Spiral Extrusion Research Articles

Numerical Simulation and Optimization Design of Particle Transport in 3D Printers Spiral Extrusion 3D Printers

Abstract In response to the challenges of feed delay and inconsistent wire production in existing 3D printers, a novel 3D simulation model for spiral extrusion 3D printers was developed. This model incorporates the particle filling rate within the spiral groove as a critical evaluation criterion, establishing a correlation between the transport section parameters and the filling rate. The simulation software STAR-CCM+ was utilized for in-depth analysis, leading to structural optimizations based on various feeding mechanisms. The effects of different hopper models on feeding efficiency were investigated using the principles of the discrete element method. The findings indicate that the enhanced feed structure effectively addresses particle transportation issues within the printer. An increase in rotational speed is shown to improve the filling efficiency of the spiral groove, while simultaneously reducing the residence time of the particle material in the extruder, which in turn affects particle melting quality. By integrating the simulation data with experimental validation, an optimized printing structure was designed to fulfill the requirements of spiral extrusion printers.

Research Background and Mechanism of Soil Filling Pile with Spiral Cone Technology

This paper introduces the research background of soil filling pile with spiral cone technology. It is a new type of energy-saving and emission-reducing construction pile foundation design and construction technology. The foundation pile is a kind of soil filling pile with spiral cone which has the technical advantages of rotating extrusion cast-in-situ pile and bidirectional short spiral extrusion soil pile. At the same time, the mechanism is expounded. The soil compaction of the bit and the secondary diameter-retaining drill pipe is sufficient, the penetrating force is strong, and the geological conditions are widely adapted. The effect of the rock and soil around the pile on the pile is fully improved, thus the bearing capacity of the pile is increased and the construction cost is reduced. When calculating the vertical ultimate bearing capacity of a single pile, the value of the correction factor for the increase of the same rock and soil layer around the pile increases gradually from the soil displacement screw pile, rotating extrusion cast-in-situ pile and soil filling pile with spiral cone, and the vertical ultimate bearing capacity of the three piles increases sequentially.

Microstructure and Mechanical Properties of Aluminum/Copper Composite Rod Fabricated by Axisymmetric Spiral Extrusion

In the present investigation, an axisymmetric spiral extrusion was used for fabrication of bimetallic Al/Cu composite rods. In this process, a cylindrical bimetallic sample was extruded through an extrusion die having engraved spiral grooves to produce near net shaped composite part. After preparation of composite rods, the bonding strength was evaluated by applying shear stress on Al/Cu interface using compression test. Also the bonding interface was examined by optical metallography and scanning electron microscopy. The results showed that the bond strength increased in Al/Cu composite rods after spiral extrusion and the bonded interface was free of intermetallic layer. The stress imposed on interface region during spiral extrusion broke the work hardened layer in the mating surfaces, and consequently, the cold weld was established between virgin Al and Cu in the contact area. The obtained results showed a feasibility of spiral extrusion processing for production of Al/Cu bimetallic composite rods.

Spiral equal channel angular extrusion (Sp-ECAE) as a modified ECAE process

This research includes efforts to introduce a new severe plastic deformation (SPD) technique, entitled spiral equal channel angular extrusion (Sp-ECAE). In this operation, spiral grooves are provided in the inlet channel of equal channel angular extrusion (ECAE) process. Therefore, a cylindrical specimen twists about its centerline and experiences shear strain prior to the lateral extrusion in ECAE processing. Forming load required for lateral extrusion is much more than that for filling spiral grooves. Thus, the material follows such spiral paths throughout the process. In fact, the Sp-ECAE is modified based on axisymmetric forward spiral extrusion (AFSE) and the ECAE operations. The Sp-ECAE was experimentally conducted on AZ80 magnesium alloy at 200°C and with a ram velocity of 5mm/min. Then, both mechanical and microstructural improvements of the alloy were measured. Findings revealed considerable increase in the strength of alloy. The yield stress and the ultimate tensile strength were increased from 90 and 144MPa to 160 and 247MPa, respectively, denoting a 70% improvement compared to the as-cast state. The ductility was also increased from 2.65 to 3.18%. Moreover, the Sp-ECAE was capable of homogenizing and improving the microhardness from 76.5 to 108.5HV. Studies showed that more than 60% of the total increase in the microhardness was attained after the spiral region which indicates the effective role of this section of Sp-ECAE in improving the mechanical properties of AZ80. The average grain size was also decreased from 48 to 17μm, showing 64% refinement in comparison with the as-cast condition. Comparing such improvements with those achievable via ECAE and AFSE processes, shows significant efficiency of the Sp-ECAE process. Therefore, this process can be considered as an effective, novel SPD process.

Numerical Modeling to Determine Test Conditions of Shear Blanking Test for a Hybrid Material

A dedicated blanking test (DBT) was designed to measure the bonding shear strength of a metallic hybrid sample. To identify the required design parameters of the rig, a macro numerical model was developed using Abaqus Finite element (FE) package. Copper clad aluminum hybrid samples fabricated by an axi symmetric forward spiral composite extrusion (AFSCE) process were analyzed using the developed numerical model. The effect of the design parameters including sample thickness, blanking clearance and the die and punch fillet radii were determined to ensure a pure shear blanking along the interface. The numerical results showed that the sample thickness, clearance and fillet radii have a significant effect on the measured bond shear strength and the location of the failure. The required rig was designed and composite copper clad aluminum bonding shear strength was experimentally determined based on the numerical findings.

Numerical Simulation of Three Dimensional Flow Fields for Extrusion Process of GR-35 Double-base Propellant

Due to the instability of materials and the screw's rotation friction, it will be dangerous in the screw extrusion process of solid propellant. Because there were so much nitroglycerin and solid part in GR-35 double-base propellant, it was more difficult in spiral extrusion for this important propellant than others. In order to solve this problem, the Polyflow software was used to simulate the spiral extrusion process of GR-35 in this paper. Then four parameters (the temperature, the pressure, the shearing rate and the velocity) were analyzed at the axial direction (Z=0.02 m and Z=0.08 m). Then, these parameters of Z direction were analyzed by a line near the arris. According to the results, no matter the value of temperature, pressure, shearing rate or velocity, was larger in screw arris position. In addition, the values of temperature and pressure will increase as the extrusion processes while the velocity and the shearing rate will decrease. The simulated results can be used to optimize the technological in the process of screw extrusion of solid propellant and decrease the risks in process.

A comprehensive 3D analysis of polymer flow through a conical spiral extrusion die

Several restrictions which are related to extruder machinery and nature of process material exist in the design of plastic extrusion dies. To this respect, it is very important to consider design criteria and limitations in order to operate extrusion dies at desired production rate and temperature. In the current study, flow field characteristics through a conical spiral mandrel die are analysed in detail by 3D Computational Fluid Dynamics (CFD) simulations. The effects of operating conditions such as production rate and temperature on pressure drop through the spiral mandrel die and the occurence of melt fracture are investigated. The temperature dependent viscosity versus shear rate data for grade QB79P (CarmelTech) polypropylene (PP) melt under study are measured by use of rotational and capillary rheometers. Stress terms in the momentum equations are modeled by Generalized Newtonian Fluid (GNF) Model. For this, Bird-Carreau Model is employed as the viscosity model for the polymer melt. 3D CFD analyses provide comprehensive data and understanding with regard to flow behaviour through complex extrusion dies.

Multiple pass axi-symmetrical forward spiral extrusion of interstitial-free (IF) steel

Mechanical property changes and microstructure evolution after multi-pass axi-symmetrical forward spiral extrusion (MPAFSE) on Ti-IF steel were studied. Torsion tests on the samples processed by the MPAFSE indicated that the process has improved the yield and ultimate tensile strength at the expense of the material ductility. Existing analytical and experimental studies of the AFSE proved a radial gradient of deformation for a single pass AFSE. However, it will be shown here that in the MPAFSE, the hardness distribution becomes homogenized after 4-pass of deformation which is due to “the friction induced deformation” during the process. Also, Electron Back Scattered Diffraction (EBSD) assessments of the processed samples revealed the effect of shear deformation during the MPAFSE on the formation of low angle grain boundaries (LAGBs) the intensity of which is proportional to the number of the MPAFSE passes. Based on the EBSD observations, the homogenization of material after the MPAFSE can also be correlated to the saturation of microstructure/LAGBs after successive passes of deformation. The texture analysis, in plane normal to the extrusion direction, suggested that despite the texture development during MPAFSE, the subsequent mechanical properties were not considerably affected.

Spiral extrusion of aluminum/copper composite for future manufacturing of hybrid rods: A study of bond strength and interfacial characteristics

An axi-symmetric forward spiral composite extrusion (AFSCE) method is proposed to produce hybrid rods. This process involves extrusion of a composite sample through a die with engraved spiral grooves to create a near net shape product. The process can be easily performed and has better dimensional control than the existing bimetallic rod fabrication processes because of the zero shape change effect of this process. An analytical solution of shear deformation during AFSCE in the radial direction of the hybrid sample is first presented. To demonstrate the production of composite rods using the process, an experimental case study of an Aluminum and Copper (Al/Cu) sample at elevated temperature and in the presence of a back pressure is presented. Microstructure characterizations of the Al/Cu interface and the neighboring regions revealed the formation of a bonded layer with the possibility of intermetallic compounds present at the interface. Composite blanking proved good bonding strength between the parent materials. The results show that the AFSCE process has strong potential to be utilized for the fabrication of hybrid metal rods.

Finite element analysis of plastic deformation in variable lead axisymmetric forward spiral extrusion

A modified axisymmetric forward spiral extrusion (AFSE) has been proposed recently to enhance the strain accumulation during the process. The new technique is called variable lead axisymmetric forward spiral extrusion (VLAFSE) that features a variable lead along the extrusion direction. To assess the effect of design modification on plastic deformation, a comprehensive study has been performed here using a 3D transient finite element (FE) model. The FE results established the shear deformation as the dominant mode of deformation which has been confirmed experimentally. The variable lead die extends strain accumulation in the radial and longitudinal directions over the entire grooved section of the die and eliminates the rigid body rotation which occurs in the case of a constant lead die, AFSE. A comparison of forming loads for VLAFSE and AFSE proved the advantages of the former design in the reduction of the forming load which is more pronounced under higher frictional coefficients. This finding proves that the efficiency of VLAFSE is higher than that of AFSE. Besides, the significant amount of accumulated shear strain in VLAFSE along with non-axisymmetric distribution of friction creates a surface feature in the processed sample called zipper effect that has been investigated.

A study of plastic deformation during axisymmetric forward spiral extrusion and its subsequent mechanical property changes

Axisymmetric forward spiral extrusion (AFSE) accumulates large strains in its sample while extruding it through a die with engraved spiral grooves. A three-dimensional finite element model of AFSE has been developed using ABAQUS to investigate the deformation mode in detail, including the effect of groove geometry and the heterogeneity of plastic deformation. The numerical results demonstrated that the strain distribution in the AFSE sample cross section is linear in the radial direction within a concentric core while the distribution, outside the core, in the vicinity of the grooves is non-linear and non-axisymmetric. Mechanical properties and grain structure changes of the deformed sample were investigated. Improvements of mechanical properties in the processed samples can be attributed to the domination of the shear deformation mode in a plane normal to the extrusion axis and consequently the elongation of grains in the tangential direction.

Research on a Vertical Settlement Type Dehydrator with Spiral Sieves

This article designed a kind of dehydration device using spiral sieve for solid-liquid separation of coal slime water. The device based on the spiral feeding extrusion, using the materials own gravity to achieve solid-liquid separation, so as to realize the continuous material feeding. Due to the mutual extruding of the material, spiral sieve and spiral rotor, the device has the following advantages: less work cycle, continuous feeding, easy for application and maintenance, reliable work, less repair point and low maintenance costs.

Review on modified and novel techniques of severe plastic deformation

This review highlights very recent achievements and new developments of severe plastic deformation (SPD) technology for producing bulk ultrafine-grain (UFG) and even nanocrystalline (nc) materials. These numerous modified and novel SPD methods include cyclic forward-backward extrusion, axi-symmetric forward spiral extrusion, vortex extrusion, simple shear extrusion, planar twist extrusion, tubular channel angular pressing, cone-cone method, high-pressure tube twisting, tube channel pressing and elliptical cross-section spiral equal-channel extrusion. According to classification, these new methods are categorized into the extension of equal-channel angle pressing (ECAP), high-pressure torsion (HPT), twist extrusion (TE) and constrained groove pressing (CGP), respectively. The principles of various new SPD technologies are described in detail. In addition, the microstructure revolution characteristics and mechanical properties of materials produced by SPD process, as well as the applications of SPD techniques to UFG materials, are also reported. Furthermore, this article reviews recent progresses in determining the refinement and/or deformation mechanisms, e.g. dislocation deformation mechanism, twin deformation mechanism and grain boundary sliding and torsional deformation mechanism, and further orientation of SPD technology.

A kinematics study of variable lead axisymmetric forward spiral extrusion

Variable lead axi-symmetric forward spiral extrusion (VLAFSE) allows far more efficient strain accumulation than constant lead counterpart AFSE. It eliminates the rigid body rotation of the sample in an AFSE die which only causes frictional loss and has no contribution to the deformation. Based on a proposed velocity field, the kinematic formulation for VLAFSE is presented, utilized to predict strain components in the deformation zone and compared with experimental measurements. A simple closed form solution of the VLAFSE problem is presented which describes the flow of material inside the extrusion die. The results confirm that the effective strain of the process accumulates non-linearly in the both radial and extrusion directions.

Upper-bound analysis of axi-symmetric forward spiral extrusion

An axi-symmetric forward spiral extrusion process, AFSE, has been analyzed using the principle of the virtual work rate. Based on an existing kinematically admissible velocity field, an upper bound solution has been developed for the new forming process. The solution also provides estimation of the die reaction torque during the process. AFSE experiments were conducted with lead specimens in order to verify the upper-bound solution. A reasonable agreement between experimental results and the upper bound solution was observed. The upper bound analysis indicated that both deformation in a small zone next to the velocity discontinuity plane and the frictional power constitute the most significant parts of the consumed power, respectively, during AFSE. As a result, reduction in friction will lead to a dramatic decrease in the total forming force in AFSE while maintaining a circumferentially slippage free flow of material during the process. It was shown that by increasing the die helix angle above a critical value, the rate of growth in the die reaction torque and extrusion load with the helix angle increases dramatically.

Finite Element Analysis of an Axi-Symmetric Forward Spiral Extrusion of Mg-1.75Mn Alloy

A potential severe plastic deformation process known as axi-symmetrical forward spiral extrusion (AFSE) has been studied numerically and experimentally. The process is based on the extrusion of cylindrical samples through a die with engraved spiral grooves in a near zero shape change manner. The process was simulated using a three dimensional finite element (FE) model that has been developed using commercial software, ABAQUS. In order to verify the finite element results, hot rolled and annealed samples of the alloy were experimentally processed by AFSE. The required extrusion forces during the process were estimated using the FE model and compared with the experimental values. The reasonable agreement between the FE results and experimental data verified the accuracy of the FE model. The numerical results indicate the linear strain distribution in the AFSE sample is only valid for a core concentric while the strain distribution in the vicinity of the grooves is non axi-symmetric. The FE simulation results from this research allows a better understanding of AFSE kinematics especially near the grooves, the required extrusion force and the resultant induced strain distribution in the sample. To compare the mechanical properties of the Mg-1.75Mn alloy before and after the process, a micro shear punch test was used. The tests were performed on samples undergoing one and four passes of AFSE. After four passes of AFSE, it was observed that the average shear strength of the alloy has improved by about 21%. The developed finite element model enables tool design and material flow simulation during the process.

Axi-symmetric forward spiral extrusion, a kinematic and experimental study

A modified axi-symmetric forward spiral extrusion process has been proposed here to allow for a near zero area reduction process. The axi-symmetric forward spiral extrusion, AFSE, can be carried out through a die with a number of engraved spiral grooves. This paper investigates the kinematics of the AFSE process. A velocity field is derived using principle of mass conservation along the extrusion axis. The proposed model has been developed to calculate strain components in the deformation zone during the process. An experimental method has been designed which uses composite lead samples with embedded copper wires to trace the strain path to verify the proposed velocity field. A good agreement between experimental results and the proposed analytical model was observed. The proposed velocity field, verified by experimental results, shows that the deformation develops away from the AFSE die–sample interface. A linear gradient of velocity in the radial direction was observed which is in good agreement with the proposed velocity field. Based on the estimated strains, velocity gradient, and nearly no change in sample cross section during AFSE, the process seems to have good potential for application as a new severe plastic deformation process in both continuous and batch modes.

内面螺旋溝付き押出し管の成形

The spiral extrusion processing method that forms an inner spiral multi-grooved tube by hot extrusion is proposed. The spiral extrusion processing method is a compound die extrusion method that installs a rotary plug at the exit of the die mandrel of porthole dies. In this paper, the effects of extrusion conditions and rotary plug shape on groove torsion angle, section groove angle and groove depth in the inner spiral multi-grooved tube are investigated. As a result, a good inner spiral multi-grooved tube is formed in which extrusion temperature and extrusion ram speed are low. Even if the working height of the rotary plug increases, only the outer diameter of the extruded inner spiral multi-grooved tube increases, and therefore, it is understood that the predetermined inner spiral multi-grooved tube is not provided.