Study On Extrusion Technology With Multi-direction Loading Of T-shaped Tube

The part what we study in this paper is a T-shaped used in high pressure pipe. Thematerials is304stainless-steel. The shape is complexity with high intensity and Accuracy.But the current production craft is to use casting and welding processing method. TheProduction efficiency is so low, material utilization and strength is also low，it can hardlymeet the demand of the increasing market demand. This paper，we studied the plastic formingof304stainless-steel part, adopt closed extrusion technology. The work-piece we productedhave good organization performance, high strength and size precision, good plastic, strongcorrosion resistance. This process have high production efficiency, material utilization alsohigher, It is a kind of advanced manufacturing technology.According to the characteristics of the part, formulated preliminary multi-directionloading method which with vertical load is firstly set to, horizontal load is secondly set to.This method including asynchronous loading method, sequence loading method, synchronousloading. We set up a model of the process scheme and applied finite element software toFEM numerical simulation. We modified the original extrusion process parameters andmethods. We have optimized the size of the mold structure. Analyzed the flow regularity anddie loading situation during the closed extrusion process, simulated the male mould andconcave mold on the equivalent strain and equivalent stress distribution. We obtained betterdeformation parameters through the simulation,also predicted the folding defects which mayoccur during the deformation.On the basis of the above, we designed the die and then conducted the experiment ofclosed extrusion technology with multi-direction loading. Experiments show that experimental and simulation results are basically identical. The results show that the structureof die we designed, the equipment we selected,the forming process and the processparameter were reasonable. But there are mainly two problems.1) Chamber of die mold was not be filled with metal enough, mainly because of thebillet heat loss seriously, then the temperature drops quickly, the plasticity and fluidity ofmetal was reduced seriously in the extrusion forming process.2) The thickness’s error of work-piece was great. Mainly because of the distribution ofmetal was uneven in vertical. Also we ignore the difference of rigidity between the numericalsimulation and the actual experiment. The rigidity of die is assumed absolute inflexibility,and it is impossible in the actual situation that lead to great error of thickness. We can clearlysee the difference produce great influence on the experiment, that provides a reference basisfor numerical simulation and experiment in the future.In view of the problem of above, we raise a new forming method which we firstly beginthe horizontal loading, then the vertical loading, specific loading process as follows: Thehorizontal punch begins to squeeze mental along the horizontal direction firstly, then thevertical punch begins to squeeze mental When the horizontal punch moves42mm along thehorizontal direction. As the horizontal punch drift4mm along the horizontal direction, stopsand the vertical punch go on with squeezing until it stops.We set up a model of the process scheme and applied finite element software to FEMnumerical simulation. Through the analysis of the flow regularity and die loading situationduring the closed extrusion process, We’ve come to the conclusion that the new formingmethod we raised was more reasonable, basically had the following advantages:1) The vertical punch join the loading process before the horizontal punch stopped thatmake the metal in a three-way compressive stress state. In the last, we avoid the fold defectswere caused by stress concentration.2) The distribution of metal was more equal that solved the problem of thickness’s error.3) The punch force was small, and extend the working life of the die.