JP2535333B2 - Milling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention, like a ball end mill, a radius end mill, etc., has a plurality of cutting edges that draw a convex curve from the outer periphery of the tool body toward the tip. The present invention relates to a rolling tool formed with.

[Prior Art] FIGS. 5 (A), (B) and FIG. 6 show a conventional ball end mill (hereinafter, referred to as a type of such a cutting tool).
Abbreviated as end mill. ), And reference numeral 1 in the figure indicates the end mill body of this end mill.

This end mill main body (tool main body) 1 has a substantially cylindrical appearance, and its tip portion is formed in a substantially hemispherical shape.

On the outer peripheral portion of the end mill body 1, four outer peripheral cutting blades 2 ... Which draw a spiral along the axial direction are formed at equal intervals in the circumferential direction. Further, bottom blades 3 ... Are formed at the tip of the end mill body 1. And, in the hemispherical portion of the end portion of the end mill body 1, arc-shaped cutting blades 4 are formed by connecting the outer peripheral cutting blades 2 and the bottom blades 3 to draw an approximately 1/4 circle. ing.

Then, the above-mentioned conventional end mill having the above-mentioned configuration is fed around the axial line or in the direction orthogonal to the axial line while being rotated around the axial line, so that the outer peripheral cutting edge 2, the bottom blade 3, ... And the cutting edge 4 ... Thus, the surface of a metal mold or the like having a groove or hole with a rounded corner or a curved surface is processed.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional end mill, since the cutting edges 4 ... Are arc-shaped, the length of the cutting edges involved in cutting is long, and the peripheral speed of these cutting edges 4 ... Since it is smaller than the outer peripheral portion, the cutting resistance of these arcuate cutting blades 4 becomes extremely large. Therefore, in the above-mentioned conventional end mill, there is a problem that the end mill body 1 itself bends due to a large cutting resistance particularly at the tip end portion of the end mill body 1, and as a result, chattering and vibration are likely to occur.

[Object of the Invention] The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a rolling tool capable of effectively preventing chattering and vibration from occurring in the tool body by reducing cutting resistance. It is intended.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a tool main body with a plurality of cuts so that the rotation trajectory draws a convex curve from the outer peripheral portion toward the tip portion. In a cutting tool in which a blade is formed, each of the plurality of cutting edges has a cutting edge portion whose rotational locus is located on the axial line side of the convex curve,
Further, the plurality of cutting blades are formed so that the remaining portions of the respective cutting blades excluding the cutting blade portion overlap each other in the rotation locus so as to draw the convex curve as a whole.

[Operation] In the rolling tool having the above-described structure, the plurality of cutting edges draw a convex curve as a whole, and the surface of a mold or the like whose corner portion has a rounded groove or hole or a curved surface as in the past. While enabling the machining of the cutting edge, a cutting edge portion whose rotational locus is located on the axis side of the convex curve is formed on each of these multiple cutting edges, and is involved in cutting at the tip of the rolling tool. By shortening the length of the cutting edge to be cut, the cutting resistance acting on the tip portion of the tool body is reduced, thereby preventing chatter and vibration caused by the cutting edge.

[Embodiment] FIGS. 1 (A), (B) and FIG. 2 show an end mill which is one embodiment of the rolling tool of the present invention.
Portions common to those shown in FIGS. 6A and 6B and FIG. 6 are assigned the same reference numerals and explanations thereof are omitted.

In FIGS. 1 (A), (B) and FIG. 2, in this end mill, an arc-shaped strip that draws an approximately 1/4 circle by connecting the outer peripheral cutting edge 2 ... and the bottom edge 3 ... Cutting edge 10 ~ 1
3 is formed.

Of the cutting blades 10 to 13, a pair of cutting blades 10 and 12 sandwiching the axis between them are provided with approximately 1/2 of the tip side of the end mill body 1.
That is, by cutting the approximately 1/8 circumference in a straight line, linear cutting edge portions 14 and 15 whose rotation loci are located on the axial side of the other cutting edges 11 and 13 are formed. In addition, the end mill body 1 is attached to the other pair of cutting blades 11 and 13 that sandwich the axis therebetween.
About 1/2 of the base end side of the cutting edge is linearly shaved to form linear cutting edge portions 16 and 17 whose rotation loci are located on the axial side of the cutting edges 10 and 12.

Here, the linear cutting edge parts 14 to 17 of these cutting edges 10 to 13
The length of the arc-shaped parts excluding these cutting edge parts 14 to 17 overlaps each other by about 1 to 3 mm in the rotation locus, in other words, the arc-shaped parts as a whole are approximately 1/4 circle. It is supposed to be a length. Further, rounded chamfers 18 ... Are applied to both ends of these linear cutting edge portions 14 to 17.

In the end mill having the above configuration, the cutting edge 10 to 13
The work material positioned at is cut mainly by the cutting edges 11 and 13 on the tip side of the end mill body 1 and by the cutting edges 10 and 12 on the base side. In this case, the third
As shown in the figure, since the thickness T _{1 of the} chips scraped off by the cutting blades 10 to 13 is originally smaller than the thickness T _{2 of the} chips scraped off by the outer peripheral cutting blades 2, ... It is not necessary to take measures such as intentionally increasing the strength of these cutting edges 10 to 13 even if the cutting edge becomes half.

Therefore, according to such an end mill, the cutting edge 10
As a result of forming the cutting edge portions 14 to 17 whose rotation loci are located on the axis side in -13, the cutting edge 10 involved in cutting at the tip portion thereof.
The length of ~ 13 is almost half of the conventional one. This allows
Since the cutting resistance acting on the tip of the end mill body 1 can be reduced, it is possible to prevent chattering and vibration caused by the cutting edges 10 to 13 during cutting,
Therefore, excellent cutting performance and finished surface roughness can be obtained.

On the other hand, the linear cutting edge portions 14 to 17 of the cutting edges 10 to 13
In the remaining part except for, the cutting edges 10 and 12 and the cutting edges 11 and 13 overlap each other in the rotation trajectory, and as a whole, a circular arc of about 1/4 circle is drawn, so that the corner is as usual. It is possible to process the surface of a groove or hole having a rounded portion or a metal mold having a curved surface without any support.

Moreover, since the rounded chamfers 18 to 17 are provided at both ends of the linear cutting edge portions 14 to 17, it is possible to prevent the work material from being scratched by the discontinuous portion. As a result, The finished surface roughness can be further improved.

[Other Embodiments] FIG. 4 shows another embodiment of the rolling tool of the present invention, which is a development view showing the shapes of the cutting edges 30 to 23 connecting the outer peripheral cutting edge and the bottom edge 3 ... is there.

In FIG. 4, in the end mill of this example, approximately 3/4 of the cutting edge 20 on the bottom blade 3 side is a linear cutting edge portion 24. Further, the cutting blade 21 is formed with linear cutting blade portions 25 and 26 at 1/2 on the bottom blade 3 side and 1/4 on the outer peripheral side, respectively. Further, the cutting edge 22 has linear cutting edge portions 27 and 28 formed at 1/4 on the bottom blade 3 side and 1/2 on the outer peripheral cutting edge side, respectively. And the cutting edge 23, the outer peripheral cutting edge side
3/4 is a straight cutting edge portion 29.

Here, the cutting edge excluding these linear cutting edge portions 24 to 29
20 to 23 are formed so as to overlap each other in the rotation locus, that is, to draw an arc of about 1/4 circle as a whole. Also in the end mill of this example, chamfered chamfers 30 are formed between both ends of the linear cutting edge portions 24 to 29 and the outer peripheral cutting edge or the bottom edge 3 or the cutting edges 20 to 23, respectively.
Is given.

In the end mill of this example having the above configuration,
A portion of the work material extending from the outer peripheral cutting edge to the bottom blade 3 has a cutting edge length 20, 21 which has a cutting edge length of about 1/16 circumference in order from the outer peripheral cutting edge to the bottom blade 3 side. It is cut by 22 and 23.

Therefore, in the end mill of this example, the cutting edge 20
Since it is possible to further reduce the cutting resistance in Nos. 23 to 23, it is possible to obtain a more remarkable function and effect than those shown in FIGS. 1 (A), (B) and FIG.

In addition, in the end mill of the above-mentioned embodiment, all of the four cutting edges 10 to 13 and 20 to 23 are formed, but the present invention is not limited to this, and any cutting edge may be used.

Further, the cutting blades 10 to 13 and 20 to 23 are all arc-shaped cutting blades, but the cutting blades are not limited to this and can be similarly applied to cutting blades that draw various convex curves such as ellipses. . Further, the cutting edges 10 to 13 and 20 to 23 have a linear cutting edge portion 14 to 1 as a cutting edge portion whose rotation locus is located on the axis side.
Although 7, 24 to 29 are formed, they do not necessarily have to be linear, and the essential point is that each rotation locus is located on the axis side from the rotation locus of the cutting edge involved in cutting.

[Effects of the Invention] As described above, the rolling tool of the present invention has a plurality of cutting blades formed so that the rotation trajectory draws a convex curve from the outer peripheral portion of the tool body toward the tip thereof. Forming a cutting edge part where the rotation trajectory is located on the axis side of the convex curve,
And since these remaining cutting edges of the plurality of cutting edges overlap with each other in the rotation locus of the respective cutting edges except for the cutting edge portions, they are formed so as to draw the convex curve as a whole, The cutting resistance acting on the tip of the tool can be reduced while allowing the machining of the surface of grooves, holes, etc. with rounded parts, or molds with curved surfaces, etc. Since it is possible to prevent chattering and vibration due to, it is possible to obtain excellent cutting performance and finished surface roughness.

[Brief description of drawings]

FIGS. 1 (A), (B) and FIG. 2 show an embodiment of the rolling tool of the present invention. FIG. 1 (A) is a side view and FIG. 1 (B) is the same as FIG. ) Of FIG. 2), FIG. 2 is a development view of the cutting edge of the end mill shown in FIG. 1, FIG. 3 is a view showing the thickness of chips in a rolling tool of this kind, and FIG. Development view of a cutting edge showing another embodiment of the invention, FIG.
(B) and FIG. 6 show a conventional rolling tool, FIG. 5 (A) is a side view, and FIG. 5 (B) is V-V of FIG.
FIG. 6 is a development view of a blade portion in this conventional rolling tool. 1 ... End mill body (tool body), 10-13, 20-23 ...
… Cutting edge, 14-17,24-29 …… Linear cutting edge, 18,30…
… A round chamfer.

Claims (1)

(57) [Claims] 1. A cutting tool comprising a tool body having a plurality of cutting edges formed so that a rotation locus draws a convex curve from an outer peripheral portion of the tool body toward a tip portion thereof. In each of them, the rotation locus forms a cutting edge portion located on the axial side of the convex curve, and these plural cutting edges have the remaining portion excluding the cutting edge portion of each cutting edge in the rotation locus. A rolling tool characterized by being formed so as to draw the above-mentioned convex curve as a whole so as to overlap each other.