Pouring Process Research Articles

Study on the distribution characteristics of aerosol produced by powder dumping in glove box

Objective To investigate the effects of particle size, wind speed and dumping velocity on aerosol concentration distribution during powder dumping in a reprocessing plant. Methods CeO 2 powder was selected as the substitute material of PuO 2. FLUENT software was used to calculate the pouring process of CeO 2 powder under different operation conditions. Then the aerosol concentration distribution under different dumping speeds was measured by particle size spectrometer to verify the accuracy of simulation results. Results The particles with small particle size are more likely to be separated from the mainstream area by the drag force of the surrounding gas, and the radius of the diffusion range also increases with the decrease of the particle size. 2) When the ventilation speed is less than 1 m/s, the dust lifting can be reduced and the concentration of dust particles in the chamber can be reduced to a certain extent. 3) In the process of powder dumping, the spoon is rotated anticlockwise at a speed of 100° in 2~3 s, and less dust aerosol is produced on the right side of the tray. Conclusion When operating the powder particles with smaller particle size, more attention should be paid to the monitoring of aerosol at different positions; the change of air inlet velocity makes the flow field in glove box more complex, and the volume fraction of dust particles is related to the size and location of vortex formed by airflow. The greater the wind speed, the greater the impact on the powder dumping process. The experimental results are basically consistent with the simulation results, and the results show that the lower the dumping speed, the smaller the aerosol concentration near the tray. 摘要： 目的 考察粒径、风速和倾倒速度对后处理厂粉末倾倒过程产生的气溶胶浓度分布的影响。 方法 选择 CeO 2 粉末作为 PuO 2 替代材料, 用 FLUENT 软件对不同操作条件下 CeO 2 粉末倾倒过程进行数值计算, 再利用粒径谱 仪对不同倾倒速度下的气溶胶浓度分布进行测量, 验证模拟结果准确性。 结果 小粒径的颗粒更可能受周围气体的 曳力影响而从主流区域脱离出来形成散射粉尘, 其扩散范围的半径也随着粒径的减小而扩大。通风速度在 1 m/s 以下可以减少操作过程粉尘的扬起, 在一定程度上降低箱室内粉尘颗粒的浓度。粉末倾倒过程, 以 2~3 s 将勺子逆时 针旋转 100° 的速度倾倒粉末在托盘右侧产生的粉尘气溶胶较少。 结论 在对粒径较小的粉末颗粒进行操作时, 不同 位置气溶胶的监测应该引起更多的关注;进风速度的变化使得手套箱内的流场变得复杂, 粉尘颗粒的体积分数与气流 形成涡流的大小和涡流位置有关, 风速越大, 对粉末倾倒过程的影响越大;实验结果与模拟结果基本相符, 较慢的倾倒 速度在托盘附近处产生的气溶胶颗粒较少。

Dynamic analysis of poured packing process of ellipsoidal particles

Packing properties are determined by the dynamic deposition history and affected by many variables. In this work, DEM is used to study the effects of dropping height, deposition intensity and friction coefficient on the dynamic response and stable-state packing properties of ellipsoidal particles. The results demonstrate that with dropping height increasing, packing density increases but the bed becomes less ordered. Dropping height affects the densification process of ellipsoids more significantly than spheres. At high dropping height, the transition period of the orientation angle in the densification process almost disappears for oblate particles, while it becomes longer for prolate particles. With the increase of deposition intensity, packing density decreases significantly, but orientational order changes slightly. With the increase of sliding friction coefficient, packing density and orientational order decrease dramatically. The difference in packing density is mainly caused by dynamic pouring process rather than the densification process.

Risk Assessment and Intelligent Control of Ladle Pouring Mechanism

The constant current casting of molten steel in ladle lifted by special-purpose crane is an important part of metallurgical production line. At the same time, there are risks of failure in the pouring process, so it is necessary to carry out risk assessment on the pouring system. Based on the constant current casting theory, the relationship between velocity and time is deduced by assuming the physical model in the pouring process. And the visual programming software is proposed, and the lifting speed of the auxiliary hook at different moments in different pouring stages is calculated. The lifting speed of the auxiliary hook at different times was input into MATLAB, and the Gaussian curve was fitted in the Notebook environment, to obtain the function and function curve of the lifting speed of the auxiliary hook with respect to time. It can be seen from the comparison of a series of auxiliary hook lifting velocity function curves that the molten steel starts to flow from the ladle until the molten steel is poured. The lifting speed changes smoothly and does not cause huge fluctuations and splashes of molten steel. This study not only prevents the failure of ladle crane, but also realizes the intelligent automatic control of the casting process of ladle crane. It is of great significance to the intelligent development of ladle crane.

Numerical Simulation of the Construction Process of Long Spiral CFG Piles

A numerical model for the construction process of long spiral CFG piles is established based on the coupled Eulerian–Lagrangian method. The construction process is divided into drilling process and concrete pouring process for modeling. The influence of long spiral CFG piles construction on saturated sand foundation is studied, and dynamic responses, changes of pore water pressure, and void ratio of saturated sand foundation are obtained. The rationality and accuracy of the simulation results are proved by comparing with the field test data and calculation results of the theory of cylindrical cavity expansion. The presented numerical results prove that the vibration load generated during the construction acts on saturated soil in the form of irregular reciprocating shear forces, which leads to a large excess pore water pressure in the soil and an increase in soil void ratio. Both the excess pore water pressure field generated during the construction and the soil pore ratio after the construction show a parabolic distribution in the vertical direction. The research results can provide reference and theoretical basis for future research and engineering practice.

Model-Based Flow Rate Control with Online Model Parameters Identification in Automatic Pouring Machine

In this study, we proposed an advanced control system for tilting-ladle-type automatic pouring machines in the casting industry. Automatic pouring machines have been introduced recently to improve the working environment of the pouring process. In the conventional study on pouring control, it has been confirmed that the pouring flow rate control contributes to improving the accuracy of the entire automatic pouring machine, such as the outflow liquid’s falling position from the ladle, the liquid’s weight filled in the mold, and the sprue cup’s liquid level. However, the conventional control system has problems: it is not easy to precisely pour the liquid in the ladle with a large tilting angle, and it takes time to adjust the control parameters. Therefore, we proposed the feedforward pouring flow rate control system, constructed by the pouring process’ inverse model with the online model parameters identification. In this approach, we derived the pouring process’ mathematical model, representing precisely the pouring process with the ladle’s large tilting angle. The model parameters in the pouring process’ inverse model in the controller are updated online via the model parameters identification. To verify the proposed pouring control system’s efficacy, we experimented using the tilting-ladle-type automatic pouring machine. In the experimental results, the mean absolute error between the outflow liquid’s weight and the reference weight was improved from 0.1346 at the first pouring to 0.0498 at the fifth pouring. Moreover, the model parameters were identified within 4 s. Therefore, it enables updating the controller’s parameters within each pouring motion interval by the proposed approach.

Effect of material-technological properties on the reconstruction of utility parameters of bells

An important utility parameter of bells, including church bells, is their sound – that depends on geometry of the body, changes in section thickness and material from which they are made. Knowing the geometry of casting and chemical composition of the alloy, it seems that the current state of art allows recreating not only solid, but also acoustic properties of the casting. Hence, the purpose of this work is to make a casting using reverse engineering tools, compare acoustic properties of the newly formed bell with the prototype, and test material for a bell alloy. For the host and casted bell the note and octave are identical, the sound differs only in the number of cents away from the exact note. Compared with the numerical model, the acoustic properties of newly formed bell were found with slight deviations. The reasons for registered differences between the components of the original sound and the copy are seen as differences during melting, pouring and solidification processes of the alloy. Material tests carried out on samples taken from the new bell also showed microporosity of the casting and change in microhardness of the α and eutectoid phase (α + δ) along height of the bell cross-section. The chemical composition of bronze also varied along with the change of measuring points at the rib height and the fraction of eutectoid in the alloy structure. Material tests showed a significant influence of cast porosity on its acoustic properties.

CHARACTERISTIC OF INTERFACE BIMETAL ALUMINUM-COPPER FOR BIMETAL BUSHING PRODUCED BY CENTRIFUGAL CASTING

Bimetallic is a type of metal composite that combines two metals that form a metallurgical bond. The manufacture of bimetallic bushings by centrifugal casting has not been developed much. Recently, there is no recommendation yet for optimum temperature and speed of rotation to produce bimetallic bushings. The research was conducted to determine the rotation of the mold in centrifugal casting so as to produce a well-integrated interface. The materials used are aluminum and copper. Aluminum was melted at 750 °C, while copper was melted at 1200 °C. Molten metal was pouring alternately. First, aluminum was poured into the mold, and then after the aluminum temperature reached 400º C, copper was poured into the mold to form a bushing aluminum-copper bimetallic. The molten metal was poured into a rotating sand mold with a constant filling speed of about 0.15 kg s-1. The variations of the rotational speed of the mold were 250, 300, and 350 rpm. The result shows that the interface’s width increases as the mold rotation increases during the pouring process. Interface hardness and wear are increased compared to the base metal. Hence, centrifugal casting with 350 rpm is recommended for aluminum-copper bimetal bushing applications.

How Does Gas-Phase CO2 Evolve in the Headspace of Champagne Glasses?

The chemical space perceived by a consumer of champagne or other sparkling wines is progressively modified all along tasting. Real-time monitoring of gas-phase CO2 concentration was performed, through a CO2-diode laser sensor, along a two-dimensional array of nine points in the headspace of three types of glasses poured with champagne. Two original glasses with distinct headspace volumes were compared with the standard INAO tasting glass. For each of the three glass types, a kind of temperature-dependent CO2 fingerprint was revealed and discussed as a function of the glass geometry and headspace volume. Moreover, a simple model was developed, which considers the rate of decrease of the concentration of gas-phase CO2 in the headspace of a glass after the pouring process as being mainly ruled by natural air convection in ambient air. The timescale which controls the rate of decrease of gas-phase CO2 was found to highly depend on the ratio of the headspace volume to the open aperture of the glass.

Lean construction analysis of concrete pouring process using value stream mapping and Arena based simulation model

An important challenge for the construction industry is how to reduce non-value adding activities which produce waste. Many researchers have attempted to resolve it to enhance the performance of this industry. However, the concrete pouring process (CPP) has not been adequately investigated in this regard. Accordingly, the present study aims to examine how to apply the lean manufacturing concepts to CPP effectively determine different wastes generated during operations, the main cause of the waste generation, and the strategies to minimize or mitigate the generation of the waste. Mixed value stream mapping (VSM) and computer simulation are applied to identify and eliminate wastes in a CPP case study by using lean principles and time-frame formulation through takt time calculation. Based on the future VSM improvements, findings showed that that production lead time (PLT) reduced from 11 days to 7 days, and the value-added time decreased from 38.2 min to 22.5 min. Takt time also was reduced from 138 s to 93 s. Our results are a valuable resource for construction managers and engineers to improve the concrete pouring process’s productivity in a cost-effective and timely manner.

A Positioning Method of Temperature Sensors for Monitoring Dam Global Thermal Field

During the concrete pouring process of a dam construction, timely and accurate temperature monitoring is of great significance to reveal the thermal distribution characteristics and evolution process, and control concrete cracking. In this study, a positioning method of temperature sensors (PMTS) in a concrete dam is developed to determine the arrangement of temperature sensors quantitatively. The proposed positioning method is related to the restructured thermal field based on the natural neighbor interpolation algorithm, and the cross-validation. Based on the method, thermometers, distributed optical fibers and infrared thermal imagers are optimally installed in a super-high arch dam for real-time measurement of concrete temperature. The results show that the PMTS is reasonable and reliable for obtaining the dam global thermal field. The on-site temperature monitoring data indicate that the time and space temperature distribution law of the restructured thermal field is consistent with the actual situation of the super-high arch dam. In addition, the cons and pros, and improvement of the PMTS are further discussed. The proposed PMTS is a valuable method to monitor the global thermal field of concrete dams.

In-Situ Observation of Pouring a High-Viscosity Liquid

The rheology of liquids affects their ease of pouring. In this study, the subjects evaluated the feeling of pouring liquids with various viscosities. The situation was recorded with a high-speed camera and force plate. The score for ease of pouring water and 5 wt% thickened aqueous solution was 8.9 ± 1.5 and 2.1 ± 1.6 respectively, demonstrating that the score decreased with increasing viscosity. The three stages of the pouring process, namely the flowing state in which the liquid flows out vigorously (I), the yarning state in which the liquid flows out to stretch (II), and the dripping state in which the liquid flows out as droplets (III) were observed. The duration of state II extended as the viscosity increased. These findings can be useful for the development of characteristic containers and beverages.

Exploring Productivity of Concrete Truck for Multistory Building Projects Using Discrete Event Simulation

Concrete pouring activity is essential for the schedule and quality of the structural work construction. In practice, the process of concrete pouring is frequently congested and interrupted due to many unforeseeable reasons. The primary purpose of this study is to explore the productivity of concrete trucks for multistory building projects. The interview technique and work sampling method have been employed to collect the necessary data. Based on the literature review and experts’ opinions, twenty-five factors affecting the productivity of pouring concrete have been found and discussed. Among them, there are seven factors identified as different from previous studies. Through two case studies of the hospital project, the actual average productivity of one concrete truck used to pour concrete into columns and walls is 0.184 m3/min by using a truck-mounted pump and 0.087 m3/min by using a tower crane. These productivities have been then determined based on discrete event simulation (DES). The simulation results indicated that the simulated productivity is higher than the actual productivity of approximately 16% and 13% for truck-mounted pump and tower crane, respectively. It is concluded that DES is a handy simulation tool for construction operations before the period of implementation. Based on the relationship between events of the process of concrete pouring, two relevant solutions have been proposed to enhance the productivity of concrete trucks. The results of this study may help practitioners manage the concreting activities in their projects with higher productivity.

Void closure behavior during plastic deformation using the representative volume element model

The process of smelting, pouring, and solidification for steel determines the inevitable existence of all kinds of macroscopic and microscopic void defects in the ingot. These voids need to be eliminated by a proper plastic forming process. However, the mechanism of void closure is not well understood at present. In particular, the investigation on the evolution law of void closure under complex stress state is not deep enough. Based on the representative volume element model, numerical simulations and theoretical analysis, the effects of the spherical stress tensor and the deviatoric stress tensor on the evolution of void are expounded. It is found that the relative size of the three principal values of the deviatoric stress tensor determines the shape change of the void during plastic deformation. Besides, the change of the relative value of the principal values of the deviatoric stress tensor has little effect on the maximum compressive strain required for void closure. Moreover, the smaller the principal value of the spherical stress tensor is, the smaller the strain required for void closure is.

A first step towards the mapping of gas-phase CO2 in the headspace of champagne glasses

Key upgrades to a previously developed CO2-Diode Laser Sensor (CO2-DLS) were done to monitor as accurately as possible the level of gas-phase CO2 in champagne glasses. The upgraded CO2-DLS allows to access a wide range of CO2 concentrations (10–100%). An additional set of mirrors with two pairs of galvanometer scanners was developed in order to provide simultaneous measurements of gas-phase CO2 concentrations in the whole glass headspace. During the five minutes after pouring, the CO2-DLS unambiguously unveiled horizontal homogeneity in the glass headspace in terms of gas-phase CO2 concentrations. Nevertheless, a strong vertical gradient of gas-phase CO2 was highlighted, with ever increasing CO2 concentrations ranging from approximately 15% to 50% while moving away from the glass edge to the champagne interface. This strong vertical gradient was found to persist during the five next minutes following the pouring process, but with ever decreasing CO2 concentrations as time elapses.

Superposition Technology of Complex Giant Reinforced Concrete Beams

Superposition technology construction is widely used in Large-span structures, super high-rise structures and large drop concrete structures. Based on the construction process of reinforced concrete for deep foundation pit engineering in Changsha Ice and Snow World, Superposition technology and support design of large section concrete structures are discussed. ABAQUS finite element analysis was used to obtain the pouring process. It provides the technical foundation for the future design and construction of complex giant reinforced concrete structures.

Study on ventilation performance of lateral exhaust hood under the influence of two high-temperature buoyant jets

Two high-temperature buoyant jets widely exist during the pouring process of molten metal. The lateral exhaust hood is usually used to capture contaminated airflow considering production process. However, the current flow ratio design method for the lateral exhaust hood is in consideration of a single pollution source. In this study, the applicability of the current flow ratio design method for controlling two high-temperature buoyant jets is analyzed. And the performance of lateral exhaust hood influenced by these two buoyant jets is investigated through model experiment and numerical simulation. Investigated factors are distances between two high-temperature buoyant jets, initial velocity ratios, and initial temperature ratios. The results show that the maximum capture efficiency is less than 60% when the optimal exhaust flow rate for controlling the single-buoyant jet is doubled to control the two buoyant jets. Besides, with the distance ratio between the two buoyant jets increasing to 0.75, the two jets merge into one jet. Then, compared with that when the velocity ratio is 0.4, the dimensionless installation height of the lateral exhaust hood should be increased by about 0.04 when the velocity ratio is 1.0 and by about 0.12 when the velocity ratio is 1.4. Finally, with the temperature ratio increasing, the lateral exhaust hood flowrate should be increased to improve the capture efficiency instead of exhaust hood installation heights. In summary, the obtained conclusions could help develop high-efficiency ventilation systems and reduce the energy consumption of the industrial buildings.

The Influence and Action Mechanization of Mineral Mixed Material on High Fluidity Potassium Magnesium Phosphate Cement (MKPC)

Potassium magnesium phosphate cement (MKPC) is a type of chemically bonded ceramic material that has higher performance compared to traditional Portland cement. To develop the spraying and crack pouring process of MKPC, the mechanical properties, volume deformation, hydration temperature, and water stability of the high-fluidity MKPC with different mineral mixed materials and their influence laws were studied. The effects of phase composition and micromorphology of hydration products on the properties of MKPC and its mechanism were analyzed using X-ray diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA), and scanning electron microscopy (SEM). The results show that fly ash and metakaolin will not reduce the fluidity of MKPC paste because of their material properties, and silica fume will reduce the fluidity of MKPC paste because of its large specific surface area and high water absorption. Metakaolin can react with phosphate to form aluminum phosphate gel and fill the pores between the crystals because it has a higher activity, which can significantly improve its compressive strength. However, during the later stage of hydration, there will be slight expansion, which would reduce its bonding flexural strength. The MKPC-hardened paste mixed with silicon ash has optimal stability: therefore, it has the highest bonding flexural strength. Microcosmic analysis shows that mineral mixed material plays a physical filling role and participates in the hydration reaction as an active ingredient to improve the early hydration degree, which can change the crystal size and micromorphology of MKPC-hardened paste and make the structure more compact.

Influence of reduction on adhesive properties

An analytical analysis of the action of rolls on the medium and its behaviour at adhesion bonds with its surface are carried out. The methods and means of carrying out researches on determination of surface roughness are offered, and the experimental setting for determining the adhesion strength is developed. To reveal the essence and understanding of the general research execution, a number of hypotheses for the determination of adhesion are given and a generalized approach to the definition of adhesion is given. The physical nature of the influence of the roughness of the roller surface on the injection of the dies depends on the shape and angle of roughness, the application of mechanical forces, the degree of its previous dispersion (recipe) and its physical and mechanical properties. The nature of the contact interaction of the dough with the rough surface of the roller working organ in the injection nozzle of the fumigation machine is established. Violation of these mutual relations leads to the production of poor-quality products and a reduction in the efficiency of the machine. The contact area of the adhesive and the component forming work for overcoming the adhesion and deformation of the environment in determining the criteria influencing the process according to each particular period of the deformation stage are substantiated. The obtained data give an answer to a number of questions about the possibility of interaction of the surface of the working bodies from the environment. On the basis of their data, the actual change in the contact adhesion in the roller unit of the molding machine with a comparative analysis of existing ones with the newly designed design is considered. It is established that in order to provide a constant area of actual contact, which contributes to better adhesion, and, accordingly, the passage of a qualitative process of tightening, compression and pouring, the necessary condition is the consistency of the specified criteria. This means that the actual contact area , varies from to depending on the ratio of parameters.

Simulation and Visual Tester Verification of Solid Propellant Slurry Vacuum Plate Casting

AbstractUsing an improved Carreau constitutive model, a numerical simulation of the casting process of a type of solid propellant slurry vacuum plate casting was carried out using the Flow3D software. Through the flow process in the orifice flow channel and the combustion chamber, the flow velocity of the slurry passing through the plate flow channel was quantitatively analyzed, and the viscosity, shear rate, and leveling characteristics of the slurry in the combustion chamber were qualitatively analyzed and predicted. The pouring time, pouring quality, and flow state predicted by the numerical simulation were verified using a visual tester consisting of a vacuum plate casting system in which a pouring experiment was carried out. Studies have shown that HTPB three‐component propellant slurry is a typical yielding pseudoplastic fluid. When the slurry flows through the flower plate and the airfoil, the fluid shear rate reaches its maximum value and the viscosity of the slurry decreases. The visual pouring platform was built and the experiment was controlled according to the numerically‐calculated parameters, ensuring the same casting speed. The comparison between the predicted casting quality and the one obtained in the verification test resulted in an error less than 10 %. Moreover, the error between the simulated casting completion time and the process verification test result was also no more than 10 %. Last, the flow state of the slurry during the simulation was consistent with the one during the experimental test. The overall leveling of the slurry in the combustion chamber was adequate and no relatively large holes and flaws developed during the pouring process.

Alloy Design and Characteristics of High Cr Cast Steel for Coiler Roll Produced by Continuous Pouring Process for Cladding

Alloy Design and Characteristics of High Cr Cast Steel for Coiler Roll Produced by Continuous Pouring Process for Cladding