Study Of On-machine Measuring Principle And Technology Of Large Gear Based On Straight Generatrix Family Deviation

As important base part of large-scale equipment, large gear is applied more and more widely. With the development of advanced gear manufacturing technology, higher measuring precision is therefore required. After analysis and comparison of domestic and foreign measuring principle and technology of large gear, following conclusions were drawn: it's impossible to precisely measure large-scale gear with table-type measuring instrument; with on-top measuring device, the measuring precision can not be guaranteed because of the poor positioning accuracy. The effective method to solve such problems is on-machine measurement. This technology is just what to be researched in this thesis.Based on the principle of differential geometry, the malleability of involute tooth profile is researched. The typical curve families such as involutes family, straight generatrix family, helix family, and contact trace family are analyzed. The deviation of these curve families has direct influence on the accuracy of gear transmission. Here, taking medium rack as the tool, the engagement principle of involute gear for parallel axes and engagement principle for crossing axes are researched respectively, which is the theory basis of the thesis.According to the new national gear standard, three deviation-measuring items must be included in the checkout of single gear: profile deviation, helix deviation and pitch deviation. Because pitch deviation measuring technology is very mature, the main research objective of this thesis is laid on the checkout of profile deviation and helix deviation. After research of involute helicoids characteristic lines measuring theory and technology, straight generatrix deviation on-machine measuring theory and technology project with rack-shaped-edge probe is first put forward. Through measuring every deviations of straight generatrix family on tooth profile, measuring grids are ensured. Measuring data are then processed and the tooth profiledeviation and helix deviation are thus separated, which the error-separating mathematical model for the tooth profile deviation and helix deviation is established based on straight generatrix deviation. In the thesis, the key technologies of on-machine measuring large gear, such as the signal collection of precision linear displacement and angle displacement, installation and adjustment of the device on the machine, and the determination of measuring coordinate system, are studied in detail. Precision analysis was also done.After the design of the mechanical part of on-machine measuring system, the control part is also studied in the thesis. The field application has shown that the principle is correct and the technology is feasible.