JPH10280146A - Throw away type cutting chip made of surface-coated cermet in which hard coating layer has excellent chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a throw away type cutting tip made of surface coated cermet in which a hard coating layer has chipping resistance. SOLUTION: This throw away type cutting tip made of surface-coated cermet is composed by physically vapor-depositing and/or chemically vapor-depositing a hard coating layer having the average layer thickness of 1 to 20 μm on the surface of a substrate composed of carbonitride series cermet contg., as bonding phase forming components, by weight, 17.5 to 27% Co and/or Ni, and in which a surface hardened layer in which, to the inside hardness of 1200 to 1600 by Vickers hardness (and so forth), the cutting edge ridgeline part at which the flank and face of the cutting edge cross shows the maximum surface hardness of 2200 to 2600, and the flank and face shows the maximum surface hardness of 1400 to 1800 is present on the surface part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting edge ridge line in which a flank and a rake face of a hardened surface layer formed on the surface of a substrate made of a titanium carbonitride-based cermet (hereinafter referred to as a cermet substrate). The hardness at the portion (hereinafter simply referred to as the cutting edge ridge portion) is made relatively higher than the hardness at the flank and rake face, whereby physical vapor deposition (hereinafter, referred to as PVD) is performed on the substrate surface. And / or imparts excellent fracture resistance to a hard coating layer to be subjected to chemical vapor deposition (hereinafter, referred to as CVD), so that it can be cut even when used for high-speed interrupted cutting of steel or the like, which requires fracture resistance. A surface-coated cermet throw-away type cutting tip (hereinafter, referred to as "the cutting edge") that can exhibit long-lasting cutting performance without causing chipping or chipping (small chipping) of the blade.
Simply referred to as a coated cutting tip).

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No.
No. 80, etc., containing 5 to 14% by weight of Co and / or Ni as a binder phase forming component;
Vickers hardness (hereinafter referred to as Hv), Hv: 140
For the internal hardness of 0 to 1800, the flank of the cutting edge,
A hard coating layer was formed on the surface of a cermet substrate having a surface hardened layer having a uniform hardness distribution with a maximum surface hardness of Hv: 2100 to 2500 on the cutting edge ridge portion and the rake face. 2. Description of the Related Art Coated cutting tips formed by vapor deposition using a PVD method and / or a CVD method with an average layer thickness of ２０20 μm are known, and it is also known that they are used for continuous cutting and interrupted cutting of, for example, steel. Have been.
Further, the cermet substrate constituting the above-mentioned conventional coated cutting tip is subjected to the following conditions: (a) a temperature rising rate to a sintering temperature: 1 to 3 ° C./sec; (b) a temperature from room temperature to 1100 to 1300 ° C. Heating atmosphere:
A vacuum of 0.1 torr or less, (c) a sintering temperature of 1100 to 1300 ° C.
Atmosphere for raising temperature to 0 to 1560 ° C: Nitrogen atmosphere of 5 to 100 torr, (d) Holding time and atmosphere at the above sintering temperature: 60 to
(E) Cooling: Furnace cooling in a vacuum atmosphere of 0.1 torr or less, under a condition satisfying the above conditions (a) to (e), a powder compact having a predetermined composition. It is also known to be manufactured by sintering a body.

[0003]

On the other hand, in recent years, the performance of cutting devices has been remarkably improved, and there has been a strong demand for labor saving. Accordingly, the cutting process has tended to be accelerated. In the conventional coated cutting tip where the hardness distribution of the surface hardened layer formed in the part does not change, if this is used, for example, when performing intermittent cutting of steel at high speed, due to lack of fracture resistance of the hard coating layer, At present, chipping and chipping are apt to occur in the cutting blade, and the service life is reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the viewpoint as described above, paying attention to the conventional coated cutting tip in which a surface hardened layer is formed on the surface of the cermet substrate,
As a result of a study aimed at improving the fracture resistance of the hard coating layer constituting the same, the content of Co and / or Ni as binder phase forming components was reduced to 17.5 to 27% by weight when the cermet substrate was sintered. When sintering is performed under the conditions (a) to (e), which are the above sintering conditions, the cooling atmosphere of the condition (e) is a nitrogen atmosphere of 1 to 5 torr, The cermet substrate after sintering has an Hv: 120
In contrast to the internal hardness of 0 to 1600, the cutting edge ridge line on the surface shows the highest surface hardness of Hv: 2200 to 2600 which is almost the same as the surface hardened layer of the conventional cermet substrate, but the flank surface And the rake face has a relatively lower H
v: a surface-hardened layer having the highest surface hardness of 1400 to 1800 is formed, and the surface of the cermet substrate on which such a surface-hardened layer is formed is hardened by PVD and / or CVD. When the coating layer is deposited, the resulting hard coating layer has excellent fracture resistance, and the effect of improving the fracture resistance of the hard coating layer is the same as that of the surface hardened layer formed on the cermet substrate surface. In contrast to the hardness distribution, ie, the internal hardness indicating Hv: 1200 to 1600, the cutting edge ridge line shows the highest surface hardness of Hv: 2200 to 2600, while the flank and rake face are relatively more. Low Hv: It is thought to be due to the fact that the hardness distribution showing the highest surface hardness of 1400 to 1800 causes the residual compressive stress of the hard coating layer to be significantly reduced, and thus As a result, coated cutting inserts are required to have chipping resistance. For example, when used for high-speed interrupted cutting of steel, etc., chipped cutting performance does not occur and chipping (small chipping) does not occur. The research results show that they can be used over a long period of time.

The present invention has been made on the basis of the above research results, and contains 17.5 to 27% by weight of Co and / or Ni as a binder phase forming component, and has an Hv of 1: 1.
For the internal hardness of 200 to 1600, the cutting edge ridge line shows the highest surface hardness of Hv: 2200 to 2600, and the flank and rake face show the highest surface hardness of Hv: 1400 to 1800. A hard coating layer having an average layer thickness of 1 to 20 μm is deposited on the surface of a cermet substrate having a hardened layer on the surface by a PVD method and / or a CVD method. The characteristic feature is the coated cutting tip having the following characteristics.

[0006] The hardness distribution of the surface hardened layer formed on the surface of the cermet substrate constituting the coated cutting tip of the present invention is such that the content of Co and / or Ni as binder phase forming components is 17.5. After specifying the cooling atmosphere, the cooling atmosphere of the condition (e) of the conditions (a) to (e), which are the sintering conditions of the cermet substrate constituting the conventionally coated cutting tip, is set to 1 to 27% by weight as described above. It is adjusted by performing sintering under the condition of a nitrogen atmosphere of 5 torr, that is, the content of Co and / or Ni is reduced within the above range, and the pressure of the nitrogen atmosphere under the condition (e) is set within the above range. The higher the temperature, the higher the hardness of the ridge and the flank and rake face, and conversely, the higher the Co and / or Ni content within the above range, and the lower the pressure of the nitrogen atmosphere. When the content of the binder phase forming component exceeds 27% by weight and the nitrogen atmosphere is less than 1 torr, the maximum surface hardness of the cutting edge ridge portion is less than Hv: 2200. The maximum surface hardness of the flank face and the rake face is less than Hv: 1400, and if such a hardness distribution is obtained, the difference in hardness from the internal hardness becomes too small, and the hard coating deposited on the The desired excellent fracture resistance of the layer cannot be ensured, while the content of the binder phase forming component is 17.5.
When the nitrogen atmosphere exceeds 5 torr with the content being less than 5% by weight, the maximum surface hardness of the cutting edge ridge portion exceeds Hv: 2600, and the maximum surface hardness of the flank and rake face is Hv:
Since the hardness exceeds 1800, the hardness difference from the internal hardness becomes too large, and the hard coating layer does not have the desired effect of improving the fracture resistance even with such a hardness distribution. The hardness distribution of the hardened surface layer in the cermet substrate was determined as described above. Also, the average thickness of the hard coating layer was set to 1 to 20 μm,
If the thickness is less than 1 μm, the desired excellent abrasion resistance provided by the hard coating layer cannot be secured,
On the other hand, if the thickness exceeds 20 μm, the tendency to decrease the fracture resistance appears.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated cutting insert of the present invention will be specifically described with reference to examples. As raw material powder,
In any case, TiCN having a predetermined average particle size in the range of 0.5 to 2 μm [by weight (the same applies hereinafter), TiC / TiN
= 50/50] powder, TiN powder, TaC powder, NbC
Powder, WC powder, Mo ₂ C powder, VC powder, ZrC powder, Cr ₃ C ₂ powder, (Ti, W, Mo) CN [Ti /
W / Mo = 80/10/10, C / N = 70/30] powder, (Ti, Ta, V) CN [Ti / Ta / V = 70 /
20/10, C / N = 50/50] powder, (Ti, T
a, Nb) CN [Ti / Ta / Nb = 70/15/1
5, C / N = 60/40] powder, (Ti, W, Nb) C
N [Ti / W / Nb = 80/10/10, C / N = 70
/ 30] powder, (Ti, Nb, Mo) CN [Ti / Nb
/ Mo = 60/30/10, C / N = 60/40] powder, (Ti, W) CN [Ti / W = 80/20, C / N
= 70/30] powder, Co powder, and Ni powder were prepared, and these raw material powders were blended in the composition shown in Table 1, wet-mixed in a ball mill for 24 hours, dried, and dried.
A green compact is pressed at a pressure of ton / cm ² ,
Next, these green compacts were heated from the room temperature to 1300 ° C. in a vacuum atmosphere of 0.1 torr at a temperature rising rate of 1.5 ° C./min to increase the temperature to 1300 ° C.
After the temperature was raised to 150 ° C., the atmosphere was changed to a nitrogen atmosphere of 15 torr, the temperature was raised to 1500 ° C. at the same temperature rising rate, and the temperature was kept at 1500 ° C. for 60 minutes in the same atmosphere.
A cermet substrate A having a throw-away chip shape according to ISO standard SNMG120408 by sintering under a furnace cooling condition in a predetermined nitrogen atmosphere within a range of torr and subjecting the sintered body to a round honing of 0.05 mm. M were each manufactured. Further, for the purpose of comparison, green compacts A to A having the same composition as shown in Table 1 were used, and the sintering thereof was performed in the final step of the above sintering conditions in which the furnace cooling was 0%. Cermet substrates a to m were produced under the same conditions except that the cermet substrates were carried out in a vacuum atmosphere of 0.1 torr.

With respect to various cermet substrates obtained as a result, Hv (load: 300 g) of a flank and a rake face was measured at arbitrary 10 points, respectively, while the surface was polished, and the ridge of the cutting edge was accurately measured. Since the surface hardness cannot be measured, Hv (load: 300 g) at a position 0.05 mm inside from the honing surface in the polished cross section at 10 arbitrary points is measured and determined as the surface hardness, and the maximum surface hardness is selected from this. The results are shown in Tables 2 and 3 together with the internal hardness.

Next, as shown in Tables 2 and 3, (a) the cermet substrate was ultrasonically cleaned in acetone and dried on an arc ion plating apparatus, as shown in Tables 2 and 3. And pure Ti and Ti-50% by weight respectively as a cathode electrode (evaporation source)
Al alloy, Ti-45 wt% Al-5 wt% Mg alloy,
And a Ti-40% Al-10% Cr alloy, and while the inside of the apparatus is evacuated and kept at a vacuum of 1 × 10 ⁻⁵ torr, the inside of the apparatus is heated to 500 ° C. with a heater, and then argon gas is introduced. Then, an argon gas atmosphere of 1 × 10 ⁻³ torr was applied, and in this state, a bias voltage of −800 V was applied to the cermet substrate to bombard the surface of the cermet substrate, and then, in the apparatus, depending on the composition of the hard coating layer, ,
Nitrogen gas, methane gas, or a mixture of nitrogen gas and methane gas was introduced as a reaction gas to form a reaction atmosphere of 5 × 10 ⁻³ torr, and the bias voltage applied to the cermet substrate was reduced to −200 V. An arc discharge is generated between the electrode and the electrode to form a hard coating layer having a composition and an average layer thickness shown in Tables 5 and 6 on each surface of the cermet substrate.
Method D, (b) CVD method of forming a hard coating layer having a composition and an average layer thickness shown in Tables 5 and 6 under the conditions shown in Table 4 using a normal CVD apparatus. By forming the hard coating layer by the method (b), the coated cutting tips 1 to 13 of the present invention and the comparative coated cutting tips 1 to 1 are formed.
3 were each manufactured.

[0010] With respect to the various coated cutting tips obtained as a result, a work material: JIS SCM440C, a round bar with four longitudinal grooves at regular intervals in the longitudinal direction, a cutting speed: 350 m / min, a feed: 0.2 mm / rev A high-speed intermittent cutting test of the alloy steel was performed under the following conditions: cutting depth: 1 mm, cutting time: 5 minutes, and the flank wear width of the cutting edge was measured. Tables 5 and 6 show the results of these measurements.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016]

[Table 6]

[0017]

From the results shown in Tables 5 and 6, all of the coated cutting tips 1 to 13 of the present invention have a relatively high hardness cutting edge ridge in the surface hardened layer of the cermet substrate constituting the same. The flank face and rake face, which have relatively low hardness, make the hard coating layer excellent in fracture resistance, so that the cutting edge is not chipped or chipped even at high-speed interrupted cutting of steel. In contrast, the comparative coated cutting tips 1 to 13 in which the surface hardened layer of the cermet substrate has no change in hardness as in the case of the above-mentioned conventional coated cutting tips, all have the residual compression of the hard coating layer. It is clear that high-speed intermittent cutting of steel, which is subjected to high stress, which results in cutting under severe conditions, tends to cause chipping and chipping of the cutting edge, resulting in a relatively short service life. As described above, the coated cutting tip according to the present invention has the maximum surface hardness of Hv: 2200 to 2600 of the cutting edge ridge portion in the surface hardened layer of the cermet substrate constituting the chip and the Hv of the flank and rake face: 1400-1
The hardness distribution of the highest surface hardness of 800 makes the hard coating layer formed on it have excellent fracture resistance, so it can be cut not only in high-speed continuous cutting of steel but also in high-speed interrupted cutting. Without chipping or chipping of the blade,
It exhibits excellent cutting performance over a long period of time.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsuhisa Nonaka 1511 Furamaki, Ishishita-cho, Yuki-gun, Ibaraki Pref. Mitsubishi Materials Corporation Tsukuba Works

Claims (1)

[Claims] The present invention contains Co and / or Ni as a binder phase forming component in an amount of 17.5 to 27% by weight, and has a Vickers hardness of 1200 to 1600. A carbonitrided carbon steel in which a cutting edge ridge portion where a surface and a rake face intersect has a maximum surface hardness of 2200 to 2600, and a flank surface and a rake surface have a surface hardened layer having a maximum surface hardness of 1400 to 1800. Surface coating cermet having excellent fracture resistance, wherein a hard coating layer having an average layer thickness of 1 to 20 μm is formed by physical vapor deposition and / or chemical vapor deposition on a surface of a substrate composed of a titanium-based cermet. Slowway-type cutting insert made of steel.