The results show that the size of the cylinder block is qualified and there is no obvious defect on the surface. The wall thickness of the cylinder bore is uniform, and the wall thickness difference is less than 1.0 mm. The metallographic structure and mechanical properties of the important area of the castafter pouring and cooling were observed and tested.
Cut and sample the important area (middle crankshaft connection) of engine block iron castings, as shown in Fig. 1. Grind the sample and observe its graphite morphology and length under the high power optical microscope, as shown in Fig. 5.8; the observation results are shown in Fig. 2; and the tensile strength is tested on the finished material testing machine, as shown in table 3.
The graphite state at the connection of the crankshaft in the middle of the cylinder block is A-type, the graphite length is 100-150 μ m, the size is small, the distribution is relatively uniform, and there is no obvious graphite block; the tensile strength is 247.50-248.30mpa, and the tensile strength is high. It meets the casting technical requirements of cylinder body.
The reason is that the closed and open gate design can well control the uniform and reasonable distribution of casting temperature. It has the advantages of both closed and open type, easy to exhaust and stop slag, and has a strong inhibition effect on casting defects; the top duck beak long neck riser can realize the effective feeding of casting by using the partial self feeding characteristics of the casting itself, and ensure the internal group of the cylinder body iron castings The tensile strength of the casting increases with the compactness of the fabric and the fineness and homogenization of graphite.
According to the structural parameters of the selected typical cylinder block iron castings, the digital design of the gating and riser technology and the casting pouring of the typical cylinder block iron castings were completed by using the digital gating and riser process system as a tool. The test results of metallographic structure and mechanical properties of cylinder block iron castings were revealed through experimental research, and the superiority of digital gating and riser system was verified.