JPS5943249B2 - Surface coated cemented carbide spade drill blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a surface-coated carbide drill blade that significantly extends the service life by coating at least the margin portion of a cemented carbide spade drill blade with a hard coating layer having excellent wear resistance. This invention relates to alloy spade drill blades.

Conventionally, a spade drill is generally used as a cutting tool when forming large-diameter, deep holes mainly in metal materials such as steel and iron castings.

As shown in the front view in FIG. 1 and in the side view in FIG. It has become.

Further, the details of the trill blade 2 are shown in a front view in FIG. 3 and in a side view in FIG. A cutting edge 6 is provided on each of the following edges at symmetrical positions on one side, and a cutting edge face 6a and a cutting edge flank face 6b are formed between the cutting edge 6 and the ridge line, and both side surfaces It has a structure in which the margin portion 1 has a predetermined margin width, and is manufactured by a normal powder metallurgy method.

Due to the cutting form of such a drill blade, the cutting speed is theoretically zero at the center of the drill, and increases toward the outer periphery.

Therefore, near the center where the cutting speed is slow, welding of the rigid material is likely to occur, causing chipping.

Apart from this, cutting resistance is large near the center, especially at the chisel edge, and this also makes it more likely to cause chipping.

Therefore, in order to prevent this kind of chipping of the chisel edge of a spade drill blade, it is necessary to select a material with low wear resistance but high toughness, that is, tungsten carbide-based cemented carbide, as the spade drill blade material. The reality is that there is not.

However, although spade drill blades constructed from such tungsten carbide-based cemented carbide can reduce the shortened life due to chipping, they suffer from wear due to the burnishing effect with the rigid material in the peripheral margin where the cutting speed is high. The wear of this margin portion deteriorates machining dimensional accuracy and increases cutting resistance, inevitably shortening the service life.

From the above-mentioned viewpoint, this invention makes it possible to extend the service life by covering the margin part with a hard coating layer with excellent wear resistance and suppressing the wear of the margin part during use. The present invention provides a spade drill blade made of a surface-coated tungsten carbide-based cemented carbide, in which at least the margin portion is made of a highly wear-resistant hard material, preferably a carbide of a metal from groups 4a, 5a, and 6a of the periodic table. , nitride, carbonitride, carbonate, carbonate nitride, aluminum oxide, and a single layer or a multilayer of two or more types selected from the group consisting of solid solutions of two or more of these types. A surface-coated tungsten carbide-based cemented carbide spade drill blade that improves wear resistance at least in the drill margin by coating with a coating layer of 0.5 to 20 μm, thereby significantly extending its service life. It has the following characteristics.

In the drill blade of the present invention, the service life can be significantly extended simply by providing the hard coating layer on the margin portion, but the hard coating layer is also applied to the chisel edge portion and thinning portion in addition to the margin portion. By providing this, it is possible to prevent the welding phenomenon of the work material in this part, and further improve the performance.

It goes without saying that the performance can also be improved by providing the hard coating layer on parts other than these.

In addition, in the drill blade of this invention, the layer thickness of the coating layer is limited to 0.5 to 20 μm because the layer thickness is 0.5 μm to 20 μm.
If the layer thickness is less than 5 μm, the desired effect of improving wear resistance and adhesion resistance cannot be secured, and on the other hand, if the layer thickness exceeds 20 μm, the wear resistance and adhesion resistance will not improve much, and conversely, the drill This is because the toughness of the blade decreases.

Further, the coating layer in the drill blade of the present invention can be formed by a common surface coating treatment method such as a chemical vapor deposition method, an ion blasting method, or a sputtering method.

Next, the drill blade of the present invention will be explained using examples and comparing with comparative examples.

Example 1 First, a spade drill blade (hereinafter referred to as a comparative drill blade) made of cemented carbide of ISO usage classification P30 and having the shape shown in FIGS. 3 and 4 was prepared.

On the other hand, T
iCl4: 3% by volume, N2: 37% by volume, N2:
3 while introducing a mixed gas having a composition of 60% by volume.
A drill blade of the present invention was manufactured by performing a coating treatment for a period of time to form a TiN layer with a layer thickness of 5.0 μm.

Next, regarding the drill blade of the present invention obtained by this coating treatment and the comparative drill blade described above, workpiece material: 558C (HB 250), cutting speed: 60 m/m, feed: 0.10 mrn/rev, , machined hole A cutting test was conducted under the following conditions: diameter: 45 mm, drilled hole depth: 50 mm, cutting fluid: JI83 class No. 3, and the number of holes drilled until the end of its life was measured. The drill blade of the present invention drilled 150 holes. While the drill blade reached the end of its life due to an increase in post-cutting resistance, the comparative drill blade reached the end of its life due to dimensional defects and an increase in cutting resistance after drilling 30 holes.

Next, the cutting edge of the drill blade of the present invention was regrinded from the state shown by the broken line to the state shown by the solid line in FIG. 5 with a regrinding allowance f.

As a result, the tungsten carbide-based cemented carbide was exposed in the cutting edge, chisel edge, and thinning part, and only the margin part was covered with a TiN layer.

When this reground drill blade was subjected to a cutting test under the above conditions, it reached the end of its life after drilling 130 holes due to an increase in cutting force.This result also shows that if there was a hard coating layer on the margin, the cutting time would be significantly longer. It is clear that a long life can be ensured.

Example 2 The same comparative drill blade used in Example 1 was placed in a vacuum container, and the temperature of the comparative drill blade was set to 400°.
While heating and holding at C, and introducing a mixed gas of Ar and N2, the atmospheric pressure was set to 2X-3 torr, and a voltage of 3 to ■ was applied to the target Ti plate so that it was negative relative to the wall of the vacuum chamber. The entire surface of the comparative drill blade was coated with sputtering using a sputtering method under the conditions of applying an amount of water and holding it for 2 hours.
The drill blade of the present invention was manufactured by forming a TiN layer with a layer thickness of 2 μm.

Next, regarding the drill blade of the present invention obtained by this coating treatment and the same comparative drill blade as in Example 1, the following will be explained: Rigid material: 545C (HB 200), Cutting speed: 50 m/mm, Feed: 0.15 gm / rev, , Machining hole diameter: 4
A cutting test was conducted under the following conditions: 5iiφ, drilled hole depth near 0 mm, cutting fluid: JI83 class No. 3, and the number of holes drilled until the end of its life was measured. Although it reached the end of its life due to wear, there was almost no welding of workpiece material to the thinning part, and there was no breakage.

On the other hand, most of the comparison drill blades reach the end of their life after drilling 50 holes due to wear in the margin area, and the remaining ones have a shorter lifespan due to breakage due to welding of the workpiece material to the thinning area. It was a lifespan.

As mentioned above, the spade drill blade of this invention is
At least the margin part is covered with a hard coating layer, so it has excellent abrasion resistance and welding resistance. It has extremely useful properties such as eliminating wear and preventing welding of the rigid material, ensuring an extremely long life.

[Brief explanation of drawings]

Figure 1 is a front view of the spade drill blade held in the holder, Figure 2 is its side view, Figure 3 is a front view showing details of the spade drill blade, Figure 4 is its side view, and Figure 5 is the front view of the spade drill blade held in the holder. The figure is a side view of a resharpened spade drill blade. In the drawings, 1... holder, 2...
Spade drill blade, 3... Bolt, 4.
...Chisel edge part, 5 ... Thinning part, 6 ... Cutting edge, 6a ... Cutting blade rake face, 6b ... Cutting blade flank surface ,?・・・・・・Margin section.

Claims (1)

[Claims] 1. At least the margin portion of the tungsten carbide-based cemented carbide speed drill blade is made of 4a and 5a of the periodic table.
, and carbides, nitrides, carbonitrides, carbonates, and carbonitrides of group 6a metals, and aluminum oxide,
Furthermore, a layer thickness of 0.5 consisting of a single layer or a multilayer of two or more types selected from the group consisting of two or more of these solid solutions.
A surface-coated cemented carbide spade drill blade characterized by being coated with a coating layer of ~20 μm. 2. A patented coated cemented carbide spade drill blade, characterized in that the margin part, chisel edge part, and thinning part of the tungsten carbide-based cemented carbide speed drill blade are coated with the above-mentioned coating layer.