【摘要】：大型環(huán)形零件是海上風力發(fā)電、航空航天、海洋船舶的制造及電力、石油、工程機械等方面廣泛應用的關(guān)鍵零件。環(huán)件輾擴新技術(shù)已經(jīng)能夠很好的輾擴生產(chǎn)矩形截面環(huán)件,它具有省力、節(jié)能、節(jié)材、生產(chǎn)效率高、生產(chǎn)成本低等顯著特點。在實際異形環(huán)件輾擴過程中,輾擴過程不穩(wěn)定,輾擴環(huán)件的尺寸精度低和微觀組織及力學性能控制難度大,輾擴力較大,易導致模具損壞,這在一定程度上限制了異形環(huán)件輾擴工藝在工程中的應用。要解決上述問題必須研究和掌握輾擴過程中金屬的流動規(guī)律,選擇合理的輾擴模具以及合理的芯輥進給策略及軋輥運動控制方法。本文利用數(shù)值模擬的方法,對一種既有外凹槽又有內(nèi)臺階的大型非矩形截面的環(huán)件進行了熱力耦合模擬分析。通過Gleeble-3500實驗機建立了Q345E鋼的流變應力模型,針對成形產(chǎn)品復雜的輪廓特點,采用多步輾擴,并對每步輾擴多次改進輾擴用毛坯,設(shè)計出兩套合理的模具,推導了輾擴過程中軋輥的運動控制方程,確定了輾擴過程中環(huán)件的塑性鍛透條件和咬入條件,獲得了軋輥轉(zhuǎn)速和芯輥進給速度的合理取值范圍。在此基礎(chǔ)上,分別建立了內(nèi)臺階雙件輾擴和帶有內(nèi)臺階的外凹槽環(huán)件熱輾擴過程的有限元數(shù)值模擬模型,分別獲得了兩種環(huán)件熱輾擴環(huán)件等效應變及溫度隨輾擴時間的變化規(guī)律,系統(tǒng)的研究了不同鍛坯加熱溫度、驅(qū)動輥轉(zhuǎn)速、芯輥進給速度等工藝參數(shù)對環(huán)件輾擴過程的等效應變和溫度分布、徑向輾擴力和力矩的影響規(guī)律,優(yōu)化第二步外凹槽輾擴工藝參數(shù),確定了一種可運用于實際生產(chǎn)的有限元模型。數(shù)值模擬研究表明,利用所建立的模型可以實現(xiàn)異形環(huán)件多步輾擴的生產(chǎn)。其中在預熱溫度1250℃、芯輥速率0.8mm/s、1mm/s、驅(qū)動輥轉(zhuǎn)速30.6r/min輾擴時環(huán)件的最大應變出現(xiàn)在外徑的棱角處和內(nèi)徑上下兩個端面,環(huán)件塑性變形區(qū)由這些部位向環(huán)件的其它部位擴展,內(nèi)臺階輪廓在100s左右完全充滿,充滿狀況較好,前100s環(huán)件發(fā)生局部變形,直徑長大不明顯,直徑長大主要發(fā)生在100s以后的輾擴階段;輾擴外凹槽時芯輥進給速率分別為1.2mm/s、0.8mm/s、0.3mm/s逐級減速,驅(qū)動輥轉(zhuǎn)速7.644r/min參數(shù)下,環(huán)件的外凹槽在85s左右充滿,整個環(huán)件的塑性變形是由外凹槽部位與環(huán)件內(nèi)徑小半徑的臺階部位向環(huán)件的其它部位擴展的,等效應變的最大值在外凹槽部位與臺階部位。
[Abstract]:Large annular parts are the key parts of offshore wind power generation, aerospace, marine ship manufacture, electric power, petroleum, construction machinery and so on. The new ring rolling technology has been able to produce rectangular section ring, which is characterized by saving labor, saving energy, saving materials, high production efficiency, low production cost and so on. In the process of rolling, the rolling process is unstable, the dimension precision of ring rolling is low, the control of microstructure and mechanical properties is difficult, and the rolling force is large, which can easily lead to die damage. To a certain extent, the application of ring rolling technology in engineering is limited. In order to solve the above problems, it is necessary to study and master the rule of metal flow in the rolling process, select reasonable rolling die, reasonable feeding strategy of core roll and control method of roll motion. In this paper, the thermodynamic coupling analysis of a large non-rectangular ring with both external grooves and inner steps is carried out by means of numerical simulation. The flow stress model of Q345E steel was established by Gleeble-3500 test machine. In view of the complex profile characteristics of the forming products, multi-step rolling was adopted, and two sets of reasonable dies were designed for improving the blanks for rolling several times in each step of rolling. The control equation of roll motion during rolling process is derived, the plastic forging penetration condition and biting condition of ring during rolling process are determined, and the reasonable range of roll speed and feed speed of core roll is obtained. On this basis, the finite element numerical simulation models of the hot rolling process of the inner step double-piece ring and the outer groove ring with inner step are established, respectively. The changes of equivalent strain and temperature with rolling time of two kinds of hot rolling ring were obtained, and the heating temperature of different forging billet and the rotation speed of driving roll were studied systematically. The influence of process parameters such as feed speed of core-roller on equivalent strain and temperature distribution, radial rolling force and moment of ring rolling process is studied, and the technological parameters of second step external groove rolling are optimized. A finite element model which can be used in practical production is determined. The numerical simulation results show that the multi-step ring rolling can be realized by using the established model. When the preheating temperature is 1250 鈩，

本文編號：2305131