Abstract: Existing laser honing machines all utilize the motion mode of workpiece movement. But as to complex workpiece, this mode is inappropriate to use. For example, cylinder liner, pre-casted into the engine block, is not suitable to rotate when fixed on the chuck, because the block is irregular and heavy. This equipment uses the mode of laser head rotation and linear motion. The workpiece keeps still during the laser texturing process. In this paper, the structure design and control principle of the laser machine are narrated in detail. The process of the machine is a new method of laser micro-texturing, named as “single-pulse interval of the same point many times”. The method contributes to processing microscopic or macroscopic morphology and significantly reduces the negative thermal effects of laser processing
Abstract: 0.85(Na0.5Bi0.5)TiO3-0.144(K0.5Bi0.5)TiO3-0.006BaTiO3(NBT-KBT-BT) lead-free piezo -electric ceramics were prepared using conventional solid state method. The influence of La2O3 doping amount on the crystal phase, surface microstructure and properties of the NBT-KBT-BT lead free piezoelectric ceramics were investigated using X-ray diffraction(XRD), Scanning electron microscopy(SEM) and other analytical methods. The results show that La2O3 has diffused into the lattice of NBT-KBT-BT ceramics. Consequently, a pure perovskite phase is formed. SEM images show that the microstructure of the ceramics is changed with the addition of a small amount of La2O3, La2O3 doping can make grain growing. The piezoelectric strain constant(d33) starts increasing and then decreasing, the dielectric constant(εT33/ε0) increases continuously and the dielectric loss(tanδ) starts increasing and then decreasing and then increasing when La2O3 doping amount increases. When the doping amount of La2O3 is 0.4wt.% and the sintering temperature is 1160°C, the NBT-KBT-BT piezoelectric ceramics with good comprehensive properties can be obtained. Its piezoelectric strain constant(d33), dielectric constant(εT33/ε0), and dielectric loss(tanδ) are 151pC/N, 1543 and 4.2%, respectively.
Abstract: This paper presents a new method of laser focusing used in the process of direct laser fabrication. The hollow laser beam is achieved by transmission and conversion, which is studied by modeling and analysis in this paper. The defocus distance Z must be regulated in order to fabricate clad layers with good quality. The relationship between laser focal spot and the defocus distance was investigated. The focusing laser was solid when the absolute value of Z was equal to or smaller than while hollow on the other focal planes with different defocus distances, and the diameter of the minimum focusing spot is .
Abstract: Laser Shock Processing (LSP) is a kind of new surface hardening technology, which can increase fatigue life obviously. Due to the LSP, the residual stress is generated and dislocations increase obviously in the surface of specimen, so the fatigue life of specimen processed by LSP increases. Thanks to the finite element programs, it is able to simulate the fatigue life. The simulation of fatigue life has important significance, which not only can reduce the costs of fatigue test and research, but also further study the effect of LSP on fatigue life. The results of fatigue test coincide with the results of simulation.
Abstract: Three-dimensional crack propagating path of tire bead rubber was the premise to study the crack propagation direction of bead. For this reason, Jmax Criterion was put forward. Utilized J integral maximum (Jmax) to determine the crack propagation direction of rubber. Calculated J-integral values of different preset directions by Abaqus built-in algorithm, obtained J (θ) curve which showed the Jmax and direction angle (θ) by fitting simulation data. Using Abaqus to set up two different crack model of bead rubber and simulate the crack propagation path, the results was consistent with the real crack propagation direction of specimen test, validated the applicability of Jmax Criterion..
Abstract: In the laser marking process system, a liquid crystal display (LCD) was used as the image mask, which can display dynamically and flexibly the various images by the programmable control. A nanosecond pulsed laser (1064nm) was applied to investigate the characteristic of laser photolithography fabrication technology. The light modulation function of LCD mask was firstly discussed by theory. By observing the graphics morphology with a high-powered optical microscope, it was found that the graphics of laser marking with LCD mask shows that its edges were not ablated but its line inside was ablated. According to analysis, the reasons of this phenomenon are due to the opaque lattice effect and the high light transmittance of black pixel. Results showed that the light modulation function of LCD mask was decided by adjusting the light transmittance with controlling the pixel voltage and a complete graphics was ablated in the range of 0.6J/cm2 ~ 0.8J/cm2.
Abstract: Programming of graphical interaction and modular structure are adopted in this wire cutting machine software by analyzing the structure of DXF file, picking out the part’s outline information in Visual C++ 6.0, and combining the manufacture conditions in this paper. The NC codes are obtained which are consistent with the high-speed cutting machine processing system automatically. This system software greatly facilitates the process of high speed cutting machine, shortens programming time and improves the accuracy of the programming.
Abstract: Aiming at the current situation that there is lacking in-depth study on applications of virtual technology in mechanical manufacturing and assembly process control, the virtual assembly systems was researched and designed based on combining virtual reality technology with mechanical assembly process. The support mechanism of virtual assembly platform was designed based on taking shaft parts as example, and modeling method of 3D features parameters was adopted in order to build the model of virtual assembly parts, which was modeled according with the sequence as describing physical feature parameters of parts, building data structure of feature parameters and building model features library. On the basis of modeling virtual assembly platform, the key technologies of realizing the virtual assembly processing, which was from positioning issue and collision detection issue, were also analyzed, and control methods of virtual assembly processing were pointed out in detail. All is work is significative for enhancing the level of virtual technology applications, digital machinery manufacturing and assembly.
Abstract: For the modeled engine, the soft AVL-BOOST is applied to do the single-dimensional cycling simulation and calculation. And then the engine performance after assembling the improving limiter（its diameter is 20mm） is analyzed. According to the calculation and analysis, the torque and pneumatic efficiency are largely affected by limiter, the maximum torque and pneumatic efficiency decreases 20 percents and 30 percents respectively. The limiter not only improves the engine’s fuel performance, but also reduces its power performance.
Abstract: In the experiment, we use pulsed laser to conduct discrete scratching on Ni-containing stainless steel protective coatings to test residual stress situation after the matrix is scratched; then to analyze the the impact of the impact stress wave on coating - substrate bonding strength according to the test results, finally to infer the laser power density range within which it occurs coating failure. The study shows that: after laser discrete scratching, the residual stress of the center of the laser-loaded point on matrix surface gradually reduces when the pulsed laser power density increases. The matrix produces a corresponding residual compressive stress under the laser power density reaches a certain value. The actual failure threshold values are 12.006 GW/cm2, 11.829GW/cm2 and 12.193GW/cm2 measured by the three-dimensional topography instrument testing the discrete scratch point of three groups of samples and verified by using a microscope