JP3098465B2 - Drilling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In the drilling of composite materials such as wood-based, resin-based, and ceramic-based interior wall construction materials and ceiling construction materials with decorative paper on the surface, finishing holes with little swelling or fluffing on the hole surface are used. For drilling tools to obtain.

[0002]

2. Description of the Related Art In the drilling of composite materials such as hard woods and synthetic resin materials, with a twist drill having a normal conical blade, there are many burrs and burrs in the drilled holes of a workpiece and cracks are generated. It is easy and difficult to process, requiring post-processing to remove burrs and the like. Then, the actual opening 61-393
No. 06 discloses a cutting edge shape commonly referred to as a crown shape as shown in FIG. 4 for drilling such a composite material or the like. This is the outer peripheral groove 4 of the drill 41
6, a hole edge cutting edge 43 whose tip protrudes in an outer diameter of the drill tip following the outer peripheral cutting edge 42, a chisel edge 44 which protrudes in the center of the drill tip, a hole edge cutting edge and a chisel edge. It comprises a concave cutting edge 45 provided in a concave shape between them. With this configuration, the processing center is caught by the central chisel edge 44, the fluctuation of the processing center position is eliminated, and further, the hole edge cutting edge 43 makes a cut line in the hole edge, and subsequently, the concave cutting edge 45 performs processing. Drilling is performed by cutting the surface in earnest.

[0003]

However, such a crown-shaped cutting edge has a large cutting force because it cuts all over the cutting edge when drilling. In particular, the protruding chisel edge 44 and the hole edge cutting edge 43 are barbed, and the stress at the edge is large. In addition, chisel edge 44, hole edge cutting edge 43, concave cutting edge 4
In No. 5, the respective cutting edge angles are different, and the chips tend to flow out in a direction substantially perpendicular to the cutting edges, so that the chips generated from the cutting edges tend to face different directions. For this reason, a tensile / compression force is generated between the chips, and a large stress is locally generated at the cutting edge. In particular, as the hole becomes deeper, the chip discharge resistance increases. There is a problem that the cutting edge 43 is easily chipped.

The hole cutting edge 43 has a positive rake angle in the axial direction due to the twist angle α of the outer peripheral groove 46, but the rake angle in the radial direction is very small. Therefore, the effective rake angle acting during actual cutting is limited to the rake angle only in the axial direction, and there is a problem that the sharpness is insufficient to cut the paper portion on the surface with less fluff. Furthermore, since the surface to be processed is pressed by the chisel edge 44 at the beginning of processing, the material is cut off at the edge of the hole while being pulled from the center or below, so that there is a problem that burrs and fluffing are likely to occur depending on the fiber direction. .

Further, a protruding blade comprising a chisel edge 44 and two hole edge cutting edges 43 at a small tip of the drill, and a concave cutting edge 45 between the chisel edge and the hole edge cutting edge must be formed. In addition, it is difficult to freely set the cutting edge, and there is a problem that a dedicated whetstone and skill are required for processing, which requires man-hours and cost.

On the other hand, the above-mentioned hole edge cutting blade is not a barbed
A crescent-shaped thin blade formed along the outer periphery, for example, Japanese Utility Model Laid-Open No. 56-33111, Japanese Patent Laid-Open No. 58-14911
Although there is one disclosed in Japanese Patent Application Publication No. 4 (1999) -1995, it has a problem that it is easily chipped and its sharpness is easily deteriorated like a stab-shaped one because it is a thin blade.

[0007] The object of the present invention is to solve the above problems.
It is an object of the present invention to provide a drilling tool in which, of course, there is no generation of burrs, burrs, etc., and there is no chipping of the cutting edge, and the sharpness of the cutting edge for a hole edge is enhanced. In particular, the cutting edge can be freely set to enhance cutting edge performance and cutting edge strength, making it easy to machine.
It is to provide a low-cost drilling tool.

[0008]

According to the present invention, a tip of a twist drill having at least two or more grooves is provided with a protruding blade having an apex at an edge of a hole to be machined, and is axially retreated from the front end of the protruding blade. To provide a drilling tool in which a flat blade extending in the axial direction from an outer peripheral end and a relief portion provided between the protruding blade and the flat blade retreated from the flat blade. Solved the above problem. However, the protruding blade is provided with a cutting edge in the direction of the discharge groove corresponding to one groove, and has a substantially right-angled triangular shape with the tip of the hole edge to be machined as the apex and the outer peripheral side as the vertical side when viewed from the circumferential direction, When viewed from the direction, it was formed into a substantially triangular shape having a tip portion as a vertex and projecting toward the discharge groove side, and an axial rake face was formed on the groove side face, and a shaft flank face was formed on the end side. In addition, a margin portion having a clearance angle in a direction perpendicular to the radius and provided along the outer periphery next to the distal end portion as viewed from the axial direction, and a radial rake surface extending in the axial direction from the distal end portion are formed. The cutting edge was formed on the flat blade by extending from the axis along a straight line passing through the outer peripheral end of the drill and the axis in the direction of the discharge groove corresponding to the other grooves.

In order to ensure the sharpness of the projection blade,
The hypotenuse of the substantially right-angled triangle viewed from the circumferential direction has an inclination angle of 20 ° to 50 ° with respect to the axis, the rake angle of the axial rake face viewed from the radial direction is the same as the torsion angle of the groove, and the flank of the flank perpendicular to the axis The angle is 20 ° to 35 ° in the direction perpendicular to the axis, the flank angle of the flank in the radial direction of the margin portion viewed from the axial direction is 8 ° to 15 ° in the direction perpendicular to the radius, and the rake angle of the rake face in the radial direction is 5 ° to 5 °. It is good to be 20 degrees.

In order to further prevent the chipping of the blade, a chamfer having an axial rake angle of 0 ° to 30 ° with a width of 0.5 mm or less in the axial direction from the tip of the axial rake face viewed from the radial direction of the protruding blade is provided. Good.

The flat blade has an inclination angle of 85 ° to 95 ° with respect to the axis, and the length of the flat blade in the radial direction is more than 1/2 of the drill diameter and not more than 2/3. The maximum height of the cutting edge may be set back from the tip of the projection blade by 0.3 to 1.0 mm.

[0012] The height of the relief is 0.3 from the minimum height of the flat blade.
It is better to retract by at least mm.

(Operation) When the drill having such a configuration is attached to a processing machine and is advanced while rotating, the tip of the projection blade comes into contact with the paper layer on the surface of the work material. The protruding blade has an axial rake face and a radial rake face, and has a large effective rake angle, so that it is sharp. 0.3 ~ from the tip of the protruding blade to the flat blade
Since it is retracted by 1.0 mm, the upper layer surface such as a paper layer is first cut open in a ring shape. At this time, since the force applied to the work material is only due to the small projection blade, the elastic deformation of the work material due to the application of the force is small and stable. Kebabs can be kept small.

The hypotenuse of the substantially right-angled triangular shape of the protruding blade has a smaller rake face in the radial direction when the inclination angle is 20 ° or less with respect to the axis, and the cutting edge strength is reduced. Therefore, the angle was set to 20 ° to 50 °. The rake angle in the axial direction was the same as the torsion angle of the groove from the viewpoint of processing and easiness. The clearance angle in the direction perpendicular to the axis is 20 °
If it is less than the above, the paper layer or the like cut and opened on the ring will be rubbed and the separation will be poor. When the angle is 35 ° or more, the cutting edge strength decreases, so that the angle is set to 20 ° to 35 ° in the direction perpendicular to the axis. The clearance angle in the direction perpendicular to the radius of the margin viewed from the axial direction is the same as that of a general drill because after drilling, it behaves in the same manner as a general drill. 8 ° to 15 °. The sharpness of the rake angle in the radial direction is better when sharp, but the strength is insufficient at 20 ° or more and the sharpness is poor at 5 ° or less, so the rake angle in the radial direction is 5 ° to 2 °.
0 °.

Subsequent to the protruding blade, the flat blade reaches the surface, and the flat blade cuts the inside of the hole rim with the circumferential portion being cut open by the protruding blade. Since the flat blade extends along the axis from the outer diameter edge and extends from the axis, a cutting width larger than the drill radius and a large flank in the flank direction can be formed, so that the flat blade can withstand heavy cutting load and reliably cut the inside of the hole edge. Flat blades have a large cutting resistance and cause local deformation in soft building materials, but the circumference is already opened with a protruding blade, so outside the processing diameter there is almost no effect of deformation, leaving a good appearance .

When the flat blade is at an angle of 95 ° or more with respect to the axis, cutting chips are pushed out in the radial direction. When the flat blade is at an angle of 85 ° or less, the step with the protruding blade becomes large and the proportion of the protruding blade burdens the shaft. The inclination angle was set to 85 ° to 95 ° with respect to the right angle plane. The length of the flat blade in the radial direction was set to more than １ ／ and 以下 or less of the drill diameter similar to the bottom blade of a square end mill for so-called groove processing. The reason why the dimension of the clearance is 0.3 mm or more is to prevent cutting chips cut by the flat blade from being caught by the clearance.

Further, even when the hole is deepened, the main cutting is borne by a high-strength flat blade, so that the protruding blade is only responsible for a small cutting amount, so that the load of the force is small and the blade is not easily chipped, and a sharp sharpness can be maintained. .

When the building material layer is hard, or when hard particles and fines are mixed, the width of the projection blade is increased, or the angle of the chamfer on the rake face is reduced. If the width of the chamfer exceeds 0.5 mm, the sharpness will decrease,
The width of the chamfer was set to 0.5 mm or less. If the axial rake angle of the chamfer exceeds 30 °, it is almost the same as the groove and there is no effect, and if the negative angle (minus angle) decreases the sharpness, the axial rake angle of the chamfer is set to 0 ° to 30 °.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings, in which the present invention is applied to a twist drill having two twist grooves. FIG. 1 is a front view of an end of a drilling tool according to an embodiment of the present invention viewed from an axial direction, FIG. 2 is a partial side view of the end viewed from an arrow A in FIG. 1, and FIG. It is the partial side view seen from arrow B of No. 2. As shown in FIGS. 1 and 2, a projecting blade having a vertex (tip 4) at the tip 3 of a twist drill having at least two or more grooves 1 and 2 at the tip 3 of the hole drilling tool. 5 are formed. A flat blade 8 is provided which is retreated in the axial direction from the distal end 4 of the protruding blade 5 and extends from the outer peripheral end 6 in the direction of the axis 7. The dimension 9 from the protruding blade distal end to the flat blade is 0.3 to 1.0 mm. It is to be. further,
Retracted portion 1 between projection blade 5 and flat blade 8 retracted from flat blade 8
0 is provided. The dimension 11 between the flat blade and the relief is 0.
It is 3 mm or more.

The protruding blade 5 is provided with a cutting blade 12 in the direction of the discharge groove corresponding to one groove 1, and as shown in FIG. A margin portion 14 having a radial right-angle clearance angle 13 of 8 ° to 15 ° in the direction and a radial rake surface 16 having a radial rake angle 15 extending from the tip in the axial direction and having a radial rake angle of 5 ° to 20 ° are formed. . As shown in FIG. 2, when viewed from the circumferential direction, the outer edge 1
The oblique side 18 has a slant angle 19 of 20 ° to 50 ° with respect to the axis.

As shown in FIG. 3, the protruding blade 5 has a substantially triangular shape projecting toward the discharge groove 20 with the tip 4 as the apex when viewed from the radial direction, and the rake angle on the side of the discharge groove is the torsion angle of the groove. 21 (generally 15 ° to 40 °), the same rake face 22 in the axial direction, and the clearance angle 23 on the end side is 20 ° to 20 ° in the direction perpendicular to the axis.
A 35 ° flank 24 perpendicular to the axis is formed. Further, the width dimension 25 is 0 to 0 in the axial direction from the tip 4 of the projection blade 5.
A chamfer 27 having 0.5 mm and an axial rake angle 26 of 0 ° to 30 ° is provided. 14 is a margin.

The flat blade 8 has a length 31 exceeding 1/2 of the drill diameter 30 and not more than 2/3 along a straight line passing through the outer peripheral end of the drill and the axis in the discharge groove direction corresponding to the other grooves 2. Cutting edge 2
8 are formed. The inclination angle 29 of the flat blade 8 is set to 85 ° to 95 ° with respect to the axis.

[0023]

Next, the results of actually cutting a composite material with a conventional crown-shaped drill and the drilling tool of the present invention will be described. The work piece has a surface layer of about 0.4mm thick paper and a main layer of about 15mm thickness mainly made of gypsum is adhered under it, and a wood of about 30mm thickness is adhered below it. Have been. A counterbore with a hole diameter of 10 mm and a depth of 20 mm was formed in the composite material. In the hole drilling tool of the present invention, the dimension 9 from the tip of the projection blade to the flat blade is 0.5 mm, the dimension 11 between the flat blade and the relief portion is 0.3 mm, and the clearance angle in the direction perpendicular to the radius is 13
Is 12 °, the rake angle 15 in the radial direction is 10 °, the inclination angle 19 of the hypotenuse 18 is 40 °, and the rake angle in the axial direction is the torsion angle 2 of the groove.
30 ° same as 1, 23 ° clearance angle 23 °, chamfer 27
Width dimension 25 is 0.13 mm, axial rake angle 26 is 5
°. The length 31 of the cutting edge 28 of the flat blade 8 is 5.4 m
m and the tilt angle 29 are 92 ° with respect to the axis.

As a result, in the conventional crown type drill, the maximum height of the paper is about 0.5 m in a range of about 1.5 mm around the hole.
m, and fluffing occurred about 0.5-1 mm in length. On the other hand, in the hole drilling tool of the present invention, the surface layer is hardly lifted, and the length of the fluff is about 0,0.
It decreased to 1 to 0.4 mm. The hole drilling tool of the present invention is not a hand-held power machine, but drills a hole in a state in which both the work and the tool are mechanically fixed.

[0025]

According to the present invention, at the tip of a twist drill having at least two grooves, a protruding blade having a vertex at the edge of a hole to be machined, and an outer peripheral end retreated axially from the front end of the protruding blade. Since the flat blade extended in the axial direction from the flat blade and the relief portion provided between the protruding blade and the flat blade retreating from the flat blade are formed, there is no generation of burrs, fluff, etc. Needless to say, the present invention has provided a drilling tool which is free from chipping of the cutting edge and has improved sharpness of the cutting edge for a hole edge. Also,
Protrusion blades and flat blades have reliefs between them, so they can be processed completely independently, and a large processing surface can be secured. Free setting of the cutting edge to enhance cutting edge performance and cutting edge strength It is possible to process easily, and the cost is low.

Further, since the protruding blade has a triangular shape on each surface and can support the strength of the tip blade,
The blade is not easily chipped, the sharpness can be secured for a long time, and the cutting edge can be easily processed. Further, since the flat blade following the protruding blade can form a large cutting width and a flank, it can withstand heavy cutting load, and the hole can be reliably drilled without the load being concentrated on the protruding blade. Furthermore, since the protruding blade is easy to process and can form a chamfer at the tip, a hard building material layer, hard particles,
Processing of a composite material in which fines are mixed has an effect that the sharpness does not decrease.

[Brief description of the drawings]

FIG. 1 is a front view of a tip of a drilling tool according to an embodiment of the present invention as viewed from an axial direction.

FIG. 2 is a partial side view of the tip of the drilling tool according to the embodiment of the present invention, as viewed from an arrow A in FIG.

FIG. 3 is a partial side view of the tip of the hole drilling tool according to the embodiment of the present invention, as viewed from an arrow B in FIGS. 1 and 2;

FIG. 4 is a side view of a conventional crown-shaped drill.

[Explanation of symbols]

 1, 2 groove 3 tip of twist drill 4 tip of protruding blade (apex) 5 protruding blade 6 outer peripheral end 7 axis 8 flat blade 9 dimension from protruding blade tip to flat blade 10 relief section 11 dimension between flat blade and relief section REFERENCE SIGNS LIST 12 cutting edge 13 radial right angle relief angle 14 margin part 15 radial direction rake angle 16 radial direction rake face 17 outer peripheral side 18 oblique side 19 oblique side inclination angle 20 discharge groove side 21 groove torsion angle 22 axial rake face 23 axis perpendicular direction Clearance angle 24 Clearance surface in the direction perpendicular to the axis 25 Chamfer width dimension 26 Axial rake angle 27 Chamfer 28 Flat blade cutting edge 29 Flat blade inclination angle 30 Drill diameter 31 Flat blade radial length

Claims (5)

(57) [Claims] 1. A twist drill having at least two or more grooves, wherein a cutting edge is provided at a tip in a discharge groove direction corresponding to one groove, and the cutting edge is machined at a tip as viewed from a circumferential direction. It is a substantially right-angled triangular shape with the tip of the hole edge to be apexed and the outer peripheral side as a vertical side, and a substantially triangular shape adapted to project toward the discharge groove side with the tip portion as the apex as viewed from the radial direction. An axial rake face on the groove side face and an axial flank face on the end side, and a margin section having a radial right angle flank angle provided along the outer periphery next to the tip section as viewed from the axial direction, and an axial center from the tip section. And a cutting edge formed by extending from the axis along a straight line passing through the outer peripheral end of the drill and the axis in the direction of the discharge groove corresponding to the other groove. , Axially behind the tip of the projection blade Hole machining tool, characterized in that it comprises a flat blade provided with, and a relief portion provided recessed from the flat blade between the flat edge and said projection blade. 2. The projection blade according to claim 1, wherein the oblique side of the substantially right triangle viewed from the circumferential direction has an inclination angle of 20 ° to 50 ° with respect to the axis, and the rake angle of the axial rake face viewed from the radial direction is the groove. The flank angle of the flank in the direction perpendicular to the axis is set to 20 ° to 35 ° in the direction perpendicular to the axis, and the flank angle of the flank in the radial direction of the margin portion viewed from the axial direction is 8 ° in the direction perpendicular to the radius. The drilling tool according to claim 1, wherein the rake angle of the rake face in the radial direction is 5 ° to 20 °. 3. A chamfer having an axial rake angle of 0 ° to 30 ° with a width of 0.5 mm or less in an axial direction from a tip end of the axial rake face as viewed from a radial direction of the projection blade. 3. The drilling tool according to claim 2, wherein: 4. The flat blade according to claim 1, wherein the flat blade is at an angle of 85 ° to the axis.
The flat blade has a tilt angle of ~ 95 °, the radial length of the flat blade is more than 1/2 of the drill diameter and not more than 2/3, and the maximum height of the cutting edge is 0.3 to 1. 4. The drilling tool according to claim 1, wherein the drilling tool is retracted by 0 mm. 5. The drilling tool according to claim 1, wherein the height of the relief portion according to claim 1 is set back by at least 0.3 mm from the minimum height of the flat blade.