| As an important part of wind turbine,wind turbine blade need to be ground during production and later maintenance.At present,surface of wind turbine blade is mainly ground by hand.There are many shortcomings in manual grinding,not only is it difficult to ensure the consistency of surface grinding quality,but also the grinding dust seriously affects the health of workers.With the development of science and technology,robotic automatic grinding of wind turbine blade has become a development trend.Wind turbine blade is large curved component and mainly composed of composite materials such as GFRP.The grinding temperature of GFRP composites is relatively low,and the higher grinding temperature can easily cause the surface material to soften or burn,which in turn affects the quality and efficiency of grinding.In view of the above problems,the purpose of this paper is to study the variation law of grinding temperature of robot grinding wind turbine blade.The normal grinding force distribution of the curved surface grinding contact area has a direct effect on the heat flux density at any grinding point.Therefore,the grinding force of robot grinding large curved surface was analyzed.The grinding depth of the curved surface grinding contact area is non-uniformly distribution,and is related to the normal grinding force and the grinding process parameters.This paper simplified the freeform surface of wind turbine blade,and assumed the normal grinding force distribution function according to the change of the grinding depth in the contact area of the simplified surface.By analyzing the material removal mechanism of cup wheel grinding curved surface,the maximum grinding depth was obtained by integrating the grinding depth,and then the normal grinding force distribution was determined.The normal grinding force at any grinding point in the grinding contact area was integrated to obtain the total normal grinding force,and the relationship between the total normal grinding force and the maximum grinding depth was established.The distribution of normal grinding force and total normal grinding force under different grinding process parameters were calculated by MATLAB.Based on the normal grinding force distribution of the robot's circumferential grinding and axial grinding,the heat source model for cup wheel grinding curved surface was established.In addition,the influence of the grinding depth at any grinding point on the heat flux density of the grinding chips was analyzed,and the heat flux density distribution relationship of the cup wheel grinding curved surface was established based on the traditional grinding heat distribution proportion model.The heat flux distribution of the heat source model was calculated by MATLAB,and the corresponding grinding temperature field was simulated by finite element method to obtain the temperature field distribution under different grinding process parameters.The grinding force model and temperature field were verified by the wind turbine blade grinding platform.The results indicate that the numerical calculation results of the grinding force model agree well with the experimental results and the relative error is less than 8.5%.The grinding temperature distribution of simulation and experiment is basically consistent,and the relative error of the maximum grinding temperature is less than 6%.The maximum grinding temperature of circumferential grinding appears on the cut-out side of the cup wheel,and the maximum grinding temperature of axial grinding appears in the middle position.The maximum grinding temperature respectively increases as increasing the wheel speed,feed rate and maximum grinding depth,and feed rate is the biggest influence factor on the grinding temperature.The research results reveal the variation law between the curved surface grinding parameters and grinding temperature of curved surface grinding,which provides reference and basis for the prediction of grinding temperature of the wind turbine blade ground by robot. |
PDF Full Text Request