1. Casting structure analysis
The size of the impeller body casting is φ660×22 mm, the weight of the casting is 105 kg, the center wall thickness of the casting is 22 mm, and the blade wall thickness is 21 mm. There is a big hot spot in the center of the casting. The casting has 6 blades with twisted curved surfaces. Using the traditional core assembly process, each blade needs at least two sand cores to assemble, and the entire casting requires at least 12 sand cores. After assembling the sand cores and pouring, a large number of flashes will be generated in the gap castings, which is difficult to polish, and it is easy to polish the blade The transition of the curved shape is not smooth, which affects the performance of the impeller components. The material of the casting is tentatively set to QT500-7. The large wall thickness difference of the casting requires quick pouring, and the internal shrinkage cavity and shrinkage porosity casting defects are easy to occur.
2. Design of pouring system
Considering the structural characteristics and material characteristics of the impeller body castings, the need for rapid pouring, and the feeding and shrinking of thick and large hot sections, two top risers are designed for pouring and feeding, and the bottom surface of the center hot section is chilled with cold iron to achieve Process plan for sequential solidification. There is a thick cylindrical structure with a thickness of 180 mm in the center of the casting. Simulation verification with a single top riser feeding design scheme found that the riser body is very large, and the diameter of the riser neck is almost close to the central cylinder. When people enter the riser, such a large riser directly sets up on the large heat section, resulting in a larger man-made hot section, overheating in the center, and a large riser that causes the metallographic structure of the root of the riser to be coarse, and subsequent removal of the riser is difficult. Taking into account the requirements of fast pouring, if the inner gate is designed for each blade, firstly, the inner gate is set to cause the blade shape to be irregular, and secondly, the molten iron enters the cavity with serious turbulence, and subsequent cleaning will cause the blade grinding problem.
Based on these unfavorable factors, two small risers are designed on the top surface of the central cylinder, which are used as feeder risers. The two risers are not in the center of the cylinder, which can reduce artificial hot spots, and subsequent removal becomes easier, and at the same time, they are in the center. The bottom surface of the cylinder is provided with chilled iron for chilling to achieve sequential solidification of the thick and large parts; secondly, the foam ceramic filter block is set on the upper part of the two small risers as the runner, and the foam ceramic filter block can be used to filter and comb flow slowing effect. Pouring the molten iron filter block into one riser may be damaged. Set up the filter block in the two top risers, and use another riser after pouring for a period of time in one riser.
Simulations verify that shrinkage and shrinkage are transferred into the riser. Although there are some shrinkage and shrinkage at the root of the riser neck, according to past experience, the riser is overheated due to direct pouring from the riser. These shrinkage and shrinkage can be introduced. In the riser.
With 30 years of shot blasting experience, we offer efficient solutions to boost productivity, reduce costs, and maximize your benefits!
Phone Number(whatsapp)
+8618765972210
cassie@besttechmachinery.com
