JPH01271023A - Manufacture of drill shank - Google Patents

Abstract

PURPOSE:To obtain a drill shank excellent in straigntness and high in mechanical strength by swaging a hollow drill shank and then straightening its bend with straightening rollers and, besides, contracting the diameter with the straightening rollers. CONSTITUTION:A stock is cut to a prescribed length and swaged. Then, a hexagonal part as a locking part of a detachable tool for a drill shank is formed by a pressing machine. Then, a pair of straightening rollers are rotated, the interval between two shafts 23 of these rollers is adjusted so that it agrees with the external diameter of the drill shank 1 and the shank 1 is inserted from the right side to the left side. The bend of the shank 1 is straightened by many straightening surfaces 21 of these straightening rollers 2. Simultaneously with this, when the interval between these shafts 23 is contracted, pushing pressure is given by these straightening surfaces 21 to the external surface of the shank 1, the diameter of the shank 1 is contracted by plastic deformation, working hardness is generated and the mechanical strength of the shank 1 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of manufacturing a hollow drill shank having a communicating hole by swaging, and particularly to a method of manufacturing the drill shank suitable for high-speed rotation.

"Prior Art" A construction method is known in which a large number of small holes are drilled in the walls or ceiling of a concrete structure, and anchors are driven into these small holes to support a decorative board. In order to drill this small hole, a hollow communication hole is formed in the drill shank instead of the conventional rotary impact type drill, and gas is supplied from this hollow communication hole to cool the cutting tool at the tip of the drill and remove cutting waste. A proposal for discharging is described in Japanese Patent Laid-Open No. 80-282808.

Further, the structure of a drill shank having such a hollow communication hole is described in, for example, Japanese Utility Model Application Publication No. 87850/1980.

"Problem that the invention attempts to solve"
No. 87650 does not disclose any specific method for manufacturing a drill shank having a hollow communicating hole.
The present applicant has formed a drill shank having a hollow communicating hole by swaging in Utility Model Application No. 81-131381. By the way, in swaging processing, materials with hollow communication holes have one dimension and physical properties.

There are non-uniformities such as plastic working, which cause bends in the completed drill shank.

More specifically, the uniformity of the wall thickness of a material having hollow communication holes results in uneven deformation of the material during processing, resulting in bending of the product. Even if the wall thickness is uniform, if there are parts with different coefficients of friction in the circumferential direction, the amount of deformation will be uneven as well.Also, if the material's deformation resistance is uneven in the circumferential direction, This also causes bending.

In addition, when the hexagonal part (15) which is the tool operating part of the drill shank (1) as shown in FIG. 1 is formed by pressing, bending occurs due to uneven working pressure and deformation amount.

Here, the drill bit described in Japanese Utility Model Application Publication No. 80-87850 or the drill described in Japanese Patent Application Publication No. 60-282808 is a conventional one? 2.0 faster than an IT-driven drill
00 to 11,0 OOR, P, 8 or more. These drills have a fixed proximal end, but
Since the other end, ie, the cutting edge, is a free end, if the drill shank is bent, vibration will occur during drilling.

This vibration not only impedes drilling efficiency.

This results in disadvantages such as wear and tear on the drill bit.

The tip of the drill mentioned above uses an expensive diamond tool, so there is no way to prevent this tool from wearing out or breaking! 1! This is an important issue.

"Structure of the Invention" After a hollow drill shank having a communicating hole in the axial direction is formed into a predetermined shape by swaging processing, the bending of the drill shank caused by the swaging processing is corrected by a correction roller, and In this method of manufacturing the hollow drill shank, the correction roller presses the surface of the drill shank to reduce its diameter by plastic deformation.

"Action of the Invention" After a hollow drill shank having a communicating hole in the axial direction is formed into a predetermined shape by swaging processing.

By correcting the bent hollow drill shank using a straightening roller, the hollow drill shank is corrected and becomes straight. During this straightening process, a straightening roller presses the surface of the hollow drill shank and reduces the diameter by plastic deformation, so that the surface of the hollow drill shank is work hardened and the hollow drill shank is The mechanical strength of the drill shank itself is improved.

``Example'' The drawings show an example of the present invention, in which Figure 1 is a perspective view of the drill shank, Figure PI42 is an explanatory diagram explaining the bending of the drill shank, and Figure 3 is a correction roller. 4(a) is a side view of the correction roller device, FIG. 4(b) is a partial sectional view of FIG. 4(a), and FIG. 5(a) is a front view of the device.
5(a) is a side view of another correcting roller, and FIG. 5(b) is a partial sectional view of the correcting roller of FIG. 5(a).

In FIG. 1, the drill shank with a hollow communicating hole has a parallel part, a taper 8813, and a hollow part,
A hexagonal part for operating an attachment/detachment tool is formed near the base end, and a mounting screw 16 is carved in the base end. Further, although not shown, a diamond bit is attached to the tip part to form a drill.

If the drill shank 1 is bent as described in the previous section after the swaging process, the form of this bending varies depending on the size and shape of the product. In Fig. 2, when the axis cl of the small diameter part of the drill shank l and the axis C2 of the large diameter part are bent at point CO, the amount of bending is t, which connects point a1 and point s.
It is represented by the maximum opening lie between aC and lines C1 and CI.

Such bending usually occurred by a maximum of 2 to 0.5 mm.

A straightening roller device for carrying out the present invention is shown in FIG.
As shown in FIG. 4(a), a pair of straightening rollers has straightening surfaces 21 and relief portions 22 alternately arranged on their outer circumferential surfaces, and the outer circumferential shape of the roller 2 has a hollow through hole as shown in the figure. It has a shape that matches the outer diameter shape of the drill shank l. 'W4 front 21 and escape B! The details of 622 are formed alternately in an annular shape in the outer circumferential direction, as shown in the partial cross-sectional view of FIG. 4(b).

Further, the pair of correction rollers 2 are fitted onto a drive shaft 23, and are attached to the drive shaft 23 by a nut 25 via a flange 24.
Although not shown, this drive shaft 23 is connected to a drive device and configured to provide rotation necessary for correction. Further, the pair of correction rollers 2 are configured so that the width of the drive shaft 23 can be adjusted, and the drill shank l is held between the pair of correction rollers 2 in the length direction, The diameter of the surface is reduced by plastic deformation, and the mechanical strength of the drill shank 1 is increased by work hardening.

In FIG. 3, since the drill shank 1 is subjected to such a pinching correction action, a support device 4 is provided to support the drill shank 1 in a predetermined position.

FIG. 5(A) is a side view of a correction roller showing a different embodiment from the correction roller shown in FIG. 4(A).
has a large number of correction surfaces 31 in the circumferential direction, and this correction surface 31.
A large number of auxiliary straightening surfaces 33 are arranged in a lattice-like manner in the axial direction of the straightening roller 3, substantially perpendicular to the axial direction of the straightening roller 3. There is a section 32.

The tubular material for the drill shank above is JISG3.
445 machine structural carbon steel YTT types to 17 types are preferred.

This material is cut to a predetermined length and subjected to a swaging process.Then, a press machine is used to form a hexagonal portion (15 in FIG. 1) as a locking portion for the attachment/detachment tool of the drill shank. Konoto! ! As already explained, since the drill shank is bent, it is corrected using correction rollers as shown in FIGS. 3 and 4. In other words, while applying rotation to the pair of correction rollers 2, roller 2
The distance between the two shafts 23 is adjusted to match the outer diameter of the drill shank 1, and the drill shank l is adjusted as shown in FIG.
(a) from the right side to the left side. Drill shank l above
The curvature is corrected by a large number of correction surfaces 21 of this correction roller 2. At the same time, when the distance between the shafts 23 is shortened, pressing pressure is applied to the outer surface of the drill shank 1 by the correction surface 21, and the diameter of the drill shank 1 is reduced by plastic deformation, resulting in work hardening. Increases the mechanical strength of the drill shank.

The amount of curvature of the drill shank thus corrected was less than 0.1 m.

The above-mentioned drill shank l, whose bending has been corrected in this way, is
Manufacturing is completed by cutting the threaded portion 16 shown in the figure.

As a modified example, the correction roller 3 shown in FIGS. 5(a) and 5(b)
may also be used. This correction roller 3 has a correction surface 31
In addition to this, it has an auxiliary straightening surface 33, so the area of the processed surface is larger than that of the straightening roller shown in Fig. 4, which makes it a unit surface! Since the machining pressure per unit a can be reduced, there is an advantage that when machining a relatively soft material, there is no left on the surface of the drill shank 1 due to machining.

In another embodiment of the present invention, a tubular material is cut to a predetermined length, swaged twice to form a hexagonal section 15 shown in FIG. 1 using a press, and then annealed. 4
It is also possible to carry out a method in which the bend is corrected using a straightening roller device a as shown in the figure, and the diameter is reduced, followed by polishing, cutting of the screw 16 in Fig. 1, and finally surface nitriding treatment by salt bath treatment. .

[Effects of the Invention] The method of the present invention has the advantage that a drill shank with good straightness and high mechanical strength can be manufactured by a simple method of using a straightening roller.

Next, since the drill shank obtained by the method of the present invention has good straightness and high mechanical strength, due to this synergistic effect, the drill using the above drill shank has a
．． Even when rotating at high speeds of 00OR, P, 8 or higher, there is extremely little vibration, which not only improves work efficiency but also improves tool y.
iJl and breakage can be prevented. This advantage is also highly economical since drills using the drill shank according to the invention typically rotate at high speeds and use expensive diamond tools.

[Brief explanation of the drawing]

The drawings show an embodiment of the drill shank manufacturing method of the present invention, and FIG. 1 is a perspective view of the drill shank;
Fig. 2 is an explanatory diagram explaining the bending of the drill shank, Fig. 3 is a front view of the correction roller device, Fig. 4 (a) is a side view of the correction roller device, and Fig. 4 (b) is a side view of the correction roller device. Figure (a)
FIG. 5(a) is a side view of the correcting roller showing another embodiment, and FIG. 5(b) is a partial sectional view of the correcting roller of FIG.
It is a partial sectional view of the correction roller of figure (a). l...Drill shank 2...Correcting roller 3...
・Correcting roller 4...Support member applicant 16.
Yoshino Seiki Co., Ltd. Agent 16. Patent Attorney Yoshi 1) Yoshiharu Figure 2 Figure 4 (A) Figure 4 (0)

Claims (1)

[Claims] A method for manufacturing a drill shank, which comprises swaging a hollow drill shank having a communicating hole in the axial direction, then correcting the bending of the drill shank using a correction roller, and performing diameter reduction processing using the correction roller.