Electro hydraulic valve casting is a kind of hydraulic control element. Its control pressure is much higher than that of conventional valve casting, and its structure is also complex. In order to ensure the service performance of electro-hydraulic valve casting, it has high requirements for valve casting.
The casting of electro-hydraulic valve casting is a kind of high-strength and high-precision ductile iron with complex structure, which belongs to high-end hydraulic casting. The casting of electro-hydraulic valve casting has the characteristics of complex structure, uneven wall thickness and high requirements in terms of tissue uniformity, compactness, deformation, dimensional accuracy and surface quality. In order to achieve large-scale mass production, casting production processes such as machine core making, automatic molding line and green sand molding are usually adopted. Due to the characteristics and casting production methods of electro-hydraulic valve castings, problems such as core making difficulty, hole defects in the inner part of valve castings, deformation in the assembly and use process of electro-hydraulic valve appear in the development and mass production of valve castings.
(1) for the slender and curved sand core, the process of multi nozzle combined with the design of exhaust on the core box at the key position is adopted, and the coated sand with high strength, low gas generation and good fluidity is selected, which not only ensures the forming of the sand core, but also meets the strength of the sand core;
(2) by analyzing the structure of electro-hydraulic valve casting, the reasonable riser size, placement position and exhaust system are designed, and the internal hole defects of complex valve casting are successfully solved;
(3) for the core sand in the complex inner cavity of the electro-hydraulic valve casting, the difficulty of oil channel sand cleaning is solved and the surface quality of the oil channel of the valve casting is ensured by dipping and coating the high-temperature anti sticking sand coating on the sand core, vibrating core removal and shot peening in the inner cavity;
(4) during the melting process, the strength and hardness of the electro-hydraulic valve casting are improved and the problem of valve body sticking is solved by pre-treatment of molten iron, adding an appropriate amount of Cu alloy, silicon solid solution strengthening and other measures;
(5) the valve casting of the electro-hydraulic valve has passed the production and use verification for more than 5 years, and the quality of the valve casting is stable. The process scheme has been popularized and applied to a variety of similar valve castings developed in recent 5 years, and obvious good results have been achieved.
ZHY casting adopts advanced equipment such as automatic static pressure molding line. Through many process improvements, it finally solves the problem of electro-hydraulic valve casting and realizes the production stability of valve casting quality.