Tube Drawing Research Articles

Evolution of deformation texture in cold drawing of steel tubes using EBSD analysis and FEM simulation

Cold drawing of steel tubes is the manufacturing process characterized by anisotropic material flow during drawing. In this paper, the micro structural of the E235 steel tube after recrystallization annealing and cold drawing were characterized by optical microscopy and EBSD (Electron BackScatter Diffraction) analysis performed on a scanning electron microscope. The input feedstock after recrystallization annealing with dimensions of ø 25.0 mm × 1.5 mm (O.D × W.T.) was cold drawn in two drawing passes with fixed plug to the final dimensions of ø 18.0 mm × 0.9 mm (O.D × W.T.). The development of crystallographic texture (both qualitative and quantitative) was analysed on a longitudinal section of the tube. The stress-strain state in the tube material during drawing was calculated by FEM (Final Element Method) software and the development of the texture depending on the stress-strain state in three different directions using cylindrical coordinates with respect to the drawing direction was evaluated. We have investigated the ratio of individual crystallographic planes depending on stress state during drawn tube. The main objective was to define the development of crystallographic grain orientation from stress-strain state during cold drawn tube.

Agreement between blood draw techniques for assessing platelet activation by flow cytometry

It is widely believed that assays of platelet activation are susceptible to preanalytical variables related to blood draw technique. We assessed platelet activation by whole blood flow cytometry and investigated the effects of: (1) drawing blood into vacuum tubes or manually aspirated syringes, and (2) discarding the first drawn blood sample (discard tube). Platelet P-selectin expression and platelet-monocyte complexes were measured by flow cytometry under both basal conditions and following stimulation with 0.1, 1, or 10 µM ADP. Bland-Altman plots demonstrated agreement between results for vacuum tube and syringe-aspirated samples with an a priori-defined clinically relevant agreement limit of 5%. Agreement of results was also observed between discard tube and second draw samples for both vacuum-driven and manually aspirated blood. We conclude that a vacuum tube or a manually-aspirated syringe can be used when assessing platelet activation by flow cytometry and that there is no need for a discard tube.

Determination of the Optimal Reduction Ratio for Least Springback during Cold Drawing of Seamless Tubes

Cold drawing process is one of the most used metals forming processes in industries for forming seamless tubes. This process of plastic deformation of metals occurs below the recrystallization temperature and is generally performed at room temperature. When metal is cold worked, upon the release of forming force, the springback occurs. In this paper, the springback effect of the seamless tube that has undergone cold drawing is studied for three different reduction ratios viz.10-15 %,15-20 %, and 20-25 % having the aim to reduce it. Experiments are conducted under different reduction ratios with working conditions of die semi angles of 10 and 15 degrees, die land width of 5 mm and 10 mm as well as drawing speed of 4, 6, and 8 m/min for C-45 tube material. Optimum reduction ratio is finalized using Statistical Package for Social Science (SPSS) software of data analysis using statistical tests like Kruskal-Wallis, ANOVA, Post-hoc, etc. Metallurgical analysis through microstructural investigation, XRD and mechanical testing via cold draw load, and hardness testing for different reduction ratios are also studied for validation purposes. The results of this research show that 10-15 % reduction ratio yields the minimum springback. This can be used to help designing tools in the metal forming industry to minimize springback and improve the quality of the product.

Miniaturized tube fixed plug drawing: Determination of the friction coefficients and drawing limit of 316 LVM stainless steel

Tube drawing with a fixed plug is investigated experimentally and numerically in order to optimise an industrial pass sequence. Tube drawings are performed on a laboratory drawing bench equipped with force, displacement and temperature sensors. The drawing limit of 316 LVM stainless steel (SS) tubes is determined by varying the plug position and the effect of lubricant is discussed. The numerical model relies on the precise die geometry measured using a contact method and on the mechanical behaviour of SS 316 LVM characterised by tensile tests between 20 °C and 200 °C on annealed tubes. The friction coefficients between tube and die and tube and plug are determined by FE modelling by comparing measured and simulated plug, die and drawing forces. The use of a solid lubricant together with the lubricating oil prevents stick and slip and lowers the friction coefficients. Friction is further decreased by preheating the die. The identified friction coefficients are discussed in terms of the classic Stribeck friction curves and lubrication is found to be in the hydrodynamic regime.

Finite element modelling of cold drawing for high-precision tubes

Cold tube drawing is a metal forming process that allows manufacturers to produce high-precision tubes. The dimensions of the tube are reduced by pulling it through a conical converging die with or without inner tool. In this study, finite element modelling has been used to give a better understanding of the process.This paper presents a model that predicts the final dimensions of the tube with very high accuracy. It is validated thanks to experimental tests. Moreover, five studies are performed with this model, such as investigating the influence of the die angle on the drawing force or the influence of relative thickness on tube deformation.

Determination of the Coefficient of Friction Under Cold Tube Drawing Using FEM Simulation and Drawing Force Measurement

Abstract The purpose of this article is to describe the methodology to define coefficient of friction between a tool and a forming material during tube cold draw technology process. In this regard, an experimental drawing process was done by using the tensile testing machine. The tensile testing machine was modified by additional equipment that allows drawing the tube. During the drawing, the force was recorded. Subsequently, the finite element simulation of cold draw forming was used to generate load-stroke curves with different friction coefficient. The friction coefficient was estimated by comparing the load stroke and the force recorded curves.

Rheology-based approach of design the dieless drawing processes

Dieless drawing process is based on local heating and simultaneously controlled stretching of the workpiece and allows elongation of the workpiece without using a deforming die. This process is usually used for deformation of wires, tubes and bars. The disadvantage of the dieless drawing process is the unevenness of the product diameter along its length. The present paper shows that unevenness can be substantially reduced by dividing the process into several stages. After each stage complete recrystallization of the material must be guaranteed for restoration of plasticity. The value of the strain in each stage must correspond to the area of intensive hardening on the stress–strain curve of the processed material. Thus, the proposed approach is based on the use of the special features of rheology properties of the material. The proposed approach was validated on the example of laser dieless drawing of magnesium alloy tubes.

Development of a Constitutive Model for Friction in Bulk Metal Forming

This paper presents a systematic procedure for the development of a constitutive model of friction with focus on the application in bulk metal forming simulations. The empirically based friction model describes friction as a function of sliding distance and the most relevant friction influencing parameters. The latter were determined by means of designed experiments. An optimal friction model is obtained as a trade-off between model accuracy and complexity by using stepwise nonlinear regression and a modified version of the Akaike information criterion. Within this study, the procedure is applied to determine a friction model for tube drawing. However, the same approach can also be used for modeling friction of any other bulk metal forming process.

Experimental and numerical analyses of residual stresses induced by tube drawing

Lightweight constructions are used to fulfil the ever-increasing demands regarding fuel efficiency and carbon dioxide emission in transportation industries. In order to reduce weight, technical components made of solid materials are often replaced by tubular structures. Under service conditions, the components are frequently exposed to cyclic loads. Hence, residual stresses that are induced by manufacturing processes can have a significant impact on service life. In this work, the focus is on tube manufacturing processes, precisely cold tube sinking and fixed plug drawing. Both processes induce characteristic residual stress states, which are important to assess the mechanical integrity and load-carrying capacity of tubular components during service. The aim of this article is to examine the residual stress depth distribution for medium-carbon steel tubes manufactured by cold tube sinking and fixed plug drawing. The residual stresses are measured by means of the Sachs method and the hole-drilling method, respectively. The measured results are compared to finite element simulations of the tube drawing process. It is shown that the residual stress obtained with the different experimental methods and the numerical simulations are consistent. Furthermore, it is shown that the residual stresses can be significantly reduced when a plug is used in the drawing process.

Effect of young’s modulus on springback for low, medium and high carbon steels during cold drawing of seamless tubes

Cold drawing is widely used deformation process for seamless tube manufacturing. Springback is one of the major problem faced in tube drawing. Springback is due to the elastic energy stored in the tubes during forming process. It is found that this springback depends upon Young’s modulus of the material. This paper reports mechanical testing of three grades of steels viz. low carbon steel, medium carbon steel and high carbon steel to measure their Young’s modulus and corresponding springback. The results shows that there is 10-20 % variation in the Young’s modulus and inverse proportion between the springback and Young’s modulus. More the percentage of carbon, more the strength, less the value of Young’s modulus and more will springback. The study further leads to identify optimum die semi angle of 15 degree, land width of 10 mm and drawing speed of 8, 6 and 4 m/min for least springback in all the three grades respectively and die semi angle as a most dominant factor causing springback.

Comparison of Measurement Methods to Acquire the Steel Tubes Characteristics

The main paper idea was compared three methods (Contact CenterMax and contactless ATOS TripleScan II, Metrotom 1500) for data acquisition to the output characteristics of steel drawing tubes. Outer and internal diameters, eccentricity and ovality were measured. Steel tubes produced by drawing should accomplish shape and dimensional characteristics. These can be measured by various contact and contactless methods. Each of these methods have advantages and disadvantages. The computed tomography advantages are, that we obtain both outer and inner tube shapes. Output is a 3D model from which you can get the elements to evaluate the characteristics. The data acquisition is limited by wall thickness and material density and that is disadvantage. The 3D scanner advantages are, that we obtain outer tube shapes with different diameters and wall thickness regardless of material density. Output is a 3D model. Problem is to obtain data about complex internal shape limited by tube length and diameter and that is the disadvantage. The advantage of acquiring data by contact method is that we obtain both external and internal tube shape, without thickness wall, diameter or material density limitation. The disadvantage is that we don´t obtain a 3D model of tube, but only a spot-scanned elements.

Optimum curved die profile for tube drawing process with fixed conical plug

Wide applications of tube drawing process with using a fixed conical plug in manufacturing of thin-walled tubes have convinced the researchers to investigate and optimize this process in the past years. Current study deals with presenting an optimum curved die profile utilized in tube drawing process with fixed conical plug. Minimizing the required tensile stress in the process as well as reducing the stress which is applied to the die and plug has been considered as objectives of this study. Considering work-hardening behavior of material, the drawing stress of the process is analyzed based on incremental slab method theory. In addition to, plain strain condition is applied through the thin-walled tube. Furthermore, the obtained optimum die profile has also been simulated using ANSYS Workbench 18.0 and the results were compared with those of analytical method. It is found that the die profile could be determined based on the mechanical properties of the workpiece, reduction of cross section area, plug angle, and coefficients of friction. Results demonstrate that by applying an optimum die profile, the required tension stress in tube drawing process could considerably be reduced comparing to the same process with conical die profile.

Numerical simulation of cold drawing of steel tubes with straight internal rifling

In heat exchangers, steel tubes with straight internal rifling bring several benefits to the heat transfer process. However, production of such tubes by cold drawing brings considerable challenge in meeting strict dimensional criteria on a rifling geometry. Optimization of the whole production process naturally involves a numerical simulation of cold drawing, saving time and costs of pre-production plant trials. The key aspect of a multi-rifled tube production is the proper creation of internal rifling via gradual filling of plug grooves during drawing. It is this very mechanism where the benefit of numerical simulation steps in, providing us with qualitative and quantitative estimation of important state variables. In this article, four hollows have been compared as an input feedstock for cold drawing of Ø25.4 × 2.11 mm multi-rifled tube. The calculated state variables in a feedstock material (i.e. stresses, strains, and strain rates) uniquely determine the material flow during drawing. The results of numerical simulations helped us find the most suitable input hollow for given tube dimensions while meeting customer’s strict dimensional tolerances on internal rifling. Additional tasks involved optimizing the axial position of the plug inside the die.

Integrated computational material engineering model development for tube drawing process

In order to be able to understand the tube drawing process in a better way and also to analyze more complex situations, multiscale simulation approach based on the Integrated Computational Materials Engineering was used and an FEM model was developed. The responsibility of this model was to get the eccentricity and residual stresses of the tubes before the drawing process and simulate the same parameters and their variations during the drawing. For simulation, the multiscale methodology based on the idea of Integrated Computational Materials Engineering was used to study the process. The main reason for using the multiscale simulation methodology was to study plastic behavior of the material in the FEM model considering texture of the material.

Guidelines for Selecting Plugs Used in Thin-Walled Tube Drawing Processes of Metallic Alloys

In this paper, some practical guidelines to select the plug or set of plugs more adequate to carry out drawing processes of thin-walled tubes carried out with fixed conical inner plug are presented. For this purpose, the most relevant input parameters have been considered in this study: the tube material, the most important geometrical parameters of the process (die semiangle, α , and cross-sectional area reduction, r ) and the friction conditions (Coulomb friction coefficients, μ 1 , between the die and the tube outer surface, and μ 2 , between the plug and the tube inner surface). Three work-hardening materials are analyzed: the annealed copper UNS C11000, the aluminum UNS A91100, and the stainless steel UNS S34000. The analysis is realized by means of the upper bound method (UBM), modelling the plastic deformation zone by triangular rigid zones (TRZ), under the validated assumption that the process occurs under plane strain conditions. The obtained results allow establishing, for each material, a group of geometrical parameters, friction conditions, a set of plugs that make possible to carry out the process under good conditions, and the optimum plug to carry out the process using the minimum amount of energy. The proposed model is validated by means of an own finite element analysis (FEA) carried out under different conditions and, in addition, by other finite element method (FEM) simulations and real experiments taken from other researchers found in the literature (called literature simulations and literature experimental results, respectively). As a main conclusion, it is possible to affirm that the plug that allows carrying out the process with minimum quantity of energy is cylindrical in most cases.

Effects of the semi die/plug angles on cold tube drawing with a fixed plug by FEM for AISI 1010 steel tube

Bu calismada, sonlu elemanlar analizi kullanilarak, sabit mandrel ile soguk boru cekme isleminin benzetimi yapilmis olup, kesit daralma oraninin, yari kalip acisinin, yari mandrel acisinin ve surtunme katsayilarinin cekme gerilmesine etkileri arastirilmistir. Sonlu elemenlar modeli, %16 kesit daralmasindaki deneysel verilerle dogrulanmistir. Netice olarak, yari kalip acisinin plastik sekil degisimine etkisi yari mandrel acisindan daha buyuk olmustur. Sebebi ise kalip acisinin buyuklugunden kaynaklanmaktadir. 12o’lik yari kalip acisi butun surtunme degerleri icin minumum cekme gerilmesini vermektedir. Sabit konik mandrel ile boru cekme isleminde 7o’lik yari kalip acisi icin 2-4o araligindaki yari mandrel acisi kullanilmalidir. Deneysel ve sonlu elemanlar analiz sonuclarinin uyum icinde oldugu gorulmustur.

Corrosion News

Corrosion News

The technology of cold drawing of seamless steel tubes using numerical simulation

The technology of cold drawing of seamless steel tubes using numerical simulation

The Influence of Temperature and Strain Rate on Flow Stress of Steel 10CrMo9-10 used for Drawing of Tubes

The Influence of Temperature and Strain Rate on Flow Stress of Steel 10CrMo9-10 used for Drawing of Tubes

Compare of the Dies and They Influence of Geometry Precision of the Cold Drawing Tubes with Small Dimensions

Compare of the Dies and They Influence of Geometry Precision of the Cold Drawing Tubes with Small Dimensions