Influence of Position Error on Machining Accuracy in NC Machine Tool

Release time:

2023-12-11 09:02

1 The influence of position error in CNC machine tool processing on the machining accuracy
Position error refers to the actual surface of the parts after processing, axis or symmetry plane between the mutual position relative to its ideal position of the amount of variation or deviation, such as perpendicularity, position, symmetry, etc. The position error in CNC machine tool processing usually refers to the dead zone error. The main reason for the position error is the machining error caused by the gap and elastic deformation generated during the machining of machine tool parts, and in the machining process, the cutter head of the machine tool needs to overcome the friction and other factors lead to the position error. In the open-loop system, the position accuracy is greatly affected, while in the closed-loop servo system, it mainly depends on the accuracy of the displacement detection device and the speed amplification coefficient of the system, and the influence is generally small.
2 Machining accuracy errors due to geometric errors in CNC machining
In the processing of CNC machine tools, due to the influence of external factors such as external forces and heat generated in the processing of tools and fixtures, the geometric accuracy of the machine tool is affected, and the parts processed on the machine tool produce geometric deformation, which leads to geometric errors. According to research, the main reason for the geometric error of CNC machine tools is nothing more than the following two: internal factors and external factors. The internal factors that produce geometric errors in the machine tool refer to the geometric errors caused by the factors of the machine tool itself, such as the levelness of the worktable of the machine tool, the levelness and straightness of the machine tool guide rail, the geometric accuracy of the machine tool and fixture, etc. External factors mainly refer to the geometric errors generated under the influence of external environment and thermal deformation in the process of machining. For example, the tool or parts in the cutting process, due to thermal expansion and deformation, resulting in geometric errors, affecting the machining accuracy of the machine tool and the machining accuracy of the parts.
3 CNC machine tool machining due to the positioning of the machining accuracy error
Through long-term data analysis and practical operation of parts processing, it can be seen that machine tool positioning has a great influence on the machining accuracy of CNC machine tools. The machining error of CNC machine tools, from the structural point of view, is mostly caused by the positioning accuracy, in which the feed system of the machine tool is the main link that affects the positioning accuracy. The feed system of CNC machine tools is usually composed of mechanical transmission system and electrical control system. The positioning accuracy is related to the mechanical transmission system in the structural design. In the closed-loop system, CNC machine tools can usually prevent the main components in the feed system from position deviation, such as ball screws and other components. For the open-loop system, due to more influencing factors, the situation is more complex, can not be positioning monitoring, so the machining accuracy of CNC machine tools has a greater impact.