Stress of drawing solid rectangular profiles

The process of drawing rectangular sections is conveniently designed with the use of analytical expressions that make it possible to operatively evaluate different manufacturing factors. The application of a drawing tool with optimum angles makes it possible to cut down power inputs and reduce the failure and unsoundness of a blank. A design procedure for the drawing stress of the rectangular section is advanced. Formulas for calculating the drawing stress and determining the optimum angles of a channel of the drawing tool are derived. It is shown that the optimum angles depend on the friction coefficient and the reduction ratio.     

Optimal geometry of the channel of the drawing tool when deforming bimetallic composites

Analytical expressions for the calculation of drawing stress and the optimal channel angle of the drawing tool, making it possible to operatively evaluate the influence of various manufacturing factors on the energy-power parameters of the process and on the longitudinal stresses in the layers of bimetallic composite, are derived for designing the drawing process of bimetallic wares. Disadvantages of the proposed formulas are noted.     

Power parameters of the drawing process in a roller die

With the use of the inversion method when analyzing the kinematics of the deformation center, a method for evaluating the power parameters of the drawing process in roller dies (RDs) is developed. Design formulas are obtained to determine the contact stresses and drawing stress as a function of the technological characteristics of the process and the construction of. This method can be used both to select a rational design of the roller die by the specified technological parameters of the drawing process and to find optimum paths of drawing with the application of a specific design of RDs.     

Effect of Pore Space Structure on Deformation Energy Absorption during Compression of Highly Porous Composites. Part II. Intense Hardening Stage

A method is suggested for analytical determination of the optimum structure for highly porous material according to the criterion of minimum deformation stress. It is shown that calculation by the minimum stress criterion makes it possible to obtain in the optimum structural state a lower damping stress with greater work for deformation. Calculations are in good agreement with experimental results.     

Effect of cementite morphology on pearlitic wire drawing deformation

A comparative study was conducted on the effects of lamellar cementites and globular cementites on the cold drawing process and the mechanical properties of pearlitic wire steel, with the help of metallographic microscope, scanning electron microscope, transmission electron microscope, tensile tester and hardness tester. The lamellar cementites showed the deformation capacity to some extent during the cold drawing process. As the drawing strain increased, the pearlitic wire with globular cementites evolved into the fibrous form gradually and no obvious defects were found in the microstructure. The globular cementites turned to the drawing direction without any deformation of itself during the deformation process. And micro- cracks occurred in the cementite/ferrite interface due to stress concentration caused by pinning dislocations in spherical cementites. The strength and hardness of both pearlitic wires gradually increased as the drawing strain rose. And the pearlitic wire with lamellar cementites had a higher drawing hardening rate. The ferrite <110> texture formed in both pearlitic wires during the cold drawing process. Compared with the globular pearlite, the pearlitic wire with lamellar cementites had higher ferrite <110> texture intensity. And the difference of their ferrite <110> texture intensity became bigger and bigger as the drawing strain increased.     

Modelling and experimental study of multi‐pass wire drawing of hypo‐eutectoid steels

The paper presents the results of extensive experimental research focused on the analysis of deformation conditions in multi‐pass drawing process. The wire rod of medium and high‐carbon steel manufactured with application of controlled cooling rate after hot rolling was chosen as the material to be drawn. Suitability of the wire rod for the multi‐pass drawing process was assessed by means of detailed analysis of mechanical properties of a material before drawing, after each pass as well as of the final product. The drawing process was realised without intermediate heat treatment, assuming maximum possible reduction to be attained. The effect of history of deformation (distribution and number of unit reductions, die geometry) on the mechanical properties of drawn wires was analysed. The force parameters of the drawing process were also evaluated in detail, which allowed for an attempt to determine the optimum drawing conditions. The separate part of work was the upper‐bound process modelling which included calculations of the components of power of deformation as well as the analysis of state of strain by means of strain redundancy factor evaluation. Finally, conclusions were formulated concerning suitability of the investigated wire rod for deep cold working as well as the influence of history of deformation on the product quality.     

A calculation method for determining the limit of flange wrinkling in the deep-drawing of cylindrical steel shells without blankholding

Flange wrinkling in deep drawing of cylindrical cups without a blankholder restricts the depth of the cup. In addition to the blank and tool geometries, the material properties determine the maximum reduction attained. Geckeler, Senior and Kawai have developed theories for calculating the critical hoop stress in the flange and the number of waves formed. In the present work a calculation method for predicting the limiting drawing ratio in drawing without blankholding on the basis of the theories mentioned above and the material properties is developed. By comparing the experimental and calculated values, it is shown that the limiting drawing ratio can be determined theoretically.     

Structure and Properties of Carbon Steel Wire in Drawing

A method of continuous deformational nanostructuring of wire is described. In the method, a continuously moving wire is subjected simultaneously to tensile deformation in drawing, flexural deformation on passing through a roller system, and torsional deformation. This combination permits wide variation in its mechanical properties, ensuring both high strength and plasticity. The benefits of such deformation are the use of a tool already employed in the production of metal components; compatibility with the speeds of coarse and moderate wire drawing; and simplicity of the equipment. Laboratory apparatus for this method is described. Carbon steel 50 wire is selected for investigation, since it in great demand. The chemical composition and mechanical properties of the wire in the initial state are described. Experiments are conducted to investigate the effectiveness of the proposed differential nanostructuring in producing ultrafine-grain structure in the wire. The deformation conditions of the wire are described, as well as the drawing process. The transverse and longitudinal microstructure of the carbon steel 50 wire at the surface and in the center after different types of deformational treatment is investigated. In the experiments, the influence of the type of deformational treatment on the microstructure of the steel and its anisotropy over the wire cross section is established. The compliance of the wire’s mechanical properties with current standards is verified. After all types of treatment, its mechanical properties are consistent with State Standard GOST 17305–91. Metallographic data and mechanical test results after combined deformational treatment indicate that such combinations of deformation provide a promising approach to creating ultrafine-grain structure in carbon wire.     

82B高速线材拉拔过程中显微组织的演变分析

借助扫描电子显微镜(SEM)观察分析研究了82B线材在拉拔过程中显微组织和芯部马氏体的演变规律。分析认为:由于索氏体属于细片状珠光体,拉拔变形时,承受滑移的铁素体相不易引起应力集中;渗碳体相为细薄片层形态,也能够发生塑性变形,经过多道次的拉拔,索氏体基体变形量较大,没有出现任何裂纹。而芯部由偏析形成的马氏体,其塑性变形能力明显低于索氏体,基本无变形,在基本拉应力和附加拉应力的共同作用下,在早期拉拔时就在芯部出现裂纹,在后期拉拔过程中,裂纹沿着拉拔方向不断扩展。为减少断丝,可采用加大吹风量、扩大连铸坯、控制钢水过热度、增加电磁搅拌等工艺,来提高索氏体含量和细化渗碳体片层及预防马氏体的形成,以提高拉拔性能。     

An error analysis for visioplasticity data processing

The conducted investigations are concerned with the effect of data errors on the calculations of stress and strain components according to the visioplasticity method. The error analysis was based on an evaluating process suitable both experimentally and theoretically for exact calculations. Longitudinal sectional areas of rod drawing stock were marked photochemically with measuring grids with a line spacing of 0.1–1 mm. Specimens thus prepared were partially drawn and the deformation patterns were registered by means of a measuring microscope. The measured data were evaluated with the aid of a smoothing and calculating procedure based on cubic spline approximations. This procedure was checked with a flow model and proved to be suitable for exact visioplasticity calculations. Error investigations were carried out in order to examine the influence of a measured data scatter on the visioplasticity calculation results and an error size was defined and used to establish an error curve according to three different methods. By means of this function it is possible to quantify – as has been indicated by means of an example – the calculation error for a given quantity of data or, depending on the accuracy and aim of the calculations, the demands on the measuring grid and the data quality can be derived. By the example of the calculation of frictional stresses it has been demonstrated that the spacing of the measuring grid lines must be adjusted to suit the inhomogeneity of the plastic flow. If need be, a special more sophisticated method of evaluation is necessary – as described in ⁵) – to determine accurately such inhomogenous strain patterns.     

铝合金热塑性变形流动应力及其数学模型

采用恒应变速率凸轮式压缩试验机,测定了4种铝合金材料在热状态下的流动应力,分析了应变率、应变速率及变形温度对流动应力的影响规律,通过对多种结构型式流动应力数学模型的回归分析比较,确定了计算精度较高、结构型式较简单、适合于现场计算机在线控制和工程计算的数学模型。     

Simulation and optimization of extrusion of cylindrical billets of plasticized powder and composite charges on screw extruders

A mathematical model for computing the extrusion of long billets of plasticized powder and composite charges on screw extruders through facilities with a local sectional area reduction of the forming channel is represented. The stress field calculation in the various material deformation centers along the overall length of the channel is carried out with the use of the discrete material plasticity theory. It is shown how to select their combination optimal for extrusion process by varying the form of the channel surface, the material extrusion rate in the zone of local channel section reduction, and the billet-section area.     

金属压力加工问题的流函数速度模式上限解

采用流函数法构造了塑性变形金属流动的完备速度模式,对Mises材料平面变形和轴对称变形问题,提出并推证了运动可能速度场应满足的力学边界条件一\     

Energy-power conditions for drawing bimetal blanks

A procedure for determining the optimal geometry of a drawing tool for drawing a bimetal blank is proposed. The optimum cone angles of the drawing tool, which offers the minimum drawing stress and minimum energy consumption during the manufacture of bimetal articles, were found from the condition of minimum of the drawing stress.     

连铸板坯在结晶器内凝固行为的研究

在考虑结晶器铜板水槽结构尺寸和分布的基础上，建立了连铸板坯在结晶器内温度场和应力场之间耦合过程的有限元分析模型。通过耦合计算，发现板坯在连铸结晶器中宽窄面方向上的坯壳表面温度、坯壳生长及其受力变形等行为沿拉坯方向上的变化规律，为分析和解决铸坯在结晶器中产生的质量问题、设计或优化有关结晶器工艺和结构参数提供了理论依据。     

选矿厂计算机辅助设计(CAD)与虚拟现实技术应用现状及展望

选矿厂设计过程涉及大量数据计算、图形绘制以及设计规范和设计经验的应用,计算机辅助设计的应用无疑能显著提高设计效率和质量。通过对选矿厂计算机辅助设计研究现状进行总结和分析,指出存在的问题和不足,即设计过程模块化、设计规范和经验处理不成熟、设备配置自主化和可视化程度低以及沉浸感缺乏等。计算机虚拟现实技术（VR）的出现,为解决这些问题和不足提供了新的技术途径,将VR技术应用于选矿厂设计中,可有效提升设计过程的自主化、可视化、沉浸感以及人机交互性与设计员的想象创造力,是未来选矿厂计算机辅助设计的重要发展方向。     

Cold deformation behavior of graphitized carbon steel

The cold compression test of a strain rate 1s-1 for graphitized carbon steel containing C of 0. 43 mass% with ferrite and graphite was carried out using Gleeble- 3500 thermal simulation machine, the characteristics of the stress- strain relationship was analyzed, and metallographic analysis in the large deformation zone of the compressed samples with different reduction was investigated by optical microscope, field emission scanning electron microscopy and micro hardness tester. The results show that there exists peak stress on the stress- strain curve, namely, 645MPa, the corresponding peak strain is 0. 43; in process of the compressive deformation, morphologies of ferrite and graphite in the large deformation zone on the longitudinal section of the compressed samples gradually become fibrous with increasing the reduction; thereinto, the deformation of graphite particles is realized by means of sliding deformation between basic planes of graphite, shear deformation between substructures of graphite particles, as well as elongation of compacted section near the base of the ferrite of the deformed graphite particles; microhardness of ferrite increases with increasing the reduction, it indicate that ferrite is in a state of hardening, but, increase amplitude of microhardness in the process of compressive deformation after peak stress is decreased. Therefore, based on increase amplitude of microhardness of ferrite and microstructure of the deformed graphite particles, it can be concluded that in process of the compressive deformation after peak stress, deformation of graphite particles in the large deformation zone plays a major role, a deformation of ferrite plays a secondary role (it is mainly to coordinate the deformation of graphite particles), this is one of the main reason that stress decreases in the compressive deformation after peak stress.     

Computer analysis of the deformation mode of the drawing tool for platinum alloys

A computer analysis of the deformation mode of a billet and tool in the axially symmetric statement at the stage of established drawing of the PtNi alloy of the equiatomic composition is performed by the finite-element method in the DEFORM-2D program medium. The geometry of the diamond tool providing a decrease in rigidity and weight without varying the basic parameters of the production process is proposed.     

An analysis of continuous resin contacting

The main purpose of this paper is to stress that in a first-order system, a disperse phase, e.g., resin, behaves on average as though it were well mixed, despite the fact that it is not possible that adsorbed ions re-distribute between resin particles. Average concentrations are justified for the calculation of stage efficiencies. A model involving a distribution of first-order rate constants includes (as special cases) the Vermeulen model for diffusion-rate control within resin particles, the exact form it approximates, and (with restrictions) liquid-film control.The effect of feedback of aqueous solution and resin as a result of entrainment is analysed by a general-purpose simulation programme, which was used to explain the poor performance of a resin-in-pulp process. The theory developed in the first part of the paper justified the use of average concentrations in the simulation.