Manufacturing large shafts by a novel flexible skew rolling process

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-size 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 34 degrees of freedom (circle rotating, radial rotating and radial feeding), the FSR process 35 can be divided into four stages: radial rolling, rollers inclining, skew rolling and rollers 36 levelling. Therefore, the FSR process can produce various shafts with 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 center crack in FSR products as predicted by numerical results, both the transverse and longitudinal section of the physical shaft are free from central cracking. The major forming defects 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.

The Mechanism of Forming Hollow Shafts with Constant Wall Thickness by Three-Roll Skew Rolling

“…Pater and Walczuk-G ągała [22] proposed a concept for manufacturing hollow axles using three skewed rolls, an axially moving chuck, and a moving mandrel, with numerical simulation confirming the method's feasibility. Lin [23] described a novel flexible skew rolling (FSR) process for manufacturing large shafts, offering a good combination of flexible production and less loading. Murillo-Marrodan [24] studied the performance of various friction models in a skew rolling process numerical simulation, using FORGE ® software to analyze their effects on consumed power, plastic deformation, and surface temperature.…”

Forming Quality Research on the Variable-Diameter Section of the Hollow Axle in Three-Roll Skew Rolling

“…An innovative flexible skew rolling (FSR) with increased roll freedom was also proposed and verified by Lin. FSR can be used to manufacture large shafts with multiple specifications and small batch by programming four stages of motion, namely, radial rolling, roll tilt, skew rolling and roll straightening [22,23].…”