基于伺服驱动机械压力机的静音冲裁工艺研究
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摘要
冲裁是最重要的冲压工艺之一，它不仅可作为其它复杂冲压加工的准备工序，还可以直接获得具有一定精度要求的制件。由于在板料的冲裁加工过程中，变形集中在很小的区域内，且以断裂方式告终，使得其研究存在很多困难。而且由于冲裁大多在普通曲柄压力机上进行，冲压设备运动特性的局限性，运动特性固定，不能改变，迄今为止，对于冲裁工艺的研究主要集中在模具结构、工艺参数等方面，针对压力机滑块运动特性对冲裁过程影响的研究尚未见报道。
板料的冲裁过程是随着板料的断裂分离而结束，因此，冲裁过程中积蓄在压力机机身的弹性变形能随断裂的产生而瞬时释放，引起压力机强烈的振动，产生较大的噪音和对模具以及设备的损坏。目前，对冲压生产中的噪音治理主要采用消极减振的方法，如在压力机底座与基础之间安装减振元件，这虽然将振动与基础隔离，可以减少部分振动和噪音，但是它不能从根本上消除振动和噪音。本世纪初始，一种新型的压力机—伺服压力机的出现，为解决这一问题带来了新的希望。这种压力机由交流伺服电机驱动，滑块运动特性可任意调节，通过调节压力机滑块特性来改变冲裁过程积蓄在压力机机身的弹性变形能量的释放时间，使变形能在材料冲断之前就基本释放完毕，从而最大限度地减轻压力机冲裁引起的振动，从根本上解决冲裁振动问题，有可能实现静音冲裁，称之为主动减振法。
本文从金属板料冲裁加工过程的基础理论出发，分析了板料冲裁加工过程中的塑性变形和断裂过程、研究其数学模型以及采用有限元法求解的具体方法，重点研究了网格重划、断裂问题的处理以及不同冲裁工艺参数对板料断裂的影响等。
应用Deform-2D商业有限元分析软件，用Normal Cockrott & Latham断裂准则，对不同厚度的板料冲裁过程进行模拟计算，获得冲裁过程各阶段应力、应变状态，冲裁工艺参数对板料裂纹产生及断裂位置的影响，以及整个过程冲裁力的变化，可作为减轻冲裁振动、降低冲裁噪声的基础。
按照课题组自行研制的80吨伺服精密螺旋压力机的结构，建立了压力机冲裁受力的数学模型。采用Matlab/Simulink对冲裁过程进行数值仿真的方法，对不同滑块运动特性曲线冲裁时冲头的运动进行仿真，由冲断时冲头的振动幅值和振荡次数可以判别振动的大小。
按照在冲断前降低冲头速度，释放弹性能的思路，设计了多种滑块的运动曲线，以期获得最佳的减振效果，以减速起始点和减速幅度为优化变量，振动幅值最小为目标进行优化，获得了一定材料和板厚的最佳减振工艺参数。仿真表明，按照最佳工艺进行冲裁，振幅可较匀速冲裁降低70％以上，可以基本实现静音冲裁。
Blanking is one of the most important stamping processes, not only can it be the preparation for the complex stamping, but also it can get work pieces with a certain accuracy directly. There are lots of difficulties to study sheet metal blanking process since the deformation is limited in a tiny area of sheet metal and ends with fracture. Moreover, as most blanking works on traditional crank presses, along with the fixed dynamic characteristics, and the limitation of the movement characteristics with stamping equipments, the studies on blanking focused chiefly on die structure, craft parameters and so on while the study about the effect of dynamic characteristics of slide on the blanking process is unreported.
Sheet metal blanking ends with the fracture, and thus the elastic energy accumulated in the press body releases with the fracture, bringing severe vibration, great noise and damage to the die and equipments. Up to now, passive damping, for example adding vibration-reducing components between the press base and the ground, has mainly been adopted to deal with the noise generated by stamping process. Though this method separates the vibration from the ground so as to partially reduce the vibration and noise, it fails to eliminate the noise completely. Ever since the early beginning of this century, servo presses has come out and brought us hope to solve this problem. The presses are driven by AC servo electric motors, and the dynamic characteristics of the slide can be adjusted freely. The releasing time of elastic energy accumulated during the blanking could be altered to guarantee the elastic energy to be completely released before the fracture so as to reduce the vibration maximally, realizing silence blanking. This method could be called active vibration reducing.
Starting from the finite element theories of sheet metal blanking, this thesis analyzes its plastic deformation, fracture process, mathematical model and the finite element method. It emphasizes on grid remeshing, dealing with fracture problems and different blanking parameters' effects on metal sheet fracture.
Deform-2D is used to simulate blanking process of sheet metal with different thicknesses according to the Normal Cockroft & Latham fracture principle. The stress and strain distribution, blanking parameters' effects on the crack and the force-stroke curve of the entire blanking process are obtained, setting a foundation for reducing blanking vibration and lowering blanking noises.
According to the structure of the 80t screw coining press designed by our group, the mathematical model of blanking is made. The numerical simulation model based on Matlab/Simulink software is set up, and series simulations of blanking process are carried out. The press vibration can be judged based on the amplitudes and vibration times.
According to the idea that lowering the velocity of the ram before the fracture to release the elastic energy, many types of dynamic curves are designed to attain a best vibration effect. By improving with minimum vibration as target, speed reducing spot and velocity reducing amplitude as varies, the best vibration reducing craft parameters of certain sheet metal with different depth is approached. The simulation reveals that blanking with the best blanking craft, more than 70% vibration is reduced compared to blanking at a fixed velocity and silent blanking can basically realize.
板料的冲裁过程是随着板料的断裂分离而结束，因此，冲裁过程中积蓄在压力机机身的弹性变形能随断裂的产生而瞬时释放，引起压力机强烈的振动，产生较大的噪音和对模具以及设备的损坏。目前，对冲压生产中的噪音治理主要采用消极减振的方法，如在压力机底座与基础之间安装减振元件，这虽然将振动与基础隔离，可以减少部分振动和噪音，但是它不能从根本上消除振动和噪音。本世纪初始，一种新型的压力机—伺服压力机的出现，为解决这一问题带来了新的希望。这种压力机由交流伺服电机驱动，滑块运动特性可任意调节，通过调节压力机滑块特性来改变冲裁过程积蓄在压力机机身的弹性变形能量的释放时间，使变形能在材料冲断之前就基本释放完毕，从而最大限度地减轻压力机冲裁引起的振动，从根本上解决冲裁振动问题，有可能实现静音冲裁，称之为主动减振法。
本文从金属板料冲裁加工过程的基础理论出发，分析了板料冲裁加工过程中的塑性变形和断裂过程、研究其数学模型以及采用有限元法求解的具体方法，重点研究了网格重划、断裂问题的处理以及不同冲裁工艺参数对板料断裂的影响等。
应用Deform-2D商业有限元分析软件，用Normal Cockrott & Latham断裂准则，对不同厚度的板料冲裁过程进行模拟计算，获得冲裁过程各阶段应力、应变状态，冲裁工艺参数对板料裂纹产生及断裂位置的影响，以及整个过程冲裁力的变化，可作为减轻冲裁振动、降低冲裁噪声的基础。
按照课题组自行研制的80吨伺服精密螺旋压力机的结构，建立了压力机冲裁受力的数学模型。采用Matlab/Simulink对冲裁过程进行数值仿真的方法，对不同滑块运动特性曲线冲裁时冲头的运动进行仿真，由冲断时冲头的振动幅值和振荡次数可以判别振动的大小。
按照在冲断前降低冲头速度，释放弹性能的思路，设计了多种滑块的运动曲线，以期获得最佳的减振效果，以减速起始点和减速幅度为优化变量，振动幅值最小为目标进行优化，获得了一定材料和板厚的最佳减振工艺参数。仿真表明，按照最佳工艺进行冲裁，振幅可较匀速冲裁降低70％以上，可以基本实现静音冲裁。
Blanking is one of the most important stamping processes, not only can it be the preparation for the complex stamping, but also it can get work pieces with a certain accuracy directly. There are lots of difficulties to study sheet metal blanking process since the deformation is limited in a tiny area of sheet metal and ends with fracture. Moreover, as most blanking works on traditional crank presses, along with the fixed dynamic characteristics, and the limitation of the movement characteristics with stamping equipments, the studies on blanking focused chiefly on die structure, craft parameters and so on while the study about the effect of dynamic characteristics of slide on the blanking process is unreported.
Sheet metal blanking ends with the fracture, and thus the elastic energy accumulated in the press body releases with the fracture, bringing severe vibration, great noise and damage to the die and equipments. Up to now, passive damping, for example adding vibration-reducing components between the press base and the ground, has mainly been adopted to deal with the noise generated by stamping process. Though this method separates the vibration from the ground so as to partially reduce the vibration and noise, it fails to eliminate the noise completely. Ever since the early beginning of this century, servo presses has come out and brought us hope to solve this problem. The presses are driven by AC servo electric motors, and the dynamic characteristics of the slide can be adjusted freely. The releasing time of elastic energy accumulated during the blanking could be altered to guarantee the elastic energy to be completely released before the fracture so as to reduce the vibration maximally, realizing silence blanking. This method could be called active vibration reducing.
Starting from the finite element theories of sheet metal blanking, this thesis analyzes its plastic deformation, fracture process, mathematical model and the finite element method. It emphasizes on grid remeshing, dealing with fracture problems and different blanking parameters' effects on metal sheet fracture.
Deform-2D is used to simulate blanking process of sheet metal with different thicknesses according to the Normal Cockroft & Latham fracture principle. The stress and strain distribution, blanking parameters' effects on the crack and the force-stroke curve of the entire blanking process are obtained, setting a foundation for reducing blanking vibration and lowering blanking noises.
According to the structure of the 80t screw coining press designed by our group, the mathematical model of blanking is made. The numerical simulation model based on Matlab/Simulink software is set up, and series simulations of blanking process are carried out. The press vibration can be judged based on the amplitudes and vibration times.
According to the idea that lowering the velocity of the ram before the fracture to release the elastic energy, many types of dynamic curves are designed to attain a best vibration effect. By improving with minimum vibration as target, speed reducing spot and velocity reducing amplitude as varies, the best vibration reducing craft parameters of certain sheet metal with different depth is approached. The simulation reveals that blanking with the best blanking craft, more than 70% vibration is reduced compared to blanking at a fixed velocity and silent blanking can basically realize.
引文
[1]李硕本．冲压工艺学．北京：机械工业出版社．1982：28
[2]方刚、曾攀．金属板料冲裁过程的有限元模拟．金属学报，2001．6：653-654
[3]李硕本．冲压工艺理论与新技术．北京：机械工业出版社．2002．11
[4]Post J, Voncken R M J, 1n: Kals H J J, Ed., Proceedings of Fourth International Conference on Sheet Metal. the Netherlands, University of Twente, April 1996: 631
[5]Abdali A, Benkrid K, Bussy P. In: Shen S F, Dawson P REds., Simulation of Materials Processing:Theory, Methods and Applications. NUMIFORM'95, Balkema, Rotterdam, 1995:807
[6]陈威、陈维民、刘钢．冲裁液压缓冲降噪实验研究．噪声与振动控制．1999．4：23-25
[7]南建平．冲床的噪声及控制．鄂州大学学报．2005．5：70-72
[8]孙友松、张宏超．金属板材加工设备发展新动向．锻压技术．2004(4)：1-4
[9]Dennis Boerger, Servo Driven Mechanical Presses,http://www.aida-america.com
[10]孙友松、周先辉、黄开胜等．交流伺服电机驱动—成形装备发展的新方向．锻压技术，2005年增刊
[11]C. F Noble, P L. B. Oxley. Crack Formation in Blanking And Piercing. The Int. J. Prod. Res. 1963,2:265—274
[12]S. Fukui, K. Konda, K.Maeda. Smooth Shearing by Stepped Profile Tool. Ann. CIRP20,1971:57—58
[13]Q. Zhou, T. Wierzbicki. A Tension Zone Model of Blanking And Tearing of Ductile Metal Plates, Int. J. Mech. Sci. 1996,38:303-324
[14]梁炳文等．冲裁力学与工艺的研究(一)．锻压技术．1982(4)：1～10
[15]卢险峰．冲裁变形过程控制．板材先进制造技术研讨会论文集．2000．8：6～11
[16]卢险峰．冲裁变形过程及其力的计算．科学通报．1991，36(7)：555～556
[17]揭小平、卢险峰．两步法冲裁降低冲裁噪声的实验研究．冲压加工技术最新进展．南昌：江西高校出版社，1998，6：66～69
[18]吴永东、卢险峰．两步法冲裁降低噪声再研究．第七届锻压学术年会论文集．北京：航空工业出版社，1999，11：343～350
[19]吴永东．冲裁噪声规律的模拟及实验研究[硕士学位论文]．南昌：南昌大学，2000．5
[20]王孝培主编．冲压设计资料．北京：机械工业出版社，1983
[21]肖景荣、姜奎华主编．冲压工艺学．北京：机械工业出版社，1999
[22]Rice J R, Tracey D M. On The Ductile Enlargement Of Voids In Triaxial Stress Fields, J. Mech. Phys. Solids. 1969,17:201-207
[23]王勖成、邵民．有限单元法基本原理与数值方法．清华大学出版社，1988
[24]谢水生、王祖堂．金属塑性成形工步的有限元数值模拟．北京：冶金工业出版社，1997
[25]康凤．厚板冲裁过程的模拟仿真及参数优化[硕士学位论文]．重庆大学．2005．5
[26]方刚、雷丽萍等．金属塑性成形过程延性断裂的准则及其数值模拟．机械工程学报，2002．12：21-24
[27]林新波．DEFORM-2D和DEFORM-3DCAE软件在模拟金属塑性变形过程中的应用．模具技术，2000(3)：75-80
[28]周朝辉、曹海桥、吉卫、何大钧、王孝培．DEFORM有限元分析系统软件及其应用．热加工工艺．2003(4)：51-52
[29]Clift L.Hartley P, Sturgess CEN, Rowe GW. Fracture prediction in plastic deformation process. International Journal of Mechanical Sciences 1990; 1-17
[30]Ridha Hambli, Marian Reszka. Fracture Criteria Identification Using An Inverse Technique Method And Blanking Experiment. 2002,4 1349—1361
[31]Faura F, Garcia A,Estrems M. Finite Element Analysis Of Optimum Clearance In The Blanking Process. J. Of Material Processing Technology. 1998 121-125
[32]秦泗吉．板材剪切与冲裁加工过程有限元模拟与实验研究[博士学位论文]．燕山大学，2001．7
[33]周杰，孙新岭等．金属塑性成形有限元模拟中材料的体积变化．模具技术， 2001.1: 14-16
[34]Oh S I, Chen C C, Kobayashi S. Ductile Fractv}re in Aaisymmetric Extrusion and Drawing, Trans of the ASME,J of Engineering for Industry, 1979: 101:36
[35]陈先宝、王卫卫、王静．闭式压力机冲裁过程中的振动分析．太原重型机械学院学报1995(1)：52～56
[36]蔺海鸥．高速压力机的振动研究及计算机仿真[硕士学位论文]．西安理工大学，2005．03
[37]傅志杰．振动模态分析与参数辨识．北京：北京工业出版社，1990
[38]王沫然．Simulink4建模及动态仿真．北京：电子工业出版社，2002．1
[39]C．F．比尔兹著．朱世杰、陈玉琼译．结构振动分析．北京：中国铁道出版社，1988
[40]刘瑞叶、任洪林、李志民编著．计算机仿真技术基础．北京：电子工业出版社，2004
[41]李颖、朱伯立、张威．Simulink动态系统建模与仿真基础．西安：电子科技大学出版社，2004
[2]方刚、曾攀．金属板料冲裁过程的有限元模拟．金属学报，2001．6：653-654
[3]李硕本．冲压工艺理论与新技术．北京：机械工业出版社．2002．11
[4]Post J, Voncken R M J, 1n: Kals H J J, Ed., Proceedings of Fourth International Conference on Sheet Metal. the Netherlands, University of Twente, April 1996: 631
[5]Abdali A, Benkrid K, Bussy P. In: Shen S F, Dawson P REds., Simulation of Materials Processing:Theory, Methods and Applications. NUMIFORM'95, Balkema, Rotterdam, 1995:807
[6]陈威、陈维民、刘钢．冲裁液压缓冲降噪实验研究．噪声与振动控制．1999．4：23-25
[7]南建平．冲床的噪声及控制．鄂州大学学报．2005．5：70-72
[8]孙友松、张宏超．金属板材加工设备发展新动向．锻压技术．2004(4)：1-4
[9]Dennis Boerger, Servo Driven Mechanical Presses,http://www.aida-america.com
[10]孙友松、周先辉、黄开胜等．交流伺服电机驱动—成形装备发展的新方向．锻压技术，2005年增刊
[11]C. F Noble, P L. B. Oxley. Crack Formation in Blanking And Piercing. The Int. J. Prod. Res. 1963,2:265—274
[12]S. Fukui, K. Konda, K.Maeda. Smooth Shearing by Stepped Profile Tool. Ann. CIRP20,1971:57—58
[13]Q. Zhou, T. Wierzbicki. A Tension Zone Model of Blanking And Tearing of Ductile Metal Plates, Int. J. Mech. Sci. 1996,38:303-324
[14]梁炳文等．冲裁力学与工艺的研究(一)．锻压技术．1982(4)：1～10
[15]卢险峰．冲裁变形过程控制．板材先进制造技术研讨会论文集．2000．8：6～11
[16]卢险峰．冲裁变形过程及其力的计算．科学通报．1991，36(7)：555～556
[17]揭小平、卢险峰．两步法冲裁降低冲裁噪声的实验研究．冲压加工技术最新进展．南昌：江西高校出版社，1998，6：66～69
[18]吴永东、卢险峰．两步法冲裁降低噪声再研究．第七届锻压学术年会论文集．北京：航空工业出版社，1999，11：343～350
[19]吴永东．冲裁噪声规律的模拟及实验研究[硕士学位论文]．南昌：南昌大学，2000．5
[20]王孝培主编．冲压设计资料．北京：机械工业出版社，1983
[21]肖景荣、姜奎华主编．冲压工艺学．北京：机械工业出版社，1999
[22]Rice J R, Tracey D M. On The Ductile Enlargement Of Voids In Triaxial Stress Fields, J. Mech. Phys. Solids. 1969,17:201-207
[23]王勖成、邵民．有限单元法基本原理与数值方法．清华大学出版社，1988
[24]谢水生、王祖堂．金属塑性成形工步的有限元数值模拟．北京：冶金工业出版社，1997
[25]康凤．厚板冲裁过程的模拟仿真及参数优化[硕士学位论文]．重庆大学．2005．5
[26]方刚、雷丽萍等．金属塑性成形过程延性断裂的准则及其数值模拟．机械工程学报，2002．12：21-24
[27]林新波．DEFORM-2D和DEFORM-3DCAE软件在模拟金属塑性变形过程中的应用．模具技术，2000(3)：75-80
[28]周朝辉、曹海桥、吉卫、何大钧、王孝培．DEFORM有限元分析系统软件及其应用．热加工工艺．2003(4)：51-52
[29]Clift L.Hartley P, Sturgess CEN, Rowe GW. Fracture prediction in plastic deformation process. International Journal of Mechanical Sciences 1990; 1-17
[30]Ridha Hambli, Marian Reszka. Fracture Criteria Identification Using An Inverse Technique Method And Blanking Experiment. 2002,4 1349—1361
[31]Faura F, Garcia A,Estrems M. Finite Element Analysis Of Optimum Clearance In The Blanking Process. J. Of Material Processing Technology. 1998 121-125
[32]秦泗吉．板材剪切与冲裁加工过程有限元模拟与实验研究[博士学位论文]．燕山大学，2001．7
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