Titanium alloy TC4 will have problems such as workpiece deformation and bonding during the machining process, so the processing is difficult. This study used ABAQUS software to create a simulation model. In this paper, the influence of ultrasonic elliptical vibration turning and conventional cutting on the mechanical characteristics of titanium alloy TC4 was compared, and the influence of the cutting speed, tangential amplitude, frequency and cutting depth of ultrasonic elliptical vibration turning TC4 titanium alloy on the cutting force was analyzed. The results show that the average cutting force of ultrasonic elliptical vibration cutting increases with the increase of cutting depth and cutting speed, and decreases with the increase of tangential amplitude and vibration frequency. Compared with conventional cutting, ultrasonic elliptical vibration cutting can significantly reduce cutting force, improve surface machining quality and improve machining efficiency..

The study of ultrasonic variable amplitude rods is an important part of ultrasonic vibration system. The cosine half?period cylindrical composite horn was designed to realize the smooth transition between the cosine section and the cylindrical section. By theoretical calculation, its frequency equation and amplification coefficient equation were derived. The results show that the frequency equation of the new cosine cylindrical composite variable amplitude rod is simpler than that of the cylindrical conical composite variable amplitude rod and the stepped variable amplitude rod; the amplification coefficient equation of the new cosine cylindrical composite variable amplitude rod is similar to that of the stepped variable amplitude rod, which is more concise than that of the cylindrical conical composite variable amplitude rod. Using ABAQUS finite element analysis software, modal analysis of the designed cosine cylindrical composite variable amplitude rod was carried out to determine its inherent frequency and vibration type; harmonic response analysis was conducted to check the feasibility of the theoretical design. The results of the modal analysis and harmonic response analysis show that the performance of the ultrasonic composite variable amplitude rod is optimal when the length of the cosine section is 55 and 60 mm. The research results provide a reference for the design and application of ultrasonic composite amplitude rod.

Nickel?based superalloys, as typical difficult?to?machine materials, are widely used in aerospace engines, chemicals, ships, and other fields. To meet the special working conditions requirements of the aero?engines, and further improve the surface machining quality and processing efficiency, relevant researchers have carried out many theoretical studies and process explorations. The development of nickel?based single crystal superalloys and polycrystalline superalloys, and their material properties were firstly reviewed. Then the main research results of domestic and overseas scholars on the grinding removal mechanism, grinding surface integrity, and process characteristics of nickel?based superalloys were summarized, and their development trends are prospected.

The compliant microgrippers are directly contacted with the gripper in the microoperation field and during microassembly.And as the end microactuator in the micro?operation and micro?assembly system,it plays an important role in realizing micro?operation and micro?assembly tasks.A flexible microgripper mechanism based on straight circular flexure hinge and reed isosceles trapezoidal flexure hinge was studied in this paper.The displacement amplification and parallel displacement of gripper displacement were realized by piezoelectric ceramic driving.The mechanical pseudo?rigid body model of the flexible microgripper was established, and the kinematics model was established by using the pseudo?rigid body model method.Furthermore, the displacement amplification factor was calculated, and the relationship among the input force, input displacement and output displacement was obtained.The finite element method was used to simulate and verify the model.The results show that the prediction of theoretical values is consistent with the simulation results.

In the process of processing GH4169 nickel?based superalloy, serious work hardening would occur, as well as difficult machining problems caused by excessive cutting force. The finite element model of two?dimensional orthogonal turning was established by ABAQUS software. The influence of cutting speed and amplitude on cutting force and the change of tool path of GH4169 ultrasonic elliptical vibration turning were analyzed. The results were compared with those of ordinary turning process. The results show that the cutting process parameters in the ultrasonic elliptical vibration turning of nickel?based superalloys have a significant effect on the cutting force. Choosing reasonable process parameters can effectively reduce the cutting force and improve the machining quality.

Taking the 6?PTRT parallel as the research object, the pose error model of 6?PTRT parallel robot is established, the closed?loop vector method of single branch chain is used to establish the error equation based on its input and output relationship. According to the pose error model of 6?PTRT parallel robot,the mechanism error is converted into the drive rod error,the influence of the error parameters of each drive rod length on the output pose error is analyzed by using MATLAB software;the objective function of pose error correction of 6?PTRT parallel robot is established, and the adaptive weighted particle swarm optimization algorithm based on shrinkage factor is used to optimize the error parameters of each drive rod, modify the terminal pose, and improve the kinematics accuracy, which provides a theoretical basis for the dynamics, pose calibration and trajectory planning and control of 6?PTRT parallel robot.

Finite element analysis software ABAQUS was used to study the process of micro texture PCBN tool turning Cr12MoV, Taguchi method was used to carry out orthogonal experimental design. The variation law of the actual contact area between tool and chip, cutting force and cutting temperature with texture parameters was studied by signal?to?noise ratio analysis method, and the optimal combination of texture parameters was obtained. The results indicate that the actual tool?chip contact area decreases with the increase of texture groove width and texture edge pitch respectively. Texture groove width and texture edge pitch have the most significant influence on cutting performance of the tool; Compared with the non?textured tool, the micro?textured PCBN tool with the optimal texture parameter combination can reduce the cutting force by 5.2% and the cutting temperature by 4.7%.