Draw Bench Research Articles

Change in Surface Roughness on the Inner and Outer Surfaces of the Microtube during Hollow Sinking.

Hollow sinking experiments and tensile tests were conducted to clarify the evolution of surface roughness during hollow sinking. Stainless steel tubes (outer diameter: 1.5 mm; wall thickness: 0.045 mm) featuring a single grain spanning the wall thickness achieved via annealing as the starting material. The tube was drawn without an internal tool using a draw bench by controlling the tube drawing speed ratio of the die entrance and exit sides. The surface roughnesses of the inner and outer surfaces at the die entrance and exit sides of the drawn tube were compared with the surface roughnesses of the inner and outer surfaces under the uniaxial tensile deformation of the starting material. As a result, two major findings were revealed; the surface roughness formation behavior during the hollow sinking; the uniaxial tensile deformation exhibits a tube on both sides of the entrance and the exit of a die. Former uniaxial tensile deformation forms surface roughness of the tube at the die-entrance-side. However, hollow sinking reduces the roughness. The tube keeps its small roughness even though it is applied the later uniaxial tensile deformation behind the die exit. Furthermore, the conventional formula to predict the surface roughness of a metal sheet caused by the uniaxial tensile deformation can predict the surface roughness of a tube in the hollow sinking. At both die entrance and exit sides, the roughness of the inner surface was larger than that of the outer surface at the die entrance and exit side. The outer surface of the tube contacts the inside of a die when the tube passes through the die. The height of the convex parts decreased at that moment. Hollow sinking suppressed the increase in surface roughness of the inner surface as the outer surface was smoothed in the die. However, due to the formation of surface roughness after leaving the die, there is an overall increasing trend in inner surface roughness.

UNCONVENTIONAL METHODS OF MANUFACTURING THIN WIRES FOR APPLICATION AS INPUT MATERIAL IN ADDITIVE MANUFACTURING. PART 2: DRAWING OF Fe-BASED ALLOY WIRES

The article presents the technology of drawing thin wires made from selected iron-based alloys for use in additive manufacturing using WAAM method. The final technology of wire production was developed with the use of a drawing bench, depending on the deformed material. Steel wires with a diameter of 1 mm and mechanical properties adapted to the 3D printer were produced.

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.

Process Condition Diagram Predicting Onset of Microdefects and Fracture in Cold Bar Drawing

This paper presents a process condition diagram (PCD) that not only identifies conditions under which materials fracture during bar drawing, but also infers the presence or absence of microdefects such as microvoids and microcracks in the drawn material as accumulative damage changes owing to the die semi-angle and reduction ratio. The accumulative damage values were calculated by finite element (FE) analysis. The critical damage values were determined by performing a tensile test using a smooth round bar tensile specimen and performing FE analysis simulating the tensile test. High alloy steel with a 13 mm diameter was used for the draw bench testing in a wide range of drawing conditions. Scanning electron microscopy (SEM) analysis was performed to verify the usefulness of the PCD. SEM images showed that the accumulative damage roughly matched the size of microvoids around the non-metallic inclusions and the creation of microcracks, which eventually led to fractures of material being drawn. Hence, utilizing the proposed PCD, a process designer can design drawing conditions that minimize the occurrence of microdefects in the material being drawn while maximizing the reduction ratio.

Simulation of two hollow sinking passes in one tool

The paper deals with optimization of hollow sinking process of seamless steel tube E235. Specifically, the last two sequences are merged into one drawing pass by one tool. Saving one hollow sinking operation will save rebuilding on the drawing bench, tube handling and increase drawing capacity in short time. The input feedstock with outer diameter Ø18 mm and wall thickness 0.9 and 1.0 mm was drawn into tube with final dimension Ø10 × 1.0 mm by single-die and double-die. The aim of the numerical simulations was to compare the flow of material by means of monitored values (stress, deformation) in different technologies. The final drawn tubes differed in wall thickness. This is due to the stress-strain state in the deformation zone. Both simulation and experiment of cold drawing of Ø18 × 0.9 (1.0) mm hollow into Ø10 × 1.0 mm tube confirmed that the double-die configuration is inferior to the single-die one when it comes to the optimum material flow.

Исследование пускового момента и механической характеристики асинхронного двигателя для электропривода безредукторного волочильного стана

This paper analyzes an asynchronous motor for electric drives used in geared n-block draw benches for making steel wires from hot-rolled billets (8 to 12 mm in diameter). Modern draw benches are shown to feature adjustable automated electric drives based on conventional asynchronous motors, frequency converters or soft starters. The paper describes the primary features of the drawing process and the most important requirements to the draw-bench electric drives; one such requirement is a specific starting torque. It is noted that the shaft of the asynchronous motor, the starting torque of which is 1.6 to 2.2 times as large as the nominal torque, transmits its torque to the shaft of the intermediate block via a reduction gear that reduces the speed but multiplies the torque by 3.5 to 16.5 times. Using such reduction gear lowers the electric drive efficiency by at least 13 to 20 %, making the drawing process less energy-efficient and the final product less competitive. The objective here is to study the asynchronous motor torque to design a gearless draw bench and elective drive based on an object-oriented asynchronous motor with a greater starting-torque multiplicity. The proposed solution to the problem takes into account the saturation of the motor magnetic system and the current displacement in the rotor winding. The problem is solved by calculus and modeling the mechanical characteristics of the motor in a specialized computer program. It is proven possible to design an asynchronous motor with a starting torque sufficient for gearless drawing. Using a gearless intermediate block will simplify the design and improve reliability while also reducing the operating costs and the power consumption of drawing by 17 to 20 %. The results of the study will be of interest to specialists in electric machines, engineers of electromachine-building enterprises, technologists and designers of mechanical machinery for metalworks.

Nature of substrate modification effect on thermal performance of simulated solar cells over phase-change immersion cooling under high concentration ratios

A new point from modifying substrate structure of solar cells is proposed based on direct-contact phase-change immersion cooling to solve the heat dissipation problem of solar cells worked under high concentration ratios. An electric heating plate (EHP) is carefully designed to simulate the heat flux of solar cells under high concentration ratios (184.2 X). Easy and lower cost ways of electrochemical etching and mechanical drawing bench are adopted to modify substrate surface of simulated solar cells. The result of thermal measurement shows substrate, undergoing electrochemical etching for 2 h (CE-2) or mechanical drawing bench using 800 mesh (MDB-800), owns the lower wall average temperature (85.36 and 85.7 °C) and higher surface heat transfer coefficient (3008 and 2970 W/(m2 K)). SEM results reveal that CE-2 or MDB-800 has uniform-distributed porous or dense-grooved structure. These special structures show better surface wettability and provide more active nucleus sites for small bubbles generation as well as higher bubbles update frequency according to our modified surface wettability and quantitative analysis results. Our study reveals that the advanced heat transfer performance is attributed to substrate structure with uniform-distributed porous or dense-grooved of CE-2 or MDB-800. This work gives a theoretical guidance for heat transfer advancement investigation involved in surface characteristic.

Development Structural of A Wire Drawing and Extrusion Bench

Development Structural of A Wire Drawing and Extrusion Bench

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.

Physical and Numerical Modelling of Wire Drawing Process of Mg Alloys in Heated Dies Accounting for Recrystallization

Magnesium-calcium alloys with increased bio-compatibility are applied in medicine for sake of high compatibility and solubility in human body. Production of surgical threads to integration of tissue may be one of the applications of those types of alloys. A new manufacturing process of thin wires made of biocompatible Mg alloys, including drawing in heated dies, was developed in Authors previous works. Conducting drawing process in conditions, in which recrystallization occurs, is the basis of the process. This allows for multi-pass drawing without intermediate annealing. Control of recrystallization after every pass using experimental method is complex so numerical simulation seems to be a rational method to design the process parameters. The purpose of the paper is developing a mathematical model of recrystallization for MgCa08 alloy, its implementation into the finite element (FE) code that simulates wire drawing and experimental verification of the numerical calculations. The first part of work was focused on the development of mathematical model of wire drawing process of Mg alloys in heated die. Proposed model takes into account thermal phenomena in the wire and in the die, plastic flow of the material, stress-strain state and recrystallization. The fracture criterion was implemented into FE code to eliminate the possibility of damage. The second part of the work was focused on experiments including upsetting and tensile tests for calibration of recrystallization and fracture models. Recrystallization model was calibrated on the basis of flow curves only what is a limitation. Therefore, experimental wire drawing on drawing bench developed by the Authors was the final stage of the work performed to validate the model. Recrystallization during wire drawing was studied. The developed computer program enables prediction of the recrystallization kinetics during wire drawing in heated die for MgCa08 alloy. The model of static and dynamic recrystallization of this alloy and complex model of the drawing process were proposed in this work, as well.

Analysis of the failure mechanism of a gripping tool steel component operated in an industrial tube draw bench

Gripping assemblies are sophisticated machine elements, served as clamping mechanisms in draw benches, pulling the metallic rod or tube through a die. They manufactured from special alloy tool steel and subjected to high axial and repeated stresses due to successive loading and un-loading conditions. In-service failures of gripping tools, occurred in an industrial tube draw bench, led to increased maintenance costs and machine downtime, resulting in low productivity. Samples from fractured components and their connections, namely the arm, the expansion guide and the threaded rod, were brought from a metal working industry for a failure analysis investigation. Failure analysis findings suggest strongly that the failure occurred due to fatigue under high stress amplitude, initiated at the sharp corner of the arm jaw and followed by brittle quasi-cleavage overload fracture. Review of the service history (operating loads, lubrication, etc.), in combination to the examination of a potential improvement of the steel cleanliness and surface condition are mostly recommended as further fatigue failure preventive actions.

Research of selected properties of two types of high manganese steel wires

The article presents results of tests that aimed at establishing the impact of deformation on properties of wires made of two types of high manganese steels. The deformation process was carried out with the use of a draw bench machine at a speed of 0.5 m min−1. Mechanical properties and structure of strengthened and annealed wires for both steels at different levels of relative reduction in cross-section were determined. Strength of the tested materials was determined in the tensile test, while its hardness was measured with the Vickers hardness test method. Fractographic tests were performed using a scanning electron microscope. It was shown that at the beginning of tensile test, the investigated high manganese steels were characterized by very high plasticity and become stronger as the degree of deformation grows. Surfaces of fractures that were created in the areas where the sample was torn were analyzed. These fractures indicate the presence of transcrystalline ductile fractures.

Electric drives based on induction motors with individual compensations for reactive power intended for draw benches

Power-saving electric drives created by modernizing traditional three-phase induction motors for draw benches are presented. Power-saving induction motors have cos φ = 1.0 and power efficiency ηp = 80–90%. Each kilowatt of rated power of an energy-saving induction motor makes it possible to save approximately 300–750 kW h of electric power per year.

Fatigue failure of steel links operating as chain components in a heavy duty draw bench

Steel links used as chain elements in draw benches are subjected to repetitive tensile stressing due to successive loading and un-loading conditions. In addition, friction caused by poor or improper lubrication can be very harmful, due to associated surface degradation and wear/corrosion related processes which play an important role to the integrity and performance of the machine components. Frequent in-service failures of chain links occurred in a copper tube draw bench have led to increased maintenance costs and machine downtime resulting in poor productivity indicators. Samples from fractured components, made of induction hardened structural steel, were brought for a failure analysis investigation. Failure analysis findings suggest strongly that the failure was accomplished by the operation of fatigue mechanism initiated at the inner-eye area of the link and followed by brittle overload fracture. Review of the service history (operating conditions, applied loads), in combination to the examination of a potential substitution of the material to a more fatigue resistant one are recommended as further fatigue damage preventive actions.

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

Steelmaking and Rolling at the West Siberian Metallurgical Combine

Removing scale from the surface of wire rod before it is drawn is an important operation that affects the structure, mechanical characteristics, and commercial properties of the rod. The West Siberian Metallurgical Combine has worked with the Russian-Bulgarian consortium Ekomet to develop and introduce integrated lines WCM-05 and SCM-07 (for coiled rod) and SCM-02 (for uncoiled rod) to mechanically remove scale. The lines have several advantages over similar existing equipment: they can be installed directly in line with the draw bench; the scale can be removed by a combination of several methods; the installation costs are lower than for comparable facilities.

Use of an Emulsion Based on the Lubricant Sinapol in Draw Benches to Make Galvanized Wire

Use of an Emulsion Based on the Lubricant Sinapol in Draw Benches to Make Galvanized Wire

Investigation of Ecology Friendly Lubrication in High Speed Drawing Of SSID Tubes

Tubes used in the chemical and fluid power industry have special inner surface roughness requirements. To meet these requirements, it was decided to explore the mandrel drawing of carbon steel tubes to submicron surface finish and thereby reduce the need for machining and honing the inner diameter of the tube. An additional goal was to investigate the use of ecology friendly solid lubricant in the mandrel drawing process. First, a roughness model was developed which relates the interface parameters such as effective stress to roughness changes and lubrication parameters. This model was calibrated using industrial experiments on a draw bench. Then a design of experiment was carried out to relate the tube drawing phenomenological parameters such as die angles, reduction and drawing speed to the interface parameters. These two models were then integrated to predict the surface roughness changes at the inner surface of the tube during mandrel drawing. It was found that the new lubricant is able to provide good surface finish for typical tube drawing reductions with and without the conversion coating. However, for reductions larger than 40% it cannot prevent die pick up. At drawing speeds greater than 0.5 m/s it is effective in preventing die pick up but cannot deliver SSID surface finish in drawn tubes.

Design of µ - Optimal Robust Controller for a Thermoplastic Process

Problems of the design of robust controllers are very important especially in the domain of continuous processes’ control improvement. Thermoplastic process in the form of a glass tube drawing bench represents a multidimensional system. This system can be characterized as a system with very limited measurement and modeling possibilities and with increased sensitivity to input and model parameters changes as well.The main scope of the paper is focused on problems of µ-optimal robust controller for glass tubes forming process control design. The approach presented makes possible the improvement of the accuracy of geometrical parameters of glass tubes produced, this influencing directly the economical effectiveness of the production. Different alternatives of solutions taking in account limitations of robust controllers’ synthesis, realization possibilities and applied software package MATLAB/SIMULINK.

Polymer coating of superfine wire: a new technique to ensure quality

This project outlines the design and development of a multi-purpose drawing bench along with a pressure die chamber to coat ultra fine wire. The pressure chamber was designed along similar lines to the pressure chambers used by previous researchers for plasto-hydrodynamic die-less drawing processes. The commissioning of the drawing bench along with the coating system and possible future modifications to the design for achieving the objectives have been described. Results of the initial tests to determine if it is plausible to use the plasto-hydrodynamic pressure technique to coat ultra fine wire with a very thin polymer coat are presented and discussed.