JPH0744409Y2 - Ball end mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a ball end mill in which one throwaway chip having an arcuate cutting edge is detachably mounted on the outer periphery of the end portion of an end mill body. .

[Prior Art] FIGS. 12 to 14 show a conventional ball end mill of this kind disclosed in Japanese Patent Publication No. 59-21724 previously by the present applicant.

This ball end mill has a plate-like shape, and has an arc surface that draws a quarter circle between the upper surface 2 and the lower surface, and a notch 3 having a substantially V-shaped section between the upper surface 2 and the lower surface between the arc surfaces. 3 are formed point-symmetrically, the mounting reference surface 4 is formed on one wall surface of the two wall surfaces that define each notch 3, and the intersection of the other wall surface and the upper surface 2 is the upper surface 2. To a lower surface, a curved surface 5 is formed on the lower surface, and a cutting edge 6 is formed on a ridge formed by the curved surface 5 and the upper surface 2 and an arc surface (hereinafter referred to as a chip). ) 1 is detachably attached to the outer periphery of the tip portion of the end mill body 7 so that the cutting edge 6 thereof participates in cutting.

According to the above-mentioned conventional ball end mill, at the time of cutting, first, the tip end of the cutting edge 6 of the chip 1 bites into the work material (not shown), and then the cutting edge 6 is gradually rotated as the end mill body 7 rotates. Since the whole is cut, there is an advantage that an impact cutting load does not act.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional ball end mill, the mounting reference surface 4 formed in the vicinity of the tip of the cutting edge 6 of the chip 1 extends in the axial direction of the end mill body 7. There is a problem that the chips that are ejected hinder the discharge of the chips.

The present invention aims to solve the above problems.

[Means for Solving Problems] In a ball end mill of the present invention, a throw-away tip, which is formed in point symmetry with respect to the center and has a plate shape of an ellipse in plan view, is formed on the outer periphery of the tip portion of the end mill body. A small cutting edge is formed at the tip of the arc-shaped cutting edge that intersects it at an obtuse angle, and the entire rake face along the small cutting edge and the tip of the cutting edge is cut from the center side of the throw-away tip. By being formed as a convex curved surface that gradually approaches the seating surface side toward the side, the tip of the cutting edge is formed into an arc shape in the chip thickness direction, and the tip of the cutting edge is positioned near the axis of the end mill body, Also, position the small cutting edge so that it crosses the axis and retracts toward the base end side of the end mill body, and the convex part provided on the tip mounting seat fits into the hole formed on the seating surface of the throw-away tip. Installed, positioned It is characterized by being.

[Operation] In the ball end mill configured as described above, since the cutting edge located on the tip side of the end mill body of the mounted chip has an arc shape, an impact cutting load is applied when biting. There is no.

Further, unlike the conventional one, since there is no wall surface in the vicinity of the cutting blade which hinders the discharge of chips, the chips can be discharged smoothly.

[Embodiment] FIGS. 1 to 11 show an example of the ball end mill of the present invention.

1 to 5, reference numeral 10 in the drawings denotes an end mill body. The end mill main body 10 has a generally cylindrical shape, and its tip portion is formed in a substantially hemispherical shape. On the outer periphery of the tip portion, a chip pocket 11 is formed by cutting off approximately 1/4 of the circumference, and the chip mounting seat 12 is attached to the wall surface facing the rotation direction of the chip pocket 11.
Are formed. The chip 20 is attached to the chip mounting seat 12.

This chip 20 has an upper surface 21 as shown in FIGS.
It is a plate-like member having a rake face and a flat lower surface 22 as a seating surface. Between these upper and lower surfaces 21 and 22, two short-sided planar side surfaces 23 that intersect the upper surface 21 at an acute angle, respectively, and draw a quarter circle that is longer than the planar side surfaces 23 Two arcuate side surfaces 24 are formed alternately in the circumferential direction with an obtuse angle in between and are point-symmetric with respect to the center of the chip 20.

And, in the ridge line portion between each arc-shaped side surface 24 and the upper surface 21,
A cutting edge 26 is formed. In addition, the flat side surface 23 and the top surface 21
A small cutting edge 27 that intersects the cutting edge 26 at an obtuse angle is formed in the ridge portion between and.

Further, the upper surface 21 along the tip of the cutting edge 26 and the small cutting edge 27,
The whole is formed by a convex surface 28 that gradually approaches the lower surface 22 side from the center side of the chip 20 toward the small cutting edge 27 side.

A circular recess (hole) 30 having a larger diameter than the hole 29 is formed in a portion of the lower surface 22 serving as a seating surface where the mounting hole 29 is opened. Then, as shown in FIG. 10 and FIG. 11, a cylindrical convex portion 31 that engages in the concave portion 30 is formed at a position facing the concave portion 30 on the bottom surface 15 of the chip mounting seat 12. There is.

The chip 20 is mounted on the tip mounting seat of the end mill body 10 as shown in FIGS. 1 to 5, 10, and 11.
12, the convex portion 31 is engaged with the concave portion 30 to attach the mounting hole 29.
It is detachably mounted by a mounting bolt 16 inserted therein. Here, in the chip 20, the tip of the cutting blade 26 is located in the vicinity of the axis O of the end mill main body 10, and the small cutting blade 27 traverses the axis O so as to retract toward the base end side of the end mill main body 10. It is located and attached to. In addition,
The portion of the tip 20 of the end mill body 10 that comes into contact with the small cutting edge 27 is not a seating reference portion as is apparent from FIG.

In the ball end mill having the above structure, the tip of the cutting blade 26 located on the axis O side of the mounted chip 20 has an arcuate shape due to the convex curved surface 28. The cutting load does not act, so that the chipping can be prevented.

Moreover, like the conventional one, the flat side surface of the small cutting blade 27 side
Since the standing wall that hinders the discharge of chips is not formed in 23, excellent chip discharge performance can be obtained.

In addition, a large load acts in the axial direction during cutting,
The cutting force acting on the small cutting edge 27 is perpendicular to the small cutting edge
As the tip 20 moves toward the base end side of the end mill body 10 along the longitudinal direction of 20 (even if the tip 20 is not received), the projections and depressions 30 and 31 move the chip 20 on the chip mounting seat 12 even if it acts. Is reliably blocked, the chip 20
Does not move. Therefore, the cutting accuracy does not deteriorate even when cutting is carried out at a high speed in the axial direction, and therefore, in combination with the excellent cutting edge strength and chip discharging performance at the tip of the cutting edge 26 peculiar to this ball end mill, the axial direction High feed cutting can be performed with high processing accuracy.

[Effect of the Invention] According to the ball end mill of the present invention, the throw-away tip has a small cutting edge that intersects with the arc-shaped cutting edge at an obtuse angle, and that the small cutting edge and the tip of the cutting edge are While the entire rake face of the portion along the is formed as a convex curved surface, the tip of the cutting edge is formed into an arc shape in the chip thickness direction, and
The tip of the cutting edge is located near the axis of the end mill body, and the small cutting edge is positioned so that it crosses the axis and retracts toward the base end side of the end mill body. Since the convex part provided on the chip mounting seat is fitted, positioned and mounted on the part, the convex part of the chip mounting seat that fits into the hole on the chip seating surface is used as the seating reference part. By positioning, even if a large load acts in the axial direction during cutting, the movement of the tip is reliably prevented, and high machining accuracy can be maintained even with high feed cutting in the axial direction. Moreover, since the end side surface of the small cutting edge is not used as a seating standard, the tip itself can be downsized, and even if the small cutting edge is lost during cutting, it will be difficult to install for corner change and use on both sides of the tip. In addition, since there is no load, the load can be received by the convex portion and the hole that are fitted to each other so that they face each other in the direction in which the cutting force acts on the small cutting edge. As a result, excellent cutting accuracy can be obtained.

Moreover, since the rake face of the tip of the tip is a convex curved surface and the tip of the cutting edge is arcuate in the thickness direction of the tip, a shocking cutting load does not act when biting and the tip of the cutting edge is small. It is possible to reliably prevent the cutting edge from being damaged. Further, since the central portion of the chip rake surface is flat, there is an advantage that the size of the chip can be easily adjusted and the manufacturing is easy.

[Brief description of drawings]

1 to 11 show an embodiment of the ball end mill according to the present invention. Fig. 1 is a front view, Fig. 2 is a side view, Fig. 3 is a bottom view, and Fig. 4 is Fig. 1. "A" part enlarged view of Fig. 5, Fig. 5 "B" part enlarged view of Fig. 3, Fig. 6 is a front view showing the attached chip, and Fig. 7 is a line VII-VII view of Fig. 6. A side view, FIG. 8 is a view taken along the line VIII-VIII in FIG. 6, and FIG.
FIG. 10 is a sectional view taken along the line IX-IX in FIG. 10, FIG. 10 is a perspective view showing a mounted state of the chip, FIG. 11 is a sectional view of a chip mounting portion, and FIGS. 12 to 14 show a conventional ball end mill. , FIG. 12 is a front view, FIG. 13 is a side sectional view of the tip portion, and FIG.
The figure is a bottom view. 10 …… End mill body, 20 …… Chip (throw away chip), 21 …… Upper surface (rake surface), 22 …… Lower surface (seating surface), 23,24 …… Side surface, 26 …… Cutting edge, 27 …… Small cutting blade, 28
…… Convex curved surface.

Front page continuation (72) Inventor Masayuki Okawa 1-27-20 Nishishinagawa, Shinagawa-ku, Tokyo Mitsubishi Metals Co., Ltd. Tokyo Works (56) Reference JP-A-54-93284 (JP, A) JP-A-55 -37208 (JP, A) Actual development Sho 62-22014 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A throw-away tip, which is formed in a point symmetry with respect to the center and has a substantially elliptical plate shape in plan view, on the outer circumference of the tip of the end mill body, and has one arc-shaped cutting edge of the end mill body. In a ball end mill mounted from the outer peripheral side to the tip side, the throw-away tip has a small cutting edge that intersects with the obtuse angle at the tip of the arc-shaped cutting edge, and the small cutting edge The tip of the cutting edge is formed by forming the entire rake surface of the portion along the tip of the cutting edge as a convex curved surface that gradually approaches the seating surface side from the center side of the throw-away tip toward the small cutting edge side. Is formed in an arc shape in the chip thickness direction, the tip of the cutting edge is positioned near the axis of the end mill body, and the small cutting edge is moved across the axis and retracts to the base end side of the end mill body. Yo The ball end mill is characterized in that the convex portion provided on the tip mounting seat is fitted into the hole formed on the seating surface of the throw-away tip, positioned and mounted.