Controlling of compliant grinding for low-rigidity components

Abstract

The machining of low-rigidity components (e.g. thin-walled) with compliant tools presents accuracy challenges as both sides in contact are being deformed. The controlling method presented in this paper enables, for the first time, to obtain the desired and uniform material removal rate by controlling the nominal tool offset when two bodies (workpiece and tool) are compliant in grinding. A contact deformation model is proposed to predict the relation between the nominal and actual tool offsets. The function of nominal tool offsets and material removal rates is obtained based on the calibration tests. Spot grinding tests have been performed for the validation of the calculated material removal rates, normal grinding forces and spot sizes, presenting position-dependent characteristics. The controlling method has been tested for the case of continuous grinding the whole area of a circular aluminium thin wall. The surfaces ground under the time-variant tool offsets (proposed approach) reach the desired removal depth with an average error of ≤10% and achieve 11.2μm~24.2μm (P-V) accuracy in the elastic domain, compared with the error of 76.8%~113.7% and accuracy of 42.6μm~50.1μm (P-V) in the circumstance of constant tool offsets (conventional approach).

Adaptive Optimization Method for Prediction and Compensation of Thin-Walled Parts Machining Deformation Based on On-Machine Measurement

“…Li et al [ 10 ] designed a thin-wall micro-milling deformation compensation device, which, combined with a mathematical model based on the Rayleigh–Ritz theory to calculate thin-wall deformation, can compensate for micro-straight thin-wall machining errors. Yang et al [ 11 ] proposed a flexible grinding control method for low-stiffness parts to achieve uniform thickness of the removed material. The model considers the case of dual flexibility of the workpiece and the tool and is capable of compensating both thin-walled workpiece deformation and tool deformation at nominal tool offsets.…”

Post-processing of additively manufactured metallic alloys – A review

“…The abrasive slurry consisted of stainless steel and SiC bound by a straight oil. Process modelling was founded on well-established Preston's lawcommonly employed in modelling of material removal in a variety of abrasive finefinishing processes, such as vibratory finishing [157], (bonnet) polishing [158,159], and compliant grinding [160,161]. According to Preston [162], the material removal rate is proportional to the relative velocity between the abrasive and the workpiece surface, the applied pressure and processing time.…”

A material removal model for nonconstant-contact flexible grinding

“…But with the growing application of FGP, the grinding situations and the structure of the parts become more complicated as well as the contact, which makes the mentioned simplifications irrational sometimes. For example, the deformation of low-rigidity parts may also influence the calculation of contact [18] and the contact may not be steady due to the grinding vibration [19], causing invalidation of the existing models. The above situations call for an improvement of the existing models.…”