影响黏土3D打印性能的主要参数研究

针对影响以黏土作为原材料的小尺寸3D打印性能的主要参数(包括含水率、打印线速度和打印层高)进行了全面研究,并通过试验确定在不同条件下黏土浆体的打印性能,包括浆体流动性、可挤出性、可堆积性等。试验首先研究3D打印系统中挤出压力与浆体挤出速率的关系,根据二者关系调节气泵压力来控制挤出速率。分别改变黏土含水率、打印线速度、打印层高等影响参数,进行黏土的3D打印,并对打印试件进行流变试验,观察试件的成型情况,测量打印试件的相对偏差,分别用于评估黏土浆体的流动性、可挤出性和可堆积性。结果表明:最适合3D打印的黏土含水率为34%～35%,相比于黏土的液限高出3%～4%; 最佳打印线速度为4～5.5 mm·s^-1; 最佳打印层高为1.4～1.8 mm,约为喷嘴直径的1倍～1.3倍; 打印参数的设置既要考虑打印材料的特性,又要考虑打印系统的特点,各参数取值还应当受质量守恒定律的约束; 进行黏土3D打印试验时,在确定打印机喷嘴尺寸后,应当率先确定黏土的含水率,随之确定打印系统的线速度、层高、挤出速率和挤出压力等参数。

Study on Main Parameters Affecting 3D Printing Performance of Clay

The main parameters affecting small-scale 3D printing with clay as raw material(including moisture content, printing linear speed and printing layer height)were comprehensively studied. The printing properties of clay paste under different conditions were determined through experiments, including flowability, extrudability, and buildability of clay slurry. Firstly, the relationship between extrusion pressure and slurry extrusion rate in 3D printing system was studied, and the extrusion rate was controlled by adjusting the air pump pressure according to the relationship. The influencing parameters of clay moisture content, printing linear speed and printing layer were changed respectively to carry out 3D printing with clay. The rheological test on the printing specimen was carried out, the forming condition of the specimen was observed, and the relative deviation of the printing specimen was measured, the results were used to evaluate the flowability, extrudability and buildability of clay slurry respectively. The results show that the moisture content of clay most suitable for 3D printing is 34%-35%, which is 3%-4% higher than the liquid limit of clay. The best printing line speed is 4-5.5 mm·s^-1. The best printing layer height is 1.4-1.8 mm, which is about 1-1.3 times of the nozzle diameter. The setting of printing parameters should consider not only the characteristics of printing materials, but also the characteristics of printing system. The value of each parameter should also be constrained by the law of mass conservation. During the 3D printing test of clay, after determining the nozzle size of the printer, the moisture content of clay shall be determined firstly, and then the parameters such as linear speed, layer height, extrusion rate and extrusion pressure of the printing system shall be determined.