JPH1094914A - End mill tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of interference of a material to be cutted with an end cutting edge flank of a tool near a shaft center of the tool, by changing an end cutting edge clearance angle in such manner that it is gradually increased in accordance with the decrease of the distance in the radial direction from the shaft center of the end mill tool. SOLUTION: The first clearance angle θr of an end cutting edge is changed in such manner that it is gradually increased in accordance with the decrease of the distance r in a radial direction from a shaft center of an end mill tool. That is, θr0>θ0 is satisfied when the first clearance angle of an end part at a tool inner circumfereutial side, of the end cutting edge (the distance r in the radial direction from the shaft center of the end mill toll is r0), is θ0, and that of an end part at a tool outer peripheral side, of the end cutting edge (the distance r in the radial direction from the shaft center of the end mill tool is d/2) is θr0. Thereby the interference of the material to be cutted and the end cutting edge flank of the tool at the inner circuferential part of the tool, can be prevented even in the three-dimensional machining such as the helical machining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an end mill tool having a bottom edge.

[0002]

2. Description of the Related Art An end mill tool is used, for example, in Japanese Utility Model 4-5.
No. 3847, and the like. End mill tools can handle almost all types of cutting, such as grooving, side machining, drilling, and counterboring, when the tool enters a hole or groove.
Therefore, using a small-diameter end mill tool, to perform various processing without step change to end mill tools with different tool diameters, reduce the step change time and reduce the types of tools used, so as to increase production efficiency, End mill tools are used. Conventionally, regarding the structure of an end mill tool, in an end mill tool such as a flat end mill provided with a bottom edge having a bottom edge first relief angle, the bottom edge first relief angle is constant in the end mill tool radial direction.

[0003]

However, in the conventional end mill tool, since the first relief angle of the bottom edge of the end mill tool is constant in the tool radial direction, the tool blade locus is three-dimensional as in helical machining. (The feed amount in the rotation direction and the axial direction), the feed amount of the tool (the amount of protrusion of the tool revolution) reaches a predetermined amount determined from the first relief angle of the bottom blade, and the tool blade is moved from the tool shaft center. In the part where the radial distance is small,
The work material interferes with the flank of the tool bottom blade. for that reason,
The feed amount of the tool cannot be increased to a predetermined amount determined from the first relief angle of the bottom blade, and cutting efficiency and production efficiency are limited.
An object of the present invention is to reduce the occurrence of interference between the work material and the tool bottom blade flank near the tool axis even if the amount of revolution of the tool is increased to a predetermined amount determined from the first clearance angle of the bottom blade. It is to provide an end mill tool which can be prevented.

[0004]

The present invention to achieve the above object is as follows. An end mill tool having a bottom edge, wherein the first relief angle of the bottom edge is changed so as to increase as the radial distance from the axis of the end mill decreases.

[0005] In the end mill tool of the present invention, the first relief angle of the bottom blade near the tool axis is increased, so that even in three-dimensional machining such as helical machining, the work material and the flank of the tool bottom blade can be removed. Does not interfere. Therefore, the amount of revolving plunge of the tool can be increased to a predetermined amount determined from the first clearance angle of the bottom blade at the outermost diameter of the tool, and the cutting efficiency and the production efficiency can be increased.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an end mill tool 1 according to an embodiment of the present invention has a blade portion 2, a relief diameter portion 3, and a shank portion 4. The relief diameter portion 3 is provided between the blade portion 2 and the shank portion 4, and has an outer diameter smaller than the outer diameter of the blade portion 2 and smaller than the outer diameter of the shank portion 4. The end mill tool 1 is gripped and fixed to a processing head by a shank part 4, is rotated around an axis, and cuts a work material by a blade part.

As shown in FIG. 3, the blade section 2 has a plurality of blades 5. Each blade 5 has a bottom blade 6 and an outer blade 7 as shown in FIG. The outer peripheral blade 7 is formed by being twisted over the entire length of the blade portion 2, and the bottom blade 6 is formed from the outermost diameter portion of the tool to the vicinity of the tool axis. However, since the radius near the tool axis is small and the rotation speed is small due to the small radius, the bottom blade 6 is not formed near the tool axis to prevent digging. FIGS. 2 and 3 show a bottom blade first clearance angle, a bottom blade second clearance angle, a bottom blade rake angle, a bottom blade watermark angle, an outer peripheral first outer clearance angle, an outer peripheral second clearance angle, and an outer peripheral rake. The angles, the outer peripheral first flank widths, and the torsion angles indicate which angles and dimensions correspond to each other.

[0008] The blade length (length of the blade portion 2) l is set to a minimum length capable of forming a chip pocket. Is set to the minimum length given the grinding allowance when the tool is initially made longer by the amount of grinding. The blade length of a conventional end mill is
In consideration of versatility, it is usually set to about 1.5 times the shank diameter of the tool, but in that case, it is difficult to secure the rigidity of the tool. In the embodiment of the present invention, since the blade length is determined as described above and the blade length is made as small as possible, the tool rigidity is increased.

As shown in FIG. 1, the relief diameter portion 3 is
And the shank part 4, the outer diameter of which is
Since the outer diameter of each of the shank portions 4 is smaller than the outer diameter of the shank portion 4, interference between the work material and the tool in the radial direction hardly occurs.
In the conventional end mill tool, the relief diameter portion is not provided between the blade portion and the shank portion 4, so if the processing depth in the end mill processing is longer than the blade length, the work material interferes with the shank portion. Although the machining depth is limited, in the end mill tool of the embodiment of the present invention, since the relief diameter portion 3 is provided, even if the machining depth in the end mill machining is longer than the blade length, the workpiece material And interference with the relief diameter portion 3 does not occur, and the machining depth can be increased.

As shown in FIG. 1, an R (radius R ₁ ) is provided at a transition portion between the relief diameter portion 3 and the blade portion 2, and the relief diameter portion 3 is provided.
R (radius R ₂ ) is provided at the transition between the and the shank 4. This alleviates the stress concentration at each transition and reduces the risk of cracking.

[0011] As shown in FIGS. 2 and 4, the end cutting edge first relief angle theta _r end cutting edges 6 are changed so as to increase according to radial distance r from the end mill tool axis is reduced. That is, the first clearance angle of the bottom blade at the inner peripheral side end of the tool (the radial distance r from the end mill tool axis is r ₀ ) is θ ₀ , and the outer peripheral side end of the bottom blade (end mill Assuming that the first clearance angle of the bottom blade at the radial distance r from the tool axis is d / 2) is θ _{r 0} , θ _{r 0} > θ ₀ . On the other hand, for comparison, as shown by the two-dot chain line in FIG. 4, the first relief angle of the bottom edge of the conventional end mill tool with the bottom edge is independent of the radial distance r from the end mill tool axis. It is constant.

[0012] As shown in FIG.
If the pilot hole diameter (ΦD₁) And finish diameter (ΦD₀) To diameter
Rd = (D₀-D₁) / 2. At this time, the plunge z per tool revolution is given
The slope drawn by the point P on the finished diameter side of the tool
Angle θ₁And the slope angle drawn by point Q on the pilot hole diameter side
θ_TwoIs found. They are, respectively, θ₁= Tan^-1(Z / (πD₀)) Θ_Two= Tan^-1(Z / (πD₁)) And (z / (πD₀)) <(Z / (π
D₁)), So θ₁<Θ_TwoBecomes Normal endomi
The bottom blade first clearance angle θ_rDepends on the radial position of the tool.
The slope angle during helical machining.
Degree θ_r, The outer peripheral side of the tool does not interfere with the work material
However, the slope angle is θ on the inner circumference side of the tool._rBigger than
Interference with the work material. Therefore, in practice, θ
_rCan not send tools. In the embodiment of the present invention,
In order to prevent this, the bottom blade first clearance angle θ_rThe tool radial direction
As it gets larger as it approaches the center of the tool,
Larger slope angle than machining with end mill
it can.

Next, how to change the first clearance angle θ _r of the bottom edge of the end mill tool according to the embodiment of the present invention will be described. Assuming that the first clearance angle of the bottom edge at the outer periphery of the tool is θ ₀ (see FIG. 4), the plunge amount z per revolution of the tool is z / (πD ₀ ) = tan θ ₀ , and z = πD ₀ tan θ ₀ The bottom blade first clearance angle θ _r at a point separated by r from the tool center is θ _r ≧ tan ⁻¹ {z / (π (d ₁ + r))} = tan ⁻¹ ＝ (D ₀ tan θ ₀ ) / (D ₁ + r)｝ = tan ⁻¹ {(D ₀ tan θ ₀ ) / (D ₀ −d ₀ + r)}, interference with the work material can be avoided over the entire bottom blade.

Since this result depends on the finished diameter ΦD ₀ , if it is used for drilling, it is assumed that ΦD ₀ = Φd ₀ and θ _r ≧ tan ^-1 ｛(d ₀ tan θ ₀ ) / r｝. For example, a general-purpose setting can be made, and the setting is also used in the embodiment of the present invention.

Next, the operation will be described. In the embodiment of the present invention, the first clearance angle θ _r of the bottom blade is set to tan ⁻¹ ｛(d ₀ tan
θ ₀ ) / r｝ or more, and θ _r increases as the radial distance from the tool axis decreases, so that even in three-dimensional machining such as helical machining, the inner circumferential portion of the tool can be damaged. The cutting material does not interfere with the flank of the tool bottom blade. Therefore, the feed amount of the tool (the amount of protrusion per tool revolution) can be increased to the feed amount determined from the first relief angle of the bottom blade at the outermost diameter of the tool, and the cutting efficiency and the production efficiency can be increased.

Since the length of the blade 2 is smaller than that of the conventional one, the cross-sectional area of the blade 2 is smaller than that of the shank 4 (usually 5
0 to 65%), the tool rigidity can be ensured. Further, the relief diameter portion 3 is provided between the blade portion 2 and the shank portion 4 and its outer diameter is smaller than the outer diameter of the blade portion 2, so that the working depth is increased and the work material is reduced. Relief diameter part 3
, It is possible to prevent radial interference between the work material and the tool. Also, regardless of whether the relief diameter portion 3 is smaller than the diameters of the blade portion 2 and the shank portion 4, since the transition portion is provided with R, concentration of stress on the transition portion can be suppressed, and fatigue can be reduced. Prevents the strength from decreasing,
There is no decrease in durability.

[0017]

According to the end mill tool of the first aspect, in the end mill tool having the bottom blade, the first relief angle of the bottom blade is changed so as to increase as the radial distance from the end mill tool axis decreases. Therefore, even in three-dimensional machining such as helical machining, even if the amount of revolving plunge of the tool is increased to a predetermined plunge determined from the first relief angle of the bottom blade, the work material and the tool bottom near the tool axis are not affected The occurrence of interference with the blade flank can be prevented. Therefore, the revolving plunge amount of the tool can be increased to the plunge amount determined from the first clearance angle of the bottom blade at the outermost diameter of the tool, and the cutting efficiency,
Production efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is an overall side view of an end mill tool according to a first embodiment of the present invention.

FIG. 2 is an enlarged side view of the vicinity of a tip of a blade portion of the end mill tool of FIG. 1;

FIG. 3 is a front view of a tip portion of a blade of the end mill tool of FIG. 1;

FIG. 4 is a diagram showing a manner in which a first relief angle of a bottom blade changes according to a distance from a tool axis.

FIG. 5 is a diagram showing a locus of a bottom blade in helical machining.

[Description of Signs] 1 End mill tool 2 Blade part 3 Relief diameter part 4 Shank part 5 Blade 6 Bottom blade 7 Outer peripheral blade

Claims (1)

[Claims] 1. An end mill tool having a bottom edge,
An end mill tool wherein the first relief angle of the bottom blade is changed so as to increase as the radial distance from the end mill tool axis decreases.