JP2003191114A - Throwaway type drill bit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent welding of chips of a work even to a bit body tip. <P>SOLUTION: A whole surface of the bit body tip, namely, all of a tip surface 12A and an outer circumferential surface 12B of a drill part 12, wall surfaces 18A, 18B, 18C, 19A, 19B and 19C of a chip discharging groove 13, and an outer circumferential surface 13A of a flange part 13 is coated by DLC coating 30. A thickness of the DLC coating 30 is set in the range of 1-15 μm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type drill or the like in which a throw-away tip (hereinafter referred to as a tip) having a cutting edge is attached to the tip of a chip discharge groove formed on the outer periphery of a tool body. The present invention relates to a throw-away type drilling tool.

[0002]

2. Description of the Related Art In a drilling tool of this type, a pair of chip discharge grooves are formed in a drill portion forming the tip of the tool body so as to sandwich the rotation axis of the tool body, and these chip discharge grooves are formed. There is known a so-called two-blade throw-away drill in which a tip is detachably attached to each tip and a cutting edge is formed on the tip.

[0003]

By the way, in the case of drilling a work made of a non-ferrous metal such as aluminum or copper which is easily welded by using such a throw-away type drill, The resulting cutting chips may adhere to the outer peripheral surface of the drill part made of steel or the like, or to the wall surface of the chip discharge groove, which may cause roughening of the inner wall surface of the machined hole or chip. It had spoiled the dischargeability. Further, conventionally, the surface of the drill portion made of steel or the like may be subjected to a treatment such as blackening or plating, but these are intended to prevent the surface of the drill portion from rusting. However, the effect of preventing the above-described welding cannot be sufficiently obtained.

The present invention has been made in view of the above problems, and provides a throw-away type drilling tool capable of preventing the cutting chips of a workpiece from being welded to the tip portion of the tool body. With the goal.

[0005]

[Means for Solving the Problems] By solving the above problems,
In order to achieve such an object, according to the present invention, a chip discharge groove extending from the tip of the tool body toward the rear end is formed on the outer periphery of the tool body tip portion having a substantially cylindrical shape. A drilling tool in which a throw-away tip having a cutting edge is detachably attached to the tip of a groove, wherein the surface of the tip of the tool body is coated with a DLC film. With this configuration, the surface of the tool body tip is coated with a DLC film that has an overwhelmingly small coefficient of friction, and even if the workpiece is made of a non-ferrous metal such as aluminum or copper, which is easy to weld. Even when drilling is performed, the chips can be prevented from being welded to the surface of the tool body tip, that is, the outer peripheral surface and the wall surface of the chip discharge groove. It is possible to keep it high while maintaining good chip discharge performance.

Further, if the DLC film becomes too thin, the effect of coating may be difficult to obtain, and conversely, if the DLC film becomes too thick,
The thickness of the DLC film is preferably set in the range of 1 to 15 μm because the cost may increase and the coating itself may become brittle and crack easily.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a plan view showing a throw-away type drilling tool according to an embodiment of the present invention, FIG.
Is a side view of the throw-away type drilling tool shown in FIG.
FIG. 3 is a front view of the throw-away type drilling tool shown in FIG. 1.

The throw-away type drilling tool according to the present embodiment is a two-blade throw-away type drill, and the tool main body 11 is made of, for example, steel and has a substantially multi-stage cylindrical shape with an axis O as the center. None, a drill portion 12 having a substantially cylindrical outer shape from the front end to the rear end side, and a substantially frustoconical flange portion 13 having a diameter increased by one step from the drill portion 12.
And the outer diameter is smaller than the flange portion 13 and the drill portion 12
And a shank portion 14 having a substantially cylindrical shape larger than that.

Further, on the outer peripheral surface of the shank portion 14,
Mounting surface 14A that cuts up to the outer peripheral side as it goes to the rear end side
Further, a cutting oil supply hole 15 is formed along the axis O from the rear end surface 14B of the shank portion 14 toward the front end side of the tool body 11. And
The supply hole 15 is communicated with a sub-supply hole 16 formed in the flange portion 13 from the outer peripheral side thereof, and
It branches into two and extends toward the tip side of the tool body 11, and is opened at the tip surface 12A of the drill portion 12, that is, the tip surface of the tool body 11. A plug 17 that seals the auxiliary supply hole 16 when not in use is screwed into the auxiliary supply hole 16.

Further, on the outer periphery of the tool body 11, there are provided a pair of chip discharge grooves 18, 19 from the tip surface 12A of the drill portion 12 to the flange portion 13 so as to be located on opposite sides with the axis O interposed therebetween. The outer peripheral surface 12B of the drill portion 12 and the outer peripheral surface 13A of the flange portion 13 are opened. Furthermore, these chip discharge grooves 18, 1
Tip mounting seats 20 and 21 are formed at the tips of the wall surfaces 18A and 19A facing the front side of the tool rotation direction T of 9, respectively. Chips 22 can be attached to and detached from the tip mounting seats 20 and 21 by a clamp screw 23, respectively. Is installed,
This provides the cutting edge 24 in the present embodiment.

Here, these chip mounting seats 20 and 21
Is arranged such that the chip mounting seat 20 formed at the tip of one chip discharging groove 18 is biased toward the inner peripheral side of the tool body 11 with respect to the chip mounting seat 21 formed at the tip of the other chip discharging groove 19. Accordingly, in this embodiment, the tips 22 and 22 are also attached to the tool body 11 at positions that are biased toward the inner peripheral side and the outer peripheral side.

Further, in the present embodiment, these chips 22 and 22 are made of a hard material such as cemented carbide and have a substantially rhombic flat plate shape of the same shape and size. A cutting edge 24 that is formed as a rake face toward the front side in the tool rotation direction T and is formed on the side ridge of this rake face.
One of the ... Is projected to the tip of the tool body 11 and is attached to the tip mounting seats 20 and 21. Then, in this mounted state, the tips 22, 22 are such that the inner peripheral end of the cutting edge 24 of the tip 22 located on the inner peripheral side of the tool becomes overcenter beyond the axis O and the tip 22 of the outer peripheral side of the tool is The outer peripheral edge of the cutting edge 24 slightly protrudes toward the outer peripheral side from the outer peripheral surface of the drill portion 12, and these cutting edges 2
The rotation loci of the axes 4 and 24 about the axis O are arranged so as to overlap each other.

On the other hand, as shown in FIG. 2, in the chip discharge grooves 18 and 19, the wall surfaces 18A and 19A are parallel to the axis O at the tip of the drill portion 12 where the chip mounting seats 20 and 21 are formed. On the other hand, on the rear end side thereof, a twist groove is formed which is twisted toward the rear side in the tool rotation direction T toward the rear end side of the tool body 11 in the axis O direction. Also, these chip discharge grooves 18, 1
9 is the above-mentioned wall surface 1 at the tip of the drill portion 12.
8A, 19A and the wall surface 18 facing the tool rotation direction T rear side
B and 19B define a substantially V-shape as shown in FIG. 3, while the wall surface 18A, 1
Between 9A and wall surfaces 18B and 19B, wall surfaces 18A and 19
Arc-shaped concave curved surfaces 18C and 19C which are concave with respect to A on the axis O side and which are smoothly continuous with the wall surfaces 18B and 19B are formed.

Then, the drill portion 12 and the flange portion 13
The entire surface of the (tool body tip portion), that is, the tip surface 12A of the drill portion 12, the outer peripheral surface 12B, the chip discharge groove 18,
19 wall surfaces 18A, 18B, 18C, 19A, 19B,
19C and the entire outer peripheral surface 13A of the flange portion 13, as shown by the dots in the drawing, the film thickness is 1 to 15 μm.
It is coated with the DLC film 30 set in the range of m. The DLC film 30 coating the surfaces of the drill portion 12 and the flange portion 13 is synthesized by a gas phase synthesis method using ions, has properties similar to diamond, and has a high hardness.
Although it has a low coefficient of friction, it is cheaper than diamond.

In the drilling tool thus constructed, the shank portion 14 is fitted into the spindle end or the like such that the flange portion 13 of the tool body 11 is in close contact with the tip surface of the spindle end or the like of the machine tool. Then, the mounting surface 14A is pressed to be held at the spindle end or the like, and while being rotated around the axis O, is sent to the tip side in the direction of the axis O, and the drill portion 12
With the cutting edges 24, 24 of the most advanced chips 22, 22, for example, a workpiece made of non-ferrous metal such as aluminum or copper is cut and drilled.

Here, although non-ferrous metals such as aluminum and copper have the property of being extremely easily welded, in the present embodiment, the surfaces of the drill portion 12 and the flange portion 13 made of steel have an overwhelming friction coefficient. Since the DLC film 30 is small in size, the cutting edges 24, 2
The chips generated in No. 4 are the tip surface 12 of the drill part 12.
A, the outer peripheral surface 12B and the wall surface 18 of the chip discharge grooves 18 and 19
A, 18B, 18C, 19A, 19B, 19C and the outer peripheral surface 13A of the flange portion 13 can be prevented from being welded. As a result, it is possible to maintain the accuracy of the inner wall surface of the machined hole formed in the work with high accuracy and to keep the chip discharging property excellent, and it is possible to form a machined hole of good quality with high efficiency. Further, by coating the surface of the drill portion 12 and the flange portion 13 with the DLC film 30 having high hardness, the strength thereof is improved,
It is also possible to extend the tool life.

The thickness of the DLC film 30 is set to 1 to
By setting the thickness to an appropriate range of 15 μm, the effect of forming the DLC film 30 can be favorably maintained, and when the thickness of the DLC film 30 becomes smaller than 1 μm, the effect of the coating can be obtained. If it is larger than 15 μm, the cost may increase or the coating itself may become brittle and crack easily.
In addition, in order to secure the effect as described above, the thickness of the DLC film 30 is preferably set in the range of 2 to 6 μm.

Further, in the present embodiment, the present invention is
The case of applying to a single-blade throw-away type drill has been described, but the present invention is not limited to this, and there are design changes within the scope not departing from the gist of the present invention, or other throw-away type drilling tools. It goes without saying that the present invention may be applied.

[0019]

As described above, according to the present invention,
Since the tip of the tool body is coated with a DLC film that has an overwhelmingly low coefficient of friction, even when drilling a workpiece made of non-ferrous metal such as aluminum or copper that is easily welded, It is possible to prevent chips from adhering to the surface of the tip of the tool body.This keeps the precision of the inner wall surface of the machined hole high, while maintaining good chip discharge performance and improving the quality of machined holes. It can be formed efficiently.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

2 is a side view of the embodiment shown in FIG. 1. FIG.

FIG. 3 is a front view of the embodiment shown in FIG.

[Explanation of symbols]

11 Tool Body 12 Drill Part (Tip Part of Tool Body) 12A Tip Surface 12B of Drill Part 12 Peripheral Surface of Drill Part 13 Flange Part (Tip Part of Tool Main Body) 13A Outer Surface of Flange Part 18, 19 Chip Discharge Grooves 18A, 18B , 18C, 19A, 19B, 19C Chip discharge groove wall surface 22 Throw-away tip 24 Cutting edge

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoji Takiguchi             1528, Nakashinden, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture             Address Mitsubishi Materials Corporation Gifu Factory             Within F-term (reference) 3C037 CC01 CC06

Claims (2)

[Claims] 1. A chip discharge groove extending from the tip of the tool body toward the rear end is formed on the outer periphery of the tool body tip portion having a substantially columnar shape, and a throw having a cutting edge at the tip of the chip discharge groove. A throw-away drilling tool in which an away tip is detachably mounted, wherein a surface of a tip portion of the tool body is coated with a DLC film. 2. The throw-away drilling tool according to claim 1, wherein the thickness of the DLC film is set in a range of 1 to 15 μm.