Flat metal strips are deformed progressively into profiles with certain geometry sections by a series of successive rotating rolls at the room temperature, and it is called the cold roll-forming. An effective method i...Flat metal strips are deformed progressively into profiles with certain geometry sections by a series of successive rotating rolls at the room temperature, and it is called the cold roll-forming. An effective method is given for roll design to avoid major defects via finite element method （FEM） simulation using a booting model. The simulation gives reasonable fit to the actual product in the two major roll-forming defects, i.e. , edge wave and springback. The redesigned rolls using the approach of multi-stand FEM simulation can effectively control these two defects.展开更多
To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented progra...To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented programming. Combined with the computer graphicstechnology, the visual simulation of cold roll-forming is completed and the system is established.By analyzing common channel steel, the process is shown and explained including theory method, modeland result display. So the simulation system is already a kind of mature and effective tool toanalyze the process of cold roll forming.展开更多
A multi- pumose simulation method for the roll- formign is proposed. The forming pro- cesses of welded pipes are systematically simulated by using the method. The three-dimensional cu rved surfaces of sheet...A multi- pumose simulation method for the roll- formign is proposed. The forming pro- cesses of welded pipes are systematically simulated by using the method. The three-dimensional cu rved surfaces of sheet metals in forming processes are mathema tically expressed by using the shape fonction S(X) which represents flow pattern of each part of sheet metal. Through optimis- ing t e parameter n in s(X), the best approximation of the deformation of sheet metal is derived and the minimum power of deformation is obtained. A mathematical procedure of this analysis is systematically foimulated. The simulation method can be applied to the analysis and simulation for various roll- forming processes of welded pipes observed in commercial production line.展开更多
To improve the strength-toughness of traditional U-rib（ TUR） and solve the problem of insufficient penetration between TUR and deckplate,a new local thickened U-rib（ LTUR） has been proposed to improve the fatigue ...To improve the strength-toughness of traditional U-rib（ TUR） and solve the problem of insufficient penetration between TUR and deckplate,a new local thickened U-rib（ LTUR） has been proposed to improve the fatigue resistance of the weld joint under the premise of not increasing thickness and strength of the TUR material. And a hot /warm roll-forming process（ RFP） adopting partially induction heating to 700- 1 000℃ was carried out to fabricate LTUR. The deformation behaviors in the forming process and microstructure of LTUR have been investigated.Mechanical properties and fracture mechanism of the LTUR after hot / warm RFP have been systematically discussed. Moreover,the results are compared with those obtained in cold RFP. Mechanical properties of the LTUR deformed above the critical transformation temperature（ A_（c3）） show high performance characteristics with marked fatigue resistance and superior toughness. Upon increasing the heating temperature from 700 to 900 ℃,the initial coarse ferrite-pearlite structure transform into equiaxed ultrafine ferrite（ 1- 3 μm） and precipitates such as（ Nb,Ti）（ C,N） are uniformly distributed in the matrix. The average dislocation density of the specimens after hot rollforming at heating temperature of 900 ℃ decreases dramatically compared with those of the specimens subjected to the cold RFP. Furthermore,a typical characteristic of ductile fracture mechanism and the high impact energy are more convinced that the specimens deformed above 900 ℃ have obtained an optimal combination of strength and toughness.展开更多
文摘Flat metal strips are deformed progressively into profiles with certain geometry sections by a series of successive rotating rolls at the room temperature, and it is called the cold roll-forming. An effective method is given for roll design to avoid major defects via finite element method （FEM） simulation using a booting model. The simulation gives reasonable fit to the actual product in the two major roll-forming defects, i.e. , edge wave and springback. The redesigned rolls using the approach of multi-stand FEM simulation can effectively control these two defects.
基金This project is supported by Provincial Natural Science Foundation of Hebei (No.502214).
文摘To simulate the process of cold roll-forming process, a new method isadopted. The theoretical foundation of this method is an elastic-plastic large deformation splinefinite strip method based on object-oriented programming. Combined with the computer graphicstechnology, the visual simulation of cold roll-forming is completed and the system is established.By analyzing common channel steel, the process is shown and explained including theory method, modeland result display. So the simulation system is already a kind of mature and effective tool toanalyze the process of cold roll forming.
文摘A multi- pumose simulation method for the roll- formign is proposed. The forming pro- cesses of welded pipes are systematically simulated by using the method. The three-dimensional cu rved surfaces of sheet metals in forming processes are mathema tically expressed by using the shape fonction S(X) which represents flow pattern of each part of sheet metal. Through optimis- ing t e parameter n in s(X), the best approximation of the deformation of sheet metal is derived and the minimum power of deformation is obtained. A mathematical procedure of this analysis is systematically foimulated. The simulation method can be applied to the analysis and simulation for various roll- forming processes of welded pipes observed in commercial production line.
文摘To improve the strength-toughness of traditional U-rib（ TUR） and solve the problem of insufficient penetration between TUR and deckplate,a new local thickened U-rib（ LTUR） has been proposed to improve the fatigue resistance of the weld joint under the premise of not increasing thickness and strength of the TUR material. And a hot /warm roll-forming process（ RFP） adopting partially induction heating to 700- 1 000℃ was carried out to fabricate LTUR. The deformation behaviors in the forming process and microstructure of LTUR have been investigated.Mechanical properties and fracture mechanism of the LTUR after hot / warm RFP have been systematically discussed. Moreover,the results are compared with those obtained in cold RFP. Mechanical properties of the LTUR deformed above the critical transformation temperature（ A_（c3）） show high performance characteristics with marked fatigue resistance and superior toughness. Upon increasing the heating temperature from 700 to 900 ℃,the initial coarse ferrite-pearlite structure transform into equiaxed ultrafine ferrite（ 1- 3 μm） and precipitates such as（ Nb,Ti）（ C,N） are uniformly distributed in the matrix. The average dislocation density of the specimens after hot rollforming at heating temperature of 900 ℃ decreases dramatically compared with those of the specimens subjected to the cold RFP. Furthermore,a typical characteristic of ductile fracture mechanism and the high impact energy are more convinced that the specimens deformed above 900 ℃ have obtained an optimal combination of strength and toughness.
