Title:
VALVE LIFTER WITH WEAR-RESISTANT CAST IRON LAYER ON SURFACE
Document Type and Number:
Japanese Patent JPS5732004
Kind Code:
A
Abstract:
PURPOSE:To provide a valve lifter of high hardness, tenacity and mechanical performance, by making a wear-resistant cast iron layer on the surface of the wear- resistance-required part of the valve lifter. CONSTITUTION:For one embodiment, pig iron having a prescribed composition and obtained from the market is molten at 1450 to 1550 deg.C in a melting furnace such as an electric furnace. The molten metal is poured into the cavity 7 of a sand mold 5 through a runner 6 so that the molten metal solidifies. At that time, the poured molten metal is rapidly cooled for solidification by a chill 8 set at the bottom of the cavity 7 and a carbide containing much carbon in the form of solid solution is crystallized so that a chilled layer 9 is produced on the surface. After that, the chilled cast iron is heated to 800-900 deg.C in oil so that its pearlite is changed into martensite. The cast iron is then tempered at 500-600 deg.C so that its structure is changed into sorbite. The surface of the chilled cast iron is polished to a flat smooth surface. Nitriding is effected to a predetermined depth from the surface in a gas nitriding furnace so that a nitrided layer 10 is produced. An iron oxide layer 11 is made on the surface of the nitrided layer 10 by chemical treatment or the like. This results in providing wear-resistant cast iron containing structure of much crystallized carbide and structure of sorbite.
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Inventors:
KASUYA YOSHIZOU
Application Number:
JP10432980A
Publication Date:
February 20, 1982
Filing Date:
July 31, 1980
Export Citation:
Assignee:
KASUYA SEIKO
International Classes:
C22C37/00; F01L1/14; (IPC1-7): F01L1/14
Domestic Patent References:
| JP43017497A | ||||
| JPS5183846A | 1976-07-22 |