JPH05200730A - Drill for processing hard and brittle materials - Google Patents

Abstract

(57) [Summary] [Purpose] A pyramid is formed at each end of the main body formed in a prismatic shape so that each ridge corresponds to each ridge of the main body, and the top of the pyramid is predetermined with respect to the orthogonal line of the main body. By cutting at an angle of, the hard and brittle material can be smoothly processed, and the rigidity of the blade portion is increased. [Structure] A blade is formed at the end of a prismatic main body, and the blade has a pyramid whose ridges correspond to the ridges of the main body and the top of the pyramid with respect to an orthogonal line of the main body. A hard and brittle material processing drill consisting of a cut surface cut at a predetermined angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill for processing hard and brittle materials such as crushing taps broken in screw holes and drilling of concrete.

[0002]

2. Description of the Related Art As a conventional technique, there is one shown in FIGS. In FIG. 5, reference numeral 1 is a drill formed of a powdered high-speed sintered material. In the drill 1, a main body 2 is formed in a quadrangular prism shape, and a quadrangular pyramidal blade portion 3 is integrally formed at a lower end portion of the main body 2. As shown in FIG. 5 and FIG. 6, the blade portion 3 is formed by removing from each edge 2a of the main body 2 in a plane shape toward the axis L of the main body 2.

[0003]

In the above-mentioned prior art, since the apex 3a of the blade portion 3 is located on the axis L (rotational axis) of the main body 2, the apex 3a has a cutting function. Will not do. Therefore, as shown in FIG. 5, even if the tap 1 is broken by the drill 1 while the screw hole 4 is being formed and the tap 5 is broken, the apex 3a of the blade portion 3 collides with the upper surface of the tap 5. However, the ability to cut the tap 5 is significantly reduced. Further, when the pressure of the drill 1 is increased in order to improve the cutting ability, the apex 3a slides laterally on the upper surface of the tap 5, and the drill 1 bends and breaks, or the screw portion of the screw hole 4 is damaged. was there. It is an object of the present invention to obtain a new drill for processing hard and brittle materials that solves the above drawbacks.

[0004]

In order to achieve the above-mentioned object, the present invention forms a blade portion whose cross-section is gradually reduced toward the tip at the end portion of a main body formed into a prismatic shape, and the blade portion is Each of the ridges is composed of a pyramid part corresponding to each ridge of the main body and a cut surface obtained by cutting the top part of the pyramid part at a predetermined angle with respect to the orthogonal line of the main body.

[0005]

Since the present invention is configured as described above, the apex of the blade portion, each ridge of the pyramid portion, and the ridge of the connecting portion between the pyramid portion and the cutting surface are deviated from the main axis of rotation. For this reason,
When the main body is rotated, the apex of the blade and the respective ridges come into sliding contact with the object to be cut.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. In the drawings, FIG. 1 is a side view of an essential part showing a first embodiment of the present invention, and FIG. 2 is a bottom view thereof. In FIG. 1, 1
Reference numeral 0 denotes a drill formed of a sintered material of powdered high-speed steel, and integrally has a blade portion 14 whose cross section is gradually reduced to the left at the tip portion, that is, the left end portion of the hexagonal columnar main body 11.
The blade portion 14 has a top portion of a hexagonal pyramid 15 as a main body.
Is cut at a predetermined angle with respect to the orthogonal line.

The pyramidal portion 15 has its surface portion 16 and the ridge 17 correspond to the surface portion 12 and the ridge 13 of the main body 11, and the square surface portion 16 has each surface portion 16 with a half of the diameter of the main body 11 as a radius. The ridges 17 are formed in a circular arc surface, and each ridge 17 is formed to have a predetermined curvature. The cutting surface 18 has an inclination angle α1 of the surface 18a on the outer peripheral side of about 45 degrees and an inclination angle α2 of the surface 18b on the axial center side of about 15 degrees with respect to the orthogonal line of the main body 11,
The apex 14a is deviated from the axis line (rotational axis) L of the main body 11. In addition, in FIG. 1, 10a is a cylindrical holding portion integrally formed on the right side of the main body 11.

3 and 4 show a second embodiment of the present invention. In FIG. 1, reference numeral 11 is a main body formed in a hexagonal columnar shape as in the first embodiment, and a blade portion 20 whose cross section is gradually reduced to the left is integrally formed at a tip portion, that is, a left end portion of the main body 11. The blade portion 20 is formed by cutting the top of a pyramidal portion 21 having a hexagonal pyramid shape at a predetermined angle with respect to the orthogonal line of the main body 11.

The pyramid portion 21 has its surface portions 22 and ridges 23 corresponding to the surface portions 12 and ridges 13 of the main body 11, and the inclination angle β of each surface portion 22 with respect to the orthogonal line of the main body 11 is formed to be about 35 degrees. Each ridge 23 is inclined with a straight line with respect to the orthogonal line of the main body 11. Further, the cutting surface 24 is inclined at about 15 degrees with respect to the orthogonal line of the main body 11, and the apex 20
The a is biased with respect to the axis L of the main body 11.

According to the above embodiment, the vertices 14a (20a) of the blade portion 14 (20) and the respective ridges 17 of the pyramid portion 15 (21).
(23) The ridge 19 (25) of the connecting portion between the pyramidal portion 15 (21) and the cut surface 18 (24) should be laterally offset with respect to the axis L of the main body 11, that is, the rotation axis. become. Therefore, when the drill 10, that is, the main body 11 is rotated, the apex 14a (20a) of the blade portion 14 (20) and the ridges 17 are formed.
(23) and 19 (25) revolve around the axis L, and these come into sliding contact with the object to be cut. Further, the apex 14a (20a) and the respective ridges 17 (23), 19
In (25), a cutting edge having a negative rake angle is formed, and the rigidity is increased to withstand a large load. In addition, the pyramid part 15
The corner (a) of the base of (21) is composed of the ridge 13 of the main body 11, the ridge 17 (23) of the pyramid 15 (21), and the ridge 26 of the connecting portion between the main body 11 and the pyramid 15 (21). Since it is formed by the intersection of the two persons, the cutting performance of the corner portion (a) is improved, and the main body 11 is smoothly fitted into the object to be cut.

[0011]

As is apparent from the above description, according to the present invention, the pyramidal portion is formed at the end portion of the main body formed into a prismatic shape, each ridge corresponding to each ridge of the main body, and the top portion of the pyramid portion is formed. Since the blade is cut at a predetermined angle with respect to the orthogonal line of the main body, the apex and each ridge of the blade part are laterally offset with respect to the main axis of rotation of the main body, and these slidably contact the workpiece. Thus, it is possible to smoothly perform processing of hard and brittle materials such as crushing broken taps remaining in the screw holes or drilling of concrete, and increase rigidity of the blade portion.

[Brief description of drawings]

FIG. 1 is a side view of essential parts showing a first embodiment of the present invention.

FIG. 2 is a bottom view of FIG.

FIG. 3 is a side view of an essential part showing a second embodiment of the present invention.

FIG. 4 is a bottom view of FIG.

FIG. 5 is a side view of a main part in a cutting state showing a conventional example.

FIG. 6 is a bottom view of a conventional drill.

[Explanation of symbols]

 10 Drill 10a Holding part 11 Main body 12 Face part 13 Ridge 14 Blade part 14a Apex 15 Pyramidal part 16 Face part 17 Ridge 18 Cutting section 19 Ridge 26 Ridge (a) Corner

Claims (1)

[Claims] 1. A pyramid-shaped main body formed into a prismatic shape, and a blade portion whose cross-section is gradually reduced toward a tip is formed at an end portion of the main body. A hard and brittle material processing drill, characterized in that it comprises a cutting section obtained by cutting the top of the section at a predetermined angle with respect to the orthogonal line of the main body.