# Pattern and Analysis of Corrugation-Sand Retaining Seals for
## 5 Structural Optimization
### Optimization Results
#### 5.3.3 Comparison of Results before and after Optimization  
1. Comparison of structural parameters. The thickness of the base body of the new type of sealing ring has an impact on the leakage of the main seal and the sand retaining performance of the sand retaining flap, but it is not the main influencing factor. Therefore, the leakage and sand retaining performance need to be comprehensively considered in the design to achieve the best performance of the special-shaped seal ring. Here, the thickness of the sealing substrate is 5.5 mm. In order to achieve the minimum leakage of the main seal, the inner diameter margin of the main seal and the height of the main seal arc protruding from the base should be the maximum value, and the groove inner diameter interference should be the minimum value, however, in order to ensure that the seal ring can withstand pressure fluctuations, take the inner diameter margin of the main seal as 0.4 mm. In order to make the contact gap between the tip of the sand flap as small as possible, the inner diameter margin of the sand flap should be 0.4 mm, the angle of the tip of the sand flap should be the maximum 45\({}^{\circ}\), and the angle between the tip and the bearing should be the minimum 20\({}^{\circ}\). Therefore, the key structural parameters of the special-shaped sealing ring and their corresponding values are shown in Table 4.  
2. Stress comparison. Figure 12 is the stress comparison before and after the optimization of the special-shaped seal ring. As shown in Figure 12a, the maximum local stress before optimization is 7.7738 MPa at the main seal. As  
Contact pressure comparison. Figure 13 is the comparison of the contact pressure before and after the optimization of the special-shaped sealing ring. As shown in Figure 13, the peak of the contact pressure of the seal is basically located in the main contact area of the main seal. The contact pressure before optimization is 19.213 MPa, and after optimization is 14.742 MPa, the contact pressure before optimization is greater than the contact pressure after optimization, but in the case that the sealing can be achieved, the smaller the contact pressure, the less prone to failure of the sealing ring, and the easier it is to form a lubricating liquid film to improve the lubrication state. The contact position of the seal base and the cone also has a certain amount of contact pressure, which is beneficial to fix the relative position of the sealing ring and the cone, prevent the sealing ring and the cone from sliding with each other, and avoid the second dynamic seal pair. In general, the optimized contact pressure distribution of the main seal of the special-shaped seal ring can meet the sealing requirements and is more conducive to the formation of the lubricating liquid film. 4 Comparison of the contact gap between the tip of the sand retaining flap. Figure 14 is a comparison of the contact gap between the tip of the sand retaining flap before and after the optimization of the special-shaped sealing ring. As shown in Figure 14, the contact gap is 0.00019479 mm, a decrease of 95%, the abrasive medium is separated from the main seal components, which can greatly reduce the wear of the main  
Figure 12: Comparison of stress: (**a**) Before optimization, and (**b**) Optimized. Figure 13: Comparison of contact pressure: (**a**) Before optimization, and (**b**) Optimized. seal. The contact gap of the sand retaining flap has been greatly reduced, and the theoretical performance of the sand retaining flap has been greatly improved. 5 Performance comparison. The performance indicators of the new seal ring before and after optimization are shown in Table 5.  
After the parameter optimization of the seal ring structure, the leakage of the main seal of the seal ring is reduced by 85%, and the effect is obvious. From a numerical point of view, the leakage amount is 43 mg/h, and the oil storage bag of the cone bit can be used to supplement the reserve of about 25 g. In theory, it takes 580 h for the grease to run out.