【摘要】：近年來,隨著制造業(yè)水平的提高,高精密、低能耗、安全環(huán)保的產(chǎn)品生產(chǎn)已成為塑性成形領域創(chuàng)新研究的熱點課題,不斷推動著新型工藝的發(fā)展。板鍛造是以板料或其半成品為毛坯在沖壓成形過程中控制材料流動成形局部具有三維特征結(jié)構(gòu)金屬件的精密塑性成形方法,成形板材上帶凸起結(jié)構(gòu)特征的薄板零件具有明顯的優(yōu)越性。本文以筒形件底部實心凸起結(jié)構(gòu)板鍛造成形為例,基于主應力法,分析了筒形件底部實心凸起成形過程中拉深區(qū)域、凸模圓角區(qū)域及凸模底部區(qū)域的力學特征,重點研究了凸起底部和凸模圓角底部應力分布及金屬流動規(guī)律,建立了凸起底部縮孔力學模型,推導出了凸起底部極限板材厚度的理論預測公式,提出了彎矩作用成形實心凸起的概念�；贒EFORM有限元軟件平臺,開發(fā)了Swift本構(gòu)模型的子程序模塊,從而對筒形件底部實心凸起板鍛造成形過程進行模擬分析,對比了反擠壓和板鍛造成形實心凸起應力分布和材料流動速度分布情況。模擬結(jié)果發(fā)現(xiàn),兩種成形工藝在實心凸起底部擠壓區(qū)應力具有沿厚度方向和半徑方向呈線性增加分布;當成形同一實心凸起高度時,反擠壓成形載荷僅是板鍛造成形載荷的兩倍左右,且在擠壓區(qū)徑向流動速度是板鍛造成形的幾十倍。同時,探討了摩擦條件、凸起幾何結(jié)構(gòu)及毛坯厚度對實心凸起底部缺陷形成的影響規(guī)律,建立了實心凸起板鍛造成形失效機制圖。研究結(jié)果表明,板材凸起一側(cè)潤滑條件越差,凸起半徑越大、凸起圓角越小、毛坯越薄越容易形成縮孔;當凸起圓角半徑過大,一次縮孔深度隨凸起底部厚度減薄一直增加。此外,通過板鍛造成形實心凸起結(jié)構(gòu)工藝試驗,驗證了理論結(jié)果與模擬結(jié)果的可靠性。最后文章提出了貨車搖動座板鍛造成形工藝,并對模具和毛坯結(jié)構(gòu)進行了優(yōu)化,顯著減少了成形工序,節(jié)約了材料,提高了搖動座成形性能。
[Abstract]:In recent years, with the improvement of manufacturing level, the production of high precision, low energy consumption, safety and environmental protection products has become a hot topic in the field of plastic forming innovation, and has been promoting the development of new technology. Plate forging is a kind of precision plastic forming method in which sheet metal or its semi-finished product is used as blank in stamping process to control material flow forming with three dimensional characteristic structure metal parts. Sheet parts with protruding structural features have obvious advantages. In this paper, based on the principal stress method, the mechanical characteristics of the drawing region, the corner region of the die and the bottom region of the convex die are analyzed based on the principal stress method, taking the forging forming of the solid bulge structure plate at the bottom of the cylindrical part as an example. The stress distribution and metal flow law at the bottom of the convex bottom and the corner of the die are studied emphatically, the mechanical model of the shrinkage hole at the bottom of the convex is established, and the theoretical prediction formula of the thickness of the ultimate plate at the bottom of the convex is derived. The concept of solid bulge formed by bending moment is proposed. Based on the DEFORM finite element software platform, the subroutine module of Swift constitutive model is developed, and the forging process of solid raised plate at the bottom of cylindrical part is simulated and analyzed. The distribution of solid protruding stress and material flow velocity in reverse extrusion and plate forging were compared. The simulation results show that the stress of the two forming processes increases linearly along the direction of thickness and radius in the extrusion zone at the bottom of the solid bulge, and when the forming is at the same height of the solid bulge, The forming load of back extrusion is only twice as much as that of plate forging, and the radial velocity of flow in the extrusion zone is tens of times that of plate forging. At the same time, the influence of friction conditions, geometric structure of bulge and thickness of blank on the formation of defects at the bottom of solid bulge is discussed, and the failure mechanism diagram of forging forming of solid convex plate is established. The results show that the worse the lubrication condition is, the larger the raised radius is, and the smaller the raised rounded angle is, the thinner the blank is, and when the radius of the raised corner is too large, the depth of the first shrinkage hole increases with the thickness of the bottom of the bulge. In addition, the reliability of the theoretical and simulation results is verified by the experimental results of solid bulge structure formed by plate forging. In the end, the forging process of truck rocker seat plate is put forward, the die and blank structure are optimized, the forming procedure is reduced, the material is saved, and the forming property of rocker seat is improved.
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG316

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