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Three major factors and countermeasures affecting the machining accuracy of CNC machine tools

Time:2021-07-06 Views:216


Numerical control machine tools will inevitably be affected by various factors in the processing process, which will cause certain deviations in their processing accuracy and bring some inconvenience to production and life.

1 Precision problems in CNC machine tool processing

(1) The influence of position error in CNC machining on machining accuracy

Position error refers to the amount of change or deviation between the actual surface, axis, or symmetry plane of the processed part relative to its ideal position, such as perpendicularity, position, symmetry, etc. The position error in CNC machine tool processing usually refers to the dead zone error. The cause of the position error is mainly due to the gap and elastic deformation generated during the transmission of the machine tool parts during the processing of the machine tool, and the tool head of the machine tool needs to overcome the friction force during processing. Factors such as lead to position error. 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 the effect is generally small.

(2) Machining accuracy errors caused by geometric errors in CNC machine tool processing

In CNC machine tool processing, the geometric accuracy of the machine tool is affected due to the influence of external forces and heat generated by the tool and fixture under the influence of external factors such as the heat generated in the process, and the parts processed on the machine tool are geometrically deformed, which leads to geometric errors. According to research, the main reasons for the geometric errors of CNC machine tools are nothing more than the following two: internal factors and external factors. The internal factors of the machine tool's geometric errors refer to the geometric errors caused by the machine's own factors, such as the levelness of the machine table, the levelness and straightness of the machine tool rails, and the geometric accuracy of the machine tools and fixtures. External factors mainly refer to the geometric errors generated under the influence of factors such as the external environment and thermal deformation during processing. For example, during the cutting process of tools or parts, due to thermal expansion and deformation, geometric errors occur, which affect the processing of machine tools. Precision and machining precision of parts.

(3) Machining accuracy errors caused by machine tool positioning in CNC machine tool processing

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 machine tools. From the structural point of view, the machining errors of CNC machine tools are mostly caused by positioning accuracy. Among them, the feed system of the machine tool is the main link that affects the positioning accuracy. The feed system of a CNC machine tool usually consists of two parts: a mechanical transmission system and an electrical control system. The positioning accuracy is related to the mechanical transmission system in the structural design. In the closed-loop system, the CNC machine tool can usually prevent the position deviation of the main components in the feed system, such as the ball screw and other components, through the positioning detection device. As for the open-loop system, due to many influencing factors and complicated conditions, positioning monitoring cannot be carried out, so it has a greater impact on the machining accuracy of CNC machine tools.


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