JP2020082206A - End mill with coolant hole - Google Patents

Abstract

To achieve effective discharge of chips, and cooling and lubrication of a cut portion on a bottom blade and a material to be cut by suppressing a coolant supplied from a coolant hole from being scattered before reaching the bottom blade with respect to all the bottom blades.SOLUTION: An end mill with coolant holes is such that: gashes 6 are formed in tips of a plurality of chip discharge grooves 4 formed in a tip outer periphery of an end mill body 1 rotated around an axis line O; bottom blades 8 are each formed in a cross ridge line part between a wall surface directing an end mill rotation direction T of the gash 6, and a tip flank 7; coolant holes 9 of the same number as that of the bottom blades 8 are formed in the end mill body 1 spaced apart from the axis line O so as to extend to the tip side of the end mill body 1, and are opened at an end mill rotation direction T side of the bottom blade 8 on the tip surface of the end mill body 1; and at least a part of openings of the coolant holes 9 in the tip surface of the end mill body 1 is opened to a wall surface 6b directing an opposite side to the end mill rotation direction T of the gash 6.SELECTED DRAWING: Figure 3

Description

According to the present invention, a plurality of chips discharging grooves are formed on the outer periphery of the tip end portion of the end mill body rotated around the axis, and a gash is formed at the tip ends of these chip discharging grooves. Bottom blades are formed at the ridges intersecting with the facing wall surface and the flank of the end mill body that is continuous on the side opposite to the end mill rotation direction of the gash, and the same number of coolant holes as the bottom blades are formed on the end mill body. The present invention relates to an end mill with a coolant hole that is opened toward the end mill rotation direction side of the bottom blade on the tip surface of the end mill body.

As such an end mill with a coolant hole, for example, in Patent Document 1, at least one of a plurality of bottom blades formed at a ridge line crossing a wall surface facing the end mill rotation direction of a gash of a plurality of chip discharge grooves and a tip flank. One bottom blade is a long bottom blade, and coolant holes are formed in the end mill body between the chip discharge grooves that are adjacent to each other in the circumferential direction. Of these coolant holes, the long bottom blade is The coolant hole passing between the formed chip discharge groove and the chip discharge groove adjacent to the chip discharge groove on the rear side in the end mill rotation direction of the chip discharge groove is located on the tip flank that is connected to the rear side of the long bottom blade in the end mill rotation direction. The opened one is described.

JP, 2014-087859, A

However, in the end mill with a coolant hole described in Patent Document 1, as described above, the chip discharge groove continuous with the gash in which the long bottom blade is formed and the chip discharge groove adjacent to the chip discharge groove rearward in the end mill rotation direction. A coolant hole passing between and is formed in the tip flank that is connected to the rear side of the end mill rotation direction of the long bottom blade, and this long bottom blade and the bottom blade adjacent to the side opposite to the end mill rotation direction. The interval between is large.

Therefore, the coolant is scattered from the coolant hole before the coolant reaches the bottom blade adjacent to the side opposite to the end mill rotation direction of the long bottom blade, and the coolant is scattered on the side opposite to the end mill rotation direction of this long bottom blade. The dischargeability of the chips generated by the adjacent bottom blades may be impaired. Especially, in the cutting of a work material made of a light alloy represented by an aluminum alloy, since the machining efficiency is very high and the amount of chips generated is large, the chip discharging property is extremely important. When the chips are scattered and the chip discharging property is impaired, the chips are clogged and the machining efficiency is also impaired.

In addition, if the gap between the bottom blade adjacent to the side of the long bottom blade opposite to the end mill rotation direction and the opening of the coolant hole on the end mill rotation direction is large and the coolant is scattered, this bottom The cooling property and lubricity of the blade may be impaired, and the bottom blade and the portion to be cut of the work to be cut by the bottom blade may become hot, and the cutting resistance may increase.

The present invention has been made under such a background, and for all bottom blades, the coolant supplied from the coolant holes on the end mill rotation direction side is prevented from scattering before reaching the bottom blade. It is an object of the present invention to provide an end mill with a coolant hole capable of suppressing chips and efficiently discharging chips and cooling and lubricating a cutting portion of a bottom blade or a work material even in cutting of a light alloy.

In order to solve the above-mentioned problems and achieve such an object, the present invention is directed to the outer circumference of the tip end portion of the end mill body that is rotated around the axis, in the end mill rotation direction from the tip end of the end mill body toward the rear end side. A plurality of chips discharging grooves extending to the opposite side are formed at intervals in the circumferential direction, and a gash extending toward the center of rotation of the end mill body is formed at the tip ends of these chips discharging grooves. The bottom blades are formed at the ridges intersecting with the wall surfaces of the gash facing the end mill rotation direction and the tip flanks continuous to the side opposite to the end mill rotation direction of the gash. The same number of coolant holes as the bottom blade are formed so as to extend toward the front end side of the end mill body with a gap from the axis, and the front end surface of the end mill body is opened in the end mill rotation direction side of the bottom blade. At least a part of each of the opening portions of the coolant holes in the tip end surface of the end mill body is opened in a wall surface facing the side opposite to the rotation direction of the end mill of the gash.

In the end mill configured as described above, at least a part of each of the openings in the tip surface of the end mill body of the coolant holes formed in the end mill body in the same number as the bottom blade faces the side opposite to the rotation direction of the end mill of the gash. Since it opens in the wall surface, it is formed at the intersection ridge part of the wall surface facing the opening of this coolant hole and facing the end mill rotation direction of the gash, and the tip flank that is continuous on the side opposite to the end direction of the rotation of the gash. The distance between the bottom blade and the opening can be reduced.

Therefore, it is possible to prevent the coolant ejected from the opening from scattering without being accompanied by the chips generated by the bottom blade, and it is possible to efficiently discharge the chips, and to cut a large amount of chips in the cutting of the light alloy. It is possible to prevent the chip clogging even if is generated. Further, it is possible to reliably spread the coolant to the bottom blade and the cut portion of the work material cut by the bottom blade to promote cooling and lubrication, and prevent the bottom blade and the cut portion from becoming hot. At the same time, the cutting resistance can be reduced.

Here, in a normal end mill, an outer peripheral blade is formed at each ridge line intersecting with a wall surface of the chip discharge groove facing the end mill rotation direction and an outer peripheral flank continuous to the side opposite to the end mill rotation direction of the chip discharge groove. However, in a cross section orthogonal to the axis, the radius R of the circle that is in contact with the coolant hole from the inner peripheral side of the end mill body about the axis is the circle formed by the rotation locus of the outer peripheral blade around the axis. It is desirable that the diameter D is within the range of 0.1×D to 0.2×D.

In this way, the radius R of the circle that is in contact with the coolant hole from the inner peripheral side of the end mill main body around the above-mentioned axis is made small and the coolant hole is formed so as to open in the range close to the axis, so that the coolant is ejected from the coolant hole. The chips can be evenly discharged by the coolant, and the gap between the coolant hole and the bottom blade can be further reduced to achieve more efficient cooling and lubrication.

That is, if the radius R of the circle contacting the coolant hole from the inner peripheral side of the end mill body is larger than 0.2×D, it becomes difficult to reliably obtain such an effect. On the other hand, if the radius R of this circle is smaller than 0.1×D, the coolant hole opens too close to the axis of the end mill body, and the end mill body may be vertically fed as in the ramping process described later. There is a risk that it will not be possible.

Further, in a square end mill or a radius end mill, the bottom blade is formed along a plane perpendicular to the axis, or at least toward the rear end side of the end mill main body toward the inner peripheral side at the inner peripheral portion of the end mill main body. Although inclined so as to face, it is desirable that an angle formed by the bottom blade with respect to a plane perpendicular to the axis is within a range of 0° to 1°.

If this angle is larger than 1°, the distance between the bottom blade and the bottom surface of the machined surface formed by the bottom blade becomes large, especially at the inner peripheral portion of the end mill body, and the coolant will flow from this distance to the adjacent gash. If it leaks out, the pressure of the coolant drops, which may make it difficult to efficiently discharge the chips. Further, if this angle is smaller than 0° and the bottom blade projects toward the tip end toward the inner peripheral portion of the end mill body, the bottom surface of the machined surface will be recessed.

As described above, according to the present invention, even when a large amount of chips are produced by cutting a light alloy such as an aluminum alloy, the chips are efficiently discharged to prevent chip clogging, and It is possible to reliably cool and lubricate the cut portion of the work material by the blade and the bottom blade, and it is possible to perform highly efficient cutting work.

It is a perspective view of an end mill main body tip part showing one embodiment of the present invention. 2 is a side view of the embodiment shown in FIG. 1. FIG. It is a front view of the embodiment shown in FIG. It is a ZZ sectional view in FIG.

1 to 4 show an embodiment of the present invention and show a case where the present invention is applied to a square end mill. In the present embodiment, the end mill body 1 is formed of a hard material such as cemented carbide into a columnar shape with the axis O as the center, and the rear end portion (right side portion in FIG. 2) of the shank portion 2 remains cylindrical. At the same time, the tip portion (left side portion in FIG. 2) is the cutting edge portion 3.

In such an end mill, while the shank portion 2 is gripped by the main shaft of the machine tool and is rotated about the axis O in the end mill rotation direction T, the end mill is normally fed out in a direction perpendicular to the axis O. Used for cutting alloy work materials. In addition to the case of being sent out in the direction perpendicular to the axis O in this way, it may be sent out to the oblique tip side with respect to the axis O and used for vertical feeding such as ramping.

The cutting blade portion 3 has a plurality of (three in this embodiment) chips discharged that are twisted around the axis O toward the side opposite to the end mill rotation direction T from the front end surface of the end mill body 1 toward the rear end side. Grooves 4 are formed at intervals in the circumferential direction. At the intersection ridge line portion between the wall surface of the chip discharge groove 4 facing the end mill rotation direction T and the outer peripheral surface of the end mill body 1 which is continuous on the side opposite to the end mill rotation direction T of the wall surface, the wall surface is a rake face. Along with the outer peripheral surface as the outer peripheral flank, the outer peripheral blade 5 is formed so that the rotation locus around the axis O has a cylindrical surface shape around the axis O.

In addition, the end mill of the chip discharge groove 4 is formed by notching the inner peripheral portion of the wall surface of the chip discharge groove 4 facing the end mill rotation direction T and the wall surface facing the side opposite to the end mill rotation direction T. A gash 6 extending toward the center of rotation of the body 1 on the axis O side is formed. The end face of the gash 6 is rotated at the ridge line intersecting with the wall surface 6a of the gash 6 facing the end mill rotation direction T and the end face of the end mill body 1 which is continuous on the side opposite to the end mill rotation direction T of the gash 6. A bottom blade 8 is formed to face the wall surface 6a facing the direction T and to make the tip end surface of the end mill main body 1 continuous with the rake surface the tip flank 7.

In the end mill of the present embodiment, which is a square end mill, the bottom blade 8 is formed so as to intersect the outer peripheral blade 5 at a right angle or at an acute angle. Particularly, in the present embodiment, the bottom blade 8 intersects at an acute angle and goes toward the inner peripheral side toward the end mill. The body 1 has a middle and low height inclined toward the rear end side. The angle (middle low angle) θ formed by the bottom blade 8 with respect to the plane P perpendicular to the axis O is within the range of 1° or less, and preferably within the range of 0.5° or less. A corner where a wall surface 6a facing the end mill rotation direction T of the gash 6 which is the rake surface of the bottom blade 8 and a wall surface 6b facing the rake surface and facing away from the end mill rotation direction T of the gash 6 intersect. The part is formed in a concave curved surface shape such as a concave arc having a cross section in contact with the wall surfaces 6a and 6b.

Further, in the present embodiment, one bottom blade (right side in FIG. 3) among the plurality (three) bottom blades 8 formed on the gash 6 at the tip of the plurality (three) chips discharging groove 4 is provided. Is a long bottom blade 8a extending from the vicinity of the axis O, which is the center of rotation of the end mill body 1, to the outer peripheral side, and the other two bottom blades 8 are more axial than the long bottom blade 8a. It is a short bottom blade 8b extending from the position spaced apart from the outer peripheral side.

The gash 6 having the long-bottom blade 8a formed therein and the gash 6 having the short-bottom blade 8b adjacent to the end-mill rotation direction side T of the long-bottom blade 8a have inner peripheral portions on the respective end-mill rotation direction T sides. It communicates with Gash 6 adjacent to. Further, the gash 6 in which the remaining short bottom blade 8b adjacent to the end mill rotation direction T of the long bottom blade 8a is formed, the long bottom blade 8a adjacent to the end mill rotation direction T side by this long bottom blade 8a. Is separated from the gash 6 in which is formed.

In addition, in the present embodiment, the tip flank 7 is formed in a plurality of stages by the first tip flank 7a and the second tip flank 7b whose flank angle gradually increases toward the side opposite to the end mill rotation direction T. Has been done. The wall surface 6b of the gash 6 facing the side opposite to the end mill rotation direction T intersects the second tip flank 7b of the tip flank 7 on the end mill rotation direction T side at an obtuse angle.

On the other hand, in the end mill body 1, the same number (3) of coolant holes 9 as the bottom blades 8 are provided between the chip discharge grooves 4 adjacent in the circumferential direction, respectively, as shown in FIG. Is formed so as to extend toward the front end side of the end mill body 1 with a gap from the axis O. As shown in FIG. 2, these coolant holes 9 are opened in the end mill rotation direction T side of each bottom blade 8 on the tip surface of the end mill body 1, and the coolant holes 9 in the tip surface of the end mill body 1 are formed. At least a part of each of the openings is open to the wall surface 6b facing the side opposite to the end mill rotation direction T of the gash 6.

Here, in the present embodiment, as shown in FIG. 3, the coolant holes 9 that are open in the end mill rotation direction T side of the long bottom blade 8a and the short bottom blade 8b adjacent to the end mill rotation direction T side of the long bottom blade 8a are formed. The entire opening is open to the wall surface 6b facing the side opposite to the end mill rotation direction T of the gash 6 in which the long bottom blade 8a and the short bottom blade 8b are formed. On the other hand, a part of the opening of the coolant hole 9 that is open on the T side in the end mill rotation direction of the remaining short bottom blade 8b is partially rotated by the end mill rotation of the gash 6 in which the remaining short bottom blade 8b is formed. The opening is formed in the wall surface 6b facing the opposite side to the direction T, and the remaining portion is opened across the first tip flank 7a and the second tip flank 7b of the tip flank 7 of the long-bottom blade 8a. There is.

Further, in the present embodiment, as shown in FIG. 4, in the cross section orthogonal to the axis O, the radius R of the circle C1 that is in contact with the coolant hole 9 from the inner peripheral side of the end mill body 1 about the axis O is equal to that of the outer peripheral blade 5. It is set within the range of 0.1×D to 0.2×D with respect to the diameter D (diameter of the cutting edge portion 3) D of the circle C2 formed by the rotation locus around the axis O. In the present embodiment, the coolant hole 9 is formed to have a circular shape in a cross section orthogonal to the axis O.

In the end mill having such a configuration, at least a part of each of the openings in the tip surface of the end mill body 1 of the coolant holes 9 formed in the end mill body 1 in the same number as the bottom blades 8 of the gash 6 in which the bottom blade 8 is formed. Since the opening is formed in the wall surface 6b facing away from the end mill rotation direction T, the wall surface 6a facing the opening of the coolant hole 9 facing the end mill rotation direction T and the end wall rotation direction T of the gash 6 are shown. It is possible to reduce the distance between the bottom blade 8 and the opening formed at the ridge line intersecting with the tip flank 7 continuous to the opposite side.

Therefore, it is possible to prevent the coolant ejected from the openings of the coolant holes 9 from scattering without the chips generated by the bottom blade 8 and to efficiently discharge the chips. In particular, even when a large amount of chips are generated in the cutting of a light alloy such as an aluminum alloy, it is possible to prevent the chip clogging from occurring, and it is possible to perform a highly efficient cutting process. Further, since it is possible to surely spread the coolant to the bottom blade 8 and the part to be cut of the work material cut by the bottom blade 8 to promote cooling and lubrication, the bottom blade 8 and the bottom blade 8 are used for cutting. It is possible to prevent the temperature of the part to be cut of the work material to be high and to reduce the cutting resistance.

In particular, in the present embodiment, the long bottom blade 8a is formed on the entire opening of the coolant hole 9 on the T side in the end mill rotation direction of the long bottom blade 8a that produces the most chips and has a large cutting load. It is formed on a wall surface 6b facing the side opposite to the end mill rotation direction T of the gash 6. Therefore, it is possible to reliably discharge a large amount of chips generated by such a long bottom blade 8a, and promote efficient cooling and lubrication of the long bottom blade 8a and a portion to be cut by the long bottom blade 8a. You can

Further, in the present embodiment, in a cross section orthogonal to the axis O of the end mill main body 1, the radius R of the circle C1 contacting the coolant hole 9 from the inner peripheral side of the end mill main body 1 about this axis O is the The diameter D of the circle C2 formed by the rotation locus around the axis O is within the range of 0.1×D to 0.2×D, and the coolant hole 9 is formed at a position close to the axis O of the end mill body 1. Has been done.

As described above, in the cross section orthogonal to the axis O, the radius R of the circle C1 contacting the coolant hole 9 from the inner peripheral side of the end mill body 1 with the axis O as the center is reduced, so that the tip surface of the end mill body 1 also has Since the coolant holes 9 can be formed so as to open in the range close to the axis O, chips can be evenly discharged by the coolant ejected from the coolant holes 9. In addition, since the gap between the opening of the coolant hole 9 and the bottom blade 8 becomes smaller, more efficient cooling and lubrication can be achieved.

Here, the radius R of the circle C1 that is in contact with the coolant hole 9 from the inner peripheral side of the end mill body 1 is 0.2× with respect to the diameter D of the circle C2 formed by the rotation locus of the outer peripheral blade 5 around the axis O. If it is larger than D, it becomes difficult to reliably obtain such an effect. On the other hand, if the radius R of the circle C1 is smaller than 0.1×D and the coolant hole 9 is opened on the axis O, for example, the end mill body 1 is vertically fed as in the ramping process described above. In this case, a part where the bottom blade 8 is not formed is formed on the tip end surface of the end mill body 1, and such a vertical feed process may not be possible.

Further, in the end mill of the present embodiment, which is a square end mill, the entire bottom blade 8 is inclined toward the rear end side as it goes toward the inner peripheral side of the end mill body 1, which is a so-called middle-low. The angle (middle low angle) θ formed by the inclined bottom blade 8 with respect to the plane P perpendicular to the axis O is within the range of 1° or less.

Therefore, the gap between the bottom blade 8 and the bottom surface of the machined surface formed by the bottom blade 8 can be reduced, and the coolant can be prevented from leaking to the adjacent gash 6 from this gap portion. The pressure can be maintained, and chips can be discharged more efficiently. That is, if the angle θ is larger than 1°, it may be difficult to obtain such an effect. Here, this angle θ is preferably 0.5° or less.

In addition, in the present embodiment, the case where the entire bottom blade 8 is inclined toward the rear end side toward the inner peripheral side of the end mill main body 1 and is set to be middle low is described. The angle θ may extend along a plane P perpendicular to the axis O and the angle θ may be 0°. Further, the present invention can be applied to a radius end mill in which the bottom blade 8 and the outer peripheral blade 5 are connected to each other through a curved corner edge such as a convex arc instead of the square end mill as in the present embodiment.

Further, also in the case of a ball end mill in which the locus of rotation of the bottom blade 8 around the axis O is a convex hemispherical shape centered on the axis O, the position of the opening of the coolant hole 9 in the tip surface of the end mill body 1 and the axis O. The present invention can be applied to the position of the coolant hole 9 in the cross section perpendicular to.

1 End Mill Main Body 2 Shank Part 3 Cutting Edge Part 4 Chip Discharge Groove 5 Peripheral Edge Blade 6 Gash 6a Wall Faced to the End Mill Rotation Direction T of Gash 6 6b Wall Faced to the End Mill Rotation Direction T of Gash 6 7 Tip Relief Face 7a First tip flank 7b Second tip flank 8 Bottom blade 8a Long bottom blade 8b Short bottom blade 9 Coolant hole O End mill body 1 axis T End mill rotation direction C1 Coolant hole centered on axis O in the cross section perpendicular to axis O 9 is a circle that is in contact with the end mill body 1 from the inner peripheral side. R is a radius of a circle C1 is C2 is a circle formed by a rotation locus of the outer peripheral blade 5 around the axis O. D is a diameter of a circle C2. P is a plane perpendicular to the axis O. Angle to

Claims (3)

Around the outer circumference of the tip of the end mill body that rotates around the axis, multiple chips discharge grooves are formed at intervals in the circumferential direction that extend in the direction opposite to the end mill rotation direction from the tip of the end mill body toward the rear end side. In addition, at the tip of these chip discharge grooves, a gash extending toward the rotation center of the end mill body is formed, and the wall surface of the gash facing the end mill rotation direction and the end mill rotation direction of the gash are Bottom blades are formed on the ridges that intersect with the flanks on the opposite side.
The same number of coolant holes as the bottom blade are formed in the end mill body so as to extend toward the tip side of the end mill body with a gap from the axis, and the bottom blade on the tip surface of the end mill body is formed. It has an opening on the end mill rotation direction side of
An end mill with a coolant hole, wherein at least a part of each of the coolant holes on the tip surface of the end mill body is opened on a wall surface of the gash facing away from the rotation direction of the end mill. An outer peripheral blade is formed at each of the intersecting ridges of the wall surface of the chip discharge groove facing the end mill rotation direction and the outer peripheral flank that is continuous on the side opposite to the end mill rotation direction of the chip discharge groove,
In a cross section orthogonal to the axis, the radius R of the circle that is in contact with the coolant hole from the inner peripheral side of the end mill body around the axis is the diameter D of the circle formed by the rotation locus of the outer peripheral blade around the axis. 2. The end mill with a coolant hole according to claim 1, wherein the end mill has a coolant hole size of 0.1×D to 0.2×D. The bottom blade is formed along a plane perpendicular to the axis, or is inclined at least toward the rear end side of the end mill body toward the inner peripheral side at the inner peripheral portion of the end mill body. The end mill with a coolant hole according to claim 1 or 2, wherein an angle formed by the bottom blade with respect to a plane perpendicular to the axis is within a range of 0° to 1°.

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