【摘要】：鑄造是液態(tài)金屬先充填鑄件的型腔,然后在其中受冷凝固的過程。充型過程和凝固過程對(duì)最后的鑄件質(zhì)量好壞起到至關(guān)重要的作用,對(duì)縮孔、縮松、氣孔、夾渣等鑄造缺陷的產(chǎn)生有直接影響。因此,利用鑄造CAE軟件模擬充型和凝固過程,探究液態(tài)金屬充填型腔的充型順序以及充型過程中的溫度變化,探究凝固過程中的凝固次序以及溫度場分布,分析缺陷的形成機(jī)理及分布規(guī)律,進(jìn)而優(yōu)化工藝參數(shù)、改進(jìn)鑄造工藝,降低鑄件缺陷率,提高生產(chǎn)效率。本課題以金屬型鑄造水泵活塞為凝固模擬研究對(duì)象,通過華鑄CAE軟件進(jìn)行數(shù)值模擬,分析縮孔、縮松的分布及參數(shù)改變對(duì)其影響,尋找最佳的澆冒口系統(tǒng)、澆注溫度及模具溫度；以壓鑄割草機(jī)活塞為充型模擬研究對(duì)象,通過Flow-3D軟件進(jìn)行數(shù)值模擬,分析氣孔、夾渣的形成及分布機(jī)理,尋找最佳充型速度參數(shù)。針對(duì)水泵活塞的結(jié)構(gòu)特點(diǎn),設(shè)計(jì)出合適的澆注系統(tǒng)、頂冒口及側(cè)冒口的尺寸,模擬試加冒口、底注式工藝,改進(jìn)頂冒口及側(cè)冒口的尺寸,將澆注方式由底注改為中注,模擬改進(jìn)冒口、中注式工藝,由模擬結(jié)果分析得到最優(yōu)的澆冒口系統(tǒng)為改進(jìn)冒口、中注式工藝。在最優(yōu)的澆冒口系統(tǒng)基礎(chǔ)上,模具預(yù)熱溫度選擇為200℃,澆注溫度選取在700-800℃之間,模擬縮孔、縮松的分布,由模擬結(jié)果分析得到最佳的澆注溫度為780℃；澆注溫度選擇為780℃,模具預(yù)熱溫度選取在160-260℃之間,模擬縮孔、縮松的分布,由模擬結(jié)果分析得到最佳的模具溫度為200℃。應(yīng)用改進(jìn)冒口、中注式工藝,選擇澆注溫度780℃、模具溫度200℃,以此模擬得出的最優(yōu)工藝參數(shù)進(jìn)行生產(chǎn),最終得到的鑄件表面質(zhì)量好、內(nèi)部無孔洞,縮孔、縮松缺陷率始終在5%以內(nèi),達(dá)到了預(yù)期目標(biāo)。針對(duì)割草機(jī)活塞的結(jié)構(gòu)特點(diǎn),設(shè)定澆注溫度為680℃,模具預(yù)熱溫度為200℃,充型速度選取在50-500cm/s之間,模擬得到不同充型速度下的夾渣量和卷氣體積變化曲線。通過模擬結(jié)果分析,充型速度越小,充型時(shí)間越長,高溫合金液與鑄型反應(yīng)生產(chǎn)的氧化物越多,更重要的是,夾渣不能及時(shí)順著液流排到渣包,所以鑄件表面的夾渣量越多；充型速度越大,合金液填充型腔時(shí)卷入的氣體越多,碰撞上面型壁后回落時(shí)包裹的氣體越多,并且不能從排氣槽及時(shí)排出,所以鑄件內(nèi)部出現(xiàn)的氣孔越多。試驗(yàn)選擇性地做了充型速度50cm/s、200cm/s、400cm/s條件下的壓鑄實(shí)驗(yàn),從得到的活塞可以發(fā)現(xiàn),充型速度從50cm/s變化到200cm/s時(shí),夾渣缺陷大部分被消除,充型速度從400cm/s變化到200cm/s時(shí),氣孔缺陷減少了很多,與模擬結(jié)果得到的變化趨勢一致。
[Abstract]:Casting is a process in which liquid metal fills the cavity of the casting and is then solidified by cold. The filling process and solidification process play an important role in the final casting quality, and have a direct impact on the production of casting defects such as shrinkage, porosity, slag inclusion and so on. Therefore, the mold filling and solidification process are simulated by casting CAE software, and the filling order of liquid metal filling cavity and the temperature change in the filling process are explored, and the solidification sequence and temperature field distribution in the solidification process are also investigated. The forming mechanism and distribution law of defects are analyzed, and the process parameters are optimized, the casting process is improved, the defect rate of casting is reduced, and the production efficiency is improved. This subject takes the metal mold casting pump piston as the solidification simulation object, carries on the numerical simulation through the Hua casting CAE software, analyzes the shrinkage hole, the shrinkage porosity distribution and the parameter change to it, looks for the best pouring riser system. The pouring temperature and mold temperature, the piston of the die casting mower as the model filling simulation object, the numerical simulation by Flow-3D software, the analysis of the formation and distribution mechanism of the air hole and the slag inclusion, and the finding of the best filling speed parameter. According to the structural characteristics of pump piston, the proper gating system, the size of top riser and side riser, the simulated trial riser, the bottom casting process, the improvement of the size of the top riser and the side riser are designed, and the pouring mode is changed from the bottom injection to the middle injection. The simulation results show that the optimal riser system is the improved riser and the middle injection process. On the basis of the optimum pouring riser system, the preheating temperature of the die is 200 鈩，

本文編號(hào)：2153859