Toolpath Planning Methods For Glass Sharp Corner Edge Grinding

Personalized glass products with sharp corners are widely used in the building,household furniture,automobile and other industrial fields.Grinding is the main procedure to acquire a piece of glass with sharp corners.Due to the fragility of glass and sudden change of wheel velocity produced by a sharp corner,sharp corner grinding becomes extremely difficult.Conventional transition toolpath can not be used in the glass grinding directly.It is necessary to conduct theoretical and experimental research on sharp corner glass grinding method.This study is funded by The National Natural Science Foundation of China(Grant No.51405445)and investigates the transition toolpath for glass sharp corners.On the basis of requirements of high-precision grinding,two different transition toolpath planning methods are proposed based on bi-arc spline curve and NURBS curve respectively.Glass with sharp corners is ground precisely and the human-machine interface software is designed.Firstly,studying the characteristic of glass and diamond wheels as well as the microscopic grinding process,the relationship among grinding depth,grinding force and transitional speed is discussed.The 3 requirements of high-precision grinding are proposed(hereafter called the requirements).Secondly,considering the charateristic of bi-arc curve and the requirements,two symmetrical segments of C type bi-arc spline curve are used to design the transition toolpath scheme.The expression is solved through geometric method and vector rotation method respectively.Besides,corner angle calculation method and corner classification method are proposed.The test results verify the effectiveness of the proposed algorithm in this part.Then,taking the charateristic of NURBS curve and the requirements all into account,a conic NURBS curve is used to design the transition toolpath algorithm.The expression is worked out through acceleration/deceleration distance constraints and grinding depth control equation.After confirming the application process,a piece of hexagram glass is ground.The effectiveness of the algorithm in this part has been proved.Lastly,based on the glass grinding maching production line,the function of the control system is analysed,after planning the details of each fucntion module,the human-machine interface software is designed.This article studys sharp corner glass grinding theory and proposes two transition toolpath planning methods based on bi-arc spline curve and NURBS curve respectively.The test results prove that the methods can all achieve high-precision sharp corner grinding.