Research On Instrument Panel Implicit Weakening Line And Laser Weakening Process

The application of the implicit weakening line makes the front side of the instrument panel free of visible gaps,which enhances the aesthetics of the interior while ensuring the smooth deployment of the airbag.In order to avoid irregular cracking or spattering debris of the instrument panel due to the impact of the airbag under different temperature conditions,it is necessary to find a more reasonable weakening line arrangement path and the optimal residual thickness of the instrument panel material to improve the tearing effect of the weakening line.At present,the processing technology of weakening lines mainly includes weakening of tools（cold and hot knives）and weakening of lasers.The laser weakening process is gradually replacing the traditional tool weakening process because of its high processing precision and flexibility.However,the formulation of the process parameters is difficult.Using the traditional“trial-and-error method”not only cannot guarantee the processing accuracy but also consumes a lot of manpower and material resources.In this paper,the related structure and laser weakening process of PC/ABS material instrument panel weakening line are studied.The arrangement path and optimal residual thickness of weakening line with good tearing effect are explored.Establish high-precision prediction models to achieve accurate prediction of machining results and provide efficient solutions for process parameters selection.In this paper,by studying and comparing the stress distribution characteristics and tearing patterns of different weakening line layout paths,it is proposed to add a 90°linear bifurcation structure at both ends of the transverse weakening line in the middle of the H-shaped arrangement path,so that the vertical weakening lines on both sides are also can be quickly torn with the deployment of the airbag.The LS-DYNA explicit dynamics algorithm was used to simulate the dynamic simulation of different residual thickness models,and the tearing force of different residual thickness weakening lines was obtained.A suitable residual thickness range is obtained according to the tearing force requirement.Then,by applying the reverse pressure,the pressure bearing capacity of the instrument panel under different residual thicknesses is calculated,and the optimal residual thickness of the weakening line is determined according to the tearing force and the bearing type requirements.Using CO₂ laser,pulse width,defocusing amount and processing speed are the influencing factors of the test,residual thickness is the evaluation index,single factor and orthogonal test are designed to explore the influence of process parameter change on residual thickness.It is found that the residual thickness decreases with the increase of the pulse width,and increases with the increase of the processing speed.The defocus amount has a nonlinear effect on the residual thickness.The significance of the three factors on the results is pulse width,defocusing amount and processing speed from high to low.A BP neural network was constructed and trained using orthogonal experimental data.The genetic algorithm is used to optimize the weight and threshold of the BP network to improve the accuracy,stability and convergence speed of the training.The optimized GA-BP neural network was used to predict the processing results of different process parameter combinations.According to the requirements of energy consumption,processing efficiency and error,the appropriate process parameters are formulated.