Research On The Principle And Equipment Of Hollow Glass Microsphere Enhanced Reactive Injection Molding

Reinforce Reaction Injection Molding(RRIM)technology is the latest in Reaction Injection Molding.RIM)technology in the raw material to add reinforcement to improve the physical and mechanical properties of the new composite material molding technology.Hollow Glass Microsphere(HGM)is used as filler in the field of polymer composites due to its high compressive strength,light weight,wear resistance and corrosion resistance and low thermal shrinkage coefficient.HGM can not only make the composite material have obvious weight reduction and sound insulation and heat preservation effect,but also the glass beads are broken when the product is impacted,which effectively provides the collapse space,so that it has a good buffer performance.Computational Fluid Dynamics(CFD)is a new computer technology emerging in recent years,which can obtain physical quantities such as velocity,pressure and temperature at a certain location and key points in a flow field and their changes over time through preset boundary conditions and calculations.According to the actual production demand,the RRIM technology principle and equipment products with hollow glass beads as reinforcement and rigid polyurethane foam as matrix are studied in this paper.The main work is as follows:(1)The collision of POLY(polyol)and ISO(isocyanate)phases with different HGM mass fraction in horizontal coaxial collision,horizontal Y-type collision and vertical staggered collision mixing head mixing chamber was simulated by CFD software.Multiple boundary conditions were designed by changing flow rate and viscosity.The numerical values and variation trends of the key physical quantities on the axis are obtained.Finally,the flow of HGM in the whole mixing process was analyzed by particle tracer.(2)Design and test the precise measurement part of enhanced reaction injection molding.A piston metering device driven by ball screw was designed to achieve the maximum storage of single component material up to 8000 m L,the maximum injection and discharge speed up to150mm/s,the maximum injection pressure of 150 bar,the maximum allowable difference of repetition accuracy within 0.05% and other indicators.The recommended selection of screw and motor was carried out.Then,a single component measurement test was carried out to characterize the precision of the machine designed by using the lead screw driven piston as a measuring unit.It was found that with the increase of mass flow rate,the repetition accuracy decreased.With the increase of hollow glass microsphere content,the difference between the mass of the injection quantity and the set value increased and was lower than the set value,but the repetition accuracy improved.(3)Designed and built the principle prototype,which uses the motor to drive the lead screw to realize the mixing of metering and injection.By adjusting the motor speed,the mixing of different proportions can be realized,and the pneumatic switch can be controlled.At the same time,the prototype mold can realize the hydraulic drive opening and closing.Then,different mass fractions of hollow glass microbead polyurethane foam materials were prepared by using the prototype to test the mechanical properties.It was found that the bending strength and bending modulus of the spline increased with the increase of the hollow glass bead content,and reached the maximum value when the content was 7.5%,and then decreased.The bending modulus and bending strength increased obviously in the stage of 0%-7.5%,while the bending strength decreased rapidly but the bending modulus decreased slowly in the stage of 7.5%-12.5%,which was due to the decrease of the form variable caused by the material becoming brittle.From microscopic fracture analysis of rigid polyurethane foam without hollow glass beads bubble hole large distribution and bubble pore structure is not round,with hollow glass beads of rigid polyurethane foam caused by hollow glass beads viscosity increases with the function of nucleating agent at the same time highlight reasons influence,make bubble hole density,fruity and evenly distributed.