JPH04102716U - end mill - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain an end mill that can reduce cutting resistance while maintaining tool rigidity and perform cutting with higher efficiency than conventional ones. [Structure] The peripheral surface 11a of the cutting edge portion 11 of the end mill has a concave curved surface 14 that draws a concave curve concave toward the center in the radial direction of the cutting edge portion 11 in a cross section perpendicular to the tool axis, and Convex curved surfaces 15 that draw convex curves protruding outward are arranged alternately in the circumferential direction of the tool, and the convex curved surfaces 15 follow the rotation circle C, which is the rotation locus of the outer peripheral cutting edge 12, in a cross section perpendicular to the tool axis. One end 15a is made to match, and
As it goes from the one end 15a to the other end 15b, the tool is retreated toward the center in the radial direction while gradually drawing an arc with a larger curvature than the rotation circle C. The outer peripheral cutting edge 12 is defined as the outer peripheral cutting edge 12 .

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea is suitable for deep groove machining of precision parts such as molds, etc., and has high rigidity. The present invention relates to an end mill that can perform high-precision machining with ease.

0002

[Conventional technology]

Used as an end mill that requires high rigidity and high precision machining. In some cases, deep groove machining is performed. The end mill used for deep groove machining like this For example, when the depth of cut into the workpiece is at a taper angle of 5°, it is perpendicular to the slope of the groove. It is extremely small, about 0.004 mm in the direction (about 0.1 mm in the depth direction of the groove). Since the value is set to a low value, fewer chips are generated, and the chip evacuation grooves are relatively small. Although it has the design advantage of being small and sufficient, the characteristics of deep groove machining make it difficult to The cutting edge is longer and narrower than that of a hand mill, so it is required that the tool rigidity be as high as possible. It will be done. The end mill shown in Figs. 8 to 11 was disclosed in Japanese Utility Model Application No. 161615/1983. This is an example of an end mill that takes into consideration the above characteristics.

0003 The tapered end mill shown in these figures has a tip at one end of the cylindrical shank 1. A tapered cutting edge 2 that becomes thinner as it approaches is integrally formed. On the outer periphery, a plurality of spiral peripheral cutting edges 3 have a conical rotation locus around the tool axis. It is formed to draw an R, and a bottom edge 4 is further formed at the tip of the cutting edge 2. The cutting edge 2 has a cross section of a regular hexagonal shape (Fig. 10) or a regular triangular shape (Fig. 10). It is formed into a regular polygon as shown in FIG. It is said that And, the total length of these peripheral cutting edges 3 at the tip of the peripheral cutting edge 3 is It is said to be 6 times or more the rotation diameter d. In addition, the cutting edge is a straight end mill with a cylindrical shape centered on the tool axis. 12 and 13, the cross-sectional shape is exactly the same as that in FIG. 10. There are things that have

0004 These end mills do not have grooves for chip evacuation on the outer periphery of the tool. Therefore, the cross-sectional area of the tool is large, and the cutting edge angle θ of the peripheral cutting edge 3 is also large. It has higher rigidity than end mills and avoids chattering etc. in deep groove machining as described above. Stable processing can be performed.

[0005]

[Problem that the idea aims to solve]

By the way, in the conventional end mill as described above, the cross section of the cutting edge 2 is a regular polygon. Because it is shaped like It is abbreviated as. ) γ is determined by the cross-sectional shape of the cutting edge 2, and the cutting edge 2 has a regular hexagonal cross-section. -60° for square shape, -45° for square shape, outer cutting edge 3 is at its maximum. Even in the case of an equilateral triangular shape in which the It will be greatly biased towards the corner side. For this reason, cutting resistance may increase and sharpness may deteriorate. The drawback was that it was large.

[0006] In addition, in the above-mentioned end mill, the number of corners of the cutting edge 2, that is, the number of edges of the outer cutting edge 3 is The larger the number of teeth, the larger the feed amount per rotation of the tool can be set, which improves machining efficiency. This is advantageous for improving tool rigidity, and is also effective in improving rigidity by increasing the cross-sectional area of the tool. However, as the number of peripheral cutting edges 3 increases, the rake angle γ becomes more negative. Due to the increase in cutting resistance, the practical limit is a regular hexagonal cross section; therefore, It was not possible to improve machining efficiency by increasing the number of teeth.

[0007] Furthermore, the clearance angle (hereinafter abbreviated as relief angle) in the axis-perpendicular cross section of the outer peripheral cutting edge 3. ) α is also 30° for a regular hexagon, 45° for a square, and 45° for an equilateral triangle. It is determined by the number of angles of the cutting edge 2, such as 60° at the cutting edge, so depending on the cutting conditions etc. There was also a drawback that it was not possible to set the optimum relief angle α accordingly. This idea was developed against this background, and allows cutting while maintaining tool rigidity. An end mill that reduces cutting force and allows for more efficient cutting than conventional methods. The purpose is to provide

[0008]

[Means to solve the problem]

The end mill of this invention has a cutting edge formed at one end of the shaft-shaped shank. This is an end mill with multiple peripheral cutting edges formed around the tool axis on the outer periphery of this cutting edge. The circumferential surface of the cutting edge is located in the radial direction of the cutting edge in a cross section perpendicular to the tool axis. A concave curved surface that recesses toward the core, and a convex curve that protrudes outward in the radial direction of the cutting edge. Convex curved surfaces to be drawn are arranged alternately in the circumferential direction of the tool, and the convex curved surfaces are In the cross section perpendicular to the tool axis, one end coincides with the rotation circle that is the rotation locus of the outer cutting edge. At the same time, as it goes from one end to the other end, it gradually becomes more than the rotation circle. These convex curved surfaces The intersecting ridgeline between the one end and the concave curved surface is the outer peripheral cutting edge. . The end mill has the outer cutting edge that draws a cylindrical rotation locus centered on the tool axis. Even if the straight end mill is shaped like A circular cone (truncated cone) whose diameter is centered on the tool axis and gradually decreases in diameter toward the tip. A tapered end mill formed to draw a rolling locus may also be used.

[0009]

[Effect]

According to the above configuration, the concave curved surface is depressed toward the center in the tool radial direction with respect to the outer peripheral cutting edge. Since it is a wedge face, the angle of inclination of the tangent passing through the outer cutting edge of the concave curved surface with respect to the tool radius direction is the rake angle of the peripheral cutting edge. In addition, the convex curved surface is As it moves toward This becomes the flank of the outer peripheral cutting edge, so the tangent at one end of this convex curved surface and the above rotation trajectory The angle between the surface and the tangent on the outer cutting edge is the clearance angle.

0010 Since the rake angle is determined by the slope of the tangent to the concave surface, By changing the shape such as the curvature of the curved surface and the position of the center of curvature, the number of teeth on the peripheral cutting edge can be restricted. The size of the rake angle can be set arbitrarily without being affected.

[0011] Similarly, since the relief angle is determined by the slope of the tangent to the convex curved surface, The relief angle can be arbitrarily set by changing the curvature of the surface.

0012 In addition, the cross-sectional area of the cutting edge is determined by the machining of the concave curved surface and the convex curved surface from the rotation trajectory surface. The shape of these concave and convex surfaces changes depending on the amount of retraction toward the center in the radial direction of the tool. By setting the shape appropriately, it is possible to prevent a decrease in the tool cross-sectional area and maintain tool rigidity. can be obtained.

[0013]

【Example】

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 4. As shown in FIGS. 1 and 2, the taper end mill of this embodiment has a shaft-shaped shaft. A tapered cutting edge 11 that becomes thinner toward the tip is formed at one end of the ink 10. , a plurality of peripheral cutting blades twisted spirally around the tool axis O are provided on the outer periphery of the cutting edge portion 11. 12 is formed so as to draw one virtual conical surface C around the tool axis O, and is further cut. A plurality of bottom blades 13 are formed at the tip of the blade part 11 and is generally configured.

[0014] As shown in FIGS. 1 to 3, the circumferential surface 11a of the cutting edge 11 is arranged in a cross section perpendicular to the tool axis. A concave curved surface 14 that draws a concave curve concave toward the tool axis P0 side, and a concave curved surface 14 that curves toward the tool outer circumference side. Convex curved surfaces 15 that draw convex curves that protrude are arranged alternately in the circumferential direction of the tool. has been done.

[0015] Here, in the cross section perpendicular to the tool axis, the convex curved surface 15 has one end 15a above the It is made to coincide with the virtual conical surface C, and from the one end 15a to the other end 15b. Draw a convex arc that gradually retreats from the virtual conical surface C toward the tool axis P0 as The curvature (1/R1) is similar to the curvature (1/R0) of the virtual conical surface C. There are also large rules.

[0016] Further, the concave curved surface 14 is smoothly continuous with the other end 15b of the convex curved surface 15. Both are formed to draw a concave arc that intersects one end 15a of the adjacent convex curved surface 15. The curvature (1/r1) is larger than the curvature (1/R1) of the convex curved surface 15. being admired.

[0017] The concave curved surface 14 and the convex curved surface 15 are both at the tip of the cutting edge 11. Twisted surface shape that gradually twists clockwise around the tool axis O as it moves toward the proximal end. As a result, the intersection ridge line between one end 15a of each convex curved surface 15 and the concave curved surface 14 The portion is the outer peripheral cutting edge 12 described above. Therefore, the taper end mill is By rotating in the direction of the middle arrow X, the concave curved surface 14 and the convex curved surface 15 are respectively This becomes a rake face and a flank face for the outer peripheral cutting edge 12, and along with this, the tool axis P 0 and the outer cutting edge 12, and the tangent m2 passing through the outer cutting edge 12 of the concave curved surface 14. The angle γ formed by The angle formed by the tangent m3 at 2 and the tangent m4 passing through the outer peripheral cutting edge 12 of the virtual conical surface C α is the clearance angle of the outer peripheral cutting edge 12.

[0018] In addition, as shown in FIGS. 1 and 2, the tip of the cutting edge 11 has a Two grooves 17 are formed that open on the tip surface 11b and the peripheral surface 11a, and these grooves The ridgeline between the wall surface 17 and the tip surface 11b is the bottom blade 13.

[0019] Note that the total length L and taper angle φ of the cutting edge portion 11 are set according to the shape of the groove to be cut. However, the total length L is 6d or more with respect to the rotational diameter d of the tip of the outer cutting edge 12, and The taper angle φ is 5°.

[0020] Next, the operation of the taper end mill configured as described above will be explained. In the tapered end mill of this embodiment, the peripheral surface 11a of the cutting edge 11 is a concave curved surface. 14 and a convex curved surface 15, these curved surfaces 14 , 15 shapes such as curvature can be changed individually, and these changes Therefore, the rake angle γ and clearance angle α are not limited to the number of teeth of the outer peripheral cutting edge 12, It can be set to an appropriate value depending on processing conditions, etc.

[0021] That is, the rake angle γ and the clearance angle α are the outer circumferences of the concave curved surface 14 and the convex curved surface 15. It is determined by the directions of tangents m2 and m3 passing through the cutting edge 12, and these tangents m2 , the direction of m3 is the curvature (1/r1), the magnitude of (1/R1), and the positions of the centers of curvature P1 and P2. For example, as shown in part A of FIG. 4, the curvature (1 /r1) with a smaller curve while taking care not to change the position of the outer cutting edge 12. If the rake angle γ1 is changed to the ratio (1/r2), the rake angle γ1 approaches the square side and the rake The angle changes to γ2.

[0022] In addition, the curvature (1/R1) of the convex curved surface 15 is adjusted so that the position of the outer peripheral cutting edge 12 does not change. If the curvature is changed to a larger curvature (1/R2) while taking into consideration the relief angle α1 will change to a larger clearance angle α2.

[0023] Furthermore, even when the curvatures of these curved surfaces 14 and 15 are not changed, for example, as shown in FIG. As shown in part B, the position of the outer cutting edge 12 changes the curvature center position P1 of the concave curved surface 14. If the position P3 is changed to a position closer to the center in the radial direction while taking care not to cause Rake angle γ1 changes to rake angle γ3, which is closer to a regular angle.

[0024] As described above, according to the taper end mill of this embodiment, the curvature of the concave curved surface 14, etc. can be adjusted appropriately. By changing the rake angle γ of the peripheral cutting edge 12 as appropriate, the rake angle γ of the peripheral cutting edge 12 can be constrained to the number of teeth. Because it can be changed without any change, the rake can be changed easily compared to conventional taper end mills. The sharpness can be improved by changing the angle γ to a more regular angle.

[0025] In addition, by appropriately changing the curvature of the convex curved surface 15, the number of teeth of the peripheral cutting edge 12 can be controlled. Since the clearance angle α can also be adjusted without bunching, for example, if the rake angle γ is square If the change occurs in the direction, the cutting edge strength can be improved by setting the relief angle α smaller accordingly. deterioration can be avoided.

[0026] Furthermore, regarding the cross-sectional area of the cutting edge portion 11, the concave curved surface 14 with respect to the virtual conical surface C, It can be changed by changing the amount of retraction of the convex curved surface 15 in the direction of the tool axis P0. By appropriately setting the shapes of these uneven curved surfaces 14 and 15, the above-mentioned conventional 6 Ensure a cross-sectional area equal to or greater than that of a single-blade taper end mill (Fig. 10). can be done. Therefore, according to the taper end mill of this embodiment, the tool rigidity is It is possible to improve machining efficiency by improving sharpness while preventing corrosion.

[0027] In addition, the rake angle γ and clearance angle α can be set freely, so for example, these rake angles While keeping the angle γ and clearance angle α the same as in the case of 6 blades, the number of peripheral cutting blades 12 is 8, It is also possible to increase the number of sheets to 10, etc., and in such a case, increase the feed amount of the tool, Processing efficiency can be further improved.

[0028] In addition, in the above description, the curvatures of the concave curved surface 14 and the convex curved surface 15, etc. are not specifically explained. Although the target range has not been determined, these are related to the rake angle γ, clearance angle α, and tool diameter. It is set as appropriate. However, the range of rake angle γ is 0° to -45°. It is preferable that If the rake angle γ exceeds 0°, the cutting edge angle of the peripheral cutting edge 12 is insufficient. On the other hand, if the angle is less than -45°, the outer cutting edge 1 This is because cutting resistance applied to 2 may increase excessively and the sharpness may deteriorate. Ru. In addition, the sign of the rake angle γ is determined when the line segment m1 is centered on the outer cutting edge 12 in Fig. 3. When the line segment m1 and straight line m2 overlap when rotated counterclockwise as (However, -90°<γ<90°).

[0029] Further, it is preferable that the clearance angle α ranges from 5° to 20°. Relief angle α is 5° If the clearance angle α is less than 2, there is a risk of premature wear of the peripheral cutting edge 12. If it exceeds 0°, the edge angle of the peripheral cutting edge 12 may be insufficient and the tool rigidity may deteriorate. This is because

[0030] In addition, in FIG. 3, in particular, the other end 15b of the convex curved surface 15 and the concave curved surface 14 are smoothed. However, the present invention is not limited to this, and for example, the B part in FIG. As shown in FIG. It goes without saying that a configuration in which they intersect may be used.

[0031] Furthermore, in the above section, the case of a taper end mill was explained. However, the above configuration is modified so that the outer cutting edge 12 is centered on the tool axis as shown in FIGS. 6 and 7. The same effect can be obtained even when applied to a straight end mill that draws a cylindrical rotation trajectory. Of course you can get it. That is, the straight endpoint shown in FIGS. 6 and 7 The cross section perpendicular to the axis has the same shape as the cross-sectional views shown in FIGS. 3 to 5 above. If configured as shown in FIG. especially, In the case of a straight end mill, it is suitable for cutting high hardness materials.

[0032] In addition, this invention is not limited to end mills for deep groove machining, but also improves rigidity and machining. It can be applied to any end mill that requires precision.

[0033]

[Effect of the idea]

As explained above, according to this invention, the concave curved surface and convex surface constituting the circumferential surface of the cutting edge By individually changing the shape of the curved surface, such as the curvature and the position of the center of curvature, it is possible to The rake angle and relief angle can be changed without being restricted by the number of peripheral cutting edges. Therefore, it is possible to improve cutting quality by changing the rake angle to a more square direction than before. In both cases, the tool cross-sectional area and cutting edge angle can be adjusted by adjusting the clearance angle accordingly. This prevents excessive decrease in tool rigidity, suppresses deterioration of tool rigidity, and further improves the sharpness of the outer cutting edge. It is said that it is possible to perform highly efficient machining by increasing the number of peripheral cutting edges while maintaining the same It has excellent effects.

[Brief explanation of drawings]

FIG. 1 is a side view of a tool body according to an embodiment of the present invention.

FIG. 2 is a view taken from the direction I in FIG. 1;

FIG. 3 is a sectional view taken along the line II-II in FIG. 1.

FIG. 4 is an enlarged view of a cross section of the cutting edge.

FIG. 5 is a sectional view of another embodiment of the present invention.

FIG. 6 is a side view of a tool body according to another embodiment of the present invention.

7 is a view taken from the direction III in FIG. 6; FIG.

FIG. 8 is a side view showing a tool body according to a conventional example.

FIG. 9 is a bottom view of the tool of FIG. 8;

FIG. 10 is a sectional view taken along the line IV-IV in FIG. 8;

FIG. 11 is a modification of the cross-sectional shape shown in FIG. 10.

FIG. 12 is a side view of a tool body according to another conventional example.

FIG. 13 is a bottom view of the tool of FIG. 12;

[Explanation of symbols]

10 Shank part 11 Cutting blade part 11a Surrounding surface of tapered part 12 Peripheral cutting edge 14 Concave curved surface 15 Convex curved surface 15a One end of convex curved surface 15b Other end of convex curved surface C virtual conical surface d Rotation diameter of the tip of the outer cutting edge γ, γ1, γ2, γ3 Rake angle α, α1, α2 Relief angle

Claims (3)

[Scope of utility model registration request] 1. An end mill in which a cutting edge is formed at one end of a shaft-shaped shank, and a plurality of peripheral cutting edges are formed around the tool axis on the outer periphery of the cutting edge, the cutting edge In a section perpendicular to the tool axis, the circumferential surface of the section includes a concave curved surface that is concave toward the center of the cutting edge in the radial direction, and a convex curved surface that projects outward in the radial direction of the cutting edge. are arranged alternately in the circumferential direction of the tool, and the convex curved surface has one end coincident with a rotation circle that is a rotation locus of the outer peripheral cutting edge in a cross section perpendicular to the tool axis, and a curve extending from the one end to the other end. The tool is retreated toward the center in the radial direction while gradually drawing an arc with a larger curvature than the rotating circle as it moves toward the center, and the intersection ridgeline between the one end of the convex curved surface and the concave curved surface is the outer circumferential cutting edge. An end mill characterized by: 2. The end mill according to claim 1, wherein the peripheral cutting edge is formed to draw a cylindrical rotation locus centered on the tool axis. 3. The end mill according to claim 1, wherein the outer circumferential cutting edge is formed to draw a conical rotation locus centered on the tool axis and gradually decreasing in diameter toward the tip.