Preheating and thermal behaviour of a rotating cylindrical workpiece in laser-assisted machining

Abstract

Laser-assisted machining is a widely used technique for preheating workpiece to reduce cutting forces and promote machinability in metal machining, thereby enhancing manufacturing quality and productivity. In setting laser-assisted machining parameters, the current practice typically relies on trial-and-error approaches. The uncertainties thereof could lead to adverse outcomes in product manufacturing, thus negating the potential benefits of this machining method. A clear understanding of workpiece thermal behaviour under laser spot heating is pivotal to developing a systematic basis for determining required preheating levels and optimised cutting variables for laser-assisted machining. In achieving this, the experimental methods are recognised to be largely impractical, if not tedious, due to instrument limitations and practicality of suitable non-intrusive measuring methods. Conversely, numerical methodologies do provide precise, flexible and cost-effective analytical options, warranting potential for insightful understanding on the transient thermal impact from laser preheating on rotating workpiece. Presenting such an investigation, this article presents a finite volume-based numerical simulation that examines and analyses the thermal response imparted by laser spot preheating on a rotating cylinder surface. On a rotating frame of reference using the ANSYS Fluent solver, the numerical model is formulated, accounting for transient heat conduction into the cylinder body and the combined convection and radiation loses from the cylinder surface. The model is comprehensively validated to ascertaining its high predictive accuracy and the applicability under reported laser-assisted machining operating conditions. The extensive parametric analyses carried out deliver clear insight into the dynamics of thermal penetration occurring within the workpiece due to laser spot preheating. This facilitates appropriate consideration of laser preheating intensity in relation to other operating variables to achieve necessary material softening depth at the workpiece surface prior to setting out on the subsequent machining process. Building upon the data generated, a practically simpler and cost-effective preheating parametric predictor is synthesised for laser-assisted machining using neural network principles incorporating the Levenberg–Marquardt algorithm. This predictive tool is trained and verified as a practical preheating guide for laser-assisted machining for a range of operating conditions.

Study on the Performance of laser-assisted fast tool servo machining device for glass-ceramic

“…The relationship between stiffness matrix and flexibility matrix can be expressed by K h = [B] 21 , and the k R can be obtained from equation (6).…”

“…18 Although FTS can efficiently cut optical free-form surface, glass-ceramic is a hard and brittle material that is easy to break and crumble under high cutting force. Laser-assisted machining (LAM) is an efficient technology for machining hard and brittle materials, 19 such as engineering ceramics, 20 hardened steels, 21 metal matrix composites, 22 and so on. LAM can effectively reduce yield strength, cutting force, and tool edge collapse by locally heating and softening the material.…”

Optimization Method of Sheet Metal Laser Cutting Process Parameters under Heat Influence

“…Pan et al [17] simulated the scanning of a rotating laser and approximated the absorption ratio based on the molten zone prediction. Nadim et al [18] studied thermal phenomena during laser irradiation using a finite element model, including the influence of jet cooling and different laser beam power distributions. In most of these researches, the authors focused on the thermal effects during cylindrical and thick plate cutting, with little investigation into the thermal effects and temperature field variations during thin plate processing.…”

Thermo-mechanical aspects of cutting forces and tool wear in the laser-assisted turning of Ti-6Al-4V titanium alloy using AlTiN coated cutting tools

“…They noted that the errors of both models were below 10% and stressed the necessity of use a systematic approach for laser absorptivity determination in order to improve model accuracy. Finally, Nadim et al [24] investigated the thermal phenomena during LAM with a FE model, including the effect of air jet cooling and different laser beam power profile. After validating the model with various experimental data, they were able to determine also the thermal penetration depth in each case.…”