發(fā)布時(shí)間：2018-09-13 12:29

【摘要】：橋殼是安裝差速器、減速器和輪轂的基礎(chǔ)件，在使用過(guò)程中，要承受較大的沖擊載荷及摩擦磨損，必須具備良好的綜合力學(xué)性能。本文的主要目的是對(duì)樹(shù)脂砂型鑄造球墨鑄鐵叉車驅(qū)動(dòng)橋殼的鑄造工藝進(jìn)行設(shè)計(jì)和研究，并運(yùn)用華鑄CAE模擬軟件對(duì)鑄件的充型和凝固過(guò)程進(jìn)行模擬，分析鑄件在鑄造過(guò)程中產(chǎn)生缺陷的原因，以優(yōu)化鑄造工藝，，消除鑄造缺陷，獲得優(yōu)質(zhì)的橋殼鑄件。 首先，根據(jù)QT450-10橋殼的材質(zhì)要求和鑄件的結(jié)構(gòu)特點(diǎn)，提出橋殼鑄造工藝的初始方案，利用模擬軟件對(duì)工藝方案下鑄件的充型和凝固過(guò)程進(jìn)行模擬，分析橋殼鑄件流動(dòng)場(chǎng)、溫度場(chǎng)的變化規(guī)律。模擬結(jié)果顯示橋殼鑄件中在冒口補(bǔ)縮部位和半軸部位出現(xiàn)了較多的縮松缺陷，縮松總體積為79.33cc，在下部端蓋厚壁部位和頂部凸臺(tái)部位產(chǎn)生縮孔缺陷，縮孔總體積為0.07cm3。 從改變冒口高度和冒口直徑兩個(gè)方面對(duì)初步的工藝方案進(jìn)行了改進(jìn)，并對(duì)改進(jìn)工藝下橋殼的凝固過(guò)程進(jìn)行模擬，結(jié)果表明：冒口高度、冒口直徑的增加并不能有效的增加冒口的補(bǔ)縮效果，鑄件上的縮孔、縮松缺陷未能得到徹底消除。進(jìn)而采用改變冒口頸長(zhǎng)度和冒口頸截面尺寸方法進(jìn)行工藝改進(jìn)，由模擬結(jié)果發(fā)現(xiàn)：通過(guò)減小冒口頸長(zhǎng)度、增加冒口頸截面尺寸，使得冒口頸的凝固時(shí)間延長(zhǎng)，擴(kuò)大了補(bǔ)縮通道，提高了冒口的補(bǔ)縮效果，基本上消除了冒口補(bǔ)縮部位的縮松缺陷，鑄件上的縮松總體積減為45.00cc，縮松缺陷主要出現(xiàn)在鑄件半軸部位。通過(guò)在鑄件半軸部位增加補(bǔ)貼，形成從半軸到冒口逐漸增加的溫度梯度，增大了冒口的有效補(bǔ)縮距離，半軸部位的縮松缺陷基本上被消除，鑄件縮松總體積減為10.43cc。 進(jìn)一步通過(guò)設(shè)置冷鐵及出氣孔的方法消除了鑄件中的縮孔和氣孔缺陷。橋殼鑄件下部端蓋厚壁處在凝固過(guò)程中易出現(xiàn)縮孔缺陷，通過(guò)在端蓋厚壁處放置冷鐵，提高了厚壁處的凝固速度，避免厚壁處凝固時(shí)出現(xiàn)孤立液相區(qū)，進(jìn)而消除了端蓋部位的縮孔缺陷。針對(duì)橋殼鑄件頂部在凝固過(guò)程中出現(xiàn)縮孔、氣孔的問(wèn)題，采用在鑄件頂部安放出氣孔、出氣片的方法，有效的消除了橋殼鑄件頂部的縮孔、氣孔缺陷。 本文通過(guò)模擬分析和工藝改進(jìn)得到了橋殼最優(yōu)化的鑄造工藝方案，橋殼鑄件中的縮孔、氣孔缺陷全部被消除，縮松總體積減為6.74cc。
[Abstract]:The axle housing is the foundation for the installation of differential, reducer and hub. In order to bear large impact load and friction and wear, it is necessary to have good comprehensive mechanical properties. The main purpose of this paper is to design and study the casting technology of the drive axle shell of the ductile iron forklift truck in resin sand casting, and to simulate the filling and solidification process of the casting by using the CAE software. In order to optimize the casting process and eliminate the casting defects, the causes of defects in casting are analyzed, and high quality castings of bridge shell are obtained. Firstly, according to the material requirements of QT450-10 bridge shell and the structural characteristics of casting, the initial scheme of bridge shell casting process is put forward. The filling and solidification process of the casting under the process plan is simulated by simulation software, and the flow field of bridge shell casting is analyzed. The variation of temperature field. The simulation results show that there are many shrinkage defects in the riser feeding part and half shaft part, the total volume of shrinkage is 79.33 cc. the shrinkage defect is produced in the thick wall part of the lower end cover and the top convex part, and the total volume of the shrinkage hole is 0.07 cm ~ 3. The preliminary technological scheme was improved from two aspects: riser height and riser diameter, and the solidification process of the bridge shell was simulated under the improved technology. The results show that the riser height, The increase of riser diameter can not effectively increase the shrinkage effect of riser, and the shrinkage hole and shrinkage defect on casting can not be completely eliminated. By changing the length of riser neck and the size of riser neck section, the simulation results show that by reducing the length of riser neck and increasing the size of riser neck section, the solidification time of riser neck is prolonged and the feeding channel is enlarged. The shrinkage effect of the riser is improved and the shrinkage defect of the feeding part of the riser is basically eliminated. The total volume of shrinkage on the casting is reduced to 45.00 cc.The shrinkage defect mainly occurs in the half shaft of the casting. By increasing the subsidy on the half shaft of the casting, the temperature gradient from the half shaft to the riser is gradually increased, and the effective feeding distance of the riser is increased. The shrinkage defect of the half shaft is basically eliminated, and the total volume of the casting shrinkage is reduced to 10.43 cc. Furthermore, the shrinkage and porosity defects in the casting were eliminated by setting cold iron and outlet holes. In the course of solidification, the thick wall of the bottom end cover of the bridge housing casting is prone to the defect of shrinkage holes. By placing cold iron at the thick wall of the end cap, the solidification speed of the thick wall is improved, and the isolated liquid phase zone is avoided when the thick wall is solidified. Furthermore, the shrinkage defect of the end cover is eliminated. Aiming at the problem of shrinkage and porosity in the top of the bridge shell castings during the solidification process, the method of placing air holes in the top of the castings is adopted, which effectively eliminates the shrinkage holes and blowhole defects at the top of the bridge shell castings. Through simulation analysis and technological improvement, the optimum casting process scheme of bridge shell is obtained. The shrinkage hole and pore defect are eliminated and the total volume of shrinkage is reduced to 6.74 cc.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TG255;TH242

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