Stock material or miscellaneous articles – All metal or with adjacent metals – Having metal particles
Patent
1997-09-11
2000-03-07
Speer, Timothy M.
Stock material or miscellaneous articles
All metal or with adjacent metals
Having metal particles
419 6, 419 12, 419 14, 419 19, 419 23, 419 49, 419 60, B22F 702, B22F 706
Patent
active
060337893
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a high speed cutting tool, the material of which it is constructed, and the method of making such a tool. More particularly, the invention relates to materials formed by compaction of powdered materials.
BACKGROUND ART
It is known to produce metallic bodies by hot isostatic pressing (hip-ing) of powdered steel. In this procedure, the steel powder is compacted physically within a tube which is then evacuated of gas and sealed. The tube is then placed in a furnace and heated to a temperature in the region of 1050 to 1250.degree. C., usally 1100-1200.degree. C. An inert gas such as argon is supplied to the furnace at a desired pressure which may be in the region of 103 MPa. The cycle time may be in the region of 2 to 6 hours, allowing slow cooling. The powder in the tube is thereby compacted to form a unitary steel body which is cohesive, homogenous, and substantially free of potential stress fractures.
It is also known to make high speed and other cutting. tools from materials such as carbide containing steel, or from other steels. However, the high speed at which they operate, which may be 20,000 rpm, causes a high degree of wear at the cutting edges of the tool. Attempts have been made to extend the life of the tool by coating the edges with titanium nitride, which will lower the coefficient of friction by up to one third. However, this is not entirely satisfactory since the titanium nitride coating quickly wears away so as to leave an unlubricated utting edge, which becomes blunt even more quickly.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a high speed cutting tool and a material from which it is constructed which enables the cutting tool to give improved performance for a longer period of use.
BEST MODE FOR CARRYING OUT THE INVENTION
According to a first aspect of the present invention there is provided a cutting tool comprising at least one cutting edge formed by a compacted mixture of carbide containing alloy steel and a ceramic material.
Preferably the mixture of at least one cutting edge comprises additionally particles of a hard or abrasive material.
The abrasive material may comprise 0.01-15 wt % of the mixture, optionally in the region of 1 to 10 wt %.
The abrasive material may comprise a carbide, such as silicon carbide or aluminium carbide or a boride/carbide such as aluminium titanium diboride-titanium carbide.
The ceramic material preferably comprises 0.01-15 wt % of the mixture, optionally in the region of 1 to 6 wt %.
In preferred embodiments, the amount of ceramic material may be 2 to 5 wt %, advantageously in the region of 3 wt %.
The ceramic material may comprise zirconium oxide, optionally stabilised by a minor amount of calcium oxide.
The ceramic material may have a particle size in the region of 1 to 15 .mu.m, preferably 1 to 4 .mu.m.
The steel may have a particle size of less than or equal to 500 .mu.m.
The hardness of the steel body formed from the powder may vary slightly with the powder size but is generally in the region of 270 to 295 Hv20, which is increased after hardening.
Particles of carbide in the steel may have a size in the region of 3 to 5 .mu.m.
According to a second aspect of the present invention there is provided a metallic body comprising a steel core zone and a peripheral zone comprising a compacted mixture of carbide containing alloy steel and a ceramic material.
The core zone may comprise a compacted mass of powdered alloy steel.
The core zone may alternatively or additionally comprise a core of mild or other steel.
The peripheral zone may additionally comprise particles of a hard or abrasive material.
The abrasive material may comprise 0.01-15 wt % of the mixture, optionally in the region of 1 to 10 wt %.
The abrasive material may comprise a carbide, such as silicon carbide or aluminium carbide or a boride/carbide such as aluminium titanium diboride-titanium carbide.
The ceramic material preferably comprises 0.01-15 wt % of the mixture, optionally in the region of 1 t
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patent: 4592252 (1986-06-01), Ecer
patent: 4618540 (1986-10-01), Holst
patent: 4630692 (1986-12-01), Ecer
patent: 4973356 (1990-11-01), Holst
patent: 5053284 (1991-10-01), Noda
patent: 5106576 (1992-04-01), Noda
patent: 5403670 (1995-04-01), Ohsue
Bonnell Trevor David
Saveker Jonathan James
Speer Timothy M.
Young Bryant
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