JPH06270007A - End mill for working hard brittle object - Google Patents

Abstract

PURPOSE:To improve the working precision for a hard brittle object by installing an outer peripheral cutter in a spiral form at an outer peripheral part and installing an edge surface cutter extending in a radial direction at the edge surface and setting the rake angle in the radial direction of the outer peripheral cutter to a specific negative angle, as for the edge part for a shank. CONSTITUTION:An end mill 1 formed from the sintered material of a powder vice has a cutter part 3 formed integrally at the lower edge part of a cylindrical shank 2, and the outside diameter D1 of the cutter part 3 is made smaller than the outside diameter D2 of the shank 2, and an outer peripheral cutter 4 having a spiral form is formed on the outer peripheral part, and an edge surface cutter 5 extending in the radial direction is formed at the edge surface. In this case, the rake angle in the radial direction of the rake surface of the outer peripheral cutter 4 is made negative, and the negative angle is increased gradually towards the basic part along the axis line direction from the top edge side of the cutter part 3. In other words, the negative angle on the top edge side is set to about 20 deg., and the negative angle on the basic part side is set to about 35 deg. Accordingly, the rigidity of the cutter part 3 is increased, and the vibration and resonance in cutting are suppressed, and the working of hard a brittle article is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill used in a milling machine or the like, and more particularly to an end mill for processing hard and brittle materials suitable for processing hard and brittle materials.

[0002]

2. Description of the Related Art As a conventional technique, a blade portion made of a super hard alloy is integrally provided at one end portion in the axial direction of a shank, and the blade portion has a spiral outer peripheral cutting edge on the outer peripheral portion and extends radially on the end face. There has been an end mill for processing hard and brittle materials that has end face cutting edges, and that the rake angle in the radial direction of the outer peripheral cutting edge is a negative angle, and the negative angle is the same over the entire length.

[0003]

In the above-mentioned prior art, since the negative angle of the rake angle in the radial direction of the outer peripheral cutting edge is formed to be equal over the entire length, the rigidity of the blade portion is from the base to the tip. There is a drawback that vibration and resonance are likely to occur due to cutting resistance, especially when the axial length of the blade portion is increased, and this phenomenon becomes remarkable, making it impossible to perform high-precision machining. It is an object of the present invention to obtain a novel end mill for processing hard and brittle materials that eliminates the above drawbacks.

[0004]

The present invention is configured as follows to achieve the above object. That is, a blade portion made of a superhard alloy is integrally provided at one end portion in the axial direction of the shank, and the blade portion has a spiral outer peripheral cutting edge on the outer peripheral portion and a hard brittleness having an end surface cutting edge extending in the radial direction on the end surface. In the end mill for machining a work, the rake angle in the radial direction of the outer peripheral cutting edge is set to a negative angle, and the angle of the negative angle is gradually increased from the tip side of the blade section toward the base section. In addition, the negative angle is gradually increased from the tip side of the blade toward the base,
The negative angle on the tip side is about 20 degrees, and the negative angle on the base side is about 35 degrees.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, FIG. 1 is a side view showing an embodiment of the present invention, and FIGS. 2 and 3 are II-II and III-III sectional views thereof. In FIG. 1, reference numeral 1 is an end mill formed of a powdered high-speed sintered material, and a blade 3 is integrally formed on the lower end of a cylindrical shank 2. The blade portion 3 has an outer diameter D1 smaller than the outer diameter D2 of the shank 2, and has a spiral outer peripheral cutting edge 4 on the outer peripheral portion and an end surface cutting edge 5 extending in the radial direction on the end surface.

As shown in FIGS. 2 and 3, the outer peripheral cutting edge 4 has a negative rake angle α in the radial direction of the rake face 4a, and the tip portion (lower end) of the blade portion 3 having the minimum angle. The rake angle α1 in the radial direction of the part) is formed at a negative angle of about 20 degrees, and the rake angle α2 in the radial direction of the base end portion (upper end portion) which is the maximum angle is formed at a negative angle of about 35 degrees. The fact that the rake angle α1 is set to a negative angle of about 20 ° to 35 ° does not mean that there is a clear seaside point where the cutting performance abruptly changes if the rake angle α1 deviates from this, but generally the rake angle α in the radial direction is negative. At the angle of, since the cutting edge is a press cutting that does not bite into the material to be cut, in order to perform this pressing cutting smoothly while maintaining the strength of the cutting edge, it depends on the hardness of the material to be cut,
The rake angle α is preferably a negative angle in the range of 20 to 35 degrees, and 2
If it is 0 degrees or less, the strength of the cutting edge becomes small and the durability becomes poor, and if it exceeds 35 degrees, the cutting edge becomes a burnish enough to rub the material to be cut, which is not preferable.

The twist angle θ of the outer peripheral cutting edge 4 is 45 to
The angle L is set to 65 degrees, preferably 30 to 50 degrees, and the axial length L of the blade portion 3 is set to 1 to 2 times the outer diameter D1 of the blade portion 4. The width of the land 4b of the outer peripheral cutting edge 4 and the clearance angle of the clearance surface 4c are formed to be a 0.03 mm round land and an eccentric arc clearance angle as in the conventional case.

According to the above embodiment, the cross-sectional area of the blade 3 gradually increases from the tip to the base, so that the rigidity gradually increases from the tip to the base. For this reason, the load generated at the tip portion is sufficiently taken up by the base portion, and vibration and resonance do not occur due to the cutting resistance. Further, since the radial rake angle α1 of the outer peripheral cutting edge 4 on the leading end side mainly responsible for cutting is set to the minimum negative angle required, deterioration of cutting performance is not impaired.

[0009]

As is apparent from the above description, according to the present invention, the rake angle in the radial direction of the outer peripheral cutting edge is set to a negative angle, and the angle of the negative angle is gradually increased from the tip end side of the blade portion toward the base portion. Since it is made large, the rigidity of the blade gradually increases from the tip side to the base, vibration and resonance at the time of cutting are reduced, machining of hard and brittle materials can be performed smoothly, and the durability of the blade is improved. Has the effect of increasing the sex.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

3 is a sectional view taken along line III-III in FIG.

[Explanation of symbols]

 1 End mill 2 Holding part 3 Main body 4 Peripheral cutting edge 4a Rake surface 4b Land 4c Relief surface 5 End face cutting edge α Radial rake angle α1 Radial rake angle at the tip α2 Radial rake angle at the base end

Claims (2)

[Claims] 1. A shank of a cemented carbide is integrally provided at one end of the shank in the axial direction, and the shank has a spiral outer cutting edge and an end surface having a radially extending end surface cutting edge. In the end mill for processing hard and brittle materials having, the rake angle in the radial direction of the outer peripheral cutting edge is set to a negative angle, and the angle of the negative angle is gradually increased from the tip side of the blade portion toward the base portion, End mill for processing hard and brittle materials. 2. The negative angle is gradually increased from the tip side of the blade toward the base, the negative angle on the tip side is set to about 20 degrees, and the negative angle on the base side is set to about 35 degrees. The end mill for processing hard and brittle materials according to claim 1, which is formed once.