JP2000334614A - Ball end mill for nonferrous metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball end mill for nonferrous metal that can ensure high machining efficiency and appreciable machined surface quality in cutting soft nonferrous metal. SOLUTION: This ball end mill for nonferrous metal has a circular area A of a diameter of 0.02 to 0.08 mm that is free from a pair of ball end cutting edges 16 at the hemispheric center or on the axis, an overlap (t) of the paired ball end cutting edges 16 of O to 0.08 mm in the center, a normal rake of the paired ball end cutting edges 16 of 10 deg. to 20 deg., and a helix angle difference of 0 deg. to 3 deg. between the ball end cutting edges 16 and peripheral cutting edges 18 connected thereto smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball end mill, and more particularly to a ball end mill for non-ferrous metals which is suitably used for cutting non-ferrous metals such as aluminum alloys, copper and copper alloys.

[0002]

2. Description of the Related Art A ball having a pair of ball blades provided symmetrically with respect to an axis at a hemispherical portion at the tip thereof, and an outer peripheral cutting edge twisted around the axis continuously to the ball blade. End mills are used for cutting various kinds of metals such as dies. Such a ball end mill,
Generally, there is no ball blade in the range of 0.1 to 0.3 mm in diameter at the center of the tip, and the rake angle of the pair of ball blades at right angles is in the range of -5 ° to + 5 °.

[0003]

However, when such a conventional ball end mill is used to cut a relatively soft non-ferrous metal such as an aluminum alloy, copper, or a copper alloy, the cutting performance becomes poor and the welding and chipping are not performed. Clogging was likely to occur, and high processing efficiency could not be obtained. In addition, since cutting is not performed at the center of the tip without cutting edges, the quality of the machined surface is impaired by crushing or tearing,
There is a problem in that the connection between the outer peripheral cutting edge and the ball blade is angular and the processed surface is creased.

On the other hand, Japanese Patent Application Laid-Open No. Hei 4-310306 discloses a ball end mill suitable for cutting a soft material such as aluminum in which the angle difference between the torsion angles of the ball blade and the outer peripheral cutting edge is set to 7 ° or less. It has been proposed to make the rake face smoothly continuous or to set the rake angle of the ball blade at a right angle of rake within the range of 10 ° to 25 °, but it was not always satisfactory.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a non-ferrous metal ball capable of obtaining high machining efficiency and excellent machined surface quality in soft non-ferrous metal cutting. To provide an end mill.

[0006]

According to the present invention, a pair of ball blades is provided symmetrically with respect to an axis at a hemispherical portion at the tip, and a pair of ball blades are provided continuously with the ball blades. A non-ferrous metal ball end mill provided with an outer peripheral cutting edge twisted around an axis, wherein (a) a diameter of a circular region A in which the pair of ball blades does not exist at the center of the hemispherical portion is: (B) the overlapping dimension t of the pair of ball blades at the center thereof is within the range of 0 to 0.08 mm, and (c) the right angle of the pair of ball blades. The rake angle is in the range of 10 ° to 20 °, and (d) the pair of ball blades are each smoothly connected to the outer peripheral cutting edge.

[0007]

According to the ball end mill for a non-ferrous metal of the present invention, since the diameter of the circular area A where the ball blade at the center of the tip does not exist is as small as 0.02 to 0.08 mm, the cutting action is reduced. Since the area that cannot be obtained is extremely small and the rake angle at the right angle of the ball blade is as large as 10 ° to 20 °, the sharpness of the hemispherical portion at the tip is improved as a whole, so that excellent cutting performance is obtained and the machining surface is obtained. Quality is improved.
In addition, since the pair of ball blades are each smoothly connected to the outer peripheral cutting edge, there is no squareness at the connection portion thereof, so that the processing surface is prevented from being streaked, and the processing surface quality is also improved in this respect. At the same time, the rake faces of both are connected relatively smoothly, so that the chip discharging performance is improved. As described above, since the cutting performance and the chip discharging performance are improved, high-efficiency machining by high-speed rotation and high-speed feeding becomes possible.

On the other hand, the overlapping dimension t of the pair of ball blades
Is in the range of 0 to 0.08 mm, so that the mechanical strength of the ball blade does not significantly decrease regardless of the reduction of the circular area A, and has a sufficient strength for soft materials such as aluminum. Can be secured.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The ball end mill for non-ferrous metals of the present invention is suitably used for cutting relatively soft non-ferrous metals such as aluminum alloys, copper, and copper alloys. It can also be used for cutting materials other than non-ferrous metals such as materials. As the material of the ball end mill, a hard material such as a cemented carbide is suitably used. Only the blade portion where the ball blade or the outer peripheral cutting edge is formed may be made of a hard material.

The outer peripheral cutting edge may be provided on a cylindrical surface having a constant diameter, or may be provided on a tapered surface having a changing diameter.

The diameter of the circular area A is 0.02 to 0.0
It is desirable to be as small as possible within the range of 8 mm,
If it is smaller than 0.02 mm, it becomes difficult to obtain the required strength. If it is larger than 0.08 mm, the effect of improving the cutting performance and the quality of the machined surface cannot be sufficiently obtained.

The overlapping dimension t of the pair of ball blades is such that the thickness of the blade is thin in a region where the ball blades overlap substantially in parallel (a circular region A).
The diameter may be set within the range of 0 to 0.08 mm. However, if the diameter is larger than the diameter of the circular area A, the chipping is likely to occur.
It is desirable to set the diameter to be approximately the same as or smaller than the diameter of.

The right angle rake angle of the pair of ball blades is 10 °
It is desirable that the angle be as large as possible within the range of 20 °, but if it is larger than 20 °, it becomes difficult to obtain the required strength. If the angle is smaller than 10 °, the effect of improving the cutting performance and the quality of the machined surface cannot be sufficiently obtained.

The pair of ball blades may be smoothly connected to the outer peripheral cutting edge, respectively. In order to connect the two blades smoothly, the angle difference between the torsion angles (=
The helix angle of the outer peripheral cutting edge-the helix angle of the ball blade) is 0 to 3
It is desirable to be within the range of °. The outer peripheral cutting edge is usually formed with a constant torsion angle in the entire axial direction, whereas the ball blade is provided three-dimensionally on a hemisphere, so that the torsion angle as viewed from the direction perpendicular to the axis is continuous. Therefore, the angle difference between the torsion angles at least at the connection portion between the two may be 3 ° or less, since it changes gradually and becomes smaller as it approaches the center of the tip (becomes substantially parallel to the axis). Note that the torsion angle is gradually changed, for example, at the time of grooving or grinding after grooving so as to prevent angling at the connection portion between them.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view of a ball end mill (hereinafter, simply referred to as a ball end mill) 10 for a non-ferrous metal according to an embodiment of the present invention as viewed from a direction perpendicular to an axis.
FIG. 3 is a view showing the shape of the tip of the ball end mill 10. FIG. 2B is a plan view of the ball end mill 10 viewed from the front end side, FIG. 2A is a left side view of the ball end mill 10 viewed from the left side of FIG.
(d) is a front view as viewed from below (b), and (c) is an enlarged view near the center (axial center) of (b).

The ball end mill 10 has a cylindrical shank 12 and a blade 14 concentrically provided at one end of the shank 12 with the same diameter, and is integrally formed of a cemented carbide. I have. The blade portion 14 is provided with a pair of ball blades 16 symmetrically with respect to the axis at the hemispherical portion at the tip, and an outer peripheral cutting edge 18 that is twisted around the axis continuously from the ball blade 16. Is provided.
The diameter of the blade portion 14 in this embodiment is 10 mm (R of the hemispherical portion = 5 mm).

The pair of ball blades 16 are formed so as to form a substantially S-shape in plan view shown in FIG. 2B, and the pair of ball blades 16 does not exist at the center (axial portion). The diameter of the circular area A, that is, the minimum inscribed circle (see FIG. 2 (c)) in contact with the two ball blades 16 about the axis is in the range of 0.02 to 0.08 mm. The overlap size t of the pair of ball blades 16 at the center thereof (see also FIG. 2 (c)) is substantially the same as or smaller than the diameter of the circular area A within the range of 0 to 0.08 mm. Have been.

The rake angle of the pair of ball blades 16 at a right angle to the blade, that is, the rake angle in a cross section perpendicular to the cutting edge is 10 ° to 10 °.
The angle is in the range of 20 °, and in the embodiment, in the range of 13 ° to 15 °. The ball blade 16 is provided three-dimensionally by forming a gash on a hemispherical surface, and the rake angle perpendicular to the blade has substantially the same size over the entire area.

The pair of ball blades 16 are smoothly connected to the outer peripheral cutting edge 18, respectively. That is, in this embodiment, the torsion angle of the outer peripheral cutting edge 18 is constant at about 30 °, whereas the ball blade 16 is provided three-dimensionally on a hemispherical surface, so that the torsion angle as viewed from the direction perpendicular to the axis is obtained. The angle changes continuously and becomes smaller as it approaches the center of the tip (becomes substantially parallel to the axis), but the angle difference of the torsion angle at the connection portion between the ball blade 16 and the outer peripheral cutting edge 18 (= outer peripheral cutting) The torsion angle of the ball blade 16 at the connection portion is in the range of about 27 ° to 30 ° so that the torsion angle of the blade 18−the torsion angle of the ball blade 16 is in the range of 0 to 3 °. It is gradually changed so that tension does not occur. The ball blade 16 and the outer peripheral cutting edge 18
The rake face is also smoothly connected like the cutting edge.

The ball end mill 1 of this embodiment as described above
According to No. 0, since the diameter of the circular area A where the ball blade 16 at the center of the tip does not exist is as small as 0.02 to 0.08 mm, the area where the cutting action cannot be obtained is extremely small. Since the rake angle at a right angle of the blade is as large as 13 ° to 15 °, the sharpness of the hemispherical portion at the tip is improved as a whole, so that excellent cutting performance is obtained and the quality of the machined surface is improved. In addition, the pair of ball blades 16 are each the outer peripheral cutting edge 1.
8 smoothly connected to each other, so that there is no squareness in the connecting portion thereof, and it is possible to prevent the processing surface from being creased. In this respect, the quality of the processing surface is improved, and the rake surfaces of both surfaces are also smooth. Because of the connection, the chip discharge performance is improved. Since the cutting performance and chip discharge performance are improved in this way,
High-efficiency machining by high-speed rotation and high-speed feed becomes possible.

On the other hand, the overlapping dimension t of the pair of ball blades 16 is substantially the same as or smaller than the diameter dimension of the circular area A within the range of 0 to 0.08 mm.
Regardless of the reduction of the circular area A, there is no possibility that the mechanical strength of the ball blade 16 is significantly reduced, and a practically sufficient strength can be obtained for a soft material such as aluminum.

By the way, using the ball end mill 10 (the product of the present invention) and the conventional product, cutting is performed under the following processing conditions, and the cutting speed, the surface roughness, and Table 1 shows the results of examining the load meter increase amount (load increase amount). The circular area A of the conventional product is 0.1 to 0.3 mm, the overlap dimension t of the ball blade is 0.2 to 0.4 mm, and the rake angle of the ball blade at a right angle is 3 °.
The angle difference between the twist angles of the ball blade and the outer peripheral cutting edge is 15 ° to 20 °. (Processing conditions) Work material C1100P (copper) Processing method Groove cutting (rough processing) Infeed AD (axial depth) = 3 mm, Pf (pic feed) = 7 mm Processing machine Makino Milling A55 Cutting oil Water-soluble cutting oil (Yushiro Chemical EZ-30 1
0 times)

[0023]

[Table 1]

In Table 1, the shaded area (gray zone) is an unstable area, which is comprehensively determined from the cutting noise, the surface roughness, and the load meter increase. As is clear from Table 1, according to the product of the present invention, stable cutting performance can be obtained up to a feed rate higher than that of the conventional product in a region where the tool rotation speed is 15,000 or less, and high efficiency by high-speed feeding is obtained. Processing is possible.

Table 2 shows that AD = 0.5 mm, Pf = 1 mm
And the other conditions are the same as above. In Table 2, the lightly shaded area (light gray zone) is an unstable area, and the darkly shaded area (dark gray zone) is an unworkable area. It has been determined in a comprehensive manner. As is clear from Table 2, according to the product of the present invention, stable cutting performance can be obtained up to a feed rate higher than that of the conventional product at any tool rotational speed, and high-efficiency machining by high-speed rotation and high-speed feed is achieved. Is possible.

[0026]

[Table 2]

The embodiments of the present invention have been described in detail with reference to the drawings. However, these embodiments are merely examples, and the present invention is based on the knowledge and knowledge of those skilled in the art. Can be implemented.

[Brief description of the drawings]

FIG. 1 is a front view of a ball end mill for non-ferrous metal according to one embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing the shape of the tip of the ball end mill of FIG. 1, wherein FIG. 2B is a plan view as seen from the tip side, FIG. 2A is a left side view as seen from the left side of FIG. Is a front view from the bottom of (b),
(c) is an enlarged view near the center (axial center) of (b).

[Explanation of symbols]

10: Ball end mill for non-ferrous metals 16: Ball blade 18: Outer cutting edge

Claims (1)

[Claims] 1. A non-ferrous iron having a pair of ball blades provided symmetrically with respect to an axis at a hemispherical portion at a tip thereof, and an outer peripheral cutting edge twisted around the axis continuously to the ball blades. A ball end mill for metal, wherein the diameter of the circular area A where the pair of ball blades does not exist at the center of the hemispherical portion is within a range of 0.02 to 0.08 mm, The overlapping dimension t of the ball blades is in the range of 0 to 0.08 mm, the right angle rake angle of the pair of ball blades is in the range of 10 ° to 20 °, and the pair of ball blades is Ball end mill for non-ferrous metals characterized by being connected smoothly.