JP2002283119A - Throwaway tip for ball end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently reduce cutting resistance even when the depth of cut is large by using a throwaway tip having a chip breaker in a cutting blade in the case of double-cutting to which large cutting resistance is applied, and to prevent the throwaway tip and an end mill body for mounting it from being broken in cutting. SOLUTION: A cutting blade 5 is formed on the ridge line of a cutting face 2 and a flank 4 of the tip, and the cutting blade 5 is provided with the chip breaker 8. The thickness h of the tip along the cutting blade 5 is substantially constant. The chip breaker 8 is extended from the cutting blade 5 toward a bearing surface 3 up to the midway of the flank 4, and has an inclination to the direction of the thickness of the tip. The chip breaker is set to a length 1/2 to 3/4 times as large as the tip thickness h of the chip breaker 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away insert for a ball end mill having an arc-shaped cutting blade, which is detachably attached to the end of an end mill main body.

[0002]

2. Description of the Related Art As a ball end mill 30 using a throw-away tip, for example, as shown in FIG. 6 to FIG. 8, a pair of grooves 32, 32 are formed so as to be cut out in an L-shape as viewed from the front end side in the axial direction, and the wall surfaces 33, 33 facing the end mill rotation direction side of these grooves 32, 32 are formed. Each of the throw-away tips 3
There is known a configuration in which 5, 36 are detachably mounted by clamp screws 37 (see FIG. 6).

Here, these throw-away chips 3
Each of the cutting edges 5 and 36 has a substantially arcuate cutting edge 38 and this cutting edge 3.
And a pair of straight cutting edges 39, 39 extending continuously from the cutting edges 8, 38, and one of the flank surfaces 4 connected to the cutting edges.
0 and abutting against the wall surface 33 of the tip mounting seat 34 so that the substantially arc-shaped cutting blade 38 on the other side extends from the rotation center side of the front end of the end mill body 31 toward the rear end outer peripheral side. In addition to this, a straight cutting blade 3
9 is arranged so as to extend toward the rear end side of the end mill main body 31.

In the ball end mill 30 described above, the entire cutting edge located outside during the cutting operation hits the work material, so that a large impact is applied. There are problems such as a decrease in accuracy and processing efficiency, and a problem that the width of chips is widened and it is difficult to discharge chips.

In order to avoid such a problem, FIG.
And as shown in FIG.
It is conceivable to form a nick 42 for cutting chips from the cutting edge 44 of the throw-away tip 35 toward the lower surface as the seating surface 41 on the flank 40 of the workpiece. Since cutting is not performed, the cutting resistance can be reduced, and the effect that the width of the chips is divided into small pieces to facilitate discharge can be expected.

As such a conventional throw-away tip 35 for a ball end mill, the nick 4 shown in FIG.
2 was connected to the seating surface 41, and the nick 42 shown in FIG.

In the indexable insert 35 shown in FIGS. 9 and 10, the corner of the cutting edge 44 is made closer to the axis 50 of the ball end mill 30. It was formed to have a small thickness.

[0008]

However, the throw-away tip 35 for a ball end mill shown in FIG. 9 has a small strength because the nick 42 is continuous to the seating surface 41 of the throw-away tip 35, so that it cannot be used for heavy cutting. could not.

On the other hand, the throw-away tip 35 for a ball end mill shown in FIG.
Since the length in the chip thickness direction is small, the clearance width 45 of the nick 42 is small as shown in FIG. Therefore, if the feed amount is increased during cutting, the edge 42a of the nick 42 and the work material interfere with each other.
Cutting was also performed in 2a. In that case, there is a problem that the effect of suppressing chatter vibration, which does not have a large resistance, is not exhibited.

Further, both the throw-away tips 35 of FIGS. 9 and 10 have a configuration in which the thickness of the tip 44 is reduced toward the distal end side, so that the strength of this portion is low. 11, the rake angle of the rake face 46 in the direction of the axis 50 of the cutting edge 44 of the indexable insert 35 in a state of being mounted on the end mill main body 31, as shown in FIG. )
To be attached to the axis 11 so as to be inclined downward and to the right in the figure. Therefore, there is a problem that the mechanical strength of this portion of the end mill main body 31 is reduced because the lower thickness of the tip mounting seat in the end mill main body 31 is small.

In view of such a problem of the prior art, the present invention particularly provides a large cutting depth by using a throw-away tip having a nick on a cutting edge when performing heavy cutting in which a large cutting force acts. It is an object of the present invention to sufficiently reduce the cutting resistance and to prevent breakage of the indexable insert and the end mill body to which the insert is attached during cutting.

[0012]

In order to solve the above-mentioned problems, a throw-away tip for a ball end mill according to the present invention comprises:
A throw-away insert for a ball end mill having a substantially elliptical planar shape having an upper surface as a rake surface, a lower surface as a seating surface, a side surface as a flank, and a cutting edge formed on the ridge of the rake surface and the flank. The tip thickness along the cutting edge is substantially constant, and a nick is formed on the flank extending halfway from the cutting edge toward the seating surface,
This nick is characterized in that it has a length of 1/2 to 3/4 of the chip thickness and has an inclination with respect to the chip thickness direction.

The chip having such a configuration is attached so as to be inclined with respect to the axis so that the rake angle in the axis direction of the chip is directed to the negative angle side. At this time, the nicks are arranged substantially perpendicular to the rotation axis of the end mill main body.

[0014] Since the tip has a substantially constant thickness along the cutting edge, the tip has high strength.

Further, since the nick is formed to extend from the cutting edge of the tip to the seating surface to the tip mounting seat to the lower side of the flank, the relief width of the nick portion is large. Therefore, even when the feed amount is increased, the edge of the nick does not easily interfere with the work material, so that the cutting resistance is stable and chattering is unlikely to occur. Here, since the nick does not penetrate to the seating surface, the strength of the nick portion against heavy cutting is sufficiently large.

Further, in the above chip, the nick is formed so as to be inclined with respect to the direction of the chip thickness, so that the nick is substantially perpendicular to the rotation axis of the end mill body,
Further, as described above, the chip can be disposed on the end mill main body such that the rake angle in the axial direction of the chip is directed to the negative angle side. Thereby, the lower thickness of the tip mounting seat in the end mill main body can be increased. Therefore, the strength of the chip against heavy cutting and the strength of the end mill body to which the chip is mounted can be sufficiently increased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A chip according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings.

FIGS. 1 and 2 show a chip according to an embodiment of the present invention. In these figures, reference numeral 1 denotes a chip, 2 denotes a rake surface, 3 denotes a seating surface, 4 denotes a flank, 5 denotes a cutting edge, 6 denotes a substantially arc-shaped cutting edge, 7 denotes a straight cutting edge, and 8 denotes a nick. It is.

The tip 1 is made of a hard material such as a cemented carbide and is formed into a flat plate having a substantially elliptical planar shape, and has a rake face 2 at the center of the upper surface as a seating face 3 for mounting to an end mill body. A mounting hole 10 penetrating the lower surface is provided. Further, a cutting edge 5 is formed on a ridge line between the rake face 2 and the side face as the flank face 4, and a nick 8 is provided at an appropriate position on the cutting edge 5 with a required interval.

The cutting edge 5 has a pair of substantially arc-shaped cutting edges 6, 6 and straight cutting edges 7, 7 extending continuously from the cutting edges 6, 6. Along the chip thickness h is substantially constant. Therefore, even at the tip portion, the thickness of the tip 1 is large and the strength of this portion against heavy cutting is sufficiently large. The cutting blades 5 are in a symmetrical positional relationship with respect to the mounting hole 10.

The nick 8 extends from the cutting edge 5 toward the seating surface 3 to a point on the flank 4 and has a predetermined inclination with respect to the chip thickness direction. As a result, as described later, when the nick 8 is attached to the end mill main body while being inclined with respect to the axis so that the rake angle in the axial direction of the chip 1 is directed to the negative angle side, the nick 8 is arranged orthogonal to the axis of the end mill main body. It can be.

Further, the nick 8 has a length of 1/2 to 3/4 of the chip thickness h. Note that these tips 1 are so-called positive tips in which a clearance angle is provided on a side surface which is connected to the cutting blade 5 and serves as a flank surface 4. In such a positive tip, since the nick 8 extends from the cutting edge 5 to the lower half region of the flank 4, the clearance width 12 of the nick 8 is large as shown in FIG.
Therefore, even when the feed amount is increased, the edge 8 of the nick 8
Since a and the work material hardly interfere with each other, the cutting resistance is stable and low, and chatter is hardly generated. Here, since the nick 8 does not penetrate to the seating surface 3, the strength of the nick 8 portion against heavy cutting is sufficiently large. If the nick 8 does not extend from the cutting edge 5 to the lower half area of the flank 4, the nick 8
Edge 8a and the work material easily interfere with each other. When the work is cut at the edge 8a of the nick 8 due to this interference, the cutting resistance increases and chatter is likely to occur. On the other hand, when the nick 8 extends from the cutting edge 5 toward the seating surface 3 in the chip thickness direction longer than ／ of the chip thickness h of the cutting edge 5 with respect to the seating surface 3, the nick 9 of the flank 4 is formed. The strength of the lower end portion is remarkably reduced, and if heavy cutting is performed, there is a possibility that a defect is likely to occur in this portion.

On the periphery of the rake face 2, a raised surface 13 that gradually rises toward the inside of the chip away from the cutting edge 5 so as to orbit around the edge of the rake face 2 along the cutting edge 5. Is formed.

FIGS. 3 to 5 show a ball end mill 14 in which the chip 1 is mounted on the end mill body 9.

The end mill body 9 has a columnar shape, and the tip 15 is formed in a substantially hemispherical shape. As shown in FIG. 4, a pair of grooves 16, 16 are formed in the distal end portion 15 on opposite sides of the axis 11 so that the outer periphery of the end mill body 9 is cut out in an L shape. I have.

Chip mounting seats 19 are formed on the walls 17, 17 of the grooves 16, 16 facing the end mill rotation direction (the direction of the arrow in FIG. 4). 1 and similar chips 20 having a different planar shape and size from this chip 1 are clamped by screws 18 respectively.
It is attached detachably.

As shown in FIG. 5, the tip 1 and the tip 20 have a rake angle in the direction of the axis 11 of the cutting blade 5 in a state where the tip 1 is mounted on the tip mounting seat 19 (FIG. 5). It is attached to the axis 11 so as to be inclined upward to the right in the figure so as to be directed toward the middle or upper side.

As shown in FIG. 3, one of the chips 1 and 20 has a substantially arc-shaped cutting edge 6 which is positioned near the axis 11 at the end of the end mill main body 9 so as to be close to the end mill main body 9. The other chip 20 is arranged at a position slightly separated from the axis 11 while being arranged to extend toward the rear end side of the outer periphery.

As shown in FIG. 3, the nicks 8 on one chip 1 and the nicks on the other chip 20 are formed so as to be shifted from each other in the axial direction when viewed from the side.

The ball end mill 1 constructed as described above
In 4, the work material is cut by the cutting blades divided into three by the two nicks 8, 8, so that the width of the chips can be reduced, and the chips can be discharged smoothly. .

In the tips 1 and 20, the nicks 8 are formed with a slant in the direction of the tip of the substantially arc-shaped cutting blade 6, so that the nicks 8 are aligned with the axis 11 of the end mill body 9.
The chip can be mounted obliquely with respect to the axis 11 such that the rake angle of the chip in the direction of the axis 11 is directed to the negative angle side as described above. Thereby, the lower thickness of the tip mounting seat 19 in the end mill body 9 can be increased. Therefore, the strength of the chips 1 and 20 against heavy cutting and the strength of the end mill body 11 to which the chips 1 and 20 are attached can be sufficiently increased.

[0032]

As described above, the indexable insert for a ball end mill of the present invention has a substantially identical tip thickness along the cutting edge. Is big enough.

Further, since the nick is formed to extend from the cutting edge of the throw-away tip toward the seating surface to the tip mounting seat to the lower side of the flank, the relief width of the nick portion is large. Therefore, even when the feed amount is increased, the edge of the nick hardly interferes with the work material, so that the cutting resistance is stable and chattering hardly occurs. Here, since the nick does not penetrate to the seating surface, the strength of the nick portion against heavy cutting is sufficiently large.

Further, since the nick of the tip is formed so as to be inclined with respect to the direction of the tip thickness, the nick is substantially perpendicular to the rotation axis of the end mill body and the rake angle in the axial direction of the tip is a negative angle. It can be placed on the end mill body so that it is turned to the side. Thereby, the lower thickness of the tip mounting seat in the end mill main body can be increased. Therefore, the strength of the chip against heavy cutting and the strength of the end mill body to which the chip is mounted can be sufficiently increased.

[Brief description of the drawings]

FIG. 1 shows a throw-away tip for a ball end mill according to an embodiment of the present invention, wherein (a) is a top view and (b) is a side view.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a top view of a ball end mill to which the chip of FIG. 1 is mounted.

FIG. 4 is a front end view of the ball end mill of FIG. 3;

FIG. 5 is a side view showing a tip portion of the ball end mill of FIG. 3;

FIG. 6 is a top view of a conventional ball end mill.

FIG. 7 is a front end view of the ball end mill of FIG. 6;

FIG. 8 is a side view showing a tip portion of the ball end mill of FIG.

FIG. 9 shows a conventional throw-away tip for a ball end mill, wherein (a) is a top view and (b) is a side view.

FIG. 10 shows another conventional example of a throw-away tip for a ball end mill, in which (a) is a top view and (b) is a side view.

11 is a side view showing a tip end portion of a ball end mill to which the chip of FIG. 10 is mounted.

FIG. 12 is a sectional view taken along line YY of FIG. 10;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 (throwaway for ball end mill) insert 2 rake face 3 seating face 4 flank face 5 cutting edge 6 substantially arc-shaped cutting edge 7 linear cutting edge 8 nick 8a edge 9 end mill body 10 mounting hole 11 axis 12 clearance width 13 Raised surface 14 Ball end mill 15 Tip 16 Groove 17 Wall surface 18 Clamp screw 19 Tip mounting seat 20 (Throw away for ball end mill) Tip h Tip thickness

Claims (1)

[Claims] 1. A ball end mill having a substantially elliptical planar shape having an upper surface as a rake surface, a lower surface as a seating surface, a side surface as a flank, and a cutting edge formed at a ridge line of the rake surface and the flank. A throw-away tip, wherein the tip thickness along the cutting edge is substantially constant, and a nick is formed on the flank extending halfway from the cutting edge toward the seating surface. 1/2 to 3/4
A throw-away tip for a ball end mill, characterized in that the tip has a length and is inclined with respect to the direction of the tip thickness.