JPH1170405A - Radius end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a radius end mill to a curved surface working such as inclined cutting even in using a CBN sintered body for a blade tip by setting the radius of a circular-arc cutting edge in the outer circumferential side to a specific size and by providing an internal circumferential blade of medium and low inclination from the circular-arc cutting edge toward the rotation center. SOLUTION: A radius end mill is so formed that a CBN sintered body is fixed to the tip part and, for example, the blade radius is set to 6 mm and the radius of the circular-arc cutting edge 2 is set to 1.5 mm namely, to the 1/4 of the blade radius or the radius smaller than the half of the blade radius. The internal circumferential blade. 3 has a medium and low inclination and has a linear shape. The result of the pocket working by the inclined cutting shows normal abrasion and no chipping after the work. It can be used as a substitute for a square ball end mill and exhibits stable performance without cutting the low-speed-range cutting in the adjacent to the rotation center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool used as a radius end mill, particularly a cutting tool used for milling, etc., and to the stability of the performance and the extension of the service life.

[0002]

2. Description of the Related Art A radius end mill is used as an end mill tool located between a square end mill for performing right-angle shoulder milling and a ball end mill for performing curved surface machining. Since the radius end mill has an intermediate shape between the two, it has been used as a tool for R chamfering such as a mold, but it can perform curved surface processing which is a drawback of a square end mill, There is no low-speed area near the center of rotation, which is a drawback of the ball end mill, and it has been used for curved surface machining. In particular, with the development of machine tools and machining software that control the spindle like MC recently, high-speed machining using small-diameter tools by applying high rotation speeds has become widespread and has been used as a substitute tool for ball end mills. ing. Further, with the increase in speed, there has been proposed a tool using a CBN sintered body only for a blade portion from a cemented carbide solid end mill.

[0003] When a CBN sintered body is used as a cutting edge, the strength is inferior to that of a cemented carbide, and in particular, since the cutting speed near the center of rotation is low, there is a disadvantage that the cutting edge is liable to be chipped or chipped. Was. To solve them,
No. 74722 proposes a tool in which the cutting blade itself is retracted from near the center of rotation of the ball end mill and no cutting blade is provided near the center of rotation. However, even with such a ball end mill, the retraction zone can only be about 0.1 to 0.3 mm, which is smaller than the blade diameter (10 mm in the embodiment). In addition, corner R is added to the square end mill.
An example in which the bottom surface of the gasket is formed in a convex curved shape as in Japanese Utility Model Publication No. 2-30176 is given as an example.

[0004]

In view of the above, in the present application, attention is paid to a radius end mill, and the arc-shaped cutting edge portion is set to about 1/10 to 1/3 of the blade diameter, and a medium-low gradient with a large angle is provided. Prevents the cutting near the center,
This prevents damage at low speeds. More specifically, when the feed direction is the horizontal axis (X axis, Y axis) as in contour line processing, cutting is performed by an arc-shaped cutting edge and an outer peripheral blade connected to the cutting edge, and inclined cutting (spiral cutting) is performed in the axial direction. In the case of ()), the shape is such that the cutting is performed by the inner peripheral blade, but is preferably performed by the outer peripheral blade. For example, when the angle cutting is performed at an angle of 5 degrees, an inner peripheral blade corresponding to the angle is required. Therefore, it is necessary to provide a cutting blade that is inclined from the arcuate cutting blade toward the center of rotation.

[0005]

[Object of the present invention] Therefore, in the present invention, CB
Focusing on the configuration of the inner peripheral blade of a radius end mill using an N sintered body or the like, and providing a tool corresponding to curved surface processing such as inclined cutting by providing the inner peripheral blade with a medium-to-low gradient having a large angle. .

[0006]

In order to solve the above-mentioned problems, the present invention relates to a radius end mill having an arc-shaped cutting edge on the outer peripheral side, wherein R of the arc-shaped cutting edge is set to R smaller than half of the blade diameter, and And a radial end mill provided with an inner peripheral blade having a middle to low gradient from the arcuate cutting blade toward the center of rotation. Further, the angle of the medium-low gradient is 2
The angle is as large as 90 degrees, and the inner peripheral edge is straight,
A radius end mill having a convex arc shape or a stepped shape.

[0007]

According to the present invention, a radius end mill having an arc-shaped cutting edge on the outer peripheral side can be used for curved surface processing, flat surface processing, contouring processing including inclined cutting, and the like. Various uses are possible. Further, the reason why the radius of the arc-shaped cutting blade is set to R smaller than half of the blade diameter is that the R portion remains in a mold or the like,
It is selected in accordance with the specifications, and in the case of spiral cutting, a smaller R is better because a larger R increases the cutting resistance. Preferably 1/10 to 1/3 of the blade diameter
It is about. Next, by providing an inner peripheral blade having a middle to low gradient from the arc-shaped cutting edge toward the center of rotation, the feed direction is set to the horizontal axis (X axis, Y axis) as in a conventional square end mill.
In the case of, no cutting was performed as the inner peripheral blade. Conventionally, in the case of inclined cutting (spiral cutting) which is sent in the axial direction, a medium-low gradient corresponding to the inclination angle is set.

Further, in the present invention, the angle is set to 2 degrees to 90 degrees as the medium to low gradient. However, in the case of machining a large pocket, inclined cutting at a gentle angle is performed. When the angle is about the same, it is necessary to apply the angle more than 2 degrees because the load is too high during inclined cutting.
In the case of small pocket machining, cutting must be performed with a certain degree of strong inclination, and the angle of the middle and low gradient is set to 2 degrees to 90 degrees. In addition, in order to respond variously to such a component shape, the inner peripheral blade having a middle to low gradient may be provided in a straight line, but may be stepped so as not to cut near the center due to the angle of the inclined cutting. Or an arc shape,
In the region where the cutting speed is low near the rotation center, the cutting speed is not involved. Further, a coolant hole may be provided near the rotation center. Hereinafter, the present invention will be described in detail based on examples.

[0009]

1 and 2 show an embodiment of the present invention.
The radius of the radius end mill in which the CBN sintered body was fixed to the tip was 6 mm, and the radius of the arc-shaped cutting edge was 1.5 mm, that is, 1/4 of the radius of the blade. Further, as shown in FIG. 1, the inner peripheral blade having a middle and low gradient was linear. FIG. 2 is a bottom view of FIG. 1, in which two cutting blades and a chip pocket are formed as large as possible to improve chip dischargeability.

Next, a test was carried out by pocket machining by inclined cutting. For comparison, an ordinary square end mill was used. The inclined cutting was performed in pocket processing of 10 mm in width, 200 mm in length, and 20 mm in depth. The work material is pre-hardened steel, cutting speed 500m / min, feed speed 0.5-4m / min, cutting depth 4-6mm.
It was carried out as. The inclined cutting was performed at about 1.3 degrees, and only the final bottom surface was fed sideways. As a result, when the abrasion state after machining 10 pieces was observed, the product of the present invention showed normal abrasion, and the inner peripheral blade was partially cut, but there was no chipping or the like. In the conventional product, chipping was observed because a load was applied to the bottom blade.

[0011]

According to the present invention, the radius end mill can be used as a substitute tool for a square end mill and a ball end mill. In addition, cutting at a low speed region near the rotation center, which is a drawback of the square end mill and the ball end mill, can be performed. Because it is not performed, it exhibits stable performance.

[Brief description of the drawings]

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

FIG. 2 shows a bottom view of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer edge 2 Arc cutting edge 3 Inner edge 4 Chip discharge groove

Claims (3)

[Claims] In a radius end mill having an arcuate cutting edge on the outer peripheral side, the radius of the arcuate cutting edge is set to R smaller than half of the blade diameter, and the middle end has a middle and low gradient from the arcuate cutting edge toward the rotation center. A radius end mill having an inner peripheral blade. 2. The radius end mill according to claim 1, wherein the angle of the middle and low gradient is 2 degrees to 90 degrees. 3. The radius end mill according to claim 1, wherein the inner peripheral blade having the middle / low gradient is formed in a straight line, a convex arc shape, or a stepped shape.