Study And Working Model Structure Of Isobaric And Floating Pressure Of Pneumatic In Laminated Continual Hot Press With

In terms of current existing problems of heated non-simultaneously,discontinuous production during lamination process,and learning from operating principle of continuous hot press for wood-based panel.This paper indicates a working model structure of double steel belts laminated continual hot press with Isobaric and floating pressure of pneumatic.The construction of laminated continual hot press with isobaric and floating pressure of pneumatic is a sealed isobaric chamber which is composed by steel belt covered on the top of press plate and pressed by hot compressed air,lining plates combined with press plate surface,Poly Tetra Fluoroethylene(PTFE)sealing strips surrounding the four sides of lining plates and press plate with fixed interval.The operation of steel belt is supported by hot compressed air with higher pressure within this chamber which is composed by steel belt and lining plates of hot plate and sealed by sealing strips inlaid inside of lining plates.The transmission of heat and pressure is relied on the sealed chamber filled with compressed air and composed by steel belt and lining plates,that is to say the mode of mixed by solid and gas on the contact surface.Thereby the heating and pressure effect on the surface of board via steel belt.In order to guarantee precision of pressure from press plate to steel belt the hydraulic system of pressure and displacement synchronous controller via computer is designed.The operation speed of steel belt is calculated according to lamination process about1.7m/min.-10.2m/min.The elongtation of steel belt is 25.6mm under heated,tension and isobaric pressure.The automatic tension and compensation equipment is necessary for steel belt.The consumption of compressed air is 45L/min.and 41L/min.In addition,a compressed air supply system with isobaric pressure under frequency converting control is designed.Experimental study indicates that the static friction coefficient between PTFE and steel is 0.103 under the normal temperature,but the dynamic friction coefficient is zero.The static friction coefficient between PTFE and steel will decrease with the higher temperature at first,but it will increase later,the dynamic friction coefficient keep increasing trend.The test results from the experimental isobaric and floating hot press indicate that the speed of temperature increasing of steel belt surface,simulated press plate,electric heating plate is slow in sequence.Furthermore the results are shown that the construction of laminated continual hot press with isobaric and floating pressure of pneumatic could meet the requirements of transmission heat,the surface temperature of steel belt could be reach or more than 100?.The leakage of compressed air will decrease and speed of temperature increasing of steel belt surface is fast after the simulated chamber is filled with compressed air.The leakage amount of compressed air will decrease with working pressure of cylinder increasing under the isobaric pressure in Chamber.Whereas the leakage amount of compressed air will increase with the pressure of compressed air increasing under the isobaric pressure of cylinder.The mass loss of PTFE is 1.35 g after friction 100 thousands times with steel belt.The calculation result of the model of thermal-structural coupling in finite element method of steel belt and press plate demonstrates that the extensibility of lengthwise direction is 0.23% when steel belt is tensioned,surface pressed and temperature 180?.Under the normal condition the Max.stress is53.5MPa and it concentrates at the round chamfer,meanwhile the Max.deformation is 0.79 mm and it happens at mid of frame beam.The calculation result of model of the infeed value of compressed air in the sealed chamber and the thickness of compressed air and working pressure indicates that the working pressure in chamber is proportional to the infeed value of compressed air and it is inversely proportional to the speed of steel belt and thicker of compressed air.The calculation result of finite element method shows that the thickerness of compressed between steel belt and press plate could reach 0.1mm whether the pressure of compressed air is more 166.25 Pa than pressure of steel belt transferring to work piece.