JPS61288910A - Surface coated drill - Google Patents

Abstract

PURPOSE:To increase wearing resistance and tenacity of a drill and improve its durability, by coating a surface of the drill of cemented carbide base material with a hard coating layer forming its thickness in the point end part larger than the thickness in the side surface part. CONSTITUTION:The surface of a drill base material is coated with a hard coating layer film by either of the carbide, nitride, oxide of metals in the periodic table 4a, 5a, 6a or Si, Al or their solid solution. The point end part of a drill, directly contributing to drilling a work, forms a surface coating layer in thickness larger than that of the side surface part. While the side surface part of a margin part or the like, decreasing cutting resistance against the work, forms the surface coating layer in thickness smaller than that of the point end part. The thickness of the surface coating layer is desired in ratio of a relation, where (point end part)/(side surface part)=1.1-3.0, and preferable with 1.0-15mum in the point end part while 0.5-10mum in the side surface part. In this way, the drill selectively improves wearing resistance and tenacity as the whole unit.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The disclosed technology belongs to the technical field of improving the strength of drills for drilling holes in metal workpieces such as mechanical parts.

Summary> In order to improve wear resistance on the surface of the cemented carbide base of the drill body, which is integrally formed in the shank part, metals from groups 4a, 5a, 5a of the periodic table, or ,Si,
This invention relates to a surface-coated drill in which one, two or more hard coating layers are formed of one of carbides, nitrides, oxides, or solid solutions of AI,
In particular, when drilling holes such as cutting blades and chisel edges, the thickness of the hard coating layer at the tip of the drill, which has a direct cutting effect during machining, is reduced by the thickness of the hard coating layer on the side of the drill, which does not affect direct cutting, such as the margin area. This invention relates to a surface-coated drill that is made thicker than the conventional drill and has both toughness and wear resistance added to the tip of the drill.

<Prior art> As is well known, drills are widely used for drilling holes in metal products such as machine parts, but in order to deal with the increased hardness of the material to be rigidified, the drill body has been manufactured using powder metallurgy, etc. Drills made of cemented carbide have come to be used, but when the workpiece material used for the purpose is a hard, difficult-to-cut material such as stainless steel, the wear of the drill becomes severe, so it is necessary to improve the wear resistance. In order to increase the number of drills, drills whose surfaces are coated with a hard coating layer on the surface of the cemented carbide base of the drill body have been developed and adopted.

For example, as disclosed in Utility Application No. 58-109353, T or C or T1C is applied to the surface of a cemented carbide drill base.
In order to improve wear resistance by coating the surface with a hard coating layer such as N, TλN, A1203, etc.,
As in the invention disclosed in Publication No. 3246, 48 and 5 of the periodic table are printed on the surface of the cemented carbide base of the miniature drill.
a, 6a1s metal carbides, nitrides, carbonitrides, carbonates, and carbonitrides, and aluminum oxide,
Furthermore, the wear resistance is improved by coating the surface with at least one hard coating layer film composed of two or more of these solid solutions,
Furthermore, drills have been developed that also have improved welding resistance.

<Problems to be Solved by the Invention> Therefore, in a drill whose surface is coated with a hard coating film based on the prior art, it is possible to improve the wear resistance of the drill by dealing with the work material. Furthermore, although attempts have been made to improve the welding resistance, a new problem has arisen in terms of the toughness of the drill.

That is, since the base of the drill body, which is intended to improve wear resistance, is made of cemented carbide, wear resistance and toughness have come to conflict with each other.

For example, in the publication "Powder and Powder Metallurgy", Vol. 32, No. 2, pages 16 to 21, there is a statement that contradicts wear resistance and toughness regarding the surface coating of a hard coating layer film on a cemented carbide substrate. It has been shown that surface coating by PVD method causes less decrease in toughness than surface coating by CVD method, and that toughness decreases as the thickness of surface coating increases.

It has been found that the influence of the thickness of the surface coating of the hard coating layer on the wear resistance and toughness "transverse rupture strength" cannot be ignored even in the case of drills.

Therefore, in the above-mentioned conventional hard coating drill, the wear resistance increases when the surface coating of the hard coating layer is made thicker, but the toughness decreases and the drill is more likely to break. If the surface coating thickness of the hard coating layer is made thinner to deal with this problem, the toughness can be prevented from deteriorating, but there is a drawback that the wear resistance deteriorates and the field width becomes shorter. Ta.

Therefore, a drill in which the surface of the cemented carbide base of the drill body is coated with a hard coating layer film of uniform thickness has the disadvantage that both cannot perform their original functions.

The purpose of this invention is to solve the problem of durability of the drill whose surface is coated with a hard coating film based on the above-mentioned conventional technology. Machining technology in the metal product manufacturing industry by increasing wear resistance and increasing toughness in the side parts where the coefficient of friction with the rigid material is low, extending the life of the drill and improving durability. It is an object of the present invention to provide an excellent surface-coated drill that will benefit the field of application.

Means and operation for solving the above-mentioned problems In accordance with the above-mentioned object, the structure of the present invention, which is summarized in the above-mentioned claims, is to solve the above-mentioned problems by drilling a hole into a metal workpiece. During processing, metals from group 48.5816a of the periodic table are applied to the cemented carbide base surface of the drill body.
Or, a layer of carbides, nitrides, oxides, or solid solutions of S, A11, or
The surface is coated with two or more hard coating layers to improve wear resistance, and the drilling of the work material directly affects machining, while the cutting edge and chisel edge, which contribute to the refining of cutting waste, At the tip of the drill, the surface coating thickness of the hard coating layer is made thicker than the side surface to improve wear resistance and welding resistance.On the other hand, wear resistance is not required at the tip. The surface coating thickness of the hard coating layer is thinner than that at the tip of the comb, in side areas such as margin areas where cutting chips are not generated and the coefficient of friction with the workpiece is reduced to reduce cutting resistance. Technical measures have been taken to improve the toughness even when torque is applied to the drill, and to selectively improve the wear resistance and toughness of each functional part of the drill as a whole.

4a of the periodic table for the cemented carbide base of the drill body integrally formed in the 91729 section.

PVD method for surface coating of one or two or more layers of hard coating film with metals of group 5a, 5a, or carbides, nitrides, oxides of Si, A/, or solid solutions thereof. , CVD method, plasma CVD method, etc. may be used. For example, when using the PVD method, the throwing power is poor, so the mutual set positional relationship between the evaporation source and the drill body is selected in an optimal state to coat the surface. By doing this, it is relatively easy to make the thickness of the tip part thicker than the thickness of the side part by a set thickness based on the surface coating thickness of the hard coating layer film.

In addition, when using the CVD method, plasma CVD method, etc.
The surface coating thickness of the hard coating layer at the tip can be adjusted to a predetermined value by means of appropriately controlling the supply of reaction gas to the side surface, or by masking the side surface of the drill body by covering it with a cylinder with an appropriate gap. It is possible to make the side part thicker than the side part.

It is desirable that the ratio between the tip and side surface of the surface coating of the hard coating layer is 1.1 to 3.0.

In this case, it has been experimentally found that with a ratio of 1.1 or less and a ratio of 3.0 or more, it is difficult to achieve both wear resistance and toughness, which meet the initial objectives.

In addition, the surface coating thickness of the hard coating layer film is 1.0 to 1 at the tip.
0.5 to 10 μm is desirable for 5 μm and 1 side surface, and if the tip is less than 1.0 ura, the wear resistance at the cutting part such as the cutting edge will deteriorate, and if it is more than 15 μm, the toughness of the tip will decrease and there will be no problem. It becomes easier.

On the other hand, in the side surface portion, if the thickness is less than 0.5 μm, the effect of reducing the cutting resistance against the work material such as the margin portion is weak, and if the thickness is more than 10 μm, the toughness decreases and the material becomes easy to break.

Therefore, it has been experimentally determined that the above range is optimal.

<Example> Next, an example of the present invention will be described below along with a comparative example of the conventional aspect.

The base of the drill body, which is integrally formed in the shank part, is a solid drill with a diameter of 10 mm made of ISO P30 grade cemented carbide, and by changing the relative position of the base and the evaporation source using the ion blating method, the following results can be achieved. TiN surface-coated drills having hard coating layer distributions as shown in Table (2) were obtained in Examples and Comparative Examples of conventional embodiments.

Table 1: Large wear, chipping, breakage, large resistance △: Small chipping. Then, set the drill shown in Table 1 above on a 15 horsepower machining center, and set the workpiece material to 550C (surface coated He250).
), using a water-soluble cutting fluid as the cutting oil, cutting speed 50 m/min, feed O9 button 1 m/rotation, hole depth 30 mm, and the number of holes machined is 864. , as shown on the right side of the above-mentioned surface work, and it can be seen that a very remarkable effect has been obtained compared to the drill of the conventional comparative example.

It goes without saying that the embodiments of this invention are not limited to the above embodiments, and various embodiments can be adopted.

<Effects of the Invention> As described above, according to the present invention, in a drill whose surface is coated with a hard coating layer for drilling a hole in a workpiece material such as a difficult-to-cut material, the periodic rule is applied to the surface of the cemented carbide base material. Table 4at5
The surface is coated with one or more hard coating layers using a group a, 6a metal, or a carbide, nitride, or oxide of S^, AI, or a solid solution thereof. This improves wear resistance even on difficult-to-cut materials, prevents breakage of the drill, prevents welding of cutting debris such as chips, and improves its life. .

As for the thickness of the hard coating layer that coats the surface of the substrate, the thickness of the tip part that participates in direct cutting, such as the cutting blade or Giselle edge, is made thicker than that of the side part, thereby improving the wear resistance of the cutting part. It selectively improves the durability of the material such as hardness and welding resistance, and improves the toughness of the side surface, which does not relatively affect cutting, but where torque is applied and reduces friction with the workpiece material. This has the excellent effect of improving both the wear resistance and toughness of the entire drill.

Applicant: Sumitomo Electric Industries, Ltd. 1-1.

Hobby-9-7

Claims (1)

[Claims] 4a and 5 of the periodic table on the surface of the cemented carbide base of the drill body.
a, group 6a metals or Si, Al carbides, nitrides,
A surface-coated drill in which at least one hard coating layer of either an oxide or a solid solution thereof is formed, characterized in that the thickness of the hard coating layer at the tip of the drill is thicker than that at the side surface of the drill. surface coating drill.