JPH0615511A - Boring of tapered bore - Google Patents

Abstract

PURPOSE:To bore a stepped but near to tapered bore in one boring and to reduce the number of production processes by roughly boring it with a drill furnished with a point cutting blade the rotational locus of which makes a circle and a diametrically extensional cutting blade provided on the base end side rather than this point cutting blade and gradually extending its cutting blade outer diameter toward the base end side. CONSTITUTION:A prepared hole is roughly bored by a drill, and thereafter, it is finished and bored as a tapered bore with a tapered tool. This rough boring is carried out with the drill furnished with point cutting blades 20a, 21a the rotational locus of which makes a circle and diametrically extensional cutting blades 21b, 20c, 21d provided on the base end side rather than these point cutting blades 20a, 21a and gradually extending their cutting blade outer diameter toward the base end side. Consequently, it is possible to bore a stepped but near to tapered bore in one boring and to reduce the number of production processes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for machining a tapered hole using a drill and a taper reamer.

[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. The machining was carried out (b), and finally, the taper reamer (tapered tool) C was used to finish the taper hole (c). Here, taper drill B
Has a tip blade 1 formed at the intersection of the wall surface of the spiral groove 1 facing the rotation direction and the tip flank, and an outer peripheral blade 3 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 can reduce the number of steps for machining a tapered hole and reduce the load acting on the tool in one step. The purpose is to provide a processing method.

[0005]

The taper hole machining method of the present invention comprises the steps of roughly machining a prepared hole with a drill and then finishing the tapered hole with a taper tool. Performed by a drill provided with a tip cutting edge having a circular path, and a diameter-increasing cutting edge provided on the base end side of the tip cutting edge and having an outer diameter of the cutting edge gradually increasing toward the base end side. It is characterized by that. That is, the tip cutting blade processes a hole corresponding to the rotation locus, and the diameter-increasing cutting blade arranged on the base end side of the tip cutting blade sequentially processes a hole having a larger diameter than that. In this way, the tip cutting blade and the defining cutting blade are used to machine a hole whose inner diameter gradually increases, and then the inner circumference of the hole is tapered by, for example, a taper reamer.

As described above, according to the tapered hole machining method of the present invention, since a stepped hole close to a taper is machined by one machining, the number of steps can be reduced by one compared with the conventional method. Further, since the length of the part of the cutting blade that bites into the work material can be shortened, 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. Here, prior to the description of the taper hole drilling method of the embodiment, the configuration of a drill used for taper hole drilling will be described. FIG. 1 is a side view showing the drill. Reference numeral 10 in the drawing is a tool body. Tool 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. The tip mounting part 12 is
Tip part 12a, middle parts 12b and 12c, base end part 12d
The outer diameter of each of the four parts is gradually increased from the distal end side to the proximal 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 tip cutting edges 20a and 21a are respectively formed on the tip ridges of the rake faces of the tips 16a and 19a.
a is formed, and the tip cutting edges 20a and 21a overlap each other due to the locus of rotation to form a hole of a size from the axis 0 to the outer peripheral end of the tip 16a.

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
The c and 19d are formed such that the diametrical cutting edges 21b, 20c and 21d are respectively formed on the tip ridge line portion of the rake face, and the cutting edge outer diameter is sequentially increased 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 above drill will be described with reference to FIG. First, the work material W is processed by the drill D. that time,
First, the tip cutting blades 16a and 19a are used to machine a hole Ha that coincides with the rotation locus thereof. The diameter-increasing cutting blade 19b arranged on the base end side expands the hole Hb and the diameter-increasing cutting blade 16c expands the hole H. The hole Hd is processed by the cutting blade 19d. 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 above-described taper hole machining method, since the stepped hole H having a taper shape is machined by one machining, the number of steps can be reduced by one compared with the conventional method. Further, since the length of the part that bites into the work material W as a whole cutting edge can be shortened, the cutting torque is small, and therefore chatter vibration and the like occur, as well as chipping of the cutting edge and drilling. It is possible to prevent a breakage accident from occurring. Further, in the above-described machining method, since the drill D in which the cutting edge is arranged with the same taper as that of the machining hole is used, the load applied to the cutting edge during machining by the taper reamer becomes uniform, so that the taper reamer can be machined smoothly. The chatter vibration of the taper reamer can be prevented.

In the drill used in the above embodiment,
Although the cutting blades are arranged in a straight line, the present invention is not limited to such a drill as long as the cutting blade outer diameter increases toward the base end side. Further, although the screw-on type drill is used in the above embodiment, a clamp-on type drill may be used. Further, in the above embodiment,
Although a drill having a twisted groove is used so that the cutting edge is parallel to the wall surface of the twisted groove in a bottom view, as shown in FIG. 3, the wall surface 30a facing the rotation direction of the twisted groove 30 is used.
However, a drill configured to incline in the direction of rotation with respect to the cutting edge of the tip 16a may be used. Furthermore, the finishing process is not limited to the taper reamer,
The type of tool does not matter as long as the rotation locus of the cutting blade is tapered and continuous.

[0015]

As described above, the tapered hole drilling method of the present invention includes the steps of roughly working the prepared hole with a drill and then finishing the tapered hole with a tapered tool.
The rough machining, a tip cutting edge having a circular rotation locus, and a diameter-increasing cutting edge provided on the base end side with respect to the tip cutting edge, and having a cutting edge outer diameter gradually increasing toward the base end side. Since it is carried out by a drill equipped with, it is possible to process a stepped hole close to a taper by one processing, and it is possible to reduce the number of steps by one compared with the conventional method. Further, since the length of the part that bites into the work material as the entire cutting edge can be shortened, the cutting torque at the time of cutting can be reduced, and therefore chatter vibration and the like can be prevented from occurring. And so on.

[Brief description of drawings]

FIG. 1 is a side view showing a drill for performing processing 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 a drill showing a modified example of the drill shown in FIG.

FIG. 4 is a side view for explaining the taper hole processing method of the present invention.

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

[Explanation of symbols]

 A Taper reamer (tapered tool) D Drill 20a, 21a Tip cutting edge 20c, 21b, 21d Expanding cutting edge

 ─────────────────────────────────────────────────── ─── 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 step of roughly machining a prepared hole with a drill and then finishing machining with a tapered tool into a tapered hole. A tapered hole drilling method, characterized in that a drill having a diameter-increasing cutting edge which is provided closer to the base end side than the blade and whose cutting edge outer diameter gradually increases toward the base end side.