A cutting head and rotary cutting tool having two pairs of cutting arms with unequal cutting diameters.
The cutting head design with unequal diameter cutting arms and detachable tool shanks effectively distributes forces and reduces manufacturing costs by using interchangeable components.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- ISCAR LTD
- Filing Date
- 2024-04-25
- Publication Date
- 2026-06-11
AI Technical Summary
Existing rotary cutting tools with two pairs of cutting arms do not effectively distribute large cutting and impact forces generated toward the center of the cutting head, and the cutting heads are not efficiently detachable or economically manufactured.
A cutting head design with two pairs of cutting arms, where one pair has a larger diameter than the other, sharing cutting and impact forces evenly, and a detachable configuration with a tool shank made of different materials for efficient manufacturing.
The design evenly distributes cutting and impact forces, extends the operating life of the cutting edges, and allows for economical manufacturing by using interchangeable cutting heads and tool shanks.
Smart Images
Figure 2026518979000001_ABST
Abstract
Description
Technical Field
[0001]
[0001] The present invention relates to a cutting head having two pairs of cutting arms and a rotary cutting tool having such a cutting head, which are used for drilling operations, particularly metal cutting drilling operations.
Background Art
[0002]
[0002] In the field of rotary cutting tools used for drilling operations, there are several examples of cutting heads having two pairs of cutting arms.
[0003]
[0003] US Patent Application Publication No. 2008 / 110679 discloses a one-piece drilling head fixed to the end of a drill's spiral shaft by a material locking method. The drilling head is formed of a hard material and includes four legs extending radially in a cross shape, and the four legs respectively form two main cutting edges and two auxiliary cutting edges that are radially opposed. The main cutting edge and the auxiliary cutting edge extend monotonously and precisely axially from the tip of the drilling head to the radial outer edge.
[0004]
[0004] US Patent Application Publication No. 2008 / 118317 discloses a one-piece drilling head that can be fixed to the axial end of a drill's spiral shaft by a material locking method. The drilling head is formed of a hard material and includes four legs extending radially in a cross shape, and the four legs respectively form each cutting edge, and a tangential reinforcement is provided at the axial region of the cutting edge on the radial outer rim of each leg.
[0005]
[0005] U.S. Patent Application Publication No. 2021 / 205900 discloses a drill, particularly a spiral drill, having a base body substantially longitudinally extending in the axial direction of the drill axis, the base body comprising a drilling portion, the drilling portion having a radially inward core region and a radially outward region with respect to the drill axis, the drilling portion comprising a plurality of helical recesses in the outer region, with a wall between each of the two helical recesses, and it is proposed that the drill comprises at least four primary cutting edges, particularly exactly four primary cutting edges.
[0006]
[0006] An object of the present invention is to provide an improved cutting head having two pairs of cutting arms.
[0007]
[0007] Another object of the present invention is to provide an improved cutting head in which the large cutting and impact forces generated toward the center of the cutting head are shared by two pairs of "radially inward" cutting edges associated with two pairs of cutting arms.
[0008]
[0008] A further object of the present invention is to provide an improved rotary cutting tool in which the cutting head is detachably fixed to the tool shank.
[0009]
[0009] A further object of the present invention is to provide an improved rotary cutting tool in which the tool shank is manufactured efficiently and economically. [Overview of the Initiative]
[0010]
[0010] According to the present invention, a cutting head is provided that is rotatable in the rotational direction about a head axis, the head axis is defined as having a direction forward of the head and a direction backward of the head opposite to the direction forward of the head, and the cutting head is: A cutting portion having a cutting tip having the foremost tip point in the axial direction that is included in the head axis, wherein a pair of first cutting arms are arranged alternately in the circumferential direction with a pair of second cutting arms, Each first cutting arm has a first cutting edge extending radially outward from the cutting tip and a first headland surface facing radially outward. The first cutting edge extends from the cutting tip to the two outermost first cutting points in the radial direction, and the two first cutting points define a virtual first circle having a first diameter and a center coinciding with the head axis in a plan view of the cutting head, and each first cutting edge includes a first radially outer cutting edge portion and a first radially inner cutting edge portion, and the virtual first circle is located in a first plane perpendicular to the head axis. Each first headland surface has a head leading edge that extends axially rearward from its associated radially outermost first cutting point, Each second cutting arm has a second cutting edge extending radially outward from the cutting tip and a second headland surface facing radially outward. The second cutting edge extends to the two outermost second cutting points in the radial direction, and the two second cutting points define a virtual second circle having a second diameter and a center coinciding with the head axis in a plan view of the cutting head, and the virtual second circle is located in a second plane perpendicular to the head axis. The first diameter is larger than the second diameter. In a cross-section along a fifth plane that encompasses the head axis and intersects the first cutting arm, each first cutting edge has a first cutting profile, and each first radially inner cutting edge portion has a first inner cutting profile. In a cross-section along a sixth plane that encompasses the head axis and intersects the second cutting arm, each second cutting edge has a second cutting profile. The first internal cutting profile is identical to the second cutting profile.
[0011]
[0011] Furthermore, according to the present invention, a rotary cutting tool is provided, the rotary cutting tool is: A long tool shank having a shank axis that establishes a shank forward direction and a shank rearward direction opposite to the shank forward direction, The tool comprises the cutting head described above, which is positioned at the front end of the tool shank, The shank circumferential surface extends along the shank axis away from the front end of the tool shank. The shank circumferential surface has exactly two shank land surfaces and exactly two shank grooves arranged alternately.
[0012]
[0012] For a better understanding of the present invention, the present invention will be illustratively described with reference to the attached drawings in which the dashed line represents the cutting boundary of the partial view of the member.
Brief Description of the Drawings
[0013] [Figure 1]
[0013] It is a perspective view of a cutting head according to an embodiment of the present invention. [Figure 2]
[0014] It is a bottom view of the cutting head shown in FIG. 1. [Figure 3]
[0015] It is a side view of the cutting head shown in FIG. 1. [Figure 4]
[0016] It is a plan view of the cutting head shown in FIG. 1. [Figure 5]
[0017] It is a cross-sectional view taken along the line V-V of the cutting head shown in FIG. 4. [Figure 6]
[0018] It is a cross-sectional view taken along the line VI-VI of the cutting head shown in FIG. 4. [Figure 7]
[0019] It is a cross-sectional view taken along the line VII-VII of the cutting head shown in FIG. 4. [Figure 8]
[0020] It is a cross-sectional view taken along the line VIII-VIII of the cutting head shown in FIG. 4. [Figure 9]
[0021] It is a cross-sectional view taken along the line IX-IX of the cutting head shown in FIG. 3. [Figure 10]
[0022] It is an exploded perspective view of a rotary cutting tool according to an embodiment of the present invention. [Figure 11]
[0023] It is an end view of the assembled position of the rotary cutting tool shown in FIG. 10. [Figure 12]
[0024] It is a side view of the assembled position of the rotary cutting tool shown in FIG. 10. [Figure 13]
[0025] It is an end view of a tool shank according to an embodiment of the present invention. [Figure 14]
[0026] It is a side view of the tool shank shown in FIG. 13. [Embodiment for Carrying Out the Invention]
[0014]
[0027] First, referring to FIGS. 1 to 4 showing the cutting head 20 rotatable in the rotational direction RD around the head axis AH, the head axis AH establishes the head forward direction HF and the head rearward direction HR opposite to the head forward direction HF.
[0015]
[0028] In an embodiment of the present invention, the cutting head 20 can be manufactured by molding and sintering a cemented carbide such as tungsten carbide, and may or may not be coated.
[0016]
[0029] As shown in FIGS. 1 to 4, the cutting head 20 includes a cutting tip 24 having a front end point NT at the foremost axial position included in the insert axis AH, and a cutting portion 22 having a pair of first cutting arms 26 and a pair of second cutting arms 28 alternately arranged in the circumferential direction.
[0017]
[0030] In an embodiment of the present invention, the cutting portion 22 may have a bottom surface 30 facing rearward.
[0018]
[0031] As shown in FIGS. 1 to 4, each first cutting arm 26 has a first cutting edge 32 extending radially outward from the cutting tip 24 and a first head land surface 34 facing radially outward.
[0019]
[0032] In an embodiment of the present invention, the pair of first cutting arms 26 may be the same.
[0020]
[0033] Furthermore, in one embodiment of the present invention, each first headland surface 34 may intersect the bottom surface 30.
[0021]
[0034] Furthermore, in one embodiment of the present invention, each first headland surface 34 may be curved in a convex shape.
[0022]
[0035] As shown in Figures 1 to 4, each first cutting edge 32 includes a first radially outer cutting edge portion 36 and a first radially inner cutting edge portion 38.
[0023]
[0036] In one embodiment of the present invention, a pair of first cutting edges 32 may exhibit twofold rotational symmetry about the head axis AH.
[0024]
[0037] Each second cutting arm 28 has a second cutting edge 40 extending radially outward from the cutting tip 24, and a second headland surface 42 facing radially outward.
[0025]
[0038] In one embodiment of the present invention, the pair of second cutting arms 28 may be identical.
[0026]
[0039] Furthermore, in one embodiment of the present invention, a pair of second cutting edges 40 may exhibit twofold rotational symmetry about the head axis AH.
[0027]
[0040] As shown in Figure 3, each second headland surface 42 may intersect the bottom surface 30.
[0028]
[0041] In one embodiment of the present invention, each second headland surface 42 may be curved in a convex shape.
[0029]
[0042] As shown in Figures 1 to 4, a pair of first cutting edges 32 extend from the cutting tip 24 to the two outermost first cutting points NRO1 in the radial direction, and these two outermost first cutting points NRO1 define a virtual first circle C1 having a first diameter D1 and a center that coincides with the head axis AH. A pair of second cutting edges 40 extend to the two outermost second cutting points NRO2 in the radial direction, and these two outermost second cutting points NRO2 define a virtual second circle C2 having a second diameter D2 and a center that coincides with the head axis AH.
[0030]
[0043] In one embodiment of the present invention, both a pair of first cutting edges 32 and a pair of second cutting edges 40 extend radially outward from the tip point NT. In such embodiments of the present invention, each first radially inward cutting edge portion 38 and each second cutting edge 40 may include a chisel edge portion 44 extending from the tip point NT.
[0031]
[0044] In this embodiment of the present invention, in which the cutting head 20 has four chisel edge portions 44 extending from the tip point NT, it should be understood that the cutting tip 24 has a robust "pyramid" shape.
[0032]
[0045] As shown in Figure 4, the first diameter D1 is larger than the second diameter D2.
[0033]
[0046] In one embodiment of the present invention, the second diameter D2 may be greater than 30% of the first diameter D1 and less than 70% of the first diameter D1, i.e., D1 × 0.30 <D2<D1×0.70であってもよい。
[0034]
[0047] It should be understood that by configuring the cutting head 20 to have two pairs of "radially inward" cutting edges, i.e., one pair of first radially inward cutting edge portions 38 and one pair of second cutting edges 40, the feed rate of each "radially inward" cutting edge becomes half the feed rate of each first radially outward cutting edge portion 36, and therefore, the large cutting and impact forces that are usually associated with very low cutting speeds generated toward the center of the cutting head are favorably shared by the two pairs of "radially inward" cutting edges.
[0035]
[0048] As shown in Figure 4, in a plan view of the cutting head 20, the virtual first circle C1 defines a virtual first cylinder S1 that extends along the head axis AH.
[0036]
[0049] In one embodiment of the present invention, no portion of the cutting head 20 has to extend outside the virtual first cylinder S1.
[0037]
[0050] Furthermore, it should be understood that in one embodiment of the present invention, the first diameter D1 of the virtual first circle may define the cutting diameter DC of the cutting head 20.
[0038]
[0051] As shown in Figure 4, the virtual second cylinder S2 has a circular cross-section centered on the head axis AH, and the virtual second cylinder S2 has a second cylinder diameter DS2 that is larger than the second diameter D2 and smaller than the first diameter D1, i.e., D2 <DS2<D1である。
[0039]
[0052] In one embodiment of the present invention, a pair of second cutting arms 28 may be positioned entirely inside a virtual second cylinder S2, and the virtual second cylindrical surface 46 of the virtual second cylinder S2 may intersect the pair of first cutting arms 26.
[0040]
[0053] In one embodiment of the present invention, the virtual second cylindrical surface 46 may intersect a pair of first radially outer cutting edge portions 36.
[0041]
[0054] Furthermore, in one embodiment of the present invention, the cutting head 20 may exhibit twofold rotational symmetry about the head axis AH.
[0042]
[0055] As shown in Figure 3, the first virtual circle C1 is located on the first plane P1 perpendicular to the head axis AH, and the second virtual circle C2 is located on the second plane P2 perpendicular to the head axis AH.
[0043]
[0056] In one embodiment of the present invention, the first plane P1 and the second plane P2 do not have to lie on the same plane.
[0044]
[0057] Furthermore, in one embodiment of the present invention, the first plane P1 may be positioned axially behind the second plane P2.
[0045]
[0058] Furthermore, in one embodiment of the present invention, each first cutting edge 32 may extend monotonically backward in the axial direction from the cutting tip 24 to the radially outermost first cutting point NRO1.
[0046]
[0059] Furthermore, in one embodiment of the present invention, each second cutting edge 40 may extend monotonically backward in the axial direction from the cutting tip 24 to its radially outermost second cutting edge NRO2.
[0047]
[0060] As shown in Figure 3, each first headland surface 34 may have a head leading edge 48 that extends axially rearward from the radially outermost first cutting point NRO1 to the axially rearmost head leading endpoint NHR1.
[0048]
[0061] Furthermore, as shown in Figure 3, the bottom surface 30 may define a third plane P3 perpendicular to the head axis AH.
[0049]
[0062] In one embodiment of the present invention, the bottom surface 30 may be flat.
[0050]
[0063] Furthermore, in one embodiment of the present invention, each head leading endpoint NHR1 may be located on or immediately adjacent to the third plane P3.
[0051]
[0064] As shown in Figure 2, the two head leading endpoints NHR1 may be located on a fourth plane P4 that encompasses the head axis AH.
[0052]
[0065] As shown in Figure 5, in a cross-section along a fifth plane P5 that encompasses the head axis AH and intersects a pair of first cutting arms 26, each first cutting edge 32 has a first cutting profile PC1, and the first radially inner cutting edge portion 38 of each first cutting edge 32 has a first inner cutting profile PCI1.
[0053]
[0066] As shown in Figure 6, in a cross-section along a sixth plane P6 that encompasses the head axis AH and intersects a pair of second cutting arms 28, each second cutting edge 40 has a second cutting profile PC2. The sixth plane P6 may be perpendicular to the fifth plane P5.
[0054]
[0067] Throughout this specification and the claims, the term “cutting profile” should be understood to mean the rotational projection of the cutting edge or cutting edge portion centered on the head axis AH onto any plane encompassing the head axis AH, i.e., any radial plane.
[0055]
[0068] As shown in Figures 5 and 6, the first inner cutting profile PCI1 is identical to the second cutting profile PC2.
[0056]
[0069] It should be understood that the first internal cutting profile PCI1 and the second cutting profile PC2 may coincide when rotated and projected onto the same radial plane, for example, when rotated and projected onto the fifth plane P5 or the sixth plane P6.
[0057]
[0070] It should be understood that by configuring the first inner cutting profile PCI1 to be identical to the second cutting profile PC2, the large cutting and impact forces that occur toward the center of the cutting head, which are usually associated with very low cutting speeds, are advantageously and evenly distributed between the pair of first radially inner cutting edge portions 38 and the pair of second cutting edges 40.
[0058]
[0071] The first cutting profile PC1 has a first cross-sectional profile width W1 equal to D1, while both the first inner cutting profile PCI1 and the second cutting profile PC2 have a second cross-sectional profile width W2 equal to D2. Thus, in one embodiment, W1 × 0.30 < W2 < W1 × 0.70. Here, it should be understood that the cross-sectional profile width is measured in a direction perpendicular to the head axis AH.
[0059]
[0072] In one embodiment of the present invention, the cutting head 20 may preferably be used for metal cutting and piercing operations.
[0060]
[0073] Also, in one embodiment of the present invention, each first radially inner cutting edge portion 38 may be identical to each second cutting edge 40.
[0061]
[0074] Furthermore, in one embodiment of the present invention, the pair of first radially inner cutting edge portions 38 and the pair of second cutting edges 40 may exhibit four-fold rotational symmetry about the head axis AH.
[0062]
[0075] As shown in FIG. 1, each first radially inner cutting edge portion 38 is formed at the intersection of a first inner rake face 50 facing the rotational direction RD and a first inner relief face 52 facing axially forward.
[0063]
[0076] In one embodiment of the present invention, each first inner rake face 50 may be formed on a first point thinning gash 54.
[0064]
[0077] As shown in FIG. 1, each second cutting edge 40 is formed at the intersection of a second rake face 56 facing the rotational direction RD and a second relief face 58 facing axially forward.
[0065]
[0078] In one embodiment of the present invention, each second rake face 56 may be formed on a second point thinning gash 60.
[0066]
[0079] Furthermore, in one embodiment of the present invention, each second headland surface 42 may be intersected by one of the first point thinning gashs 54 and one of the second point thinning gashs 60.
[0067]
[0080] As shown in Figure 1, each second cutting arm 28 has a second front surface 62 that faces forward in the axial direction.
[0068]
[0081] In one embodiment of the present invention, each second front surface 62 may be intersected by an adjacent, rotationally trailing first point thinning gash 54.
[0069]
[0082] Furthermore, in one embodiment of the present invention, each second relief surface 58 may be positioned on one of the second front surfaces 62.
[0070]
[0083] Furthermore, in one embodiment of the present invention, each second front surface 62 may intersect with its associated second headland surface 42.
[0071]
[0084] As shown in Figure 1, each first cutting arm 26 has a first front surface 64 that faces forward in the axial direction.
[0072]
[0085] In one embodiment of the present invention, each first front surface 64 may be intersected by an adjacent, rotationally trailing second point thinning gash 60.
[0073]
[0086] Furthermore, in one embodiment of the present invention, each first inner relief surface 52 may be positioned on one of the first front surfaces 64.
[0074]
[0087] Furthermore, in one embodiment of the present invention, each first front surface 64 may intersect with its associated first headland surface 34.
[0075]
[0088] As shown in Figure 1, each first radially outer cutting edge portion 36 is formed at the intersection of a first outer rake face 66 facing the rotational direction RD and a first outer relief face 68 facing forward in the axial direction.
[0076]
[0089] In one embodiment of the present invention, each first outer relief surface 68 may be positioned on one of the first front surfaces 64.
[0077]
[0090] As shown in Figure 1, the first outer rake face 66 may be formed on a chip discharge groove 70 that extends axially rearward.
[0078]
[0091] During cutting, it should be understood that the cutting chips generated by each first radially outer cutting edge portion 36 flow axially backward along the associated chip discharge groove 70.
[0079]
[0092] In one embodiment of the present invention, each chip discharge groove 70 may intersect the bottom surface 30.
[0080]
[0093] Furthermore, in one embodiment of the present invention, the virtual second cylindrical surface 46 may intersect with two chip discharge grooves 70.
[0081]
[0094] During cutting, the cutting chips generated by each first radially inner cutting edge 38 flow axially backward along the associated first point thinning gash 54, and then continue to flow axially backward along the associated chip discharge groove 70.
[0082]
[0095] In embodiments of the present invention where the first diameter D1 is greater than the second diameter D2, it should be understood that sufficient space is provided beyond the radially outer range of each second cutting arm 28, allowing the cutting chips generated by the associated second cutting edge 40 to flow in the opposite direction of rotation RD after exiting the associated second point thinning gash 60, and then to continue flowing axially backward along the chip discharge groove 70 that follows in the direction of rotation.
[0083]
[0096] As shown in Figure 4, the virtual third cylinder S3 has a circular cross-section centered on the head axis AH. The virtual third cylinder S3 intersects a pair of first radially inner cutting edge portions 38 at two first intersections N1, and intersects a pair of second cutting edges 40 at two second intersections N2.
[0084]
[0097] As shown in Figure 7, in a cross-section along the seventh plane P7 that is tangent to the virtual third cylinder S3 and encompasses one of the first intersection points N1, the first inner rake face 50 is located on the virtual third cylinder S3 and forms a first inner rake angle α1 that is acute with respect to the first virtual vertical line LV1 which is parallel to the head axis AH.
[0085]
[0098] As shown in Figure 8, in a cross-section along the eighth plane P8 that is tangent to the virtual third cylinder S3 and encompasses one of the second intersection points N2, the second rake face 56 is located on the virtual third cylinder S3 and forms a second rake angle α2 that is acute with respect to the second virtual vertical line LV2 which is parallel to the head axis AH.
[0086]
[0099] In one embodiment of the present invention, the first internal rake angle α1 and the second rake angle α2 may be equal.
[0087] [000100] In addition, in one embodiment of the present invention, the first inside rake angle α1 and the second rake angle α2 may be negative.
[0088] [000101] Throughout this specification and the claims, it should be understood that the first inner rake angle α1 is negative in a configuration in which the first inner rake face 50 extends forward in the rotational direction as it extends away from its associated first radially inner cutting edge portion 38.
[0089] [000102] It should also be understood throughout this specification and the claims that the second rake angle α2 is negative in configurations in which the second rake face 56 extends forward in the rotational direction as it extends away from its associated second cutting edge 40.
[0090] [000103] The two pairs of "radially inward" cutting edges, that is, the pair of first radially inward cutting edge portions 38 and the pair of second cutting edges 40, are more susceptible to impact forces than the pair of first radially outward cutting edge portions 36 due to their relatively low cutting speed, especially at high feed rates. Therefore, by configuring the first inner rake angle α1 and the second rake angle α2 to be negative, the stability and robustness of the two pairs of "radially inward" cutting edges are improved, thereby extending their operating life.
[0091] [000104] Furthermore, in one embodiment of the present invention, the first internal rake angle α1 and the second rake angle α2 may have values between 3 and 15 degrees, i.e., 3° < α1 < 15° and 3° < α2 < 15°.
[0092] [000105] As shown in Figure 7, in a cross section along the seventh plane P7, the first inner relief surface 52 encompasses one of the first intersections N1 and forms an acute first inner relief angle β1 with respect to the first virtual horizontal line LH1 which is perpendicular to the first virtual vertical line LV1.
[0093] [000106] Throughout this specification and the claims, it should be understood that in a cross section along the seventh plane P7, the first inner relief surface 52 extends axially rearward as it extends away from the first radially inner cutting edge portion 38.
[0094] [000107] As shown in Figure 8, in a cross section along the eighth plane P8, the second relief surface 58 encompasses one of the second intersections N2 as described above and forms a second relief angle β2 that is acute with respect to the second virtual horizontal line LH2 which is perpendicular to the second virtual vertical line LV2.
[0095] [000108] Throughout this specification and the claims, it should be understood that in a cross section along the eighth plane P8, the second relief surface 58 extends axially rearward as it extends away from the second cutting edge 40.
[0096] [000109] In one embodiment of the present invention, the first inner relief angle β1 and the second relief angle β2 may be equal.
[0097] [000110] Furthermore, in one embodiment of the present invention, the first inner relief angle β1 and the second relief angle β2 may have values between 5 and 20 degrees, that is, 5° < β1 < 20° and 5° < β2 < 20°.
[0098] [000111] As shown in Figure 9, in a cross-section along a ninth plane P9 that is perpendicular to the head axis AH and intersects a pair of first radially inner cutting edge portions 38 and a pair of second cutting edges 40, the virtual third circle C3 is inscribed in two first point thinning gouache 54, and the virtual fourth circle C4 is inscribed in two second point thinning gouache 60.
[0099] [000112] In one embodiment of the present invention, the virtual third circle C3 and the virtual fourth circle C4 may each have centers that coincide with the head axis AH.
[0100] [000113] In one embodiment of the present invention, the virtual third circle C3 and the fourth circle C4 may coincide.
[0101] [000114] Furthermore, in one embodiment of the present invention, as shown in Figure 3, the ninth plane P9 may encompass two first intersections N1 and two second intersections N2.
[0102] [000115] As shown in Figure 3, each first point thinning gash 54 has a first gash path GP1 that extends away from the cutting tip 24, and the first gash path GP1 is defined by a plurality of radially innermost gash points (not shown) obtained from a series of cross-sections along a plane perpendicular to the head axis AH and intersecting the first point thinning gash 54 along its axial range.
[0103] [000116] In one embodiment of the present invention, each first gash path GP1 may extend monotonically radially outward from the cutting tip 24 to the first gash endpoint NG1 at the rearmost point in the axial direction.
[0104] [000117] In one embodiment of the present invention, the virtual third circle C3 may be inscribed in two first point thinning gashes 54 at a point along each of their respective first gash paths GP1.
[0105] [000118] As shown in Figure 3, each second point thinning gash 60 has a second gash path GP2 that extends away from the cutting tip 24, and the second gash path GP2 is defined by a plurality of radially innermost gash points (not shown) obtained from a series of cross-sections along a plane perpendicular to the head axis AH and intersecting the second point thinning gash 60 along its axial range.
[0106] [000119] In one embodiment of the present invention, each second gash path GP2 may extend monotonically radially outward from the cutting tip 24 to the axially rearmost second gash endpoint NG2.
[0107] [000120] In one embodiment of the present invention, the virtual fourth circle C4 may be inscribed in two second point thinning gashes 60 at a point along each of their respective second gash paths GP2.
[0108] [000121] As shown in Figures 1 and 3, each first cutting arm 26 may include a torque transmission surface 72 facing away from the rotational direction RD.
[0109] [000122] In one embodiment of the present invention, each torque transmission surface 72 may intersect with its associated first headland surface 34.
[0110] [000123] In addition, in one embodiment of the present invention, each torque transmission surface 72 may be a flat surface.
[0111] [000124] Furthermore, in one embodiment of the present invention, the virtual second cylindrical surface 46 may intersect with two torque transmission surfaces 72.
[0112] [000125] As shown in Figures 2 and 3, the cutting head 20 may have a mounting portion 74 located behind the cutting portion 22 in the axial direction.
[0113] [000126] In one embodiment of the present invention, the mounting portion 74 may have a central mounting stem 76 that extends axially rearward from the bottom surface 30 of the cutting portion along the head axis AH.
[0114] [000127] In one embodiment of the present invention, the central mounting stem 76 may also have a circumferentially outer stem surface 78.
[0115] [000128] Now, focusing on Figures 10 to 12 which show the rotary cutting tool 80, the rotary cutting tool 80 has a long tool shank 82 having a shank axis AS, the shank axis AS defines the shank forward direction SF and the shank rearward direction SR opposite to the shank forward direction SF, and the cutting head 20 is positioned at the front end 84 of the tool shank 82.
[0116] [000129] In one embodiment of the present invention, the cutting head 20 may be detachably fixed to the front end 84 of the tool shank 82.
[0117] [000130] By configuring the cutting head 20 to be removably fixed to the tool shank 82, the cutting head 20 can be manufactured from a material of appropriate hardness, such as tungsten carbide, and the tool shank 82 can be manufactured from a low-hardness and inexpensive material, such as high-speed steel. The tool shank 82 can be reused after the worn or damaged cutting head 20 is discarded.
[0118] [000131] In other embodiments of the present invention (not shown), the cutting head 20 and the tool shank 82 may be a single, integrated component with a one-piece structure.
[0119] [000132] As shown in Figures 13 and 14, the shank circumferential surface 86 extends away from the front end 84 of the tool shank 82 along the shank axis AS.
[0120] [000133] Also, as shown in Figures 13 and 14, the shank circumferential surface 86 may have just two shank land surfaces 90 and just two shank grooves 88 that are alternately arranged in the circumferential direction.
[0121] [000134] In one embodiment of the present invention, the two shank grooves 88 may extend spirally along the shank axis AS.
[0122] [000135] In one embodiment of the present invention, the tool shank 82 may exhibit twofold rotational symmetry about the shank axis AS.
[0123] [000136] As shown in Figure 14, the front end 84 of the tool shank 82 may have a support surface 92 facing forward.
[0124] [000137] In one embodiment of the present invention, the support surface 92 facing forward may define a tenth plane P10 perpendicular to the shank axis AS.
[0125] [000138] In one embodiment of the present invention, the support surface 92 facing forward may be a flat surface.
[0126] [000139] As shown in Figure 12, in the assembly position of the cutting tool 80, the head axis AH and the shank axis AS may coincide, and the bottom surface 30 of the cutting head may face the support surface 92 of the tool shank.
[0127] [000140] In one embodiment of the present invention, the bottom surface 30 of the cutting head may be in contact with the support surface 92 of the tool shank.
[0128] [000141] In one embodiment of the present invention, the third plane P3 and the tenth plane P10 may lie on the same plane.
[0129] [000142] As shown in Figure 14, each shank land surface 90 has a shank leading edge 94 that extends axially backward from the shank leading endpoint NSF1, which is the shank leading edge point furthest forward in the axial direction.
[0130] [000143] In one embodiment of the present invention, each shank leading endpoint NSF1 may be located on or immediately adjacent to the 10th plane P10.
[0131] [000144] In one embodiment of the present invention, the two leading shank endpoints NSF1 may be located on an 11th plane P11 that encompasses the shank axis AS.
[0132] [000145] As shown in Figure 11, at the assembly position of the cutting tool 80, the fourth plane P4 and the eleventh plane P11 may form a first rotational offset angle φ1 of less than 15 degrees, that is, φ1 < 15°.
[0133] [000146] In one embodiment of the present invention, the first rotational offset angle φ1 may preferably be less than 5 degrees, i.e., φ1 < 5°, and each head leading endpoint NHR1 may be positioned rotationally forward of its adjacent shank leading endpoint NSF1.
[0134] [000147] In this embodiment of the present invention, it should be understood that the two chip discharge grooves 70 are aligned in the rotational direction with the two shank grooves 88, thereby ensuring a smooth and uninterrupted flow of cutting chips from the cutting head 20 to the rear in the axial direction.
[0135] [000148] Furthermore, in these embodiments of the present invention, it should be understood that the cutting chips generated by each first cutting edge 32 and the adjacent rotationally leading second cutting edge 40 flow along the same chip evacuation groove 70 and into the shank groove 88 which is aligned with them in the rotational direction. By configuring the shank surface 86 to have just two shank grooves 88, it is advantageously possible to manufacture the tool shank 82 efficiently and economically.
[0136] [000149] In an embodiment of the present invention in which the cutting head 20 and the tool shank 82 are integral parts of a one-piece structure (not shown), the two chip evacuation grooves 70 may merge into two shank grooves 88.
[0137] [000150] As shown in Figures 10 to 14, the front end 84 of the tool shank may include two shank projections 96 that are spaced apart in the circumferential direction.
[0138] [000151] In one embodiment of the present invention, each shank projection 96 may extend axially forward of the support surface 92 of the tool shank.
[0139] [000152] As shown in Figures 10 to 14, each shank projection 96 may have a drive surface 98 facing the rotational direction RD, and in the assembly position of the cutting tool 80, each torque transmission surface 72 may be in contact with one of the drive surfaces 98.
[0140] [000153] In one embodiment of the present invention, each shank projection 96 may have a projection end face 100 facing forward, and each second gash endpoint NG2 may be positioned axially forward of one of the projection end faces 100.
[0141] [000154] As shown in Figures 10 to 14, each shank projection 96 may have an inner projection surface 102 facing radially inward, and each inner projection surface 102 may face one of the second headland surfaces 42.
[0142] [000155] Also, as shown in Figures 10 to 14, the front end 84 of the tool shank may include a central pocket recess 104, and in the assembly position of the cutting tool 80, the central mounting stem 76 may occupy the central pocket recess 104.
[0143] [000156] In one embodiment of the present invention, the central pocket recess 104 may extend axially rearward from the support surface 92 of the tool shank along the shank axis AS.
[0144] [000157] In one embodiment of the present invention, the central pocket recess 104 may also have at least two inner pocket surfaces 106 that are spaced apart in the circumferential direction and face radially inward, and each inner pocket surface 106 may face the outer stem surface 78 of the central mounting stem.
[0145] [000158] Furthermore, in one embodiment of the present invention, as shown in Figures 10 to 14, the central pocket recess 104 may intersect with two shank grooves 88 to form exactly two inner pocket surfaces 106, each inner pocket surface 106 may be in clamping contact with a corresponding stem clamp area 108 on the outer stem surface 78 of the mounting stem.
[0146] [000159] In an embodiment of the present invention in which a central pocket recess 104 is provided at the front end 84 of the tool shank, it should be understood that the forward-facing support surface 92 may have two spaced-apart support sub-surfaces.
[0147] [000160] Although the present invention has been described in some detail, it should be understood that various changes and modifications are possible without departing from the scope of the invention as described in the claims below.
Claims
1. A cutting head (20) that is rotatable in the rotational direction (RD) about a head axis (AH), wherein the head axis (AH) establishes a head forward direction (HF) and a head rearward direction (HR) opposite to the head forward direction (HF), and the cutting head (20) is A cutting portion (22) having a cutting tip (24) whose axially forward tip point (NT) is included in the head axis (AH), wherein a pair of first cutting arms (26) are alternately arranged in the circumferential direction with a pair of second cutting arms (28), Each first cutting arm (26) has a first cutting edge (32) extending radially outward from the cutting tip (24) and a first headland surface (34) facing radially outward. The first cutting edge (32) extends from the cutting tip (24) to the two radially outermost first cutting points (NRO1), and the two first cutting points (NRO1) define a virtual first circle (C1) having a first diameter (D1) and a center coinciding with the head axis (AH) in a plan view of the cutting head (20), and each first cutting edge (32) includes a first radially outer cutting edge portion (36) and a first radially inner cutting edge portion (38), and the virtual first circle (C1) is located in a first plane (P1) perpendicular to the head axis (AH). Each second cutting arm (28) has a second cutting edge (40) extending radially outward from the cutting tip (24) and a second headland surface (42) facing radially outward. The second cutting edge (40) extends to the two outermost second cutting points (NRO2) in the radial direction, and the two second cutting points (NRO2) define a virtual second circle (C2) having a second diameter (D2) and a center coinciding with the head axis (AH) in a plan view of the cutting head (20), and the virtual second circle (C2) is located in a second plane (P2) perpendicular to the head axis (AH). The first diameter (D1) is larger than the second diameter (D2), In a cross-section along a fifth plane (P5) that encompasses the head axis (AH) and intersects the first cutting arm (26), each first cutting edge (32) has a first cutting profile (PC1), and each first radially inner cutting edge portion (38) has a first inner cutting profile (PCI1). In a cross-section along a sixth plane (P6) that encompasses the head axis (AH) and intersects the second cutting arm (28), each second cutting edge (40) has a second cutting profile (PC2). A cutting head (20) wherein the first internal cutting profile (PCI1) is identical to the second cutting profile (PC2).
2. The cutting head (20) according to claim 1, wherein the pair of first cutting edges (32) exhibit two-fold rotational symmetry about the head axis (AH).
3. The cutting head (20) according to claim 1 or 2, wherein each first cutting edge (32) extends monotonically backward in the axial direction from the cutting tip (24) to the radially outermost first cutting point (NRO1).
4. The cutting head (20) according to any one of claims 1 to 3, wherein the pair of second cutting edges (40) exhibit two-fold rotational symmetry about the head axis (AH).
5. The cutting head (20) according to any one of claims 1 to 4, wherein each second cutting edge (40) extends monotonically backward in the axial direction from the cutting tip (24) to the radially outermost second cutting point (NRO2).
6. The cutting head (20) according to any one of claims 1 to 5, wherein the second diameter (D2) is greater than 30% of the first diameter (D1) and less than 70% of the first diameter (D1).
7. Each first radially inner cutting edge portion (38) is formed at the intersection of a first inner rake face (50) facing the rotational direction (RD) and a first inner relief face (52) facing forward in the axial direction. Each second cutting edge (40) is formed at the intersection of a second rake face (56) facing the rotational direction (RD) and a second relief face (58) facing forward in the axial direction, according to any one of claims 1 to 6, the cutting head (20).
8. A virtual third cylinder (S3) having a circular cross-section centered on the head axis (AH) intersects the pair of first radially inner cutting edge portions (38) at two first intersections (N1), and intersects the pair of second cutting edges (40) at two second intersections (N2), In a cross-section along a seventh plane (P7) that is tangent to the virtual third cylinder (S3) and encompasses one of the first intersections (N1), the first inner rake face (50) forms a first inner rake angle (α1) that is acute with respect to a first virtual perpendicular line (LV1) that encompasses one of the first intersections (N1) and is parallel to the head axis (AH). In a cross-section along an eighth plane (P8) that is tangent to the virtual third cylinder (S3) and encompasses one of the second intersections (N2), the second rake face (56) forms a second rake angle (α2) that is acute with respect to a second virtual vertical line (LV2) that encompasses one of the second intersections (N2) and is parallel to the head axis (AH). The cutting head (20) according to claim 7, wherein the first internal rake angle (α1) and the second rake angle (α2) are equal.
9. In a cross-section along the seventh plane (P7), the first inner relief surface (52) encompasses one of the first intersections (N1) and forms a first inner relief angle (β1) that is acute with respect to the first virtual horizontal line (LH1) perpendicular to the first virtual vertical line (LV1). In a cross-section along the eighth plane (P8), the second relief surface (58) encompasses one of the second intersections (N2) and forms a second relief angle (β2) that is acute with respect to the second virtual horizontal line (LH2) perpendicular to the first virtual vertical line (LV1). The cutting head (20) according to claim 8, wherein the first inner relief angle (β1) and the second relief angle (β2) are equal.
10. Each first inner scoop face (50) is formed on the first point thinning gash (54), A cutting head (20) according to any one of claims 7 to 9, wherein each second rake face (56) is formed on a second point thinning gash (60).
11. In a cross-section along a ninth plane (P9) perpendicular to the head axis (AH) and intersecting the pair of first radially inward cutting edge portions (38) and the pair of second cutting edges (40), a virtual third circle (C3) is inscribed within the two first point thinning gashs (54), and a virtual fourth circle (C4) is inscribed within the two second point thinning gashs (60). The cutting head (20) according to claim 10, wherein the virtual third circle (C3) and the virtual fourth circle (C4) coincide.
12. The cutting head (20) according to claim 10 or 11, wherein one of the first point thinning gashs (54) and one of the second point thinning gashs (60) intersect at each second headland surface (42).
13. Each second cutting arm (28) has a second front surface (62) facing forward in the axial direction, A cutting head (20) according to any one of claims 10 to 12, wherein adjacent first point thinning gashs (54) that follow in the rotational direction intersect each second front surface (62).
14. Each first cutting arm (26) has a first front surface (64) facing forward in the axial direction, A cutting head (20) according to any one of claims 10 to 13, wherein adjacent second point thinning gashs (60) that follow in the rotational direction intersect each first front surface (64).
15. Each first radially outer cutting edge portion (36) is formed at the intersection of a first outer rake face (66) facing the rotational direction (RD) and a first outer relief face (68) facing forward in the axial direction. The cutting head (20) according to claim 14, wherein each first outer relief surface (68) is positioned on one of the first front surfaces (64).
16. The cutting head (20) according to claim 15, wherein the first outer rake face (66) is formed on a chip discharge groove (70) extending axially rearward.
17. The cutting head (20) is the cutting head (20) according to any one of claims 1 to 16, wherein the cutting head (20) exhibits two-fold rotational symmetry about the head axis (AH).
18. The virtual second cylinder (S2) has a circular cross-section centered on the head axis (AH) and a virtual second cylindrical surface (46), The virtual second cylinder (S2) has a second cylindrical diameter (DS2) that is larger than the second diameter (D2) and smaller than the first diameter (D1). The pair of second cutting arms (28) are positioned entirely inside the virtual second cylinder (S2). The cutting head (20) according to any one of claims 1 to 17, wherein the virtual second cylindrical surface (46) intersects the pair of first cutting arms (26).
19. The cutting head (20) according to claim 18, wherein the virtual second cylindrical surface (46) intersects the pair of first radially outer cutting edge portions (36).
20. The first cutting profile (PC1) has a first cross-sectional profile width W1, Both the first internal cutting profile (PCI1) and the second cutting profile (PC2) have a second cross-sectional profile width W2. A cutting head (20) according to any one of claims 1 to 19, wherein W1 × 0.30 < W2 < W1 × 0.
70.
21. A rotary cutting tool (80), A long tool shank (82) having a shank axis (AS) that establishes a shank forward direction (SF) and a shank rearward direction (SR) opposite to the shank forward direction (SF), The cutting head (20) according to any one of claims 1 to 20 is positioned at the front end (84) of the tool shank (82), The shank circumferential surface (86) extends along the shank axis (AS) away from the front end (84) of the tool shank (82), The shank circumferential surface (86) has exactly two shank land surfaces (90) and exactly two shank grooves (88) arranged alternately in the circumferential direction, the rotary cutting tool (80).
22. The front end (84) of the tool shank (82) has a support surface (92) facing forward. The cutting portion (22) of the cutting head has a bottom surface (30) facing the rear, The cutting head (20) is detachably fixed to the front end (84) of the tool shank (82), The head axis (AH) and the shank axis (AS) coincide. The cutting tool (80) according to claim 21, wherein the bottom surface (30) of the cutting head faces the support surface (92) of the tool shank.
23. Each first headland surface (34) has a head leading edge (48) that extends axially rearward from the radially outermost first cutting point (NRO1) associated with it to the axially rearmost head leading endpoint (NHR1). Each shank land surface (90) has a shank leading edge (94) that extends axially rearward from the shank leading endpoint (NSF1) at the axial front end, The two head leading endpoints (NHR1) are located on a fourth plane (P4) that encompasses the head axis (AH), The two shank leading ends (NSF1) are located on the 11th plane (P11) that encompasses the shank axis (AS), The cutting tool (80) according to claim 22, wherein the fourth plane (P4) and the eleventh plane (P11) form a first rotational offset angle (φ1) of less than 15 degrees.
24. The cutting tool (80) according to claim 22 or 23, wherein the bottom surface (30) of the cutting head is in contact with the support surface (92) of the tool shank.
25. Each first cutting arm (26) includes a torque transmission surface (72) facing opposite to the rotational direction (RD), The front end (84) of the tool shank includes two shank projections (96) spaced apart in the circumferential direction, and each shank projection (96) has a drive surface (98) facing the rotational direction (RD). The cutting tool (80) according to any one of claims 22 to 24, wherein each torque transmission surface (72) is in contact with one of the drive surfaces (98).