JPH06218617A - End mill - Google Patents

Abstract

PURPOSE:To provide a general-surface end mill by improving surface roughness in the vicinity of a cutting edge in an end mill, etc. CONSTITUTION:In an end mill for cutting metal materials, on the rake face and the relief face in the vicinity of a cutting edge, for a width 2mm or less the means roughness at ten points, Rz is set at 0.5mum or smaller in irregularilty measurement. Accordingly, the instability of cutting edge is eliminated, high precision in finish cutting is obtained and further uniform coating becomes easy, so that edge tip strength and cutting efficiency are increased and high accuracy is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a general-purpose end mill used for machine tools such as milling machines and machining centers.

[0002]

2. Description of the Related Art As a rotary tool of this kind for cutting general materials such as steel materials by using a machine tool such as a milling machine or a machining center, there are end mills suitable for various uses such as a squarer, a ball and a taper. Further, as the material thereof, high speed steel, super hard metal, cermet, etc. are used according to the purpose.

For example, an end mill called steel cutting has a positive rake angle, a high feed rate for rough cutting, a small feed rate for finish cutting, and a small feed rate for finishing. Ingenuity has been made to obtain precision and cutting surface roughness. In addition, the life of coating end mills etc. is roughly divided into wear precedent type and chipping precedent type, and it is wear precedent type for light cutting such as finishing, but chipping and chipping occur during general use, so The main process is breaking.

Therefore, when observing the wear state at the initial stage of use, one of the causes of chipping is the problem of peeling of the coating film, and particularly in the PVD method in which the coating treatment is carried out at a low temperature, the roughness of the ground surface is large. The coated end mill is improved by reducing the roughness and unevenness of the ground surface as in Japanese Patent Application No. 4-164383 filed by the present applicant.

[0005]

However, paying attention to the grinding surface roughness or surface quality near the end mill cutting edge,
By examining the grindstone count (grinding stone grain size), concentration, particle shape, etc., stable cutting is achieved by reducing chipping of the cutting edge, abnormal wear, and film peeling in the case of coating with conventional surface quality. It was difficult to get normal wear.

[0006]

SUMMARY OF THE INVENTION Therefore, according to the present invention, in an end mill for cutting a metal material, the roughness of the ground surface is 10 mm in a width of 2.0 mm or less from the cutting edge in the direction of the rake face and flank near the cutting edge. This is done by improving the grinding method for finishing the point average roughness Rz to 0.5 μm. Furthermore, when coating is performed, the adhesion to the substrate is improved, and the unevenness of the film is reduced, so that a smooth surface is obtained and the peeling resistance of the film is improved. The 10-point average roughness Rz is used because when the surface roughness is represented by Rmax (maximum height), the entire surface cannot be expressed and therefore does not correlate with the performance. With the roughness meter, the end mill itself is a curved cutting edge, so its irregularities cannot be grasped sufficiently, and in particular, it is difficult to measure the roughness of the rake face, and the photographic method was used.

[0007]

In the end mill, the sharper the tip of the cutting edge, the more the surface roughness of the surface forming the cutting edge contributes to the shape of the edge line. That is, reducing the surface roughness of the rake face and the flank face enhances the sharpness of the cutting edge, and the effect is remarkable. Further, even in an end mill that has been subjected to a cutting blade treatment of about 2 to 30 μm, if the surface roughness of the portion subjected to the cutting blade treatment is improved, the same effect is obtained.

Further, in the coated end mill, the sharp edge portion is apt to cause overheating, uneven film thickness, and film roughness during vapor deposition, but this cutting edge treatment can prevent overheating of the cutting edge. Since the overheated portion is reduced, the film thickness becomes more uniform and the cutting performance is stabilized.

[0009]

EXAMPLE An end mill having a tool blade diameter of 10 mm, two blades and a right blade with a right twist is used, and the rake angle of the outer peripheral cutting edge is 10 ° and the clearance angle is 10 ° at right angles to the axis. Since it is difficult to measure the ground surface roughness of the cutting edge due to the conventional contact type surface roughness twisted cutting blade, the 10-point average roughness was examined while observing with an SEM or the like.

A conventionally used method is used for grinding,
Wheel abrasive grains (grain size, concentration,
As a result of examining the particle shape), the specifications of grinding, especially the cutting amount, the feed amount, etc., after grinding the flute part of the end mill, an eccentric blade was attached to prepare a sample. The section of that part is SE
It was enlarged with M and the average roughness was measured at 10 points. 10-point average roughness is in accordance with JIS B0601, and the roughness of peaks and valleys is 1μ
Since it is m or less, the reference length is set to the minimum value of 0.08 mm. The surface roughness was measured by changing the grain size, concentration, and abrasive grain shape on the blade edge side of the creep grinding wheel to improve the surface roughness. In addition, the wheel was changed for the eccentric blade attachment as well.

FIG. 1 schematically shows a cross section of the rake face observed by SEM. As a result of measuring the 10-point average roughness Rz from FIG. 1, it was 0.29 μmRz, and the unevenness was reduced as a whole. As shown in FIG. 2, when the wheel was not changed, the width was 0.89 μm, and the peaks and valleys were sharp and the peaks and valleys were clear.

Next, in the cutting test, the length of the chipping on the cutting edge caused by 1 m cutting was evaluated by the ratio to the total cutting edge length, the cutting speed was 40 m / min, and the cutting depth A was set.
d = 10 mm, Rd = 5 mm, feed per blade fz =
As a result of cutting five pieces with the specifications of 0.2 mm / tooth, the work material-structural steel, the product of the present invention was 0, 0, 0,
While it was 0, 0%, the conventional product had 5.9, 2.
The chipping was 5, 6.5, 4.9, 6.8% from the initial cutting.

Then, after similarly honing a sample manufactured in the same manner, coating TiN of 2 μm was applied, and then a cutting test was conducted in the same manner. Was evaluated by the ratio. Cutting speed 100m / min, cut Ad = 10m
m, Rd = 5 mm, feed per blade fz = 0.2 mm /
As a result of performing 5 cuttings with the specifications of tooth, work material-structural steel, the product of the present invention showed normal wear,
1.2, 2.2, 0.9, 1.0, 0.8% for conventional products
Although some chipping occurred, these chippings peeled off a part of the film, which is considered to affect the life.

[0014]

As described above, according to the present invention, by improving the ground surface roughness in the vicinity of the cutting edge of the end mill,
The instability of the cutting edge can be eliminated, high precision can be maintained even in finish cutting, it is easier to apply a uniform coating, overheating of sharp edges can be prevented, and overheating can be eliminated Become uniform

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing an SEM photograph of FIG.

FIG. 2 is an explanatory view schematically showing an SEM photograph showing a conventional example.

Claims (2)

[Claims] 1. In an end mill for cutting a metal material, a 10-point average roughness Rz is obtained by measuring the roughness of a ground surface with a width of 2 mm or less from the cutting edge in the direction of the rake face and the bald surface near the cutting edge. The end mill is characterized in that it is 0.5 μm or less. 2. The end mill according to claim 1, wherein the coating layer is Al, Si, 4a, 5a, 6a of the periodic table.
Group 1 transition metal carbides, nitrides, oxides, borides, and one or more hard selected from the group consisting of boron carbide, hard boron nitride, hard carbon, and solid solutions or mixtures thereof. An end mill characterized in that the substance is coated in a thickness of 0.2 to 20 μ in a single layer or in a multilayer of two or more layers.