Optimization Of The Hydraulic System Of High-speed Punching Machine And Its Influence On The Quality Of The Sheared Surface Of Steel Plates

With the development of the machinery manufacturing industry,presses are widely used in electronics,aerospace,electric motors,automobiles,etc.The presses have also evolved step by step from huge mechanical presses to the current compact,high-precision servo presses.At the same time,however,a number of problems with punching machines have constrained the development of punching machines.High-speed punching machines have a large stroke volume and the vibrations during operation become more pronounced,and the magnitude of pressure changes in the hydraulic cylinder also affects the quality of the cross-section of the blanked part.In order to address the effects of excessive pressure variations,the hydraulic system of the high-speed punching machine is optimized in order to effectively reduce the pressure variations of the hydraulic cylinders and improve the quality of the punching machine when cutting steel plates.This paper takes a conventional high speed punching machine hydraulic system as the object of study.The aim is to design a high-speed hydraulic press with smooth operation,low pressure variation and good cross-sectional properties for cutting steel plates.The accumulator is based on its ability to reduce pressure shocks and to respond quickly.Firstly,a comparison is made between the pressure variation of a hydraulic cylinder with a rod chamber connected to an accumulator and a low-pressure oil connection.A hydraulic system for high-speed punching machines is proposed to reduce the pressure variation in the rod chamber of the hydraulic cylinder by means of an accumulator.Secondly,a simulation of the hydraulic system with two different return methods is carried out for plate blanking.The effect of the accumulator returning and the low-pressure oil return on the quality of the sheared surface of the punched plate is analyzed.Finally,the effect of the two hydraulic systems with accumulator return and low-pressure oil return on the sheared surface of the plates is verified through tests.(1)Based on the characteristics of the accumulator that can reduce pressure shock and can respond quickly.The pressure variation of the hydraulic cylinder is compared and analyzed by AMESim dynamic simulation software in two ways: with an accumulator connected to the rod chamber of the hydraulic cylinder and with low pressure oil.Based on the simulation results,the hydraulic system of a conventional punch press is optimized.A hydraulic system for high-speed presses is proposed which reduces the pressure variation in the rod chamber of the hydraulic cylinder by means of an accumulator.(2)Simulation analysis of the effect of pressure variation in the hydraulic system of a punch press on the quality of steel plate blanking.The model of the punching machine was constructed using the 3D software Solid Works and then imported into the LS-DYNA display dynamics module.The pressure variation of the hydraulic cylinder with accumulator and low-pressure oil return from the AMESim simulation was also imported into LS-DYNA for simulation analysis.The effect of the proposed hydraulic system with accumulator return and the conventional hydraulic system with low-pressure oil return on the quality of the punching process is analyzed.(3)Experimental verification of the effect of pressure variation of the hydraulic system of the punching machine on the quality of the steel plate punching and cutting.Construction of a test rig.Verify the proposed use of the accumulator return hydraulic system versus the conventional hydraulic system,the impact on the quality of the steel plate shear surface.And to verify the hydraulic cylinder pressure variation of the hydraulic system for the two different return methods.The simulation results show that the proposed hydraulic system with a hydraulic cylinder rod chamber connected to an accumulator has less pressure variation in the hydraulic cylinder rod chamber when punching different thicknesses of steel plates than the conventional low-pressure oil return method,and can guarantee the stability of the hydraulic cylinder downstream.The results of the plate blanking simulation show that the hydraulic system with a rod chamber connected to an accumulator result in smaller rounded corners,wider bright zones,fewer burrs and less stress concentration on the sheared surface of the punched steel plate than the conventional low pressure oil return method.The test results validate the results of the system simulation and the plate blanking simulation and show the effectiveness of the hydraulic system of the punching machine with accumulator return.