Screw Section Research Articles

Continuous Anode Slurry Production in Twin-Screw Extruders: Effects of the Process Setup on the Dispersion

Screw design in the extrusion process has an important effect on the distribution of material through the extruder, resulting in partially filled sections in the processing zone. Accordingly, the local accumulation of material in the extruder leads to variations in material strain conditions and also influences the local residence time of the material in a given screw section. This work evaluates particle dispersion in anode slurry considering three different screw arrangements. The particle size distribution is considered as a quality parameter representing the microstructure of the battery slurry components and their distribution. Numerical simulation of the material flow behavior through a laboratory extruder was performed to investigate the filling ratios and resulting shear rates for different screw designs and process conditions. The importance of process parameters and a suitable screw configuration to achieve specific particle sizes in battery slurry is discussed.

Design of a detachable bronchoscope for endotracheal intubation

A novel detachable bronchoscope with a 3D printed micro-transmission is investigated. The micro-transmission controls the motion of the tip of the bronchoscope and is embedded in one end of the flexible insertion section of the bronchoscope. The micro-transmission allows manipulation of the distal end through the translation of guide nuts that are connected to the tip of the bronchoscope through so-called “angulation” wires. The displacement of the guide nuts on the left and right-handed screw sections and the control of the distal end of the bronchoscope are investigated. The maximum tensile force on the angulation wire before failure is determined experimentally for different screw pitches.

Influence of Lowering the pH Value on the Generation of Fibrous Structures of Protein Gels with Different Network Types.

High-moisture extrusion of plant proteins to create meat-like structures is a process that has met with increasing attention in the recent past. In the process, the proteins are thermomechanically stressed in the screw section of the extruder, and the resulting protein gel is structured in the attached cooling die. Various protein sources, notably soy protein isolate (SPI) and wheat gluten, are used to form gels with different networks: SPI creates a physical, non-covalent network, while gluten forms a chemical, covalent one. The food industry frequently adds weak acids to modify taste and shelf life. However, it is known that a change in pH affects the gelation behavior of proteins because the repulsive forces within and between the proteins change. The research reported here was carried out to investigate for the two proteins mentioned the influence of pH modification by the addition of citric acid and acetic acid on gel formation and the meat-like structures produced. For this purpose, materials and parameters were screened using a closed cavity rheometer, followed by extrusion trials at pH 7.36-4.14 for SPI and pH 5.83-3.37 for gluten. The resulting extrudates were analyzed optically and mechanically, and protein solubility was tested in a reducing buffer. For both protein systems, the addition of acid results in less pronounced meat-like structures. At decreasing pH, the complex viscosity of SPI increases (from 11,970 Pa·s to 40,480 Pa·s at 100 °C), the generated gel becomes stronger (strain decreased from 0.62 to 0.48 at 4.5 × 105 Pa), and the cross-linking density grows. For gluten, a decreasing pH results in altered reaction kinetics, a more deformable resulting gel (strain increased from 0.7 to 0.95 at 4.5 × 105 Pa), and a decreased cross-linking density. Solubility tests show that no additional covalent bonds are formed with SPI. With gluten, however, the polymerization reaction is inhibited, and fewer disulfide bonds are formed.

Determination of optimal parameters of hinged operating elements of screw conveyers

The relevance of the research lies in the need to improve, develop new designs and determine the optimal structural and kinematic parameters of the hinged sections of the screw working bodies of the conveyors, in order to obtain better functional and operational characteristics of the process of transporting loose and lumpy materials and granular fertilizers. It is necessary to improve and develop a new designs and determine optimal design and kinematic parameters of hinged sectional operating elements of screw conveyers, which can provide the improvement of functional and operating characteristics of the process of transporting loose materials. Therefore, the purpose of the research was to improve the operational performance of flexible screw conveyors by developing and determining the optimal parameters of hinged flexible screw sectional working bodies for overloading bulk materials along curved transportation branches. The research was carried out using the methods of the theory of mathematical and computer modeling. the method of mathematical planning of the experiment. The article presents new designs of hinged screw working bodies and substantiates their optimal parameters for ensuring the movement of loose materials along curvilinear routes. The relationship between the magnitude of the torque that occurs between the loaded screw sections and their spatial arrangement is determined. Analytical dependences were obtained for the stiffness conditions of a separate section with a hinged connection depending on the load and design parameters of the conveyor. It has been established that the angular displacement of the sections according to the dependence established in the state allows to significantly (up to 4-5 times) reduce the amplitude of the change of the torque of the drive, and also lowers its maximum value. It was proved that in the pushing mode, energy consumption is 1.06...1.4 times higher than in the pulling mode. The practical significance of the results lies in the ability to choose the optimal structural, kinematic and technological parameters of the developed sections of the screw working body for transporting loose or lumpy materials and mineral fertilizers

ОПРЕДЕЛЕНИЕ РАЦИОНАЛЬНОГО КОЛИЧЕСТВА ВИТКОВ ШНЕКОВОГО СМЕСИТЕЛЯ С АКТИВНЫМ КАНАЛОМ ОБРАТНОГО ХОДА

The conducted studies have shown that a promising design and technological scheme of the mixer is a low-speed screw mixer of periodic action, the loading and unloading parts of which are connected by an active return channel having areas of interpenetration of feed mixture components.It is established that the cycle time consists of the time of passage of the components of the mixture through the sections of the screw winding, tangential blades and in the return channel under the action of an additional screw. The time spent by the mixture on the screw section and in the return channel is determined by the length of each section, the design parameters of the winding, the angle of installation of the housing to the horizon and the rotation frequency of the working body. When determining the time spent on the interpenetration site of the components of the mixture, it is necessary to take into account the filling factor of the return channel and the physico-mechanical properties of the components of the mixture.The duration of loading and unloading of the mixer is determined from the condition of the axial velocity of movement of the feed mixture components in each of the sections and corresponds to the cycle time.The residence time of the mixture at each of the sites is determined taking into account the design parameters and the rotation speed of each working body. The optimal ratio between the diameters of the auger and the additional auger from the condition of the maximum volumetric capacity of the mixer is revealed. Expressions are obtained for determining the supply of working bodies at each of the sections from the condition of continuity of the flow. Modeling of the volumetric feed allowed us to estimate the effect on the volumetric flow of the mixer depending on the ratio of the pitch of the screw turn to its diameter, the number of screw turns.

Estimation of eddy currents and power losses in the rotor of a screw electrothermomechanical converter for additive manufacturing

. Screw conveyors are widely used in the movement of various loose and lump materials related to agricultural production, such as: seed granular materials, cereals, bran, chaff, turf, flakes, mixed feed, mineral fertiliser pellets, etc. However, the conventional flexible screw conveyor operating mechanisms do not fully meet the operational requirements for these types of conveyors. Screw operating mechanisms are characterised by the complexity of the design and manufacturing technology, high material consumption, which causes increased energy consumption, damage to the transported material and the inner surface of flexible sleeves. Therefore, the task of developing new designs of flexible sectional screw operating mechanisms with advanced technological capabilities is urgent. To increase the reliability of the flexible screw conveyor, it was proposed to make its operating mechanism from separate screw sections that are pivotally connected to each other. Therefore, the purpose of this study is to determine the rational parameters and operating modes of the developed operating mechanism, which would ensure stable transportation of loose and lump materials on various technological routes. The study was conducted using the methods of differential and integral calculus, the theory of mathematical and computer modelling, mathematical planning of the experiment. This paper shows the results of theoretical and experimental studies of the process of transporting loose or lump material in the inactive zone between the pivotally connected screw sections of a flexible screw conveyor. The results of comparison of the obtained results of theoretical and experimental studies are shown. This allows choosing rational design, kinematic and technological parameters of the developed sectional screw operating mechanism when moving loose or lump agricultural materials along curved routes, both in horizontal and inclined directions, and along curved routes

Experimental and Theoretical Approach to the Extrusion of Rubber Compounds with a Two-Stage Screw**

AbstractThe extrusion of EPDM compounds with a two-stage vented screw has been studied. Experimentally, the pressures and temperatures were measured at the end of each stage, for different processing conditions (screw speed, die geometry etc.). Screw pulling experiments have allowed to observe the partially filling of the different screw sections. Assuming a power-law pseudoplastic behaviour for the rubber compound, the flow in each stage of the screw has been computed. The evolutions of the pressure and the temperature all along the screw, as well as the filling length of the second stage are then obtained. The theoretical results are in good agreement with the experimental measurements.

Morphology Development and Flow Characteristics during High Moisture Extrusion of a Plant-Based Meat Analogue.

Plant-based meat analogues that mimic the characteristic structure and texture of meat are becoming increasingly popular. They can be produced by means of high moisture extrusion (HME), in which protein-rich raw materials are subjected to thermomechanical stresses in the extruder at high water content (>40%) and then forced through a cooling die. The cooling die, or generally the die section, is known to have a large influence on the products’ anisotropic structures, which are determined by the morphology of the underlying multi-phase system. However, the morphology development in the process and its relationship with the flow characteristics are not yet well understood and, therefore, investigated in this work. The results show that the underlying multi-phase system is already present in the screw section of the extruder. The morphology development mainly takes place in the tapered transition zone and the non-cooled zone, while the cooled zone only has a minor influence. The cross-sectional contraction and the cooling generate elongational flows and tensile stresses in the die section, whereas the highest tensile stresses are generated in the transition zone and are assumed to be the main factor for structure formation. Cooling also has an influence on the velocity gradients and, therefore, the shear stresses; the highest shear stresses are generated towards the die exit. The results further show that morphology development in the die section is mainly governed by deformation and orientation, while the breakup of phases appears to play a minor role. The size of the dispersed phase, i.e., size of individual particles, is presumably determined in the screw section and then stays the same over the die length. Overall, this study reveals that morphology development and flow characteristics need to be understood and controlled for a successful product design in HME, which, in turn, could be achieved by a targeted design of the extruders die section.

Experimental study on magnesium wire–polylactic acid biodegradable composite implants under in vitro material degradation and fatigue loading conditions

This study investigated the fatigue life of biodegradable magnesium wire–polylactic acid (Mg/PLA) composite implants during the initial patient rehabilitation period under physiological loads through experimental and finite element methods. Under a simulated body fluid condition, the fatigue life was observed to be completely affected by material degradation, which accelerated the pitting corrosion of the composite bone plate. The mechanical behaviour of Mg/PLA composite bone plate was investigated under physiological loading conditions for the case of a tibial fracture with a 3 mm gap. A three-point bending fatigue test setup was employed to validate the fatigue characteristics of composite specimens. Finally, to alleviate the generated stress and enhance the fatigue resistance of fully biodegradable composites, a hybrid composite bone plate is proposed. At the screw section, the hybrid composite is partly composed of a comparatively more fatigue-safe non-degradable glass–polypropylene composite, which improves the healing performance of the fractured tibia.

Material Screw Testing ON Tail Rotor Drive Using 'D' Penetrant Testing Method

Non Destructive Testing is a method of inspection that used in aircraft maintenance. Penetrant test is one type of Non Destructive Test (NDT) which is applied to screw tail rotor drive material. The purpose of this study was to determine the presence of defects, cracks, or other discontinuities without damaging the object being tested or inspected. The design research of applying the penetrant test to screw tail rotor drive material containing ferrous (fe) used the 'D' method, which is by dipping the material into the penetrant liquid with a waiting time of 20 minutes, then cleaning it using water and an emulsifier and drying using an oven. Before the inspection is carried out, the material is sprayed with a developer with a waiting time of 10 minutes, then the material is checked for defects or not. The test results showed that there was no defect in the form of a crack, but found an indication that is included in the non-relevant indication, which is an indication of the shape or design of the material found in the screw section.

ANALYSIS OF THE OPERATING CONDITIONS OF THE TRIBO CONNECTORS OF SUBMERSIBLE SCREW PUMPS

The reliability indicators of the main units of the screw pumping unit are influenced by operational factors, therefore, the analysis of the operating conditions of the working parts of submersible pumps is carried out in the work. The main advantages of single-screw pumps lie in a wide range of their application in terms of the pumped liquid parameters. During testing of the submersible pump, the following breakdowns and failures took place: breakage of tubing at the wellhead at the base of the tapered thread; breakage of the screw from the thrust bearing; detachment of the locking device with a drain valve. The working process of the pump is determined by the interaction of its working bodies - the screw and the cage - in their relative motion. To analyze the workflow, the most common option is considered: a fixed cage and a planetary propeller. The kinematic pair «screw - cartridge clip» in each cross section can be represented in the form of two initial circles, one of which is rolled inside the other without sliding at a constant angular velocity. For continuous contact of a pair «screw - cage» and, consequently, to ensure the operation of the submersible pump, it is necessary to comply with the conditions for running in the initial circles and fulfill the necessary profiles of the helical surfaces. The cross section of the pump working bodies is considered from the point of view of their kinematics. The center of the screw section performs harmonic oscillations along the major axis of the yoke cross-section. The resulting torques and axial forces act only on the convex parts of the propeller, creating a vibrating vibration for it, which reduces its fatigue strength.

Dynamic characteristic analysis of vertical screw conveyor in variable screw section condition.

Vertical screw conveyors are used widely in industry for elevating bulk materials over relatively short distances, but the problem of insufficient feeding and low conveying efficiency always exist in the vertical conveying process. In this paper, a vertical screw conveyor with variable screw section is presented, and the characteristics of vertical screw conveyor are investigated under the variable screw sections using discrete element method (DEM). The results show that the particle volume fraction in the inlet and the mass flow rate increase in the condition of variable screw section, and the screw rotational speed has a significant influence on mass flow rate. It is evident that the design of variable screw section provides an effective way in improving the particle feeding rate and the conveying efficiency.

New production technology of screw sections by drawing

The development of engineering and technology necessitates the search for new solutions related to the release of innovative products with high added value, which include long-length cold-worked screw sections. An analysis of the methods for producing long screw profiles is made, as a result of which a new method is proposed that differs from the known methods by the absence of a twisting operation for forming a helical surface. This feature of the new method for producing long screw profiles simplifies the design of the device and reduces energy consumption. The influence of the workpiece diameter and the number of passes of the helical surface on energy consumption was studied, and a comparative schedule was constructed that proves the advantages of the proposed method for producing screw sections by drawing. For the strength analysis of equipment, a dependence is proposed by which the force that occurs when drawing long screw profiles can be found, taking into account the deformation conditions and design features of the device forming the screw surface. Using the fourth theory of strength, a dependence is obtained to determine the condition that guarantees the absence of breaks in the process of drawing a screw profile.

ДОСЛІДЖЕННЯ ПРОЦЕСУ ПЕРЕМІЩЕННЯ СИПКОГО МАТЕРІАЛУ В НЕАКТИВНІЙ ЗОНІ МІЖ ГВИНТОВИМИ СЕКЦІЯМИ

The article presents the results of theoretical and experimental studies of the process of moving bulk material in the inactive zone between hinged screw sections of a flexible screw conveyor. The influence of the gap between the edges of adjacent screw sections and the magnitude of their circular displacement on the process of continuous transportation of bulk material is presented. The results of theoretical and experimental studies are compared. This will allow choosing the optimal design, kinematic and technological parameters of the developed sectional screw working body when transporting bulk agricultural materials along curved paths, both in horizontal and inclined directions, as well as along curved paths.

Investigation of sectional operating elements for conveying agricultural materials

The paper covers the results of the theoretical and experimental investigation of the developed sectional operating element of a flexible screw conveyer designed for transporting bulk agricultural materials. In order to determine the correlation between the design parameters of the hinged screw sections and the minimum permissible radius of curvature of a processing line, the analytical dependences have been deduced. The results of the experimental studies aimed at determining the efficiency of a screw conveyer and the level of the grain material damage depending on the change in design, kinematic and technological parameters of an operating element are presented.

Failure mechanism and bearing capacity of vertically loaded pile with partially-screwed shaft: Experiment and simulations

An experimental and numerical investigation on performance of piles with partially-screwed shaft that were installed in sands was presented. Static load tests were conducted on a series of model piles to examine pile–sand interactions and the bearing capacity. The tested piles were varied in thread pitch in order to examine its effects on pile performance. Digital imaging correlations were used to visualise the failure slips of sands at locations of interest. The test results were used to validate a discrete element model (DEM) that was developed to assess the pile–sand interactions at micro-scale. The DEM model was applied to examine the effects of important pile geometric characteristics on the load transfer and bearing capacity of piles. The characteristics included the pitch, length of screw section, and shaft diameter. The simulation results suggested that the screw section and bottommost thread significantly influenced the pile bearing capacity. An optimum geometry of pile that maximised pile–sand interactions and prompted the pile performance was suggested.

Analysis of the bearing behaviour of a screw-pile foundation in silt soil

Screw-pile composite foundations have been widely implemented on multiple high-speed railways in China. Their distinctive design with variable sections makes the bearing behaviour of screw piles far more complex than that of common smooth piles. The bearing behaviour of a screw-pile composite foundation was analysed in silt soil on a national key construction project. A comparative analysis of the bearing characteristics of composite foundations of smooth piles and screw piles was performed through model tests. The results showed that, in a single-pile composite foundation and with the same pile diameter and length, the ultimate bearing capacity of the screw pile was 67% higher than that of the smooth pile. The smooth pile showed an area of negative frictional resistance at the top of the composite foundation. The screw pile had a negative friction area below the junction of the smooth section and the screw section in the screw-pile composite foundation.

Innovative method "DV-PIMS" technique and dental implant design for grafting injectable platelet-rich fibrin around the dental implant - Goat jaw cadaver study.

Dental implants have revolutionized the treatment modality for replacing missing teeth. The ability of implants to osseointegrate with the bone leads to its success. The problem is sometimes there is inadequate bone available for implant. If hygiene is not maintained, biofilms of bacteria can be formed around the dental implant. One approach to this problem has been development of bioactive surgical additives. Platelet-rich fibrin (PRF) appears as an alternative. There are various techniques of using PRF. These techniques need skill and practice to use PRF. To evaluate implant stability and flow of injectable PRF (i-PRF) of regular implant and modified innovative design implant. Thirty goat jaw bones were selected. Implants were placed in mandibular posterior region. Fifteen implants were placed using regular dental implant system (Group A) on the left side of jaw bone. The other 15 implants were placed using modified dental implant (Group B) on the right side of jaw bone. The body of these implants at middle has drainage vents to drain/flow the i-PRF-like dye. The dye was injected through regular and modified implants (DV-PIMS technique). Then the stability was checked with the help of Periotest. Cross section was taken 3 cm away from dental implant at the angle of mandible, to check the flow of i-PRF/platelet-rich plasma (PRP)-like dye. Periotest evaluation showed a mean of 2.3 for implant Group B and a mean of 1.5 for implant Group A. The flow of i-PRF-like dye was seen in Group B, and Group A does not show any flow. There are various techniques of using PRF. These techniques need skill and practice to use PRF. This (DV-PIMS) method aims to explain new implant design that disperses an i-PRF solution from inside out. The screw section of the new implant is made of a reservoir running vertically down inside. That reservoir is filled with (injectable) PRF, and then a cover screw is placed. The solution will begin to slowly diffuse out, through the vents in implant, keeping biofilms from forming or avoiding at the screw-bone interface and accelerate healing process.

New Designs of Sectional Screw Working Bodies

Screw mechanisms are widely spread in all areas of national economy of Ukraine. The creation of new designs of flexible screw working bodies is an up-to-date issue. The research considers the development of new designs of sectional screw conveyor flexible working bodies (section double connection of screw spirals and a section of flexible screw conveyor) and the raising their functional and operational characteristics, made with the individual sections, because the existing flexible screw working bodies may not fully meet performance requirements because of their high material consumption, high energy expenses and other requirements. It has been proved that the choice of screw working bodies’ design will depend, first of all, on the characteristics of the process and the load on the screw. Therefore, to ensure the design of producing joints equal in spirals, we can limit the number of design choices and offer a number of functioning structures of sections of flexible screw conveyors for transportation of granular materials on curved roads. The analytical dependences for determination of design parameters of conveyor flexible screw sections are determined in the paper. The results of the research are protected by declaration patent No. 123628 "Screw hinge-part working body." It benefits in the expansion of technological capabilities and reducing the radius of the track. The new designs of conveyor sectional flexible screw working bodies (SGGRO) have advanced technological capabilities that provide significant increase in operational reliability and durability, reduction of the radius of transportation track curvature, reduce in energy costs and increase in productivity

High moisture extrusion of wheat gluten: Modeling of the polymerization behavior in the screw section of the extrusion process

Thermomechanical treatment in the screw section of the extrusion process has a major impact on wheat gluten polymerization and subsequent structuring mechanisms that lead to the formation of anisotropic product textures. Therefore, this study presents a modeling approach that allows to predict wheat gluten polymerization at non-isothermal conditions by measuring material temperatures and temperature variations along the screws section. Since no study exists considering modeling of the reaction behavior of plant proteins during extrusion processing, the predictive accuracy of the non-isothermal approach was compared to another approach assuming isothermal conditions by measuring material temperature at die exit and mean residence time. Results show that the approach considering non-isothermal conditions significantly improved the predictive accuracy of wheat gluten polymerization as compared to the results from isothermal modeling.