Multi-stage Drawing Process Research Articles

Phase transformation, texture evolution, and mechanical properties of Mg-9.5Gd-4Y-2Zn-0.3Zr alloy wires fabricated using hot drawing

Mg-9.5Gd-4Y-2Zn-0.3Zr alloy wires with a diameter of 1.2 mm were fabricated by a multistage drawing process with a cumulative area reduction (CAR) of 96% at 500 °C using as-extruded rods with a diameter of 6 mm as the raw material. Investigated the impact of microstructural transformations on the mechanical performance of these wires, with a focus on phase evolution, texture changes, and grain refinement. In the alloy, second-phase 18R-LPSO, rare-earth-rich (RE-rich) phase, and Zn2Zr3 distributed at the grain boundaries along the extrusion direction (ED) or the drawing direction (DD), which were different from the intragranular 14H-LPSO phase, were observed. Significantly, we observed the transformation of blocky 18R-LPSO phases into sub-2μm W-Mg3Zn3RE2 particles during hot drawing. All the as-extruded and as-drawn wires exhibited equiaxed grains with average sizes between 4 μm and 7 μm. The as-extruded wires exhibited a texture with {0001} perpendicular to ED. As the CAR increased, the texture of the wires transformed into a basal texture with {0001} parallel to DD. The ultimate tensile strength (UTS) and tensile yield strength (TYS), respectively, increased from 369 MPa to 283 MPa for the as-extruded wire to 466 MPa and 436 MPa for the as-drawn wire with CAR increasing to 55%, and then decreased to 328 MPa and 318 MPa for the wire with CAR increasing to 96%. The elongation (EL) reduced from 8.01% to 1.37% with CAR increasing to 96%. As CAR exceeded 55%, the increased volume fraction of the W-Mg3Zn3RE2 phase resulted in a significant decrease in both the strength and the plasticity of the wires. The evolution of microstructure and mechanical properties provides possibility for regulating both the strength and elongation of the Mg-Gd-Y-Zn-Zr alloy wires by optimizing the drawing process.

Analytical and Numerical Models for the Analysis of the Multi-Stage Drawing Process of Zn Wires

Today environmental aspects are of great importance in the sustainability of the planet, in this aspect anti-corrosive treatments facilitate the durability of metal structures. Among the most widely used anticorrosive metals is Zinc and its alloys. In the deep galvanizing process of large steel structures, tanks containing Zinc in a molten state at a temperature of 460 °C are necessary. Then, to protect elements that are too large or that need to be treated "in situ", metallization is used, which consists of projecting molten zinc wire on the metal surface that has previously been subjected to a process sandblasting (mechanical abrasion). The two main methods of metalizing are electric arc and flame. In the present work an industrial wiredrawing draft has been studied, determining the drawing force and the power required in each stage. For this purpose, linear strain hardening model vs non-linear strain hardening model that takes strain rate hardening into account has been proposed for its implementation in the analytical model of the process and finite element model (FEM) has been developed too. The use of Hall Petch equation has been allowed to get a prediction of the evolution of the grain size during the wiredrawing sequence.

An Effective Formability Model of Pearlitic Steel Wires in Multi-stage Drawing Process Based on the Stress-Based Forming Limit Criterion

An Effective Formability Model of Pearlitic Steel Wires in Multi-stage Drawing Process Based on the Stress-Based Forming Limit Criterion

High speed multi-stage drawing process of hot-dip galvanised steel wires

In this paper, unique tests into the production of galvanised steel wires in industrial conditions were presented. It was demonstrated that three phenomena occur during the wire-drawing process at high speeds: namely, zinc sticking to the surface of drawing drums, zinc coating grinding caused by a larger friction surface area between the tool and the material, combined with the detachment of the zinc coating in the calibrating part of the die until the wire breaks and the drawing process is interrupted. After drawing at high speeds (over 15 m/s), the wires were characterised by a thin coat. The research carried out in the study showed a significant influence of the speed and the drawing angle on the mechanical and technological properties as well as the residual stresses in hot-dip galvanised steel wires. Depending on the speed of drawing, wires drawn in dies with an angle α = 7°, in relation to wires drawn in dies with an angle α = 3°, were characterised by 7.8–12% higher yield strength, and 3.7–7.1% higher tensile strength, 16.7% and 21.5% lower elongation, 24.3% lower reduction in area, 33% lower number of twist and bends, and 145.9% higher residual stresses.

The Multi-Stage Drawing Process of Zinc-Coated Medium-Carbon Steel Wires in Conventional and Hydrodynamic Dies.

This paper discusses experimental studies aiming to determine the effect of the drawing method on the lubrication conditions, zinc coating mass and mechanical properties of medium-carbon steel wires. The test material was 5.5 mm-diameter galvanized wire rod which was drawn into 2.2 mm-diameter wire in seven draws at a drawing speed of 5, 10, 15, 20 and 20 m/s, respectively. Conventional and hydrodynamic dies with a working portion angle of α = 5° were used for the drawing process. It has been shown that using hydrodynamic dies in the process of multi-stage drawing of zinc-coated wire improves the lubrication conditions, which leads to a reduction in friction at the wire/die interface. As a consequence, wires drawn hydrodynamically, as compared to wires drawn conventionally, are distinguished by a thicker zinc coating and better mechanical and technological properties.

Micro-Drawing of Circular Cups with Thin Stainless Steel Sheets

With the ongoing development of product process, there is a growing demand on micro products. Though the macro-drawing process has been well-developed, the design concepts may not be directly applicable to the micro-drawing due to the size effect occurred in the micro-forming processes. In the present study, experiments were conducted first to establish the stress-strain curves, r-values and work hardening exponents of 304 stainless steel sheets with different grain sizes. The experiment results reveal that the stress-strain and r-value become smaller and the work hardening exponent increases for larger grain sizes. The difference between stress-strain curves in various directions of 0°, 45° and 90°, respectively, is significant when the grain size increases. The stamping of a vibration motor shell of cell phone, which bears a circular cylindrical shape, was also examined in the present study. The finite element simulations were performed to evaluate the formability of the multi-stage drawing process with initial die design. The forming characteristics were identified and an optimum die design was then developed with the use of the finite element analysis. The stamping process with multi-stage tooling design based on the finite element analysis was implemented and the actual stamping experiments were conducted to verify finite element analysis. The experimental results confirm the validity of the modified tooling design and the efficiency of the finite element analysis.

Multistage Cup Drawing of Thicker Blanks of Al-Killed AISI 1010 Steel: A Modified Approach

In this paper a new modified processing route for deep drawing has been proposed for producing long cylindrical cups from 12 mm thick circular blanks of Aluminium (Al)-killed AISI 1010 steel, without blank-holder. In this modified route, flat blanks were fabricated to a preformed shape by stamping operation and then followed by multistage drawing processes to increase depth of the cups. Wall ironing was also purposefully included in each draw step with deep drawing processes to reduce wall thickness and earing tendency on cup edges. Thus, evolution of wall thickness distribution, drawability and ironability parameters, punch force history, microstructures and strain distribution profiles on outer cup surfaces were obtained as effects of interaction between processes, tools and material in the investigation. The overall draw stages showed: LDR 2.06; overall draw reduction >50% with a drawing efficiency ~72%; LIR 3.55; overall ironing reduction >70% with an ironing efficiency ~68%, which were achieved in the experimental works.

Analysis of the Heating of Steel Wires During High Speed Multipass Drawing Process/ Analiza Nagrzewania Się Drutów Stalowych W Procesie Ciągnienia Wielostopniowego Z Dużymi Prędkosciami

Abstract The analysis of the heating of the wire including theoretical studies showed that in the multistage drawing process a increase drawing speed causes intense heating of a thin surface layer of the wire to a temperature exceeding 1100°C, which should be explained by the accumulation of heat due to friction at the interface between wire and die. It has been shown that with increasing of drawing speed the heated surface layer thickness measured at the exit of the wire from the dies is reduced significantly and at drawing speed of 25 m/s is equal to about 68 μm. The decrease in the thickness of this layer can be explained by a shorter time of heat transfer to the wire, which causes additional heat accumulation in the surface layer. Thus fivefold increase in drawing speed caused an approximately 110% increase in the temperature in the surface layer of the wire. Experimental studies have shown that the increase of drawing speed of 5 to 25 m/s will increase the temperature of the wire after coiled on the spool more than 400%.

Selected Problems from the High-Carbon Steel Wire Drawing Theory and Technology

Abstract Use of computer programs based on finite element methods for simulations of plastic working processes allows for their wider analysis. The theoretical studies presented in the paper, carried out using Drawing 2D, a specialized software application for modelling of the multi-stage drawing process, and their experimental verification have enabled a comprehensive analysis of many problems related to high-carbon steel wire drawing to be made, such as: drawing under hydrodynamic lubrication conditions, drawing with a change in the deformation direction, drawing with small final reductions, and high-speed drawing.

Influence of cavity pressure on hydrodynamic deep drawing of aluminum alloy rectangular box with wide flange

Abstract The multi-stage deep drawing process had been traditionally adopted for the box part with super wide flange using multiple annealing procedures with problems of poor surface quality, long manufacturing cycle, high cost and low yield. The hydrodynamic deep drawing (HDD) method was suggested to solve these issues during the multi-stage drawing process, in which the loading path of cavity pressure was one of the key parameters immediately related to the product's quality. The effects of cavity pressure on forming quality and precision were explored according to theoretical analysis, numerical simulations and experiments, and the process window of cavity pressure was established through stress analysis of the corner and straight regions. Meanwhile, wall thickness distributions were investigated with different parameters, including pre-bulging pressure, piecewise stroke and maximum pressure. Furthermore, the reasonable loading path was validated by process experiments. The results indicate that the proper control of cavity pressure will be beneficial in improving the drawability of aluminum alloys effectively, and the conventional drawing process consisting of three drawing operations and two intermediate anneals can be replaced by the one-step HDD process.

Multi-Stage Deep Drawing Process of Thin Sheets for the Sleeve Housing Component of a Spindle Motor in HDD

High-precision micro-fluid dynamic bearing is the key part in a hard disk drive, as it offers low noise levels, high speeds and high rates of accuracy with low amount of vibration. To enhance the performance, a thin sheet component called sleeve housing are newly adopted in FDB. In this paper, multi-stage sheet metal forming process is utilized to fabricate the sleeve housing component. Multi-stage drawing simulations are conducted to investigate the adequate process parameters preventing wrinkling and tearing. From the simulation result, multi-stage drawing processes are conducted with progressive die sets in order to evaluate the forming accuracy. The results reveal that it is successful to fabricate the sleeve housing component with multi-stage drawing process.

Reducing Non-Value Added Process for an Automotive Component Using Finite Element Modeling

The research work focuses on sheet metal stamping process simulation of an automotive component known as bracket assembly upper spring made from low carbon steel and has axis-symmetrical cup shape that employs four multi-stage drawing processes. Non-value added drawing stages (optimization process) reduced and portrayed from the formability simulation result using finite element modeling (FEM) method. The modified design, with reduction of one draw stage, showed that the risk of the component to form cracks is lesser, the material elements are further away from the failure zone of the forming limit diagram (FLD) and it meets the requirement for minimum thickness. The FEM simulation was able to predict the formability and optimize the design of a sheet metal forming process that lowered the product cost and improve cycle time.

Development of Finite Element Model of Reorientation of Cementite Lamellae in Pearlite Colonies in Wire Drawing Process for Wires Made from High Carbon Steel

Studies of properties of pearlitic steel wires used for production of metal cord or mining hoisting ropes have revealed a relationship between the orientation of cementite lamellas in the material and the mechanical properties of the wire and its resistance to cyclic loads. Influence of technological parameters on the orientation of cementite lamellas in wire was established. Experimental determination of the range of inclination angles of cementite lamellas in a given pearlite colony, at which their advantageous orientation, parallel to the wire axis, occurs, is not feasible in practice. Therefore, the only approach for solving this problem was to develop an appropriate mathematical model. Solution of the formulated problem proceeded in two stages. At first, the DRAWING2d program [3], modified and adapted to the needs of the task, was employed. The software incorporates a model based on the theory of plastic flow of the rigid-plastic medium. The boundary problem of the theory of plasticity is solved in this model considering the flow of heat and material heating due to plastic deformation and friction. Transfer of all strain tensor components data from draw to draw enabled simulation and optimization of the multi-stage drawing processes. Based on the model, strains fields and flow velocities were determined for the whole cross-section of the material being deformed in a particular draw. At the second stage, a program was developed to model the deformation of a single pearlite colony of dimensions corresponding to those of grains occurring in the actual structure of pearlitic steel after patenting. The mechanisms of deformation of the pearlite colony, the boundary conditions related to interaction of adjacent grains, and the rheology of cementite and ferrite were also accounted for.

FEA-aided design of multi-stage drawing process and tooling for production of a miniature sheet metal component

This paper presents the design of multi-stage drawing process and tooling aided by finite element analysis (FEA) for fabrication of a miniature sheet metal component, made of a cold-reduced carbon steel material (SPCC). To design such a tooling, it is essential to figure out how many intermediate drawing steps are needed to produce the final part without deformation defect. First of all, a four-stage drawing process and a set of four-station tooling are designed. This pre-designed process is then analyzed by simulation, and the deformation behavior and formability in each stage is revealed. Based on the revealed deformation behavior and formability, the design of the process and tooling is confirmed. The reasonable drawing ratio and drawing depth in each drawing operation are determined. The size, clearance, and the corner radii of punch and die in each stage are also identified. The designed process and tooling are finally implemented. Through experiment, the “right design in the first time” is realized, and the simulation and experiment are found to have a good agreement. The research further demonstrates that the FEA simulation can be used as an effective tool to aid the design of metal-formed component, tooling, and process in upfront design process.

Numerical Analysis of Electrodeposited Nickel Coating in Multistage Drawing Processes

The elastic-plastic finite element method of a dynamic explicit algorithm was used to simulate the deep drawing processes of nickel coating electrodeposited on a steel substrate to form an advanced battery shell. The Belytschko-Wong-Chiang shell element was used to mesh the materials, the kinematical work-hardening model was adopted for the components, and the tied-with-failure contact criterion was given to the interfacial combination. The rate-type elastic-plastic constitute law was employed to handle the large deformation, and the central difference method was utilized to solve the finite element equations. The simulations of the materials in the first and final processes illustrated that the steel substrate and the nickel coating were simultaneously deformed and yielded in the die fillet profile and the flange area. The thickness variation of the nickel coating and steel substrate was dependent on the main principal stress, and their variation rule was consistent. In the entire drawing processes, the thinnest region after forming was at the lower part of the cup near the cup bottom, the extent of the coating being thinned after drawing was acceptable, and the material was capable of forming the battery shell. The simulated results were partly compared with tests and other analysis and showed good agreement.

Development of Wire Temperature Prediction Method in a Continuous Dry Wire Drawing Process Using the High Carbon Steel

Wire drawing process of the high carbon steel with a high speed is usually conducted at room temperature using a number of passes or reductions through consequently located dies. In multi-stage drawing process, temperature rise in each pass affects the mechanical properties of final product such as bend, twist and tensile strength. Also, this temperature rise during the deformation is the reason that the wire in drawing process is broken by the embrittlement due to rapid strain aging effect. This paper presents the estimation of the wire temperature for the multi-stage wire drawing process. Using the proposed calculation method of wire temperature, temperature rise at deformation zone as well as temperature drop in block considering the heat transfer between the block and wire were calculated. As these calculated wire temperatures were applied to the real industrial fields, it was known that the calculated results were in a good agreement with the measured wire temperature.