Simulation of the Interphase of Insert Injection Moldings

In this work, the generalizing of the finite element method (FEM) of thermoplastic prepreg insert injection molding composites was investigated. The specimens were prepared using glass fiber/polyamidc 6 (GF/PA6) inserted prepreg, and their characteristics were investigated and compared under ANSYS workbench program. The prediction of the bending initial fracture point under analytical tensile testing with interlayer on prepreg insert moldings was focused. It was found that the bending initial fracture point was applied to predict by matching the shear stress. There was obtained from analytical tensile testing and bending analysis. Therefore, it can be obtained the optimum of the clastic modulus ratio on the injection part/interlayer/insert part by using FEM via ANSYS workbench.

Mechanical Properties of Carbon Epoxy Prepreg Insert Phenolic Resin Injection Moldings

This study focuses on the insert-injection molding process. The thermoset composite inserts in this study were carbon fiber/epoxy (CF/Epoxy) prepreg sheets. The injected molded part was glass fiber contained phenolic resin (GF/PF). The CF/Epoxy was placed in the mold cavity prior to injecting GF/PF onto the inserted injection molded CF/Epoxy specimens. The role of adhesion between the inserted part and injected resin on the mechanical properties was evaluated by 3 point bending and impact tests. In addition, the effect of prepreg orientation on the mechanical properties of the prepreg inserted-injection molding system was investigated. It was found that the prepreg with unidirectional orientation significantly improved flexural and impact strength of the inserted injection molding composites, providing better support and resistance to bending and impact loading. The main failure modes of the specimens were structural and adhesive failure.

Irregular initial solidification by mold thermal monitoring in the continuous casting of steels:A review

Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the high-efficiency continuous casting of steels.The application of mold thermal monitoring(MTM) systems,which use thermocouples to detect and respond to temperature variations in molds,has become an effective method to address irregular initial solidification phenomena.Such systems are widely applied in numerous steel companies for sticker breakout prediction.However,monitoring the surface defects of strands remains immature.Hence,indepth research is necessary to utilize the potential advantages and comprehensive monitoring of MTM systems.This paper summarizes what is included in the irregular initial solidification phenomena and systematically reviews the current state of research on these phenomena by the MTM systems.Furthermore,the influences of mold slag behavior on monitoring these phenomena are analyzed.Finally,the remaining problems of the formation mechanisms and investigations of irregular initial solidification phenomena are discussed,and future research directions are proposed.

Effects of the Water-Cement Ratio and the Molding Temperature on the Hydration Heat of Cement

The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry.The specimens were prepared with water-cement ratios of 0.31,0.38,and 0.45,and the molding temperature was specified at 10 and 20℃.The experimental results show that,as the water-binder ratio increases,the value of the second temperature peak on the temperature curve of the cement paste decreases,and the age at which the peak appears is delayed.The higher the water-cement ratio,the higher the hydration heat release in the early period of cement hydration,but this trend reverses in the late period.There are intersection points of the total hydration heat curve of the cement pastes under the influence of the water-cement ratio,and this law can be observed at both molding temperatures.With the increase in the molding temperature,the age of the second temperature peak on the temperature curve of the cement paste will advance,but the temperature peak will decrease.The higher the molding temperature,the earlier the acceleration period of the cement hydration began,and the larger the hydration heat of the cement in the early stage,but the smaller the total heat in the late period.A subsection function calculation model of the hydration heat,which was based on the existing models,was proposed in order to predict the heat of the hydration of the concrete.

Analysis and optimization of stamping and forming process of bearingouter ring

To address the common issues of wrinkling,tearing,and uneven wall thickness in the actual sheet metal stamp-ing process of the outer ring of needle roller bearings,this study analyzes critical technical indicators such asforming limits,thickness distribution,and principal strains in the forming process in detail.Three-dimensionalmodels of the concave and convex dies were constructed.The effects of different process parameters,includingstamping speed,edge pressure,sheet metal thickness,and friction coefficient,on the quality of the forming partswere investigated by varying these parameters.Subsequently,the orthogonal experimental method was used todetermine an optimal experimental group from multiple sets of experiments.It was found that under the processparameters of a stamping speed of 3000 mm/s,edge pressure of 2000 N,sheet metal thickness of 0.9 mm,andfriction coefficient of 0.125,the forming quality of the outer ring of the bearing is ideal.

基于创新性内侧壁成型工艺的多光学通道微型碱金属原子气室

Existing microfabricated atomic vapor cells have only one optical channel,which is insufficient for supporting the multiple orthogonal beams required by atomic devices.In this study,we present a novel wafer-level manufacturing process for fabricating multi-optical-channel atomic vapor cells and an innovative method for batch processing the inner sidewalls of millimeter glass holes to meet optical channel requirements.Surface characterization and transmittance tests demonstrate that the processed inner sidewalls satisfy the criteria for an optical channel.In addition,the construction of an integrated processing platform enables multilayer non-isothermal anode bonding,the filling of inert gases,and the recovery and recycling of noble gases.Measurements of the absorption spectra and free-induction decay signals of xenon-129(^(129)Xe)and xenon-131(^(131)Xe)under different pump-probe schemes demonstrate the suitability of our vapor cell for use in atomic devices including atomic gyroscopes,dual-beam atomic magnetometers,and other optical/atomic devices.The proposed micromolding technology has broad application prospects in the field of optical-device processing.

Elimination of cracks in stainless steel casings via 3D printed sand molds with an internal topology structure

The important supporting component in a gas turbine is the casing,which has the characteristics of large size,complex structure,and thin wall.In the context of existing 3DP sand casting processes,casting crack defects are prone to occur.This leads to an increase in the scrap rate of casings,causing significant resource wastage.Additionally,the presence of cracks poses a significant safety hazard after the casings are put into service.The generation of different types of crack defects in stainless steel casings is closely related to casting stress and the high-temperature concession of the sand mold.Therefore,the types and causes of cracks in stainless steel casing products,based on their structural characteristics,were systematically analyzed.Various sand molds with different internal topology designs were printed using the 3DP technology to investigate the impact of sand mold structures on high-temperature concession.The optimal sand mold structure was used to cast casings,and the crack suppression effect was verified by analyzing its eddy current testing results.The experimental results indicate that the skeleton structure has an excellent effect on suppressing cracks in the casing.This research holds important theoretical and engineering significance in improving the quality of casing castings and reducing production costs.

Non-Darcy Flow in Molding Sands

Darcy’s law is widely used to describe the flow in porous media in which there is a linear relationship between fluid velocity and pressure gradient. However, it has been found that for high numbers of Reynolds this law ceases to be valid. In this work, the Ergun equation is employed to consider the non-linearity of air velocity with the pressure gradient in casting sands. The contribution of non-linearity to the total flow in terms of a variable defined as a non-Darcy flow fraction is numerically quantified. In addition, the influence of the shape factor of the sand grains on the non-linear flow fraction is analyzed. It is found that for values of the Reynolds number less or equal than 1, the contribution of non-linearity for spherical particles is around 1.15%.

Advances in Research of Molded Pulp for Food Packaging

The molded pulp,a product of three-dimensional papermaking technology,is environmentally friendly and has a low environmental impact due to its ability to decompose quickly in the natural environment after disposal.The application of molded pulp for food packaging can replace or reduce the use of plastic food packaging.Researchers extract fibers from plants for the production of safe and hygienic molded pulp for food packaging,and they also study and enhance the qualities of molded pulp to broaden its use in the food industry.This paper reviews the sources and varieties of plant fiber used in molded pulp for food packaging,as well as research on the improvement and optimization of the performance of molded pulp products.Additionally,issues with molded pulp’s actual use for food packaging are reviewed,along with the potential for future research.This work can serve as a reference for molded pulp applications and research in the food industry in the future.

Influence of substituting B_(2)O_(3) with Li_(2)O on the viscosity,structure and crystalline phase of low-reactivity mold flux

The low-reactivity mold flux with low SiO_(2)content is considered suitable for the continuous casting of high-aluminum steel since it can significantly reduce the reaction between Al in steel and SiO_(2)in mold flux.However,the traditional low-reactivity mold flux still presents some problems such as high viscosity and strong crystallization tendency.In this study,the co-addition of Li_(2)O and B_(2)O_(3)in CaO–Al_(2)O_(3)–10wt%Si O_(2)based low-reactivity mold flux was proposed to improve properties of mold flux for high-aluminum steel,and the effect of Li_(2)O replacing B_(2)O_(3)on properties of mold flux was investigated.The viscosity of the mold flux with 2wt%Li_(2)O and 6wt%B_(2)O_(3)reached a minimum value of 0.07 Pa·s.The break temperature and melting point showed a similar trend with the viscosity.Besides,the melt structure and precipitation of the crystalline phase were studied using Raman and X-ray diffraction spectra to better understand the evolution of viscosity.It demonstrated that with increasing Li_(2)O content in the mold flux from 0 to 6 wt%,the degree of polymerization of aluminate and the aluminosilicate network structure increased because of increasing Li+released by Li_(2)O,indicating the added Li_(2)O was preferentially associated with Al^(3+)as a charge compensator.The precipitation of LiAlO_(2)crystalline phase gradually increased with the replacement of B_(2)O_(3)by Li_(2)O.Therefore,Li_(2)O content should be controlled below 2wt%to avoid LiAlO_(2)precipitation,which was harmful to the continuous casting of highaluminum steels.

Effect of electromagnetic stirrer centered outside the mold on steel flow field of bloom continuous casting

Mold electromagnetic stirring technology for optimizing the flow of molten steel is now widely used in the continuous casting production process of high-quality steels.However,studies on the case that the center of the electromagnetic stirrer is located outside the mold have not been reported.Herein,the effect of the electromagnetic stirrer centered outside the mold on the steel flow field was studied in detail by means of numerical simulations.A Gauss meter was used to measure the magnetic induction intensity at different positions,currents,and frequencies.The test results were compared with the simulation results of electromagnetic stirring to calibrate and verify the accuracy of the electromagnetic model.Then,electromagnetic force was introduced into the flow field model as a source term to study its effect on the flow field under anomalous conditions.The results show that when the center of the electromagnetic stirrer is located outside the mold,the magnetic field strength is about twice as strong as that located inside the mold.This also leads to an increase in the flow velocity near the electromagnetic stirrer.As a result,the optimal electromagnetic stirring parameters(200 A,2.5 Hz)were specified when the center of the electromagnetic stirrer is located outside the mold.

Dissolution of TiO_(2) and TiN inclusions in CaO–SiO_(2)–B_(2)O_(3)-based fluorine-free mold flux

Mold flux serves the crucial metallurgical function of absorbing inclusions, directly impacting the smoothness of the casting process as well as the cast slab quality. In this study, the dissolution behavior and mechanism of Ti O_(2)and Ti N inclusions in molten Ca O–Si O_(2)–B_(2)O_(3)-based fluorine-free mold flux were explored by in situ single hot thermocouple technology combined with X-ray photoelectron spectroscopy.The results showed that Ti O_(2) inclusions are effectively dissolved by the molten slag within 76 s, during which the original octahedral [Ti O_(6)]^(8-)structures are destroyed and convert to the networker tetrahedral [Ti O_(4)]^(4-)structures. However, the dissolution rate is much lower for Ti N inclusions than for Ti O_(2)inclusions. This can be attributed to the fact that the Ti N particles need to be oxidized and then dissolved in the molten slag to form tetrahedral [Ti O4]4-and octahedral [Ti O_(6)]^(8-)structures during the Ti N inclusion dissolution process, which is accompanied by the generation of a large amount of N_(2)gas. Moreover, Ca Ti O_(3)crystals tend to nucleate and grow on bubble surfaces with sufficient octahedral [Ti O_(6)]^(8-)structures and Ca^(2+)ions, eventually resulting in the molten slag being in a solid–liquid mixed state.

Numerical Simulation and Experimental Study of the Stress Formation Mechanism of FDM with Different Printing Paths

Environmental contamination has been caused by petroleum-based polymeric materials in the melt deposition process.Nowadays biodegradable materials have been widely used in the fused deposition modeling(FDM)industry,such as polylactic acid(PLA).However,internal complex thermal stress and deformations in part caused by an uneven distribution of PLA filament deposition temperatures during FDM,which will seriously affect the geometric accuracy of the printed part.In order to reduce material waste and environmental pollution during the printing process,the accuracy of PLA part can be improved.Herein,numerical simulation was carried out to investigate the temperature field and stress field during the building and cooling process of cuboid specimens.The effects of printing path on the thermal stress and temperature field during the building process were mainly studied.The results show that the printing path has a significant effect on the stress distribution.The most uni-form stress distribution and the smallest deformation were obtained using the Zig Zag printing path.Finally,the residual stress during the cooling process was collected using strain gauges embedded at the mid-plane of the FDM built cuboid specimens.The simulation results are consistent with the experimental results.

Numerical Study on the Resin Transfer Molding Curing Process for Thick Composites Materials

The successful manufacture of thick composites is challenging since the highly exothermic nature of thermoset resins and limited temperature control make avoiding the onset of detrimental thermal gradients within the composite relatively difficult.This phenomenon is mainly caused by exothermic heat reactions.The so-called Michaud's model has been largely used in the literature to reduce the gap between experience and simulation with regard to the effective prediction of the temperature cycle in these processes.In this work,another solution is proposed to simulate the curing process for thick composites,namely preheating the resin to activate the curing reaction before resin injection into the mold.A good agreement between the experiment and the simulation is found.Moreover,in order to minimize the thermal gradient in the final composite,the thermophysical properties of the fiber and the torque(temperature,time)of the Plate have been varied leading to interesting results.

Preparation Process,Pharmacological Activity and Molecular Mechanism of Valepotriate

In recent years,with the continuous development of the medicinal value of valepotriate and the great attention of scholars.The traditional extraction and purification process can no longer meet the current market standards and needs.The modern technology of valepotriate is of great significance to its application and development.This paper reviews the extraction and purification process,molding process and pharmacological activity of valepotriate,providing a theoretical basis for the research and application of valepotriate.

Reaction of Sorghum Differentials to Grain Mold Infection in Puerto Rico

Grain mold, associated with many fungi, is the most important disease of sorghum, causing both yield and quality losses. In this study, 23 sorghum differentials used in pathotype characterization of anthracnose and head smut pathogens were evaluated for grain mold resistance under favorable conditions in Isabela, Puerto Rico. Lines BTx643 and IS18760 exhibited the lowest grain mold severity, indicating that these two may possess genes for grain mold resistance. These two lines also recorded the highest germination rates 94.7% and 97.6%, respectively, and their seed weight was among the heaviest. In conclusion, these two lines can be utilized in breeding programs to develop grain mold-resistant hybrid lines.

Megamitochondria Initiate Differentiation of Monolayer Cells into Detached Dome Cells That Proliferate by a Schizogony-Like Amitotic Process

Mitonucleon-initiated dome formation involves structural changes occurring over a 20 to 24 hour period in monolayer cells induced by a serum factor. The earliest observable change is the fusion of monolayer cells into a syncytium in which nuclei aggregate and become surrounded by a membrane that stains for endogenous biotin. Each of these structures is further surrounded by a fraction of the mitochondria that arise in the syncytium following initiation of dome formation. The mitochondria fuse around the chromatin aggregate in a structure we have called a mitonucleon. Within mitonucleons, a gaseous vacuole is generated that can be seen in protrusions of the apical membrane pressuring chromatin into a pyknotic state. Eventually that pressure, together with whatever enzymatic changes have occurred in the bolus of chromatin, results in DNA fragmentation. The fragments drawn out through the syncytium by a unipolar spindle are arrayed in a configuration that appears open both to epigenetic changes and to DNA repair and replication by polyteny. The fragmented DNA stretched across the syncytial space, hardly detectable by light microscopy, becomes visible approximately half way through the differentiation as the filaments thicken in what looks like replication by polyteny. This “recycling” of attached monolayer cells into detached dome cells must include DNA replication since the number of cells in the resulting domes is greater than the number of monolayer cells by 30% or more. The resulting DNA associates into a mass of chromatin which will “segment” into polyploid structures and then into what appear to be diploid nuclei over a period of 2 to 4 hours. When the layer of nuclei has filled the syncytium, the nuclei are cellularized, forming dome cells rising up from the monolayer and arching over a fluid cavity. Dome cells can extend into gland-like structures by the same mitonucleon dependent amitotic process observed in dome formation. Some of the characteristics of this process resemble the amitotic process of schizogony among single-celled eukaryotic parasites of the apicomplexan phylum. Mitonucleon initiated amitotic proliferation results in synthesis of dozens of dome cell nuclei in a period of 20 to 24 hours, so it is much more efficient than mitosis. Cells generated by this process and their progeny would also not be sensitive to agents that inhibit mitosis suggesting that the process, as an alternative to mitosis, might be activated in cancers that become resistant to some cytotoxic drugs.

Practicability Evaluation and Improvement of Bloodletting Model Mold in Mongolian Medicine Teaching

According to the problems such as low level and depth of experimental teaching research of Mongolian medicine in higher vocational colleges, lack of applicable teaching model mold, lack of students practical operation in time, and single teaching, the development direction and ideas of bloodletting model mold in Mongolian medicine in vocational Mongolian medicine teaching were proposed to provide valuable reference for the experimental teaching reform of traditional therapy of Mongolian medicine and the teaching reform and development ideas of Mongolian medicine and other traditional medicine.

Effect of Molding Technique That Move Model Position Just before Formation in Production of Laminated Mouthguard

Many molding techniques have been researched to ensure the thickness of custom mouthguards. The aim of this study was to clarify the effect on the thickness of a laminated mouthguard of a molding technique in which the model position is moved forward just before molding. Mouthguards were molded using a 3.0-mm-thick ethylene vinyl acetate mouthguard sheet and a pressure molding machine. The molding method was the normal molding method (condition C) and the molding technique (condition MP) in which the model position was moved 20 mm forward just before molding. Regarding the molding of the first layer (F) and the second layer (S), the following four molding methods based on the combination of conditions C and MP were compared;FC-SC, FC-SMP, FMP-SC, and FMP-SMP. Differences in mouthguard thickness due to molding conditions for the first and second layers were analyzed by two-way ANOVA and Bonferroni’s multiple comparison test. Significant differences were observed among all molding conditions on the labial surface, and the thicknesses were in the order FC-SC < FC-SMP < FMP-SC < FMP-SMP. FMP-SMP was 4.67 mm thick, which was 1.39 mm thicker than FC-SC. FC-SC was the thinnest at the cusp, and a significant difference was observed between other molding conditions. On the buccal side, significant differences were observed between all conditions except FC-SMP and FMP-SC, and the thicknesses were in the order FC-SC < FC-SMP, FMP-SC < FMP-SMP. The results of this study suggested that the labial and buccal sides of laminated mouthguards could be made 1.4 and 1.2 times thicker when a molding technique that moves the model position just before formation was used for the first and second layers. The reduction in thickness was suppressed by approximately 23.2% and approximately 10.7% on the labial and buccal sides, respectively, compared with the normal molding method.

Research on the Impact Behavior of Molten Metal on the Mold Shell in Gravity Casting of Large Titanium alloy Castings

The impact behavior of molten metal on the mold shell in gravity casting of large titanium alloy castings by investment precision castings was studied.The physical and mechanical models of the impact of molten metal on the mold shell during the pouring process were constructed using numerical simulation.The effects of molten metal pouring rate and pouring weight on the maximum impact force of the mold shell were studied.The research results indicated that during the entire pouring process,the impact force of the first molten metal contacting the mold shell was higher than subsequent molten metal.The maximum impact force increased with the increase of pouring rate and pouring weight.The total impact force of the molten metal on the mold shell was composed of the instantaneous impact force converted from instantaneous impulse and itself gravity.The instantaneous impact force of the molten metal that first impacts the mold shell was much greater than its own gravity,while the impact force of the molten metal at the end of pouring was much less than its own gravity.The maximum impact force on the mold shell of a large casting with a pouring weight of 800kg was about three times higher than that of a medium-sized casting with a pouring weight of 80kg.The difference in the total impact force on the mold shell between them mainly comes from the instantaneous impact force converted from instantaneous impulse.