JPS6374512A - Rotary cutting tool - Google Patents

Abstract

PURPOSE:To reduce cutting resistance and prevent noise and vibration from being produced by making a rotary locus of at least one of multiple cutting edges to be located nearer to an axial line side than the loci of the rest of the cutting edges so that the locus draws a convex curve as a whole. CONSTITUTION:Between peripheral cutting edges 2 and a bottom edge 3 are formed arc-shaped cutting edges 10 through 13 of a shape of approximately a quarter cicumference. About half lengths of front ends of paired cutting edges 10 and 12 out of those cutting edges are cut off in straight lines to form straight line shaped cutting edges 14 and 15 with their rotary loci located nearer to an axial line side than those of the cutting edges 11 and 13. About half lengths of the other pair of cutting edges 11 and 13 are cut off in straight lines to form straight line-shaped cutting edges 16 and 17 with their rotary loci located nearer to the axial line side than the cutting edges 10 and 12. Lengths of cutting edge portions 14 through 17 are formed so that the arc-shaped parts are overlapped along the rotary loci by a length of about 1 to 3 mm. The cutting edge portions 14 through 17 are chamfered and the lengths of the cutting edges involved in cutting at the front end are approximately halved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a tool body having a plurality of cutting edges that draw a convex curve from the outer periphery toward the tip of the tool body, such as a ball end mill or a radius end mill. This is related to a milling tool that has been formed.

[Prior Art] Figures 5 (A), (B), and 6 show a conventional pole end mill (hereinafter abbreviated as an end mill), which is a type of milling tool. The reference numeral l 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 is formed into a substantially hemispherical shape.

On the outer periphery of the end mill main body I, four outer peripheral cutting edges 2 are formed at equal intervals in the circumferential direction, spiraling at rσ in the axial direction. Furthermore, a bottom blade 3 is formed at the tip of the end mill main body l. Then, in the hemispherical part of the tip of this end mill main body l, there is approximately 1/4 by connecting these peripheral cutting edges 2 and bottom edges 3...
An arcuate cutting edge 4 is formed to draw the circumference of the cutting edge.

The above-mentioned conventional end mill consisting of the above-mentioned sliding composition is
By being rotated around the axis and fed in the axial direction or in the direction perpendicular to the axis, the outer cutting edge 2.
・The bottom blade 3 . . . and the cutting blade 4 . . . are used to process holes, holes, etc. with rounded corners, or surfaces of molds, etc. with curved surfaces.

[Problems to be Solved by the Invention] However, in the conventional end mill described above, since the cutting blades 4 are arcuate, the length of the cutting blades involved in cutting is long, and furthermore, these cutting blades 4... Since the circumferential speed at the outer edge 771 is smaller than that at the outer edge 771, the cutting resistance at these arc-shaped cutting edges 4 becomes extremely large. For this reason, in the above-mentioned conventional end mill, especially the end mill body 1
Since the cutting resistance at the tip of the end mill is large, the end mill main body l itself is bent, and as a result, there is a problem in that it is likely to cause chatter and vibration.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a milling tool that can reduce cutting resistance and effectively prevent chatter and vibration from occurring in the tool body. This is the purpose.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides at least one of the plurality of cutting edges with a plurality of cutting edges that are convex as a whole in the rotation locus. The rotation locus forms a cutting edge portion that is located closer to the axis than the rotation loci of other cutting blades so as to draw a curved line.

[Function] In the milling tool with the above configuration, by shortening the length of the cutting blade that participates in cutting at the tip, the cutting resistance acting on the tip of the tool body is reduced, thereby reducing the cutting edge. The occurrence of chatter vibrations caused by this is prevented.

[Embodiment Figures 1 (A), (I3) and Figure 2 show an end mill which is an embodiment of the cutting tool of the present invention.
Portions common to those shown in FIGS. (A), (B), and FIG. 6 are given the same reference numerals, and their explanations will be omitted.

1(A), (B) and FIG. 1, in this end mill, the outer peripheral cutting edge 2... and the bottom edge 3...
- Arc-shaped cutting blades 10 to 13, which connect these and draw approximately 1/4 circumference, are formed between them.

Of these cutting blades 10 to 13, a pair of cutting blades 10.12 sandwiching the axis between them have 1/2 of the tip side path of the end mill body 1, that is, approximately 1/8 circumference cut off in a straight line. As a result, a linear cutting edge portion 14.15 is formed whose rotation locus is located closer to the axis than that of the other cutting edges 11.13. In addition, another pair of cutting blades 11, 1 sandwiching the axis between them
3, approximately 1/2 of the proximal end side of the end mill body l is shaved off in a straight line, and the linear cutting blade portion 16.17 has a rotation locus located on the axis side of the cutting blade 10.12. is formed.

Here, the linear cutting edge portion 14 of these cutting edges 10 to 13 is
The length of ~17 is determined so that the arcuate portions excluding the cutting edge portions 14~17 overlap each other by about 1~31 points in the rotation locus, in other words, the arcuate portions as a whole are approximately 1/4 of each other. It is said to have a length that traces the circumference. Furthermore, rounded chamfers 18 are provided at both ends of these linear cutting edge portions 14 to +7.

In the end mill having the above configuration, the cutting edge lO~1
The workpiece located at 3 is mainly cut by the cutting blades 11 and 13 on the distal end side of the end mill body 1, and by the cutting blade 1O112 on the proximal end side. In this case, as shown in FIG.
The thickness T of chips removed by 3 is the outer cutting edge 2...
Because it is thinner than the thickness of the chips removed by T,
Even if the number of cutting edges to be cut is reduced to half of the conventional one, there is no need to take any measures such as intentionally increasing the strength of these cutting edges 1o-t3.

Therefore, according to such an end mill, the cutting edge lO
- Cutting blade portion 14-1 whose rotation locus is located on the axis side in ~I3
7, the length of the cutting edges 10 to 13 involved in cutting at the tip thereof becomes approximately half that of the conventional lance. As a result, the cutting resistance acting on the tip of the end mill body l can be reduced, so the cutting edge l can be reduced during cutting.
O~! It is possible to prevent the chatter vibration caused by the above-mentioned No. 3 from occurring, and therefore it is possible to obtain excellent cutting performance and finished surface roughness.

In addition, since rounded chamfers 18 are applied to both ends of the linear cutting edge portions 14 to 17, it is possible to prevent the work material from being scratched due to these discontinuous points. As a result, the finished surface roughness can be further improved.

[Other Embodiments] FIG. 4 shows another embodiment of the milling tool of the present invention, and is a developed view showing the shapes of cutting edges 20 to 23 connecting the outer peripheral cutting edge and the bottom edge 3. It is.

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

Here, the cutting blades 20 to 23 excluding these linear cutting blade portions 24 to 29 are formed so as to overlap each other in the rotation locus, that is, to draw an arc of approximately 1/4 circumference as a whole. There is. Also, in the end mill of this example, rounded chamfers 30 are formed between both ends of the linear cutting blade portions 24 to 29 and the outer peripheral cutting edge, the bottom blade 3, or the cutting blades 20 to 23. ... has been applied.

In the end mill of this example having the above configuration, the portion of the workpiece from the outer cutting edge to the bottom edge 3... It is cut by cutting edges 20.21.22.23 having a cutting edge length of I6 circumference.

Therefore, in the end mill of this example, the cutting edge is 20.
Since the cutting resistance in steps 1 to 23 can be further reduced, even more remarkable effects than those shown in FIGS. 1(A), 2(B) and 2 can be obtained.

In addition, in the end mill of the said Example, all four cutting edges 10-13.20-23 are formed, but it is not limited to this, and it is sufficient if it has a plurality of cutting edges.

In addition, although the above cutting edges 1O~13 and 20~23 are all arc-shaped cutting edges, they are not limited to this, and can be similarly applied to cutting edges that draw various convex curves such as ellipses. reactor. Furthermore, although these cutting edges 10 to 13, 20 to 23 are formed with linear cutting edge portions 14 to 17 and 24 to 29 as cutting edge portions whose rotation locus is located on the axis side, they are not necessarily linear. In short, it is sufficient that each rotation locus is located on the axis side from the rotation locus of the cutting blade involved in cutting.

[Effects of the Invention] As explained above, the end mill of the present invention has at least one cutting edge among the plurality of cutting blades such that a convex curve is drawn as a whole in the rotation locus of the plurality of cutting blades.
Since its rotation locus forms a cutting edge portion located on the axis side than the rotation locus of other cutting blades, the cutting resistance acting on the tip can be reduced, and therefore, when cutting, the bipedal cutting edge Since the occurrence of chattering vibration caused by this can be prevented, excellent cutting performance and finished surface roughness can be obtained.

[Brief explanation of the drawing]

Figures 1 (A), (B) and Figure 2 show an embodiment of a milling tool of the present invention, with Figure 1 (A) being a side view and Figure 1 (B) being a side view (A). ), Figure 2 is a developed view of the cutting edge of the end mill shown in Figure 1, Figure 3 is a diagram showing the thickness of chips in this type of milling tool, and Figure 4 is this Developed views of cutting blades showing other embodiments of the invention, FIGS. 5(A) and 5(B)
) and Fig. 6 show a conventional milling tool, Fig. 5 (A) is a side view, Fig. 5 (B) is a view taken along the line ■-■ of Fig. 5 (A), and Fig. 6 is this It is a developed view of the blade part of a conventional milling tool. l...End mill body (tool body), lO~1
3.20~23... Cutting edge, 14~17.24~
29... Linear cutting edge part, 18.30 ・
・R-shaped chamfer.

Claims (1)

[Claims] In a milling tool in which a plurality of cutting blades forming a convex curve from the outer periphery toward the tip are formed on the tool body, at least one of the plurality of cutting blades has a plurality of cutting blades formed on the tool body. A milling tool characterized in that the cutting edge of the strip forms a cutting edge portion whose rotation locus is located closer to the axis than the rotation locus of other cutting blades so that the entire rotation locus of the cutting edge draws the above-mentioned convex curve.