Abstract: Microcantilever hotplates use the self-heating phenomenon to achieve the required large, uniform temperature field or the cantilever-tip movement. The present study investigates the effect of self-heating on temperature and its distribution in microcantilever hotplates in monolith and u-shape configuration with different substrate materials, operating environments and applied voltages. The cantilevers are made of Si and SiO2 with a p-type Si resistor embedded. The cantilevers are operated in air and water at different applied voltages. The numerical analysis uses finite element analysis software ANSYS Multiphysics. Results show that monolith and u-shape cantilevers have similar temperature distributions, but the maximum temperature values in u-shape cantilever are higher.
Abstract: In a cannonball firing test, inactive cannonballs are fired to an impact area of a medium such as sand. Collision, penetration, impulse damping and fracture are investigated. For an efficient construction and utilization, researches on media for an impact area are necessary. In this study, the collision and penetration of cannonballs into sand is analyzed. It is found that density of a medium is an important factor.
Abstract: In order to study the influence of the layer of the laser cladding to the bending degree, obtain the mathematical formulation in shaft laser cladding bending and derive the empirical formula, the laser cladding test for shaft was designed. The laser cladding test had been proceeded at the same cladding area and different layer of cladding. The results of the experiment show that the shaft is bended facing the laser beam. The bending degree and the layer of laser cladding are at the direct proportion. At the same time mathematical formulation in shaft laser cladding bending has been established and the parameter which is used to measure the degree of the bending has been obtained. Empirical formula between bending degree and the layer of laser cladding has been established. The circular run-out formula along the shaft length has been derived. The calculated value and the measured value are of the goodness fit. The maximal error is 0.035mm, and the average error is 0.017mm. It illustrates that the mathematic formulation is correct and the empirical formula has high accuracy.
Abstract: This article determines the main factors influencing the quality of ERTi-7 titanium wire through building AHP-PQ model: processing technology. under the circumstance of instable quality of ERTi-7 titanium wire in international market. Through the selection of raw material, feeding material evenly during melting, control of melting times and the determination of surface machining process, the inhomogeneity of chemical compositions of ERTi-7 and the corresponding removal method are studied. The results show that it is easier to obtain ingot with good surface and fine structure using triple melting without increasing the content of Pd element, and then going through non-oxidation roller-die drawing process, we will obtain qualified titanium wire with good surface and also conforming to the request of AWS A5.16/A5.16M:2007.
Abstract: The feasibility of mirror surface polishing by using the ring shaped tool (abbreviated as the RST) is studied. This novel polishing process is expected to apply in the fabrication of precise mold and optics. In order to reduce the tool wear effect, the semi-spherical tool was replaced by the ring shaped tool. The experimental results show that the machining rate is not affected by the tool wear, That is, this new process provides excellent machining repeatability. On the other hand, the mirror surface with Ra 4.4nm was yielded in the lager area polishing.
Abstract: In this paper,SWRH82B steel as the object of study,analysis of several typical drawing fracture tpyes to explore the reasons for fracture by SEM testing.The results show that:the type of slope-type fracture mainly due to cracks defects generated in surface of the wire rod;the Pen-shaped type fracture due to central segregation in the continuous casting process;whole flat brittle fracture mainly due to a serious slag in the continuous casting process.
Abstract: The dimensional accuracy of shells and binders of investment casting which incorporation with selective laser sintering is investigated. The results show that the dimensional accuracy of colloidal silica is higher than that of ethyl silicate, and the dimensional variation rate of investment casting shells produced with colloidal silica is much lower than ethyl silicate shells. Moreover, colloidal silica possesses better performance on environmental protection and production cost control. These indicate that the comprehensive properties of colloidal silica are better than that of ethyl silicate. Meanwhile, the average dimensional variation rate of the single colloidal silica shell and the ethyl silicate-colloidal silica alteration shell was almost identical and it was much lower than that of the other shells which were produced in this study. This means two kinds of shells are optimized in all five types of shells studied in the aspect of dimensional accuracy. The unique properties of two shells show clearly direction to choose the type of shell.
Abstract: Abstract The titanium alloy direct laser fabrication process, the collapse of a side issue has interference and preventing the forming quality and forming precision. This thesis mainly contain with of temperature field analysis and actual observation, by changing the scanning mode to solve this issue. The new scanning mode, dam-type, has a good property and proves that the direct laser fabrication parameters can be complete without change through the whole forming process, and puts the process of control simply.
Abstract: Flexible automated manufacturing environment put new demands to the Coordinate Measuring Machines, an operator in CAD center, inputs inspection requirements according to the drawings parameter, should automatically generate the CMM measuring programs. To solve these issues, we use of an expert systems which is composed of the knowledge base, the inference engine, a database and a human-machine interface.
Abstract: Local environment control system (LECS) has been widely used in many areas as the necessary guarantee for most precision instruments. A sealed air cooling constant temperature box with dual-chamber structure that can provide constant working condition for precision instruments in-vehicle was developed. According to the heat transfer analysis of the double plate-fins heatsink, the heat radiation area and dimensions were determined based on electrical analogy. The air flow rate and temperature distribution of the system in heat steady-state was simulated by CFD software, and the results are consistent with that of experimental test. In different conditions, the thermal test results indicate that when the heat flow rate in the inner chamber is about 170 W, the temperature difference between inner chamber and environment is no more than 6.5 °C. The thermal design and test methods can be as the reference for the design of other precision instruments in-vehicle.