| Diode lasers have the advantages of high electro-optical conversion efficiency,rich wavelength,and long life,making them widely used in laser communication,display,medical and other fields.In addition,metal materials have a higher absorption rate for diode lasers with the 800nm-1000 nm wavelength than other lasers,making them advantageous in material processing.However,the inherent defects of low output power and large divergence angle of diode laser unit devices result in poor beam quality of high-power diode laser sources developed by the technology of beam shaping and combination,making them difficult to meet the processing requirements of many for applications,such as laser cladding,cutting,and welding.In this paper,aiming at the problems of low output power and poor beam quality of current diode laser sources,we proposed a new method for beam combination based on beam shaping and combination.By combining the beam characteristics of the diode laser source,we established a coupling model between diode laser and metal materials,studied the processing mechanism of diode lasers on metal materials,and met the processing requirements such as laser cutting,laser welding,and laser cladding.The main contributions of this paper are as follows:1.Based on the coupled wave theory model,combined with the structural characteristics of the volume Bragg grating,the diffraction efficiency equation of the volume Bragg grating is derived.Through the analysis of the diffraction efficiency,a single emitter diode laser external cavity feedback model based on the volume Bragg grating is established and a dense spectral beam combining system with an ultra-narrow wavelength interval is designed,which effectively increases the number of beam combining channels within the spectral gain bandwidth.This method develops a high-beam quality diode laser source with an output power of 2045 W and beam quality of 4.5 mm·mrad.2.Combined with the light field characteristics of the dense spectrum combined diode laser source,a diode laser coupling model based on metal surface absorption is established.The processing mechanism of diode lasers on metal materials is clarified by calculating and optimizing the key parameters such as laser wavelength,absorption rate,cutting speed,and cutting angle.Through the process experiment,the cutting of a 1 mm-10 mm thick stainless-steel plate is realized.The cutting speed and cutting quality of somestainless-steel plates are better than that of fiber laser.3.An eave-like model for the welding of 304 stainless-steel tailor-welded blanks with different thicknesses was established.Using the diode laser source developed by the dense spectrum combination,the processing technology of pre-cutting and tailor-welding of thin plate and the thick plate was explored,and the self-fusion welding forming of stainless-steel tailor-welded blanks with 1mm-2mm and 2mm-3mm was realized.Through the analysis of the welding elements of the processed samples,there is no phenomenon of element ablation.The strength tensile testing proves that the strength of the welded bead is higher than that of the base metal,which meets the application requirements of industrial laser welding.4.The cladding processing method of stainless-steel ball valves based on the diode laser source with three beam spot is proposed.The diode laser stack is employed as the unit device,and the high-power diode laser source with a three-spot output is developed utilizing the technology of polarization beam combination,wavelength beam combination,and beam shaping.Through the processing experiment,the preheating,cladding,and annealing for stainless-steel ball valve are realized with one-time processing.Through the testing and analysis of the cladded sample,there are no defects such as pores and micro-cracks in the cladding layer,which solves the technical problems of the stainless-steel ball valve cladding. |
