JPH07614U - Throw-away tip and ball end mill equipped with it - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the rigidity and sharpness of the tip and increase the number of flutes in the ball end mill. [Structure] The ball end mill 8 has a central cutting edge tip 12,
The intermediate cutting edge tip 13 and the outer peripheral cutting edge tip 14 are vertically arranged. The central cutting edge tip 12 located near the axis of rotation has a substantially triangular plate shape, and each side includes a cutting edge portion 22 and a straight line portion 23 that are convex curved in plan view. The upper surface 19 is provided with planar inclined surfaces 21a, 21b, 21c so that the distance between the upper and lower surfaces gradually decreases from the boundary portion 20 and the end of the cutting hole 17 toward the corner portions 12a, 12b, 12c. Therefore, the cutting edge portion 22 and the straight line portion 23 have a roof-like shape in a side view with the connection portion with the boundary portion 20 as a boundary.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a throw-away type ball end mill equipped with a throw-away tip.

[0002]

[Prior art]

 BACKGROUND ART Conventionally, there is known a ball end mill in which the tip of a tool body is formed into a ball shape, and a plurality of kinds of throw-away tips are detachably attached from the vicinity of the center of rotation of the tip to a cylindrical portion. One example thereof will be described with reference to FIG. At the tip of the tool body 1, a substantially triangular plate-shaped central cutting edge tip 2 that cuts the center of rotation of the tool body is attached to a tip pocket 3 in a horizontal state. Further, on the outer peripheral side of the ball-shaped portion with respect to the central cutting edge tip 2, an intermediate cutting edge tip 4 for cutting a work material on the outer peripheral side of the central cutting edge tip 2 is horizontally mounted, and further outside In the cylindrical portion of the tool body 1, an outer peripheral cutting edge 5 is similarly arranged horizontally.

[0003]

[Problems to be solved by the device]

 By the way, in such a cutting blade tip, in the case of horizontal placement, the central cutting blade tip 2 located at the center is liable to be broken by the rotation of the ball end mill, and has a drawback that the rigidity is low. If the mounting position of the central cutting edge tip 2 is displaced in the direction away from the center of rotation in order to suppress chipping, the number of cutting edge tips that can be mounted is reduced. Further, in particular, since the blade of the central cutting edge tip 2 is linear in a side view and the upper surface facing the lower surface which is the seating surface is formed into a flat surface, when the ball is mounted on the ball end mill, the tip is placed vertically. When set to, the rake angle of the rake face becomes a negative angle, but the negative angle is large, which causes a problem that the sharpness near the rotation center is poor. Also, in the case of the horizontal cutting edge tip shown in FIG. 7, it is necessary to form a curved surface in the direction in which the thickness is reduced from the center of the ball-shaped portion toward the outer peripheral direction. However, the molding process is difficult, and it is necessary to separately form the cutting edge after the molding process to form the cutting edge, which is complicated.

In view of the above problems, an object of the present invention is to provide a throw-away tip having high rigidity and improved sharpness and a ball end mill including the same.

[0005]

[Means for Solving the Problems]

 The throw-away tip according to the present invention is a throw-away tip of a substantially triangular plate shape used as a vertical blade, in which each side of the upper surface facing the flat lower surface forming the seating surface protrudes outward in a plan view. The cutting edge portion and the straight line portion are formed, and each of the flat surfaces is formed so that the distance between the upper and lower surfaces gradually decreases from the central region of the upper surface reaching the boundary between the cutting edge portion and the straight line portion of each side to each corner portion. The feature is that an inclined surface is formed.

In addition, the throw-away tip according to the present invention is a substantially triangular plate-like throw-away tip used as a stand-up blade, in which each side of the upper surface facing the flat lower surface forming the seating surface is in plan view. The cutting edge is composed of a curved portion and a straight portion protruding outward, and the distance between the upper and lower surfaces gradually decreases from the central region of the upper surface that reaches the boundary between the curved portion and the straight portion of each side to each corner portion. Each of the inclined surfaces is formed by a boundary line extending from the central region of the upper surface toward each corner, and each of the inclined surfaces forms a first inclined surface reaching the curved portion and a second inclined surface reaching the straight portion. The first inclined surface is a flat surface, the second inclined surface is a convex curved surface, and the linear portion is formed in an arc shape in a side view.

Further, the ball end mill according to the present invention is a ball end mill to which a plurality of types of throw-away tips are attached, and one of the above-mentioned throw-away tips is vertically installed near the rotation axis of the tip ball-shaped portion. The cutting insert has an intermediate throw-away tip with a circular arc shape in side view and the outer throw-away tip with a straight or arcuate cutting edge in a side view, which are sequentially fixed vertically or horizontally. is there.

[0008]

[Action]

 This throw-away tip has a cutting edge that is configured as a convex curved surface that protrudes to the outside in plan view, so it is easy to process and can be molded. Since it is configured as an inclined surface in the lower surface direction, the side surface that forms the rake face can be mounted at a positive angle, the sharpness is high and the rigidity of the tip is high. Further, since the inclined surface is a flat surface and the inclined surface partitioned by the straight line portion constitutes the relief surface of the cutting edge portion, it is possible to prevent the tip of the cutting edge portion on the adjacent side from being involved in the cutting. The cutting edge part adjacent to is not damaged.

In addition, the throw-away tip according to the present invention is highly efficient in cutting because the entire upper surface of each side constitutes a cutting edge.

Further, in the ball end mill according to the present invention, the throw-away tip vertically placed near the rotation axis has a rake angle that is a positive angle or a relatively small negative angle, which improves the sharpness. Moreover, since the rigidity is high, the cutting blades can be arranged on the rotation axis, and the number of cutting blade tips that can be mounted on the whole is large, so that the number of blades can be increased.

[0011]

【Example】

 Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. 1 is a side view of a main part of the ball end mill according to this embodiment, FIG. 2 is a bottom view of the ball end mill in FIG. 1, FIG. 3 (A) is a plan view of a central cutting edge tip, and FIG. 3 (B) is the same view (A). Right side view, FIG. 4 (A) is a plan view of the intermediate cutting edge tip, (B) is a right side view of the same figure (A), FIG. 5 (A) is a plan view of the outer peripheral cutting edge tip, and (B). Is a right side view of FIG. 1 and 2, the tool body 9 of the ball end mill 8 has a body portion 9a having a substantially columnar shape, and the tip thereof is formed into a hemispherical ball-shaped portion 9b. A plurality of chip pockets 10a, 10b, 10c, 10d in the form of oval grooves are formed from the ball portion 9b to the body portion 9a.

A central cutting edge chip 12 whose one corner portion is located in the vicinity of the rotation axis is detachably attached to the one tip pocket 10a that reaches the rotation axis of the tool body 9. The intermediate cutting edge chips 13 and 13 and the outer peripheral cutting edge chips 14 and 14 are sequentially attached and detached in the same manner from the outer peripheral direction toward the rear (ball end mill base side). The center cutting edge tip 12 is right-handed. Similarly, an intermediate cutting edge tip 13 and an outer peripheral cutting edge tip 14 are sequentially attached to the other pocket tips 10b, 10c, 1od so as to be detachable. In this embodiment, each cutting edge tip is placed vertically with respect to the tool body 9.

As shown in FIG. 3, the central cutting edge tip 12 has a substantially triangular plate shape having three corner portions 12a, 12b, 12c and a peripheral side surface 16, and a central portion for fitting a fixing bolt. The stepped hole 17 is formed. Further, the upper surface 19 facing the flat lower surface 18 forming the seating surface on the tool body 9 has a substantially triangular planar shape in plan view which is substantially parallel to the lower surface from the stepped hole 17 to the vicinity of the center of each side. Boundary portions 20, 20, 20 are formed, and slopes are formed such that the thickness between the upper and lower surfaces gradually decreases from the peripheral ends of the respective boundary portions 20, 20, 20 and the cutting hole 17 to the corner portions 12 a, 12 b, 12 c, respectively. The surfaces 21a, 21b, 21c are each formed in a flat shape. Each inclined surface 21a, 21b, 21c is inclined, for example, about 7 degrees with respect to a surface parallel to the lower surface 18 (see FIG. 3B). Further, the peripheral side surface 16 is inclined outward by about 11 degrees with respect to the surface perpendicular to the lower surface 18. Moreover, each side of the upper surface 19 that forms a boundary between the peripheral side surface 16 of the chip 12 and each of the inclined surfaces 21a, 21b, and 21c has a cut line that forms a convex curve that is arcuate in a plan view with a connection point with the boundary portion 20 as a boundary. The blade 22 and the straight line portion 23 are respectively formed (see FIG. 11A).

Therefore, when the center cutting edge tip 12 is installed vertically on the tool body 9 of the ball end mill 8, the corner portion 12a is positioned near the rotation axis and the lower surface 18 is used as a seating surface on the ball-shaped portion 9b. When fixed, the peripheral side surface 16 side of the cutting edge 22 constitutes a rake surface, and the inclined surface 21a (21b, 21c) side constitutes a flank surface. In addition, in the side view shown in FIG. 3B, each side of the upper surface 19 of the central cutting edge tip 12 is inclined like a roof with the connection point with the boundary portion 20 as a boundary. Therefore, the inclined surface 21c (21a, 21b) partitioned by the straight line portion 23 constitutes a relief surface for the cutting edge 22. Accordingly, when cutting with the cutting edge 22, the adjacent cutting edge 22 adjacent to the straight line portion 23 of the side including the cutting edge 22 is prevented from being involved in the cutting and is not damaged. Moreover, when the central cutting edge tip 12 is attached, the inclined surface 21a constituting the flank surface is inclined toward the lower surface 18, so that the upper surface is compared to a chip formed in a plane parallel to the seating surface. The peripheral side surface 16 forming the rake face can be set to a positive angle instead of a negative angle. Therefore, the sharpness of the central cutting edge tip 12 is improved.

Further, as shown in FIG. 4, the intermediate cutting edge tip 13 has a substantially triangular plate shape having three corner portions 13 a, 13 b, 13 c each having a chamfered surface and a peripheral side surface 25. A stepped hole 26 for fitting a fixing bolt is bored in the central portion thereof. Further, a substantially ring-shaped flat surface 29 parallel to the lower surface 27 is provided on the upper surface 28 facing the flat lower surface 27 that forms a seating surface for the tool body 9, and the flat surface 29 has a stepped hole 26. The three peripheral intersections are partitioned by three arc-shaped sides projecting in the corner portions 13a, 13b, 13c of the chip 13, respectively. Further, each arcuate side of the substantially ring-shaped flat surface 29 is in contact with three sides of the upper surface 28 in plan view. In addition, a curved boundary line 30a (see FIG. 4B) in which the distance from the lower surface 27 gradually decreases from each intersection of the substantially ring-shaped plane 29 toward the midpoint of each corner portion 13a, 13b, 13c in plan view. , 30b, 30c extend from each other, and are opposed to each other such that the distance from the substantially ring-shaped flat surface 29 and each of the boundary lines 30a, 30b, 30c toward the respective sides of the upper surface 28 and the lower surface 27 becomes gradually smaller. The convex curved inclined surface 31a and the convex curved inclined surface 31b are formed respectively. Therefore, each side of the upper surface 28 has a large-diameter arc shape in a plan view (see FIG. 4 (A)) and is also formed in an arc shape in a side view (see FIG. 4 (B)), and the cutting edges 32 are respectively formed. Constitute. When the intermediate cutting edge tip 13 is vertically fixed to the tool body 9 with the lower surface 27 as a seating surface, the upper surface 28 serves as a flank and the peripheral side surface 25 serves as a rake surface.

As shown in FIG. 5, the outer peripheral cutting edge tip 14 has a substantially triangular plate shape having three corner portions 14 a, 14 b, 14 c and a peripheral side surface 34, each of which has a chamfered surface. A stepped hole 35 for fitting a fixing bolt is bored in the central portion thereof. Further, an upper surface 37 facing the lower surface 36 which is a seating surface for the tool body 9 forms a plane parallel to the lower surface 36, and each side of the upper surface 37 constitutes a cutting edge 38. When the outer peripheral cutting edge tip 14 is vertically fixed to the tool body 9 with the lower surface 36 as a seating surface, the upper surface 37 serves as a flank and the peripheral side surface 34 serves as a rake surface.

Since the present embodiment is configured as described above, as shown in FIG. 1, the central cutting edge chip 12, the intermediate cutting edge tip 13, and the outer peripheral cutting edge tip 14 are attached respectively. When the work material is cut by the ball end mill 8, the cutting is performed by the cutting edge of each chip. In particular, in the center cutting edge tip 12, cutting is performed by the convex curved cutting edge 22, and chips are guided by the rake face composed of the peripheral side surface 16 and are formed on the inner wall surface of the chip pocket 10a formed in two steps. It is curled, conveyed to the base side (outside) of the ball end mill 8 in the longitudinal direction, cut, and discharged. In this case, since the central cutting edge chip 12 is arranged as a vertical blade, the width of the upper surface 19 becomes the thickness of the central cutting edge tip 12, and its rigidity increases. This is particularly useful in a center cutting edge chip, where the tip of the cutting edge is generally located near the axis of rotation of the ball end mill, because the cutting edge is easily damaged. Moreover, the inclined surface 21a allows the cutting edge 22 to be mounted so that the rake angle is positive, so that sharpness is improved as compared with a chip having a flat upper surface.

Further, when cutting with the cutting edge 22, the inclined surface 21c (21b, 21a) which is partitioned by the straight line portion 23 of the side including the cutting edge 22 constitutes a relief surface, and is adjacent to this straight line portion 23. The adjacent cutting edge 22 avoids being involved in cutting and is not damaged. Therefore, when the corner is changed, the adjacent cutting edge 22 newly provided for cutting (forming the ridgeline of the inclined surface 21c (21b, 21a)) is chipped before the start of cutting. There is no such thing. Further, since the intermediate cutting edge tip 13 and the outer peripheral cutting edge tip 14 are also vertically arranged, their rigidity is high.

As described above, according to the present embodiment, the central cutting edge tip 12 has the cutting edge 22 configured as a convex curve in plan view, so that the machining is easy and can be molded. When used as a stand-up blade, the straight line portion 23 following each cutting edge 22 and its inclined surfaces 21c, 21b, 21a constitute the relief surface of each cutting edge 22, so that when cutting with one cutting edge 22, a straight line is formed. There is an advantage that the cutting edge 22 on the side adjacent to the portion 23 does not participate in chips and is not damaged. In addition, there is an advantage that the rigidity of the chip is increased.

Further, in the ball end mill 8 according to this embodiment, since the cutting edge chips 12, 13, 14 are vertically installed and attached as a stand-up blade, the rigidity of each cutting edge 12, 13, 14 is high. There is an advantage. Further, in the central cutting edge tip 12, the inclined surfaces 21c, 21a, 21b forming the flanks are inclined to the roof type in a side view of the central cutting edge tip 12, so that the rake angle when mounted as a vertical blade Can be set to a positive angle, and the sharpness can be improved accordingly, and the cutting edges 22 on the adjacent sides can be prevented from being damaged before use without participating in cutting. Moreover, since the central cutting edge tip 12 can be attached near the rotation axis of the ball end mill 8, the number of cutting edge tips that can be attached to the whole is large, and there is an advantage that the number of blades can be increased.

FIG. 6 shows a second embodiment of the central cutting edge tip 12 according to the present invention. The center cutting edge tip 40 according to the present embodiment is also configured to be right-handed, and the curved portion 41a and the straight portion 41b on the three sides of the upper surface 19 respectively configure the cutting blade 41. Further, the inclined surfaces 21a ', 21b', 21c 'are provided with curved boundary lines 42a, 42b, 42c from the cutting hole 17 toward the corner portions 12d, 12e, 12f, respectively. It is divided into a first inclined surface 43a partitioned by 41a and a second inclined surface 43b partitioned by a straight portion 42b. The first inclined surface 43a is a flat surface with a distance between the upper and lower surfaces gradually decreasing, and the second inclined surface 43b is a convex curved surface with the distance between the upper and lower surfaces decreasing gradually. Then, as shown in FIGS. 6B and 6C, each linear portion 41b forms a circular arc in a side view. Further, each intersection of the curved portion 41a and the straight portion 41b forming each of the corner portions 12d, 12e, 12f is formed in a curved shape on the lower surface 18 side so that the distance between the upper and lower surfaces becomes smaller. (See (B) and (C) in the figure). As a result, the corner portions 12d, 12e, 12f do not participate in the cutting when the cutting blade 41 cuts, and thus the curved portion 41a of the adjacent cutting blade 41 can be prevented from being damaged during cutting.

In the case of the central cutting edge tip 40 according to the present embodiment, unlike the first embodiment, the second inclined surface 43b having the straight line portion 41b as the ridge line is a convex curved surface and does not serve as a relief surface. However, since the corner portions 12d, 12e, 12f are inclined in a curved shape, it is possible to prevent the curved portion 41a of the adjacent cutting blade 41 from being damaged. In addition, since the entire edge of the upper surface 19 constitutes the cutting edge 41, there is an advantage that the cutting efficiency becomes high. In addition, when the throw-away tip is used as a vertical blade, the negative angle of the rake face can be set to a relatively small value due to the inclined surface that forms the upper surface, which also has the advantage of improving the sharpness.

In the center cutting edge tips 12 and 40 described above, the boundary portion 20 on the upper surface 19 does not necessarily have to be a triangular flat surface, but may be a boundary line that separates two adjacent inclined surfaces. . Further, although the central cutting edge tips 12 and 40 are right-handed in the first and second embodiments, they are not limited to this, and may be left-handed or non-handed. Further, such center cutting edge tips 12 and 40 are applicable not only to the ball end mill but also to other cutting tools such as a radius end mill. Further, in the above-described embodiment, the intermediate cutting edge tip 13 and the outer peripheral cutting edge tip 14 are vertically placed on the ball end mill 8, but instead of this, one or both tips are horizontally placed and horizontally placed. Good. Further, in the outer peripheral cutting edge tip 14, the cutting edge 38 is formed in a linear shape in a side view, but instead of this, it may be formed in a convex curved shape in a side view.

[0024]

[Effect of device]

 As described above, in the throw-away tip according to the present invention, each side of the upper surface is composed of the cutting edge portion and the straight line portion which are curved outwardly protruding in plan view, and the cutting edge portion and the straight line portion of each side are formed. Since the inclined surfaces are formed so that the distance between the upper and lower surfaces gradually decreases from the central region of the upper surface reaching the boundary between the upper and lower sides, the processing is easy and can be molded. In addition, when the throw-away tip is used as a vertical blade, the inclined surfaces adjacent to the inclined surfaces that form the flanks of each cutting edge form the flanks, so that the adjacent cutting edges that do not participate in cutting during cutting are It can prevent damage. Moreover, since the rake surface can be set to a positive angle due to the inclined surface forming the upper surface, the sharpness is improved accordingly. Further, in the throw-away tip according to the present invention, each side of the upper surface forms a cutting edge portion with a curved portion and a straight portion protruding outward in plan view, so that the entire side is a cutting edge. It is possible to obtain a chip with high cutting efficiency. Furthermore, the processing is easy, and it is also possible to perform molding, and when the throw-away tip is used as a vertical blade, the negative angle of the rake surface can be set to a relatively small value due to the inclined surface that forms the upper surface of the blade. There is also an advantage that the sharpness is improved accordingly. Further, in the ball end mill according to the present invention, a throw-away tip, in which a part or the whole of each side forms a cutting edge and an inclined surface is formed on the upper surface, is vertically arranged near the rotation axis of the tip ball-shaped portion. Therefore, there is an advantage that the throw-away tip has high rigidity. Moreover, since this throw-away tip can be attached near the axis of rotation of the ball end mill, the number of cutting edge chips that can be attached to the whole is large, which has the advantage of increasing the number of blades. Also, when installed as a vertical blade, the rake angle can be set to a positive angle or a relatively small negative angle, which has the advantage of improving the sharpness.

[Brief description of drawings]

FIG. 1 is a side view of the tip of a ball end mill according to an embodiment of the present invention.

FIG. 2 is a bottom view of the ball end mill of FIG.

3A is a plan view of a central cutting edge tip according to a first embodiment, and FIG. 3B is a side view.

4A is a plan view according to an embodiment of an intermediate cutting edge tip, and FIG. 4B is a side view.

5A is a plan view according to an embodiment of an outer peripheral cutting edge tip, and FIG. 5B is a side view.

FIG. 6A is a plan view of a central cutting edge tip according to a second embodiment, and FIGS. 6B and 6C are side views.

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

[Explanation of symbols]

8 ball end mill 9 tool body 12,40 center cutting edge tip 13 intermediate cutting edge tip 14 outer peripheral cutting edge tip 12a, 12b, 12c corner portion 12d, 12e, 12f corner portion 18 lower surface 19 upper surface 20 boundary portion 21a, 21b, 21c, 21a ', 21b', 21
c ′ inclined surface 22 cutting edge portion 23 linear portion 42a, 42b, 42c boundary line 43a first inclined surface 43b second inclined surface

Claims (3)

[Scope of utility model registration request] 1. In a throw-away tip of a substantially triangular plate shape used as a stand-up blade, each side of an upper surface facing a flat lower surface forming a seating surface has a curved line protruding outward in plan view. It consists of a straight section and a section,
From the central region of the upper surface reaching the boundary between the cutting edge portion and the straight line portion of each side to each corner portion, each of the flat inclined surface is formed so that the distance between the upper and lower surfaces thereof becomes gradually smaller. A throw-away tip to do. 2. A substantially triangular plate-shaped throw-away tip used as a vertical blade, wherein each side of an upper surface facing a flat lower surface forming a seating surface protrudes outward in a plan view and a linear portion. And a cutting edge consisting of, and inclined surfaces are formed such that the distance between the upper and lower surfaces gradually decreases from the central region of the upper surface reaching the boundary between the curved portion and the straight portion of each side to each corner portion, Each inclined surface is divided into a first inclined surface reaching the curved portion and a second inclined surface reaching the linear portion by a boundary line extending from the upper surface central region toward each corner portion,
A throw-away tip, wherein the first inclined surface is a flat surface, the second inclined surface is a convex curved surface, and the linear portion is formed in an arc shape in a side view. 3. A ball end mill having a plurality of types of throw-away tips attached thereto, wherein the throw-away tip according to claim 1 or 2 is vertically placed near the axis of rotation of the tip ball-shaped portion, and the cutting edge is viewed from the side. A ball end mill in which an arc-shaped throw-away tip and a cutting edge are straight lines in a side view or arc-shaped throw-away tips that are sequentially fixed vertically and horizontally.