WO2018131537A1 - Drill and drill head - Google Patents

Abstract

This drill (10) comprises: a drill body (1) which rotates about an axis (O); a chip-discharging groove (2) which extends towards the base end of the drill body (1) from the tip of the drill body (1); and a tip blade (20) which is formed at the intersecting ridgeline part between the wall surface (2a) of the chip discharging groove (2), which is oriented in the drill rotational direction, and the tip surface (6) of the drill body (1). The tip blade (20) has: a first tip blade (21) which extends towards the base end in the axis (O) direction as the blade extends towards the outside in the radial direction; a second tip blade (22) which is disposed on the outside of the first tip blade (21) in the radial direction and extends towards the tip in the axis (O) direction as the blade extends towards the outside in the radial direction; a third tip blade (23) which is disposed on the outside of the second tip blade (22) in the radial direction and extends towards the base end in the axis (O) direction as the blade extends towards the outside in the radial direction; and a boundary vertex (24) which is located on the boundary between the second tip blade (22) and the third tip blade (23). The boundary vertex (24) is located further towards the base end in the axis (O) direction than the innermost periphery portion (21c) of the first tip blade (21).

Description

Drill and drill head

The present invention relates to a drill and a drill head.
This application claims priority based on Japanese Patent Application No. 2017-004189 filed in Japan on January 13, 2017, the contents of which are incorporated herein by reference.

CFRP (carbon fiber reinforced resin) and other composite materials used for aircraft parts, etc., when drilling, for example, fiber layer delamination (delamination), uncut fiber (uncut fiber), Extensive missing burr, whiskers, etc. (hereinafter abbreviated as burr) are likely to occur. Therefore, for a work material made of CFRP or the like, a dedicated drill is used for the purpose of suppressing the occurrence of burrs or the like on the inner periphery of the machining hole (for example, Patent Document 1).

JP 2009-502538 A

Work material made of fiber reinforced plastic such as CFRP has fiber orientation. For this reason, unless the rake angle of the cutting edge is set appropriately with respect to the fiber direction, the fiber is easily peeled off, and burrs and the like are likely to occur. The conventional drill has room for improvement in that the rake angle of the cutting edge with respect to the fiber direction is appropriately set to suppress the occurrence of burrs and the like.

The present invention has been made under such a background, and provides a drill and a drill head capable of suppressing the occurrence of burrs even when drilling a fiber reinforced plastic such as a carbon fiber reinforced plastic. It is an object.

In order to solve such problems and achieve the above object, the present invention proposes the following means.

(1) A drill according to an aspect of the present invention includes a drill body that rotates around an axis, and a drill body that is formed on an outer periphery of the drill body and extends from the distal end of the drill body to the proximal end side of the drill body along the axial direction. A chip discharge groove extending toward the tip, and a tip blade formed at a cross ridge line portion between the wall surface of the chip discharge groove facing the drill rotation direction and the tip surface of the drill body, and the tip blade is in the radial direction. A first tip blade that extends toward the base end side in the axial direction as it goes outward, and a radially outer side of the first tip blade, and extends toward the tip end side in the axial direction as it goes outward in the radial direction A second tip blade, a third tip blade that is disposed radially outward of the second tip blade and extends toward the base end side in the axial direction toward the radially outer side; the second tip blade; Boundary vertex located at the boundary with 3 tip blade and The a, the boundary vertex located on the proximal side of the axial direction from the innermost portion of the first tip blade.

In general, the axial cutting force (thrust load) acting on the work material during drilling with a drill tends to increase at the innermost peripheral portion at the tip of the drill. In conventional drills, the axial cutting force acting on the work material near the center of the drill tip is propagated to the inner periphery of the drilled hole, and the work material is likely to delaminate. .
On the other hand, according to this invention, the front-end | tip blade is separately provided with the 1st front-end | tip blade located in the radial direction inner side in a drill front-end | tip, and the 2nd front-end | tip blade located in a radial direction outer side. The first leading edge is inclined toward the proximal end in the axial direction as it goes radially outward, and the second leading edge is inclined to the side opposite to the first leading edge. Thereby, the cutting force in the axial direction generated in the work material by the first tip edge is suppressed from being propagated to the outside by the second tip edge. Accordingly, it is possible to suppress delamination on the inner periphery of the processed hole after processing.

Furthermore, the 3rd front-end | tip blade which functions as a chamfer part is provided in the radial direction outer side of the 2nd front-end | tip blade. The second tip blade extends toward the tip side in the axial direction as it goes radially outward. Therefore, the second tip blade cuts the fibers of the work material so as to press the work material inward in the radial direction.
In addition, since the 2nd front-end | tip blade presses a workpiece | work material to radial direction inner side, when escaping from a workpiece | work material, a workpiece | work material may be elastically deformed and it may produce delamination and a fiber uncut. Even in this case, by providing the third tip blade as the chamfer portion outside the second tip blade, when the tip blade exits the work material, the tip blade opens the through hole of the work material. The action of pressing the peripheral edge in the axial direction can be reduced. That is, the reinforcing fibers at the periphery of the opening can be cut without being pushed out in the penetrating direction, and delamination and uncut fibers can be suppressed at the periphery of the opening of the through hole.

Furthermore, since the boundary vertex is located on the proximal end side in the axial direction from the innermost peripheral portion of the first tip blade, the innermost peripheral portion of the first tip blade comes into contact with the workpiece prior to the boundary vertex. The innermost peripheral portion of the first tip blade is disposed along an axis that is the center of rotation of the drill. Therefore, when the innermost peripheral portion of the first tip edge comes into contact with the object to be processed in advance, it is possible to position the drilling without causing chatter.

(2) The third tip edge may have a positive rake angle in the radial direction at the radially outermost peripheral portion.

In this case, in the third tip blade, the rake angle in the radial direction at the outermost peripheral portion in the radial direction is a positive angle (positive angle). Accordingly, the outermost peripheral portion of the third tip blade has the highest speed at the tip blade. The outermost peripheral portion of the third tip blade is a portion where the tip blade is connected to the outer peripheral blade, and is a portion that forms the inner peripheral surface of the hole in the drilling process. Therefore, by setting the rake angle of the outermost peripheral portion of the third tip blade to be a positive angle, the fiber is cut by cutting a sharp edge at a high speed with respect to the inner peripheral surface of the hole, and the burrs on the inner peripheral surface of the hole are cut. Can be effectively suppressed.

(3) The first tip blade extends along a radial direction perpendicular to the axis in a front view of the drill when the drill body is viewed from the tip in the axial direction toward the base end. The rake face of one tip blade may be parallel to the axis.

In this case, the rake face of the first tip edge is formed to be parallel to the axis of the drill body. Therefore, the axial rake angle (axial rake angle) of the first tip edge is a negative angle (0 °). And in drill front view, the 1st tip edge is extended so that the radial direction of a drill main part may be met. That is, the first tip edge is set so that the center height is zero, not the center up or core down.
When drilling a work material such as CFRP with one direction as the fiber direction with such a drill, the occurrence of burrs or the like is noticeable even in the region where the cutting edge rotates in the direction opposite to the fiber direction of the work material. Can be suppressed. That is, the cutting edge of the first tip blade is not cut in the reverse direction with respect to the fiber direction of the work material, and the cutting edge is cut perpendicular to the fiber direction, so that generation of uncut fibers can be suppressed.

(4) The diameter of the rotation locus of the boundary vertex may be 50% or more with respect to the maximum diameter of the drill body.

In this case, the radially outer end of the second tip blade can be disposed sufficiently outside. The tip blade is faster in the radial direction. Therefore, the speed of the radial end portion of the second tip blade can be increased, the machinability of the second tip blade can be improved, and delamination of the work material by the second tip blade and uncut fiber can be suppressed.

(5) The third tip edge is inclined in a direction away from the axis as it goes toward the base end side, and the inclination with respect to the axis may be small as it goes from the radially inner side to the radially outer side.

In this case, the third tip blade has a smaller inclination with respect to the axis as it goes radially outward. As the cutting force acting on the work material from the third tip edge increases in the radial direction, the component force in the circumferential direction increases and the component force in the axial direction decreases. Thereby, it is possible to reduce the load to be delaminated at the portion forming the inner peripheral surface of the hole to be processed, and to suppress delamination of the work material.

(6) You may have a primary front end flank which continues to the rotation back side of the 1st front end blade, and a secondary front end flank which continues to the rotation back side of the primary front end flank.

In this case, a primary tip flank and a secondary tip flank are formed in this order on the rotation rear side of the first tip blade. Therefore, even when the primary tip flank is worn, it is possible to ensure sufficient evacuation for the action of the secondary tip flank.

(7) In the axial direction, the second tip edge may overlap an area of 30% or more of the first tip edge.

In this case, it is possible to more reliably suppress the axial cutting force that causes delamination in the work material by the first tip edge from propagating to the outer peripheral side by the second tip edge.

(8) The drill head according to one aspect of the present invention is a drill head attached to a tip portion of a tool main body, and is formed on the outer periphery of the head main body rotating around the axis together with the tool main body, A chip discharge groove extending from the front end of the head body toward the base end side of the head main body along the axial direction, a wall surface facing the drill rotation direction of the chip discharge groove, and a front end surface of the head main body A tip blade formed on the ridge line portion, the tip blade extending toward the proximal end in the axial direction as it goes radially outward, and the radially outer side of the first tip blade A second tip blade extending toward the tip end side in the axial direction as it goes radially outward, and a base end in the axis direction as it goes radially outward of the second tip blade. Extend toward the end And a boundary vertex located at the boundary between the second tip blade and the third tip blade, and the boundary vertex is the axis line from the innermost peripheral portion of the first tip blade. Located on the proximal side of the direction.

According to the drill head according to the present invention, the same operational effects as the above-described drill according to the present invention can be obtained.

According to the drill and the drill head of the present invention, it is possible to stably improve the finishing accuracy of the inner periphery of the processed hole formed in the work material.

It is a side view of the drill of 1st Embodiment. It is a front view of the drill of 1st Embodiment. It is an enlarged view of the area | region III of FIG. FIG. 4 is a cross-sectional view of the drill along the line IV-IV in FIG. 1. It is a side view of the drill of 2nd Embodiment. It is a front view of the drill of 2nd Embodiment. It is a side view of the drill of 3rd Embodiment. It is a front view of the drill of 3rd Embodiment.

Embodiments to which the present invention is applied will be described below in detail with reference to the drawings.
Note that in the drawings used in the following description, in order to make the characteristic portions easy to understand, portions that do not become characteristic may be omitted for convenience.

<First Embodiment>
FIG. 1 is a side view of a drill 10 according to the first embodiment. FIG. 2 is a front view of the drill 10 as viewed from the front end surface side.

[Schematic configuration of drill]
As shown in FIG. 1 and FIG. 2, a drill 10 according to the present embodiment has a drill body 1 that is formed in a substantially cylindrical shape centering on an axis O and is formed of a hard material such as cemented carbide. Yes.
The drill body 1 has a proximal end portion in the axis O direction as a cylindrical shank portion (not shown) and a distal end portion in the axis O direction as a blade portion having a cutting edge. The cutting blade includes a tip blade 20 and an outer peripheral blade 4 which will be described later.

The drill 10 is used in a state in which the shank portion of the drill body 1 is detachably mounted on the spindle of a machine tool, a drilling machine, a three-jaw chuck of an electric drill, or the like. The drill 10 is fed to the tip side (lower side in FIG. 1) along the axis O direction while the drill body 1 rotates in the drill rotation direction T around the axis O, and cut into the work material by the blade portion. Drill holes.

Examples of the work material to be processed by the drill 10 include CFRP (carbon fiber reinforced resin) used for aircraft parts and the like, and composite materials in which a metal plate such as titanium or aluminum is laminated on CFRP. In the present specification, these may be collectively referred to as CFRP or the like.

[Definition of direction (direction) used in this specification]
In this specification, the direction from the shank part toward the blade part in the direction along the axis O of the drill body 1 (axis O direction) is referred to as the distal end side (lower side in FIG. 1), and is directed from the blade part toward the shank part. The direction is referred to as a base end side (upper side in FIG. 1).
In addition, a direction orthogonal to the axis O is referred to as a radial direction, and in the radial direction, a direction approaching the axis O is referred to as a radial inner side, and a direction away from the axis O is referred to as a radial outer side.
Further, a direction that circulates around the axis O is referred to as a circumferential direction. Of the circumferential directions, a direction in which the drill 10 rotates during cutting is referred to as a drill rotation direction T, and an opposite rotation direction is referred to as a drill rotation direction T. Is the opposite side (counter-drilling direction).

[Outer circumference of drill body]
On the outer periphery of the drill body 1, a chip discharge groove 2 extending from the tip of the drill body 1 toward the base end side of the drill body 1 along the axis O direction, and a wall surface facing the drill rotation direction T of the chip discharge groove 2 The outer peripheral blade 4 formed in the crossing ridgeline part of 2a and the outer peripheral surface of the drill main body 1 is provided.

Of the outer periphery of the drill body 1, a margin portion 11 and a second picking surface 15 are formed on the outer peripheral surface other than the chip discharge groove 2.
The margin portion 11 is connected to the side opposite to the drill rotation direction T with respect to the outer peripheral blade 4. The margin portion 11 extends along the outer peripheral blade 4 and has the same diameter as the outer peripheral blade 4, and constitutes the outermost diameter portion of the blade portion of the drill body 1.
The second picking surface 15 is continuous with the margin portion 11 on the side opposite to the drill rotation direction T. The second surface 15 has a smaller diameter than the outer peripheral blade 4 and the margin portion 11.

[Chip discharge groove]
In the present embodiment, a plurality of chip discharge grooves 2 are formed on the outer periphery of the drill body 1 at intervals in the circumferential direction. The chip discharge grooves 2 are opened in the tip surface 6 of the drill body 1, respectively. Further, the chip discharge groove 2 is gradually twisted toward the side opposite to the drill rotation direction T from the tip end in the direction of the axis O toward the base end side, and extends spirally.

Of the wall surface 2 a facing the drill rotation direction T in the chip discharge groove 2, a gash rake surface 2 c is formed at a tip portion connected to the tip surface 6 via a tip blade 20 described later. The gash rake face 2c is formed to be parallel to the axis O. In this embodiment, the gash rake face 2c is formed in a triangular shape.
A portion of the chip discharge groove 2 that is located on the proximal end side in the axis O direction from the gash rake face 2c (that is, a portion other than the gash rake face 2c) is directed from the gash rake face 2c toward the proximal end side in the axis O direction. Accordingly, it gradually twists and extends toward the side opposite to the drill rotation direction T.

As shown in FIGS. 1 and 2, a plurality (two in this embodiment) of the chip discharge grooves 2 are arranged so as to be rotationally symmetric with respect to the axis O. Further, the plurality of chip discharge grooves 2 are arranged on the outer periphery of the drill main body 1 at equal intervals (at an equal pitch) in the circumferential direction.
Specifically, the drill 10 of the present embodiment is a twist drill in which the two chip discharge grooves 2 are arranged in the drill main body 1 with a 180 ° rotational symmetry about the axis O.

Although not shown in particular, the chip discharge groove 2 is cut to the outer peripheral surface toward the radially outer side, for example, in the vicinity of the central portion along the axis O direction of the drill body 1. In the drill body 1, a range in which the chip discharge groove 2 along the axis O direction is formed is a blade portion, and a proximal end side is a shank portion from this range.

The chip discharge groove 2 has a concave curved inner surface. The chip discharge groove 2 is formed so as to be recessed in the radial direction and toward the drill rotation direction T. Further, the chip discharge groove 2 is formed so that the groove depth is deepest (the inner periphery of the groove is closest to the axis O) in the vicinity of the central portion along the circumferential direction.

[Outer peripheral edge, margin part]
The margin portion 11 is continuous with the wall surface 2 a facing the drill rotation direction T with respect to the chip discharge groove 2. The margin portion 11 has an outer diameter that is substantially equal to an outermost diameter of the tip blade 20 described later (that is, a diameter φD of a circle of a rotation locus formed by rotating the outer edge in the radial direction of the tip blade 20 around the axis O). It is formed so as to be located on the virtual cylindrical surface. In the drill main body 1, an intersecting ridge line portion between the wall surface 2 a facing the drill rotation direction T of the chip discharge groove 2 and the margin portion 11 is an outer peripheral blade 4.

In the present embodiment, the outer peripheral blade 4 and the margin portion 11 are gradually twisted toward the side opposite to the drill rotation direction T along the spiral chip discharge groove 2 from the distal end in the axis O direction toward the proximal end side. , Extending spirally. In other words, the chip discharge groove 2, the outer peripheral edge 4, and the margin portion 11 have the same twist angle (lead, axial tilt angle). The twist angle of the outer peripheral blade 4 is, for example, 40 ° or less.

[2nd surface]
Of the outer peripheral surface of the drill body 1, a portion located between the margin portion 11 and the chip discharge groove 2 adjacent to the margin portion 11 on the opposite side to the drill rotation direction T is a second collecting surface 15. It is said that.
Although not particularly illustrated, the second picking surface 15 is disposed so as to recede inward in the radial direction with respect to the rotation locus of the outer peripheral blade 4 around the axis O.

The second face 15 is connected to the side opposite to the drill rotation direction T with respect to the margin portion 11 on the outer peripheral surface of the drill body 1. The second surface 15 has an outer diameter smaller than the outer diameter of the margin portion 11. Even if the retreating amount (second reclaiming depth) by which the second picking surface 15 retreats radially inward from the rotation locus of the outer peripheral blade 4 is constant over the entire circumferential direction of the second picking surface 15. Good. Further, as the second picking surface 15 moves from the end of the drill rotation direction T toward the side opposite to the drill rotation direction T, the amount of retraction from the rotation locus of the outer peripheral blade 4 toward the radially inner side gradually increases. Also good.

[Heel part]
Of the outer periphery of the drill main body 1, the heel portion 13 is an intersecting ridge line portion between the second picking surface 15 and the wall surface 2 b facing the side opposite to the drill rotation direction T with respect to the chip discharge groove 2. The heel portion 13 is pointed toward the side opposite to the drill rotation direction T. The heel part 13 is formed in a ridge shape extending along the chip discharge groove 2.

[End of drill body]
Formed at the tip of the drill body 1 is a crossed ridge line portion between the tip surface 6 facing the tip side (drill feed direction) of the drill 10 and the wall surface 2 a facing the drill rotation direction T of the chip discharge groove 2 and the tip surface 6. And a thinning surface 9 positioned between the tip surface 6 and the chip discharge groove 2 adjacent to the tip surface 6 on the side opposite to the drill rotation direction T.

[Tip surface]
As shown in FIG. 2, the tip surface (tip flank) 6 has a first flank 61, a second flank 62, and a third flank 63.
The first flank 61 inclines toward the base end side in the axis O direction as it goes from the first tip edge 21 of the tip edge 20 to the side opposite to the drill rotation direction T. The second flank is inclined toward the base end side in the direction of the axis O as it goes from the second tip edge 22 of the tip edge 20 to the side opposite to the drill rotation direction T. The third flank 63 inclines toward the base end side in the axis O direction from the third tip edge 23 of the tip edge 20 toward the side opposite to the drill rotation direction T.
The first flank 61, the second flank 62, and the third flank 63 are each inclined toward the proximal end in the direction of the axis O gradually toward the opposite side of the drill rotation direction T. Thereby, clearance angles are given to the first tip blade 21, the second tip blade 22, and the third tip blade 23, respectively.

In the front view of the drill shown in FIG. 2, the first flank 61 is formed in a triangular shape having one side as the first tip edge 21. As shown in FIG. 2 by a virtual line (two-dot chain line), the first flank 61 may have a primary tip flank 61a and a secondary tip flank 61b. In this case, the primary tip flank 61 continues to the rotational rear side of the first tip blade 21. Further, the secondary tip flank 61b is continuous with the rotational rear side of the primary tip flank 61a.
Since the first flank 61 has the primary tip flank 61a and the secondary tip flank 61b, even if the primary tip flank 61a is worn, the secondary tip flank 61b ensures sufficient escape. it can.

A coolant hole may be opened in the tip surface 6. The opening shape of the coolant hole is, for example, a circular shape, but is not limited thereto, and may be, for example, other polygonal shapes, elliptical shapes, or the like. In the coolant hole, for example, coolant supplied from a spindle of a machine tool or the like circulates. This coolant is supplied to the tip portion of the drill body 1 and the processing part of the work material.

[Thinning surface]
The thinning surface 9 is located at the tip of the chip discharge groove 2. The thinning surface 9 is formed in a portion located between the tip surface 6 and the region from the wall surface 2b facing the opposite side of the drill rotation direction T of the chip discharge groove 2 to the groove bottom. In other words, the thinning surface 9 is located between the tip surface 6 and the chip discharge groove 2 adjacent to the tip surface 6 on the opposite side to the drill rotation direction T.

The thinning surface 9 is inclined toward the proximal end side in the axis O direction as it goes from the distal end surface 6 to the side opposite to the drill rotation direction T. The displacement amount (that is, the inclination) in the direction of the axis O per unit length along the drill rotation direction T on the thinning surface 9 is larger than the displacement amount on the tip surface 6.

[Tip blade]
As shown in FIGS. 1 and 2, the tip blade 20 is formed at the intersecting ridge line portion between the wall surface 2 a of the chip discharge groove 2 facing the drill rotation direction T and the tip surface 6 of the drill body 1. A gash rake face 2c is formed at a part of the tip of the wall surface 2a. Therefore, a part of the tip blade 20 is located at the intersection ridgeline between the gash rake face 2 c and the tip face 6. Further, the tip blade 20 has a gash rake face 2c and a wall surface 2a as a rake face, and a tip face 6 as a flank face. The tip blade 20 extends from the axis O in the drill body 1 to the outer end (outermost circumference) in the radial direction.

The leading edge 20 has a first leading edge 21, a second leading edge 22 and a third leading edge 23.
The first tip blade 21, the second tip blade 22, and the third tip blade 23 each extend from the radially inner side toward the radially outer side. The first tip blade 21, the second tip blade 22 and the third tip blade 23 are arranged in this order from the radially inner side to the radially outer side.

As shown in FIG. 1, the 1st front-end | tip blade 21 has the inner side part 21a and the outer side part 21b located in a radial direction outer side from the inner side part 21a.
The inner part 21a and the outer part 21b extend in a direction inclined toward the base end side in the axis O direction as going outward in the radial direction. The inclination of the outer part 21b is larger than the inclination of the inner part 21a. Therefore, the boundary between the inner portion 21a and the outer portion 21b is a convex portion. The innermost peripheral part 21c of the first tip blade 21 is located on the innermost side in the radial direction of the inner part 21a.

The inner portion 21 a of the first tip edge 21 is located at the intersection ridge line between the gash rake face 2 c and the tip face 6. The gash rake face 2c functions as a rake face of the inner portion 21a. As described above, the gash rake face 2c is formed to be parallel to the axis O.

As shown in FIG. 2, the inner portion 21 a of the first tip blade 21 extends along the radial direction when the drill body 1 is viewed from the tip in the direction of the axis O toward the base end. .
In this specification, “extending along the radial direction” means that the angle formed between the radial direction of the drill body 1 and the blade length direction is close to zero in the front view of the drill. It means that it is a small value (approximately 0 °). Specifically, it means that the angle is, for example, 5 ° or less (0 to 5 °). That is, the inner portion 21a of the first tip blade 21 of the present embodiment is set so that the center height is not zero but the center height is zero.

The “core height” will be described.
As is well known, the center height (center height dimension) is a distance at which the tip blade is separated from a virtual straight line VL passing through the axis parallel to the blade length direction of the tip blade in a front view of the drill. A distance L at which the tip blade is separated from a virtual straight line VL that is parallel to the blade length direction of the tip blade and passes through the axis O is the core height. When the tip edge is positioned in the drill rotation direction T with respect to the imaginary straight line VL, it becomes “centering up”, and when it is located on the opposite side of the drill rotation direction T, it is “centering down”.

In the drill 10 of this embodiment, the center height of the inner portion 21a of the first tip blade 21 is zero. Specifically, in this drill front view, the inner portion 21a of the first tip blade 21 is formed in a straight line, and the center height is set to zero over the entire blade length.
In this specification, “the core height is zero” means not only the case where the core height is completely zero, but also the core height of the inner portion 21a is a small value (approximately 0) close to zero. Refers to being. Specifically, the case where the core height is 3% or less with respect to the maximum diameter of the drill body 1 is included.

The rake face (gash rake face 2c) of the inner portion 21a of the first tip blade 21 is formed to be parallel to the axis O of the drill body 1. Therefore, the axial rake angle (axial rake angle) of the inner portion 21a of the first tip blade 21 is a negative angle (0 °) over the entire blade length of the inner portion 21a.
The axial rake angle of the inner portion 21a of the first tip blade 21 is a negative angle (0 °), and the inner portion 21a extends along the radial direction (the core height is zero). Therefore, the rake angle (radial rake angle) in the radial direction of the inner portion 21a is a negative angle (0 °).

The second tip blade 22 is disposed on the radially outer side of the first tip blade 21. The second tip blade 22 extends in a direction inclined toward the tip side in the axis O direction as it goes radially outward. The second tip blade 22 extends while being inclined to the opposite side with respect to the first tip blade 21. For this reason, the boundary part of the 1st tip blade 21 and the 2nd tip blade 22 turns into a recessed part. The second tip blade 22 preferably overlaps with an area of 30% or more along the axis O direction of the first tip blade in the axis O direction.

The outermost peripheral portion 23a and the second tip blade 22 of the first tip blade 21 are located on the intersecting ridge line with the wall surface 2a facing the drill rotation direction T of the chip discharge groove 2. Therefore, the wall surface 2 a functions as the outermost peripheral portion 23 a of the first tip edge 21 and the rake face of the second tip edge 22.

The third tip blade 23 is disposed on the radially outer side of the second tip blade 22. The third leading edge 23 extends obliquely toward the base end side in the axis O direction as it goes radially outward. A boundary portion between the second tip blade 22 and the third tip blade 23 is a convex portion. The third tip blade 23 functions as a chamfer portion of the second tip blade 22. A boundary vertex 24 is located at the boundary between the second tip edge 22 and the third tip edge 23. The boundary vertex 24 is located on the proximal end side in the axis O direction from the innermost peripheral portion 21c of the first tip blade 21.

By rotating the drill body 1, the boundary vertex 24 draws a rotation locus having a diameter d <b> 24. The diameter d24 of the rotation locus of the drill body 1 is preferably 50% or more with respect to the maximum diameter D of the drill body 1.
The maximum diameter D of the drill body 1 matches the diameter of the hole drilled by the drill 10. In the present embodiment, the maximum diameter D of the drill main body 1 matches the diameter of the outer peripheral blade 4. When the drill body 1 is provided with a back taper, the maximum diameter of the drill body 1 is the tip portion of the outer peripheral blade 4 in the direction of the axis O, and the boundary portion between the outer peripheral blade 4 and the third tip blade 23 ( That is, it becomes the diameter of the rotation locus of the outermost peripheral portion 23a) of the third tip blade 23.

As shown in FIG. 2, the second tip edge 22 and the third tip edge 23 are in the vicinity of the apex where the rake angles (axial rake angle and radial rake angle) are different from those of the other portions in the vicinity of the boundary apex 24. It has a rake face 24a.
The rake surface 24a near the apex is formed on the same surface as the rake surface (gash rake surface 2c) of the inner portion 21a of the first tip blade 21. Therefore, the rake face 24 a near the apex is formed to be parallel to the axis O of the drill body 1. Further, the rake surface 24a near the apex extends along the radial direction when the drill body 1 is viewed from the front end toward the base end side in the axis O direction. Therefore, the axial rake angle (axial rake angle) and the radial rake angle (radial rake angle) of the rake surface 24a near the apex are negative angles (0 °).

FIG. 3 is an enlarged view of region III in FIG.
As shown in FIG. 3, the 3rd front-end | tip blade 23 continues to the outer periphery blade 4 in the outermost peripheral part 23a of radial direction. The third tip blade 23 includes a first straight portion 23e and a second straight portion 23f located on the radially outer side from the first straight portion 23e.
The first straight portion 23e and the second straight portion 23f each extend linearly. Further, the first straight line portion 23e and the second straight line portion 23f are inclined in a direction away from the axis O toward the proximal end side. The inclination of the first straight line portion 23e with respect to the axis O is larger than the inclination of the second straight line portion 23f with respect to the axis O. That is, the third tip blade 23 has a smaller inclination with respect to the axis O as it goes from the radially inner side to the radially outer side.

4 is a cross-sectional view of the drill 10 taken along the line IV-IV in FIG. 1 that passes through the outermost peripheral portion 23a of the third tip blade 23. As shown in FIG.
As shown in FIG. 4, the third tip edge has a positive rake angle (radial rake angle) θ23a in the radially outermost peripheral portion 23a.

[Effects of this embodiment]
Generally, the cutting force (thrust load) in the direction of the axis O acting on the work material during drilling with a drill tends to be large at the radially inner portion (near the central portion in the radial direction including the axis) at the drill tip. . For this reason, in the conventional drill, the cutting force in the direction of the axis O acting on the work material from the vicinity of the center of the drill tip propagates to the inner peripheral planned portion of the processing hole, and delamination is likely to occur. .

On the other hand, according to this embodiment, it goes to the outer side of the 1st front-end | tip blade 21 extended toward the base end side of an axis line O direction as it goes to a radial direction outer side, and goes to the front end side of an axis line O direction as it goes to a radial direction outer side. The 2nd front-end | tip blade 22 extended toward is provided.
Thereby, the cutting force in the direction of the axis O that is generated in the work material by the first tip blade 21 and causes delamination is prevented from being propagated to the outside by the second tip blade 22. Accordingly, it is possible to suppress delamination on the inner periphery of the processed hole after processing.

In the present embodiment, the second tip blade 22 overlaps with an area of 30% or more along the axis O direction of the first tip blade in the axis O direction. Thereby, it is possible to more reliably suppress the cutting force in the direction of the axis O that causes delamination of the work material by the first tip edge 21 from being propagated to the outer peripheral side by the second tip edge 22.

According to this embodiment, the third tip blade 23 that functions as a chamfer portion is provided on the radially outer side of the second tip blade 22.
Since the second tip blade 22 extends toward the tip side in the axis O direction as it goes radially outward, the second tip blade 22 presses the work material radially inward so as to press the work material. Cut the fiber. At this time, the second tip edge 22 may elastically deform the work material to cause delamination and uncut fiber.
Even in this case, since the third tip blade as the chamfer portion is provided outside the second tip blade 22, when the tip blade 20 exits the work material, the tip blade 20 is made of the work material. The action of pressing the peripheral edge of the opening of the through hole in the direction of the axis O can be reduced. That is, the reinforcing fibers at the periphery of the opening can be cut without being pushed out in the penetrating direction, and delamination and uncut fibers can be suppressed at the periphery of the opening of the through hole.

According to the present embodiment, the boundary vertex 24 located between the second tip blade 22 and the third tip blade 23 is located closer to the base end side in the axis O direction than the innermost peripheral portion 21 c of the first tip blade 21. To do. For this reason, the front-end | tip of the 1st front-end | tip blade 21 precedes the boundary vertex 24, and contacts with respect to a process target. The innermost peripheral portion 21c of the first tip blade 21 is disposed along the axis O serving as the rotation center of the drill. Therefore, when the tip of the first tip 21 comes into contact with the object to be processed in advance, it is possible to position the drilling without causing chatter.

According to the present embodiment, as shown in FIG. 4, the third tip blade 23 has a positive rake angle θ23a in the radial outermost peripheral portion 23a. The outermost peripheral portion 23 a of the third tip blade 23 has the highest speed in the tip blade 20. Moreover, the outermost peripheral part 23a of the 3rd front-end | tip blade 23 is a part which the front-end | tip blade 20 connects with the outer peripheral blade 4, and is a part which forms the internal peripheral surface of the hole in drilling.
Therefore, by setting the radial rake angle θ23a of the outermost peripheral portion 23a of the third tip blade 23 to be a positive angle, a sharp edge is cut at a high speed with respect to the inner peripheral surface of the hole, and fibers are cut off. Can be suppressed.

According to the present embodiment, the gash rake face of the chip discharge groove that becomes the rake face of the inner portion 21a of the first tip blade 21 is formed to be parallel to the axis of the drill body. Therefore, the rake angle in the axial direction of the inner portion 21a of the first tip blade 21 is a negative angle (0 °).
The first tip blade 21 extends along the radial direction of the drill body 1 in the front view of the drill. That is, the first tip blade 21 is set so that the center height is zero, not the center up or the core down.
When drilling a work material such as CFRP having one direction as the fiber direction with such a drill 10, the occurrence of burrs or the like is prominent even in a region where the cutting edge rotates in a direction opposite to the fiber direction of the work material. Can be suppressed. That is, according to the present embodiment, the cutting edge of the first tip blade 21 does not cut in the opposite direction with respect to the fiber direction of the work material, and the cutting edge cuts perpendicularly to the fiber direction. Generation can be suppressed.

In the tip blade 20 of the present embodiment, a rake face 24a in the vicinity of the boundary vertex 24 is formed in the same plane as the gash rake face 2c. The rake face 24 a near the apex is formed so as to be parallel to the axis O of the drill body 1.
Accordingly, the axial rake angle (axial rake angle) and the radial rake angle (radial rake angle) of the rake surface 24a near the apex are negative angles (0 °), and the same effect as the gash rake surface 2c is achieved. . That is, according to the present embodiment, the cutting edge does not cut in the reverse direction with respect to the fiber direction of the work material in the vicinity of the boundary vertex 24, and the cutting edge cuts perpendicularly to the fiber direction. Generation can be suppressed.

In the present embodiment, as shown in FIG. 1, the diameter d24 of the rotation trajectory of the boundary vertex 24 is 50% or more with respect to the maximum diameter D of the drill body 1, so The end can be located sufficiently outside. The tip blade is faster in the radial direction. Therefore, according to the present embodiment, it is possible to increase the speed of the radial end portion of the second tip blade 22 and improve the machinability of the second tip blade 22, and the layer of the work material by the second tip blade 22. Separation and uncut fiber can be suppressed.

In the present embodiment, the third tip blade 23 has a smaller inclination with respect to the axis O as it goes outward in the radial direction. The component force in the direction of the axis O of the cutting force acting on the work material from the tip edge decreases as the inclination of the tip edge approaches the axis O. According to the present embodiment, the cutting force acting on the work material from the third tip blade 23 increases in the circumferential direction and decreases in the axial O direction as it goes radially outward. Thereby, it is possible to reduce the load to be delaminated at the portion forming the inner peripheral surface of the hole to be processed, and to suppress delamination of the work material.

In addition, the 3rd front-end | tip blade 23 of this embodiment is located in the radial direction outer side from the 1st straight line part 23e and the 1st straight line part 23e, and the 2nd straight line part 23f whose inclination with respect to the axis line O is smaller than the 1st straight line part 23e. And have. However, the third tip blade 23 may be formed in a curved shape that gradually decreases the inclination with respect to the axis O as it goes radially outward.

In the drill 10 of this embodiment, a pair (two strips) of the chip discharge grooves 2 are arranged on the outer periphery of the drill body 1 at intervals in the circumferential direction, and a pair (two) of the tip blades 20 are formed. Although it is a 2-blade drill (twist drill), it is not limited to this. That is, three or more chips discharging grooves 2 are arranged on the outer periphery of the drill body 1 at intervals in the circumferential direction, and can also be applied to a drill having three or more blades in which three or more tip blades 20 are formed. It is.

In the drill 10 of the present embodiment, the drill body 1 is formed of a hard material such as cemented carbide, but the material of the drill body 1 is not limited to this. Further, the blade portion of the drill body 1 may be coated with a coating film such as a diamond film.

The drill 10 of this embodiment is a solid type integrally formed drill. However, the same configuration can be applied to a drill head that is detachably attached to the tip of the tool body of a replaceable cutting edge drill or a drill head that is fixedly attached to the tip of the tool body by brazing or the like. Applicable.
That is, although not particularly illustrated, this reference example is formed on the outer periphery of the head main body (corresponding to the drill main body 1 described in the above-mentioned reference example) rotating around the axis O together with the tool main body, A chip discharge groove 2 extending from the front end of the head body toward the base end side of the head main body along the axis O direction, a wall surface 2a facing the drill rotation direction T of the chip discharge groove 2, and a front end face 6 of the head main body. The present invention can also be adopted for a drill head provided with a tip blade 20 formed at an intersecting ridge line portion.

Second Embodiment
FIG. 5 is a side view of the drill 110 of the second embodiment. FIG. 6 is a front view of the drill 110 as viewed from the distal end surface side.
Compared with the drill 10 described in the above-described embodiment, the drill 110 of the present embodiment mainly differs in the configuration of the tip blade 120. Detailed description of the same components as those in the first embodiment is omitted.

The drill 110 of the present embodiment has a drill body 101 formed in a substantially cylindrical shape with the axis O as the center. On the outer periphery of the drill body 101, a chip discharge groove 102 and an outer peripheral blade 104 formed along the chip discharge groove 102 are provided. A tip blade 120 is provided on the tip surface 106 of the drill body 101.

The leading edge 120 is formed at the intersecting ridge line portion between the wall surface 102 a facing the drill rotation direction T of the chip discharge groove 102 and the distal end surface 106 of the drill body 101. A gash rake face 102c is formed at a part of the tip of the wall face 102a. As in the first embodiment, the gash rake face 102c is formed to be parallel to the axis O.

The leading edge 120 of the drill 110 has a first leading edge 121, a second leading edge 122, and a third leading edge 123.
The first tip blade 121, the second tip blade 122, and the third tip blade 123 extend from the radially inner side toward the radially outer side, respectively. The first tip blade 121, the second tip blade 122, and the third tip blade 123 are arranged in this order from the radially inner side to the radially outer side.

The first tip blade 121 extends in a direction inclined toward the base end side in the axis O direction as it goes radially outward. The first tip blade 121 of the present embodiment has a smaller angle with respect to the axis O as compared to the first embodiment. The first tip 121 is a portion that first comes into contact with the work material when the drill 110 is brought close to the work material along the axis O. By reducing the angle of the first tip edge 121 with respect to the axis O, the stability of the drill when the drill 110 bites the work material can be enhanced. Therefore, the drill 110 of this embodiment is suitable for use as a hand drill.

The second tip blade 122 is disposed on the radially outer side of the first tip blade 121. The second tip edge 122 extends in a direction inclined toward the tip side in the axis O direction as it goes radially outward. The second tip blade 122 extends while being inclined to the side opposite to the first tip blade 121.

The third tip 123 has a first straight part 123e and a second straight part 123f located on the radial direction and side of the first straight part 123e. The first straight portion 123e and the second straight portion 123f linearly extend in a direction inclined toward the proximal end side in the axis O direction as going outward in the radial direction. The inclination of the second straight line portion 123f is larger than the inclination of the first straight line portion 123e. Moreover, the inclination with respect to the axis line O becomes small as the 3rd front-end | tip blade 123 goes to radial direction outer side from radial inner side.

The first straight edge portion 123e of the first tip blade 121, the second tip blade 122, and the third tip blade 123 is a radial view in the front view of the drill when the drill body 101 is viewed from the tip end in the axis O direction toward the base end side. It extends so that. Accordingly, the first straight portion 123e of the first tip blade 121, the second tip blade 122, and the third tip blade 123 of the present embodiment is set so that the center height is zero, not the center rise or the center fall. Yes.

The first straight edge portion 123e of the first tip blade 121, the second tip blade 122, and the third tip blade 123 is located at the intersecting ridge line between the gash rake face 102c and the tip face 106. The gash rake face 102 c functions as a rake face for the first straight portion 123 e of the first tip edge 121, the second tip edge 122, and the third tip edge 123.

The rake face (gash rake face 102c) of the first straight edge 123e of the first tip edge 121, the second tip edge 122, and the third tip edge 123 is formed to be parallel to the axis O of the drill body 101. . Therefore, the axial rake angle (axial rake angle) of the first straight edge 123e of the first tip blade 121, the second tip blade 122, and the third tip blade 123 is a negative angle (0 °) over the entire blade length. ing.

The rake angle in the axial direction of the first straight portion 123e of the first tip blade 121, the second tip blade 122, and the third tip blade 123 is a negative angle (0 °), and the center height is zero. Accordingly, the rake angle in the radial direction of the first straight portion 123e of the first tip blade 121, the second tip blade 122, and the third tip blade 123 is a negative angle (0 °).

According to the present embodiment, when a work material such as CFRP having one direction as the fiber direction is drilled, generation of burrs or the like is remarkable even in a region where the blade edge rotates in a direction opposite to the fiber direction of the work material. Can be suppressed. That is, according to the present embodiment, the cutting edges of the first straight portion 123e of the first tip blade 121, the second tip blade 122, and the third tip blade 123 cut into the opposite direction with respect to the fiber direction of the work material. Since the cutting edge cuts perpendicularly to the fiber direction, the occurrence of uncut fibers can be suppressed.

<Third Embodiment>
FIG. 7 is a side view of the drill 210 of the third embodiment. FIG. 8 is a front view of the drill 210 as seen from the distal end surface side.
Compared with the drill 10 described in the above-described embodiment, the drill 210 of the present embodiment mainly differs in the configuration of the rake angle of the tip blade 220. Detailed description of the same components as those in the first embodiment is omitted.

The drill 210 of the present embodiment includes a drill body 201 provided with a chip discharge groove 202 and an outer peripheral blade 204 formed along the chip discharge groove 202. A tip blade 220 is provided on the tip surface 206 of the drill body 201. The tip blade 220 is formed at the intersecting ridge line portion between the wall surface 202 a facing the drill rotation direction T of the chip discharge groove 202 and the tip surface 206 of the drill body 201.
A gash rake face 202c is formed at a part of the tip of the wall face 202a. The gash rake face 202c is formed to be parallel to the axis O.

The leading edge 220 of the drill 210 has a first leading edge 221, a second leading edge 222, and a third leading edge 223.
The first tip blade 221, the second tip blade 222, and the third tip blade 223 each extend from the radially inner side toward the radially outer side. The first tip blade 221, the second tip blade 222, and the third tip blade 223 are arranged in this order from the radially inner side to the radially outer side.

As shown in FIG. 8, the first tip blade 221, the second tip blade 222, and the third tip blade 223 have a diameter in a front view of the drill when the drill body 201 is viewed from the tip in the axis O direction toward the base end. It extends along the direction. Therefore, the first tip blade 221, the second tip blade 222, and the third tip blade 223 of the present embodiment are set so that the center height is zero, not the center rise or the center fall.

In the present embodiment, the radial rake angle (radial rake angle) in the radially outermost peripheral portion 223a of the third tip blade 223 is a negative angle (0 °). Thereby, since the cutting edge is cut into the cutting edge of the work material at an obtuse angle, it is difficult to apply a load between the fibers, and separation between the fibers can be suppressed.

In addition, in the range which does not deviate from the meaning of this invention, you may combine each structure (component) demonstrated by the above-mentioned embodiment, a modification, and a note, etc., addition of a structure, omission, substitution, others It can be changed. Further, the present invention is not limited by the above-described embodiments, and is limited only by the scope of the claims.

According to the present invention, it is possible to stably improve the finishing accuracy of the inner periphery of a processed hole formed by drilling a work material. Therefore, it has industrial applicability.

DESCRIPTION OF SYMBOLS 1,101,201 ... Drill main body 2,102,202 ... Chip discharge | emission groove | channel 2a, 2b, 102a, 202a ... Wall surface 2c, 102c, 202c ... Gash rake face (rake face of 1st front-end | tip cutting edge)
4, 104, 204 ... outer peripheral blade 6, 106, 206 ... tip surface 10, 110, 210 ... drill 20, 120, 220 ... tip blade 21, 121, 221 ... first tip blade 21a ... inner portion 21b ... outer portion 21c ... innermost peripheral part 22, 122 ... second tip blade 23, 123 ... third tip blade 23a, 223a ... outermost peripheral part 24 ... boundary vertex 61 ... first flank 61a ... primary tip flank 61b ... secondary tip flank Surface 62 ... Second flank 63 ... Third flank D ... Maximum diameter d24 ... Diameter O ... Axis T ... Drill rotation direction θ23a ... Radial rake angle

Claims (8)

A drill body that rotates about an axis;
A chip discharge groove formed on the outer periphery of the drill body and extending from the tip of the drill body toward the base end side of the drill body so as to be along the axial direction;
A tip blade formed on a cross ridge line portion between the wall surface of the chip discharge groove facing the drill rotation direction and the tip surface of the drill body, and
The tip blade is
A first tip blade extending toward the base end side in the axial direction as it goes radially outward;
A second tip blade that is disposed radially outside the first tip blade and extends toward the tip end side in the axial direction as it goes radially outward;
A third tip blade that is arranged radially outward of the second tip blade and extends toward the base end side in the axial direction as it goes radially outward;
A boundary vertex located at a boundary between the second tip blade and the third tip blade;
The said boundary vertex is a drill located in the base end side of the said axial direction from the innermost peripheral part of the said 1st front-end | tip blade. The drill according to claim 1, wherein the third tip edge has a positive rake angle in the radial direction at the outermost peripheral portion in the radial direction. The first tip blade extends in a radial direction perpendicular to the axis in a front view of the drill when the drill body is viewed from the tip in the axial direction toward the base end.
The drill according to claim 1 or 2, wherein a rake face of the first tip edge is parallel to the axis. The drill according to any one of claims 1 to 3, wherein a diameter of a rotation locus of the boundary vertex is 50% or more with respect to a maximum diameter of the drill body. The third tip blade is inclined in a direction away from the axis as it goes toward the base end side, and the inclination with respect to the axis decreases as it goes from the radially inner side to the radially outer side. The drill according to any one of the above. A primary tip flank continuous to the rotational rear side of the first tip blade;
The drill according to any one of claims 1 to 5, further comprising a secondary tip flank continuous to the rotational rear side of the primary tip flank. The drill according to any one of claims 1 to 6, wherein in the axial direction, the second tip edge overlaps with an area of 30% or more of the first tip edge. A drill head mounted on the tip of the tool body,
A head body that rotates about an axis together with the tool body;
A chip discharge groove formed on the outer periphery of the head main body and extending from the tip of the head main body toward the base end side of the head main body along the axial direction;
A tip blade formed at a cross ridge line portion between the wall surface of the chip discharge groove facing the drill rotation direction and the tip surface of the head body,
The tip blade is
A first tip blade extending toward the base end side in the axial direction as it goes radially outward;
A second tip blade that is disposed radially outside the first tip blade and extends toward the tip end side in the axial direction as it goes radially outward;
A third tip blade that is arranged radially outward of the second tip blade and extends toward the base end side in the axial direction as it goes radially outward;
A boundary vertex located at a boundary between the second tip blade and the third tip blade;
The boundary apex is a drill head positioned on the proximal end side in the axial direction from the innermost peripheral portion of the first tip edge.

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