Research On Position-pressure Control Of Hydraulic System Of Rolling Shear

As one of the important equipment for steel plate rolling in the production line,the rolling shear is now an indispensable core equipment in industrial As one of the important equipment of steel plate rolling in the production line,the rolling shears are the indispensable core equipment in the industrial production.As an essential equipment in rolling cutting and shearing,the precision of hydraulic system must be considered.Roller cutting shears in the shear process mainly depends on the left and right two hydraulic cylinders,the two hydraulic cylinders at different speeds,through the two hydraulic cylinders at different speeds to drive the connecting rod up and down,so as to form a suitable shear angle to shear the steel plate.Under high pressure and large flow,the shear track can not be accurately traced when the rolling shears cut the steel plate.The smaller cutting angle of the rolling shears will cause a sharp increase in the shear force.The steel plate shear will appear incomplete shear,poor shear quality,continuous steel shear,cavitation on the inner surface of the hydraulic cylinder and serious damage to the sealing ring.Faced with these problems,the main reason is that under the condition of high speed and large flow,the control valve of the hydraulic system is directly connected with the hydraulic cylinder,which will lead to the cavitation phenomenon of the valve port and produce a large amount of gas,which is caused by the oil entering the hydraulic cylinder.In view of the problems mentioned above,the distance between the valve port of the rolling shear hydraulic system and the gas dissolving in the hydraulic cylinder orifice was deeply studied.(1)Firstly,mathematical models of gas content,system pressure and pressure rising rate are established based on the effective volume modulus and initial gas content of hydraulic oil.(2)Then,according to the relationship between gas variation and solubility,the mathematical model between initial gas content and gas dissolution distance is established.Then the model was established for simulation analysis.The results show that the error of gas dissolution distance between the simulation analysis and the mathematical model is less than 10% under different gas content,so the optimal hole distance between the valve port and the hydraulic cylinder is obtained under different initial gas content.(3)For the improved hole distance on slitting shears the position-pressure hydraulic system control research,with force balance equation is established,load flow equation and elastic load.Through these equations displacement pressure of adaptive control algorithm is proposed,research the location of the roll cutting camber of cutting time,stress path changes.Then simulation and experiment,the displacement-pressure match gradually,the shear tracking trajectory has no mutation and the shear is stable.According to the high pressure,large flow conditions on the slitting shears hydraulic system between valve and hydraulic cylinder hole distance made improvement,do so for valve mouth after cavitation bubbles partly dissolved in oil,makes less of gas into the hydraulic cylinder,lest cause cavitation of the hydraulic cylinder wall,thus increasing the service life of hydraulic cylinder,at the same time ensure the sealing ring are not destroyed.In this way,the mixed gas in the hydraulic oil is reduced and the effective volume elastic modulus of the oil is improved,and the precision of the location-pressure tracking trajectory of the hydraulic system in work is improved,so as to improve the shear quality of the steel plate.