Cold-drawn cast iron products, European countries and the United States began to develop as early as the early 1920s, widely popularized in the sixties and seventies, and the technology of the eighties was fully mature. Cold-drawn cast iron products are widely used in internal combustion engines because of their remarkable features of low cost and high performance.
The camshaft is an indispensable and important component of the internal combustion engine valve train. Its role is to control the valve movement and open and close according to a certain working sequence and time. Therefore, it must have excellent wear resistance. Now commonly used domestic camshafts are made of medium carbon steel surface quenching and ductile iron isothermal quenching.
In foreign countries, 43% of the internal combustion engine industry—47% gasoline engine and diesel engine use cold-used cast iron as the camshaft material. The chilled cast iron is widely used as the camshaft material and has been widely used due to its remarkable features of low cost and high performance.
First, the performance and application of chilled cast iron camshaft
Cold-drawn cast iron has good wear resistance and scratch resistance due to its high hardness carbide structure. The white-colored layer in the cast iron is leucite. At room temperature, it is a mechanical mixture of pearlite and carbides. Since it contains a large amount of carbides, it acts as a skeleton. The hardness is higher, and the pearlite in the leucite plays a role in oil storage. This rod's wear resistance, abrasion resistance and oil storage are widely recognized and applied in the internal combustion engine industry.
The chilled cast iron camshaft is made by adding a certain amount of alloying elements on the basis of HT250, and is cast through a special casting process. The addition of alloying elements improves the hardness and overall mechanical properties of the camshaft base body and greatly improves the wear resistance. The wear volume of the chilled cast iron is only about 12% of the 45# steel and other camshafts of the ductile iron.
1, mechanical properties tensile strength ób> 250N/mm2
2, hardness HRC48 - 54
3, wear layer depth of ? 6 - 10mm
Third, due to the current use of ductile iron and 45 # steel using austempering or high frequency quenching to obtain martensite structure. After high-speed operation, early abrasion of the cam lobe occurs, and the chilled cast iron adopts a special forming process and does not require heat treatment. All the parts of the camshaft can get the required different hardness values. The amount of wear on the tip of the loach is only 1/7 of ductile iron and 45# steel, and it has the advantages of reduced processing costs and improved economy.
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Pool: This tower's pool and foundation, pre-buried steel plate, etc. by the user is responsible for, the water level should be controlled at -0.25-0.3m as well.
Applied to petroleum, chemical, metallurgy, medicine, electricity and other industrial large water circulation system.
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