本文選題：板料壓扁 + 成形力　； 參考：《重慶理工大學(xué)》2017年碩士論文

【摘要】：板料壓扁成形是綜合體積成形和板料成形特點(diǎn)的一種工藝,一方面具有體積成形的三維特征即厚度差,另一方面作用對象是厚度較薄的板料,該工藝具有節(jié)省材料、強(qiáng)化基體的特點(diǎn)。在板料壓扁過程中,根據(jù)零件的尺寸和形變,凸模上會被施加非常高的壓力,可能導(dǎo)致過載,從而造成模具開裂或者產(chǎn)生疲勞裂紋。由于現(xiàn)存的壓扁經(jīng)驗(yàn)公式的誤差較大,針對板料壓扁成形力大的特點(diǎn),為了獲取準(zhǔn)確的壓扁力公式,為了模具設(shè)計(jì)和壓力機(jī)選型展開以下研究。首先,根據(jù)零件和模具的幾何特點(diǎn)對板料壓扁進(jìn)行分類和特點(diǎn)分析,運(yùn)用有限元軟件deform對實(shí)心板、空心板、外環(huán)局部板和內(nèi)環(huán)局部板壓扁過程中的速度場,應(yīng)力場,應(yīng)變場進(jìn)行了分析,一方面得到板料壓扁工藝中金屬材料流動的規(guī)律特征,另一方面獲得板料壓扁材料中的應(yīng)力和應(yīng)變分布以及擴(kuò)展規(guī)律。其次,采用正交實(shí)驗(yàn)方法,以實(shí)心板料壓扁成形力為對象,對材料、直徑、厚度以及摩擦系數(shù)四個(gè)影響因素進(jìn)行重要性分析,隨后采用控制變量法進(jìn)行各個(gè)因素的單一分析,得出各個(gè)因素對成形力的影響規(guī)律,為壓扁力公式的提出奠定基礎(chǔ)。通過對棒料鐓粗成形力、閉式模鍛的變形抗力和摩擦力、壓扁力經(jīng)驗(yàn)公式的研究以及結(jié)合板料壓扁本身特點(diǎn)提出實(shí)心和空心板料壓扁成形力的數(shù)學(xué)模型,經(jīng)過模擬反推得出關(guān)鍵系數(shù)m,結(jié)合工藝試驗(yàn)進(jìn)行驗(yàn)證對系數(shù)m進(jìn)行修正;對于內(nèi)環(huán)局部壓扁和外環(huán)局部壓扁采用剪切力加上墩壓力的方法計(jì)算得出。最后,通過MATLAB對于20鋼的流動應(yīng)力曲線進(jìn)行擬合,以此來計(jì)算一次能夠下壓的壓扁量最大值,進(jìn)而針對零件要求計(jì)算壓扁次數(shù);針對壓扁力大的問題,根據(jù)零件的幾何特征采取合適的分流降壓措施,并對分流降壓進(jìn)行了分析比較;結(jié)合磁盤架對壓扁在精沖壓扁復(fù)合成形中的應(yīng)用進(jìn)行工藝分析。主要工作包括:板料壓扁特征分析,速度場等各種場量結(jié)果分析,壓扁力的影響因素重要性排序以及數(shù)學(xué)模型構(gòu)建,進(jìn)行物理實(shí)驗(yàn)修正以及精沖壓扁復(fù)合成形工藝研究。以上研究成果具有一定的科研價(jià)值和工程意義,為板料壓扁在精沖壓扁復(fù)合成形提供一定意義的技術(shù)指導(dǎo)。
[Abstract]:Sheet metal flattening is a process that integrates the characteristics of bulk forming and sheet metal forming. On the one hand, it has the three-dimensional characteristics of volume forming, that is, thickness difference, on the other hand, the action object is thin sheet metal, which can save materials. Strengthen the characteristics of matrix. In the process of sheet metal flattening, according to the size and deformation of the parts, the punch will be subjected to very high pressure, which may lead to overload, which may lead to die cracking or fatigue crack. Due to the large error of the existing flattening empirical formula, in order to obtain the accurate flattening force formula, die design and press type selection, the following research is carried out in view of the characteristics of the sheet metal flattening forming force. Firstly, according to the geometric characteristics of parts and dies, the flattening of sheet metal is classified and analyzed. The velocity field and stress field of solid plate, hollow plate, outer ring local plate and inner ring local plate are analyzed by using finite element software deform. On the one hand, the characteristics of metal material flow in sheet metal flattening process are obtained; on the other hand, the stress and strain distribution and propagation law in sheet metal flattening material are obtained. Secondly, the importance of four factors, such as material, diameter, thickness and friction coefficient, is analyzed by orthogonal experiment method, and the single analysis of each factor is carried out by controlling variable method. The influence of various factors on forming force is obtained, which lays a foundation for the formulation of flattening force. Based on the research of the forging force of bar, the deformation resistance and friction force of closed die forging, the empirical formula of flattening force and combining with the characteristics of sheet metal flattening, the mathematical model of solid and hollow sheet flattening forming force is put forward. The key coefficient m is obtained by the simulation and back extrapolation, and the coefficient m is corrected by the process test. The method of shear force and pier pressure is used to calculate the local flattening of the inner ring and the local flattening of the outer ring. Finally, the flow stress curve of steel 20 is fitted by MATLAB to calculate the maximum flattening amount which can be pressed at a time, and then to calculate the flattening times according to the requirements of the parts, and to solve the problem of large flattening force. According to the geometric characteristics of the parts, appropriate measures of shunt pressure reduction are adopted, and the shunt pressure reduction is analyzed and compared, and the application of flattening in the fine punching flattening composite forming is analyzed in combination with the disk frame. The main work includes: analysis of flattening characteristics of sheet metal, analysis of the results of various fields such as velocity field, ranking of influencing factors of flattening force and construction of mathematical model, modification of physical experiments and research on the process of fine blanking flattening composite forming. The above research results have certain scientific research value and engineering significance, and provide some significant technical guidance for sheet metal flattening in fine punching flattening composite forming.
【學(xué)位授予單位】：重慶理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG306

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本文編號：1994274