JPH0676649B2 - Sintered trochoidal rotor for oil motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sintered trochoid rotor for an oil motor, which is composed of an outer rotor and an inner rotor.

[Conventional technology]

In general, the trochoid rotor for the oil motor is composed of an outer rotor and an inner rotor, and is machined from a material such as low carbon steel into a predetermined shape by machining.
It is well known that it is manufactured by subsequently performing a carburizing and quenching treatment for the purpose of improving the surface hardness.

[Problems to be solved by the invention]

However, in the above-mentioned conventional trochoidal rotor, the production thereof is mechanical, so that the cost is inevitably high.
Many methods have been tried to manufacture by the powder metallurgy method which can omit the processing steps and is advantageous in terms of cost, but in any case, due to insufficient strength, the internal pressure reaches 200 Kg / cm ² or more. It is something that cannot be served.

[Means for solving problems]

Therefore, the present inventors, from the above viewpoint, as a result of conducting research to manufacture a tocolloid rotor having the same performance as the conventional trochoid rotor by the above-mentioned machining by the powder metallurgy method. % (Hereinafter% means% by weight), C: 0.3 to 1%, Cu: 0.9 to 5%, Ni: 2 to 6%, Mo: 0.1 to 1%, and the rest is Fe and inevitable impurities. Composition consisting of 7.3K
The trochoid rotor for oil motors, which has a density of g / cm ³ or more and a surface carburizing and quenching layer of 600 or more with Vickers hardness (Hv), is equivalent to the conventional trochoid rotor manufactured by machining and carburizing It has been found that it has the strength and wear resistance of No. 1, and can be sufficiently put to practical use under a high-pressure load condition of 200 Kg / cm ² or more.

The present invention has been made based on the above findings, and the reasons why the component composition range, density, and hardness of the surface carburized and quenched layer are limited as described above will be described below.

A component composition range (a) C C component is a solid solution in the matrix to enhance matrix strength, and
And Mo has the effect of forming carbides with Mo to improve the hardness, but if the content is less than 0.3, the desired effect cannot be obtained, while if the content exceeds 1%, toughness decreases. Therefore, its content is 0.3-1%
I decided.

(B) Cu The Cu component has a function of forming a solid solution in the matrix to enhance the matrix strength and forming a liquid phase at the time of sintering to promote densification. If the desired effect is not obtained on the other hand, and if its content exceeds 5%, the expansion phenomenon during sintering becomes remarkable and it becomes difficult to secure dimensional accuracy. % To 5%.

(C) Ni The Ni component, like the Cu component, acts to form a solid solution in the matrix to increase the strength, but if the content is less than 2%, the desired strength improving effect cannot be obtained, while 6% is added. Even if it is contained over the above range, further improvement in strength does not appear, and in consideration of economic efficiency, its content is set to 2 to 6%.

(D) Mo Mo component has the action of forming a solid solution in the matrix to increase the strength, and the action of forming carbides to improve the hardness as described above, but if the content is less than 0.1%, If the desired effect is not obtained on the other hand, and if the content exceeds 1%, the toughness is markedly reduced.
It was set at ~ 1%.

B Density To secure the strength and toughness required for the trochoid rotor for oil motors, the density must be 7.3 g / cm ³ or more.
It cannot withstand an internal pressure of 200 Kg / cm ² or more.

Further, particularly when used at a high pressure, it is preferable that the trochoid rotor, particularly the outer rotor, is impregnated with resin for improving airtightness.

C Hardness of surface carburizing and quenching layer Trochoid rotors are required to have excellent wear resistance in addition to strength and toughness, so surface hardness can be increased to Hv: 600 or more by normal carburizing and quenching treatment. Therefore, the desired wear resistance cannot be ensured with a hardness of less than Hv: 600. Therefore, the surface hardness due to the formation of the carburized and quenched layer is set to Hv: 600 or more.

〔Example〕

Next, the sintered trochoid rotor of the present invention will be described with reference to examples.

As raw material powders, each has a particle size of -100 mesh and contains 7 kinds of Fe-Cu- with different Cu, Ni, and Mo contents.
A Ni-Mo alloy powder and a graphite powder having a particle size of -200 mesh were prepared, and these raw material powders were mixed in the compounding compositions shown in Table 1, respectively, and 1% of zinc stearate was added as a lubricant, After mixing for 0.5 hours with a double cone type mixer, press-molding into a powder compact with a pressure of 6 ton / cm ² , and then under the condition of keeping the temperature for 3 hours at 450 ° C in an atmosphere of ammonia decomposition gas. Degreasing is performed, and subsequently, in a vacuum atmosphere with a vacuum degree of 10 ^-3 torr, sintering is performed at a predetermined temperature within the range of 1250 to 1270 ° C for 3 hours, and then 0.8 to
In a carburizing atmosphere with a C concentration within the range of 1.1% by volume, temperature: 850
~ 900 ℃, holding time: Carburizing treatment under the condition of 1-2 hours, after carburizing and water quenching, it has the substantially same composition as the composition, and maximum outer diameter: 50mmφ ×
Inner rotor with height: 25 mm and outer diameter: 76 mm
The sintered tocolloid rotors 1 to 9 of the present invention each comprising an outer rotor having a size of φ × height: 25 mm were manufactured.

Next, for the sintered trochoid rotors 1 to 9 of the present invention obtained as a result, surface hardness was measured by Vickers hardness for the purpose of evaluating wear resistance, and density and 0.2% proof stress was measured. These measurement results are shown in Table 1. Indicated. In addition, Table 1 also shows characteristic values of a conventional trochoid rotor obtained by carburizing and quenching a machined low carbon steel for comparison purposes.

〔The invention's effect〕

As shown in Table 1, each of the sintered trochoid rotors 1 to 9 of the present invention has a density of 7.3 g / cm ³ or more, and
Hv: It has a surface hardness of 600 or more and a proof stress of 70 Kg / mm ² or more, and these surface hardness and proof stress are equivalent to the characteristics that a conventional trochoid rotor has.

As described above, the sintered trochoidal rotor of the present invention has the same characteristics as the conventional trochoidal rotor manufactured by machining and carburizing and quenching treatment.
Even if an oil motor that reaches g / cm ² or more is used, excellent performance can be achieved over a long period of time.

Claims (2)

[Claims] 1. A composition containing C: 0.3 to 1%, Cu: 0.9 to 5%, Ni: 2 to 6%, Mo: 0.1 to 1%, and the balance consisting of Fe and inevitable impurities (more than wt%). ), A density of 7.3 g / cm ³ or more, and a surface carburizing and quenching layer of 600 or more in Vickers hardness, a sintered trochoid rotor for an oil motor. 2. A sintered trochoid rotor for an oil motor according to claim 1, which is impregnated with a resin for improving airtightness.