| Fine-blanking is an advanced sheet metal forming process,which is widely used in the manufacturing of various products such as automobile,electronic,and military industry etc.In recent years,the sizes of fine-blanking products have developed from small to large,the shapes from simple to complex,and the materials from soft to hard.The development of new products,new materials and new processes put forward higher requirements for the forming accuracy and load capacity of fine-blanking equipment.Fine-blanking presses(FBPs)are specialized presses used for fine-blanking process,and they can be devided into mechanically-driven and hydraulically-driven according to the main driven system.Traditional mechanical FBPs are rarely used in nowadays because their blanking capacity is low and cannot process large and complex parts.Hydraulic FBPs have the following advantages: stable blanking force,adjustable slider motion,easy for automation and heavy-load capacity etc.Therefore,hydraulic FBPs are more and more widely used.At present,FBPs below 10,000 k N have been widely used in China.However,regarding the FBPs over 10,000 k N,there is still a gap with the international advanced level.Therefore,the research and development of heavy-load hydraulic FBP is of great significance to the development of fine-blanking and high-end equipment in China.In this research,basic research of heavy-load hydraulic FBP were carried out focusing on the two key technical problems of precision and energy consumption.The main contents of this paper are as follows:(1)Based on the working requirements of fine-blanking processes to FBP,the mechanical-electrical-hydraulic system of heavy-load hydraulic FBP was desined,and a 12,000 k N hydraulic FBP prototype was made.The mechanical motion system and hydraulic control system were analyzed comprehensively.The kinematic model of the slider motion was established,based on which the motion characteristics of the slider were qualitatively analyzed.(2)An improved finite element analysis model of the FBP frame was proposed,based on which the strength,stiffness and dynamic characteristics of the frame were analyzed.A two-stage topology optimization procedure of the frame structure was proposed based on SIMP method,based on which the frame weight was reduced by13.66% with improvement of comprehensive mechanical properties.The effect of the material distribution on the mechanical properties of the frame was investigated.(3)The power bond graph models of key components were derived.Based on the Simcenter Amesim platform,the mechanical-electric-hydraulic integration simulation model of the heavy-load hydraulic FBP was established,whose accuracy was verified by experiments.The force and motion responses of the system were analyzed comprehensively and quantitatively.(4)To cope with low energy efficiency,the energy dissipation law of the heavyload hydraulic FBP was analyzed,and the energy comsumption of the mechanicalhydraulic system was revealed quantitatively.The key components and main reasons of high energy dissipation were pointed out.Modified hydraulic systems for highpressure and medium-pressure circuits were proposed,respectively.Simulation results showed that the energy dissipation of the modified system was reduced by 23.85%,and the energy efficiency was increased from 17.86% to 23.44%.(5)Aiming at the problem of poor accuracy of open-loop control,a piecewise PID closed-loop servo control strategy was propsed based on the characteristcs of hydraulic system and slider motion,and fuzzy adaptive PID control was adopted in the blanking stage.A fuzzy controller model was built in Matlab/Simulink,and co-simulation results showed that the proposed closed-loop control method have good transient and steadystate response characteristics.The research of this paper can provide theoretical basis and technical support for the development of heavy-load hydraulic FBP. |
PDF Full Text Request