The 3d scanning equipment is used to scan the workpiece and obtain the accurate 3d data of the workpiece. The engineer applied professional software to analyze and decompose the 3d data obtained by scanning, reconstruct the structure of the workpiece, and redesign it according to the customer's requirements.
1. Overview of reverse engineering (reverse engineering).
Reverse engineering is the data acquisition equipment for physical or surface and inner cavity on the surface of the sample data, enter the special data processing software or with data processing ability of 3 d CAD software for processing and 3 d reconstruction, on the computer retrieval physical sample geometry, and on this basis the same copy, modify or redesign, this method is mainly used for surface shape of difficult to accurately express or unknown design method of component reconstruct 3 d shape and design again.
Reverse engineering is a comprehensive very strong terms, it is a design methodology as the instruction, on the basis of the modern design theory, method, technology, using a variety of professional engineering design experience, knowledge and innovative thinking, the existing dissect, deepen, and to create the new product is the design of the existing design, this is the meaning of reverse engineering, with particular emphasis on the creation is the soul of reverse again. The reverse engineering is mainly composed of three parts, namely, the digitization of the physical geometry of the product, the reconstruction of CAD model, the manufacture of products or molds.
2. Reverse engineering (reverse engineering) production process.
The key techniques in reverse engineering are data acquisition, data processing and model reconstruction.
Step 1: digitize the parts.
The 3d coordinate values of the original surface points of parts are usually obtained by measuring devices such as CMM or optical scanner. For example:
The physical model is placed on the scene and the 3d scanner is put into the field for preparation. Surface pretreatment, paste mark point, frame photography positioning measurement framework.
The camera positioning system will be tested by the unknown marking point of the surface of the object. Through the trig calculation method, the coordinate values of the known points in AICON Software are calculated and the coordinate values of the unknown points are calculated. The coordinates of the unknown points obtained from the calculation are output in 3DS or TXT file formats.
Open the 3d scanner special scanning software OPTOCAT, and mark the coordinates of 3ds or Txt. Using the Reference Indexs Matching mode scan in the OPTOCAT software, the coordinates of the whole model are based on the same coordinate, so the accuracy of obtaining point cloud is improved and the efficiency of obtaining point cloud data is improved.
The second part: the geometrical characteristics of the original shape of parts extracted from the measurement data.
According to the geometrical properties of the measured data, the design and processing characteristics of the parts are obtained by means of geometric feature matching and recognition.
The difficulty of extracting geometric features is very high for engineers. In particular, software proficiency, relevant technical industry experience value. If there is no relevant industry experience, it can also be used to extract the geometrical features, take time and energy, reduce work efficiency, and extract quality of features. The following steps:
The point cloud data obtained by the 3d scanner is imported into the professional reverse engineering software to carry out the pre-processing of point cloud data. It mainly filters the excess noise points and reduces the early stage of the data guarantee feature. The basic construction method is to construct the characteristic curve by extracting the feature point cloud. Because the 3d scanner gets sufficient point cloud data, in order to obtain the characteristics of the object being tested, some excessive point cloud data will be obtained in the process. Extracting feature points is necessary to extract features quickly.
General extraction feature point cloud, some experience. It is best to extract the characteristic point cloud data of intersecting cross. Because the basic principles of reverse engineering design are:
The body of point, line and plane
According to such design rules, it is necessary to pay more attention to the extraction of feature points cloud, and analyze how to make the feature point cloud connection into the characteristic curve.
The cross - phase cross feature curve is constructed, and two - phase cross curves are selected to complete the surface feature extraction. At this point, the first feature surface is extracted successfully. The characteristic surface is composed of UV direction control line. UV control curve of the order number can be set by instruction (control the higher the order number, adjust the surface of the numerical approach and theory, the surface characteristics of the adjustment work has increasingly responsible for), the general setting adjustment order UV for the 4 order. The adjustment speed is fast, the adjustment surface area is smooth. The higher order mass of the characteristic surface can be changed and the continuity of the surface is better.
To adjust the feature surface, you need to jump the whole point cloud data. As shown in the figure, the extracted high order surface is the red region, and the original point cloud data is the light blue region. By adjusting the UV direction control point, the surface is matched with the actual point cloud data. When adjusting the UV direction control point, it is necessary to refer to the actual point cloud data. Only the extracted high order surface is close enough to the actual point cloud data, and the distance error between the high order surface and the actual point cloud is guaranteed to be within 0.02mm.
As shown in the figure above, only when the red surface and pale blue original point cloud data overlap, the extracted high order surface is the best. At this time, the higher order surface, the deviation distance between the actual point cloud and the actual point cloud is within 0.02mm, and the high order surface extraction is completed. The higher order surface is extracted by analogy one by one, and the original point cloud data is completely replaced by the efficient higher-order surface.
Part iii: reconstruction of parts prototype CAD model.
In CAD system, the three - dimensional data are fitted together, and the CAD model of the original surface of parts is obtained through the intersection and splicing of each surface film.
The high order surface extracted by professional reverse engineering software is exported to 3d modeling software. In the software such as UGS, Proe, Catal and Solidworks, the high order surface is edited.
Because only entity format data can be applied to actual production and processing. So, this step is not necessary. In the modeling software, high order surface stitching function can be used to control the high order surface and realize the construction of the solid model.
For symmetric models, mirror production is generally adopted.
So far, the company has for the automotive manufacturing, shipbuilding, aerospace, mold manufacturing, machinery processing, shoes, mobile phone manufacturing, dental and orthopedic, protection of cultural relics, university education and scientific research and so on various types of enterprises and institutions to provide nearly ten thousand times the service project.
For EnvisionTEC, 2017 is a busy year because it has introduced many new 3D printing materials, including engineering grade materials E-CE, E-Poxy and E-Flex Flex; a series of new bioprint materials and FDA approved dental 3D printing materials. The company also launched a series of new 3D printers, including large versions of the Perfactory and cDLM 3D printers, and a new Vida cDLM 3D printer for the dental market.
Recently, EnvisionTEC introduced the new Vida cDLM 3D printer. It is reported that the 3D printer is the largest of the company's existing equipment and is still based on the company's continuous digital light manufacturing (cDLM) technology.