There are few publications on the dynamic model of double helical gears considering axial vibration. In the present dynamic model, it is thought that the axial force of the left and right ends generated by tooth meshing can offset each other. Because of the existence of manufacture and installation, the axial force of the left and right ends cannot completely offset which will cause the axial vibration. In this paper, a dynamic model of double helical gears is proposed. Firstly, the calculated model of axial displacement caused by the errors of manufacture and installation under low speed is proposed. Secondly, the dynamic model of double helical gears considering axial vibration and backlash is built. On this basis, the dynamic equations of this system are established and solved. Finally, a pair of double helical gears is taken as an example. The axial displacement is calculated out and compared with that from the experiment. The dynamic behaviors of double helical gears are studied.

Using optical microscopy, electron backscatter diffraction and transmission electron microscopy, the static recrystallization (SRX) mechanisms of ZK 60 magnesium alloy was examined under twin-roll-cast and hot compression (TRC-HC, 350 °C/0.1 s-1) and subsequent annealing (1000 second at 250-400°C). The static recrystallization (SRX) mechanisms, such as grain boundary migration (GBM), grain boundary bulging (GLB) and subgrain rotation (SGR), were discussed.

A three-dimension discrete element model of the shot blasting machine has been established to study the principles of shots flow motion in shot blasting machine. The three-dimension discrete element method (EDEM) was used to analyse the shot-motion process inside the shot blasting machine. The dynamic law of shots motional process inside shot blasting machine was shown through simulation.

The effect of austenitizing temperature on the quenching microstructure and properties of 51CrV4 steel was studied. The results show that with the increase of austenitizing temperature, the austenite grains grow gradually. After quenching, the hardness increased first and then decreased, and the strength increased first and then decreased after tempering at 460°C. When the austenitizing temperature was 880°C, the austenite grains were fine and uniform, about 16μm, the martensite structure was dense, the strength and hardness reached maximum. When the austenitizing temperature was 910°C, the decarburization phenomenon was obvious, and the strength, hardness and plasticity of the test steel decreased obviously. When the austenitizing temperature exceeded 910°C, the austenite grains grow sharply and some grains were abnormally coarse. The austenite grain size reached 20μm and the microstructure was coarser at austenitizing temperature of 950°C. Therefore, in order to ensure uniform grain size and no decarburization under the premise of complete austenitization, the best austenitizing temperature of 51CrV4 steel for good properties is 880°C.

In this research, graphite has been found to have excellent tribological properties as a lubricant additive. To reduce high friction and wear in cylinder liner piston ring friction pairs, modified flocculent graphite have been prepared via chemical technology. The morphology and microstructure of modified flocculent graphite were investigated via SEM, EDS, XRD and IR. In this study, varying concentrations (0.1, 0.5, and 0.9 wt.%) within modified flocculent graphite were dispersed at 350 SN lubricant for Gasoline Engine. Suspension stability of the lubricating oils with modified flocculent graphite and graphite as determined by ultraviolet-visible light (UV-VIS) spectrophotometry. The friction and wear characteristics of lubricants containing materials of modified flocculent graphite were evaluated under reciprocating test conditions to simulate contact. The morphology and microstructure of the friction pair tribofilms produced during frictional contact were investigated via SEM, EDS and a 3D surface profiler. The results show that scratching, pits, furrows and adhesive wear took place, respectively, on the worn surfaces of friction pairs. But, modified flocculent graphite showed excellent friction reducing and anti-wear performance and subsequently has great potential for the application of anti-wear.