ANALYSIS ON THE SPINNING FORCESN IN FLEXIBLE SPINNING OF CONES

Flexible spinning is a new type of spinning process where spin-forming is performed without using a mandrel. Combining shearing and rolling processes, the calculation formulas of the spinning forces in flexible spinning of cones is presented. The effects of the main processing parameters, such as gripping force G applied to the blank by the inner roller, the feed rate of rollers f and theroundness radius of outer roller ro, on the spinning forces are analyzed experimentally and theorelically.     

三维非轴对称偏心类管件旋压成形时的变形力分析

采用主应力法建立了三维非轴对称偏心类薄壁管件旋压成形时的变形力的理论计算公式,并对旋轮公转角度γ、道次偏移量δ等成形工艺参数对旋压力变化的影响进行了理论分析。结果表明,在偏心类管件旋压过程中,旋压力随旋轮公转角度γ作周期性变化,其变化的幅度取决于道次偏移量δ的大小。对工件道次偏移量δ、旋轮进给比f和名义压下量Δ等主要成形工艺参数对最大旋压力的影响进行了理论分析和试验研究,理论计算结果与试验结果吻合较好。     

旋压成形有限元分析中旋轮被动转动问题的研究

旋压成形中旋轮被动转动是一个重要的边界条件，在有限元分析中需要时实确定旋轮的转速。接触区不同位置摩擦力的大小和方向不一致，旋轮和坯料接触区的摩擦力综合作用引起旋轮被动转动。利用在每个增量步内转矩平衡给出确定旋轮的转速的原则，通过反复迭代求解每个增量步内旋轮的转速，通过事例验证所提方法的可行性。     

杯形薄壁矩形内齿旋压成形数值模拟与试验

为研究主要工艺参数对齿轮成形状况的影响规律,并为参数优化和工艺设计提供依据,基于MSC.MARC有限元分析软件,对杯形薄壁矩形内齿旋压成形工艺过程和工艺特点进行分析,从而获得旋压成形时变形金属沿轴向、径向和切向的流动规律。结合工艺试验,定量地研究了主要工艺参数对齿高成形的影响规律,并对试验中出现的各种典型缺陷进行分析,提出有效的预防和改进方法。提出将包括轮齿的切向和轴向尺寸均匀程度等作为旋压成形内齿零件的主要质量评价指标。模拟和工艺试验结果表明,矩形内齿旋压成形时,压下量在一定范围内对齿高的成形影响显著,进给比对齿高成形影响不大。当工艺参数选择不当时,可能出现表面隆起或破裂、轮齿周向错移、周向高度不均和齿槽撕裂等缺陷。     

Finite element simulation and experimental investigation on the forming forces of 3D non-axisymmetrical tubes spinning

3D non-axisymmetrical tube (NAT) spinning is a kind of new spinning technology, which breaks through the restriction that only axisymmetrical hollow parts could be produced by traditional spinning technology. The research on the spinning force aims to optimize the machine design and the processing parameters selection. The neck-spinning process of the 3D NAT is simulated by 3D elastic–plastic finite element software, MARC. The characteristics of the neck-spinning force of 3D NAT are compared with that of the axisymmetrical tube (AT) spinning. The effect of the main forming parameters, such as offset amount, oblique angle, nominal reduction of blank radius, feed rate and path direction, on the spinning forces have been studied theoretically and experimentally. It shows that during 3D NAT spinning, the spinning forces varies periodically with the revolution angle of the roller around the blank; the spinning force during backward path spinning is greater than that of forward path spinning. The simulation results conform well to the experimental ones.     

旋压成形带内筋筒形件的工艺研究及数值模拟

针对旋压成形带内筋筒形件的工艺进行试验研究和数值模拟.依据实际试件的尺寸及成形情况对边界、接触、摩擦以及空间运动等条件进行确定.建立三维有限元数学模型,分析在不同壁厚减薄率和旋轮进给率等工艺参数下内筋的成形情况和应力、应变及旋压力的变化规律.对试件在成形试验时出现的表面剥离、裂纹等缺陷进行预测和初步分析,可提高工作效率并降低研发成本,为进一步深入研究带内筋筒形件旋压工艺的成形机理和变形特点打下了良好基础,为优化工艺参数提供了有效方法和可靠依据.     

滚珠丝杠副滚动体自旋运动分析

滚珠丝杠副滚动体自转运动中包含自旋和纯滚动,滚动体的自旋运动造成滚动体滑动。利用角接触轴承旋滚比的概念和目前对滚珠丝杠副自旋运动的研究情况,采用运动分析的方法分析了丝杠公称直径、接触角和螺旋升角对滚珠丝杠副自旋运动的影响情况,为设计和选用滚珠丝杠副参数提供了参考。     

A Study on the mechanics of shear spinning of cones

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the workpiece, shows a promise for increasingly broader application to the production of axially symmetric parts. In this paper, the three components of working force are calculated by the newly proposed deformation model in which the spinning process is understood as shearing deformation after uniaxial yielding by bending, and shear stress, τ _rz becomesk, yield limit in pure shear, in the deformation zone. The tangential forces are first calculated and the feed forces and the normal forces are obtained by the assumption of uniform distribution of roller pressure on the contact surface. The optimum contact area is obtained by minimizing the bending energy required to get the assumed deformation of the blank. The calculated forces are compared with experimental results. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results.     

ANALYSIS OF MECHANICS IN BALL SPINNING OF THIN-WALLED TUBE

Ball spinning is applied to manufacturing thin-walled tube with high precision and high mechanical properties. On the basis of plastic mechanics, by simplifying ball spinning of thin-walled tube as plane strain problem, slab method is used for the purpose of calculating the contact deformation pressure. The spinning force components, the torsional moment, the deformation power and the deformation work are calculated further as well. The influence of the two important process parameters such as the feed ratio and the ball diameter on the spinning force components is analyzed in order to further control the spinning force components by regulating the two process variables during the ball spinning process. The stress and strain state in deformable zone as well as mechanics boundary conditions in ball spinning are obtained. The effect of the three spinning force components on the formability of the spun part is analyzed and validated through the ball spinning experiments. The theoretical and experimental results show that the radial spinning component plays a significant role in ball spinning of thin-walled tube, and the mechanics situation in backward ball spinning contributes to enhancing the plasticity of the metal material, but that in forward ball spinning contributes to advancing the axial flow of the metal material.     

工艺参数对平板毛坯普旋成形的影响规律

基于ABAQUS/Explicit平台建立了符合实际的普旋三维仿真模型,利用此模型对平板毛坯普旋成形过程进行了模拟,研究了旋轮进给率、旋轮圆角半径、旋轮入旋角、板料厚度4个关键参数对平板毛坯普旋(第一道次)成形过程及旋压件质量的影响。结果表明:入旋角对板料的壁厚变化有较大的影响;旋轮圆角半径和板料厚度仅对板料的壁厚减薄率影响较大,对板料的壁厚增厚率影响很小;当旋轮进给率的值较小时,旋轮进给率对普旋成形过程影响不大。基于以上研究,最后得到了合理的工艺参数取值。     

ESTABLISHMENT OF 3D FEM MODEL OF MULTI-PASS SPINNING

In order to improve the computational accuracy and efficiency,it is necessary to establish a reasonable 3D FEM model for multi-pass spinning including not only spinning process but also springback and annealing processes.A numerical model for multi-pass spinning is established using the combination of explicit and implicit FEM,with the advantages of them in accuracy and efficiency. The procedures for model establishment are introduced in detail,and the model is validated.The application of the 3D FEM model to a two-pass spinning shows the following:The field variables such as the stress,strain and wall thickness during the whole spinning process can be obtained,not only during spinning process but also during springback and annealing processes,and the trends of their distributions and variations are in good agreement with a practical multi-spinning process.Thus the 3D FEM model for multi-pass spinning may be a helpful tool for determination and optimization of process parameters of multi-pass spinning process.     

A study of the spinning force of hollow parts with triangular cross sections

The noncircular spinning is one of the recent breakthroughs of the traditional spinning processes. The spinning force is one of the important parameters for designing the spinning equipment and one of the main factors influencing the forming quality of spun parts. The variation of spinning force during noncircular spinning is considerably different from that of the conventional spinning due to the high-speed reciprocating movement of the roller induced by the variable spun workpiece profile. This paper presents an experimental investigation of spinning force characteristics of a hollow part with triangular cross sections using an octagon ring transducer based on electrical measuring method. A series of experiments using profiling driving spinning method was carried out to study the effects of the main process parameters, such as the roller feed rate, blank thickness–diameter ratio, and mandrel rotational speed, on the spinning force characteristics. The important characteristics of the force components of noncircular spinning were discussed based on the electrical measuring results. Furthermore, the variations of force components were compared with those obtained in the cases of conventional spinning and 3D non-axisymmetrical spinning. The results show that different from the conventional spinning and similar to the 3D non-axisymmetrical spinning, the three components of spinning force along the axial, radial, and tangential direction of roller vary periodically with the mandrel rotational angle. Different from the conventional and the 3D non-axisymmetrical spinning, the maximum spinning force is related to the mandrel rotational speed, even if the feed rate of roller remains constant, and increases with the increase of the mandrel rotational speed.     

MECHANISM RESEARCH FOR 3D NON-AXISYMMETRIC THIN-WALL TUBE OFFSET SPINNING

Difference of offset spinning with conventional symmetric spinning is analyzed. A 3D FEM model for offset tube neck-spinning is established and the spinning process is simulated by means of ANSYS software. Dynamic boundary and contact problems in simulation are solved. Transient stress distribution of contact area, transient strain distribution of nodes in typical section and strain distribution of the workpiece at last are attained, the place and the cause of crack are analyzed. Strain variation curves with time of offset spinning and conventional spinning are compared. It shows the mechanism difference between offset spinning and conventional spinning. In addition, simulation results show how strain distribution of typical section, thickness of some typical nodes, axial extension in left section and force of three rollers change with time. According to the study of the variation curve, material flow law along radial, tangential and axial direction is attained and the whole spinning process is studied. The simulation results discover that offset distance is the key to manufacture offset non-symmetric tube, and process parameters change with spinning angle. Experiment data really reflect different process parameters' influence on conventional symmetric and offset spinning force. Experiments accord well with simulation.     

电极丝自旋式电火花线切割加工

提出了一种全新的电极丝高速自旋的电火花线切割加工方法。论述了这种新方法中存在的一系列特殊效应及由此而带来在加工精度、表面粗糙度和加工效率方面的独持优越性。按此原理设计构成的新一代电火花线切割机床，可以有一个突破性发展。     

An analysis of force distribution in shear spinning of cone

An analytic model for calculation of shear spinning force incorporate factor of over-roll (press down) of the blank is derived. The effects of blank thickness, roller nose radius, mandrel revolution and roller feed on the spinning force are discussed. Results obtained from calculation were compared with the experiment and other theoretical predictions. It is found that the present findings yield optimum results.     

高压气瓶强力旋压工艺研究

从旋压毛坯设计、旋压后零件状态确定、旋压参数选择、旋压芯轴和旋轮的设计等几个方面,讨论某型高压气瓶瓶身强力旋压工艺。结合旋压成形试验过程,制定出合理的工艺方案。通过试验验证该工艺方案完全适应高压气瓶瓶身的加工。     

旋压件的成形质量及其控制参数

本文着重讨论了旋压件成形质量的影响因素,工艺选择以及控制方法。研究结果表明,为了得到质量良好的旋压件,除了要控制好减薄率、主轴转速、芯模和旋轮之间的间隙,迸给比、旋轮安装角、旋轮圆角半径等关键参数外,还必须要注意旋压湿度、毛坯厚度、旋压道次与热处理等问题。     

Study on compound spinning technology of large thin-walled parts with ring inner ribs and curvilinear generatrix

Given their rapid development, aerospace and other high-tech industries are in urgent need of process technology for large complex thin-walled shells represented by large thin-walled parts with ring inner ribs and curvilinear generatrix. To make up for the deficiency in existing forming methods, this paper presents a compound spinning process that integrates counter-roller spinning, multi-neck spinning, and hot spinning. The finite element models for the counter-roller spinning and multi-neck spinning forming of such parts are established, and these models can simulate the influences of different spinning process parameters on workpiece maximum equivalent stress and maximum ovality. The 2A12 aluminum alloy tube blank is used in this paper. The process parameters for obtaining the counter-roller spinning for such parts are as follows: a feed ratio of 1.0 mm/r and a roller nose radius of 8 mm. The process parameters of multi-neck spinning are as follows: a feed ratio of 3.0 mm/r and a roller nose radius of 80 mm; and the forming temperature of hot spinning is 200–250 °C. Verification by a compound spinning test found that the numerical simulation results are consistent with the process test results. The process parameters can be used for guiding the actual production of large thin-walled parts with ring inner ribs and curvilinear generatrix.     

碟形容器封头冷旋压过程三维有限元数值分析

依据有限元理论,对冷旋压碟形封头的变形机理进行了分析,应用ANSYS软件对其变形过程进行了数值模拟研究,得出了封头在不同位置成形时应力、应变的分布规律。分析了应力、应变对变形的影响,计算了旋压力,为优化工艺参数提供了有效方法和可靠依据。     

旋压辊运动轨迹设计与旋压力计算

对一步法无胎冷旋压机中的旋压辊装置运动轨迹的设计进行了分析，给出了旋压力的两种理论计算方法，并与工业样机实际测试值进行比较，为旋压机的系列设计提供了理论依据。