Optimization design of two-stage amplification micro-drive system without additional motion based on particle swarm optimization algorithm

With the increasing requirements of precision mechanical systems in electronic packaging,ultra-precision machining,biomedicine and other high-tech fields,it is necessary to study a precision two-stage amplification micro-drive system that can safely provide high precision and a large amplification ratio.In view of the disadvantages of the current two-stage amplification and micro-drive system,such as poor security,low motion accuracy and limited amplification ratio,an optimization design of a precise symmetrical two-stage amplification micro-drive system was completed in this study,and its related performance was studied.Based on the guiding principle of the flexure hinge,a two-stage amplification micro-drive mechanism with no parasitic motion or non-motion direction force was designed.In addition,the structure optimization design of the mechanism was completed using the particle swarm optimization algorithm,which increased the amplification ratio of the mechanism from 5 to 18 times.A precise symmetrical two-stage amplification system was designed using a piezoelectric ceramic actuator and two-stage amplification micro-drive mechanism as the micro-driver and actuator,respectively.The driving,strength,and motion performances of the system were subsequently studied.The results showed that the driving linearity of the system was high,the strength satisfied the design requirements,the motion amplification ratio was high and the motion accuracy was high(relative error was 5.31%).The research in this study can promote the optimization of micro-drive systems.

Influence of positive DC electric field on rime icing on the insulator and its experimental verification in the natural environment

The electric field imposes a significant effect on ice accretion on the insulator.The impact of an AC electric field on insulator icing in an artificial climate chamber has been addressed.Compared with AC,DC electric field exerts an attraction on supercooled water droplets,which is more detrimental to the power system.Moreover,the icing on energised insulators is rarely studied in the natural environment.In the present research,an electrical,fluid coupled‐field simulation was carried out on the insulator.The force characteristics and motion deviation features of water droplets at different positive DC electric field strengths were studied.On this basis,rime icing on the insulator energised with different positive DC voltages was investigated in the field.Results show that the charged droplet shifts along the electric field line under a positive DC voltage.The deviation degree of the droplet increases with the increment of the voltage and droplet size and decreases with an increase in wind speed.As the voltage rises,the surface roughness,icing amount and icing length of rime ice‐covered insulator increase.Consequently,compared with that without energisation,the local collision coefficient,icing amount and icing length increase by 17.6%,46.4%and 63.9%,respectively,under a 40 kV DC voltage.

An automated approach to calculating the maximum diameters of multiple cutters and their paths for sectional milling of centrifugal impellers on a 4_(1/2)-axis CNC machine

Power generators and chemical engineering compressors include heavy and large centrifugal impellers. To produce these impellers in high-speed machining, a 4?-axis milling machine(or a 4-axis machine plus an indexing table) is often used in the industry, which is more rigid than a5-axis milling machine. Since impeller blades are designed with complex B-spline surfaces and impeller channels spaces vary significantly, it is more efficient to use multiple cutters as large as possible to cut a channel in sections and a blade surface in patches, instead of only using a small cutter to machine a whole blade and a channel. Unfortunately, no approach has been established to automatically calculate the largest diameters of cutters and their paths, which include the indexing table angles. To address this problem, an automated and optimization approach is proposed. Based on the structure of a 4?-axis machine, a geometric model for a cutter gouging/interfering the impeller is formulated, and an optimization model of the cutter diameter in terms of the indexing table angle is established at a cutter contact(CC) point on a blade surface. Then, the diameters of the tools,their orientations, and the indexing table angles are optimized, and each tool's paths are generated for machining its corresponding impeller section. As a test, an impeller is efficiently machined with these tools section by section; thus, this approach is valid. It can be directly used in the industry to improve efficiency of machining centrifugal impellers.