DE-102021203039-B4 - COATED CUTTING TOOL

Abstract

Coated cutting tool (4) comprising a carbide (1) and a coating layer (3) formed on the carbide (1), wherein the coated cutting tool (4) is arranged such that the coated cutting tool (4) has a rake face, a clearance face and a cutting edge line part which is located between the rake face and the clearance face, the coating layer (3) has a composite layer (2) which contains a compound with a composition represented by the following formula 1: (Al x Ti 1-x )N Formula 1, In formula 1, x represents the atomic ratio of elemental Al relative to the total of elemental Al and elemental Ti and satisfies 0.70 ≤ x ≤ 0.90. if the average thickness of the coating layer (3) in the cutting edge line part is expressed as T1 and the average thickness of the coating layer (3) in the rake face at a position 2 mm or more away from the cutting edge line part in the direction of the rake face is expressed as T2 , T1 is 4.0 µm or more and 10.0 µm or less, T2 is 2.0 µm or more and 7.0 µm or less, and T2 < T1 is satisfied, and if the residual stress of the carbide (1) in the cutting edge line part is expressed as S 1 and the residual stress of the carbide (1) in the rake face at a distance of 2 mm or more from the cutting edge line part in the direction The position furthest from the rake surface is expressed as S 2 , and S 2 < S 1 is satisfied.

Inventors

• TSUKASA SHIROCHI
• Naoyuki Fukushima

Assignees

• TUNGALOY CORPORATION

Dates

Publication Date

20260513

Application Date

20210326

Priority Date

20200331

Claims (6)

1. Coated cutting tool (4) comprising a hard metal (1) and a coating layer (3) formed on the hard metal (1), wherein the coated cutting tool (4) is configured such that the coated cutting tool (4) has a rake face, a clearance face and a cutting edge line part which is located between the rake face and the clearance face, the coating layer (3) has a composite layer (2) which contains a compound with a composition represented by the following formula 1: (Al x Ti 1-x )N Formula 1, In formula 1, x represents the atomic ratio of elemental Al relative to the total of elemental Al and elemental Ti and satisfies 0.70 ≤ x ≤ 0.90 if the average thickness of the coating layer (3) in the cutting edge line part is expressed as T1 and the average thickness of the coating layer (3) in the rake face at a position 2 mm or more away from the cutting edge line part in the direction of the rake face is expressed as T2 , T1 is 4.0 µm or more and 10.0 µm or less, T2 is 2.0 µm or more and 7.0 µm or less, and T2 < T1 is satisfied, and if the residual stress of the cemented carbide (1) in the cutting edge line part is expressed as S1 and the residual stress of the cemented carbide (1) in the rake face at a position 2 mm or more away from the The cutting edge line part in the direction of the rake face is expressed as S 2 , where S 2 < S 1 is satisfied.
2. Coated cutting tool (4) according to Claim 1 , where the residual stress S 1 is -0.5 GPa or more and 0.0 GPa or less, and the residual stress S 2 is -2.0 GPa or more and -0.3 GPa or less.
3. Coated cutting tool (4) according to Claim 1 or 2 , where the difference T 1 - T 2 between the average thickness T 1 and the average thickness T 2 is 1.0 µm or more and 4.0 µm or less.
4. Coated cutting tool (4) according to one of the Claims 1 until 3 , wherein in the hard metal (1) the proportion of measurement points where tungsten carbide (WC) has a KAM value of 1° or less is 90% or more and 98% or less.
5. Coated cutting tool (4) according to one of the Claims 1 until 4 , wherein the hard metal (1) is based on a WC phase, contains Co in a proportion of 5.0 wt% or more and 15.0 wt% or less, and contains Cr in a proportion of 0.3 wt% or more and 1.0 wt% or less than Cr 3 C 2 .
6. Coated cutting tool (4) according to one of the Claims 1 until 5 , wherein the coating layer (3) has a lower layer between the hard metal (1) and the composite layer (2) which contains a Ti compound comprising elemental Ti and at least one element selected from the group consisting of C, N, O and B.

Description

Technical field The present invention relates to a coated cutting tool. Technical background It is conventionally known that a coated cutting tool, which has a coating layer deposited on the surface of a hard metal substrate by a chemical vapor deposition process with a total thickness of 3 to 20 µm, is used for cutting steel, cast iron, or the like. The coating layer described above, for example, is one consisting of a single layer or two or more layers selected from the group consisting of titanium carbides, nitrides, carbonitrides, oxycarbides, oxycarbonitrides, and aluminum oxide ( Al₂O₃ ). Furthermore, a coated tool with a Ti-Al-based nitride layer deposited on the surface of a substrate made of cemented carbide or cubic boron nitride by a physical vapor deposition process is known, and such tools are known to exhibit excellent wear resistance. Although the conventional coated tool described above, which has a Ti-Al-based nitride layer formed by a physical vapor deposition process, exhibits relatively excellent wear resistance, cracking is likely to occur when such a tool is used under cutting conditions involving high-speed machining and intermittent loading. Therefore, various proposals for improving the coating layer have been submitted. For example, PTL 1 describes a surface-coated cutting tool with a hard coating layer, comprising at least two layers, an upper layer (α) and a lower layer (β), which are formed on the surface of a tool base formed from a WC-based carbide, a TiCN-based cermet or an ultra-high pressure sintered body based on cBN. The surface-coated cutting tool is characterized in that (a) the upper layer (α) is formed from an Al₂O₃ layer with an α-type crystal structure, (b) the lower layer (β) is formed from a Ti-Al composite nitride layer or composite carbonitride layer, (c) the Ti-Al composite nitride layer or composite carbonitride layer has at least one crystal layer with a face-centered cubic structure of the NaCl type, (d) if the thickness of the upper layer (α) in the cutting edge line is expressed as Tα₁ and the thickness at a point 500 µm from the cutting edge line in the direction of the rake face is expressed as Tα₂ , Tα₁ and Tα₂ satisfy values of 0.0 to 5.0 µm and 1.0 to 20.0 µm respectively, and furthermore Tα₁ < Tα 2 are satisfied and (e) if the thickness of the lower layer (β) in the cutting edge line is expressed as Tβ 1 and the thickness at a point 500 µm away from the cutting edge line in the direction of the rake face is expressed as Tβ 2 , Tβ 1 and Tβ 2 each satisfy 1.0 to 20.0 µm and also satisfy Tβ 2 < Tβ 1 . JP 2019-010707 A Disclosure is made of a surface-coated cutting tool comprising a hard coating consisting of a nitride or carbonitride composite layer of Ti and Al with a face-centered cubic NaCl structure and an average layer thickness of 1.0–20.0 µm. The crystal orientation within the crystal grains is analyzed, the mean orientation difference between two adjacent measurement points in the same crystal grain is calculated, and a KAM value is determined at each measurement point. Layers in which the proportion of measurement points with a KAM value of less than 1 degree is at least 50%, and layers in which this proportion is 50% lower, are laminated. If the layer is represented by the composition (TiAl)(CN), the following conditions apply to the layer: 0.60 ≤ x ≤ 0.95 and 0 ≤ y ≤ 0.005. JP 2004-122263 A Disclosing a coated cutting tool for cutting a high-precision component, which is shaped such that the cutting edge is a sharp edge, the surface roughness of the cutting edge in a center line is mean roughness 0.4 µm or less, the thickness of the coating layer on the cutting surface is 0.5-2 µm and the thickness of the coating layer on the flank is 4-7 µm. US 2018/0347027 A1 It reveals coatings that utilize composite architectures offering high aluminum content and high hardness for various cutting applications. For example, a coated cutting tool comprises a substrate and a coating consisting of a material formed by physical processes. a refractory layer applied by vapor deposition and adhering to the substrate, wherein the refractory layer consists of a plurality of sublayer groups, wherein a sublayer group consists of a titanium aluminum nitride sublayer and an adjacent composite sublayer consisting of alternating nanolayers of titanium silicon nitride and titanium aluminum nitride. List of objections Patent literature Patent document 1: JP-A-2019-155570 Brief description of the invention Technical problem In recent cutting processes, higher speed, higher feed rates, and deeper cuts have become increasingly important, and tools must exhibit better wear resistance and fracture toughness than before. Furthermore, due to the increasing complexity of machining operations compared to the past, intermittent tool loading is becoming more prevalent. Under such harsh cutting conditions, conventional tools can fracture due to thermal cracking. A coating layer form