JP3342522B2 - End mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill having an outer peripheral edge formed on the outer periphery of a tip end of a tool body, and a bottom edge connected to the outer peripheral edge formed at the end of the tool body.

[0002]

2. Description of the Related Art For grooving and shoulder milling in cutting, a chip discharge groove is formed on the outer periphery of a tip end of a cylindrical shaft-shaped tool body which is made of a hard material such as cemented carbide and is rotated around its axis. An outer peripheral edge is formed at an intersection ridge portion between the groove wall surface of the chip discharge groove facing the tool rotation direction and the outer peripheral surface of the tool body, and an intersection ridge line portion between the groove wall surface and the front end surface of the tool body. In addition, an end mill having a bottom blade formed from the tip of the outer peripheral blade toward the rotation center of the tip of the tool body is used. Here, the groove wall surface of the chip discharge groove is a rake face of an outer peripheral blade and a bottom blade, the outer peripheral surface of the tool main body is a flank of an outer peripheral blade (outer peripheral flank), and the tip end surface of the tool main body. Is the flank of the bottom blade (the flank of the tip).

In such an end mill, the strength of the cutting edge at the corner of the outer periphery of the tool main body where the outer peripheral blade and the bottom blade intersect is secured, or the discharge of chips generated by the bottom blade is promoted. In order to do so, a so-called gash surface is formed by shaving off a portion connected to the bottom blade on the tip end side of the groove wall surface entirely or partially along the bottom blade in one step. .
FIGS. 7 to 10 show the end of the end mill having such a gash surface 1 formed thereon. FIGS. 7 and 8 show the gash surface 1 at the end of the groove wall 3 over the entire length of the bottom blade 2. 9 and 10 show a case where the gash surface 1 is formed along a part of the bottom blade 2. FIG. In the drawing, reference numeral 4 denotes a tool main body of the end mill. Similarly, reference numeral 5 denotes a chip discharge groove, reference numeral 6 denotes an outer peripheral flank, reference numeral 7 denotes an outer peripheral blade, and reference numeral 8 denotes a tip flank. Reference symbol O indicates the axis of the tool body 4. Further, the groove wall surface 3 is formed in a concave curved surface that is recessed rearward in the tool rotation direction (the direction of the arrow T in the drawing) so that the outer peripheral blade 7 is provided with a positive rake angle in the radial direction.

Here, in the end mill of the example shown in FIGS. 7 and 8, the gash surface 1 is formed from the center of rotation of the tool at the tip of the tool body 4 to the outer peripheral blade 7 over the entire length of the bottom blade 2. Therefore, the corner portion 9 where the bottom blade 2 and the outer peripheral blade 7 intersect is formed at the corner of the gash surface 1 which has been shaved off in a planar shape, whereby the gash surface 1, the outer peripheral flank 6 and the tip flank are formed. The intersection angle formed by the surface 8 can be set to be large, and the edge strength at the corner 9 of each of the cutting edges 2 and 7 can be secured. On the other hand, in the end mill of the example shown in FIGS. 9 and 10, since the gash surface 1 is formed only from the tool rotation center to the middle of the bottom blade 2, the gash surface 1 extends from the gash surface 1 in the radial direction of the tool body 4. 3, the bottom blade 2 is bent. Then, as a result, the chips C generated by the bottom blade 2 are divided into two at the generation stage as shown in FIG. 10, so that it is possible to promote good chip discharge.

[0005]

As described above, according to the above-mentioned conventional end mill, by appropriately forming the gash surface 1 along the bottom edge 2, the life of the tool can be extended and the chip discharge performance can be improved. It is possible to obtain an advantage that smooth cutting can be performed with an improvement. However, in these end mills, it was impossible to obtain the advantages of the other end mill, and to obtain one advantage, the other advantage had to be sacrificed to some extent.

That is, in the end mill shown in FIGS. 7 and 8, although the strength of the cutting edges 2 and 7 at the corner 9 is ensured, the gash surface 1 is provided over the entire length of the bottom blade 2. As a result, the bottom blade 2 must be formed in a straight line, so that the chips C generated by the bottom blade 2 become wide as shown in FIG. 8, and the chip discharge performance is significantly impaired. I will be. On the other hand, in the end mill shown in FIGS. 9 and 10, although the bottom blade 2 is bent as described above, the chips C can be divided to obtain a good discharge property, but the bottom blade 2 and the outer peripheral blade 7 are separated. Since the gash surface 1 does not extend to the intersecting corner portion 9, the bottom blade 2 and the outer peripheral edge 7 near the corner portion 9.
It is not possible to make the edge angle of the blade too large, and there is a possibility that the edge strength is degraded to cause chipping or the like.

Therefore, in the above-mentioned conventional end mill, an appropriate end mill is selected according to the cutting conditions, or
Alternatively, it is necessary to set the cutting conditions according to the end mill performance such as the chip dischargeability and the strength of the cutting edge, and it is difficult to support a wide range of cutting conditions with one end mill. There has been a high demand for a highly versatile end mill that has both the advantages of the two types of end mills described above, which has high cutting edge strength while providing dischargeability. The present invention has been made in view of such circumstances, and has been made to satisfy such a demand.

[0008]

According to the present invention, in order to solve the above-mentioned problems and achieve the above object, a chip discharge groove is formed on the outer periphery of a tip end portion of a tool body rotated around an axis. An outer peripheral edge is formed at an intersection ridgeline between the chip discharge groove and the outer peripheral surface of the tool body, and a groove wall facing the tool rotation direction of the chip discharge groove, and at an intersection ridgeline between the groove wall surface and the tip end surface of the tool body. An end mill formed with a bottom blade extending from the distal end of the outer peripheral blade toward the rotation center of the distal end of the tool main body, wherein the distal end of the groove wall surface extends along the bottom blade from the outer periphery of the tool main body to the rotation center. A gash surface is formed, and the gash surface is formed by a plurality of planes or curved surfaces, or a plane and a curved surface, which are bent in multiple stages in the circumferential direction of the tool main body. blade Rake angle of the fine peripheral cutting edge is a conformal
It has a concave curved surface when viewed from the front and is located radially inward.
The angle of intersection with the gash surface to be placed is obtuse and
The intersection angle between the gash surface located on the side
Set the cutting edge strength at the corner between the bottom edge and the outer edge.
It is characterized by securing .

[0009]

According to the end mill having such a configuration, first, the gash surface is formed so as to reach the outer periphery of the tool main body when viewed from the center of rotation of the tip of the tool main body. The cutting edge angle of both cutting edges can be ensured, and the cutting edge strength can be maintained to prevent breakage or the like. On the other hand, since the gash surface is formed to be bent in multiple stages in the circumferential direction of the tool body by a plurality of surfaces, the bottom blade is also bent in multiple stages accordingly. Thus, the chips generated by the bottom blade are separated in the width direction at the stage of generation, so that it is possible to promote smooth discharge of the chips. Therefore, according to the present invention, it is possible to obtain excellent chip dischargeability while maintaining the strength of the cutting edge and extending the tool life, and also has the advantages of the two types of conventional end mills described above. It is possible to provide a highly versatile end mill.

[0010]

1 to 3 show an embodiment of the present invention. In the end mill of this embodiment, the tool body 1
Reference numeral 1 denotes a substantially cylindrical shaft formed of a hard material such as a cemented carbide and the like, and a tip portion of which has two strips twisted helically from the tip end of the tool body 11 toward the base end at a twist angle α. Drain groove 1
2 and 12 are formed at equal intervals in the circumferential direction of the tool main body 11. A groove wall surface 13 of the chip discharge groove 12 facing the tool rotation direction (the direction of the arrow T in the drawing) and a tool body 11
An outer peripheral blade 15 is formed at a ridge line crossing the outer peripheral surface (outer peripheral flank) 14 of the distal end portion. In addition, this groove wall 1
3 has a tip end surface (tip flank) 1 of the tool body 11.
A bottom blade 17 is formed at the intersection ridge line with the bottom 6 so as to extend from the tip of the outer peripheral blade 15 toward the tool rotation center at the tip of the tool body 11.

In this embodiment, the bottom blade 17 formed at the tip of one of the chip discharge grooves 12 has its center of rotation as viewed from the front side of the tool body 11. Beyond, it is formed to be longer than the bottom blade 17 at the tip of the other chip discharge groove 12. In addition, the outer peripheral blade 1
5 is formed by being twisted in accordance with the twist of the chip discharge groove 12, whereby the outer peripheral blade 15 is given a positive axial rake angle α. Further, the groove wall surface 13 is formed as a concave curved surface that is recessed rearward in the tool rotation direction, so that the outer peripheral edge 15 is also given a positive radial rake angle.

At the tip of the groove wall 13, the gasket surface 18 is cut so that the groove wall 13 is cut down one step from the outer periphery of the tool body 11 to the tool rotation center along the bottom blade 17. Are formed. Therefore, the bottom blade 17 is actually formed at the intersection ridge line between the gash surface 18 and the front flank 16. Also, the tip of the outer peripheral blade 15 is formed at the intersection ridge line between the gash surface 18 and the outer peripheral flank 14. Further, in the present embodiment, the gash surface 18 is formed by two flat surfaces 18a and 18b that are bent in the circumferential direction of the tool main body 11 toward the outer peripheral side of the tool. Here, these planes 18a and 18b are arranged such that the plane 18b arranged on the outer peripheral side of the tool with respect to the plane 18a arranged on the central side of the tool rotation is directed toward the rear side in the tool rotation direction toward the outer peripheral side of the tool. Are crossed at an obtuse angle. Thus, the bottom blade 17 is also formed by two cutting blade portions 17a and 17b which are bent in the circumferential direction of the tool body 11 and intersect at an obtuse angle.

The planes 18a and 18b are inclined with respect to the direction of the axis O of the tool body 11 at an inclination angle φ smaller than the inclination angle of the groove wall surface 13 with respect to the axis O, that is, the torsion angle α. Is formed. Therefore, the intersection angle formed by the flat surfaces 18a and 18b with the tip flank 16 is larger than the intersection angle formed by the groove wall surface 13 with the tip flank 16. Further, as described above, the plane 18
Since the plane 18b is formed so as to intersect at an obtuse angle with respect to the a, the intersection angle formed by the plane 18b and the outer peripheral flank 14 on the tool outer peripheral side of the gash surface 18 is equal to the groove wall surface 13 and the outer peripheral flank. Is larger than the intersection angle
As a result, the radial rake angle δ at the tip of the outer peripheral blade 15 is set to the negative angle side.

In the end mill having such a configuration, the two flat surfaces 18a and 18b of the gash surface 18 formed at the tip of the groove wall surface 13 are formed so as to intersect the tip flank 16 at a large intersection angle. At the same time, the flat surface 18b arranged on the outer peripheral side of the tool is formed so as to reach the outer peripheral blade 15 and intersect with the outer peripheral flank 14 at a large intersection angle. The blade angle at the tip of the blade 15 is set to be large. For this reason, according to the end mill having the above configuration,
High cutting edge strength can be given to each of the cutting edges 15, 17,
Particularly at the corner 19 where the outer peripheral blade 15 and the bottom blade 17, which tend to be fragile, intersect with each other, a situation such as a loss of the cutting blade is prevented beforehand, and the tool life can be extended.

On the other hand, in the end mill having the above-described structure, the gash surface 18 is formed by the two flat surfaces 18a and 18b bent in the circumferential direction of the tool body 11, so that the bottom blade 17 also has two cutting blades bent in a broken line. Parts 17a, 17b
Formed from Accordingly, the chips C generated by the bottom blade 17 flow out in a state of being separated in the width direction from the generation stage as shown in FIG.
Rapid chip processing becomes possible and smooth discharge can be promoted. As described above, according to the present embodiment, it is possible to provide both of the advantages of the two types of conventional end mills described above, and to provide an end mill having a good chip discharge property while extending the tool life. Becomes possible. This makes it possible to cut a wide range of conditions with one end mill without having to select end mills that match cutting conditions as in the past, or force cutting conditions to be set according to end mills. This makes it possible to expand the versatility of the end mill.

In the present embodiment, two flat surfaces 18a and 18 are formed so that the gash surface 18 is bent in the circumferential direction of the tool body 11.
4B, it may be formed by a flat surface 18c and a concave curved surface 18d as shown in FIG. 4A, or may be formed by a flat surface 18e and 18f and a concave curved surface 18 as shown in FIG.
g, three or more planes 18h, 18i, 18j, 18k... as shown in FIG. 4C, or planes 18l and 18l as shown in FIG.
18m and the convex curved surface 18n, or a configuration in which these are appropriately combined. Here, in the examples shown in FIGS. 4A and 4C, the radial rake angle δ at the tip of the outer peripheral blade is set to the regular angle side, but the respective surfaces 18c, 18d, 18h, 18i, 1
By setting the intersection angle between 8j, 18k and the flank 16 of the tip to be larger, it is possible to sufficiently secure the edge strength at the corner portion 19. In addition, conversely, in these examples, by setting the radial rake angle δ on the regular angle side, it is possible to obtain an advantage that the cutting resistance acting on the outer peripheral blade 15 can be reduced.

Further, in the embodiment shown in FIGS. 1 to 3, the case where the present invention is applied to a two-flute end mill has been described, but the present invention is not limited to such a number of cutting blades. Of course, for example, as shown in FIGS.
It is also possible to use it for a single-flute end mill or an end mill having a different number of teeth. 4 to 6, the same components as those of the embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and description thereof is omitted. Also, in FIG. 4, the tip flank 16 at the tip of the tool body,
Only the bottom blade 17 and the gash surface 18 are shown.

[0018]

As described above, according to the present invention, in an end mill having an outer peripheral edge and a bottom edge, the edge strength of these cutting edges, particularly the outer peripheral portion of the tip of the tool body where these cutting edges intersect. It is possible to ensure the strength of the cutting edge at the corners, to suppress the occurrence of chipping and the like, and to improve the tool life, and also to enable the chip to be finely divided from the stage of its generation, thereby enabling smooth chip discharge. This makes it possible to provide a highly versatile end mill that can respond to a wide range of cutting conditions with one end mill.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a (a) side view of a tip portion of the embodiment shown in FIG. 1;
(B) is a front view, and (C) is a top view.

FIG. 3 is a front view showing a generation state of chips in the cutting according to the embodiment shown in FIG. 1;

4 is a front view showing a modified example of the embodiment shown in FIG. 1 (a tip flank 16, a bottom blade 17, and a gash surface 18).
Only).

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

FIG. 6 is a front view of the embodiment shown in FIG.

7A is a side view showing an example of a conventional end mill, FIG.
(B) is a front view, and (C) is a top view.

8 is a front view showing a state of generation of chips in cutting by the conventional end mill shown in FIG.

9A is a side view, FIG. 9B is a front view, and FIG.

FIG. 10 is a front view showing a state of generation of chips in cutting by the conventional end mill shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Tool main body 12 Chip discharge groove 13 Groove wall surface 14 Outer peripheral flank 15 Outer peripheral blade 16 Tip flank surface 17 Bottom blade 17a, 17b Cutting blade portion 18 Gash surface 18a, 18b Surface (plane) forming gash surface 18 19 Corner portion O The axis C of the tool body 11

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-159010 (JP, A) JP-A-1-216710 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23C 5/10

Claims (1)

(57) [Claims] 1. A chip discharge groove is formed on an outer periphery of a tip end portion of a tool body rotated around an axis, and an intersection ridgeline portion of a groove wall surface of the chip discharge groove in a tool rotation direction and an outer peripheral surface of the tool body. An end mill formed with an outer peripheral edge formed at an intersection ridge line between the groove wall surface and the distal end surface of the tool main body, the bottom edge extending from the distal end of the outer peripheral edge toward the rotation center of the tool main body distal end. In the end of the groove wall surface, a gash surface is formed along the bottom blade from the outer periphery of the tool body toward the rotation center, and the gash surface is bent in multiple steps in the circumferential direction of the tool body. Plane, or a curved surface, or a plane and a curved surface, and the gash surface intersecting the outer peripheral blade has a rake angle of the bottom blade and the outer peripheral blade of a regular angle and
It has a concave curved surface when viewed from the front and is located radially inward.
The angle of intersection with the gash surface is obtuse, and
Increase the intersection angle between the located gash surface and the flank of the tip
Set the edge strength at the corner between the bottom blade and the outer blade
An end mill characterized by being secured .