JP3474550B2 - End mill - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill suitable for use in performing cutting by moving an end mill body stepwise in the axial direction, and a method for manufacturing the same.

[0002]

2. Description of the Related Art When shoulder milling or grooving a workpiece with an end mill, the depth of the shoulder or groove to be machined depends on the axial direction of the cutting edge provided with the outer peripheral cutting edge on the tip side of the end mill body. When it is deeper than the cutting edge length, the end mill main body is once rotated to be fed in a direction intersecting the axis to machine the depth of the cutting edge length, and then the end mill main body is moved in the axial direction, and then again. The cutting process is performed stepwise by repeating operations such as feeding in the direction intersecting the axis, and at this time, the outer diameter of the shank part is on the rear end side of the end mill body like a general end mill. Is larger than the outer diameter of the outer peripheral cutting edge of the cutting edge portion on the tip side, the shank portion interferes with the workpiece, and thus, for example, Japanese Patent Laid-Open No. 11-58120 or 2000. No. 334615, the outer diameter of the shank portion is made smaller than the outer diameter of the outer peripheral cutting edge of the cutting blade portion, or the neck portion between the cutting blade portion and the shank portion has a smaller diameter than the outer diameter of the outer peripheral cutting edge. An end mill provided with is proposed.

However, as shown in FIG. 9, simply by making the outer diameter of the outer peripheral cutting edge 3 of the cutting edge portion 2 on the front end side of the end mill body 1 smaller than the outer diameter of the shank portion 4 on the rear end side and the neck portion,
When the end mill body 1 is gradually moved in the direction of the axis O to perform cutting, the machined surface P of the workpiece W when the end mill body 1 is machined at a position on the rear end side of the axis O,
By the rear end portion of the outer peripheral cutting blade 3 of the end mill body 1 located on the tip side, at the joint with the processing surface Q when processing is performed at a position where the one-step end mill body 1 is on the tip side in the axis O direction, A streak R may be formed along the feeding direction F of the end mill body 1. Therefore, in order to prevent such a line R from being formed at the joint between the processing surfaces P and Q, the above-mentioned JP-A-11-58120 and JP-A-200120.
In Japanese Patent Laid-Open No. 0-334615, the rear end portion of the outer peripheral cutting edge 3 forms a 1/4 arc shape or a polygonal line shape in a rotation locus around the axis O so as to move toward the axis O side toward the rear end side. It is proposed to form.

[0004]

However, even in an end mill in which the rotation locus of the rear end portion of the outer peripheral cutting edge 3 is directed toward the axis O side as the rear end side is moved toward the rear end side, the end mill of this rear end portion When the outer peripheral flank continuous with the outer peripheral cutting edge 3 is a straight second surface which is linear in a cross section orthogonal to the axis O, when it is attempted to secure a large cutting edge angle of the outer peripheral cutting edge 3, this outer peripheral flank The relief amount on the rear side of the end mill rotation direction becomes small and interferes with the machining surfaces P and Q, and the above-described streak R may be attached to the joint, while conversely, it is attempted to secure this relief amount sufficiently. When the peripheral clearance angle is increased, the cutting edge angle becomes smaller, the strength of the peripheral cutting edge 3 is impaired, and the peripheral cutting edge 3 may be damaged. Further, in this way, in order to form the rotation locus of the outer peripheral cutting edge 3 so that it goes toward the axis O side toward the rear end side at the rear end portion,
After grinding the outer peripheral flank on the tip side with a grindstone to form an outer peripheral cutting edge 3 having a constant outer diameter on the side edge portion on the side of the end mill rotation direction, the outer peripheral flank is formed on the outer peripheral flank at the rear end of the cutting edge 2. Cylindrical grinding must be performed to form the outer peripheral cutting edge 3 in a 1/4 arc shape or a polygonal line shape so that the rear end of the outer peripheral cutting edge 3 faces the axis O side. Of course, when the rotation locus of the rear end portion of the outer peripheral cutting edge 3 is made into a quarter arc shape, the tip end of the quarter arc formed by this cylindrical grinding is made to have a constant outer diameter. If the rear end of the outer peripheral cutting edge 3 on the leading end side is not exactly aligned,
A step is generated between both ends, and a line R is formed at the joint between the processing surfaces P and Q.

The present invention has been made under such a background, and particularly in the case where the end mill main body is moved stepwise in the axial direction for cutting as described above,
A first object of the present invention is to provide an end mill capable of more surely preventing the formation of streaks on a machined surface, and further to provide a manufacturing method capable of manufacturing such an end mill more easily. The second purpose is to do so.

[0006]

[Means for Solving the Problems]
In order to achieve the first object described above, the present invention provides an axial rotation.
A peripheral cutting edge is provided on the tip side of the end mill body that rotates
Cutting edge part is formed and the rear end side is the shank part.
The outer diameter of the outer peripheral cutting edge is the outer diameter of the shank portion,
Or the outer diameter of the neck connecting the shank and the cutting edge
It is an end mill that is larger than the cutting edge
At the end, the locus of rotation of the outer peripheral cutting edge around the axis
To On a plane containing the axis, Outer peripheral cutting edge
Smoothly on the rotation trajectory of Touch and Toward the rear end
Formed so as to face the axis side, and its outer periphery
Make a convex curve in the cross-section of the flank perpendicular to the axis
As an eccentric clearance surface, its outer clearance angle should be the outside of the cutting edge tip side.
It is characterized by making it larger than the clearance angle. Therefore,
With the end mill configured in this way,
The rotation trajectory of the part On the plane containing the axis Outside the tip side
Smoothly follows the rotation path of the peripheral cutting edge Touch and Toward the rear end
Since it is formed so as to face the axis line,
Domming body is moved stepwise in the direction of its axis for cutting.
It is possible to prevent the formation of streaks on the machined surface even if it is machined
Of course, at the rear end of this peripheral cutting edge,
The flank is an eccentric flank, and the outer peripheral clearance angle is the cutting edge.
Since it is larger than the peripheral clearance angle on the tip side of the part,
It is necessary to secure sufficient tip angle to maintain the strength of the outer cutting edge.
On the other hand, on the rear side of the outer cutting edge in the end mill rotation direction,
It is possible to secure a sufficient amount of relief on the outer flank, and
Surely prevent streaks from forming on the machined surface
can do.

In order to achieve the above second object,
The end mill of the present invention, the outer peripheral cutting edge, the outer peripheral surface of the grindstone rotated around the center line, while making sliding contact with the portion to be the outer peripheral flank of the cutting edge portion, the grindstone and the end mill body By relatively moving in the axial direction along the outer peripheral cutting edge to grind the outer peripheral flank, the outer peripheral flank is formed at a side ridge on the end mill rotation direction side of the outer peripheral flank, At the rear end portion, while relatively moving the grindstone and the end mill body in the axial direction, the center line of the grindstone and the axis line of the end mill body are relatively close to each other, so that the rear end portion Is formed so that the rotation locus of the outer peripheral cutting edge in the direction of the axis becomes closer to the rear end of the end mill body .
With this, the outer peripheral cutting edge as described above can be formed by grinding the outer peripheral flank in one step from the front end side to the rear end portion of the cutting edge portion with the above grindstone, and thus manufacturing the end mill. The manufacturing cost can be reduced easily and efficiently, and the outer peripheral cutting edge can be formed smoothly from the front end side to the rear end portion without causing a step or the like.

[0008]

1 to 4 show one embodiment of the end mill of the present invention. In the present embodiment, the end mill main body 11 is formed of a hard material such as cemented carbide into a substantially cylindrical shape centered on the axis O, and the tip side (left side in FIG. 1) serves as the cutting edge portion 12 and A shank portion 13 having a substantially constant outer diameter d is provided on the rear end side (right side in FIG. 1) of the cutting edge portion 12. Here, on the outer periphery of the cutting edge portion 12, a pair of spiral twists are formed around the axis O toward the rear side in the end mill rotation direction T at the time of cutting processing from the tip end toward the rear end side in the axis O direction. The chip discharge grooves 14 and 14 are formed on opposite sides of the axis O, and the outer peripheral cutting edge 15 is formed on the ridge line portion of the wall surface of the chip discharge grooves 14 and 14 facing the end mill rotation direction T side. Are formed respectively. Therefore,
The wall surface of the chip discharge groove 14 serves as the rake face 16 of the outer peripheral cutting edge 15, and the outer peripheral surface portion of the cutting edge portion 12 extending rearward from the outer peripheral cutting edge 15 in the end mill rotation direction T is the outer peripheral flank surface 17. Therefore, the outer peripheral cutting edge 15 and the outer peripheral flank 17 are formed in a spiral shape that matches the twist of the chip discharge groove 14.

Here, the outer peripheral cutting edge 15 of the cutting edge portion 12,
The rotation locus 15 makes about the axis O except for a slight range of the rear end portion 12a of the cutting edge portion 12 except for the rear end portion 12a.
The portion closer to the tip end than the above forms a cylindrical surface with the axis O as the center, and the outer diameter of this cylindrical surface, that is, the cutting edge portion 1
The outer diameter D of the outer peripheral cutting edge 15 on the 2 tip side is slightly larger than the outer diameter d of the shank portion 13.
It should be noted that instead of making the outer diameter d of the shank portion 13 substantially constant and making the outer diameter D of the outer peripheral cutting edge 15 on the tip side of the cutting edge portion 12 larger than this outer diameter d, as shown in FIG. The outer diameter of the shank portion 13 is larger than or equal to the outer diameter D, and the neck portion 18 is provided between the shank portion 13 and the cutting edge portion 12 with a predetermined length. The outer diameter D of the outer peripheral cutting edge 15 may be larger than the outer diameter e of the neck portion 18. Further, at the tip of the cutting edge portion 12, bottom blades 19, 19 are formed extending from the tips of the outer peripheral cutting edges 15, 15 to the inner peripheral side of the end mill body 11, that is, the axis O side.

On the other hand, the outer peripheral flank 17 on the tip side of the cutting edge portion 12 has a substantially arcuate convex curve having a center eccentric from the axis O as shown in FIG. 2 in a cross section orthogonal to the axis O. However, it is formed so as to gradually retreat toward the axis O side from the outer peripheral cutting edge 15 toward the rear side in the end mill rotation direction T, whereby the outer peripheral cutting edge 1 is formed.
The outer peripheral clearance angle (second eccentric angle) θ is given to 5,
Therefore, on the outer peripheral flank 17 on the tip side of the cutting edge portion 12, the clearance amount X from the outer peripheral cutting edge 15 at the position of the arc of the length L centering on the axis O is given by X = L · tan θ. In addition, the outer peripheral surface of the cutting edge portion 12 further rearward in the end mill rotation direction T than the outer peripheral flank 17 is further retracted to the one-step axis O side from the outer peripheral flank 17, and then the axis O
It circulates around and is connected to the rake face 16 of the outer peripheral cutting edge 15 adjacent to the rear side of the end mill rotation direction T.

At the rear end portion 12a of the cutting edge portion 12, the rotation locus of the outer peripheral cutting edge 15a around the axis O at the rear end portion 12a is the axis O as shown in FIG. On the included plane, the outer peripheral cutting edge 1 on the above-mentioned tip side
5 is formed so as to smoothly contact the rotation locus of No. 5 and to move toward the rear end side toward the axis O side. In particular, in the present embodiment, a convex arc that smoothly contacts the outer peripheral cutting edge 15 on the front end side at the contact point S. Are formed so as to form a convex curve, and the radius of curvature formed by this convex curve is the above-mentioned rear end portion 12a.
Is larger than the length in the direction of the axis O. However,
In the present embodiment, in the extremely short range 12b in which the chip discharge groove 14 at the rearmost end of the cutting edge portion 12a cuts to the outer peripheral side, the rotation locus of the outer peripheral cutting edge 15 has a convex curve as described above. It is formed so as to be parallel to the axis O or slightly cut toward the rear end side without drawing. In addition, instead of forming the rotation locus of the outer peripheral cutting edge 15a at the rear end portion 12a from the contact point S to reach the range 12b in the convex curve shape as shown in FIG. Only the outer peripheral cutting edge 15 on the front end side is smoothly contacted with the outer peripheral cutting edge 15 toward the rear end side, and has a convex curve shape toward the axis O side, and on the rear end side more smoothly contact with the convex curve and toward the rear end side. Accordingly, it may be formed so as to reach the above range 12b as a straight line inclined toward the axis O side.

Further, in the present embodiment, of the outer peripheral flank 17 of the outer peripheral cutting edge 15, the rear end portion 12a of this cutting edge portion 12 is provided.
The outer peripheral flank 17a also has a substantially arcuate convex curve having a center eccentric from the axis O in a cross section orthogonal to the axis O similarly to the tip side, and the rear side in the end mill rotation direction T from the outer peripheral cutting edge 15a. As you go to the above axis O
It is an eccentric clearance surface which gradually recedes toward the side, and the peripheral clearance angle α given to the peripheral clearance surface 17a is larger than the peripheral clearance angle θ on the tip side. Here, the outer peripheral clearance surface 17a, to which a large outer peripheral clearance angle α is given in the rear end portion 12a, extends from the outer peripheral cutting edge 15a of the rear end portion 12a, which has a rotational locus of a convex curve, to the tip side substantially parallel to the axis O. As shown in FIG. 3A, the outer peripheral flank 17 is formed in a substantially parallelogram shape with respect to the outer peripheral flank 17 extending spirally. Therefore, the outer peripheral flank 17a is located closer to the tip side than the contact point S. In the formed portion, as shown in FIG. 4A, an outer peripheral flank 17 having a small outer peripheral clearance angle θ is formed on the outer peripheral cutting edge 15 side, and further on the rear side in the end mill rotation direction T than this. The outer peripheral clearance surface 17a having a large outer peripheral clearance angle α is formed. Further, at the rear end portion 12a of the cutting edge portion 12 on the rear end side of the contact point S, as shown in FIG.
An outer peripheral clearance angle β larger than the outer peripheral clearance angle θ of the outer peripheral clearance surface 17 on the tip side is given.

Here, in one embodiment of the manufacturing method of the present invention for manufacturing the end mill having the above-mentioned structure, the outer peripheral cutting edge 15 is thus formed at the rear end 12a of the cutting edge 12.
As described above, the rotation trajectory of a is formed so as to smoothly contact the outer peripheral cutting edge 15 on the front end side, and toward the axis O side toward the rear end side, and the outer peripheral clearance angle α of the outer peripheral flank 17a,
In order to make β larger than the tip side, in the step of grinding the outer peripheral flank 17 to form the outer peripheral cutting edge 15 when manufacturing the end mill, the grinding stone is applied to the end mill body at the rear end 12a of the cutting edge portion 12. The axis O of 11 is made to approach. That is, in a general manufacturing process of an end mill, as shown in FIG. 6, an angular grindstone 21 having an outer peripheral surface 21a having a tapered shape is used, with its center line (not shown) directed toward the axis O of the end mill body 11. Is arranged at a distance from the axis O so as to extend as
While rotating 1 around the center line, the outer peripheral surface 21a is brought into slidable contact with the portion to be the outer peripheral flank 17 of the end mill body 11, and when the outer peripheral cutting edge 15 has a spiral shape, the end mill is matched with this spiral. While rotating the main body 11, the angular grindstone 21 and the end mill main body 11 are relatively moved in the direction of the axis O along the outer peripheral cutting edge 15 and the outer peripheral flank 17 is ground to form the outer peripheral clearance. The outer peripheral cutting edge 15 is formed at the side ridge of the surface 17 on the side of the end mill rotation direction T, that is, the ridge line intersecting with the rake face 16. At this time, the center line of the angular grindstone 21 and the end mill body 11 are formed. The distance from the axis O is constant except for the rearmost end of the cutting edge portion 12 where the chip discharge groove 14 rises.

On the other hand, in the manufacturing method of the present embodiment and the end mill manufactured by the manufacturing method, as shown in FIG. 5, the outer diameter D of the outer peripheral cutting edge 15 is set.
On the front end side of the cutting edge portion 12 where the angle O is constant, both the center line of the angular grindstone 21 and the axis O of the end mill main body 11 are kept constant, and both are aligned along the outer peripheral cutting edge 15.
Direction, the angular grindstone 21 is gradually moved so that the center line of the angular grindstone 21 approaches the axis O of the end mill body 11 when it reaches the rear end 12a of the cutting edge 12. As a result, the rotation locus of the outer peripheral cutting edge 15a at the rear end portion 12a is formed so as to smoothly contact the outer peripheral cutting edge 15 on the front end side and move toward the rear end side toward the axis O side as described above. And the outer peripheral flank 17 at the rear end 12a
a is also a peripheral clearance angle α, which is larger than the peripheral clearance angle θ on the tip side.
It can be β. At this time, if the approaching amount of the angular grindstone 21 is set to increase as the angular grindstone 21 relatively moves toward the rear end side in the direction of the axis O, as shown in FIG. If the rotation locus of the blade 15a can be formed in a convex curve shape as a whole, and the rear end side of the contact point S has a constant approaching amount, the range from the rear end side of the contact point S to the above range. The rotation locus of the outer peripheral cutting edge 15a can be formed to extend linearly up to 12b. However, also in the present embodiment, at the rear end of the cutting edge portion 12 where the chip discharge groove 14 is cut up, the distance between the center line and the axis O is again set so that the angular grindstone 21 does not interfere with the shank portion 13 and the neck portion 18. Of the angular grindstone 21 and the end mill main body 11 by making the distance constant or conversely separating them from each other.
And must be moved relative to each other, so that in the extremely short range 12b at the rear end, the rotation locus of the outer peripheral cutting edge 15 is parallel to the axis O or slightly slightly toward the rear end as described above. It will be formed so as to cut up to the side.

Therefore, in the end mill thus manufactured, the rear end portion 12a of the cutting edge portion 12 is first
As described above, the rotation locus of the outer peripheral cutting edge 15a smoothly connects to the outer peripheral cutting edge 15 on the front end side at the contact point S and moves backward toward the rear end side toward the inner peripheral side toward the axis O side of the end mill body 11. Therefore, the contact S or the like is not bent at an angle or a step or the like is generated at the contact S, and the bent portion or the step does not form a line on the machined surface. Then, the outer peripheral clearance surface 17a, which is continuous with the outer peripheral cutting edge 15a whose rotation locus of the rear end portion 12a extends toward the axis O, is an eccentric clearance surface, and the outer peripheral clearance angles α, β are on the distal side relative to this. It is set to be larger than the outer peripheral clearance angle θ of the surface 15, so that the edge angle of the outer peripheral cutting edge 15a of the rear end portion 12a can be secured to maintain sufficient strength.
In the outer peripheral flank 17a located at the joint between the machining surfaces as described above, a large amount of clearance can be secured on the rear side in the end mill rotation direction T, so that the outer peripheral flank 17a is It is possible to prevent a situation in which a line or a scratch is generated at the joint due to the interference with the processed surface. Further, even if the outer peripheral cutting edge 15 is worn, if the amount of radial wear with respect to the axis O is the same, the outer peripheral cutting edge 15 of the rear end portion 12a is
In a, the wear width in the circumferential direction can be reduced by the amount that the outer peripheral clearance angle β is larger than the outer peripheral clearance angle θ of the outer peripheral cutting edge on the tip side, and the rotation of the outer peripheral cutting edge 15a continuous to the outer peripheral clearance surface 17a. An excellent machined surface can be maintained in combination with the fact that the locus is formed toward the rear end side toward the axis O side.

Further, in the method of manufacturing the end mill of the present embodiment described above and the end mill of the embodiment manufactured by the manufacturing method, the outer peripheral cutting edge at the rear end 12a of the cutting edge 12 having such a rotation locus. 15a is slidably contacted with the outer peripheral surface 21a of the angular grindstone 21 to the portion to be the outer peripheral flank 17, and is relatively moved in the direction of the axis O with respect to the end mill body 11 to grind the outer peripheral flank 17, thereby cutting the outer periphery. When the blade 15 is sharpened, the center line of the angular grindstone 21 and the end mill body 11 are, as described above, in the portion of the outer peripheral cutting edge 15 on the rear end 12a side.
Is formed by relatively approaching the axis O of the outer peripheral cutting edge, and therefore, the outer peripheral cutting edge 15 on the tip side is continuously formed by the one-step grinding with the angular grindstone 21 for sharpening the single outer peripheral cutting edge 15. Outer peripheral cutting edge 1 of lever rear end 12a
5a can be formed. However, in this respect, in the conventional end mill in which the rotation locus of the rear end portion of the outer peripheral cutting edge is formed into a polygonal line shape or a 1/4 circular arc shape, the rear end portion is ground after the normal outer peripheral cutting edge is formed. It requires two steps of machining, especially in the case where the rotation locus is arcuate, and when the contact points of the outer peripheral cutting edge in both steps do not exactly match and a step occurs, a streak is formed on the machined surface only by that. In contrast to this, according to the present embodiment, the manufacturing process of the end mill can be simplified by the one-step grinding process as described above, and, of course, the outer circumference can be obtained without causing a step or the like. The cutting blades 15 and 15a can be surely smoothly connected to each other, so that an end mill in which no streaks are formed on the machined surface can be relatively easily manufactured at low cost.

In the end mill of this embodiment, as shown in FIG.
In the range 12b at the rearmost end of the rear end portion 12a of the cutting edge portion 12 as shown in Fig. 2, the angular grindstone 21 does not interfere with the shank portion 13 and the neck portion 18 and the end mill body 1
In order to make relative movement with respect to 1, the rear end of the outer peripheral cutting edge 15a in the rear end portion 12a is also formed so as to be parallel to the axis O in the range 12b or slightly cut up toward the outer peripheral side toward the rear end side. However, the size of the angular grindstone 21 and the outer diameters d and e of the shank portion 13 and the neck portion 18
When the above-mentioned interference is small due to the above, for example, as shown in FIG. 8, the portion where the outer peripheral flank 17a is cut up by the angular grindstone 21 does not reach the outer peripheral cutting edge 15a, and the rear end of the cutting edge portion 12 is prevented. The outer peripheral cutting edge 15a may be formed so as to face the axis O side toward the rear end side in the entire portion 12a. Further, in manufacturing the end mill as described above in the present embodiment, the angular grindstone 21 having the tapered outer peripheral surface 21a is arranged so that its center line extends in the direction of the axis O of the end mill body 11. The outer peripheral flank 17 is ground by the abrasive grain layer formed on the outer peripheral surface 21a of the lever, but the center line is formed by using a flat grindstone whose outer peripheral surface is a cylindrical surface parallel to the center line. Grinding may be performed by inclining with respect to the axis O, or a cup-shaped grindstone having an outer peripheral end face perpendicular or tapered to the center line may be used.

[0018]

As described above, according to the end mill of the present invention, the rotation locus of the outer peripheral cutting edge on the rear end side of the cutting edge portion is smoothly contacted to the front end side and directed toward the rear end side. According to the above, it is formed toward the axis side,
Even when the end mill is moved stepwise in the axial direction to form a machined surface by increasing the outer peripheral clearance angle as an eccentric clearance surface on the rear end side and making the outer peripheral clearance angle larger than that on the front end side, the cutting edge strength is improved. While maintaining, it is possible to more reliably prevent the generation of streaks at the joints between the processed surfaces, and it is possible to form a smooth and excellent processed surface.
Further, according to the end mill of the present invention, such an outer peripheral cutting edge can be formed by one-step grinding process using an angular grindstone for each line, and thus an end mill having the above-described excellent effects can be easily manufactured. Therefore, the processing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side view schematically showing an embodiment of the present invention.

FIG. 2 is an enlarged front view of the embodiment shown in FIG. 1 as seen from the tip side (however, the bottom blade 19 and the like are not shown).

FIG. 3 is a rear end portion 1 of the cutting edge portion 12 of the embodiment shown in FIG.
(A) Side view showing around 2a, (b) Outer peripheral cutting edge 15,1
It is a figure which shows the rotation locus | trajectory of 5a.

FIG. 4A is a sectional view taken along line YY in FIG.
(B) It is a ZZ sectional view in FIG.

5 is an outer peripheral flank surface 17, 17 of the embodiment shown in FIG.
It is a figure which shows the case where a is grind | pulverized and a peripheral cutting edge 15 and 15a is formed.

FIG. 6 is a diagram showing a case where an outer peripheral flank 17 of a general end mill is ground to form an outer peripheral cutting edge 15.

FIG. 7 is a side view schematically showing a modified example of the embodiment shown in FIG.

8 is a side view showing the periphery of the rear end portion 12a of the cutting edge portion 12 in another modified example of the embodiment shown in FIG.
It is a figure which shows the rotation locus | trajectory of the outer peripheral cutting edges 15 and 15a.

FIG. 9 is a diagram showing a state in which a streak R is generated at a joint between the processing surfaces P and Q.

[Explanation of symbols]

11 End Mill Main Body 12 Cutting Blade 12a Cutting Edge 12a Rear End 13 Shank 14 Chip Discharge Groove 15 Peripheral Cutting Blade 15a Outer Perimeter Cutting Blade 17 at Rear End 12a Outer Perimeter Flank 17a Outer Perimeter Flank 18 at Rear End 12a Neck 21 Angular whetstone O End mill main body 11 axis T End mill rotation direction D Outer diameter of outer peripheral cutting edge d Outer diameter of shank 13 e Outer diameter of neck 18 θ Outer peripheral clearance angle of outer peripheral flank 17 Figure 3 (a) Outer peripheral clearance angle of the outer peripheral clearance surface 17a in the YY cross section of the outer peripheral clearance angle of the outer peripheral clearance surface 17a in the ZZ cross section of FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-238216 (JP, A) Registered utility model 3041243 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23C 5 / 10 B24B 3/06

Claims (2)

(57) [Claims] 1. A cutting edge portion having an outer peripheral cutting edge is formed on a front end side of an end mill body rotated about an axis and a rear end side is a shank portion, and an outer diameter of the outer peripheral cutting edge is the shank portion. The outer diameter of, or an end mill that is larger than the outer diameter of the neck portion connecting the shank portion and the cutting edge portion, in the rear end portion of the cutting edge portion, around the axis of the outer peripheral cutting edge The rotation trajectory is on the plane containing the axis.
And is formed so as to be smoothly in contact with the rotation locus of the outer peripheral cutting edge on the front end side , and to face the axial line side toward the rear end side , and the outer peripheral flank thereof is orthogonal to the axial line. An end mill having an eccentric clearance surface having a convex curve in a cross section, the outer peripheral clearance angle being larger than the outer peripheral clearance angle on the tip side of the cutting edge portion. 2. The outer peripheral cutting edge is configured such that the outer peripheral surface of a grindstone rotated about a center line is brought into sliding contact with a portion which becomes an outer peripheral flank of the cutting edge part, and the grindstone and the end mill body are formed. By relatively moving in the axial direction along the outer peripheral cutting edge to grind the outer peripheral flank, the outer peripheral flank is formed at the side ridge on the end mill rotation direction side of the outer peripheral flank, and after the cutting edge portion. In the end portion, while relatively moving the grindstone and the end mill body in the axial direction, by bringing the center line of the grindstone and the axis line of the end mill body relatively close to each other, in the rear end portion The end mill according to claim 1, wherein the rotation locus of the outer peripheral cutting edge is formed so as to be directed toward the axial line side toward the rear end side of the end mill body.