Research Of The Large Module Gear-rack Bending Fatigue Strength

At present, more and more modulus of larger than50mm gear-rack are used in the drivingsysytem of big equipment at home and abroad. Compared with the conventional geartransmission, although the carrying capacity becomes larger, overload and complicatedengagement relationship between the tooth surface will also lead to large modulus gear-rackfailure. Therefore, in order to ensure the safe and reliable operation of the equipment, it isimportant to research the reasons and forms of large modulus gear-rack failure and calculatethe bending fatigue strength. Compared with traditional gear-rack fatigue strength researchmethod, the research of large modulus gear-rack lacks perfect theoretical and data supportwithin the scope of the national standard. The original calculation model about contact,bending strength of national standard no longer applies to the large modulus gear-rack. Itneeds to modify model or use other methods to calculate the large modulus gear-rack fatiguestrength. So this paper uses the finite element analysis method that has been widely used indomenic and foreign to analyze and calculate the large modulus gear-rack bending fatiguestrength. The main research content includes:1. Taking the large modulus gear-rack designed modulus of62.7mm on the Sanxia shiplift as the research object, and aiming at the limitation of conventional calculation methodused for modulus less than50mm of tooth root bending strength in the GB/T3480-1997, tolearn the idea ‘small push large’ used by the chord measurement method of track inspectioninstrument, which is applied to the theoretical study of the gear-rack. With the idea, it wasfound that the GB method to change the correction factor formula can be applied to thecalculation of large modulus gear-rack tooth root bending strength, what’s more, the paper didthe theoretical calculations of bending strength, what can provide theoretical support for thesimulation analysis of large modulus gear-rack tooth root bending strength.2. Considering the engagement of gear-rack is a dynamic process, Pro/Engineer wasused to establish the three-dimensional model of large modulus gear-rack. With the specialmeshing software HYPERMESH, the model was meshed, and the finite element model generated was imported in ABAQUS to do dynamic simulation analysis. The distribution andsize of the circumferential stress in different engagement position was obtained. Through thecompare between the results of simulation and formula, it was explained that the finiteelement analysis results is correct. Accordingly, the influence of tooth root fillet radius tolarge modulus gear-rack tooth root bending strength was explored, what could be the basis forthe life prediction.3. Aiming at the present situation that the test properties of advanced alloy steelmaterial G35CrNiMo large modulus gear-rack used are lacked, in order to accurately acessbending fatigue life of large modulus gear-rack, the modulus of10mm gear-rack bendingfatigue test is intended to be done. Before that, the related test methods were studied,specifically including, the bending fatigue testing gear-rack fixture were designed and used, adetailed test program was formulated, what can provide guarantee for the smoothdevelopment of the bending fatigue test.