JPH0615513A - Throwaway drill - Google Patents

Abstract

PURPOSE:To provide a throwaway type drill capable of reducing the number of processes for boring a tapered bore and furthermore decreasing load affected on a tool in one process. CONSTITUTION:In a throwaway drill provided with a plural number of helical flutes 13a, 13b on the outer peripheral part of a tool main body 10 axially rotated and throw away tips 16a, 19a on the point part of a wall surface facing the rotational direction of each of the helical flutes 13a, 13b so that the cutting blades of the throwaway tips 16a, 19a face the point side and rotational loci of the cutting blades are overlapped with each other and make a circle, the helical flutes 13a, 13b are separated from the throwaway tips 16a, 19a toward the base end side. Simultaneously, the cutting blades are arranged so that diameter of the cutting blades becomes gradually larger from the point side to the base end side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throwaway type drill for machining a tapered hole.

[0002]

2. Description of the Related Art Conventionally, when forming a tapered hole, as shown in FIG. 5, a cylindrical pilot hole is first processed by a straight drill A (a), and this pilot hole is tapered by a taper drill B. It was processed (b), and finally, the taper reamer C was used to finish the tapered hole (c). Here, in the taper drill B, the tip blade 1 is provided at the intersection of the wall surface facing the rotation direction of the spiral groove 1 and the tip flank.
An outer peripheral blade 3 is formed at the intersection of the spiral groove 1 and the outer peripheral surface of the tool.

[0003]

However, in the machining method as described above, when the taper hole is machined (b), the entire outer peripheral edge 3 of the taper drill B bites into the work material, so that the cutting torque is increased. Therefore, there is a problem that so-called chatter vibration is generated and the cutting surface is roughened, and in some cases, the taper drill B is broken. Further, there is a problem that the processing efficiency of the tapered hole is low because the three steps are required to process one tapered hole as described above.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to reduce the number of steps of taper hole machining and to reduce the load acting on a tool in one step. The purpose of the present invention is to provide a formula drill (hereinafter, simply referred to as "drill").

[0005]

A drill of the present invention is provided with a throw-away tip, which has a circular shape in which the loci of rotation overlap each other, at the tip of a spiral groove provided in the outer peripheral portion of a tool body. The cutting blade is arranged so as to be separated from the throw-away tip toward the base end side, and the diameter of the cutting blade gradually increases from the tip end side toward the base end side.

[0006]

[Operation] In the drill having the above-mentioned structure, the cutting edge on the most distal side makes a hole corresponding to the rotation locus, and the cutting edge arranged on the proximal side makes a hole having a larger diameter successively. To be done. In this way, the cutting blades arranged from the distal end side to the proximal end side are used to machine holes whose inner diameter gradually increases,
After that, the inner circumference of the hole is tapered by, for example, a taper reamer. As described above, in the drill having the above-described structure, it is possible to process a stepped hole having a shape close to a taper by one-time processing. Therefore, it is possible to reduce the number of steps by one compared with the conventional method. Moreover, since the length of the part of the cutting blade that bites into the work material is short, the cutting torque is small, and therefore chatter vibration and the like can be prevented from occurring.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
Will be described with reference to. FIG. 1 is a side view showing a drill of the embodiment. Reference numeral 10 in the drawing is a tool body. The tool main body 10 has a columnar shape, and includes a shank 11 on the base end side and a tip mounting portion 12 on the tip end side. Tip mounting part 1
Reference numeral 2 includes four portions, a tip portion 12a, intermediate portions 12b and 12c, and a base end portion 12d, and the outer diameters of these portions gradually increase from the tip end side to the base end side.

Two thread grooves 13a and 13b are formed on the outer periphery of the chip mounting portion 12. Twist groove 13
As shown in FIG. 2, a and 13b have a V-shaped cross section, and have a spiral shape so as to recede toward the opposite side to the rotation direction from the distal end side toward the proximal end side. And
On the wall surfaces of the twisted grooves 13a and 13b facing the rotation direction, the above-mentioned tip portion 12a, intermediate portions 12b and 12c, and the base end portion 1
Throw away chips (hereinafter, simply referred to as “chips”) are arranged every 2d.

A tip seating portion 15 is formed at the tip of one of the twisted grooves 13a, and a tip 16a having a corner portion 16b aligned with the axis 0 is detachably attached to the tip seating portion 15 by a clamp bolt 17. Has been. Further, the tip seating portion 18 is also formed on the tip end portion of the other twisted groove 13b, and the tip seating portion 18 has a tip 19a.
a is detachably attached by a clamp bolt 17. The cutting edges 20a and 21a of the chips 16a and 19a are formed on the tip ridge of the rake face, and the cutting edges 20a and 21a overlap each other due to the rotation locus, so that the outer circumference of the cutting edge 21a from the axis line 0a. It is designed to process holes up to the end.

Next, in the twist groove 13b, the intermediate portion 12b is formed.
The tip 19b is attached to the position of, and the tip 19d is attached to the position of the base end portion 12d in the same manner as described above. Also,
Even in the twist groove 13a, the tip 16 is provided at the position of the intermediate portion 12c.
c is attached. And the chips 19b, 16
c and 19d have a cutting edge 21 at the tip ridge of the rake face.
b, 20c, and 21d are formed, and are arranged so that the cutting edge outer diameter increases in that order.

The chips 19a, 19b, 16c,
19d is arranged so that the outer peripheral end of the cutting edge in the rotation locus is located on a substantially straight line, and the angle between the straight line and the axis O is the angle between the inner circumference of the hole to be machined and the center line. The same, that is, the same taper as the processed hole is set. Further, each of the tips 19a is a positive tip in which the rake face and the flank face intersect at an acute angle, and each cutting edge has a positive axial rake angle corresponding to the helix angle of the helix grooves 13a, 13b. Is attached.

Next, a procedure for processing a tapered hole using the drill having the above structure will be described with reference to FIG. First, the work material W is processed by the drill D. At this time, first, the cutting blades 20a and 21a on the most distal side process a hole Ha that coincides with the rotation locus, the cutting blade 21b arranged on the proximal end side makes a hole Hb, and the cutting blade 20c makes a hole H. The hole Hd is processed by the cutting blade 21d.
Next, the hole H is processed by a taper reamer C and finished in a taper shape. The cutting allowance at that time is a portion on the inner peripheral side of the two-dot chain line in FIG.

As described above, in the drill D having the above-mentioned structure, since the stepped hole H having a taper can be formed by one-time processing, the number of steps can be reduced by one compared with the conventional method. . Moreover, since the length of the part that bites into the work material W as a whole cutting edge is short, the cutting torque is small, and therefore,
It is possible to prevent chatter vibration and the like, as well as chipping of the cutting edge and breakage of the drill. Further, in the above-mentioned drill D, since the cutting edge is arranged with the same taper as the processing hole, the load applied to the cutting edge in the processing by the taper reamer becomes uniform, so that the taper reamer can be processed smoothly, Chatter vibration and the like can be prevented.

Although the cutting blades are arranged in a straight line in the above embodiment, the present invention is not limited to such a structure as long as the cutting blade outer diameter increases toward the base end side. Further, although the above embodiment is a screw-on type drill, a clamp-on type drill may be used. Further, in the above-described embodiment, the twist groove is configured so that the cutting edge is parallel to the wall surface of the twist groove in bottom view, but as shown in FIG. 3, the wall surface 30a facing the rotation direction of the twist groove 30 is The cutting edge of the tip 16a may be inclined in the direction of rotation. Further, the twist groove is not limited to the two threads as in the above embodiment, but three or more threads may be formed.

[0015]

As described above, in the drill of the present invention, the tip of the spiral groove provided on the outer peripheral portion of the tool body is provided with the throwaway tip forming a circle with the rotation loci overlapping each other. , The cutting edge is arranged so as to be separated from the throwaway tip toward the base end side and gradually increase in diameter from the tip end side toward the base end side. Thus, a stepped hole close to a taper can be processed, and the number of steps can be reduced by one compared with the conventional method. In addition, since the length of the part of the cutting edge that bites into the work material is short, the cutting torque is small, and therefore chatter vibration and the like can be prevented.

[Brief description of drawings]

FIG. 1 is a side view showing a drill according to an embodiment of the present invention.

FIG. 2 is a bottom view of the drill shown in FIG.

FIG. 3 is a bottom view of the drill showing a modification of the drill shown in FIG. 2.

FIG. 4 is a side view showing a step of processing a tapered hole with the drill of the present invention.

FIG. 5 is a side view showing a conventional method for processing a tapered hole.

[Explanation of symbols]

0 axis 10 tool body 13a, 13b twist groove 16a, 16c, 19a, 19b, 19d tip (throw away tip)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yoshikazu Iwata Yoshikazu Iwata 1528, Nakashinden, Yokoi, Kobe, Anpachi-gun, Gifu Prefecture Mitsubishi Materials Corporation Gifu Factory (72) Hiroshi Kasuya 2 Higashisakura, Naka-ku, Nagoya-shi, Aichi 22-22, Nikko Building, 4th floor, Nikko Building, Mitsubishi Materials Corporation, Nagoya First Branch

Claims (1)

[Claims] 1. A plurality of twist grooves are provided on an outer peripheral portion of a tool body which is rotated around an axis, and a throwaway tip has a cutting edge at the tip end side of a wall surface of the tool body which faces the rotation direction of each twist groove. In a throwaway type drill provided so as to face each other and the rotation loci of each cutting edge overlap each other to form one circle, the twist groove is separated from the throwaway tip toward the base end side, and A throwaway type drill in which cutting blades are arranged such that the diameter of the blade gradually increases from the tip side toward the base side.