Vibration Extrusion Research Articles

Longitudinal–torsional ultrasonic vibration–extrusion tapping of small blind holes in Ti-6Al-4V with large length-to-diameter ratio

Longitudinal–torsional ultrasonic vibration–extrusion tapping of small blind holes in Ti-6Al-4V with large length-to-diameter ratio

Effect of ultrasonic vibration extrusion cutting on the corrosion resistance of ultra-fine grained strips

Ultrasonic vibration extrusion cutting (UVEC), a new processing method, is proposed to prepare ultra-fine grained materials with better corrosion resistance. The mathematical models, finite element simulations, and experiments are combined and validated against each other to investigate the mapping relationships and influence mechanisms among ultrasonic amplitude, stress field parameters, microstructure, and corrosion resistance. It is found that with the increase of ultrasonic amplitude, the equivalent strain, equivalent strain rate, grain refinement degree of strip and thickness of a nanocrystalline surface layer on the side of the strip in contact with a tool (front side) increase gradually. The immersion corrosion test shows that both sides of the strip have better corrosion resistance than original matrix, and the corrosion resistance of the strip front side is better than that of strip side in contact with the extrusion block (back side). The electrochemical corrosion test shows that with the increase of ultrasonic amplitude, the electrochemical parameters are improved. It is determined that the corrosion resistance of ultra-fine grained strips prepared by UVEC is significantly improved compared with the original matrix, and the overall corrosion resistance is best at 2 μm ultrasonic amplitude.

Mechanical properties of ultra-fine grained strips under ultrasonic vibration extrusion cutting

Ultrafine grained materials often have superior mechanical properties. In order to complement the advantages of other preparation methods of ultrafine materials, a new process of ultrasonic vibration extrusion cutting was proposed to induce severe plastic deformation of materials to prepare ultrafine grained strips with superior mechanical properties. The mathematical model, finite element simulation and cutting test were combined to validate each other. The mapping relationship and influence law among process parameters, physical field parameters, microstructures and mechanical properties were studied. After ultrasonic vibration extrusion cutting, average grain size of material was refined from tens of microns to ultra-fine grain level. With the decrease of extrusion ratio, thickness of nanocrystalline surface layer, degree of grain refinement, average microhardness and tensile strength of strip increase gradually. When extrusion ratio is 1.2, 1.5, 1.8 and 2.1, thickness of nanocrystalline surface layer is 52.9 μm, 44.1 μm, 26.5 μm and 22.8 μm, respectively. Compared with original matrix, average internal microhardness of strip is increased by about 39.9%, 37.6%, 32.8%, 24.1%, and tensile strength is increased by about 306.9%, 273.7%, 254.1%, 240.9%, respectively.

Preparation and mechanism of copper ultra-fine grain strip by ultrasonic vibration extrusion cutting-model, FEM and experiment

Ultra-fine grain materials are widely used due to their superior material properties. In presented work, ultrasonic vibration extrusion cutting (UVEC) is put forward to prepare ultra-fine grain strip. UVEC induces material to produce strain and strain rate far exceeding that of ordinary severe plastic deformation process. The mathematical model and finite element simulation model of physical field parameters was established. UVEC test platform was set up to verify each other with previous model. Relationship and mechanism among processing parameters, physical field parameters and microstructure changes were analyzed, mechanism of grain refinement in UVEC was revealed. The results show that the grain size can be refined to ultra-fine grain size by UVEC method. With the increase of tool rake angle, the strip equivalent strain/equivalent strain rate decrease gradually, and the grain refinement weakens gradually. Besides UVEC, ordinary turning (OT) and ordinary extrusion cutting (OEC) tests are also carried out. The average grain size of UVEC-strip (0.75 μm) is about 3/4 that of OEC-strip (1.03 μm). The passivation layer depth of OT-strip (38 μm), OEC-strip (58 μm) and UVEC-strip (75 μm) increases gradually.

An Improved Surface Treatment Process of 304 Stainless Steel Based on Low-Temperature Chromizing and Ultrasonic Vibration Extrusion

The ultrasonic vibration extrusion process is a widely used surface treatment process of stainless steel, e.g., 304 stainless steel, to improve the surface quality and increase hardness and wear resistance. However, for high-hardness 304 stainless steel, the traditional process, i.e., a single ultrasonic vibration extrusion process, does not fulfil its application requirements. To cope with this problem, this paper proposes an improved surface treatment method based on low-temperature chromizing and ultrasonic vibration extrusion to obtain the expected surface quality of 304 stainless steel. Using orthogonal design and multivariate regression, the influence of ultrasonic impact parameters on the surface integrity of 304 stainless steel was studied in this work. Finally, the experimental results show that the hardness of the surface processed by the proposed method is increased by about 2.55 times compared with the ultrasonic vibration extrusion process, and the surface roughness of the composite process is reduced by an average of 60.8% compared with that of unfinished surface. In addition, the optimal combination of process parameters is obtained: the spindle speed of 240 rpm, the feed of 0.1 mm/r, and the static extrusion of 40 μm, which can provide the optimal process parameter support for the surface treatment of 304 stainless steel.

A new surface vibration extrusion process for surface densification and improvement of properties in powder metallurgical steel

Selective surface densification (SSD) can greatly improve the mechanical properties of powder metallurgical (P/M) parts with low additional costs. This work proposes a new surface vibration extrusion process to make up for some drawbacks of the existing SSD processes as far as possible. The surface densification effect and mechanism, as well as mechanical properties of the surface extruded P/M Fe-Mo-Cu-C steel with and without vibration assistance, are comparatively investigated. Following a small surface extrusion processing via a simple extrusion die, the surface of the vibration extruded P/M steel is more thoroughly and uniformly densified under a lower extrusion load when compared with the directly extruded P/M steel. This can be attributed to the vibration assistance facilitating the dislocation motion and metal flow. The high surface-densified layer is achieved, with depth up to 530 μm slightly superior to some commercial SSD parts. Moreover, approximately twice the surface hardness is obtained compared with the hardness before the extrusion. Lastly, superior friction and wear properties are achieved. Results indicate that surface vibration extrusion can be used as a promising process for the surface densification of P/M parts.

Vibroextrusion flow of concrete mixtures in a right four-corner pyramidal channel

The purpose of the research was to obtain calculation formulas for describing the flow of concrete mixtures and determining their viscosity directly in the process of vibroextrusion in regular quadrangular pyramidal channels.
 In solving the flow problems, it was taken into account that concrete mixtures are non-Newtonian systems in the conditions of a vibration field, and hydrodynamic theories were used to calculate the processes and rheological characteristics.
 Since the calculation formulas for describing the flow of fluids in a regular quadrangular pyramidal channel are absent and the channel has a square cross section, an analytical dependence was used to characterize the process, which describes the flow of a Newtonian fluid in a rectangular channel of constant cross section. The authors proposed for use simplified formulas for determining the maximum flow rate and flow rate of a Newtonian fluid in a channel of rectangular cross-section.
 The degree of decrease in the flow velocity and the flow rates of a Newtonian fluid in a channel of rectangular cross-section in comparison with the flow between flat parallel plates are analyzed.
 To describe the flow of concrete mixtures in regular quadrangular pyramidal channels, the proposed coefficients for reducing the speed and flow rate, as well as the existing formulas for the flow between flat symmetric stationary walls, which converge, were used.
 The possibility of using the obtained formula for the flow rate in a regular quadrangular pyramidal channel for calculating the viscosity of a concrete mixture during vibration extrusion is shown. To simplify the experimental procedure, a new formula for calculating the viscosity based on the expiration time for a certain amount of concrete mixture has been proposed.
 The formulas obtained are convenient for further mathematical processing and have no restrictions in their application. The proposed method for determining the viscosity expands the possibilities of studying the rheological properties of concrete mixtures in the vibroextrusion of fiber-reinforced concrete mixtures.

Semi-analytical torque modeling of Ti-6Al-4V-alloy internal trapezoidal thread extrusion forming with an emphasis on low-frequency torsional vibration

Abstract Conventional cold extrusion is generally considered to be less practical for trapezoidal threads, requiring a relatively large form tapping torque. The machining of it is always based on cutting, but the actual demands of high strength and long life have brought this process to its limits. These requirements drove the present work, which proposes a new process for the fabrication of a Ti-6Al-4V-alloy trapezoidal thread using low-frequency torsional vibration extrusion (LTVE) through a forming tap. A semi-analytical model of torsional vibration extrusion with friction was established by solving the problem of mechanical friction and slip-line field. The influence of low-frequency torsional vibration on the form tapping torque was studied, and the total amounts were determined quantitatively. The conclusion shows that the total tapping torque was composed of the positive pressure load and the friction load on the forming tap. The friction load was generated by the tool/workpiece friction, which is the largest component, accounting for more than 90 %. The introduction of vibration can reduce the friction in the thread form tapping so as to obtain high rheological properties, which is applicable for the low-frequency stage. Finally, a mechanical LTVE tapping excitation device was proposed based on this process method, and an experimental prototype that can meet the requirements of titanium alloy trapezoidal thread machining was developed. Experimental verification indicated that the LTVE forming process had reduced the total form tapping torque. It also proved the method’s overall reliability and effectiveness and the underlying insights needed to guide the thread manufacturing.

Experimental study on the forming process of spline by frequency and amplitude modulated axial vibration extrusion

The change rule of forming force and the load-restraining mechanism of vibration machining during the extrusion process of spline under low frequency vibration were studied. Using the frequency modulated and amplitude modulated vibration extrusion forming machine developed by our research group as the experimental equipment, a forming force measurement system was built to measure the change of forming force during vibration extrusion spline, and the data were analyzed. The results show that the forming force is mainly related to the amplitude of vibration, especially the retreat stroke. When the retreat stroke is large enough, the friction between the die and the workpiece stretches the workpiece to the yield stage and immediately reverses the extrusion. Because of Bauschinger effect, the forming force decreases significantly. In addition, good lubrication conditions can effectively reduce the forming force and the instantaneous retreat of the die. When the material deformation zone is opened, the lubricant enters, which reduces the friction between the material and the die, thus reducing the forming force. The experimental results show that for extrusion forming of involute external spline with 0.47 modulus and 36 teeth, the forming force decreases by 27% when the frequency is 10 Hz, the forward travel is 1.38 mm and the backward travel is 0.67 mm, and the load reduction effect is remarkable.

Distributional analysis of residual stresses with the Ti-6Al-4V internal trapezoidal thread torsional vibration extrusion

The aim of this study is to actively explore the quantitative measurement of residual stress of trapezoidal internal threads after extrusion processing. In this paper, innovative stress test specimens of the Ti-6Al-4V alloy disc with a diameter of 86 mm and a thickness of 20 mm were designed, and vibration extrusion tapping was carried out with a Tr14*2 extrusion tap in the center of the disc. Then, based on the elastic principle and the linear superposition principle, the incremental slicing method or crack flexibility method was applied to retrieve the residual stress distribution from the strain measurement. The stress distributions along the axial direction of the threaded hole and along the tangential and normal directions of the threaded hole were measured. The redistribution law of internal residual stress of extruded internal threaded parts was explored and studied, which provides a basis for studying the fatigue resistance of materials. In addition, the three-dimensional finite element method was used innovatively to calculate the stress flexibility factor of circular pie specimens with finite boundary constraints as not used the previous two-dimensional plane strain approximation.

Experimental study on mix proportion and the strength of law-grade magnesite hollow block

In this paper, the properties of test block and hollow block made of low-grade magnesite is analysed and studied. First, in order to get the results, the X-ray diffraction analysis was carried out on the phases composition of low-grade magnesite. Then, the influence is researched successively by orthogonal experimental design of water consumption, water-cement ratio, sand ratio and building gypsum on the compressive intensity of test block which can get the best Mix. Finally, the optimum mix ratio of magnesite hollow block is obtained by using the vibration extrusion method to prepare the traditional size distribution concrete hollow block, and the strength relationship between magnesite hollow block and traditional block is solved by linear regression equation. The conclusions shows: compressive strength of hollow block presents a tendency that decreased first and then increased, and strength ranks of all first group hollow blocks exceed MU10.

Ways of increase of efficiency of process of the vibroextrusion of fibrous concrete

The process of mixing the components of the mixture is an important factor affecting the physical and mechanical properties and appearance of the final product. The proposed designs of vibroexcluders for mixing fibrous concrete and the formation of flat products provided analytical formulas for calculating the process of vibration extrusion.
 The quantitative criterion of laminar convective mixing, which occurs when vibroexclusion, is the degree of increase in the surface area of the interface between the components, which in turn depends on the total deformation and initial orientation of the surface.
 The constructions of vibroextruders are provided for the mixing of a fibrous concrete and forming flat products, and analytical formulas are given for the calculation of the vibroextrusion process.
 The construction of a cascade vibrating extruder for the proposed mixing can be applied to a wide range of compositions of fibro concrete mixes, and a specially designed vibratory extruder for forming can significantly improve the longitudinal orientation of dispersed fittings in flat products.
 The degree of longitudinal orientation of the fiber in the process of vibroexclusion of fiber concrete can be regulated by the geometry and size of the channels of the vibroexcutter bunker, as well as by the application of special guiding partitions.
 Practically the degree of mixing is characterized by the speed of vibration exclusion. Due to the fact that the vibroextrusion mixing does not occur the destruction of fiber reinforcement, as a result of the successive passage of the mixture through several channels, the moment when the vibration excursion velocity stabilizes.
 The given analytical dependencies give the possibility of quantitative description of differences in the deformation of the mixture and the final orientation of fibers in the products for the proposed apparatus. The degree of longitudinal orientation fibers need to be set separately for different products, depending on their purpose, and change the degree of orientation is carried out by changing the geometry of the vane bunker vibroextruder.
 The results of the work are supposed to be used in the design of a new vibration excretory equipment for mixing fibrous concrete mixtures and the formation of dispersed reinforced products.

Experimental Investigation on GCr15 Steel for Marine Vessels Treated by Ultrasonic Assisted Equal Channel Angular Extrusion

Wang, X. and Yu, Y., 2018. Experimental investigation on GCr15 Steel for marine vessels treated by ultrasonic assisted equal channel angular extrusion. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 548–551. Coconut Creek (Florida), ISSN 0749-0208.ECAE deformation refines grain via large shear deformation. Ultrasonic assisted plastic deformation can reduce flow stress of the material and reduce the friction coefficient, etc. In this paper, ultrasonic is applied to the ECAE deformation process, and impact of ultrasonic assisted ECAE forming process on microstructure and mechanical properties of GCr15 steel for marine vessels is studied. The results show that: With ultrasonic assisted ECAE process, ultrafine-grained material can be obtained, compared with the case without ultrasonic vibration extrusion, for GCr15 steel for marine vessels microstructure, average grain size of cementite is 10μm; the sample underwent ECAE one-pass extrusion, with extrusion force at 11098 N, one-pass extrusion force of UV-ECAE was 10090 N, with extrusion force reduced by 9% compared to before; microhardness without ECAE was 365 HV, but significantly increased to 580 HV after ECAE and significantly increased to 620 HV after ultrasonic assisted ECAE, up by 70% compared with that before extrusion.

VIBRATION EXTRUSION OF FLAT FIBER-REINFORCED CONCRETE PRODUCTS WITH MAINLY LONGITUDINAL ORIENTATION OF FIBERS

For the production of high-quality fiber-reinforced concrete slabs, the authors proposed a new design of the vibration extruder with a guide device in the form of a deltoid. The improved device allows the use of fibrous concrete mixes of different compositions, thus achieving mainly longitudinal orientation of fibers throughout the product. The technique of calculating the degree of orientation of fibers during the flow of fibro concrete mix in the channel of the vibration extruder bunker and in the finished flat product is proposed. The influence of the geometry of the forming channel on the location of the disperse fittings in the product is determined. The program was developed and the results of calculating the location of fibers in a flat plate with a thickness of 40 mm are given. The results of the work are supposed to be used when designing a new vibration extrusion equipment for the manufacture of fiber-reinforced concrete products.

Study on Slow Crack Growth Resistance of High-Density Polyethylene Pipes Prepared by Vibration Extrusion

The slow crack growth resistance is one of the key factors to improve the service life of the plastic pipes. The high-density polyethylene (HDPE) pipes were prepared using a self-made electromagnetic dynamic plasticating extruder, which applied a vibration force field to the entire plasticating and extrusion process by the axial vibration of the screw. The slow crack growth resistance of HDPE pipes prepared by static extrusion and vibration extrusion was investigated. The effects of the vibration force field on the slow crack growth resistance of HDPE pipes were studied by DSC and WAXD analysis. The results showed that HDPE pipes prepared by vibration extrusion had higher melting temperature, higher crystallinity, larger crystal sizes, thicker lamellas and more perfect crystals. At the same time, the quasi net structure of the HDPE pipes chains can be obtained. All these are favorable for the improvement of the slow crack growth resistance property HDPE pipes.

Study on the Design of a Preload Adjustable Ultrasonic Vibration Extrusion System

A preload adjustable new ultrasonic vibration extrusion system was designed based on one-dimensional theory of elastic, moreover, the vibrator also has passed simulation analysis tested by Ansys. The influence of the flange structure to the resonance vibration mode of the vibrator was proposed. Finally its vibration performance was verified by impedance characteristic test and conformed to the processing requirement.

The Design and Simulation of Vibrate Impact Extrusion Die

As conventional technique of cold extruding process face the problems that the equipment must provide large extrusion force during the workpiece extruding process, it has huge flow stress of the material and the frictional force between the mould and blank against the material flow under room temperature. To solve these problems, this article put forward a cold extruding mould with vibration. By simulation analysis of conventional and vibration of cold extrusion of travel load and velocity field, the force of vibration extrusion is reduced by 54% than that of conventional cold extrusion; therefore the forming surface of the parts and the material flow speed of vibration cold extrusion is greatly improved

Numerical Simulation and Die Design for Vibration Extrusion of Spur Gear

The numerical simulation for spur gear vibration extrusion is performed in this paper. The metal flow characteristic and load-stroke relationship during forming process is analyzed and then compared with traditional metal extrusion process. The results revealed the axial vibration of cavity die can both reduce forming load and benefit for metal flow, which could achieve better forming quality. Finally according to the processing requirements, the vibration generator and whole extrusion die structure is designed.

Effect of Vibration Extrusion on Mechanical Properties and Structure of HDPE/OMMT Nanocomposites

A vibration technique was applied in extrusion molding of HDPE 6100M/OMMT nanocomposites. The results from the study suggest that samples obtained by vibration extrusion were strengthened effectively. The maximum increase percentage of tensile strength at 180°C and 200°C reached 25.14% and 21.43% respectively. It was found from microscopic structures measured by DSC, WAXD and SEM that the crystalline grains of polyethylene matrix became fine, that the orientation degree of crystalline increased and that crystallinity became perfect under the vibration field. Moreover, vibration can make nano-OMMT disperse more homogeneously in the HDPE matrix.

Using Artificial Neural Networks in Investigations on the Effects of Ultrasonic Vibrations on the Extrusion Process

Neural Networks are powerful data modeling tools that are capable of capturing and representing complex input/output relationships. The motivation for the development of neural network technology stemmed from the desire to develop an artificial system that could perform "intelligent" tasks similar to those performed by the human brain. Using artificial neural network in approximating of complex data is one of easy way to save time and cost. Ultrasonic vibrations can be applied on the die during the extrusion process. Numerical and experimental analyses have been already performed in the literature on the application of ultrasonic vibrations on the wire drawing, deep drawing, upsetting and rolling processes. No attempts have been made to investigate on the effects of ultrasonic vibrations on the forward extrusion process, yet. A detailed analysis and understanding of the mechanism of improvement is not possible on the basis of conventional experimental observations because ultrasonic vibration processing phenomenon occur at high speeds. Hence, in order to progress the perceptive of the mechanism of ultrasonic vibration extrusion, the finite element analysis was performed by using the explicit analysis procedure. The proposed approach builds on a comprehensive Neuro-Finite Element simulation of the effects of ultrasonic vibration on the forward extrusion. Then use the resulting data to train a Multi-Layer Perceptron (MLP) Neural Network which would predict –accurately enough- those quantities throughout the speeds, vibration amplitudes and frequencies, friction factors and reductions body for any given input vector. The resulting neural simulator is intended to replace the computationally expensive cost-function evaluators that are traditionally used in numerical optimization algorithms. To demonstrate the applicability of the proposed approach, we examine data from FEM as from training with together ultrasonic vibration using the constructed neural simulator and present the results.