JP3250909B2 - 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 an end mill configured to hold a cutting insert at the tip of a tool body.

[0002]

2. Description of the Related Art Conventionally, an end mill has been used in which an insert pocket is formed at the tip of a tool body and a cutting insert is held in the pocket.

FIGS. 4 and 5 show such an end mill 20 conventionally used.
Then, a rib 23 is provided in the vicinity of the insert pocket 21 in order to compensate for the reduction in the strength of the tool body due to the insert pocket 21 and the flat portion 22 around the insert pocket 21, and cracks are generated from the boundary between the flat portion 22 and the rib 23. In some cases, an oblique cut portion 24 is formed at this portion in order to prevent the occurrence of the above problem.

[0004]

However, the conventional end mill 20 has the following problems.

That is, depending on the shape of the end mill 20, a greater stress acts on the boundary between the side wall surface and the bottom surface of the insert pocket 21 than on the boundary between the flat portion 22 and the rib 23, and cracks occur from this portion. Was sometimes done.

Further, a tool body 25 for machining a small diameter is used.
When the diameter of the tool body 25 is reduced, the strength of the tool body 25 becomes insufficient, and cracks are generated or broken at the boundary between the flat part 22 and the rib 23 and the like. However, there is a problem that a practical end mill 20 corresponding to the above problem cannot be manufactured.

[0007]

According to the present invention, there is provided an end mill in which an insert pocket for holding a cutting insert is formed at a tip portion of a tool body. R0.5 to R1.R1 over the entire length of the boundary between the wall surface and the bottom surface.
0 is formed along the entire length of the boundary between the rear wall surface and the bottom surface in the insert pocket.
And a flat cut portion having a width of 1 to 2 mm perpendicular to the bottom surface of the insert pocket over the entire length of the bottom surface of the insert pocket at a boundary between the bottom surface of the insert pocket and the side peripheral surface of the tool holder. Was formed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an end mill 1 according to an embodiment of the present invention. This end mill 1 has an insert pocket 5 for holding a cutting insert 4 at a tip 3 located on the tip side of a shank 2 of a tool body 1a, and rotation of the insert pocket 5. A chip pocket 6 and a rib 7 are formed on the direction side.

FIG. 2 is an enlarged view of a region A of the end mill 1 of FIG. 1. As shown in FIG. 2, a slant cut portion 9 is formed at a boundary between the rib 7 and the side wall surface 8 of the insert pocket 5. An R-shaped concave groove 14 is formed at the boundary between the side wall surface 8 and the bottom surface 10 of the insert pocket 5, and an R-shaped horizontal groove 15 is formed at the boundary between the rear wall surface 13 and the bottom surface 10.
Is formed, and the bottom surface 10 of the insert pocket 5 is formed.
A flat cut portion 12 perpendicular to the bottom surface 10 is formed at a boundary portion between the tool body 1a and the side peripheral surface 11 of the tool body 1a.

FIG. 3 is a view of the end mill 1 of FIG. 1 viewed from the front end side. The outer dotted line represents the processing diameter, and the inner dotted line represents the diameter of the tool body 1a when the flat cut portion 12 is not provided. ing.

The end mill 1 configured as described above has the following functions and effects.

First, since an R-shaped concave groove is formed at the boundary between the side wall surface 8 and the bottom surface 10 of the insert pocket 5, the stress generated in this portion is dispersed in multiple directions, and the stress is exerted by its cushioning action. Can be absorbed, so that it is possible to prevent cracks from being generated or breakage from this portion.

The flat cut portion 1 perpendicular to the bottom surface 10 extends over the entire length of the bottom surface 10 at the boundary between the bottom surface 10 of the insert pocket 5 and the side peripheral surface 11 of the tool holder.
By forming No. 2, as shown in FIG. 3, the diameter of the tool body 1a for a certain processing diameter can be maximized, so that the strength of the tool body 1a is maintained and the processing diameter that can be cut is reduced. It has the feature that it can be made as small as possible.

The size of the vertical groove 14 is R
A range of 0.5 to R1.0 is preferable because the stress dispersibility or the stress absorption is excellent. In contrast, R
When it is smaller than 0.5, the stress dispersibility or the stress absorption is insufficient and cracks may occur.
If it is larger than 1.0, the thickness of this portion becomes small, resulting in insufficient strength, and there is a possibility that cracks or breakage may occur.

The size of the lateral groove 15 is R
A range of 1.0 to R2.0 is preferable because the stress dispersibility or the stress absorption is excellent. In contrast, R
If it is smaller than 1.0, the stress dispersibility or stress absorption is insufficient and cracks may occur.
When it is larger than 2.0, the thickness of this portion becomes small, resulting in insufficient strength, which may cause cracks and breakage.

Further, the width of the flat cut portion 12 is preferably in the range of 1 to 2 mm. On the other hand, when the width is smaller than 1 mm, the flat cut portion 12
The ratio of increasing the diameter of the tool body 1a with respect to a certain processing diameter is smaller than that in the case where there is no machining, and the effect is hardly exhibited.
May interfere with each other.

Embodiment 1 An end mill 1 of the present embodiment shown in FIGS.
An end mill in which the size of the vertical groove 14 is R0.5 and the size of the horizontal groove 15 is R1.0 is used, and an end mill in which only the horizontal groove 15 (R1.0) is formed as a comparative example. Using an end mill in which neither was formed, continuous cutting was performed under the following conditions, and the time until crack generation was measured. If the cutting durability time is 21 minutes or longer, cracks and the like do not occur in normal cutting, and if shorter than 21 minutes, cracks and the like may occur in normal cutting.

(Conditions) Cutting speed 100 m / min. (Number of rotations: 1592 rpm) Cutting depth: 6 mm × width: 4.5 mm Feed: 0.2 mm / blade (Table feed: 955 mm / min) Work material S50C As a result, the end mill 1 of the present example was 41 minutes and 27 seconds. On the other hand, the time was 20 minutes and 37 seconds in the end mill in which only the lateral concave groove 15 (R1.0) was formed, and 5 minutes and 5 seconds in the end mill in which neither was formed.

Embodiment 2 An end mill 1 of the present embodiment shown in FIGS.
The same measurement as in Example 1 was performed using the end mill 1 in which the size of the horizontal groove 15 was changed to R1.5 and the size of the horizontal groove 15 was changed as shown in Table 1. Table 1 shows the results.

[0020]

[Table 1]

As is clear from Table 1, the vertical grooves 14
If the size of R is in the range of R0.5 to R1.0, the stress dispersibility or the stress absorption is excellent, and the cutting durability time is 21 minutes or more. Was. On the other hand, when it is smaller than R0.5, the stress dispersibility or the stress absorption is insufficient, the cutting durability time is shorter than 21 minutes, and cracks may occur,
On the other hand, when it was larger than R1.0, it was found that the thickness of this portion was small and the strength was insufficient, the cutting durability was shorter than 21 minutes, and cracks and breakage might occur.

Embodiment 3 An end mill 1 of the present embodiment shown in FIGS.
The same measurement as in Example 1 was performed using the end mill 1 in which the size of the vertical groove 14 was changed to R0.7 and the size of the horizontal groove 15 was changed as shown in Table 2. Table 2 shows the results.

[0023]

[Table 2]

As is evident from Table 2, the vertical grooves 14
If the size of R is in the range of R1.0 to R2.0, the stress dispersibility or stress absorption is excellent, and the cutting durability time is 21 minutes or more, so that the strength is excellent. Was. On the other hand, when the value is smaller than R1.0, the stress dispersibility or the stress absorption is insufficient, the cutting durability time is shorter than 21 minutes, and cracks may be generated.
On the other hand, when it is larger than R2.0, it was found that the strength of this portion was insufficient because the thickness of this portion was small, the cutting durability time was shorter than 21 minutes, and cracks and breakage might occur.

[0025]

As described above, according to the end mill of the present invention, the boundary between the side wall surface and the bottom surface and the boundary between the rear wall surface and the bottom surface of the insert pocket have the effect of dispersing and absorbing stress. By forming R-shaped concave grooves over their entire length in the above-mentioned boundary portion, and making these grooves have sizes of R0.5 to R1.0 and R1 to R2, cracks are generated from this portion. And a flat cut portion having a width of 1 to 2 mm perpendicular to the bottom surface is formed over the entire length of the boundary between the bottom surface of the insert pocket and the side peripheral surface of the tool holder. By doing so, it is possible to maximize the diameter of the tool main body with respect to the processing diameter, thereby maintaining the strength of the tool main body and minimizing the cutting diameter that can be cut, The one in which an effect.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of a region A in FIG.

FIG. 3 is a view of the end mill of FIG.
The outer dotted line represents the processing diameter, and the inner dotted line represents the diameter of the tool body when the flat cut portion is not provided.

FIG. 4 is a plan view of a conventional end mill.

FIG. 5 is a view on arrow B of the end mill of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 End mill 1a Tool main body 2 Shank 3 Tip part 4 Cutting insert 5 Insert pocket 6 Chip pocket 7 Rib 8 Side wall surface 9 Oblique cut part 10 Bottom surface 11 Side peripheral surface 12 Flat cut part 13 Rear wall surface 14 Vertical concave groove 15 Horizontal concave groove A region

Claims (1)

(57) [Claims] 1. An end mill having an insert pocket for holding a cutting insert at a tip end portion of a tool body, wherein R0.5 to R1.0 is provided over the entire length of a boundary portion between a side wall surface and a bottom surface in the insert pocket. R1.0 to R2.0 are formed over the entire length of the boundary between the rear wall surface and the bottom surface in the insert pocket, and the bottom surface of the insert pocket and the side of the tool holder. An end mill having a flat cut portion having a width of 1 to 2 mm perpendicular to the bottom surface over the entire length of a boundary portion with a peripheral surface.