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Tool made of cubic boron nitride sintered body

a technology of boron nitride and tool body, which is applied in the direction of manufacturing tools, turning machine accessories, other chemical processes, etc., can solve the problems of cbn sintered body diffusion, poor cutting efficiency, and inability to cut, so as to improve the hardness of the tool, improve the hardness, and improve the effect of hardness

Inactive Publication Date: 2013-11-07
SUMITOMO ELECTRIC HARDMETAL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a tool made of a cubic boron nitride sintered body that achieves both lowering in thermal conductivity and improvement in hardness. By containing a cBN component by not less than 60 volume % and adding an intermetallic compound in a form of fine particles, a compound composed of one or more types of element selected from the group consisting of Al, Si, Ti, Zr, or the like, and one or more types of element selected from the group consisting of N, C, O, and B, which has an average particle size smaller than 100 nm, a compound composed of one or more types of element selected from the group consisting of Al, Si, Ti, Zr, or the like, and one or more types of element selected from the group consisting of N, C, O, and B, can act as a heat insulating phase to lower thermal conductivity. This tool has excellent wear resistance and chipping resistance.

Problems solved by technology

In a case where a tool made of a cBN sintered body high in cBN content is applied to cutting of a recent difficult-to-machine material having low ductility characteristics, however, since the cBN sintered body has high thermal conductivity, friction heat generated in a worked portion during cutting diffuses into the cBN sintered body.
Consequently, cutting cannot proceed while a high temperature of the difficult-to-machine material is maintained and hence cutting efficiency becomes significantly poor.
Therefore, since the work material does not soften due to insufficient conduction of heat generated during working to the work material, load is imposed on the tool and even the tool made of the cBN sintered body high in chipping resistance is chipped.
In particular during cutting of an iron-based sintered alloy, because of its low ductility, in a cutting environment where a temperature of a work material is insufficient, shear does not smoothly proceed, pits are created in a worked surface, and surface roughness may become poor.
When a cutting speed is increased in order to improve surface roughness, that is, a temperature of the work material is raised, wear rapidly develops and a satisfactory tool life cannot be obtained.
It is estimated that a main factor for such chipping caused in a cBN sintered body would be a mechanism of mechanical damage such as crush of cBN particles themselves due to insufficient strength or conspired falling-off of cBN particles due to insufficient binding force among the cBN particles.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0069]A tool made of a cBN sintered body was fabricated as below. Initially, a compound obtained by mixing WC powders having an average particle size of 1.3 μm, Co powders having an average particle size of 1.1 μm, and Al powders having an average particle size of 4 μm at a mass ratio of WC:Co:Al=25:68:7 and then subjecting the mixture to heat treatment under vacuum at 1000° C. for 30 minutes was crushed with a ball of φ4 mm made of cemented carbide, to thereby obtain source material powders forming the binder phase.

[0070]Then, as a component for the first compound forming the heat insulating phase, a mixture of Al powders having an average particle size of 0.85 μm and Zr powders having an average particle size of 0.7 μm was subjected to heat treatment in a nitrogen atmosphere at 1000° C. for 30 minutes to thereby fabricate a compound. Thereafter, the compound was coarsely crushed, and then a medium having a diameter of φ0.6 mm and made of zirconia was employed, and the medium and t...

examples 2 to 3

[0074]Tools made of cBN sintered bodies according to Examples 2 to 3 respectively were fabricated with the method the same as in Example 1 except that a cBN content was different as in Table 1 from the tool made of the cBN sintered body according to Example 1.

examples 4 to 6

[0075]Tools made of cBN sintered bodies according to Examples 4 to 6 respectively were fabricated with the method the same as in Example 1 except that a cBN content and composition in the heat insulating phase were different as in Table 1 from the tool made of the cBN sintered body according to Example 1.

[0076]For example, in Example 4, as a component for the first compound forming the heat insulating phase, a mixture of Ti powders having an average particle size of 0.9 μm and Zr powders having an average particle size of 0.7 μm was employed. Similarly, in Example 5, as a component for the first compound in the heat insulating phase, a mixture of Ti powders having an average particle size of 0.9 μm and Si powders having an average particle size of 0.8 μm was employed. In Example 6, as the component for forming the heat insulating phase, Al powders having an average particle size of 0.85 μm and Zr powders having an average particle size of 0.7 μm was employed for the component for th...

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Abstract

A tool includes a cubic boron nitride sintered body at least at a tool working point. The cubic boron nitride sintered body contains cubic boron nitride, a heat insulating phase, and a binder phase. Cubic boron nitride is contained in the cubic boron nitride sintered body by not less than 60 volume % and not more than 99 volume %, and the heat insulating phase includes one or more types of first compound composed of one or more types of element selected from the group consisting of Al, Si, Ti, and Zr and one or more types of element selected from the group consisting of N, C, O, and B. The first compound is contained in the cubic boron nitride sintered body by not less than 1 mass % and not more than 20 mass % and it has an average particle size smaller than 100 nm.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a tool made of a cubic boron nitride sintered body and particularly to a tool made of a cubic boron nitride sintered body excellent in wear resistance and chipping resistance.[0003]2. Description of the Background Art[0004]In cutting a material, a cutting tool and a cutting method suitable for a work material are selected. In order to achieve a long life during cutting, it is important how a temperature at a cutting edge during cutting can be suppressed, and a tool material having excellent thermal conductivity is valued. In general, also during cutting using a tool made of an ultra-high pressure sintered body such as a diamond sintered body and a cubic boron nitride (which may also be denoted as “cBN”) sintered body excellent in thermal conductivity, diffusion into a work material or chemical wear such as oxidation develops due to increase in temperature at the cutting edge under such a...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B24D3/04
CPCB22F2005/001B23B2226/125B23C2226/125C04B35/5831C04B35/6268C04B35/645C04B2235/3847C04B2235/40C04B2235/402C04B2235/404C04B2235/5436C04B2235/5445C04B2235/96C22C2026/003
Inventor KUKINO, SATORUOKAMURA, KATSUMIFUKAYA, TOMOHIRO
Owner SUMITOMO ELECTRIC HARDMETAL CORP
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