JPH09192916A - Throw-away type radius mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radius mill which can perform a high speed process through a roughing process using resin dies made of plastic or the like, die-cast dies made of aluminum, in a short delivery period, that is, with a high degree of efficiency, by making use advantages of circular die tips. SOLUTION: A radius mill is removably attached thereto with a plurality of circular die tips so as to have maximum diameter of 25 to 125mm, the tips having an outer diameter A of 10 to 18mm, and the height difference at the front surface between a circular tip at the axially front end, and the front surface end part of the tip end part of a tool body, being set to g=(1/5-1/2.5) A, and the height difference (h) at the outer periphery between the outermost part of the circular die tip in a radial direction and the tip end of the tool body being set to h=(1/10-1/4) A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away (exchangeable cutting edge) type end mill, and more particularly to a general-purpose throw-away type radius mill using round inserts.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 1, a throw-away type end mill using a round insert has a round insert 4 which can be attached to and detached from a tip portion 2 of a tool body 1 having a straight shank 3 with a set screw 5. Installed on. Also, there is a type in which a clamp piece 6 is used instead of the screw 5 (FIG. 2), and a type having a larger blade diameter is attached to an arbor which is a holding tool through a mounting hole. These radius mills use a milling machine or a machining center to perform lateral feed processing in the direction orthogonal to the tool center line as shown in Fig. 3 for shoulder milling or grooving with a corner R, or for excellent cutting edge strength of round inserts. Although it is related to the depth, it has been used for machining difficult-to-cut materials by taking advantage of the fact that it has a large corner angle.

[0003]

[Problems to be Solved by the Invention] Rough cutting of resin molds such as plastics and die-casting molds mainly made of aluminum is aimed at shortening the delivery time, that is, improving the efficiency by taking advantage of the above-mentioned round piece chips. Although there is a request to process by feeding,
In the conventional type, there is no problem in the first step, that is, in the planar processing, but it cannot be applied to the die processing having a three-dimensional shape for the following reasons. (1) In the case of grooving after plunging as in the case of grooving with a dead end as shown in FIG. 4 or slant cutting in which cutting is performed at an oblique angle, the front step g between the tip 4 and the front end of the tip 2 Is small, the cutting depth d per cut cannot be made large, resulting in poor efficiency. (2) When the process of FIG. 4 is engraved in the axial direction and repeatedly engraved, chips are caught between the outer peripheral portion 7 and the inner end portion 8 of the work material, or the cutting amount d per cut is reduced. If it is large, the outer peripheral portion 7 abuts on the inner end portion 8 and the cutting is hindered.
This is because the outer peripheral step h between the outer peripheral portion 7 of the tip portion 2 and the round piece 4 is small.

[0004]

In order to achieve the above object, the present invention has the following constitutional requirements. That is, in a throw-away type radius mill having an outermost diameter dimension of φ25 to 125 to which a plurality of round piece tips are detachably attached, the outer diameter A of the tip is φ10 to φ18 mm, and a round piece tip at the axial end is used. The frontal step difference g between the front end of the tool body and the front end is g = (1/5 to 1/2.
5) A, the outer peripheral step h between the outermost portion of the circular piece in the radial direction and the outer peripheral portion of the tip of the tool body is h = (1/10 to 1/4) A. Further, in order to further improve the performance, a configuration is added in which the clearance angle of the round piece chip is escaped in two steps, a double clamp mechanism by a set screw and a clamp piece, and a breaker groove is provided along the cutting edge.

[0005]

In the present invention, the outer diameter of the throw away radius mill and the outer diameter A of the insert to be used are determined by the change in the rigidity and strength of the holder depending on the outer diameter of the radius mill and the chip contact length depending on the outer diameter A of the insert. Since it is related to the change in cutting resistance, it will be described below in relation to the diameter.

When the outer diameter of the throw away radius mill is 63 mm and three blades are used, the depth of one cut is d = 5 mm.
When engraved with, the chip outer diameter A is φ14 to φ18
The rank is good. At φ10, there is a hole, so the chip lacks strength and is chipped. With φ20, the cutting edge length becomes too long, so 2
The cutting resistance is large even when turning once, causing chattering, which is impossible. Further, the reason for setting g = (1/5 to 1 / 2.5A) is that if g = 1 / 5A or less, the cutting depth d cannot be large and there is no merit, and if g is larger than 1 / 2.5A. Chip retention becomes unstable. Preferably 1/4 to 1/3
A grade is good. If h is smaller than 1/10 A, chips are likely to be caught, and if h is larger than 1/4 A, chip holding becomes unstable. Therefore, h = (1/1
It was set to 0 to 1/4) A.

When the outer diameter of the throw away radius mill is 35 mm and the tool rigidity is low like a double-edged blade, the outer diameter A of the tip is φ10 to φ14 when the hole is machined with a single cutting depth d = 3 mm. Is good. At φ8, it may be missing due to lack of strength, probably because it has holes. With φ18, the cutting edge length becomes too long, so even if it is cut twice, the cutting resistance is large and chattering occurs, which is impossible. Tip outer diameter A is φ10 to φ1
4 is good.

Next, the clearance angle of the throw-away tip is set to 2
By adopting the step clearance, the radius mill using the round piece insert has a large feed for the purpose of high efficiency processing, and by adding the second clearance angle θ2 to the original first clearance angle θ1 to make the two-step clearance, Negativeness on the bottom surface side of the tip can be secured without reducing the strength of the cutting edge. In addition, the round piece insert has a double clamp mechanism with a set screw and a clamp piece to increase the tip clamping force and enable stable cutting even at higher feed rates. Since the round piece chip has no wall that receives the rotation of the chip as compared with a normal square or triangular chip, it is necessary to fix the chip more firmly than these chips. Further, as described above, since the high feed is used, the stability of the chip holding is still important. Further, the round piece has a long cutting edge length and a large cutting resistance even at the same cutting depth. Therefore, it is advantageous to use a chip with a breaker groove for further engraving the rake and improving the sharpness in the engraving process in which the contact length of the cutting edge becomes large. Hereinafter, the present invention will be described in detail based on embodiments.

[0009]

EXAMPLE FIGS. 6 and 7 show an example of a throwaway radius mill of the present invention having an outer diameter of 63 mm and three blades.
According to FIG. 6, a round piece tip 4 is removably attached to a tip portion 2 of a tool body 1 having a straight shank 3 with a clamp piece 6 via a set screw 5 and a clamp bolt. When the tip is set, radial rake Ar = -5 °, axial rake Rr = + on the tool body
9 °, straight shank diameter = 32, g = 5.5 mm,
h = 2.5 mm. Assuming the engraving process, the process of FIGS. 4 and 5 is performed with the chip outer diameter A dimension of 12, 14, 16,
5 types of 18 and 20 (chip thickness 4.76 mm, breaker rake angle α = 12 °, clearance angle θ1 = 15 °, θ2 =
20 °). S50C is used as the work material, cutting speed V = 168 m / min (rotation speed 850 min), and feed amount per blade fz = 0.3, 0.4, 0.5 mm /
Blade, d = 5 mm, but when plunging, the feed rate per revolution is 0.15 mm / re in increments of 1 mm.
v.

As a result, when the tip outer diameter A is φ12, 1
It was chipped with fz = 0.4 mm / blade in the second planing. It is thought that this was due to the fact that the step difference g on the front side was as large as 5 (1 / 2.2 · A) and that the chip itself had a hole and was insufficient in strength because of the hole. Other chips have no problem with fz = 0.4 and 0.5. Next, engrave further 5 mm (see Fig. 5)
The test was performed for chips other than the outer diameter Aφ12. φ20 chip fz = 0.3mm / blade and the test was severely discontinued. The φ18 chip was chattering, but fz = 0.5m
m / blade was able to be cut without chipping. φ1
4, φ16 was stable cutting.

Further, a third groove was carved by carving 5 mm. As a result, the chip outer diameter A is φ14, φ16, φ1
8 was in the same cutting state as the second machining, and the chips were discharged from the chip pocket without being caught between the outer peripheral portion 22 of the tool tip and the work material.
Also, when the inclined machining, which is a necessary condition for the direct die cutting of the mold, is continuously performed, the cutting load changes cyclically and the forward and reverse rotation loads are continuously applied to the center of the circular piece. Therefore, with the central set screw alone, the set screw becomes loose during cutting. However, it has been found that this can be solved by using it together with a clamp piece, and by mounting a chip with breaker grooves, the feed limit can be 1.3 times that of a chip without a breaker groove with the same size cutter. It has become possible. Similarly, a radius mill of φ35 was tested with the tip outer diameter A of φ8, 10, 12, 14, and 16, but with fz = 0.2 mm / feed of the blade, φ1
0-14 was good. At φ8, lack of strength resulted in loss, φ
No. 16 is too much chatter.

Further, since the deep engraving is performed, the tool protrusion amount is 2.5D.
If the cutting is set to, the cutting area is greatly reduced and cutting vibration is likely to occur even if the cutting speed is reduced by 30%. Under such conditions, it is necessary to have a clearance amount (see FIG. 4) that does not allow the parts other than the cutting edge to come into contact with the workpiece due to cutting strength and cutting vibration. Was greatly improved.

[0013]

EFFECTS OF THE INVENTION By applying the throw away type radius mill of the present invention, the present invention can be applied to three-dimensionally used die machining including groove digging, and particularly to the inclined machining of the direct die machining. Can be used in various ways.

[Brief description of the drawings]

FIG. 1 is a front view of a throw-away type end mill using a conventional round piece insert.

FIG. 2 shows a front view of another example using a conventional round piece chip.

FIG. 3 is a cross-sectional view for explaining transverse feed machining in a direction orthogonal to a tool center line.

FIG. 4 is a top view for explaining blind groove processing.

5 is a sectional view taken along line VV of FIG.

FIG. 6 shows a front view of a throw-away radius mill of the present invention.

FIG. 7 shows a bottom view of FIG.

[Explanation of symbols]

 1 Tool body 2 Tip part 3 Straight shank 4 Round piece tip 5 Set screw 6 Clamp piece 7 Outer peripheral part of tip 8 Inner end part of tip g Front step d Cut amount h Outer step A A Tip outer diameter

Claims (4)

[Claims] 1. A throw-away type radius mill having a plurality of round pieces removably attached and having an outermost diameter of φ25 to 125, wherein the outer diameter of the tips is φ10 to φ18 m.
m, and the frontal step g between the round tip at the axial tip and the front end of the tool body tip is g = (1/5 to 1 /
2.5) A, the outer peripheral step h between the outermost part of the circular piece in the radial direction and the outer peripheral portion of the tip of the tool body is h = (1/10 to 1/4)
Throw-away type radius mill characterized by being A. 2. The throw-away radius mill according to claim 1, wherein the round piece tips have a clearance angle of two steps. 3. The throw-away radius mill according to any one of claims 1 and 2, wherein the insert is a double clamp mechanism including a set screw and a clamp piece. 4. The throw-away radius mill according to claim 1, wherein a breaker groove is provided along the cutting edge of the tip.