& nbsp; Low pressure casting process is a casting method that lies between pressure casting and gravity casting. Its basic principle is to introduce dry compressed air into a holding furnace containing liquid metal, which acts on the metal liquid surface at a certain temperature, causing the liquid metal to enter the sand mold cavity from bottom to top along the riser. After the metal liquid fills the cavity, the pressure is increased, and the gas pressure on the liquid surface is maintained until the casting is completely solidified, Then relieve the pressure and allow the unsealed metal liquid in the riser and runner to fall back into the holding furnace, completing a casting process. Obtain the required castings after unpacking. & nbsp; The sand mold low-pressure casting equipment consists of two parts: an insulation furnace and a liquid level pressure control system. The insulation furnace cover is used as the working platform for the sand box, and the shaped sand box is directly fixed on the insulation furnace cover for pressure casting. & nbsp; The operation process is as follows: The operator will lift the sand mold that has been shaped and closed onto the working platform of the insulation furnace, and after achieving docking and sealing with the liquid lifting pipe mouth, start pressurized pouring to achieve fully automatic casting and pressure boosting processes such as liquid lifting, mold filling, pressurization, pressure maintaining, and pressure relief. Then, the sand box will be lifted off the working platform and the parts will be unpacked. & nbsp; The liquid level pressurization device adopts an imported proportional valve and high-precision pressure sensor to achieve pressure detection and real-time closed-loop feedback control in the insulation furnace, with PID adjustment method. It has functions such as multi-level linear pressurization, automatic tracking and setting of pressurization process curve, insulation furnace leakage compensation, and liquid level compensation. High pressure control accuracy and good repeatability ensure the stability and consistency of the low-pressure pouring process. Especially in response to the characteristics of sand mold low-pressure casting, such as the easy occurrence of metal liquid flushing and sand contamination in the mold cavity, the performance requirements of the liquid level pressure control system in sand mold low-pressure casting are very high. It is necessary to completely eliminate the shaking phenomenon of the liquid level during the filling process, and the filling must be stable, the filling rate must be constant, the pressure control must be accurate, and ensure the accurate repetition and reproducibility of the pressurization process parameters. Only in this way can the yield of castings be effectively improved& nbsp; & nbsp; The control system uses a computer as the upper monitoring and management computer, running the monitoring and management software independently developed by Haomai, with a fully Chinese standard Windows interface, which is easy to operate. By using database technology, all data of the pressurization process is saved in the database, which can store the actual process data of each casting, and can trace and analyze historical process data, greatly improving the process quality management of production.