Optimal Design Of Vibration Qualification Rate For Cubic Inch Relay Considering Assembly Process

For cubic-inch balanced force relay,its mechanical property is still the main problem that restricts quality of product and reliability.That the unreasonable mechanism design,artificial debugging process and semi-automatic assembly process resulting in the poor quality of products is the main reason for the extremely low qualified rate and reliability of batch products in vibration test.Therefore,it is of great significance to study the robust design method and process optimization considering the assembly process,to improve the vibration resistance of the products from its performance and the assembly process and the qualified rate in vibration test.Firstly,in order to solve the operation failure of the relay in vibration test,the structure and magnetic circuit of the relay were analyzed to initially find out the vibration propagation path and weak links.Control experiment was designed with the rework products in the factory.The main factors affecting the product’s vibration resistance were initially obtained.The value of main factors were set.And experiments are carried out to further verify the main factors affecting the vibration resistance of the relay and obtain its initial failure threshold.The finite element vibration characteristics of the relay were simulated.And the response force under sinusoidal vibration and random vibration was obtained.According to the results of vibration test and simulation,the failure mode and failure mechanism of the relay were analyzed.And the failure threshold of the factors were obtained.Secondly,the relay’s assembly process was analyzed to find out the crucial assembly links and design parameters affecting the desired quality characteristic of the relay.A finite element model of the relay’s electromagnetic system was established considering the assembly design parameters,to obtain electromagnetic force under excited state and de-excited state.The Latin hypercube sampling method is used to construct the emulational sample points with assembly design parameters and components’ dimension.A fast calculation model for crucial quality characteristics based on the Kriging method was built.Generate virtual samples of batch products with Monte Carlo method and calculate the quality characteristics of batch products through the established fast calculation model.And the relay’s qualified rate in vibration test was completed with failure threshold of the quality characteristic.Then,in the parameter design,the influence of every parameter on crucial quality characteristics was analyzed to find out the parameters that have a greater influence on the quality characteristic.Multivariate analysis were performed on the parameters to verify main influence parameters.The entire combination experiment design of the main influence parameters was analyzed to obtain the optimal parameter combination.And qualified rate in vibration test was calculated.The components’ dimension and assembly design parameters affecting the key quality characteristic were selected.Based on the traditional Taguchi’s calculation method of contribution rate and established fast calculation model,the tolerance design method of variable contribution rate coefficients is adopted to complete the reasonable distribution of tolerances.Finally,based on the stream of variation theory,the process parameters of the relay’s key assembly processes were analyzed to find out the main process parameters affecting the assembly design parameters.Based on the state space equation of the variation propagation,the mathematical model between the process parameters and the key assembly design parameters was established.The final tolerance of the assembly design parameters obtained in the tolerance design was selected as optimization objective.And the process parameters are optimized with established the mathematical model and process parameters’ limit range.The auxiliary process in the relay assembly process was improved and optimized from the three aspects of spot welding process,pressure shield process and debugging process.The research result of this paper is the optimization and improvement of vibration resistance of cubic-inch relay from the assembly process and its performance.The research ideas and methods can be applied to the optimization design and assembly process’ s improvement of other electromechanical component.