The accuracy of CNC machine tools directly determines the yield of processing. High-precision machine tools play a vital role in reducing defective products and reducing the loss of production materials. The accuracy of machine tools is an important indicator for measuring machine tool performance. Then there are many factors that affect the accuracy of CNC machine tools. The accuracy of the machine tool itself is a major factor. Which factors determine the accuracy of CNC vertical machining centers?
1. Precision problems in CNC machining center processing 加工
1.1 The effect of position error on machining accuracy
Position error refers to the amount of variation or deviation of the mutual position between the actual surface, axis, or plane of symmetry of the part relative to its ideal position after processing, such as perpendicularity, position, and symmetry. The main causes of position errors in machining centers are machining errors caused by clearance and elastic deformation during transmission during part processing, and position errors caused by factors such as friction of the machine tool bit during machining. In the open-loop system, the position accuracy is greatly affected, while in the closed-loop follow-up system, it mainly depends on the accuracy of the displacement detection device and the speed amplification factor of the system, and generally has a small impact.
1.2 Errors in machining accuracy caused by geometric errors
In the machining of the machining center, due to the influence of external factors such as external forces and heat generated during machining, the geometric accuracy of the machine tool is affected, and the parts processed on the machine tool are deformed geometrically, resulting in geometric errors. According to research, the main causes of geometric errors are the following two: internal factors and external factors. The internal factors that the machine tool produces geometric errors refer to the geometric errors caused by the machine tool itself, such as the level of the machine table, the level and straightness of the machine guide rails, and the geometric accuracy of the tool and fixture of the machine. External factors mainly refer to the geometric errors caused by the external environment and thermal deformation during processing. For example, during the cutting process, due to thermal expansion and deformation of the tool or component, geometric errors occur, affecting the machining center. Machining accuracy and machining accuracy of parts.
1.3 Machining accuracy error caused by machine positioning
Through long-term data analysis and practical operation of parts processing, it can be seen that machine tool positioning has a greater impact on the machining accuracy of CNC machining centers. From the structural point of view, the machining errors of machining centers are mostly caused by positioning accuracy, and the feed system of the machine tool is the main link that affects the positioning accuracy. The feed system of a machining center usually consists of a mechanical transmission system and an electrical control system. The positioning accuracy is related to the mechanical transmission system in the structural design.
2. Effective methods to improve machining accuracy
During the machining process of the CNC machining center, the accuracy of the parts processed directly affects the quality of the product. Some mechanical parts and precision equipment parts have very high requirements for the machining accuracy. Improving the machining accuracy of the machining center is the solution. The key to the problem. It can be concluded through extensive research and analysis that there are several methods to improve the machining accuracy of machining centers:
2.1 Can improve the machining accuracy by controlling the original error of the machining center
During the machining process of the machining center, the error itself is unavoidable. There must be an error between the machined part and the machining center. This must be called the original error.
To improve the machining accuracy, controlling the original error of the machining center is one of the important methods. A systematic analysis is required for the possibility of the original error, and corresponding improvement measures shall be formulated according to the cause and type of the error. During the machining of mechanical parts, the position accuracy and geometric accuracy of the machining center have an important influence on the machining accuracy of the parts. Position control and geometric accuracy control should be used to reduce the impact of position errors and geometric errors on the parts. For deformation errors generated during processing, it is necessary to use air cooling, water cooling, and other methods to control the thermal deformation during processing, and reduce the impact of processing accuracy caused by thermal deformation errors. At the same time, for the position error, it is necessary to reasonably choose a tool suitable for the material of the part to avoid tool deformation. At the same time, choose a reasonable fixture according to the shape of the blank of the processed part. Position error.