| Pressing machine is a kind of hydraulic press, mainly used in the vulcanization of rubberconveyer belt, a single-layer hot press of the wood particleboard, compression molding of therubber molded products, multilayer hot press of the wood plywood, and so on. With the rapiddevelopment of society, the demand of foamed floor rubber, insulation materials, divingclothing materials and life jacket materials are also increasing, for the production of suchproducts, all kinds of equipments appear in succession,13.5MN foamed rubber hydraulicpress is one of them. The hydraulic press requires a large flow relief-valve to unload theworking cylinder pressure in0.15seconds, and then ask the oil of working cylinder to flowback into the fuel tank through the electromagnetic reversing cartridge valve quickly, so thefoaming and demoulding of products are completed in this process. Finally, the plunger speedmust be controlled at the stroke terminal of the plunger to prevent the plunger from a bigimpact on the bottom.This paper chose13.5MN foamed rubber hydraulic machine to study. The range ofsystem speed is relatively large, so using the opening of cartridge valve to adjust system speed,and then the spool position control strategy of electro-hydraulic proportional cartridge valve isputted forward.Fist of all, the simulation model is established by Matlab/Simulink depending on themathematical model of cartridge valves, and then the spool displacement step response curveof cartridge valve is concluded, response time is about0.25s and the overshoot is about5.6%.Second, the speed calculation formula of hydraulic press at no-load downlink is derived, andthen according to the parameters of13.5MN foamed rubber hydraulic press, the descendingspeed of moving beam during practical production of the hydraulic press is calculated. Thesimulation model of speed control system of moving beam is established by Matlab/Simulink,the speed step response simulation curve of moving beam under the cartridge valve withdifferent opening degree is concluded and dynamic response characteristics and influencingfactors of the moving beam speed is analyzed. When the opening of main spool is36mm, thereturn speed of the response time is about0.25s, the overshoot is about2.99%. Finally, thispaper deals with simulation analysis of the preliminary design of the throttle buffer system by Matlab/Simulink, founding that the system has larger vibration and noise problem, in order toreduce the vibration and noise, this paper puts forward the accumulator throttling buffersolution. Using accumulator throttling damping system, hydraulic oscillation frequency issignificantly reduced, and Bottom pressure tends to balance in0.017s, buffer effect has beendramatically improved than the throttling damping system. Proved the use of the accumulatorbuffer damping system, the system can effectively reduce the vibration and noise. |
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