Numerical simulation of tube profile growth during spray forming process

Spray forming is a new type of metal material forming process,which can produce metal blanks such as billet,tube,plate etc.A mathematical model has been developed to forecast the shape evolution of tube billets during the spray forming process.The atomizer mass flux as,radial distribution coefficient bs,draw velocity and diameter of mandrel were considered in this model and the influence of different parameters such as metal flowrate,draw velocity of mandrel,diameter of mandrel on the tube’s shape change were simulated and analyzed in this paper.The simulation results obtained from this model can be provided to engineers as reference.     

Forming evaluation of complex tube hydroformed components

Abstract

Currently, the main feedstock of tubular blank material for tube hydroforming is derived from slit steel coil, which has been roll formed and electric resistance welded (ERW). From ERW tubular blank, a number of intermediate processing stages such as prebending and preforming may be necessary to achieve the final formed component. The end result is a component that may have experienced a complex strain path history. The traditional forming limit (strain) curve (FLC) is inherently affected by non-linear strain paths; hence, a suitable alternative forming limit criterion has been studied and is proposed for complex tube hydroforming processes. The criterion proposed is the forming limit stress curve (FLSC), which is theoretically independent of strain path and prestrain history. The methods used to generate the FLC and FLSC for tubular blanks are described, and prebending is used as an example to demonstrate how complex tubular component forming operations, and subsequent formability, may be evaluated through use of the FLSC.     

Design of hydroforming process for an automobile subframe by FEM and experiment

Tube hydroforming technology has shown the attention of the automotive industry due to its advantages over conventional stamping and welding methods.In this study,the tube hydroforming process including tube bending,preforming and hydroforming process for an automobile subframe is analyzed and designed by the simulation software AutoForm of a finite element method (FEM) program.A parametric study is carried out to obtain the effect of the forming parameters such as initial tube size and loading path on the forming results.The simulation results are also compared with experiment results.The research indicates that the multiple forming operation of the tube hydroforming process can be simulated accurately by using the implicit code AutoForm,and the formability of tube hydroforming can be improved by designing suitable forming parameters.     

成形工艺对冷弯方管残余应力及焊接微观组织的影响简

 冷弯方管成形有“直接成方”和“圆成方”两种方式。为了研究成形工艺对于产品的不同影响,以规格为100mm×100mm×6mm,材料为Q235的两种成形工艺的方管为研究对象,采用钻孔法对方管各个部位的残余应力进行了测量,并观测了焊缝处的显微组织。研究结果表明,不同成形工艺对纵向残余应力的分布影响较大,焊缝处的残余应力最大。“圆成方”过程中施加较大的焊接压力使得其焊接热影响区宽度小于“直接成方”工艺条件下焊接热影响区的宽度,且抑制了奥氏体晶粒长大,冷却后获得较为细小均匀的晶粒。     

The microstructure and recrystallization of flow-formed oxide-dispersion-strengthened ferritic alloy: Part I. Deformation structure

Oxide-dispersion-strengthened (ODS) alloy tubes with a nominal composition of Fe-19.5 pct Cr-5.5 pct Al-0.5 pct Y₂O₃ have been cold flow formed to deformation levels between 72 and 92 pct. The deformation structure of the tubes has been studied using a variety of techniques including transmission electron microscopy (TEM). The deformation cells produced by flow forming are elongated in both the hoop and axial directions, especially at deformation levels above 80 pct. In this case, most deformation cells can be regarded as ribbons, lying roughly along the “rolling direction,” which for flow forming is a helix around the tube surface. No obvious particle alignment was found in the tubes. Although the initial grain size is submicron, transition bands composed of parallel-sided long deformation cells similar to those in deformed single-crystal specimens have been observed in the transverse section of the tubes and a macroscopic shear band has been observed in the longitudinal section of the 92 pct deformed tube.     

一次成型的多层卷焊管的试验研究

介绍了４层卷焊管的卷曲方法以及孔型设计的方法，通过对１０机架成型机组卷曲４层卷焊管的试验分析了影响多层卷焊管成型的因素，提出了成型力能参数的测试方案和观察试验方案，对试验结果进行了分析。并根据试验结果，对４层卷焊管的孔型设计提出了若干改进方法。     

Tailored Profiles Made of Tailor Rolled Strips by Roll Forming – Part 2 of 2

The main scope of the presented work is to demonstrate the potential of load optimized tubes with a varying thickness distribution in circumferential direction produced by roll forming. As initial material a so called Tailor Rolled Strip (TRS) sheet metal coil produced by Strip Profile Rolling (SPR) method was used instead of plain sheet. The TRS sheet metal is manufactured in a continuously working process by rolling one or more groves in transverse direction into the sheet metal coil. In this paper, the secondary forming of the TRS sheet metal to TRS tubes is investigated by means of FE‐simulations and roll forming experiments. To simulate the manufacturing process of the TRS tube by FEM, an integrated consideration of the process is necessary because of the large local strain hardening in the groves of the initial SPR sheet metal. In experimental roll forming operations welded tubes could be manufactured successfully. The geometrical and material properties of these tubes are analyzed. The reprocessing of TRS tubes by hydroforming is investigated by means of tube bursting tests. It has been found that an additional annealing process is necessary to achieve deformations in the grooved area during the hydroforming process.     

20钢管坯表面裂纹研究

详细分析了新钢公司20钢管坯表面裂纹的类型、产生原因、形成机理,针对原管坯生产中的工艺问题提出了改进措施,按新工艺进行了工业性生产试验.试验结果及一年来的生产实践证明,按新工艺生产的20钢管坯表面质量明显改善,表面裂纹明显减少,风铲报废率显著降低.     

三辊连轧管(PQF)的计算机仿真

针对影响连轧管产品质量的几大关键因素进行了三维弹塑性大变形有限元分析，建立了相应的各种分析模型，以动态图形形式的模拟了变形过程与壁厚变化规律，为产品工艺设计提供科学依据。     

钢管圆周剪切法的实验研究

介绍一种新的钢管剪切方法－－圆周剪切法。其原理是让剪切刀刃绕某一中心点旋转沿钢管圆周逐步进入，以实现钢管切断，通过运动分析阐述了剪切金属的变形过程；实验研究证明了方法的合理性，并对切口断面的质量进行了分析。