Model for calculating the current dimensions of the processed surface when grinding a non-circular workpiece in a circular plunge grinding cycle with CNC

At the moment, among a large number of different CAM-systems, there is no digital tool of control of designed control programs for CNC machines, which allows checking the possibility of ensuring the accuracy and roughness of the processed surface in the production of a batch of parts. As a result, CP designed with the help of CAD/CAM-systems require a procedure for their verification in real production conditions by processing a number of test parts. Despite all the accuracy of the positioning systems, modern CNC grinding machines, which allow performing processing according to the specified cycles of the cutting modes, have elastic deformations of the technological system. They have a significant impact on the fluctuations of the value of the removed allowance and on the formation of sizes errors in the production of a batch of parts. Processing of a batch of parts is performed under variable technological conditions. Approximately 90% of the processing error is due to the fluctuation of the part radius caused by the initial radial runout of the workpiece and the allowance fluctuation. This makes it necessary to establish a functional interrelation between the fluctuations of the sizes of the workpiece processed surface with the input, output and control parameters of the cycle, considering the allowance fluctuation and the initial radial runout of the workpiece throughout the entire processing process. This article describes a model for calculating the current dimensions of the processed surface when grinding a non-circular workpiece in a circular plunge grinding cycle with CNC. The model allows calculating changes in the actual radial feed on each radius of the processed surface on each revolution of the workpiece during the entire grinding cycle, considering the initial radial runout of the workpiece. This makes it possible to calculate the changes in the current sizes of the processed surface throughout the entire cycle, considering the “hereditary shape” of the workpiece. This model can be used not only to predict the accuracy of the diametrical dimensions and the deviation and location of the surface shape, but also to optimize the cycles of circular plunge grinding.