Utilization of quantitative measurement categories for process monitoring

Abstract

Current laser systems with strong focusability exhibit a high innovation potential in many application ranges, for example regarding the achievable welding speed or the possibility of adjusting the welding depth to even small material thicknesses. However, the usability of these advantages is limited because the suitable process windows are considerably constricted at increased welding speed. Consequently, slight changes of the process parameters induced by minor modifications of the system technology and/or component tolerances affect the process window adversely.Controlling typical features in the welding zone during the process can clarify whether the process parameters are within the process window or not. In addition to the dimensions of the melt pool, the shape of the welding bead of the resultant weld seam is an important quality characteristic for industrial applications. This paper pursues the approach to utilize the characteristics of the emission of hot radiating surfaces. It should be kept clearly in mind that depending on the used material (e.g. steel or aluminum) an adapted monitoring wave-length has to be found. A promising range of typical wavelengths is between one and two micrometers. Using a camera system in this wavelength range together with an intelligent data processing, it can be expected to get quantitative temperature distributions in and around the melt pool and information about surface structures and shapes.Current laser systems with strong focusability exhibit a high innovation potential in many application ranges, for example regarding the achievable welding speed or the possibility of adjusting the welding depth to even small material thicknesses. However, the usability of these advantages is limited because the suitable process windows are considerably constricted at increased welding speed. Consequently, slight changes of the process parameters induced by minor modifications of the system technology and/or component tolerances affect the process window adversely.Controlling typical features in the welding zone during the process can clarify whether the process parameters are within the process window or not. In addition to the dimensions of the melt pool, the shape of the welding bead of the resultant weld seam is an important quality characteristic for industrial applications. This paper pursues the approach to utilize the characteristics of the emission of hot radiating surfaces. It should be kept cle...