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Casting process 3.1 Casting process characteristics Since all surfaces need to be machined, the shape and position accuracy of the blade casting must be ensured during the casting process. There are several difficulties in the casting process: Traditional casting blades have the following two requirements: ①. The customer needs to provide an expanded view of the section from near to far in the circumferential direction; ②. In the actual production process, make 3-5 graphite rings according to the circumferential radius of the profile development diagram provided by the customer. This parting method is more suitable for small size castings. The advantage of this parting method is that the model has less waste and high utilization rate, but it is not suitable for large castings.

The size of the blades cast in this paper is large. According to this method of casting, the utilization rate of graphite is less than 50%, and the model cannot be reused; due to the structural characteristics of the blade and the uneven thickness of the blade, the cooling speed of each part of the casting is caused. Different, the degree of shrinkage is different, the casting is deformed during solidification; the distance between the furthest part of the blade and the wheel is large, and the riser and the farthest end of the hub cannot form a good feeding channel; the customer only provides three-dimensional A picture, and in actual production and process design, you need to convert the three-dimensional picture into a two-dimensional picture. The structure of the blade surface of the blade is complicated, the measurement positions are many, the accuracy requirements are high, and the spatial position is difficult to determine, which brings great difficulty to the detection. 3.2. Casting process design Traditional casting blade castings are first divided into several circular sections according to the circumferential direction. Then, the cross-sectional view along the circumferential direction is made into a template, and the template is drawn on the graphite type according to the corresponding position, and finally the excess graphite is removed. This parting method is more suitable for the production of small-sized castings. This scheme is not suitable for large-scale blade casting. This blade has a large appearance and a large number of pieces. Considering factors such as cost and human labor intensity, designing a reusable model is the first problem to be solved in the design. After careful discussion and research, the original process was changed to the following method. The original casting process plan of Brass Bushing Sleeve Roller Bearing the impeller The current casting process plan of the impeller In the current process, the original ring-shaped group plan is changed to a combination of rectangular parallelepiped materials.

The size of each rectangular block material is 640mmx440mmx60mm. Rules, each piece of material is easy to choose without waste. Each material is divided into two pieces according to the chamfering and following edges, which realizes the reuse of the model. When making the model, the deformation of the blade during the solidification process was fully considered. During solidification and cooling of liquid alloys, during the solid shrinkage phase (shrinkage from the solidification termination temperature TS to room temperature), the volume shrinkage of the casting is linear with the temperature drop. This relationship determines the size of the "reduced scale" of the casting. See the curve of the volume of the casting with temperature. The liquid shrinkage bookmark1 solid shrinkage TSTL temperature. The curve of the volume of the casting with temperature.

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