Tooth Root Strength of Spur and Helical Gears Manufactured With Gear-Shaper Cutters

At the beginning of gear transmission design, mainly simplified methods of gear strength analysis based on ISO or AGMA standards are used. However, they allow for calculation of approximate and sometimes biased stresses. Moreover, ISO standard is generally focused on using racks for gear manufacturing. A method proposed in this paper allows for computation of the parameters of critical section, strength coefficients $YF$⁠, $YS$⁠, and tooth root stress $σF$ according to the procedure from ISO standard also in the case of machining gears with gear type tools. The proposed improvement of ISO standard leads to replacement of real gear tool with rack with substitute tip radius $ρa0*$⁠. The developed method maintains basic assumptions and advantages of ISO standard, including its simplicity. Simultaneously, it allows for computing the maximum tooth root stresses $σF$⁠: (i) very close to results of accurate geometric analysis and finite element analysis, and (ii) much closer, compared to conventional ISO procedure, to results obtained using AGMA standard.