平压平模切机模切有限元分析及实验研究 320.docx

1、平压平模切机模切有限元分析及实验研究 320Chinese library classification number: TS803The Research of Finite Element Analysis and Experiment on Die Cutting Process in the Platen Die-cutting MachineAbstract：The research object is the die-cutting equipment, the die-cutting pressure production mechanism and influence fact

2、ors were studied in depth. The method of combining the die cutting process components finite element analysis with experiment is proposed. The deformation for the die-cutting process parts including cardboard, blade line and sponge rubber strip was analyzed by finite element method, and the mechanic

3、al characteristics of various components were obtained. The die-cutting pressure test workbench developed in BIGC digital manufacturing laboratory adopts pneumatic and hydraulic driven system and determines the die cutting pressure through the oil pressure value, the relationship between the die cut

4、ting pressure and process components parameters is obtained by experimental analysis. Comparing the simulation results with the experimental results, it is proved that the simulation results can reveal the real die cutting pressure value basically, but it still need further analysis to get the subtl

5、e factors that affect die cutting pressure to improve the accuracy of the simulation.Key Words：die-cutting machine; finite element method; pneumatic and hydraulic driven system; nonlinearity; experiment0 IntroductionIn printing and packaging industry, printing machine, die-cutting machine, laminatin

6、g machine, etc, as a complicated equipment, their key mechanisms are designed with an innovation method of virtual prototype gradually, they are relatively complex in both structure and operation process, so, to the model machine, dynamic simulation software is applied to analyze their statics, kine

7、matics and dynamics, then output displacement, velocity, acceleration and the analysis results of reaction curve, scope of prediction mechanism motion, collision detection, peak load and finite element calculation input load12 to shorten product development cycle, reduce the cost. For the whole inde

8、nting process in the die cutting, pressure control is a key point in the process of quality control. Due to the die cutting tools and cutting pressure by the pressure on the material physical properties and different die-cutting version of the performance impact cannot be neglected, the initial sett

9、ing pressure is difficult to set. As a reference, the die cutting pressure can be obtained by using the method of theoretical calculation, but in actual production, influenced by various factors, a non-ignorable deviation exists between the theoretical value and practical value. During the actual pr

10、oduction in the factory, it always takes a test method to determine the shearing force value on unit length, and then calculate the size of the die cutting pressure, the process cant improve the production efficiency, and has certain consumption on manpower and material resources at the same time. T

11、his paper presents a method combining the die cutting process components finite element analysis with experiment, analysis of mechanical characteristics for cardboard, blade line and sponge rubber strip under different working conditions respectively, the simulation results will be compared with the

12、 experimental results, by a further optimization of finite element analysis methods with the results, the mechanism of die cutting pressure will be refined. The method has a guiding significance in replacing actual production test method by finite element die cutting pressure simulation method, impr

13、oving the production efficiency and reducing production cost.1the theoretical basis 1.1 die-cutting creasing mechanism analysisDriven by the pressure mechanism, the lower platform of die cutting mechanism moves up and bumps into the upper platform, deformation will be produced on the cardboard place

14、d on the lower platform by the mould pressing of the indentation line and the upper blade line, the elastic deformation stage comes first, that is, print materials such as paper, the fiber and packing in the cardboard, etc. will have elastic deformation, and then enter the stage of formation damage

15、with the increase of indentation processing pressure, at this time, the increasing stress concentration near the steel blade and steel line makes the local destruction of internal fiber and packing paper, leading to the printing quality on the surface or cardboard indentation. For die cutting, the d

16、eformation does not end so far, but with the further increasing pressure, it enters the next stage of brittle failure phase, or calls the cut off stage, and will cut off the certain parts of the cardboard or print; after cut off the cardboard, blade collision with steel plate under the platform and

17、produce tiny deformation3. The main parts of the process includes upper and lower platform, pressure cutting institutions and templates, templates include indentation bottom die and bottom die steel, which placed on the lower platform. Pressure cutting institutions include die cutter base board, bla

18、de, indentation steel line, and sponge strip, which placed on the upper platform.The work resistance of the die cutting work, mainly from three aspects, on the one hand, with the increasing of mould pressing, the deformation of elastic strip increases, the resistance comes from the elastic reaction

19、of the deformed strip; The second aspect, in the process of loading, the resistance comes from the processing that indentation line made plastic indentation on the cardboard; The third aspect is in the loaded process, the resistance on the die cutting blade cutting cardboard and the pressure on the

20、platform deformation when die cutting blade has cut through the cardboard. The die cutting pressure is the total resistances from the three aspects in the die pressing process.Studying the theory of die cutting stress is helpful to get information such as the process model characteristics, physical

21、characteristics, deformation and dynamic process modeling, lay theoretical basis for the finite element solution.1.2 the finite element methodCutter line resistance and strip elastic reaction are two important factors of die cutting pressure, in order to analysis the mechanism that is produced by di

22、e cutting pressure in-depth, it is necessary to analyze the deformation of the knife line and the strip. The die cutting model of the components includes both characteristics, physical characteristics, and process condition, the stress data is used to describe process state. In the ANSYS finite elem

23、ent analysis software, LS-DYNA is a large nonlinear dynamic analysis program based on explicit, it can simulate all kinds of complicated geometrical nonlinearity in the real world (large displacement, large rotation and large strain), material nonlinear and contact nonlinear problem, especially suit

24、able for solving all kinds of nonlinear dynamic impact problem such as high-speed collision, explode and metal forming in two-dimensional or three-dimensional nonlinear structure. For example, Stanislaw Kut and Felikes Stachowicz establishes the finite element model for 2.0 4.0 mm sheet steel using

25、the theory of elastic-plastic strength 4 continuity, assumed to be isotropic materials, numerical simulation analysis draw a conclusion that bending in advance of semi-finished products is advantageous to the steel plate cutting quality4.Die cutting indentation process is a high-speed collision and

26、stamping forming process, the blade cut the cardboard, indentation line creasing the board, so the molding process can be simulated by LS-DYNA, and using explicit-implicit sequence to solve.LS-DYNA gives priority to Lagrange algorithm, including the ALE and Euler algorithm meanwhile, it gives priori

27、ty to nonlinear dynamic analysis and has static analysis capabilities at the same time, it gives priority to an explicit solution and possesses implicit solving function5.Implicit algorithmLS-DYNA implicit time integration doesnt consider the inertia effect(C and M), it calculates average accelerati

28、on and displacement at the time t+t:ut+t=K-1 （1-1）To the linear problem when K is linear, unconditional stability; large time step can be adopted. For the nonlinear problem, the solution can be made through a series of linear approximation (Newton-Raphson); requesting transposed nonlinear stiffness

29、matrix K; convergence need small time step; it cannot guarantee convergence to the highly nonlinear problem.Explicit algorithmLS-DYNA explicit time integration using the central difference method in time to the acceleration:at=M-1(-) （1-2）In the formula, is the external force and physical vector, is

30、 the internal force vector, it consists of the formula: Fint= （1-3）3 items of the formula in sequence are the current unit stress field equivalent nodal force, the sandglass resistance (to overcome the problem of the hourglass single-point gauss integral and introduction of viscous resistance) and t

31、he contact force vector. Speed and displacement of the node can be achieved by the formula:vt+t/2=vt-t/2+attt （1-4）ut+t=vt+vt+t/2tt+t/2 （1-5）In the formula tt+t/2=0.5(tt+tt+t)，tt-t/2=0.5(tt-tt+t)；New geometric configurations obtained by initial configuration plus displacement increment, namely:xt+t=

32、x0+ut+t （1-6）In this paper, explicit dynamic module in ANSYS WorkbenchExplicit Dynamics (ANSYS), and the transient dynamic module (Transient Structural) are used to analyze the deformation of papers, cutter lines, and sponge strips. The elastic deformation of the cardboard can be ignored, and the material can be regarded as a rigid-plastic body6, the relationship between the elastic zone and the plastic area neednt to be considered, rigid-plastic finite element analysis is adopted in the process. Blade line and steel plates collision process can be sim