US20170145753A1

US20170145753A1 - Cutting tool insert

Info

Publication number: US20170145753A1
Application number: US15/324,261
Authority: US
Inventors: Young Ho Ko; Hee Sub Park
Original assignee: Iljin Diamond Co Ltd
Current assignee: Iljin Diamond Co Ltd
Priority date: 2014-05-22
Filing date: 2015-05-13
Publication date: 2017-05-25
Also published as: KR20150134706A; WO2015178617A1

Abstract

A cutting tool insert is disclosed. The disclosed cutting tool insert comprises: a supporting substrate extending in a first direction; and a cutting layer coupled to one surface of the supporting substrate and supported by the supporting substrate, wherein the one surface of the supporting substrate has an uplift part, which is uplifted in the first direction. The present invention can reduce a residual stress generated in a polycrystalline diamond compact.

Description

TECHNICAL FIELD

The present invention relates to a cutting tool insert.

BACKGROUND ART

An insert for a cutting tool is coupled to a tool assembly used for an oil drilling operation or a cutting operation and is used for an excavating operation of cutting down the bedrock and the like existing in the underground or a cutting operation of cutting metal or other members.
A plurality of inserts for the cutting tool is generally attached to the cutting tool.
Further, the insert for the cutting tool may include a supporting substrate shaped like a pillar, and a cutting layer formed at one end of the supporting substrate and formed of a super hard layer so as to perform a cutting function.
In this case, the cutting layer may include a polycrystalline diamond compact, and the diamond compact is generally sintered under a high temperature and high pressure condition, under which diamond particles are crystallographically or thermodynamically stable.

DISCLOSURE

Technical Problem

The present invention has been made in an effort to provide a cutting tool insert, which is capable of decreasing residual stress generated in a crystalline diamond compact.
Other objects of the present invention are derivable by those skilled in the art through an exemplary embodiment below.

Technical Solution

According to an exemplary embodiment of the present invention, there is provided a cutting tool insert, including: a supporting substrate extended in a first direction; and a cutting layer coupled to one surface of the supporting substrate and supported by the supporting substrate, in which the one surface of the supporting substrate is formed with an uplift part uplifted in the first direction.
The uplift part may include a center supporting part uplifted from a center in the first direction, and a circumference supporting part uplifted between the center supporting part and an outer circumferential surface of the supporting substrate in the first direction.
The supporting substrate may have a cylindrical shape extended in the first direction, and the center supporting part may have a smaller diameter (D2) than a diameter (D1) of the supporting substrate.
The circumference supporting part may be gradually uplifted from the outer circumferential surface of the supporting substrate to the center supporting part.
An inclination (α) of the circumference supporting part based on a second direction, which is perpendicular to the first direction, may be 20° or less.
The center supporting part may be gradually uplifted from the circumference supporting part to the center.
A curvature radius (r) of the center supporting part may be 37.5 mm or less.
A curvature radius (r) of the circumference supporting part may be 37.5 mm or less.
A ratio of an area of the center supporting part to an area of the uplift part may be 0.45 to 0.8.
An upper surface of the center supporting part may be surface treated so as to have an unevenness structure.
The unevenness structure may be formed in a bilaterally symmetric structure based on a center of the upper surface of the center supporting part.

Advantageous Effect

According to the present invention, there is an advantage in that it is possible to decrease residual stress generated in a crystalline diamond compact.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a cutting tool insert according to an exemplary embodiment of the present invention.

FIG. 2 is an exploded perspective view illustrating the cutting tool insert according to the exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along line AA of FIG. 1.

FIG. 4 is a diagram illustrating residual stress in a top portion and an outside portion of a cutting layer according to an inclination angle of a circumference supporting part according to the exemplary embodiment of the present invention.

FIG. 5 is a diagram illustrating residual stress in the top portion and the outside portion of the cutting layer according to a curvature radius of a center supporting part according to the exemplary embodiment of the present invention.

FIG. 6 is a diagram illustrating maximum residual stress according to a ratio of an area of the center supporting part to an area of an uplift part.

FIGS. 7A, 7B, and 7C are a top plan view, a front view, and a cross-sectional view of a supporting substrate 110′ according to another exemplary embodiment of the present invention, respectively.

BEST MODE

According to an exemplary embodiment of the present invention, there is provided a cutting tool insert, including: a supporting substrate extended in a first direction; and a cutting layer coupled to one surface of the supporting substrate and supported by the supporting substrate, in which the one surface of the supporting substrate is formed with an uplift part uplifted in the first direction

Mode for Carrying Out the Invention

The present invention may be variously modified and have various exemplary embodiments, so that specific embodiments will be illustrated in the drawings and described in the detailed description. However, it is not intended to limit the present invention to the specific embodiments, and it will be appreciated that the present invention includes all modifications, equivalences, or substitutions included in the spirit and the technical scope of the present invention. In the description of respective drawings, similar reference numerals designate similar elements.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to accompanying drawings.
FIG. 1 is a perspective view illustrating a cutting tool insert 100 according to an exemplary embodiment of the present invention, and FIG. 2 is an exploded perspective view illustrating the cutting tool insert according to the exemplary embodiment of the present invention.
FIG. 3 is a cross-sectional view taken along line AA of FIG. 1.
As illustrated in FIGS. 1 to 3, the cutting tool insert 100 according to the exemplary embodiment of the present invention includes a supporting substrate 110 and a cutting layer 120.
The supporting substrate 110 according to the exemplary embodiment of the present invention may be formed in a pillar shape, for example, a cylinder shape extended in a first direction. In this case, the first direction may mean an up direction of the supporting substrate 110 as illustrated in FIGS. 1 to 3.
The supporting substrate 110 may be formed of a carbide alloy including tungsten (W), tantalum (Ta), vanadium (V), and titanium (Ti), and in this case, cobalt (Co), iron (Fe), nickel (Ni), and the like may be used as a binder for easily binding a pellet.
For example, the supporting substrate 110 may include a cobalt-based tungsten carbide (WC-Co) alloy, and for a sintering process for forming the supporting substrate, a sintering process may be performed by putting a cobalt-based tungsten carbide material into a mold.
The cutting layer 120 is formed on an upper surface of the supporting substrate 110.
In the present invention, for convenience of the description, it is assumed that the cutting layer 120 is formed on the upper surface of the supporting substrate 110, but the cutting layer 120 may also be formed on a lower surface of the supporting substrate 110 according to a direction of the view.
The cutting layer 120 according to the exemplary embodiment of the present invention may include a basic material 122 and diamond particles 124.
For example, the base material 122 may contain cobalt-based tungsten carbide (WC-Co), and the diamond particles 124 may be formed of polycrystalline diamond (PCD).
A sintering method is used for forming the cutting layer 120 on the upper surface of the supporting substrate 110, so that the sintering process according to the exemplary embodiment of the present invention will be described in more detail.
First, a material for forming the cutting layer 120 is put into a predetermined mold in a powder form.
That is, cobalt-based tungsten carbide (WC-Co) powder for forming the base material 122 and crystalline diamond particles for forming the diamond particles 124 are put.
In this case, a volume ratio of the diamond particles 124 in the cutting layer 120 may be ½ to ⅘. When the volume ratio of the diamond particles 124 is less than ½, cutting efficiency is decreased. Further, the volume ratio of the diamond particles 124 is more than ⅘, the quantity of base material 122 interposed between the diamond particles 124 is decreased, and this causes deterioration of bonding force between the diamond particles 124 and the base material 122, so that the diamond particles 124 are easily separated from the cutting layer 120. Accordingly, the volume ratio of the diamond particles 124 may be ½ to ⅘.
Next, the base material 122 and the diamond particles 124 are evenly distributed by using a ball mill, an attrition mill, and the like.
Then, the supporting substrate 110 is put into the mold, into which the powders are input, and the powders face the upper surface of the supporting substrate 110 so that the cutting layer 120 is coupled to the upper surface of the supporting substrate 110.
In this case, the base material 122 may be distributed on a surface of the cutting layer 120 which is in contact with the upper surface of the supporting substrate 110.
As described above, the supporting substrate 110 may contain the carbide-based alloy (for example, a cobalt-based tungsten carbide), and the base material 122 may also contain the cobalt-based tungsten carbide, so that the upper surface of the supporting substrate 110 and the base material 122 contain the same component, and as a result, bonding force of the upper surface of the supporting substrate 110 and the base material 122 may be further improved than bonding force of other parts, that is, bonding force of the upper surface of the supporting substrate 110 and the diamond particles 124.
In this case, bonding force of the supporting substrate 110 and the cutting layer 120 may also be improved by distributing only the base material 122 on the surface of the cutting layer 120 which is to be bonded to the upper surface of the supporting substrate 110. Accordingly, it is possible to prevent the supporting substrate and the cutting layer from being separated, thereby improving durability of the cutting tool insert.
Next, sintering is performed at a high temperature and high pressure so that the supporting substrate 110 is coupled to the cutting layer 120. For example, a sintering process may be performed while maintaining up to a high temperature of about 1,300 to 1,500° C. and high pressure of 5 to 7 GPa.
In order to maintain the high temperature and the high pressure, the process may be performed by sealing the mold, into which the supporting substrate and the cutting layer are put, with a large cell again, and after the sintering process, the outer mold and the sealing cell are removed, and then the supporting substrate and the cutting layer are processed and used.
According to a characteristic of the sintering process performed at the high temperature and the high pressure, the cutting tool insert accompanies residual stress. That is, thermal coefficients of the supporting substrate 110 and the cutting layer 120 are different, so that residual stress is generated.
The residual stress generates cracks in an interface region and inner sides of the supporting substrate and the cutting layer, thereby causing deterioration of durability of the cutting tool insert.
According to the exemplary embodiment of the present invention, the residual stress of the crystalline diamond compact, that is, the cutting layer 120, may be decreased, and hereinafter, this will be described in more detail with reference to FIG. 3.
As illustrated in FIG. 3, an uplift part 112 uplifted in an upper direction is formed on the upper surface of the supporting substrate 110 according to the exemplary embodiment of the present invention. It can be seen that when the cylindrical supporting substrate 110 is extended in the first direction, the uplift part 112 is also uplifted in the first direction.
The uplift part 112 includes a center supporting part 1121 uplifted from a center in the up direction, and a circumference supporting part 1122 uplifted between the center supporting part 1121 and an outer circumferential surface of the supporting substrate 110 in the up direction, and the circumference supporting part 1122 and the center supporting part 1121 are uplifted toward the center.
First, the center supporting part 1121 is formed to have a smaller diameter D2 than a diameter 1 of the supporting substrate 110 to support a center part of the cutting layer 120.
An unevenness structure for improving bonding force with the cutting layer 120 may be applied to an upper surface of the center supporting part 1121. For example, as illustrated in FIG. 3, the upper surface of the center supporting part may be surface-treated so that a plurality of recesses having a fan shape is formed along a circumference of the center supporting part.
In this case, the unevenness structure may have a bilaterally symmetric structure based on a center of the upper surface of the center supporting part so that bonding force with the cutting layer 120 is evenly improved throughout the entire upper surface of the center supporting part 1121.
Further, the circumference supporting part 1122 is formed to be gradually uplifted from the outer circumferential surface of the supporting substrate 110 to the center supporting part 1121 to support a circumference part of the cutting layer 120.
The circumference supporting part 1122 has the gradually uplifted shape, so that the circumference supporting part 1122 is slantly formed, and herein, an inclination α of the circumference supporting part 1122 may be 20° or less.
FIG. 4 illustrates residual stress in a top portion and an outside portion of the cutting layer 120 according to an angle of an inclination α of the circumference supporting part 1122 according to the exemplary embodiment of the present invention.
Referring to FIG. 4, it can be seen that compared to a case where the circumference supporting part 1122 is flat, when the inclination α is −10°, residual stress of the top portion and the outside portion is decreased by 23.56% and 38.03%, respectively, when the inclination α is −15°, residual stress of the top portion and the outside portion is decreased by 29.32% and 49.58%, respectively, and when the inclination α is −20°, residual stress of the top portion and the outside portion is decreased by 35.10%, and 58.31%, respectively.
That is, the circumference supporting part 1122 is not formed to be flat, but is formed to be gradually uplifted from the outer circumferential surface of the supporting substrate 110 to the center supporting part 1121, and thus, when the circumference supporting part 1122 is formed to be slant by 20°, residual stress generated in the top portion and the outside portion of the cutting layer 120 may be decreased up to 35.10% and 58.31%, respectively.
On the contrast to this, when the circumference supporting part 1122 is formed to be gradually lowered from the outer circumferential surface of the supporting substrate 110 to the center supporting part 1121, that is, the circumference supporting part 1122 is formed higher than the center supporting part 1121, residual stress in the top portion and the outside portion is increased by 11% and 61.69%, respectively, compared to the case where the circumference supporting part 1122 is flat, so that the case is not preferable.
In the meantime, when the circumference supporting part 1122 has an inclination larger than 20°, the material for forming the cutting layer 120 is more consumed according to the increased inclination, and the diffusion is not properly performed during the sintering process, so that the circumference supporting part 1122 may have an inclination of 20° or less.
According to the exemplary embodiment of the present invention, the center supporting part 1121 may also be formed so as to be gradually uplifted toward the center. That is, the center supporting part 1121 is formed to be gradually uplifted from the circumference supporting part 1122 to the center to support the center portion of the cutting layer 120.
The center supporting part 1121 has the gradually uplifted shape, so that the center supporting part 1121 has a predetermined curvature, and in this case, a curvature radius r of the center supporting part 1121 may be 37.5 mm or less.
FIG. 5 illustrates residual stress in a top portion and an outside portion of the cutting layer 120 according to a curvature radius r of the center supporting part 1121 according to the exemplary embodiment of the present invention.
Referring to FIG. 5, it can be seen that compared to a case where the center supporting part 1121 is flat, when a curvature radius r is 40 mm, residual stress in the top portion and the outside portion of the cutting layer 120 is increased by 40.31% and 5.35%, respectively, but the residual stress is sharply decreased until the curvature radius r is 37.5 mm, and when the curvature radius r is 30 mm, residual stress in the top portion and the outside portion of the cutting layer 120 is decreased by 28.8% and 47.32%, respectively.
That is, the center supporting part 1121 is not flatly formed, but is formed to be gradually uplifted from the circumference supporting part to the center, and thus, when the center supporting part 1121 is formed to have a curvature radius r of 37.5 mm or less, residual stress generated in the top portion and the outside portion of the cutting layer 120 may be decreased up to 28.8% and 47.32%, respectively.
When a curvature radius r of the center supporting part 1121 is less than 30 mm, the material for forming the cutting layer 120 is more consumed according to the small curvature radius, and the diffusion is not properly performed during the sintering process, so that the center supporting part 1121 may have a curvature radius r of 30 mm or more.
In the meantime, for convenience of the description, the center supporting part 1121 is discriminated from the circumference supporting part 1122, but the center supporting part and the circumference supporting part are continuously formed to form one uplift part 110 on the upper surface of the supporting substrate 110, and a curvature radius of the circumference supporting part 1122 may be 37.5 mm or less.
The center supporting part 1121 has a curvature of 37.5 mm or less and the circumference supporting part 1122 is formed to have an angle of 20° or less in order to decrease residual stress of the cutting layer 120 as described above, so that an area ratio of the center supporting part 1121 to the entire area of the uplifted part 110 may be drawn.
According to the exemplary embodiment of the present invention, an area ratio of the center supporting part 1121 to the entire area of the uplifted part 110 may be 0.45 to 0.8.
FIG. 6 illustrates maximum residual stress (a y-axis) according to an area ratio (an x-axis) of the center supporting part to the area of the uplift part, and referring to FIG. 6, an area ratio of the center supporting part is decreased within a range, in which an area ratio of the center supporting part is 0.45 to 0.8, so that maximum residual stress tends to also be decreased.
In this case, when the area ratio of the center supporting part to the area of the uplift part is less than 0.45, the material for forming the cutting layer 120 is more consumed, and the diffusion is not properly performed during the sintering process, and when the area ratio of the center supporting part to the area of the uplift part is larger than 0.8, there is difficulty in manufacturing the insert, so that the area ratio of the center supporting part to the area of the uplift part may be 0.45 to 0.8.
In the meantime, the present invention has been described based on the example, in which the predetermined inclination α angle according to the exemplary embodiment of the present invention is applied to the circumference supporting part 1122, and simultaneously, the predetermine curvature radius r according to the exemplary embodiment of the present invention is also applied to the center supporting part 1121, but according to another exemplary embodiment of the present invention, as illustrated in FIG. 7, a supporting substrate 110′, in which an inclination is applied only to a circumference supporting part 1122′, may also be taken.
FIGS. 7A, 7B, and 7C are a top plan view, a front view, and a cross-sectional view of the supporting substrate 110′ according to another exemplary embodiment of the present invention, respectively, and as illustrated in FIGS. 7A, 7B, and 7C, an uplift part 112′ uplifted in an up direction may be formed on an upper surface of the supporting substrate 110′, and the uplift part 112′ may include a center supporting part 1121′ uplifted from the center thereof in the up direction, and a circumference supporting part 1122′ uplifted in the up direction between the center supporting part 1121′ and an outer circumferential surface of the supporting substrate 110′.
In this case, only the circumference supporting part 1122′ may be formed to be gradually uplifted from the outer circumferential surface of the supporting substrate to the center supporting part, and the center supporting part 1121′ may be formed in a flat shape, not a shape gradually uplifted from the circumference supporting part to the center.
In this case, it cannot be expected even a residual stress decrease effect according to an application of a predetermined curvature radius r to the center supporting part 1121′, but the inclination α angle according to the exemplary embodiment of the present invention may be applied to the circumference supporting part 1122′, so that a residual stress decrease effect may be still expected.
In the meantime, the upper surface of the center supporting part 1121′ of the supporting substrate according to another exemplary embodiment of the present invention may be surface treated so as to have an unevenness structure for improving bonding force with a cutting layer 120.
A predetermined combteeth pattern may be formed on the upper surface of the center supporting part 1121′ by the surface treatment, and the combteeth pattern may have a bilaterally symmetric structure based on a center of the upper surface of the center supporting part 1121′ as illustrated in FIG. 7.
As described above, according to the present invention, there is an advantage in that it is possible to decrease residual stress generated to the cutting layer including crystalline diamond.
The specified matters and embodiments and drawings such as specific apparatus drawings of the present invention have been disclosed for illustrative purposes, but are not limited thereto, and those skilled in the art will appreciate that various modifications, additions and substitutions are possible from the disclosure in the art to which the present invention belongs. The spirit of the present invention is defined by the appended claims rather than by the description preceding them, and all changes and modifications that fall within metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the range of the spirit of the present invention.

Claims

1. A cutting tool insert, comprising:

a supporting substrate extended in a first direction; and

a cutting layer coupled to one surface of the supporting substrate and supported by the supporting substrate,

wherein the one surface of the supporting substrate is formed with an uplift part uplifted in the first direction.

2. The cutting tool insert of claim 1, wherein the uplift part includes a center supporting part uplifted from a center in the first direction, and a circumference supporting part uplifted between the center supporting part and an outer circumferential surface of the supporting substrate in the first direction.

3. The cutting tool insert of claim 2, wherein the supporting substrate has a cylindrical shape extended in the first direction, and the center supporting part has a smaller diameter (D2) than a diameter (D1) of the supporting substrate.

4. The cutting tool insert of claim 2, wherein the circumference supporting part is gradually uplifted from the outer circumferential surface of the supporting substrate to the center supporting part.

5. The cutting tool insert of claim 4, wherein an inclination (α) of the circumference supporting part based on a second direction, which is perpendicular to the first direction, is 20° or less.

6. The cutting tool insert of claim 4, wherein the center supporting part is gradually uplifted from the circumference supporting part to the center.

7. The cutting tool insert of claim 6, wherein a curvature radius (r) of the center supporting part is 37.5 mm or less.

8. The cutting tool insert of claim 7, wherein a curvature radius (r) of the circumference supporting part is 37.5 mm or less.

9. The cutting tool insert of claim 7, wherein a ratio of an area of the center supporting part to an area of the uplift part is 0.45 to 0.8.

10. The cutting tool insert of claim 6, wherein an upper surface of the center supporting part is surface treated so as to have an unevenness structure.

11. The cutting tool insert of claim 10, wherein the unevenness structure is formed in a bilaterally symmetric structure based on a center of the upper surface of the center supporting part.