鋁型材柔性三維拉彎回彈預(yù)測(cè)及工藝優(yōu)化
發(fā)布時(shí)間：2019-04-02 21:18
【摘要】：隨著車輛輕量化和工業(yè)發(fā)展,傳統(tǒng)的鋁型材二維拉彎成形構(gòu)件己不能滿足工業(yè)需求,鋁型材三維拉彎成形構(gòu)件越來(lái)越受到關(guān)注。本文提出了一種新型柔性三維拉彎成形工藝,實(shí)現(xiàn)了快速重構(gòu)模具型面和加工多種截面型材。該成形工藝可進(jìn)行鋁型材三維彎曲的加工,且成形面可重構(gòu),能有效地縮短模具的設(shè)計(jì)、調(diào)試和生產(chǎn)的時(shí)間,從而提高生產(chǎn)效率。鋁型材的三維拉彎成形是一個(gè)復(fù)雜的力學(xué)過程,型材成形形狀難以精確控制,而且拉彎成形過程中構(gòu)件易出現(xiàn)回彈、起皺和破裂等成形缺陷。為了得到成形質(zhì)量較高的三維拉彎成形鋁型材構(gòu)件,需要對(duì)成形過程中的工藝參數(shù)進(jìn)行嚴(yán)格控制和優(yōu)化。本文對(duì)柔性三維拉彎成形工藝進(jìn)行了系統(tǒng)地研究,提出了回彈預(yù)測(cè)方法和工藝優(yōu)化方法。本文將拉彎工藝與多點(diǎn)成形思想進(jìn)行有機(jī)地結(jié)合,提出了一種新型三維拉彎成形工藝,該工藝將三維拉彎成形分解為水平彎曲和垂直彎曲。首先介紹了該工藝的成形原理、成形過程和關(guān)鍵部件柔性模具單元體的結(jié)構(gòu),并建立了柔性三維拉彎成形的有限元模型。研究?jī)?nèi)容包括模型簡(jiǎn)化、模擬算法選擇、材料本構(gòu)模型、單元選擇、接觸和摩擦處理以及邊界條件處理等問題,為后續(xù)的柔性三維拉彎成形工藝研究中有限元模擬部分提供理論依據(jù)�；貜検怯绊懤瓘澇尚喂に嚨淖畲箅y點(diǎn),針對(duì)三維拉彎成形工藝回彈的特點(diǎn),本文提出了采用支持向量回歸算法對(duì)三維拉彎成形回彈進(jìn)行預(yù)測(cè)的模型。目前人工神經(jīng)網(wǎng)絡(luò)是常用的回彈預(yù)測(cè)算法,支持向量回歸算法是一種與人工神經(jīng)網(wǎng)絡(luò)類似的機(jī)器學(xué)習(xí)方法,但是支持向量回歸算法的泛化能力高于神經(jīng)網(wǎng)絡(luò)算法。首先分析了彈性模量、屈服應(yīng)力、預(yù)拉量、補(bǔ)拉量、水平彎曲角和垂直彎曲角對(duì)回彈影響的規(guī)律。然后以這些參數(shù)作為輸入?yún)?shù),水平回彈角和垂直回彈角作為輸出參數(shù),分別采用支持向量回歸算法和人工神經(jīng)網(wǎng)絡(luò)算法建立了柔性三維拉彎成形的回彈預(yù)測(cè)模型。采用相同的樣本對(duì)兩個(gè)模型進(jìn)行訓(xùn)練和精度檢驗(yàn),證實(shí)了該模型預(yù)測(cè)精度高于人工神經(jīng)網(wǎng)絡(luò)模型。傳統(tǒng)的拉彎工藝成形過程中拉力保持不變,本文提出了三維拉彎成形過程中采用變拉力的方法,并以減小回彈為目標(biāo)建立了變拉力軌跡優(yōu)化模型。首先以復(fù)雜T型材為例分析了三維拉彎成形不同階段的應(yīng)力應(yīng)變狀態(tài),建立了力學(xué)分析模型。將拉力分為四個(gè)階段,預(yù)拉階段、水平拉彎階段、垂直拉彎階段和補(bǔ)拉階段,將各階段的拉力、預(yù)拉量以及補(bǔ)拉量作為設(shè)計(jì)變量,以回彈最小化為優(yōu)化目標(biāo)建立了變拉力優(yōu)化模型。優(yōu)化模型以型材最小減薄率和最大增厚率作為約束條件,用試驗(yàn)數(shù)據(jù)建立目標(biāo)函數(shù)和約束條件的響應(yīng)面代理模型,然后采用粒子群算法對(duì)不同階段的拉力大小進(jìn)行優(yōu)化。通過試驗(yàn)對(duì)優(yōu)化后的變拉力組合與未優(yōu)化的拉力組合成形后回彈進(jìn)行比較,證明優(yōu)化后的拉力軌跡可以有效地減小回彈。本文對(duì)矩形型材的三維拉彎成形進(jìn)行了研究,建立了其三維拉彎成形的多目標(biāo)優(yōu)化模型。由于矩形型材截面中空的特性,其三維拉彎成形過程中易出現(xiàn)截面凹陷的成形缺陷,本文提出了填充鋼塊抑制截面凹陷的方法。分析了預(yù)拉量和補(bǔ)拉量對(duì)截面凹陷影響的規(guī)律,發(fā)現(xiàn)增加預(yù)拉量和補(bǔ)拉量會(huì)引起截面凹陷增加,但增加預(yù)拉量和補(bǔ)拉量是減小回彈的主要方法。為了達(dá)到同時(shí)控制回彈和截面凹陷的目的,建立了矩形型材三維拉彎成形的多目標(biāo)優(yōu)化模型。該模型以預(yù)拉量和補(bǔ)拉量作為設(shè)計(jì)變量,以回彈最小化和截面凹陷最小化作為目標(biāo)函數(shù),以型材最小減薄率和最大增厚率作為約束條件。用多項(xiàng)式響應(yīng)面法建立目標(biāo)和約束的代理模型,用非支配遺傳算法對(duì)其進(jìn)行多目標(biāo)優(yōu)化,得到優(yōu)化解集,對(duì)解集進(jìn)行分析后選擇最優(yōu)解。優(yōu)化后的預(yù)拉量和補(bǔ)拉量組合能夠同時(shí)達(dá)到減小回彈和截面凹陷的目的。本文還提出了基于迭代回彈補(bǔ)償優(yōu)化柔性三維拉彎成形模具型面的方法。該方法以控制回彈為目的,根據(jù)回彈量大小對(duì)成形面進(jìn)行迭代補(bǔ)償,直到成形件的形狀偏差滿足要求。針對(duì)型材柔性三維拉彎成形特點(diǎn),提出了分段補(bǔ)償因子的概念,根據(jù)回彈大小對(duì)型材進(jìn)行分段,根據(jù)分段型材的回彈量分別采用不同的回彈補(bǔ)償因子。使用優(yōu)化后的模具型面進(jìn)行三維拉彎成形,可以極大地降低與目標(biāo)形狀的形狀偏差。
[Abstract]:With the light weight and industrial development of the vehicle, the traditional two-dimension drawing-forming component of the aluminum profile has not met the industrial demand, and the three-dimensional stretch-bending forming component of the aluminum profile is more and more concerned. In this paper, a new flexible three-dimensional drawing process is proposed, which realizes the rapid reconstruction of the profile of the mould and the processing of a variety of cross-sectional profiles. The forming process can be used for processing the three-dimensional bending of the aluminum section, and the forming surface can be reconstructed, so that the design, the debugging and the production time of the die can be effectively shortened, and the production efficiency is improved. The three-dimensional bending and forming of the aluminum profile is a complex mechanical process. The shape of the profile is difficult to control precisely. In order to obtain the three-dimensional drawing-forming aluminum profile component with high forming quality, the process parameters in the forming process need to be strictly controlled and optimized. In this paper, the flexible three-dimensional bending forming process is studied systematically, and the method of springback prediction and the process optimization method are put forward. In this paper, the pull-bending process and the multi-point forming idea are organically combined, and a new three-dimensional drawing-bending forming process is proposed, and the three-dimensional bending forming is decomposed into horizontal bending and vertical bending. First, the forming principle, forming process of the process and the structure of the flexible die unit of key parts are introduced, and the finite element model of flexible three-dimensional drawing and bending is established. The research contents include model simplification, simulation algorithm selection, material constitutive model, cell selection, contact and friction treatment and boundary condition treatment. The springback is the most difficult point to influence the bending forming process. In the light of the characteristics of the springback of the three-dimensional pull-bending forming process, this paper presents a model for predicting the springback of three-dimensional pull-bending forming by using the support vector regression algorithm. The artificial neural network is a common rebound prediction algorithm, and the support vector regression algorithm is a kind of machine learning method similar to that of the artificial neural network, but the generalization ability of the support vector regression algorithm is higher than that of the neural network algorithm. First, the law of elastic modulus, yield stress, pre-pull, pull-up, horizontal bending angle and vertical bending angle on springback is analyzed. Then, using these parameters as the input parameters, the horizontal rebound angle and the vertical rebound angle as the output parameters, the rebound prediction model of the flexible three-dimensional pull-bending formation is established by using the support vector regression algorithm and the artificial neural network algorithm, respectively. The two models were trained and verified with the same sample, and the prediction accuracy of the model was higher than that of the artificial neural network model. In the traditional drawing-bending process, the tension remains the same. In this paper, the method of changing the tension in the process of three-dimensional drawing and bending is put forward, and a variable-tension trajectory optimization model is set up with the aim of reducing the springback. First, the stress-strain state of three-dimensional pull-and-bending forming is analyzed by taking the complex T-section as an example, and the mechanical analysis model is established. The pulling force is divided into four stages, a pre-drawing stage, a horizontal pull-bending stage, a vertical pull-bending stage and a pull-up stage, and the pulling force, the pre-pulling amount and the pull-up amount of each stage are taken as a design variable, and a variable-tension optimization model is established for the optimization target by the rebound minimization. In this paper, the response surface agent model of the objective function and the constraint condition is established by using the test data as a constraint condition based on the minimum thinning rate and the maximum thickening rate of the profile, and then the size of the pulling force at different stages is optimized by the particle swarm algorithm. The result shows that the optimized tension combination can reduce the springback effectively by comparing the optimized tension combination with the unoptimized tension combination. In this paper, the three-dimensional bending and forming of the rectangular profile is studied, and the multi-objective optimization model for the three-dimensional bending formation is established. Due to the hollow character of the cross section of the rectangular section, the forming defect of the cross-section depression is easy to occur in the three-dimensional curve forming process, and the method of filling the steel block to suppress the cross-section depression is proposed. The influence of the amount of pre-drawing and the amount of pull-up on the depression of the cross-section is analyzed, and it is found that the increase of the amount of pre-drawing and the amount of pull-up can cause the increase of the cross-section depression, but the increase of the amount of pre-drawing and the amount of pull-up is the main method to reduce the rebound. In order to achieve the purpose of simultaneously controlling the springback and the cross-section depression, a multi-objective optimization model for the three-dimensional drawing and bending of the rectangular profile is established. The model takes the pre-draw amount and the pull-up amount as the design variable to minimize the rebound and minimize the cross-section depression as the objective function, and the minimum thinning rate and the maximum thickening rate of the profile are taken as the constraint conditions. The objective and constrained agent model is established by the polynomial response surface method, and the multi-objective optimization is carried out by the non-dominant genetic algorithm to obtain the optimized solution set, and the optimal solution is selected after the solution set is analyzed. The optimized pre-pulling amount and the pull-up amount combination can achieve the purpose of reducing the rebound and the cross-section depression at the same time. The invention also provides a method for optimizing the profile of a flexible three-dimensional pull-bending forming die based on the iterative rebound compensation. The method is used for controlling the rebound as the purpose, and the forming surface is subjected to iterative compensation according to the size of the rebound quantity until the shape deviation of the forming part meets the requirement. According to the characteristics of the flexible three-dimensional drawing and bending of the profile, the concept of the section compensation factor is put forward, and the sectional material is segmented according to the rebound size, and different rebound compensation factors are respectively used according to the springback amount of the sectional profile. The shape deviation of the target shape can be greatly reduced by using the optimized mold profile for three-dimensional drawing and bending.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG389
本文編號(hào)：2452929
[Abstract]:With the light weight and industrial development of the vehicle, the traditional two-dimension drawing-forming component of the aluminum profile has not met the industrial demand, and the three-dimensional stretch-bending forming component of the aluminum profile is more and more concerned. In this paper, a new flexible three-dimensional drawing process is proposed, which realizes the rapid reconstruction of the profile of the mould and the processing of a variety of cross-sectional profiles. The forming process can be used for processing the three-dimensional bending of the aluminum section, and the forming surface can be reconstructed, so that the design, the debugging and the production time of the die can be effectively shortened, and the production efficiency is improved. The three-dimensional bending and forming of the aluminum profile is a complex mechanical process. The shape of the profile is difficult to control precisely. In order to obtain the three-dimensional drawing-forming aluminum profile component with high forming quality, the process parameters in the forming process need to be strictly controlled and optimized. In this paper, the flexible three-dimensional bending forming process is studied systematically, and the method of springback prediction and the process optimization method are put forward. In this paper, the pull-bending process and the multi-point forming idea are organically combined, and a new three-dimensional drawing-bending forming process is proposed, and the three-dimensional bending forming is decomposed into horizontal bending and vertical bending. First, the forming principle, forming process of the process and the structure of the flexible die unit of key parts are introduced, and the finite element model of flexible three-dimensional drawing and bending is established. The research contents include model simplification, simulation algorithm selection, material constitutive model, cell selection, contact and friction treatment and boundary condition treatment. The springback is the most difficult point to influence the bending forming process. In the light of the characteristics of the springback of the three-dimensional pull-bending forming process, this paper presents a model for predicting the springback of three-dimensional pull-bending forming by using the support vector regression algorithm. The artificial neural network is a common rebound prediction algorithm, and the support vector regression algorithm is a kind of machine learning method similar to that of the artificial neural network, but the generalization ability of the support vector regression algorithm is higher than that of the neural network algorithm. First, the law of elastic modulus, yield stress, pre-pull, pull-up, horizontal bending angle and vertical bending angle on springback is analyzed. Then, using these parameters as the input parameters, the horizontal rebound angle and the vertical rebound angle as the output parameters, the rebound prediction model of the flexible three-dimensional pull-bending formation is established by using the support vector regression algorithm and the artificial neural network algorithm, respectively. The two models were trained and verified with the same sample, and the prediction accuracy of the model was higher than that of the artificial neural network model. In the traditional drawing-bending process, the tension remains the same. In this paper, the method of changing the tension in the process of three-dimensional drawing and bending is put forward, and a variable-tension trajectory optimization model is set up with the aim of reducing the springback. First, the stress-strain state of three-dimensional pull-and-bending forming is analyzed by taking the complex T-section as an example, and the mechanical analysis model is established. The pulling force is divided into four stages, a pre-drawing stage, a horizontal pull-bending stage, a vertical pull-bending stage and a pull-up stage, and the pulling force, the pre-pulling amount and the pull-up amount of each stage are taken as a design variable, and a variable-tension optimization model is established for the optimization target by the rebound minimization. In this paper, the response surface agent model of the objective function and the constraint condition is established by using the test data as a constraint condition based on the minimum thinning rate and the maximum thickening rate of the profile, and then the size of the pulling force at different stages is optimized by the particle swarm algorithm. The result shows that the optimized tension combination can reduce the springback effectively by comparing the optimized tension combination with the unoptimized tension combination. In this paper, the three-dimensional bending and forming of the rectangular profile is studied, and the multi-objective optimization model for the three-dimensional bending formation is established. Due to the hollow character of the cross section of the rectangular section, the forming defect of the cross-section depression is easy to occur in the three-dimensional curve forming process, and the method of filling the steel block to suppress the cross-section depression is proposed. The influence of the amount of pre-drawing and the amount of pull-up on the depression of the cross-section is analyzed, and it is found that the increase of the amount of pre-drawing and the amount of pull-up can cause the increase of the cross-section depression, but the increase of the amount of pre-drawing and the amount of pull-up is the main method to reduce the rebound. In order to achieve the purpose of simultaneously controlling the springback and the cross-section depression, a multi-objective optimization model for the three-dimensional drawing and bending of the rectangular profile is established. The model takes the pre-draw amount and the pull-up amount as the design variable to minimize the rebound and minimize the cross-section depression as the objective function, and the minimum thinning rate and the maximum thickening rate of the profile are taken as the constraint conditions. The objective and constrained agent model is established by the polynomial response surface method, and the multi-objective optimization is carried out by the non-dominant genetic algorithm to obtain the optimized solution set, and the optimal solution is selected after the solution set is analyzed. The optimized pre-pulling amount and the pull-up amount combination can achieve the purpose of reducing the rebound and the cross-section depression at the same time. The invention also provides a method for optimizing the profile of a flexible three-dimensional pull-bending forming die based on the iterative rebound compensation. The method is used for controlling the rebound as the purpose, and the forming surface is subjected to iterative compensation according to the size of the rebound quantity until the shape deviation of the forming part meets the requirement. According to the characteristics of the flexible three-dimensional drawing and bending of the profile, the concept of the section compensation factor is put forward, and the sectional material is segmented according to the rebound size, and different rebound compensation factors are respectively used according to the springback amount of the sectional profile. The shape deviation of the target shape can be greatly reduced by using the optimized mold profile for three-dimensional drawing and bending.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG389
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