本文選題：PE管道 + 熱熔焊接接頭�。� 參考：《哈爾濱理工大學》2015年碩士論文

【摘要】：隨著社會和科技的進步，聚乙烯（PE）管道由于其優(yōu)越的性能，逐步取代了傳統(tǒng)金屬管道，，在給水和燃氣輸送等領(lǐng)域的應(yīng)用越來越廣，已成為維持城鎮(zhèn)居民正常生活必不可少的管道系統(tǒng)。聚乙烯管道的連接方式主要有熱熔焊接和電熔焊接，其中熱熔焊接的應(yīng)用最為廣泛。在聚乙烯管道熱熔焊接過程中，由焊接參數(shù)選擇不當引起的工藝缺陷極容易被忽視，給聚乙烯管道系統(tǒng)留下了重大隱患。因此，對含工藝缺陷的熱熔焊接接頭的力學性能進行研究，分析焊接接頭的失效機理，可有效的避免聚乙烯管道熱熔焊接過程中工藝缺陷的產(chǎn)生，保證管道系統(tǒng)的安全穩(wěn)定。 本文通過對聚乙烯管材力學性能試驗方法的總結(jié)與對比，并結(jié)合本試驗?zāi)繕伺c條件，決定采用拉伸試驗來判定聚乙烯管道熱熔焊接接頭的性能優(yōu)劣。在拉伸試驗之前，根據(jù)標準GB/T8804和GB/T19810，對拉伸試樣形式進行改進，獲得了制備簡便，能直接獲得熱熔焊焊縫拉伸性能的試樣形式，并重新確定了拉伸速率。對熱熔焊接接頭的拉伸屈服強度進行方差分析，分析得出加熱溫度和焊接壓力兩個焊接參數(shù)對熱熔焊接接頭拉伸性能的影響十分顯著，而其他三個焊接參數(shù)（加熱時間、切換時間和壓焊冷卻時間）相比于加熱溫度和焊接壓力來說，其影響可以說是微乎其微，在加熱溫度為210℃和焊接壓力為0.2MPa時熱熔焊接接頭的拉伸性能最佳。 本文從PE管道熱熔焊接接頭的焊縫失效斷口入手，采用掃描電鏡對含工藝缺陷熱熔焊接接頭的焊縫失效斷口進行顯微觀察，并利用X射線衍射法測量了焊縫的結(jié)晶度。對大量的斷口形貌進行對比，總結(jié)得出失效斷口的微觀形貌組成，分為銀紋區(qū)域和黑色片層區(qū)域，兩區(qū)域之間有明顯分界，并分析得出了斷口形貌的成因。最后結(jié)合熱熔焊接接頭的拉伸屈服強度，分析焊縫失效斷口的顯微形貌和焊縫的結(jié)晶度與拉伸性能的關(guān)系，獲得了由加熱溫度和焊接壓力引起的工藝缺陷的失效機理，其最主要影響因素就是，受到應(yīng)力作用時熱熔焊接接頭處聚乙烯無定形區(qū)內(nèi)系帶分子鏈的數(shù)量與取向。
[Abstract]:With the development of society and science and technology, the PE pipe has gradually replaced the traditional metal pipeline because of its superior performance, and has been used more and more widely in the fields of water supply and gas transportation. It has become an indispensable pipeline system to maintain the normal life of urban residents. The connection modes of PE pipeline are mainly hot-melt welding and electric fusion welding, among which the hot-melt welding is the most widely used. In the process of hot-melt welding of polyethylene pipeline, the technological defects caused by improper selection of welding parameters are easily ignored, leaving a great hidden danger to the polyethylene pipeline system. Therefore, the mechanical properties of hot-melt welded joints with process defects are studied, and the failure mechanism of welded joints is analyzed, which can effectively avoid the production of technological defects in the process of hot-melt welding of polyethylene pipelines and ensure the safety and stability of pipeline systems. Based on the summary and comparison of the test methods of mechanical properties of polyethylene pipes and combined with the objectives and conditions of this test, this paper decides to use tensile test to judge the properties of hot-melt welded joints of polyethylene pipes. Before the tensile test, according to the standard GB/T8804 and GBR / T19810, the form of the tensile specimen was improved, and the form of the sample which was easy to be prepared and the tensile properties of the weld could be obtained directly was obtained, and the tensile rate was redetermined. The variance analysis of tensile yield strength of hot-melt welded joint shows that the two welding parameters, heating temperature and welding pressure, have a significant effect on the tensile properties of hot-melt welded joint, while the other three welding parameters (heating time, etc.) Compared with heating temperature and welding pressure, the effect of switching time and welding cooling time is minimal, and the tensile properties of hot-melt welded joints are the best when heating temperature is 210 鈩

本文編號：1908250