Research On Novel Electro-hydraulic Vibration Exciter Based On Concrete Block Forming Machine

As a kind of new building material,concrete block is environmentally harmless,energy-efficient and high-quality.It has been gradually taken the place of solid clay brick,and has a wide market prospect.The concrete block forming machine is the main equipment to produce the concrete blocks,and its working performance directly affects the forming efficiency and forming quality.The forming machine also has influence on product diversity of the concrete block.Excitation technique is the key technology of compacting forming of the concrete block and decides the forming quality.At present,mechanical vibration exciters are often applied to the block forming machine,but as the limit of its operating principle,the upper frequency is low and the waveform distortion is high.In addition,the mechanical exciters cannot control vibration frequency.The traditional electro-hydraulic vibration exciters are also applied to some kind of block forming machine.However,the servo valve,which is used in traditional electro-hydraulic vibration exciters,is a kind of the slide valve.So as the limit of its structure,the frequency width is narrow and the structure of the whole system is very complex.Furthermore,the cost of the servo valve is expensive.Based on the above,in this paper,a new electro-hydraulic vibration exciters with high frequency based on rotary high speed reversing valve is proposed,and its characteristics are analyzed comprehensively.Firstly,for the vibration system of the block forming machine,the principle of compacting molding is analyzed and a kind of new electro-hydraulic vibration exciters is designed.The mathematical model of the vibration system is developed based on the principle and feature of the device.Moreover,based on the target equipment,the key vibration parameters are given taking the design rules into consideration.Then,a new rotary high speed four-way reversing valve is designed based on new electro-hydraulic vibration exciter.According to its own characteristics,the changing of open area formed by axial channel of the left spool and the middle is analyzed.In addition,Based on the vibration parameters of the concrete block forming machine,the structure parameters of the excitation cylinder is calculated.What’s more,The key sizes of the valve are given taking thedesign rules into consideration.Meanwhile,the hydrodynamic force acted on valve and the friction resistance between spool and valve body are analyzed,and the key sizes are given.The related parts of the reversing valve are designed and chosen,and the prototype is developed.In addition,the flow characteristics on static and dynamic condition and the cavitation phenomenon are studied combined with Computational Fluid Dynamics.The three-dimensional fluid mode of the reversing valve is calculated,the pressure and velocity distribution rules are obtained under different rotation angle.Based on the rotation angle,the characteristics of the pressure and velocity distribution under dynamic condition is analyzed compared to the characteristics under static condition.The law of the cavitation generation and collapse in channel is analysed,and the influence of the cavitation on the stability of the reversing valve is also researched.Finally,the static and dynamic characteristics of the vibration system of the block forming machine based on new electro-hydraulic vibration exciter are researched.The static pressure-flow curve of the rotary valve are analyzed and the influence of different channel type on characteristic curve is studied.The experimental test platform is set up to analyze the characteristic flow curve of the rotary valve under static pressure,and it is also verified by the developed numerical calculation.The simulation model of the vibration system is set up in Simulink based on force equilibrium equation,flow continuity equation of excitation cylinder and flow equation of the valve.What’s more,the dynamic features of the designed system are researched,which includes the influence of rotary frequency and spool structure parameters on vibration system performance.The innovative point of this paper is considering the characteristics based on the compacting forming technology of the concrete block and high speed vibration,a new electro-hydraulic vibration exciter of the concrete block forming machine controlled by rotary high speed reversing valve is developed,which has simple structure,high frequency response and strong anti-pollution ability.This new device is helpful to promote the forming efficiency,forming quality and variety diversity.It could also accommodate development requirements of the concrete block forming machine.