Thread Detection Software System Based On Laser Displacement Detection Technology Design And Development

By analyzing the feature and difficulty of traditional thread screw parametersdetection methods, this paper proposes a multi-parameter technical system based onlaser probing technique to realize the non-contact detection of screw threads. Thesystem consists of a laser displacement sensor with triangle laser method,3-coordinatemeasuring machine, rotating platform, computer and software for screw threadsdetection, which is able to detect some parameters, such as major diameter, pitchdiameter, minor diameter, pitch, half of thread angle and so on.The possibility is analyzed that fast Fourier transform algorithm is used todetermine whether contour data of the screw threads is valid; digital filter with zerophase error will filter the valid contour data; the valid contour data is analyzed with firstorder regression to get crest data, flank data and root data; crest data, flank data and rootdata will be divided into smaller data segments, and unary linear regression algorithm isadopted to select data segment with the smallest variance to describe the screw threadmathematical model; some parameters, such as major diameter, pitch diameter, minordiameter, pitch, half of thread angle and so on, are calculated by their definitions.The software for screw threads detection is developed based on the same principleunder Microsoft Visual Studio2010. The operator can control the system to scancontour of the screw threads with this software, and the software will calculate majordiameter, pitch diameter, minor diameter, pitch and half of thread angle. These threadparameters calculated will be compared with parameters from screw threads standarddatabase. This result would be the basis to judge thread is qualified or not.Factors that may impact the result of screw threads detection are analyzed, anderror compensation measures are taken to ensure detection accuracy.