The so-called “cloud points” data refers to the three-dimensional data of the real object measured by various methods in the process of reverse design. When displayed on the computer screen, the image composed of dense three-dimensional data points is like a cluster of clouds, so it is vividly called “point cloud”.
Data acquisition, also known as the digitization of parts, is to obtain the geometric coordinate data of discrete points on the surface of parts through specific measuring equipment and methods, and carry out the modeling, evaluation, transformation and manufacturing of complex surfaces on this basis. Data acquisition methods are mainly divided into three categories: contact, non-contact and destructive. The representative equipment are CMM, optical scanner and tomography respectively.
Point cloud acquisition plays an important role in reverse modeling. The quality of point cloud directly affects the accuracy of 3D modeling. Because the tooth surface of spiral bevel gear is relatively complex, the contact method is difficult to measure, slow and error is large, the cost of destructive measurement is high and resources are wasted. Therefore, the non-contact measurement is adopted, the measurement speed is relatively fast, there is no need to measure point by point, the measurement area is large and the data is relatively complete. Here, exascan non-contact three-dimensional laser scanner produced by Canadian Creaform company is used to scan spiral bevel gear. The accuracy of the scanner can reach 0.5% 2 mm, which works on the principle of optical triangle.
Due to the complex shape of the scanned part, the data of all faces cannot be scanned at one time. It is necessary to scan the scanned part for many times from different angles, and finally splice the scanned point cloud data.