曲面零件連續(xù)成形的理論與數(shù)值模擬研究及控制軟件開發(fā)
發(fā)布時間：2018-07-28 21:45
【摘要】：曲面零件具有質量輕、流線型好、承載能力強等特點，被廣泛應用于工業(yè)生產(chǎn)的各個領域。隨著經(jīng)濟的發(fā)展和社會的進步，對各種曲面件的需求開始從大批量單一產(chǎn)品向小批量或單件多樣化的產(chǎn)品轉變。模具成形是加工曲面零件的重要方法，但每一種零件都要開發(fā)相應的模具，并且模具的設計、調試周期長，尤其加工大型曲面件時，成形設備的體積大、制造成本高。因此，開展新的曲面件成形工藝研究具有重要的理論意義和實用價值。 卷板成形是一種傳統(tǒng)的連續(xù)成形方式，曲面連續(xù)成形將傳統(tǒng)卷板成形的直輥用可彎曲的柔性輥代替，形成一種快速、高效的板料加工技術，適用于不同形狀大型雙曲度曲面件的成形。目前，曲面連續(xù)成形工藝雖然已有一定的研究工作，但在板料連續(xù)成形理論、成形曲面件的精度、數(shù)值模擬的有限元模型及成形過程控制等方面還有許多亟待解決的問題，迫切需要進一步深入研究，提高工程應用價值，以融入到現(xiàn)代制造業(yè)的行列中。本文通過對連續(xù)成形過程中板料雙向彎曲變形的理論分析，建立了成形過程橫向與縱向形狀控制模型，并開發(fā)了成形過程控制軟件。 本文研究的主要內(nèi)容和結論如下： 1.根據(jù)板料連續(xù)成形的變形歷史，對連續(xù)成形過程提出了一種平板橫向彎曲與柱面縱向彎曲組合的曲面形成機制。板料連續(xù)成形時，在局部變形區(qū)先形成橫向曲率變?yōu)橹�，再由上輥下壓使柱面發(fā)生縱向彎曲變?yōu)殡p曲度曲面，并通過柔性輥滾動實現(xiàn)板料連續(xù)進給完成曲面件的成形。由此可見，曲面連續(xù)成形的最終曲率要綜合考慮單向彎曲回彈及橫向與縱向彎曲的相互影響�；谌N不同的材料模型，給出單向彎曲變形中彎矩與回彈比的計算公式。分析了連續(xù)成形過程中橫向與縱向彎曲的相互影響，結果表明：縱向成形的曲率越大，對橫向彎曲形成的附加彎矩越大，上輥下壓前后橫向曲率的變化值也就越大；橫向彎曲對縱向曲率的影響主要體現(xiàn)在截面形狀方面，不同的橫向曲率形成不同的橫截面形狀，縱向壓下量不變時在橫截面上產(chǎn)生的彎矩和慣性矩不同，使縱向彎曲的相對回彈比隨橫向曲率的減小呈指數(shù)遞減。 2.描述了不同曲面件的連續(xù)成形原理。根據(jù)成形曲面的掃略特性，給出成形曲面的數(shù)學描述形式�；跈M向回彈及縱向彎曲對橫向曲率的影響，對橫向目標截面線方程進行補償，得到上、下柔性輥的軸線方程及每個控制點的調形量，建立了橫向彎曲的形狀控制模型。分析縱向滾彎成形過程中柔性輥與板料接觸點和彎曲角的變化，，考慮縱向回彈和橫向曲率對縱向成形的影響，得到上輥下壓量與成形目標曲率的關系式，建立了縱向彎曲的形狀控制模型。采用本文建立的控制理論與方法進行數(shù)值模擬，成形的曲面件精度較高，驗證了該方法的有效性。 3.提出了一種連續(xù)柔性輥的有限元建模方法。連續(xù)柔性輥模型中接觸方式為光滑曲線接觸，避免壓痕產(chǎn)生，提高了成形件的表面質量；應力、應變分布更加均勻；成形曲面件的精度較高。對柔性輥調形過程進行有限元仿真，分析控制點數(shù)量對調形形狀及成形精度的影響，結果表明：控制點數(shù)量越多，調形形狀越接近于目標形狀，成形曲面件的精度也越高。給出了柔性輥調形誤差的補償方法，補償后成形曲面件的精度提高，驗證了補償方法的可行性。 4.分析了不同材料和板厚對柔性輥產(chǎn)生的作用力，結果表明：隨著彈性模量和屈服強度的增加，板料對柔性輥的作用力提高，隨著板厚的增加，對柔性輥的作用力也會增加，而且上輥受到的作用力要大于下輥。分析了材料性能、板厚、上輥下壓量、柔性輥形狀及下輥中心距對成形誤差的影響規(guī)律，結果表明：橫向與縱向成形誤差隨彈性模量的增加而減小；隨板厚的增加而減��；隨上輥壓下量的增加而減��；隨橫向曲率半徑的減小而減小；隨下輥中心距的增加而增大。給出了橫向與縱向彎曲的相互影響曲線，壓下量不變時，橫向曲率半徑增加，縱向曲率半徑有減小的趨勢；柔性輥形狀不變時，上輥壓下量增大，橫向曲率半徑增加。 5.基于給出的連續(xù)成形過程橫向與縱向的控制理論與方法，在VC++平臺開發(fā)了曲面連續(xù)成形過程的控制軟件。該軟件主要包括曲面造型模塊、工藝參數(shù)設置模塊、程序計算模塊及圖形顯示模塊。曲面造型模塊可以實現(xiàn)NURBS曲面重構；工藝參數(shù)設置模塊的功能是輸入設備參數(shù)、材料力學性能及板料尺寸；程序計算模塊能夠根據(jù)目標曲面橫向與縱向曲率，計算出上輥壓下量及柔性輥上每個控制點的調形量；圖形顯示模塊結合OpenGL庫函數(shù)，用來虛擬顯示曲面連續(xù)成形過程。 6.開發(fā)了連續(xù)成形過程的計算機控制系統(tǒng)。應用該系統(tǒng)成形典型曲面件并與數(shù)值模擬件進行對比，實驗結果與數(shù)值模擬結果吻合較好。采用數(shù)值模擬方法為部分正高斯曲率和負高斯曲率曲面件建立了控形數(shù)據(jù)庫。通過連續(xù)成形過程控制系統(tǒng)實現(xiàn)了不同類型曲面件的成形，以鞍面件和凸面件為目標曲面件，分析成形件表面質量和成形精度，結果證明曲面連續(xù)成形工藝加工的曲面件質量和精度都符合要求。
[Abstract]:With the characteristics of light quality, good streamline and strong bearing capacity, curved surface parts are widely used in various fields of industrial production. With the development of the economy and the progress of the society, the demand for various surface parts begins to change from a large quantity single product to a small batch or a single piece of diversified product. The mold forming is the important part of the processing of surface parts. Method, but each part should develop the corresponding mold, and the design of the mold, the long debugging period, especially when the large surface parts are processed, the size of the forming equipment is large and the manufacturing cost is high. Therefore, it is of great theoretical significance and practical value to carry out the research of the new forming process of the curved surface parts.
The roll forming is a traditional continuous forming method. The continuous forming of the curved surface is replaced by a flexible flexible roll formed by the traditional roll forming, forming a fast and efficient sheet metal processing technology, which is suitable for the forming of large hyperbolic surfaces with different shapes. There are still many problems to be solved in the continuous forming theory of sheet metal, the precision of forming surface parts, the finite element model of numerical simulation and the control of forming process. It is urgent to further study in order to improve the application value of the engineering, so as to integrate into the ranks of modern manufacturing. Based on the theoretical analysis of the deformation, a lateral and longitudinal shape control model is established, and the software for forming process control is developed.
The main contents and conclusions of this paper are as follows:
1. according to the deformation history of sheet metal continuous forming, a curved surface forming mechanism is proposed for the continuous forming process. In the continuous forming of the sheet, the transverse curvature is formed into a cylinder in the local deformation zone, and then the vertical bending of the cylinder becomes hyperbolic surface by the pressure of the upper roll, and the flexor is passed through the bending. It can be seen that the ultimate curvature of the continuous forming of the curved surface should take into account the mutual influence of the one-way bending rebound and the transverse and longitudinal bending. Based on three different material models, the calculation formula of the bending moment and the rebound ratio in the unidirectional bending deformation is given. The interaction between transverse and longitudinal bending shows that the greater the curvature of the longitudinal forming, the greater the additional bending moment formed by the transverse bending, the greater the change value of the transverse curvature before and after the pressure of the upper roll; the effect of the transverse curvature on the longitudinal curvature is mainly reflected in the shape of the cross section, and the different transverse curvature forms a different cross section. The bending moment and moment of inertia on the cross section are different when the shape of the plane is fixed and the longitudinal pressure is constant, so the relative rebound ratio of the longitudinal bending decreases exponentially with the decrease of the transverse curvature.
2. the continuous forming principle of different curved surfaces is described. Based on the scanning characteristics of the formed surface, the mathematical description of the forming surface is given. Based on the effect of the transverse springback and longitudinal bending on the transverse curvature, the equation of the cross section line is compensated, and the axis equation of the upper and lower flexible rolls and the adjustment of each control point are established. The shape control model of transverse bending is used to analyze the change of the contact point and bending angle of the flexible roll and the sheet in the process of the longitudinal roll forming, considering the influence of the longitudinal springback and the transverse curvature on the longitudinal forming, and the relationship between the pressure of the upper roll and the shape of the forming target is obtained, and the shape control model of the longitudinal bending is established. The theory and method are used for numerical simulation, and the accuracy of the curved surface parts is relatively high, which verifies the effectiveness of the method.
3. a finite element modeling method for continuous flexible roll is proposed. The contact mode of the continuous flexible roller model is smooth curve contact, avoiding the indentation, improving the surface quality of the forming parts; the stress, the strain distribution is even more uniform; the precision of the forming surface is high. The finite element simulation of the flexible roll profile process is carried out and the number of control points is analyzed. The effect of quantity on shape shape and forming precision shows that the more control points, the closer the shape of the shape to the shape of the target, the higher the precision of the forming surface. The compensation method for the adjustment error of the flexible roll is given. The accuracy of the formed curved surface is improved after the compensation, and the feasibility of the compensation method is verified.
4. the force produced by different material and plate thickness to the flexible roll is analyzed. The results show that with the increase of modulus of elasticity and yield strength, the force of the sheet to the flexible roller is increased. With the increase of the thickness of the plate, the force of the flexible roll will increase, and the action of the top roller is greater than the lower roller. The effect of down pressure, the shape of the flexible roll and the center distance of the lower roll on the forming error, the results show that the lateral and longitudinal forming error decreases with the increase of the modulus of elasticity, decreases with the increase of the thickness of the plate, decreases with the increase of the upper roll down and decreases with the decrease of the transverse curvature radius, and increases with the increase of the center distance of the lower roll. The interaction curve of transverse and longitudinal bending is given. When the pressure is constant, the radius of the transverse curvature increases and the longitudinal curvature radius decreases. When the shape of the flexible roll is constant, the amount of the upper roller is increased and the radius of the transverse curvature increases.
5. based on the lateral and longitudinal control theory and method of continuous forming process, the control software of curved surface forming process is developed on the VC++ platform. The software mainly includes surface modeling module, process parameter setting module, program calculation module and graphic display module. The surface modeling module can realize the reconstruction of NURBS surface; The function of the parameter setting module is the input device parameters, the material mechanics performance and the sheet size. The program calculation module can calculate the amount of upper roll down and the control point on each control point on the flexible roll according to the lateral and longitudinal curvature of the target surface. The graphics display module is used in combination with the OpenGL library function, which is used for the continuous forming of the virtual display surface. Cheng.
6. the computer control system of the continuous forming process is developed. The typical curved surface parts are formed and compared with the numerical simulation parts. The experimental results are in good agreement with the numerical simulation results. The control database is established for the partial positive Gauss curvature and the negative Gauss curvature surface parts by numerical simulation. The forming of different types of curved surface parts is realized. The surface parts of the saddle and convex surfaces are used as the target surface parts. The surface quality and forming precision of the formed parts are analyzed. The results show that the quality and accuracy of curved surface parts are all in accordance with the requirements.
【學位授予單位】：吉林大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TH164;TG306
本文編號：2151669
[Abstract]:With the characteristics of light quality, good streamline and strong bearing capacity, curved surface parts are widely used in various fields of industrial production. With the development of the economy and the progress of the society, the demand for various surface parts begins to change from a large quantity single product to a small batch or a single piece of diversified product. The mold forming is the important part of the processing of surface parts. Method, but each part should develop the corresponding mold, and the design of the mold, the long debugging period, especially when the large surface parts are processed, the size of the forming equipment is large and the manufacturing cost is high. Therefore, it is of great theoretical significance and practical value to carry out the research of the new forming process of the curved surface parts.
The roll forming is a traditional continuous forming method. The continuous forming of the curved surface is replaced by a flexible flexible roll formed by the traditional roll forming, forming a fast and efficient sheet metal processing technology, which is suitable for the forming of large hyperbolic surfaces with different shapes. There are still many problems to be solved in the continuous forming theory of sheet metal, the precision of forming surface parts, the finite element model of numerical simulation and the control of forming process. It is urgent to further study in order to improve the application value of the engineering, so as to integrate into the ranks of modern manufacturing. Based on the theoretical analysis of the deformation, a lateral and longitudinal shape control model is established, and the software for forming process control is developed.
The main contents and conclusions of this paper are as follows:
1. according to the deformation history of sheet metal continuous forming, a curved surface forming mechanism is proposed for the continuous forming process. In the continuous forming of the sheet, the transverse curvature is formed into a cylinder in the local deformation zone, and then the vertical bending of the cylinder becomes hyperbolic surface by the pressure of the upper roll, and the flexor is passed through the bending. It can be seen that the ultimate curvature of the continuous forming of the curved surface should take into account the mutual influence of the one-way bending rebound and the transverse and longitudinal bending. Based on three different material models, the calculation formula of the bending moment and the rebound ratio in the unidirectional bending deformation is given. The interaction between transverse and longitudinal bending shows that the greater the curvature of the longitudinal forming, the greater the additional bending moment formed by the transverse bending, the greater the change value of the transverse curvature before and after the pressure of the upper roll; the effect of the transverse curvature on the longitudinal curvature is mainly reflected in the shape of the cross section, and the different transverse curvature forms a different cross section. The bending moment and moment of inertia on the cross section are different when the shape of the plane is fixed and the longitudinal pressure is constant, so the relative rebound ratio of the longitudinal bending decreases exponentially with the decrease of the transverse curvature.
2. the continuous forming principle of different curved surfaces is described. Based on the scanning characteristics of the formed surface, the mathematical description of the forming surface is given. Based on the effect of the transverse springback and longitudinal bending on the transverse curvature, the equation of the cross section line is compensated, and the axis equation of the upper and lower flexible rolls and the adjustment of each control point are established. The shape control model of transverse bending is used to analyze the change of the contact point and bending angle of the flexible roll and the sheet in the process of the longitudinal roll forming, considering the influence of the longitudinal springback and the transverse curvature on the longitudinal forming, and the relationship between the pressure of the upper roll and the shape of the forming target is obtained, and the shape control model of the longitudinal bending is established. The theory and method are used for numerical simulation, and the accuracy of the curved surface parts is relatively high, which verifies the effectiveness of the method.
3. a finite element modeling method for continuous flexible roll is proposed. The contact mode of the continuous flexible roller model is smooth curve contact, avoiding the indentation, improving the surface quality of the forming parts; the stress, the strain distribution is even more uniform; the precision of the forming surface is high. The finite element simulation of the flexible roll profile process is carried out and the number of control points is analyzed. The effect of quantity on shape shape and forming precision shows that the more control points, the closer the shape of the shape to the shape of the target, the higher the precision of the forming surface. The compensation method for the adjustment error of the flexible roll is given. The accuracy of the formed curved surface is improved after the compensation, and the feasibility of the compensation method is verified.
4. the force produced by different material and plate thickness to the flexible roll is analyzed. The results show that with the increase of modulus of elasticity and yield strength, the force of the sheet to the flexible roller is increased. With the increase of the thickness of the plate, the force of the flexible roll will increase, and the action of the top roller is greater than the lower roller. The effect of down pressure, the shape of the flexible roll and the center distance of the lower roll on the forming error, the results show that the lateral and longitudinal forming error decreases with the increase of the modulus of elasticity, decreases with the increase of the thickness of the plate, decreases with the increase of the upper roll down and decreases with the decrease of the transverse curvature radius, and increases with the increase of the center distance of the lower roll. The interaction curve of transverse and longitudinal bending is given. When the pressure is constant, the radius of the transverse curvature increases and the longitudinal curvature radius decreases. When the shape of the flexible roll is constant, the amount of the upper roller is increased and the radius of the transverse curvature increases.
5. based on the lateral and longitudinal control theory and method of continuous forming process, the control software of curved surface forming process is developed on the VC++ platform. The software mainly includes surface modeling module, process parameter setting module, program calculation module and graphic display module. The surface modeling module can realize the reconstruction of NURBS surface; The function of the parameter setting module is the input device parameters, the material mechanics performance and the sheet size. The program calculation module can calculate the amount of upper roll down and the control point on each control point on the flexible roll according to the lateral and longitudinal curvature of the target surface. The graphics display module is used in combination with the OpenGL library function, which is used for the continuous forming of the virtual display surface. Cheng.
6. the computer control system of the continuous forming process is developed. The typical curved surface parts are formed and compared with the numerical simulation parts. The experimental results are in good agreement with the numerical simulation results. The control database is established for the partial positive Gauss curvature and the negative Gauss curvature surface parts by numerical simulation. The forming of different types of curved surface parts is realized. The surface parts of the saddle and convex surfaces are used as the target surface parts. The surface quality and forming precision of the formed parts are analyzed. The results show that the quality and accuracy of curved surface parts are all in accordance with the requirements.
【學位授予單位】：吉林大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TH164;TG306
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