JP2005246577A - Deburring drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deburring twist drill even having a simple structure and a small diameter, which continuously carries out drilling and deburring and removes burrs in the withdrawal stroke after drilling. <P>SOLUTION: The twist drill having two chip discharging flutes is configured such that positions of respective cutting edges of the drill in the axial view from the tip end of the drill are unsymmetrical with respect to the drill axis, and an approximately cylindrical portion having the diameter smaller than that of the drill is provided on the intermediate portion of the chip discharging flutes, and deburring cutting edges are provided at least on the tip end side of the drill at the stepped portions of the approximately cylindrical portion. The rotational axis of the drill is made different in drilling and deburring. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, during drilling of metal and non-ferrous metal, after drilling through a drill chisel part composed of an asymmetric tip cutting edge as a cutting center, the cylindrical part is pushed in until it reaches the back side of the penetration part, and then pulled back. The present invention relates to a deburring drill in which burrs attached to a peripheral portion of a through hole are cut by a deburring cutting edge provided at a step portion that rotates around a drill axis when drilling and deburring are performed continuously.

As a method to prevent back burrs during drilling of metal and non-ferrous metals, a burr cutting blade that moves in and out by the elasticity of the spring is provided at the land near the tip of the drill so that burrs are removed when pulling back after drilling. A specially designed drill is used, but the structure is complicated and it is difficult to manufacture with a small diameter drill. There exists patent document 1 as such an example.
Japanese Patent Laid-Open No. 2003-127017

  The present invention relates to deburring, and is a deburring drill that has a simple structure and can continuously perform drilling and deburring even with a small-diameter drill, and by varying the center of rotation of drilling and deburring, Provided is a drill that can remove burrs during pulling after drilling.

The present invention relates to a twist drill having two chip discharge grooves, in which the position of each drill cutting edge in the front end view is asymmetric with respect to the drill axis, and is substantially shorter than the diameter of the drill from the middle of the chip discharge groove. A deburring drill characterized in that a cylindrical portion is provided and a cutting edge for deburring is provided at least on a step portion on the drill tip side of the substantially cylindrical portion. By employing the present invention, drilling is performed. The drill chisel composed of both cutting edges is the cutting center of the drill, and the cutting edge for deburring is centered on the drill axis. Can follow the hole around the back burr and remove it when pulling back.
More specifically, the angle formed by the imaginary line connecting the outer peripheral corner portion of each drill cutting edge and the drill axis in the front end view is 145 ° or more and 175 ° or less, and the diameter of the substantially cylindrical portion is 0 of the drill diameter. .6 to 0.9 times, the cutting edge for deburring is provided at 60 ° or more and 150 ° or less facing the tip side of the drill, and at least a portion of the drill having a cutting edge such as TiN, TiCN, TiAlN, etc. It is a deburring drill characterized by forming a single layer or multiple layers of hard material.

  By this invention, the burr | flash which generate | occur | produces when processing a through-hole can be continuously removed in the case of pulling back at the time of drilling.

In the drill of the present invention, even after the tip cutting edge penetrates, until the deburring cutting edge provided on the cutting edge side of the substantially cylindrical portion which is thinner than the diameter of the tip drill in the middle of the groove reaches the back surface of the hole where the back burr is open After the push-in, the back burr is removed by following the hole around the back burr with a cutting blade for deburring when it is pulled back. In this case, in order to perform cutting while following the hole peripheral part of the back burr with the cutting edge for deburring, it is necessary to make the rotation center of the drill tip cutting edge and the deburring cutting edge different from each other. Does not imitate the hole periphery around the back burr. In order to make the rotation center different, the drill tip edge is made asymmetric with respect to the drill axis, and the angle formed by the imaginary line connecting the outer peripheral corner of each drill edge and the drill axis in the drill tip view is less than 145 ° The displacement of the center with respect to the center of rotation of the cutting edge of the tip becomes large, and the work becomes unstable with vibration during drilling. At 175 ° or more, the displacement of the center with respect to the center of rotation of the cutting edge of the tip is small. The peripheral part of the burr hole cannot be sufficiently copied with the cutting edge for deburring, and the back burr cannot be completely removed. Therefore, the angle formed by the imaginary line connecting the outer peripheral corner portion of each drill cutting edge and the drill axis is set to 145 ° or more and 175 ° or less.
Since this drill has a cutting edge for deburring, it has a substantially cylindrical part that is thinner than the diameter of the tip drill in the middle of the groove, and the drill strength decreases if the diameter of the substantially cylindrical part is 0.6 times the drill diameter or less. However, the stability at the time of drilling is impaired, and the deburring blade needs to have a cutting edge length that is greater than the raised width around the back burr hole. Since the width is 0.03 to 0.05 times the drill diameter, the diameter of the substantially cylindrical portion where the deburring blade is provided is 0.9 times or less the drill diameter.

  The deburring blade follows the hole around the back burr and removes the burr when pulling back, but the deburring blade provided on the cylindrical part in the middle of the drill groove and the step on the tip side of the drill When the taper angle is 60 ° or less, the deburring blade slides into the hole and does not sufficiently follow the periphery of the processed hole, so that the burr is not completely removed. When the angle is 150 ° or more, the deburring blade is caught in the hole during pulling and damages the deburring surface. Therefore, the taper angle of the deburring blade is 60 ° or more and 150 ° or less. Further, the hole entrance portion can be chamfered by providing a tapered cutting edge from the substantially cylindrical portion toward the drill proximal end side at the step portion on the drill proximal end side of the substantially cylindrical portion.

(Example 1)
As Example 1 of the present invention, manufactured by SKH51, TiAlN coating, drill diameter = 8.0 mm, tip angle = 118 °, drill groove length = 95 mm, drill overall length = 150 mm, core thickness = 1.4 mm, screw angle = 30 °, approximately The diameter of the cylindrical portion = 6.4 mm, the taper angle (α) for deburring = 120 °, the position of the substantially cylindrical portion = 20 mm from the tip of the drill, and the length of the substantially cylindrical portion = 10 mm. Using the angle (β) formed by the imaginary line connecting the outer peripheral corner portion and the drill axis as shown in Table 1, using one tool in each shape, using a drilling machine, the number of revolutions = 820 min ⁻¹ , 5 plates of SS400 with a thickness of 4.5mm are processed by hand feed, and the stability of cutting and the removal state of back burrs are investigated, and the state is also shown in Table 1.

  As shown in Table 1, the shape within the specification range of the present invention was able to completely remove the back burr and stable drilling was performed, but the shape outside the specification range was not able to completely remove the back burr. The stability of was unstable.

(Example 2)
As Example 2 of the present invention, in the drill of Example 1 described above, the angle (β) formed by the imaginary line connecting the outer peripheral corner portion of each drill cutting edge and the drill axis in the front end view is 160 °, and the diameter of the substantially cylindrical portion Table 2 is used, one tool is used for each shape, drilling is performed in the same manner as in Example 1, the stability of cutting and the removal state of back burrs are investigated, and the state is also shown in Table 2. .

  As shown in Table 2, the shape within the specification range of the present invention was able to completely remove the back burr and stable drilling was performed, but the shape outside the specification range could not be removed completely, The stability of was unstable.

(Example 3)
As Example 3 of the present invention, in the drills of Examples 1 and 2 described above, the angle (β) formed by the imaginary line connecting the outer peripheral corner portion of each drill cutting edge and the drill axis in the front end view is 160 ° and substantially cylindrical. Use a taper angle (α) of the cutting edge for deburring provided in the step part on the drill tip side of the substantially cylindrical part with a part diameter (D) of 6.0 mm, one for each shape. Are drilled in the same manner as in Examples 1 and 2, and the removal state of the back burr is investigated, and the state is also shown in Table 3.

  As shown in Table 3, the shape within the specification range of the present invention was able to completely remove the back burr and stable drilling was performed, but the shape outside the specification range could not be completely removed from the back burr. A cutting flaw occurred.

FIG. 1 shows a front view of the present invention. FIG. 2 shows a shaft end view of the present invention.

Explanation of symbols

1: Cutting edge for deburring 2: substantially cylindrical portion 3: substantially cylindrical diameter (D)
4: Taper angle (α) of deburring blade
5: Peripheral corner portion of the drill cutting edge 6: Angle formed by an imaginary line connecting the outer peripheral corner portion of the drill cutting edge and the drill axis (β)
7: Chisel portion 8: Chisel portion center 9: Drill rotation center

Claims (5)

In a twist drill having two chip discharge grooves, the position of each drill cutting edge in the front end view is asymmetric with respect to the drill axis, and a substantially cylindrical part thinner than the drill diameter is provided in the middle of the chip discharge groove part. A deburring drill characterized in that a cutting edge for deburring is provided at least on a step portion on the drill tip side of the substantially cylindrical portion. 2. The deburring drill according to claim 1, wherein an angle formed by an imaginary line connecting the outer peripheral corner portion of each drill cutting edge and the drill axis in a front end view is 145 ° or more and 175 ° or less. drill. The deburring drill according to claim 1 or 2, wherein the diameter of the substantially cylindrical portion is not less than 0.6 times and not more than 0.9 times the drill diameter. The deburring drill according to any one of claims 1 to 3, wherein the deburring cutting edge is provided at 60 ° or more and 150 ° or less toward the tip of the drill. The drill according to any one of claims 1 to 4, wherein a hard substance such as TiN, TiCN, TiAlN or the like is formed in one or more layers on at least a portion of the drill having a cutting edge.

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