| Large-tonnage fine blanking press' s drive system generally uses hydraulic structure,it is mainly used in the production of material thicker,complex shape,high strength plate parts,and it has the advantages of high working pressure,high efficiency,high precision,low energy consumption,low noise,stable transmission,etc.But the large-tonnage fine blanking press has higher requirements on the mechanical structure design,hydraulic system design and the choice of key hydraulic components.Large-tonnage fine blanking press hydraulic system mainly includes fast cylinder hydraulic system,main cylinder hydraulic system,blank holder cylinder and back pressure cylinder hydraulic system.The fast cylinder hydraulic system in the fine blanking process to play the role of opening and shutting the mold fast,positioning quickly.The main cylinder hydraulic system provides blanking force.The whole system is working in the high pressure,high flow,high frequency of cyclic commutation conditions.Pressure fluctuations,hydraulic shock and control problems are very prominent.These problems may cause the pressure switch to send out the wrong signal,which affects the working stability and the reliability of the hydraulic system,and the malfunction make it difficult to guarantee the motion accuracy of the slider.Compared with the ordinary blanking process,the die gap of fine blanking process is smaller,and the positioning accuracy of the slider is more sensitive.Positioning error will cause the parts to produce tear zone and burr,even equipment failure,mold damage.Therefore,it is of great significance to improve the product quality and prolong the life of the mold by carrying out the design and simulation of the hydraulic system of the large-tonnage fine blanking press.This paper took the KHF1200 fine blanking press developed by Wuhan University of Technology and Huangshi Huali Forging Machine Corporation as research object.Firstly,this paper gives an overview of the working principle of the large-tonnage fine blanking machine.According to the hydraulic transmission principle,hydraulic system design technology,combined with the fine blanking process,a large-tonnage fine blanking hydraulic system was redesigned.And the hydraulic system parameters are calculated and the main hydraulic components are selected.Then,by using the hydraulic module in the AMESim software,the simulation model of the fast cylinder hydraulic system and the main cylinder hydraulic system were established,including a phased PID control method and an artificially simulated load module.And by simulating the simulation model above,the pressure and flow curve of the key hydraulic elements and the movement curve of the slider were obtained,and the influence of the main parameters of the key hydraulic components on the working characteristics of the fine blanking machine were analyzed.In particular,the design of the accumulator can save the system more than 50%.Finally,the pressure and displacement curve of the large-tonnage fine blanking machine were collected by carrying out the fine blanking test.Compared with the simulation results,it shows that the positioning error of the dead point on the slider is in 0.01 mm,and the delay error between the simulation displacement curve and the given displacement curve is in 0.02 s,and the simulation pressure fluctuates in a periodic fluctuation in the simulated pressure,the amplitude of the fluctuation is about 0.034 MPa.So the correctness of the design and calculation method and the reliability of the hydraulic simulation model were verified.Therefore,this paper provided technical guidance for the design and improvement of hydraulic system of large-tonnage fine blanking machine. |
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