基于DLP 3D打印成型技术的研究

发布时间：2018-08-14 20:01

【摘要】：3D打印技术主要应用于航天航空行业、食品行业、汽车工业、医疗行业等领域。近年来,牙科3D打印在医疗行业中成为热门,因此本文选择面向牙科的3D打印快速成型技术进行研究。常用于牙科3D打印的快速成型技术主要有以下四种:FDM技术、SLA技术、PolyJet技术和DLP技术。FDM技术的缺点是成型物体精度低,成型速度较慢、打印机结构精度要求高、对喷头温度的要求也很高,此外,打印材料需要在喷头中高温熔融,会产生刺激性气味气体;SLA技术的缺点是需要专用的实验环境,成型后需要进行二次固化等后处理,激光管寿命短(3000小时左右,价格昂贵),成型时间较长,使用的原材料有限;PolyJet技术的缺点是耗材成本较高、对打印机的结构精度要求非常高;DLP技术是以高分辨率的DLP投影仪来固化液态的光聚合物,每次固化一个层面,步进电机带动滑杆向下移动一个距离,直至打印完整个三维物体。与前三种成型技术相比,DLP技术最大的优点就是成型速度快,精度高。前三种成型技术采取的是由点到线,再到面,最后到三维物体,而DLP技术则是直接成一个面,再到三维物体,因此成型速度快。对于DLP技术来说,投影仪的分辨率越高,成型精度就越高。尽管该成型技术可使用的打印材料较少,但是对于在牙科上的应用来说,目前MED610这款打印材料就足以满足需要,所以影响并不大。通过对上述四种成型技术的比较,本文选取了成型速度快、精度高的DLP技术来实现假牙、牙模、牙套等物件的3D打印。本文设计的基于DLP成型技术的3D打印机主要由DLP投影系统、打印机服务器、步进电机控制系统、步进电机套件、成型套件五个部分组成。其中DLP投影系统是基于DLP投影仪进行改进的,通过HDMI接口连接到打印机服务器,用于传输3D模型图像信息,使其投影到成型平台上固化液态打印材料成型;打印服务器是基于树莓派3B平台构建,它是本文设计系统的核心部分,用于客户机访问上传3D打印文件并控制打印机其他组成部分工作,完成打印任务;步进电机控制系统是基于Arduino Mega2560的平台搭建,通过USB转串口连接打印机服务器,用于控制步进电机的运动;步进电机套件是由步进电机、螺杆、导轨三部分组成,主要是当接收到步进电机控制系统的信号时,带动成型平台在成型槽内运动。成型套件包括成型平台与成型槽,用于固定3D打印物体和液态打印材料。步进电机控制系统、步进电机套件、成型套件共同组成打印机的机械系统。为了提高成型精度和成型速度,本文基于DLP投影仪来搭建验证实验平台,具体步骤如下:第一,对该投影仪的光学系统进行优化,基于柯拉照明系统的原理,将光源所成的像与投影镜头重合,使得像面边缘光照度更接近中心光照度,提高成型精度;第二,设计梯形光积分器,增强紫外光照能量,缩短固化时间,提高成型速度。结果表明,与改良光学系统前相比,DLP成型精度(0.05mm)要高和成型速度(0.013mm/s)要快。通过最后实验结果可知,研究这种成型速度快、精度高、结构简单、成本低廉的3D打印机可以运用于牙科方面。
[Abstract]:In recent years, dental 3D printing has become a hot topic in the medical industry. Therefore, this paper chooses the dental 3D printing rapid prototyping technology to study. SLA, PolyJet and DLP technology. FDM technology has the disadvantages of low precision, slow speed, high precision printer structure and high temperature requirement. In addition, printing materials need to be melted in the nozzle at high temperature, which will produce irritating odor gas. SLA technology has the disadvantages of special experimental environment, forming. After secondary curing and other post-processing, the laser tube life is short (about 3000 hours, expensive), molding time is long, the use of raw materials is limited; PolyJet technology is a shortcoming of high cost of consumables, the structural accuracy of the printer is very high; DLP technology is a high-resolution DLP projector to solidify liquid photopolymer, every time. Compared with the former three molding technologies, the DLP technology has the advantages of fast molding speed and high precision. For DLP technology, the higher the resolution of the projector, the higher the molding accuracy. Although the molding technology can use fewer printing materials, but for dental applications, the current MED610 printing material is enough to meet the needs, so the impact is not great. Comparing the four molding technologies mentioned above, this paper chooses the DLP technology with high molding speed and precision to realize the 3D printing of denture, toothmold, sleeve and other objects.The 3D printer based on the DLP molding technology designed in this paper mainly consists of five parts: DLP projection system, printer server, stepper motor control system, stepper motor suite and molding suite. The DLP projection system is improved based on the DLP projector, which is connected to the printer server through the HDMI interface to transmit the 3D model image information and make it projected onto the molding platform to solidify the liquid printing material molding; the printing server is based on the raspberry pie 3B platform construction, which is the core part of the design system in this paper, used for the transmission of 3D model image information. Client accesses and uploads 3D printing documents and controls the other components of the printer to complete the printing task; stepper motor control system is based on Arduino Mega2560 platform, connected to the printer server through USB serial port, used to control the movement of the stepper motor; stepper motor suite is composed of stepper motor, screw, rail three parts The forming kit includes the forming platform and the forming slot, which are used to fix 3D printing objects and liquid printing materials. The mechanical system of the printer is composed of the stepping motor control system, the stepping motor kit and the forming kit. In order to improve the precision and speed of forming, this paper builds a validation experiment platform based on DLP projector. The concrete steps are as follows: Firstly, the optical system of the projector is optimized. Based on the principle of Cora illumination system, the image formed by the light source is overlapped with the projection lens, which makes the edge illumination of the image closer to the center illumination and improves the forming precision. Secondly, a trapezoidal light integrator is designed to enhance the ultraviolet light energy, shorten the curing time and improve the molding speed. The results show that the DLP molding accuracy (0.05mm) is higher and the molding speed (0.013mm/s) is faster than that before the improved optical system. 3D printers can be used in dentistry.
【学位授予单位】：南方医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.73

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