JP3335401B2 - 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 in which a corner portion between an outer peripheral edge and a bottom edge is rounded or chamfered.

[0002]

2. Description of the Related Art An end mill as shown in FIGS. 6 to 9 is known as a cutting tool used for shoulder milling or grooving of a work material. In this end mill, four spiral chip discharge grooves 2 are formed on the outer periphery of a substantially cylindrical tool body 1, and these chip discharge grooves 2 are directed in the tool rotation direction (the direction of arrow T in FIG. 8). An outer peripheral blade 4 is formed at an intersection ridgeline between the groove wall surface 2a and the outer peripheral flank 3 of the tool body 1, and the chip discharge groove 2
Are formed, and bottom blades 7 are formed at the intersection ridges of the groove wall surfaces 5a of the gashes 5 facing the tool rotation direction and the flank surfaces 6 of the tip end of the tool body 1. At the same time as the side cutting with the outer peripheral blade 4, the bottom blade 7
The cutting of the end face such as the bottom face of the groove to be processed is performed. That is, in this conventional example, the groove wall surface 2a
Is the rake face of the outer peripheral blade 4, and the groove wall surface 5 a is
It is a rake face. In addition, what is indicated by reference numeral O in the drawing is the rotation center axis of the tool main body 1.

In such an end mill, the corner portion 8 where the outer peripheral blade 4 and the bottom blade 7 intersect has a high cutting speed, applies a large cutting load, and tends to concentrate cutting heat during cutting. This is a part where wear and breakage are most likely to occur, and if the two cutting edges 4 and 7 continue to intersect at a sharp angle in such a corner portion 8, wear and breakage are further promoted and tool life is increased. Will be significantly shortened. Therefore, conventionally, a chamfering process is performed on an intersection ridge portion between the outer peripheral flank surface 3 and the tip flank surface 6, and the cross ridge portion is inclined at a constant gradient in the axial direction and the radial direction of the tool body 1 to form the two cutting edges. The corner 8 also intersects both the bottom blade 7 and the outer peripheral blade 4 at an obtuse angle when viewed from the side of the wall surface 2a of the chip discharge groove 2 by shaving off the inclined surface at an obtuse angle intersecting at 4,7. The corner portion 8 is formed in a straight line to prevent loss of the corner portion 8.

Here, a corner flank 9 formed behind the corner 8 in the tool rotation direction by the chamfering process.
In the same manner as the outer peripheral flank 3 and the tip flank 6,
It is necessary to secure an appropriate clearance in the radial direction and the axial direction of the tool body 1 with respect to the rotation locus of the corner portion 8 around the axis O. Therefore, the corner portions flank 9 toward the corner portion 8 in the tool rotation direction rear side, the rotation locus to Q ₁ peripheral cutting edge 4 in the bottom view of the tip end side in the axial direction of the tool body 1 as shown in FIG. 8 , And retreats toward the tool inner peripheral side, and as shown in FIG. 9, when viewed from the side in the radial direction of the tool main body 1, toward the axial base end side of the tool main body 1 with respect to the rotation locus Q ₂ of the bottom blade 7. It is formed on a receding inclined surface having a constant gradient.

[0005]

In the case where the corner flank 9 is formed as an inclined surface inclined at a constant gradient with respect to the radial direction of the tool body 1 as described above, the corner flank 9 is formed. becomes to be arranged in the direction of the chord with respect to the arc of the rotational locus to Q ₁ the peripheral cutting edge 4 is drawn as shown in FIG. Therefore, in order to secure a sufficient clearance over the entire surface of the corner flank 9, first, the end 9a of the corner flank 9 on the rear side in the tool rotation direction and the outer edge 4 of the outer peripheral blade 4 are formed. as relief amount required between the rotation locus Q ₁ is being secured, it must form the corner portion flank 9 by scraping the intersecting ridgeline portion.

However, when the corner flank 9 is formed in this way, it becomes difficult to secure a sufficient thickness behind the corner 8 in the tool rotation direction, and the corner 8 is formed The intersection angle between the groove wall surface 2a of the chip discharge groove 2 and the corner flank 9 intersecting with each other, that is, the cutting edge angle at the corner portion 8 becomes small, and the problem occurs that the cutting edge strength at the corner portion 8 decreases. However, since the corner portion 8 is a portion where wear and breakage are likely to occur as described above, if the edge strength is reduced in such a corner portion 8 as described above, the above-described effect by performing the chamfering process is reduced. It is inevitable that the life of the tool is significantly shortened.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent a decrease in edge strength at a corner while securing a sufficient clearance at a corner flank. Accordingly, an object of the present invention is to provide an end mill having a long tool life.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and achieve the above object, the present invention provides a chip discharge groove on the outer periphery of a tool body which is rotated around an axis from its distal end toward its proximal end. Is formed, an outer peripheral edge is formed at an intersection ridge portion of a groove wall surface of the chip discharge groove facing the tool rotation direction and an outer peripheral flank surface of the outer periphery of the tool body, and the groove wall surface and a tip flank surface of a tip of the tool main body are formed. An end mill in which a bottom edge is formed at an intersection ridge line portion of the end mill, wherein a corner portion where the outer peripheral edge and the bottom edge intersect has a substantially arc shape or a chamfered shape.
A corner flank is formed at the rear of the corner in the tool rotation direction, and the corner flank is formed on the inner circumferential side and the base end of the tool as it moves rearward in the tool rotation direction with respect to the rotation locus around the axis of the corner. The tool body is formed by a convex curved surface which gradually retreats to the side and is curved at least in a circumferential direction of the tool main body.

[0009]

According to the end mill having such a configuration, the flank of the corner portion disposed rearward in the tool rotation direction of the corner portion is formed as a convex curved surface which is curved in the circumferential direction of the tool body. As compared with the case where the corner flank is formed as a slope inclined at a constant gradient with respect to the radial direction of the tool body, the amount of flank at the end of the corner flank on the rear side in the tool rotation direction is the same. In this case, the thickness behind the corner portion can be increased, and the edge angle at the corner portion can be increased. Conversely, if the cutting edge angle is the same, it is possible to set a large amount of clearance at the corner flank. Therefore,
According to the end mill having the above configuration, it is possible to maintain the edge strength at the corner portion while giving a sufficient clearance to the flank of the corner portion, and it is possible to suppress the occurrence of wear and chipping.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In this embodiment, however, the basic configuration of the end mill is not different from that of the conventional end mill. Therefore, the overall view corresponding to FIG. 6 of the description of the conventional example is omitted, and the same configuration as that of the conventional end mill is omitted. Are assigned the same reference numerals. Now, in the embodiment shown in these figures, the tool body 1 is formed of a hard material such as a cemented carbide and has a substantially cylindrical shape, and the outer periphery of a tip portion thereof has a spirally twisted four chip discharge groove. 2 ... from the tip of the tool body 1 to the base end,
Further, they are formed so as to be equidistant from each other in the circumferential direction of the tool main body 1.

At the intersection ridge line between the groove wall surface 2a of the chip discharge grooves 2 facing the tool rotation direction and the outer peripheral flank 3 on the outer periphery of the tool body 1, a spiral is formed in accordance with the twist of the chip discharge grooves 2. An outer peripheral blade 4 twisted in a shape is formed. A gask 5 is formed at the tip end of each of the chip discharge grooves 2... The groove wall 5 a of the gash 5 connected to the groove wall 2 a and facing the tool rotation direction, and the tip of the tip of the tool body 1 escapes. The tool body 1 is located at the intersection ridge line with the surface 6.
The bottom blade 7 is formed to extend radially from the tip of the bottom blade. Further, a corner portion 11 is formed on the outer periphery of the tip end of the tool body 1 where the outer peripheral edge 4 and the bottom edge 7 intersect. The corner flank 12 is formed so as to be continuous with the outer peripheral flank 3 and the tip flank 6.

In this embodiment, as shown in FIG. 2, the corner portion 11 is formed to have a substantially 1/4 arc shape when viewed from the groove wall surface 2a (5a) side. The corner flank 12 is also formed so as to form a 1/4 arc shape in a cross section including the axis O of the tool body 1 in accordance with the corner 11. The center angle of the arc formed by the corner portion 11 as viewed from the groove wall surface 2a side is appropriately set according to the shape of the end mill, but is in the range of 75 ° to 120 ° with respect to the straight line parallel to the axis O. Is preferably set to. As shown in FIG. 3, the corner flank 12 forms a convex curved surface that bulges toward the outer periphery of the tool as shown in FIG.
As progressively retracted into the peripheral side tool relative to axis O of the rotation locus to Q _1, and the rotation of the axis O of the end cutting edge 7 while drawing a convex curve swell to a tool tip side as shown in FIG. 5 It is formed so as to gradually retreat to the tool base end side relative to the path Q _2. Therefore, the corner flank 12 gradually retreats toward the tool inner peripheral side and the tool base end side with respect to the rotation trajectory around the axis O of the corner part 11 as it goes backward from the corner part 11 in the tool rotation direction, And it is formed in the convex curved surface which curves in the circumferential direction of the tool main body 1 and the direction of the axis O.

In the end mill according to the present embodiment, the corner flank 12 draws a convex curved surface curved in the circumferential direction of the tool body 1 as described above, and the corner flank 12 extends from the corner 11 toward the rear in the tool rotation direction. Since it is formed so as to gradually recede toward the inner circumferential side of the tool with respect to the rotation locus about the axis O, the flank 9 of the corner portion is formed on the tool body 1 as in a conventional end mill shown in FIGS. If the escape amount of the end 12a (see FIG. 3) on the rear side in the tool rotation direction is the same as that formed on the inclined surface inclined at a constant gradient with respect to the radial direction of the The corner flank 12 between 12a is formed closer to the outer periphery of the tool than the corner flank 9 of the conventional end mill. For this reason, in the end mill of the present embodiment, even if the relief amount at the end 12a is the same, the rear wall thickness of the corner portion 11 can be made larger than that of the conventional end mill, and the corner portion 11 The angle of intersection between the groove wall surface 2a (5a) and the corner flank 12, that is, the cutting edge angle at the corner 11, can be increased.

Therefore, according to the present embodiment, while ensuring a necessary and sufficient clearance in the corner flank 12, the corner 11
Can provide a high cutting edge strength, thereby making it possible to suppress the occurrence of wear, chipping, and the like in the corner portion 11 where a large cutting load is applied and cutting heat is easily concentrated. Conversely, when the blade edge strength is set in the same manner, it is possible to increase the clearance of the corner flank 12 as compared with the conventional end mill. Therefore, in such a case, it is possible to suppress the contact between the processed surface of the work material and the corner flank surface 12 to reduce the cutting resistance.

Further, in this embodiment, the corner flank 12 is formed so as to have a convex curved surface which is also curved in the axial direction of the tool body 1 as shown in FIG. For this reason, as compared with the conventional case where the corner flank 9 has an inclined surface having a constant gradient also in the axial direction, a sufficient clearance is provided to the corner flank 12 in the axial direction while the corner flank 12 is provided.
Of the cutting edge can be improved.

Further, in this embodiment, the corner flank 12 is formed so as to form a 1/4 arc shape in a cross section including the axis O of the tool main body 1, and accordingly, the corner 11 also has a groove wall surface 2a. (5a) It is formed so as to form a quarter-arc shape when viewed from the side. That is, in the conventional end mill, the corner flank 9 is chamfered to form the corner 8, whereas in the present embodiment, the corner flank 12 is so-called rounded. As a result, the outer peripheral blade 4 and the bottom blade 7 and the outer peripheral flank 3 and the tip flank 6 are each formed into a quarter-arc
1 and the corner portion flank 12 so as to be smoothly connected. Therefore, according to the present embodiment,
A large cutting load and cutting heat concentrated on the corner portion 11 and the corner flank 12 can be quickly diffused, thereby also suppressing the occurrence of wear and chipping. In addition, since the corner flank 12 is formed in an arc-shaped cross section, there is an advantage that the thickness at the outer periphery of the distal end portion of the tool main body 1 can be increased to improve the tool rigidity.

In this embodiment, as described above, the corner flank 12 is formed by performing a rounding process so that the cross section thereof has a quarter-arc shape, but the corner flank 12 is formed by the tool body 1. As long as the end mill is formed into a convex curved surface curved in the circumferential direction, its cross section becomes a straight line that intersects the outer peripheral flank 3 and the tip flank 6 at an obtuse angle, similarly to the conventional end mill described above. Flank 3 and flank 6
The corner flank 12 may be formed by performing chamfering on the intersection ridge line portion. In this case, as in the case shown in FIG. 7, the corner portion 11 also has the groove wall surface 2a (5a).
When viewed from the side, both the outer peripheral blade 4 and the bottom blade 7 are formed in a straight line that intersects at an obtuse angle. In this embodiment,
Although the corner flank 12 is a convex curved surface that is also curved in the axial direction of the tool body 1, it may be formed so as to be inclined at a constant gradient in the axial direction. However, in this case as well, it goes without saying that the corner flank 12 should be formed as a convex curved surface that curves in the circumferential direction of the tool body 1.

[0018]

As described above, according to the present invention,
The corner flank formed in the tool rotation direction behind the corner where the outer peripheral blade and the bottom blade intersect is formed into a convex curved surface that curves in the circumferential direction of the tool body, so that the corner flank is necessary and sufficient. It is possible to increase the thickness of the rear portion of the corner portion, increase the edge angle at the corner portion, and improve the edge strength while securing a sufficient escape amount. And, by this, it is possible to prevent a situation in which abrasion remarkably progresses or a cutting edge is chipped in a corner portion where a large cutting load is applied and cutting heat is liable to be concentrated, and the tool life is shortened. Extension can be achieved.

[Brief description of the drawings]

FIG. 1 is a front view of a tool body 1 according to an embodiment of the present invention, as viewed from a distal end side.

FIG. 2 is an enlarged view as viewed in a direction A in FIG. 1;

FIG. 3 is a view as viewed in a direction B in FIG. 2;

FIG. 4 is a diagram viewed from a direction C in FIG. 2;

FIG. 5 is a diagram viewed in a direction D in FIG. 3;

FIG. 6 is a side view showing a conventional end mill.

FIG. 7 is an enlarged view as viewed in a direction E in FIG. 6;

FIG. 8 is a view as viewed in a direction F in FIG. 7;

FIG. 9 is a diagram viewed in a G direction in FIG. 7;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 tool body 2 chip discharge groove 2 a groove wall (rake face) of chip discharge groove 2 facing tool rotation direction 3 outer peripheral flank 4 outer peripheral blade 6 tip flank 7 bottom blade 8, 11 corner part 9, 12 corner flank 9a, 12a Ends of corner flank surfaces 9, 12 on the rear side in the tool rotation direction O Axis line of tool body 1 Q ₁ Rotation trajectory around axis O of outer peripheral blade 4 Q ₂ Rotation trajectory around axis O of bottom blade 7

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23C 5/10

Claims (1)

(57) [Claims] 1. A chip discharge groove is formed on an outer periphery of a tool body rotated about an axis from a tip end thereof to a base end side, and a groove wall surface of the chip discharge groove in a tool rotation direction and an outer periphery of the tool body. An end mill comprising: an outer peripheral edge formed at an intersection ridge line with an outer peripheral flank; and a bottom edge formed at an intersection ridge line between the groove wall surface and the tip flank of the tool body tip. substantially arcuate also have corners where the end cutting edge intersects the
Is formed in a chamfered shape, and a corner flank is formed behind the corner in the tool rotation direction. The corner flank is positioned rearward in the tool rotation direction with respect to the rotation locus of the corner around the axis. An end mill which gradually retreats toward a tool inner peripheral side and a base end side as it goes to a side, and is formed of a convex curved surface which is curved at least in a circumferential direction of the tool main body.