Design Of Safety Belt Retractor Based On Six Sigma Method

The car safety belt is a passive safety device mandated by the state.Its main function is to reduce the collision between the occupant and the vehicle when the collision occurs,and greatly reduce the safety risk of the occupant.With the continuous development of China's economy and the continuous increase of car ownership,the rate of China's traffic safety accident remains high.These problems are mainly caused by the large population and the great pressure of road traffic in our country.However,it is more importantly because of the slow development of China's vehicle safety technology and the generally backward technology.Aiming at the problem of poor development ability and low reliability of domestic safety belt,this paper establishes a design process of a vehicle safety belt coiler based on design methods for six sigma,such as Quality Function Deployment(QFD),Design of Experiment(DOE),Design Failure Mode and Effects Analysis(DFMEA).And the process is applied to design a vehicle safety belt coiler.The research of this paper has important engineering application value for improving the quality and responding to the market quickly of our country's automobile safety belt enterprises.The main contents are as follows:(1)The design process of a certain vehicle safety belt coiler is established,which is based on design methods for six sigma.QFD technology is applied to carry out analysis from three aspects: laws and regulations,internal customers and external customers,and then to convert customer requirements into engineering indicators of automobile safety belt design.The historical quality records studied,and DFMEA in advance is completed.DFMEA and QFD are used as the design input of safety belt to determine the design index of automobile safety belt coiler and define the objective of its optimal design.(2)The working principle and structural characteristics of the locking mechanism of the safety belt coiler are studied deeply.The dynamic modeling and solving of the locking mechanism of a vehicle safety belt coiler are completed.With the solution of MATLAB,the effects on the locking acceleration of four parameters as spring stiffness,spring precompression,spring force axis distance and inertia moment of inertia swing block are studied respectively.And then the optimal design of the locking mechanism is carried out.DOE is used for parameter analysis to determine the most influential parameters and the best combination of parameters,so as to improve the reuse rate of parts where the non-important parameters are located.(3)DFMEA and the optimization parameters of lock mechanism design are inputted to complete the structural design of the safetybelt coiler assembly and parts;According to the potential failure mode analyzed in DFEMA,the finite element method is used to simulate and verify the design of a vehicle safetybelt coiler in the design stage to ensure the robustness of the design.(4)The accuracy analysis for the measurement system of a vehicle safety belt is completed to ensure the correctness of the measurement results.The performance experiment for the manual sample of a vehicle safety belt coiler and the experiment for small batch products are completed to verify the correctness of the theoretical design.