Study Of In-line Precision Planing Technology For Laser Tailored Welding

Laser tailored welding technology is the use of laser energy,the different thickness,material,coating of the plate to automatically put together and welding process method,laser tailored welding plate is mainly used in automotive body-in-white manufacturing,is one of the main ways to achieve light weight and energy-saving automotive emissions reduction.Due to the small diameter of the laser spot and its limited melting range,laser tailored welding is very sensitive to the pre-weld butt gap and the size of the pre-weld butt gap will directly affect the quality of the weld.Weld preforming technology is a pre-weld pre-processing technology,i.e.a series of techniques or methods designed to reduce the butt gap before welding.Although more research has been done at home and abroad on weld seam preforming technology,proposing a variety of methods such as extrusion forming,lapping forming and fillet filling,which have achieved certain results,there are derivative problems such as increasing the process and adding dissimilar materials.In-line precision planing technology is one of the pre-forming technologies for laser sputtering welds.It is proposed to use in-line precision planing process to directly improve the flatness of the joint edge of the plate,thus effectively solving the problem of weld gap,which saves processing time and simplifies the process due to in-line operation.At present,there is no detailed theoretical research on laser welding In-line precision planing technology in China and abroad,and this thesis intends to carry out research work in this direction.The essence of precision planing technology is the finishing of thin plate joints using a wide edge planing tool.Based on shear theory,this thesis presents a theoretical analysis of the cutting forces during precision planing and establishes a theoretical calculation model of the cutting forces for the right-angle cutting process and the bevel cutting process,which provides the basic data for the subsequent mechanism design.Based on orthogonal tests,25 sets of simulations were carried out for the precision planing process to obtain cutting forces,flatness parameters and the comprehensive evaluation indexes of the two parameters;extreme difference analysis and ANOVA were carried out for the three,and the order and significance of the influence of process parameters and tool geometry parameters on cutting forces,flatness and comprehensive evaluation indexes were obtained.The process parameters and tool geometry parameters of the precision planing process were optimised.Based on the result data obtained from the orthogonal test,the prediction model of cutting force and flatness was established using BP neural network;the BP prediction model was used as the fitness function of genetic algorithm for parameter optimisation,and the optimal combination of parameters was obtained,the optimum process parameters were: cutting speed of 314.81 mm/s,depth of cut of 0.13 mm,and the optimum tool geometry parameters were: front angle of 28.82°,back angle of 8.36° and edge inclination of 1.66°.Based on the optimised results,the simulation of the precision planing process was carried out again and the results showed that: the cutting combined force was reduced by 16.68% and the flatness was optimised by14.11%;for the problem of large burrs at the beginning and end of the precision planing process,the staggered extrusion method was proposed,a small staggered extrusion action was added to the butt joint,which significantly reduced the size of the burrs and further reduced the weld gap.Combined with the process characteristics of laser tailored welding,the process flow of in-line precision planing is designed,and the overall structure of the in-line precision planing mechanism is designed in detail based on the optimal combination of parameters and the requirements of the precision planing process.In this thesis,we study in depth the in-line precision planing technology of laser tailored welding,which can effectively solve the problem of butt gap,and the research results are of great significance to improve the quality of the weld seam of laser tailored welding and to improve the technical level of domestic laser tailored welding equipment.