Patent ID: 11945026
Assignee: NANJING UNIVERSITY OF AERONAUTICS AND ASTRONAUTICS
Field: Materials, metallurgy (Chemistry)
Classification: CPC B | IPC B

Claim 0:
1. A multi-path internal microporous efficient refrigeration method for a frozen sand mold, implemented by a multi-path internal microporous efficient refrigeration device, wherein the multi-path internal microporous efficient refrigeration device comprises a frozen sand molding chamber, an electric lifting platform, a frozen sand mold refrigeration device box, an ultrasonic generator, and a low-temperature refrigeration system, wherein the frozen sand molding chamber is located inside the frozen sand mold refrigeration device box and a bottom of the frozen sand molding chamber is arranged on the electric lifting platform; the frozen sand molding chamber comprises a polytetrafluoroethylene (PTFE) porous lining and a removable porous aluminum plate; and an ultrasonic piezoelectric sheet is located between the PTFE porous lining and the removable porous aluminum plate and fixed at a bottom of the PTFE porous lining;
wherein the method is suitable for rapid freezing and auxiliary cutting processes of the frozen sand mold, and specific implementation steps comprises:
S1, selecting suitable molding sand according to characteristics of a casting, and measuring 3%-8% of water by weight into a sand mixer, followed by uniform mixing for 2 to 10 minutes to prepare water-containing green sand;
S2, starting the electric lifting platform to ensure that the frozen sand molding chamber is located at an upper limit position; laying prepared green sand grains in the frozen sand molding chamber, starting the ultrasonic generator and selecting a low frequency to vibrate and compact a sand mold; inserting iron wires along through holes of the PTFE porous lining to form vent holes following an arrangement law on a frozen sand billet; starting the electric lifting platform again to ensure that the frozen sand molding chamber is located at a lower limit position;
S3, starting the low-temperature refrigeration system, mixing low-temperature gas with nitrogen through a one-way valve to form a low-temperature mixed gas, delivering the low-temperature mixed gas to a condenser tube loop through a pressure regulating valve for cyclic refrigeration, enabling the through holes of the PTFE porous lining and the removable porous aluminum plate to quickly enter a core of the sand mold, and freezing the frozen sand billet; and
S4, when an internal temperature of the frozen sand mold reaches a preset temperature, opening a sealing cover plate, selecting to open the electric lifting platform, and taking out the frozen sand mold; or placing an entire frozen sand molding device on a platform of a digital forming machine for digital cutting forming to ensure that strength and hardness of the frozen sand mold satisfy efficient cutting forming; after the core of the frozen sand mold reaches the preset temperature, starting the lifting platform to facilitate demolding of the frozen sand mold, and placing the frozen sand mold on the digital forming machine for milling after being taken out.