Iteration of modification parameters for multi-stage gear transmission system of shearer cutting section

(a) Peak of dynamic engagement force (b) Peak value of meshing tooth direction error

An example is given to show the iterative process of the modification parameters. The tooth profile modification in this study is determined by three parameters: the amount of tooth profile modification, the amount of tooth profile modification and the dimensionless range of tooth profile modification. In order to make the gear modification have better effect of vibration and noise reduction and strong robustness to load changes, this study adopts medium length profile modification. Therefore, there are two undetermined modification parameters: the amount of tooth profile modification and the amount of tooth profile modification. In the iteration process, the modification parameter of the i-generation is denoted as Gen. I, and Gen. 0 represents the transmission system without modification.

(a) Before shaping (b) After shaping

As shown in Figure 1, the limit meshing state of gear pair 2 under the modification parameters of each generation is shown. The specific iterative process is as follows: starting from the transmission system without modification, the first step of this section is to obtain the 0-generation limit meshing state; taking the 0-generation limit meshing state as the input, the first generation (Gen. 1) modification parameters are obtained through the second and third steps of this section; the first generation (Gen 1) The modification parameters are substituted into the system dynamics equation, and the first step is repeated to obtain the ultimate meshing state; then the Gen. 2 modification parameters are obtained by taking the Gen. 1 Ultimate meshing state as the input, and so on. The difference between the third-generation and the second-generation modification parameters is less than 2%, so the iteration process is ended.

(a) Before shaping (b) After shaping

Finally, the third generation modification parameters are applied to the shearer cutting part. After the modification, the contact area of the tooth surface moves from the edge of the tooth to the middle of the tooth, and the peak stress decreases from 1541 MPa to 1185 MPa, as shown in Figure 2. The peak value of dynamic meshing force of gear pair 2 after modification is also significantly reduced, as shown in Fig. 3. The peak value of contact stress and dynamic load coefficient of each gear pair in the cutting part after modification are shown in Fig. 4. The average decrease of peak value of contact stress of each gear pair is 21.1%, and the average decrease of dynamic load coefficient is 25.5%.

(a) Variation of peak value of contact stress (b) Dynamic load coefficient variation