# Pattern and Analysis of Corrugation-Sand Retaining Seals for
## 1 Introduction  
The cone bit is a commonly used rock breaking tool in petroleum drilling engineering, and its working life affects drilling efficiency and cost. Field use data shows that the main reason for the failure of the cone bit is the early failure of the sealing system; therefore, the seal is the key to determining the life of the high-speed cone bit, and the entry of abrasive media is the main reason for the failure of the seal. Improving the wear resistance and working life of the sealing system has become an important issue that needs to be solved urgently in current oil drilling projects. At present, the most common applications for roller cone bit bearing seals are radial seals and metal seals [1, 2]. For the radial seal ring, the structural design, improvement, and failure research are mainly carried out through theory, simulation, and experimental research on the sealing performance, and the purpose is to improve the life and reliability of the seal [34]. O-ring is the most widely used. Based on O-ring, researchers have improved the structure [5, 6], the sealing performance [7], and life to a certain extent [8, 9]. The failure mechanism, sealing performance, and wear capacity of the sealing ring were studied by means of theoretical calculation and other methods [10, 11], and the corresponding improvement methods were proposed [12, 13]. Different sealing rings have different sealing characteristics, but the problem of high temperature failure cannot be solved [14]. Therefore, bimetallic seals are designed, and its heat resistance is better than rubber seal. The researchers improve its sealing performance through structural optimization and material improvement [15, 16]. However, because it takes up a large space, it will have a certain impact on the strength of the bearing. In response to this problem, the researchers designed a single metal seal [17, 18]. The single metal seal has a simple structure, small volume, andfew components [19; 20]. Therefore, many scholars use theory, simulation, and experimental research methods [21; 22] to study the effects of factors on the metal sealing performance, such as high rotation speed, rubber compression, contact pressure, structural form, structural parameters, materials, grease, assembly form, etc. [23; 24], then optimize and improve the structure to improve sealing performance, service life, and drilling efficiency [25]. Although the existing sealing research results are more significant, the design concept of dynamic sand retaining structure has never been applied in the field of cone bit sealing, and the sealing mechanism of sand retaining structure in other fields is completely different from this paper. Therefore, the sand retaining structure proposed in this paper is distinctively innovative. The traditional seal has no sand-retaining structure specially designed. When mud particles enter the gap and cannot be discharged, they will cause wear and premature failure. Therefore, it is necessary to make breakthroughs and changes in the seal design concept and type, and increase the sand retaining structure in order to effectively solve the wear problem. This paper proposes a corrugated special-shaped sand retaining sealing structure for roller cone bits based on the idea of \"sand retaining\", as shown in Figure 1a. The main functional structure of the new type of sealing ring is a corrugated main seal and a sand retaining flap auxiliary seal. The two parts are an integral structure, which can save space and ensure the strength and safety of the bearing. The main seal is responsible for preventing the mud medium from entering the bearing system. The cross-section of the contact with the bearing is corrugated in the circumferential direction, reducing the contact area, and can introduce grease into the seal gap to form a lubricating oil film, reducing wear and heat generation (as shown in Figure 1b). The tip of the sand retaining flap is in contact with the bearing, and the angle is acute.