Abstract
When manufacturing large shafts with multi-specification and small-batch production, both the conventional forging and rolling process bring a high tooling cost due to heavy forging press or large-sized specialized roller. In this study, a novel flexible skew rolling (FSR) process is proposed by adding degrees of freedom to the rollers as compared to the typical skew rolling process. Since each of the FSR rollers has three degrees of freedom (circle rotating, radial rotating, and radial feeding), the FSR process can be divided into four stages: radial rolling, rollers inclining, skew rolling, and rollers leveling. Therefore, the FSR process can produce various shafts with the same rollers via programming different movements. To verify the feasibility of FSR process, a physical investigation corresponding with a numerical simulation for a single-step shaft is undertaken with a Φ80 × 390 mm C45 steel billet. According to the results from physical experiments and numerical simulations, the FSR formed shaft has a maximum deviation of 0.99 mm, and its microstructure and properties have been improved obviously. Moreover, although there is a tendency of the center crack in FSR products as predicted by numerical results, both the transverse and longitudinal sections of the physical shaft are free from central cracking. The major forming defects that existed on the rolled shaft are knurled pockmarks, surface threads, and side cavity, which are the typical defects of the conventional skew rolling and cross-wedge rolling and can be removed by machining. To the authors’ knowledge, this novel process has a good combination of flexible production and less loading, which will be of great engineering significance to reduce the tooling cost in large shafts manufacturing.
Highlights
Large shafts play an important role in large-elongated axial parts manufacturing and die-forging billets preforming, which are widely used on transportation vehicle, aerospace, construction machinery and other indutrial clusters, such as railway axles [1, 2], truck shafts [3], preform of turbine blade [4] and railway switch [5]
Skew rolling can be automatically driven by the axial component of friction, so that the drawing force of the chuck can be significantly decreased. All these mentioned processes, whether in axial feed rolling, copy skew rolling or CNC skew rolling, a chuck is required to draw the workpiece in axial direction that may cause the limitations of :1) a considerable amount of chucking allowance is indispensable that the material utilization is reduced; 2) the maximum length of the rolled shaft is limited by the chuck stroke of the mill
The corresponding flexible skew rolling (FSR) finite element (FE) projects were performed in Simufact.Forming software, which has been successfully employed in t numerical analysis of cross-wedge rolling process [26, 27] and skew rolling process [2, 28], and their FE results have a good agreement with experimental results
Summary
Large shafts play an important role in large-elongated axial parts manufacturing and die-forging billets preforming, which are widely used on transportation vehicle, aerospace, construction machinery and other indutrial clusters, such as railway axles [1, 2], truck shafts [3], preform of turbine blade [4] and railway switch [5]. Due to the tapered rollers are inclined to each other, the rolling workpiece of copy skew rolling and CNC skew rolling can be automatically driven by the axial component of friction, so that the drawing force of the chuck can be significantly decreased All these mentioned processes, whether in axial feed rolling, copy skew rolling or CNC skew rolling, a chuck is required to draw the workpiece in axial direction that may cause the limitations of :1) a considerable amount of chucking allowance is indispensable that the material utilization is reduced; 2) the maximum length of the rolled shaft is limited by the chuck stroke of the mill. Several types of physical experiments are performed to explore the FSR applications and reveal the FSR forming defects
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have