Thermal modeling of laser drilling and cutting of engineering materials.

摘要

Lasers are used to drill small holes of high aspect ratio in difficult-to-drill materials. In this investigation, thermal aspects of laser drilling and cutting process are modeled using the Jaeger's heat source method. The laser beam is considered as a circular moving plane disc heat source. The resulting equation is a general solution, in that it can be used for transient as well as quasi-steady state conditions. It can be used with different laser beam distributions, such as normal, bimodal, and uniform. Simpson 1/3rd numerical integration method is used to solve the heat source equation and programmed using Visual Basic.NET.; Temperature rise at any time and at any location in the workpiece drilled or cut is determined using the laser beam parameters and the thermal properties of workmaterials, such as AISI-1036 steel, and CP-titanium. Fusion and evaporation temperatures of the workmaterials are used to calculate the amount of material removed by each laser pulse for a given laser beam parameters. The effect of latent heat of fusion and evaporation are considered. Effect of different laser beam parameters, such as energy density, beam radius, and pulse duration on the profile of laser drilled hole and cut materials are investigated. Mass and energy balance were done for the laser machining process. Using this method, the number of laser pulses required to drill a hole of required depth and diameter can be calculated. Heat affected zone (HAZ) calculations were also performed for different materials.