo deflection.

[0075] Although the subject matter of the present application has been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the spirit or scope of the invention as hereinafter claimed.