JP2007260843A - Drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill extended in life, which prevents occurrence of burring and scuffing in drilling work on a composite material of CFRP or the like. <P>SOLUTION: The drill is constituted by forming a chip discharging groove 13 extending toward the rear end side on an outer periphery of a cutting blade part 12 provided on the head end side of a drill main body 10 rotated around an axis O, and also by forming a cutting blade 16 on a crossing crest line part of an inner wall surface 13A directed to the front side in the drill rotating direction T of this chip discharging groove 13. A radial rake angle on an outer peripheral end 13B of the chip discharging groove 13 is set within a range from +5° to +25°, a radial rake angle of the cutting blade 16 formed on the head end flank 15 is set within a range from -20° to 0°, and a head end angle α of the drill main body 10 is set within a range from 80° to 120° on a cross-section orthogonal with the axis O of the cutting blade part 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drill used for drilling a composite material such as a carbon fiber reinforced plastic (CFRP) used as an aircraft material.

Conventionally, various drills as shown in, for example, Patent Document 1 and Patent Document 2 have been proposed as drills for drilling a composite material.
Patent Document 1 discloses a drill in which R is provided at an outer peripheral corner portion, a negative land is provided at a cutting edge, and a tip angle is 125 to 145 °. Patent Document 2 discloses a drill in which a back taper portion is provided on the front end side of the cutting blade portion, and a small diameter portion having a constant outer diameter is formed on the rear end side of the back taper portion.
JP 2002-326109 A Japanese Patent Laid-Open No. 08-71824

  By the way, CFRP used as an aircraft material is a composite material reinforced by mixing carbon fiber in plastic, and when this CFRP is drilled, when the drill comes out from the opening end of the drilled hole In addition, the so-called fuzz that the carbon fibers protrude from the peripheral edge of the processed hole opening end toward the inner peripheral side of the processed hole may occur, or burrs may occur on the peripheral edge of the open end.

The drill disclosed in Patent Document 1 drills a metal matrix composite (MMC: Metal Matrix Composite) in which reinforcing particles such as SiC or Al ₂ O ₃ are dispersed in a metal such as aluminum or copper. It is. When CFRP drilling is performed using this drill, fluffing and burrs are generated at the opening end of the processing hole, as in the case of a normal drill.

In addition, the drill disclosed in Patent Document 2 drills a composite material in which CFRP and a titanium alloy or the like are laminated. The small diameter portion reduces sliding friction between the drill and the titanium alloy to suppress wear of the cutting edge, and cannot suppress fuzz and burrs that occur when processing with CFRP alone.
As described above, a drill capable of satisfactorily drilling a composite material such as CFRP has not been proposed so far.

  The present invention has been made in view of such circumstances, and it is possible to prevent the occurrence of burrs and fluff when drilling a composite material such as CFRP, and to extend the lifetime. An object is to provide a drill that can be used.

  In order to solve such a problem, the present invention is formed with a chip discharge groove extending toward the rear end side on the outer periphery of the cutting edge portion provided on the tip side of the drill body rotated about the axis, In the drill in which the cutting edge is formed at the intersecting ridge line portion between the inner wall surface facing the front side in the drill rotation direction of the chip discharge groove and the tip flank surface of the cutting blade portion, in a cross section orthogonal to the axis of the cutting blade portion The radial rake angle at the outer peripheral end of the chip discharge groove is set in the range of + 5 ° to + 25 °, and the radial rake angle of the cutting edge formed on the tip flank is -20 ° to 0 °. The tip angle of the drill body is set in the range of 80 ° to 120 °.

  In the drill having this configuration, since the tip angle is set to 120 ° or less, the cutting amount per one rotation of the drill is small, and when the drilled hole opens on the side opposite to the drill insertion side, the opening end gradually Processed to widen and prevent the generation of burrs without leaving a thin unprocessed part at the periphery of the opening end, and to extend toward the inner peripheral surface of the processing hole at the opening end of the processing hole The cutting blades intersect with the carbon fibers that are formed at an angle, and the carbon fibers are surely cut to prevent fuzz. However, if the tip angle α is too small, the force that pushes the hole opening end toward the outer periphery becomes strong, and there is a risk that fluffing and burrs are likely to occur. Therefore, the tip angle α is from 80 °. Within a range of 120 °. Furthermore, by setting the tip angle to 80 ° or more, the rigidity of the tip of the drill is ensured, and drill breakage due to cutting resistance is prevented.

  Further, the radial rake angle at the outer peripheral end of the chip discharge groove, that is, the angle formed by the direction in which the outer peripheral end of the chip discharge groove extends and the radial direction of the drill body in the cross section orthogonal to the axis is + 5 ° or more. The direction in which the outer peripheral end of the discharge groove extends is inclined so as to face the front side of the drill rotation direction rather than the radial direction of the drill body, so that the resistance when the inner peripheral wall of the machining hole and the outer peripheral end are in sliding contact with each other is kept small. Thus, the occurrence of fluff due to such sliding contact can be prevented. Furthermore, since the radial rake angle at the outer peripheral end is set to + 25 ° or less, the rigidity of the outer peripheral end is ensured, and drill breakage can be prevented.

  In addition, since the radial rake angle of the cutting edge is set to -20 ° or more, the cutting resistance acting on the cutting edge can be kept relatively small, and the cutting with respect to the work material becomes sharp and the cutting is performed well. It is possible to prevent the occurrence of fuzz and burrs. Furthermore, since the radial rake angle of the cutting edge is 0 ° or less, the rigidity of the cutting edge is secured and the cutting edge is prevented from being lost.

  Here, by covering the surface of the cutting edge part with a hard coating, the wear resistance of the cutting edge can be improved and the life of the drill can be extended. As the hard film, diamond coating by CVD method, ceramic coating such as TiN, TiCN, TiAlN by PVD method can be adopted.

  Furthermore, by drilling a fluid supply hole that opens in the tip flank in the drill body, when performing cutting, air or the like can be supplied to the cutting blade through the fluid supply hole, The temperature rise of the cutting blade is suppressed and chip discharge is promoted.

  ADVANTAGE OF THE INVENTION According to this invention, when drilling with respect to composite materials, such as CFRP, the drill which can prevent generation | occurrence | production of a burr | flash and fluff and can aim at the extension of a lifetime can be provided.

  The drill which is embodiment of this invention is demonstrated using attached drawing. FIG. 1 shows a drill according to an embodiment of the present invention. This drill is used when drilling holes in CFRP.

  As shown in FIG. 1, the drill according to the present embodiment has a drill body 10 having a substantially cylindrical shape centering on an axis O, and a rear end side (upper side in FIG. 1) of the drill body 10 is The shank portion 11 is held by the spindle end of the machine tool, and the distal end side (the lower side in FIG. 1) of the drill body 10 is the cutting edge portion 12.

On the outer periphery of the cutting edge portion 12, a pair of chip discharge grooves 13 that are twisted toward the rear side in the drill rotation direction T with a constant twist angle as it goes toward the rear end side in the axis O direction are formed symmetrically with respect to the axis O. ing.
Further, the outer peripheral surface of the cutting edge portion 12, that is, a portion of the cutting edge portion 12 other than the portion where the chip discharge groove 13 is formed is a land portion 14, which is the same as the chip discharge groove 13. Further, it is formed so as to be twisted to the rear side in the drill rotation direction T as it goes toward the rear end side in the axis O direction.

  Then, when the cutting edge portion 12 is viewed in a cross section orthogonal to the axis O, as shown in FIG. 2, the intersecting ridge line portion between the land portion 14 and the inner wall surface 13A facing the front side in the drill rotation direction T of the chip discharge groove 13 is It is projected so as to protrude forward in the drill rotation direction T. In other words, the extending direction of the outer peripheral end 13B of the inner wall surface 13A facing the front side of the drill rotation direction T of the chip discharge groove 13 is inclined to the front side of the drill rotation direction T rather than the radial direction of the drill body 10. In the present embodiment, the angle formed by the extending direction of the outer peripheral end 13B of the inner wall surface 13A and the radial direction of the drill body 10, that is, the radial rake angle θ1 at the outer peripheral end 13B is in the range of + 5 ° to + 25 °. Is set to

  A tip end face 10A of the drill body 10 connected to the inner wall surface 13A facing the front side of the drill rotation direction T of the chip discharge groove 13 is a tip flank 15, and the tip flank 15 extends from the axis O to the rear of the drill body 10. The drill body 10 is inclined toward the outer side in the radial direction toward the end side, and the distal end surface 10A of the drill body 10 has a V-shape projecting toward the distal end side of the drill body 10 in a side view. Yes. This V-shaped crossing angle, so-called tip angle α, is set within a range of 80 ° to 120 °, and is set to 90 ° in the present embodiment.

  The tip flank 15 is continuous with the first flank 15A continuous with the cutting edge 16 and the rear side of the first flank 15A in the drill rotation direction T, and gives a clearance angle larger than the clearance angle of the first flank 15A. The second flank 15B is formed in a multi-step shape. In the present embodiment, the clearance angle of the first flank 15A is 10 °, the clearance angle of the second flank 15B is 30 °, and the cutting edge 16 is directed toward the rear side in the drill rotation direction T. Therefore, escape is given that increases in multiple steps.

  Further, the tip surface 10A of the drill body 10 has an area from a wall surface portion facing the radially outer side of the drill body 10 of the chip discharge groove 13 to a position close to the axis O located at the center of the drill body 10 tip surface 10A. The center of the drill tip surface 10A intersects with the inner peripheral end side of the cutting edge 16 by being obliquely cut out toward the front side of the drill rotation direction T along the tip side in the axis O direction. A thinning surface 17 is formed extending toward the axis O located at the position. Accordingly, a thinning cutting edge 18 having a substantially linear shape extending toward the axis O is disposed at a portion on the inner peripheral end side of the cutting edge 16.

  When the drill body 10 is viewed from the tip, as shown in FIG. 3, a thinning cutting edge 18 that extends linearly from the axis O is disposed, and the thinning cutting edge 18 has a drill rotation direction T rear side at the outer peripheral end. A cutting edge 16 having a concave curve shape that is recessed toward is provided continuously. However, the outer peripheral end side of the cutting edge 16 is bent so as to be directed toward the rear side of the drill rotation direction T in the radial direction with respect to the axis O or toward the outer peripheral side when viewed from the front end. The radial rake angle θ2 at the outer peripheral end of the cutting edge 16 is set within a range of −20 ° to 0 °.

Further, the cutting edge portion 12 is provided with a diamond coating by a CVD method as a hard film.
Furthermore, a fluid supply hole 19 that opens to the front end surface 10 </ b> A of the drill body 10 and penetrates to the rear end side of the drill body 10 is formed in the drill body 10.

  In the drill having the above-described configuration, the shank portion 11 formed at the rear end of the drill body 10 is gripped by the spindle end of the machine tool and rotated around the axis O and at the front end side in the axis O direction. It is sent toward and pressed against the material to be cut to form a processed hole having a predetermined inner diameter in the material to be cut. When cutting with this drill, air is supplied toward the vicinity of the cutting edge 16 through a fluid supply hole 19 formed in the drill body 10.

  According to the drill of this embodiment, the tip angle α is set in the range of 80 ° to 120 °, and more specifically 90 °, so that the cutting amount per one rotation of the drill is small. When the processed hole opens on the other surface, the opening is processed so as to gradually widen, so that a thin unprocessed portion does not remain largely at the edge of the opening, It can suppress that a burr | flash generate | occur | produces from an opening part. In addition, the cutting edge 16 intersects the carbon fibers arranged so as to extend toward the inner peripheral surface of the processing hole at the opening, so that the carbon fibers can be reliably cut and fluffed. Can be suppressed. Further, it is possible to prevent the tip angle α from becoming too small and increase the force with which the opening end of the processing hole is pushed to the outer peripheral side, and it is also possible to prevent the occurrence of fluff and burrs. Furthermore, since the rigidity of the tip of the drill body 10 is ensured, it is possible to prevent the drill from being broken due to cutting resistance.

  Further, when the cutting edge portion 12 is viewed in a cross section perpendicular to the axis O, the direction in which the outer peripheral end 13B of the inner wall surface 13A that faces the front side of the drill rotation direction T of the chip discharge groove 13 extends more than the radial direction of the drill body 10. The angle formed between the direction in which the outer peripheral end 13B of the inner wall surface 13A extends and the radial direction of the drill body 10, that is, the radial rake angle θ1 at the outer peripheral end 13 is + 5 ° to + 25 °. Therefore, the resistance when the inner peripheral wall of the machining hole and the outer peripheral end 13B of the inner wall surface 13A facing the front side of the drill rotation direction T of the chip discharge groove 13 are in slidable contact is kept small. In addition to preventing fluffing of the carbon fiber, it is possible to ensure the rigidity of the outer peripheral end 13B and to prevent defects.

  Further, since the radial rake angle θ2 of the cutting edge 16 is set to −20 ° or more, the cutting resistance acting on the cutting edge 16 can be suppressed to a small level, and the cutting with respect to the CFRP becomes sharp and the cutting process is performed well. Can do. Furthermore, since the radial rake angle of the cutting edge 16 is set to 0 ° or less, the rigidity of the cutting edge 16 is ensured, and the cutting edge 16 can be prevented from being broken due to cutting resistance.

  Furthermore, since the cutting edge portion 12 is coated with diamond, it is possible to extend the life of the drill by improving the wear resistance of the outer peripheral edge 13B of the cutting edge 16 and the chip discharge groove 13. Further, since the wear of the cutting edge 16 is prevented, the CFRP can be cut with the sharp cutting edge 16 for a long period of time, and the occurrence of fuzz and burrs can be prevented.

  Further, since the drill body 10 has an opening in the distal end surface 10A of the drill body 10 and has a fluid supply hole 19 that penetrates to the rear end side of the drill body 10, when performing cutting, Air can be supplied to the cutting blade 16 through the fluid supply hole 19, and the life of the cutting blade 16 can be extended by suppressing the temperature rise of the cutting blade 16. For example, even when forming a deep hole, the discharge of chips is promoted by air, so that cutting can be performed satisfactorily.

  As described above, according to the drill of this embodiment, when drilling a CFRP, it is possible to prevent the occurrence of burrs and fluff, and to prevent the chipping and wear, thereby extending the life of the drill. .

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, in the present embodiment, the surface of the cutting edge portion 12 has been described as being subjected to diamond coating. However, the present invention is not limited thereto, and for example, a ceramic coating such as TiN, TiCN, or TiAlN may be coated. However, these hard coatings may not be coated.

Moreover, although the drill which formed the fluid supply hole 19 in the inside of the drill main body 10 was demonstrated, it is not limited to this, The drill in which the fluid supply hole 19 is not formed may be sufficient.
Further, the drill shape such as the back taper and the clearance angle of the cutting edge 16 is not limited to this embodiment, and is preferably set as appropriate in consideration of the shape of the work material and the processing conditions. However, the tip angle α is 80 ° to 120 °, the radial rake angle θ2 of the cutting edge 16 is −20 ° to 0 °, and the radial rake angle θ1 at the outer peripheral end 13B of the chip discharge groove 13 is in the range of + 5 ° to + 20 °. It is necessary to set so that

Below, the result of the comparative experiment conducted in order to confirm the effect of this invention is demonstrated. In this comparative experiment, drilling was performed on a CFRP having a thickness of 5 mm using a drill with a changed tip angle, and the occurrence of burrs and fuzz at the opening end of the processed hole was confirmed. Cutting conditions were a cutting speed of 128 m / min, a feed speed of 0.06 mm / rev, and no cutting oil was used.
The experimental results are shown in Table 1.

As shown in Table 1, when the tip angle was 140 °, large burrs were recognized along with fluffing. Further, when the tip angle was 40 °, fuzz was confirmed. On the other hand, when the tip angle was 90 ° and 120 °, neither fuzz nor burrs were observed.
From this experimental result, it was confirmed that the occurrence of fuzz and burrs can be effectively suppressed by setting the tip angle within the range of the present invention.

It is a side view of the drill which is embodiment of this invention. It is XX sectional drawing in FIG. It is a Y direction arrow directional view in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Drill main body 12 Cutting edge part 13 Chip discharge groove 13B Perimeter end 16 Cutting edge 19 Fluid supply hole

Claims (3)

A chip discharge groove extending toward the rear end side is formed on the outer periphery of the cutting edge portion provided on the tip side of the drill body rotated about the axis, and the inner wall surface facing the front side in the drill rotation direction of the chip discharge groove In the drill in which the cutting edge is formed at the intersecting ridge line part between the tip flank and the cutting edge part,
In the cross section perpendicular to the axis of the cutting edge portion, the radial rake angle at the outer peripheral end of the chip discharge groove is set within a range of + 5 ° to + 25 °, and the cutting edge formed on the tip flank The radial rake angle of the blade is set within the range of -20 ° to 0 °,
The drill characterized in that the tip angle of the drill body is set within a range of 80 ° to 120 °.   The drill according to claim 1, wherein a surface of the cutting edge portion is coated with a hard coating.   The drill according to claim 1 or 2, wherein the drill body is provided with a fluid supply hole that opens to the tip flank.

Images