The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that wh...The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that when the tool has a fine and uniform microstructure,the main failure mode is wear failure.Furthermore,observed phenomena including large chip bonding,coating peeling,cracks demonstrate that the main wear mechanisms of the tool are adhesive wear,abrasive wear,coating flaking,and microchipping.展开更多
The effect of cutting teeth number on the cutting force,surface roughness,tool wear rate and the cutting chip shape charac teristics is systematically evaluated.A novel five tee th chaser insert(C tool)which could tur...The effect of cutting teeth number on the cutting force,surface roughness,tool wear rate and the cutting chip shape charac teristics is systematically evaluated.A novel five tee th chaser insert(C tool)which could turn the workpiece at five cutting points simultaneously is involved in comparison with the standard triangle shaped insert(T tool),in the purpose of solving the problems of cutting heat concentration and rapid tool failures in the Inconel 718 machining process.Comparative orthogonal cut ting experimen ts of the C tool and T tool show that the cut ting depth is the significant influencing factor of the cutting forces.Meanwhile,the five cut ting teeth of the C tool show the effec tiveness of dispersing the cut ting forces as well as improving the cut ting efficiency.The feed rate is the significant factor to affect the root-mean-square surface roughness(Ra)of workpiece machined by the T tool,while the significant influencing variable of Ra for the C tool is the cutting depth due to its unique tool geome try(0°rake angle)in the axial feeding process.Moreover,due to the dispersing effect,the cut ting edges on the C tool exhibits lower tool wear rate than that of the T tool under the same axial feed.The chips are regular continuous long chips for the T tool,while the irregular continuous chips with the characteristic of saw-toothed profile are obtained due to its unique 0°rake angle.The C tool shows the valid potential for effectively dispersing the cut ting heat and slowing down the tool wear rate in the Inconel 718 machining process.展开更多
Mooring systems play an important role for semi-submersible rigs that drill in deepwater.A detailed analysis was carried out on the mooring of a semi-submersible rig that conducted a trial well drilling at a deepwater...Mooring systems play an important role for semi-submersible rigs that drill in deepwater.A detailed analysis was carried out on the mooring of a semi-submersible rig that conducted a trial well drilling at a deepwater location in the South China Sea in 2009.The rig was 30 years old and had a shallow platform with a designed maximum operating water depth of 457 m.Following the mooring analysis,a mooring design was given that requires upgrading of the rig’s original mooring system.The upgrade included several innovations,such as installing eight larger anchors,i.e.replacing the original anchors and inserting an additional 600 m of steel wires with the existing chains.All this was done to enhance the mooring capability of the rig in order for the rig to be held in position to conduct drilling at a water depth of 476 m.The overall duration of the drilling was 50 days and the upgraded mooring system proved to be efficient in achieving the goal of keeping the rig stationary while it was drilling the trial well in the South China Sea.This successful campaign demonstrates that an older semi-submersible rig can take on drilling in deep water after careful design and proper upgrading and modification to the original mooring system.展开更多
The increase of human population generates the need to improve the efficiency of food production. A thorough planning is required following the scope of economic and sustainable development, being irrigation a basic t...The increase of human population generates the need to improve the efficiency of food production. A thorough planning is required following the scope of economic and sustainable development, being irrigation a basic tool, however water availability is restricted and it obliges farmers to progress increasing water productivity. Irrigation uses around 70% of total available fresh water, while irrigation water application efficiency is around 40%. Irrigation systems must follow strong criteria at the design stage to achieve high values of water productivity. Maintenance is indispensable to follow the original functioning level of those systems. At last the daily precise management of systems, following soil water potential, considering the effective rain storage at root depth of the crop and the evolution of daily evapotranspiration, preserving natural resources, are relevant to achieve low values of water footprint of this crop. In an 8 year drip irrigation system, the Uniformity Coefficient of Christiansen (UCC) measured was 95.14%;the Uniform Coefficient of the Minor Quart (UCMQ) was 93.16%. The Total Distribution Efficiency (EDT) was 95.13% when measurements finished while the irrigation systems is of. When measurements also considered the volume collected during the “recession phase in drip irrigation” and the “volume of water collected during recession phase in drip irrigation” collected at different points, EDT was 95.13%. Moreover it can be seen that when three different typical soil of the area were considered, the EDT was, 91.85%, 91.47% and 90.30% respectively, according with different water storage capacity of each soil. The Total Distribution Efficient is a strong method, to evaluate the design and management of drip irrigation systems, under different design criteria, management practices and maintenance of the systems. Water footprint in a blueberry (Vaccinium corymbosum L.) crop with drip and sprinkler anti-frost system, were measure and values obtained were 846, 310, 223, 212, 172 and 218 liters per kg of fresh fruit in the period 2010-2015. The UCC and the UCMQ reflects properly the irrigation design, while the EDT reflects irrigation design, management and maintenance. Water footprint is at last the strong tool to evaluate design and operation of the irrigation system and crop management.展开更多
文摘The wear mechanism and tool life of four types of oil country tubular goods chasers are studied herein via metallographic microscopy,scanning electron microscopy,and energy dispersive spectroscopy.Results show that when the tool has a fine and uniform microstructure,the main failure mode is wear failure.Furthermore,observed phenomena including large chip bonding,coating peeling,cracks demonstrate that the main wear mechanisms of the tool are adhesive wear,abrasive wear,coating flaking,and microchipping.
基金the Shanghai Sailing Program(No.17YF1403100)the National Natural Science Foundation of China(No.51705155)+1 种基金the Shanghai Minhang District University-Industry Cooperation Project(No.2017MH287)the Important National Science and Technology Specific Projects(No.2018ZX04040001)
文摘The effect of cutting teeth number on the cutting force,surface roughness,tool wear rate and the cutting chip shape charac teristics is systematically evaluated.A novel five tee th chaser insert(C tool)which could turn the workpiece at five cutting points simultaneously is involved in comparison with the standard triangle shaped insert(T tool),in the purpose of solving the problems of cutting heat concentration and rapid tool failures in the Inconel 718 machining process.Comparative orthogonal cut ting experimen ts of the C tool and T tool show that the cut ting depth is the significant influencing factor of the cutting forces.Meanwhile,the five cut ting teeth of the C tool show the effec tiveness of dispersing the cut ting forces as well as improving the cut ting efficiency.The feed rate is the significant factor to affect the root-mean-square surface roughness(Ra)of workpiece machined by the T tool,while the significant influencing variable of Ra for the C tool is the cutting depth due to its unique tool geome try(0°rake angle)in the axial feeding process.Moreover,due to the dispersing effect,the cut ting edges on the C tool exhibits lower tool wear rate than that of the T tool under the same axial feed.The chips are regular continuous long chips for the T tool,while the irregular continuous chips with the characteristic of saw-toothed profile are obtained due to its unique 0°rake angle.The C tool shows the valid potential for effectively dispersing the cut ting heat and slowing down the tool wear rate in the Inconel 718 machining process.
文摘Mooring systems play an important role for semi-submersible rigs that drill in deepwater.A detailed analysis was carried out on the mooring of a semi-submersible rig that conducted a trial well drilling at a deepwater location in the South China Sea in 2009.The rig was 30 years old and had a shallow platform with a designed maximum operating water depth of 457 m.Following the mooring analysis,a mooring design was given that requires upgrading of the rig’s original mooring system.The upgrade included several innovations,such as installing eight larger anchors,i.e.replacing the original anchors and inserting an additional 600 m of steel wires with the existing chains.All this was done to enhance the mooring capability of the rig in order for the rig to be held in position to conduct drilling at a water depth of 476 m.The overall duration of the drilling was 50 days and the upgraded mooring system proved to be efficient in achieving the goal of keeping the rig stationary while it was drilling the trial well in the South China Sea.This successful campaign demonstrates that an older semi-submersible rig can take on drilling in deep water after careful design and proper upgrading and modification to the original mooring system.
文摘The increase of human population generates the need to improve the efficiency of food production. A thorough planning is required following the scope of economic and sustainable development, being irrigation a basic tool, however water availability is restricted and it obliges farmers to progress increasing water productivity. Irrigation uses around 70% of total available fresh water, while irrigation water application efficiency is around 40%. Irrigation systems must follow strong criteria at the design stage to achieve high values of water productivity. Maintenance is indispensable to follow the original functioning level of those systems. At last the daily precise management of systems, following soil water potential, considering the effective rain storage at root depth of the crop and the evolution of daily evapotranspiration, preserving natural resources, are relevant to achieve low values of water footprint of this crop. In an 8 year drip irrigation system, the Uniformity Coefficient of Christiansen (UCC) measured was 95.14%;the Uniform Coefficient of the Minor Quart (UCMQ) was 93.16%. The Total Distribution Efficiency (EDT) was 95.13% when measurements finished while the irrigation systems is of. When measurements also considered the volume collected during the “recession phase in drip irrigation” and the “volume of water collected during recession phase in drip irrigation” collected at different points, EDT was 95.13%. Moreover it can be seen that when three different typical soil of the area were considered, the EDT was, 91.85%, 91.47% and 90.30% respectively, according with different water storage capacity of each soil. The Total Distribution Efficient is a strong method, to evaluate the design and management of drip irrigation systems, under different design criteria, management practices and maintenance of the systems. Water footprint in a blueberry (Vaccinium corymbosum L.) crop with drip and sprinkler anti-frost system, were measure and values obtained were 846, 310, 223, 212, 172 and 218 liters per kg of fresh fruit in the period 2010-2015. The UCC and the UCMQ reflects properly the irrigation design, while the EDT reflects irrigation design, management and maintenance. Water footprint is at last the strong tool to evaluate design and operation of the irrigation system and crop management.
