JP3161353B2 - Indexable 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 in which a pair of throw-away tips having, for example, arc-shaped cutting edges are detachably mounted at the tip of an end mill body.

[0002]

2. Description of the Related Art As this type of ball end mill, for example, as shown in FIGS. 6 to 8, the end of a substantially cylindrical end mill body 1 rotating around an axis O is opposed to each other with the axis O interposed therebetween. 8 when viewed from the front end side in the direction of the axis O.
As shown in FIG. 8, a pair of grooves 2, 2 are formed so as to be cut out in an L-shape, and are formed on the wall surfaces of the grooves 2, 2 facing the end mill rotation direction (the direction of the white arrow in FIG. 8). There is known a configuration in which chips 4 and 5 are detachably mounted on chip mounting seats 3 and 3 by clamp screws 6 respectively.

[0003] Each of the chips 4 and 5 has a pair of a substantially arcuate cutting edge 7 and a straight cutting edge 8 extending in a tangential direction of the cutting edge 7, and one of the cutting edges 7 is provided. Blade 7,
The end surface of the end mill body 1 extends from the rotation center C side of the end mill body 1 toward the rear end outer peripheral side while the side surface connected to the end surface 8 is in contact with the wall surface 3A of the tip mounting seat 3 for mounting. The other straight cutting blade 8 is arranged so as to extend toward the rear end of the end mill main body 1.

[0004]

However, in the above-mentioned ball end mill, since the entire outer cutting blades 7, 8 hit the work material during cutting, the impact is large and a large cutting resistance acts. In addition, there is a problem that chatter vibration is generated and the machining accuracy and machining efficiency are reduced, and a problem that the width of the chips is widened and it is difficult to discharge the chips.

In order to avoid such a problem, FIG.
It is conceivable that a nick 9 is formed on the cutting blades 7 and 8 as shown in FIG. 4. In this case, the nick 9 does not cut the work material, thereby reducing the cutting resistance and reducing the width of the chips. The effect of dividing and facilitating discharge can be expected.

[0006] However, since the work material is not cut in the nick 9, uncut portions are left behind.
The recesses of the nick 9 interfere with the exposed portions 3B of the tip mounting seats 3 and 3 exposed in the rotation direction of the end mill main body 1, causing chatter vibration, and the exposed portions 3B hinder the discharge of chips. Occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables a smooth throwing out of chips, an effective suppression of chattering vibration, and an effective throwing speed for improving machining accuracy and machining efficiency. An object of the present invention is to provide an away type ball end mill.

[0008]

In order to solve the above-mentioned problems and to achieve the object, a throw-away type ball end mill of the present invention mounts a throw-away tip on a tip mounting seat at an end of an end mill main body which rotates around an axis. In the throw-away type ball end mill, a nick for chip separation extending from a cutting edge of the throw-away tip toward a seating surface to the tip mounting seat is formed on a flank of the throw-away tip, A groove communicating with the nick is provided on the outer peripheral surface of the end of the end mill main body.

With this configuration, the cutting resistance can be reduced, and the interference between the uncut portion left by the nick and the chip mounting seat exposed in the rotation direction of the end mill body from the dent of the nick can be eliminated. Generation of chatter vibration can be effectively suppressed.

[0010] Further, since the cutting blade is configured to be intermittent through the nick, the width of the chip can be divided into small pieces so that the chip can be discharged smoothly.

In the case where the nick is formed so as to widen toward the seating surface, the cutting may be performed while the ball end mill moves in a direction inclined with respect to its axis. Since there is no interference between the chip mounting seat exposed from the nick recess in the rotation direction of the end mill main body and the uncut portion left by the nick, chatter vibration can be suppressed.

Further, when a key is formed on one of the tip mounting seat of the end mill main body and the seating surface of the throw-away tip, and a key groove is formed on the other, positioning when the chip is mounted on the end mill main body is performed. In addition to being easy, mounting rigidity and the like can be increased.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. 1 is a plan view of a throw-away type ball end mill, showing an example of an embodiment of the present invention, FIG. 2 is an enlarged view of a main part of the end mill, FIG. 3 is a side view of the end mill, and FIG. In these figures, reference numeral 31 denotes a nick, and 32 denotes a groove.

In this embodiment, the end mill body 1
As shown in FIG. 1, 1 has a cylindrical shape whose diameter decreases as it goes toward the distal end, and its distal end is formed in a substantially hemispherical shape. As shown in FIG. 3 and FIG. 4, a pair of grooves 12, 1 are formed in the front end portion so that the outer periphery of the end mill main body 11 is cut out in an L-shape on opposite sides of the axis O.
2 are formed.

Chip mounting seats 13 are formed on the walls of the grooves 12 facing the end mill rotation direction (the direction of the arrow in FIG. 4).
Chips 14 and 15 are removably attached to 3 and 13 by clamp screws 16 and 16, respectively.

The chips 14 and 15 are formed of a hard material such as a cemented carbide in the shape of a flat plate, and a cutting edge 18 having a substantially 1/4 arc shape is formed on a ridge of an upper surface 17 serving as a rake face.
And a pair of linear cutting blades 19 that smoothly contact the arcuate cutting blades 18 are formed symmetrically with respect to a screw hole 20 through which the clamp screw 16 is inserted.

The tips 14 and 15 are so-called positive tips in which a side surface 21 which is a flank connected to the cutting blades 18 and 19 is provided with a clearance angle. The protruding surface 22 that gradually protrudes toward the inside of the chip away from the cutting blades 18 and 19,
It is formed so as to go around the periphery of the upper surface 17 along the cutting blades 18 and 19.

A pair of parallel key grooves 24 extending in a direction substantially perpendicular to the axis O is formed on a lower surface 23 which is a seating surface of the chips 14 and 15. Here, the key grooves 24, 24 may be formed to have an appropriate angle, for example, an acute angle with respect to the axis O as shown by a dashed line in FIG.

On the other hand, a pair of keys 25, 25 are formed on the bottom surface 13A of the chip mounting seat 13 on which the lower surface 23 is seated, and the key grooves 24, 24 are engaged with the keys 25, 25. , Chips 14 and 15 are chip mounting seats 1
Sitting at 3,13.

As shown in FIG. 3, when the chips 14 and 15 are mounted on the chip mounting seats 13 and 13, the rake angles of the cutting blades 18 and 19 in the direction of the axis O are directed to the regular angle side. As shown in FIG.

Then, among these chips 14 and 15,
One of the tips 14 is arranged so that its arcuate cutting edge 18 extends from the vicinity of the rotation center C at the end of the end mill main body 11 toward the rear end side of the outer periphery of the end mill main body 11, while The tip 15 is disposed so as to extend from the position slightly separated from the rotation center C to the outer peripheral rear end side.

On the side surfaces 21 of the chips 14 and 15, the nicks 31 for cutting chips are formed by cutting out the upper surface 17 which is a rake surface and extending from the cutting blades 18 and 19 to the lower surface 23 which is a seating surface. The grooves 24 are formed so as to overlap.

As shown in FIG. 2, the nick 31 on the tip 14 side and the nick 31 on the tip 15 side are formed so as to be shifted from each other in the direction of the axis O when viewed from the side. The groove 32 is provided in the circumferential direction so as to communicate with the nicks 31. Also,
The groove 32 has the same width as the nick 31.

In the ball end mill constructed as described above, the cutting edge 1 from the intersection A to one of the nicks 31 where the work material is divided into three by the two nicks 31.
8, the cutting edge 18 and the cutting edge 19 from the one nick 31 to the other nick, and the cutting edge 18 from the other nick 31 to the intersection A, so that the width of the chips Can be thinned, and chips are smoothly discharged.

Further, since the groove 32 communicating with the nick 31 is formed in the outer peripheral surface of the end of the end mill main body 11, the uncut portion of the nick 31 interferes with the chip mounting seats 3, 3 of the end mill main body 11 during cutting. And the occurrence of chattering vibration is effectively suppressed.

In this embodiment, the nicks 31 and the grooves 32 have been described in which the widths of the grooves are formed uniformly in the longitudinal direction. However, as shown in FIG.
The nick 33 formed so as to be widened toward the nick 33 and the communication portion with the nick 33 may have the same width, and the groove 34 may be formed so that the width gradually decreases as the distance from the communication portion increases.

In such a configuration, even when the ball end mill is cut while moving in a direction inclined with respect to its axis O, the uncut portion of the nick 33 is left uncut by the tip mounting seat 13, Therefore, it is possible to suppress occurrence of chattering vibration and prevent accumulation of chips.

[0028]

As is clear from the above description, according to the present invention, the following effects can be obtained. (A) In the throw-away type ball end mill according to the first aspect of the present invention, the cutting resistance can be reduced and the uncut portion caused by the nick and the interference with the tip mounting seat of the end mill main body can be eliminated. The generation can be effectively suppressed and the accumulation of chips can be prevented.

(B) Further, since the cutting blades are intermittently arranged via the nicks, the width of the chips can be divided into small pieces, and the chips can be discharged smoothly.

(C) In the throw-away type ball end mill according to the second aspect, even if the cutting is performed while the ball end mill moves in a direction inclined with respect to its axis, the tip of the end mill body is formed. Interference between the mounting seat and the uncut part due to the nick is eliminated, and the occurrence of chatter vibration can be suppressed.

(D) In the throw-away type ball end mill according to the third aspect, the positioning when the chip is mounted on the end mill main body can be facilitated and the mounting rigidity can be increased.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an embodiment of a throw-away type ball end mill according to the present invention.

FIG. 2 is an enlarged view of a main part of the ball end mill.

FIG. 3 is a side view of the ball end mill.

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

FIG. 5 is an enlarged view of a main part showing an example of a throw-away type ball end mill according to another embodiment of the present invention.

FIG. 6 is a plan view showing an example of a conventional throw-away type ball end mill.

FIG. 7 is a side view of the ball end mill.

FIG. 8 is a front view of the ball end mill.

FIG. 9 is an enlarged view of a main part showing an example of the ball end mill in which a nick is provided on a cutting blade.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 End mill main body 13 Tip mounting seat 14, 15 Tip (throw-away tip) 18, 19 Cutting edge 21 Side surface (flank surface) 23 Lower surface (seating surface) 24 Key groove 25 Key 31, 33 Nick 32, 34 Groove O axis

Continuation of the front page (56) References JP-A-7-299633 (JP, A) JP-A-60-29416 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23C 5 / 10 B23C 5/20 B23B 27/16

Claims (3)

(57) [Claims] 1. A throw-away type ball end mill in which a throw-away tip is mounted on a tip mounting seat at a tip end of an end mill main body that rotates around an axis, wherein a flank of the throw-away tip is formed by a cutting edge of the throw-away tip. A nick for cutting chips extending toward a seating surface on a mounting seat is formed, and a groove communicating with the nick is provided on an outer peripheral surface of a tip end of the end mill main body. Type ball end mill. 2. The throw-away ball end mill according to claim 1, wherein the nick is formed so as to widen toward the seating surface. 3. A key is formed on one of a tip mounting seat of the end mill main body and a seating surface of the indexable tip, and a key groove is formed on the other, respectively. The throw-away ball end mill as described.