本文關(guān)鍵詞： 負(fù)重輪 擠壓鑄造 數(shù)值模擬 復(fù)合加壓　出處：《中北大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：科技時(shí)代的到來,使高精度、輕量化和高性能的武器裝備成為各個(gè)國家發(fā)展的重點(diǎn)。而負(fù)重輪是裝甲車輛行走系統(tǒng)的關(guān)鍵部件,直接影響著整個(gè)裝甲車的重量和性能。使用鋁合金替代原有鋼質(zhì)材料可大大減輕裝甲車重量,實(shí)現(xiàn)輕量化,提高裝甲車作戰(zhàn)機(jī)動(dòng)性。壓鑄、模鍛和擠壓鑄造工藝是目前負(fù)重輪生產(chǎn)的主要方法。其中,擠壓鑄造是一種介于鑄鍛之間綜合了鑄鍛加工優(yōu)點(diǎn)、少切削或無切削的近終形成型技術(shù),適合于補(bǔ)縮困難、壁厚不均勻的鑄件。該工藝一次成型獲得晶粒細(xì)小、組織均勻、力學(xué)性能優(yōu)良的鑄件且機(jī)加工量小、節(jié)省材料,不僅能保證產(chǎn)品的使用性能,而且具有良好的經(jīng)濟(jì)性能。因此,在負(fù)重輪的生產(chǎn)工藝中,首選擠壓鑄造。在學(xué)習(xí)掌握擠壓鑄造工藝原理及特點(diǎn)、凝固過程的傳熱學(xué)規(guī)律以及壓力下凝固過程的力學(xué)成形過程等相關(guān)知識后,采用Pro CAST三維模擬軟件,成功的模擬出負(fù)重輪擠壓鑄造工藝的凝固過程,得到了不同壓力下的溫度場變化和縮松、縮孔缺陷的預(yù)測結(jié)果。在結(jié)合國內(nèi)擠壓鑄造設(shè)備情況和鑄件補(bǔ)縮特點(diǎn)的基礎(chǔ)上,根據(jù)模擬結(jié)果改進(jìn)了工藝方案并優(yōu)化模具設(shè)計(jì)。本文主要有以下結(jié)論:(1)根據(jù)凝固傳熱學(xué)的基本理論,建立負(fù)重輪的溫度場數(shù)學(xué)傳熱模型并給出求解,成功應(yīng)運(yùn)于溫度場模擬,進(jìn)而預(yù)測缺陷。(2)不同比壓下的溫度場模擬結(jié)果表明:負(fù)重輪在壓力下由表到里逐漸凝固,但各部位的凝固速度有明顯區(qū)別。負(fù)重輪比較厚大的拐角部位,凝固最慢;而負(fù)重輪的表面,凝固最快。負(fù)重輪的凝固速度隨壓力的增大而加快。(3)負(fù)重輪的凝固時(shí)間隨壓力的增大而減小。(4)在研究壓力對縮松、縮孔的影響時(shí),發(fā)現(xiàn)壓力的增大可以有效的減少縮孔和縮松,而當(dāng)壓力增大到100MPa后縮松和縮孔消失。(5)擠壓鑄造加載方式,由常規(guī)簡單加壓調(diào)整為復(fù)合加壓。對復(fù)合加壓的擠壓鑄造工藝數(shù)值模擬,發(fā)現(xiàn)較低的壓力下縮松縮孔就大大減少甚至消失。實(shí)驗(yàn)驗(yàn)證,復(fù)合加壓的負(fù)重輪件,抗拉強(qiáng)度和伸長率已達(dá)標(biāo),即力學(xué)性能已符合科研項(xiàng)目的要求。(6)文中在補(bǔ)縮量為4mm的復(fù)合加壓擠壓鑄造工藝中,采用澆注溫度730℃、模具預(yù)熱溫度300℃,保壓時(shí)間32S的主要工藝參數(shù)獲得的負(fù)重輪件,其整體抗拉強(qiáng)度σ_b為361.5MPa,伸長率δ為8.18%,滿足項(xiàng)目σ_b360MPa、δ6%的力學(xué)要求。(7)在復(fù)合加壓擠壓鑄造工藝可行的基礎(chǔ)上,優(yōu)化負(fù)重輪的成形模具,研發(fā)成形模具的控溫系統(tǒng)并介紹其組成設(shè)備如加熱裝置、冷卻裝置、定位裝置的工作原理。
[Abstract]:With the advent of the era of science and technology, high-precision, lightweight and high-performance weapons and equipment have become the focus of each country's development. And the load-bearing wheel is the key component of the armored vehicle's walking system. It has a direct impact on the weight and performance of the whole armored vehicle. Using aluminum alloy to replace the original steel material can greatly reduce the weight of the armored vehicle, achieve lightweight, and improve the operational mobility of the armored vehicle. Die forging and squeeze casting are the main methods in the production of load-bearing wheels at present. Among them, squeeze casting is a kind of near-end forming technology which combines the advantages of casting and forging with less cutting or no cutting, and is suitable for the difficulty of feeding. Casting with uneven wall thickness. The casting with fine grain size, uniform microstructure, good mechanical properties and low machining quantity can not only guarantee the performance of the product, but also have good economic performance. In the production process of load bearing wheel, the first choice is squeeze casting. After studying and mastering the principle and characteristics of squeeze casting process, the law of heat transfer in solidification process and the mechanical forming process of solidification process under pressure, and so on, The solidification process of weight bearing wheel squeeze casting process was successfully simulated by using Pro CAST 3D simulation software, and the temperature field and shrinkage were obtained under different pressure. Prediction results of shrinkage defects. On the basis of combining the situation of squeeze casting equipment in China and the characteristics of casting shrinkage, According to the simulation results, the technological scheme is improved and the die design is optimized. In this paper, the following conclusions are drawn: 1) according to the basic theory of solidification heat transfer, the mathematical heat transfer model of the temperature field of the load-bearing wheel is established and solved, which should be successfully applied to the simulation of the temperature field. The simulation results of temperature field under different specific pressures show that the weight bearing wheel solidifies gradually from surface to interior under pressure, but the solidification speed of each part is obviously different. The thickest corner is the slowest solidification. The solidification rate of the load wheel increases with the increase of pressure, and the solidification time decreases with the increase of pressure. 4) in the study of the influence of pressure on shrinkage and shrinkage, the solidification rate of the bearing wheel is quickened with the increase of the pressure, and the solidification time of the wheel decreases with the increase of the pressure, and the solidification time decreases with the increase of the pressure. It is found that the increase of pressure can effectively reduce the shrinkage and porosity, but when the pressure increases to 100 MPA, the shrinkage and shrinkage disappear. By adjusting the conventional simple pressure to the compound pressure, the numerical simulation of the squeeze casting process shows that the shrinkage shrinkage holes are reduced or even disappeared at lower pressure. The experimental results show that the composite pressure bearing wheel parts, The tensile strength and elongation have reached the standard, that is, the mechanical properties have met the requirements of the scientific research project. In this paper, the casting temperature is 730 鈩，

本文編號：1547422