KR950001370Y1 - Ball end mill - Google Patents

Abstract

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Description

Bowl End Mill

1 is a front view of a conventional bowl end mill.

FIG. 2 is a partial bottom view of the bowl end mill of FIG. 1 seen from arrow II-II of FIG.

3 is a side view of the first end bowl end mill.

4 is a front view of the bowl end mill according to the first embodiment of the present invention.

FIG. 5 is a bottom view of the FIG. 4 bowl end mill. FIG.

6 is a side view of the bowl end mill of FIG.

7 is an enlarged view of the upper end of the bowl end mill.

8 is an enlarged view of the sixth view of the bowl end mill of FIG.

9 is a plan view of the drawaway tip used in the FIG. 4 bowl end mill.

FIG. 10 is a side view of the drawaway tip of FIG. 9 as seen from the arrow Ⅹ-Ⅹ direction of FIG.

FIG. 11 is a side view of the FIG. 9 drawaway tip as seen from arrow XI-XI of FIG.

12 is a front view of a bowl end mill according to a second embodiment of the present invention.

FIG. 13 is a bottom view of the FIG. 12 bowl end mill. FIG.

14 is a side view of the bowl end mill.

FIG. 15 is an enlarged view of section V of the bowl end mill of FIG.

FIG. 16 is an enlarged view of part 14-VI of the bowl end mill.

FIG. 17 is a plan view of the first drawaway tip attached to the end mill body of the bowl end mill.

FIG. 18 is a side view of the first drawaway tip of FIG. 17 as viewed from the direction of arrows Ⅷ Ⅷ-Ⅹ 의 of FIG. 17;

FIG. 19 is another side view of the first drawaway tip of FIG. 17 viewed from the direction of arrows Ⅸ Ⅸ-Ⅹ 의 of FIG. 17;

20 is a plan view of a second drawaway tip attached to the end mill body of the bowl end mill.

FIG. 21 is a side view of the second drawaway tip of FIG. 20 viewed from the direction of arrows XI-XI XI of FIG. 20; FIG.

FIG. 22 is a side view of the second drawaway tip of FIG. 20 viewed from the direction of arrows XII-XII of FIG. 20;

Figure 23 is a front view of a bowl end mill according to a third embodiment of the present invention.

24 is a bottom view of the 23rd bowl end mill.

25 is a side view of the 23rd bowl end mill.

FIG. 26 is a partially enlarged front view of the 23rd bowl end mill. FIG.

27 is a plan view of a first drawaway tip attached to an end mill body of a 23rd bowl end mill.

28 is a plan view of a second drawaway tip attached to an end mill body of a 23rd bowl end mill;

29 is a front view of a bowl end mill according to a fourth embodiment of the present invention.

30 is a partial bottom view of the bowl end mill.

FIG. 31 is a side view of the FIG. 29 bowl end mill. FIG.

32 is a front view of a bowl end mill according to a fifth embodiment of the present invention.

FIG. 33 is a bottom view of the FIG. 32 bowl end mill. FIG.

FIG. 34 is a side view of the FIG. 32 bowl end mill. FIG.

35 is an enlarged view of the 엔드 엔드 Ⅹ V section of the bowl end mill of FIG.

36 is an enlarged view of the Ⅹ Ⅹ Ⅵ VI of the bowl end mill of FIG.

37 is a front view of a bowl end mill according to a sixth embodiment of the present invention.

FIG. 38 is a bottom view of the FIG. 37 bowl end mill. FIG.

FIG. 39 is a side view of the FIG. 37 bowl end mill. FIG.

40 is a front view of the bowl end mill according to the seventh embodiment of the present invention.

FIG. 41 is a bottom view of the FIG. 40 bowl end mill. FIG.

42 is a side view of the bowl end mill.

43 is a front view of the bowl end mill according to the eighth embodiment of the present invention.

FIG. 44 is a partial bottom view of the bowl end mill.

45 is a side view of the bowl end mill.

FIG. 46 is a view of the 43rd bowl end mill, as seen from the direction of arrows Ⅹ LVI- Ⅹ LVI in FIG. 43;

47 is a front view of the bowl end mill according to the ninth embodiment of the present invention.

48 is a side view of the 47th bowl end mill.

49 is a cross sectional view of the 47th line 선 L Ⅸ-Ⅹ L ..

The present invention relates to a bowl end mill having at least one drawaway tip (hereinafter referred to as a tip) detachably attached to the end mill body.

1 to 3 show a conventional bowl end mill as described in Japanese Patent Laid-Open No. 59-21725.

This bowl end mill usually consists of a cylindrical end mill body 100 and a drawaway tip 102 detachably attached to the front end of the end mill body 100.

The drawaway tip 102 is composed of a plate formed by a side surface, which is an outer peripheral surface located between the front side 104 and the rear side 104 and the front side 104 and the rear side 106.

A pair of opposing notches 108 that are approximately V-shaped are formed on the outer periphery to cut the outer periphery to form a pair of opposite sides 110.

Each of the V-shaped notches 108 extends from the front face 104 to the back face 106 and has a pair of opposing first and second wall surfaces 112. Formed by 114.

The first wall surface 112 is flat and perpendicular to the front face 104, and the second wall surface 114 is convex when viewed in a direction perpendicular to the first wall surface 112.

The side surfaces 110 are approximately one quarter circular when viewed in a direction perpendicular to the front face 104, and the front face 104 and notches () are formed to form the cutting edge 116 which is convex in shape when viewed in the same direction. The second wall surface 114, which is the curved surface of 108, intersects.

One of the cutting edges 116 of the drawaway tip 102 is divided at the cutting position so as to extend outwardly toward the front end and the outer circumferential surface of the end mill body 100, and near the axis (0) of the end mill body 100. The distal end portion 116a of the divided cutting edge 116 arranged is a convex curve when viewed in the axial direction of the end mill body 100.

In the bowl end mill as described above, the distal end portion 116a of the divided cutting edge 116 first starts to engage the workpiece, and then the other portion of the cutting edge 116 is connected to the end mill body 100. As it rotates, it begins to engage the workpiece.

Therefore, the cutting load gradually increases as the cutting operation proceeds, and at that time, a large load is not applied to the divided cutting edge 116, so that the damage of the cutting edge 116 is reduced.

However, in this conventional bowl end mill, the flat first wall 112 of the V-shaped notch 108 prevents the chip from being ejected smoothly during the cutting operation and causes the chip to jam.

It is therefore an object of the present invention to provide a bowl end mill having a greater chip ejection capacity as well as greater strength at divided cutting edges.

According to the present invention, it comprises an end mill body having a rotating shaft, a head and a body, and a first drawaway tip detachably attached to the head of the end mill body, the first tip having a front and a rear face. At least one short second corner, each of which has at least one approximately arc-shaped first corner portion, each of which is used as a major cutting edge, each arc being roughly arc-shaped; Section, the main cutting edge has a tip located at one end thereof, intersects the short cutting edge in such a way that the leading edge and the short cutting edge form an obtuse angle, and the front face is used as a slope for the cutting edge and the short cutting edge and the leading edge Having an edge located adjacent to the edge, which is a convex curved surface which is inclined toward the back towards the short cutting edge, with the leading end of the major cutting edge The first tip is placed on the end mill body in such a manner that it is located adjacent to the axis of the body and the short cutting edge extends from the distal end toward the rear end of the end mill body when viewed in a direction substantially perpendicular to the front side. A bowl end mill is provided.

Various embodiments of the present invention will be described with reference to FIGS. 4 through 49 where like parts or parts are designated by like reference numerals.

4 to 11, the bowl end mill according to the first embodiment of the present invention includes an end mill body 10 having an approximately arc-shaped head and a body having an approximately circular arc shape. The body is suitable for being firmly fixed to the mechanical spindle so that the end mill body 10 can rotate about the axis 0.

A chip pocket 12 having a wall surface facing in the rotational direction of the end mill body 10 is formed at the head of the end mill body 10.

A recess 14 having a flat bottom surface is formed on the wall, and the drawaway tip 16 is detachably mounted to the recess 14.

As shown in FIGS. 9-11, the drawaway tip 16 alternates between the front face 18 and the rear face 20 positioned parallel to the front face 18 and between the front face 18 and the rear face 20. It consists of a pair of roughly inner-shaped plates formed by two pairs of first side surfaces 22 and second side surfaces 24, each of which is inclined toward the interior of the plate in a direction away from the front face 18. .

The two first sides 22 as well as the two second sides 24 face each other such that they are symmetrical about the axis of the plate or drawaway tip.

Each of the first side surfaces 22 is a convex curved surface that becomes a quarter circle when viewed in a direction perpendicular to the front face 18, and has an arcuate side surface portion 22 and a side center portion 22a at each end. It consists of the side front end part 22b which is planar located in both sides of the side center part 22a, and the side rear end part 22c so that it may contact | connect.

Each second side 24 is planar and very short compared to the first side 24.

Each first side and the second side intersect at an obtuse angle.

A pair of convex curved main cutting edges 26 formed by the intersection of each of the drawaway tip front face 18 and the first side face, and the intersection of one of the front face 18 and the second side face 24, respectively. It holds a pair of short cutting edges 28 formed by.

Each major cutting edge 26 has an intersecting tip of one of the short cutting edges 28 and a trailing edge intersecting with the other short cutting edge 28, and the cutting edge center 26a and the cutting edge center 26a. It consists of the front-end | tip part 26b and the rear end part 26c located in both sides of ().

The angle formed by the short cutting edge 28 and the line in contact with the main cutting edge 26 at the distal end portion is an obtuse angle.

The front face 18 is used as an inclined surface for the cutting edge, and the edge face 30 located adjacent to each of the short cutting edge 28 and the short cutting edge 28 and the rear end 26b and the rear end 26c. Is a convex arc shape inclined toward the back surface 20 toward the short cutting edge 28, whereby the leading end 26b and the trailing edge 26c of each major cutting edge 26 are convex when viewed from the side. to be.

Furthermore, since the side end 22b and the side rear end 22c, which are the planes of the first side surface 22, are inclined toward the inside of the plate in a direction away from the front face 18, the tip end 26b of the main cutting edge 26. And rear end 26c are also convex curves in plan view.

The plate has a central hole 32 formed therethrough.

The drawaway tip 16 is received in the recess 14 and is divided in the cutting position so that one of the main cutting edges 26 is slightly extended beyond the tip of the end mill body 10 to the outside and the main cutting edge ( By means of a set screw 34 passing through the central hole 32 so that the back surface 20 coincides with the flat bottom surface of the recess 14 in such a way that the axial tilt angle θ for 26 is positive. Removably fixed to the end mill body (10).

As shown in FIG. 7, the tip portion 26b of the main cutting edge 26 is located adjacent to the axis 0 of the end mill body 10 and is short at the tip crossing the major cutting edge 26. The cutting edge 28 extends beyond the axis 0 of the end mill body 10 toward the rear end of the end mill body 10.

Moreover, the drawaway tip 16 is positioned in place by a pair of planar side tip portions 22b and side trailing edges 22c contacting the flat portion 14a formed on the wall surface of the recess 14, respectively. .

In the bowl end mill described above, since the tip portion 26b of the main cutting edge 26 is a convex curve when viewed in the axial direction of the end mill body 10, the cutting load increases gradually as the cutting operation proceeds. Therefore, a large cutting load is not applied to the main cutting edge 26 at one time.

Moreover, since the drawaway tip 16 does not include a wall, such as the flat wall 112 in the prior art drawaway tip 102, the bowl end mill provides better chip evacuation compared to conventional bowl end mills. Have

Moreover, since the angle formed by the short cutting edge 28 and the line contacting the main cutting edge 26 at the tip end is an obtuse angle, the main cutting edge 26 has increased strength even at the tip end.

12 to 20 show a bowl end mill according to the second embodiment of the present invention, which is different from the bowl end mill described above, and the pair of recesses having the end mill body 10 formed in a substantially hemispherical shape at the front end thereof ( 44 and 46, wherein the recess 44 is located adjacent to the axis 0 of the end mill body 10, and the recess 46 is formed from the shaft of the end mill body 10. Radially spaced to face outward from 0).

The first drawaway tip 48 is received in the recess 44 and detachably fixed by the set screw 34, while the second drawaway tip 50 is received in the recess 46 and the set screw. It is detachably fixed by (not shown).

As shown in Figs. 17-19, the first drawaway tip 48 is basically similar to the structure of the drawaway tip 16 of the first embodiment, but the two first sides 52 are plated. It is also symmetrical about the longitudinally extending central plane of the tip, and the two second sides 54 are symmetrical about the transversely extending central plane.

Each of the first side surfaces 52 is a convex curved surface that forms a quarter circle in plan view, and both ends of the side central portions 52a are in contact with the side central portions 52a having an arc shape and the side central portions 52a on both sides thereof. The side end portion 52b and the side rear end portion 52c, which are planar surfaces, are formed.

And, the edge face 60 of the front face 58 located adjacent to each second side face 54 longer than the edge face 30 of the tip 16 in the first embodiment is the back face toward the second side face 54. It is a convex curved surface that slopes toward (62).

In this structure, each of the major cutting edges 56 is a curved line having an arc shape as viewed from the direction perpendicular to the front face 58, and is composed of the cutting edge center portion 56a, the tip portion 56b, and the rear end portion 56c. The leading and trailing ends are each convex, not only in the sides but also in the plane.

And the angle (alpha) ₁ of the line yarn which contact | connects the main cutting edge 56 by the short cutting edge 63 and the front end is an obtuse angle.

As shown in Figs. 20 to 22, the second tip 50 is similar to the structure of the first tip 48, but the side center portion 64a and the side tip portion formed by the arc-shaped curved surface, respectively ( 64b) and opposing one-sided sides 64 composed of lateral rear end portions 64c, which are planes extending from the lateral central portions 64a so that the ends abut.

Furthermore, as shown in FIGS. 21 and 22, each side is positioned adjacent to the front face 68 and extends approximately perpendicular to the front face 68 and the bottom slopes toward the inside of the tip away from the face face 68. Is formed by.

The edge face 66 of the front face 68 located adjacent to each second side face 70 is a convex curved face that slopes toward the back face 72 toward the second side face 70.

Therefore, each major cutting edge 74 is a curve which is substantially arcuate when viewed from the direction perpendicular to the front face 68, and is composed of the cutting edge center portion 74a, the western end 74b and the rear end 74c. .

The cutting edge center portion 74a and the tip portion 74b are substantially arc-shaped in plan view, and the rear end portion 74c is a straight line in plan view.

Moreover, the tip portion 74c intersects at an obtuse angle α ₂ of one of the short cutting edges 76, and the rear end 74c intersects at substantially right angles with the other short cutting edge 76.

As in the case of the first embodiment, the first tip 48 is divided at the lower cutting position of the main cutting edge 56 and the axial inclination angle θ ₁ for the divided main cutting edge 56 becomes positive. It is arranged in such a way.

The tip 56b of the main cutting edge 56 is positioned adjacent to the axis 0 of the end mill body 10, and the short cutting edge 62 crossing the main cutting edge 56 at the tip is an end mill body. It extends beyond the axis 0 of the end mill body 10 toward the rear end of (10).

Furthermore, the recess 44 includes two flat portions 44a formed on the wall surface, and the first tip 48 has a pair of flat side tip portions 52b and side trailing portions 52c, respectively. In place by contacting 44a).

On the other hand, the second tip 50 is divided in the cutting position in the cutting position such that one of the main cutting edges 74 extends along the front end of the end mill body 10 and in the axial direction for the divided main cutting edges 74. The back surface 72 is received in the recess 46 in such a manner that the warp work becomes positive so as to coincide with the flat bottom surface of the recess 46.

As shown in FIG. 15 and FIG. 16, the tip portion 74b of the main cutting blade 74 is radially spaced from the axis 0 of the end mill body 10 toward the outside of the end mill body 10. It is positioned to be erased.

As a result the first and second tips 48. The major cutting edge and the short cutting edge of (50) show an approximate S shape as viewed from the side view.

Furthermore, the recess 46 includes two flat portions 46a formed on the wall surface, and the second tip 50 has one of the planar side end portions 64c and one of the second side surfaces 70 respectively. It is disposed in place by contacting the flat portion 46a.

In the bowl end mill as described above, not only the tip portion 74a of the main cutting edge 74 of the second tip 50 but also the tip portion 56b of the main cutting edge 56 of the first tip 48 has been seen in a side view. Because of the large convex curves, the cutting forces gradually increase as the cutting operation proceeds, so that no large cutting forces are applied to the cutting edge of each tip at a time.

Furthermore, each tip 48. 50 does not include walls such as the flat wall 112 of the conventional tip 102, so the bowl end mill has better chip evacuation performance.

Moreover, angle (α ₁ ). Since α ₂ is an obtuse angle, the main cutting edge 56 is used. 74 has increased strength even at the tip.

Furthermore, in the second embodiment, the first and second tips (48). The arrangement of (50) is such that when the end mill body 10 rotates about the axis 0 of the end mill body 10, the main cutting edge 56 of the first tip 48 is the second tip 50. The major cutting edge 74 may be modified to form an approximately hemispherical shape having a diameter larger than the approximately hemispherical shape that can be formed.

In particular, the first and second tips 48. 50 may be modified to form an approximately hemispherical contour having a larger diameter than the approximately hemispherical contour that the second tip 50 major cutting edge 74 can form.

In particular, the first and second tips 48. Reference numeral 50 is a hemispherical shape in which the cutting edge center portion 74a and the tip portion 74b, which are arcs of the second tip 50 and the major cutting edge 74, are formed by the main cutting edge 56 of the first tip 48. A hemispherical shape having a radius of curvature of 0.1 mm smaller than the external shape is formed, and the rear end portion 74c, which is a straight line of the main cutting edge 74 of the second tip 50, is the main cutting edge of the first tip 48 ( It may be arranged to form a cylindrical contour having a diameter of at most 0.1 mm smaller than the maximum diameter of the contour formed by 56).

In the particular arrangement described above, the major cutting edge 56 of the first tip 48 is primarily involved in cutting, thus obtaining a flexible hemispherical recess that does not have a step formed therein, thus such a bowl end mill. Silver can be used successfully for cutting such as die cutting.

As for the second tip 50, only the rear end portion 74c, which is a straight line located on the rear surface of the end mill body 10 from one point of the main cutting edge 56 of the first tip 48, which forms the largest circular contour, is mainly used. Involved in cutting.

23 to 28 show a bowl end mill according to a third embodiment of the present invention.

First and second tip 80. In addition to (82), this bowl end mill has a third and fourth tip (84). (86).

First and second tip 80. Although 82 is generally similar in structure to the first and second tips 48 and 50 of the second embodiment, the first and second tips 80 and 82 of this embodiment are respectively Short cutting edge 88 at this tip. (90) and major cutting edge (92). Each angle α ₃ formed by 94. (α ₄ ) is larger than the angles α ₁ and α ₂ of the first and second tips 48 and 50 in the second embodiment.

Therefore, the strength of the primary cutting edges of the first and second tips 80 and 82 at the distal end thereof is improved.

Furthermore, in the second tip 82 of this embodiment, the edge face 96 of the front face 98 positioned adjacent the short cutting edge 92 is directed towards the short cutting edge 90, ie, with the short cutting edge 90. It is a convex curved surface which is inclined toward the rear surface 150 toward the front end portion of the main cutting edge 94 as well as the front end portion of the major cutting edge 94 abuts.

The third and fourth tips 84 and 86 are rectangular in shape and similar in structure to each other.

Each of the third and fourth tips 84 and 86 is divided at the cutting position so that one of the cutting edges serves as the outer peripheral cutting edges 152 and 154, respectively. 84), the divided cutting edges of (86) and the divided cutting edges of the first and second tips (80) and (82) are seen in the circumferential direction of the end mill body (10) in the series of axial directions of the end mill body (10). It is detachably attached to the front end of the end mill body 10 so as to be.

The axial inclination angle θ ₁ for the first and second tips 80, 82, as well as the axial inclination angle θ ₂ for the third and fourth tips 84, 86 are positive. Is installed.

The installation of the additional third and fourth tips 84, 86 described above allows the bowl end mill to be used for deep cutting operations.

Furthermore, in this embodiment the second tip may be omitted.

29 to 31 show a bowl end mill according to a fourth embodiment of the present invention, and the first and second tips 80 and 82 of the third embodiment are the first and second portions of the second embodiment. Replaced with second tips 48, 50, and the third and fourth tips 84, 86 are axial tilt angles θ1 for the first and second tips 80, 82, although This positive is different from the third embodiment in that it is arranged to have a negative axial inclination angle ₃ .

In this embodiment, the torsional load is applied by the third and fourth tips 84 and 86, and the torsional load is applied by the first and second tips 48 and 50. This torsional load is dissipated by each other because it is different from the losing direction.

As a result, the bowl end mill is less susceptible to vibrations and vibrations during cutting, so that the finished surface is actually improved.

As described above, the axial inclination angle θ ₁ for the first and second tips 82 and 82 is preferably in the range of 3 ° to 10 °, and the third and fourth tips 84, ( The axial tilt angle θ ₃ for 86) is preferably in the range of −10 ° to 0 °.

If the axial inclination angle θ ₁ for the first and second tips 80, 82 is less than 3 °, the cutting load is actually increased.

On the other hand, if the axial inclination angle θ ₁ exceeds 10 °, the amount of back metal (H) in the concave portion of the front end of the end mill body is severely reduced, thus lowering the rigidity of the bowl end.

When the axial inclination angle θ _{3 of} the third and fourth tips 84 and 86 is more than 0 °, the torsional load generated by the third and fourth tips 84 and 86 is It is not sufficient to rule out the torsional load caused by the first and second tips.

On the other hand, if the axial inclination angle θ ₃ is less than −10 °, the cutting forces due to the third and fourth tips 84 and 86 become larger, thereby adversely affecting the cutting operation. Exerted.

32 to 36 show a bowl end mill according to a fifth embodiment of the present invention, which is composed of one tip 160 as in the case of the first embodiment.

However, the tip 160 has a front surface 162 and a rear surface 164 and an arcuate side surface 166 that is a quarter-circle, and the first and second side surfaces which are planes intersecting with each other at an angle slightly smaller than 90 °. 168 and 170, which is formed of a substantially fan-shaped plate.

Edges where the arcuate side surface 166 and the first side surface 168 intersect with each other are removed to form a short side.

The tip 160 is formed by an arc-shaped cutting edge 172 formed by the front face 162 and the arcuate side surface 166, and an arc at the distal end thereof formed by an intersection of the front face 162 and the short side. A short cutting edge 174 that intersects the shape cutting edge 172.

The edge face 176 of the front face 162 positioned adjacent the short cutting edge 174 is a convex curved surface that slopes toward the short cutting edge 174 toward the back surface 166.

And the tip 160 is such that the arcuate cutting edge 172 is divided in the cutting position such that the tip portion 172a of the arcuate cutting edge 172 is located adjacent to the axis 0 of the end mill body 10. It is accommodated in the recess 178 and detachably fixed by the fixing screw 180.

As in the case of other embodiments, the short cutting edge 174 extends beyond the axis 0 of the end mill body 10 toward the rear foot end of the end mill body 10.

In addition, the concave portion 178 is composed of first and second wall surfaces 182, 184 extending perpendicular to each other, the first wall surface 182 extends in the axial direction of the EdMil body 10, The two wall surface 184 extends in the radial direction of the end mill body 10.

The tip 160 is positioned in position by bringing the first and second side surfaces 168 and 170 which are planar surfaces into contact with the first and second wall surfaces 182 and 184, respectively.

In this structure, the tip 160 is absolutely lifted during the cutting operation because the tip 160 is received between two first and second wall surfaces 182, 184 that intersect each other perpendicularly. It is prevented, and thus the precision of cutting can be further improved.

37 to 39 show a bowl end mill according to a sixth embodiment different from the fifth embodiment in that the second tip 50, which is usually in the form of a tauner, is added as in the case of the second embodiment.

40 to 42 show that the third and fourth tips 84 and 86, which are rectangular in shape as in the fourth embodiment, are additionally attached to the end mill body so that a bowl end mill is used for deep cutting operations. In other respects, the bowl end mill according to the seventh embodiment of the present invention is different from the sixth embodiment.

43 to 46 show a bowl end mill according to the eighth embodiment of the present invention, which is generally similar to the second embodiment.

The chip pocket 40 for the first tip 48 has a second wall surface 200b facing in a direction opposite to the rotational direction of the end mill body 10 and the first wall surface 200a on which the recess 44 is formed. It consists of.

As shown in FIG. 44, the second wall surface 200b of the chip pocket 40 is formed therein and is inclined to the front end of the end mill body 10 in the rotational direction of the end mill body 10. 202.

In this structure, chips generated during the cutting operation are guided flexibly along the inclined tip portion 202, so that the chip ejection performance can be substantially improved.

47 to 49 show a bowl end mill according to the ninth embodiment of the present invention which is generally similar to the first embodiment.

However, in this embodiment, the convex curved edge surface 30 is formed by the cylindrical surface, and the position of the tip 16 is deformed.

In particular, the tip 16 has an end mill body when the axis P of the cylinder forming the cylindrical surface is viewed in a direction perpendicular to the reference plane (JIS BO170; No.204) with respect to the main cutting edge 26. It is positioned in such a way that it is inclined at an inclination angle β between 15 ° and 50 ° with respect to the axis 0 of 10).

The reference plane is defined as a plane perpendicular to the main direction of motion of the main cutting edge 26.

If the inclination angle is smaller than 15 °, the blade tip angle δ at the tip which is the convex curve of the main cutting edge 26 is severely reduced, and thus the cutting edge is liable to be damaged.

On the other hand, if the inclination angle exceeds 50 °, the precision of cutting decreases, and furthermore, the cutting load suddenly increases.

The advantages of this embodiment are illustrated in detail with reference to the following examples.

In particular, two bowl end mills, each having a 25 mm outer diameter and a 4 mm thick tip, were prepared, and the inclination angle β for the convex curved portion and the clearance angle γ for the tip were adjusted to the cutting precision. In order to demonstrate the effect of these angles on the various, the spherical shape of the recess bottom was processed by the bowl end mill described above.

The axial tilt angle for the tip is 5 ° for one of the bowl end mills referred to below as sample 1, while the axial tilt angle is 10 ° for the other bowl end mill referred to as sample 2.

Therefore, with respect to the bowl end mill described above, the deviation of the hemispherical shape formed on the arc-shaped cutting edge from the hemispherical shape formed by the distal end of the cutting edge is a calculation.

The results are shown in Table 1, where a positive value means that the contour formed by the tip of the cutting edge is excluded from the contour formed by the arc-shaped cutting edge, while a negative value indicates the tip. The outer shape formed by means that it is contained in the outer shape formed by the arc-shaped cutting edge.

In this example, the tip is the axis of the curved surface passing through an edge where the arcuate surface and the plane merge.

TABLE 1

As can be seen from Table 1, if the inclination angle is 60 °, the deviation is excessively excessive, and thus the precision is lowered.

In other words, the allowable deviation for this type of bowl end mill is usually in the range of ± 20 μm.

However, in the bowl end mill of the present invention, since the inclination angle is in the range of 15 ° to 50 °, the strength of the cutting edge and the chip ejection performance are further improved, and high precision can be obtained.

Moreover, in the case where the inclination angle exceeds 60 °, the deviation cannot be reduced within the range of ± 20 μm even though the curved surface is compensated for the curvature of the edge surface.

Many modifications and variations of the present invention are possible in light of the above teaching.

Therefore, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described.

Claims (7)

An end mill body 10 having a rotating shaft, a head and a body, and a first drawway tip 16 detachably attached to the head of the end mill body, wherein the head of the end mill body is a chip. A recess 14 is formed to receive the pocket 12 and the drawaway tip, and the first drawaway tip has a front side 18 and a back side 20 and two pairs of first side surfaces alternately located between the front side and the back side. And a front face formed of a plate formed by a second side face 24, the front face being used as a major cutting edge 26 that is substantially arc-shaped, respectively, intersecting with each of the first side face and the second side face. One approximately arc-shaped first corner portion and at least one short second edge portion, each of which is used as a short cutting edge 28, wherein the major cutting edge has a tip portion 26b located at one end and a tip and a short edge. Intersect the short cutting edge to make the cutting edge obtuse, The front face is used as an inclined surface for the main cutting edge and the short cutting edge, and has an edge surface 30 positioned adjacent to the leading edge and the short cutting edge of the main cutting edge, and the edge surface is the back side toward the short cutting edge. A convex curved surface which is inclined toward the end mill, wherein the first drawaway tip of the main cutting edge is positioned adjacent to the axis (0) of the end mill body, and the short cutting edge is the A bowl end mill, wherein the bowl end mill is disposed in such a manner as to extend from the tip portion beyond the axis of the end mill body toward the rear end portion of the end mill body when viewed in a direction substantially perpendicular to the one front side. The tip end portion of the main cutting edge with respect to the end mill body, wherein the second drawaway tip having the same configuration as the first drawaway tip is radially outward from the axis of the end mill body. Bowl end mill, characterized in that additionally arranged at intervals from the first drawaway tip. The end mill according to claim 1 or 2, having at least one cutting edge and detachably attached to the end mill body at a distance from the first or second drawaway tip described above towards the back of the end mill body (10). Further constitute at least one outer drawaway tip (84), 86, said outer drawaway tip is divided in the outer cutting position so that at least one cutting edge is used as the outer cutting edge (152), (154) And the cutting edge used as the outer cutting edge and the main cutting edge of the first or second drawaway tip are located in a circumferential direction of the end mill body so as to extend in the axial direction of the end mill body. 3. The main cutting edge of the second drawaway tip according to claim 2, wherein the main cutting edge of the first drawaway tip is rotated when the first and second drawaway tips are rotated about the axis of the end mill body. A bowl end mill, characterized in that it is arranged to form an approximately hemispherical outline having a larger diameter than the approximately hemispherical outline to be formed. 4. The axial inclination angle 0 ₁ for the first or second drawaway tip is positive, and at least one of the axial inclination angles θ ₃ for the outer drawaway tip is zero. Bowl end mill, characterized in that not greater than °. The axial inclination angle for the first or second drawaway tip is in the range of 3 to 10 degrees, and the axial inclination angle for the at least one outer drawaway tip is in the range of -10 to 0 degrees. Bowl end mill, characterized in that. 2. The bowl end mill according to claim 1, wherein the plate of the first drawaway tip is substantially fan-shaped.