JP2002144134A - 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 with a throwaway tip accurately and firmly installable thereon. SOLUTION: The abutting part 8 of a body 3 comprises horizontal abutting parts 8a1, 8a2, and 8a3, and a pair of V-shaped abutting parts 8b and 8b having an opening angle of β and recessed in V-shape. The bottom surface part 9 of the throwaway tip 2 comprises a pair of V-shaped bottom surface parts 9a and 9a having a tip angle of α and projected in V-shape. The both side parts of the V-shaped bottom surface parts 9a and 9a of the throwaway tip 2 are allowed to abut on the V-shaped abutting parts 8b and 8b of the body 3 to position the throwaway tip 2 so as to accurately install the throwaway tip 2 on the body 3. Since the V-shaped bottom surface parts 9a and 9a of the throwaway tip 2 are arrested to the V-shaped abutting parts 8b and 8b of the body 3, 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 111 and the contact portions 112, 112 of the main body 111 are likely to come into contact with two points, so that the indexable insert 109 cannot be firmly fixed and high-precision processing cannot be performed. There was a point.

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, the abutting portion of the main body is formed in a V-shape that is oriented in the axial direction of the main body, and is formed with respect to the axis of the main body. A pair of symmetrically arranged V-shaped abutments A bottom portion of the throw-away tip includes a pair of V-shaped bottom portions formed in a V-shape such that at least a part thereof is in contact with both side portions of the V-shaped contact portion. ing.

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. In the bottom portion of the throw-away tip, at least a part of a pair of V-shaped bottom portions of the bottom portion is in contact with both side portions of the V-shaped contact portion of the main body. By this contact, the throw-away tip is restrained and positioned by the pair of V-shaped contact portions of the main body. 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 V-shaped abutting portions of the main body contracts in a direction toward the rear end of the main body. And the pair of V-shaped bottom surfaces of the throw-away tip is formed in a V-shape corresponding to the V-shaped contact portion of the main body.

According to a third aspect of the present invention, there is provided a throw-away type ball end mill according to the second aspect, wherein an opening angle formed by the V-shaped contact portion of the main body is greater than 90 ° and less than 170 °. Has been
The tip angle formed by the V-shaped bottom portion of the throw-away tip is formed to be equal to or larger than the opening angle formed by the V-shaped contact portion of the main body.

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 a bottom portion of the throw-away tip is in contact with a contact portion of the main body. In this case, the center of the screw insertion hole formed in one of the holding portions is larger than the screw passage hole of the screw fastening hole and the throw-away tip formed in the other of the holding portion. It is eccentric toward the rear end.

According to the throw-away type ball end mill according to the fourth aspect, it operates in the same manner as the throw-away type ball end mill according to any one of the first to third aspects, and the bottom surface of the throw-away tip is formed of 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 fifth aspect of the present invention, in the throw-away type ball end mill according to the fourth aspect, the screw insertion hole formed in one of the holding portions is formed in a countersunk shape. A plate portion disposed on the side opposite to the slit, and a body portion connected to the slit side from the plate portion, and the bottom surface of the throw-away tip is connected 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 fifth aspect, it operates in the same manner as the throw-away type ball end mill of the fourth 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.

[0015] The throwaway tip 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.

[0016]

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 where 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 has a pair of holding portions 5a, 5b for holding the throw-away tip 2 by extending a slit from the tip 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 sectional view taken along 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 contacts the bottom surface 9 of the throw-away tip 2 and
The horizontal contact portions 8a1, 8a2, and 8a are used to restrain and position the contacted throw-away tip 2.
3 and a pair of V-shaped contact portions 8b, 8b. The horizontal contact portions 8a1 to 8a3 are formed in a straight line substantially perpendicular to the axis L of the main body 3, and are arranged so that they are aligned on one straight line. V-shaped contact portions 8b, 8b
Are recessed in a V-shape that contracts at an opening angle β from the horizontal contact portions 8a1 to 8a3 toward the rear end side (the right side in FIG. 3) of the main body 3. The opening angle β is larger than 90 ° and 1
The range is less than 70 °.

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 a screw 4 is passed through a substantially central portion of a plane portion of the throw-away tip 2. A screw passage hole 10 is formed to penetrate, and the central axis O (see FIG. 2A) of the screw passage hole 10 is located on the axis of symmetry P of the indexable insert 2. Further, a cutting edge 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. 2a is formed.

At the rear end (right side in FIG. 3) of the throw-away tip 2, there is provided a bottom surface portion 9 formed in a substantially W shape when viewed from the front. The bottom portion 9 is for positioning the throw-away tip 2 by being brought into contact with the contact portion 8 of the main body 3 and has a pair of V-shaped bottom portions 9a, 9a. The V-shaped bottom portions 9a, 9a are located at positions corresponding to the V-shaped contact portions 8b, 8b of the main body 3 at the rear end side of the main body 3 (FIG. 3).
(To the right of the right side of FIG. 2). The tip angle α is V-shaped contact portions 8b, 8b of the main body 3.
Is greater than or equal to 90 ° and less than 170 °.

As described above, the V-shaped contact portions 8b, 8b of the main body 3 are set so that the opening angle β is larger than 90 °, and the pair of V-shaped bottom portions 9a, 9a,
The angle formed by the V-shaped concave portion formed between 9a is also an angle larger than 90 °. Therefore, these recesses can be processed by an end mill or the like.

Here, the throw-away tip 2 is attached to the main body 3
When the V-shaped bottom portion 9a of the throw-away tip 2 is mounted, both side portions forming the tip angle α are in contact with the V-shaped contact portions 8b of the main body 3, respectively. Therefore,
By this contact, the throw-away tip 2 is positioned, and the axis of symmetry 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. Also, throw away tip 2
The V-shaped bottom portions 9a, 9a of the V-shaped contact portions 8b,
8a, and the indexable tip 2 is restrained by the main body 3 by such abutment, so that 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.

In 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 opening angle β formed by the V-shaped abutting portions 8b, 8b of the main body 3 is greater than 90 ° and less than 170 °, and the V-shaped bottom portion 9a,
9a is equal to the V-shaped contact portions 8b, 8b of the main body 3.
Is greater than or equal to the opening angle β. Therefore, the bottom portion 9 of the throw away tip 2 can be efficiently pressed against the contact portion 8 of the main body, and it is possible to prevent the throw away tip 2 from moving due to an external force acting on the throw away tip 2. .

When cutting is performed by the throw-away 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, a pair of V-shaped bottom portions 9a, 9b are formed on the bottom portion 9 of the throw-away tip 2 in correspondence with the V-shaped contact portions 8b, 8b formed on the contact portion 8 of the main body 3.
By forming 9a, it is possible to position the throw-away tip 2 with respect to the main body 3. Therefore,
The indexable insert 2 can be attached to the main body 3 with high accuracy. In addition, throwaway tip 2
And the contact portion 8 of the main body 3 is contacted at four places,
Since the indexable tip 2 is restrained by the contact portion 8 of the main body 3, 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 V-shaped contact portions 8b, 8b of the main body 3 are recessed toward the rear end of the main body 3, and the V-shaped bottom surface 9a of the throw-away tip 2 is formed. , 9a protrude toward the rear end side of the main body 3, but in the throw-away type ball end mill 11 of the second embodiment, the V-shaped contact portion 18 of the main body 13 is provided.
a, 18a are protruded toward the distal end side of the main body 13, and the V-shaped bottom portion 19b,
19 b is recessed toward the tip end 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 the 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 is for contacting the bottom portion 19 of the throw-away tip 12 and for restraining and positioning the contacted throw-away tip 12, and includes a pair of V-shaped contact portions 18a, 18a. V-shaped contact portions 18a, 1
8a is formed in a V-shape that contracts at a tip angle β2 toward the tip end side (left side in FIG. 3) of the main body 3. Tip angle β2
Is a V-shaped bottom portion 1 of a throw-away tip 12 described later.
9b and 19b are equal to or larger than the opening angle α2,
The angle is in a range larger than 170 ° and smaller than 170 °.

The throw-away tip 12 is formed in a plate shape whose outer shape is symmetrical with respect to the axis of symmetry P. A substantially central portion of a plane portion of the throw-away tip 12 is for passing the screw 4 therethrough. A screw passage hole 10 is formed through the screw passage hole 10, and the center axis O (see FIG. 2A) of the screw passage hole 10 is located on the axis of symmetry P of the throw-away tip 12. In addition, a cutting edge is provided at the tip of the throw-away tip 12 which is formed in an arc shape (the left side in FIG. 4) and the side (the upper side or the lower side in FIG. 4) linearly extending from the tip. 12
a is formed.

The rear end of the throw-away tip 12 (FIG. 4)
On the right side), the bottom portion 19 is
Is formed in a shape symmetrical with respect to the symmetry axis P. The bottom surface portion 19 is for positioning the throw-away tip 12 by being brought into contact with the contact portion 18 of the main body 13, and is provided with horizontal bottom surface portions 19a1, 19a2, and 19a.
3 and a pair of V-shaped bottom surfaces 19b, 19b.
The horizontal bottom portions 19a1 to 19a3 are formed in a straight line substantially perpendicular to the axis of symmetry P of the throw-away tip 12, and are arranged so as to coincide with each other on one straight line. The V-shaped bottom portions 19b, 19b are
It is recessed in a V-shape that contracts at an opening angle α2 from 1 to 19a3 toward the tip end of the throw-away tip 12 (left side in FIG. 4). The opening angle α2 is in a range of more than 90 ° and less than 170 °. Here, when the throw-away tip 12 is attached to the main body 13, the V-shaped bottom portions 19b, 19b of the throw-away tip 12 have: Both sides of the V-shaped contact portions 18a of the main body 13 forming the tip angle β2 are contacted. 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. Then, as described above, 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 V-shaped bottom portions 19b and 19b of the throw-away tip 12 are connected to the V-shaped contact portions 18 of the main body 13.
Since the throw-away tip 12 is restrained by the main body 13 by the contact at four places, 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 opening angles α2 and
β, the tip angles α, β2 are the opening angles α2, β are the tip angles α, β
The case where it is formed larger than 2 has been described. However, the opening angles α2 and β need not necessarily be formed larger than the tip angles α and β2, and may be configured to be equal to the tip angles α and β2.

[0040]

According to the present invention, the abutting portion of the main body is formed in a V-shape oriented in the axial direction of the main body, and the pair of V-shaped abutments arranged symmetrically with respect to the axis of the main body. A bottom portion of the throw-away tip, which is in contact with the contact portion of the main body, is formed in a V-shape such that at least a part thereof is in contact with both sides of the V-shaped contact portion. And a pair of V-shaped bottom portions. Therefore, by bringing the throw-away tip into contact with the contact portion of the main body, 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. Further, by bringing the bottom portion of the throw-away tip into contact with the bottom portion of the main body at four locations, there is an effect that the throw-away tip can be firmly fixed.

The opening angle formed by the V-shaped contact portion of the main body is 90 °.
The tip angle formed by the V-shaped bottom portion of the throw-away tip is greater than or equal to the opening angle formed by the V-shaped contact portion of the main body. A V-shaped recess having an angle greater than 90 ° is formed between the contact portion and the pair of V-shaped bottom surfaces of the throw-away tip. Therefore, when processing these V-shaped concave portions, there is an effect that workability is good.

When the bottom portion of the throw-away tip is brought into 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 formed in the holding portion and the throw-away tip. 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 opening angle formed by the V-shaped contact portion of the main body is greater than 90 ° and less than 170 °,
The tip angle formed by the V-shaped bottom portion of the throw-away tip is formed to be equal to or larger than the opening angle formed by the V-shaped contact portion of the main body. Therefore, it is possible to efficiently press the V-shaped bottom portion of the throw-away tip against the V-shaped contact portion of the main body, and to prevent the throw-away tip from being moved by an external force acting on the throw-away tip. effective.

[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 part 8b, 18a V-shaped contact part 9, 19 Bottom part 9a, 19b V-shaped bottom part 10 Screw passage hole L Axis (axis of main body) M Center axis (of screw insertion hole) Center) N Center axis (center of screw fastening hole) O Center axis (center of screw passage hole) α Tip angle β Opening angle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeshi Torii 450 Ichinomiya-cho, Ichinomiya-cho, Hoei-gun, Aichi Prefecture, Japan F-term (reference) 3C022 KK02 KK07 KK12 KK14 KK23 KK25 LL01 MM06

Claims (6)

[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 abutting portion of the main body has a V pointing in the axial direction of the main body.
And a pair of V-shaped abutting portions that are formed in the shape of a letter and that are arranged symmetrically with respect to the axis of the main body. The bottom portion of the throw-away tip is provided on both sides of the V-shaped abutting portion. A throw-away type ball end mill comprising a pair of V-shaped bottom portions formed in a V-shape so that at least a part thereof abuts. 2. A pair of V-shaped bottom portions of the throw-away tip, wherein a pair of V-shaped abutting portions of the main body are recessed in a V-shape that contracts toward the rear end of the main body. 2. The throw-away type ball end mill according to claim 1, wherein the protrusion is formed in a V-shape corresponding to the V-shaped contact portion of the main body. 3. An opening angle formed by a V-shaped contact portion of the main body,
It is greater than 90 ° and less than 170 °, and the tip angle formed by the V-shaped bottom portion of the throw-away tip is formed to be equal to or larger than the opening angle formed by the V-shaped contact portion of the main body. The throw-away type ball end mill according to claim 2, characterized in that: 4. When the bottom portion of the throw-away tip abuts on the abutment portion of the main body, the center of the screw insertion hole formed in one of the holding portions is located on the other side of the holding portion. The throw-away ball according to any one of claims 1 to 3, wherein the formed screw fastening hole and the screw-through hole of the throw-away tip are eccentric to a rear end side of the main body. End mill. 5. 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 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. The throw-away type ball end mill according to claim 4. 6. A throw-away tip for use in the throw-away type ball end mill according to any one of claims 1 to 5.