Use of reverse engineering methods in the process of restoration of machine parts

Abstract

The paper considers the peculiarities of creating digital copies of objects using reverse engineering technology. The main process used in reverse engineering is the processing of digital copies of objects, which is called photogrammetry. The reverse engineering process consists of the following stages. First, a 3D scan of the product and scan data processing is performed. The received digital data (polygonal mesh) is converted into a CAD file, which can be used to change the shape and topology of the model in accordance with the project. Based on this, an analysis of the two main technologies on which photogrammetry is based was performed: 1) laser triangulation method (laser scanners are used), 2) structured light method (optical scanners are used). The main disadvantages of using laser triangulation when scanning machine parts and methods of reducing their negative impact on the final result are given. The process of determining the position of a point when scanning parts by the laser triangulation method is considered in detail. Equations for normalizing the position of the point and equations that remove the distortion of the point due to the aberration of the camera lens are given. An equation for determining the width of a laser beam is presented, on the basis of which its main geometric characteristics are determined. A general diagram of the influence of the main factors on the quality of the process of scanning parts by the method of laser triangulation is constructed. One of the varieties of scanning objects using structured light is the range imaging (SfM) technique. The SfM technique is a process of estimating a three-dimensional structure from a sequence of two-dimensional images that can be associated with local traffic signals. The position of the camera in space is used to find the x,y,z coordinates of each pixel. An overview of the main software for creating and editing a structured polygonal mesh based on scan data is carried out. As a study of the process of reverse engineering technology, a connecting rod of a car engine was scanned by the SfM method and its digital model was created.