End mills and inserts

Abstract

The present invention provides an end mill and its blade. The blade extends from the rear end to the front end along the rotation axis, and includes an end face, a front angle face and a cutting edge; the end face is located at the front end side of the blade and has a back angle face; the front angle face is located in front of the back angle face in the rotation direction; the cutting edge is located between the back angle face and the front angle face and has a passivation face; the cutting edge extends from the center side of the rotation axis to the outer peripheral side of the blade as it moves away from the front end side; the passivation face has a first portion and a second portion closer to the outer peripheral side than the first portion; the width of the second portion is greater than the width of the first portion. The present invention can improve the cutting performance of the blade on the center side and improve the surface processing quality of the workpiece.

Description

Technical Field

[0001] The invention relates to a workpiece processing tool, in particular to an end milling cutter and a blade thereof. Background Art

[0002] Chinese invention patent application CN109862983A discloses a ball end mill, wherein the cutting blade has an arc-shaped cutting edge protruding toward the outer peripheral side of the front end of the cutting blade, and a chamfer is formed in the range of the radial angle of at least 30° in the tip of the arc-shaped cutting edge. Thus, when a high-hardness workpiece is processed efficiently, the tip strength near the front end of the arc-shaped cutting edge can be fully ensured, and chipping can be prevented.

[0003] For finishing with high requirements on workpiece surface quality, or in processing situations with relatively small cutting depth and feed, the chamfer on the cutting edge can easily produce a movement that applies extrusion to the workpiece, resulting in poor cutting performance and high cutting resistance, which can easily cause the tool to slip and cause scraping marks on the workpiece surface, affecting the surface quality of the workpiece. Summary of the invention

[0004] An object of the present invention is to provide a blade for an end mill to improve the surface quality of a machined workpiece.

[0005] Another object of the present invention is to provide an end mill having the above-mentioned insert.

[0006] In order to solve the technical problem, the present invention adopts the following technical solution:

[0007] According to one aspect of the present invention, the present invention provides a blade for an end mill, which extends from the rear end to the front end along the rotation axis, and includes an end face, a front angle surface and a cutting edge; the end face is located on the front end side of the blade and has a rear angle surface; the front angle surface is located in front of the rear angle surface in the rotation direction; the cutting edge is located between the rear angle surface and the front angle surface and has a passivation surface; the cutting edge extends from the center side of the rotation axis to the outer peripheral side of the blade as it moves away from the front end side; the passivation surface has a first portion and a second portion closer to the outer peripheral side than the first portion; the width of the second portion is greater than the width of the first portion.

[0008] According to another aspect of the present invention, there is provided an end mill, comprising a shank extending forward and backward along a rotating axis and a blade as described above located at the front end of the shank, wherein the blade is detachably mounted on the shank, or the blade and the shank are an integral structure.

[0009] It can be seen from the technical solution that the present invention has at least the following advantages and positive effects: in the blade of the end mill provided by the present invention, the cutting edge has a passivation surface, and the first part of the passivation surface closer to the center side has a smaller width, so that the part of the cutting edge closer to the center side is sharper and has better cutting performance, and has lower cutting resistance during processing, which is conducive to the part of the cutting edge closer to the center side with a lower cutting speed to cut more smoothly and smoothly, thereby improving the surface quality of the workpiece. The second part closer to the peripheral side has a larger width, so that the part of the cutting edge closer to the peripheral side has better strength, which is more conducive to maintaining a relatively large cutting amount and cutting speed working state, thereby increasing the service life of the blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a three-dimensional structural schematic diagram of an embodiment of an end mill of the present invention.

[0011] Figure 2 yes Figure 1 Schematic diagram of the three-dimensional structure of the blade of the neutral milling cutter.

[0012] Figure 3 yes Figure 2 Front view of .

[0013] Figure 4 yes Figure 2 End view of the .

[0014] Figures 5 to 8 yes Figure 3 The cross-section at DD is perpendicular to the cutting edge. Figures 5 to 8 Several different structural forms of the passivation surface are illustrated respectively.

[0015] Fig. 9 is Figure 3 Schematic diagram of the location of selected features on the view.

[0016] Fig.10 yes Fig. 9 Cross-sectional view perpendicular to the cutting edge at EE.

[0017] Fig.11 yes Fig. 9 Cross-sectional view perpendicular to the cutting edge at FF.

[0018] Fig.12 yes Fig. 9 Cross-sectional view perpendicular to the cutting edge at GG in the middle.

[0019] Fig.13 It is a schematic diagram of the processing process of the end mill of the present invention.

[0020] Fig.14 yes Fig.13 Schematic diagram of the state of the middle blade when cutting the workpiece.

[0021] Figures 15 to 17 It is a front view of the blade shape of other embodiments of the present invention.

[0022] The description of the reference numerals is as follows: 10, end mill; 1 / 1a / 1b / 1c, blade; 2, tool holder; 21, tool jaw; 3, fastening screw; 11, end face; 111, back angle face; 1111, primary back angle face; 1112, secondary back angle face; 12, front angle face; 13 / 13a / 13b / 13c, cutting edge; 40, workpiece. DETAILED DESCRIPTION

[0023] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations therein are essentially used for illustration purposes rather than for limiting the present invention.

[0024] The present invention provides an end mill and a blade thereof, wherein the end mill can be a ball end mill, a circular arc end mill, etc. The blade of the end mill is located at the front end side of the end mill and has a plurality of cutting edges in the shape of a plane curve or a space curve. When in use, the end mill rotates around a rotation axis, and each cutting edge performs cutting processing on a workpiece, thereby processing a spherical surface or a space curved surface on the workpiece.

[0025] Figure 1 The structure of an end mill 10 according to an embodiment of the present invention is illustrated. The end mill 10 comprises a shank 2 and a blade 1 located at the front end of the shank 2. In this embodiment, the end mill 10 is a ball end mill.

[0026] The handle 2 extends from the rear end to the front end along the rotation axis L, and two spaced jaws 21 are provided at the front end of the handle 2. The blade 1 is installed between the two jaws 21 and fixed by a fastening screw 3 that passes through the jaws 21 and the blade 1.

[0027] In this structure, the blade 1 is detachably mounted on the handle 2. In other embodiments, the blade 1 and the handle 2 may also be an integral structure.

[0028] The present invention optimizes the cutting edge structure of the blade 1, and the following is a specific description of the structure of the detachable blade 1. The structure related to the cutting edge is also applicable to the blade 1 with an integral structure with the handle 2.

[0029] Figure 2 A three-dimensional diagram of the blade 1 of this embodiment is shown. Figure 3 A front view of the blade 1 is shown. Figure 4 A tip end view of the blade 1 is shown.

[0030] The blade 1 extends from the rear end to the front end along the rotation axis L, and has an end face 11 located on the front end side of the blade 1 and having a rear angle face 111, a front angle face 12 located in front of the rotation direction of the rear angle face 111, and a cutting edge 13 located between the rear angle face 111 and the front angle face 12 and having a passivated surface.

[0031] To facilitate the installation of the blade 1 and the handle 2, the blade 1 of this embodiment also has two opposite restraining surfaces 14 and a through hole 15 passing through the two restraining surfaces 14. The two restraining surfaces 14 are used to fit with the two blade jaws 21 respectively, and the through hole 15 is used to connect and cooperate with the fastening screw 3.

[0032] The end face 11 is located between the two restraining faces 14. The back angle surface 111 of the end face 11 is located behind the cutting edge 13 in the rotation direction and connected between the cutting edge 13 and the restraining face 14. Specifically, the back angle surface 111 includes a main back angle surface 1111 and a secondary back angle surface 1112, the main back angle surface 1111 is connected to the cutting edge 13, and the secondary back angle surface 1112 is connected to the restraining face 14.

[0033] The rake face 12 is located in front of the cutting edge 13 in the rotation direction, and a chip discharge groove (not numbered in the figure) is formed between the rake face 12 and the restraining face 14 for discharging chips generated when the cutting edge 13 cuts the workpiece.

[0034] The cutting edge 13 extends from the center side of the rotation axis L to the outer peripheral side of the blade 1 as it moves away from the front end side of the blade 1. In this embodiment, the cutting edge 13 is in the shape of a spatial arc. The cutting edges 13 are arranged to be two centrally symmetrical with respect to the rotation axis L. From the front view, the projections of the two cutting edges 13 are located on the same circle. When the blade 1 rotates around the rotation axis L, the contour of the cutting edge 13 forms a spherical shape, so as to machine a spherical surface on the workpiece.

[0035] The cutting edge 13 may be formed into a passivation surface according to relevant passivation means in the art, and the passivation surface also extends from the center side to the outer peripheral side along the extension direction of the cutting edge 13. Figures 5 to 8 According to different passivation methods, the passivation surface can be a plane or a convex surface. The passivation surface of the cutting edge 13 is connected to the front angle surface 12 and the main back angle surface 1111 respectively.

[0036] Figure 5 As shown, the passivation surface of the cutting edge 13 is an arc surface, which is tangent to the front angle surface 12 and the main back angle surface 1111 respectively, and can be formed by chamfering, and the radius R of the arc of the entire passivation surface remains consistent.

[0037] Figure 6 As shown, the passivation surface of the cutting edge 13 is flat, which can be called a chamfer. The passivation surface and the front angle surface 12 and the main back angle surface 1111 have angles respectively, and the two angles can be the same or different.

[0038] Figure 7As shown, the passivation surface of the cutting edge 13 is two smoothly connected arc surfaces, the radius of the arc surface connected to the front angle surface 12 is R1, and the radius of the arc surface connected to the main back angle surface 1111 is R2, R1>R2.

[0039] Figure 8 As shown, the passivation surface of the cutting edge 13 is also two smoothly connected arc surfaces, the radius of the arc surface connected to the front angle surface 12 is R3, the radius of the arc surface connected to the main back angle surface 1111 is R4, and R3<R4.

[0040] In practical applications, the specific shapes of the passivation surface are not limited to the four types listed above, and can be set according to needs, and will not be listed one by one.

[0041] In some embodiments not shown in the figure, the surface of the blade 1 can be plated to form a coating, in which case the passivation surface is correspondingly formed on the coating. The coating can be deposited by physical vapor deposition or chemical vapor deposition, and the specific method can refer to the relevant technology. The thickness of the coating can be set according to the needs, and the thickness and shape of the coating can be different at different positions of the cutting edge 13, so that passivation surfaces of different sizes can be formed at the coatings at different positions. The strength of the blade 1 can also be increased by coating, which is conducive to reducing the size of the passivation surface on the basis of ensuring the strength of the blade 1, thereby improving the cutting performance of the cutting edge 13.

[0042] Regardless of the passivation method used, according to an embodiment of the present invention, along the extension direction of the cutting edge 13, the passivation surface has a first portion and a second portion located on the outer peripheral side of the first portion, and the width of the second portion is greater than the width of the first portion.

[0043] It is understandable that the first and second portions do not represent fixed positions in the extending direction of the cutting edge 13, but can be selected dynamically. Based on the width relationship between the first and second portions, it can be inferred that on the cutting edge 13, the width of the passivation surface near the center side is smaller than the width of the passivation surface near the periphery side.

[0044] In other words, the cutting edge 13 near the center is relatively sharp, while the cutting edge 13 near the periphery is relatively blunt. Therefore, the portion of the cutting edge 13 near the center can more easily cut into the workpiece, has better cutting performance, and has lower cutting resistance during processing, which is conducive to the portion of the cutting edge 13 near the center with a lower cutting speed to cut more smoothly and steadily, thereby improving the surface quality of the workpiece. The second portion near the periphery has a larger width, so that the portion of the cutting edge 13 near the periphery has better strength, which is more conducive to maintaining a relatively large cutting amount and cutting speed working state, thereby increasing the service life of the blade 1.

[0045] The width of the passivation surface of a certain location of the cutting edge 13 refers to the distance between two points where the cutting edge 13 is connected to the front angle surface 12 and the rear angle surface 111 respectively.

[0046] exist Figures 5 to 8 In the cross section shown orthogonal to the cutting edge 13, the width of the passivation surface is shown in the front view ( Figure 3 In addition, if the view from the top end ( Figure 4 From the axonometric view ( Figure 2 From the perspective of the viewing direction shown), it can be represented as S.

[0047] The cross section orthogonal to the cutting edge 13 refers to an orthogonal plane perpendicular to a tangent line of the cutting edge 13 passing through a certain point on the cutting edge 13 .

[0048] Regardless of whether the width of the passivation surface is evaluated by the above-mentioned A, B or S, the above-mentioned width size relationship between the first portion and the second portion holds true as the cutting edge 13 extends.

[0049] Preferably, the width of the passivation surface increases gradually from the first part to the second part, thereby being consistent with the trend that the cutting speed of the cutting edge 13 increases gradually from the first part to the second part, so that the cutting performance of each part of the cutting edge 13 is more uniform.

[0050] In some embodiments, the cutting edge 13 has a passivation surface in the entire blade length extending direction from the center side to the peripheral side, improving the overall fracture resistance of the cutting edge 13. Furthermore, the width of the passivation surface gradually increases from the end of the center side to the end of the peripheral side.

[0051] The end of the passivation surface on the central side has the smallest width, and the end of the passivation surface on the peripheral side has the largest width, and the largest width = (1.5-5) × the smallest width. Thus, a better balance between cutting performance and strength can be achieved.

[0052] In some embodiments, the passivation surface may be formed only at a portion of the extended length of the cutting edge 13, for example, only on a portion of the cutting edge 13 close to the center side, or on a portion of the cutting edge 13 in the middle area where the cutting edge 13 is frequently used, and so on.

[0053] In addition, in some embodiments, the passivation surface may further include a third portion located closer to the center than the first portion, and the width of the third portion is the same as the width of the first portion.

[0054] Furthermore, the passivation surface may further include a fourth portion located closer to the outer circumference than the second portion, and the width of the second portion and the width of the fourth portion may be the same.

[0055] That is to say, there may be a partial area with a constant passivation surface size on the cutting edge 13, and there may be multiple areas with a constant passivation surface size. In an extended manner, over the entire extended length of the cutting edge 13, areas with gradually increasing passivation surface width and areas with a constant passivation surface width may alternately exist on the cutting edge 13.

[0056] See also Fig. 9 In one embodiment, the passivation surface is an arc surface, and three positions E, F, and G are taken in sequence along the extension direction of the cutting edge 13 from the center side to the outer peripheral side, among which the radiation angle of the cutting edge 13 at E is 20°, the radiation angle of the cutting edge 13 at F is 50°, and the radiation angle of the cutting edge 13 at G is 75°.

[0057] The radiation angle means: take point C on the rotation axis L whose distance from the tip is equal to the maximum machining radius of the cutting edge 13, take the projection line of the line connecting point C and any point on the cutting edge 13 on the reference plane, and the angle between the projection line and the rotation axis L is the radiation angle.

[0058] For the ball end mill shown in this embodiment, Fig. 9 In the viewing direction, point C is exactly at the center of the through hole 15, and the reference plane is the restraining surface 14 of the blade 1.

[0059] from Figures 10 to 12 The radii of the passivation surface are R E , R F , R G , the relationship between the radii of these passivation surfaces is: R E <R F <R G For example, R E Can be 0.02mm, R F 0.025mm, R G Correspondingly, the radius of the passivation surface at the end of the center side is preferably 0.005mm to 0.015mm. As for the cutting edge 13, the radius of the passivation surface in the entire extension direction is preferably between 0.005mm and 0.05mm, so as to balance the cutting performance and strength.

[0060] For the passivated surface using other passivation methods, the numerical range of the width of the passivated surface can be reasonably adjusted with reference to the above-mentioned arc surface radius range.

[0061] Fig.13 The processing state of the end mill 10 is shown. The end mill 10 moves in the horizontal direction, and the single-edge feed is Fz. W1 shows the position of the first cutting edge 13 of the blade 1 of the end mill 10 when cutting, and W2 shows the position of the next cutting edge 13 of the blade 1 when cutting.

[0062] The thickness of the workpiece 40 actually cut by the cutting edge 13 at a certain position is H, which is Fig.13 It can be seen that the relationship between H and Fz depends on the cutting angle, that is, the angle between the tangent line of the cutting edge 13 and the horizontal plane at the contact point between the cutting edge 13 and the workpiece 40, which is also equal to the radiation angle of the cutting edge 13 at this position. According to the trigonometric function relationship, H = Fz × sinθ.

[0063] Fig.14 The cross-sectional structure of the cutting edge 13 of the blade 1 when the end mill 10 is in contact with the workpiece 40 is shown. During cutting, the cutting edge 13 and the front angle surface 12 act together on the workpiece 40 to cut the workpiece 40. The cutting thickness is Fig.13 The width of the contact between the passivation surface of the cutting edge 13 and the workpiece 40 is A (refer to Figures 5 to 8 ).

[0064] Under the conditions of different feed angles θ, different feed Fz, and different passivation surface widths A, the following relationship table is obtained.

[0065]

[0066] According to the shape of the blade 1 in contact with the workpiece 40, the cutting resistance within the range of the passivation surface width A is determined by the structure of the passivation surface. Within this range, the passivation surface of the cutting edge 13 is equivalent to a very small rake angle (negative rake angle with a large absolute value), the cutting resistance is large, and the cutting performance of the cutting edge 13 is very poor. In the range outside the passivation surface, the rake surface 12 is in contact with the workpiece 40, and the cutting resistance depends on the rake surface 12. In this range, the rake angle is relatively large, the cutting resistance is relatively small, and the cutting performance is relatively better.

[0067] In general, the smaller the A / H value is, the better the cutting performance is and the lower the cutting resistance is. The larger the A / H value is, the greater the influence of the passivation surface is, the worse the cutting performance of the cutting edge 13 is, the greater the cutting resistance is, and it is easy to cause scratches on the surface of the workpiece 40, affecting the surface quality of the workpiece.

[0068] According to the data in the above table, under the conditions of the same single-edge feed Fz and the same passivation surface width A, comparing the two positions where the feed angle θ is 20° and the feed angle θ is 47°, at the position where θ is 20° which is relatively closer to the center side, A / H is greater, indicating that the cutting performance of the cutting edge 13 closer to the center side will be worse. At the same position of the cutting edge 13, with the same passivation surface width A and the same feed angle θ, the smaller the single-edge feed Fz, the larger the A / H, indicating that when the single-edge feed is smaller, the cutting performance will be worse, and the influence of the passivation surface will be greater. Under the processing conditions of a small feed angle and a small feed, reducing the passivation surface width of the cutting edge 13 is more meaningful for improving the cutting performance.

[0069] In combination with the above-mentioned scheme of the present invention, for the first part close to the center side, the passivation surface has a relatively small width, so that the A / H value can be reduced, the cutting performance of the center side part is effectively improved, and the surface processing quality of the workpiece is improved, which is particularly suitable for situations with small feed angles and low feeds.

[0070] As for the second part close to the outer peripheral side, the cutting speed and cutting amount of the cutting edge 13 are relatively larger. At this time, the cutting resistance is mainly determined by the front angle surface 12. Properly increasing the width of the passivation surface has little effect on the cutting resistance. On the contrary, it can increase the strength of the cutting edge 13, which is more in line with the working condition requirements of the cutting edge 13.

[0071] See also Figures 15 to 17 In some other embodiments, the end mill of the present invention may also be an arc end mill, and the cutting edge of the blade is in a planar curve shape.

[0072] Fig.15 The insert 1a of the arc angle end mill is shown. The corner of the insert 1a is provided with an arc-shaped cutting edge 13a. Fig.16 In the end mill insert 1 b shown, the cutting edge 13 b includes an arc segment close to the center side and a straight line segment extending rearwardly from the rear end of the arc segment toward the outer peripheral side. Fig.17 In the end mill insert 1c shown, the cutting edge 13c includes a plurality of smoothly connected circular arcs with different radii.

[0073] In the above-mentioned end mill blades, the cutting edges have different extension shapes, and are not limited to the several shapes listed here, but generally speaking, the cutting edges extend from the center side to the peripheral side in the direction away from the front end. On these cutting edges, the passivation surface can also be set in the same way as the above-mentioned ball-end mill blade, and the width of the passivation surface can be set according to the above-mentioned change rules to improve the cutting performance of the center side of the cutting edge, thereby improving the surface processing quality of the workpiece. No detailed introduction will be given here.

[0074] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A blade of an end mill, which extends from a rear end to a front end along a rotation axis, comprising: An end surface located at the front end side of the blade and having a back angle surface; A front angle surface corresponding to the front angle surface in the rotation direction of the rear angle surface; and A cutting edge located between the rear angle surface and the front angle surface and having a blunt surface; The cutting edge extends from the center side of the rotating shaft toward the outer peripheral side of the blade as it moves away from the front end side; The passivation surface has a first portion and a second portion closer to the outer circumference than the first portion; The width of the second portion is greater than the width of the first portion, The back angle surface has a main back angle surface connected to the cutting edge, The passivation surface is two arc surfaces connected smoothly, and the radius (R3) of the arc surface connected to the front angle surface is smaller than the radius (R4) of the arc surface connected to the main rear angle surface.

2. The blade according to claim 1, characterized in that The width of the passivation surface gradually increases from the first portion to the second portion.

3. The blade according to claim 2, characterized in that The width of the passivation surface gradually increases from the end portion on the center side toward the end portion on the outer peripheral side.

4. The blade according to claim 3, characterized in that The passivation surface has a minimum width at the end portion on the center side, and has a maximum width at the end portion on the outer peripheral side, and the maximum width=(1.5 to 5)×the minimum width.

5. The blade according to claim 1, characterized in that The passivation surface further includes a third portion located closer to the center than the first portion, and a width of the third portion is the same as a width of the first portion.

6. The blade according to claim 1, characterized in that The passivation surface further includes a fourth portion located closer to the outer circumference than the second portion, and the second portion has the same width as the fourth portion.

7. The blade according to claim 1, characterized in that The surface of the blade has a coating, and the passivation surface is formed on the coating.

8. The blade according to claim 1, characterized in that The cutting edge is in the shape of a plane curve or a space curve.

9. An end mill, comprising a shank extending forward and backward along a rotating axis and a blade as claimed in any one of claims 1 to 8 located at the front end of the shank, wherein the blade is detachably mounted on the shank, or the blade and the shank are an integral structure.

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