Rotary cutting tool with hybrid cutting insert design

Abstract

A rotary cutting tool having a hybrid cutting insert design is disclosed. A rotary cutting tool includes a cutting head having a plurality of insert receiving pockets for radially mounting a first type of cutting insert in a first cutting region and for tangentially mounting a second type of cutting insert in a second cutting region. The first cutting region has a first length L1 and the second cutting region has a second length L2 that is greater in size than the first length L1. The two types of cutting inserts provide a hybrid cutting insert design in which the first type of cutting insert provides increased chip flute volume for effective chip evacuation and the second type of cutting insert provides increased core diameter for minimizing deflection of the rotary cutting tool.

Description

Technical Field

[0001] The present invention relates to a rotary cutting tool on which cutting inserts are mounted, and more particularly to a helical end mill with a hybrid design having at least one row of first-type radially mounted cutting inserts in the front row and at least one row of second-type tangentially mounted cutting inserts in the rear row. Background Technology

[0002] Long end mills exhibit significant deflection when subjected to cutting loads. This creates excessive stress at the base of the tool, exceeding the yield strength of the tool body material, leading to failure.

[0003] Tangentially mounted inserts improve this situation because they are thinner in the radial direction and take into account a larger core diameter on the cutter body. However, because the chip kerf (i.e., chip flute) is also thinner, thinner inserts cannot remove chips from the cut as effectively as radially mounted inserts. To be an effective long helical end mill, a rotary cutting tool must have both rigidity and sufficient effective chip evacuation space. Summary of the Invention

[0004] The problem of providing a milling cutter that has both rigidity and sufficient chip removal space is solved by providing a rotary cutting tool, such as a milling cutter, which has radially mounted cutting inserts in the front row and tangentially mounted cutting inserts in the rear row.

[0005] By using two types of inserts with different thicknesses, the hybrid design of this invention provides sufficient chip groove (i.e., chip flute) volume for effective chip removal, with the most critical aspect being the direction towards the front of the cutter during chip removal; and provides a larger cross-sectional core diameter, with the greatest curvature towards the base of the cutter. Finite element analysis (FEA) shows a reduction in deflection of approximately 30% compared to cutters with only radially mounted cutting inserts.

[0006] In one aspect of the invention, a rotary cutting tool includes a cutting head having a plurality of blade receiving grooves in a first cutting region near an end face of the rotary cutting tool and in a second cutting region near the shank of the rotary cutting tool. A plurality of first-type cutting blades are mounted in the blade receiving grooves in the first cutting region of the cutting head. Each first-type cutting blade has a first thickness. A plurality of second-type cutting blades are mounted in the blade receiving grooves in the second cutting region of the cutting head. The plurality of first-type cutting blades provide an increased kerf volume for effective chip removal, and the plurality of second-type cutting blades provide an increased core diameter to minimize deflection of the rotary cutting tool.

[0007] In another aspect of the invention, a rotary cutting tool includes a cutting head having a plurality of insert receiving grooves in a first cutting region near an end face of the rotary cutting tool and a second cutting region near a tool shank of the rotary cutting tool. The first cutting region has a first length L1, and the second cutting region has a second length L2. A plurality of first-type cutting inserts are radially mounted in the insert receiving grooves of the first cutting region of the cutting head. A plurality of second-type cutting inserts are tangentially mounted in the insert receiving grooves of the second cutting region of the cutting head. The first length L1 of the first cutting region is greater than 50% of the total length (L1+L2) of the first and second cutting regions. Attached Figure Description

[0008] While various embodiments of the invention have been shown, the specific embodiments illustrated should not be construed as limiting the claims. Various changes and modifications are contemplated without departing from the scope of the invention.

[0009] Figure 1 This is a side view of a rotary cutting tool according to an embodiment of the present invention, on which a plurality of cutting blades are mounted;

[0010] Figure 2 yes Figure 1 End view of a rotary cutting tool;

[0011] Figure 3 This is a perspective view of a first type of cutting insert according to one aspect of the present invention;

[0012] Figure 4 yes Figure 3 A side view of an exemplary embodiment of a first type of cutting insert;

[0013] Figure 5 yes Figure 3 A top view of an exemplary embodiment of a first type of cutting insert;

[0014] Figure 6 It is along Figure 5 A cross-sectional view of an exemplary embodiment of a first type of cutting insert, taken by line 6-6;

[0015] Figure 7 It is an enlarged view of the chip formation characteristics of a first type of cutting insert, which has an optional cutting face formed at a zero angle relative to the central longitudinal axis of the cutting insert;

[0016] Figure 8 This is a perspective view of a second type of cutting insert according to one aspect of the present invention;

[0017] Figure 9 yes Figure 8 A front view of an exemplary embodiment of a second type of cutting insert;

[0018] Figure 10 yes Figure 8 An isometric front view of an exemplary embodiment of a second type of cutting insert;

[0019] Figure 11 yes Figure 8 An equidistant end view of an exemplary embodiment of a second type of cutting insert;

[0020] Figure 12 yes Figure 8 A top view of an exemplary embodiment of the second type of cutting insert;

[0021] Figure 13 It is along Figure 12 A cross-sectional view of an exemplary embodiment of a second type of cutting insert, taken by line 13-13; and

[0022] Figure 14 It is along Figure 12 A cross-sectional view of an exemplary embodiment of a second type of cutting insert, taken by line 14-14. Detailed Implementation

[0023] For reference Figure 1 and Figure 2 According to one embodiment of the invention, a rotary cutting tool is generally shown as 10. Typically, the rotary cutting tool 10 includes a helical end mill comprising a cutter body 12 having an elongated and generally cylindrical shape. The cutter body 12 includes a shank 16 and a cutting head 18. As is known in the art, the shank 16 is configured to be inserted into and secured within the spindle of a milling machine (not shown). In the illustrated embodiment, the shank 16 has a tapered design to allow insertion into and secure within the spindle. However, it should be understood that the shank 16 can be of any shape or design to allow insertion into and secure within the spindle. Such designs include, but are not limited to, V-flanges, shell mill mounts, Weldon shanks, etc. In the illustrated embodiment, the rotary cutting tool has a large length-to-diameter ratio (i.e., L / D ratio) greater than about 2:1.

[0024] Although the end mill is described in the illustrated embodiment, the principles of the invention can be applied to other types of rotary cutting tools, such as end mills, twist drills, etc.

[0025] Directional phrases used herein, such as left, right, front, back, top, bottom, and their derivatives, relate to the orientation of the elements shown in the accompanying drawings and do not limit the claims unless expressly stated herein. In all the drawings, the same parts have the same reference numerals.

[0026] As used herein throughout the specification and claims, approximate language can be used to modify any quantitative expression that allows for variation without causing a change in the fundamental function it relates to. Therefore, values ​​modified by one or more terms such as “about,” “approximately,” and “substantially” are not limited to the specified precise values. In at least some cases, approximate language can correspond to the precision of the instrument used to measure the value. In this document and throughout the specification and claims, scope limitations can be combined and / or interchanged, and unless the context or language otherwise indicates, these scopes are identified and include all sub-scopes contained herein.

[0027] Throughout the text and claims, the use of the word “about” relative to a range of values ​​(e.g., “about 2 inches to 5 inches”) is intended to modify the high and low values ​​listed and to reflect the degree of ambiguity associated with variations in measurement, significant figures, and interchangeability, all of which should be understood by one of ordinary skill in the art to which this invention pertains.

[0028] For the purposes of this specification (except in operational examples), unless otherwise stated, all numerical values ​​representing quantities and ranges of components, process conditions, etc., should in all cases be understood to be modified by the term "about". Therefore, unless stated to the contrary, the numerical parameters listed in this specification and the appended claims are approximations that may vary according to the desired results sought to be obtained according to the invention. To a minimum, and without attempting to limit the application of the doctrine of equivalence to the scope of the claims, each numerical parameter should be interpreted at least based on the reported significant figures and by employing general rounding techniques. Furthermore, as used in this specification and the appended claims, the singular forms "an", "a", and "the" are intended to include plural references unless explicitly and unambiguously limited to a single designation.

[0029] Although the numerical ranges and parameters listing the broad scope of the invention are approximate, the values ​​listed in specific examples are reported as precisely as possible. However, any numerical value inherently contains some error, which must be caused by the standard deviation (including the standard deviation found in the measuring instrument) found in their respective test measurements. Similarly, it should be understood that any numerical range listed herein is intended to include all subranges contained therein. For example, the range "1 to 10" is intended to include all subranges between the listed minimum value of 1 and the listed maximum value of 10, that is, the range having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10. Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Unless otherwise expressly stated, the various numerical ranges specified in this application are approximate.

[0030] In the following description and claims, several terms with the following meanings are referenced.

[0031] Unless the context clearly indicates otherwise, the singular forms “a,” “a,” and “the” include plural references.

[0032] "Optional" or "optionally" means that the event or situation described below may or may not occur, and the description includes instances where the event occurs and instances where the event does not occur.

[0033] As used in this article, the term "elongated" is defined as something that is longer than its width. In other words, its width is less than its length.

[0034] As used in this article, a rotary cutting tool with a “large L / D ratio” is defined as a rotary cutting tool having a length-to-diameter ratio (i.e., L / D ratio) greater than about 2:1.

[0035] As used herein, the term "region" is defined as any principal sub-region into which something or a portion thereof is divided. For example, a cutting head is divided into two regions: a first cutting region and a second cutting region. In another example, a simple closed curve divides a plane into two regions.

[0036] The cutting head 18 is typically a cylindrical or generally cylindrical body or shaft extending axially from the shank 16 to the end face 20. The cutting head 18 includes a plurality of helical chip grooves or chip outlets 24. It should be understood that the invention is not limited by the number of chip outlets 24. For example, in the illustrated embodiment, the cutting tool 10 includes a total of five chip outlets 24, although any number of chip outlets is conceivable in the invention. Each chip outlet 24 cuts into the cutting head 18 in a helical or spiral manner, extending generally from the end face 20 to the shank 16. In one embodiment, each chip outlet 24 is cut at a helix angle 26 relative to the central longitudinal axis 28 of the cutter body 12 at a helix angle 26 between about 10 degrees and about 40 degrees.

[0037] The length L of the rotary cutting tool 10 is between approximately 6.85 inches (174 mm) and approximately 8.03 inches (204 mm), and its cutting diameter D is between approximately 2.48 inches (63 mm) and approximately 3.10 inches (80 mm). For example, in one embodiment, the length L of the rotary cutting tool 10 is approximately 11.5 inches (292.1 mm), and its cutting diameter D is approximately 3.0 inches (76.2 mm). Figure 1 As shown, the blade 12 rotates around the central longitudinal axis 28 in the direction of the arrow.

[0038] Each chip outlet 24 is disposed between and associated with the helical group or row 30 of the cutting inserts 100, 200. The tool body 12 includes a plurality of insert receiving slots 32 for mounting the respective cutting inserts therein. When the cutting tool 10 is assembled, each of the cutting inserts 100, 200 is held in its respective insert receiving slot 32 by insert screws 34.

[0039] In the illustrated embodiment, there is a one-to-one correspondence between the number of helical assemblies or rows 30 and the number of chip grooves 24. As described above, the rotary cutting tool 10 in the illustrated embodiment includes a total of five chip grooves 24. Therefore, the rotary cutting tool 10 includes a total of five helical assemblies or rows 30 of cutting blades 100, 200. However, it should be understood that the present invention is not limited by the number of chip grooves and the corresponding number of helical rows, and the present invention can be implemented with any desired number of chip grooves and helical rows depending on the size of the tool body 12.

[0040] As mentioned above, end mills with longer lengths (i.e., greater than 5.9 inches (150 mm)) or larger L / D ratios (i.e., L / D ratio greater than 2:1) exhibit greater deflection when a cutting load is applied. This creates excessive stress at the base of the tool, exceeding the yield strength of the tool body material, leading to failure.

[0041] According to one aspect of the invention, the cutting head 18 includes a plurality of first-type cutting inserts, generally shown as 100, radially mounted in a first cutting region 40 of the cutting head 18, and a plurality of second-type cutting inserts, generally shown as 200, tangentially mounted in a second cutting region 50 of the cutting head 18. By using two types of cutting inserts 100, 200 with different thicknesses, the hybrid design of the invention provides sufficient chip kerf (i.e., chip flute) volume for effective chip removal, with the most critical aspect being towards the front of the cutter (i.e., near the end face 20); and provides a larger cross-sectional core diameter, with the greatest curvature towards the base of the cutter (i.e., near the shank 16).

[0042] like Figure 1As shown, a first type of cutting insert 100 is mounted on a cutting head 12 in a first cutting region 40 of a cutting head 18 having a first length L1, and a second type of cutting insert 200 is mounted on a cutting head 12 in a second cutting region 50 having a second length L2. The first cutting region 40 extends from the end face 20, and the second cutting region 50 extends from the first cutting region 40 to the shank 16. In one aspect, the first length L1 of the first cutting region 40 is larger in size than the second length L2 of the second cutting region 50. In other words, the first length L1 is greater than 50% of the total length (L1+L2) of the first length L1 and the second length L2. For example, the first cutting region 40 may have a first length L1 of about 6.05 inches (153.66 mm), and the second cutting region 50 may have a second length L2 of about 3.226 inches (81.95 mm). In this example, the total length (L1+L2) of the first cutting region 40 and the second cutting region 50 is about 9.28 inches (235.6 mm). Therefore, the first length L1 of the first cutting region 40 is about 65.22% of the total length (L1+L2) of the first and second cutting regions 40 and 50, and the second length L2 of the second cutting region 50 is about 34.78% of the total length (L1+L2) of the first and second cutting regions 40 and 50.

[0043] It should be noted that the present invention is not limited by the relative lengths L1 and L2 of the first and second cutting regions 40 and 50, and for the first and second cutting regions 40 and 50, as long as the first length L1 of the first cutting region 40 is larger in size than the second length L2 of the second cutting region 50 (i.e., larger than 50% of the total length L1+L2), the present invention can be implemented with any desired lengths L1 and L2.

[0044] For reference Figures 3-7 The first type of cutting insert 100 is a generally square, indexable cutting insert having a first or top surface 112, a second or bottom surface 114, and a plurality of flank faces 116. Cutting edges 120 are formed at the intersections between the top surface 112 and each flank face 116, and also at the intersections between the bottom surface 114 and each flank face 116. Therefore, the cutting insert 100 has a total of eight cutting edges 120. It should be understood that, since the terms "top" and "bottom" are directional phrases, when the cutting insert is inverted and mounted in the insert groove 32, the "top" surface 112 of the cutting insert 100 becomes the "bottom" surface 114, and vice versa.

[0045] In the illustrated embodiment, the top surface 112 and the bottom surface 114 of the cutting blade 100 are substantially the same. Therefore, for the sake of brevity, only the top surface 112 will be described here. However, it should be understood that the description of the top surface 112 also applies to the bottom surface 114.

[0046] like Figure 3 As shown, the two opposing flank faces 116 are rotationally symmetrical about a first central axis A1 passing through them (180° rotational symmetry), the other two opposing flank faces 116 are rotationally symmetrical about a second central axis A2 passing through them (180° rotational symmetry), and the top and bottom surfaces 112 and 114 are rotationally symmetrical about a third central axis A3 passing through them (180° rotational symmetry). The second central axis A2 is perpendicular to the first central axis A1, and the third central axis A3 is perpendicular to both the first and second central axes A2. It should be noted that the first central axis A1 is approximately parallel to the Y-axis of the cutting insert 100, the second central axis A2 is approximately parallel to the X-axis of the cutting insert 100, and the third central axis A3 is approximately parallel to the Z-axis of the cutting insert 100.

[0047] like Figure 4 and 5 As shown, the cutting insert 100 has a length LX1 along the X-axis, a length LY1 along the Y-axis, and a length LZ1 along the Z-axis. Lengths LX1, LY1, and LZ1 are also referred to as the height, width, and thickness of the cutting insert 100, respectively. Because the cutting insert 100 is approximately square, the length LY1 along the Y-axis is equal to the length LX1 along the X-axis. It should be noted that lengths LX1 and LY1 are larger than length LZ1. For example, in one embodiment, lengths LX1 and LY1 are approximately 0.394 inches (10.00 mm), and length LZ1 is approximately 0.178 inches (4.52 mm).

[0048] The cutting insert 100 can be made of any suitable material. For example, the cutting insert 100 can be made of a material selected from the group consisting of alumina-based ceramics, silicon nitride-based ceramics, and SiALON-based ceramics. Preferably, the ceramic composition has a reinforcing agent dispersed therein, which is selected from ceramic whiskers (e.g., titanium carbide and / or silicon carbide), ceramic particles (e.g., zirconium oxide, hafnia, silicon carbide, and / or titanium carbide), and mixtures thereof. Additionally, preferably, the ceramic composition also contains residues of sintering aids dispersed therein. Preferably, the sintering aids are selected from zirconium oxide, alumina, aluminum nitride, yttrium oxide, yttrium oxide, lanthanum oxide, magnesium oxide, and mixtures thereof or with other elements. A preferred ceramic composition contains about 90-100% silicon nitride or silon phase, with rare earth oxides added in an amount of 0-15% by weight, all of which are distributed within the silicon nitride or silon matrix. More preferably, the composition has 4 to 12 weight percent aluminum nitride and 2 to 10 weight percent 5 to 12 percent yttrium oxide.

[0049] review Figure 3The top surface 112 of the cutting insert 100 includes a chip-forming feature, generally shown as 118, which extends in a generally radially inward direction from each cutting edge 120 to the inner edge 122. The chip-forming feature 110 may include an optional cutting face 124 adjacent to the cutting edge 108, the width 126 of which is between about 0.0 inch and about 0.2 inch (0.508 mm).

[0050] For reference Figure 7 The cutting edge 124 can be formed at an angle 128 between about 0.0 degrees and about -25.0 degrees relative to a plane 130 that is generally perpendicular to the central longitudinal axis 132 of the cutting insert 100.

[0051] like Figure 7 As shown, the chip forming feature 118 also includes a front wall 134 that slopes radially inward toward a rounded bottom surface 136 from an optional cutting face 124 (or from the cutting edge 120 if the cutting face 124 is omitted). The front wall 134 slopes downward at a rake angle 138 of about 10 degrees to about 25 degrees relative to a plane 130 that is substantially perpendicular to the central longitudinal axis 132 of the cutting insert 100. A rounded bottom surface 136 is formed with a radius R of about 0.02 inches (0.508 mm) to about 0.08 inches (2.032 mm). The depth 140 of the rounded bottom surface 136 relative to the cutting edge 120 of the cutting insert 100 is between about 0.006 inches (0.1524 mm) and about 0.025 inches (0.635 mm).

[0052] It is worth noting that the inner edge 22 is located at the intersection of the rear wall 142 and the centrally flat platform 144. The rear wall 142 is inclined upward at an angle 146 of about 30 degrees to about 50 degrees relative to a plane 130 that is generally perpendicular to the central longitudinal axis 132 of the cutting insert 100. When the cutting insert 100 is mounted in the end mill 10, the central platform 144 serves as the seat surface of the cutting insert 100.

[0053] The foregoing has shown and described a first-class cutting insert 100 that is generally square. However, it should be understood that the invention is not limited to the shape of the cutting insert 100, and the principles of the invention can be implemented with cutting inserts having any desired shape. For example, the principles of the invention can be implemented with a circular cutting insert. Other shapes, such as triangular, rectangular, and any polygonal cutting inserts, are also considered within the scope of the invention.

[0054] For reference Figures 8-14A second type of cutting insert 200 according to an embodiment of the present invention is shown. Typically, the cutting insert 200 is rectangular in shape and has two identical opposing end facets 212, two identical opposing secondary side surfaces 214 extending between the two opposing end facets 212, and two identical opposing primary side surfaces 216 extending between the end facets 212 and the secondary side surfaces 214. Each end facet 212 is rotationally symmetric about a first central axis A1 passing through the two end faces 212, each secondary side surface 214 is rotationally symmetric about a second central axis A2 passing through the two secondary side surfaces 214, and each primary side surface 216 is rotationally symmetric about a third central axis A3 passing through the two primary side surfaces 216. The second central axis A2 is perpendicular to the first central axis A1, and the third central axis A3 is perpendicular to the first central axis A1 and the second central axis A2. The cutting insert 200 also includes four opposing corner side surfaces 218 extending between the secondary side surfaces 214 and the primary side surfaces 216 and the end face 212.

[0055] like Figure 9 and 12 As shown, the cutting insert 100 has a length LX2 along the X-axis, a length LY2 along the Y-axis, and a length LZ2 along the Z-axis. Lengths LX2, LY2, and LZ2 are also referred to as the height, width, and thickness of the cutting insert 200, respectively. It should be noted that lengths LX2 and LY2 are larger than length LX2, and length LY2 is larger than length LX2. For example, in one embodiment, length LX2 is approximately 0.512 inches (13.00 mm), length LY2 is approximately 0.532 inches (13.50 mm), and length LZ2 is approximately 0.250 inches (6.35 mm).

[0056] It should also be noted that the length LZ2 of the second type of cutting insert 200 is smaller in size than the length LX1 of the first type of cutting insert 100. For example, in the illustrated embodiment, the length LZ2 of the second type of cutting insert 200 is approximately 0.250 inches (6.35 mm), and the length LX1 of the first type of cutting insert 100 is approximately 0.178 inches (10.00 mm). The difference in lengths LZ2 and LX1 relative to the first type of cutting insert 100 radially mounted in the first cutting region 40 near the end face 20 (i.e., the distal end of the shank 16) allows the tangentially mounted second type of cutting insert 200 to provide an increased core diameter in the second cutting region 50 near the shank 16.

[0057] Each end face 212 has four corners: two diagonally opposite descending angles 220 and two diagonally opposite ascending angles 222. The descending angles 220 are closer to the second central axis A2 than the ascending angles 222. Each corner side surface 218 extends between the ascending angle 222 of one of the two opposite end faces 212 and the descending angle 220 of the other of the two opposite end faces 212.

[0058] Two opposing primary edges 232 are formed at the intersection of each end face 212 and the primary side surface 216, two opposing secondary edges 234 are formed at the intersection of each end face 212 and the secondary side surface 214, and two opposing corner edges 236 are formed at the intersection of each corner side surface 218 and the primary side surface 216. A primary cutting edge 238 is formed at the intersection of each primary edge 232 and the end face 212 and extends approximately along the entire length of its associated primary edge 232. A secondary cutting edge 240 is formed at the intersection of each secondary edge 234 and the end face 214 and extends along its associated secondary edge 234. A corner cutting edge 242 is formed at the intersection of the primary and secondary cutting edges 238 and 240. Since the cutting insert 200 is symmetrical about all three axes: axes A1, A2, and A3, the cutting insert 200 has a total of four primary cutting edges 238, four secondary cutting edges 240, and four corner cutting edges 242.

[0059] The section of the main cutting edge 238 near the rise angle 222 constitutes the front end 244 of the main cutting edge 238, while the section of the main cutting edge 238 near the fall angle 220 constitutes the rear end 246 of the main cutting edge 238, as shown below. Figure 9 and 10 As shown. The main cutting edge 238 is formed at an angle 239 relative to the second axis A2. Angle 239 can be in the range of approximately 5 degrees to approximately 10 degrees. For example, angle 239 can be approximately 12 degrees.

[0060] For reference Figure 12 Each secondary side surface 214 is formed having a large radius R1. Therefore, each secondary side surface 214 has a convex profile. In one embodiment, the radius R1 ranges from about 0.75 inches (19.05 mm) to about 1.25 inches (31.75 mm). For example, in the illustrated embodiment, the radius R1 is about 0.984 inches (25.00 mm). However, it should be understood that the invention is not limited to the size of the radius R1, and the invention can be implemented with any desired radius R1 size as long as the secondary side surface 214 has a convex profile.

[0061] For reference Figure 13 and 14Each end face 212 of the cutting insert 200 has a seat surface 230 for contacting the insert groove 32 of the milling cutter 10, which extends integrally from the reduction angle 220 of the cutting insert 200 to an obliquely opposite reduction angle 220. In the illustrated embodiment, the seat surface 230 is in the form of a U-shaped groove, having side support walls 230a, 230b and a bottom wall 30c formed between the two side support walls 230a, 230b. The two side support walls 230a, 230b extend from the bottom wall 230c to a rake face 226 extending between the main edge 232 and the side support walls 230a, 230b.

[0062] Another aspect of the invention is the formation of a bottom wall 230c having a very large radius R2. Therefore, the bottom wall 230c has a concave shape. In one embodiment, the radius R2 is in the range of about 3.00 inches (76.2 mm) to about 5.00 inches (127.0 mm). For example, in the illustrated embodiment, the radius R2 is about 3.937 inches (100.00 mm). However, it should be understood that the invention is not limited to the size of the radius R2, and the invention can be implemented with any desired radius R2 size as long as the bottom wall 230c has a concave shape.

[0063] like Figure 6 As shown, the rake face 226 forms a rake angle 248 relative to the first central axis A1. The rake angle 248 can be greater than 0 degrees and less than 90 degrees. In the illustrated embodiment, the rake angle 248 is approximately 65 degrees. However, it should be understood that the invention is not limited to the size of the rake angle 248, and the invention can be implemented with any desired rake angle.

[0064] like Figure 13 As shown, the distance 250 between the bottom wall 230c and the third central axis A3 remains constant along the entire length of the seat surface 230. In other words, along its entire length, the bottom wall 230c of the seat surface 230 is approximately coplanar from a lowering angle 220 to the opposite lowering angle 220.

[0065] like Figure 12As shown, along its entire length, the bottom wall 230c has a substantially constant width 251 from one downward angle 220 to the opposite downward angle 220. On the other hand, along its entire length, the side support walls 230a and 230b have continuously varying widths 252 from one downward angle 220 to the opposite downward angle 220. Specifically, the widths 252 of the side support walls 230a and 230b are inversely proportional to each other. For example, the width of side support wall 230a is the smallest, while the width 252 of side support wall 230b is the largest at the downward angle 220; the width 252 of side support wall 230a is the largest, while the width 252 of side support wall 230b is the smallest at the opposite downward angle 220. It is noteworthy that the widths 252 of each side support wall 230a and 230b are approximately the same at the intersection of the first central axis A1 and the third central axis A3, as shown... Figure 12 As shown.

[0066] As described above, the rotary cutting tool of the present invention includes a cutting head having a plurality of insert receiving slots for radially mounting a first type of cutting insert in a first cutting region and for tangentially mounting a second type of cutting insert in a second cutting region. The first cutting region has a first length L1, and the second cutting region has a second length L2, the second length L2 being larger in size than the first length L1. These two types of cutting inserts provide a hybrid cutting insert design, wherein the first type of cutting insert provides an increased kerf volume for effective chip removal, and the second type of cutting insert provides an increased core diameter to minimize the deflection of the rotary cutting tool.

[0067] Finite element analysis (FEA) shows that the hybrid cutting insert design of the present invention reduces deflection by approximately 30% compared to the same rotary cutting tool without the hybrid cutting insert design.

[0068] The patents and publications mentioned in this article are incorporated herein by reference.

[0069] Although the present preferred embodiments have been described, the invention may be practiced in other ways within the scope of the appended claims.

Claims

1. A rotary cutting tool, comprising: A cutting head having a plurality of blade receiving grooves in a first cutting region extending from the end face of the rotary cutting tool and in a second cutting region extending from the first cutting region to a position close to the shank of the rotary cutting tool; A plurality of first-class cutting inserts are radially mounted in the insert receiving groove of the first cutting region of the cutting head, each first-class cutting insert having a first length LX1; as well as A plurality of second-type cutting inserts are tangentially mounted in the insert receiving groove of the second cutting region of the cutting head, each second-type cutting insert having a second length LZ2. The second length LZ2 is less than the first length LX1. The plurality of first-class cutting inserts provide increased kerf volume for effective chip removal, and The plurality of second-type cutting inserts provide an increased core diameter to minimize the deflection of the rotating cutting tool. The length-to-diameter ratio of the rotary cutting tool is greater than 2:

1.

2. The rotary cutting tool as claimed in claim 1, wherein the first cutting region has a first length L1 and the second cutting region has a second length L2, and wherein the first length L1 of the first cutting region is greater than 50% of the total length (L1+L2) of the first cutting region and the second cutting region.

3. The rotary cutting tool of claim 1, wherein the first type of cutting insert includes a first surface, a second surface, and at least one flank face extending between the first surface and the second surface, the first surface including a chip forming feature extending radially outward to the cutting edge and radially inward to an inner edge, the chip forming feature including a front wall and a rear wall, the front wall sloping downward from the cutting edge toward a rounded bottom surface, and the rear wall sloping upward from the rounded bottom surface toward the inner edge.

4. The rotary cutting tool of claim 3, wherein the front wall is inclined downward at a rake angle of 10 to 25 degrees relative to a plane substantially perpendicular to the central longitudinal axis of the first type of cutting insert.

5. The rotary cutting tool of claim 3, wherein a rounded bottom surface with a radius R between 0.508 mm and 2.032 mm and a depth between 0.1524 mm and 0.635 mm is formed relative to the cutting edge of the first type of cutting insert.

6. The rotary cutting tool of claim 3, wherein the rear wall is inclined upward at an angle of 30 to 50 degrees relative to a plane substantially perpendicular to the central longitudinal axis of the first type of cutting insert.

7. The rotary cutting tool of claim 3, wherein the inner edge is formed at the intersection between the rear wall and the central platform of the seat surface serving as the first type of cutting insert.

8. The rotary cutting tool as claimed in claim 3, wherein the first type of cutting blade has a polygonal shape.

9. A rotary cutting tool, comprising: The cutting head has multiple blade receiving slots in a first cutting region near the end face of the rotary cutting tool and in a second cutting region near the shank of the rotary cutting tool. A plurality of first-class cutting inserts are mounted in the insert receiving groove in the first cutting region of the cutting head; as well as A plurality of second-type cutting inserts are mounted in the insert receiving groove in the second cutting region of the cutting head. The plurality of first-class cutting inserts provide increased kerf volume for effective chip removal, and The plurality of second-type cutting inserts provide an increased core diameter to minimize the deflection of the rotating cutting tool. The second type of cutting insert includes: Two opposing end faces, two opposing secondary side surfaces extending between the two opposing end faces, and two opposing primary side surfaces extending between the end faces and the secondary side surfaces, each end face having four corners, the four corners including two lowered corners and two raised corners, the two lowered corners being diagonally opposite each other, and the two raised corners being diagonally opposite each other; Two opposing main edges are formed at the intersection of each end face and the main side surface; two opposing secondary edges are formed at the intersection of each end face and the secondary side surface; and two opposing corner edges are formed at the intersection of each corner side surface and the main side surface; and A main cutting edge is formed at the intersection of each main edge and the end face, a secondary cutting edge is formed at the intersection of each secondary edge and the end face, and an angular cutting edge is formed at the intersection of the main cutting edge and the secondary cutting edge. Each end face includes a seat face extending from one lowering angle to the opposite lowering angle. The seat surface is in the form of a U-shaped groove, having a first side support wall, a second side support wall, and a bottom wall between them. The bottom wall is formed with a radius of R2, such that the bottom wall has a concave shape.

10. The rotary cutting tool of claim 9, wherein each secondary side surface is formed with a radius of R1 such that each secondary side surface has a convex shape.

11. The rotary cutting tool of claim 9, further comprising a rake face extending between the first side support wall and the second side support wall and the main edge, wherein the rake face is formed at an angle relative to the central axis A2 passing through the secondary side surface of the second type of cutting insert.

12. The rotary cutting tool of claim 9, wherein the first side support wall and the second side support wall have continuously varying widths.

13. The rotary cutting tool of claim 9, wherein the bottom wall has a constant width.

14. The rotary cutting tool of claim 9, wherein each secondary side surface is rotationally symmetrical about a central axis A2 passing through the two secondary side surfaces at 180°.

15. The rotary cutting tool of claim 9, wherein each primary side surface is rotationally symmetrical about a central axis A3 passing through the two primary side surfaces of the second type of cutting insert at 180°, and wherein the central axis A2 is perpendicular to the central axis A1 passing through the two end faces and the central axis A3 is perpendicular to the central axis A1 and the central axis A2.

16. The rotary cutting tool of claim 9, wherein the second type of cutting insert further comprises four opposing corner side surfaces between the secondary side surface and the end face and between the primary side surface and the end face.

17. The rotary cutting tool of claim 9, wherein the section of the main cutting edge near the rise angle constitutes the front end of the main cutting edge, and wherein the section of the main cutting edge near the fall angle constitutes the tail end of the main cutting edge.

18. The rotary cutting tool of claim 9, wherein the length-to-diameter ratio of the rotary cutting tool is greater than 2:

1.

19. A rotary cutting tool, comprising: A cutting head having a plurality of blade receiving grooves in a first cutting region near the end face of the rotary cutting tool and a second cutting region near the shank of the rotary cutting tool, the first cutting region having a first length L1 and the second cutting region having a second length L2; A plurality of first-class cutting inserts are radially mounted in the insert receiving groove of the first cutting region of the cutting head; as well as A plurality of second-type cutting inserts are tangentially mounted in the insert receiving groove of the second cutting region of the cutting head. The first length L1 of the first cutting region is greater than 50% of the total length (L1+L2) of the first cutting region and the second cutting region.

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