| Silicone rubber elastic keys are widely used in various industries as their good physical and chemical properties.In this paper,based on the existing patch silicone elastic keys in the laboratory,a high cost performance silicone elastic key structure is proposed.Using ANSYS finite element simulation software,the key structure was modeled,thermal reflow simulation,pressing process simulation,thermal reflow test,pressing mechanics test,fatigue pressing test,temperature aging test are submitted.The effects of thermal reflow and temperature aging on the deformation of key structure,pressing mechanics and fatigue pressing life are studied.The main research contents and results are as follows:(1)At present,the silicone elastic keys developed in the laboratory mainly include inlaid QFN pin keys,thin-walled coat QFN pin keys,and embedded SOP pin keys.On this basis,a new type of machine mounted silicone rubber key for bookbinding pins is proposed in this paper.Compared with the existing keys,this key has obvious cost advantages in pin manufacturing cost,pin and silica gel body molding.Modeling,thermal reflow simulation,pressing process simulation are carried out by ANSYS.The simulation results of thermal reflow show that the structure of the new key is deformed after thermal reflow simulation,that is,the inclined wall of the key is changed from a round vertebral body to an elliptical vertebral body,and the key structure has prestress distribution.The simulation results of pressing process show that the stress concentration of the key is mainly distributed in the inclined wall of the key during pressing process.After thermal reflow,the internal stress value and the pressing value of the key are reduced.(2)According to the key model designed in(1),the samples were made,and the thermal reflow test,pressing mechanics test and fatigue pressing life test are carried out.The experimental results of thermal reflow show that the structure of the key is deformed after high temperature reflow welding,which is consistent with the deformation in the simulation of thermal reflow.The experimental results of press mechanics test show that the pressing force of the key decreases after thermal reflow,which is also consistent with the simulation results of pressing.The fatigue press life test results show that when the pressing frequency is 60 times/min,the fatigue press life of the key is at least 3.5E+5 times,and the life of the key after thermal reflow test is higher than that without thermal reflow test.(3)The same batch of key samples are aging at different temperatures.The temperature aging experiment results show that the mechanical properties of the keys are obviously affected by temperature.The higher the temperature is,the faster the mechanical properties decrease and the shorter the fatigue pressing life of the keys is.But in the ambient temperature below 95?,the key temperature resistance is good.According to the fatigue pressing experimental data,the fatigue pressing life empirical formula of the key is derived by numerical fitting method.The formula can provide useful reference value for the similar key life prediction.To sum up,the new type silicone elastic key proposed in this paper is feasible,and the research results can provide useful reference value for similar silicone rubber key products. |
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