JP2004230472A - Indexable ball end mill - Google Patents

Abstract

A throw-away ball end mill to which a substantially elliptical-shaped throw-away tip is mounted is to surely prevent the throw-away tip from rotating around a clamp.
A throw-away tip having a substantially elliptical plate shape is fitted into a tip mounting pocket formed at a tip end of an end mill main body, and the throw-away tip is attached to the end mill main body with a negative axial rake angle. The throw away tip 45 is provided with a notched flat surface 11 adjacent to the seating surface 13 on a flank along the arcuate cutting edge 15, and the tip mounting pocket 23 is provided with the tip mounting pocket 23. The notch plane 11 of the away chip 45 is provided with a notch plane flat wall 2A that is entirely in contact with the notch plane 11, and the chip seating surface 2D is formed with an escape groove 2E at an intersection with the notch plane flat wall 2A. .
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a throw-away ball end mill used for die machining and the like, and more particularly, to a throw-away ball end mill that enhances seating properties of a throw-away tip and prevents chip displacement due to cutting resistance.
[0002]
[Prior art]
The throw-away ball end mill has an approximately elliptical plate-like shape in which a tip mounting pocket is formed at a hemispherical tip of a substantially cylindrical end mill main body, and two arc-shaped cutting blades are arranged in a back-to-back relationship. Generally, a fixed throw-away tip is used.
[0003]
In this throw-away ball end mill, one arc-shaped cutting edge is positioned from the outer peripheral side of the end mill body to the tip side, the seating surface is brought into contact with the chip seating surface of the chip mounting pocket, and the other arc-shaped cutting edge is used. In a state where the flank along the groove is in contact with the arc-shaped side wall of the tip mounting pocket, the throw away tip is fixed by a clamp screw penetrating the center of the throw away tip (see Patent Document 1).
[0004]
In this throw-away ball end mill, there has been a problem in that the tip of the throw-away tip rotates around the clamp screw during the cutting process.
[0005]
In order to solve this problem, an attempt has been made to provide a notch plane on an arc-shaped flank along the arc-shaped cutting edge of the throw-away tip, and to contact this with a flat wall for a notch plane provided on the side wall of the tip mounting pocket. Has been done.
[Patent Document 1]
JP-A-4-11559
[Problems to be solved by the invention]
However, even if the notch plane is provided on the arc-shaped flank along the arc-shaped cutting edge of the throwaway tip as described above, as shown in FIG. Since a corner R-shaped (corner R9) relief portion 8 for preventing stress concentration is formed in a portion adjacent to the seating surface, as shown in FIG. The contact area was small, and the function of preventing the rotation of the throw-away tip was insufficient. In FIG. 6, a hatched portion of the flat wall for the cutout plane indicates a portion where the cutout plane of the throw-away tip comes into contact.
[0007]
In view of the above, an object of the present invention is to reliably prevent a throw away tip from rotating around a clamp in a throw away ball end mill to which a substantially elliptical plate-shaped throw away tip is mounted.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the throw-away ball end mill of the present invention is arranged such that two arc-shaped cutting blades are located on the back surface of a ridge formed by an upper surface serving as a rake surface and a side surface serving as a flank. The approximately elliptical plate-shaped throw-away tip is fitted into a tip mounting pocket formed at the distal end of the end mill main body, and one arc-shaped cutting edge of the throw-away tip is moved from the outer peripheral side of the end mill main body to the distal end side. Position, the lower surface serving as a seating surface is brought into contact with the chip seating surface of the chip mounting pocket, and the arc-shaped flank along the other arc-shaped cutting edge is formed in an arc-shaped flank formed in the chip mounting pocket. A ball end mill for fixing the throw away tip to the end mill body at a negative axial rake angle along the side wall of the throw out. In the tip, a notch plane adjacent to the seating surface is provided on an arc-shaped flank surface along the arc-shaped cutting blade, and the chip mounting pocket has a notch plane in which the notch plane of the indexable tip is entirely contacted. A flat wall is provided, and the chip seating surface is provided with an escape groove at an intersecting portion with the notched flat wall.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 1 shows a throw-away type ball end mill of the present embodiment. In the figure, reference numeral 1 denotes a cylindrical end mill main body having a hemispherical tip 1A formed in a hemispherical shape. A main blade tip mounting pocket extending rearward from the end side of the end mill main body is provided in the tip hemispherical portion 1A of the end mill main body 1. 2 and a sub-tip insert mounting pocket 3 are formed approximately 180 ° apart from each other. A main blade tip 4 and a sub-blade tip 5 are attached to these tip mounting pockets 2 and 3, respectively. 7 fixed.
[0011]
The main blade tip 4 and the sub blade tip 5 have substantially the same configuration. The main blade tip mounting pocket 2 and the sub blade tip mounting pocket 3 have substantially the same configuration. However, the main cutting tip 4 is arranged beyond the axis of the end mill main body 1, whereas the sub cutting tip 5 is not arranged beyond the axis of the end mill main body 1.
[0012]
Therefore, in the following description, the main blade tip 4 and the sub-blade tip 5 are combined into a tip 45, and the main blade tip mounting pocket 2 and the sub-blade tip mounting pocket 3 are combined into a tip mounting pocket. 23, which will be described in common.
[0013]
As shown in FIG. 2, the tip 45 used in the present embodiment is a generally elliptical indexable insert in which two arc-shaped cutting edges 15 are formed facing each other. One arc-shaped cutting edge 15 is located from the outer peripheral side of the end mill main body 1 to the distal end side. The upper surface of the chip 45 is the rake surface 12, the lower surface is the seating surface 13, and the side surface between the rake surface 12 and the seating surface 13 is the flank 10. The screw hole 14 is formed in the chip 45 so as to pass through the seating surface 13 from the center of the rake face 12. The tip 45 has a point-symmetric shape so that both of the two arc-shaped cutting blades 15 can be used. In the present embodiment, the tip 45 includes a total of two linear cutting blades 16, 16 arranged at a position between the two arc-shaped cutting blades 15, 15 in a relationship of being back surfaces.
[0014]
In FIG. 2, reference numeral 11 denotes a notched plane formed on the flank 10 along the arcuate cutting edge 15. The notch plane 11 has an inclination angle β formed by a perpendicular to the rake face 12. The inclination angle β is larger than the clearance angle α of the flank along the arcuate cutting edge 15. In order to make the area of the cutout plane sufficiently large, it is preferable that the inclination angle β is larger than the clearance angle α by 3 ° or more. Further, in order not to lower the strength of the chip 45, the inclination angle β is preferably equal to or less than 20 °.
[0015]
FIG. 3 is a perspective view showing a tip mounting pocket 23 provided in the end hemispherical portion 1A of the end mill main body 1. As shown in FIG. The chip mounting pocket 23 has a chip seat surface 2D and side walls (2A, 2B, 2C) rising from the chip seat surface 2D. The chip seat surface 2D has a negative axial rake angle. The seating surface 13 of the chip 45 is placed on the chip seating surface 2D. The flank of the chip 45 contacts the side walls (2A, 2B, 2C). A screw hole 2F is formed at the center of the chip seating surface 2D. The clamp screws 6 and 7 inserted into the screw holes 14 provided in the chip 45 are screwed into the screw holes 2F.
[0016]
The side wall of the tip mounting pocket 23 has a first flat wall 2B on the tip side. The flank of the tip 45 along the straight cutting edge 16 is brought into contact with the first flat wall 2B. An arc-shaped wall 2C is formed on the rear side of the first flat wall 2B and adjacent to the outer periphery of the end mill main body 1, where one of the flank faces along the arc-shaped cutting edge 15 of the tip 45 abuts. Have been. A second flat wall 2A is formed on the rear side of the arc-shaped wall 2C. The notch plane 11 of the chip 45 is brought into contact with the second flat wall 2A. In FIG. 3, a hatched portion of the second flat wall 2 </ b> A indicates a portion where the cutout plane 11 contacts.
[0017]
An escape groove 2E is formed at the intersection of the chip seat surface 2D and the second flat wall 2A. Here, as described above, since the chip seating surface 2D has a negative axial rake angle, the thickness of the underside of the clearance groove 2E can be kept large. Therefore, the mechanical strength of this part is sufficiently large.
[0018]
FIG. 4 is an explanatory diagram showing an engagement state between the tip 45 and the second flat wall 2A. As shown in the figure, the second flat wall 2 </ b> A is also in contact with the side edge of the chip 45 at the intersection with the seating surface 13. That is, almost the entire notch plane 11 of the chip 45 contacts the second flat wall 2A.
[0019]
According to this throw-away type ball end mill, substantially the entire surface of the notch plane 11 of the tip 45 abuts on the second flat wall 2A, so that the rotation of the tip 45 by the second flat wall 2A is extremely large. Further, as described above, since the tip seating surface 2D has a negative axial rake angle, the thickness of the lower side of the clearance groove 2E can be kept large, so that the strength of the end mill main body 1 is sufficiently large.
[0020]
In the tip 45, the clearance angle of the flank along the straight cutting edge 16 is set to about 0 °, and the first flat wall 2B is substantially upright with respect to the tip seating surface 2D in the tip mounting pocket 23. Is preferred. In this case, it is preferable that the angle between the first flat wall 2B and the chip seating surface 2D is in the range of -2 ° to 2 °. With such a configuration, the lifting of the chip 45 can be effectively prevented. As described above, since the tip bearing surface 2D has a negative axial rake angle, even if the clearance angle of the flank along the linear cutting edge 16 is 0 ° or negative, the actual clearance angle is positive, and Does not interfere.
[0021]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that the present invention can be implemented in any form without departing from the object of the invention.
[0022]
【The invention's effect】
As described above, the throw-away ball end mill of the present invention has a substantially elliptical plate shape in which two arc-shaped cutting blades are arranged on the ridge formed by the upper surface and the side surface, which are the rake surface, so that the two arc-shaped cutting blades are on the back surface. The indexable insert is fitted into a tip mounting pocket formed at the distal end of the end mill main body, and one of the arc-shaped cutting blades is positioned from the outer peripheral side of the end mill main body to the distal end side. A negative axial rake angle in a state where the chip mounting pocket is brought into contact with the chip seating surface and the flank along another arc-shaped cutting edge is along the arc-shaped side wall provided in the chip mounting pocket. A ball end mill for fixing the throw away tip to the end mill body, wherein the throw away tip is adjacent to a seating surface on a flank along the arcuate cutting edge. The tip mounting pocket has a flat wall for a notch plane in which the notch plane of the throw-away tip abuts entirely, and the tip seating surface intersects with the flat wall for the notch plane. Since the escape groove is formed in the portion, almost the entire notch plane of the chip comes into contact with the flat wall for the notch plane, and the action of suppressing the rotation of the chip by the notch plane is very large. Further, since the indexable insert has a negative axial rake angle, the thickness of the underside of the clearance groove can be kept large, so that the strength of the end mill body is sufficiently large.
[0023]
Further, as described above, since the throw-away tip has an axial rake angle, a total of two linear cutting tips are disposed on the throw-away tip between the two arc-shaped cutting blades so as to face each other. Even if the blade is formed, even if the clearance angle of the flank along the linear cutting edge is set to 0 ° or negative, the actual clearance angle becomes positive and does not interfere with the processing surface, so the side surface along the linear cutting blade The side wall of the chip mounting pocket in the portion that comes into contact with the chip mounting surface may be a flat wall that is substantially upright with respect to the chip seating surface. When the side surface along the straight cutting edge is configured to abut on a flat wall substantially upright on the chip seating surface in the chip mounting pocket of the end mill body, it is possible to effectively prevent the chip from floating. it can.
[Brief description of the drawings]
1A and 1B show a throw-away ball end mill according to an embodiment of the present invention, wherein FIG. 1A is a front view and FIG. 1B is a side view.
FIGS. 2A and 2B show a throw-away tip constituting the throw-away ball end mill of FIG. 1, wherein FIG. 2A is a top view, FIG. 2B is a side view, FIG. 2C is a bottom view, and FIG. FIG. 4 is a cross-sectional view taken along line A.
FIG. 3 is a perspective view showing a distal end portion of an end mill main body constituting the throw-away ball end mill of FIG. 1;
FIG. 4 is a view taken in the direction of arrow B in FIG. 3;
FIG. 5 is an explanatory view of a conventional throw-away ball end mill, corresponding to FIG.
FIG. 6 is a perspective view showing a distal end portion of an end mill main body constituting a conventional throw-away ball end mill.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 End mill main body 1A Tip hemispherical part 2 Main blade tip mounting pocket 3 Secondary blade tip mounting pocket 4 Main blade tip (Indexable tip)
5 Secondary Blade Inserts (Indexable Inserts)
Reference Signs List 6 clamp screw 7 clamp screw 10 flank 11 notch plane 12 rake face 13 seating surface 14 screw hole 15 arc-shaped cutting blade 16 linear cutting blade 2A Second flat wall (flat wall for notched plane)
2B First flat wall (almost upright wall)
2C Arc-shaped wall 2D Tip seat surface 2E Relief groove 2F Screw hole 23 Tip mounting pocket 45 (Indexable) Tip α Relief angle β Incline angle L1 Length L2 between tip and reference surface of holder L2 Length of chip reference surface

Claims (2)

An approximately elliptical plate-shaped insert insert in which two arc-shaped cutting blades are arranged in a back-to-back relationship on a ridge formed by an upper surface serving as a rake surface and a side surface serving as a flank, and a tip end of an end mill body. And the one arc-shaped cutting edge of the throw-away tip is positioned from the outer peripheral side of the end mill main body to the distal end side, and the lower surface serving as a seating surface is inserted into the tip of the tip mounting pocket. With a negative axial rake angle with the abutment against the seat surface, and with the arc-shaped flank along the other arc-shaped cutting edge along the arc-shaped side wall formed in the tip mounting pocket, A ball end mill for fixing the throw-away tip to the end mill body, wherein the throw-away tip is adjacent to the seating surface at an arc-shaped flank along the arc-shaped cutting edge. Notch plane, the tip mounting pocket is provided with a flat wall for a notch plane that the cutout plane of the throw-away tip is in full contact with, and the tip seating surface is formed with the flat wall for the notch plane. A throw-away ball end mill, characterized in that a relief groove is provided at the intersection of. The indexable insert includes a total of two linear cutting blades arranged in a back-to-back relationship with each other, one of which is disposed on the outer peripheral side of the end mill body and the other linear cutting edge is disposed. The indexable insert according to claim 1, wherein the flank along the blade is in contact with a flat wall substantially upright with respect to the tip seat surface in the tip mounting pocket of the end mill body.

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