Drawing Force Research Articles

Experimental analysis of the warm stamping of metal/thermoplastic polymer nanocomposite laminates

AbstractThe effects of matrix type, temperature, and weight percentage of nano‐reinforcement on maximum drawing force and drawing depth have been studied in warm stamping of reinforced metal/nanocomposite laminates. The laminates were composed of two thermoplastic polymers of glass fibers‐reinforced polypropylene and polyvinyl chloride, two reinforcements of nanoclay and multi‐walled carbon nanotubes as the core layer, and aluminum 1050‐O as the skin layer. Change of the matrix type from polyvinyl chloride to polypropylene increased the maximum drawing force and decreased the drawing depth. Besides, the drawing depth in most samples was decreased by increasing the weight percentage of the nano reinforcement. Increase of the temperature led to increasing the drawing depth and decreasing the maximum drawing force. Temperature had the greatest effect on the output parameters, especially the drawing depth.

Modeling and drafting process simulation of cotton slivers based on an octahedron structure

In order to study the variation of the drafting force of cotton slivers, a three-dimensional model of cotton slivers was proposed. The model is based on the three-dimensional network structure of the fibers in the cotton sliver. The three-dimensional network structure is simulated by an octahedron. Based on the similarity between dynamic drawing and static drawing, the static drawing simulation of the model is carried out by using ANSYS software, and the static drawing force of different quantitative cotton slivers is simulated. The results show that the average relative error of the static stretch force and dynamic drafting force is 8.09%, and the maximum relative error is less than 15%. Then, the equations of the dynamic drafting force and static stretch force are obtained by linear regression, and the drawing force under other quantitative conditions is successfully predicted. Finally, static stretching is used to simulate the influence curve of different roller spacings on the dynamic drafting force, and the results show that the simulation results are consistent with the actual situation. Therefore, the octahedral cotton sliver model is effective, and the simulation results also provide a reference for the approximate prediction of dynamic drafting force.

Influence of Semi Die Angle on the Forming Process of Ribbed Tube

Cladding tube is one of the key components in nuclear power reactor. In this paper, the forming process of a new cladding tube is investigated, namely ribbed tube. The influence of semi die angle on the forming process of ribbed tube is studied. Firstly, the strain-stress curves of 316L stainless steel (SS) at different strain rates are obtained. Based on the strain-stress curves, a modified Johnson-Cook constitutive model which ignore the influence of temperature are used, and the parameters of the modified model are determined. Then, the modified Johnson-Cook is used to establish the finite element (FE) model of ribbed tube drawing process, and two pass drawing process is adopted in this paper. Finally, the influence of semi die angle on the forming process (forming quality and drawing force) of ribbed tube is elucidated, and the credibility of the simulation is confirmed by comparing the simulation and experimental results. The results show that when the semi die angle less than 8 °, all the formed ribbed tubes meet the requirement, but there are inner grooves appear at the inner wall, and the inner grooves cannot be avoided in the drawing process. Moreover, when the semi die angle is 8 °, the inner grooves have smallest depth.

Computer intelligent dynamic simulation and optimization for structural platform of water treatment subsystem on the spacecraft

In order to reduce the load response condition of space-borne equipment, an optimized design scheme of carbon fiber composites sandwich panel was proposed in this paper. The state before and after optimization was analyzed and compared trough simulation calculation. The comparison shows that after the honeycomb sandwich structure was optimized, its fundamental frequency increased by 75%, the drawing force of embedded parts decreased by 50%, and the maximum acceleration response also decreased. Finally, the response under sinusoidal vibration was evaluated by test, and the results show that the optimization of the structure is reasonable and feasible, it can be the reference of other similar products.

The influences of the variable speed and internal die geometry on the performance of two commercial soluble oils in the drawing process of pure copper fine wire

The cold wiredrawing process constitutes a classical-tribological system in which a stationary tribe-element (die) is in contact with a tribe-element in relative motion (wire) and both interacting with the interfacial tribe-element (lubricant). This condition is reflected in the effect of friction as a function of the drawing speed and temperature, and directly affects the wearing of the surface into the die and the final quality on the drawn wire. The aim of this work has been to determine the best conditions to process ETP-copper using two different types of oil/water emulsion lubricants. For this purpose, six different die geometries have been proposed and a set of tests have been carried out at different speeds (between 1 and 21 m/s) to determine those combinations that give a lower value in the required drawing force (Fd). The experiments allowed to know the friction coefficient (µ), the temperature profile inside the drawing die and in the lubricant and also the mean roughness (Ra) in the drawn product. The results have shown that drawing speeds above 10 m/s significantly decrease the drawing force and, as a consequence, the friction effect on the interface. The best results have been achieved in the combinations of the lower die angle (2β = 14°) with drawing speeds between 17 and 18 m/s with both types of lubricants used, obtaining the lower values of the friction coefficient between µ = 0.10–0.15 with the lubricant type D (Agip S234-60 oil at 7% concentration). It has been found that those tests carried out with dies with a smaller approach angle have generally made it possible to obtain better qualities in the final product. Additionally, FEM simulations have been done to analyse those cases with the lower values of µ, throwing values of Fd that are consistent with those measured in the experimental setting and allowing to better understand the behavior of the material as it passes through the die.

Optimization and Mapping of the Deep Drawing Force Considering Friction Combination

Deep drawing is characterized by extremely complex deformation that is influenced by process characteristics such as die and punch shapes, blank shape, blank holding force, material properties, and lubrication. The optimization of the deep drawing process is a challenging issue due to the complicated functions that define and relate the process parameters. However, the optimization is essential to enhance the productivity and the product cost in the deep drawing process. In this paper, a MATLAB toolbox (Pattern Search) was employed to minimize the maximum deep drawing force (Fd-min) at different values of the operating and the geometrical parameters. As a result, a minimum deep drawing force chart (carpet plot) was generated to show the best combination of friction coefficients at the blank contact interfaces. The extracted friction coefficients guided the selection of proper lubricants while minimizing the deep drawing force. A finite element analysis (FEA) was applied through 3D model to simulate the deep drawing process. The material modeling was implemented utilizing the ABAQUS/EXPLICIT program with plastic anisotropy. The optimization results showed that the deep drawing force and the wrinkling decrease when compared with experimental and numerical results from the literature.

Study of rotating drawing process of wire rod based on slab method and FEM simulation with constant shear friction

The study based on the slab method and FEM simulation is to explore the wire rod drawing using rotating die. Constant shear friction is assumed at the interface between die and wire rod to explore different drawing conditions such as rotating angular velocity (ω), half die angle (α°), frictional factor (m) etc. on the influence of drawing forming characteristics. Besides, the die stress of rotating die occurred has been analyzed to realize whether the drawing die is failed or not. The axial stress, the radial stress, the drawing force, and the rotating torque can be obtained from the slab method to compare with the FEM, the error between the both models is around 8-10%. Moreover the realistic experiment is able to verify the acceptances of both models. Therefore through the study due to the rotation of drawing die, the drawing force can be reduced and the flowing of wire rod is increased.

Study on size effects in micro deep drawing of stainless steel foil

In this paper, the mechanism of processing parameters, such as lubrication conditions, grain size and foil thickness, on micro deep drawing (MDD) of stainless steel 304 (SUS304) foil has been investigated. The dry and glycerin-based nano-additive TiO2 lubricant with different concentrations were selected to study the effects of lubrication on MDD process. Four stainless steel samples with different thicknesses of 20, 30, 40 and 50 μm were employed in this study. Each foil was annealed under 950, 980 and 1050 °C respectively to obtain different grain sizes of the samples. The formed cups qualities in terms of surface roughness, wrinkling and earing defects were analysed, and the punch force-stroke curves and the stress-strain curves were studied in MDD. The experimental results show that 4.0 wt.% glycerin-based nano-additive TiO2 lubricant has the best lubrication effects due to its lowest drawing force and the better surface quality obtained, and the SUS304 foil with thinner thickness required smaller punch force, while the surface is more uneven in comparison with the thicker SUS304 foil. Moreover, the SUS304 foils annealed at lower temperature had smaller grains, and subsequently had smoother surface textures than those of SUS304 foils with larger grains annealed at higher temperature. The findings of size effects from lubrication, grain size and foil thickness obtained in this study will enhance the mechanism understanding of SUS304 foil deformation in MDD.

CLAIMS MANAGEMENT: UNDERLYING CAUSES IN MEGA-CONSTRUCTION PROJECTS

Construction claims remain unavoidable in any megaproject contractual relationship and can quickly escalate to misunderstandings, disputes and litigations if not appropriately managed. Disputes pose a significant risk in hindering project progress; they are characterised by lengthy legal battles that consume substantial time and financial resources. This study identifies the causes of claims encountered by clients, contractors and consultants in transport and energy sector mega construction projects in South Africa. A semi-systematic literature review was used to identify, select and appraise existing literature on this issue. Content analysis using NVivo 12 was used to identify factors causing claims in the construction sector, particularly in MCPs. Findings of the study revealed that construction projects occurring outside of South Africa experienced a delay in payments, time and cost overruns, change orders, inadequate project and drawing specifications, natural risks or force majeure. In South Africa, delays and cost overruns (due to insufficient experience and expertise of project managers and engineers) frequent to be the causes attributable to claims.

Research on Intelligent Fault Diagnosis of Servo Hydraulic Drawing Cushion

The drawing cushion of press line in the press workshop of the whole car factory has been extensively upgraded from air cushion to hydraulic drawing cushion. The hydraulic drawing cushion is more accurate than the drawing force of the air cushion, however, the hydraulic drawing cushion is a complex of mechanical, hydraulic, Motion Control and detection technology, and coupled with the press, which makes the fault diagnosis of the hydraulic drawing cushion more difficult. This paper mainly introduces the problems of the coordination among the three systems of mechanical, hydraulic and electronic control of Rexroth Company’s servo-hydraulic drawing cushion and its intelligent fault diagnosis method.

Study on the biomechanical analysis and influencing factors study for the treatment of humeral epicondylitis by Bachuorounian manipulation

To quantitatively study the biomechanical parameters of Bachuorounian manipulation in the treatment of humeral epicondylitis, and discuss the effects of individual characteristics on the biomechanical parameters were discussed. From July 2019 to February 2020, 40 patients with external humeral epicondylitis were selected, including 18 males and 22 females, ranging in age from 20 to 50 years old, with an average of (34.37±8.41) years old;and the course of disease ranged from 1 to 11 months, with a mean of (6.05±2.71) months. The biomechanical parameters of the elbow joint of the affected side were measured by using the biomechanical sensor. At thesame time, the individual characteristic parameters of patients were collected to analyze the influence of different individual characteristics of patients on biomechanical parameters. The results of mechanical analysis in each stage of the bachuorounian manipulation were as follows:the rolling back rotation force was (31.17±2.99) N;the buckling bending drawing force was (44.99±2.38) N;the rolling pre rotation force was (31.03±2.75) N;and stretching drawing force was (48.75±2.09) N. The correlation analysis between the parameters showed that there was a significant positive correlation between the buckling bending drawing force and the stretching drawing force parameters, and a significant positive correlation between the rolling force back-rotation force and the rolling pre-rotation force parameters. The multivariate linear regression analysis on the parameters of influencing factors and manipulative biomechanics showed that there was a significant correlation between body weight and rolling back-rotation force, significant correlation between elbow tenderness and the buckling bending drawing force, and significant correlation between disease duration and the stretching drawing force. The bachuorounian manipulation of humeral epicondylitis has a certain range of operating force. Manipulation of each stage has a correlation and systematic. The patient's weight, elbow tenderness and disease course are important factors affecting the bachuorounian manipulation.

Experimental Investigation on Mechanical Behavior of Anchor and Shotcrete Support System Under Axial Pull-Out Action

Based on axial pull-out performance tests of anchor and shotcrete support system with three types of plates and two kinds of shotcretes (plain and steel fiber reinforced concrete) conducted by use of the multi-functional testing system. The mechanical behavior of the anchor and shotcrete support system with the different plate and shotcrete such as the pull-out performance of support system, deformation and failure properties of shotcrete was studied and analyzed. Experimental results showed that the relationship curves between elongation and drawing force has three stages, which are elastic, yielding and hardening. Different plate types have obvious influence on the tensile stiffness during the elastic stage. The steel fiber reinforced concrete spray layer can improve the yield strength of rockbolt under the coupling effect by the support system. The strain at the interface between the initial shotcrete layer and surrounding rock mass is greater than that of the external surface of the resprayed shotcrete layer, though they are equal far away from the rockbolt hole. The shotcrete strain values of steel fiber reinforced concrete is lower than that of plain concrete, and the shotcrete strain values decreases with the improvement of steel fiber content. For shotcrete strain values on the same position, the higher they are the steel fiber content, the lower their strain will be. The failure of plain shotcrete usually begins around of rockbolt hole, when the interfacial stress between the initial shotcrete layer and surround rock is higher than that in the initial shotcrete layer and resprayed shotcrete layer. The steel fiber can effectively improves the toughness, anti-cracking performance and prevent fracture of shotcrete from failure properties. The research results can provide reference for the design and construction of anchor and shotcrete support structure in underground engineering.

Development of an automatic crack detection method for cupping tests on sheets and foils with a wall thickness below 0.1 mm

In deep drawing and stretch forming, in-situ crack detection is usually performed by detecting the drop in drawing force, by analyzing structure-borne sound or by reflected light methods. Friction, vibration, and machine noise are disturbance variables that prevent crack detection in thin sheets and foils using the first two methods and highly reflective as well as inhomogeneous surfaces prevent crack detection in the last method. In order to avoid the above-mentioned disadvantages of the existing crack detection methods, a method based on transmission-illumination was developed. Key to this new development is the use of a translucent punch, which incorporates a light source, and a camera connected to an image-processing unit. The detection process works as follows: the luminous punch penetrates the sheet and forms it accordingly. As soon as a crack is formed, light penetrates the crack and falls onto the image sensor of the camera. The image processing unit detects the jump in illumination and triggers the sudden stop of the forming process. Forming tests were performed that show the stable and operator independent performance of the newly developed detection process using sheet samples made from steel and aluminum.

To calculation of stresses in drawing of anisotropic viscoplastic material

Relations for calculation of stresses arising in the deformation zone during isothermal drawing without thinning the wall of cylindrical articles from a flat sheet blank are proposed. The stresses are determined by a joint solution of the equilibrium equations and plasticity condition for the plane stress state. The workpiece material is assumed to be transversely isotropic, the deformation is carried out under conditions of viscoplasticity. The deformation hardening and stress relaxation due to manifestation of viscosity of the material in the heating zone is taken into account. Tensile meridional stresses are defined as the sum of stresses in the workpiece flange, stresses caused by bending and straightening of the workpiece on the radial surface of the matrix, as well as friction on the planes of the clamp and the matrix. The received information on stresses in a flange allows to estimate power modes of drawing and damageability of workpiece material. On the basis of the obtained relations, the calculations of stresses and isothermal drawing forces for aluminum and titanium alloys at processing temperature of 450 and 930 оC, respectively, were performed. The dependences of the drawing force on the tool movement rate, which varied in the range from 1 to 10 mm/min, which corresponds to the viscoplasticity mode, are presented. It is established that in the given temperaturevelocity conditions the considered alloys show viscous properties that has considerable influence on the power mode of drawing. A comparison of the results of the force calculation with and without viscosity is performed. It is noted that the deformation degree, tool geometry and anisotropy of mechanical properties of the original material also have a significant effect on the drawing force. The obtained results can be used in design of processes for drawing workpieces from hard-to-deform aluminum and titanium alloys, which are used in aviation and space technology, the deformation of which is carried out under conditions of viscoplastic flow.The work was performed within the framework of the grant for state support of the leading scientific schools of the Russian Federation NSh-2601.2020.8.

Asymmetric shape of distal phalanx of human finger improves precision grasping

In morphology field, the functions of an asymmetric-shaped distal phalanx in human finger have only been inferred. In this study, we used an engineering approach to empirically examine the effects of the shape of distal phalanx on the ability of precision grasping. Hence, we developed artificial fingertips consisting of four parts, namely bones, nails, skin, and subcutaneous tissue, that substitute the actual human fingertips. Furthermore, we proposed a method to evaluate the grasping ability of artificial fingers. When a cylindrical object was grasped by an artificial fingertip, a pull-out experiment was conducted. Thus, the asymmetric type was found to be superior in terms of drawing force, holding time, and work of friction than the symmetric type. Our results clearly demonstrate that the asymmetric shape, particularly the mirror-reversed shape of the distal phalanx, improves the ability of precision grasping and suggests that the human distal phalanx is shaped favorably for object grasping.

Impact of Die Radius in a Streamlined Die during Wire Drawing

The effects of die radius in a streamlined die on design factors, such as the distribution of strain, stress, temperature, damage, and drawing force of a wire, were investigated during wire drawing for a better understanding of streamlined die and improvement in drawing quality of the wire. A numerical simulation was performed with the die radius of the streamlined die. The behavior of the design factors of the drawn wire fabricated by the streamlined die was different from that of the conventional die and was highly dependent on the die radius. The different behaviors of the design factors with the die radius can be explained by the frictional work and redundant work of the wire with die angle. The temperature rise and drawing force were high at a greater die radius because of the great frictional stress and heating effect stemming from the high contact length of the wire and die. Meanwhile, the higher redundant work at the surface area with decreasing die radius led to higher strain inhomogeneity, effective stress, damage value, temperature rise, and drawing force due to the abrupt change in the metal flow of the wire stemming from the high die angle. After the optimization of several design factors with die radius, it was concluded that the optimum IDR values ranged from 0.14 to 0.18, indicating that a streamlined die with a radius of 70 to 90 mm was the most suitable in the present process condition. In particular, the damage value of the wire was reduced in this range of die radii compared to the conventional die.

Evaluation of efficiency of methods for drawing round wire with large diameters

Drawing in monolithic draw dies is the primary and often nonalternative pressure metal treatment (PMT) method used in the wire manufacture for various purposes both in our country and abroad. Its effectiveness largely depends on the wire diameter and properties. Thus, when drawing wire of large diameters (>8.0 mm) from high-carbon steels (high-tensile reinforcing wire, spring wire, etc.), the stability of the process and the probability of metal fraction decreases. The use of classic roller draw dies increases the strain uniformity along the wire cross-section, reduces the force and multiplicity of drawing. However, the «circle-shaped section-circle» roller gauge system used in this process leads to a more complicated process, and most importantly, to a significant increase in production costs. In this paper, a comparative analysis of the drawing efficiency of a round billet with a diameter of 16.00 mm from steel grade 80 into a wire with a diameter of 14.25 mm (strain degree 21%) in one step in the classic monolithic draw die and roller draw dies: three-roller draw die with a spatially closed round gauge and three-roller draw die of radial shear strain. The latter is comparable to the well-known radial-shear rolling. The difference is that the energy is introduced into the deformation zone by applying a front pulling force, and the idler rollers rotate around the wire with a special drive. The authors used finite element modeling in the Deform-3d software package. The deformed state in processes with linear tensile strain was estimated by the distribution of the accumulated strain degree in the billet cross-section, and in processes with torsion – by the change in the curvature of the line applied to the side surface of the billet. The power parameters were determined in Deform-3d in the coordinates: drawing force – time of billet movement. The stress state was determined by the hydrostatic stress on the wire axis and the Cockcroft-Latham fracture criterion. It is established that the wire strain in a monolithic draw die is characterized by a significant strain inhomogeneity across the cross-section, monotonous flow, high energy consumption, and the wire collapsibility, especially of the mid-layers. The use of draw dies with a spatially closed round gauge reduces the drawing force by about 40%, reduces the degree of strain inhomogeneity along the cross-section, and increases the degree of accumulated strain. The radial-shear strain drawing significantly increases the degree of accumulated strain and provides grain grinding, especially in the surface layers of the wire.

A study of influence of hydraulic pressure on micro-hydromechanical deep drawing considering size effects and surface roughness

Micro-hydromechanical deep drawing (MHDD) is a promising micro-manufacturing technology to fabricate micro-metallic products in batch scale. Size effects significantly affect MHDD regarding both material properties and friction. Hydraulic pressure on the blank and its development differ from that in conventional hydromechanical deep drawing. Combined influence of fluid pressure, surface roughness and material inhomogeneity of the blank was investigated in this study via MHDD experiments and advanced FE simulation considering strong fluid-solid interaction (FSI) and size effects. The MHDD experiments under different hydraulic pressures were conducted using the annealed foil followed by the advanced FE simulation. The foil can be successfully drawn into micro-cups, however, wrinkles occurred under high hydraulic pressures. Wrinkle height and number are affected by hydraulic pressure and size effects. Average hydraulic pressure on the blank is lower than the inlet pressure, and pressure development on the blank depends on location and is complex, due to transition of sealing between the blank and die. The maximum drawing force increases, while the contact forces and pressures on the blank holder and die decrease with an increase of hydraulic pressure. Optimal hydraulic pressure for MHDD should be determined with consideration of size effects and MHDD tool geometry.

Manufacture of Narrow Thin-Walled Super Invar Pipe

The manufacture of thin-walled narrow pipe from 32NKD Super Invar alloy by drawing is studied. The drawing forces on the mandrel and the pipe blank are determined. The influence of the lubricant on the frictional forces is analyzed. The linear-expansion coefficient of the thin-walled pipe produced by drawing is compared with that of an undeformed sample of 32NKD alloy, as a function of the temperature.

Earing Reduction by Varying Blank Holding Force in Deep Drawing with Deep Neural Network

In the present study, we propose a novel method of varying blank holding force (BHF) with the segmental blank holder and investigated its influence on the earing reduction in the circular deep drawing process of an aluminum alloy sheet. Based on the analysis of cup height profile, the principle of varying BHF using segmental blank holder was presented and analyzed by analytical theory and numerical simulation. The optimal varying BHF was reasonably determined and compared by using the analytical model and deep neural network (DNN) model integrated with genetic algorithm (GA). The integrated DNN-GA model revealed an accurate prediction and optimization of varying BHF for the minimum earing height variation, which showed a superior result to the analytical model. The optimal varying BHF exhibited a significant influence on the earing formation, resulting in the noticeable decrease of earing height variation. For volume consistency, it was found that an increase in thickness at the cup wall region predicted with the optimal varying BHF was achieved in the transverse direction, which implies an improvement of deep-drawability. Such results indicate that the varying BHF is more reasonable and effective than the uniform BHF. Furthermore, the material properties of the blank sheet also affected the reduction of earing in the deep drawing with varying BHF. The present study revealed that the lower the material strength, the more significant the earing reduction in the deep drawing with varying BHF will be.