JP2002144136A - Throwaway ball end mill, and throwaway tip used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a throwaway ball end mill having a throwaway tip accurately and firmly installable thereon. SOLUTION: The abutting part 8 of a body 3 comprises a horizontal abutting part 8a and a pair of inclined abutting parts 8b and 8b formed aslant from both end parts thereof. The bottom surface part 9 of the throwaway tip 2 comprises a horizontal bottom surface part 9a and a pair of inclined bottom surface parts 9b and 9b formed aslant from both end parts thereof. The horizontal bottom surface part 9a is allowed to abut on the horizontal abutting part 8a, and the inclined bottom surface parts 9b and 9b are allowed to abut on the inclined abutting parts 8b and 8b to position the throwaway tip 2 to accurately install the throwaway tip 2 on the body 3. Since the horizontal bottom surface part 9a is allowed to surface-abut on the horizontal abutting part 8a, and the throwaway tip 2 is arrested between the inclined abutting parts 8b and 8b, the throwaway tip 2 can be firmly fixed to the body 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type ball end mill and a throw-away tip used in the throw-away type ball end mill.

[0002]

2. Description of the Related Art In a conventional throw-away type ball end mill, as shown in FIGS.
A pair of holding portions 102a and 102b are provided at the tip of
The holding part 102a, 102
b and the throw-away tip 10
3 is a contact portion 1 having one end side formed linearly on the main body 101.
04. In this abutting state, the screw 105 is inserted into the screw insertion hole 106 provided in the one holding portion 102a, passes through the screw passage hole 107 provided in the throw-away tip 103, and is provided in the other holding portion 102b. By being screwed into the fastening hole 108, the holding portion 102
The indexable insert 103 is sandwiched and fixed between a and 102b.

[0003]

However, in this throw-away type ball end mill, since the contact portion 104 of the main body 101 is formed in a straight line, the positioning thereof becomes unstable when the throw-away tip 105 is attached. , Mounting accuracy deteriorates. Therefore, there is a problem that high-precision processing is difficult.

[0004] For this reason, as shown in FIG.
A throw-away type ball end mill is described in which 10, 110 and contact portions 112, 112 of a main body 111 contacting the ends 110, 110 are respectively formed in a V-shaped tapered shape toward the rear. . According to such a throw-away type ball end mill, the ends 110 and 110 of the throw-away tip 109 are connected to the contact portion 1 of the main body 111.
By screwing the screw 113 in a state of contact with the main body 11, 112,
The indexable insert 109 is positioned by being restrained by the first contact portions 112, 112.

However, in this throw-away type ball end mill, it is difficult to form the end portions 110, 110 of the throw-away tip 109 and the abutment portions 112, 112 of the main body 111 with high precision, so that the throw-away tip is used. The end portions 110, 110 of the main body 109 and the contact portions 112, 112 of the main body 111 are likely to come in contact with two points, and cannot be brought into close surface contact. Therefore, there is a problem that the throw-away tip 109 cannot be firmly fixed and high-precision processing cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has as its object to provide a throw-away type ball end mill in which a throw-away tip can be accurately and firmly attached.

[0007]

In order to achieve this object, a throw-away type ball end mill according to claim 1 is provided with a pair of holding portions formed by extending a slit from a tip portion along an axial direction. A body having a contact portion provided at the end of the slit, a screw insertion hole formed through one of the holding portions and a screw fastening hole formed at the other, and abutted against the contact portion; A throw-away tip having a bottom surface portion, a screw passage hole communicating with the screw insertion hole and the screw fastening hole when the bottom surface portion abuts on the contact portion, the screw insertion hole and the screw passage hole. A screw that penetrates the hole and is screwed into the screw fastening hole, wherein the abutting portion of the main body has a horizontal abutting portion formed to be substantially perpendicular to the axis of the main body; One that is installed continuously from both ends of the contact part A pair of inclined contact portions, and the bottom portion of the throw-away tip has a horizontal bottom portion formed so as to contact the horizontal contact portion, and is inclined from both ends of the horizontal bottom portion. And a pair of inclined bottom portions formed so as to be in contact with at least a part of the inclined contact portion.

According to the throw-away type ball end mill of the first aspect, the throw-away tip is held and fixed by the holding portion provided on the main body. In this case, the throw away tip is sandwiched between a pair of holding portions formed on the main body, and the bottom portion of the throw away tip is
The abutting portion is in contact with a contact portion provided at the end of the holding portion. The bottom surface of the throw-away tip has a horizontal bottom surface abutting against the horizontal abutting portion of the abutting portion, while the inclined bottom portions formed at both ends of the horizontal bottom portion have an inclined abutting portion of the abutting portion. Contacted at least in part. By this contact, the throw-away tip is restrained and positioned by the horizontal contact portion and the inclined contact portion of the contact portion. Then, the screw is screwed into the screw fastening hole of the other holding portion while passing the screw from the screw insertion hole of one holding portion to the screw passage hole of the throw-away tip, whereby the throw-away tip is positioned at a predetermined position. In this state, it is clamped and fixed by the clamping section.

According to a second aspect of the present invention, there is provided a throw-away type ball end mill according to the first aspect, wherein the pair of inclined abutting portions of the main body extend from the horizontal abutting portion to a tip end side of the main body. The pair of inclined bottom surfaces of the throw-away tip are inclined corresponding to the inclined contact portions of the main body.

A throw-away type ball end mill according to a third aspect of the present invention is the throw-away type ball end mill according to the first or second aspect, wherein the inclined bottom portion is one of a horizontal bottom portion of the throw-away tip and another inclined bottom portion. Are both 5 ° or more and 45 ° or less.

According to a fourth aspect of the present invention, there is provided a throw-away type ball end mill according to any one of the first to third aspects, wherein the throw-away tip is formed in a plate shape having a predetermined throw-away tip width. The width of the horizontal bottom portion of the throw-away tip is 2 to the width of the throw-away tip.
5% or more and 75% or less.

According to a fifth aspect of the present invention, there is provided a throw-away type ball end mill according to any one of the first to fourth aspects, wherein the bottom portion of the throw-away tip is connected to the contact portion of the main body. When contacted, the center of the screw insertion hole formed in one of the holding portions is the center of the screw fastening hole formed in the other of the holding portion and the center of the screw passage hole of the throw-away tip. More eccentric to the rear end of the body.

According to the throw-away type ball end mill according to the fifth aspect, it operates in the same manner as the throw-away type ball end mill according to any one of the first to fourth aspects, and the bottom surface of the throw-away tip is formed on the main body. In the state of being in contact with the contact portion, the center of the screw insertion hole formed in the holding portion is eccentric to the rear end side of the main body with respect to the centers of the screw fastening hole and the screw passage hole. Therefore, from this state, when the screw is screwed into the screw fastening hole while passing through the screw passage hole from the screw insertion hole, the screw presses the bottom portion of the throw-away tip against the contact portion of the main body, and the screw is pressed. In the state,
The indexable insert is fixed to the holding portion.

According to a sixth aspect of the present invention, there is provided a throw-away type ball end mill according to the fifth aspect, wherein the screw insertion hole formed in one of the holding portions is formed in a countersunk shape. A plate portion provided on the side opposite to the slit, and a body portion continuously connected to the slit side from the plate portion, and the bottom surface of the throw-away tip to the contact portion of the main body. When the portion is abutted, the center of the countersunk portion of the screw insertion hole formed in one of the holding portions is the screw fastening hole formed in the other of the holding portions and the throw away tip has It is eccentric to the rear end side of the main body from the center of the screw passage hole.

According to the throw-away type ball end mill of the sixth aspect, it operates in the same manner as the throw-away type ball end mill of the fifth aspect, and additionally, the bottom portion of the throw-away tip abuts on the abutting portion of the main body. In this state, the center of the countersunk portion of the screw insertion hole formed in the holding portion is more eccentric to the rear end side of the body than the centers of the screw fastening hole and the screw passage hole. Therefore, from this state, when the screw is screwed into the screw fastening hole while passing through the screw passage hole from the screw insertion hole, the screw presses the bottom portion of the throw-away tip against the contact portion of the main body, and the screw is pressed. In this state, the indexable insert is fixed to the holding portion.

The indexable insert according to claim 6 is
It is used for the throw-away type ball end mill according to any one of claims 1 to 5.

[0017]

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view of a throw-away type ball end mill 1 according to a first embodiment of the present invention. This throw-away type ball end mill 1 comprises a throw-away tip 2 having a cutting edge 2a, a main body 3 for holding and fixing the throw-away tip 2 and a screw 4, and is provided with a milling machine and a machining center via a holder (not shown). It is a tool to which the rotational force of a processing machine such as is transmitted to cut metal or the like.

FIG. 2A is a partial sectional side view of the throw-away type ball end mill 1, showing a state in which the bottom surface 9 of the throw-away tip 2 is in contact with the contact portion 8 of the main body 3. FIG. 2B is a partial side sectional view of the throw-away type ball end mill 1, and shows a state in which the throw-away tip 2 is fixed to the holding portions 5a and 5b by screws 4. 2A and 2B, illustration of the rear end of the main body 3 is omitted.

As shown in FIG. 2A, the main body 3 is provided with a pair of holding portions 5a, 5b for holding the throw-away tip 2 by extending a slit from the front end thereof to a predetermined length. Is provided. A screw insertion hole 6 is formed through one of the holding portions 5a. The screw insertion hole 6 has a countersink-shaped countersunk portion 6a for guiding the screw 4 and a body portion 6b extending downward from the countersunk portion 6a. The inner diameter of the body portion 6b will be described later. It is formed slightly larger than the outer diameter of the shaft portion 4b of the screw 4 (see FIG. 2B).
In the other holding portion 5b, a screw fastening hole 7 in which a female screw is threaded is formed through the inner surface. The center axis M of the screw insertion hole 6 and the center axis N of the screw fastening hole 7 are located on the axis L of the main body 3 (see FIG. 3).

At the end of the slit formed at the tip of the main body 3 (on the right side in FIG. 2A), there is formed a contact portion 8 with which the bottom surface 9 of the throw-away tip 2 contacts. .
Here, with reference to FIG. 3, the contact portion 8 and the throw-away tip 2 contacting the contact portion 8 will be described.

FIG. 3 is a partial cross-sectional view taken along the line III-III in FIG. The contact portion 8 is formed in the main body 3 of the throw-away type ball end mill 1 in a shape symmetrical with respect to the axis L of the main body 3. The contact portion 8 includes a horizontal contact portion 8a and inclined contact portions 8b, 8b.
The horizontal contact portion 8a is arranged at the center of the contact portion 8, and is formed in a straight line substantially perpendicular to the axis L of the main body 3. From both ends of the horizontal contact portion 8a, a pair of inclined contact portions 8b, 8b are formed to be inclined at a predetermined inclination angle α toward the tip end side (left side in FIG. 3) of the main body 3.

The throw-away tip 2 is formed in a plate shape whose outer shape is symmetrical with respect to the axis of symmetry P, and its width (width of the throw-away tip) is a width W. A screw passage hole 10 for allowing the screw 4 to pass therethrough is formed substantially in the center of the plane portion of the throw-away tip 2. The central axis O of this screw passage hole 10 (see FIG. 2A) It is located on the axis of symmetry P of the throw-away tip 2. Also,
A cutting edge 2a is provided at the tip of the throw-away tip 2 formed in an arc shape (the left side in FIG. 3) and the side (the upper side or the lower side in FIG. 3) linearly extending from the tip. Is formed.

At the rear end (right side in FIG. 3) of the throw-away tip 2, a bottom surface 9 for positioning the throw-away tip 2 by being brought into contact with the contact portion 8 of the main body 3 is formed. . The bottom part 9 of the throw-away tip 2
Is a horizontal bottom portion 9 abutting on the horizontal contact portion 8a of the main body 3.
a and a pair of inclined bottom surfaces 9 b, 9 b of which a part is in contact with the inclined contact portions 8 b, 8 b of the main body 3. The horizontal bottom surface portion 9a is arranged at the center of the bottom surface portion 9 and is formed in a straight line substantially perpendicular to the axis of symmetry P of the throw-away tip 2. The width x of the horizontal bottom surface portion 9a is in a ratio of 25% to 75% with respect to the width W of the throw-away tip.

The inclined bottom portions 9b, 9b are connected to the horizontal bottom portion 9a.
Are formed at a predetermined inclination angle (outside angle) β from both end portions toward the tip end side (left side in FIG. 3) of the throw-away tip 2. In this way, the inclined bottom surfaces 9b, 9b are inclined toward the distal end of the throw-away tip 2, so that the bottom surface 9 of the throw-away tip 2 is formed in a convex shape protruding from the throw-away tip 2. Therefore, when the bottom portion 9 is polished, good workability can be obtained. Tilt angle β of indexable insert 2
Is smaller than the inclination angle α of the main body 3 described above (β <α), and is set to 5 ° to 45 °.

Here, the throw-away tip 2 is attached to the main body 3
When the horizontal bottom portion 9a of the throw-away tip 2 is brought into contact with the horizontal contact portion 8a of the main body 3, the inclined bottom portions 9b, 9b of the throw-away tip 2 become inclined contact portions 8b of the main body 3. , 8b. Therefore, the throw-away tip 2 is positioned by such contact, and the symmetry axis P of the throw-away tip 2 coincides with the axis L of the main body 3. Then, as described later, by screwing the screw 4 into the screw fastening hole 7 in this state, the indexable tip 2 can be attached to the main body 3 with high accuracy. Further, the horizontal bottom surface 9a of the throw-away tip 2 and the horizontal contact portion 8a of the main body 3 are brought into surface contact with each other, and the inclined bottom surfaces 9b, 9b of the throw-away tip 2 are located between the inclined contact portions 8b, 8b. Therefore, the indexable tip 2 can be firmly fixed to the main body 3.

Returning to FIG. 2A, the description will be continued. Nipping part 5a
The center axis M of the screw insertion hole 6 formed on the main body 3 is eccentric to the rear end side (the right side in FIG. 2A) of the center axis N of the screw fastening hole 7 formed on the holding portion 5b. . In particular,
As shown in FIG. 2A, the center axis M of the screw insertion hole 6 is
It is eccentric to the rear end side (right side in FIG. 2A) of the body 3 by δ with respect to the central axis N of the screw fastening hole 7. When the bottom surface 9 of the throw-away tip 2 is in contact with the contact portion 8, the central axis O of the screw passage hole 10 of the throw-away tip 2 coincides with the central axis N of the screw fastening hole 7. I have. Therefore, the center axis M of the screw insertion hole 6 is eccentric to the rear end side of the main body 3 by δ with respect to the center axis N of the screw fastening hole 7 and the center axis O of the screw passage hole 10 of the throw-away tip 2. I have. The eccentricity difference δ is set to 0.1 mm.

When fixing the throw-away tip 2 to the main body 3, the throw-away tip 2 is
a, 5b, and the bottom surface 9 of the throw-away tip 2 is brought into contact with the contact portion 8 of the main body 3. In this abutted state, the screw 4 is screwed into the screw fastening hole 7 while passing through the screw insertion hole 6 and the screw passage hole 10 of the throw-away tip 2.

As described above, when the screw 4 is screwed into the screw fastening hole 7 while passing through the screw insertion hole 6 and the screw passage hole 10 of the throw-away tip 2, the center of the screw insertion hole 6 becomes And screw passage hole 10 of indexable insert 2
2 is eccentric to the rear end side of the main body 3 by δ from the center of the screw 3. The flat head 4a of the screw 4 is connected to the flat portion 6a of the screw insertion hole 6 and the front end side of the main body 3 (left side in FIG. It is abutted against.

When the screw 4 is further screwed in, as shown in FIG.
As shown in (b), the countersunk head 4a of the screw 4 is
The main body 3 is screwed into the screw fastening hole 7 while being pressed toward the rear end side (the right side in FIG. 2B) by the plate portion 6a. Accordingly, in the throw-away tip 2, the screw passage hole 10 of the throw-away tip 2 is pressed toward the rear end side (the right side in FIG. 2B) of the main body 3 by the shaft portion 4b of the screw 4, and The bottom portion 9 is pressed against the contact portion 8 of the main body 3. Thus, the bottom surface 9 of the throw-away tip 2
Is pressed against the contact portion 8 of the main body 3, and the holding portions 5a,
Since the throw-away tip 5b holds and fixes the throw-away tip 2, the throw-away tip 2 is firmly fixed to the holding portions 5a, 5b without rattling.

In the above embodiment, the screw insertion hole 6 of the holding portion 5a is formed such that the center axis M of the dish portion 6a and the body portion 6b are both the screw passage hole 10 of the throw-away tip 2 and the screw fastening hole 7 of the holding portion 5b. Eccentric to the rear end side of the main body 3 by δ with respect to the central axes N and O. However, the screw fastening holes 6
Only the central axis of the plate portion 6a is the central axis N of the screw passage hole 10 of the throw-away tip 2 and the screw fastening hole 7 of the holding portion 5b.
It may be configured to be eccentric to O on the rear end side of the main body 3 by δ. In this case, the center axis of the body portion 6b of the screw insertion hole 6 may coincide with the center axes N and O of the screw passage hole 10 of the throw-away tip 2 and the screw fastening hole 7 of the holding portion 5b.

Here, the outer angle formed by the horizontal bottom surface and the inclined bottom surface of the throw-away tip is not less than 5 ° and not more than 45 °. Therefore, the bottom portion of the throw-away tip can be efficiently pressed against the contact portion of the main body, and it can be prevented that the throw-away tip is moved by an external force acting on the throw-away tip. Also, the width of the horizontal bottom of the throw-away tip is
Since the width of the throw-away tip is 25% or more and 75% or less with respect to the throw-away tip width, the load acting on the horizontal bottom surface and the inclined bottom surface of the throw-away tip is not biased to one side, and The portion and the inclined bottom portion can be appropriately shared.

When cutting is performed by the throw-away type ball end mill 1, the throw-away tip 2 projects from the tip of the main body 3 by rotating the main body 3 fixed to the holding portions 5a, 5b. The object to be cut is cut by the cutting edge 2a of the indexable insert 2.

As described above, by forming the horizontal bottom portion 9a and the pair of inclined bottom portions 9b, 9b on the bottom portion 9 of the throw-away tip 2 so as to correspond to the contact portion 8 of the main body 3, The indexable insert 2 can be positioned with respect to the main body 3. Therefore, the throw-away tip 2 can be attached to the main body 3 with high accuracy. Furthermore, the horizontal bottom portion 9 of the throw-away tip 2
a and the horizontal contact portion 8a of the main body 3 can be brought into surface contact with each other, and the inclined bottom portion 9 of the throw-away tip 2 can be contacted.
b and 9b are restrained between the inclined contact portions 8b and 8b,
The indexable tip 2 can be firmly fixed. Therefore, the mounting accuracy of the indexable insert 2 can be maintained, and stable and high-precision processing can be performed.

Next, a second embodiment will be described with reference to FIG. In the throw-away type ball end mill 1 of the first embodiment, the inclined bottom surface 9 of the throw-away tip 2 is formed.
b and 9b are configured to be inclined toward the tip end side of the throw-away tip 2. On the other hand, in the throw-away type ball end mill 11 of the second embodiment, the inclined bottom portions 19b and 19b of the throw-away tip 12 are formed. It is configured to be inclined toward the side opposite to the tip of the throw-away tip 12. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 4 is a partial sectional view of the throw-away type ball end mill 11 of the second embodiment, taken along line III-III in FIG. 2 (a). The contact portion 18 is formed in the main body 13 of the throw-away type ball end mill 11 in a shape symmetrical with respect to the axis L of the main body 13. The contact portion 18 includes a horizontal contact portion 18a and inclined contact portions 18b, 18b.
And The horizontal contact portion 18a is arranged at the center of the contact portion 18 and is formed in a straight line substantially perpendicular to the axis L of the main body 13. From both ends of the horizontal contact portion 18a, a pair of inclined contact portions 18b, 18b
3 toward the rear end side (right side in FIG. 4).
It is formed so as to be inclined.

On the other hand, a bottom portion 19 formed at the rear end (right side in FIG. 4) of the throw-away tip 2 has a horizontal bottom portion 19a which is in contact with the horizontal contact portion 18a of the main body 13 and an inclination of the main body 13. It has a pair of inclined bottom surfaces 19b, 19b of which a part is in contact with the contact portions 18b, 18b. The horizontal bottom portion 19a is disposed at the center of the bottom portion 19, and is formed in a straight line substantially perpendicular to the axis of symmetry P of the throw-away tip 12. The width x2 of the horizontal bottom portion 19a is 25% or more of the width W of the throw-away tip.
The ratio is 75%.

The inclined bottom portions 19b, 19b are inclined from both ends of the horizontal bottom portion 19a toward the opposite side (the right side in FIG. 4) of the tip of the throw-away tip 12 at a predetermined inclination angle (outside angle) β2. Is formed. The inclination angle β2 of the throw-away tip 2 is the inclination angle α2 of the main body 13 described above.
The angle is made larger (α2 <β2), and is set to 5 ° to 45 °.

Here, when the throw-away tip 12 is mounted on the main body 13, when the horizontal bottom portion 19a of the throw-away tip 12 is brought into contact with the horizontal contact portion 18a of the main body 13, the inclined bottom face of the throw-away tip 12 is formed. Part 19b,
19b is in contact with the inclined contact portions 18b, 18b of the main body 13. Therefore, the throw-away tip 12 is positioned by such contact, and the symmetric axis P of the throw-away tip 12 coincides with the axis L of the main body 13. By screwing the screw 4 into the screw fastening hole 7 in this state, the indexable tip 12 can be attached to the main body 13 with high accuracy. The horizontal bottom portion 19a of the throw-away tip 12 and the horizontal contact portion 1 of the main body 13
8a is brought into contact with the surface, and the inclined bottom surfaces 19b, 19b of the throw-away tip 12 are brought into contact with the inclined contact portions 18b, 18b.
18b, the throw-away tip 12
Can be firmly fixed to the main body 13.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the gist of the present invention. Can easily be inferred.

For example, in the throw-away type ball end mills 1 and 11 of the above embodiments, the throw-away tips 2 and 12 are held by the holding portions 5a and 5
b. However, the throw-away chips 2 and 12 do not necessarily need to be held between the holding portions 5a and 5b by one screw, and are held between the holding portions 5a and 5b by screwing two or more screws. It is good.

In each of the above embodiments, the inclination angles β and β2 of the inclined bottom surfaces 9b and 19b of the throw-away tips 2 and 12 correspond to the inclination contact portions 8b and 18b of the main bodies 3 and 13, respectively.
The case where the inclination angles α and α2 are set to different angles has been described. However, the inclination angles β and β2 do not necessarily have to be different from the inclination angles α and α2, and may be configured to be equal to the inclination angles α and α2.

[0042]

According to the present invention, the bottom portion of the throw-away tip has a pair of horizontal bottom portions that contact the horizontal contact portion of the main body and at least a part of the inclined contact portion of the main body. And an inclined bottom surface portion. When the bottom portion of the throw-away tip is in contact with the contact portion of the main body, when the horizontal bottom portion of the throw-away tip is in contact with the horizontal contact portion of the main body, the pair of inclined bottom portions of the throw-away tip is It comes into contact with the inclined contact part. Therefore, the throw-away tip is restrained by the contact portion of the main body, and the throw-away tip can be positioned, so that there is an effect that the throw-away tip can be accurately attached to the main body. In addition, the horizontal bottom portion of the bottom portion and the horizontal contact portion of the contact portion abut on the surface, and the bottom portion of the throw-away tip is restrained between the pair of inclined contact portions. Can be firmly fixed to the main body, and high-precision processing can be performed.

The pair of inclined contact portions of the main body are inclined from both ends of the horizontal contact portion toward the distal end of the main body, and the pair of inclined bottom surfaces of the throw-away tip are connected to the inclined contact portions of the main body. Therefore, the bottom portion of the throw-away tip is formed in a convex shape protruding from the throw-away tip side. Therefore, there is an effect that the workability is good when the bottom surface is polished.

When the bottom portion of the throw-away tip is in contact with the contact portion of the main body, the center of the screw insertion hole formed in the holding portion is aligned with the screw fastening hole and the throw-away tip formed in the holding portion. It is eccentric to the rear end side of the main body from the center of the screw passage hole. Therefore, the screw is screwed into the screw fastening hole while passing through the screw passage hole from the screw insertion hole in a state where the bottom portion of the throw-away tip is in contact with the contact portion of the main body. The bottom portion of the away chip can be pressed against the contact portion of the main body.
Therefore, there is an effect that the throw-away tip can be firmly fixed to the holding portion without rattling.

The outer angle formed by the horizontal bottom surface and the inclined bottom surface of the throw-away tip is not less than 5 ° and not more than 45 °. Therefore, it is possible to efficiently press the bottom portion of the throw-away tip against the contact portion of the main body, and it is possible to prevent the throw-away tip from being moved by an external force acting on the throw-away tip. Further, the width of the horizontal bottom portion of the throw-away tip is 25% or more and 75% or less of the width of the throw-away tip, so that the width of the horizontal bottom portion and the inclined bottom portion of the throw-away tip are different. There is an effect that the acting load can be appropriately shared between the horizontal bottom surface portion and the inclined bottom surface portion without being biased to one side.

[Brief description of the drawings]

FIG. 1 is a front view of a throw-away type ball end mill according to a first embodiment of the present invention.

FIG. 2 (a) is a partial side sectional view of a throw-away type ball end mill, showing a state where a bottom portion of a throw-away tip is in contact with a contact portion of a main body;
(B) is a partial sectional side view of the throw-away type ball end mill, and shows a state where the throw-away tip is fixed to the holding portion by a screw.

FIG. 3 is a partial cross-sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line III-III in FIG.
It is a partial section of a throw away type ball end mill of an example.

FIG. 5 is a view showing a conventional throw-away type ball end mill, in which (a) is a front view of the throw-away type ball end mill, and (b) is a partial side sectional view of the throw-away type ball end mill. is there.

FIG. 6 is a front view of a conventional throw-away type ball end mill.

[Explanation of symbols]

1,11 throw-away type ball end mill 2,12 throw-away tip 3,13 body 4 screw 5a, 5b pinching part 6 screw insertion hole 6a plate part (part of screw insertion hole) 6b body part (part of screw insertion hole) 7) Screw fastening hole 8, 18 Contact portion 8a, 18a Horizontal contact portion 8b, 18b Inclined contact portion 9, 19 Bottom portion 9a, 19a Horizontal bottom portion 9b, 19b Inclined bottom portion 10 Screw passage hole L axis (main body) M Center axis (center of screw insertion hole) N Center axis (center of screw fastening hole) O Center axis (center of screw passage hole) W Width of throwaway tip (width of throwaway tip) x, x2 Horizontal bottom surface Part width β, β2 Tilt angle (outer angle)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Torii 450 Ichinomiya-cho, Ichinomiya-cho, Hohan-gun, Aichi Prefecture F-term (reference) 3C022 KK02 KK12 KK14 MM02 MM06

Claims (7)

[Claims] 1. A pair of holding portions formed by extending a slit from a front end portion along an axial direction, a contact portion provided at an end portion of the slit, and a through-hole formed in one of the holding portions. A main body having a screw insertion hole formed therein and a screw fastening hole formed on the other side, a bottom portion abutting on the contact portion, and the screw insertion when the bottom portion abuts on the contact portion. A throw-away ball having a throw-away tip having a hole and a screw passage hole communicating with the screw fastening hole, and a screw which penetrates the screw insertion hole and the screw passage hole and is screwed into the screw fastening hole. In the end mill, the contact portion of the main body has a horizontal contact portion formed so as to be substantially perpendicular to the axis of the main body, and a pair of inclined portions which are continuously provided by being inclined from both ends of the horizontal contact portion. An abutment portion, wherein the throw away The bottom portion of the chip is a horizontal bottom portion formed so as to contact the horizontal contact portion, and at least a part of the inclined contact portion is provided while being inclined from both ends of the horizontal bottom portion. A throw-away type ball end mill, comprising: a pair of inclined bottom portions formed to be in contact with each other. 2. A pair of inclined contact portions of the main body are inclined from the horizontal contact portion toward a tip end of the main body, and a pair of inclined bottom surfaces of the throw-away tip are provided on the main body. 2. The throw-away type ball end mill according to claim 1, wherein the ball end mill is inclined corresponding to the inclined contact portion. 3. An outer angle formed between the horizontal bottom portion of the throw-away tip and one inclined bottom portion or another inclined bottom portion is:
The throw-away type ball end mill according to claim 1 or 2, wherein both are set to 5 ° or more and 45 ° or less. 4. The throw-away tip is formed in a plate shape having a predetermined throw-away tip width, and the width of the horizontal bottom portion of the throw-away tip is at least 25% with respect to the throw-away tip width. The throw-away type ball end mill according to any one of claims 1 to 3, wherein the content is 75% or less. 5. A center of the screw insertion hole formed in one of the holding portions when the bottom portion of the throw-away tip is in contact with the contact portion of the main body. The throwaway according to any one of claims 1 to 4, wherein the screw fastening hole formed on the other side and the screw passage hole of the throwaway tip are eccentric to the rear end side of the main body. Type ball end mill. 6. The screw insertion hole formed in one of the sandwiching portions is formed in a countersink shape and is provided on a side opposite to the slit, and a countersink is formed from the counterpart to the slit side. A threaded hole formed in one of the holding portions when the bottom portion of the throw-away tip is in contact with the contact portion of the main body. The center of the plate portion is eccentric to the rear end side of the main body with respect to the center of the screw passage hole formed in the other side of the holding portion and the screw passage hole of the throw-away tip. A throw-away type ball end mill according to claim 5. 7. A throw-away insert used for the throw-away type ball end mill according to claim 1.