Cold Drawing Of Tubes Research Articles

A statistical approach in the FEM simulation analysis of geometrical product specification during the cold tube drawing process

The cold drawing process produces high-quality tubes with precise dimensions, good surface quality, and higher strength due to cold forming. The tube drawing is used to reduce the cross section of the produced tubes. Depending on the reduction size, the outer diameter and wall thickness of the final tube changes. Due to the fact that cold drawing of tubes is mostly the last operation of production, it is necessary to pay attention to the process parameters and geometry of the forming tools. This paper presents a statistical evaluation of the influence of the wall thickness of the pre-tube, die diameter, and pre-tube diameter on the measured responses, which were the outer diameter and wall thickness of final tube, after the FEM simulations of the drawing process. For these purposes, a factorial design with three input factors was implemented. The goal of using the simulations was also to investigate whether the single-pass type of tube drawing would guarantee useful statistical results that could lead to significant time and cost reductions. The FEM simulations were executed using DEFORM software of Scientific Forming Technologies Corporation with Design of Experiment application module of this software. A factorial design of experiment has been processed in Minitab v. 17 software. The results show that most of the factors significantly influenced the response variables.

The effect of ultrasonic vibrations on residual stresses and material properties of steel tubes during the cold tube drawing process

ABSTRACT In this study, the ultrasonically assisted plug vibrating tube drawing system was developed for an industrial draw bench and investigated using experimental and finite element (FE) modelling. The effect of ultrasonic vibrations on the induced residual stresses on the drawn steel tubes is evaluated using the mechanical and X-ray diffraction (×RD) method. The results indicate that the distribution of induced residual stresses mostly shows compressive stresses under ultrasonic vibrations. In contrast, the residual stresses are tensile in nature for conventionally drawn tubes, which are not very desirable. The experimental results show 11% reduction in draw load, while the FE analysis shows a 13% reduction in draw load, which indicates that the experimental and FE results are in good agreement. In addition, the effect of ultrasonic vibrations on the tensile strength, yield strength and percentage elongation is investigated and compared with samples from conventionally drawn tubes. The ultrasonic-assisted tube drawing has resulted in favourable tensile properties, which helps in improving the formability limit of the tubes. The Von Miss stress distribution obtained indicates that the ultrasonically assisted drawing results in a more uniform and lower Von Mises stress when compared to conventionally drawn tubes.

A Statistical Approach in the Analysis of Geometrical Product Specification during the Cold Tube Drawing Process

Cold tube drawing provides higher accuracy compared to hot approaches. The process can be used to reduce the dimensions of tubes, and depending on the reduction size, the wall thickness of these may be subject to changes. In the process, any form of variability provoked by external factors is highly sensitive, given that the resulting tubes are often the final step in tube production. This paper focused on the evaluation of the influence of pre-tube factors on key variables after the drawing process, i.e., the final roundness, outer diameter, and wall thickness of the tubes. For these purposes, a factorial design with fixed factors was implemented. It was also a goal to investigate if the single-pass type of drawing would guarantee good statistical results potentially leading to significant time and financial reductions. The measurements were executed in the machine ZEISS CenterMax. The statistical analysis took place on Minitab 19. The results prove that most factors, and their interactions, significantly impacted the response variables, leading the authors to understand that a single-pass approach would not properly work under the conditions defined for the experimentation. These results also allow for reflection on the causes and necessary measures related to lubrication, technological heritage, and quality that would impact the results themselves.

Texture Evolution during Cold Drawing of Steel Tube with Respect to the Stress - Strain State

Cold tube drawing is a metal forming process that enable to manufacturers to produce high precision tubes. The dimensions of the tube are reduced by drawing it through a conical converging die with or without inner tool. There are four types of tube cold drawing process. Their difference relies on the technique used for inner diameter calibration. Therefore, the main objective was determining the difference in development of crystallographic texture and stress-strain state between drawing with the fixed plug and hollow sinking process. The input feedstock (with E235 steel grade) after the recrystallizing anneal was cold drawn (drawing with the fixed plug, hollow sinking) by one drawing passes. Electron BackScatter Diffraction (EBSD) analysis was used to evaluate the changes of grain structure and texture connected with tubes manufacturing. The stress-strain state in the tube material during drawing was calculated using DEFORM-3D software and the crystallographic orientation with respect to the cylindrical reference frame (Z-direction = drawing direction). A significant difference in stress-strain state between drawing with the fixed plug and hollow sinking process was recorded in radial direction.

A new development of measurement technique for residual stresses generated by the cold tube drawing process with a fixed mandrel

The residual stresses during the cold tube drawing process affect the quality of the final tube products significantly. In this study, a new development of measurement technique that is built on the removing layer method (RLM) is developed to measure the axial and the hoop residual stresses (ARS, HRS) inside the tube wall for AISI 1010 steel. The tube is produced by the cold tube drawing process with a fixed straight mandrel (fixed plug). The RLM by milling process is performed on the inner and the outer surfaces of the tubes while the tee rosette strain gages (TRSGs) are fixed at the inner and the outer tube surfaces respectively for strain measurements. An axisymmetric finite element model (AFEM) based on explicit dynamic analysis is also performed to predict the ARS and the HRS within tube thickness. The experimental and finite element results are compared with variable X-ray diffraction (XRD) results. It is found that the results are in good agreement and the RLM is proved to be one of the appropriate methods to measure residual stresses inside the tube wall. The results showed that residual stresses present inside the tube wall are completely different by different reduction of areas of R = 16 and 23%.

Simulation of rifled tubes drawing process

Presented paper is focused on knowledge in the field of tube drawing process. The introduction consists of summarizing the current state of the art. In the material and methods section, it is a characteristic of the usability of rifled tubes for heat exchangers, which serve to better heat exchange between the medium and the tube. The following section describes the implementation of the experiment. This section shows the principle of pipe drawing using a grooved mandrel and a die. The result section is showing resulting a simulation of strength analyzes and the recorded values during the pulling tests. In conclusion, the aim of this paper is briefly explained, as well as the need to take into account the leading part of the mandrel, which may result in incorrect geometry and cavitation. In conclusion, the issue is mentioned, which is beneficial for science and research in the field of cold drawing of tubes. It is also about knowledge with internally shaped surface in energetic equipment.

Evaluation of strain in cold drawing of tubes with internally shaped surface

Abstract Presented article is focused on strains acting in cold forming process of drawing tubes with shaped internal surface. At present, mathematical simulation, tools make it possible to significantly shorten the deadlines for pre-checking the possibilities of very complex processes. Pulling pipes with an internal shape with a broken surface is a complex problem with many deformation zones. The principle of the shape of the broken pipes is very similar to pulling smooth pipes. In the process, the same dies as the drawing of smooth pipes are used. Courses of total and axial strain describe the transformation of an object from an initial state to the final shape of the tube

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.

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.

Experimental and finite element analysis of residual stresses in cold tube drawing process with a fixed mandrel for AISI 1010 steel tube

Cold tube drawing with a fixed straight mandrel (fixed plug) is one of the major drawing process in tube drawing operations. Although the process has high dimensional accuracy and good surface finish in general, the process parameters have significant effects on part quality. Therefore, an accurate finite element model is extremely important to improve part quality and reduce the cost of the part. In this article, a cold tube drawing with a fixed straight mandrel is studied experimentally and numerically for AISI 1010 steel tube. Two different reduction of areas of 16 and 23% are considered. X-ray diffraction (XRD) method is used to determine hoop residual stresses inside the tube wall at five different orientations. The experimental models are validated successfully with finite element analysis (FEA) by correlations of the compression force vs. the displacement and the residual stress vs. the position. Effect of the drawing parameters on the hoop residual stress is studied by an axisymmetric finite element model. Although the reduction of area strongly affects the residual stress compared to other process parameters, the friction coefficient has minimum effect on residual stresses. This study concludes that the residual stress states inside the tube wall produced by cylindrical and conical plugs are completely different.

A conical mandrel tube drawing test designed to assess failure criteria

Cold tube drawing is a metal forming process which enables to produce tubes with high dimensional precision. It consists in reducing tube dimensions by pulling it through a die. Tube outer diameter is calibrated by a die and the tube inner diameter and thickness are calibrated by a mandrel. One of the major concern of metal forming industry is the constant improvement of productivity and product quality. In the aim of pushing the process to the limit the question is how far the material can be processed without occurrence of failure. In the present study, a long conical mandrel with a small cone angle was designed in order to carry out drawing tests up to fracture with experimental conditions very close to the industrial process. The FEM of the process was built in order to access the local stress and strain data. A specific emphasis was put on the friction characterisation. For that purpose force measurement during the conical mandrel experiments enabled to characterise a pressure dependent friction coefficient constitutive law by means of an inverse analysis. Finally, eleven failure criteria were selected to study the drawability of cobalt–chromium alloy tubes. The assessment of failure criteria based on damage variables or damage accumulation variables involved their calibration on uniaxial tensile tests. The experimental studies were completed by SEM fractography which enabled to understand the fracture locus and the propagation direction of the fracture.

Effect of Drawing Tubes without Interoperation Recrystallization Annealing on the Orientation of Boundaries Grain - Orthogonal Direction

The term cold-drawing of tubes refers to forming when the final material (a tube) is formed in a pipe bell and its vertical cross-section is smaller, the tube wall is thinner or thicker and its length is greater. Steel is most commonly the final material. The forming proceeds in a few draws which depend on the final tube dimension. The selection of relative reduction for particular diameters plays an important role because an unbalanced reduction causes stress, and therefore also deformation or cracks during drawing. The technological parameters are: rolling temperature, de-burring of tube ends, the reduction, which determines the dimensions of the forming tools, the optimal chemical modification, the speed of forming on the drawbenches, and the method of tube drawing.

Die shape design of tube drawing process using FE analysis and optimization method

The cold tube drawing has been generally regarded as an effective technology because of its high productivity and low production costs. It has been used instead of the swaging process to form monobloc tube shafts (MTSs) with a constant outer diameter or hollow shafts without defects. MTSs are used nowadays to reduce the weight of shafts and to improve power transmission in the auto industry nowadays. The objective of this study was to design an optimal die that can prevent material fracture considering critical damage value in the tube drawing process. To achieve this objective, a finite element simulation and the flexible polyhedron search method are used. The drawing die shape is represented by the Bezier curve that is able to generate all the possible die shapes. The tube drawing experiments were carried out using the optimized tool. In the experiments, it was possible to produce sound products without fracture.

Numerical Analysis of Cold Tube Drawing Operation using Finite Element Method

In this paper the effect of semi die angle on drawing load in cold tube drawing has been investigated numerically using the finite element method. The equation governing the stress distribution was derived and solved using Galerkin finite element method. An isoparametric formulation for the governing equation was utilized along with C0 cubic isoparametric element. Numerical experimentation showed that the results obtained using the present method is very close to the analytical solution and more accurate than finite difference solution. Having established the accuracy of the present solution method, parametric studies were carried out to show the effect of semi die angle on the drawing load for different tube drawing processes. The analysis was carried out using a Visual Basic.Net program developed by the authors. The results are presented in both graphical and tabular forms.

A study on monobloc tube drawing for steering input shaft

Abstract The cold tube drawing process has high productivity and low cost, so it is regarded as an effective technology. It has been used instead of the swaging process to form monobloc tube shafts (MTS) with constant outer diameter or hollow shaft without surface defects. The objective of this study is to design an appropriate die shape that can prevent material fracture considering critical damage value (CDV) in the tube drawing process for the steering input shaft (SIS). In this study, the CDV was evaluated by the simple compression test. Based on the CDV, FE-analysis was used to design an appropriate die shape. Finally, the tube drawing experiment was performed to verify the effectiveness of the appropriate die.

Design of mandrel in tube drawing process for automotive steering input shaft

Monobloc technology provides a homogeneous material along the complete tubular shaft without any discontinuity between the interconnecting tube and the stems as is found when the tubes and stems have been joined by welding. Cold tube drawing is a technique that can be applied for manufacturing of monobloc tubular shafts with several advantages such as high productivity and cost reduction. In drawing processes, the profile design of die and mandrel is the most important factor related to forming energy and deformation behavior of tubular material. The present study is concerned with the investigation about the process parameters related with tool configuration. In order to obtain successfully formed shaft without any defects, conventional straight type and terraced type of mandrels have been proposed. For both types of mandrel, FE analyses of drawing processes were carried out and a ductile fracture criterion was utilized to predict forming failure. As the results, the advanced mandrel shape, which effectively can transmit drawing force to deforming tube, was designed.

Numerical and experimental analysis of tube drawing with fixed plug

Numerical simulation of manufacturing processes has become in the last years an important tool to improve these processes reducing lead times and try out, and providing products free of defects and with controlled mechanical properties. Finite Element Method (FEM) is one of the most important methods to simulate metal forming. In tube drawing with fixed plug both the outer diameter and the inner diameter of the tube are properly defined if correct process conditions are chosen for the die angle, drawing speed, lubrication and area reduction per pass. These conditions have great influence on drawing loads and residual stresses present in the product. In this work, the cold drawing of tubes with fixed plug was simulated by FEM with the commercial software MSC.Superform to find the best geometry of die and plug to reduce the drawing force. The numerical analysis supplied results for the reactions of the die and plug and the stresses in the tube, the drawing force and the final dimensions of the product. Those results are compared with results obtained from analytic models, and used tooling design. Experimental tests with a laboratory drawing bench were carried out with three different lubricants and two different lubrication conditions. Keywords: Cold tube drawing, finite element analysis, die design, upper bound solution

Study of cold tube drawing by finite-element modelling

Abstract The potential for optimising commercial cold drawing of steel tubes by reducing the number of drawing passes whilst minimising the induced tensile residual stresses has been investigated. Modelling techniques have been used based on a commercial implicit finite-element (FE) code. The FE model takes into account the elastic–plastic response of the tube, the elastic response of the tools and the adiabatic and frictional heating effects during drawing. The model has been validated against the measured surface temperature, drawing load and mandrel reaction force. Key model outputs such as residual stresses, drawing force and temperature distribution have been predicted. In addition, an optimisation procedure has been developed based on the Cockcroft–Latham workability failure criterion to determine whether it is possible to reduce the number of drawing passes for a given size reduction. The optimisation procedure can be used to design optimum dies and mandrels for tube drawing and minimise the time and cost associated with lengthy works trials in bulk metal-forming processes.

Geometry factors and inhomogeneity of flow in rotary piercing and cold drawing of seamless tubing

An assessment of the levels of inhomogeneous or redundant flow, as reflected by the redundancy factors, in the basic rotary-piercing and cold tube drawing processes, is made by means of derived geometry factors. The validity of the approach is tested against the experimental data. A generally satisfactory measure of agreement which exists between the proposed factors and the experimentally established inhomogeneity of the deformation, particularly in drawing, indicates the possibility of utilising this simple method in the computation of stress and strain levels in the tube making processes.