Meshing Characteristics Analysis Of Intersected Beveloid Gears Used In Marine Gearbox With Small Down-Angle

The research subject of the thesis stems from the subtopic “Key Technologies andthe Industrialization of the Marine Gearbox” which belongs to the project “The study ofkey technologies of high-speed heavy-duty precise transmission”(2006BAF01B07-02)in the National Science and Technology Pillar Program during the Eleventh Five-yearPlan Period of China.High-speed marine gearbox with small down-angle can meet the requirements ofahead running for vessels by using intersected involute beveloid gears. However,theoretically, the main disadvantage in intersected axis application is the contact path ispoint-wise which tends to cause lower transmission efficiency, lower duration, highernoise and vibration and serious wear problems, limiting the bearing capacity seriously.For above-mentioned, considering the line contact condition, based on the structuralcharacteristics, the spatial gearing theory, geometry design methods, the precisionmanufacturing theory and meshing characteristics of intersected involute beveloid gearsare investigated which has great practical values and industrial significance. The maincontents of this thesis are shown as follows:①On the basis of spatial gearing theory, the meshing theory of pitch cone designfor intersected beveloid gears used in marine gearbox with small shaft angle isdeveloped. Based on mechanical design theory and gear meshing theory, consideringthe factors including undercutting phenomenon, pointing phenomenon, toothinterference phenomenon and non-backlash meshing, the modification coefficients ofbeveloid gears are calculated. By the hobbing theory, a rack cutter is used to generatethe beveloid involute gears and the corresponding Matlab GUI program is written togenerate the gear surface point set. Combined with Pro/E, the3-dimentional solid modelof beveloid gear is created.②The correct meshing conditions for beveloid gears are proposed. The TCAmodel is built based on the tangent contact conditions to research the influences ofprofile-shift coefficients, shaft angle error and axial position error on the contactpath.The formulas to transform point contact to line contact are derived and theinfluences of geometrical parameters on first principal directions (FPD) angle areresearched. According to the length of practical mesh line, the research on contact ratio and the influence of design parameters on contact ratio are investigated.③The3-dimension assembly model and finite element model for intersectedbeveloid gears are built by Pro/E and Abaqus, respectively. The meshing characteristics,influences of shaft angle and FPD angle, loads, shaft angle error and axial position erroron contact pattern, contact force contribution and transmission error, are researched.④On the strength of the down-angle marine gearbox test rig, the experimentalstudy on the meshing characteristics of intersected beveloid gears are performedthrough the loaded tests. The practical contact pattern is obtained which compares wellwith the theoretical results, validating the theoretical research method.