JP3230148B2 - Drilling tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drilling tool such as a miniature drill mainly used for forming a small-diameter hole in a printed circuit board.

[0002]

2. Description of the Related Art Generally, a miniature drill has a hole to be drilled having a very small diameter. Is provided with a relatively large-diameter shank portion for gripping the rotary shaft of the machine tool. Usually, a hard cemented carbide is used as the material of the drill portion. Therefore, when manufacturing miniature drills, the solid type with the drill part and shank part integrated,
For example, a cylindrical material of cemented carbide is cut out and the drill part and shank part are integrally formed, and the cost of the cemented carbide material and the amount of processing for forming the drill part are large, resulting in high cost. There is a disadvantage. Therefore, as shown in FIG. 3 , the small-diameter drill portion 1 is made of a substantially cylindrical cemented carbide material, and the large-diameter shank portion 2 is used as an inexpensive material such as steel. A composite type miniature drill 3 has been proposed in which a rear portion 1a of a drill portion 1 is fitted to 2a by a method such as shrink fitting, and thereafter, the drill portion 1 is cut.

[0003]

By the way, in such a composite type miniature drill, the rear part 1a of the drill part 1 is, for example, a cylindrical round bar, and the hole 2a of the shank part 2 is a cylindrical round hole. In the case of, since a load is applied to the drill portion 1 at the time of manufacturing or cutting the drill, a slip phenomenon occurs at the fitting portion, and the drill portion 1 slides in the circumferential direction or the longitudinal direction with respect to the shank portion 2. There is a problem of causing a gap. In view of such circumstances, an object of the present invention is to provide a drilling tool that suppresses a slip phenomenon that occurs in a fitting portion between a blade portion and a shank portion during manufacturing or cutting.

[0004]

According to the present invention, there is provided a drilling tool in which a blade portion is fitted into a hole formed in a shank portion and tightly closed.
In the fixed drilling tool, a concave portion is formed in a portion located in the hole of the blade portion, and the concave portion has an upright surface that rises at right angles to an inner wall of the hole of the shank portion on the rear side. It is characterized by having. With the blade part fitted in the hole of the shank part, when cutting to form a tip cutting edge or a chip discharge groove in the blade part, or when drilling a work material with the blade part, Even if force is applied to the inner wall of the hole of the shank part by vibration or impact due to the load on the part, the blade may be caught by the concave part and the inner wall of the hole due to the action of the blade part sliding. The part does not move and slippage can be prevented. Further, the drilling tool according to the present invention is characterized in that the entire concave portion or the upright surface is formed obliquely with respect to the rotation axis of the blade portion.

[0005]

FIG. 1 is a block diagram showing an embodiment of the present invention.
And FIG. FIG. 1 is a sectional view of a fitting state of a drill portion and a shank portion in a process of manufacturing a miniature drill according to an embodiment, and FIG. 2 is a plan view of the drill portion. Miniature drill 1 as drilling tool shown in Fig. 1
0 is a small-diameter substantially cylindrical drill portion 11 as a blade portion on the tip side.
, And a relatively large-diameter substantially cylindrical shank portion 12 is located on the rear end side. Drill part 11 is rear part 1
The outer peripheral surface of 1a is partially cut away, and a groove 13 having, for example, a substantially wedge-like shape in a longitudinal section is formed as a concave portion (see FIGS. 1 and 2). The wall of the groove 13 is, for example, a drill 1
1 upright surface 13a which is substantially perpendicular to the outer peripheral surface
And an inclined surface 13 b that is gently inclined with respect to the outer peripheral surface of the drill portion 11.

The shank portion 12 has a tapered surface 12a at the tip, and a substantially cylindrical round hole 14 is formed in the tip surface 12b of the tapered surface 12a coaxially with the outer peripheral surface. The inner diameter of the round hole 14 is substantially the same as the outer diameter of the drill portion 11, and the rear portion 11a of the drill portion 11 is fitted into the round hole 14 by shrink fitting or the like and tightly fixed. Moreover, in the fitted state, the groove 13 of the drill 11 is located in the round hole 14 of the shank 12. afterwards,
A tip cutting edge, a chip discharge groove and the like are formed in the drill portion 11 by shaving or the like.

[0007] The miniature drill 10 according to the present embodiment.
Is provided with the above-described configuration, for example, when forming a cutting edge or a chip discharge groove in the drill portion 11 by cutting, or when drilling a printed circuit board with the manufactured miniature drill 10, Stress acts in the direction (longitudinal direction) or circumferential direction in which 11 is pulled out from shank portion 12. Then, the sliding force acts on the outer peripheral surface of the rear portion 11a of the drill portion 11 relatively to the inner wall 14a of the round hole 14 in the round hole 14, and at this time, the groove 13 of the drill portion 11 stands upright. Since the outer edge 13c of the surface 13a is caught by the inner wall 14a of the round hole 14, the slip of the drill portion 11 in the longitudinal direction is suppressed, and the ridge line portion 1 between the inclined surface 13b and the outer peripheral surface of the drill portion is formed.
In 3d, slip in the circumferential direction is suppressed, and relative displacement of the drill portion 11 does not occur. According to the miniature drill 10 of the present embodiment, compared to a miniature drill having the same shape of the conventional structure in which the drill portion 11 is not provided with a groove, the miniature drill 10 has
A slip prevention effect of 2 to 2.0 times was obtained. FIG.
As shown by the dashed line, the entire groove 13 or the groove 13
Is formed obliquely with respect to the rotation axis of the drill portion 11, the effect of preventing circumferential slippage is improved.

As described above, according to the present embodiment, the drill portion 11 slides in the longitudinal direction and the circumferential direction in the round hole 14 of the shank portion 12 at the time of manufacturing the miniature drill 10 or at the time of cutting and drilling. This can suppress the occurrence of positional deviation, and exhibit a slip prevention effect.

Although only one groove 13 is provided on the outer peripheral surface of the drill 11 in the above-described embodiment, a plurality of grooves 13 may be provided. At this time, the grooves 13 may be formed so as to be shifted in the circumferential direction of the outer peripheral surface of the drill portion 11 or may be arranged in the longitudinal direction. The concave portion of the drill portion 11 can be formed in various shapes without being limited to the groove portion 13 having a wedge-shaped cross section, but at least one surface stands at a right angle to the inner wall of the round hole 14 or at a large angle before and after the inner wall. It is preferable to provide the upright surface 13a as described above. Further, the hole of the shank portion 12 is not limited to the round hole 14 and may be a prism or the like. In this case, the rear portion 11a of the drill portion 11 may be similarly formed in a prismatic shape. Further, the present invention is not limited to a miniature drill, and can be applied to various drilling tools such as a large diameter drill and an end mill.

[0010]

According to the present invention as described above, drilling tool according to the present invention, the recess is formed in the portion located in the hole of the blade portion, said
The recess stands upright at right angles to the inner wall of the shank hole.
Since the upright surface is provided on the rear side, even if a force acts in the direction in which the blade portion slides relatively in the hole of the shank portion when manufacturing or drilling a drilling tool, the end of the wall surface of the groove portion The edge is caught on the inner wall of the hole to prevent displacement, and has a slip prevention effect.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view in a manufacturing process of a miniature drill according to an embodiment of the present invention.

FIG. 2 is a plan view of a drill unit.

FIG. 3 is a partially cutaway view showing a cross section of a part of a general miniature drill.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Miniature drill 11 Drill part 12 Shank part 13 Groove part 14 Round hole

Claims (2)

(57) [Claims] 1. A drilling tool in which a blade portion is fitted into a hole formed in a shank portion and tightly fixed , wherein a concave portion is formed in a portion of the blade portion located in the hole, and the concave portion is formed. A drilling tool, characterized in that an upright surface that rises at right angles to the inner wall of the hole of the shank portion is provided on the rear side. 2. The blade according to claim 1, wherein the entire concave portion or the upright surface is provided with the blade.
It is characterized by being formed obliquely to the rotation axis of the part
The drilling tool according to claim 1, wherein