A cutting head, tool holder, and rotary cutting tool having a fastening recess and a cutting arm with a dovetail joint rear contact surface.

Abstract

The cutting head (22) has two radially extending cutting arms and at least one fastening recess having an opening at least partially located on one of the cutting arms. Each cutting arm has a dovetail arm rear contact surface. The tool holder (24) has two drive members spaced apart in the circumferential direction. The tool holder has a pocket having two radially extending arm receiving receptacles. Each receptacle has a dovetail receptacle rear contact surface. The tool holder has at least one through hole located on one of the drive members. When assembled, a fastening member (26) is positioned in the through hole and engages with the fastening recess to bias each cutting arm toward the respective drive member.

Description

Technical Field

[0001] The subject matter of the present application relates to a rotary cutting tool of a type in which a cutting head is removably held by a connecting mechanism in a tool holder.

Background Art

[0002] A rotary cutting tool may include a cutting head removably attached to a tool holder. The cutting head may include at least two radially extending cutting arms. The tool holder may include at least two drive members defining a pocket having at least two arm receiving receptacles extending radially, and the numbers of the cutting arms, the drive members, and the arm receiving receptacles all match each other. Such a rotary cutting tool may be provided with a connecting mechanism for securely holding the cutting head in the pocket. The connecting mechanism may include at least one fastening member for removably holding the cutting head in the pocket, thereby forming an assembled state of the rotary cutting tool. In the assembled state, the cutting arms are in contact with the drive members.

[0003] Among such rotary cutting tools, there are those in which the cutting head is clamped by one or more clamping screws. Each clamping screw is disposed in a through hole formed in each cutting arm and is screwed into a screw hole of each drive member. An example of such a rotary cutting tool is disclosed in, for example, U.S. Patent No. 6,530,728, in which a set screw (a type of grub screw) is screwed into a female screw formed in a hole of a drill body, contacts a leading surface of a wing, and rotates an exchangeable drill tip, and as a result, a second support surface of a cutting insert abuts against a third support surface of the drill tip.

[0004] In other such rotary cutting tools, the cutting head is clamped by one or more set screws. The set screws are disposed in through holes of the cutting arms and are screwed into screw holes of the drive members. An example of such a rotary cutting tool is disclosed in, for example, European Patent No. 1,136,161.

[0005] In other types of rotary cutting tools, the cutting head is clamped between drive members. A clamping screw is positioned in a first through-hole in one of the drive members and a second through-hole in the cutting head, and is screwed into a threaded hole in the other drive member. The two drive members are pressed against each other to clamp the cutting head. An example of such a rotary cutting tool is disclosed, for example, in U.S. Patent No. 6,514,019. [Overview of the project]

[0006] According to a first aspect of the subject matter of the present application, a cutting head having a head central axis is provided, wherein the head central axis defines opposing forward and backward directions, and the cutting head is rotatable in a rotational direction about the head central axis, and the cutting head comprises a cutting portion. The aforementioned cut portion: Opposing head front end faces and head rear end faces, and a head circumferential surface extending between the head front end face and the head rear end face,: Two cutting arms, each cutting arm extending radially outward with respect to the head's central axis along its arm axis, and: An arm rotation leading surface and an arm rotation trailing surface are arranged on the head circumferential surface, wherein the arm rotation leading surface is located in front of the arm rotation trailing surface in the rotation direction; A forward-positioned main cutting blade formed along at least a portion of the intersection line between the arm rotation leading surface and the head front surface; The rear arm contact surface located on the rear surface of the head, the rear arm contact surface being inclined forward in a direction away from the rear arm rotation surface and toward the leading arm rotation surface; Two cutting arms, each comprising a driven surface positioned on the subsequent rotating surface of the arm; The at least one fastening recess opening in a recess opening at least partially located on the arm rotation trailing surface of each cutting arm associated with the at least one fastening recess; The at least one fastening recess comprises a recess circumferential surface extending around the central axis of the recess, the recess circumferential surface being oriented laterally with respect to the central axis of the head and having a recess contact surface facing away from the rear surface of the head.

[0007] According to a second aspect of the subject matter of the present application, a tool holder is provided having a holder longitudinal axis, the holder longitudinal axis extending in opposing forward and rearward directions, and the tool holder being rotatable in a rotational direction about the holder longitudinal axis, the tool holder: The holder circumferential surface extends circumferentially along the longitudinal axis of the holder and forms the boundary of the holder base surface facing forward at the front end of the tool holder: The holder has two circumferentially spaced holder grooves that are recessed on the circumferential surface of the holder and extend spirally around the longitudinal axis of the holder; The holder comprises two drive members that are spaced apart in the circumferential direction and extend forward from the holder base surface, and each drive member is: A driving member rotation leading surface and a driving member rotation trailing surface, wherein the driving member rotation leading surface is located in front of the driving member rotation trailing surface in the rotation direction, The drive surface arranged on the rotating surface of the drive member; A drive member through-hole extending along the axis of the drive member through-hole and opening on the rotating front surface of the drive member and the circumferential surface of the holder; A head receiving pocket formed between the two drive members spaced apart in the circumferential direction, the head receiving pocket comprising two arm receiving receptacles, each arm receiving receptacle extending radially outward with respect to the longitudinal axis of the holder along the receptacle axis, converging into the respective holder grooves in the rotational direction, and defined by the respective drive members in the direction opposite to the rotational direction; Each arm receiving receptacle is provided with a receptacle rear contact surface located on the holder base surface; With respect to any arm-receiving receptacle, the associated holder groove of the arm-receiving receptacle, and the associated drive member of the arm-receiving receptacle, the rear contact surface of the receptacle is inclined forward in the direction away from the associated drive member and toward the associated holder groove.

[0008] According to a third aspect of the subject matter of the present application, a rotary cutting tool is provided, the rotary cutting tool being: With the above-mentioned type of cutting head; A tool holder having opposing forward and rearward longitudinal axes, the tool holder being rotatable around the longitudinal axis; At least one fastening member; The rotary cutting tool comprises at least one fastening member that is adjustable between an detachment position and a fastening position in which the cutting head is detachably attached to the tool holder by the at least one fastening member.

[0009] According to a fourth aspect of the subject matter of the present application, a rotary cutting tool is provided, the rotary cutting tool being: With the above-mentioned type of cutting head; The above-mentioned type of tool holder and; A fastening member comprising, The rotary cutting tool is adjustable between a removal position and a fastening position, and in the fastening position: The cutting head is removably attached to the tool holder by the at least one fastening member; The head centering pin is positioned in the holder centering hole; Each cutting arm is positioned in its respective arm-receiving receptacle; Each driven surface contacts its respective driving surface; The rear contact surface of each arm contacts the respective receptacle contact surface; The at least one fastening member engages with the recess contact surface of the at least one fastening recess.

[0010] According to a fifth aspect of the subject matter of the present application, a cutting head having a head central axis is provided, wherein the head central axis defines opposing forward and backward directions, and the cutting head is rotatable in a rotational direction about the head central axis, and the cutting head comprises a cutting portion: The cutting portion does not have an insert sheet configured to receive a cutting insert, and the cutting portion is: Opposing head front end faces and head rear end faces, and a head circumferential surface extending between the head front end face and the head rear end face; Two cutting arms, each cutting arm extending radially outward with respect to the head's central axis along its arm axis, and: An opposing arm rotation leading surface and arm rotation trailing surface are arranged on the head circumferential surface, wherein the arm rotation leading surface is located in front of the arm rotation trailing surface in the rotation direction; A forward-positioned main cutting blade formed along at least a portion of the intersection line between the arm rotation leading surface and the head front surface; The rear contact surface of the arm located on the rear surface of the head; Two cutting arms comprising a driven surface positioned on the rear surface of the arm rotation; The at least one fastening recess comprises: at least one fastening recess opening into a recess opening at least partially located on the arm rotation trailing surface of each cutting arm associated with the at least one fastening recess; The at least one fastening recess comprises a recess circumferential surface extending about the central axis of the recess, the recess circumferential surface being oriented laterally with respect to the central axis of the head and having a recess contact surface facing away from the rear surface of the head; The at least one fastening recess is a blind hole and does not penetrate the entire thickness of each cutting arm so as to intersect both the rotation leading surface and the rotation trailing surface of each cutting arm.

[0011] The above is an overview, and it is understood that the features described below may be applicable in any combination to the subject matter of the present application. For example, any of the following features may be applicable to a rotary cutting tool, a cutting head, or a tool holder.

[0012] The recess central axis may intersect the head central axis.

[0013] In any fastening recess and the cutting arm associated with the any fastening recess, the recess contact surface may converge with the arm rear contact surface in a direction away from the arm rotation subsequent surface and toward the arm rotation leading surface.

[0014] The cutting head may further include a centering portion. The rear surface of the head may define a boundary between the cutting portion and the centering portion. The centering portion may include a head centering pin that projects rearward along the head central axis from the rear surface of the head. The cutting portion and the centering portion. The centering portion may include a head centering pin that projects rearward along the head central axis from the rear surface of the head.

[0015] In a perspective along the arm axis, the recess contact surface and the arm rear contact surface may form an acute arm engagement angle. The arm engagement angle may be greater than 5° and not more than 10°.

[0016] In a perspective along the arm axis, the arm rear contact surface may form an acute arm rear step angle with respect to a radial head surface oriented perpendicular to the head central axis. The arm rear step angle may be 10° or more and 30° or less.

[0017] The recess contact surface may slope forward in a direction away from the recess opening.

[0018] In a perspective along the arm axis, the recess contact surface may form a recess contact angle with respect to a radial head plane oriented perpendicular to the head central axis. The recess contact angle may be 15° or more and 25° or less.

[0019] The cutting portion may comprise exactly two cutting arms that are diametrically opposed to each other around the central axis of the head.

[0020] The cutting portion may have exactly two fastening recesses, each of which is associated with a different cutting arm.

[0021] The cutting portion may include a central portion in the radial direction of the head. Exactly two cutting arms may extend radially outward from the central portion in the radial direction of the head. The cutting portion may also include exactly two opposing chip breaker blades extending radially outward from the central portion in the radial direction of the head, each chip breaker blade positioned between the exact two cutting arms.

[0022] The two cutting arms may define the head outer diameter. The two chip breaker blades may define the blade width dimension measured perpendicular to the driven surface. The blade width dimension may be greater than half the head outer diameter.

[0023] The cutting portion does not necessarily have to have an insert sheet configured to receive a cutting insert.

[0024] The at least one fastening recess may be a blind hole and does not have to penetrate the entire thickness of each cutting arm so as to intersect both the rotation leading surface and the rotation trailing surface of each cutting arm.

[0025] The central axis of the through hole may intersect the longitudinal axis of the holder.

[0026] The tool holder may further include a holder centering hole that is recessed in the holder base surface and extends in the rearward direction along the longitudinal axis of the holder.

[0027] The tool holder may comprise exactly two drive members spaced apart in the circumferential direction.

[0028] The tool holder may have just two drive member through holes, each drive member through hole formed in a different drive member.

[0029] In a viewpoint along the receptacle axis, the rear contact surface of the receptacle may form a rear dovetail angle of the receptacle that is acute with respect to the radial holder plane oriented perpendicular to the longitudinal axis of the holder. The rear dovetail angle of the receptacle may be 10° or more and 30° or less.

[0030] The through-hole of the drive member may have a circumferential surface extending around the central axis of the through-hole. The circumferential surface of the through-hole may have internal threads.

[0031] The at least one fastening member may be a grub screw having a male thread that screws into the female thread.

[0032] The rotary cutting tool may comprise exactly two fastening members.

[0033] Refer to the attached drawings for a better understanding of this application and to show how it can actually be implemented. [Brief explanation of the drawing]

[0034] [Figure 1] This is a perspective view of a rotary cutting tool according to one embodiment of the present invention. [Figure 2] Figure 1 is an exploded perspective view of the front end of the rotary cutting tool. [Figure 3] Figures 1 and 2 are front views of the cutting head, showing two hidden fastening recesses. [Figure 4] Figure 3 is a main side view of the cutting head as seen along the arm axis, showing two hidden fastening recesses. [Figure 5] Figure 4 is a secondary side view showing the cutting head, which has been rotated 90° around the head's central axis. [Figure 6]This is another side view showing the cutting head shown in Figure 3, viewed along the central axis of the recess. [Figure 7] Figure 3 is a rear view of the cutting head. [Figure 8] Figures 1 and 2 show perspective views of the tool holder. [Figure 9] Figure 8 is a front view of the tool holder. [Figure 10] Figure 8 is a main side view of the front end of the tool holder. [Figure 11] Figure 10 shows a secondary side view of the front end, where the tool holder has been rotated 90° around the holder's central axis. [Figure 12] This is a cross-sectional view of the tool holder along line XII-XII in Figure 10. [Figure 13] This is a side view of the fastening member. [Figure 14] Figure 1 is a front view of the front end of the rotary tool holder. [Figure 15] Figure 14 is a main side view of the front end of the rotary tool holder shown. [Figure 16] Figure 14 is a cross-sectional view of a rotary cutting tool along line XVI-XVI. [Figure 17] Figure 15 is a cross-sectional view of a rotary cutting tool along line XVII-XVII.

[0035] For the sake of simplification and clarity, please note that the elements shown in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to others for clarity, or multiple physical components may be included in a single functional block or element. Furthermore, where deemed appropriate, reference numbers may be duplicated between figures to indicate corresponding or similar elements. [Modes for carrying out the invention]

[0036] The following description explains various aspects of the subject matter of this application. For the sake of clarity, specific configurations and details are described in sufficient detail to allow for a thorough understanding of the subject matter of this application. However, it will be apparent to those skilled in the art that the subject matter of this application can be implemented without the specific configurations and details presented herein.

[0037] First, we look at Figures 1 and 2, which show a rotary cutting tool 20 of a type used for drilling operations, according to an embodiment of the subject matter of the present application. The rotary cutting tool 20 has a cutting head 22, which may typically be made of cemented carbide. The rotary cutting tool 20 also has a tool holder 24 complementary to the cutting head 22, which may typically be made of steel. The rotary cutting tool 20 is adjustable at least between a detached position and a fastened position. In the fastened position of the rotary cutting tool 20, the cutting head 22 is detachably attached to the tool holder 24 by at least one fastening member 26.

[0038] Here, we refer to Figures 3 to 6, which show the cutting head 22 relating to the subject matter of this application. The cutting head 22 is formed from a single, integrated, one-piece (monolithic) structure. The cutting head 22 has a head central axis A, and the cutting head 22 is rotatable in a rotational direction R about this head central axis A, and the rotational direction R is the cutting direction. In one embodiment relating to the subject matter of this application, the head central axis A may be the longitudinal axis. The head central axis A is in the forward direction D F and rearward direction D RIt extends along the head. As best shown in Figures 4 to 6, the cutting head 22 includes a cutting portion 28. The cutting head 22 has a radial head plane HP oriented perpendicular to the head central axis A. In the drawings, the radial head plane HP is shown to be located on the rear surface 34 of the head. According to one embodiment of the subject matter of the present application, the cutting head 22 may also include a centering portion 30, in which case the cutting portion 28 is formed at the front end of the cutting head 22 and the centering portion 30 is formed at the rear end of the cutting head 22. The terms “front” and “rear” as used throughout this specification and the claims should be understood to refer to relative positions in the direction of the head central axis A, which is upward and downward, respectively, in Figures 4 to 6.

[0039] The cutting portion 28 includes opposing head front surfaces 32 and 34, and a head circumferential surface 36 extending between the head front surfaces 32 and 34. The head central axis A extends through the head front surfaces 32 and 34. The head rear surface 34 defines the boundary between the cutting portion 28 and the centering portion 30. Referring to Figures 4 and 7, according to a certain embodiment of the subject of the present application, the head rear surface 34 may include a head central rear surface 35, which is planar and oriented perpendicular to the head central axis A. The head central rear surface 35 may define (i.e., be encompassed within) the radial head plane HP.

[0040] The cutting portion 28 includes the head central axis 40. The cutting portion 28 includes two cutting arms 42 extending radially outward from the head radial central portion 40 with respect to the head longitudinal axis A. Each cutting arm 42 is fixed to its respective arm receiving receptacle 104 and connected to its respective drive member 84, as will be described later in this specification. Each cutting arm 42 extends radially outward along its arm axis AA. The cutting portion 28 may exhibit rotational symmetry about the head central axis A. Referring to Figure 3, the two cutting arms 42 define the head outer diameter OD. In this non-limiting example shown, the cutting portion 28 includes exactly two cutting arms 42 that are opposite each other with respect to the head central axis A. The arm axes AA intersect the head central axis A.

[0041] As best illustrated in Figure 3, each cutting arm 42 includes opposing arm rotation leading surface 44 and arm rotation trailing surface 46, and an arm circumferential surface 48 extending circumferentially between the arm rotation leading surface 44 and the arm rotation trailing surface 46. The arm rotation leading surface 44, the arm rotation trailing surface 46, and the arm circumferential surface 48 are all located on the head circumferential surface 36. The arm axis AA intersects the arm circumferential surface 48. Throughout this specification and the claims, when the terms “rotation leading” and “rotation trailing” are used, it should be understood that they refer to positions relative to the head rotation direction R. Thus, the arm rotation leading surface 44 is located forward in the rotation direction R than the arm rotation trailing surface 46. Each cutting arm 42 includes a driven surface 50 that engages with a complementary surface of the tool holder 24. The driven surface 50 is located on the arm rotation trailing surface 46. As shown in Figure 4, in this non-limiting example, each driven surface 50 may be a plane. Furthermore, each driven surface 50 may be parallel to the head's central axis A.

[0042] As shown in Figures 3 to 7, the cutting head 22 of this embodiment does not have an insert sheet configured to accommodate a cutting insert having a cutting edge.

[0043] Referring to Figure 4, each cutting arm 42 includes its own main cutting edge 54. The main cutting edge 54 is positioned forward, i.e., formed at the front end of the cutting head 22. The main cutting edge 54 is formed along at least a portion of the line of intersection between the arm rotation leading surface 44 and the head front surface 32. The head front surface 32 includes a plurality of main relief surfaces 56. Each main relief surface 56 extends from its respective main cutting edge 54 toward the opposite arm rotation trailing surface 46 of the same cutting arm 42. Each arm rotation leading surface 44 includes its respective main rake surface 58. Each main rake surface 58 extends from its respective main cutting edge 54 toward the head rear surface 34. As is known in the field of rotary cutting tools, each cutting arm 42 may include a cutting arm groove 59 for chip evacuation, associated with its respective main cutting edge 54.

[0044] As best shown in Figures 4 to 6, according to a subjective embodiment of the present application, the centering portion 30 may include a head centering pin 60 projecting rearward from the head rear surface 34 along the head central axis A. The purpose of the head centering pin 60 is to provide a centering means for the tool holder 24. The head centering pin 60 includes a pin rear surface 62 spaced apart from the head rear surface 34 and a pin circumferential surface 64 extending between the pin rear surface 62 and the head rear surface 34. The head centering pin 60 may project from a planar head central rear surface 35. The pin circumferential surface 64 may have a cylindrical shape. The pin circumferential surface 64 does not have to be provided with notches for fixing, for example, of the type disclosed in U.S. Patent No. 9,468,979. The head rear surface 34 may form the peripheral boundary of the pin circumferential surface 64 in the region where the head centering pin 60 projects from the head rear surface 34. The head centering pin 60 may be rotationally symmetrical with respect to the head central axis A.

[0045] At least one cutting arm 42 includes an arm rear contact surface 67 positioned on the head rear surface 34. As shown in Figure 4, the arm rear contact surface 67 is inclined forward in the direction away from the arm rotation trailing surface 46 and toward the arm rotation leading surface 44. In other words, the arm rear contact surface 67 has a dovetail joint shape. In a viewpoint along the arm axis AA (i.e., Figure 4), the arm rear contact surface 67 forms an arm rear dovetail angle β that is acute with respect to the radial head plane HP. According to a subjective embodiment of the present application, the arm rear dovetail angle β may satisfy the condition 10° ≤ β ≤ 30°. Preferably, the arm rear dovetail angle β may be 20°.

[0046] Referring again to Figure 4, according to one embodiment of the subject of the present application, the rear arm contact surface 67 may be flat. The rear arm contact surface 67 may be spaced apart from the arm rotation trailing surface 46 by the arm chamfer surface 68.

[0047] Referring particularly to Figures 3 and 4, the cut portion 28 includes at least one fastening recess 70 extending along the central axis C of the recess. The at least one fastening recess 70 is “hidden” and is therefore shown by a dashed line.

[0048] At least one fastening recess 70 opens at a recess opening 71. The recess opening 71 is at least partially located on the arm rotation trailing surface 46 of each cutting arm 42 associated with at least one fastening recess 70. That is, at least one fastening recess 70 is associated with each cutting arm 42. According to one embodiment of the subject of the present application, the cutting portion 28 may include just two fastening recesses 70, each associated with a different cutting arm 42. In Figure 3, the left “hidden” fastening recess 70 is associated with the left cutting arm 42, and vice versa.

[0049] Referring to Figures 5 and 6, according to one embodiment of the subject matter of the present application, the recessed opening 71 is partially located on the arm rotation following surface 46. The majority of the recessed opening 71 may be located on the arm rotation following surface 46. A small portion of the recessed opening 71 may be located on the arm rotation leading surface 44 of the cutting arm 42 that follows in the rotational direction. This is shown in Figures 3 and 5, where the recessed opening 71 extends across the longitudinal head plane LP, which encompasses the head longitudinal axis A and is oriented perpendicular to the arm axis AA.

[0050] At least one fastening recess 70 includes a recess circumferential surface 72 extending around the recess central axis C. Note that the recess opening 71 is defined by the intersection of the recess circumferential surface 72 with the arm rotation trailing surface 46 and optionally the arm rotation leading surface 44. According to one embodiment of the subject matter of the present application, the fastening recess 70 may include a recess bottom surface 74 whose boundary is defined by the recess circumferential surface 72 and which intersects the recess central axis C. The fastening recess 70 may be a blind hole, in which case it does not penetrate the entire thickness of the associated cutting arm 42 so as to intersect both the rotation leading surface 44 and the rotation trailing surface 46 of the associated cutting arm 42.

[0051] According to a particular embodiment of the subject matter of the present application, as shown in Figure 3 (i.e., a viewpoint along the head central axis A), the recess central axis C may be perpendicular to the head central axis A. The recess central axis C may intersect the head central axis A. Thus, in a configuration having just two fastening recesses 70, the two fastening recesses 70 are coaxial. Advantageously, each fastening recess 70 is oriented toward the radial central portion 40 of the head, thereby maintaining the rigidity of the two cutting arms 42.

[0052] As shown in Figure 3, from a viewpoint along the head central axis A, the recess central axis C forms an acute recess angle γ with respect to the arm axis AA. The acute recess angle γ may satisfy the condition 50° ≤ γ ≤ 70°. Preferably, the acute recess angle γ may be 60°. According to other embodiments of the subject matter of this application, the recess central axis C may be offset from the head central axis A (i.e., it may not intersect) (not shown).

[0053] Returning to Figure 5, the recessed circumferential surface 72 includes a recessed contact surface 76 oriented laterally with respect to the head central axis A, the recessed contact surface 76 facing away from the head rear surface 34. Generally, the recessed contact surface 76 extends along the recess central axis C. According to certain embodiments of the subject matter of the present application, the recessed contact surface 76 may be planar. The recessed contact surface 76 may be inclined forward within the associated cutting arm 42 in the direction away from the recessed opening 71 (for example, from the arm rotation trailing surface 46 toward the arm rotation leading surface 44). In a main side view along the arm axis AA (Figure 4), the recessed contact surface 76 may form a recessed contact angle θ with respect to the radial head plane HP. The forward-inclined recessed contact angle θ may satisfy the condition 15° ≤ θ ≤ 25°.

[0054] According to a subjective embodiment of the present application, for any fastening recess 70 and a cutting arm 42 associated with the fastening recess 70, the recess contact surface 76 may converge to the inclined arm rear contact surface 67 in the direction away from the arm rotation trailing surface 46 and toward the arm rotation leading surface 44. Therefore, the arm rear dovetail angle β is greater than the recess contact angle θ. From a viewpoint along the arm axis AA, the recess contact surface 76 and the inclined arm rear contact surface 67 form an acute arm engagement angle α. The arm engagement angle α may satisfy the condition 3° ≤ α ≤ 20°. Preferably, the arm engagement angle α may satisfy the condition 5° ≤ α ≤ 10°.

[0055] According to a subjective embodiment of the present invention, in a configuration having just two cutting arms 42, the cutting portion 28 may include just two opposing chip breaker blades 77 extending radially from the radial central portion 40 of the head. Each chip breaker blade 77 may be positioned between just the two cutting arms 42. Each chip breaker blade 77 extends in the forward direction D F It may extend to the front of the head 32. Each chip breaker blade 77 is in the rearward direction D R The chip breaker blades 77 do not necessarily have to extend to the rear surface 34 of the head. In other words, each chip breaker blade 77 may be spaced apart from the rear surface 34 of the head. Each chip breaker blade 77 may form part of the respective cutting arm groove 59. Advantageously, the chip breaker blades 77 reinforce the cutting portion 28 and improve chip flow and evacuation. Just two chip breaker blades 77 may define a blade width dimension WD measured perpendicular to the driven surface 50. The chip breaker blades 77 may be radially shorter than the cutting arm 42. In particular, the blade width dimension WD may be greater than half the head outer diameter OD. Alternatively, the blade width dimension WD may be less than three-quarters of the head outer diameter OD.

[0056] Another aspect of the subject matter of the present application includes a tool holder 24 for removably mounting a cutting head 22 to the tool holder 24.

[0057] Let us focus on Figures 8 to 12, which show the tool holder 24 relating to the subject matter of this application. The tool holder 24 is in the forward direction D F and rearward direction D RThe tool holder 24 has a holder longitudinal axis D extending along it, and the tool holder 24 is rotatable in the rotational direction R about this holder longitudinal axis D. The tool holder 24 includes a holder circumferential surface 78 extending circumferentially along the holder longitudinal axis D. The holder circumferential surface 78 forms the boundary of the holder base surface 80 facing forward at the front end of the tool holder 24. The tool holder 24 has a radial holder plane HP' oriented perpendicular to the holder longitudinal axis D. According to one embodiment of the subject matter of the present application, the holder base surface 80 may include a holder central base surface 81, which is planar and oriented perpendicular to the holder longitudinal axis D. The holder central base surface 81 may define (i.e., be included in) the radial holder plane HP'.

[0058] The tool holder 24 includes two circumferentially spaced holder grooves 82, which are recessed in the holder circumferential surface 78 and extend spirally around the holder longitudinal axis D.

[0059] The tool holder 24 includes two circumferentially spaced drive members 84 that extend forward from the holder base surface 80. The drive members 84 serve to apply cutting torque to the cutting head 22 as the tool holder 24 rotates. In the non-limiting illustrated example, the tool holder 24 includes two drive members 84 that face each other in opposite directions around the holder longitudinal axis D. Each drive member 84 includes an opposing drive member rotation leading surface 86 and drive member rotation trailing surface 88, and a drive member circumferential surface 90 that extends circumferentially between the drive member rotation leading surface 86 and drive member rotation trailing surface 88. The drive member rotation leading surface 86 is located forward of the drive member rotation trailing surface 88 in the rotation direction R.

[0060] The leading rotating surface 86 of the drive member includes a drive surface 92 for driving engagement with complementary driven surfaces 50 of the cutting head 22. According to one embodiment of the subject matter of the present application, the drive surface 92 may be positioned axially forward of the holder base surface 80. The drive surface 92 may be planar.

[0061] The tool holder 24 includes drive member through holes 93 formed in each drive member 84. The drive member through holes 93 extend along the central axis B of the through hole. According to one embodiment of the subject of the present application, the tool holder 24 may include just two drive member through holes 93, each drive member through hole 93 formed in a different drive member 84.

[0062] The drive member through-hole 93 opens to the drive member rotation direction leading surface 86 and the holder circumferential surface 78 (of the drive member through-hole 93 in which the drive member through-hole 93 is formed). The drive member through-hole 93 may include a through-hole circumferential surface 94 extending around the through-hole central axis B. According to a subjective embodiment of the present application, the through-hole circumferential surface 94 may include a female thread 95.

[0063] According to a particular embodiment of the subject matter of the present application, as shown in Figure 12 (i.e., in a view along the longitudinal axis D of the holder), the through-hole center axis B may intersect the longitudinal axis D of the holder. Thus, in a configuration having just two drive member through-holes 93, the two drive member through-holes 93 are coaxial. The through-hole center axis B forms an acute through-hole angle μ with respect to the receptacle axis RA. The acute through-hole angle μ may satisfy the condition 50° ≤ μ ≤ 70°. Preferably, the acute through-hole angle μ may be 60°.

[0064] Returning to Figure 9, the tool holder 24 includes a head support pocket 102 formed between two circumferentially spaced drive members 84. The head support pocket 102 includes two arm support receptacles 104. The two arm support receptacles 104 extend radially with respect to the holder's longitudinal axis D. Each arm support receptacle 104 merges into its respective holder groove 82 in the rotational direction R and is separated by its respective drive member 84 in the direction opposite to the rotational direction R. In this non-limiting example shown, the head support pocket 102 includes exactly two arm support receptacles 104 that face each other in opposite directions with respect to each other around the holder's longitudinal axis D, and therefore the head support pocket 102 is slotted (see Figure 10).

[0065] Each arm-receiving receptacle 104 includes a receptacle rear contact surface 108 positioned on the holder base surface 80. Referring to Figure 10, for any arm-receiving receptacle 104, a holder groove 82 associated with the arm-receiving receptacle 104, and a drive member 84 associated with the arm-receiving receptacle 104, the receptacle rear contact surface 108 is inclined forward toward the associated holder groove 82 away from the associated drive member 84. In a viewpoint along the receptacle axis RA (i.e., Figure 10), the receptacle rear contact surface 108 forms an acute receptacle rear dovetail angle δ with respect to the radial holder surface HP'. The receptacle rear dovetail angle θ may satisfy the condition 10° ≤ δ ≤ 30°. Preferably, the receptacle rear dovetail angle δ may be 20°. According to one embodiment of the subject matter of the present application, the rear contact surface 108 of the receptacle may be planar.

[0066] The tool holder 24 includes a holder centering hole 96 for receiving the head centering pin 60 of the cutting head 22. The holder centering hole 96 is recessed in the holder base surface 80 and extends rearward along the longitudinal axis D of the holder. R The holder centering hole 96 includes a rear hole surface 98 spaced apart from the holder base surface 80, and a circumferential hole surface 100 extending between the rear hole surface 98 and the holder base surface 80. According to one embodiment of the subject matter of the present application, the holder centering hole 96 may be recessed into the planar holder centering base surface 81. The circumferential hole surface 100 may have a cylindrical shape. The intersection line of the circumferential hole surface 100 and the holder base surface 80 may be chamfered to allow for easy initial insertion of the head centering pin 60 when assembling the rotary cutting tool 20.

[0067] Now, let us focus on Figure 13, which shows the fastening member 26. The fastening member 26 has a fastening biasing surface 110 that acts on the recessed contact surface 76. According to one embodiment of the subject of this application, the fastening member 26 may be a grub screw 26A having a male thread 112. The fastening biasing surface 110 may be conical in shape. Also, the fastening biasing surface 110 does not have a male thread.

[0068] Another aspect of the subject matter of this application relates to a rotary cutting tool 20 shown in Figures 14 to 17. In the removed position of the rotary cutting tool 20, the head centering pin 60 is not located in the holder centering hole 96. Also, the cutting head 22 is not detachably attached to the tool holder 24.

[0069] In the fastening position of the rotary cutting tool 20, the cutting head 22 is removably attached to the tool holder 24 by at least one fastening member 26. Preferably, the rotary cutting tool 20 may include just two fastening members 26. The head centering pin 60 is located in the holder centering hole 96. The head central axis A and the holder longitudinal axis D are coaxial. Each cutting arm 42 is in contact with its respective drive member 84. Specifically, each driven surface 50 abuts against its respective drive surface 92. At least one fastening member 26 is removably attached to the tool holder 24. At least one fastening member 26 is located in each drive member through hole 93 and abuts against its respective fastening recess 70. Specifically, the fastener biasing surface 110 abuts against its respective recess contact surface 76. Note that the recess bottom surface 74 is spaced apart from the fastening member 26. In a configuration where at least one fastening member 26 is a grab screw 26A, the male screw 112 may be screwed into each female screw 95.

[0070] The assembly of the rotary cutting tool 20 is achieved by performing the following procedure. The head centering pin 60 is positioned axially forward of the holder centering hole 96 and facing the holder centering hole 96. Note that in this position, each cutting arm 42 is positioned axially forward and circumferentially between each adjacent pair of drive members 84 (i.e., rotatably aligned with each arm receiving receptacle 104, as best shown in Figure 2). The cutting head 22 is then moved backward, so that the head centering pin 60 is first inserted into the holder centering hole 96. The cutting head 22 is then moved further backward until the head rear surface 34 first contacts the holder base surface 80. Note that the head center rear surface 35 is spaced apart from the holder center base surface 81. Also note that the cutting arms 42 and drive members 84 are designed to have sufficient spacing between each adjacent pair of drive members 84 to allow for the positioning of the cutting arms 42.

[0071] To adjust the cutting tool 20 to the fastening position, the cutting head 22 is rotated relative to the tool holder 24 in the opposite direction of rotation R until at least one of the driven surfaces 50 first contacts the respective drive surface 92. The first fastening member 26 is actuated (for example, tightened in the case of a screw) until it enters the first fastening recess 70 of the associated cutting arm 42 and contacts the recess fastening surface 76, thereby acting a fastening force F on the recess fastening surface 76 along a force line L directed generally backward. The force line L is perpendicular to the recess contact surface 76. Since the force line L has an axial (i.e., perpendicular) component, further tightening of the fastening member 26 biases the cutting arm 42 backward toward the holder base surface 80. The inclined arm rear contact surface 67 and the receptacle rear contact surface 108 slide relative to each other. The paired dovetail joint configurations of the arm rear contact surface 67 and the receptacle rear contact surface 108 bias each cutting arm 42 toward its respective drive member 84 until each driven surface 50 contacts its respective drive surface 92 (resulting in the cutting head 22 rotating relative to the tool holder 24), forming the fastening position of the rotary cutting tool 20. To improve fastening, the second fastening member 26 may be actuated and engage with the second fastening recess 70 after the first fastening member 26 has fully actuated, or alternately thereafter.

[0072] In a configuration where the central axis C of the recess intersects the central axis A of the head, it should be noted that the fastening member 26 does not exert a direct rotational force (specifically, a force in the opposite direction to the rotational direction R around the central axis A that biases the cutting arm 42 toward each drive member 84). Conversely, in a configuration where the central axis C of the recess is offset from the central axis A of the head, the fastening member 26 may exert such a rotational force, particularly in a configuration where the recess contact surface 76 converges with the rear arm contact surface 67 in a direction toward the leading arm rotation surface 44, away from the trailing arm rotation surface 46.

[0073] While the subject matter of this application has been described in some detail, it should be understood that various changes and modifications are possible without departing from the spirit or scope of the invention as claimed below.

Claims

1. Opposing forward direction (D Ｆ ) and rearward direction (D Ｒ A cutting head (22) having a head central axis (A) that defines the cutting head (22), wherein the cutting head (22) is rotatable in the rotational direction (R) about the head central axis (A), and the cutting head (22) is equipped with a cutting portion (28), The aforementioned cut portion (28) is Opposing head front surfaces (32) and head rear surfaces (34), and a head circumferential surface (36) extending between the head front surfaces (32) and head rear surfaces (34), Two cutting arms (42), each cutting arm (42) extends radially outward with respect to the head central axis (A) along the arm axis (AA), and Opposing arm rotation leading surface (44) and arm rotation trailing surface (46) arranged on the head circumferential surface (36), wherein the arm rotation leading surface (44) is located in front of the arm rotation trailing surface (46) in the rotation direction (R), A forward-positioned main cutting edge (54) is formed along at least a portion of the intersection line between the arm rotation leading surface (44) and the head front surface (32), The rear arm contact surface (67) is located on the rear surface (34) of the head, and is inclined forward in a direction toward the leading arm rotation surface (44) away from the trailing arm rotation surface (46), Two cutting arms (42) are provided, each having a driven surface (50) positioned on the arm rotation trailing surface (46), The device comprises at least one fastening recess (70) that opens into a recess opening (71) at least partially located on the arm rotation trailing surface (46) of each cutting arm (42) associated with the at least one fastening recess (70), The cutting head (22) comprises at least one fastening recess (70) having a recess circumferential surface (72) extending around the central axis (C) of the recess, the recess circumferential surface (72) having a recess contact surface (76) oriented laterally with respect to the central axis (A) of the head and facing away from the rear surface (34) of the head.

2. The cutting head (22) according to claim 1, wherein the central axis (C) of the recess intersects the central axis (A) of the head.

3. With respect to an arbitrary fastening recess (70) and a cutting arm (42) associated with the arbitrary fastening recess (70), the recess contact surface (76) converges to the arm rear contact surface (67) in a direction away from the arm rotation rear surface (46) toward the arm rotation leading surface (44), as described in claim 1 or 2.

4. Further comprising a centering portion (30), The rear surface of the head (34) defines the boundary between the cutting portion (28) and the centering portion (30), The cutting head (22) according to any one of claims 1 to 3, wherein the centering portion (30) includes a head centering pin (60) that protrudes rearward from the rear surface (34) of the head along the head central axis (A).

5. In a viewpoint along the arm axis (AA), the recessed contact surface (76) and the rear arm contact surface (67) form an acute arm engagement angle (α). The cutting head (22) according to any one of claims 1 to 4, wherein the arm engagement angle (α) satisfies the condition 5° ≤ α ≤ 10°.

6. In a viewpoint along the arm axis (AA), the rear contact surface (67) of the arm forms an acute rear dovetail joint angle (β) with respect to the radial head plane (HP) oriented perpendicular to the head central axis (A). The cutting head (22) according to any one of claims 1 to 5, wherein the rear dovetail joint angle (β) of the arm satisfies the condition of 10° ≤ β ≤ 30°.

7. The cutting head (22) according to any one of claims 1 to 6, wherein the recess contact surface (76) is inclined forward in a direction away from the recess opening (71).

8. In a viewpoint along the arm axis (AA), the recessed contact surface (76) forms a recessed contact angle (θ) with respect to the radial head plane (HP) oriented perpendicular to the head central axis (A). The cutting head (22) according to claim 7, wherein the contact angle (θ) of the recess satisfies the condition 15° ≤ θ ≤ 25°.

9. The cutting head (22) according to any one of claims 1 to 8, wherein the cutting portion (28) comprises exactly two cutting arms (42) that face each other in the exact opposite direction around the head central axis (A).

10. The cutting head (22) according to claim 10, wherein the cutting portion (28) comprises exactly two fastening recesses (70), each fastening recess (70) being associated with a different cutting arm (42).

11. The aforementioned cut portion (28) is The head has a radially central portion (40), The two cutting arms (42) mentioned above extend radially outward from the radially central portion (40) of the head, The cutting head (22) according to claim 10, wherein the cutting portion (28) comprises exactly two opposing chip breaker blades (77) extending radially outward from the radially central portion (40) of the head, and each chip breaker blade (77) is positioned between the exactly two cutting arms (42).

12. The two cutting arms (42) mentioned above define the head outer diameter (OD), The two chip breaker blades (77) define the blade width dimension (WD) measured in a direction perpendicular to the driven surface (50), The cutting head (22) according to claim 11, wherein the blade width dimension (WD) is greater than half of the head outer diameter (OD).

13. The cutting head (22) according to any one of claims 1 to 12, wherein the cutting portion (28) does not have an insert sheet configured to receive a cutting insert.

14. The cutting head (22) according to any one of claims 1 to 13, wherein the at least one fastening recess (70) is a blind hole and does not penetrate the entire thickness of each cutting arm (42) so as to intersect both the rotation leading surface (44) and the rotation trailing surface (46) of each cutting arm (42).

15. Opposing forward direction (D Ｆ ) and rearward direction (D Ｒ A tool holder (24) having a holder longitudinal axis (D) extending in the ) wherein the tool holder (24) is rotatable in the rotational direction (R) about the holder longitudinal axis (D), and the tool holder (24) is A holder circumferential surface (78) extends circumferentially along the longitudinal axis (D) of the holder and forms the boundary of the holder base surface (80) that faces forward at the front end of the tool holder (24), The holder circumferential surface (78) has two holder grooves (82) that are recessed and spirally extend around the longitudinal axis (D) of the holder, and are spaced apart in the circumferential direction. Two drive members (84) extending forward from the holder base surface (80) and spaced apart in the circumferential direction, wherein each drive member (84) is A driving member rotation leading surface (86) and a driving member rotation trailing surface (88), wherein the driving member rotation leading surface (86) is located in front of the driving member rotation trailing surface (88) in the rotation direction (R), and the driving member rotation leading surface (86) and the driving member rotation trailing surface (88), The drive surface (92) is positioned on the rotation leading surface (84) of the drive member, Two drive members (84) each having at least one drive member through hole (93) extending along the drive member through hole axis (B) and opening to the drive member rotation leading surface (86) and the holder circumferential surface (78), A head receiving pocket (102) formed between the two circumferentially spaced drive members (84), wherein the head receiving pocket (102) comprises two arm receiving receptacles (104), each arm receiving receptacle (104) extending radially outward with respect to the holder longitudinal axis (D) along the receptacle axis (RA), converging into the respective holder grooves (82) in the rotational direction (R), and being separated by the respective drive members (84) in the direction opposite to the rotational direction (R), the head receiving pocket (102) comprises Each arm receiving receptacle (104) is provided with a receptacle rear contact surface (108) located on the holder base surface (80), A tool holder (24) having an arbitrary arm receiving receptacle (104), a holder groove (82) associated with the arbitrary arm receiving receptacle (104), and a drive member (84) associated with the arbitrary arm receiving receptacle (104), wherein the rear contact surface (108) of the receptacle is inclined forward in a direction away from the associated drive member (84) and toward the associated holder groove (82).

16. The tool holder (24) according to claim 15, wherein the central axis (B) of the through hole intersects the longitudinal axis (D) of the holder.

17. The holder base surface (80) is recessed, and along the longitudinal axis (D) of the holder, the rearward direction (D Ｒ The tool holder (24) according to claim 15 or 16, further comprising a holder centering hole (96) extending in the ).

18. The tool holder (24) according to any one of claims 15 to 17, wherein the tool holder (24) comprises two drive members (84) spaced exactly apart in the circumferential direction.

19. The tool holder (24) according to claim 18, wherein the tool holder (24) comprises exactly two drive member through holes (93), and each drive member through hole (93) is formed on a different drive member (84).

20. In a viewpoint along the receptacle axis (RA), the rear contact surface (108) of the receptacle forms an acute rear dovetail angle (δ) with respect to the radial holder plane (HP') oriented perpendicular to the longitudinal axis (D) of the holder. The tool holder (24) according to any one of claims 15 to 19, wherein the rear dovetail joint angle (δ) of the receptacle satisfies the condition 10° ≤ δ ≤ 30°.

21. The drive member through hole (93) includes a through hole circumferential surface (94) that extends around the central axis (B) of the through hole. The tool holder (24) according to any one of claims 15 to 20, wherein the circumferential surface (94) of the through hole is provided with an internal thread (95).

22. A cutting head (22) according to any one of claims 1 to 14, Opposing forward direction (D Ｆ ) and rearward direction (D Ｒ A tool holder (24) having a holder longitudinal axis (D) extending in the ) and a tool holder (24) that is rotatable around the holder longitudinal axis (D), It comprises at least one fastening member (26), The rotary cutting tool (20) is adjustable between a removal position and a fastening position in which the cutting head (22) is detachably attached to the tool holder (24) by at least one fastening member (26).

23. A cutting head (22) according to any one of claims 1 to 14, The tool holder (24) described in claim 15, It comprises at least one fastening member (26), The rotary cutting tool (20) is adjustable between the removal position and the fastening position. At the aforementioned fastening position, The cutting head (22) is detachably attached to the tool holder (24) by at least one fastening member (26). The head centering pin (60) is positioned in the holder centering hole (96), Each cutting arm (42) is positioned on its respective arm receiving receptacle (104). Each driven surface (50) contacts its respective driving surface (92), Each arm's rear contact surface (67) contacts its respective receptacle contact surface (108). The at least one fastening member (26) is a rotary cutting tool (20) that engages with the recess contact surface (76) of the at least one fastening recess (26).

24. The drive member through hole (93) includes a through hole circumferential surface (94) that extends around the central axis (B) of the through hole. The circumferential surface (94) of the through hole is provided with an internal thread (95). The rotary cutting tool (20) according to claim 23, wherein the at least one fastening member (26) is a grab screw (26A) having a male thread (112) that is screwed into the female thread (95).

25. The cutting portion (28) has exactly two cutting arms (42) that face each other in the exact opposite direction around the head central axis (A), There are exactly two fastening recesses (70), and each fastening recess (70) is associated with a different cutting arm (42). The tool holder (24) comprises exactly two drive members (84) spaced apart in the circumferential direction. The tool holder (24) has exactly two drive member through holes (93), and each drive member through hole (93) is formed on a different drive member (84). The rotary cutting tool (20) according to claim 23 or 24, wherein the rotary cutting tool (20) comprises exactly two fastening members (26).

26. The cutting head (22) having a head center axis (A) that defines the opposing forward direction (D Ｆ ), and the rearward direction (D Ｒ ), wherein the cutting head (22) is rotatable in a rotational direction (R) about the head center axis (A), and the cutting head (22) includes a cutting portion (28). The cutting portion (28) does not have an insert sheet configured to receive a cutting insert, and Opposing head front end surfaces (32) and head rear end surfaces (34), and a head circumferential surface (36) extending between the head front end surface (32) and the head rear end surface (34), Two cutting arms (42), each cutting arm (42) extends radially outward with respect to the head central axis (A) along the arm axis (AA), and The arm rotation leading surface (44) and arm rotation trailing surface (46) are arranged on the head circumferential surface (36), wherein the arm rotation leading surface (44) is located in front of the arm rotation trailing surface (46) in the rotation direction (R), A forward-positioned main cutting blade (54) is formed along at least a portion of the intersection line between the arm rotation leading surface (44) and the head front surface (32), The rear contact surface (67) of the arm, which is located on the rear surface (34) of the head, Two cutting arms (42) are provided, each having a driven surface (50) positioned on the arm rotation trailing surface (46), The device comprises at least one fastening recess (70) that opens into a recess opening (71) at least partially located on the arm rotation trailing surface (46) of each cutting arm (42) associated with the at least one fastening recess (70), The at least one fastening recess (70) comprises a recess circumferential surface (72) extending around the recess central axis (C), and the recess circumferential surface (72) comprises a recess contact surface (76) oriented laterally with respect to the head central axis (A) and facing away from the head rear surface (34). The cutting head (22) wherein the at least one fastening recess (70) is a blind hole and does not penetrate the entire thickness of each cutting arm (42) so as to intersect both the rotation leading surface (44) and the rotation trailing surface (46) of each cutting arm (42).

Images