JP2004017240A - Ball end mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely provide a deposit of chips, without lowering the rigidity of a tool body unnecessarily. <P>SOLUTION: In a tip portion 11 of the tool body 10 other than chip pockets 12, 13, by notching a portion which is positioned at the back side in the turning direction of a tool in substantially circular arc cutting edges 27, 27 of chips 20, 20', a notched face of a convex curved shape is formed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ball end mill of a throw-away type, for example.
[0002]
[Prior art]
For example, in a two-flute throw-away type ball end mill, a pair of tip pockets is formed by cutting off a tip end of a tool body rotated about an axis, and further formed in each of the pair of tip pockets. The insert mounting seat has a throw-away tip (hereinafter, referred to as a tip) having a substantially arc-shaped cutting edge, and a substantially hemispherical shape in which the rotation locus of the cutting edge around the axis is convex toward the tip end in the axial direction. It is attached to make it.
In such a ball end mill, the portion excluding the tip pocket at the tip of the tool body has a radius slightly smaller than a substantially hemisphere formed by the rotation locus of the substantially arc-shaped cutting blade in order to secure the rigidity as large as possible. It is formed to have a substantially hemispherical shape.
[0003]
At this time, if the tip of the tool body simply forms a substantially hemisphere slightly smaller than the substantially hemisphere formed by the rotation locus of the cutting blade, the chips generated by the cutting blade during cutting of the workpiece are not used. May be caught between the outer peripheral surface of the tip of the tool body and the machined surface of the workpiece, and the caught chips cause abrasion on the outer peripheral surface of the tip of the tool body, so that the welding of the chips is There is a problem that it occurs.
In particular, in the case of a small-diameter ball end mill, it is difficult to secure the rigidity of the tool body, and the deflection of the tool body makes it easier for the outer peripheral surface of the tip of the tool body to come into contact with the work surface of the workpiece. The problem becomes noticeable.
[0004]
[Problems to be solved by the invention]
Therefore, conventionally, in order to solve the above-mentioned problem, a flat notch is formed by notching a portion of the tip of the tool body located on the rear side in the tool rotation direction of the cutting edge of the tip with a plane. A surface is formed.
In other words, by cutting in advance the portion of the tip of the tool body, which is likely to cause abrasion due to the chip incorporation, located on the rear side of the cutting blade in the tool rotation direction, the cut surface and the work surface of the workpiece are cut. Thus, a gap between them is ensured to solve the above-mentioned problem.
[0005]
However, the formation of the flat cutout surface in this manner requires a large amount of shaving at the tip of the tool body, which causes a new problem that the rigidity of the tool body is significantly reduced.
In addition, since the intersection ridge line between the flat notch surface and the outer peripheral surface of the tip of the tool body is formed to be relatively sharp and sharp, chips are easily caught on the intersection ridge line, and rigidity is increased. Despite the fact that the flat cutout surface was formed with the knowledge of lowering it, it was not possible to sufficiently exert the effect of preventing chip welding.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a ball end mill capable of reliably preventing chip welding without reducing the rigidity of a tool body more than necessary.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve such an object, the present invention provides a substantially hemispherical shape in which a distal end portion of a tool body rotated around an axis is convex toward the distal end side in the axial direction. In a ball end mill having a substantially arc-shaped cutting edge whose rotation trajectory around the axis forms a substantially hemisphere at the tip end, a portion of the tip end located on the rear side in the tool rotation direction of the cutting edge is cut. It is characterized in that a cutout surface having a convex curved shape is formed by the chipping.
With such a configuration, a notch surface is formed at the tip of the tool body, so that a sufficient clearance can be secured between the notch surface and the work surface of the work when cutting the work, so that chips can be removed. It is possible to effectively suppress chip welding without causing entangling.
In addition, since the notched surface has a convex curved surface, the tip of the tool main body is not largely removed as compared with the conventional flat notched surface, and the wall thickness is sufficiently reduced. Since it can be maintained, the rigidity of the tool body is not inadvertently reduced.
In addition, the intersection ridge portion between the convex curved notch surface and the outer peripheral surface of the tip of the tool body may be formed sharper and sharper than the conventional flat notch surface. Since the chips are not caught, the chips can be prevented from being caught and welding of the chips can be more reliably prevented.
[0008]
Further, a portion of the tool body located on the rear end side of the cutout surface in the axial direction of the tool body is cutout to form a second cutout surface having a convex curved surface connected to the cutout surface. In addition to the above-described notch surface being formed at a position where chip welding is most likely to occur, and the second notch surface being formed at a position where even slight chip welding may occur, Chip welding can be more reliably prevented.
Further, despite the fact that such a second notch surface is formed in the tool body, the second notch surface has a convex curved surface shape. There is no possibility that the rigidity of the main body is unnecessarily reduced.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a ball end mill according to a first embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a perspective view of the ball end mill according to the first embodiment, FIG. 2 is a plan view of the ball end mill, FIG. 3 is a side view of the ball end mill, and FIG.
[0010]
As shown in FIGS. 1 to 4, the ball end mill according to the first embodiment is, for example, a two-flute indexable end mill on which two chips are mounted, and a substantially circular shape that is rotated around an axis O. The tool body 10 has a columnar shape.
The distal end portion 11 of the tool main body 10 has a substantially hemispherical shape that is convex toward the distal end side in the direction of the axis O, and the distal end portion 11 is located on the opposite side so as to sandwich the axis O from the distal end side in the direction of the axis O. As shown in FIG. 4, a pair of chip pockets 12 and 13 are formed so as to be cut out at substantially right angles.
One chip pocket 12 of the pair of chip pockets 12 and 13 is cut and formed so as to include the axis O, while the other chip pocket 13 is formed so as not to include the axis O. One chip pocket 12 is formed larger than the other chip pocket 13.
[0011]
The tip end portions of the tool bodies of the wall surfaces 12A and 13A facing the tool rotation direction T rear side in the tip pockets 12 and 13 intersect the outer peripheral surface of the tip portion 11 of the tool body 10 and move toward the tool body rear end side. Accordingly, it is formed to be curved toward the rear side in the tool rotation direction T.
On the wall surfaces of the tip pockets 12 and 13 facing the front side in the tool rotation direction T, first tip mounting seats 14 and 14 are formed on the front end sides of the respective tool bodies and the rear end sides of the respective tool bodies. Are formed with second chip mounting seats 15, 15.
[0012]
The first tip mounting seats 14, 14 formed on the tip side of the tool body of the tip pockets 12, 13 are retracted one step backward from the wall surfaces of the tip pockets 12, 13 in the tool rotation direction T, and the tip end of the tool body 10. 11, a flat bottom surface 14A in which two keys 14C, 14C and a clamp screw hole 14D are formed, and a wall surface 14B rising from the bottom surface 14A.
[0013]
Here, the tip 20 mounted on the first tip mounting seat 14 of the one tip pocket 12 is formed of a hard material such as a cemented carbide, for example, and has a substantially leaf-shaped plate shape. An upper surface 22 which is a rake face is provided opposite to a lower surface 21 which forms a seating surface when mounted, and a side surface 23 which is a flank is gradually inclined outward from the lower surface 21 toward the upper surface 22. It is provided as a positive chip.
In addition, the chip 20 has a through hole 29 for clamping a screw, which penetrates from the central portion of the upper surface 22 to the lower surface 21. For example, two key grooves 28, 28 are formed.
[0014]
A pair of cutting blades 27, 27 each having a substantially 1/4 arc shape in a plan view are formed at the intersection ridge line portion between the upper surface 22 and the side surface 23 so as to be located on opposite sides of the insertion hole 29. I have. These cutting blades 27, 27 are formed so as to be point-symmetric with respect to the center of the chip 20 in a plan view, and are designed so that one chip can be used twice.
[0015]
In addition, the upper surface 22 is formed so as to gradually approach the lower surface 21 of the tip 20 as it goes toward the corner 27A at the front end and the corner 27B at the rear end of the one cutting edge 27 at both ends in the longitudinal direction. Two inclined surfaces 22A and 22B are formed.
In the upper surface 22 excluding the inclined surfaces 22A and 22B, the periphery of the insertion hole 29 at the center of the upper surface 22 is a flat surface 22C parallel to the lower surface 21 and the periphery of the flat surface 22C, that is, the upper surface. In the vicinity of a pair of cutting blades 27 formed on the side ridges of the 22, serrations 26, 26 in which a plurality of grooves 24 and peaks 25 are alternately arranged at substantially equal intervals are formed, respectively.
[0016]
The plurality of grooves 24 and the ridges 25 constituting the serration 26 are respectively formed by smooth curved surfaces and are smoothly connected to each other. Further, the plurality of grooves 24 and the ridges 25 in the serration 26 are By intersecting a pair of substantially arc-shaped cutting blades 27, 27 formed on the side ridges, the substantially entire length of the cutting blades 27, 27 has a wavy shape formed by a smooth curve. At least one of the plurality of grooves 24 forming the serration 26 is a deep groove formed to be deeper than the other grooves.
[0017]
The tip 20 has a top surface 22 facing the front side in the tool rotation direction T at a first tip mounting seat 14 at a tip end side of the tool body of one tip pocket 12, and a side surface 23 continuing to the other cutting edge 27 is attached to a wall surface 14 </ b> B. Further, a corner 27A at the tip of one of the cutting blades 27 is positioned on the axis O, and the one cutting blade 27 is arranged so as to extend outward from the rear end of the tool body.
Then, the clamp screw 16 is passed through the insertion hole 29 of the chip 20 and screwed into the clamp screw hole 14D formed on the bottom surface 14A of the first chip mounting seat 14. 27 are mounted so that the rotation trajectory around the axis O is substantially hemispherical.
Further, the keys 14C, 14C formed on the bottom surface 14A of the first chip mounting seat 14 are engaged with the key grooves 28, 28 of the chip 20, thereby preventing the chip 20 from shifting.
[0018]
The tip 20 ′ mounted on the first tip mounting seat 14 on the tool tip end side of the other tip pocket 13 has substantially the same shape as a slightly reduced length of the tip 20. The same parts as those of the chip 20 are denoted by the same reference numerals, and description thereof is omitted.
As shown in FIGS. 2 and 4, the tip 20 'has a corner 27A at the tip of the cutting edge 27 of the tip 20' slightly smaller than the corner 27A at the tip of the cutting blade 27 of the tip 20. Side, from which the cutting edge 27 of the tip 20 ′ extends to the outer peripheral side of the rear end of the tool body, and the rotation trajectory of the cutting edge 27 of the tip 20 It is arranged so as to overlap with the rotation locus.
[0019]
On the second tip mounting seat 15 on the rear end side of the tool body of the other tip pocket 13, a chip 30 having a substantially rectangular flat plate shape is provided with a substantially straight cutting blade 31 formed on a side ridge on the upper surface thereof. Is mounted so as to overlap the rotation locus of the cutting edge 27 of the tip 20 mounted on the first chip mounting seat 14 of the one tip pocket 12.
On the second tip mounting seat 15 on the rear end side of the tool body of one of the tip pockets 12, a substantially rectangular flat plate-like tip 40 is provided with a substantially straight cutting edge 41 formed on a side ridge on the upper surface thereof. Is mounted so as to overlap the rotation locus of the cutting edge 31 of the tip 30 mounted on the second chip mounting seat 15 of the other chip pocket 13.
[0020]
In the first embodiment, the rotation locus of the tip 20 around the axis O at the tip portion 11 of the tool body 10 having a substantially hemispherical shape protruding toward the tip side in the direction of the axis O except for the tip pockets 12 and 13. Is cut off at a portion of the cutting blade 27, which is substantially hemispherical, located on the rear side in the tool rotation direction T, so that a notched surface 17 having a convex curved surface shape protruding toward the front end side in the direction of the axis O and the outer peripheral side of the tool body. Is formed.
[0021]
The notch surface 17 is located on the rear side in the tool rotation direction T with respect to the intersection ridge line where the bottom surface 14A of the first tip mounting seat 14 on which the tip 20 is mounted intersects the outer peripheral surface of the tip end portion 11 of the tool body 10. A predetermined distance away from the tool pocket in the tool rotation direction T of the other tip pocket 13 adjacent to the one of the tip pockets 12 having the first tip mounting seat 14 on which the tip 20 is mounted, in the tool rotation direction T of the other. Is formed until it intersects the wall surface 13A facing the front.
[0022]
A substantially hemispherical surface is formed between the notch surface 17 and a portion where the bottom surface 14A of the first chip mounting seat 14 on which the chip 20 is mounted intersects the outer peripheral surface of the tip end portion 11 of the tool body 10. In other words, the outer peripheral surface of the distal end portion 11 of the tool body 10 is left, that is, the outer peripheral surface 11A that forms a part of the substantially hemispheric surface is left. An intersecting ridge line portion M with the outer peripheral surface 11A has a curved shape protruding forward in the tool rotation direction T.
Note that the cutout surface 17 is located just behind the bottom surface 14A of the first chip mounting seat 14 formed in the one chip pocket 12, so that the first chip mounting seat 14 A clamp screw hole 14D formed in the bottom surface 14A is open at a portion of the notch surface 17 on the front side in the tool rotation direction T.
[0023]
Here, when viewed in a cross section taken on a plane perpendicular to the axis O, the outer peripheral surface 11A that forms a part of the substantially hemispherical surface forms an arc of a circle centered on the axis O, but has a notched surface. An outer peripheral surface 11A is located at a predetermined distance in a direction just opposite to the cutout surface 17 with respect to the axis O, is centered on an axis O 'parallel to the axis O, and forms a part of a substantially hemispherical surface. Make an arc of a circle having a radius larger than the radius of the circle forming the arc.
[0024]
Further, when viewed in a cross section by a plane including the axis O, the outer peripheral surface 11A which forms a part of the substantially hemispherical surface forms an arc of a circle centered on one point on the axis O, but has a notched surface. In 17, the outer peripheral surface 11 </ b> A forming a part of the substantially hemispherical surface forms a curve with a radius of curvature larger than the radius of a circle forming an arc.
The cutout surface 17 may be formed so as to form a part of a substantially hemispherical surface (having a larger radius than the outer peripheral surface 11A forming a part of the substantially hemispherical surface).
[0025]
Such a notched surface 17 is shown in FIG. 3 by performing a grinding process while rotating the tool body 10 after forming the chip pockets 12 and 13 in an eccentric state about the axis O ′. It can be formed by removing such hatched portions.
In addition, at the distal end portion 11 of the tool body 10 which is convex to the distal end side in the direction of the axis O except for the tip pockets 12 and 13, the rotation trajectory around the axis O of the tip 20 'is substantially hemispherical. A notch surface 17 ′ similar to the notch surface 17 is also formed at a portion of the cutting blade 27 located on the rear side in the tool rotation direction T.
[0026]
According to the ball end mill of the first embodiment having the above-described configuration, at the time of cutting the work, the chips 20, 20 at the tip end portion 11 of the tool main body 10, which are easy to wind chips into the work surface of the work. The portions of the cutting edges 27, 27 of the 20 'located on the rear side in the tool rotation direction T are removed in advance, and the cutout surfaces 17, 17' are formed. Therefore, the chips are not entrained, and the chips are effectively welded. Can be suppressed.
[0027]
In addition, since the notched surfaces 17 and 17 ′ have a convex curved shape, the distal end portion 11 of the tool body 10 is largely shaved as compared with a conventional flat notched surface. Therefore, the thickness can be sufficiently ensured, and the rigidity of the tool main body 10 is not inadvertently reduced.
That is, in the ball end mill of the first embodiment, the tip 11 of the tool main body 10 is efficiently cut out in a convex curved shape, so that the rigidity of the tool main body 10 is not reduced more than necessary, and the welding of chips is performed. Can be reliably prevented.
[0028]
Furthermore, the angle between the convex curved notch surfaces 17, 17 'and the outer peripheral surface 11A forming a part of the substantially hemispherical surface at the tip end portion 11 of the tool body 10 is less than that of the conventional flat notch surface. Thus, the intersection ridgeline portion M is formed, and the intersection ridgeline portion M is not sharply pointed, so that chips are less likely to be caught and welding of the chips can be more reliably prevented.
[0029]
It should be noted that, as in the first embodiment, even if the notch surfaces 17 and 17 'are simply formed in the tip portion 11 of the tool body 10, a sufficient effect can be obtained in preventing chip welding. A second notch surface may be formed in the tool main body 10 so as to be continuous with the rear ends of the notch surfaces 17 and 17 'in the direction of the axis O. In such a case, a second embodiment of the present invention will be described. This will be described with reference to FIGS. The same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.
FIG. 5 is a perspective view of the ball end mill according to the second embodiment, FIG. 6 is a plan view of the ball end mill, FIG. 7 is a side view of the ball end mill, and FIG.
[0030]
As shown in FIGS. 5 to 8, the tool body 10 ′ of the ball end mill according to the second embodiment has a portion located on the rear end side of the notch surface 17 formed at the front end portion 11 in the axis O direction. Are notched, respectively, so as to smoothly connect to the notch surface 17, intersect with the wall surface 12 </ b> A facing the tool rotation direction T rear side in one of the tip pockets 12, and have a convex curved surface that protrudes toward the outer periphery of the tool body. A second cutout surface 18 is formed.
The second cutout surface 18 has a front end portion in the direction of the axis O smoothly connected to the cutout surface 17, and an intersection ridge line between the second cutout surface 18 and the cutout surface 17. The portion M1 is located on a plane orthogonal to the axis O and forms an arc of a circle about the axis O '.
[0031]
Then, the second notch surface 18 extends from the intersection ridge line portion M1 toward the rear end side in the axis O direction while reducing the notch allowance, and finally, the position in the axis O direction becomes one side. In the vicinity of the tip 40 mounted on the second tip mounting seat 15 of the tip pocket 12, the tip pocket 12 is cut off on the outer peripheral surface of the tool body 10 '.
Further, an intersection ridge portion M2 between the second cutout surface 18 and the outer peripheral surface of the tool main body 10 'has a curved shape that is convex toward the rear end side in the axis O direction.
[0032]
Here, when viewed in a cross section by a plane orthogonal to the axis O, the second notch surface 18 is formed around the axis O ′, and the outer peripheral surface 11A that forms a part of the substantially hemispherical surface has a circular arc. The second cutout surface 18 is formed by a cutout surface 17 when viewed in a cross section of a plane including the axis O, which is a circular arc having a radius larger than the radius of the circle to be formed. A straight line that is smoothly connected to the rear end of the curve in a tangential relationship and that is inclined toward the outer peripheral side of the tool body (for example, an inclination angle of 3 °) toward the rear end side in the axis O direction. Has become.
The second cutout surface 18 may be formed so as to form a part of a conical surface of a substantially conical body.
[0033]
Such a second cutout surface 18 is formed by eccentricity of the tool main body 10 ′ after the formation of the chip pockets 12 and 13 about the axis O ′ as in the case of forming the cutout surface 17. By performing a grinding process while rotating in a state, it can be formed by removing a hatched portion as shown in FIG.
In the tool main body 10 ', a notch surface 18' similar to the second notch surface 18 is also formed in a portion located on the rear end side of the notch surface 17 'in the direction of the axis O. .
[0034]
According to the ball end mill of the second embodiment having the above-described configuration, the notch surfaces 17, 17 'are formed at the tip end portion 11 of the tool main body 10', and a portion where chips are easily welded is formed. In addition to being removed in advance, the second notch surfaces 18 and 18 'are formed at portions of the notch surfaces 17 and 17' located on the rear end side in the axis O direction. A portion where there is a possibility of welding is completely cut off, and a reliable chip welding prevention effect can be obtained.
In addition, since the second cutout surfaces 18 and 18 'have a convex curved shape, the rigidity of the tool body 10' is not unnecessarily reduced similarly to the cutout surfaces 17 and 17 '. is there.
[0035]
【The invention's effect】
According to the present invention, by forming the notch surface in the shape of a convex curved surface at the tip end portion of the tool main body, welding of chips can be effectively suppressed during cutting of a work, and Since the tip portion is not largely scraped, the rigidity of the tool body is not inadvertently reduced.
Also, since the intersection ridge line between the notch surface of the convex curved surface and the outer peripheral surface of the tip of the tool body is not formed sharply and sharply, it is possible to reduce the engagement of chips and reduce the welding of chips. This can be more reliably prevented.
[Brief description of the drawings]
FIG. 1 is a perspective view of a ball end mill according to a first embodiment of the present invention.
FIG. 2 is a plan view of the ball end mill according to the first embodiment of the present invention.
FIG. 3 is a side view of the ball end mill according to the first embodiment of the present invention.
FIG. 4 is a front end view of the ball end mill according to the first embodiment of the present invention.
FIG. 5 is a perspective view of a ball end mill according to a second embodiment of the present invention.
FIG. 6 is a plan view of a ball end mill according to a second embodiment of the present invention.
FIG. 7 is a side view of a ball end mill according to a second embodiment of the present invention.
FIG. 8 is a front end view of a ball end mill according to a second embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 10 Tool body 11 Tip portion 11A Outer peripheral surface 12 forming part of a substantially hemispherical surface One chip pocket 13 The other chip pocket 14 First chip mounting seats 17, 17 'Notch surfaces 18, 18' Second notch Surface 20, 20 'Tip 27 Cutting Edge O Axis

Claims (2)

The tip of the tool body rotated about the axis forms a substantially hemisphere convex to the tip side in the axial direction. In a ball end mill with a cutting blade,
A ball end mill, wherein a portion of the cutting edge located on the rear side in the tool rotation direction of the cutting edge is cut out to form a cutout surface having a convex curved shape. The ball end mill according to claim 1,
A second cutout surface having a convex curved surface connected to the cutout surface is formed by cutting out a portion of the tool main body located on the rear end side in the axial direction of the cutout surface. And ball end mill.

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