Aiming at the problems of the work profile of globoidal cam in automatic tool changer (ATC) is difficult to design,manufacture and both side of cam groove meshing with the roller in indexing period,taking the globoidal cam of a certain machining center as example,the motion and position relationship between globoidal cam and indexing plate are analyzed,the mathematical equation of globoidal cam contour surface is derived and modified.By using the segment modeling method,the cam profile curve groups in both indexing period and dwell period are created in Pro/E software.By the physical modeling of line and surface,the accurate 3D solid model of the globoidal cam is established.After globoidal cam profile performance analysis and machining practice,the designed globoidal cam model is verified to meet the design and machining requirements,which provides technical support for improving its finish grinding accuracy.

磨削是磨具表面大量形状各异且复杂多边形的磨粒参与切削工件的加工工艺,其过程复杂、试验观察困难,从而单颗磨粒切削研究成为研究磨削机理的重要手段.根据单颗磨粒的切削特点,分别建立其单颗CBN磨粒高速划擦的力学模型和有限仿真模型,利用数值仿真软件Matlab及有限元软件Abaqus对合金钢20CrMo的磨削进行了仿真研究.仿真结果表明单颗磨粒高速划擦的力学模型的正确性,同时分析了未变形切削厚度与其它磨削工艺参数在单颗磨粒切削过程中对磨削力的影响规律.

The gas-solid two phase flow through the bag filter fibers was numerically simulated by Lattice Boltzmann Method.The one-way coupled technique was used to describe the particles' movement behavior according to the Lagrange method.The results indicate that the variation of pressure drop conforms to the Darcy's law perfectly when gas flow passes through the porous media.The principles of the particulate(diameter≤1 μm) transportation and deposition on to the surfaces of the bag fiber were also discussed.The simulation results show that the collection efficiency varies with the particle diameter.When the particle diameter is less than 0.01 μm,the collection efficiency is quite high due to the strong Brownian diffusion effect.If the particle is greater than 0.1 μm,the collection efficiency goes up too,since the interception mechanism of the fiber plays an important role for the big size particles.However,it is relatively difficult to trap the particles in the range from 0.01 μm to 0.1 μm.The simulation is meaningful for the mechanism researches of bag-type dedust.

Surfactant solutions were propounded to remove fine and hydrophobic carbon black particles from coal-fired flue gas. The adsorption mechanisms between sodium dodecyl benzene sulfonate (SDBS, an anionic surfactant) and carbon black particles in suspension were investigated. The influence of inorganic salt (NaCl) was also considered. As results showed, hydrophobic interactions contributed to the strong adsorption between SDBS and carbon black particles in the absence of NaCl, and adding NaCl affected the adsorption process. The adsorption amount of SDBS significantly increased when NaCl was added into the SDBS solution; however, when SDBS was in low concentration, the amount of adsorbed SDBS, which was responsible for the shift of zeta potentials, varied little under different concentrations of NaCl. This indicated that the adsorption of SDBS was mainly caused by hydrophobic interaction and Na+ could not change the adsorption of SDBS on adsorption site when SDBS was in low concentration. Moreover, the adsorbed SDBS and Na+ were retained in the Stern layer.

Four surfactants CTAB,SDBS,AEO-9 and OP-10 were used for washing liquids preparation respectively.The removal of hydrophobic powdered carbon was carried out with a bevel edge scrubber.The effects of surfactants,inlet dust concentration,superficial gas velocity,and liquid-gas ratio on dust removal efficiency(η) and pressure drop(ΔP) were discussed.Furthermore,the dewatering performance of the bevel edge scrubber was evaluated.The bevel edge scrubber had high removal efficiency,low pressure drop,and good dewatering performance.Meanwhile,four washing liquids could greatly improve the dust removal efficiency.And the washing liquid of AEO-9 had the optimal removal effect.When AEO-9 concentration was 0.07mmol/L,inlet dust concentration was 5g/m3,L/G was 1.0L/m3,and superficial gas velocity was 2.5m/s,the removal efficiency reached 99.99%.The inlet dust concentration had little effect on ΔP,whereas L/G and superficial gas velocity had much influence on it.The water content in outlet flue gas was less than 11g/kg(dry) under the experimental condition.

A cake collapse model was developed by taking the combined effects of fractal dimension, relaxation ratio, coordination number, and aggregate diameter into consideration. The cake porosity including intraaggregate and inter-aggregate porosities was modeled successively by three typical coordination numbers (n = 6, 8, and 12). Accordingly, an inversion method made it possible to deduce the coordination number using the measured cake porosities, and the reverse-calculated value with minimum error and the corresponding relaxation ratios were applied as the parameters for the model. As a result, the profiles of intraaggregate and interaggregate porosities and cake porosity were respectively predicted in contrast to the integrated variation of the relaxation ratio and the fractal dimension. Furthermore, a comparison between the model predictions of the cake pressure drop gradients with and without aggregate compression was conducted to validate the presence of cake collapse. The results show that the predictions based on the proposed collapse model are in agreement with the experiments, and the coordination number is one of the key factors that must be incorporated into the cake collapse models.

Scrubbers are being widely used to remove the dust, sulphur dioxide and other harmful gases from coal-fired boilers. In this paper, a novel ‘wet-type’ desulphurization absorber, the PCF device (Chinese LOGO), was developed and studied through an experimental method. The mixture of air and SO2 was used as simulated flue gas and CaCO3-in-water suspension was used as absorbent. The results show that the PCF device has a good overall performance for FGD. Under moderate conditions employed, the content of SO2 in outlet flue gas can achieve a level much lower than that permitted, while the pressure drop is very small due to co-flows in preliminarily treating chamber and no venturi structure in inlet tube. Guide plates and self-excitation chamber can improve the SO2 removal efficiency by intensifying the mass-transfer and second purification. Some feasible process parameters are as follows: slurry pH value = 5.6–6.0, liquid–gas ratio = 8.7–10.4 L/m3, superficial gas velocity in inner cylinder = 3.5–4.5 m/s, and addition of Cl− (in the form of CaCl2) to the slurry (25 g/L) decreased the degree of SO2 removal about 13.12%.

The internal ring matrix distribution of many special ceramic porous medium tubes on a circular plate constitutes an adsorbent device, which can retain nanoparticles aerosol agglomerate by the way of collision, adsorption and diffusion in the process of mass transfer. In this paper, the behavior of industrial flue dust diffusion in the ceramic porous medium device is researched by computational fluid dynamics (CFD) simulation and experiments. Furthermore, resistance characteristic of aerosol flow, nonlinear time-dependent characteristic of flow field and frequency distribution of escaping dust particles are studied. According to the results of simulation and experiment, the lower inlet velocity can keep the lower pressure drop and obtain higher purification efficiency.

The aim of this work is to evaluate the adsorption performances of activated carbon derived from sewage sludge (ACSS) for gaseous formaldehyde removal compared with three commercial activated carbons (CACs) using self-designing adsorption and distillation system. Formaldehyde desorption of the activated carbons for regeneration was also studied using thermogravimetric (TG) analysis. The porous structure and surface characteristics were studied using N2 adsorption and desorption isotherms, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that ACSS has excellent adsorption performance, which is overall superior to the CACs. Adsorption theory indicates that the ACSS outperforms the CACs due to its appropriate porous structure and surface chemistry characteristics for formaldehyde adsorption. The TG analysis of desorption shows that the optimum temperature to regenerate ACSS is 75°C, which is affordable and economical for recycling.

The general behavior of micron-particles in the inner domain of porous ceramic vessel was simulated by computational fluid dynamics software in terms of sampling experimental data. The results show that there is an optimum porosity of 0.32 to get a higher efficiency and lower pressure drop during filtration. According to the results of simulation and experiment, it is evident that lower inlet velocity can maintain lower pressure drop and obtain higher collection efficiency and inlet concentration also has a crucial influence on the collection efficiency. The collection efficiency of equipment increases significantly with the increase of inlet concentration when the inlet concentration is less than 6.3 g/m3, but it gradually tends to be stable in the range of 97.3%-99.7% when the inlet concentration is over this concentration.

The wet flue gas desulphurization has been the most widely used in the coal-fired power plants because of high SO2 removal efficiency, reliability and low utility consumption. In this paper, laboratory studies on the removal of SO2 from gas mixtures with a novel wet-type PCF device (Chinese LOGO) were reported, CaCO3-in-water suspension used as absorbent. The main work included the influences of some process parameters such as slurry pH, limestone concentration in feed stream, SO2 inlet concentration, liquid–gas ratio and superficial gas velocity. Meanwhile, the desulphurization process in the PCF device was analyzed using the two-film theory of gas–liquid mass-transfer. The results show that the PCF device has low pressure drop, large specific capacity for flue gas treatment, high absorption rate and good dewatering performance. Under moderate conditions, the concentration of SO2 in outlet flue gas can achieve a much lower level than that of permitted. The reasonable operating conditions for the PCF device are as follows: slurry pH value is 5.7 ± 0.1, limestone concentration in feed stream is 13 wt.%, SO2 inlet concentration is less than 4.1 g/m3, liquid–gas ratio is 8.7–10.4 L/m3 and superficial gas velocity in preliminary treating chamber is 2.0–2.5 m/s (3.4–4.3 m/s in inner cylinder). Furthermore, the results obtained from the two-film theory show that the SO2 removal rate is controlled by the combination of both gas- and liquid-film diffusions in the range of operating conditions tested.