JP2000288827A - End mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cutting performance and chip discharging property while preventing welding of chippings. SOLUTION: An end mill has a tool mainbody with its axially perpendicular section in approximately square and cutting edges 17 formed at corners C. Pockets 23 are formed in approximately V-shaped section by rake faces 15 and bottom faces 22 provided on the front sides of the cutting edges in the rotating direction. Chip discharging grooves 14 are formed by approximately V-shaped recesses in the cutting faces 15 and the bottom face 22 and twisted toward the base ends. The pockets 23 formed by the rake faces 15 and the bottom face 22 have fine protruded faces 25 arranged in matrix with their tops 25a located at the same height in the perpendicular sections of the cutting edges. Chippings flow on the tops 25a of the protruded faces 25 formed by the rake faces 15 and the bottom face 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip discharge groove formed on an outer periphery of a tool body, wherein a cutting edge is formed on an outer peripheral side ridge, and a groove or shoulder cutting of a workpiece such as a mold is performed. The present invention relates to end mills used for

[0002]

2. Description of the Related Art Conventionally, as an example of this type of end mill, there is a solid type end mill. This end mill is, for example, an end mill 1 having four blades, and an axis O of a substantially cylindrical tool body 2 centered on an axis O which forms a rotation center.
6 is shown as a cross section orthogonal to the axis as shown in FIG. 6, in which four chip discharge grooves 3 are formed on the outer circumference at equal intervals in the circumferential direction, and each chip discharge groove 3 is in the tool rotation direction T side. The rake face 4 is a rake face 4 and a cutting edge is formed at an outer peripheral side ridge of the rake face 4, that is, an intersection ridge line portion between the rake face 4 and a flank 5 facing the outer peripheral side of the tool while intersecting the rake face 4. 6 are formed. Here, the rake face 4 draws a concave curve or a straight line in a sectional view and extends to the radial axis O side and is connected to the groove bottom 3a of the chip discharge groove 3, and the groove bottom 3a draws a concave curve and the tool body 2 Is connected to the flank 5 of another cutting edge 6 adjacent to the outer side of the center thickness circle R in the rotation direction via the convex curved portion 7 circumscribing the center thickness circle R and further drawing a convex curve. Become.
The rake face 4 and the groove bottom 3 which are continuous in the rotation direction of the cutting blade 5 forward.
a and the convex portion 7 constitute the chip discharge groove 3 and at the same time, the cutting edge 6.
Is constituted.

In general, the chip discharge groove 3 is formed so as to be helically twisted about the axis O toward the rear side in the tool rotation direction T from the front end side to the rear end side of the tool body 2. Accordingly, the cutting blade 6 is also formed in a spiral shape. When the workpiece is cut by rotating the tool body 2 around the axis, the chip k generated by the cutting edge 5 is formed.
Is run along the rake face 4 and the convex curved portion 7 of the pocket portion 8 to be curled and discharged to the base end side through the chip discharge groove 3.

[0004]

However, in such an end mill 1, when the work material is a soft material such as aluminum, the chips k come into surface contact with the rake face 4 and the convex curved portion 7 of the pocket portion 8. While traveling, it is rubbed, and chips k may be welded to the rake face 4 and the convex curved portion 7 due to cutting resistance and frictional heat,
In addition to impairing the evacuation of the chips k, the cutting performance of the work material is reduced, and the tool body 2 is thermally damaged, so that the tool life is significantly reduced. Moreover, the cutting blade 6 is provided in the chip discharge groove 3.
Is formed following the rake face 4 in the direction intersecting with the surface, there is also a disadvantage that the chips k sliding on these surfaces are easily clogged and the chip discharging property is poor. The present invention
In view of such circumstances, an object of the present invention is to provide an end mill capable of improving chip dischargeability and cutting performance.

[0005]

An end mill according to the present invention has a substantially polygonal cross section perpendicular to the axis of a tool body rotating about an axis, and a cutting edge is formed at each corner of the outer peripheral surface of the tool body. And a pocket portion having a rake surface provided on the front side in the rotation direction of the cutting blade and a bottom surface connected to the rake surface is formed, and a plurality of fine convex curved surfaces are formed in the pocket portion. It is characterized by. The chips generated by the cutting blade travel in the pocket from the rake surface to the bottom surface, and at this time, the chips slide on a plurality of minute convex curved surfaces provided on the surface of the pocket portion, so that the convex curved surface is formed. Of the chip, the contact area between the chip and the rake face or bottom surface is small, and even if the chip is made of a soft material such as aluminum, it can be slid without welding. In addition, since the area of the rake face and the bottom surface is large, there is a heat radiation effect, the bending rigidity of the tool body is high, and when coating the pocket surface, the adhesion strength with the coating layer is high. The rake face and the bottom face connected to the rake face form a concave shape that is recessed with respect to an imaginary line connecting the adjacent cutting blades, and constitute a chip discharge groove that is continuous from the tip to the base end.

In the cross section orthogonal to the cutting edge, the plurality of convex curved surfaces may be arranged at substantially the same height. Since the convex curved surfaces are arranged at the same height, the chips flowing thereon will flow on a substantially flat surface, and the chip flow is good. Further, the convex curved surfaces may be smoothly connected to each other via the concave curved surface. Since two adjacent convex curved surfaces are smoothly connected by a concave curved surface, the strength of the tool main body is high without cracks between the convex curved surfaces. Preferably, the tool main body may have a substantially quadrangular cross-section or a substantially polygonal cross-section.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 is a side view of the end mill according to the embodiment, FIG. 2 is a front end view of the end mill shown in FIG. 1, FIG. 3 is an axial cross-sectional view taken along line AA of the end mill shown in FIG. 1, and FIG. And FIG. 5 is an enlarged cross-sectional view of the pocket portion shown in FIG. In the end mill 10 shown in FIGS. 1 to 3, a tool body 11 whose axis of rotation is the center of rotation is made of a hard material such as a cemented carbide, and is composed of a blade portion 12 on the distal side and a shank portion 13 on the proximal side. Is a solid type square end mill. The end mill 10 has a section along the line AA in a direction perpendicular to the axis O at an appropriate position from the tip end of the blade section 12, that is, a section perpendicular to the axis, for example, has a substantially square shape. Blade 12
Are formed with a chip discharge groove 14 in a front region of each corner portion C of the axis orthogonal cross section shown in FIG. 3 in the tool body rotation direction T, and these four chip discharge grooves 14. An appropriate angle δ with respect to the axis O so that it is twisted rearward in the rotation direction T about the axis O of the tool main body 11 toward the base end.
And are formed at equal intervals in the circumferential direction.

The wall surface of each of the chip discharge grooves 14 facing the tool rotation direction T is a rake face 15 reaching the top of the corner C, and the intersection ridge line between the rake face 15 and the flank 16 connected thereto is formed. A cutting edge 17 is formed as an outer peripheral edge at the corner C formed, and the cutting edge 17 is formed to be spirally twisted around the axis O at an inclination angle δ. A rake face 15 and a rake face 15 as shown in FIG.
A bottom blade 19 is formed at the intersection ridge line with the tip flank 18 that intersects with the bottom surface. The four bottom blades 19 are formed radially so as to extend from the axis O to the outer peripheral side of the tool along the radial direction thereof. ing.

The configuration of the cross section perpendicular to the axis of the end mill 10 will be further described. In the cross section perpendicular to the axis of the tool main body 11 shown in FIG. A cutting edge 17 serving as an outer peripheral edge is formed at each corner portion C with the square cross section S as a basic shape, and the rake face 15 is formed with the side s1 of the virtual square cross section S facing inward in the axis O direction. The flank 16
Is formed to expand outward with respect to the side s1. With this, the rake angle θ of the cutting edge 17 is set to be more positive with respect to the virtual side s1 to ensure good sharpness, and the flank 16 is formed along the rotation locus of the cutting edge 17 (that is, the circumscribed circle of the tool body 11). Ra) and swell outward to avoid contact with Ra)
, A large edge angle β can be secured. Here, the rake angle θ is set to a negative value in FIG. 3, but is not limited to this, and by setting the rake angle in a range of −15 ° to + 15 °, the cutting resistance can be reduced and a high-hardness material such as aluminum can be used. Can handle a wide range of material cutting. By setting the clearance angle α to 5 ° to 20 °, the cutting edge angle β can be made large and the cutting edge rigidity can be improved.

A bottom surface 22 is formed from the inner edge of the rake face 15 to the flank 16 of the cutting edge 17 at the adjacent corner C, and the bottom face 22 has a imaginary connection 22a with the rake face 15. Is formed at an angle γ with respect to the virtual side s1 such that the connection portion 22b between the virtual side s1 and the adjacent flank 16 is positioned outside the virtual side s1. And the chip discharge groove 14 is the rake face 1
5 and the bottom surface 22 are formed so as to be substantially V-shaped when viewed in cross section. At the same time, the entire area formed by the rake face 15 and the bottom surface 22 constitutes a pocket portion 23 of the cutting blade 17. An inscribed circle drawn by a two-dot chain line with respect to the cross section orthogonal to the axis of the tool body 11 thus formed, preferably
The inscribed circle contacting at 2 is referred to as a core thickness circle Rb. This heart thickness circle Rb
Is larger in diameter than the inscribed circle of the virtual square S. For this reason, the cross section orthogonal to the axis of the tool main body 11 forms a substantially square shape, so that the rigidity is higher than that of the conventional end mill, and the core thickness circle Rb can be further enlarged, so that the rigidity can be further improved. Here, assuming that the diameter of the circumscribed circle Ra is D1 and the diameter of the inscribed circle Rb is D2, D2 = (0.6 to 0.8) D1. If D2 is smaller than 0.6D1, the rigidity of the tool main body 11 decreases, and if D2 is larger than 0.8D1, the depths of the pocket portion 23 and the chip discharge groove 14 become small, and chip clogging easily occurs.

FIG. 4 shows a cross section orthogonal to the cutting edge 17 of the cutting body 17 of the tool body 11 of the end mill 10 configured as described above. The bottom surfaces 22 are each formed substantially linearly. Moreover, the rake face 15 and the bottom face 23 have a substantially radius r1 (for example, r1 = 10 m) as shown in FIG.
m), a large number of substantially hemispherical fine convex curved surfaces 25 are arranged, and two adjacent convex curved surfaces 25, 25 are fine concaves having a substantially radius r2 (for example, r1>r2; r2 = 1 mm). They are smoothly connected by a curved surface 26. As a result, it is possible to prevent cracks or the like from occurring at the joint between the adjacent convex curved surfaces 25. Therefore, the convex curved surface 25 and the concave curved surface 26 are arranged in a matrix along the direction perpendicular to the cutting edge and the extending direction of the cutting edge 17 intersecting with the cutting surface, and have a substantially sinusoidal shape in cross section. . The tops 25a of the convex curved surfaces 25 are formed so as to be located at substantially the same height, that is, at the same plane in a cross section orthogonal to the cutting blade.
The convex curved surface 25 and the concave curved surface 26 are preferably formed in the entire area of the rake surface 15 and the bottom surface 22 of the pocket portion 23,
It may be formed only in a part of the area. Further, since the convex curved surface 25 has a small diameter r1 and is arranged in a matrix, it does not function as a breaker, and the chips reliably slide on the top 25a of the convex curved surface 25.

Since the end mill 10 according to the present embodiment is configured as described above, the tool body 11 is rotated while rotating the end mill 10 around the axis O during the cutting of the workpiece.
The work material is cut by the bottom blade 19 and the cutting blades 17 on the outer peripheral surface. Chips generated by the cutting edge 17 forming the outer peripheral edge travel on the rake face 15 of the pocket portion 23 in a direction intersecting the cutting edge 17, extend on the bottom surface 22 and are rounded, and the chip discharge groove 1 is formed.
4 to the proximal end. At this time, pocket 2
Since the rake face 15 and the bottom face 3 of 3 are composed of a large number of fine convex surfaces 25..., Chips run by rubbing the vicinity of the top 25 a of the convex surface 25 as shown in FIG. Because it does not touch the curved surface 26, the contact area is small,
Even if the chips are made of a soft material such as aluminum which is easily welded, welding to the rake face 15 and the bottom face 22 can be reliably prevented. Bottom 2
2 is formed in a substantially linear shape when viewed in a cross section orthogonal to the cutting blade, so that the chip flow is good and the chip discharging property through the chip discharging groove 14 is improved. On the other hand, in the conventional end mill 1, since the large-diameter convex curved portion 7 is formed in the region of the bottom surface 22 as shown by a two-dot chain line in FIG. Arise

Further, since the rake face 15 and the bottom face 22 are composed of a large number of convex curved surfaces 25 and concave curved surfaces 26, the surface area is large and the heat radiation effect is high. In addition, when the rake face 15 and the bottom face 22 or the entire tool body 11 is coated with a coating of a high-hardness material such as titanium, the adhesion strength is improved due to the unevenness. Further, the bending rigidity of the tool body 11 can be improved.

In the above-described embodiment, the rake face 15 and the plurality of convex curved faces 25 on the bottom face 22 are formed to have the same height, that is, a substantially straight shape when viewed in a cross section orthogonal to the cutting edge. Is not limited to such a configuration, and may be formed in a concave curve or a convex curve with respect to the rake face 15 when viewed in a cross section orthogonal to the cutting edge, and may be formed with a concave curve with respect to the bottom surface 22. Is also good. Further, in the above-described embodiment, the so-called square end mill 10 in which the cutting edge 17 and the bottom edge 19 have a square corner has been described. However, the present invention is not limited to such a configuration, and may be an outer peripheral edge. The present invention can be applied to a so-called taper end mill having a tapered cutting edge 17, a ball end mill having an arc-shaped bottom blade, a radius end mill having a round corner, and the like. Although the solid end mill has been described in the above embodiment, the present invention is not limited to such a configuration, and the present invention can be applied to a cutting edge brazing type end mill, a throwaway type end mill, and the like.

[0015]

As described above, in the end mill according to the present invention, the cross section orthogonal to the axis of the tool body rotating around the axis is substantially polygonal, and the cutting edge is provided at each corner of the outer peripheral surface of the tool body. Is formed, and a pocket portion having a rake surface provided on the front side in the rotation direction of the cutting blade and a bottom surface connected to the rake surface is formed, and a plurality of fine convex curved surfaces are formed in the pocket portion. The chip has a small contact area with the rake face and bottom when sliding on multiple fine convex surfaces in the pocket, and even if the chip is made of a soft material such as aluminum, It can be moved, has good chip discharge performance and cutting performance, has a large rake face and bottom area, has a heat dissipation effect, has high bending rigidity of the tool body, and furthermore, it has a coating layer when coating the pocket surface. Adhesive strength with An effect that high.

In the cross section orthogonal to the cutting edge, the plurality of convex curved surfaces are arranged at substantially the same height, so that the chips flowing on the bottom surface flow on a substantially flat surface, and the chips flow well. Further, since the convex curved surfaces are smoothly connected to each other via the concave curved surfaces, the strength of the tool main body is high without cracking between the convex curved surfaces.

[Brief description of the drawings]

FIG. 1 is a side view of an end mill according to an embodiment of the present invention.

FIG. 2 is a front end view of the end mill shown in FIG.

FIG. 3 is a cross-sectional view orthogonal to the line AA of the end mill shown in FIG. 1;

FIG. 4 is a cross-sectional view orthogonal to a cutting edge in a pocket portion of the end mill shown in FIG. 1;

FIG. 5 is an enlarged sectional view of a bottom surface portion of the pocket portion shown in FIG.

FIG. 6 is a cross-sectional view perpendicular to the axis of a conventional end mill.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 End mill 11 Tool main body 14 Chip discharge groove 15 Rake surface 17 Cutting blade (outer peripheral blade) 22 Bottom surface 23 Pocket portion 25 Convex curved surface 26 Concave curved surface

Claims (3)

[Claims] 1. A tool body rotating about an axis has a substantially polygonal cross section orthogonal to an axis, and a cutting edge is formed at each corner of an outer peripheral surface of the tool body, and a rotating direction of the cutting edge is provided. An end mill in which a pocket having a rake face provided on the front side and a bottom face connected to the rake face is formed, and a plurality of fine convex curved surfaces are formed in the pocket. 2. The end mill according to claim 1, wherein the plurality of convex curved surfaces are arranged at substantially the same height in a cross section orthogonal to the cutting edge. 3. The convex curved surface is smoothly connected to each other via a concave curved surface.
End mill as described.