JPH08290314A - High speed cutting ball end mill - Google Patents

Abstract

PURPOSE: To perform cutting with high efficiency by making the rake of an end cutting edge of circular arc shape negative. CONSTITUTION: In a ball end mill made of ultrafine-grain hard metal of about 10mm in diameter, about 15mm in length of cut and about 100mm in overall length with two cutting edges, a helix angle is about 30 deg., the rake of the peripheral cutting edge is about -10 deg., and the rake of a ball part changes continuously from the maximum of about 10 near the peripheral cutting edge to about 0 deg. at a nose. A body 1 is provided with a coolant hole 4 of about 1.2mm in diameter having the same torsion as the peripheral cutting edge. This hole 4 is opened to the flank relief side of a ball cutting part. In the opening part, only the cutting edge side periphery of the hole 4 (the position of two - thirds or less of the cutting edge diameter) is chamferred, and the cutting edge part is covered with (TiAl)N. When this tool is applied to cut hot tool steel, quenched to a hardness of HRC about 40, with depth of cut about 1mm, at the rotating speed of about 10000rpm and at the feed speed of about 1m/min, the discharge of chips is excellent, and cutting can be performed for many hours.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball end mill mainly used for machine tools, and particularly for high speed cutting used for three-dimensional forming of a die. The present invention relates to a ball end mill used for machine tools. 2. Description of the Related Art As a conventional ball end mill, there is a tapered ball end mill with a hole described in Japanese Utility Model Laid-Open No. 59-28410 shown in FIG. 1, which is made fine by providing a coolant hole. It describes a tapered ball end mill that discharges chips even when machining deep parts. [Problems to be Solved by the Invention] Recently, the mold 3
In three-dimensional forming, there is an increasing need for shifting from manual finishing to high-speed finishing by machining, which makes it necessary to cut a long distance with a small incision. Has no choice but to use high-speed, high-feed cutting. However, when the above ball end mill is subjected to three-dimensional processing, since the shape and coolant hole are adapted to the use of deep grooves, etc., the chip discharge is supplied from the hole instead of the smooth. There is a problem that it is difficult for the cutting fluid and the air to work effectively. SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and in particular, a ball end mill used for a machine tool for high speed cutting used for three-dimensional molding of a mold. Is provided. In order to achieve the above-mentioned object, the present invention is a ball end mill provided with a coolant hole, wherein the rake angle of the arcuate bottom blade is negative,
Further, an opening portion of a hole is provided on the flanks of the adjacent arc-shaped bottom blades, and the opening portion is provided at a position not more than 2/3 of the blade diameter of the ball end mill. To correspond to Al, Si, Periodic Table 4
a, 5a, 6a transition metal carbide, nitride, boride and boron carbide, hard boron nitride, hard carbon, and one or more hard selected from the group consisting of solid solutions or mixtures thereof. The substance is coated in one layer or two or more layers in a thickness of 0.2 to 20 μm. By applying the present invention, the rake angle of the ball blade portion is set to a negative angle, so that the chips generated by the cutting edge are generated at the same time as the chips move away from the rake face. ,
The discharge of chips from the cutting part becomes smooth, and the cutting fluid and air supplied from the hole effectively act to discharge chips quickly, enabling highly efficient machining. . Further, the opening of the hole is provided on the flanks of the adjacent arc-shaped bottom blades, for high-speed cutting, the hole opening position is separated from the cutting edge, and the cooling effect is exerted on the entire cutting edge. It is arranged so as to match the direction in which chips are scattered by holding it and making the rake angle negative. Further, the opening is located at a position not more than ⅔ of the blade diameter of the ball end mill so that the rake angle can be made negative so that the shavings can be quickly discharged. This is because Next, a hard substance is coated on the cutting edge to reduce frictional resistance, and further, due to the effect of reducing friction due to coating, more efficient workability can be obtained. Hereinafter, examples will be described in detail. FIG. 2 shows an embodiment of the present invention, which is made of ultrafine particle cemented carbide, diameter 10 mm, blade length 15 mm, total length 100.
mm, the number of blades is two, the ball end mill has a helix angle of 30 °, the rake angle of the outer peripheral blade is -10 °, and the rake angle of the ball portion is 10 ° from the maximum in the vicinity of the outer peripheral blade to zero.
It changes continuously up to °. The main body is provided with a coolant hole having a diameter of 1.2 mm and having the same twist as the outer peripheral blade. The hole is open to the flank of the ball blade, and the opening is chamfered only around the cutting edge of the hole. Further, the cutting edge portion was coated with (TiAl) N. Cut this tool 1mm, rotation speed 10000
When used for cutting hot tool steel hardened to hardness HRC40 at rpm and feed rate of 1 m / min, chip discharge is excellent and stable cutting can be performed for a long time, compared to general ball end mills. It was possible to cut for four times as long. As described above, according to the present invention, improvements have been made in a ball end mill suitable for a machine tool for high-speed cutting, which is particularly used for three-dimensional molding of a mold.
Highly efficient cutting has become possible.

[Brief description of drawings] FIG. 1 shows a front view of a conventional product. FIG. 2 shows a front view of an embodiment of the present invention. 3 shows a side view of FIG. [Explanation of symbols] 1 body 2 blades 3 ball blades 4 holes α twist angle β rake angle

Claims (1)

Claim: What is claimed is: 1. A ball end mill having a coolant hole, wherein a rake angle of an arc-shaped bottom blade is negative, and a hole is provided on a flank of the adjacent arc-shaped bottom blades. The ball end mill for high-speed cutting, characterized in that the opening is provided at a position not more than 2/3 of the blade diameter of the ball end mill. 3. The ball end mill for high speed cutting according to claim 1, wherein Al, Si and periodic table 4a, 5a, 6 are used.
One layer of one or two or more hard substances selected from the group consisting of carbides, nitrides, borides and boron carbides of group a transition metals, hard boron nitrides, hard carbons, and solid solutions or mixtures thereof. Or a multilayer of two or more layers, 0.2
A ball end mill for high-speed cutting, which is coated with a thickness of up to 20 μm.