JP2970016B2 - Hard layer coated cemented carbide cutting tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention shows excellent cutting performance when used in intermittent cutting such as milling, and also when used in continuous cutting, particularly when used in medium to low speed continuous cutting. The present invention relates to a hard layer coated cemented carbide cutting tool that exhibits excellent cutting performance in such cases.

[0002]

2. Description of the Related Art Generally, one or more of iron group metals are contained as a binder phase forming component, and if necessary, carbides and nitrides of metals of groups 4a, 5a and 6a of the periodic table are used. , A cemented carbide substrate (hereinafter referred to as a cemented carbide substrate) containing 0.5 to 30% by weight of carbonitride and the balance of tungsten carbide (hereinafter referred to as WC) and unavoidable impurities. A cutting tool made of a hard layer-coated cemented carbide obtained by coating a layer by a physical vapor deposition method is known (see JP-A-52-10871).

[0003]

However, since the crystal grain size of the TiCN layer formed by the conventional physical vapor deposition method obtained by the above method is coarse, the toughness of the TiCN layer is insufficient, and the conventional physical A hard layer coated cemented carbide cutting tool having a TiCN layer formed by a vapor deposition method, when used for intermittent cutting such as milling, the TiCN hard layer peels off, and defects are generated from that part, which is satisfactory. There was a problem that a long service life could not be obtained.

[0004]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of studying to solve the above-mentioned problems and to obtain a hard layer coated cemented carbide cutting tool that has a longer life even when used for interrupted cutting such as milling, as a result, titanium carbonitride the composition of one hard layer Ti (C _x N _y) [here, x
+ Y = 1], _{x in} Ti (C _x N _y ) is changed so as to continuously increase from the innermost surface to the outermost surface in contact with the cemented carbide substrate, and y is continuously reduced. (C _x N _y ) obtained by changing
Since the layer has fine grains, it has been found that a hard layer coated cemented carbide cutting tool obtained by coating the surface of a cemented carbide substrate with this Ti (C _x N _y ) layer has excellent exfoliation resistance. is there.

[0005] The present invention has been made based on this finding, and Ti (C _x
N _y ) [where x + y = 1] is a cutting tool coated with a single hard layer of titanium carbonitride having the composition represented by the formula: wherein the single hard layer of titanium carbonitride Ti (C _x N _y ) , X takes the minimum value at the innermost surface in contact with the cemented carbide substrate, and changes so as to increase in the layer thickness direction from the innermost surface to the outermost surface, and takes the maximum value at the outermost surface, while y is ,
Hard layer coated cemented carbide cutting tool that takes the maximum value on the innermost surface in contact with the cemented carbide substrate, and changes so that it decreases in the layer thickness direction from the innermost surface to the outermost surface and takes the minimum value on the outermost surface , Are characterized by:

In order to form a single hard layer of titanium carbonitride in the hard layer-coated hard metal cutting tool of the present invention, a physical vapor deposition device such as an ion plating device is used. The reaction gas introduced into the physical vapor deposition apparatus is a mixed gas of a nitrogen gas and a hydrocarbon gas. As shown in the graph of FIG. Is continuously reduced, and the hydrocarbon gas is supplied so as to be continuously increased in inverse proportion thereto. Although the nitrogen gas introduction amount and the hydrocarbon gas introduction amount may be changed intermittently, it is preferable to change them continuously. In the graph of FIG. 1, the nitrogen gas introduction amount and the hydrocarbon gas introduction amount are linearly changed. Although it is changed continuously, it is not limited to this, and may be changed continuously in a curved line.

When the titanium carbonitride single hard layer thus obtained is represented by Ti (C _x N _y ) (where x + y = 1), the values of x and y are determined by reacting nitrogen gas and carbonized gas as reaction gases. From the relation of introducing a mixed gas of hydrogen gas, 0.05 ≦ x ≦ 0.95 and 0.05 ≦ y ≦ 0.95, respectively.
And the innermost surface in contact with the cemented carbide substrate
Since iN is contained as the maximum component, the adhesion to the cemented carbide substrate is excellent, while on the other hand, the hardest TiC on the outermost surface, which is directly affected at the time of cutting, is the maximum component, so that it has excellent wear resistance and a single hard layer. However, since it has excellent characteristics having both adhesion and wear resistance, it is particularly effective for intermittent cutting such as milling. Further, the hard layer coated cemented carbide cutting tool of the present invention having the above-mentioned titanium carbonitride single hard layer has a medium to low speed (cutting speed: less than 200 m / min) continuous cutting which is generally considered to have severe flank wear. It is also effective.

[0008] The thickness of this titanium carbonitride single hard layer is 2
It is preferably 0 μm or less. If it exceeds 20 μm, the difference in thermal expansion between the substrate and the substrate at the time of cutting becomes large, and cracks are generated, which makes it easy to peel off. On the other hand, when the single hard layer is 0.1.
When the thickness is less than 5 μm, the effect of suppressing the wear of the hard layer is not sufficient, so that the thickness is preferably 0.5 μm or more.

[0009]

Next, a hard layer coated cemented carbide cutting tool according to the present invention will be described in detail with reference to examples.

As raw material powders, each has an average particle diameter of 3 μm.
m Co powder, TiC powder, TaC powder, and WC powder were prepared, and these powders were prepared such that Co powder: 9% by weight, TiC powder: 1% by weight, TaC powder: 2% by weight, and remaining: WC powder. After blending and mixing, it is molded into a green compact,
The green compact was sintered under normal conditions to produce a sintered body, and the sintered body was ground to produce a WC-based cemented carbide chip having a shape of ISO standard TNGA160408.

Next, this WC-based cemented carbide chip is mounted above a normal ion plating apparatus, while Ti metal is placed in a crucible installed below the above ion plating apparatus. Filled. In this state, the inside of the ion plating apparatus was maintained at a vacuum of 1 × 10 ⁻⁵ Torr, and the temperature was increased to 700 ° C. at a rate of 6 ° C./min. Subsequently, while maintaining this temperature, 5 × 10 ^-2
Bombard cleaning is performed while maintaining the atmosphere in an Ar gas atmosphere of Torr. Then, while heating and evaporating the Ti metal by energization or the like, nitrogen gas: 99.95% by volume
Acetylene gas: introduced so as to be a mixed gas of 0.05%, and the pressure in the ion plating apparatus was set to 1.0 × 1.
0 was maintained at ^-4 Torr, the nitrogen gas, at the same time the acetylene gas is supplied so as to reduce gradually, continuously changed in inverse proportion to the amount of the nitrogen gas and acetylene gas while supplying to increase gradually The hard layer-coated cemented carbide tips 1 to 8 of the present invention in which the surface of the WC-based cemented carbide tip is coated with a single hard layer of titanium carbonitride having a thickness shown in Table 1 Was manufactured.

The composition of the single hard layer of titanium carbonitride is defined by EP
When measured using MA, the carbon of the titanium carbonitride single hard layer takes the minimum value on the innermost surface in contact with the cemented carbide substrate and continuously increases in the layer thickness direction from the innermost surface to the outermost surface. So that the nitrogen has a maximum value on the outermost surface, while the nitrogen has a maximum value on the innermost surface in contact with the cemented carbide substrate and continuously decreases in the layer thickness direction from the innermost surface to the outermost surface. To have a concentration gradient showing a minimum value on the outermost surface.

The single hard layer of titanium carbonitride was subjected to X-ray diffraction, and the average crystal grain size was calculated by the Scherrer equation using the half width of the (200) plane. The results are shown in Table 1.

[Conventional Example] On the other hand, for the sake of comparison, after the bombard cleaning of the embodiment, a mixed gas of a fixed mixture ratio of nitrogen gas and acetylene gas mixed at a volume ratio of 1: 1 was flown to obtain the WC. Conventional hard layer coated cemented carbide chips 1 to 4 having a thickness shown in Table 1 and comprising a titanium carbonitride layer on the surface of the base cemented carbide chip were manufactured. This conventional hard layer coated cemented carbide tip 1 to 4 was also subjected to X-ray diffraction to obtain (2
The average crystal grain size was calculated by the Scherrer's formula using the half width of the (00) plane, and the results are shown in Table 1. The continuous cutting test and the intermittent cutting test were performed on the hard alloy chips 1 to 4 under the following conditions, and the cutting test results are shown in Table 1.

Continuous dry cutting test Work material: SNCM439 (Brinell hardness: 250), Cutting speed: 150 m / min, Feed: 0.3 mm / rev., Cutting depth: 1.5 mm. The time (minute) until the flank wear width of the cutting edge of the tip became 0.3 mm was measured.

Intermittent dry cutting test Work material: A cylinder made of SCM440 (Brinell hardness: 300) and having four grooves on the outer periphery in the axial direction, cutting speed: 100 m / min, feed: 0.21 mm / rev. The cutting was performed under the following conditions: cutting depth: 1.0 mm; cutting time: 2 min.

[0017]

[Table 1]

[0018]

From the results shown in Table 1, the crystal grain size of the coated hard layer of the hard layer coated cemented carbide tips 1 to 8 of the present invention is fine, and the cutting speed is less than 200 m / min. Excellent effect in dry cutting, and even in intermittent dry cutting, there is almost no occurrence of chipping,
Even though they are very slight, they exhibit excellent cutting performance over a long period of time. On the other hand, the conventional hard layer-coated cemented carbide tips 1-4 have a flank wear width of the cutting edge of the tip of 0.
It is clear that the cutting performance was inferior due to the short time required to reach 3 mm and the occurrence of many defects, and the short life of the insert.

As described above, the hard layer-coated cemented carbide cutting tool of the present invention has excellent wear resistance and chipping resistance, so that it can exhibit excellent cutting performance for a long period of time and is industrially excellent. The effect is brought about.

[Brief description of the drawings]

FIG. 1 is a graph schematically showing the amounts of nitrogen gas and hydrocarbon gas introduced.

Claims (1)

(57) [Claims] 1. Ti (C _x N _y ) is formed on the surface of a cemented carbide substrate.
A cutting tool coated with a single hard layer of titanium carbonitride having a composition represented by [x + y = 1], wherein x in the single hard layer of titanium carbonitride Ti (C _x N _y ) Takes the minimum value on the innermost surface in contact with the cemented carbide substrate, changes from the innermost surface toward the outermost surface in the layer thickness direction, and takes the maximum value on the outermost surface. A hard layer-coated cemented carbide, characterized in that it takes the maximum value at the innermost surface in contact with the substrate, changes from the innermost surface to the outermost surface in the layer thickness direction, and takes the minimum value at the outermost surface. Cutting tools.