Critical Techniques Of Image Processing For Dimensional Measurement Of Hot Forgings

As the key parts for the manufacture of heavy or large mechanical equipments, heavy forgings are widely used in the national key projects, however the manufacture of heavy forgings involves with some problems, such as high production cost, and over-consumed energy. At the same time the in-time dimensional measurement of the heavy forging during the production plays an important role to the improvement of manufacturing process, enchantment of quality qualification and the saving of energy. However, the extreme situations in the workshop and high temperature radiation of the hot forging carry difficulty to the dimensional measurement on-line. Considering the negative factor during the measurement under high temperature, the on-line dimensional measurement method is studied with the structure light technology. The research conducted in this paper is listed as follows:(1) Considering the outline of cubic forgings, light stripes projected on the surface of cubic forging is studied with the characteristics of light stripes and cubic forgings under high temperature; then the feature points in image is extracted in high accurate level by the light model established for the dimensional measurement of cubic forgings with vision technology; therefore, the dimensions of the cubic forgings are calculated with the method above.(2) With the feature lines used in the dimensions obtained process proposed by the research team, the skew distributed light stripe mode that suitable for the gray distribution of light stripes on cylindrical forgings is established, and also subpixel extrication of center points of light stripes in normal direction is studied. Moreover, with the light stripe projected, the matrix used for the matching of corresponding points in different images is calibrated online to satisfy the visionary dimensional measurement in multiple fields; finally the dimensions of cylindrical forgings are obtained by solving the spatial relationships between the 3D points after reconstruction of the matching points.(3) According to the manufacturing requirements in the forging workshop, software is designed to satisfy the dimensional measurement during the practical production of the hot forgings; at the same time, the two dimensional measurement methods for the cubic and cylindrical forgings are studied with experiments, whose results verify the reliability of the measurement methods proposed in this paper.