JPH0832383B2 - End mill - Google Patents

Description

TECHNICAL FIELD The present invention relates to an end mill capable of preventing welding of a work material to a cutting edge and vibration of a tool.

[Prior Art] FIGS. 4 and 5 show a conventional end mill. In the end mill shown in FIG. 4, two chip discharge grooves 2, 2 are formed on the outer periphery of a cylindrical end mill body 1. At the same time, a gash 3, 3, which is continuous with the chip discharge groove 2, is formed at the tip of the end mill body 1, and an outer peripheral blade 4 is provided on the outer edge of the wall faced in the rotation direction of the chip discharge groove 2 and a tip edge of the gash 3. The bottom blade 5 is formed. Further, in the end mill shown in FIG. 5, one bottom blade 6 is formed longer than the other bottom blade 7.

Such an end mill performs groove processing and recess processing, and particularly when processing recesses, the end mill is first sent in the axial direction to be dug by the bottom blades 5 (6, 7), and then By cutting the work with the outer peripheral blade 4 by laterally feeding the table on which the work material is attached, it is possible to carry out the recess work such as the die carving.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional end mill, in particular, when the digging process is performed, a periodic lateral shake is likely to occur, and in some cases, the table or the spindle is shaken so that the machining accuracy becomes extremely high. It may worsen or cause abnormal noise, and may even lead to an end mill cutting accident. For this reason, in the case of digging, the feed of the end mill has to be greatly reduced, and there is a problem that the processing efficiency of cutting is reduced.

That is, when the end mill is fed in the axial direction, pressure is applied to the spindle that rotates the end mill, increasing the frictional resistance between the flank surface of the bottom blade and the work material, and the work material is welded to the flank surface and gradually accumulates. Proceed to wear. Then, when the coagulate is fully developed, the end mill tries to shift to a more stable state, which causes the table and spindle to shake, but at the same time, the coagulum falls off and the table and spindle are removed. The state is restored to the above state, and the periodic lateral shake occurs in this way.

[Object of the Invention] The present invention has been made in view of the above circumstances, and can prevent adhesion of a work material to a flank, thereby preventing occurrence of lateral runout during excavation. It is intended to provide an end mill that can be used.

[Means for Solving the Problem] In the end mill of the present invention, a first flank is provided along the bottom blade, and a clearance larger than the clearance angle of the first flank is provided rearward in the rotational direction of the first flank. In the end mill provided with the angled second flank, the width of the first flank in the rotation direction is set to be smaller on the inner peripheral side than on the outer peripheral side.

[Operation] The welding of the work material as described above occurs in the conventional end mill for the following reason.

FIG. 6 illustrates the advancing angle of the bottom blade with respect to the plane when the digging process is performed with constant feed over the entire bottom blade. The feed per revolution of the bottom blade is the same on the outer peripheral side and the inner peripheral side of the bottom blade, but the length of rotation in one rotation is shorter on the inner peripheral side of the bottom blade than on the outer peripheral side. For this reason, the outer peripheral side of the bottom blade plunges from the point B to the point A ₀ , and the inner peripheral side plunges from the point B to A ₁ , and the inner peripheral side has a sharper angle (α ₀ , α ₁ than the outer peripheral side). It can be understood that plunge in (illustration). In other words, the inner circumference side has a second contact more significantly than the outer circumference side. Therefore, if the clearance angle of the flank is set to match the outer circumference side, welding of the work material will occur on the inner circumference side. .

The present invention is based on the above knowledge, and as the width of the first flank in the rotational direction becomes smaller on the inner peripheral side than on the outer peripheral side, the first flank becomes closer to the inner peripheral side. The area of contact with the work material becomes smaller. Therefore, on the inner peripheral side, the amount of heat generated by the frictional resistance does not increase despite the large advancing angle of the bottom blade, and thus welding of the work material can be prevented. Further, by setting the clearance angle of the first flank to be larger on the inner peripheral side than on the outer peripheral side, the welding of the work material can be prevented more effectively.

[Embodiment] FIG. 1 is a perspective view of an end mill according to an embodiment of the present invention. Like the conventional end mill, two chip discharge grooves are formed on the outer periphery of a cylindrical end mill body 10. In addition, a gash continuous with the chip discharge groove is formed at the tip of the end mill main body 10, an outer peripheral blade 13 is formed on the outer peripheral ridge of the wall surface facing the rotation direction of the chip discharge groove, and a bottom blade 14 is formed on the tip ridge of the gash 12. It was done.

In the end mill of this embodiment, the first flank 20 is formed along the bottom blade 14 and the first flank 20 is formed.
A second flank 21 having a larger clearance angle than the clearance angle of the first flank 20 is formed on the rear side in the rotational direction of. And
The first flank 20 is formed in a triangular shape when viewed from the front end in the axial direction so that the width in the rotation direction becomes gradually narrower from the outer peripheral side toward the inner peripheral side.

In the end mill thus configured, the width of the first flank 20 becomes gradually narrower toward the inner peripheral side, and thus the area of contact with the work material becomes smaller toward the inner peripheral side. Therefore, on the inner peripheral side, the amount of heat generated by the frictional resistance does not increase despite the large traveling angle of the blade portion 14,
As a result, welding of the work material can be prevented, and the same effect as that of the above-described embodiment can be obtained.

In this embodiment, the clearance angle of the first flank 20 is set to be larger on the inner peripheral side than on the outer peripheral side, whereby the welding of the work material can be prevented more effectively.

Further, the width of the first flank 20 does not have to change linearly as in this embodiment. That is, it is not limited to the case where the intersecting ridgeline of the first flank 20 and the second flank 21 is a straight line, and may be a convex curve or a concave curve in the rotation direction. Further, the first flank 20 does not need to be formed so that the width becomes zero at the center of rotation as in this embodiment, and may have a constant width at the center. Further, the bottom blade 14 may be formed so that the width becomes zero at the middle portion in the longitudinal direction.

By the way, the present invention is not limited to the above-mentioned two-blade end mill, and is applied to an end mill having a single-blade or a larger number of blades, or an end mill called unequal division in which the lengths of bottom blades are different from each other. Of course, the same effect can be obtained.

Next, FIGS. 2 and 3 show another embodiment of the present invention. In the end mills shown in these figures, one bottom blade 20 is formed shorter than the other bottom blade 21. In the figure, reference numeral 22 is a first flank. Similar to that shown in FIG. 1, the first flank 22 is formed so as to become gradually narrower from the outer peripheral side toward the inner peripheral side. The first flank 22 is formed so that its width becomes zero in the longitudinal middle portion of the bottom blades 20, 21.

A second flank 23 having a clearance angle larger than the clearance angle of the first flank is formed behind the first flank 22 in the rotation direction, and further behind the second flank 23 in the rotation direction. A third flank 24 having a larger clearance angle than the clearance angle of the second flank is formed. A nick 25 is formed on the tip surface of the end mill main body 10 configured as described above.

The nick 25 is formed so as to scrape off the axial side end of the shorter bottom blade 22, and extends in a direction inclined by an angle α with respect to the direction orthogonal to the bottom blades 20 and 21. This inclination angle α is set to 10 ° to 40 °. As a result, the second flank 23 is largely scraped off compared to the width of the nick 25,
Second hit is effectively prevented. A tilt angle α of 10 ° is sufficient for end mills that use relatively small feeds, but about 40 ° is required for end mills that use large feeds. Further, the nick 25 is formed such that the bottom surface 25a thereof is inclined downward in the rotation direction.

In the end mill configured in this way, one of the bottom blades 20
Of these, the nick 25 part is left uncut because it is not cut. Since the other bottom blade 21 cuts this uncut portion, one hole can be cut by the entire bottom blades 20 and 21. In the end mill, since the surface of the second flank 23 near the nick 25 is scraped off, friction with the work material does not occur at that portion, and welding of the work material is prevented. Moreover, since the nick 25 is located in the vicinity of the axis line where the movement angle of the bottom blade 20 is large, the effect of providing the nick is maximized. Further, since the nick 25 is inclined with respect to the rotation direction, a wide range of the second flank 23 is scraped off. Therefore, it is possible to prevent the welding of the work material over a wide range of the second flank 23 without enlarging the uncut portion.

The present invention does not limit the sectional shape of the nick 25 at all. For example, various shapes such as a rectangular shape, an arc shape, and an elliptical shape can be applied. Further, the width of the nick 25 may be constant, or may be set so as to gradually widen toward the rear in the rotation direction. Also Nick 25
The position of may be near the axis, but it is 1.5 mm away from the axis where the advancing angle of the bottom blades 20 and 21 sharply increases (12th
It is effective if it is formed so as to include the range up to the figure). Furthermore, a plurality of nicks 25 may be formed, or both nicks 25 and 21 may be formed.

[Effects of the Invention] As described above, in the end mill of the present invention, the first flank is provided along the bottom blade, and is larger than the clearance angle of the first flank in the rear of the first flank in the rotation direction. In the end mill provided with the second flank having the clearance angle, the width of the first flank in the rotation direction is set to be narrower on the inner peripheral side than on the outer peripheral side. It is possible to prevent welding of the work material. Therefore, it is possible to prevent lateral runout of the table and the spindle caused by the adhesion of the work material, increase the feed rate for the digging process, and perform the cutting process efficiently. Obtainable.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a perspective view of another embodiment, FIG. 3 is an axial end view thereof, and FIGS. Fig. 6 is a perspective view showing the end mill of Fig. 6, and Fig. 6 is a diagram for explaining the advancing angle of the bottom blade. 10 …… End mill body, 14 …… Bottom blade, 20 …… First flank, 21 …… Second flank,

Claims (2)

[Claims] 1. A bottom blade extending from an outer peripheral side to an inner peripheral side is provided at a tip of an end mill main body rotated about an axis, and a first flank is provided along the bottom blade, and the first flank is provided.
In an end mill in which a second flank having a clearance angle larger than the clearance angle of the first flank is provided behind the flank in the rotation direction, the width in the rotation direction of the first flank is set to be smaller on the inner peripheral side than on the outer peripheral side. An end mill characterized by being set to be narrow. 2. The end mill according to claim 1, wherein the clearance angle of the first flank is set to be larger on the inner peripheral side than on the outer peripheral side.