Analysis Of The Meshing Impact Of Involute Gear Effected By Backlash

With the development of science and technology, people are increasinglydemanding on the properties of mechanical equipment. Gear transmissionsystem is used widely, its performance directly affects the performance of thewhole mechanical system. In general, due to the need of lubrication, and theerror of manufacture, processing, installation as well as the abrasion in theprocess of using, the backlash in gear exists. But in the actual working condition,the gear system maybe work under the fluctuation of load or the frequentstarting and braking, thus due to the existence of backlash, the contact betweenthe gear will change, leading to the repeated impact, the detachment of teeth,and the twice contact, which have the adverse effects on the dynamiccharacteristics of gear system. Therefore, establishing finite element model ofgear with backlash according to the actual production condition and researchingthe meshing impacts of involute gear with backlashs are of great significance toimprove the performance of mechanical transmission system.Based on the comprehensive analysis of the backlash theory, the meshingimpact of involute gear with backlashs analyzed by using ANSYS/Ls-dynafinite element analysis software. Six groups of different conditions on the spur and helical gears respectively are simulated and analyzed. The speed of thedriving wheel and driven wheel are extracted by LS-PREPOST software, andthe results are analyzed and compared. At the same time, the change of stressand the time history of the maximum equivalent stress of the meshing gear withbacklash are compared, and the meshing impacts of gear with backlash arestudied in detail, and the time of gear detachment by extraction of meshingimpact force data is analyzed.Through studying the various aspects, we come to the conclusion. With thebacklash changing, the average speed, the fluctuation cycle and the amplitude ofthe speed of the driving gear change a little, but the driven gear changes moreobvious. No matter what kind of working conditions, the maximum equivalentstress is near the tip of gear. With the increasing width of backlash, the impactprocess will be delayed. Although the maximum mesh force of spur gear andhelical gear are increasing with the increasing width of backlash, in low speed(3r/s), the maximum mesh force increases slightly and the backlash has littleeffect on the maximum mesh force. Energy assembled in multiples of gearmeshing frequency zones, so we should avoid the multiples of gear meshfrequency in the design of gear. The backlash seriously affects the detachmentof gear, especially at the spur gear with0.5mm backlash in low speed, and thistime is only accounted for53%of the engagement time. Through analyzing thedynamic characteristic of meshing gear with backlash, this paper not onlyprovides a method to study the nonlinear dynamic characteristics of gear, but also shows that the gear backlash should be strictly controlled in actualproduction.