The components of an automobile steering gear are shown in Figure 1. The sand casting has complex structure, many processing and assembly holes, and the sand casting mass is 34 kg. The traditional casting adopts the method of investment casting for trial production and production. Investment casting needs to go through the processes of wax pressing, wax trimming, tree assembly, slurry dipping, wax melting, pouring and post-treatment, The shell making process needs 3 ~ 5 times of repeated work to reach the state of semi-finished products, and the production cycle is long. In the trial production stage of auto parts, the time cycle determines the finished product cycle of final sand casting, and in the process of R & D and trial production of new sand casting, the sand casting structure, process scheme and other links need to be modified many times. When 3D printing is used for production, the whole process is shortened to sand mold design (computer), sand mold printing, pouring metal liquid and post-treatment, which greatly shortens the production cycle. Moreover, the 3D printed sand mold file is a digital file directly output by the computer, which is convenient to modify, more flexible to change the process, and can quickly respond to the change speed, so as to achieve the purpose of rapid trial production.
As shown in Figure 2, the parts of an automobile engine require high dimensional accuracy and complex structure. Considering the reasons for energy saving and efficiency improvement of sand casting of the final assembly switchboard, there are many weight reduction structures of sand casting. In the traditional manufacturing process, this sand casting adopts the method of metal model and hot core box core making. It is difficult to modify the mold production cost of 200000 to 500000 yuan per mold production cycle. Therefore, in the trial production and R & D stage of sand casting, the advantages of fast 3D printing response, high dimensional accuracy and low batch cost of single piece are prominent, which can well solve all the needs in the verification stage. Until the sand casting is fully verified and reaches the finalized state, the metal model can be made for mass production, so as to save a lot of R & D costs for the enterprise, Speed up the research and development progress to improve the competitiveness of sand casting enterprises.
