Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bond...Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bonding mechanism of the cold welding sealing process （CWSP） is investigated and compared with the experimental results obtained from the bonding interface analysis. An orthogonal experiment is conducted to observe the effects of various parameters, including the sealing gap, sealing length, sealing diameter, and sealing velocity on bonding strength. A method with the utilization of saturated vapor pressure inside a copper tube is proposed to evaluate bonding strength. A corresponding finite element model is developed to investigate the effects of sealing gap and sealing velocity on plastic deformation during the cold welding process. Effects of various parameters on the bonding strength are determined and it is found that the sealing gap is the most critical factor and that the sealing velocity contributes the least effect. The best parameter combination （AIB3CID3, with a 0.5 mm sealing gap, 6 mm sealing length, 3.8 mm sealing diameter, and 50 mm/s sealing velocity） is derived within the experimental parameters. Plastic deformation results derived from the finite element model are consistent with those from the experiment. The instruction for the CWSP of heat pipes and the design of sealing dies of heat pipes are provided.展开更多
The control manner during the process to ensure the quality of pipe products mainly relies on the operator’s experience, so it is very necessary to study the setting round process and obtain its spring-back law. The ...The control manner during the process to ensure the quality of pipe products mainly relies on the operator’s experience, so it is very necessary to study the setting round process and obtain its spring-back law. The setting round process is shaping an oval section pipe into circular section, so it is difficult to provide a quantificational analysis for its spring-back process because of the curvature inequality of pipe section neutral layer. However, the spring-back law of the circle-oval process can be easily predicted. The experimental method is firstly used to establish the equivalent effect between the setting round process and the circle-oval process. The setting round process can be converted into the circle-oval process. There are two difficulties in the theoretical analysis for the circle-oval process: elastic-plastic bending problem of curved beam; statically indeterminate problem. A quantitative analytic method for the circle-oval process is presented on the basis of combination of the spring-back law of plane curved beam with the element dividing idea in finite element method. The ovality after unloading versus the relative reduction is plotted with analytical and experimental results respectively, which shows a fair agreement. Finally, the method of quantitative prediction of reduction for large pipe setting round is given based on the equivalent effect and the analytical results. Five pipes, which are needed to be set round, are used to carry out experiment so as to verify this method. The results of verification experiment indicates that, in the experimental range, the residual ovality are all under 0.35% after the once only setting round with the theoretical prediction reductions. It is much less than the 1% requirement of pipe standard. Applying the established theoretical analysis is able to correct the pipe ovality with sufficient accuracy, which provides theoretical direction to plant use.展开更多
The West East pipeline project attracted the attention from all over the world for its long distance, huge diameter, complex geographic conditions, and diversified welding techniques being applied.In this paper the de...The West East pipeline project attracted the attention from all over the world for its long distance, huge diameter, complex geographic conditions, and diversified welding techniques being applied.In this paper the detail welding process and procedures used in the project are discussed and the distinguished achievements on welding techniques of China pipeline construction are described.展开更多
基于STT封底和全自动FCAW-G填充盖面焊接,开发了一种适用于双层海管外管全自动焊工艺,通过宏观形貌观察、力学性能测试等手段验证自动焊工艺下的海管焊接接头的可靠性,满足DNV OS F101:2017《海底管线系统》标准要求,可应用于X65碳素钢...基于STT封底和全自动FCAW-G填充盖面焊接,开发了一种适用于双层海管外管全自动焊工艺,通过宏观形貌观察、力学性能测试等手段验证自动焊工艺下的海管焊接接头的可靠性,满足DNV OS F101:2017《海底管线系统》标准要求,可应用于X65碳素钢海管外管的焊接施工。展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51175186,51675185)Guangdong Provincial Natural Science Foundation of China(Grant No.S2013020012757)EU project PIIF-GA-2012-332304(Grant No.ESR332304)
文摘Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bonding mechanism of the cold welding sealing process （CWSP） is investigated and compared with the experimental results obtained from the bonding interface analysis. An orthogonal experiment is conducted to observe the effects of various parameters, including the sealing gap, sealing length, sealing diameter, and sealing velocity on bonding strength. A method with the utilization of saturated vapor pressure inside a copper tube is proposed to evaluate bonding strength. A corresponding finite element model is developed to investigate the effects of sealing gap and sealing velocity on plastic deformation during the cold welding process. Effects of various parameters on the bonding strength are determined and it is found that the sealing gap is the most critical factor and that the sealing velocity contributes the least effect. The best parameter combination （AIB3CID3, with a 0.5 mm sealing gap, 6 mm sealing length, 3.8 mm sealing diameter, and 50 mm/s sealing velocity） is derived within the experimental parameters. Plastic deformation results derived from the finite element model are consistent with those from the experiment. The instruction for the CWSP of heat pipes and the design of sealing dies of heat pipes are provided.
基金supported by National Natural Science Foundation of China (Grant No. 51175452)Hebei Provincial Natural Science Foundation of China (Grant No. E2012203061)
文摘The control manner during the process to ensure the quality of pipe products mainly relies on the operator’s experience, so it is very necessary to study the setting round process and obtain its spring-back law. The setting round process is shaping an oval section pipe into circular section, so it is difficult to provide a quantificational analysis for its spring-back process because of the curvature inequality of pipe section neutral layer. However, the spring-back law of the circle-oval process can be easily predicted. The experimental method is firstly used to establish the equivalent effect between the setting round process and the circle-oval process. The setting round process can be converted into the circle-oval process. There are two difficulties in the theoretical analysis for the circle-oval process: elastic-plastic bending problem of curved beam; statically indeterminate problem. A quantitative analytic method for the circle-oval process is presented on the basis of combination of the spring-back law of plane curved beam with the element dividing idea in finite element method. The ovality after unloading versus the relative reduction is plotted with analytical and experimental results respectively, which shows a fair agreement. Finally, the method of quantitative prediction of reduction for large pipe setting round is given based on the equivalent effect and the analytical results. Five pipes, which are needed to be set round, are used to carry out experiment so as to verify this method. The results of verification experiment indicates that, in the experimental range, the residual ovality are all under 0.35% after the once only setting round with the theoretical prediction reductions. It is much less than the 1% requirement of pipe standard. Applying the established theoretical analysis is able to correct the pipe ovality with sufficient accuracy, which provides theoretical direction to plant use.
文摘The West East pipeline project attracted the attention from all over the world for its long distance, huge diameter, complex geographic conditions, and diversified welding techniques being applied.In this paper the detail welding process and procedures used in the project are discussed and the distinguished achievements on welding techniques of China pipeline construction are described.
