The mechanism of pre roll ploughing for 3D fins on the outside surface of copper tube was studied systematically, and especially the process and conditions of 3D fin formation were analyzed. The right mathematical mod...The mechanism of pre roll ploughing for 3D fins on the outside surface of copper tube was studied systematically, and especially the process and conditions of 3D fin formation were analyzed. The right mathematical model was also established. Based on the volume of fin ploughed out is equal to the volume of the metal extruded up by the extruding face of the tool, the relations between fin height, pre roll ploughing feed and pre roll ploughing depth have been achieved. With the increase of pre roll ploughing depth which must be equal to groove depth, the fin height gradually becomes larger. There are different critical feeds with the various depths of pre roll ploughing. The pre roll ploughing feed is the critical one, the height of fin is largest. And when the feed is above the critical one, the fin height will reduce with the increase of feed. The theoretical analysis basically accords with experimental results.展开更多
Using rolling-ploughing-extrusion compound processing methods,a 3D integral-fin structure on outside surface of red copper tube with diameter of 16.0 mm and wall thickness of 1.5 mm was obtained. When both rolling dep...Using rolling-ploughing-extrusion compound processing methods,a 3D integral-fin structure on outside surface of red copper tube with diameter of 16.0 mm and wall thickness of 1.5 mm was obtained. When both rolling depth and ploughing-extrusion(P-E) depth were 0.2 mm,rotating speed was 50 r/min,feed speed was 0.16 mm/r,3D fin structures with height of 0.25 mm were gotten. Two different fin structures were obtained in grooves formed with rolling-ploughing-extrusion compound forming technology and observed by scanning electron microscope(SEM). One is the compound structure with V-shaped groove and U-shaped groove,and the other is the single structure with V-shaped grooves. Two kinds of groove structures obtained by rolling processing and ploughing extrusion processing are restricted together by groove interval and rolling depth,and pitch and P-E depth,respectively. Based on the analysis of interaction of rolling and P-E processing,it is found from the result that the outside 3D integral-fin can be achieved by rolling-ploughing-extrusion compound processing when single V-shaped groove structures are formed by both rolling and P-E processing.展开更多
Using ploughing-extrusion method, a cross-connected finned micro-grooves structure was formed on the surface of copper strips with thickness of 0.4 mm. The structure was fabricated by making ‘V’-grooves in copper st...Using ploughing-extrusion method, a cross-connected finned micro-grooves structure was formed on the surface of copper strips with thickness of 0.4 mm. The structure was fabricated by making ‘V’-grooves in copper strips and perpendicular ‘V’-grooves on the opposite side that intersect the first set of grooves. Micro pores appear at the intersection of these cross-connected grooves, and micro fins appear on the groove fringes. So it can be defined as ‘pore-groove-fin’ structure. The preferable ‘pore-groove-fin’ structure can be obtained under the condition that the tool edge inclination angle (χγ) is 45°, both the major extrusion angle (γo) and the minor extrusion angle (γ 0′ ) are 30°, both the major formation angle (β) and the minor formation angle (β′) are 10°, the ploughing-extrusion depth (fd) is 0.32 mm and the groove pitch is 0.4 mm on surfaces A and B. The formed included angle of groove A is 70°, and the groove depth is 0.3 mm, while the included angle of opposite perpendicular groove B is 20° with the groove depth of 0.35 mm. The obtained fin height is 0.15 mm, the elliptical pore length is 0.2 mm and the width is 0.05 mm. Experiments show that fd has the greatest influence on the formation of micro pores. Bulges appear on the opposite surface B when the ploughing-extrusion depth on surface A (fdA) reaches a critical value. The ploughing-extrusion depth on surface B (fdB) has great influence on the re-growth of fin structure.展开更多
文摘The mechanism of pre roll ploughing for 3D fins on the outside surface of copper tube was studied systematically, and especially the process and conditions of 3D fin formation were analyzed. The right mathematical model was also established. Based on the volume of fin ploughed out is equal to the volume of the metal extruded up by the extruding face of the tool, the relations between fin height, pre roll ploughing feed and pre roll ploughing depth have been achieved. With the increase of pre roll ploughing depth which must be equal to groove depth, the fin height gradually becomes larger. There are different critical feeds with the various depths of pre roll ploughing. The pre roll ploughing feed is the critical one, the height of fin is largest. And when the feed is above the critical one, the fin height will reduce with the increase of feed. The theoretical analysis basically accords with experimental results.
基金Projects(50436010, 50675070) supported by the National Natural Science Foundation of ChinaProject(07118064) supported by the Natural Science Foundation of Guangdong Province, China
文摘Using rolling-ploughing-extrusion compound processing methods,a 3D integral-fin structure on outside surface of red copper tube with diameter of 16.0 mm and wall thickness of 1.5 mm was obtained. When both rolling depth and ploughing-extrusion(P-E) depth were 0.2 mm,rotating speed was 50 r/min,feed speed was 0.16 mm/r,3D fin structures with height of 0.25 mm were gotten. Two different fin structures were obtained in grooves formed with rolling-ploughing-extrusion compound forming technology and observed by scanning electron microscope(SEM). One is the compound structure with V-shaped groove and U-shaped groove,and the other is the single structure with V-shaped grooves. Two kinds of groove structures obtained by rolling processing and ploughing extrusion processing are restricted together by groove interval and rolling depth,and pitch and P-E depth,respectively. Based on the analysis of interaction of rolling and P-E processing,it is found from the result that the outside 3D integral-fin can be achieved by rolling-ploughing-extrusion compound processing when single V-shaped groove structures are formed by both rolling and P-E processing.
基金Projects(50436010, 50605023, 50675070) supported by the National Natural Science Foundation of ChinaProject(04105942) supported by the Natural Science Foundation of Guangdong Province, China
文摘Using ploughing-extrusion method, a cross-connected finned micro-grooves structure was formed on the surface of copper strips with thickness of 0.4 mm. The structure was fabricated by making ‘V’-grooves in copper strips and perpendicular ‘V’-grooves on the opposite side that intersect the first set of grooves. Micro pores appear at the intersection of these cross-connected grooves, and micro fins appear on the groove fringes. So it can be defined as ‘pore-groove-fin’ structure. The preferable ‘pore-groove-fin’ structure can be obtained under the condition that the tool edge inclination angle (χγ) is 45°, both the major extrusion angle (γo) and the minor extrusion angle (γ 0′ ) are 30°, both the major formation angle (β) and the minor formation angle (β′) are 10°, the ploughing-extrusion depth (fd) is 0.32 mm and the groove pitch is 0.4 mm on surfaces A and B. The formed included angle of groove A is 70°, and the groove depth is 0.3 mm, while the included angle of opposite perpendicular groove B is 20° with the groove depth of 0.35 mm. The obtained fin height is 0.15 mm, the elliptical pore length is 0.2 mm and the width is 0.05 mm. Experiments show that fd has the greatest influence on the formation of micro pores. Bulges appear on the opposite surface B when the ploughing-extrusion depth on surface A (fdA) reaches a critical value. The ploughing-extrusion depth on surface B (fdB) has great influence on the re-growth of fin structure.
