Top-down 3d printer and 3d printing method

A 3D printing method, for controlling a top-down 3D printer, wherein the top-down 3D printer comprises a workbench, a light device, a first drive mechanism, a second drive mechanism, a scraper, a printing platform, a resin vat, a laser displacement sensor and a liquid level adjustment mechanism, wherein the light device, the first drive mechanism, the second drive mechanism, the scraper, the printing platform, the resin vat, the laser displacement sensor and the liquid level adjustment mechanism are disposed on the workbench;

• wherein an output end of the first drive mechanism is connected to the printing platform, the first drive mechanism is configured to drive the printing platform to move up and down in a height direction of the workbench, an output shaft of the second drive mechanism is connected to the scraper, the second drive mechanism is configured to drive the scraper to move up and down in the height direction of the workbench and drive the scraper to rotate around the output shaft of the second drive mechanism, the output shaft of the second drive mechanism is parallel to the height direction of the workbench, the laser displacement sensor is configured to monitor a liquid level of resin in the resin vat, and the liquid level adjustment mechanism is capable of feeding resin to or extracting resin from the resin vat;
• and
• the light device, the second drive mechanism, the scraper, the printing platform, the resin vat and the liquid level adjustment mechanism are arranged at intervals from top to bottom in the height direction of the workbench;
• the 3D printing method comprising:
• controlling a printing platform to acquire resin from a resin vat;
• controlling a scraper to rotate by a preset angle in a first rotation direction from a first initial position to flatten resin on the printing platform, making a thickness of resin on the printing platform to be a preset layer thickness;
• controlling the scraper to move up by a first preset distance;
• allowing the top-down 3D printer to stand for a preset standing duration;
• controlling a light device to expose a printed picture;
• acquiring a liquid level of resin in the resin vat;
• determining whether the liquid level of resin in the resin vat is within a preset liquid level range;
• and
• in response to determining that the liquid level of resin in the resin vat is within the preset liquid level range, simultaneously controlling the scraper to return to the first initial position and controlling the printing platform to acquire resin again from the resin vat;
• in response to determining that the liquid level of resin in the resin vat is not within the preset liquid level range, simultaneously controlling the scraper to return to the first initial position, controlling the liquid level adjustment mechanism to adjust the liquid level of resin in the resin vat to be within the preset liquid level range and controlling the printing platform to acquire resin again from the resin vat.