JP2825035B2 - 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 provided with a cutting edge reaching a center of rotation of a tool body, in which an ultra-high-hardness sintered body and a high-hardness sintered body are laminated as a cutting edge tip. The present invention relates to a ball end mill employing a composite chip having a configuration.

[0002]

2. Description of the Related Art In recent years, as a cutting tool used for machining a high-hardness material such as a die, an ultra-high-hardness sintered body such as cubic boron nitride (hereinafter referred to as CBN) or diamond is used as a material for a cutting edge chip. Ball end mills using the same are being widely used. Here, in such a ball end mill,
Although the fixing method by brazing is generally adopted as a fixing means of the cutting edge chip, since the ultra-hard sintered body itself is difficult to braze, there is a problem that the joining strength of the cutting edge chip is insufficient as it is. There is. So, for example,
As described in Japanese Patent No. 2-181311, a composite chip in which a high hardness sintered body represented by a cemented carbide such as tungsten carbide (WC) is laminated on the back side of the ultra high hardness sintered body is used. There has been proposed a ball end mill having a configuration in which the joining strength of the cutting edge tip is ensured by brazing a portion of the composite tip constituted by the high hardness sintered body to a tool body.

[0003] This will be briefly described with reference to FIGS. 6 and 7. In the illustrated ball end mill 1, a tip insertion groove 3 is formed at a tip end of a tool main body 2 rotated around an axis O.
Is formed. A composite chip 6 in which an ultra-high hardness sintered body 4 such as CBN is sandwiched between the chip insertion grooves 3 by a high-hardness sintered body 5 such as a cemented carbide, It is mounted with its surface exposed in the direction of rotation of the tool main body 2 (the direction of arrow A in the figure), and the end face 6a of the composite chip 6 facing the tool tip side and the surface of the ultra-hard sintered body 4 Of the composite chip 6 is secured by brazing and fixing the high hardness sintered body 5 to the wall surface of the chip insertion groove 3.

In the above-described ball end mill 1, the ultra-hard sintered body 4 is cut into a predetermined shape by grinding or the like, so that each cutting edge 7 is viewed from the front along the axis O of the tool body 2. in which it is curved so as to draw a convex curve, yet the inner peripheral edge 7a of the cutting edges 7 are caused to coincide with the exact center of rotation P _0.

[0005]

However, in the above-mentioned conventional ball end mill 1, since the cutting speed on the inner peripheral side is smaller than the cutting speed on the outer peripheral side of the tool body 2, the cutting applied to the cutting edge 7 is reduced. The resistance increases toward the inner peripheral side of the tool body 2. Especially in the vicinity of the center of rotation P ₀ is the cutting resistance is extremely high for the cutting speed is substantially zero, and also so crushed rather than cut the workpiece the cutting action. For this reason, the conventional ball end mill 1 is liable to be damaged at the inner peripheral end portion of the cutting edge 7 and the tool life is likely to be shortened, and the work surface of the work material is damaged by the action of crushing the center of rotation. However, there is a disadvantage that the surface roughness is likely to deteriorate. Also, in forming the cutting edge 7, the disadvantage them takes time in processing the respective inner peripheral end 7a while bending rotation center higher demand for machining accuracy because P ₀ must butt over a predetermined shape there were. This point is a disadvantage that also occurs during repolishing. The present invention has been made under such a background, and a ball end mill which can prevent chipping at the center of rotation of a cutting edge, improve tool life, prevent damage to a machined surface, and can be easily manufactured. The purpose is to provide.

[0006]

In order to solve the above-mentioned problems, a ball end mill according to the present invention has a tip insertion groove formed at a tip end of a tool body rotated around an axis, and the tip insertion groove has an extremely high height. A composite chip formed by laminating a high-hardness sintered body and a high-hardness sintered body is brazed and joined with the surface of the ultra-high-hardness sintered body exposed in the rotating direction of the tool body. A ball end mill in which an intersection ridge line between an end face of the composite tip facing the tool tip side and a surface of the ultra-high-hardness sintered body is a cutting edge, wherein the composite tip has an inner peripheral end whose tool body is the tool body. A main blade tip protruding to the opposite side beyond the center of rotation of the tool body, and an inner peripheral end thereof are provided separately with a sub-blade tip separated from the center of rotation of the tool body, and the inner peripheral end of the main blade tip is The amount of protrusion of the tool body from the center of rotation is D rotation diameter of the outer circumference end of the cutting edge
Is set in the range of 0.5 mm to D / 5 mm,
On the inner peripheral side of the ridge portion where the cutting edge of the main blade tip is formed, a notch portion which is depressed from the surface of the ultra-high hardness sintered body of the main blade tip and is separated from the rotation center of the tool main body. Is formed on the inner peripheral side of the cutting blade by the notch, and a thinning blade is formed at a distance from the center of rotation of the tool main body, and an inner peripheral end of the cutting edge of the sub-blade tip with respect to an inner peripheral end of the thinning blade. Is set within 1.5 mm.

[0007]

According to the above construction, the thinning blade is formed on the inner peripheral side of the cutting edge of the main blade tip so that the cutting edge of the main blade tip is separated from the center of rotation of the tool body, while the cutting edge of the auxiliary blade tip is formed. Since the inner peripheral edge of the cutting blade is also separated from the center of rotation of the tool body, the cutting resistance at the center of rotation of the tool main body is greatly reduced compared to the conventional example where the inner peripheral edge of the cutting blade coincides with the center of rotation. Defective cutting edge is prevented. In addition, the inner peripheral edge of the cutting blade does not have the effect of crushing the work material, and the surface roughness of the machined surface of the work material is improved. In addition, since it is not necessary to make the cutting edge coincide with the center of rotation, it is easy to form the cutting edge.

Furthermore, since the inner peripheral side of the cutting edge of each chip does not protrude beyond the center of rotation to the opposite side, the cutting load applied to the cutting edge is such that the ultra-high hardness sintered body is separated from the high hardness sintered body. Without acting, peeling of the ultra-high hardness sintered body is prevented. In this case, cutting is not performed because there is no cutting edge at the center of rotation.However, in reality, the uncut portion is shifted from the center of rotation by the radial feed of the ball end mill, and eventually the cutting is performed. There is no problem because it will be scraped off with a blade.

Here, in the above configuration, the amount of protrusion of the inner peripheral end of the main blade tip from the rotation center of the tool body is 0.5 mm.
ＤD / 5 mm is set for the following reason. That is, it is extremely difficult to set the protrusion amount to less than 0.5 mm due to an error in brazing and fixing the main blade tip,
If the distance is set to D / 5 mm or more, the cutting range of the main cutting edge is excessively enlarged, the cutting range of the sub cutting edge is narrowed, and the cutting resistance of the main cutting edge is excessively increased. Further, the distance between the inner peripheral end of the sub-blade tip and the inner peripheral end of the thinning blade is set to be within 1.5 mm, even when the distance exceeds 1.5 mm. This is because the difference in the cutting resistance that each chip bears is significantly increased due to the narrowing.

The distance of the outer peripheral end of the thinning blade of the main blade tip from the center of rotation of the tool body is appropriately determined according to the rotational diameter D of the outer peripheral end of the cutting blade of the main blade tip. It is desirable to set it in the range of 0.1 to 1.0 mm. If the thickness is less than 0.1 mm, the effect of avoiding the crushing action of the work material due to the provision of the thinning blade may not be sufficiently exerted.
If it exceeds 0 mm, the region where the cutting action does not occur in the center of rotation of the tool body is excessively enlarged, which may hinder machining.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, the overall configuration of the ball end mill according to the present embodiment will be described with reference to FIGS. As shown in these figures, the ball end mill 10 of this embodiment
Are formed with a tip insertion groove 12, 13 at a tip end of a cylindrical tool body 11, and these tip insertion grooves 12, 13 are formed.
Are mounted with four cutting blade tips 14. The front of each of the chip insertion grooves 12, 13 is largely cut away toward the tip and the outer periphery of the tool body 11 so that the tip pocket 1 is cut out.
5 and 16.

The cutting edge tip 14 is provided in the tip insertion groove 12, 1
3, straight blade tips 17, 18 attached to the rear end side,
The straight blade tips 17 and 18 are provided separately from curved blade tips 19 and 20 which are attached to the distal ends. Each of the straight blade tips 17 and 18 is formed by forming a single high-hardness sintered body such as a cemented carbide into a rectangular flat plate shape, and is formed at an intersection ridge line between a rake face and a flank face. Cutting blade 1
7a and 18a are inserted into the tool body 1 from the chip insertion grooves 12 and 13.
1 and projecting from the tool axis O in parallel to the tool axis O and by an equal amount from the tool axis O,
13 and fixed by brazing.

On the other hand, as shown in more detail in FIG. 1, FIG. 2 and FIG. 5, each of the curved blade tips 19 and 20 is made of a super-hard sintered body 21 or 22 such as CBN and a high-hardness sintered body such as a cemented carbide. This is a composite chip formed by laminating sintered bodies 23 and 24, and the surfaces 21a and 22a of the ultra-hard sintered bodies 21 and 22, respectively, are rotated in the direction of rotation of the tool body 11 (the direction of arrow A in FIG. 2). Insertion groove 1 with exposed toward
2 and 13 and the high-hardness sintered bodies 23 and 2
4 is integrated with the tool body 11 by being brazed into the chip insertion grooves 12 and 13.

An arc-shaped intersection is formed between the end surfaces 19a, 20a of the curved blade tips 19, 20 facing the tool body front end and the flat surfaces 21a, 22a of the ultra-hard sintered bodies 21, 22. Cutting blades 25 and 26 are formed. These cutting blades 25 and 26 are arranged so as to extend straight in the radial direction of the tool main body 11 in a front view (FIG. 2) from the axial direction of the tool main body 11, and the cutting edges 25 and 26 are arranged around the axis O of the tool main body 11. Are arranged so as to draw a hemispherical rotation locus. Further, as shown in FIGS. 4 and 5, the axis O of the tool main body 11 is provided on the outer peripheral side of the cutting blades 25 and 26.
The straight blades 27 and 28 extending in parallel along are formed, and these straight blades 27 and 28 are directly connected to the cutting blades 17a and 18a of the straight blade tips 17 and 18 described above. The radial rake angle and the axial rake angle of each of the cutting edges 25 to 28 are both set to 0 °.

[0015] Then, as shown in FIGS. 1 to 3, of each song blade tip 19, 20, opposite the inner peripheral edge 19b of one of the songs blade tip 19 beyond the rotation center P ₀ of the tool body 11 The curved blade tip 19 is used as a main blade tip in the present embodiment by a predetermined amount e (see FIG. 1). In contrast the inner peripheral end 20b of the other songs blade tip 20 is caused to apart from the rotation center P ₀ by the projecting amount e equivalent of the songs blade tip 19, thereby the songs blade tip 20 sub in this embodiment It is a blade tip.

Here, the value of the protrusion amount e is determined by
Although it is appropriately changed according to the rotational diameter D of 28 (see FIG. 4), an appropriate range is 0.5 mm to D / 5 mm. It is often difficult to make the protrusion amount e smaller than 0.5 mm in terms of accuracy at the time of brazing, while D / 5 mm
When the cutting edge is larger than the cutting edge, the cutting area of the curved blade tip 19 serving as the main blade tip is excessively enlarged toward the side of the curved blade tip 20 serving as the auxiliary blade tip, and the cutting area of the curved blade tip 20 by the cutting blade 26 is increased. Greatly retreats to the outer peripheral side of the tool main body 11, whereby only the cutting resistance applied to the curved blade tip 19 remarkably increases, which may cause inconveniences such as generation of chatter vibration and extension of the life difference between the curved blade tips 19 and 20. Because it is big.
Incidentally, in the illustrated example, the protrusion amount e is set to 1.0 mm with respect to the rotation diameter D = 25 mm.

On the inner peripheral end side of the ridge portion where the cutting blade 25 of the curved blade tip 19 is formed, a cutout portion 29 which is depressed from the surface 21a of the ultra-hard sintered body 21 of the curved blade tip 19 is formed. The notch 29 forms a thinning blade 30 on the inner peripheral side of the cutting blade 25, which is separated from the rotation center P ₀ of the tool body 11.
Are formed. The notch 29 has a bottom surface 29 a inclined at a constant thinning angle θ with respect to the cutting blade 25 in a front view (FIG. 3) from the axial direction of the tool body 11, and a surface 21 a of the ultra-hard sintered body 21. It has a side wall surface 29b inclined at a constant thinning angle φ with respect to the tool axis O in a side view (FIG. 1).
2 after brazing. The above-mentioned thinning angles θ and φ are appropriately changed according to cutting conditions and the like, but θ is preferably in the range of 5 ° to 25 °, more preferably 10 ° to 15 °, and φ is preferably Is in the range of 20 ° to 70 °, more preferably 40 ° to 4 °.
A range of 5 ° is preferably used. Incidentally, in the illustrated example, θ = 30 ° and φ = 45 ° are set.

The distance g (see FIG. 3) of the outer peripheral end P ₁ of the thinning blade 30 from the rotation center P ₀ is appropriately changed according to the above-mentioned rotation diameter D, cutting conditions, and the like. It is desirable to set the distance in the range of 0.1 mm to 1.0 mm as much as possible. May not be able to sufficiently reduce the crushing effect of the workpiece in the inner peripheral portion of the cutting edge 25 when less than 0.1 mm, while the cutting in the vicinity of the rotation center P ₀ exceeds a 1.0mm This is because a region where no action occurs may be excessively enlarged and hinder processing. Also, the retreat amount h of the thinning blade 30 from the cutting blade 25.
Is preferably in the range of 0.05 to 1 mm.
Incidentally, in the illustrated example, h = 0.3 mm.

As shown in FIG. 1, the curved blade tips 19, 20
Chamfered portions 31 and 32 for preventing the cutting edges 25 and 26 from being lost are formed at the front end of the cutting edges 25 and 26.
Inner peripheral ends of the thinning blades 30, more precisely, the inner peripheral end P ₂ of the thinning blade 30.
It is separated by a predetermined amount f the inner peripheral end P ₃ Toga径direction of the cutting edge 26 and. The distance f is also appropriately determined according to the rotation diameter D and the like in the same manner as the protrusion amount e described above, but the appropriate range is 1.5 mm or less. The distance f is 1.5mm
Is exceeded, as long as the protrusion amount e is obeyed,
The distance k between the inner peripheral end P ₃ of the cutting blade 26 of the curved blade tip 20 and the rotation center P ₀ is excessively increased, and the cutting area of the cutting blade 26 retreats largely toward the outer peripheral side of the tool body 11, whereby This is because only the cutting resistance applied to the curved blade tip 19 is significantly increased, which may cause inconveniences such as generation of chatter vibration and extension of the life difference between the curved blade tips 19 and 20. By the way,
The distance k is set to 1.3 mm to 1.5 mm.

The open angle α of the chamfers 31 and 32 is 9
0 °, and the opening angle α is the axis O of the tool body 11.
Are distributed symmetrically with respect to the direction along. The thinning blade 30 cut out by the chamfer 30
Distance j in the radial direction of the rotation center P ₀ of the inner peripheral end P ₂ and the tool body 11 in the range of 0.3~0.8mm are suitably used in,
In the illustrated example, it is 0.6 mm.

In the ball end mill 10 configured as described above, the thinning blade 30 is formed on the inner peripheral side of the cutting blade 25 of the curved blade tip 19 serving as the main blade tip, so that the inside of the cutting blade 25 is formed. While the circumferential side is separated from the rotation center P ₀ , the curved blade tip 20 serving as the sub-blade tip
Since the inner peripheral portion of the cutting blade 26 is also separated from the rotation center P ₀ , the cutting resistance at the rotation central portion of the tool body 11 is smaller than that when the inner peripheral edge of the cutting blade is aligned with the rotation center P _0. Thus, the cutting edges 25 and 26 are prevented from being lost. Further, the inner peripheral ends of the cutting blades 25 and 26 do not have the effect of crushing the work material, and the surface roughness of the machined surface of the work material is improved.

[0022] Moreover, the processing is easy since it is not necessary to match each of the inner peripheral portion and the rotation center P ₀ is the formation of the cutting edges 25 and 26. Furthermore, the surface 21 of the super-hardened sintered bodies 21 and 22 which are the rake faces of the cutting blades 25 and 26
Since the flat surfaces a and 22a are formed, the formation and re-polishing of the cutting blades 25 and 26 can be performed extremely easily as compared with the conventional example in which the cutting blades are curved in a convex curve.

Furthermore, since the inner peripheral portion of the cutting edge 25 by thinning edge 30 is formed on the inner peripheral side of the cutting edge 25 is spaced apart from the rotation center P _0, ultra high-hardness sintered body 2
Peeling from the high-hardness sintered body 23 is also prevented. That is, the cutting blade 25 is provided without provision of the thinning blade 30.
The inner peripheral end portion when extended to straighten the opposite side beyond the rotation center P ₀ of the relative rotational direction overhang region beyond the center of rotation P ₀ for cutting 25 of the tool body 11 is reversed. For this reason, the cutting load applied to the cutting blade 25 also acts in the direction from the cutting blade 25 toward the tip pocket 15, thereby changing the ultra-hard sintered body 21 to the high-hardness sintered body 23.
A force is generated to separate the cutting edge from the cutting edge, and the cutting edge is easily damaged. Because the inner peripheral portion of the cutting edge 25 by thinning edge 30 in this respect this embodiment is away from the rotation center P _0, all the cutting load applied to the cutting edge 25 is ultra high hardness sintered 21 high hardness sintered body 23 to prevent the ultra-hard sintered body 21 from peeling off, further improving the tool life, and deteriorating the surface roughness due to the roughened work surface due to the damaged cutting blade 25. Nor.

Further, according to the present embodiment, the curved blade tip 19
Projecting amount e from the rotational center P ₀ of the inner peripheral edge, and the cutting edge 26 of Kyokuha chip 20 from the inner peripheral end P ₂ of the thinning edge 30
By length f to the inner peripheral end P ₃ of is set within the above-described range, since undue expansion of the difference between the cutting resistance applied to Kyokuha chip 19, 20 is prevented, by imbalance of cutting resistance The occurrence of chatter vibration is prevented and the processing accuracy is further improved, and the difference in life between the chips 19 and 20 is not excessively increased, so that the chips 19 and 20 can be used without waste and the economy is improved. In this regard, since in particular the ball end mill to which the present embodiment has the characteristic that the chip thickness from the rotation center P ₀ as away to the outer peripheral side is increased,
As the cutting area of each curved blade tip 19 expands toward the outer periphery of the curved blade tip 20, the imbalance of the cutting resistance becomes more remarkable. Therefore, it is highly necessary to restrict the protruding amount e and the distance f to the above-described ranges.

[0025] In the case of the ball end mill of the present embodiment, since there is no cutting edge to the rotation center P ₀ of the tool body 11,
Although so that cutting is not performed at such a part, the fact that the non-cutting portion by the feed in the radial direction of the tool body 11 deviates from the rotation center P ₀ is uncut portion end is at the cutting edge 25, 26 There is no problem because it will be cut off.

Here, in order to separate the cutting blade 25 from the rotation center P _0, it is conceivable to separate the inner peripheral end 19 b of the curved tip 19 from the rotation center P ₀ as in the case of the curved tip 20. but thinning edge 3 to form a dare songs blade bother notch 29 on which is projected to the opposite side of the inner peripheral end portion 19b beyond the rotation center P ₀ of the chip 19 in this embodiment
0 disposed, thereby by separating the cutting blade 25 from the rotation center P _0. This is for the following reason.

[0027] That is, the position of Kyokuha chips 19 and 20, in order to vary relatively greatly with error in these brazing, to separate the inner peripheral end portion 19b of the Kyokuha chip 19 from the rotation center P ₀ If thinning blade 3
There is a possibility that spacing amount g from the rotation center P ₀ of the outer peripheral end P ₁ of 0 varies greatly, Therefore, it becomes necessary cautious brazing work Kyokuha chip 19. The Kyokuha chip 19 to space the cutting edge 25 reliably from the rotation center P ₀
The amount of separation from the rotation center P ₀ must be set large in consideration of an error. However, in this case, the cutting edge 25 may be significantly separated from the rotation center P ₀ . The uncut area is significantly enlarged. On the other hand, in the case of the present embodiment, the center of rotation P ₀ of the inner peripheral end of the curved blade tip 19 only changes the position of the outer peripheral end P ₁ of the thinning blade 30 due to an error in forming the notch 29.
The amount of protrusion e of the do not relate to the position of the cutting edge 25, there is no possibility that uncut region distance amount g is increased unnecessarily in the outer peripheral end P ₁ of the thinning edge 30 by brazing error unduly enlarge Therefore, the brazing operation can be easily performed, and the manufacture of the ball end mill is further facilitated.

The example shown in FIGS. 1 to 5 show a preferred embodiment of the present invention only, for example, the central rotational those like cutting edge 25 the shape of the notch 29 of recessed spherical P ₀
Any shape can be included as long as it can be separated from the object. In addition, the thickness and the like of the ultra-hard sintered bodies 21 and 22 in the curved blade tips 19 and 20 can be appropriately changed as needed, and the straight blade tips 17 and 18 are not necessarily required.

[0029]

As described above, according to the present invention, since the inner peripheral side of the cutting edge is separated from the center of rotation of the tool body, the cutting resistance on the inner peripheral side of the cutting edge is reduced, and the loss of the cutting edge is reduced. As a result, the tool life is improved, and the inner peripheral end of the cutting edge does not have the effect of crushing the work material, so that the surface roughness of the machined surface of the work material is improved.

Further, since it is not necessary to make the cutting edge coincide with the center of rotation, it is easy to form the cutting edge. Moreover, in particular, by protruding the inner peripheral end of the cutting blade tip to the opposite side beyond the center of rotation, forming a notch and providing a thinning blade,
Since the cutting edge is separated from the center of rotation, the uncut area in the center of rotation does not greatly increase due to an unnecessarily increased amount of separation of the cutting edge from the center of rotation due to an error during brazing. Therefore, the brazing operation can be easily performed, and the manufacture of the ball end mill is further facilitated.

In addition, the amount of protrusion of the inner peripheral end of the main blade tip from the center of rotation and the distance from the inner peripheral end of the thinning blade to the inner peripheral end of the cutting edge of the sub-tip are restricted to appropriate ranges. This prevents the difference in cutting resistance applied to these chips from increasing, thereby preventing chatter vibration due to cutting force imbalance, further improving machining accuracy, and increasing the life difference between chips. It is possible to use both chips without waste and economic efficiency is increased.

Further, since the inner peripheral end of the cutting blade does not exceed the center of rotation, the cutting load applied to the cutting blade does not act in the direction of separating the ultra-hard sintered body from the high-hardness sintered body, and Peeling of the sintered body is prevented, the tool life is also improved in this respect, and the work surface of the work material is not roughened by the damaged cutting blade, and the surface roughness of the work surface is not deteriorated.

[Brief description of the drawings]

FIG. 1 is a side view showing a state in which a tip end portion of a ball end mill according to an embodiment of the present invention is viewed from a surface side of a super hard sintered body of a main blade tip.

FIG. 2 is a front view of the ball end mill shown in FIG. 1 as viewed from an axial direction.

FIG. 3 is an enlarged view showing an inner peripheral side of a main blade tip in FIG. 2;

FIG. 4 is a side view showing an overall configuration of a ball end mill according to one embodiment of the present invention.

FIG. 5 is a view from arrow V in FIG. 4;

FIG. 6 is a side view of a conventional ball end mill.

FIG. 7 is a view as seen from the direction of the arrow VII in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Ball end mill 11 Tool main body 12, 13 Tip insertion groove 19 Curved blade tip (main blade tip) 20 Curved blade tip (sub-blade tip) 21, 22 Ultra high hardness sintered body 23, 24 High hardness sintered body 25, 26 cutting edge 25a, the 26a cutting the inner peripheral edge 29 notch 30 thinning edge O of the tool body axis P ₀ rotation center P ₁ of the thinning edge of the outer circumference end P ₂ thinning edge inner peripheral end P ₃ of the auxiliary cutting edges tip of the cutting edge Inner edge

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuo Takasaki Gifu Prefecture, Kochi-cho, Gifu Prefecture 1528 Nakaiden, Yokoi, Mitsubishi Materials Corporation Gifu Works (72) Inventor Yuichi Kodera Kobe-cho, Anpachi-gun, Gifu 1528 Nakashinda, Yokoi, Mitsubishi Materials Corporation Gifu Works (58) Field surveyed (Int. Cl. ⁶ , DB name) B23C 5/10

Claims (2)

(57) [Claims] 1. A tip insertion groove is formed at a tip end of a tool body rotated about an axis, and an ultra-high-hardness sintered body and a high-hardness sintered body are laminated at least on the tip end side of the tip insertion groove. The composite tip is brazed and joined in a state where the surface of the ultra-high hardness sintered body is exposed in the rotation direction of the tool body, and the end face of the composite tip facing the tool tip side and the ultra-high hardness A ball end mill having a cutting edge at a crossing ridge line portion with a surface of a sintered body, wherein the composite tip has a main blade tip whose inner peripheral end projects to the opposite side beyond the center of rotation of the tool body. And a sub-blade tip whose inner peripheral end is separated from the rotation center of the tool main body. The amount of protrusion of the inner peripheral end of the main blade tip from the rotation center of the tool main body is the cutting edge. When the rotation diameter of the outer peripheral end of D is D, 0. mm to D / 5 mm, a notch depressed from the surface of the super-hardened sintered body of the main blade tip is provided on an inner peripheral side of a ridge portion where the cutting edge of the main blade tip is formed. A notch is formed on the inner peripheral side of the cutting blade by the notch, and a thinning blade is formed at a distance from the rotation center of the tool body. A ball end mill characterized in that the distance between the ends is set within 1.5 mm. 2. An amount of separation of an outer peripheral end of a thinning blade of the main blade tip from a rotation center of the tool body is 0.1 to 1.0.
2. The ball end mill according to claim 1, wherein the diameter is set in a range of mm.