| Resin transfer molding developed rapidly these years, which is a composite material liquid molding technology, and it is the most important techniques for fiber reinforced plastics. In the process, resin is injected into the closed mold and infiltrate the reinforce materials, then solidify. There are four steps in this process: (1) Lay the fiber. The fiber can either be weaved into the product's shape in one time or laid into the mold layer by layer, or both; (2) Resin injection. Resin and activator are mixed in the motionless mixer before injecting by the former of the injector.;(3) Resin solidify. Heating the mold cavity so as to solidify the resin. (4) Take product out from the mold. When the resin is solidified, open the mold and get the part. The mold of RTM is closed, so the quantity of styrene volatilization is small. It can improve the working condition and satisfy the standard of harmful gas ejection. In this paper, combining the main insulative board of the open circuit insulator of the light rail RTM process, the molding theory, choice of the material, numerical simulation analyses and testing for the performance are researched.1. Study on the rheology theory for RTMThe resin filling process of RTM is analyzed, including the preparing phase, resin flow phase , resin solidify phases and some measure means for the resin permeability and penetrate ratio. Study on the mathematic model for resin filling process, including conservation of momentum equation, conservation of mass equation and conservation of energy equation.2. Materials chosen for the main insulative boardThe matri-material of the main insulator is phenol-formaldehyde resin and epoxy resins which the content is 20%-40%.Both resins have the excellent insulated capability, the high strength and stabilization .The reinforced material is non-alkali glass fiber, the good mechanical properties can be testified. The outer dope of the main insulator is the organic silicon rubber, the resistance for water and aging ,insulated capability is remarkable. 3. Study on numerical simulation of RTM filling process for the main insulative board Focused on the main insulative board of the open circuit insulator of the light rail, firstly builting the entity model for the insulator, then using Moldflow software to numerical simulate the effect of the injection pressure, resin viscosity. The results show that the injection pressure is an important parameter. During the moulding, guarantee soakaging the glass fiber effectively, reduce the injection pressure to lessen the scouring to the fasciculus. The resin viscosity is also an important parameter which has the effect on the moulding. When the resin,s viscosity is exorbitant, the flowing and soakaging will be difficult, but when the resin,s viscosity is very low, the flowing will be unstable and the production will have the disfigurement of the hole and the dry section. Adjust the place of the injection and the viscosity of the resin to reduce and eliminate the bubble of the production.The result can guide the practice production.4. The properties testing of the main insulative board of the light railFirstly, the mechanics properties are examined, Discuss the coupling agent of KH-550 and the length of the glass fiber versus the tensile strength.The binder of poly(vinyl butyral) and the other modifier have a good effect on the impact strength and the bend strength.Then the dielectric breakdown ,the creepage distance and the electrical resistance are measured and analysed. The creepage distance of 300mm is satisfied the request. Preheating will clear up the bubble to improve the performance of the electric resistance. Lastly, test the hydrophobicity and the aging resistance. The silicon rubber has a good performance on the hydrophobicity to prevent the creepage.5. The molding technics of the main insulative boardComparing the result of the test and the result of the numerical simulation, get the best technical condition. The production achieves the request and applys into the use.
|
PDF Full Text Request