Papers by Keyword: Cross Wedge Rolling (CWR)

Abstract: Based on the motion relation between rollers and work piece during cross wedge rolling (CWR) process, roller profile equations for cam forming were studied. A three-dimensional entity model of the roller was established using the profile equations. Process of cam forming by CWR was simulated by DEFORM-3D. The FEM data was used to analyze dimensional accuracy of the formed cam. Results demonstrate that the equations can be used in roller design for cam rolling.

Abstract: Central cavity in the workpiece of cross wedge rolling is a high-level product defect which would seriously weaken the strength of material. Based on the three-dimensional elastic-plastic finite element analysis method, numerical simulation of cross wedge rolling parts with minute central cavities was performed. The area changes of the minute central cavities were obtained, and combined with the internal stress state during the rolling process, the viewpoint that tensile stress in the three-dimensional directions is one factor that leads to cavity growth was expound.

Abstract: The use of cross-wedge rolling method in metal-working industry allows development of new high-productive low-waste technologies designed to produce shaped billets for subsequent precision forging or other plastic forming processes. The paper deals with spheres of application, advantages and disadvantages of flat and roller cross-wedge rolling schemes. The equipment and tooling for flat cross-wedge rolling are described.

Abstract: One direction of the cross wedge rolling technology is to realize high-efficiency, precise and near-net-shape forming hollow axle with multi-wedge synchrostep cross wedge rolling. This paper deduced the rotated condition of forming hollow shaft with multi-wedge cross wedge rolling (MCWR) base on forming solid shaft with single-wedge cross wedge rolling, and analyzed technics parameters on the influence of rotated conditions. Through the finite element simulation we got rolling technics parameters on the effect of rolled piece and selecting principle, and then created the 3D model of the equal diameter period of hollow axle with the MCWR. By using DEFORM-3D software, the process of rolling equal diameter period was simulated. The result indicated that it is feasible to roll hollow axle with multi-wedge synchrostep by cross wedge rolling.

Abstract: The feature of the gear shaft with Cross wedge rolling technology is high efficiency, low material loss and higher strength of the gear shaft forming. A research model of cross wedge rolling plastic forming adopting tri-dimensional thermal elastic-plastic finite element method is put forward. Forming mold divided into two parts as the wedge-shaped molds and tooth mold is designed. Depending on orthogonal test program, applying Deform-3D to numerical simulate for the gear shaft with cross wedge rolling, the influence of temperature, number of teeth, module and feet rate for gear shaft tooth forming quality is studied. The results are analyzed with the temperature of the workpiece, number of teeth, module and feet rate of the die movement during CWR and the best combination of produce conditions is reached.

Abstract: The mold for cross wedge rolling (CWR) is difficult in making, complicated in adjustment and high in costs. It is extremely meaningful to optimize the parameters for wear reduction to extend the mold life. This paper analyzes the influence of the processing parameters on the mold wear based on orthogonal experimental design method and the computer simulation method, which can optimize the parameters in an efficient and simple way. The results show that the rolling process using optimized technological parameters can greatly extend the mold life of the cross wedge rolling.

Abstract: Microstructure evolution is an effective means to improve the mechanical properties of products, shaft parts formed by cross wedge rolling is not only the shape of the formed parts, but more importantly it improves the comprehensive mechanical properties of the products by deformation. Therefore, the paper sets up the coupled rigid-plastic finite element model with deformation-heat transfer-microstructure by using nonlinear finite element method, and this model is adopted to make simulation calculation for the forming techniques of asymmetric shaft parts of cross wedge rolling based on parity wedge, specifically analyzes the rule of dynamic recrystallization and grain size distribution in the asymmetric rolled parts. The results show that the grain in the wedging place of asymmetric shaft parts of cross wedge rolling based on parity wedge can be obviously refined, and the research results of this paper may provide theoretical foundation for further improving the quality and mechanical properties of asymmetric shafts parts of cross wedge rolling.

Abstract: The analysising of strain is the key factors to understand the forming mechanism of cross wedge rolling asymmetric shaft. due to the extrusion of dies and other external force, its interior,interactions can cause the relative position between the various parts. In order to study the deformation of workpiece at different degrees, pulling in the finite element strain field analysis, the strain of the analysis at deformation process is also a necessary precondition for forming and stress distribution. In this papre,By using Deform3D platform, the forming process of the cross wedge rolling on parity wedge asymmetric shaft is simulated. It is also to be analyzed the distribution and variation of the amount of strain in the rolling process, it shows that a cross-sectional and longitudinal section about the deformation characteristics of the strain fields, the results can achieve production of cross wedge rolling and provide important theoretical foundation to promote further cross-wedge rolling.

Abstract: Because most of the asymmetric shaft-parts have relatively large size in the axial direction, single-wedge cross-wedge rolling (CWR) exposes many imperfections, such as the huge roller, higher cost etc. The paper adopted finite element method (FEM) to simulate multi-wedge synchrostep CWR (MS-CWR) based on the typical asymmetric shaft-part, and gained its distribution and characteristics of stress and strain. In the knifing stage, the deformation of work piece only emerges on the local region, but in the stretching stage, most of regions are observed the deformation except two ends of the billet and the transition position between inner and outer wedge of multi-wedges. The results offer theoretical basis for promoting and applying MS-CWR technology on asymmetric shaft-parts.

Abstract: Based on the constitutive relationship of 4Cr9Si2 martensite refractory steel obtained by Gleeble-1500 hot simulation isothermal compression, a finite element model of Cross Wedge Rolling was build up for 4Cr9Si2 Martensite and the heat conduction, convection, plastic work and friction work were taken in account in the model. The forming process of 4Cr9Si2 martensite refractory steel by cross wedge rolling was simulated by means of DEFORM-3D software. The influence regularities of temperature of rolling process parameters were obtained: temperature rise rapidly result from plastic work and friction work in the cross-section at the process of rolling, with the completion of rolled piece cross-section, temperature descending due to heat conduction and radiation with atmosphere. The rolled piece temperature difference decrease with rolling speed and die preheat temperature increasing, the billet heating temperature is little for rolled piece temperature difference compared with rolling speed and die preheat temperature.