Study On The Technology And Equipment Of Polymer Spouted-accumulated Forming

With the development of pipeline transportation industry,the demand for pipeline transportation capacity is getting higher and higher,and the application of large diameter plastic pipe is more and more widely.Researching and producing the large diameter plastic pipe of high strength,light weight,impact resistance and corrosion-resistant is one of the main development direction of future pipeline transportation industry.Firstly,the forming methods and their research status,existing problems and development trend of large diameter plastic pipe were summarized in this paper.In order to solve the problems existing in the traditional forming methods of large diameter plastic pipe,the polymer melt spouted-accumulated forming technology,which was combined the additive manufacturing with traditional molding technology like extrusion molding,was put forward.The principle of this new technology is that the polymer melt jet and fill the constrained room formed by the calendering device,pipe billet and retaining block under the action of extrusion pressure,and spiral-accumulate the pipe under the action of the calendering device and the traction machine.Then,according to the principle of the polymer melt spouted-accumulated forming technology,the large diameter plastic pipe spouted-accumulated forming equipment was researched and developed.The equipment is composed of extruder,pipe forming device,hauling machine,control system,etc.Compared with the traditional pipe forming equipment,the equipment does not need any mold like extrusion die,winding core and so on,but also can form a pipe flexibly,which can form plastic pipes with ?749~?948 mm external diameter and 30~50 mm wall thickness.Next,the main process parameters of the forming process were analyzed,including forming temperature,screw speed,traction speed,rotation speed,pitch,etc.Then the parameters of the numerical simulation and experiment were set up and calculated according to the mathematical relationship between the process parameters.Afterwards,the mathematical model and geometric model were established according to the principle of the polymer melt spouted-accumulated forming technology,and the numerical simulation analysis was done by using POLYFLOW software.Then,the velocity distribution,temperature distribution and local flowing law of the melt were analyzed,and the numerical simulation analysis was carried out combined with drawing speed,rotation speed,cooling temperature and spouted temperature.And then the conclusions which would provide theoretical guidance for the actual experiment were obtained.Finally,the large diameter plastic pipe spouted-accumulated forming experiment was carried out on the basis of the calculated parameters and numerical simulation results.And then,the mechanical properties of the pipes including ring stiffness,tensile properties and impact properties were tested.Then the influence of drawing speed,rotation speed,cooling temperature and spouted temperature on the mechanical properties of the pipes was analyzed combined with the DSC analysis results,and the conclusions of numerical simulation analysis were verified.In addition,the mechanical properties of the formed pipes and the extrusion pipes with the same size were compared.And the results show that the mechanical properties of the formed pipes were better than the extrusion pipes,especially the impact property.Among them,the axial impact strength is 1.6 times of the extrusion pipe,and the circumferential impact strength is about 2.2 times of the extrusion pipe.