JP5800477B2 - drill - Google Patents

Description

The present invention relates to a drill suitable for high-speed machining of holes.

2. Description of the Related Art Conventionally, in order to drill holes in a metal material or the like, a twist drill having a cutting edge formed at the tip and a chip discharge groove formed in a spiral shape on the outer periphery has been widely used. According to such a drill, the drill is rotated, a work material such as a metal material is cut by the cutting blade, and the chips cut by the cutting blade are discharged to the outside of the hole through the chip discharge groove. Can be drilled.
In recent years, there has been an increasing need for drilling at high speeds. However, increasing the feed rate of a drill places a large load on the cutting edge, especially the outer peripheral edge of the cutting edge, and the drill tends to break. It was. Therefore, for example, Patent Document 1 discloses a twist drill in which the corner cutting edge is formed on the outer periphery of the cutting edge and the strength of the outer peripheral end portion is improved to improve the strength of the cutting edge.

JP 2000-198011 A

However, if the corner cutting edge is made large in order to improve the strength of the cutting edge, the chips are discharged toward the outer circumference, so that the chips hit the wall surface of the hole and generate heat or are not easily discharged to the outside. As a result, a large resistance is applied to the drill, cutting performance is degraded, the drill is broken, and the life of the drill is shortened. For this reason, there is a problem that the feed amount of the drill cannot be increased and the sufficiently high-speed drilling cannot be performed.

Therefore, the present invention realizes a long-life drill capable of high-speed machining by improving the cutting edge strength and controlling the chip discharge direction to the upward direction of the hole so that it is efficiently discharged. Objective.

In order to achieve the above object, according to the first aspect of the present invention, in the invention described in claim 1, a chip discharge groove is formed in the outer peripheral portion of the drill, and the relief formed in the rake face of the inner peripheral surface of the chip discharge groove and the drill tip. In a drill in which a cutting edge is formed in the ridge line portion by the surface, the cutting edge is formed to recede toward the rear in the rotation direction of the drill toward the outer circumferential direction, and the cutting when the drill tip is viewed from the front. The rake angle α in the radial direction at the outer peripheral edge of the blade is −50 ° ≦ α ≦ −15 °, the tip angle of the cutting blade is the largest at the center, and the width W from the outer peripheral edge of the cutting blade is The technical means that the tip angle β is formed to satisfy 50 ° ≦ β ≦ 110 ° in a region satisfying 0.2D ≦ W ≦ 0.4D (D: diameter of the drill) is used.

According to the first aspect of the present invention, the cutting edge is formed by retreating toward the rear in the rotation direction of the drill toward the outer circumferential direction, and at the outer peripheral end of the cutting edge when the front end of the drill is viewed from the front. By configuring the rake angle α in the radial direction to be −50 ° ≦ α ≦ −15 °, the contact length between the work material and the cutting blade is increased, and the load per unit length of the cutting blade is reduced. While reducing, the intensity | strength of the outer peripheral edge part of a cutting blade can be improved.
Further, the tip angle of the cutting edge is maximum at the center, and the tip angle β is in a region where the width W from the outer peripheral end of the cutting edge satisfies 0.2D ≦ W ≦ 0.4D (D: diameter of the drill). Is configured to satisfy 50 ° ≦ β ≦ 110 °, the chip can be discharged efficiently by controlling the chip discharging direction to the upward direction of the hole.
As a result, the strength of the cutting edge can be improved and the chips can be efficiently discharged, so that the feed amount of the drill can be increased, and a high-speed machining and long-life drill can be achieved.

According to a second aspect of the present invention, in the drill according to the first aspect, the chamfer portion is chamfered at the outer peripheral end portion of the cutting blade, and the width L of the chamfer portion is 0.05D ≦ L ≦ 0. Use technical means of 3D.

In the drill of the present invention, the chip discharge direction can be controlled in the hole upward direction so as to be efficiently discharged, so that the width is wider than the conventional drill as in the invention of claim 2. A chamfer part can be provided. Thereby, since the intensity | strength of the outer peripheral edge part of a cutting blade can be improved further, it can be set as a long-life drill which can be processed at high speed.

According to a third aspect of the present invention, in the drill according to the first or second aspect, the cutting blade has a plurality of linear shapes in which the tip angle and the rake angle in the radial direction become smaller toward the outer peripheral direction of the drill. The technical means of being constituted by a cutting blade is used.

According to the third aspect of the present invention, when the cutting blade is constituted by a plurality of linear cutting blades, it is possible to facilitate re-polishing of the cutting blade after manufacturing and use of the drill.

It is the front view (A) and side view (B) of the front-end | tip part of the drill which concern on one Embodiment of this invention.

The drill of this invention is demonstrated with reference to figures. In addition, this invention is not limited to the following embodiment.

As shown in FIG. 1, a drill 1 that rotates around an axis and drills a hole includes a pair of chip discharge grooves 11 formed in a spiral shape in the axial direction of the outer peripheral portion, a rake face 11 a of the chip discharge groove 11, and a drill A cutting edge 14 having a predetermined tip angle is formed at the ridge line portion by the flank formed in the tip (in this embodiment, the first flank 12 and the second flank 13).

A chisel edge 15 is formed at the center of the tip of the drill 1 by intersecting the first flank 12. Further, a thinning portion 16 is formed on the inner peripheral side of the tip portion of the cutting blade 14 by cutting out the inner wall surface of the rake face 11a.

On the outer peripheral surface of the cutting edge 14, a margin portion 17 and a second picking surface 18 having an outer diameter smaller than that of the margin portion 17 are formed.

The cutting edge 14 is formed to recede toward the rear in the rotation direction of the drill so that the rake angle in the radial direction becomes smaller toward the outer periphery of the drill. In the present embodiment, the cutting blade 14 is formed by connecting a plurality of cutting blades formed in a straight line, and the first cutting blade formed by the first flank 12 and the rake face 11a from the center side. 14a, a second cutting edge 14b formed by the second flank 13 and the rake face 11a is provided.
Here, by constituting the cutting blade 14 with a plurality of linear cutting blades, re-polishing of the cutting blade after the manufacture and use of the drill can be facilitated.

A chamfer portion 19 chamfered toward the rear in the rotation direction of the drill is formed at the outer peripheral end portion of the cutting blade 14. The chamfer portion 19 is formed so that the rake angle α in the radial direction satisfies −50 ° ≦ α ≦ −15 °. Further, the width L of the chamfer portion is formed such that 0.05D ≦ L ≦ 0.3D with respect to the diameter D of the drill.
Here, when the chamfer portion 19 is not formed, the cutting edge 14 is formed such that the rake angle α in the radial direction at the outer peripheral end portion satisfies the above condition.

The cutting edge 14 is formed so that the tip angle becomes smaller toward the outer peripheral direction of the drill. In the present embodiment, the tip angle θ of the first cutting edge 14a is formed to be 118 ° to 150 °.
Further, the cutting edge 14 has a tip angle β of 50 ° ≦ β ≦ 110 ° in a region where the width W from the outer peripheral edge of the cutting blade satisfies 0.2D ≦ W ≦ 0.4D (D: diameter of the drill). It is comprised so that.
In this embodiment, the 2nd cutting blade 14b and the chamfer part 19 (area | region of the width W from the outer peripheral edge part of the cutting edge 14) correspond to the said area | region.

The cutting edge 14 is formed so as to recede toward the rear in the rotation direction of the drill toward the outer peripheral direction, thereby increasing the contact length between the work material and the cutting edge 14 and per unit length of the cutting edge. The load can be reduced.
If the rake angle α is too large, the effect of preventing the outer peripheral edge from being lost is reduced, and if the rake angle α is too small, the cutting resistance increases, so −50 ° ≦ α ≦ −15 °, preferably −40 °. It is preferable to configure so that ≦ α ≦ −20 °.

In the drill 1 of the present invention, the chamfer portion 19 having a width L wider than that of the conventional drill can be obtained because the chip can be discharged efficiently by controlling the chip discharge direction to the upward direction of the hole as described later. Can be provided. Thereby, the intensity | strength of the outer peripheral edge part of the cutting blade 14 can further be improved.
If the width L of the chamfer portion 19 is too small, the effect of preventing the outer peripheral end portion from being lost is reduced. If the width L is too large, the cutting resistance increases, so the width L is 0 with respect to the diameter D of the drill 1. .05D ≦ L ≦ 0.3D is preferably formed.

In the present embodiment, the region where the rake angle in the radial direction has a negative value corresponds to the first cutting edge 14a, the second cutting edge 14b, and the chamfer portion 19. In a region where the rake angle in the radial direction is a negative value, chips are discharged toward the outer peripheral direction, but the width W from the outer peripheral end of the cutting blade is 0.2D ≦ W ≦ 0.4D (D: drill The tip angle β is 50 ° ≦ β ≦ 110 °, preferably 60 ° ≦ β ≦ 100 ° in a region satisfying It can be efficiently discharged.
Here, if the tip angle β is less than 50 °, the chips are easily discharged in the central direction, and the cutting edge becomes longer, so that the cutting resistance increases.
Moreover, even if the tip angle β exceeds 100 °, the action of discharging chips to the upper surface of the hole surface becomes small.

Thereby, while improving the intensity | strength of the cutting blade 14, a chip | tip can be discharged | emitted efficiently and the feed amount of a drill can be increased, Therefore A high-speed machining is possible and it can be set as a long-life drill. . In addition, since the chips are efficiently discharged through the chip discharge groove 11, the chip discharge groove 11 does not have to be enlarged, so that the core thickness can be increased and the rigidity of the drill 1 can be increased. Thereby, the lifetime of the drill 1 can be lengthened.

(Example of change)
In the above-described embodiment, the configuration in which the cutting blade 14 includes the first cutting blade 14a and the second cutting blade 14b and the chamfer portion 19 is illustrated is exemplified, but the configuration is not limited thereto.
For example, the cutting edge 14 may be constituted by three or more linear cutting edges such that the tip angle β and the rake angle α in the radial direction become smaller toward the outer peripheral direction of the drill 1.
Further, the cutting edge 14 can be formed by a circular arc or a smooth curve convex in the rotation direction. According to this, since the cutting edge 14 has no corners, the stress concentration is small and the length of the cutting edge 14 is increased, so that the strength of the cutting edge 14 can be improved. In this case, the chamfer part 19 may not be formed.
It can also be formed in a curved shape in which the tip angle β continuously decreases. In this case, the outer side corresponds to the region having the width W from the point where the tip angle β is 110 ° or less.

(Example 1)
Hole drilling was performed using a drill according to an example of the present invention and a conventional drill, and the life of each drill was evaluated.

The drill of the example is the same as the drill 1 in the above embodiment, the diameter D is 1 mm, the rake angle α is −38 °, the tip angle θ of the first cutting edge 14a is 140 °, and the tip angle β of the second cutting edge 14b. Was 90 °, and the chamfer portion 19 had a width L of 0.13 mm (0.13D). Moreover, as a drill of the comparative example, a twist drill having a straight edge with no chamfer portion formed and having a tip angle of 120 ° was used.

S50C was used as a work material, a hole having a diameter of 1 mm and a depth of 4 mm was performed, and the life was evaluated based on the number of holes that could be processed. Table 1 shows the processing conditions and life.
As high-speed machining conditions, the feed amount was set to 0.1 mm / rev, which is twice the 0.05 mm / rev adopted as general machining conditions.
Example 1 and Comparative Example 1 are the same processing conditions, and Example 2 is a condition in which the number of rotations is increased.

According to the conventional drill, as shown in Comparative Example 1, the cutting edge was lost due to the processing of 3000 holes, and it was impossible to process. On the other hand, according to the drill of the present invention, as shown in Examples 1 and 2, processing of 17,000 holes or more was possible, and the life was significantly prolonged.
Further, the machining time per hole required about 2 seconds under the conventional machining conditions, but it was able to be significantly reduced to within 0.4 seconds.

From the above, it was confirmed that the drill of the present invention has a longer life than conventional drills under high-speed machining conditions.

[Effect of the embodiment]
According to the drill of the present invention, the cutting edge 14 is formed to recede toward the rear in the rotation direction of the drill 1 in the outer circumferential direction, and the rake angle α in the radial direction at the outer circumferential end of the cutting edge 14 is −. By configuring so that 50 ° ≦ α ≦ −15 °, the contact length between the work material and the cutting blade 14 is lengthened to reduce the load per unit length of the cutting blade 14, and the cutting blade The strength of the outer peripheral end portion of 14 can be improved.
The tip angle β is 50 ° ≦ β ≦ 110 ° in a region where the width W from the outer peripheral end portion of the cutting edge satisfies 0.2D ≦ W ≦ 0.4D (D: diameter of the drill). By doing so, it is possible to control the chip discharge direction in the upward direction of the hole so as to be discharged efficiently.
As a result, the strength of the cutting edge can be improved and the chips can be efficiently discharged, so that the feed amount of the drill can be increased, and a high-speed machining and long-life drill can be achieved.

DESCRIPTION OF SYMBOLS 1 ... Drill 11 ... Chip discharge groove 11a ... Rake face 12 ... 1st flank 13 ... 2nd flank 14 ... Cutting blade,
14a ... 1st cutting edge 14b ... 2nd cutting edge 15 ... Chisel edge 16 ... Thinning part 17 ... Margin part 18 ... Second picking surface 19 ... Chamfer part

Claims (3)

In a drill in which a chip discharge groove is formed in the outer peripheral portion of the drill, and a cutting edge is formed in the ridge line portion by a scoop surface of the inner peripheral surface of the chip discharge groove and a flank surface formed at the tip of the drill,
The cutting edge is formed to recede toward the rear in the rotation direction of the drill toward the outer circumferential direction,
The rake angle α in the radial direction at the outer peripheral end of the cutting edge when the drill tip is viewed from the front is −50 ° ≦ α ≦ −15 °,
The tip angle of the cutting edge is maximum at the center, and the tip angle β is 50 in a region where the width W from the outer peripheral end of the cutting edge satisfies 0.2D ≦ W ≦ 0.4D (D: diameter of the drill). A drill characterized in that it is formed such that ° ≦ β ≦ 110 °. The drill according to claim 1, further comprising a chamfered portion chamfered at an outer peripheral end portion of the cutting blade, wherein a width L of the chamfered portion is 0.05D ≦ L ≦ 0.3D. The said cutting blade is comprised by the some linear cutting blade with which a tip angle and radial rake angle become small as it goes to the outer peripheral direction of a drill, The claim 1 or Claim 2 characterized by the above-mentioned. drill.

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