Ferrous seal sliding parts and producing method thereof

Abstract

A ferrous seal sliding part excellent in heat crack resistance, seizing resistance and abrasion resistance is provided. The ferrous seal sliding part having a seal sliding surface, wherein the seal sliding surface has a martensite parent phase which forms a solid solution with carbon of 0.15 to 0.6 wt % and contains a first dispersion material of at least either cementite of 5 to 70% by volume or MC-type carbide of 0.1 to 10% by volume and a second dispersion material of at least either graphite of 1 to 15% by volume or Cu alloy phase of 1 to 20% by volume dispersed therein, with a total content of the first dispersion material and the second dispersion material being 5 to 70% by volume.

Description

FIELD OF THE INVENTION [0001] The present invention relates to ferrous seal sliding parts available for floating seal members such as rollers, idlers and reduction gears for construction machines and a producing method thereof. BACKGROUND OF THE INVENTION [0002] A track roller assembly and a reduction gear apparatus of a construction machine are equipped with ferrous floating seal parts for the purpose of preventing leakage of lubrication oil from inside thereof as well as entering of earth and sand therein. Accordingly, such floating seal parts are widely produced by applying adequate treatment in which a seal sliding surface thereof is quenched to have a hard martensite structure, or a large amount of hard cementite and Cr7C3 carbide of 30% by volume are crystallized in the seal sliding surface while causing a parent, phase to a martensite by quenching, in order to improve seizing resistance and abrasion resistance. Such an exemplary floating seal part is made by using a Ni-hard c...

AI Technical Summary

Benefits of technology

The present invention provides a ferrous seal sliding part with a seal sliding surface that has a martensite parent phase with carbon and a dispersion material, such as cementite, MC-type carbide, graphite, or a Cu alloy phase, dispersed therein. The seal sliding surface can be formed by using a cast iron containing carbon, silicon, chromium, and one or more alloy elements. The ferrous seal sliding part can be made by casting using the cast iron and can be a floating seal part. The invention also provides a method for producing the ferrous seal sliding part. The technical effects of the invention include improved sealing performance and durability of the ferrous seal sliding part.

Problems solved by technology

Even in a case of a most conventionally used hard ferrous floating seal part made of a high-carbon and high-Cr cast iron, when setting pressure (press force) at assembling is high, considerable quenching crack (heat crack), seizing and abnormal abrasion occur on the seal sliding surface, resulting in leakage of oil.

And, even if various tool steels such as a cold work tool steel and a high speed steel (SKH material) are applied so as to increase the seizing resistance and the abrasion resistance, seizing due to defect of seizing resistance easily occurs, resulting in insufficient heat crack resistance and abrasion resistance.

In addition, since such steels are so expensive that a material costs would increase in view of material yields before a product is finished.

This also causes quenching crack, seizing and abnormal abrasion, resulting in leakage of oil.

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