The rock-breaking efficiency of a drilling tool directly affects the production costs and progress of foundation construction. It is essential to understand the mechanism of mechanical rock-breaking to improve rock-breaking efficiency. In this study, dynamic rock-breaking simulation research was carried out on a drill bit and was based on the LS-DYNA simulation platform. Additionally, the influence of the rotational speed of the spindle and the feed rate on the force of the drill bit in the rock-breaking process was obtained. The influence of the rotational speed of the spindle and the feed rate on drill vibration was also analyzed. The content of the presented theoretical and simulation research was verified through experiments. The following conclusions were drawn: first, the reaction force that rock has on the drill bit presents a law according to different rock types and drilling process parameters. With the increase in rotational speed, the axial reaction force decreases. With the increase in the feed rate, the axial reaction force increases. The effect of rock type on axial reaction force is nonlinear. Second, the influence of the spindle rotational speed and feed rate on the vibration of the drill bit also presents a law during rock-breaking. When the feed amount is constant, the transverse vibration slows down, and the axial vibration intensifies as the rotational speed increases. When the rotational speed is constant, as the feed increases, the transverse vibration slows down and the axial vibration intensifies. The research results provide a theoretical basis for selecting drilling process parameters and for improving rock-breaking efficiency.

Welded metal bellows are commonly used in mechanical sealing devices. Its properties directly affect the sealing effect, and thus it is very important to study its stress–strain for a high reliability. In this study, to explore the stress–strain state of the diaphragm of welded metal bellows under axial force, based on the elastic mechanics, S-shaped welded bellows of single-layer (SL) and double-layer (DL) with small diameters (D1, size 60 mm) and large diameter (D2, size 95 mm) were used as materials. ANSYS Workbench was used for simulation, and a digital image correlation (DIC) method was carried out for experimental validation. The results of finite element analysis (FEA) showed that the greater the compression, the greater the strain. The DIC analysis showed that the strain increased with the increase of the amount of compression. However, the diaphragm of DL metal bellows showed a lower stress than that of the SL metal bellows. Moreover, the strain of S-shaped welded bellows at larger-diameter was less than at small-diameter. This trend applied to single and double layers. In some layers, the strain showed abrupt changes. The Principal strain was 0.02563 at P6 position of SL-D1 and 0.01333 at P8 position of DL-D1 with compression at 5 mm; while with compression at 4 mm, the Principal strain was 0.0841 at P8 position of SL-D2 and 0.00182 at P6 position of DL-D2. In conclusion, the resistance to elastic deformation of double-layer S-shaped welded metal bellows is better than that of single-layer. Moreover, this study provides a new idea and method for the strain test of S-shaped welded metal bellows.