Clean pneumatic conveying shield, mold replacement system for expanding machine and replacement method

A clean pneumatic conveying shield, comprising:

• a shield body (1) used for picking up an expanded material from an expanded material discharge port and pneumatically conveying the expanded material to the next process and provided with a hollow closed inner cavity, an outlet pipeline (2) positioned in the middle of the top of the shield body and communicated with the inner cavity of the shield, and at least two inlet pipelines (3) positioned at the top of the shield body, arranged around the outlet pipeline and communicated with the inner cavity of the shield, wherein the shield body is provided with a splitter plate (4) corresponding to each inlet pipeline and capable of rotating, an upper partition plate (5) positioned above each splitter plate and a lower partition plate (6) positioned below each splitter plate;
• when each splitter plate is rotated to be connected with the upper partition plate and the lower partition plate corresponding thereto, a conveying airflow channel communicated with the inlet pipelines and the outlet pipeline and capable of carrying and conveying the expanded material through the expanded material discharge port is formed in the shield body in a dividing manner;
• when each splitter plate is rotated until all the splitter plates are intersected, a short-circuit airflow channel communicated with the inlet pipelines and the outlet pipeline and bypassing the expanded material discharge port is formed in the shield body in a dividing manner.