In this paper, turning experiments of machining particle reinforced metal matri x composites(PRMMCs) SiC p/Al with PCD tools have been carried out. The cutting force characteristics in ultrasonic vibration turning com...In this paper, turning experiments of machining particle reinforced metal matri x composites(PRMMCs) SiC p/Al with PCD tools have been carried out. The cutting force characteristics in ultrasonic vibration turning compared with that in com mon turning were studied. Through the single factor experiments and multiple fac tor orthogonal experiments, the influences of three kinds of cutting conditions such as cutting velocity, amount of feed and cutting depth on cutting force were analyzed in detail. Meanwhile, according to the experimental data, the empirica l formula of main cutting force in ultrasonic vibration turning was conclude d. According to the test results, the cutting force is direct proportion to cutt ing depth basically according to the relation between cutting force and other fa ctors, which is similar to that of common cutting, so is the feed rate, but the influence is not so big. The influence of cutting speed is larger than that of f eed rate on cutting force because the efficient cutting time increases in vibrat ion cycle with the increase of cutting speed, which causes cutting force to incr ease. The research results indicate: (1) Ultrasonic vibration turning possesses much lower main cutting force than that in common turning when adopting smaller cutting parameters. If using larger cutting parameters, the difference will inco nspicuous. (2) There are remarkable differences of cutting force-cutting veloci ty characteristics in ultrasonic vibration turning from that in common turning m ainly because built-up edge does not emerge in ultrasonic turning unlike common turning in corresponding velocity range. (3) In ultrasonic vibration cutting, t he influence of cutting velocity on cutting force is most obvious among thre e cutting parameters and the influence of feed is smallest. So adopting lower cu tting velocity and larger cutting depth not only can reduce cutting force effect ively but also can ensure cutting efficiency. (4) The conclusions are useful in precision and super precision manufacturing thin-wall pieces.展开更多
The cutting performance of particulate reinforced me tallic matrix composites(PRMMCs) SiC p/Al in ultrasonic vibration cutting and c ommon cutting with carbide tools and PCD tools was researched in the paper. Mic rost...The cutting performance of particulate reinforced me tallic matrix composites(PRMMCs) SiC p/Al in ultrasonic vibration cutting and c ommon cutting with carbide tools and PCD tools was researched in the paper. Mic rostructure of machined surface was described, the relation between cutting para meters and surface roughness was presented, and characteristic of the surface re mained stress was also presented. Furthermore, wear regularity and abrasion resi stance ability of tools in ultrasonic vibration cutting and common cutting o f PRMMCs were discussed in detail. The test results show: (1) The surface config urations are obviously different when using different tools to machine such PRMM Cs. The surface machined with carbide tools looks luminous and orderly and there are seldom surface defects on it. The reason is that the soft basal body is apt to flow during cutting, therefore a layer of Al matrix film covers machined sur face. On the contrary, the surface machined with PCD tools looks lackluster. But the profile of machined surface is very clear. Superfine grooves, pits and blac k reinforce particulates can be seen easily without obvious Al film. (2) Because of unstable cutting process in common cutting, the surface is easy to produce s ome defects such as burrs, built-up edges and so on so that the quality of surf ace becomes very poor. Vibration cutting can reduce the influence of tearing, pl astic deformation and built-up edge in cutting and can restrain flutter so as t o make cutting process more stable. Therefore, surface roughness of vibration cu tting is better than that of common cutting. (3) There is an optimum value of fe ed rate in vibration cutting of PRMMCs due to the influence of material characte ristics. Whether feed rate is more than or less than this optimum value, surface roughness will increase. (4) According to analyzing the wear rate of tools in v ibration cutting PRMMCs, it can be concluded that abrasion resistance of tools w ill be improved remarkably when vibration cutting composites have a lower pe rcentage of reinforce particulate. If the percentage of reinforce particulate is higher, the influence on abrasion resistance of carbide tool in vibration cut ting will not be obvious. The research result indicates that vibration cutting effect has a close relation with material characteristics.展开更多
Aluminum based metal matrix composites are offering o utstanding properties in a number of automotive and aircraft components and body structures. The major advantages of these composite materials are their high st re...Aluminum based metal matrix composites are offering o utstanding properties in a number of automotive and aircraft components and body structures. The major advantages of these composite materials are their high st rength to weight ratio, high stiffness, high hardness, wear resistance, low coef ficient of thermal expansion, superior dimensional stability and versatility to designer. In addition to these their isotropic properties, good forming characte ristics, easy availability of cheaper reinforcements along with the availability of comparatively low cost, high volume production methods have made them a prom ising material for future growth. Weight reduction is a major goal of automotive innovations. Lighter vehicles/ ai rcraft means less fuel consumption, reduced emissions, and improved performance. Components made from highly loaded aluminium matrix composites are attractive r elative to iron based materials because of their low density, high stiffness (eq uivalent to nodular iron) and better heat transfer characteristics. The basic co st of materials is higher with these advanced composites; however, manufacturing the part to near net shape may offset basic material costs. A good aluminium based material design can improves safety. The aluminium-based composites can give cars better acceleration and braking, improved handling, ex cellent durability, and ease of repair. Tha aluminum-based composite performs a s well or better in crash than conventional steel-structured cars because of th eir larger volume, which can absorb more crash energy. Another excellent advanta ge of Al-SiC p composite in auto design is better stability and response, and reduced noise, vibration/harshness (NHV). These advantages stem from reduced veh icle weight combined with high structural stiffness and also lead to improved st ability and turning response. In the present work Al-SiC p composite plates of 10 to 12 mm thickness w ere cast using sand casting as well as die casting process. The plates were furt her machined to 3 to 4 mm thicknesses. The machined plates were subjected to col d as well hot rolling. The cold rolling of Al-3 wt.% SiC composite plates was done on 2 high experimental cold rolling mill at Indian Oil Corporation Ltd., R esearch and Development centre, Faridabad. For hot rolling, the Al-5 weight % SiC p composite plates were heat treated at 500 ℃ temperature and Al-15 weight % SiC p composite plates were heat treate d at 550 ℃ temperature for 20 minutes. The plates were hot rolled on 2 high ro lling mill of one ton capacity at IIT Delhi. The maximum percentage reduction ob tained after hot rolling of Al-5 weight % SiC p composite and Al- 15 weight % SiC p composite plates for 10 passes was 11 % and 6 % respectively. During col d rolling of Al-SiC p composites cracks (particle fracture) were observed due to the low ductility of Al-SiC p composties at room temperature. The various m echanical properties such as tensile strength, hardness and wear resistance were measured for the rolled and un-rolled Al-SiC p composite plates. The tensile strength of un-rolled and rolled Al-5wt.% SiC p composites are shown in Tab. 1. Table shows that the tensile strength decreases after rolling. This may be du e to the damage of the bonding between aluminum and silicon carbide particulates . The Rockwell hardness values of Al-5 wt.% SiC p composites measured before a nd after hot rolling are shown in Tab.2. The hardness was found to decrease afte r hot rolling, which may be due to the annealing of composites during heating. T he Rockwell hardness values of Al-3 wt.% SiC p composites before and after cold rolling are shown in Tab.3. The Table shows that the Rockwell hardness of Al-SiC p compostes increases after cold rolling due to the workhardening effec t. The wear resistance of rolled and un-rolled Al-SiC p composites were teste d on reciprocating ball on flat wear testing machine. The wear resistance of Al -SiC p composites decreases after hot rolling due to decrease in hardness展开更多
文摘In this paper, turning experiments of machining particle reinforced metal matri x composites(PRMMCs) SiC p/Al with PCD tools have been carried out. The cutting force characteristics in ultrasonic vibration turning compared with that in com mon turning were studied. Through the single factor experiments and multiple fac tor orthogonal experiments, the influences of three kinds of cutting conditions such as cutting velocity, amount of feed and cutting depth on cutting force were analyzed in detail. Meanwhile, according to the experimental data, the empirica l formula of main cutting force in ultrasonic vibration turning was conclude d. According to the test results, the cutting force is direct proportion to cutt ing depth basically according to the relation between cutting force and other fa ctors, which is similar to that of common cutting, so is the feed rate, but the influence is not so big. The influence of cutting speed is larger than that of f eed rate on cutting force because the efficient cutting time increases in vibrat ion cycle with the increase of cutting speed, which causes cutting force to incr ease. The research results indicate: (1) Ultrasonic vibration turning possesses much lower main cutting force than that in common turning when adopting smaller cutting parameters. If using larger cutting parameters, the difference will inco nspicuous. (2) There are remarkable differences of cutting force-cutting veloci ty characteristics in ultrasonic vibration turning from that in common turning m ainly because built-up edge does not emerge in ultrasonic turning unlike common turning in corresponding velocity range. (3) In ultrasonic vibration cutting, t he influence of cutting velocity on cutting force is most obvious among thre e cutting parameters and the influence of feed is smallest. So adopting lower cu tting velocity and larger cutting depth not only can reduce cutting force effect ively but also can ensure cutting efficiency. (4) The conclusions are useful in precision and super precision manufacturing thin-wall pieces.
文摘The cutting performance of particulate reinforced me tallic matrix composites(PRMMCs) SiC p/Al in ultrasonic vibration cutting and c ommon cutting with carbide tools and PCD tools was researched in the paper. Mic rostructure of machined surface was described, the relation between cutting para meters and surface roughness was presented, and characteristic of the surface re mained stress was also presented. Furthermore, wear regularity and abrasion resi stance ability of tools in ultrasonic vibration cutting and common cutting o f PRMMCs were discussed in detail. The test results show: (1) The surface config urations are obviously different when using different tools to machine such PRMM Cs. The surface machined with carbide tools looks luminous and orderly and there are seldom surface defects on it. The reason is that the soft basal body is apt to flow during cutting, therefore a layer of Al matrix film covers machined sur face. On the contrary, the surface machined with PCD tools looks lackluster. But the profile of machined surface is very clear. Superfine grooves, pits and blac k reinforce particulates can be seen easily without obvious Al film. (2) Because of unstable cutting process in common cutting, the surface is easy to produce s ome defects such as burrs, built-up edges and so on so that the quality of surf ace becomes very poor. Vibration cutting can reduce the influence of tearing, pl astic deformation and built-up edge in cutting and can restrain flutter so as t o make cutting process more stable. Therefore, surface roughness of vibration cu tting is better than that of common cutting. (3) There is an optimum value of fe ed rate in vibration cutting of PRMMCs due to the influence of material characte ristics. Whether feed rate is more than or less than this optimum value, surface roughness will increase. (4) According to analyzing the wear rate of tools in v ibration cutting PRMMCs, it can be concluded that abrasion resistance of tools w ill be improved remarkably when vibration cutting composites have a lower pe rcentage of reinforce particulate. If the percentage of reinforce particulate is higher, the influence on abrasion resistance of carbide tool in vibration cut ting will not be obvious. The research result indicates that vibration cutting effect has a close relation with material characteristics.
文摘Aluminum based metal matrix composites are offering o utstanding properties in a number of automotive and aircraft components and body structures. The major advantages of these composite materials are their high st rength to weight ratio, high stiffness, high hardness, wear resistance, low coef ficient of thermal expansion, superior dimensional stability and versatility to designer. In addition to these their isotropic properties, good forming characte ristics, easy availability of cheaper reinforcements along with the availability of comparatively low cost, high volume production methods have made them a prom ising material for future growth. Weight reduction is a major goal of automotive innovations. Lighter vehicles/ ai rcraft means less fuel consumption, reduced emissions, and improved performance. Components made from highly loaded aluminium matrix composites are attractive r elative to iron based materials because of their low density, high stiffness (eq uivalent to nodular iron) and better heat transfer characteristics. The basic co st of materials is higher with these advanced composites; however, manufacturing the part to near net shape may offset basic material costs. A good aluminium based material design can improves safety. The aluminium-based composites can give cars better acceleration and braking, improved handling, ex cellent durability, and ease of repair. Tha aluminum-based composite performs a s well or better in crash than conventional steel-structured cars because of th eir larger volume, which can absorb more crash energy. Another excellent advanta ge of Al-SiC p composite in auto design is better stability and response, and reduced noise, vibration/harshness (NHV). These advantages stem from reduced veh icle weight combined with high structural stiffness and also lead to improved st ability and turning response. In the present work Al-SiC p composite plates of 10 to 12 mm thickness w ere cast using sand casting as well as die casting process. The plates were furt her machined to 3 to 4 mm thicknesses. The machined plates were subjected to col d as well hot rolling. The cold rolling of Al-3 wt.% SiC composite plates was done on 2 high experimental cold rolling mill at Indian Oil Corporation Ltd., R esearch and Development centre, Faridabad. For hot rolling, the Al-5 weight % SiC p composite plates were heat treated at 500 ℃ temperature and Al-15 weight % SiC p composite plates were heat treate d at 550 ℃ temperature for 20 minutes. The plates were hot rolled on 2 high ro lling mill of one ton capacity at IIT Delhi. The maximum percentage reduction ob tained after hot rolling of Al-5 weight % SiC p composite and Al- 15 weight % SiC p composite plates for 10 passes was 11 % and 6 % respectively. During col d rolling of Al-SiC p composites cracks (particle fracture) were observed due to the low ductility of Al-SiC p composties at room temperature. The various m echanical properties such as tensile strength, hardness and wear resistance were measured for the rolled and un-rolled Al-SiC p composite plates. The tensile strength of un-rolled and rolled Al-5wt.% SiC p composites are shown in Tab. 1. Table shows that the tensile strength decreases after rolling. This may be du e to the damage of the bonding between aluminum and silicon carbide particulates . The Rockwell hardness values of Al-5 wt.% SiC p composites measured before a nd after hot rolling are shown in Tab.2. The hardness was found to decrease afte r hot rolling, which may be due to the annealing of composites during heating. T he Rockwell hardness values of Al-3 wt.% SiC p composites before and after cold rolling are shown in Tab.3. The Table shows that the Rockwell hardness of Al-SiC p compostes increases after cold rolling due to the workhardening effec t. The wear resistance of rolled and un-rolled Al-SiC p composites were teste d on reciprocating ball on flat wear testing machine. The wear resistance of Al -SiC p composites decreases after hot rolling due to decrease in hardness
