| Compared with metal pipe,PE pipe has the advantages of hygienic environmental protection,light mass,hardly breakup,no rust,small wall resistance,good toughness,etc.After decades of development,the production process and equipment of plastic pipes have become quite mature.The key to the quality of PE pipe systems is the connection between pipes.There are many ways to connect plastic pipes,of which pipe thermal welding is commonly used.In this paper,Polyflow finite element software was applied in this paper to numerically analyze the process of flaring thermoforming and butt-fusion welding of PE pipe.The effect of processing temperature and working temperature of PE pipe on its performance was experimentally studied,and the experiment can provide theoretical support and process guidance for the practical production.The finite element method is adopted for studying the effects of heating temperature,forming time and slip coefficient on the flaring thermoforming of the PE pure pipe,it was found that when the heating temperature and forming time were changed within a reasonable state,they have little effect on the flaring thermoforming results of the PE pure pipe,but the choice of heating location is critical to improving the quality of thermoformed products.The slip coefficient has a great influence on the flaring thermoforming of PE pure pipe.The slip coefficient is too small to cause voids in the thermoforming products.If the slip coefficient is too large,the void can be filled,but it will reduce the appearance quality of the end of the deformation area.The finite element method is adopted for studying the effect of slip coefficient on the flaring thermoforming results of CGF-RTP composite pipe.The results show that the effect of slip coefficient on the flaring thermoforming of CGF-RTP composite pipe is similar to that of the flaring thermoforming of PE pure pipe,however CGF-RTP composite pipe is more sensitive to the slip coefficient than PE pure pipe,and under the same slip coefficient,the void of CGF-RTP composite pipe is larger and the quality of the appearance quality at the end is worse.The finite element method is adopted for studying the effect of heating temperature on butt-fusion welding between thermoformed PE pure pipes,and the quality of welded joint was characterized by the shape of the welded joints and the pressure between the welding surfaces.Under the setted heating temperature,a good shape of the welded joint can be obtained,and the pressure between the welding surfaces can reach the megapascals level;in the welding process,the maximum flow velocity of the melt at the PE pure pipe end occurs in the melt filling the void for the first time;and with the progress of welding,the maximum value of the velocity increases continuously;since the welding interface speed is lower than the speed away from the interface area,excessive melt flow away from the welding interface,and the welding interface creates voids.The experimental method is adopted for studying the PE pure pipe and the CGF-RTP composite pipe,according to the processing temperature of the base pipe in the processing of the CGF-RTP composite pipe,the working temperature of the PE pure pipe and the CGF-RTP composite pipe.When the whole wall surface of PE pipe is heated,the strain value in the height direction of the CGF-RTP composite pipe and the PE pure pipe increase with increasing temperature,and the strain increments of the PE pure pipe is more prominent.When the inner or outer wall of the pipe is heated,with the increase of temperature,the PE pure pipe has a large strain increments in the height and thickness direction,and the radial strain also shows an increasing trend,and the internal diameter strain increments is similar to the external diameter strain increments;CGF-RTP composite pipe has a small strain increments in height and thickness direction,the radial strain value shows an increasing trend,and the internal diameter strain value is greater than the external diameter strain value. |
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