Research On Key Techniques Of High-efficient Energy-saving Large-scale Die Casting Machine

Die casting is one of advanced manufacturing techniques that enables component to beformed in one piece for specific materials. The casting machine is the fundamental equipmentof pressure die casting. It is sophisticated with high technique and involves mechanical,electrical and fluid flow dynamic properties. There is a wide gap between China anddeveloped countries in the design method, manufacture technique, work efficiency, energyconsumption and reliability of die casting equipment especially in large scale.Since the die casting equipment developed in the country is far behind advanced, a25000kN large scale die casting machine has been studied. The project is in combination ofnational intelligent manufacture equipment development project in ‘high efficiency diecasting island system’ and breakthrough project in key area in Canton and Hong Kong. Thereport is focus on crucial technique that could provide higher work efficiency and lowerenergy consumption using numerical simulation. Final model has been developed based ontheoretical, numerical and laboratorial research have been done in dynamic properties such askinematic simulation of mould clamping device, design optimization, mechanical strengthanalysis of complete machinery, modal of the machinery, impact respond, heat and thermalconduction structural coupling, lightweight design for main structural components and controlsystem for crucial techniques of energy consumption reduction.Double-toggle clamping device in the die casting machine based on kinematic modellinghas been researched and optimised designed. System kinematic and dynamic properties of thejoint-double clamping device have been analysed and a mathematic model has been set up.Relations between coefficient of expanding force, distance of the dies movement andgeometries are derived and practical variables and constraints have been determined in thefunction with stroke ratio and coefficient of expanding force. By analysing the kinematic anddynamic property of joint-double, five-hinge-joint, inclined-array clamping device withADAMS and optimising the design, the coefficient of expanding force is increased by24.6%from18.93to23.59, matching the world leading level and results in growing locking force from25.89MN to32.27MN.The25000kN clamping force can be provided using low power hydraulic motor andvalve in the hydraulic system with less pressure and time. Working efficiency and energyconsumption are therefore improved. The driving base plate has reduced its stroke by26.3%which lessen the impact and oscillation during clamping. It also enhances the quality andperformance of the die casting machine.Die casting machinery strength has been researched based upon multi-body dynamicanalysis. The curves of velocity, acceleration and load property of the key components withinthe die casting machine against time have been derived. Result showed that by modellingflexible body system similar kinematic and dynamic properties with the one in reality can besimulated. Strength of the25000kN die casting machine has been analysed and modifiedbased on flexible body kinematic study as well as that of the clamping device using CAEsoftware. Results showed significantly that the flexible body analysis had given validoutcomes.Dynamic property analysis of the whole machine has been studied. ImprovedCraig-Bampton method has been used to calculate the constraint model of the25000kN diecasting clamping device assembly with large amount of highly non-linear contact pair.However, finite element method can hardly solve it. Resonant frequency in the first20phaseswith corresponding formations heaved also been obtained. Degree of sensitivity of theassembly responds to the vibration excitation and the weakness of vibration resistance havebeen identified to prevent resonance. It also gives evidence to improve design andmanufacture of die casting. According to the shock respond analysis of the clamping device,the main impact effcts are on the driving base plate, long hinge, hock hinge, fixed plate andthe Gelin Columns. By analysing thermal field and thermal structural coupling properties ofthe casting plates and the mould system with ‘thermal shock’ loading and mechanical loading,the maximum pressures applied to driving base plate and the fixed plate have been set to254.1MPa and181.6MPa, respectively. Work conditions of every assembly under theseconditions are acceptable. However optimization should be done to the driving base plate and should lighten the fixed plate and the transom plate.Crucial assemblies have been lightweight designed for the die casting machine.Topological and geometrical optimizations for continuum structure have been used tooptimise the crucial assemblies of the die casting machine such as fixed plate, transom plate,driving base plate and the base. The percentage of the bound volume and the penalty factor ontopological optimization are significant therefore they are determined to be0.7and3,respectively. Result after optimizations showed that total weight of the mould plates and thebase has reduced from91.10tons to79.75tons. With a12.5%drop in weight of the wholemachine and6.4%drop in weight of moving parts. Therefore, the work load of the hydraulicdriving system has reduced dramatically. As result the working efficiency of the wholemachine can be improved and energy consumption can be lowered.Key technique on energy saving for the die casting machine control system has beenstudied. A technique of using variable frequency control with real time monitor embedded tosave energy has been purposed. Above the hardware and software in the control system,non-inductive vector close-loop torque control technique, specific double DSP energyefficient system CPU together with specific die casting software have been introduced. Theelectricity cost during the small discharge in periodic manufacturing has been dramaticallydecreased.41%of the electricity cost can be saved using this technique and25%~35%ofelectricity can be saved when comparing with normal die casting machine. Thus the goal oftechnical innovation and energy saving can be achieved. This technique can be introduced tothe analysis of energy saving for periodical variable loading operation devices and can beused broadly in the future.