In order to further improve the mixing performance of the mixing device, the structure of the agitator was optimized, and the effects of the diameter and pitch of the agitator on the solid-liquid suspension characteristics were analyzed by single factor method. Multiple reference frame (MRF), computational fluid dynamics, Euler multiphase flow model and standard K- ε turbulence model were used to investigate the effect of the height from the bottom of the agitator on the suspension characteristics of particles in the agitator was studied. The results show that reducing the height from the bottom of the agitator can promote the suspension of particles at the bottom of the tank, but too low height from the bottom will easily produce mixing dead zone at the bottom of the tank, and cause the accumulation of particles. Reducing the height of the agitator from the bottom will enlarge the clear liquid area of the flow field, cause uneven particle distribution and increase the stirring torque. With the increase of agitator diameter, the critical suspension speed of the flow field decrease, but the stirring power required by the flow field increase. Increasing the blade spacing in a certain range can promote the suspension of particles and make the distribution of particles in the flow field more uniform. Therefore, the mixing power and the uniformity of particle concentration distribution need to be considered together in order to make the mixing device more efficient and energy-saving.

Chip morphology is one of the evaluation indexes of cutting performance of cutting tools, and chip forming process has a direct and important influence on chip morphology. High-strength steel 40CrMnMo is one of typical oil country tubular goods (OCTG) and difficult-to-cut materials, and its chip morphology represents the machining quality of OCTG. The chip forming process of a new independent-developed microgroove turning tool for turning oil country tubular goods 40CrMnMo is researched, combining machining experiments with theoretical analysis. Research results show that with the increase of cutting speed, the initial radius of curvature of the chip fluctuates slightly, but the overall trend is upward. However, the ultimate radius of curvature decreases and the chip’s radius ratio also decreases. The relative ideal chip can be obtained if the proper cutting velocity and feed rate are given. Chip morphology results from the comprehensive effect of the two processes: The fracture and separation process of the workpiece during passing through the shear deformation zone and the process of curling and breaking away of the chip after passing through the rake face of the tool. The research results have a certain guiding significance for controlling the cutting process of machining the other material with similar performance.