JP2559531Y2 - Ball end mill - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type ball end mill used for die machining.

[0002]

2. Description of the Related Art A conventional example of the above-mentioned ball end mill is disclosed in Japanese Utility Model Laid-Open Publication No. 2-3618. The configuration of this ball end mill is shown in FIGS.
This will be described below.

At the tip of the tool body 1, a main chip 2 and a sub chip 3 are arranged with a phase of about 180 degrees around the axis of the tool body 1. These chips 2 and 3
Each is fixed to the tool body 7 by a bolt 7.

As shown in FIG. 12 and FIG. 13, the main tip 2 of the ball end mill has a convex curved surface with a middle height as a whole when viewed from the side and the bottom, and thus has a feature that the edge strength is high. ing.

[0005]

However, since the main chip 2 has the above-described shape, the range in which the rake angle increases in the negative direction is wide, and accordingly, the cutting force increases. Therefore, there is a problem that chattering occurs when the rigidity of the tool body 1 is insufficient.

The present invention has been made in view of the above circumstances, and has as its object to reduce the cutting resistance while maintaining the edge strength.

[0007]

[Means for Solving the Problems]

[0008] To achieve the above object, claim 1 of the present application.
The plan described in is a plan view is substantially elliptical, and,
A throw-away insert having a main cutting edge having a ridgeline that forms a part of an arc in plan view at two points that are point-symmetrical to each other in a part thereof, the rotation path of the main cutting edge is the axis of the tool body. In the ball end mill, which is detachably attached to the ball-shaped portion at the tip of the tool main body so as to coincide with the spherical surface having the center as the center, the throw-away tip has a center of the throw-away tip in plan view. A straight line that passes is defined as a valley line, and an inclined surface whose thickness gradually increases toward both ends is provided. The inclined surface intersects the valley line at an angle α of less than 90 ° C. with respect to the axis of the tool body. By being attached to the tool body in the direction, the main cutting edge moves forward in the rotational direction of the tool body when viewed from either the side surface or the bottom surface side of the tool body.
The configuration is such that it has a convex convex shape .

According to a second aspect of the present invention, in the first aspect, the main cutting edge extends from the center of the tool main body to the tip of the tool main body in the quadrant arc-shaped main cutting edge. A small cutting edge extending in the opposite direction, wherein the ridge line of the small cutting edge is directed in a direction crossing the axis of the tool body at an angle β of less than 90 ° in plan view. .

According to a third aspect of the present invention, in the second aspect, α is set to 45 ° <α <90 °.

According to a fourth aspect of the present invention, in the second aspect, β is set to 15 ° <β <90 °.

According to a fifth aspect of the present invention, in the fourth aspect, 45 ° <α <90 °.

[0013]

According to the first aspect of the present invention, by providing the inclined surface, an appropriate rake angle with respect to the cutting surface can be secured. In addition, since the cutting edge of the main cutting edge has a convex curved shape in a side view and a bottom view, the total length of the cutting edge is longer than otherwise. According to the invention of claim 2, since the small cutting edge is provided in the direction opposite to the main cutting edge,
The effect of the load on the main cutting edge near the rotation center can be reduced. In the invention of claims 3 to 5, the range of the quadrant of the main cutting edge can be made necessary and sufficient by setting the predetermined range α, and the range of the positive rake angle is set. As a result, cutting resistance can be reduced. Further, by setting the value to β in a predetermined range, the cutting resistance applied to the small cutting edge can be set in an optimum range.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the drawings, the same parts as those of the conventional example are denoted by the same reference numerals, and the description will be simplified. The ball end mill of this embodiment has a tool body 1 of FIG. 1 having substantially the same configuration as the ball end mill described as one conventional example, and a throw-away type tip having a specific shape as shown in FIGS. The basic configuration is such that a chip 10 and an outer peripheral chip 12 having a substantially square shape in a plan view are provided. Each of these indexable inserts 10 and 12 is attached to a predetermined portion of the tool body 1 by a bolt 7.

As shown in FIG. 7, the indexable tip constituting the tip blade 10 has a substantially elliptical shape in plan view, and a bolt hole 14 is provided at the center. The upper surface of the throw-away tip 10 is an inclined surface 16 whose thickness gradually increases toward both ends with a straight line C passing through the center as a valley line. A part of the ridge line from one end to the other end of the throw-away tip 10 is a main cutting edge 18 which forms a part of an arc having the same diameter as a spherical surface to be formed by the throw-away tip. The ridge line from 18 to the other end is a straight line portion 20. Also, the inclined surface 16,
The straight line C serving as the 16 valley lines is set at an angle that intersects the tool main body 1 at an angle of α when the straight line portion 20 is arranged parallel to the axis X of the tool main body 1.

The indexable insert 10 is arranged such that the straight portion 20 is parallel to the axis X of the tool body 1 and the straight portion 20 is located on the opposite side of the arc of the main cutting edge 18 via the axis X. It is attached to be. A small cutting edge 22 is formed between the straight portion 20 and the end of the throw-away tip 10 at an angle β with respect to the axis X.

Therefore, the throw-away tip 1
0, since the upper surface is an inclined surface whose valleys the line C as described above, in the state attached to the tool main body 1, as shown in FIG. 5, the main cutting edge 18 in the bottom view times
The main cutting edge 18 has a convex curve in the rotation direction and a convex curve in the side view as shown in FIG.
Has become.

On the other hand, the tool main body 1 has a first locking wall 30 abutting on a part of the outer periphery of the flank of the main cutting edge 18 of the indexable insert 10 and a flank of the straight portion 20. And a second locking wall 32 that is in contact with each other.
The indexable insert 10 is positioned with respect to the tool body 1. That is, the throw-away tip 10 is positioned in parallel with the axis X by tightening the bolt 14 in a state where it is brought into contact with the locking walls 30 and 32, whereby the valley line C of the inclined surface 16 is formed.
Makes an angle between the tool axis X and α, and the small cutting edge 22 makes an angle between the tool axis X and β.

In the ball end mill having the above configuration, the indexable insert 10 performs cutting by rotating the tool body 1 about the axis X. In this cutting, since the rake angle of the main cutting edge portion 18 with respect to the work surface is secured by the inclination, the cutting resistance is small. In addition, since the cutting edge ridge line has a convex curve in both bottom view and side view , compared to the case of a straight line
As a result, the edge angle increases, and the entire length of the blade that performs the cutting action increases, so that the edge strength is ensured.

Further, as shown in FIG. 4, a small cutting edge 22 is formed at a position on the inner diameter side of the main cutting edge 18 slightly outside the center, as shown in FIG. Chipping of the main cutting edge 18 near the small center is prevented.

It is desirable that α is set in the range of 45 ° <α <90 °. That is, when the angle is 45 ° or less, the range in which the rake angle is negative is longer than the positive portion in the curve formed by the cutting edge when the main cutting edge 18 is viewed from the bottom or side view, and the cutting resistance increases. , 90 ° or more, the ridge line of the main cutting edge is in a range of not more than a quadrant, and spherical machining cannot be performed.

It is preferable that β is set in a range of 15 ° <β <90 °. That is, when the angle is 90 ° or more, the cutting of the spherical surface cannot be performed at the central portion of the main cutting edge 18, and when the angle is 15 ° or less, the cutting edge becomes excessively sharp and easily chipped.

[0023]

As apparent from the above description, claim 1
According to the present invention, by providing the inclined surface, it is possible to secure an appropriate rake angle with respect to the cutting surface, reduce cutting resistance, and suppress chatter of the tool body. In addition, since the cutting edge of the main cutting edge has a convex curved shape in side view and bottom view, the total length of the cutting edge is larger than in the case where the cutting edge is linear, and the cutting edge angle is larger, and therefore, the cutting edge strength. Becomes larger. According to the invention of claim 2,
Since the small cutting edge is provided in the direction opposite to the main cutting edge, the load applied to the main cutting edge can be reduced in the vicinity of the rotation center where the cutting speed is extremely low, and the chipping of the blade can be prevented. According to the invention of claims 3 to 5, by setting the predetermined range to α, the range of the quadrant of the main cutting edge is made necessary and sufficient, and the range in which the positive rake angle is secured. As large as possible to reduce the cutting resistance. Further, by setting the value to β in a predetermined range, it is possible to secure the cutting ability at the central portion and prevent chipping.

[Brief description of the drawings]

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

FIG. 2 is a side view of the tool of FIG. 1;

FIG. 3 is a bottom view of the tool of FIG. 1;

FIG. 4 is an enlarged plan view of a tip of the tool in FIG. 1;

FIG. 5 is an enlarged view showing details of a portion shown in FIG. 3;

FIG. 6 is an enlarged view showing details of a portion shown in FIG. 2;

FIG. 7 is a plan view of the throw-away tip.

FIG. 8 is a view taken in the direction of arrows along the line A-A ′ in FIG. 7;

FIG. 9 is a view taken along the line B-B ′ in FIG. 7;

FIG. 10 is an arrow view along the line C-C ′ in FIG. 7;

FIG. 11 is a plan view showing a conventional example of a ball end mill.

FIG. 12 is a side view of the ball end mill of FIG. 11;

FIG. 13 is a bottom view of the ball end mill of FIG. 11;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tool main body 10 Indexable insert (tip tip) 16 Inclined surface 18 Main cutting edge 2
0 linear part 22 small cutting blade 30 locking wall 3
2 Lock wall

Claims (5)

(57) [Scope of request for utility model registration] 1. A throw having a substantially elliptical shape in plan view and having a main cutting edge having ridges each forming a part of an arc in plan view at two points symmetrical with each other in a part thereof. In a ball end mill, a detachable tip is detachably attached to a ball-shaped portion at a tip end of a tool main body such that a rotation locus of the main cutting edge coincides with a spherical surface around the axis of the tool main body. A straight line passing through the center of the throw-away tip in plan view as a valley line, and an inclined surface whose thickness gradually increases toward both ends is provided, and the inclined surface is The main cutting edge is attached to the tool body in a direction in which the line intersects with the axis of the tool body at an angle α of less than 90 ° C., so that the main cutting edge is from either the side surface or the bottom surface side of the tool body. It is convex in the rotation direction front side of the tool body
A ball end mill characterized by forming a convex curve . 2. A small cutting blade extending from the center of the tool main body in a direction opposite to the main cutting blade is provided continuously to an end of the tool arc main body in the quadrant arc-shaped portion. The ridge line of the cutting edge is 90 ° with respect to the axis of the tool body in plan view.
2. The ball end mill of claim 1, wherein the ball end mill is oriented in an intersecting direction at an angle .beta. 3. The ball end mill according to claim 1, wherein 45 ° <α <90 °. 4. The ball end mill according to claim 2, wherein 15 ° <β <90 °. 5. The ball end mill according to claim 4, wherein 45 ° <α <90 °.