JP2530259B2 - Diamond coated cutting tools - Google Patents

Description

Detailed Description of the Invention

[0001]

[Industrial application] Bits, end mills, cutters,
Cutting tools such as drills.

[0002]

2. Description of the Related Art Conventionally, it has been shown that a silicon nitride base material or a base material having a specific coefficient of thermal expansion is used as a means for obtaining a diamond-coated member having excellent adhesion. (Japanese Patent Publication No. 60-59086, Japanese Patent Publication No. 60-122785, 61-109628,
61-252004, 61-291493, 62-107067, 63-20478, 63-2047
9, 63-33570, 63-306805)

[0003]

However, in any of these diamond-coated members, the adhesion between the diamond film and the base material is still insufficient, and when used as a cutting tool, when the work is actually cut, diamond is used. There is a drawback that the film is easily peeled off.

[0004]

The present inventors have [Problems means and operations In order to achieve the above was subjected to a study in order to prevent peeling of the diamond such film peeling during cutting is caused mainly in the flank face, group
The plane formed by the flank surface of the material and the plane formed by the rake surface of the base material
Adjacent to the virtual cutting edge where the
A diamond film-coated cutting tool with excellent releasability can be obtained by coating a diamond film on a base material on which a stepped step is formed to prevent peeling on the flank surface. We have found this and completed the present invention.

In the cutting tool of the present invention, the peeling of the film is less likely to occur because the stepped portion of the base material instead receives the force that the film-base material interface of the flank face receives from the work during cutting. . Optimum shape of the step portion can not be said sweepingly because it varies depending on the cutting tool shape, for example, in the case of byte or similar thereto shape, formed stepped from the plane formed of the rake face
The distance to the surface (a in Fig. 1 and 2) is 0.1 to 1.5 mm, preferably 0.2 to 1.0 mm, the step (b in Fig. 1 and 2) 5 [mu] m or more, preferably when the stepped portion of 10~100μm Most effective. Distance from a plane formed of the rake face to the plane formed of the step difference is 0.
If it is shorter than 1 mm, the stepped portion may come into contact with the work before the dimensional accuracy of cutting decreases to the limit of use due to the progress of flank wear, and the dimensional accuracy may decrease. 1.5mm The distance from a plane formed of the rake face to the plane formed of the step difference
When the length is longer, the peeling resistance improving effect may not be sufficiently exhibited. Stage difference is processed 5μm smaller substrates is difficult, not less effective it can be expected because if there is not sufficient area supporting force received from the work even can be processed. Although larger side of the restriction is no stage difference, rather than greatly going improvement in peel resistance even to 100 [mu] m, there is a case where the step portion hits the workpiece during cutting.

As a method for coating the diamond film, a so-called CVD method can be used in which a mixed gas of a carbon source gas and a hydrogen gas is excited and brought into contact with a substrate. For example, methane, carbon monoxide or the like may be used as a carbon source gas, and a microwave plasma CVD method, a DC plasma CVD method, an RF plasma CVD method, or the like may be used as a gas excitation method. it can.

The synthesized diamond-like film enhances the characteristics of the cutting tool such as abrasion resistance, and is preferably coated on the substrate in a thickness of, for example, 0.5 to 100 μm , preferably 5 to 20 μm. If the film thickness is less than 0.5 μm, the effects such as abrasion resistance due to the coating cannot be sufficiently obtained, and if it exceeds 100 μm, the corresponding effect cannot be obtained and it is also disadvantageous in terms of cost.

The step portion effectively acts by being formed at least in a portion adjacent to the virtual cutting edge where peeling is likely to occur during cutting, and retreat from the plane formed by the main flank surface where peeling is likely to occur.
It may be formed by. Further, the diamond film may cover at least a region necessary for cutting, including a step .

The base material is not particularly limited, and Si ₃ N ₄ ,
What is generally used as a coated cutting tool of this kind, such as Sialon, can be used. In the present invention, when simply referred to as diamonds, it includes diamond and diamond-like carbon partially containing diamond-like carbon in addition to diamond.

[0010]

EXAMPLE 70% by weight of Si ₃ N ₄ powder, 10% by weight of Y ₂ O ₃ powder, 5% by weight of Al ₂ O ₃ powder and 15% by weight of TiN powder were wet-mixed, dried and molded. Then, it was fired at 1700 ° C. for 1 hour in a nitrogen atmosphere by an atmospheric pressure sintering method. The obtained sintered body was crystallized at a temperature of 1550 ° C in a nitrogen atmosphere to prepare a base material for a cutting tool. This base material is SPGN421
On the flank of the shaped tip, with the dimensions shown in Table 1,
The stepped part where the flat surface formed by the flank as shown in 2 recedes
(Step) 1 is provided (in FIG. 2, A:
12.7, B: 12.7, C: 3.18 mm).

Each of these chips was placed in a reaction vessel of a microwave plasma CVD apparatus as a base material. Then, under the conditions of a substrate temperature of 1000 ° C. and a pressure of 50 torr, the flow rate of the raw material gas into the reaction chamber was set to 15 sccm of carbon monoxide gas and 85 sccm of hydrogen gas, the microwave output was set to 300 W, and the reaction was carried out for 5 hours. Alternatively, the raw material gas flow rate into the reaction chamber is set to 0.5 scc of methane gas under the conditions of substrate temperature 900 ° C and pressure 50 torr.
m, hydrogen gas set to 99.5sccm, microwave output 500W
And the reaction was carried out for 12 hours to obtain a deposit having a thickness of 10 μm on the substrate.

Raman spectroscopic analysis was carried out on these deposits, and all were found to have Raman scattering spectra of 1333.
A peak due to diamond was found near cm ^-1 and it was confirmed that the diamond has almost no impurities.

Table 1 shows the results of a cutting test conducted on the obtained diamond-coated chips under the following conditions.

[0014]

[Table 1] Work material: Al-12 wt% Si alloy Cutting speed: 600 m / min Feed: f = 0.1 mm / rev Cutting depth: 0.25 mm

[0015] When using the no stepped portion base (sample 14)
Compared with, the cutting performance is improved in all cases when the base material provided with the stepped part in which the plane formed by the flank is set back is used.In particular, the distance from the face made by the rake face to the face made by the step is 0.2 to 1.5.
mm, stage step 5μm or more flank side formed plane retreats
When a base material provided with parts is used (Samples 3 to 6 and 9 to 1)
In 3), the cutting performance was remarkably improved.

The improvement in cutting performance when the distance from the plane formed of the rake face to the plane formed of the step difference is less (Sample 1) was small. This is because a plane formed of the step difference is too close to the rake face,
It is considered that the stepped portion comes into contact with the work before the dimensional accuracy of cutting decreases due to the progress of flank wear, and the dimensional accuracy decreases. If the distance from the plane formed <br/> the rake face in the opposite to the plane formed of the step difference is longer (sample 7,8)
The cutting distance was measured using a base material without steps (Sample 1
It was almost the same as 4). This is because the distance to the stage is too long, membrane than supporting force received from the workpiece by the forming surface of the step difference - so supported at the substrate interface, since the effect of providing a step portion is not obtained very much and Conceivable.

[0017]

As described above, according to the present invention, it is possible to easily obtain a diamond-coated cutting tool having a long life, and to obtain industrially advantageous effects such as significantly reduced wear during practical use.

[Brief description of drawings]

FIG. 1 is an enlarged view of a main part of FIG.

FIG. 2 is a perspective view showing a base material of a diamond-coated chip as an example of the present invention.

First step portion [Description of symbols] (stage) Distance b stage difference from plane formed a rake face to the plane formed of the step (Distance forming plane of the flank is retracted)

Claims (6)

(57) [Claims] 1. A substrate and a diamond coating the substrate
And a flat surface formed by the flanks of the base material and a rake surface of the base material.
Adjacent to the virtual cutting edge where the plane to be formed intersects, the base material
The flat surface formed by the flank of the
The diamond-like film includes the base material including the step.
A diamond-coated cutting tool characterized by being coated. 2. The step of the step from the plane formed by the rake face
The diamond-coated cutting tool according to claim 1, wherein the distance a to the plane formed is 0.1 to 1.5 mm, and the step b is a base material having the step portion of 5 μm or more. 3. The level difference of the step from the plane formed by the rake face.
Nasu distance a to the plane is 0.2 to 1.0 mm, diamond compound coated cutting tool according to claim 2, wherein said step b is a substrate having a step portion of 10 to 100 [mu] m. 4. The diamond-coated cutting tool according to claim 1, wherein the diamond film thickness is 0.5 to 100 μm. 5. The diamond-coated cutting tool according to claim 4, wherein the diamond film thickness is 5 to 20 μm. 6. The diamond-coated cutting tool according to claim 1, wherein the cutting tool is a cutting tool.