A novel control strategy for the multi-step straightening process of long/extra-long linear guideways

Abstract

The straightening process for a linear guideway with particular cross-section shape is normally conducted by the three-point pressure bending method. However, the single-step straightening process (SSSP) of a long/extra-long linear guideway may make the workpiece from a single-curvature curve into a more complex shape. Due to these limitations of SSSP, a quantitative control strategy for the multi-step straightening process (MSSP) of a long/extra-long linear guideway is proposed in this paper based on the straightening principle of SSSP. Firstly, the predictive models for straightening stroke and helix angle after unloading with respect to SSSP are developed based on the elasto-plastic theory and curvature integral model. Depending on the established analytical model for SSSP, the MSSP is then mathematically modelled to obtain corresponding straightening parameters considering feeding process, clamping process and straightening process. Besides, the finite element method has been applied to validate the developed mathematical model for the MSSP. Taking the approach of a linear guideway as an example, the experimental results have also shown that the proposed control strategy is appropriate for the MSSP of a long/extra-long linear guideway.

Variable Span Multistep Straightening Process for Long/Extra-Long Linear Guideways

“…If the deflection δ i > 0, the straightening step would generate in the tensile coordinate system {S S : O S − X S Y S }.The angle of rotation at the supporting points during single-step straightening process can be calculated as in [20]. (15) where, θ f = M x l/ (4EI ) is the angle of rotation during the elastic springback.…”

“…in a 'S' shape or a multi-peak shape). Our previous work investigates the initial deflection-straightening stroke model and the angle of rotation of the deflection curve on the supporting points [20]. Then, a fixed-step multistep straightening process (FSMSP) was proposed for the long linear guideways with complex deflection curves, considering the angle of rotation caused by single-step straightening and the relationship between different straightening steps.…”

Billet Straightening by Three-Point Bending and Its Automation

“…Modern steel factories and enterprises of heavy industry, whose field of activity includes the production of long metallic articles, meet the issue of effective straightening of such products. Typical products that involve straightening during their production technology are billets [ 1 , 2 ], strips [ 3 ], railway rails [ 4 ], elevator guide rails [ 5 ], or more general long linear guideways that enable precise linear motion of machines [ 6 ]. For the mentioned commodities, there are only two straightening principles that mostly used in technical practice.…”

“…Each type of billet shape requires a unique approach to the straightening, which minimalizes the time of the process. This is the so-called multi-step straightening mechanism [ 6 , 19 ], for which functionality is necessary to correctly determine the velocity of the straightening force/stroke, the distance of supports, the number of straightening steps, and so on. Different parameter settings return differently straightened billets [ 5 ].…”