JP2573120Y2 - Ball 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 a ball end mill in which an arc-shaped cutting edge is provided on an ultra-high pressure sintered body such as cubic boron nitride (hereinafter referred to as CBN) or a diamond sintered body.

[0002]

2. Description of the Related Art Conventionally, as a ball end mill used for mold processing or the like, for example, as shown in FIG.
The tip of the tool body 1 that is rotated about
A two-blade cutting insert (hereinafter, abbreviated as a tip) 2, 3 is attached with the respective arc-shaped cutting blades 4, 5 positioned from the outer peripheral side of the tool body 1 to the distal end side. ball end mill M ₀ is known. Here, as shown in more detail in FIGS. 8 and 9, one of the chips 2 and 3 has an arcuate cutting edge 4 and a straight cutting edge 6 with respect to the center P ₀ of the chip mounting hole 7. At the tip of the arc-shaped cutting edge 4, a convex curved portion 4 a is formed, which approaches the lower surface 8 as approaching the tip P ₁ of the arc-shaped cutting edge 4. And one chip 2
Moves the tip P ₁ of the arcuate cutting edge 4 to the axis O of the tool body 1.
It is attached to match. On the other hand, the other chip 3 has an arc-shaped cutting edge 5 and a linear cutting edge 9 like the one chip 2, but is provided with a linear notch 10 at a corner thereof. 2 and the shape is different. And when the tip 3 is attached to the tool body 1,
Tip P ₂ of the arc-shaped cutting edge 5 by the presence of the notch 10 is spaced from the axis O of the tool body 1 by a predetermined distance d.

[0003]

An invention is the way, when processing the high-hardness material of the mold such as in the conventional ball end mill M ₀ as described above, the rake face of the chip 2,3 CBN or diamond sintered body or the like of the ultrasonic 2. Description of the Related Art High-speed sintering is fixed, and arc cutting blades 4, 5 and the like are formed on the ultra-high-pressure sintering body. However, when it adds an extra-high pressure sintered body chips 2 of the ball end mill M ₀ of the above-described configuration, there is a disadvantage that its performance wear of the ultra-high-pressure sintered body is severely can not be obtained at an early stage Was. That is, in the ball end mill M ₀ shown in FIG. 7 described above, since the distal end P ₂ of the arc-shaped cutting edge 5 is spaced by a predetermined distance d from the axis O of the tool body 1, to a position spaced from the axis O by a distance d During this period, cutting is performed only by the arcuate cutting edge 4 of one tip 2. Moreover, the axis O of the tool body 1
Since the cutting speed is extremely slow in the vicinity of the tool body 1 compared to the outer peripheral side of the tool body 1, the cutting resistance applied to the tip of the arc-shaped cutting blade 4 is considerably large. The ultrahigh-pressure sintered body has high rigidity and low toughness as compared with a chip material such as a cemented carbide, so that the wear progresses remarkably quickly when the cutting resistance is large. Therefore,
When the ultra-high pressure sintered body is used for the ball end mill M ₀ as it is, the wear of the ultra-high pressure sintered body at the tip of the arc-shaped cutting edge 4 becomes much more intense than other parts,
The superior performance of the ultra-high pressure sintered body cannot be exhibited over a long period of time. The present invention has been made under such a background, and in a ball end mill using a chip with an ultra-high pressure sintered body, the excellent cutting performance of the ultra-high pressure sintered body can be exhibited over a long period of time. It is intended to provide a ball end mill.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a tool body which is rotated about an axis, and a tool body attached to an axial end of the tool body.
In the ball end mill having the above-mentioned tip and the tip, the arc-shaped cutting edge is positioned from the outer peripheral side of the tool body to the tip end side, and the surface connected to these arc-shaped cutting edges is attached as a rake face. When the inner peripheral end of the arc-shaped cutting edge of each of the tips is viewed from the bottom in the axial direction of the tool body, a circular arc having a diameter of 0.1 to 0.5 mm around the axis of the tool body. Rutotomoni is separated from the axis of said tool body so as to draw a rotation locus, the side facing the tool body radially inner periphery of each chip, axial rear end of the tool body from the inner peripheral end of the arcuate cutting edge Towards this side
So that the angle of inclination with respect to the axis is in the range of 15 ° to 60 °
In addition, the tool body is retracted to the radially outer peripheral side of the tool main body. In this case, the chips may be different in shape from each other as in the prior art. However, in order to facilitate tool management, it is desirable that all chips have the same shape and size. To further extend the life of the chip,
An ultra-high pressure sintered body in which each of the above chips is fixed to each base metal
The above-mentioned arcuate cutting blade is formed thereon, and these arcuate cutting blades are formed.
The surface of the ultra-high pressure sintered body connected to
In a certain range connected to the inner peripheral end of the arcuate cutting edge of each of these tips, the tip is convex in the direction of rotation of the tool body, and the superimposed as it goes toward the inner peripheral end of the tip. The thickness of the ultra-high pressure sintered body at the inner peripheral end of the arcuate cutting edge which forms a convex curved portion approaching to the joining surface side between the high pressure sintered body and the base metal and is located at the tip of the convex curved portion The amount of retreat in the direction is preferably set to be less than the thickness of the ultrahigh-pressure sintered body.

[0005]

According to the above construction, the arc-shaped cutting blades of the plurality of inserts are formed such that each inner peripheral end has a diameter of about 0.
Since it is arranged so as to describe an arc-shaped rotation locus of 1 mm to 0.5 mm, the arc-shaped cutting edge of each chip performs cutting substantially equal to almost the axis of the tool body at the time of cutting. Therefore, the wear does not progress unevenly to a specific chip, and the possibility that the cutting performance is impaired at an early stage is small. Here, the reason why the diameter of the rotation locus of the arc-shaped cutting edge is set to 0.1 mm or more is 0.1 mm.
If it is less than 1 mm, the inner peripheral edges of the arc-shaped cutting edges are likely to interfere with each other, while if it exceeds 0.5 mm, the part without the cutting edge near the axis of the tool body is too large, and the work material is cut. This is because a non-negligible effect occurs on the sphericity of the surface. Further, the side of the insert facing the radially inner peripheral side of the tool main body is directed from the inner peripheral end of the arcuate cutting edge toward the rear end side in the axial direction of the tool main body, and the inclination angle with respect to this axis is in the range of 15 ° to 60 °.
To the outer circumference of the tool body in the radial direction so that
Because there, preventing decrease in rigidity of the tool body by increasing the wall thickness of the tool body to be left between the chip side surfaces when the inner peripheral edge between the arcuate cutting edge of each chip is closer to the axis of the tool body While giving a sufficient cutting edge length to the arc-shaped cutting edge of the insert.
In addition, the cutting depth can be ensured, and smooth cutting can be performed . In other words, when the inclination angle falls below 15 °,
There is a risk that the thickness of the tool body may not be sufficient
On the other hand, if it exceeds 60 °, the tool body diameter of this insert
The rear end side in the axial direction of the side surface facing the inner peripheral side of the
As it intersects the rear end, sufficient cutting
There is a possibility that the blade length cannot be secured.

If all the chips are of the same shape and size, it is not necessary to prepare a plurality of types of chips, so that the management of the tool is facilitated and the manufacturing cost of the tool is reduced. Further, when the convex curve portion is formed within a certain range from the inner peripheral edge of the arc-shaped cutting blade, the edge strength of the inner peripheral edge of the arc-shaped cutting blade increases. Here, the amount of retreat at the inner peripheral end of the arc-shaped cutting edge is set to be less than the thickness of the ultrahigh-pressure sintered body, when the convex curve portion is retreated beyond the thickness of the ultrahigh-pressure sintered body. ,
This is because the joint between the ultrahigh-pressure sintered body and the base metal is exposed in the middle of the arc-shaped cutting blade, and the ultrahigh-pressure sintered body is likely to be peeled off.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, an overall configuration and a tip shape of a ball end mill according to the present embodiment will be described with reference to FIGS. As shown in FIGS. 3 and 4, the ball end mill M ₁ according to the present embodiment includes a tool main body 20 that is rotated about an axis O, and a tip mounting seat 21 formed at an axial end of the tool main body 20. And two chips 23 which are detachably attached by attachment screws 22.

As shown in FIG. 5 and FIG.
Is a high-pressure sintered body 25 such as a CBN or diamond sintered body fixed at a constant thickness on a surface of a base metal 24 made of a cemented carbide or the like. , An arcuate cutting edge 26 and a straight cutting edge 27 are formed. The predetermined range from the distal end (inner peripheral end) P ₃ of the arcuate cutting edges 26, the junction surface of the ultra-high-pressure sintered compact 25 and the metal base 24 As the approaches the distal end P ₃ of the arcuate cutting edges 26 Convex curve part 2 approaching to the side
8 are formed. The amount of retreat δ in the thickness direction at the tip P ₃ of the convex curve portion 28 is
Is set to be less than 1 mm, more specifically, within 1 mm. If the thickness t of the ultrahigh-pressure sintered body 25 is equal to or more than the thickness t, the portion of the arc-shaped cutting edge 29 extending on the ultrahigh-pressure sintered body 22 and the base metal 2
1 due to the difference in wear rate between the upper part and the lower part.
And greater wear floating from the tip end P ₃ side base metal 21 of the ultra-high-pressure sintered compact 22, since ultra-high-pressure sintered body 22 is easily peeled off. The retreat amount δ and the convex curve portion 3
The radius of curvature R of 1 is appropriately selected according to the dimensions of the tool body on which the chip 20 is mounted. In the illustrated example, when the tool diameter is 80 mm, the retraction amount δ is 1 mm, and the radius of curvature R is 0.1 mm. 4
is set to mm.

The side surface 29 of the tip 23 located on the side opposite to the linear cutting blade 27 is formed on the surface 30 of the ultrahigh-pressure sintered body 25.
To the tip P of the arcuate cutting blade 26
_The inclined surface is formed so as to gradually approach the linear cutting blade 27 as the tip 23 moves away from the tip 23 toward the rear end side (upward in FIG. 5). The inclination angle θ of the side surface 29 with respect to the direction parallel to the linear cutting blade 27 is set in the range of 15 ° to 60 °.

As shown in FIG. 3 and FIG.
Is mounted on the chip mounting seat 21 with the arcuate cutting blade 26 positioned from the outer peripheral side to the distal end side of the tool body 20, and then tightened in the thickness direction by the mounting screw 22 mounted on the mounting hole 31. It is detachably attached to the tool body 20. Then, as shown in FIGS. 1 and 2, in a state where the tips 23 are attached to the tool body 20, the tip P ₃ of the arc-shaped cutting blade 26 of each tip 23 is positioned from the tip side of the tool body 20 in the direction of the axis O. When viewed from the bottom, the tool body 20 is separated from the axis O of the tool body 20 so as to draw an arc-shaped rotation trajectory Q having a diameter D about the axis O of the tool body 20. The straight cutting blade 27 is arranged parallel to the axis O of the tool body 20.
Here, 0.1 to 0.5 mm is selected as the range of the diameter D. Is large may interfere tip P ₃ between the arc-shaped cutting edge 26 in the range where the diameter D is less than 0.1 mm,
On the other hand, if the diameter D exceeds 0.5 mm, the portion without a cutting edge in the vicinity of the axis O of the tool main body 20 becomes too large, which has a considerable effect on the sphericity of the work surface of the work material. .

Further, as shown in FIGS. 1 and 3, the side surface 29 of the tip 23 is moved from the tip P ₃ of the arc-shaped cutting edge 26 to the tool body 20 in accordance with the inclination angle θ with respect to the direction parallel to the linear cutting edge 27. Of the tool body 20 toward the rear end side in the direction of the axis O of the
Is gradually retracted to the radially outer peripheral side.

Thus, in the ball end mill M _{1 having} the above-described configuration, the arc-shaped cutting blades 26 of the plurality of tips 23 are formed such that each tip P ₃ has a diameter of 0.1 mm or less around the axis O of the tool body 20. Since they are arranged so as to draw a 0.5 mm arc-shaped rotation trajectory, each tip 23
Of the tool main body 20 cuts substantially equally on the axis O. Therefore, the wear of the ultrahigh-pressure sintered body 25 does not progress unevenly to the specific chip 23, and the possibility that the cutting performance of the ultrahigh-pressure sintered body 25 is impaired at an early stage is small. Further, as the side surface 29 of the tip 23 moves toward the rear end side in the direction of the axis O of the tool body 20, the inclination angle θ with respect to the axis becomes
Since slide into progressively larger receding radially outer periphery of the tool body 20 in the range of 15 ° to 60 °, the tip P ₃ between the arc-shaped cutting edge 26 of each chip 23 is not close to the axis O of the tool body 20 However, the thickness of the tool main body 20 remaining between the side surfaces 29 of the tip 23 increases toward the rear end side in the direction of the axis O of the tool main body 20, and the rigidity of the tool main body 20 increases.
In this regard, below the ° the inclination angle θ is 15, for example, the side surface 29 if the interest provided parallel to the axis O of the tool body 20, wall thickness chip 23 of the tool body 20 that is left between the side surface 29 tip P ₃ equal to the gap amount between the stiffness reduction at the tip of the tool body 20 is remarkable. On the other hand, incline in reverse
When the angle θ exceeds 60 °, the side surface 29 is positioned after the direction of the axis O.
The end side intersects the rear end side of the arc-shaped cutting edge 26 and the straight cutting edge 27
As a result, these cutting edge lengths cannot be secured sufficiently,
The cutting depth of the ball end mill was limited accordingly
May be lost.

Since the tips 23 have the same shape and the same size, it is not necessary to prepare a plurality of types of the tips 23, so that the management of the tool is facilitated and the manufacturing cost of the tool is reduced. Further, a convex curved portion 2 is provided at the tip of the arc-shaped cutting blade 26.
8, the cutting edge strength at the tip of the arcuate cutting blade 26 is increased.

In this embodiment, a two-blade ball end mill is described as an example. However, the present invention is not limited to this, and a ball end mill having three or more chips is used. Also applies naturally.

[0015]

As described above, in the ball end mill of the present invention, the arc-shaped cutting blades of a plurality of chips are formed such that the inner peripheral end of each of them has a diameter of 0.1 mm to 0.1 mm around the axis of the tool body.
Since the arranged draw an arc of rotational path of 5 mm, without particular chip is uneven wear in the vicinity of the axis of the tool body, since the wear of each chip progresses substantially uniformly, excellent cutting The performance can be exhibited over a longer period than before. In addition, the side surface of the insert that faces the radially inner peripheral side of the tool body extends from the inner peripheral end of the arcuate cutting edge toward the rear end side in the axial direction of the tool main body, and the inclination angle with respect to this axis is 15 °.
° to 60 °, so that it retreats to the radially outer peripheral side of the tool main body. While the thickness of the tool body remaining between them is sufficiently ensured to prevent the rigidity of the tool body from decreasing , a sufficient cutting edge is also used for the insert.
Length to secure the depth of cut and perform smooth cutting.
It becomes possible. If all the chips have the same shape and the same size, it is not necessary to prepare a plurality of types of chips, so that the management of the tool is facilitated and the manufacturing cost of the tool is reduced. Further, by forming a convex curve portion within a certain range from the inner peripheral end of the arc-shaped cutting blade, the edge strength of the inner peripheral end of the arc-shaped cutting blade can be increased.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a tip end rotation center portion of a ball end mill according to an embodiment of the present invention in a radial direction of a tool main body.

FIG. 2 is a view as seen from an arrow II in FIG. 1;

FIG. 3 is a side view of the tip of the ball end mill of FIG. 1 viewed from the radial direction of the tool body.

FIG. 4 is a view from arrow IV in FIG. 3;

FIG. 5 is a plan view of a chip used in the ball end mill of FIGS.

FIG. 6 is a view from arrow VI in FIG. 5;

FIG. 7 is a diagram showing a tip of a conventional ball end mill as viewed from the side in a radial direction of a tool body.

FIG. 8 is a plan view of a chip used in the ball end mill of FIG. 7;

FIG. 9 is a view as viewed from the direction IX in FIG. 8;

[Explanation of symbols]

Reference Signs List 20 tool main body 23 tip 24 base metal 25 super-high pressure sintered body 26 arc-shaped cutting edge 28 convex curved part 29 side surface of chip M ₁ ball end mill O axis of tool body P ₃ tip of arc-shaped cutting edge (inner peripheral end)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23C 5/10 B23C 5/20

Claims (3)

(57) [Scope of request for utility model registration] 1. A tool main body which is rotated around an axis, and a tool main body mounted on an axial end of the tool main body.
With the above-mentioned throw-away tip, the above-mentioned throw-away tip positions the arc-shaped cutting edge from the outer peripheral side of the tool main body to the tip side, and is attached as a rake face with a surface connected to these arc-shaped cutting edges. In the ball end mill, the inner peripheral end of the arc-shaped cutting edge of each of the throw-away inserts is
Upon bottom view from the tip end side in the axial direction of the tool body, Ru is separated from the axis of the tool body so as to draw an arc of rotational path of the diameter 0.1~0.5mm about the axis of the tool body with a side facing the tool body radial inner peripheral side of the respective throw-away tip, toward the inner peripheral end of the arc-shaped cutting edge to the rear end side in the axial direction of the tool body, this axis
So that the inclination angle with respect to is in the range of 15 ° to 60 °.
A ball end mill which is retracted radially outward of a tool body. 2. The ball end mill according to claim 1, wherein all the throw-away tips are of the same shape and the same size. 3. Each of the throw-away chips is
The above arc-shaped cutting edge is formed on the ultra-high pressure sintered body fixed to the base metal.
The ultra-high pressure sintering formed and connected to these arc-shaped cutting edges
The surface of the body is the rake face, and each of the throw-away inserts has a certain range connected to the inner peripheral end of the arc-shaped cutting edge, and is convex toward the rotating direction of the tool body, and A convex curve portion is formed which approaches the joining surface side of the ultrahigh-pressure sintered body and the base metal toward the inner peripheral end of the away chip, and the arc-shaped portion located at the tip of the convex curve portion is formed. 3. The ball according to claim 1, wherein an amount of retreat of an inner peripheral end of the cutting blade in a thickness direction of the ultrahigh-pressure sintered body is less than a thickness of the ultrahigh-pressure sintered body. End mill.