Porthole dies are important tools in extrusion process to produce hollow sections and the life of the dies counts for the cost of products. In this work, the finite element method was adopted to analyze a particular p...Porthole dies are important tools in extrusion process to produce hollow sections and the life of the dies counts for the cost of products. In this work, the finite element method was adopted to analyze a particular porthole die to produce hollow rectangle sections which are widely used in construction. The upper die was mainly studied. Because it is symmetrical, a quarter of the die was analyzed. The upper die was divided into 2199 elements with 3018 nodes. Elements were produced by four steps and the geometric shape of the die could be well simulated. The boundary condition was given according to the shape of the welding chamber and an empirical average extrusion stress was adopted, which was 210N/mm 2. Three-dimensional equivalent stresses were received. The original porthole die studied had obvious stress concentration and the stress distribution was very inhomogeneous, which would heavily affect the die life. A new design was proposed in which the portholes were rearranged and their shape and dimension were changed. According to the finite element analysis, the stress distribution of the improved die was quite homogeneous and the stress concentration was lessened.展开更多
This research deals with the forward extrusion process of tubes. In this process, a piercing process was carried out on the billet to produce the tube, followed directly by a reduction in the wall thickness. A specifi...This research deals with the forward extrusion process of tubes. In this process, a piercing process was carried out on the billet to produce the tube, followed directly by a reduction in the wall thickness. A specific geometrical shape for the piercing zone and the wall thickness reduction zone were chosen and designed. The effects of the redundant shear strain and the magnitude of the extrusion load were investigated and simulated with the finite element method using Q Form software program. Lead was used as model materials since (if the experiments were carried out at room temperature) it has the similar behavior of the steel at high temperature. The results obtained have shown that at the piercing zone, the lowest values of the extrusion load, the redundant strain, the total strain and the finite element effective strain were when a piercing tool (mandrel) of (C = 1.1) was used. While, at the die zone, the lowest values of the extrusion load, the redundant strain, the total strain was when a die of (C = 0.9) was used.展开更多
In the extrusion of shapes with flat faced die,the proper design of die land is of critical importance in avoiding the generations of geometry defects.A methodology for the design of die land,which consists of a simu...In the extrusion of shapes with flat faced die,the proper design of die land is of critical importance in avoiding the generations of geometry defects.A methodology for the design of die land,which consists of a simulation adjustment iteration,is proposed.The metal flow in extrusion is simulated by the three dimensional finite element method and the die land is adjusted according to the simulation result.Both the formulae for adjustment of the die land and the criterion for the judgment of proper die land are suggested.The extrusion of an L section shape is chosen as the computational example and the result is compared with the industrial design.展开更多
Equal cross section lateral extrusion (ECSLE) is an effective method realizing pure shear deformation. The influence of friction factor on the deformation uniformity of ECSLE was investigated with rigid plastic finite...Equal cross section lateral extrusion (ECSLE) is an effective method realizing pure shear deformation. The influence of friction factor on the deformation uniformity of ECSLE was investigated with rigid plastic finite element method. The result shows that the non-uniform deformation in extrusion is caused mainly by the friction between workpiece and die. The higher the friction factor is, the more uneven plastic deformation resulted in extruded workpiece. The relation curve of deformation uniformity vs. friction factor was drawn based on the analysis result. The curve can be used as a basis of ECSLE process design.展开更多
文摘Porthole dies are important tools in extrusion process to produce hollow sections and the life of the dies counts for the cost of products. In this work, the finite element method was adopted to analyze a particular porthole die to produce hollow rectangle sections which are widely used in construction. The upper die was mainly studied. Because it is symmetrical, a quarter of the die was analyzed. The upper die was divided into 2199 elements with 3018 nodes. Elements were produced by four steps and the geometric shape of the die could be well simulated. The boundary condition was given according to the shape of the welding chamber and an empirical average extrusion stress was adopted, which was 210N/mm 2. Three-dimensional equivalent stresses were received. The original porthole die studied had obvious stress concentration and the stress distribution was very inhomogeneous, which would heavily affect the die life. A new design was proposed in which the portholes were rearranged and their shape and dimension were changed. According to the finite element analysis, the stress distribution of the improved die was quite homogeneous and the stress concentration was lessened.
文摘This research deals with the forward extrusion process of tubes. In this process, a piercing process was carried out on the billet to produce the tube, followed directly by a reduction in the wall thickness. A specific geometrical shape for the piercing zone and the wall thickness reduction zone were chosen and designed. The effects of the redundant shear strain and the magnitude of the extrusion load were investigated and simulated with the finite element method using Q Form software program. Lead was used as model materials since (if the experiments were carried out at room temperature) it has the similar behavior of the steel at high temperature. The results obtained have shown that at the piercing zone, the lowest values of the extrusion load, the redundant strain, the total strain and the finite element effective strain were when a piercing tool (mandrel) of (C = 1.1) was used. While, at the die zone, the lowest values of the extrusion load, the redundant strain, the total strain was when a die of (C = 0.9) was used.
文摘In the extrusion of shapes with flat faced die,the proper design of die land is of critical importance in avoiding the generations of geometry defects.A methodology for the design of die land,which consists of a simulation adjustment iteration,is proposed.The metal flow in extrusion is simulated by the three dimensional finite element method and the die land is adjusted according to the simulation result.Both the formulae for adjustment of the die land and the criterion for the judgment of proper die land are suggested.The extrusion of an L section shape is chosen as the computational example and the result is compared with the industrial design.
文摘Equal cross section lateral extrusion (ECSLE) is an effective method realizing pure shear deformation. The influence of friction factor on the deformation uniformity of ECSLE was investigated with rigid plastic finite element method. The result shows that the non-uniform deformation in extrusion is caused mainly by the friction between workpiece and die. The higher the friction factor is, the more uneven plastic deformation resulted in extruded workpiece. The relation curve of deformation uniformity vs. friction factor was drawn based on the analysis result. The curve can be used as a basis of ECSLE process design.
