Belt tensioning mechanism for 3d printer and 3d printer

A belt tensioning mechanism for a 3D printer, wherein the 3D printer comprises at least one lead screw arranged in a vertical direction and a printing bed sleeved on the at least one lead screw, and the belt tensioning mechanism comprises:

• a base provided with a first sliding groove;
• a driving pulley and at least one timing pulley mounted on the base and connected in series with each other via a belt, wherein the at least one timing pulley is configured to drive the at least one lead screw to rotate under the driving of the driving pulley to enable the printing bed to be raised and lowered along the at least one lead screw;
• a sliding block mounted on the base and capable of sliding along the first sliding groove;
• a tensioning pulley mounted on the sliding block, and connected in series with the driving pulley and the at least one timing pulley via the belt to tension the belt;
• and
• a spring configured to apply an elastic force to the sliding block to make a siding block at a working position within the first sliding groove, wherein at the working position, a tensioning pulley tensions the belt.