3D模型创建

3D model creation

由于实现快速成型的系统只能接受计算机构建的产品的三维模型（立体图），然后才能进行切片加工，所以要在计算机上实现设计思想的数字化，即即，将产品的形状、特性等数据输入计算机。目前，快速成型机的数据输入主要有两种方式：

Because the rapid prototyping system can only accept the three-dimensional model (stereogram) of the product built by the computer, and then can carry out slicing processing, it is first necessary to digitize the design idea on the computer, that is, input the shape, characteristics and other data of the product into the computer. At present, there are two main methods for data input of rapid prototyping machine:

一是设计人员利用计算机辅助设计软件（如Pro/Engineering、SolidWorks、IDEAS、MDT、AutoCAD等）根据产品要求设计3D模型，或将现有产品的2D和3D视图转换为3D模型；

First, designers use computer-aided design software (such as pro/engineering, Solidworks, ideas, MDT, AutoCAD, etc.) to design 3D models according to product requirements, or convert 2D and 3D views of existing products into 3D models;

另一种是将现有对象数字化，可以是手工模型、手工艺品，也可以是人体器官。这些物体的形状信息可以通过3D数字化仪、CT和MRI等手段进行采集和处理，然后通过相应的软件将获得的形状信息等数据转化为快速成型机能够接受的输入数据。

The other is to digitize the existing objects, which can be manual models, handicrafts, or human organs. The shape information of these objects can be collected and processed by means of 3D digitizer, CT and MRI, and then the obtained shape information and other data can be transformed into input data that can be accepted by the rapid prototyping machine through corresponding software.

3D模型的近似处理

Approximate treatment of 3D model

由于产品上经常有一些不规则的自由曲面，在加工前必须进行近似。在目前的快速成型系统中，常用的逼近方法是用一系列小三角形平面来逼近自由曲面。其中，每个三角形由3个顶点的坐标和一个法线相量来描述。

Because there are often some irregular free-form surfaces on the products, they must be approximated before machining. In the current rapid prototyping system, the common approximation method is to use a series of small triangular planes to approximate the free-form surface. Each triangle is described by the coordinates of three vertices and a normal phasor.

可以选择三角形的大小以获得不同的曲面逼近精度。经过上述近似处理后的3D模型文件称为STL格式文件（很多CAD软件都提供此功能，如Pro/Engineering、SolidWorks、IDEAS、AutoCAD、MDT等），由一系列相连的空间三角形组成。

You can select the size of the triangle to obtain different surface approximation accuracy. The 3D model file after the above approximate processing is called STL format file (many CAD software provide this function, such as pro/engineering, Solidworks, ideas, AutoCAD, MDT, etc.), which is composed of a series of connected spatial triangles.

典型的计算机辅助设计具有用于转换和输出STL格式文件的接口。但是，有时输出的三角形会有少量误差，需要在本地进行修改。

A typical CAD has an interface for converting and outputting STL format files. However, sometimes the output triangles have a small amount of error and need to be modified locally.

切片3D模型

Slice 3D model

山东快速成型提醒您，由于快速成型是逐层断面轮廓加工的，所以在加工前需要将三维模型沿成型高度方向每隔一定的间隔进行切片，以便提取横截面的轮廓。

Shandong rapid prototyping reminds you that since rapid prototyping is processed layer by layer, it is necessary to slice the 3D model at certain intervals along the molding height direction before processing, so as to extract the profile of the cross section.

间隔的大小根据成型零件的精度和生产率的要求来选择。间隔越小，精度越高，成型时间越长；相当光滑的成型表面。切片间隔选定后，每层叠加的材料厚度应与之相适应。各种快速成型系统都配备了切片软件，可以自动提取模型的横截面轮廓。

The size of the interval is selected according to the accuracy and productivity requirements of the formed parts. The smaller the interval, the higher the precision and the longer the forming time; Fairly smooth formed surface. After the slice interval is selected, the superimposed material thickness of each layer shall adapt to it. Various rapid prototyping systems are equipped with slicing software, which can automatically extract the cross-sectional profile of the model.

这里介绍快速成型的过程之前处理准备的相关内容。您可以访问我们的网站www.metferro.com进行咨询以获取更多信息。

Here are the relevant contents of preparation before rapid prototyping. You can visit our website www.jrjmockup Com for more information.