JP2575983Y2 - Ball end mill and indexable insert - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball end mill provided with an arc-shaped cutting edge at the tip of a tool body, and a throw-away chip (hereinafter, referred to as a chip) for providing the cutting edge of such a ball end mill. It is about.

[0002]

2. Description of the Related Art As a ball end mill of this type, for example, a throw-away type ball end mill as shown in FIGS. 6 to 8 is known. This is Tokiko 56-2
No. 0125, two tips 2 having the same shape and the same size are provided at the tip of the tool body 1 rotated about the axis O on opposite sides of the axis O, and They are displaced from each other in the direction of the axis O and are detachably mounted by the clamp mechanism 3. Here, the chip body 4 has an upper surface 4A as shown in FIG.
It is a flat plate having a substantially equilateral triangle shape in a plan view from the side, and each edge of the upper surface 4A is larger than a radius of a circumscribed circle of the equilateral triangle formed by the upper surface 4A in the plan view. Cutting edges 5 having a convex arc shape with a large radius of curvature are formed.

As shown in FIG. 7, each of the chips 2, 2 has a tool body 1 such that the upper surface 4A is located in a plane including the axis O and faces the tool rotation direction (counterclockwise direction in FIG. 7). And the rotation trajectories of the respective cutting blades 5, 5 around the axis O overlap each other to form a hemisphere as a whole. Note that the chip 2
The side surface of the chip body 4 may be a negative chip whose side surface is perpendicular to the upper surface and the lower surface, or the side surface 4B forms an acute angle with the upper surface 4A and forms an obtuse angle with the lower surface 4C as shown in FIG. The cutting edge 5 may be a positive tip with a clearance angle.

[0004]

However, in the ball end mill having the above structure, as shown in FIG.
The chip 2 is mounted such that A is disposed in a plane including the axis O. Therefore, the cutting edge 5 formed on the edge of the upper surface 4A is also disposed in a plane including the axis O. It will be. Accordingly, when the cutting edge 5 bites into the work material, the entire ridge line of the arc-shaped cutting edge 5 simultaneously bites into the work material, so that a shocking cutting load acts on the cutting edge 5. Resulting in. On the other hand, in addition to the case where a positive tip in which the cross section of the cutting edge 5 is an acute angle is used as the tip 2, even if a negative tip in which the cross section of the cutting edge is a right angle is used, the cutting edge strength of the cutting edge 5 naturally increases. Since there is a limit, the impact of the above-described impact cutting load when biting into the work material causes the cutting edge 5 to be damaged,
Alternatively, there has been a problem that wear is promoted at a stretch.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem. The present invention is directed to a tip of a tool body which is rotated around an axis, and a top edge of a tool body. A plurality of flat chips provided with cutting blades having a convex arc shape are oriented with the upper surface in the tool rotation direction, and are shifted from each other so that the rotation trajectory around the axis of the cutting blade forms a substantially hemisphere. In a ball end mill which is detachably mounted, the cutting edge is formed so as to be curved also in the thickness direction of the chip so that the center portion of the cutting edge expands more than the both end portions in the direction of tool rotation. And a raised surface which is connected to the cutting edge and which gradually rises in the thickness direction with respect to the cutting edge as the distance from the cutting edge increases.

[0006]

In the ball end mill having such a configuration, the cutting edge of the tip mounted on the tip of the tool body is formed so as to be curved in the thickness direction of the tip so that the center portion is swelled more in the tool rotation direction than both ends. Therefore, when this cutting edge bites into the work material, it gradually bites from the central portion of the cutting edge to both end portions. For this reason, it is possible to avoid an impact cutting load acting on the cutting blade during biting, and it is possible to suppress chipping and wear of the cutting blade. In addition, on the upper surface of the chip connected to the cutting blade, a raised surface is formed that gradually rises in the chip thickness direction as the distance from the cutting blade side increases, and the cutting edge angle of the cutting blade can be set large by this raised surface. Since the strength can be improved, it is possible to more effectively prevent the occurrence of defects and the like.

[0007]

1 to 5 show an embodiment of the present invention. In this embodiment, the tool main body 11 has a substantially cylindrical shape, and the tip is formed in a hemispherical shape. A pair of tip pockets 12, 12 are formed at the tip of the tool body 11 on opposite sides in the circumferential direction of the tool body 11, and the tool rotation direction of these tip pockets 12, 12 (see FIG. 2). On the wall facing counterclockwise)
One tip pocket 1 across the axis O of the tool body 11
Three chip mounting seats 13 are formed on two sides, and two chip mounting seats 13 are formed on the other chip pocket 12 side. The chips 14 having the same shape and the same size are removably mounted on the chip mounting seats 13 by clamp screws 15.

The chip 14 is made of a hard material such as a cemented carbide, and as shown in FIGS. 3 to 5, the chip body 16 has a flat plate shape having a substantially regular triangular shape in plan view from the upper surface 16A side. Are formed so as to intersect the lower surface 16C at an obtuse angle and have a clearance angle. Further, from the center of the upper surface 16A to the lower surface 16C, a mounting hole 17 through which the clamp screw 15 is inserted is provided.
Is pierced. Cutting edges 18 are formed on the three side edges of the upper surface 16A of the chip body 16, respectively. Each of these cutting edges 18 is formed in a convex arc shape bulging out of the chip body 16 with the same radius R in the plan view, and the radius R is equal to the upper surface 1.
6A is set to be larger than the radius of the circumscribed circle of the equilateral triangle shown in plan view. The cutting blades 18 are also curved in the thickness direction of the chip main body 16 so that the central portion 18A of the cutting blade 18 bulges toward the upper surface 16A from both ends 18B, 18B. Particularly, in this embodiment, FIG.
As shown in FIG. 3, the tip body 16 is formed to have a convex arc shape with a radius r when viewed from the side surface 16B side.

Further, a portion of the upper surface 16A of the chip body 16 on the side of the edge is connected to each of the cutting blades 18 and separated from the cutting blades 18 so that the chip body 16 can be seen in a plan view. The protruding surfaces 19 that protrude in the thickness direction of the tip body 16 are formed on the cutting blades 18. In addition,
In the present embodiment, these raised surfaces 19 are connected to the mounting holes 17.
The cutting blades 18 ...
Is formed so as to go around the side of the side ridge where the edge is formed, and the periphery of the opening of the mounting hole 17 at the center of the upper surface 16A is a flat surface parallel to the lower surface 16C. The raised surface 19 is formed such that a ridge line in a cross section orthogonal to the cutting edge 18 is linear.

Further, in this embodiment, the raised surface 19
As shown in FIGS. 3 and 5, the width m is set to be minimum at the central portion 18A of the cutting edge 18, while the ridge angle θ is set to be maximum. The width m of the raised surface 19 is gradually increased and the raised angle θ is gradually reduced toward both end portions 18B, 18B along the line 18. However,
In the vicinity of both ends 18B, 18B of the cutting blade 18, the width m is limited to the width of the end 1 because it interferes with the raised surface 19 of the adjacent cutting blade 18.
It becomes smaller as approaching 8B. Here, the minimum width m formed by the raised surface 19 in the central portion 18A of the cutting edge 18 is a radius R of an arc formed by the cutting edge 18 in the plan view.
Is preferably set to 5% or more, or 1 mm or more, and the maximum protruding angle θ formed by the protruding surface 19 is preferably set to 30 ° or less. As shown in FIG. 5, the width m of the raised surface 19 refers to the width of the raised surface 19 in a direction perpendicular to the thickness direction of the chip body 16 in a cross section orthogonal to the cutting edge 18, and the raised angle θ Means the raised surface 1 in this section
9 is an angle formed with respect to a plane perpendicular to the thickness direction (in FIG. 5, the flat surface at the center of the upper surface 16A is taken).

With the tip 14 having such a configuration, the upper surface 16A is directed in the tool rotation direction, and one cutting edge 18 is protruded to the outer peripheral side of the tool main body 11, so that the tip mounting seat 1 is formed.
3 are provided, and cutting edges in the ball end mill of the present embodiment are provided. Here each chip 1
The tips 14 on one of the tip pockets 12 are arranged such that the rotation trajectories of the respective cutting edges 18 around the axis O overlap each other to form a substantially hemisphere as a whole.
And the chips 14 on the other chip pocket 12 side are staggered. Therefore, the radius of the hemisphere formed by the rotation locus of these cutting edges 18 is equal to the radius R of the arc formed by the cutting edges 18 of the tip 14 in the plan view.

However, in the ball end mill having such a configuration, the cutting edge 18 formed on the tip 14 has the central portion 18A in the side view of the tip body 16, and the both ends 18B, 18B.
The tip 14 is curved in the thickness direction of the tip 14 so as to bulge toward the upper face 16A side from the upper face 18B, and such a tip 14 is mounted with the upper face 16A facing the tool rotation direction. Eventually, the cutting blade 18 is arranged so that the central portion 18A expands and curves in the tool rotation direction more than the end portions 18B, 18B. Therefore, when the cutting blade 18 bites into the work material, the central portion 18A first bites and then gradually bites toward both ends 18B and 18B. Therefore, unlike the above-described conventional ball end mill, an impactful cutting load does not act on the entire cutting edge at once, and such an impacting load causes the cutting edge 18 to be broken or accelerated wear. Can be prevented.

Further, a raised surface 19 is formed on the upper surface 16A of the chip 14 so as to be continuous with the cutting blade 18 and to gradually protrude with respect to the cutting blade 18 as the distance from the cutting blade 18 increases. Although the clearance angle is given to the side surface 16B of the 14, the cutting edge angle δ of the cutting blade 18 can be set large as shown in FIG. Accordingly, it is possible to secure a high edge strength to the cutting blade 18, and together with the above-described effects, it is possible to more reliably prevent the chipping or abrasion of the cutting blade 18 when biting the work material. can do. In the present embodiment, in the cross section perpendicular to the cutting edge 18, the raised angle θ formed by the raised surface 19 with respect to the surface perpendicular to the chip thickness direction has a maximum value of 30 ° at the central portion 18 A of the cutting blade 18. When the ridge angle exceeds 30 °, the blade edge strength increases, but the rake angle of the cutting edge 18 in the state in which the tip 14 is mounted on the tool body 11 is on the negative angle side. This is because there is a possibility that the cutting resistance becomes too large and the cutting resistance increases. Regarding the minimum value of the elevation angle θ, the elevation surface 19 in the cross section orthogonal to the cutting edge 18 rises in the thickness direction of the chip body 16 with respect to the cutting edge 18 as the distance from the cutting edge 18 increases. Therefore, the angle is set to exceed 0 °.

Further, in this embodiment, the raised surface 1
9 has a maximum value at the central portion 18A of the cutting edge 18, and since the clearance angle given to the side surface 16B of the tip body 16 is constant, the cutting edge angle δ of the cutting edge 18 is also large. It will be largest at the central portion 18A of the cutting blade 18. Here, since the central portion 18A of the cutting blade 18 is a portion that first bites into the work material as described above,
Is the part where the largest cutting load acts,
By setting the cutting edge angle δ to be the largest in such a portion, the largest cutting edge strength is given to the central portion 18A of the cutting edge 18 in the tip 14 of the ball end mill having the above configuration. That is, according to the present embodiment, since the greatest cutting edge strength is given to the portion of the cutting blade 18 where the largest cutting load acts, the chipping and wear of the cutting blade 18 can be more reasonably and effectively prevented. be able to. On the other hand, on both end portions 18B and 18B sides of the cutting blade 18 where only a relatively small cutting load acts,
Although the cutting edge angle δ becomes smaller, the rake angle is set to a more regular angle side than the central portion 18A to reduce the cutting resistance, and the cutting force acting on the entire cutting edge 18 is excessively large. This also has the advantage that it can be avoided.

However, in this embodiment, the raised surface 1
9 from the central portion 18A of the cutting blade 18 to the both end portions 18A.
Although it is set so as to gradually decrease toward the sides B and 18B, it may be set so that the ridge angle θ becomes equal over the entire cutting edge 18. In the present embodiment, the width m of the ridge angle θ is also formed to be the minimum width at the central portion 18A of the cutting edge 18. However, such a configuration is not always necessary, and for example, the entire circumference of the cutting edge 18 may be used. , Or the maximum width at the central portion 18A.
Further, in the present embodiment, the raised surface 19 is formed so as to go around the edge of the upper surface 16A of the chip body 16, but the entire upper surface 16 may be constituted by the raised surface 19. Furthermore, the raised surface 19 of the present embodiment is formed so that the ridge line in a cross section orthogonal to the cutting edge 18 is linear, but may be formed so that the ridge line in this cross section is curved. Further, the cutting edge 18 is formed so as to draw a convex arc having a radius r in a side view of the chip body 16, but if the central portion 18A is a curve that bulges toward the upper surface 16A from both ends 18B and 18B, Other curves may be used.

[0016]

According to the present invention as described above, according to the present invention, it is possible to prevent an impact cutting load from acting on the cutting edge when biting into the work material, and to increase the included angle of the cutting edge. High cutting edge strength can be imparted to the cutting edge, thereby effectively preventing the cutting edge from being chipped or worn, and extending the life of the tool.

[Brief description of the drawings]

FIG. 1 is a plan view of a ball end mill showing one embodiment of the present invention.

FIG. 2 is a front view of the embodiment shown in FIG. 1 as viewed from a tool tip side.

FIG. 3 is a plan view of the chip 14 mounted on the ball end mill of the embodiment shown in FIG. 1 as viewed from the upper surface 16A side.

FIG. 4 is a side view of the chip 14 shown in FIG.

5 is a ZZ cross-sectional view of the chip 14 shown in FIG.

FIG. 6 is a plan view showing a conventional ball end mill.

FIG. 7 is a front view of the conventional example shown in FIG.

8 is a plan view of the chip 2 mounted on the conventional ball end mill shown in FIG. 6 as viewed from the upper surface 2A side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Tool main body 14 Tip 16 Tip main body 16A Upper surface of chip main body 16 18 Cutting edge 18A Central part of cutting edge 18B End of cutting edge 18 19 Raised surface O Rotation axis of tool main body 11 Raised angle m of raised surface 19 Raised The width of the surface 19 R The cutting edge 18 in a plan view from the upper surface 16A side of the chip 14
Radius of the arc formed by the cutting edge r as viewed from the side 16B of the tip 14
Radius of the arc formed by δ angle of the cutting edge of the cutting edge 18

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23C 5/10 B23C 5/20

Claims (2)

(57) [Scope of request for utility model registration] 1. A plurality of flat-shaped indexable inserts provided at the tip of a tool body rotated about an axis, with a cutting edge having a convex arc shape as viewed from the upper surface side at an upper surface side ridge. In the ball end mill, which is oriented in the tool rotation direction and is removably mounted so as to be displaced from each other so that the rotation trajectory around the axis of the cutting edge forms a substantially hemisphere, the cutting edge has a center portion at both ends. In order to expand more in the direction of tool rotation, it is also formed so as to be curved in the thickness direction of the throw-away tip, and is connected to the cutting edge on the upper surface of the throw-away tip and is separated from the cutting edge side. Characterized in that a raised surface is formed on the cutting edge so as to gradually rise in the thickness direction. 2. A throw-away chip comprising a flat chip body having a substantially equilateral triangular shape in a plan view and a cutting edge having a convex arc shape as viewed from the upper surface side formed on each side ridge of the upper surface. The cutting edge is formed so as to be curved also in the thickness direction of the chip body so that the center portion swells toward the upper surface side from both end portions, and the upper surface is connected to the cutting edge,
A throw-away tip, wherein a raised surface is formed on the cutting blade so as to gradually rise in the thickness direction as the distance from the cutting blade increases.