JP3019298B1 - Surface coating drill - Google Patents

Abstract

Abstract: [PROBLEMS] To provide a long-life coated drill by controlling the thickness of a film on a scooping surface and a margin portion at the time of coating to make use of the original function of a hard film and increasing the thickness thereof. In a drill covered with a hard coating layer, the thickness of the coating layer at the drill tip and / or in the vicinity thereof is:
It is characterized in that it is thin at the flank and a honing portion provided at the boundary between the flank and the scooping surface, and thick at the scooping surface and the margin portion. A drill provided with a second cutting edge in the direction, coated with a hard coating layer, wherein the thickness of the coating layer is a flank, a honing portion provided at the boundary between the flank and the scooping surface, a margin portion, and a The scooping surface with two cutting edges is thin,
It is configured by thickening the scooping surface at the tip and the margin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface coated drill, and more particularly to a hard coated film thickness.

[0002]

2. Description of the Related Art In recent years, coated drills in which a drill made of a high-speed steel, a cemented carbide or the like is coated with a hard substance have been widely used. Although such coated drills have high efficiency processing and long life as their main purposes, it is important that the hard coating at the tip of the drill fully exerts its functions in order to meet the purpose. However, in the conventional coating drill, whether the thickness of the coating film at the tip portion is substantially the same at almost any portion, or as described in JP-B-6-28811, whether the thickness is small at the side of the drill and thick at the tip portion, It is known that by re-grinding the margin portion as in Japanese Patent Publication No. 1-50527, the thickness of the coating film on the margin portion (and flank) is consequently made smaller than other portions. Thus, it was difficult to say that the function of the hard film was sufficiently utilized.

[0003]

SUMMARY OF THE INVENTION The present inventors have conducted intensive studies on how a hard coating can exhibit its function sufficiently. (1) The hard coating does not peel off during cutting. The conclusion that (2) the hard film must be worn by rubbing wear without being damaged, and (3) that the time until the hard film is worn down especially at the margin and the scooping surface is required. Obtained.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a coated drill having a long life by controlling the thickness of the scooping surface and the film of the margin portion at the time of coating, thereby making the most of the original function of the hard film and increasing the thickness. The purpose is to:

[0005] In order to achieve (3), the thickness of the margin portion and the scooping surface can be increased. And this is exactly the point that should be distinguished from the conventional technology. Also,
When the wear state of the covering drill is observed sequentially, for example, even if the thickness of the covering film at the margin portion is increased, if the thickness of the covering film at the scooping surface at the drill tip is thin, the margin / scooping surface boundary Exposure phenomena of the drill body appear early, and once the exposed part appears, it quickly spreads to the margin, resulting in early tool life. Therefore,
It was concluded that the most effective method was to increase the thickness of the coating on the scooping surface and the margin.

[0006]

For Means for Solving the Problems] As a first aspect of the present invention, in coating the general hard layer drill, in a drill coated with a hard layer, the drill tip and de
The thickness of one or both of the coating layers in the vicinity of the tip of the rill is thin at the honing portion provided at the boundary between the flank surface and the flank surface and the scooping surface, and thick at the scooping surface and the margin portion. It is a surface coating drill. Further, in the second invention, in the drill coated with a hard layer, either the contact vicinity of the peripheral cutting edge and the tip blade radial and one axial
Alternatively, provide a second cutting edge on both, and
The thickness of one or both of the coating layers in the vicinity of the tip of the knuckle is thinner at the honing part provided at the boundary between the flank face and the flank face and the scooping face, and thick at the scooping face and the margin part. It is a surface coating drill.

The method of coating a drill is roughly classified into a chemical vapor deposition method (hereinafter, referred to as a CVD method) and a physical vapor deposition method (hereinafter, referred to as P method).
It is called VD method. )It has been known. In the CVD method, tensile stress generally remains in the film, and in the PVD method, compressive stress remains. If the residual stress is too large, the coating film is likely to be damaged, which is not preferable in practical use. However, the residual stress tends to increase as the film thickness increases. Although the residual stress can be reduced to some extent depending on the coating conditions, the residual stress may remain in order to utilize the characteristics of the film. In this case, the residual stress is particularly likely to concentrate and accumulate on the ridge portion, so that the coating film may self-destruct at the ridge portion or a peeling phenomenon may occur during drilling.

As means for avoiding the above-mentioned phenomenon,
It was found that it is very effective to make the ridges round before or after coating. Regardless of the CVD method, P
In the VD method, the film is generally deposited in a direction perpendicular to the surface of the substrate. The residual stress is the amount of deposition per unit area, but by rounding the ridge, the amount of deposition in unit area can be reduced. As a result, the phenomenon of film peeling or breakage during cutting is eliminated, and the film is worn away by abrasion. In this case, an appropriate range of the radius of curvature of the roundness is basically defined by the magnitude of the residual stress and the film thickness. However, a range of 0.5 to 50 microns is practically preferable. Outside this range, the effect of rounding is insufficient.

Further, in a drill provided with a second cutting edge in one or both of the radial direction and the axial direction in the vicinity of the contact point between the margin portion and the cutting edge, a portion of the scooping surface of the second cutting edge is formed. It was found that the thinner the film, the better. This is because peeling of the film hardly occurs. The thinner the film, the smaller the thickness.
A range of 5-7 microns, with the thicker being 2-20 microns is appropriate. Next, the second cutting edge is provided with a longer cutting edge at the tip portion and the outer peripheral portion, and the length of the second cutting edge is set to 0.01 to 0.2 times the drill diameter. 0.01
If it is less than twice, it is too short to have an effect on chipping resistance and the like, and if it is more than 0.2, the tip becomes stepped, and problems such as burrs tend to occur in drilling and the like. The length of the second cutting edge is 0.01 to 0.2 of the drill diameter.
Doubled.

[0010] When a used drill is used after re-grinding and re-coating, it is extremely easy to achieve the purpose of the present invention, and its effect can be expected sufficiently. That is, when the re-grinding, surface relief for the drill tip, the cutting edge honing unit, whereas either the radial and axial direction in the contact vicinity of (and margin portion and the cutting edge also
In the case of a drill provided with a second cutting edge on both sides, re-grinding is performed only on the margin) and the margin and flank are intentionally not ground, and then the re-coating is performed. Is as in the present invention, and the maintenance or improvement of the drill characteristics is sufficiently recognized. Of course, rounding the ridge line formed between the surfaces after re-grinding and before re-coating after re-grinding or re-coating greatly improves the peeling resistance and the drill performance.

Further, the present invention is directed to a general drill coated with a hard film, and the effect can be expected regardless of the type of the hard film. That is, TiN, TiCN, Ti
Not only films of C and TiAlN but also other periodic table 4a, 5a
It is effective for any film such as carbides, nitrides, carbonitrides, borides, oxides or a combination thereof, a single-layer film and a multi-layer film of the group a and 6a.

[0012]

EXAMPLE An ultrafine cemented carbide was manufactured using a commercially available mixed powder of WC powder having an average particle diameter of about 0.5 micron and Co powder of about 1 micron and mixed in an alcohol for 6 hours with an attritor. And a twist drill made of cemented carbide having a twist angle of 30 degrees. Next, this twist drill is attached with a cathode type arc ion plating,
First, the temperature of the substrate is heated to 500 degrees by a heater, and a bias voltage is applied to the substrate while maintaining the temperature, and high-purity nitrogen gas and methane-based gas are introduced into the apparatus, and arc discharge is started. Ti on straight surface
Films of N, TiCN, and TiAlN were formed. Table 1 shows the results. Some samples of solid carbide drills include:
The corners of the ridge were rounded at a predetermined radius of curvature.

[0013]

[Table 1]

Next, the cutting specifications are SCM4 as the work material.
Using 40, cutting speed 60m / min, feed speed 0.2m
m / rotation, hole depth 24 mm (three times the blade diameter). The tool life was determined until the cutting chips were long and cutting was judged to be inappropriate for further cutting, and the number of machined holes at that time was compared. The results are also shown in Table 1.

It can be seen that when the thickness of the scooping surface and the margin is increased as described above, the number of processed holes is significantly increased.
In particular, the one provided with the second cutting edge is advantageous because the radius of curvature of the ridge line can be set smaller.

[0016]

According to the present invention, a tool having a longer life can be obtained by increasing the thickness of a specific portion. In addition, when re-grinding and re-coating, a surface coating having a uniform thickness is newly obtained. There is also an effect that man-hours such as film removal can be omitted as compared with manufacturing a drill.

Claims (4)

(57) [Claims] 1. A drill coated with a hard coating layer,
Either the drill tip or near the drill tip or
A surface-coated drill characterized in that the thickness of both coating layers is thin at a flank and a honing portion provided at a boundary between the flank and the scooping surface, and thick at a scooping surface and a margin portion. 2. A drill covered with a hard coating layer,
Dochi the contact vicinity of the peripheral cutting edge and the tip blade radial and axial
A second cutting edge is provided on one or both sides, and the thickness of one or both of the drill tip and the vicinity of the drill tip is reduced to the flank, the flank, and the scooping surface. A surface-coated drill characterized in that it is thin at the honing part and thick at the scooping surface and the margin part provided at the boundary of. 3. The surface-coated drill according to claim 1, wherein a ridge portion formed by a scooping surface and a flank surface at a tip portion of the drill has a radius of curvature of 0.5 to 50 μm. Drill. 4. The surface-coated drill according to claim 2, wherein the length of the second cutting edge is from 0.01 to 0.01 mm of the drill diameter.
A surface-coated drill characterized by being 0.2 times larger.