China
Africa
Explore chapters and articles related to this topic
Research on the optimization of the numerical control machine in engraving
Published in Fei Lei, Qiang Xu, Guangde Zhang, Machinery, Materials Science and Engineering Applications, 2017
Xiao-Yue Liang, Jiao Zheng, Su Wang
The high-speed feed unit consists of a powerful and large-stroke linear servo motor and a working table driven by the motor. It is one of the most important parts of the superhigh-speed machine, whose main advantages are: High feed speed; the linear motor’s real highest speed is 50–180 m/min.High acceleration; the linear motor’s highest acceleration is (1–8)g (g = 10 m/s2).Steady transmission; there will be no mechanical transmission part between the linear motor and the machine working table. The magnetic force pushes the working table to move. As a result, the feed motion is steady, fast, and of low noise, high rigidity, and high accurate positioning.High start push force; at present, the highest push force of linear motor has already reached 1200 N. In theory, there is no limit of the push force of the linear motor. Therefore, more powerful processing abilities will result.At present, several linear motors for splicing technology have reached a very high level that can meet the levels of superlong stroke machine tools (such as high-speed rail grinding machine).Increased servo response speed. In order to save the intermediate link as belt, chain, and screw components, it is important to enhance the response performance of the whole closed-loop servo system.Increased transmission accuracy. In order to reduce the lead screw transmission lag caused by the tracking error, and the negative feedback control with high-precision linear displacement transducer, it is necessary to improve the positioning precision of the machine tool significantly.
Control analysis and experimental investigation of a multi-coil moving coil linear motor based on an improved bacterial foraging algorithm
Published in Systems Science & Control Engineering, 2018
Gong Zhang, Zheng Xu, Zhichen Hou, Qunxu Lin, Jimin Liang, Songsong Liang, Jian Wang, Youhao Li, Weijun Wang
A linear motor (LM), converting the electromagnetic energy into mechanical energy reciprocating linear motion continuously and proportionally, is regarded as the most widely employed linear motion mechanism in various industry driving fields. Basically, it could be classified into moving iron linear motor (MILM) and moving coil linear motor (MCLM) by the moving part (Goll & Kronmuller, 2000; Takezawa et al., 1998). At present, an MCLM is receiving increased attention for use in applications requiring linear motion at high speed and high accuracy for its smaller hysteresis and higher linearity (George & William, 2000; Ruan, 2013; Zhao & Tan, 2005). The generated electromagnetic force is about 1.5 times higher than the others with the same size (Tanaka, 2000; Zhang, Yu, & Ke, 2007).
A review of electro-hydraulic servovalve research and development
Published in International Journal of Fluid Power, 2018
Paolo Tamburrano, Andrew R. Plummer, Elia Distaso, Riccardo Amirante
In addition to two-stage servovalves, direct drive servovalves are also constructed by manufacturers. The actuation is achieved through linear force motors; direct current flows in a coil producing an interaction with a magnetic field generated by rare earth magnets. Force motors have lower moving mass and larger driving forces than proportional solenoids and are more linear, and thus have better performance as far as response speed and chip shear force are concerned. The maximum force exerted by a linear motor is of the order of 200 N (Moog 2017).
40 K single-stage split-type Stirling cryocooler
Published in International Journal of Ambient Energy, 2022
Fayaz H. Kharadi, A. Karthikeyan, Bhojwani Virendra
Stirling cycle cryocooler due to high coefficient of performance (COP) are most preferred Cryocooler technology. The Stirling cryocooler works on Stirling cycle, which is a closed thermodynamic cycle. It consists of four processes, namely isothermal compression, isothermal expansion and constant volume heat addition and constant volume heat rejection. The Stirling cycle cryocooler utilise valve-less linear compressor. In valve-less linear compressor, moving coil linear motor (top pole piece, bottom pole piece and magnet arrangement) is used to give linear motion to the piston in the cylinder. This arrangement eliminates mechanical linkages essential for converting rotary motion into linear motion as it directly produces linear motion. Stirling cooler is preferable over other system due to its high operating speed and pressure which directly enhance the cooling capacity. The high operating speed and pressure reduces the specific mass (mass of cooler per unit cooling capacity). The linear motors used in Stirling cryocooler are either moving magnet or moving coil type. The moving coil linear motor has the advantage over the moving magnet type of lesser inertia forces involved in moving the coil (Dang 2015). Therefore, in this set up, moving coil motors were used. The Neodymium-Iron-Boron (Nd-Fe-B) material was used for the magnet. Those materials have high energy density which directly affects the power of linear motor. As the working fluid helium gas was used (Walker 1983). To maintain the piston to its mean position during the operation, a stack of flexure bearing was used. The flexure bearing is a circular flat metallic disc on which spiral arms are cut for flexing. The radial clearance between the piston and the cylinder bore is maintained by these bearings which increase the service life of the cryocooler. To seal and suspend the piston in the cylinder, Caughley et al. (2016) used a pair of metal diaphragms in Stirling cryocooler. Wang et al. (2016) developed a two-stage high capacity Stirling cryocooler for cooling high-temperature superconductor devices in which the concept of free piston supported by flexure bearing was used. The leakage increases with increase in clearance between the piston and the cylinder bore over a period of time. As leakage increases, it lowers pressure ratio developed by the compressor and thus drastically bring down the cooling capacity of the cryocooler. For that purpose, the piston of compressor and displacer is coated with Rulon. To estimate the operating and geometric parameters of the present cryocooler, thermal analysis proposed by Atrey (1990) was used.