End mill with trimmed cutting edge and method of manufacturing same
By designing a clearance surface with a specific clearance angle for the end milling cutter, the problem of end milling cutter flutter at high spindle speed is solved, achieving a more stable and efficient machining process.
Patent Information
- Application Number
- CN202411570983.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-11-13
- Filing Date
- 2024-11-06
- Publication Date
- 2025-05-13
AI Technical Summary
At high spindle speeds, end milling cutters used to machining non-ferrous materials (such as aluminum) are prone to flutter problems, resulting in poor machining surface finish, shortened tool life, part tolerance issues, and potential machine spindle bearing damage.
A solid end milling cutter with a gap surface is designed, and the cutting edge has a gap angle of less than about 5 degrees adjacent to the inner eccentric gap portion of the groove, and a gap angle of between about 5 degrees and about 15 degrees adjacent to the outer eccentric gap portion of the inner eccentric gap portion.
With this design, it can greatly reduce flutter during machining, improve tool stability and surface finish, extend tool life, and reduce part tolerance problems and machine damage.
Smart Images
Figure CN119973193A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a rotary cutting tool. More particularly, the present invention relates to a solid end mill having a relief surface, the relief surface including an inner eccentric relief portion proximate a radial cutting edge and an outer eccentric relief portion proximate the inner eccentric relief portion. The inner eccentric relief portion is formed with a relief angle less than about 5 degrees and the outer eccentric relief portion is formed with a relief angle between about 5 degrees and about 15 degrees. Background Art
[0002] In its most basic form, milling is the meeting of a rotating tool with a clamped and stationary workpiece, as opposed to turning, where the tool is stationary and the work material rotates. In reality, the workpiece has a feed motion imparted by the machine. The meeting of the rotary motion of the tool and the cutting edge of the tool creates fluctuating cutting forces: vibrations, heat, and, if all goes well, chips.
[0003] Milling machines can have vertical or horizontal spindle orientations, and typically, face milling cuts flat surfaces, but multi-axis computer numerical control (CNC) machines enable the inclusion of three-dimensional movement. That said, there are four basic categories of milling: face milling, perimeter milling, slot milling, and special applications.
[0004] Face milling is used to produce a flat surface (face) on a workpiece. The cutting plane is usually perpendicular to the tool's axis of rotation. Surface finish requirements are an important input in determining the best type of tool.
[0005] Peripheral milling produces a primary surface parallel to the main axis of rotation. Secondary surfaces are sometimes produced by the axial portion of the tool during peripheral milling. The cutting plane is usually parallel to the axis of rotation.
[0006] Slot milling is used to create slots or channels in a workpiece. There are two main types of slot milling tools: disc milling cutters and end milling cutters. Disc milling cutters can be high speed steel, brazed carbide, and indexable insert based. They are typically used for operations that rotate perpendicular to the spindle.
[0007] End mills used for slot milling operations are similar to tools used for perimeter milling. The slots are generated parallel to the spindle rotation.
[0008] When end mills are used for machining non-ferrous materials (such as aluminum, etc.), it is generally desirable to have a cutting edge as sharp as possible without chips or serrated edges. It is also desirable to improve sliding friction to reduce cutting forces and reduce the formation of cutting bumps. A major problem with the milling of non-ferrous materials such as aluminum is chatter at a generally high spindle speed. Combining the natural swinging motion of the tool during the machining process with a very sharp blade will cause the tool to cut into the workpiece because the motion increases the cutting depth in the feed direction. This cutting action increases chip thickness, makes the force greater and further increases chatter. This may result in poor machined surface finish, shortened tool life, part tolerance problems, and potential machine spindle bearing damage. Summary of the invention
[0009] The problem of designing an end mill with a sharp cutting edge capable of machining non-ferrous materials with greatly reduced chatter is solved by providing an end mill with a cutting edge having an inner eccentric relief portion proximate a groove and an outer eccentric relief portion proximate the inner eccentric relief portion having a relatively large relief angle.
[0010] In one aspect of the present invention, a rotary cutting tool includes a handle portion and a cutting portion extending from the handle portion to a cutting tip. The cutting portion has a plurality of blades separated by grooves. Each of the blades includes a relief surface and a radial cutting edge formed at the intersection between the corresponding groove and the relief surface. The relief surface includes an inner eccentric relief portion adjacent to the radial cutting edge and an outer eccentric relief portion adjacent to the inner eccentric relief portion.
[0011] In another aspect of the present invention, a rotary cutting tool having a longitudinal axis includes a shank portion and a cutting portion extending from the shank portion to a cutting tip. The cutting portion has a plurality of blades separated by grooves. Each of the blades includes a relief surface and a radial cutting edge, the radial cutting edge being formed at the intersection between the corresponding groove and the relief surface. The relief surface includes an inner eccentric relief portion adjacent to the radial cutting edge and an outer eccentric relief portion adjacent to the inner eccentric relief portion. The inner eccentric relief portion is formed with an inner eccentric relief angle β of less than about 5 degrees. The outer eccentric relief portion is formed with an outer eccentric relief angle β between about 5 degrees and about 15 degrees. The inner eccentric relief portion is formed with a surface finish of less than 0.15 microns Ra.
[0012] In yet another aspect of the present invention, a method for manufacturing a rotary cutting tool is provided, the rotary cutting tool comprising a handle portion and a cutting portion. The cutting portion has a plurality of blades separated by grooves. Each of the blades comprises a relief surface and a radial cutting edge, the radial cutting edge being formed at the intersection between the corresponding groove and the relief surface. The relief surface comprises an inner eccentric relief portion proximate to the radial cutting edge and an outer eccentric relief portion proximate to the inner eccentric relief portion, the method comprising:
[0013] by grinding a cylindrical blank using a grinding wheel to form a groove and a radial cutting edge;
[0014] grinding an outer relief surface behind and adjacent the radial cutting edge using a grinding wheel, the outer relief surface having an outer eccentric relief angle β between about 5 degrees and about 15 degrees; and
[0015] An inner relief surface is formed by grinding and polishing a portion of the outer eccentric relief surface proximate the radial cutting edge using a fine grit grinding wheel, the inner relief surface having an inner eccentric relief angle β of less than about 5 degrees. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Although various embodiments of the present invention have been shown, the specific embodiments shown should not be construed as limiting the claims. It is contemplated that various changes and modifications may be made without departing from the scope of the present invention.
[0017] Figure 1 is a perspective view of a rotary cutting tool having an improved relief configuration according to an embodiment of the present invention;
[0018] Figure 2 It is along Figure 1 A cross-sectional view of the rotary cutting tool taken along line 2-2;
[0019] Figure 3 yes Figure 1 An enlarged side view of an inner eccentric relief portion and an outer eccentric relief portion of a rotary cutting tool; and
[0020] Figure 4 yes Figure 1 An enlarged cross-sectional view of a rotary cutting tool showing an inner eccentric relief portion and an outer eccentric relief portion of the rotary cutting tool. DETAILED DESCRIPTION
[0021] Reference now Figure 1-4 , a rotary cutting tool 10 is provided, which includes a shank portion 12, a cutting portion 14 having a cutting tip 16, and a central longitudinal axis A. In the illustrated embodiment, the rotary cutting tool 10 includes a solid end mill ( Figure 1). The overall shape of the cutting portion 14 can be, but is not limited to, a cylindrical shape or a frustoconical shape. The cutting portion 14 includes a plurality of blades 18 separated by grooves 20 extending the length of the cutting portion 14. Each blade 18 has a relief surface, generally shown at 22, and a radial (i.e., side) cutting edge 24 formed at the intersection between the groove 20 and the relief surface 22.
[0022] Approximate language as used herein throughout the specification and claims may be applied to modify any quantitative representation that may vary in a permissible manner without causing a change in its associated basic function. Therefore, values modified by words such as "about", "approximately" and "substantially" are not limited to the exact values specified. In at least some cases, approximate terms may correspond to the precision of the instrument used to measure the value. Here and throughout the specification and claims, range limitations may be combined and / or interchanged, unless otherwise indicated by the context or the language, such ranges are determined to include all subranges contained therein.
[0023] Throughout the text and claims, use of the word "about" with respect to ranges of values (e.g., "about 22 wt % to 35 wt %) is intended to modify both the upper and lower values recited and to reflect the degree of ambiguity associated with measurements, significant figures, and interchangeability, all of which would be understood by one of ordinary skill in the art to which the invention pertains.
[0024] For the purpose of this specification (except in the operating examples), unless otherwise indicated, all numerical values representing the number and range of ingredients, process conditions, etc. should be understood as being modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters listed in this specification and the attached claims are approximate values, which may vary according to the desired results sought to be obtained by the present invention. At a minimum, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying general rounding techniques. In addition, as used in this specification and the attached claims, unless explicitly and unambiguously limited to one indicator, the singular forms "a", "a kind" and "the" are intended to include plural indicators.
[0025] Although the numerical ranges and parameters describing the broad scope of the present invention are approximate, the numerical values described in the specific examples are reported as accurately as possible. However, any numerical value inherently contains certain errors, which must be caused by the standard deviations found in their respective test measurements (including the standard deviations found in the measuring instruments). Similarly, it should be understood that any numerical ranges listed herein are intended to include all subranges contained therein. For example, the range "1 to 10" is intended to be included between the listed minimum value 1 and the listed maximum value 10 and include all subranges of the minimum and maximum values, that is, a range with 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 indicated, the various numerical ranges specified in this application are all approximate.
[0026] In the following description and claims, reference is made to a number of terms having the following meanings.
[0027] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.
[0028] "Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
[0029] As used herein, an eccentric relief is defined as a slightly convex surface behind the cutting edge. When a continuous eccentric relief is provided, the relief angle must be measured by the indicator drop per rotation angle using the following formula:
[0030]
[0031] in
[0032] β is the radial relief angle,
[0033] λ is the indicator drop,
[0034] θ is the rotation angle, and
[0035] Alpha is the cutting diameter.
[0036] As used herein, a "fine grit" grinding wheel is a grinding wheel having a D20 grit size (ie, diamond grit size) or finer.
[0037] As used herein, surface finish Ra is a universal unit of measurement for surface roughness. It is the average roughness between the roughness profile and the mean line. Ra is the calculated average between the peaks and valleys on the surface. The lower the Ra value, the smaller the variation between the peaks and valleys on the surface, making the surface smoother.
[0038] In the illustrated embodiment, the end mill 10 has a total of two blades 18 and grooves 20. However, it should be understood that the present invention is not limited by the number of blades and grooves, and the present invention can be implemented with fewer or greater numbers of blades and grooves. For example, the present invention can be implemented with three blades and grooves, four blades and grooves, five blades and grooves, six blades and grooves, seven blades and grooves, eight blades and grooves, etc.
[0039] The blades 18 and grooves 20 of the cutting portion 14 extend helically within the cutting portion 14 at a helix angle HA between about 25 degrees and about 50 degrees relative to the central longitudinal axis A. In another embodiment, the blades 18 and grooves 20 are "straight grooves" extending parallel to the longitudinal axis A. In the illustrated embodiment, the blades 18 and grooves 20 of the cutting portion 14 extend helically within the cutting portion 14 at a helix angle HA of approximately 35 degrees.
[0040] Reference now Figure 3 and 4 One aspect of the present invention is that the relief surface 22 includes an inner eccentric relief portion 30 and an outer eccentric relief portion 32. The inner eccentric relief portion 30 is proximate to the cutting edge 24 and the outer eccentric relief portion 32 is proximate to the inner eccentric relief portion 30. In other words, the inner eccentric relief portion 30 is disposed between the cutting edge 24 and the outer eccentric relief portion 32.
[0041] According to one aspect, the inner eccentric relief portion 30 has a relatively low inner eccentric relief angle β of less than about 5 degrees, and the outer eccentric relief portion 32 has a relatively large outer eccentric relief angle β between about 5 degrees and about 15 degrees. In addition, the inner eccentric relief portion 30 has a very narrow width WI of less than about 0.25 mm, and the outer eccentric relief portion 32 has a relatively much larger width WO of at least twice the width WI of the inner eccentric relief portion 30. In the illustrated embodiment, the width WO of the outer eccentric relief portion 32 is approximately 4 times greater than the width WI of the inner eccentric relief portion 30.
[0042] A method of making the end mill 10 of the present invention having a relief surface 22 with an inner eccentric relief portion 30 and an outer eccentric relief portion 32 will now be described.
[0043] First, a cylindrical blank is ground by using a grinding wheel to form the groove 20 and the corresponding radial cutting edge 24. Next, an outer eccentric relief portion 32 is formed by grinding behind (i.e., behind) and adjacent to the cutting edge 24 using a grinding wheel. The outer eccentric relief portion 32 is formed to have an outer eccentric relief angle β between about 5 degrees and about 15 degrees. Then, an inner eccentric relief portion 30 is formed by grinding and polishing a portion of the outer eccentric relief portion 32 proximate to the cutting edge 24 using a fine sand grinding wheel. The inner eccentric relief portion 30 has a width WI of less than about 0.25 mm, an inner eccentric relief angle β of less than about 5 degrees, and a surface finish of less than about 0.15 microns Ra.
[0044] It has been found that the above-described inner eccentric relief 30 and outer eccentric relief 32 produce a high quality finished cutting edge 24 with extremely low damage. This is because the inner eccentric relief 30 and outer eccentric relief 32 are ground and the inner eccentric relief 30 is polished. In addition, the design of the relatively low inner relief angle β for the inner eccentric relief 30 still provides some process damping in machining non-ferrous materials (such as aluminum, etc.).
[0045] Patents and publications mentioned herein are hereby incorporated by reference.
[0046] Although presently preferred embodiments have been described, the invention may be otherwise embodied within the scope of the appended claims.
[0047] Parts List
[0048] 10 Rotary cutting tool
[0049] 12 Handle
[0050] 14 Cutting section
[0051] 16 Cutting tip
[0052] 18 Blade
[0053] 20 grooves
[0054] 22 Relief surface
[0055] 24 Cutting Edges
[0056] 30 Internal eccentric clearance
[0057] 32 External eccentric clearance
[0058] A Central longitudinal axis
[0059] HA Helix Angle
[0060] WI width (internal eccentric clearance) WO width (external eccentric clearance)
Claims
1. A rotary cutting tool (10), comprising: A handle portion (12); as well as a cutting portion (14) extending from the shank portion (12) to a cutting tip (16), the cutting portion (14) having a plurality of blades (18) separated by grooves (20), each of the blades (18) including a relief surface (22) and a radial cutting edge (24) formed at an intersection between a respective groove (20) and the relief surface (22), The relief surface (22) includes an inner eccentric relief portion (30) proximate to the radial cutting edge (24) and an outer eccentric relief portion (32) proximate to the inner eccentric relief portion (30).
2. The rotary cutting tool (10) of claim 1, wherein the inner eccentric relief portion (30) is formed with an inner eccentric relief angle β of less than about 5 degrees, and wherein the outer eccentric relief portion (32) is formed with an outer eccentric relief angle β between about 5 degrees and about 15 degrees.
3. The rotary cutting tool (10) according to claim 1, wherein the inner eccentric gap portion (30) is formed with a width WI, and the outer eccentric gap portion (32) is formed with a width WO, and wherein the width WO of the outer eccentric gap portion (32) is at least twice the width WI of the inner eccentric gap portion (30).
4. The rotary cutting tool (10) of claim 3, wherein the width WO of the outer eccentric relief portion (32) is approximately four times the width WI of the inner eccentric relief portion (30).
5. The rotary cutting tool (10) of claim 1, wherein the inner eccentric relief portion (30) is formed with a surface finish of less than 0.15 microns Ra.
6. The rotary cutting tool (10) of claim 1, wherein the rotary cutting tool (10) comprises a solid end mill.
7. The rotary cutting tool (10) of claim 1, wherein each blade (18) forms a helix angle HA with respect to the central longitudinal axis A of between about 25 degrees and about 50 degrees.
8. A rotary cutting tool (10), comprising: A handle portion (12); as well as a cutting portion (14) extending from the shank portion (12) to a cutting tip (16), the cutting portion (14) having a plurality of blades (18) separated by grooves (20), each of the blades (18) including a relief surface (22) and a radial cutting edge (24) formed at an intersection between a respective groove (20) and the relief surface (22), wherein the relief surface (22) includes an inner eccentric relief portion (30) proximate to the radial cutting edge (24) and an outer eccentric relief portion (32) proximate to the inner eccentric relief portion (30), wherein the inner eccentric relief portion (30) is formed with an inner eccentric relief angle β of less than about 5 degrees, and wherein the outer eccentric relief portion (32) is formed with an outer eccentric relief angle β between about 5 degrees and about 15 degrees, and The inner eccentric relief portion (30) is formed with a surface finish of less than 0.15 microns Ra.
9. The rotary cutting tool (10) according to claim 8, wherein the inner eccentric relief portion (30) is formed with a width WI, and the outer eccentric relief portion (32) is formed with a width WO, and wherein the width WO of the outer eccentric relief portion (32) is at least twice the width WI of the inner eccentric relief portion (30).
10. The rotary cutting tool (10) of claim 9, wherein the width WO of the outer eccentric relief (32) is approximately four times the width WI of the inner eccentric relief (30).
11. The rotary cutting tool (10) of claim 8, wherein the rotary cutting tool (10) comprises a solid end mill.
12. The rotary cutting tool (10) of claim 8, wherein each blade (18) forms a helix angle HA with respect to the central longitudinal axis A of between about 25 degrees and about 50 degrees.
13. A method of manufacturing a rotary cutting tool (10) comprising a handle portion (12) and a cutting portion (14), the cutting portion (14) having a plurality of blades (18) separated by grooves (20), each of the blades (18) comprising a relief surface (22) and a radial cutting edge (24), the radial cutting edge being formed at the intersection between the respective groove (20) and the relief surface (22), the relief surface (22) comprising an inner eccentric relief portion (30) proximate the radial cutting edge (24) and an outer eccentric relief portion (32) proximate the inner eccentric relief portion (30), the method comprising: grinding the cylindrical blank using a grinding wheel to form a groove (20) and a radial cutting edge (24); grinding an outer relief surface (32) behind and adjacent the radial cutting edge (24) using a grinding wheel, the outer relief surface having an outer eccentric relief angle β between about 5 degrees and about 15 degrees; as well as An inner relief surface (30) is formed by grinding and polishing a portion of the outer eccentric relief surface (32) proximate the radial cutting edge (24) using a fine grit grinding wheel, the inner relief surface having an inner eccentric relief angle β of less than about 5 degrees.