KR20110078462A - Method for manufacturing cutting tool and cutting tool manufactured by the method - Google Patents

Abstract

PURPOSE: A cutting tool and a method of manufacturing the cutting tool are provided to reduce residual stress of a cutting too and improve surface roughness since in a state coated layers are formed, blasting and brushing are successively performed. CONSTITUTION: A method of manufacturing a cutting tool comprises next steps. A base(100) is prepared, which is formed from one of cemented carbide, cermet and ceramic. On the base is formed an underlying layer(110) comprising a layer formed from one of IV, V and VI groups of metallic elements and carbide, nitride, carbo-nitride and carbonic-acid nitride of the metallic elements. On the underlying layer is formed a first coated layer(120) comprising a layer formed from one of Al, Zr and Hf oxides. On the first coated layer is formed a second coated layer comprising a layer formed from one of IV, V and VI groups of metallic elements and carbide, nitride, carbo-nitride and carbonic-acid nitride of the metallic elements.

Description

Method for manufacturing a cutting tool and a cutting tool manufactured by the above-described method TECHNICAL FIELD AND CUTTING TOOL MANUFACTURED BY THE METHOD

The present invention relates to a method for manufacturing a cutting tool and a cutting tool manufactured by the method, which is manufactured through a multi-layer coating, blasting and brushing process to improve toughness, wear resistance, welding resistance and chipping resistance, and A method for manufacturing a cutting tool.

Cutting tools used for cutting, etc. are generally hard with a Ti-based compound or Al ₂ O ₃ or the like on the surface of the substrate made of cemented carbide (hard metal), cermet, ceramic (ceramic), etc. Thin film coating improves wear resistance and toughness.

One of the long-standing wishes of such coated cutting tools is to minimize or convert to tensile residual stresses caused by the difference in coefficient of thermal expansion between the substrate and each coating layer during the coating process where heating and cooling are repeated. This is because the tensile residual stress accelerates tool damage such as wear, chipping, and defects when working with the cutting tool, thereby shortening the life of the tool.

Many studies have been conducted to solve the above problems, but the study to reduce the residual stress by controlling the coating process was insignificant. For example, in US Pat. Nos. 6,84496, US Pat. No. 6,3,0310, etc., to reduce the residual stress by reducing the residual stress by surface treatment on the thin film itself after coating in order to solve the residual stress generated during coating.

On the other hand, in the structural industry, such as the automotive industry in recent years, forging steel, surface treatment steel, new alloy cast steel, difficult materials, etc. have been developed as a very improved material and processing characteristics. However, although these materials are tough compared to the existing materials, they have difficulty in chip processing and make welding and adhesion to the cutting tool easier during processing. Such welding and adhesion are mainly generated at the flank face, the rake face, the ridge of the cutting edge, and the like, and are particularly generated around the boundary between the flake face and the edge. As a result of the welding and adhesion, chipping and defects occur in the cutting edge of the cutting edge when the tool is continuously used, and the wear progresses rapidly, thereby reducing the cutting quality and shortening the tool life.

In order to solve this problem, EP1193328, through the surface treatment of the coated cutting tool 200, Al ₂ O ₃ layer (201, 202) is more chemically stable and excellent oxidation resistance than the Ti-based compound layer (203, 204) In order to minimize the welding by exposing to the outer layer. In addition, in EP0693574, a problem such as welding is solved by removing the outermost layer of the Ti-based layer only at the cutting edge. On the other hand, in Japanese Unexamined Patent Publication No. JP 1996-011005, unlike the above two methods, by removing the Al ₂ O ₃ layer is not good chipping resistance and by showing a relatively stable Ti-based compound of the base layer to the edge portion We tried to solve the welding problem.

On the other hand, one of the recent studies is to reduce the surface roughness (Ra, Rmax, etc.) by applying a variety of surface treatment to the cutting tool to ensure the lubricity of the workpiece and the cutting tool edge. As an example of such a method, US Patent US7090914 proposes a method for solving the problem of welding and chipping by controlling the surface roughness of the cutting edge through the surface treatment of the coating.

However, all of the above methods are intended to solve the two problems of the control of the residual stress of the thin film and the control of the cutting edge, respectively, which is insufficient in the overall solution.

Therefore, the present invention is to provide a method for manufacturing a cutting tool that can satisfy the control of the residual stress and the cutting edge of the thin film at the same time.

Accordingly, an object of the present invention is to provide a method for manufacturing a cutting tool that can improve not only toughness and wear resistance, but also welding and chipping resistance.

Another object of the present invention is to provide a cutting tool with improved toughness, wear resistance, welding resistance and chipping resistance.

In addition, the present invention, in the coated cutting tool coated with a hard layer on the outside, reducing the tensile residual stress of the thin film generated during the coating and reduce the surface roughness (Ra), the cutting tool without peeling the outer layer and its manufacturing method The purpose is to provide.

In the present invention, to prepare a substrate 100 for cutting tools; Forming a base layer (110) on the substrate (100); Forming a first coating layer (120) on the underlayer (110); Forming a second coating layer (130) on the first coating layer (120); Blasting the coating layer; It provides a method for manufacturing a cutting tool comprising a; and a brushing step.

Here, the substrate 100 for cutting tool may be formed by any one selected from the group consisting of hard metal, cermet, and ceramic.

The base layer 110 includes a layer formed by any one selected from the group consisting of Group IV, Group V, and Group VI metal elements, carbides, nitrides, carbonitrides, and carbonate nitrides of the metal elements.

That is, the underlayer 110 may include group IV, group V, and group VI metal elements; Carbides of the Group IV, Group V, and Group VI metal elements; Nitrides of the Group IV, Group V, and Group VI metal elements; Carbonitrides of the Group IV, Group V, and Group VI metal elements; And at least one layer formed by any one selected from the group consisting of carbonate nitrides of Group IV, Group V, and Group VI metal elements.

The first coating layer 120 may include a layer formed of any one of Al oxide, Zr oxide, and Hf oxide. According to an example of the present invention, the first coating layer 120 may include at least one layer formed by Al ₂ O ₃ .

According to an example of the present invention, the second coating layer 130 is formed by any one selected from the group consisting of Group IV, Group V and Group VI metal elements, carbides, nitrides, carbonitrides and carbonate nitrides of the metal elements. Layer.

That is, the second coating layer 130, Group IV, Group V and Group VI metal elements; Carbides of the Group IV, Group V, and Group VI metal elements; Nitrides of the Group IV, Group V, and Group VI metal elements; Carbonitrides of the Group IV, Group V, and Group VI metal elements; And at least one layer formed by any one selected from the group consisting of carbonate nitrides of Group IV, Group V, and Group VI metal elements.

According to an example of the present invention, the second coating layer 130 is M _w Ti _x C _y N _z (w + x + y + z = 1, w> 0, x> 0, y> 0, z> 0) Or M _x Ti _y N _z (x + y + z = 1, x> 0, y> 0, z> 0), wherein M is selected from Group IV, Group V, and Group VI metal elements. It is possible.

In the present invention, by controlling the conditions of the blasting step and the brushing step, the surface roughness is very low without peeling the coating layer of the outermost layer, very excellent lubricity of the cutting tool and the workpiece, reducing the tensile residual stress Avoid welding.

To this end, in the method for manufacturing a cutting tool according to the present invention, using the particles having a particle size of 10 ~ 400㎛ as the blasting and applying wet blasting performed by compressed air of 0.5 ~ 5.0 bar, in the brushing step Φ A brush of 0.1 to 1.0 mm is used, and a lubricating medium having a particle size of 0.1 to 10.0 μm is used.

In the present invention, the blasting step and the brushing step are performed at a strength that does not peel off the second coating layer 130.

According to an example of the present invention, in the wet blasting, Al ₂ O ₃ may be used as the particles.

On the other hand, the present invention provides a cutting tool manufactured by the above method. Cutting tool according to the invention the substrate 100; An underlayer 110 formed on the substrate 100; A first coating layer 120 formed on the base layer 110; And a second coating layer 130 on which the first coating layer 120 is formed.

In the cutting tool according to the present invention, the second coating layer 130 is not peeled off, and the surface roughness is low, thereby providing excellent lubricity with the workpiece.

According to an example of the present invention, the surface roughness Ra of the cutting tool may be in the range of 0.05 to 0.100 μm, and the compressive residual stress of the cutting tool may be in the range of 100 to −3900 MPa.

According to one embodiment of the present invention, an arc path from the boundary point 30 of the clearance surface 10 and the edge honing portion 20 of the cutting tool to a 70% point in the direction of the edge honing portion 20 is centered. It is desirable for the roundness to be less than ± 0.5%.

Further, according to an example of the present invention, the boundary portions 30 and P1 of the clearance surface 10 and the cutting edge honing portion 20 of the cutting tool deviate in the inclined surface direction from a point perpendicular to the clearance surface at the center C of the circle. It is preferred that the degree is less than 10%.

In the cutting tool according to the present invention, the first coating layer acts as a wear-resistant coating layer, the second coating layer acts as a hard coating layer, and the residual stress of the coated cutting tool by sequentially performing blasting and brushing in the state of forming the coating layers as described above. It is possible to reduce the surface roughness and improve the surface roughness. Through this effect, a high wear resistance cutting tool can be obtained.

In addition, the cutting tool according to the present invention can minimize the occurrence of welding and chipping during the processing of the workpiece because the cutting edge is very stable because no peeling is applied to the outer layer.

Hereinafter, with reference to the drawings and embodiments will be described the present invention in more detail.

The method of manufacturing a cutting tool according to the present invention includes the steps of preparing a substrate 100 for a cutting tool; Forming a base layer (110) on the substrate (100); Forming a first coating layer (120) on the underlayer (110); Forming a second coating layer (130) on the first coating layer (120); Blasting the coating layer; And a brushing step.

The coating layer may be formed by chemical vapor deposition (CVD) or physical vapor deposition (PVD).

In addition, by wet blasting treatment using the 10 ~ 400㎛ particles on the surface to reduce the residual stress and surface roughness generated during coating to have high toughness and wear resistance, in addition to the roundness of the cutting edge portion by brushing Improvements can minimize welding and chipping during machining. As a result, the cutting tool according to the present invention has a long life and excellent surface properties.

According to an embodiment of the present invention, the wet blasting sprays Al ₂ O ₃ particles having a diameter of 10 to 400 μm with water at a pressure of 0.5 to 5.0 bar directly to the coated cutting tool surface, thereby cutting the cutting edge of the coated cutting tool. The tensile residual stress of the uppermost layer of the sub-film is reduced, and has a compressive residual stress of 100 to -3900 MPa and a surface roughness Ra of 0.05 to 0.10 µm. Here, even when the wet blasting is performed, no peeling occurs in the outermost layer.

Further, the coating layer is brushed by using a brush having a diameter of 0.1 to 1.0 mm on a horizontal or vertical rotating body for the surface-treated coated cutting tool, and using a lubricant medium of 0.1 to 10.0 μm. At this time, the peeling does not occur in the outermost layer.

On the other hand, the cutting tool according to the present invention can be manufactured by the above method, specifically, the substrate 100; An underlayer 110 formed on the substrate 100; A first coating layer 120 formed on the base layer 110; And a second coating layer 130 on which the first coating layer 120 is formed.

The coated cutting tool according to the embodiment of the present invention forms a base layer 110 on a cemented carbide or cermet or ceramic substrate, and forms at least one layer 120 of Al ₂ O ₃ thin film having excellent wear resistance by chemical vapor deposition. In addition, the outer layer is coated with a hard layer 130 having excellent discrimination by using one of Group IV, Group V, and Group VI metal elements on the periodic table, or carbides, nitrides, carbonitrides, and carbonate nitrides of the metal elements.

As a result of the production, the cutting edge roundness (Rc, Ri, Ro), in particular, an arc from the boundary 30 of the clearance surface 10 and the edge honing portion 20 to a 70% point in the direction of the edge honing portion The roundness centered from the center is less than ± 0.5%, and the boundary portions 30 and P1 of the clearance surface 10 and the edge line honing portion 20 deviate in the inclined plane direction from a point perpendicular to the clearance surface from the center of the circle. A cutting tool having an accuracy B of less than 10% can be obtained.

The cutting tool surface-treated according to the present embodiment is excellent in the appearance discrimination and is in a state without peeling of the outermost layer, thereby improving toughness, wear resistance, welding resistance, and chipping resistance.

Hereinafter, the present invention describes each Example, Comparative Example, and Test Example.

<Example 1-3 and Comparative Example 1-4>

The cutting tool was manufactured according to the method of the present invention and the method of the prior art.

First, using a cemented carbide for a coated cutting tool corresponding to the ISO P20 grade as the base material 100, TiCN thin film was deposited by MT-CVD of 7㎛ thickness as a base layer 110.

In order to improve bonding between the deposition layers, an interfacial layer was formed on the base layer using a Ti-based compound, which is a known interfacial layer material, and then a 4 μm-thick Al ₂ O ₃ thin film was deposited as the first coating layer 120. Next, a cutting tool was manufactured by depositing 1 μm of TiCN / TiN as the second coating layer 130, which is the outermost layer.

The cutting tools were divided into seven groups.

Among the first group, blasting and brushing were not performed. This was called Comparative Example 1.

Only the blasting was done for the second group. This was called Comparative Example 2.

For the third to seventh groups, blasting and brushing were performed. These were set as Comparative Example 3, Comparative Example 4, and Examples 1 to 3, respectively. This is summarized in Table 1.

division Base layer First coating layer Second coating layer Blasting Brushing Comparative Example 1 TiCN Al ₂ O ₃ TiCN / TiN - - Comparative Example 2 TiCN Al ₂ O ₃ TiCN / TiN ○ - Comparative Example 3 TiCN Al ₂ O ₃ TiCN / TiN ○ ○ Comparative Example 4 TiCN Al ₂ O ₃ TiCN / TiN ○ ○ Example 1 TiCN Al ₂ O ₃ TiCN / TiN ○ ○ Example 2 TiCN Al ₂ O ₃ TiCN / TiN ○ ○ Example 3 TiCN Al ₂ O ₃ TiCN / TiN ○ ○

As wet blasting, wet blasting was performed, and the surface of the cutting tool was sprayed by wet blasting by spraying Al ₂ O ₃ powder having a size of 10 to 400 μm with water at 0.5 to 5.0 bar air pressure. At this time, the outermost layer was prevented from peeling off.

Brushing was performed while changing conditions. Brushing was carried out at 350 RPM using a disk-shaped brush attached to a bristles of thin threaded horsehair.

For the third group, brushing was performed at 350 RPM using a brush of Φ 0.5 mm and a lubricity medium of 11.0 μm. Here Φ0.5mm means that the diameter of the brush hair is 0.5mm. The third group corresponds to Comparative Example 3.

For the fourth group, brushing was performed at 350 RPM using a brush of Φ 1.5 mm and a lubricity medium of 1.0 μm. The fourth group corresponds to Comparative Example 4.

For the fifth group, brushing was performed at 350 RPM using a Φ 0.1 mm brush and a 10.0 μm lubricious media. The fifth group corresponds to Example 1.

For the sixth group, brushing was performed at 350 RPM using a brush of Φ 0.5 mm and a lubricity medium of 1.0 μm. The sixth group corresponds to Example 2.

For the seventh group, brushing was performed at 350 RPM using a brush of phi 1.0 mm and a lubricity medium of 0.1 탆. The seventh group corresponds to Example 3.

Test Example 1 Measurement of Properties

Surface roughness (Ra, μm), stress (MPa), roundness, and edge deviation (K) of the cutting tools prepared in Comparative Examples 1, 2 and Example 2 were measured.

The surface of the cutting tool was analyzed the surface roughness (Ra) of the 50㎛ portion of the cutting edge in the 50 × 50㎛ ² area at 50x magnification using NANO-VIEW (High Accuracy Mode) of NANO SYSTEM, the residual stress X 'The analysis was performed by the sin ² Ψ method using XRD of PERT. In addition, the shape of the cutting edge portion was measured by using a shape measuring instrument to analyze the degree of the edge.

Referring to FIG. 9, the roundness was analyzed from the three points of the 35% / 70% point P2 / P3 from the boundary P1 of the clearance surface and the edge honing portion toward the edge honing portion with respect to the edge El. The edge deviation was analyzed by analyzing the degree of deviation of the clearance plane perpendicular to the center of the circle (K edge deviation) from the generated clearance edge edge (P1).

The results are shown in Table 2 below.

division Surface Roughness (Ra, ㎛) Stress (MPa) Roundness Edge deviation (K) Comparative Example 1 0.319 174.1 ± 0.95 18.1 Comparative Example 2 0.098 -139.5 ± 0.72 29.2 Example 2 0.092 -140.2 ± 0.49 5.1

Looking at the results of Table 2, it can be seen that the cutting tool (Example 2) according to the present invention has superior physical properties than conventional cutting tools (Comparative Examples 1, 2), not only excellent surface roughness and stress It can be seen that it is particularly excellent in roundness and edge deviation.

<Test Example 2>

Turning was performed to evaluate the toughness and wear resistance of the cutting tools manufactured in the above Examples and Comparative Examples.

 (1) toughness evaluation conditions

Toughness assessment compared the final life by machining with increasing feed until end of life due to chipping or breakage under the same conditions.

Cutting condition: vc = 100m / min., Fn = variable, ap = 2.0mm, dry machining

Workpiece: SCM440-4groove (Φ300 × 50L)

Tool Part Number: CNMG120408-HM

When the service life of the cutting tool according to Comparative Example 1 is 100 and the relative service life is compared, the service life of the cutting tool according to Example 1 is 110, the service life of the cutting tool according to Example 2 is 119, and according to Example 3 The life of the cutting tool is 111, and it can be seen that the toughness of the cutting tool according to the present invention is superior to that of the cutting tool according to the prior art.

(2) Wear resistance evaluation condition

The wear resistance evaluation of the tool up to the said lifetime was performed according to the following conditions.

Cutting conditions: vc = 260 m / min., Fn = 0.35 (outer diameter), 0.25 (cross section) mm / rev., Ap = 2.0 mm, wet machining

Workpiece: SM45C (Φ100 × 130L)

Tool Part Number: CNMG120408-HM

Typically, the wear resistance evaluation results of Comparative Example 1 and Example 2 were disclosed in Figs. 5A (Comparative Example 1) and 5B (Example 2), respectively.

As can be seen from the photographs disclosed in FIGS. 5A and 5B, the cutting tool according to the present invention has better wear resistance than the cutting tool according to the prior art.

<Test Example 3>

Turning was performed for evaluation of welding resistance and chipping property of the cutting tool produced in the above Examples and Comparative Examples. Weldability and chipping evaluation were compared with the processing quality and processing performance from the degree of welding and chipping of the edge portion generated during the processing under the same conditions.

※ Condition for welding / chipping property

Cutting condition: vc = 300m / min., Fn = 0.300mm / rev., Ap = 2.0mm, wet machining

Workpiece: SM45C-4groove (Φ300 × 50L) Machining-Cooling Repeated Machining

Tool Part Number: CNMG120408-HM

Typically, the results of welding and chipping evaluation of Comparative Examples 1, 2 and Example 2 are disclosed in FIGS. 6A (Comparative Example 1), 6B (Comparative Example 2) and 6c (Example 2), respectively.

Looking at the above results, it can be seen that compared with the prior art, the cutting tool according to the present invention has improved welding resistance and chipping.

<Test Example 4>

The cutting edges of the cutting tools prepared in Examples 1-3 and Comparative Examples 3 and 4 were compared.

Representatively, photographs of the edges of the cutting tool produced in Comparative Example 4 and Example 2 are shown in FIGS. 7A (Comparative Example 4) and 7B (Example 2), respectively.

As seen above, it can be seen that only blasting and brushing under the conditions according to the present invention can have excellent surface roughness without peeling or scratching the edge portion. The cutting tool according to the present invention maintains the effect of blasting as it is, excellent surface lubricity and excellent weldability and chipping.

1 is a view showing an example of a conventional cutting tool showing a cutting edge (cutting edge).

2 is a view showing the edge portion of the cutting notification according to an example of the present invention.

3 is a view showing the edge portion of the cutting notification according to another embodiment of the present invention.

Figure 4 is a view showing the cutting edge of the cutting announcement according to another embodiment of the present invention.

5A and 5B are photographs comparing the wear resistance of the conventional cutting tool and the cutting tool according to the first embodiment of the present invention, respectively.

 6a to 6c are photographs comparing the welding resistance and the chipping resistance of the conventional cutting tool and the cutting tool according to Examples 1 and 2 of the present invention, respectively.

Figure 7a and 7b is a photograph of the cutting edge of the cutting tool produced in Comparative Example 4 and Example 2, respectively.

8 is a photograph of a cutting tool according to an example of the present invention.

9 is an enlarged photograph of a coating layer portion of a cutting tool according to an example of the present invention.

10 illustrates evaluating roundness and edge deviation K. FIG.

<Description of main parts of drawing>

100: base material (100) 110: base layer (110)

120: first coating layer 120 130: second coating layer 130

10: clearance surface 20: cutting edge honing part

30: boundary 40: slope

Claims (9)

Preparing a substrate 100 formed by any one selected from the group consisting of hard metal, cermet, and ceramic; An underlayer 110 including the layer formed on the substrate 100 by any one selected from the group consisting of Group IV, Group V, and Group VI metal elements, carbides, nitrides, carbonitrides, and carbonate nitrides of the metal elements. Forming a; Forming a first coating layer (120) on the base layer (110) comprising a layer formed of any one of Al oxide, Zr oxide, and Hf oxide; On the first coating layer 120, a second coating layer comprising a layer formed by any one selected from the group consisting of Group IV, Group V and Group VI metal elements, carbides, nitrides, carbonitrides and carbonate nitrides of the metal elements Forming 130; Blasting the coating layer; And Including a brushing step; The blasting is wet blasting using particles having a particle diameter of 10 ~ 400㎛ and compressed air of 0.5 ~ 5.0 bar, The brushing is performed using a brush of Φ 0.1 ~ 1.0mm and a lubricity medium having a particle size of 0.1 ~ 10.0㎛, And the blasting step and the brushing step are performed at a strength not to peel off the second coating layer (130). The method of claim 1, wherein the first coating layer (120) comprises at least one layer formed by Al ₂ O ₃ . The method of claim 1, wherein the particles used in the blasting step are Al ₂ O ₃ . The method of claim 1, wherein the second coating layer 130 is M _w Ti _x C _y N _z (w + x + y + z = 1, w> 0, x> 0, y> 0, z> 0) or M _x Ti _y N _z (x + y + z = 1, x> 0, y> 0, z> 0), M is selected from Group IV, Group V and Group VI metal elements. Cutting tool manufactured by the manufacturing method according to any one of claims 1 to 4. The cutting tool according to claim 5, wherein the surface roughness Ra is in the range of 0.05 to 0.100 µm. The cutting tool according to claim 5, wherein the compressive residual stress is in the range of 100 to -3900 MPa. 6. The cutting method as set forth in claim 5, wherein a roundness around an arc path from a boundary of the clearance surface of the cutting tool and the edge honing portion to a 70% point in the direction of the edge honing portion is less than ± 0.5%. tool. 2. The cutting tool according to claim 1, wherein a deviation of the boundary between the clearance surface of the cutting tool and the edge honing portion from the point perpendicular to the clearance surface at the center of the circle is less than 10%.

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