CLOG RESISTANT PRINT HEAD METHOD FOR HIGH SPEED CEMENTITIOUS MATERIAL 3D PRINTING

摘要

An Advanced Additive Construction device to extrude layers of cementitious material consistently and accurately with an anti-clogging method is disclosed. The device introduces low continuous frequency sonic vibrations with frequency range of 20- to 10000 Hz to slow cement or binding agents from curing the mixture inside the extruder and to get rid of air bubbles trapped in the mixture. Buildup of early cured mixtures inside the extruder tract especially in large volume or long period prints result in accumulation of material inside the extruder tract which causes extruder clogging. A shaker plate coupled with four miniature shakers excite the material mixture inside the extruder orthogonal to the inner casing direction. Furthermore, four more miniature shakers equipped with extension rods excite the material mixture inside the extruder orthogonal to the top mount, thereby preventing any cementitious material sticking within the extruder casing and around the central flight auger. Moreover, increasing the print speed and flow rate of the extruder by 60% which results in cutting the print time to more than 70% when counting the elimination of clogging. Also, it allows the extruder to accommodate a wider range of cementitious mixtures without the need to adjust admixtures and setting times especially for mixtures that have a rapid setting rate. The shaker's vibrating system, FIG. 7, functions within the upper chamber of the extruder casing, the upper chamber has the largest diameter as it operates as a flow control reservoir, which has less pressure compared to the lower chamber of the extruder. The vibrating rods and inner wall system prevent cementitious material from sticking to the extruder inner walls and allows smooth continuous flow of material.