Research on tool presetting and tool deviation in CNC lead screw grinding process

In CNC lead screw grinding, grinding allowance of screw groove is small. Tool deviation may lead to one side of the screw groove heavily grinded, while the other side of that not grinded or grinded not enough. Though the grinding wheel is right in the middle of the screw groove in the process of tool presetting for CNC lead screw grinding, tool deviation typically occurs in the subsequent grinding process. More specifically, the grinding wheel slightly deviates from the middle of the screw groove to the left or right of the screw groove. In this work, the cause of tool deviation is analyzed as follows: the mutual following error of Z-axis and A-axis due to the differences between the mechanical and electrical characteristics. A method and formulas to address the tool deviation are proposed: The coordinates of A-axis and Z-axis in the grinding process are measured and recorded by the CNC system; then, the value of tool deviation caused by the mutual following error of Z-axis and A-axis is calculated. As a result, the grinding start position and the grinding end position are adjusted according to the tool deviation in the subsequent grinding process, so as to address the tool deviation issue.